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Edzeamey FJ, Ramchunder Z, Valle Gómez A, Ge H, Marobbio CMT, Pourzand C, Virmouni SA. Therapeutic combination of L-ascorbic acid, N-acetylcysteine, and dimethyl fumarate in Friedreich's ataxia: insights from in vitro models. Redox Rep 2025; 30:2505303. [PMID: 40375363 DOI: 10.1080/13510002.2025.2505303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2025] Open
Abstract
Friedreich's Ataxia (FRDA) is a rare neurological disorder caused by an abnormal expansion of Guanine-Adenine-Adenine (GAA) repeat in intron 1 of the FXN gene, which encodes frataxin, leading to reduced expression of frataxin, a mitochondrial protein essential for cellular homeostasis. Frataxin deficiency results in oxidative stress and mitochondrial dysfunction and impaired redox balance. Currently, there is no cure for FRDA. This study aimed to evaluate the therapeutic potential of antioxidants dimethyl fumarate (DMF), N-acetylcysteine (NAC), and L-ascorbic acid (LAA) in restoring mitochondrial redox homeostasis and frataxin levels in FRDA patient-derived fibroblasts and 2D sensory neurons. We assessed cell viability, mitochondrial and cellular reactive oxygen species (ROS) levels, mitochondrial DNA copy number, mitochondrial membrane potential, and frataxin and NRF2 expression at both mRNA and protein levels following antioxidant treatment, either individually or in combination. Treatment with LAA, NAC, and DMF resulted in significant reductions in mitochondrial and cellular ROS, along with increased FXN and NRF2 expression, and enhanced NRF2 nuclear translocation. Furthermore, these compounds improved aconitase/citrate synthase activity, GSH/GSSG ratios, and mitochondrial membrane potential. Notably, the combination of LAA and NAC consistently alleviated multiple disease-associated defects in FRDA cells, suggesting its potential as a promising therapeutic approach.
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Affiliation(s)
- Fred Jonathan Edzeamey
- Division of Biosciences, College of Health, Medicine, and Life Sciences (CHMLS), Institute of Environment, Health & Societies, Brunel University London, London, UK
| | - Zenouska Ramchunder
- Division of Biosciences, College of Health, Medicine, and Life Sciences (CHMLS), Institute of Environment, Health & Societies, Brunel University London, London, UK
| | - Adamo Valle Gómez
- Energy Metabolism and Nutrition, Research Institute of Health Sciences (IUNICS), University of Balearic Islands, Palma, Spain
- Health Research Institute of Balearic Islands (IdISBa), Palma, Spain
- Biomedical Research Networking Center for Physiopathology of Obesity and Nutrition (CIBERobn CB06/03/0043), Instituto de Salud Carlos III, Madrid, Spain
| | - Haobo Ge
- Department of Life Sciences, University of Bath, Bath, UK
- Centre for Therapeutic Innovation, University of Bath, Bath, UK
- Centre for Bioengineering and Biomedical Technologies, University of Bath, Bath, UK
| | | | - Charareh Pourzand
- Department of Life Sciences, University of Bath, Bath, UK
- Centre for Therapeutic Innovation, University of Bath, Bath, UK
- Centre for Bioengineering and Biomedical Technologies, University of Bath, Bath, UK
| | - Sara Anjomani Virmouni
- Division of Biosciences, College of Health, Medicine, and Life Sciences (CHMLS), Institute of Environment, Health & Societies, Brunel University London, London, UK
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Salinas L, Figueroa F, Montgomery CB, Thai PN, Chiamvimonvat N, Cortopassi G, Dedkova EN. Omaveloxolone, But Not Dimethyl Fumarate, Improves Cardiac Function in Friedreich's Ataxia Mice With Severe Cardiomyopathy. J Am Heart Assoc 2025; 14:e038505. [PMID: 40501183 DOI: 10.1161/jaha.124.038505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2024] [Accepted: 03/24/2025] [Indexed: 06/19/2025]
Abstract
BACKGROUND Friedreich's ataxia (FA) is a genetic disorder caused by a severe decrease in FXN (frataxin) protein expression in mitochondria. The clinical manifestation of this disorder is a cerebellar ataxia; however, the common lethal component in FA is cardiomyopathy. METHODS A conditional Fxnflox/null::MCK-Cre knockout (FXN-cKO) mouse model was used to mimic the late-stage severe cardiomyopathy in FA. Nrf2 (nuclear factor erythroid 2-related factor 2) inducers, omaveloxolone and dimethyl fumarate (DMF), were independently tested in this mouse model to determine the effects on cardiac health and lifespan. RESULTS Omaveloxolone significantly improved cardiac contractile function and markers of heart failure in FA such as Nppb, Aldh1a3, and Gdf15. Despite improvement in cardiac function, omaveloxolone did not prevent premature death in FXN-cKO animals and notably accelerated death in FXN-cKO females. Omaveloxolone decreased oxidative stress and inflammatory marker IL1β (interleukin-1 beta), and stimulated Nqo1 gene expression above control level. DMF restored elevated HO-1 (Hmox) expression and significantly increased Sirt1 expression. Although both omaveloxolone and DMF restored decreased SERCA2 (Atp2a) and MCU (Mcu) expression and ameliorated elevated phosphorylation of CaMKIIδ at Thr286 site in FA hearts, DMF did not improve cardiac contractile function and survival. Furthermore, neither omaveloxolone or DMF decreased hypertrophy and fibrosis (Masson trichrome staining and Lgals3 expression) or rescued impaired mitochondrial function and integrative stress response in FXN-cKO hearts. CONCLUSIONS These data demonstrate that omaveloxolone significantly improved contractile function but not survival in FA hearts because cardiac fibrosis and wall stress persisted even with omaveloxolone treatment. More studies are warranted to determine the cause of premature death in omaveloxolone-treated FXN-cKO female mice.
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Affiliation(s)
- Lili Salinas
- Department of Molecular Biosciences University of California Davis CA USA
| | - Francisco Figueroa
- Department of Molecular Biosciences University of California Davis CA USA
| | | | - Phung N Thai
- Department of Internal Medicine, Cardiovascular Medicine University of California Davis CA USA
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Cardiovascular Medicine University of California Davis CA USA
- Department of Veterans Affairs Northern California Health Care System Mather CA USA
| | - Gino Cortopassi
- Department of Molecular Biosciences University of California Davis CA USA
| | - Elena N Dedkova
- Department of Molecular Biosciences University of California Davis CA USA
- Department of Basic Sciences California Northstate University Elk Grove CA USA
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Jimenez DA, Miller CJ, Walker A, Anupindi K, Hayward BE, Lorenzi HA, Usdin K, Zhao X. Reconciling the effects of PMS2 in different repeat expansion disease models supports a common therapeutic strategy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2025:2024.08.13.607839. [PMID: 39185211 PMCID: PMC11343130 DOI: 10.1101/2024.08.13.607839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Expansion of a disease-specific tandem repeat is responsible for >45 Repeat Expansion Diseases (REDs). The expansion mutation in each of these diseases has different pathological consequences and most are currently incurable. If the underlying mechanism of mutation is shared, a strategy that slows repeat expansion in one RED may be applicable to multiple REDs. However, the fact that PMS2, a component of the MutLα mismatch repair complex, promotes expansion in some models and protects against it in others, suggests that the expansion mechanisms may differ. We show here using mouse models of two REDs caused by different repeats that the seemingly paradoxical effects of PMS2 do not reflect different expansion mechanisms but rather cell-type and dosage effects in different tissues. This differential effect is recapitulated in mouse embryonic stem cells with inducible PMS2 expression: PMS2 promotes expansion at low concentrations, an effect that requires a functional nuclease domain; while at higher concentrations it protects against expansion. The apparent paradoxical behavior of PMS2 can be resolved in a model based on the different in vitro cleavage preferences of MutLα and MutLγ, another MutL complex known to be required for expansion. Our data thus resolve a longstanding puzzle and suggest a common mechanism responsible for REDs. Our data also provide proof of concept that increasing PMS2 levels suppresses repeat expansion not only in cells where its loss promotes expansion, but also in cells that require it for expansion, supporting its potential as a broadly applicable therapeutic strategy. Significance statement Collectively the Repeat Expansion Diseases (REDs) represent a significant health burden. Since the consequences of the expansion mutation differ across diseases, therapeutic approaches that block the underlying mutation are appealing, particularly if the mechanism is shared. However, the conflicting effects of PMS2 loss in different REDs models challenges this idea. Here we show using two different REDs models that these disparate effects can be reconciled into a single model of repeat expansion, thus increasing confidence that the REDs do all share a common mutational mechanism. Importantly, we show that elevating PMS2 levels suppresses repeat expansion in multiple cellular contexts, including those in which PMS2 is normally required for expansion, demonstrating its potential as a broadly applicable therapeutic strategy for REDs.
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Park J, Dufke C, Fleszar Z, Schlotterbek M, Buena-Atienza E, Stühn LG, Gross C, Sturm M, Ossowski S, Schöls L, Riess O, Haack TB. Long-Read Sequencing Identifies Mosaic Sequence Variations in Friedreich's Ataxia-GAA Repeats. Int J Mol Sci 2025; 26:4969. [PMID: 40507780 PMCID: PMC12154355 DOI: 10.3390/ijms26114969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2025] [Revised: 05/14/2025] [Accepted: 05/16/2025] [Indexed: 06/16/2025] Open
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disorder characterized by ataxia, sensory loss and pyramidal signs. While the majority of FRDA cases are caused by biallelic GAA trinucleotide repeat expansions in intron 1 of FXN, there is a subset of patients harboring a heterozygous pathogenic small variant compound-heterozygous with a GAA repeat expansion. We report on the diagnostic journey of a 21-year-old patient who was clinically suspected of having FRDA at the age of 12 years. Genetic testing included fragment analysis, gene panel analysis and exome sequencing, which only detected one pathogenic heterozygous missense variant (c.389 G>T,p.Gly130Val) in FXN. Although conventional repeat analyses failed to detect GAA expansions in our patient, subsequent short-read genome sequencing (GS) indicated a potential GAA repeat expansion. This finding was confirmed by long-read GS, which in addition revealed a complex pattern of interruptions. Both large and small GAA expansions with divergent interruptions containing G, A, GA, GAG and/or GAAG sequences were present within one allele, indicating mosaic sequence variations. Our findings underscore the complexity of repeat expansions which can exhibit both interruptions and somatic instability. We also highlight the utility of long-read GS in unraveling intricate genetic profiles, ultimately contributing to more accurate diagnoses in clinical practice.
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Affiliation(s)
- Joohyun Park
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
| | - Claudia Dufke
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
| | - Zofia Fleszar
- Department of Neurodegenerative Diseases, Center for Neurology and Hertie-Institute for Clinical Brain Research, University of Tübingen, 72076 Tübingen, Germany
| | - Michael Schlotterbek
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
- Department of Neurodegenerative Diseases, Center for Neurology and Hertie-Institute for Clinical Brain Research, University of Tübingen, 72076 Tübingen, Germany
| | - Elena Buena-Atienza
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
- NGS Competence Center Tübingen, 72076 Tübingen, Germany
| | - Lara G. Stühn
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
| | - Caspar Gross
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
| | - Marc Sturm
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
| | - Stephan Ossowski
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
- Center for Rare Diseases, University of Tübingen, 72076 Tübingen, Germany
| | - Ludger Schöls
- Department of Neurodegenerative Diseases, Center for Neurology and Hertie-Institute for Clinical Brain Research, University of Tübingen, 72076 Tübingen, Germany
- Center for Rare Diseases, University of Tübingen, 72076 Tübingen, Germany
- German Center of Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany
| | - Olaf Riess
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
- Center for Rare Diseases, University of Tübingen, 72076 Tübingen, Germany
| | - Tobias B. Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
- Center for Rare Diseases, University of Tübingen, 72076 Tübingen, Germany
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Saha S, Corben LA, Selvadurai LP, Harding IH, Georgiou-Karistianis N. Predictive machine learning and multimodal data to develop highly sensitive, composite biomarkers of disease progression in Friedreich ataxia. Sci Rep 2025; 15:17629. [PMID: 40399385 PMCID: PMC12095658 DOI: 10.1038/s41598-025-01047-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2024] [Accepted: 05/02/2025] [Indexed: 05/23/2025] Open
Abstract
Friedreich ataxia (FRDA) is a rare, inherited progressive movement disorder for which there is currently no cure. The field urgently requires more sensitive, objective, and clinically relevant biomarkers to enhance the evaluation of treatment efficacy in clinical trials and to speed up the process of drug discovery. This study pioneers the development of clinically relevant, multidomain, fully objective composite biomarkers of disease severity and progression, using multimodal neuroimaging and background data (i.e., demographic, disease history, genetics). Data from 31 individuals with FRDA and 31 controls from a longitudinal multimodal natural history study IMAGE-FRDA, were included. Using an elasticnet predictive machine learning (ML) regression model, we derived a weighted combination of background, structural MRI, diffusion MRI, and quantitative susceptibility imaging (QSM) measures that predicted Friedreich ataxia rating scale (FARS) with high accuracy (R2 = 0.79, root mean square error (RMSE) = 13.19). This composite also exhibited strong sensitivity to disease progression over two years (Cohen's d = 1.12), outperforming the sensitivity of the FARS score alone (d = 0.88). The approach was validated using the Scale for the assessment and rating of ataxia (SARA), demonstrating the potential and robustness of ML-derived composites to surpass individual biomarkers and act as complementary or surrogate markers of disease severity and progression. However, further validation, refinement, and the integration of additional data modalities will open up new opportunities for translating these biomarkers into clinical practice and clinical trials for FRDA, as well as other rare neurodegenerative diseases.
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Affiliation(s)
- Susmita Saha
- School of Psychological Sciences, The Turner Institute for Brain and Mental Health, Monash University, 18 innovation walk, Clayton campus, Clayton, Victoria, Australia
- Department of Neuroscience, School of Translational Medicine, Monash University, Melbourne, Australia
| | - Louise A Corben
- School of Psychological Sciences, The Turner Institute for Brain and Mental Health, Monash University, 18 innovation walk, Clayton campus, Clayton, Victoria, Australia
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - Louisa P Selvadurai
- School of Psychological Sciences, The Turner Institute for Brain and Mental Health, Monash University, 18 innovation walk, Clayton campus, Clayton, Victoria, Australia
| | - Ian H Harding
- Department of Neuroscience, School of Translational Medicine, Monash University, Melbourne, Australia
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Nellie Georgiou-Karistianis
- School of Psychological Sciences, The Turner Institute for Brain and Mental Health, Monash University, 18 innovation walk, Clayton campus, Clayton, Victoria, Australia.
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Visani E, Canafoglia L, Nanetti L, Rossi Sebastiano D, Duran D, Anversa P, Bonfoco D, Dotta S, Tabarelli D, Castaldo A, Marchini G, Mongelli A, Mariotti C. Neuromagnetic responses to multimodal stimuli in Friedreich's ataxia. Clin Neurophysiol 2025; 175:2110738. [PMID: 40403493 DOI: 10.1016/j.clinph.2025.2110738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2024] [Revised: 04/14/2025] [Accepted: 04/23/2025] [Indexed: 05/24/2025]
Abstract
OBJECTIVE This study explores the utility of various evoked fields in elucidating the pathophysiology of Friedreich's ataxia (FA) and potentially contributing to developing more targeted diagnostic and therapeutic strategies. METHODS Thirty-seven patients with FA aged 27.6 ± 7.4 years and a control group of 17 healthy subjects were enrolled in the study. The neuromagnetic response to auditory, tactile, visual, somatosensory, auditory and tactile oddball stimulation were acquired. For all the components of interest, latency and amplitude were measured and correlated with clinical data. RESULTS Neuromagnetic responses were identifiable in more than 90% of cases. A significant response delay was observed in all tested modalities (auditory, somatosensory, tactile and visual responses). P300 responses were comparable in patients and healthy subjects. Latencies of visual and auditory responses correlated with SARA scores. Moreover, latencies of auditory responses correlated with disease onset age, whereas latencies of visual responses correlated with disease severity. CONCLUSIONS Auditory and visual responses correlated with the severity of the disease, whereas alterations in somatosensory responses represent an intrinsic characteristic of the disease. SIGNIFICANCE In FA the study of evoked visual fields could provide a possible biomarker of disease progression and treatment efficacy.
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Affiliation(s)
- Elisa Visani
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy
| | - Laura Canafoglia
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy.
| | - Lorenzo Nanetti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Via Celoria 11, 20133 Milan, Italy
| | - Davide Rossi Sebastiano
- Neurophysiology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy
| | - Dunja Duran
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy
| | - Paola Anversa
- Neurophysiology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy
| | - Deborah Bonfoco
- Neurophysiology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy
| | - Sara Dotta
- Neurophysiology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy
| | - Davide Tabarelli
- Centre for Mind/Brain Sciences, University of Trento, via delle Regole 101, 38123 Trento, Italy
| | - Anna Castaldo
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Via Celoria 11, 20133 Milan, Italy
| | - Gloria Marchini
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Via Celoria 11, 20133 Milan, Italy
| | - Alessia Mongelli
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Via Celoria 11, 20133 Milan, Italy
| | - Caterina Mariotti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Via Celoria 11, 20133 Milan, Italy
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Sureshkumar S, Chhabra A, Guo YL, Balasubramanian S. Simple sequence repeats and their expansions: role in plant development, environmental response and adaptation. THE NEW PHYTOLOGIST 2025. [PMID: 40325839 DOI: 10.1111/nph.70173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2024] [Accepted: 03/28/2025] [Indexed: 05/07/2025]
Abstract
Repetitive DNA is a feature of all organisms, ranging from archaea and plants to humans. DNA repeats can be seen both in coding and in noncoding regions of the genome. Due to the recurring nature of the sequences, simple DNA repeats tend to be more prone to errors during replication and repair, resulting in variability in their unit length. This feature of simple sequence repeats led to their use as molecular markers for mapping traits in diverse organisms. Advances in genomics, and the ever-reducing costs of genome sequencing have empowered us to assess the functional impacts of DNA repeats. The variability in repeat lengths can cause phenotypic differences depending on where they are present in the genome. Variability in the repeat length in coding regions of genes results in poly amino acid stretches that appear to interfere with protein function, including the perturbation of protein-protein interactions with diverse phenotypic impacts. These are often common allelic variations that can significantly impact evolutionary dynamics. In extreme situations, repeats can undergo massive expansions and appear as outliers. Repeat expansions underlie several genetic defects in plants to diseases in humans. This review systematically analyses tandem DNA repeats in plants, their role in development and environmental response and adaptation in plants. We identify and synthesise emerging themes, differentiate repeat length variability and repeat expansions, and argue that many repeat-associated phenotypes in plants are yet to be discovered. We emphasise the underexplored nature and immense potential of this area of research, particularly in plants, and suggest ways in which this can be achieved and how it might contribute to evolution and agricultural productivity.
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Affiliation(s)
- Sridevi Sureshkumar
- School of Biological Sciences, Monash University, Clayton Campus, Melbourne, VIC, 3800, Australia
| | - Aaryan Chhabra
- School of Biological Sciences, Monash University, Clayton Campus, Melbourne, VIC, 3800, Australia
| | - Ya-Long Guo
- State Key Laboratory of Plant Diversity and Speciality Crops/State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
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Grant-Bier J, Ruppert K, Hayward B, Usdin K, Kumari D. MSH2 is not required for either maintenance of DNA methylation or repeat contraction at the FMR1 locus in fragile X syndrome or the FXN locus in Friedreich's ataxia. Epigenetics Chromatin 2025; 18:24. [PMID: 40296143 PMCID: PMC12036138 DOI: 10.1186/s13072-025-00588-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2024] [Accepted: 04/11/2025] [Indexed: 04/30/2025] Open
Abstract
BACKGROUND Repeat-induced epigenetic changes are observed in many repeat expansion disorders (REDs). These changes result in transcriptional deficits and/or silencing of the associated gene. MSH2, a mismatch repair protein that is required for repeat expansion in the REDs, has been implicated in the maintenance of DNA methylation seen in the region upstream of the expanded CTG repeats at the DMPK locus in myotonic dystrophy type 1 (DM1). Here, we investigated the role of MSH2 in aberrant DNA methylation in two additional REDs, fragile X syndrome (FXS) that is caused by a CGG repeat expansion in the 5' untranslated region (UTR) of the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene, and Friedreich's ataxia (FRDA) that is caused by a GAA repeat expansion in intron 1 of the frataxin (FXN) gene. RESULTS In contrast to what is seen at the DMPK locus in DM1, loss of MSH2 did not decrease DNA methylation at the FMR1 promoter in FXS embryonic stem cells (ESCs) or increase FMR1 transcription. This difference was not due to the differences in the CpG density of the two loci as a decrease in DNA methylation was also not observed in a less CpG dense region upstream of the expanded GAA repeats in the FXN gene in MSH2 null induced pluripotent stem cells (iPSCs) derived from FRDA patient fibroblasts. Surprisingly, given previous reports, we found that FMR1 reactivation was associated with a high frequency of MSH2-independent CGG-repeat contractions that resulted a permanent loss of DNA methylation. MSH2-independent GAA-repeat contractions were also seen in FRDA cells. CONCLUSIONS Our results suggest that there are mechanistic differences in the way that DNA methylation is maintained in the region upstream of expanded repeats among different REDs even though they share a similar mechanism of repeat expansion. The high frequency of transcription-induced MSH2-dependent and MSH2-independent contractions we have observed may contribute to the mosaicism that is frequently seen in carriers of FMR1 alleles with expanded CGG-repeat tracts. These contractions may reflect the underlying problems associated with transcription through the repeat. Given the recent interest in the therapeutic use of transcription-driven repeat contractions, our data may have interesting mechanistic, prognostic, and therapeutic implications.
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Affiliation(s)
- Jessalyn Grant-Bier
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
- Present address: Cellular and Molecular Biology Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Kathryn Ruppert
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Bruce Hayward
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Karen Usdin
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Daman Kumari
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA.
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Smith FM, Kosman DJ. Brain microvascular endothelial cells differentiated from a Friedreich's Ataxia patient iPSC are deficient in tight junction protein expression and paracellularly permeable. Front Mol Neurosci 2025; 18:1511388. [PMID: 40303283 PMCID: PMC12037585 DOI: 10.3389/fnmol.2025.1511388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2024] [Accepted: 03/19/2025] [Indexed: 05/02/2025] Open
Abstract
Friedreich's Ataxia (FA) is a rare, inherited ataxia resulting from GAA triplet expansions in the first intron of the Frataxin (FXN) gene, which encodes a mitochondrial protein involved in the incorporation of iron into iron-sulfur clusters. We previously identified decreased levels of F-actin and tight junction (TJ) proteins, which coincided with paracellular permeability in an FXN shRNA-mediated knockdown immortalized human brain microvascular endothelial cell (BMVEC) model. This premise is underexplored in the FA literature, prompting us to confirm these findings using a patient-derived iPSC model. One line each of FA patient iPSCs and age- and sex-matched apparently healthy iPSCs were differentiated into BMVEC-like cells. We quantified actin glutathionylation, F-actin abundance, TJ expression and organization, and barrier integrity. In the absence of dysregulated F-actin organization, FA iBMVEC exhibited a loss of 50% ZO-1, 63% Occludin, and 19% Claudin-5 protein expression, along with a disruption in the bi-cellular organization of the latter two proteins. Functionally, this correlated with barrier hyperpermeability, delayed barrier maturation, and increased flux of the fluorescent tracer Lucifer Yellow. These data indicate that decreased barrier integrity is a pathophysiological phenotype of FA brain microvascular endothelial cells. Clinically, this may represent a targetable pathway to reduce brain iron accumulation, neuroinflammation, and neurodegeneration profiles in FA. Additionally, an investigation into other barrier systems, such as the blood-nerve barrier, blood-CSF barrier, or cardiac vasculature, may provide insights into the extra-neural symptoms experienced by FA patients.
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Affiliation(s)
| | - Daniel J. Kosman
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, The State University of New York at Buffalo, Buffalo, NY, United States
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Adam CL, Rocha J, Sudmant P, Rohlfs R. TRACKing tandem repeats: a customizable pipeline for identification and cross-species comparison. BIOINFORMATICS ADVANCES 2025; 5:vbaf066. [PMID: 40351869 PMCID: PMC12064168 DOI: 10.1093/bioadv/vbaf066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2024] [Revised: 03/14/2025] [Accepted: 04/07/2025] [Indexed: 05/14/2025]
Abstract
Summary TRACK is a user-friendly Snakemake workflow designed to streamline the discovery and comparison of tandem repeats (TRs) across species. TRACK facilitates the cataloging and filtering of TRs based on reference genomes or T2T transcripts, and applies reciprocal LiftOver and sequence alignment methods to identify putative homologous TRs between species. For further analyses, TRACK can be used to genotype TRs and subsequently estimate and plot basic population genetic statistics. By incorporating key functionalities within an integrated workflow, TRACK enhances TR analysis accessibility and reproducibility, while offering flexibility for the user. Availability and implementation The TRACK toolkit with step-by-step tutorial is freely available at https://github.com/caroladam/track.
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Affiliation(s)
- Carolina L Adam
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon 97403, United States
| | - Joana Rocha
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, United States
| | - Peter Sudmant
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, United States
| | - Rori Rohlfs
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon 97403, United States
- School of Computer and Data Sciences, University of Oregon, Eugene, OR 97403, United States
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11
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Pellerin D, Méreaux JL, Boluda S, Danzi MC, Dicaire MJ, Davoine CS, Genis D, Spurdens G, Ashton C, Hammond JM, Gerhart BJ, Chelban V, Le PU, Safisamghabadi M, Yanick C, Lee H, Nageshwaran SK, Matos-Rodrigues G, Jaunmuktane Z, Petrecca K, Akbarian S, Nussenzweig A, Usdin K, Renaud M, Bonnet C, Ravenscroft G, Saporta MA, Napierala JS, Houlden H, Deveson IW, Napierala M, Brice A, Molina Porcel L, Seilhean D, Zuchner S, Durr A, Brais B. Somatic instability of the FGF14-SCA27B GAA•TTC repeat reveals a marked expansion bias in the cerebellum. Brain 2025; 148:1258-1270. [PMID: 39378335 PMCID: PMC11969470 DOI: 10.1093/brain/awae312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2024] [Revised: 08/21/2024] [Accepted: 09/24/2024] [Indexed: 10/10/2024] Open
Abstract
Spinocerebellar ataxia 27B (SCA27B) is a common autosomal dominant ataxia caused by an intronic GAA•TTC repeat expansion in FGF14. Neuropathological studies have shown that neuronal loss is largely restricted to the cerebellum. Although the repeat locus is highly unstable during intergenerational transmission, it remains unknown whether it exhibits cerebral mosaicism and progressive instability throughout life. We conducted an analysis of the FGF14 GAA•TTC repeat somatic instability across 156 serial blood samples from 69 individuals, fibroblasts, induced pluripotent stem cells and post-mortem brain tissues from six controls and six patients with SCA27B, alongside methylation profiling using targeted long-read sequencing. Peripheral tissues exhibited minimal somatic instability, which did not significantly change over periods of more than 20 years. In post-mortem brains, the GAA•TTC repeat was remarkably stable across all regions, except in the cerebellar hemispheres and vermis. The levels of somatic expansion in the cerebellar hemispheres and vermis were, on average, 3.15 and 2.72 times greater relative to other examined brain regions, respectively. Additionally, levels of somatic expansion in the brain increased with repeat length and tissue expression of FGF14. We found no significant difference in methylation of wild-type and expanded FGF14 alleles in post-mortem cerebellar hemispheres between patients and controls. In conclusion, our study revealed that the FGF14 GAA•TTC repeat exhibits a cerebellar-specific expansion bias, which may explain the pure cerebellar involvement in SCA27B.
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Affiliation(s)
- David Pellerin
- Dr John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC H3A 2B4, Canada
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, London WC1N 3BG, UK
| | - Jean-Loup Méreaux
- Sorbonne Université, Institut du Cerveau—Paris Brain Institute- ICM, Inserm, CNRS, APHP, University Hospital Pitié-Salpêtrière, F-75013 Paris, France
| | - Susana Boluda
- Sorbonne Université, Institut du Cerveau—Paris Brain Institute- ICM, Inserm, CNRS, APHP, University Hospital Pitié-Salpêtrière, F-75013 Paris, France
| | - Matt C Danzi
- Dr John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Marie-Josée Dicaire
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Claire-Sophie Davoine
- Sorbonne Université, Institut du Cerveau—Paris Brain Institute- ICM, Inserm, CNRS, APHP, University Hospital Pitié-Salpêtrière, F-75013 Paris, France
| | - David Genis
- Ataxia and Hereditary Spastic Paraplegia Unit, Service of Neurology, Hospital Universitari de Girona Dr. Josep Trueta (ICS) & Hospital Santa Caterina IAS, Institut d’Investigació Biomèdica de Girona (IDIBGI), 17007 Girona, Spain
| | - Guinevere Spurdens
- Dr John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Catherine Ashton
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC H3A 2B4, Canada
- Department of Neurology, Royal Perth Hospital, Perth, WA 6000, Australia
| | - Jillian M Hammond
- Genomics and Inherited Disease Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
- Centre for Population Genomics, Garvan Institute of Medical Research and Murdoch Children’s Research Institute, Sydney, NSW 2010, Australia
| | - Brandon J Gerhart
- Department of Neurology, Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-8823, USA
| | - Viorica Chelban
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, London WC1N 3BG, UK
- Neurobiology and Medical Genetics Laboratory, ‘Nicolae Testemitanu’ State University of Medicine and Pharmacy, MD-2004 Chisinau, Republic of Moldova
| | - Phuong U Le
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Maryam Safisamghabadi
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Christopher Yanick
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Hamin Lee
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, London WC1N 3BG, UK
| | - Sathiji K Nageshwaran
- Department of Psychiatry, Friedman Brain Institute Icahn School of Medicine at Mount Sinai, New York, NY 10029-5674, USA
- Department of Neuroscience, Friedman Brain Institute Icahn School of Medicine at Mount Sinai, New York, NY 10029-5674, USA
- Department of Genetics and Genomic Sciences, Friedman Brain Institute Icahn School of Medicine at Mount Sinai, New York, NY 10029-5674, USA
- Neurogenetics Program, Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | | | - Zane Jaunmuktane
- Division of Neuropathology, The National Hospital for Neurology and Neurosurgery, University College London NHS Foundation Trust, London WC1N 3BG, UK
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Kevin Petrecca
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Schahram Akbarian
- Department of Psychiatry, Friedman Brain Institute Icahn School of Medicine at Mount Sinai, New York, NY 10029-5674, USA
- Department of Neuroscience, Friedman Brain Institute Icahn School of Medicine at Mount Sinai, New York, NY 10029-5674, USA
- Department of Genetics and Genomic Sciences, Friedman Brain Institute Icahn School of Medicine at Mount Sinai, New York, NY 10029-5674, USA
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Karen Usdin
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mathilde Renaud
- INSERM-U1256 NGERE, Université de Lorraine, 54500 Nancy, France
- Service de Neurologie, CHRU de Nancy, 54000 Nancy, France
- Service de Génétique Clinique, CHRU de Nancy, 54000 Nancy, France
| | - Céline Bonnet
- INSERM-U1256 NGERE, Université de Lorraine, 54500 Nancy, France
- Laboratoire de Génétique, CHRU de Nancy, 54000 Nancy, France
| | - Gianina Ravenscroft
- Harry Perkins Institute of Medical Research, Centre for Medical Research, University of Western Australia, Nedlands, Perth, WA 6009, Australia
| | - Mario A Saporta
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Jill S Napierala
- Department of Neurology, Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-8823, USA
| | - Henry Houlden
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, London WC1N 3BG, UK
| | - Ira W Deveson
- Genomics and Inherited Disease Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
- Centre for Population Genomics, Garvan Institute of Medical Research and Murdoch Children’s Research Institute, Sydney, NSW 2010, Australia
- Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia
| | - Marek Napierala
- Department of Neurology, Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-8823, USA
| | - Alexis Brice
- Sorbonne Université, Institut du Cerveau—Paris Brain Institute- ICM, Inserm, CNRS, APHP, University Hospital Pitié-Salpêtrière, F-75013 Paris, France
| | - Laura Molina Porcel
- Alzheimer’s Disease and other Cognitive Disorders Unit, Service of Neurology, Hospital Clínic, Fundació de Recerca Clínic Barcelona-Institut d’Investigacions Biomediques August Pi i Sunyer (FRCB-IDIBAPS), University of Barcelona, 08036 Barcelona, Spain
- Neurological Tissue Brain Bank, Biobanc-Hospital Clínic-FRCB-IDIBAPS, 08036 Barcelona, Spain
| | - Danielle Seilhean
- Sorbonne Université, Institut du Cerveau—Paris Brain Institute- ICM, Inserm, CNRS, APHP, University Hospital Pitié-Salpêtrière, F-75013 Paris, France
| | - Stephan Zuchner
- Dr John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Alexandra Durr
- Sorbonne Université, Institut du Cerveau—Paris Brain Institute- ICM, Inserm, CNRS, APHP, University Hospital Pitié-Salpêtrière, F-75013 Paris, France
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC H3A 2B4, Canada
- Department of Human Genetics, McGill University, Montreal, QC H3A 0C7, Canada
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12
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Indelicato E, Delatycki MB, Farmer J, França MC, Perlman S, Rai M, Boesch S. A global perspective on research advances and future challenges in Friedreich ataxia. Nat Rev Neurol 2025; 21:204-215. [PMID: 40032987 DOI: 10.1038/s41582-025-01065-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2025] [Indexed: 03/05/2025]
Abstract
Friedreich ataxia (FRDA) is a rare multisystem, life-limiting disease and is the most common early-onset inherited ataxia in populations of European, Arab and Indian descent. In recent years, substantial progress has been made in dissecting the pathogenesis and natural history of FRDA, and several clinical trials have been initiated. A particularly notable recent achievement was the approval of the nuclear factor erythroid 2-related factor 2 activator omaveloxolone as the first disease-specific therapy for FRDA. In light of these developments, we review milestones in FRDA translational and clinical research over the past 10 years, as well as the various therapeutic strategies currently in the pipeline. We also consider the lessons that have been learned from failed trials and other setbacks. We conclude by presenting a global roadmap for future research, as outlined by the recently established Friedreich's Ataxia Global Clinical Consortium, which covers North and South America, Europe, India, Australia and New Zealand.
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Affiliation(s)
- Elisabetta Indelicato
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Martin B Delatycki
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Parkville, Victoria, Australia
| | | | | | | | - Myriam Rai
- Friedreich's Ataxia Research Alliance, Downingtown, PA, USA
- Laboratory of Experimental Neurology, Brussels, Belgium
| | - Sylvia Boesch
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
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13
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Mercado-Ayón E, Talgo E, Flatley L, Coulman J, Lynch DR. Neurochemical alterations in the cerebellum of Friedreich's Ataxia mouse models. Exp Neurol 2025; 386:115176. [PMID: 39904419 DOI: 10.1016/j.expneurol.2025.115176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2024] [Revised: 01/29/2025] [Accepted: 02/01/2025] [Indexed: 02/06/2025]
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder caused by frataxin deficiency. Neurological deficits remain the ubiquitous feature of FRDA and include progressive ataxia and dysarthria, both of which are controlled to a large degree by the cerebellum. The precise impact of frataxin deficiency on the cerebellum including Purkinje cells remains unclear. In the present work, we examined the biochemical and structural properties of the cerebellum and Purkinje cells in the doxycycline-inducible (FRDAkd) and the Knock-in/Knockout (KIKO) mouse models of FRDA. Acute systemic knockdown of frataxin in FRDAkd mice and chronic frataxin deficiency in KIKO leads to a significant decrease in levels of AMPA receptors, particularly GluR2, and an increase in glial glutamate transporters. Significant astroglial accumulation occurred in KIKO cerebellum but not in FRDAkd mice. Purkinje cell dendritic arbors in the molecular layer did not change compared to wildtype in either model. The Purkinje cell postsynaptic receptor NMDAR1 significantly decreased only in the FRDAkd cerebellum while other NMDA receptor subunits, largely found in non-Purkinje cells, did not change. Overall, we observed dysregulated levels of glutamate receptors and transporters in the KIKO and FRDAkd mice models of Friedreich ataxia, suggesting the importance of frataxin in maintaining Purkinje cells and cerebellar integrity along with synaptic properties. These results point to conserved but not identical synaptic features between the models that may represent markers or conceivably targets in human FRDA.
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Affiliation(s)
- Elizabeth Mercado-Ayón
- Departments of Pediatrics and Neurology, The Children's Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104, USA; Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA 19104, USA.
| | - Ellarie Talgo
- Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA 19104, USA
| | - Liam Flatley
- Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA 19104, USA
| | - Jennifer Coulman
- Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA 19104, USA.
| | - David R Lynch
- Departments of Pediatrics and Neurology, The Children's Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104, USA; Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA 19104, USA.
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14
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Li F, Yu J, Wang P, Li T, Tang Q, Zhu J. Bridge RNA-Guided Genetic Recombination Tools for Treating Neurodegenerative Nucleotide Repeat Disorders. Neurosci Bull 2025; 41:734-736. [PMID: 39966309 PMCID: PMC11979011 DOI: 10.1007/s12264-025-01358-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Accepted: 12/06/2024] [Indexed: 02/20/2025] Open
Affiliation(s)
- Fengshi Li
- Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, National Center for Neurological Disorders, National Key Laboratory of Brain Function and Brain Diseases, Institutes of Brain Science, Shanghai Key Laboratory of Brain Function and Regeneration, Institute of Neurosurgery, MOE Frontiers Center for Brain Science, Shanghai Institute of Stem Cell Research and Clinical Translation, Fudan University, Shanghai, 200040, China
| | - Jingyu Yu
- Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, National Center for Neurological Disorders, National Key Laboratory of Brain Function and Brain Diseases, Institutes of Brain Science, Shanghai Key Laboratory of Brain Function and Regeneration, Institute of Neurosurgery, MOE Frontiers Center for Brain Science, Shanghai Institute of Stem Cell Research and Clinical Translation, Fudan University, Shanghai, 200040, China
| | - Peng Wang
- Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, National Center for Neurological Disorders, National Key Laboratory of Brain Function and Brain Diseases, Institutes of Brain Science, Shanghai Key Laboratory of Brain Function and Regeneration, Institute of Neurosurgery, MOE Frontiers Center for Brain Science, Shanghai Institute of Stem Cell Research and Clinical Translation, Fudan University, Shanghai, 200040, China
| | - Tianwen Li
- Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, National Center for Neurological Disorders, National Key Laboratory of Brain Function and Brain Diseases, Institutes of Brain Science, Shanghai Key Laboratory of Brain Function and Regeneration, Institute of Neurosurgery, MOE Frontiers Center for Brain Science, Shanghai Institute of Stem Cell Research and Clinical Translation, Fudan University, Shanghai, 200040, China
| | - Qisheng Tang
- Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, National Center for Neurological Disorders, National Key Laboratory of Brain Function and Brain Diseases, Institutes of Brain Science, Shanghai Key Laboratory of Brain Function and Regeneration, Institute of Neurosurgery, MOE Frontiers Center for Brain Science, Shanghai Institute of Stem Cell Research and Clinical Translation, Fudan University, Shanghai, 200040, China
| | - Jianhong Zhu
- Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, National Center for Neurological Disorders, National Key Laboratory of Brain Function and Brain Diseases, Institutes of Brain Science, Shanghai Key Laboratory of Brain Function and Regeneration, Institute of Neurosurgery, MOE Frontiers Center for Brain Science, Shanghai Institute of Stem Cell Research and Clinical Translation, Fudan University, Shanghai, 200040, China.
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15
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Ben Zichri- David S, Shkuri L, Ast T. Pulling back the mitochondria's iron curtain. NPJ METABOLIC HEALTH AND DISEASE 2025; 3:6. [PMID: 40052109 PMCID: PMC11879881 DOI: 10.1038/s44324-024-00045-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2024] [Accepted: 12/09/2024] [Indexed: 03/09/2025]
Abstract
Mitochondrial functionality and cellular iron homeostasis are closely intertwined. Mitochondria are biosynthetic hubs for essential iron cofactors such as iron-sulfur (Fe-S) clusters and heme. These cofactors, in turn, enable key mitochondrial pathways, such as energy and metabolite production. Mishandling of mitochondrial iron is associated with a spectrum of human pathologies ranging from rare genetic disorders to common conditions. Here, we review mitochondrial iron utilization and its intersection with disease.
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Affiliation(s)
| | - Liraz Shkuri
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, 7610001 Israel
| | - Tslil Ast
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, 7610001 Israel
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16
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Montgomery CB, Salinas L, Cox GP, Adcock LE, Chang T, Figueroa F, Cortopassi G, Dedkova EN. Robust behavioral assessment of the inducible Friedreich's ataxia mouse does not show improvement with NRF2 induction. Dis Model Mech 2025; 18:dmm052128. [PMID: 40017373 PMCID: PMC11992351 DOI: 10.1242/dmm.052128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2024] [Accepted: 02/23/2025] [Indexed: 03/01/2025] Open
Abstract
Friedreich's ataxia, a recessive disorder caused by a mutation in the frataxin (FXN) gene, has few mouse models that demonstrate a progressive behavioral decline paralleling that of patients. A mouse model of systemic frataxin deficiency, the FXNKD, was recently developed using a doxycycline-inducible method; it is thought to mimic the patient phenotype seen when frataxin levels are decreased, but it has not been determined whether it is reliable for assessment of therapeutics. FXNKD mice underwent testing for 12 weeks alongside littermates, undergoing tests of motor function, gait and sensation. Additionally, a subset underwent treatment with omaveloxolone or dimethyl fumarate, both NRF2 inducers. We identified multiple techniques that sensitively detect decline in the mice, including open field, gait analysis and Von Frey tests. Furthermore, we developed a novel Salinas-Montgomery ataxia scale, which allows for more comprehensive assessment than a four-part cerebellar ataxia scale. Despite validating multiple sensitive techniques, we did not see any benefits of NRF2-inducing therapies in any tests. This was exacerbated by the discovery of a sexual dimorphism in FXNKD mice, in which males show more significant decline and better responsiveness to NRF2-inducing therapeutics.
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Affiliation(s)
- Claire B. Montgomery
- Department of Molecular Biosciences, University of California, Davis, Davis, CA 95616, USA
| | - Lili Salinas
- Department of Molecular Biosciences, University of California, Davis, Davis, CA 95616, USA
| | - Garrett P. Cox
- Department of Molecular Biosciences, University of California, Davis, Davis, CA 95616, USA
| | - Lauren E. Adcock
- Department of Molecular Biosciences, University of California, Davis, Davis, CA 95616, USA
| | - Tiffany Chang
- Department of Molecular Biosciences, University of California, Davis, Davis, CA 95616, USA
- Biomedical Research Models Inc., Richmond, CA 94806, USA
| | - Francisco Figueroa
- Department of Molecular Biosciences, University of California, Davis, Davis, CA 95616, USA
| | - Gino Cortopassi
- Department of Molecular Biosciences, University of California, Davis, Davis, CA 95616, USA
| | - Elena N. Dedkova
- Department of Molecular Biosciences, University of California, Davis, Davis, CA 95616, USA
- Department of Basic Sciences, California Northstate University, Elk Grove, CA 95757, USA
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17
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Jacobi H, Weiler M, Sam G, Heiland S, Hayes JM, Bendszus M, Wick W, Hayes JC. Peripheral Nerve Involvement in Friedreich's Ataxia Characterized by Quantitative Magnetic Resonance Neurography. Eur J Neurol 2025; 32:e70121. [PMID: 40130461 PMCID: PMC11933833 DOI: 10.1111/ene.70121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2025] [Revised: 02/26/2025] [Accepted: 03/06/2025] [Indexed: 03/26/2025]
Abstract
BACKGROUND Friedreich's ataxia (FRDA) affects both the central and peripheral nervous system. Peripheral nerve involvement manifests predominantly as a progressive sensory neuropathy caused by dorsal root ganglionopathy. An additional direct involvement of peripheral nerves leading to abnormal myelination is increasingly discussed. Here, we characterize lower extremity peripheral nerve involvement in FRDA by quantitative magnetic resonance neurography (MRN). METHODS Sixteen genetically confirmed FRDA patients and 16 age-/sex-matched controls were prospectively enrolled. Patients underwent neurologic examinations and nerve conduction studies (NCS). Large-coverage MRN of sciatic and tibial nerves was conducted utilizing dual-echo turbo-spin-echo sequences with spectral fat saturation for T2-relaxometry, and two gradient-echo sequences with and without off-resonance saturation rapid frequency pulses for magnetization transfer contrast imaging. Microstructural and morphometric MRN markers including T2-relaxation time (T2app), proton spin density (ρ), magnetization transfer ratio (MTR), and cross-sectional area (CSA) were calculated to characterize nerve lesions. RESULTS Tibial nerve ρ and T2app were markedly decreased in FRDA at the thigh (ρ: 368.4 ± 11.0 a.u.; T2app: 59.5 ± 1.8 ms) and lower leg (ρ: 337.3 ± 12.6 a.u.; T2app: 53.9 ± 1.4 ms) versus controls (thigh, ρ: 458.9 ± 9.5 a.u., p < 0.0001; T2app: 66.3 ± 0.8 ms, p = 0.0019; lower leg, ρ: 449.9 ± 12.1 a.u., p < 0.0001; T2app: 62.4 ± 1.2 ms, p < 0.0001) and correlated well with clinical scores, disease duration, and NCS. MTR and CSA did not differentiate between FRDA and controls. CONCLUSION Our study results provide a profound characterization of peripheral nerve involvement in FRDA. The identified good correlation between ρ and T2app with clinical symptom scores and NCS suggests that parameters of T2 relaxometry may become relevant biomarkers to monitor disease progression and therapeutic responses in potential future clinical trials.
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Affiliation(s)
- Heike Jacobi
- Department of NeurologyHeidelberg University HospitalHeidelbergGermany
| | - Markus Weiler
- Department of NeurologyHeidelberg University HospitalHeidelbergGermany
| | - Georges Sam
- Department of NeurologyHeidelberg University HospitalHeidelbergGermany
| | - Sabine Heiland
- Department of NeuroradiologyHeidelberg University HospitalHeidelbergGermany
- Division of Experimental Radiology, Department of NeuroradiologyHeidelberg University HospitalHeidelbergGermany
| | - John M. Hayes
- Department of NeurologyUniversity of MichiganAnn ArborUSA
| | - Martin Bendszus
- Department of NeuroradiologyHeidelberg University HospitalHeidelbergGermany
| | - Wolfgang Wick
- Department of NeurologyHeidelberg University HospitalHeidelbergGermany
- Clinical Cooperation Unit NeurooncologyGerman Cancer Research Center/DKTKHeidelbergGermany
| | - Jennifer C. Hayes
- Department of NeuroradiologyHeidelberg University HospitalHeidelbergGermany
- Department of RadiologyUniversity of MichiganAnn ArborUSA
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18
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Ercanbrack WS, Ramirez M, Dungan A, Gaul E, Ercanbrack SJ, Wingert RA. Frataxin deficiency and the pathology of Friedreich's Ataxia across tissues. Tissue Barriers 2025:2462357. [PMID: 39981684 DOI: 10.1080/21688370.2025.2462357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2024] [Revised: 01/08/2025] [Accepted: 01/14/2025] [Indexed: 02/22/2025] Open
Abstract
Friedreich's Ataxia (FRDA) is a neurodegenerative disease that affects a variety of different organ systems. The disease is caused by GAA repeat expansions in intron 1 of the Frataxin gene (FXN), which results in a decrease in the expression of the FXN protein. FXN is needed for the biogenesis of iron-sulfur clusters (ISC) which are required by key metabolic processes in the mitochondria. Without ISCs those processes do not occur properly. As a result, reactive oxygen species accumulate, and the mitochondria cease to function. Iron is also thought to accumulate in the cells of certain tissue types. These processes are thought to be intimately related to the pathologies affecting a myriad of tissues in FRDA. Most FRDA patients suffer from loss of motor control, cardiomyopathy, scoliosis, foot deformities, and diabetes. In this review, we discuss the known features of FRDA pathology and the current understanding about the basis of these alterations.
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Affiliation(s)
- Wesley S Ercanbrack
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Mateo Ramirez
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Austin Dungan
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Ella Gaul
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Sarah J Ercanbrack
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Rebecca A Wingert
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
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19
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Cory SA, Lin CW, Patra S, Havens SM, Putnam CD, Shirzadeh M, Russell DH, Barondeau DP. Frataxin Traps Low Abundance Quaternary Structure to Stimulate Human Fe-S Cluster Biosynthesis. Biochemistry 2025; 64:903-916. [PMID: 39909887 PMCID: PMC11840927 DOI: 10.1021/acs.biochem.4c00733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2024] [Revised: 01/25/2025] [Accepted: 01/30/2025] [Indexed: 02/07/2025]
Abstract
Iron-sulfur clusters are essential protein cofactors synthesized in human mitochondria by an NFS1-ISD11-ACP-ISCU2-FXN assembly complex. Surprisingly, researchers have discovered three distinct quaternary structures for cysteine desulfurase subcomplexes, which display similar interactions between NFS1-ISD11-ACP protomeric units but dramatically different dimeric interfaces between the protomers. Although the role of these different architectures is unclear, possible functions include regulating activity and promoting the biosynthesis of distinct sulfur-containing biomolecules. Here, crystallography, native ion-mobility mass spectrometry, and chromatography methods reveal the Fe-S assembly subcomplex exists as an equilibrium mixture of these different quaternary structures. Isotope labeling and native mass spectrometry experiments show that the NFS1-ISD11-ACP complexes disassemble into protomers, which can then undergo exchange reactions and dimerize to reform native complexes. Single crystals isolated in distinct architectures have the same activity profile and activation by the Friedreich's ataxia (FRDA) protein frataxin (FXN) when rinsed and dissolved in assay buffer. These results suggest FXN functions as a "molecular lock" and shifts the equilibrium toward one of the architectures to stimulate the cysteine desulfurase activity and promote iron-sulfur cluster biosynthesis. An NFS1-designed variant similarly shifts the equilibrium and partially replaces FXN in activating the complex. We propose that eukaryotic cysteine desulfurases are unusual members of the morpheein class of enzymes that control their activity through their oligomeric state. Overall, the findings support architectural switching as a regulatory mechanism linked to FXN activation of the human Fe-S cluster biosynthetic complex and provide new opportunities for therapeutic interventions of the fatal neurodegenerative disease FRDA.
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Affiliation(s)
- Seth A. Cory
- Department
of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Cheng-Wei Lin
- Department
of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Shachin Patra
- Department
of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Steven M. Havens
- Department
of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Christopher D. Putnam
- Department
of Medicine, University of California School
of Medicine, La Jolla, California 92093-0660, United States
| | - Mehdi Shirzadeh
- Department
of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - David H. Russell
- Department
of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - David P. Barondeau
- Department
of Chemistry, Texas A&M University, College Station, Texas 77842, United States
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20
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Miller WL, Pandey AV, Flück CE. Disordered Electron Transfer: New Forms of Defective Steroidogenesis and Mitochondriopathy. J Clin Endocrinol Metab 2025; 110:e574-e582. [PMID: 39574227 PMCID: PMC11834722 DOI: 10.1210/clinem/dgae815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2024] [Indexed: 02/19/2025]
Abstract
Most disorders of steroidogenesis, such as forms of congenital adrenal hyperplasia (CAH) are caused by mutations in genes encoding the steroidogenic enzymes and are often recognized clinically by cortisol deficiency, hyper- or hypo-androgenism, and/or altered mineralocorticoid function. Most steroidogenic enzymes are forms of cytochrome P450. Most P450s, including several steroidogenic enzymes, are microsomal, requiring electron donation by P450 oxidoreductase (POR); however, several steroidogenic enzymes are mitochondrial P450s, requiring electron donation via ferredoxin reductase (FDXR) and ferredoxin (FDX). POR deficiency is a rare but well-described form of CAH characterized by impaired activity of 21-hydroxylase (P450c21, CYP21A2) and 17-hydroxylase/17,20-lyase (P450c17, CYP17A1); more severely affected individuals also have the Antley-Bixler skeletal malformation syndrome and disordered genital development in both sexes, and hence is easily recognized. The 17,20-lyase activity of P450c17 requires both POR and cytochrome b5 (b5), which promote electron transfer. Mutations of POR, b5, or P450c17 can cause selective 17,20-lyase deficiency. In addition to providing electrons to mitochondrial P450s, FDX, and FDXR are required for the synthesis of iron-sulfur clusters, which are used by many enzymes. Recent work has identified FDXR mutations in patients with visual impairment, optic atrophy, neuropathic hearing loss, and developmental delay, resembling the global neurologic disorders seen with mitochondrial diseases. Many of these patients have had life-threatening events or deadly infections, often without an apparent triggering event. Adrenal insufficiency has been predicted in such individuals but has only been documented recently. Neurologists, neonatologists, and geneticists should seek endocrine assistance in evaluating and treating patients with mutations in FDXR.
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Affiliation(s)
- Walter L Miller
- Department of Pediatrics, Center for Reproductive Sciences, and Institute for Human Genetics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Amit V Pandey
- Pediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Bern 3010, Switzerland
- Department of BioMedical Research, University of Bern, Bern 3010, Switzerland
| | - Christa E Flück
- Pediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Bern 3010, Switzerland
- Department of BioMedical Research, University of Bern, Bern 3010, Switzerland
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21
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Joseph DJ, Mercado-Ayon E, Flatley L, Viaene AN, Hordeaux J, Marsh ED, Lynch DR. Functional Characterization of Parallel Fiber-Purkinje Cell Synapses in Two Friedreich's Ataxia Mouse Models. CEREBELLUM (LONDON, ENGLAND) 2025; 24:42. [PMID: 39907933 PMCID: PMC11799031 DOI: 10.1007/s12311-025-01796-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/27/2025] [Indexed: 02/06/2025]
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive disorder caused by GAA expansions in the FXN gene, which codes for the protein frataxin (FXN). These mutations reduce FXN expression, leading to mitochondrial dysfunction and multisystemic disease. Accumulating evidence suggests that neuronal dysfunction, rather than neuronal death, may drive the neurological phenotypes of FRDA, but the mechanisms underlying such neurological phenotypes remain unclear. To investigate the neural circuit basis of this dysfunction, we employed field recordings to measure Purkinje cell (PC) function and synaptic properties along with western blotting and immunohistochemistry to determine their density and structure in two established FRDA mouse models, the shRNA-frataxin (FRDAkd) and the frataxin knock in-knockout (KIKO) mice. Western blotting demonstrated subtle changes in mitochondrial proteins and only a modest reduction in the density of calbindin positive cells PCs in the cerebellar cortex of the FRDAkd mice, with no change in the density of PCs in the KIKO mice. Though PC density differed slightly in the two models, field recordings of parallel fiber-PC synapses in the molecular layer demonstrated concordant hypo-excitability of basal synaptic transmission and impairments of long-term plasticity using induction protocols associated with both potentiation and depression of synaptic strength. These results indicate that synaptic instability might be a common feature in FRDA mouse models.
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Affiliation(s)
- Donald J Joseph
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Elizabeth Mercado-Ayon
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Liam Flatley
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Angela N Viaene
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Juliette Hordeaux
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Eric D Marsh
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - David R Lynch
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Department of Pediatrics and Neurology, Perelman School of Medicine, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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22
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Lynch DR, Subramony S, Lin KY, Mathews K, Perlman S, Yoon G, Rummey C. Characterization of Cardiac-Onset Initial Presentation in Friedreich Ataxia. Pediatr Cardiol 2025; 46:379-382. [PMID: 38427090 DOI: 10.1007/s00246-024-03429-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Accepted: 01/23/2024] [Indexed: 03/02/2024]
Abstract
We examined the clinical features of Friedreich ataxia (FRDA) patients who present first with cardiac disease in order to understand the earliest features of the diagnostic journey in FRDA. We identified a group of subjects in the FACOMS natural history study whose first identified clinical feature was cardiac. Only 0.5% of the total cohort belonged to this group, which was younger on average at the time of presentation. Their cardiac symptoms ranged from asymptomatic features to heart failure with severe systolic dysfunction. Two of those individuals with severe dysfunction proceeded to heart transplantation, but others spontaneously recovered. In most cases, diagnosis of FRDA was not made until well after cardiac presentation. The present study shows that some FRDA patients present based on cardiac features, suggesting that earlier identification of FRDA might occur through enhancing awareness of FRDA among pediatric cardiologists who see such patients. This is important in the context of newly identified therapies for FRDA.
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Affiliation(s)
- David R Lynch
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Departments of Pediatrics and Neurology, Perelman School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, 502F Abramson Research Center, 3615 Civic Center Blvd, Philadelphia, PA, 19104-4318, Switzerland.
| | - Sub Subramony
- Department of Neurology, University of Florida, Gainesville, FL, 32608, USA
| | - Kimberly Y Lin
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Division of Cardiology, Department of Pediatrics, Perelman School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Katherine Mathews
- Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Susan Perlman
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, 90095, USA
| | - Grace Yoon
- Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
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23
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Lynch DR, Shen M, Wilson RB. Friedreich ataxia: what can we learn from non-GAA repeat mutations? Neurodegener Dis Manag 2025; 15:17-26. [PMID: 39810561 PMCID: PMC11938963 DOI: 10.1080/17582024.2025.2452147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 01/08/2025] [Indexed: 01/16/2025] Open
Abstract
Friedreich ataxia (FRDA) is a slowly progressive neurological disease resulting from decreased levels of the protein frataxin, a small mitochondrial protein that facilitates the synthesis of iron-sulfur clusters in the mitochondrion. It is caused by GAA (guanine-adenine-adenine) repeat expansions in the FXN gene in 96% of patients, with 4% of patients carrying other mutations (missense, nonsense, deletion) in the FXN gene. Compound heterozygote patients with one expanded GAA allele and a non-GAA repeat mutation can have subtle differences in phenotype from typical FRDA, including, in patients with selected missense mutations, both more severe features and less severe features in the same patient. In this review, we propose explanations for such phenotypes based on the potential for activities of frataxin other than enhancement of iron-sulfur cluster synthesis, as well as crucial future experiments for fully understanding the role of frataxin in cells.
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Affiliation(s)
- David R. Lynch
- Friedreich Ataxia Program, Division of Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
- Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, USA
| | - M. Shen
- Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, USA
| | - Robert B. Wilson
- Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, USA
- Department of Pathology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
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24
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Pandolfo M. Friedreich Ataxia: An (Almost) 30-Year History After Gene Discovery. Neurol Genet 2025; 11:e200236. [PMID: 39810753 PMCID: PMC11731367 DOI: 10.1212/nxg.0000000000200236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2024] [Accepted: 11/26/2024] [Indexed: 01/16/2025]
Abstract
In the late 1800s, Nikolaus Friedreich first described "degenerative atrophy of the posterior columns of the spinal cord," noting its connection to progressive ataxia, sensory loss, and muscle weakness, now recognized as Friedreich ataxia (FRDA). Renewed interest in the disease in the 1970s and 80s by the Quebec Cooperative Group and by Anita Harding led to the development of clinical diagnostic criteria and insights into associated biochemical abnormalities, although the primary defect remained unknown. In 1988, Susan Chamberlain mapped FRDA's location on chromosome 9. In the early 90s, collaborative research, including work by the author's team, identified a gene, later named FXN, containing an expanded GAA repeat-confirming it as the FRDA mutation. This discovery established a diagnostic foundation for FRDA, advancing genetic testing and opening new research avenues. These new areas of study included the characteristics, origin, and pathogenicity of the GAA repeat expansion; the characterization of frataxin, the encoded protein, including its subcellular localization, structure, and function; the identification of cellular pathways disrupted by frataxin deficiency; and the redefinition of FRDA phenotypes based on genetic testing, along with the study of FRDA's natural history. In addition, efforts focused on the search for biomarkers to reflect diagnosis, disease severity, and progression and, most importantly, the identification and development of therapeutic approaches in both preclinical and clinical settings. The creation of cellular and animal models was crucial to this progress, as was the formation of consortia to collaboratively drive basic and clinical research forward. Now, 28 years after the gene discovery, although much remains to be understood about the disease's mechanisms and the development of effective therapies, the progress is undeniable. A thriving community has emerged, uniting researchers, health care providers, industry professionals, individuals with FRDA, their families, and dedicated volunteers. With this collective effort, a cure is within reach.
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Affiliation(s)
- Massimo Pandolfo
- Department of Neurology and Neurosurgery, McGill University, Montreal, Canada
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25
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Yang ZF, Jiang XC, Gao JQ. Present insights into the progress in gene therapy delivery systems for central nervous system diseases. Int J Pharm 2025; 669:125069. [PMID: 39662855 DOI: 10.1016/j.ijpharm.2024.125069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2024] [Revised: 12/06/2024] [Accepted: 12/08/2024] [Indexed: 12/13/2024]
Abstract
Central nervous system (CNS) diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), spinal cord injury (SCI), and ischemic strokes and certain rare diseases, such as amyotrophic lateral sclerosis (ALS) and ataxia, present significant obstacles to treatment using conventional molecular pharmaceuticals. Gene therapy, with its ability to target previously "undruggable" proteins with high specificity and safety, is increasingly utilized in both preclinical and clinical research for CNS ailments. As our comprehension of the pathophysiology of these conditions deepens, gene therapy stands out as a versatile and promising strategy with the potential to both prevent and treat these diseases. Despite the remarkable progress in refining and enhancing the structural design of gene therapy agents, substantial obstacles persist in their effective and safe delivery within living systems. To surmount these obstacles, a diverse array of gene delivery systems has been devised and continuously improved. Notably, Adeno-Associated Virus (AAVs)-based viral gene vectors and lipid-based nanocarriers have each advanced the in vivo delivery of gene therapies to various extents. This review aims to concisely summarize the pathophysiological foundations of CNS diseases and to shed light on the latest advancements in gene delivery vector technologies. It discusses the primary categories of these vectors, their respective advantages and limitations, and their specialized uses in the context of gene therapy delivery.
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Affiliation(s)
- Ze-Feng Yang
- State Key Laboratory of Advanced Drug Delivery and Release Systems, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Xin-Chi Jiang
- State Key Laboratory of Advanced Drug Delivery and Release Systems, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China..
| | - Jian-Qing Gao
- State Key Laboratory of Advanced Drug Delivery and Release Systems, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China..
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26
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Pellerin D, Iruzubieta P, Xu IRL, Danzi MC, Cortese A, Synofzik M, Houlden H, Zuchner S, Brais B. Recent Advances in the Genetics of Ataxias: An Update on Novel Autosomal Dominant Repeat Expansions. Curr Neurol Neurosci Rep 2025; 25:16. [PMID: 39820740 DOI: 10.1007/s11910-024-01400-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/04/2024] [Indexed: 01/19/2025]
Abstract
PURPOSE OF REVIEW Autosomal dominant cerebellar ataxias, also known as spinocerebellar ataxias (SCAs), are genetically and clinically diverse neurodegenerative disorders characterized by progressive cerebellar dysfunction. Despite advances in sequencing technologies, a large proportion of patients with SCA still lack a definitive genetic diagnosis. The advent of advanced bioinformatic tools and emerging genomics technologies, such as long-read sequencing, offers an unparalleled opportunity to close the diagnostic gap for hereditary ataxias. This article reviews the recently identified repeat expansion SCAs and describes their molecular basis, epidemiology, and clinical features. RECENT FINDINGS Leveraging advanced bioinformatic tools and long-read sequencing, recent studies have identified novel pathogenic short tandem repeat expansions in FGF14, ZFHX3, and THAP11, associated with SCA27B, SCA4, and SCA51, respectively. SCA27B, caused by an intronic (GAA)•(TTC) repeat expansion, has emerged as one of the most common forms of adult-onset hereditary ataxias, especially in European populations. The coding GGC repeat expansion in ZFHX3 causing SCA4 was identified more than 25 years after the disorder's initial clinical description and appears to be a rare cause of ataxia outside northern Europe. SCA51, caused by a coding CAG repeat expansion, is overall rare and has been described in a small number of patients. The recent identification of three novel pathogenic repeat expansions underscores the importance of this class of genomic variation in the pathogenesis of SCAs. Progress in sequencing technologies holds promise for closing the diagnostic gap in SCAs and guiding the development of therapeutic strategies for ataxia.
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Affiliation(s)
- David Pellerin
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, London, UK
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC, Canada
| | - Pablo Iruzubieta
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC, Canada
- Department of Neurosciences, Biogipuzkoa Health Research Institute, San Sebastián, Spain
- CIBERNED, ISCIII (CIBER, Carlos III Institute, Spanish Ministry of Sciences and Innovation), Madrid, Spain
| | - Isaac R L Xu
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Matt C Danzi
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Andrea Cortese
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, London, UK
| | - Matthis Synofzik
- Division of Translational Genomics of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Henry Houlden
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, London, UK
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC, Canada.
- Department of Human Genetics, McGill University, Montreal, QC, Canada.
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27
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Tranfa M, Costabile T, Pontillo G, Scaravilli A, Pane C, Brunetti A, Saccà F, Cocozza S. Altered Intracerebellar Functional Connectivity in Friedreich's Ataxia: A Graph-Theory Functional MRI Study. CEREBELLUM (LONDON, ENGLAND) 2025; 24:30. [PMID: 39808241 PMCID: PMC11732920 DOI: 10.1007/s12311-025-01785-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/04/2025] [Indexed: 01/16/2025]
Abstract
Historically, Friedreich's Ataxia (FRDA) has been linked to a relatively preserved cerebellar cortex. Recent advances in neuroimaging have revealed altered cerebello-cerebral functional connectivity (FC), but the extent of intra-cerebellar FC changes and their impact on cognition remains unclear. This study investigates intra-cerebellar FC alterations and their cognitive implications in FRDA. In this cross-sectional, single-center study, resting-state functional MRI data from 17 patients with FRDA (average age 27.7 ± 13.6 years; F/M = 6/11) and 20 healthy controls (HC) (average age 29.4 ± 9.7 years; F/M = 9/11), all of whom underwent neuropsychological testing, were analyzed. From functional connectivity matrices, graph measures were computed at both the network and node levels using two complementary parcellations. FRDA patients exhibited decreased global efficiency (p = 0.04), nodal degree (p = 0.001) and betweenness centrality (p = 0.04) in the vermal portion of lobule VIII, along with reduced global efficiency in cerebellar regions belonging to the Control-A network (p = 0.02), one of the three subdivisions of the Frontoparietal network. Verbal memory deficits correlated with global efficiency in both the vermal portion of lobule VIII (r = 0.53, p = 0.02) and the cerebellar regions of the Control-A network (r = 0.49, p = 0.05). Graph analysis revealed regional intra-cerebellar FC changes in FRDA, marked by reduced functional centrality in cerebellar regions of the vermis and responsible for executive functions. These changes correlated with cognitive alterations, highlighting the role of the cerebellar cortex in the cognitive impairment observed in FRDA.
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Affiliation(s)
- Mario Tranfa
- Department of Advanced Biomedical Sciences, University of Naples "Federico II", Via Pansini 5, 80131, Naples, Italy
| | - Teresa Costabile
- Department of Clinical and Experimental Medicine, "Luigi Vanvitelli" University, Naples, Italy
| | - Giuseppe Pontillo
- Department of Advanced Biomedical Sciences, University of Naples "Federico II", Via Pansini 5, 80131, Naples, Italy
| | - Alessandra Scaravilli
- Department of Advanced Biomedical Sciences, University of Naples "Federico II", Via Pansini 5, 80131, Naples, Italy
| | - Chiara Pane
- Department of Neurosciences and Reproductive and Odontostomatological Sciences, University of Naples "Federico II", Naples, Italy
| | - Arturo Brunetti
- Department of Advanced Biomedical Sciences, University of Naples "Federico II", Via Pansini 5, 80131, Naples, Italy
| | - Francesco Saccà
- Department of Neurosciences and Reproductive and Odontostomatological Sciences, University of Naples "Federico II", Naples, Italy
| | - Sirio Cocozza
- Department of Advanced Biomedical Sciences, University of Naples "Federico II", Via Pansini 5, 80131, Naples, Italy.
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28
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Wen H, Deng H, Li B, Chen J, Zhu J, Zhang X, Yoshida S, Zhou Y. Mitochondrial diseases: from molecular mechanisms to therapeutic advances. Signal Transduct Target Ther 2025; 10:9. [PMID: 39788934 PMCID: PMC11724432 DOI: 10.1038/s41392-024-02044-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Revised: 09/28/2024] [Accepted: 10/31/2024] [Indexed: 01/12/2025] Open
Abstract
Mitochondria are essential for cellular function and viability, serving as central hubs of metabolism and signaling. They possess various metabolic and quality control mechanisms crucial for maintaining normal cellular activities. Mitochondrial genetic disorders can arise from a wide range of mutations in either mitochondrial or nuclear DNA, which encode mitochondrial proteins or other contents. These genetic defects can lead to a breakdown of mitochondrial function and metabolism, such as the collapse of oxidative phosphorylation, one of the mitochondria's most critical functions. Mitochondrial diseases, a common group of genetic disorders, are characterized by significant phenotypic and genetic heterogeneity. Clinical symptoms can manifest in various systems and organs throughout the body, with differing degrees and forms of severity. The complexity of the relationship between mitochondria and mitochondrial diseases results in an inadequate understanding of the genotype-phenotype correlation of these diseases, historically making diagnosis and treatment challenging and often leading to unsatisfactory clinical outcomes. However, recent advancements in research and technology have significantly improved our understanding and management of these conditions. Clinical translations of mitochondria-related therapies are actively progressing. This review focuses on the physiological mechanisms of mitochondria, the pathogenesis of mitochondrial diseases, and potential diagnostic and therapeutic applications. Additionally, this review discusses future perspectives on mitochondrial genetic diseases.
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Affiliation(s)
- Haipeng Wen
- Department of Ophthalmology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
- Xiangya School of Medicine, Central South University, Changsha, Hunan, 410013, China
| | - Hui Deng
- Department of Ophthalmology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
- Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, 410011, China
| | - Bingyan Li
- Department of Ophthalmology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
- Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, 410011, China
| | - Junyu Chen
- Department of Ophthalmology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
- Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, 410011, China
| | - Junye Zhu
- Department of Ophthalmology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
- Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, 410011, China
| | - Xian Zhang
- Department of Ophthalmology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
- Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, 410011, China
| | - Shigeo Yoshida
- Department of Ophthalmology, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Yedi Zhou
- Department of Ophthalmology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China.
- Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, 410011, China.
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Livanos I, Votsi C, Michailidou K, Pellerin D, Brais B, Zuchner S, Pantzaris M, Kleopa KA, Zamba Papanicolaou E, Christodoulou K. The FGF14 GAA repeat expansion is a major cause of ataxia in the Cypriot population. Brain Commun 2025; 7:fcae479. [PMID: 39801711 PMCID: PMC11724429 DOI: 10.1093/braincomms/fcae479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2024] [Revised: 11/08/2024] [Accepted: 01/02/2025] [Indexed: 01/16/2025] Open
Abstract
Dominantly inherited intronic GAA repeat expansions in the fibroblast growth factor 14 gene have recently been shown to cause spinocerebellar ataxia 27B. Currently, the pathogenic threshold of (GAA)≥300 repeat units is considered highly penetrant, while (GAA)250-299 is likely pathogenic with reduced penetrance. This study investigated the frequency of the GAA repeat expansion and the phenotypic profile in a Cypriot cohort with unresolved late-onset cerebellar ataxia. We analysed this trinucleotide repeat in 155 patients with late-onset cerebellar ataxia and 227 non-neurological disease controls. The repeat locus was examined by long-range PCR followed by fragment analysis using capillary electrophoresis, agarose gel electrophoresis and automated electrophoresis. A comprehensive comparison of all three electrophoresis techniques was conducted. Additionally, bidirectional repeat-primed PCRs and Sanger sequencing were carried out to confirm the absence of any interruptions or non-GAA motifs in the expanded alleles. The (GAA)≥250 repeat expansion was present in 12 (7.7%) patients. The average age at disease onset was 60 ± 13.5 years. The earliest age of onset was observed in a patient with a (GAA)287 repeat expansion, with ataxia symptoms appearing at 25 years of age. All patients with spinocerebellar ataxia 27B displayed symptoms of gait and appendicular ataxia. Nystagmus was observed in 41.7% of the patients, while 58.3% exhibited dysarthria. Our findings indicate that spinocerebellar ataxia 27B represents the predominant aetiology of autosomal dominant cerebellar ataxia in the Cypriot population, as this is the first dominant repeat expansion ataxia type detected in this population. Given our results and existing research, we propose including fibroblast growth factor 14 GAA repeat expansion testing as a first-tier genetic diagnostic approach for patients with late-onset cerebellar ataxia.
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Affiliation(s)
- Ioannis Livanos
- Neurogenetics Department, The Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
- The Cyprus Institute of Neurology and Genetics is a member of the European Reference Network-Rare Neurological Diseases (ERN-RND), Research Management Unit, Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen, Tübingen 72076, Germany
| | - Christina Votsi
- Neurogenetics Department, The Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
- The Cyprus Institute of Neurology and Genetics is a member of the European Reference Network-Rare Neurological Diseases (ERN-RND), Research Management Unit, Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen, Tübingen 72076, Germany
| | - Kyriaki Michailidou
- The Cyprus Institute of Neurology and Genetics is a member of the European Reference Network-Rare Neurological Diseases (ERN-RND), Research Management Unit, Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen, Tübingen 72076, Germany
- Biostatistics Unit, The Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
| | - David Pellerin
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC, CanadaH3A 2B4
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, London WC1N 3BG, UK
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC, CanadaH3A 2B4
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Marios Pantzaris
- The Cyprus Institute of Neurology and Genetics is a member of the European Reference Network-Rare Neurological Diseases (ERN-RND), Research Management Unit, Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen, Tübingen 72076, Germany
- Neuroimmunology Department, The Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
| | - Kleopas A Kleopa
- The Cyprus Institute of Neurology and Genetics is a member of the European Reference Network-Rare Neurological Diseases (ERN-RND), Research Management Unit, Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen, Tübingen 72076, Germany
- Neuroscience Department, The Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
- Centre for Neuromuscular Disorders, The Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
| | - Eleni Zamba Papanicolaou
- The Cyprus Institute of Neurology and Genetics is a member of the European Reference Network-Rare Neurological Diseases (ERN-RND), Research Management Unit, Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen, Tübingen 72076, Germany
- Centre for Neuromuscular Disorders, The Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
- Neuroepidemiology Department, The Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
| | - Kyproula Christodoulou
- Neurogenetics Department, The Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
- The Cyprus Institute of Neurology and Genetics is a member of the European Reference Network-Rare Neurological Diseases (ERN-RND), Research Management Unit, Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen, Tübingen 72076, Germany
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Marullo C, Croci L, Giupponi I, Rivoletti C, Zuffetti S, Bettegazzi B, Cremona O, Giunti P, Ambrosi A, Casoni F, Consalez GG, Codazzi F. Altered Ca2+ responses and antioxidant properties in Friedreich's ataxia-like cerebellar astrocytes. J Cell Sci 2025; 138:jcs263446. [PMID: 39648860 PMCID: PMC11828468 DOI: 10.1242/jcs.263446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2024] [Accepted: 12/03/2024] [Indexed: 12/10/2024] Open
Abstract
Friedreich's ataxia (FRDA) is a neurodegenerative disorder characterized by severe neurological signs, affecting the peripheral and central nervous system, caused by reduced frataxin protein (FXN) levels. Although several studies have highlighted cellular dysfunctions in neurons, there is limited information on the effects of FXN depletion in astrocytes and on the potential non-cell autonomous mechanisms affecting neurons in FRDA. In this study, we generated a model of FRDA cerebellar astrocytes to unveil phenotypic alterations that might contribute to cerebellar atrophy. We treated primary cerebellar astrocytes with an RNA interference-based approach, to achieve a reduction of FXN comparable to that observed in individuals with FRDA. These FRDA-like astrocytes display some typical features of the disease, such as an increase of oxidative stress and a depletion of glutathione content. Moreover, FRDA-like astrocytes exhibit decreased Ca2+ responses to purinergic stimuli. Our findings shed light on cellular changes caused by FXN downregulation in cerebellar astrocytes, likely impairing their complex interaction with neurons. The potentially impaired ability to provide neuronal cells with glutathione or to release neuromodulators in a Ca2+-dependent manner could affect neuronal function, contributing to neurodegeneration.
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Affiliation(s)
- Chiara Marullo
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Laura Croci
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Iris Giupponi
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Claudia Rivoletti
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Sofia Zuffetti
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
| | - Barbara Bettegazzi
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
| | - Ottavio Cremona
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
| | - Paola Giunti
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Alessandro Ambrosi
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
| | - Filippo Casoni
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
| | - Gian Giacomo Consalez
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
| | - Franca Codazzi
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
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31
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Sperelakis-Beedham B, Gitiaux C, Rajaoba M, Magen M, Derive N, Chansard J, de Sainte Agathe JM, Maurin ML, Assouline Z, Barnerias C, Desguerre I, Steffann J, Barcia G. Uniparental IsoDisomy: a case study on a new mechanism of Friedreich ataxia. Eur J Hum Genet 2025; 33:137-140. [PMID: 39496895 PMCID: PMC11711457 DOI: 10.1038/s41431-024-01728-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 09/17/2024] [Accepted: 10/27/2024] [Indexed: 11/06/2024] Open
Abstract
Friedreich's Ataxia (FRDA) is the most common hereditary ataxia and is mainly caused by biallelic GAA repeat expansion in the FXN gene. Rare patients carrying FXN point mutations or intragenic deletions are reported. We describe the first FRDA patient with a chromosome 9 segmental Uniparental isoDisomy (UPiD) unmasking a homozygous FXN expansion initially undetected by TP-PCR. The child presented with a progressive proprioceptive ataxia associated with peripheral sensory neuronopathy and severe scoliosis. Whole genome sequencing (WGS) identified a maternal segmental Uniparental Isodisomy (UPiD) encompassing FXN. Short tandem repeats analysis on WGS showed a biallelic FXN expansion. The identification of a deletion in the primer-annealing region of the TP-PCR explained the initial TP-PCR failure. This is the first documented case of FRDA caused by segmental UPiD. This case highlights the complexity of the molecular diagnosis of FRDA, and emphasises the importance of integrating results from various technical diagnostic approaches.
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Affiliation(s)
- Brian Sperelakis-Beedham
- Service de Médecine Génomique des Maladies Rares, Hôpital Necker - Enfants Malades, Assistance Publique-Hôpitaux de Paris, Paris, France
- Imagine Institute, Genetics of Mitochondrial Disorders, INSERM, Paris, France
- Université Paris Cité, Paris, France
| | - Cyril Gitiaux
- Université Paris Cité, Paris, France
- Pediatric Neurology and Neurophysiology Department, Necker-Enfants-Malades Hospital, Assistance Publique-Hôpitaux, Paris, France
| | - Marine Rajaoba
- Service de Médecine Génomique des Maladies Rares, Hôpital Necker - Enfants Malades, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Maryse Magen
- Service de Médecine Génomique des Maladies Rares, Hôpital Necker - Enfants Malades, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Nicolas Derive
- Laboratoire de Biologie Médicale Multi-Sites SeqOIA Assistance-Publique, Paris, France
| | - Jerome Chansard
- Laboratoire de Biologie Médicale Multi-Sites SeqOIA Assistance-Publique, Paris, France
| | | | - Marie-Laure Maurin
- Service de Médecine Génomique des Maladies Rares, Hôpital Necker - Enfants Malades, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Zahra Assouline
- Service de Médecine Génomique des Maladies Rares, Hôpital Necker - Enfants Malades, Assistance Publique-Hôpitaux de Paris, Paris, France
- Imagine Institute, Genetics of Mitochondrial Disorders, INSERM, Paris, France
| | - Christine Barnerias
- Université Paris Cité, Paris, France
- Pediatric Neurology and Neurophysiology Department, Necker-Enfants-Malades Hospital, Assistance Publique-Hôpitaux, Paris, France
| | - Isabelle Desguerre
- Université Paris Cité, Paris, France
- Pediatric Neurology and Neurophysiology Department, Necker-Enfants-Malades Hospital, Assistance Publique-Hôpitaux, Paris, France
| | - Julie Steffann
- Service de Médecine Génomique des Maladies Rares, Hôpital Necker - Enfants Malades, Assistance Publique-Hôpitaux de Paris, Paris, France
- Imagine Institute, Genetics of Mitochondrial Disorders, INSERM, Paris, France
- Université Paris Cité, Paris, France
| | - Giulia Barcia
- Service de Médecine Génomique des Maladies Rares, Hôpital Necker - Enfants Malades, Assistance Publique-Hôpitaux de Paris, Paris, France.
- Imagine Institute, Genetics of Mitochondrial Disorders, INSERM, Paris, France.
- Université Paris Cité, Paris, France.
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32
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Mukherjee S, Pereboeva L, Fil D, Saikia A, Lee J, Li J, Cotticelli MG, Soragni E, Wilson RB, Napierala M, Napierala JS. Design and validation of cell-based potency assays for frataxin supplementation treatments. Mol Ther Methods Clin Dev 2024; 32:101347. [PMID: 39823061 PMCID: PMC11735916 DOI: 10.1016/j.omtm.2024.101347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 09/24/2024] [Indexed: 01/19/2025]
Abstract
Friedreich's ataxia (FRDA) is a multisystem, autosomal recessive disorder caused by mutations in the frataxin (FXN) gene. As FRDA is considered an FXN deficiency disorder, numerous therapeutic approaches in development or clinical trials aim to supplement FXN or restore endogenous FXN expression. These include gene therapy, protein supplementation, genome editing or upregulation of FXN transcription. To evaluate efficacy of these therapies, potency assays capable of quantitative determination of FXN biological activity are needed. Herein, we evaluate the suitability of mouse embryonic fibroblasts derived from Fxn G127V knockin mice (MUT MEFs) as a candidate for cell-based potency assays. We demonstrate that these cells, when immortalized, continue to express minute amounts of Fxn and exhibit a broad range of phenotypes that result from severe Fxn deficiency. Exogenous FXN supplementation reverses these phenotypes. Thus, immortalized MUT MEFs are an excellent tool for developing potency assays to validate novel FRDA therapies. Care needs to be exercised while utilizing these cell lines, as extended passaging results in molecular changes that spontaneously reverse FRDA-like phenotypes without increasing Fxn expression. Based on transcriptome analyses, we identified the Warburg effect as the mechanism allowing cells expressing a minimal level of Fxn to thrive under standard cell culture conditions.
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Affiliation(s)
- Shibani Mukherjee
- Department of Neurology, O’Donnell Brain Institute, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Larisa Pereboeva
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
| | - Daniel Fil
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Achisha Saikia
- Department of Neurology, O’Donnell Brain Institute, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Jeon Lee
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Jixue Li
- Department of Neurology, O’Donnell Brain Institute, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - M. Grazia Cotticelli
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Elisabetta Soragni
- Friedreich’s Ataxia Research Alliance, 533 W. Uwchlan Avenue, Downingtown, PA 19335, USA
| | - Robert B. Wilson
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Marek Napierala
- Department of Neurology, O’Donnell Brain Institute, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Jill S. Napierala
- Department of Neurology, O’Donnell Brain Institute, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
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33
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Steinhilper R, Boß L, Freibert SA, Schulz V, Krapoth N, Kaltwasser S, Lill R, Murphy BJ. Two-stage binding of mitochondrial ferredoxin-2 to the core iron-sulfur cluster assembly complex. Nat Commun 2024; 15:10559. [PMID: 39632806 PMCID: PMC11618653 DOI: 10.1038/s41467-024-54585-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 11/15/2024] [Indexed: 12/07/2024] Open
Abstract
Iron-sulfur (FeS) protein biogenesis in eukaryotes begins with the de novo assembly of [2Fe-2S] clusters by the mitochondrial core iron-sulfur cluster assembly (ISC) complex. This complex comprises the scaffold protein ISCU2, the cysteine desulfurase subcomplex NFS1-ISD11-ACP1, the allosteric activator frataxin (FXN) and the electron donor ferredoxin-2 (FDX2). The structural interaction of FDX2 with the complex remains unclear. Here, we present cryo-EM structures of the human FDX2-bound core ISC complex showing that FDX2 and FXN compete for overlapping binding sites. FDX2 binds in either a 'distal' conformation, where its helix F interacts electrostatically with an arginine patch of NFS1, or a 'proximal' conformation, where this interaction tightens and the FDX2-specific C terminus binds to NFS1, facilitating the movement of the [2Fe-2S] cluster of FDX2 closer to the ISCU2 FeS cluster assembly site for rapid electron transfer. Structure-based mutational studies verify the contact areas of FDX2 within the core ISC complex.
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Affiliation(s)
- Ralf Steinhilper
- Redox and Metalloprotein Research Group, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438, Frankfurt am Main, Germany
| | - Linda Boß
- Institut für Zytobiologie, Philipps-Universität Marburg, Karl-von-Frisch-Str. 14, 35032, Marburg, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Karl-von-Frisch-Str. 14, 35032, Marburg, Germany
| | - Sven-A Freibert
- Institut für Zytobiologie, Philipps-Universität Marburg, Karl-von-Frisch-Str. 14, 35032, Marburg, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Karl-von-Frisch-Str. 14, 35032, Marburg, Germany
| | - Vinzent Schulz
- Institut für Zytobiologie, Philipps-Universität Marburg, Karl-von-Frisch-Str. 14, 35032, Marburg, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Karl-von-Frisch-Str. 14, 35032, Marburg, Germany
| | - Nils Krapoth
- Institut für Zytobiologie, Philipps-Universität Marburg, Karl-von-Frisch-Str. 14, 35032, Marburg, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Karl-von-Frisch-Str. 14, 35032, Marburg, Germany
| | - Susann Kaltwasser
- Central Electron Microscopy Facility, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438, Frankfurt am Main, Germany
| | - Roland Lill
- Institut für Zytobiologie, Philipps-Universität Marburg, Karl-von-Frisch-Str. 14, 35032, Marburg, Germany.
- Zentrum für Synthetische Mikrobiologie Synmikro, Karl-von-Frisch-Str. 14, 35032, Marburg, Germany.
| | - Bonnie J Murphy
- Redox and Metalloprotein Research Group, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438, Frankfurt am Main, Germany.
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34
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Masnovo C, Paleiov Z, Dovrat D, Baxter LK, Movafaghi S, Aharoni A, Mirkin SM. Stabilization of expandable DNA repeats by the replication factor Mcm10 promotes cell viability. Nat Commun 2024; 15:10532. [PMID: 39627228 PMCID: PMC11615337 DOI: 10.1038/s41467-024-54977-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 11/22/2024] [Indexed: 12/06/2024] Open
Abstract
Trinucleotide repeats, including Friedreich's ataxia (GAA)n repeats, become pathogenic upon expansions during DNA replication and repair. Here, we show that deficiency of the essential replisome component Mcm10 dramatically elevates (GAA)n repeat instability in a budding yeast model by loss of proper CMG helicase interaction. Supporting this conclusion, live-cell microscopy experiments reveal increased replication fork stalling at the repeat in mcm10-1 cells. Unexpectedly, the viability of strains containing a single (GAA)100 repeat at an essential chromosomal location strongly depends on Mcm10 function and cellular RPA levels. This coincides with Rad9 checkpoint activation, which promotes cell viability, but initiates repeat expansions via DNA synthesis by polymerase δ. When repair is inefficient, such as in the case of RPA depletion, breakage of under-replicated repetitive DNA can occur during G2/M, leading to loss of essential genes and cell death. We hypothesize that the CMG-Mcm10 interaction promotes replication through hard-to-replicate regions, assuring genome stability and cell survival.
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Affiliation(s)
- Chiara Masnovo
- Department of Biology, Tufts University, Medford, MA, 02155, USA
| | - Zohar Paleiov
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva, 8410501, Israel
| | - Daniel Dovrat
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva, 8410501, Israel
| | - Laurel K Baxter
- Department of Biology, Tufts University, Medford, MA, 02155, USA
| | - Sofia Movafaghi
- Department of Biology, Tufts University, Medford, MA, 02155, USA
| | - Amir Aharoni
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva, 8410501, Israel
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA, 02155, USA.
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35
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Gerhart BJ, Pellerin D, Danzi MC, Zuchner S, Brais B, Matos-Rodrigues G, Nussenzweig A, Usdin K, Park CC, Napierala JS, Lynch DR, Napierala M. Assessment of the Clinical Interactions of GAA Repeat Expansions in FGF14 and FXN. Neurol Genet 2024; 10:e200210. [PMID: 39574782 PMCID: PMC11581763 DOI: 10.1212/nxg.0000000000200210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Accepted: 09/19/2024] [Indexed: 11/24/2024]
Abstract
Background and Objectives The number of GAA repeats in the FXN gene is a major but not sole determinant of the clinical presentation of Friedreich ataxia (FRDA). The objective of this study was to establish whether the length of the GAA repeat tract in the FGF14 gene, which is associated with another neurodegenerative disorder (SCA27B), affects the clinical presentation (age at onset, mFARS score) of patients with FRDA. Methods The number of GAA repeats in the FXN and FGF14 genes was determined using PCR in a cohort of 221 patients with FRDA. Next, we compared absolute lengths of the FGF14 GAAs with FXN GAAs, followed by correlative analyses to determine potential effects of FGF14 GAA length on age at onset and clinical presentation (mFARS) of FRDA. Results We found no significant correlation between the size of the GAA repeats in FXN and FGF14 loci in our FRDA cohort. Moreover, the number of GAAs in FGF14 did not affect the clinical presentation of FRDA even in a small number of cases where a long FGF14 allele was present. Discussion Despite both molecular and clinical similarities between FRDA and SCA27B, the length of the GAA repeats in the FGF14 gene, including potentially pathogenic alleles, did not influence the clinical presentation of FRDA.
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Affiliation(s)
- Brandon J Gerhart
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - David Pellerin
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - Matt C Danzi
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - Stephan Zuchner
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - Bernard Brais
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - Gabriel Matos-Rodrigues
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - Andre Nussenzweig
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - Karen Usdin
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - Courtney C Park
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - Jill S Napierala
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - David R Lynch
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
| | - Marek Napierala
- From the Department of Neurology (B.J.G., J.S.N., M.N.), O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas; Department of Neurology and Neurosurgery (D.P., B.B.), Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Neuromuscular Diseases (D.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, United Kingdom; Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics (M.C.D., S.Z.), University of Miami Miller School of Medicine, FL; Department of Human Genetics (B.B.), McGill University, Montreal, Quebec, Canada; Laboratory of Genome Integrity (G.M.-R., A.N.), National Cancer Institute, NIH; Laboratory of Cell and Molecular Biology (K.U.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; and Department of Pediatrics and Neurology (C.C.P., D.R.L.), The Children's Hospital of Philadelphia, PA
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36
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Mohammed A, Churion K, Danda A, Philips SJ, Ansari AZ. A "Goldilocks Zone" for Recruiting BET Proteins with Bromodomain-1-Selective Ligands. ACS Chem Biol 2024; 19:2268-2276. [PMID: 39401417 PMCID: PMC12011195 DOI: 10.1021/acschembio.4c00505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2024]
Abstract
Synthetic genome readers/regulators (SynGRs) are bifunctional molecules that are rationally designed to bind specific genomic sequences and engage cellular machinery that regulates the expression of targeted genes. The prototypical SynGR1 targets GAA trinucleotide repeats and recruits the BET family of transcriptional regulatory proteins via a flexibly tethered ligand, JQ1. This pan-BET ligand binds both tandem bromodomains of BET proteins (BD1 and BD2). Second-generation SynGRs, which substituted JQ1 with bromodomain-selective ligands, unexpectedly revealed that BD1-selective ligands failed to functionally engage BET proteins in living cells despite displaying the ability to bind BD1 in vitro. Mechanistically, recruiting a BET protein via BD1- or BD2-selective SynGRs should have resulted in indistinguishable functional outcomes. Here we report the conversion of inactive BD1-targeting SynGRs into functional gene regulators by a structure-guided redesign of the chemical linker that bridges the DNA-binding molecule to the highly selective BD1 ligand GSK778. The results point to an optimal zone for positioning the BD1-selective ligand for functional engagement of BET proteins on chromatin, consistent with the preferred binding of BD1 domains to distal acetyllysine residues on histone tails. The results not only resolve the mechanistic conundrum but also provide insight into domain-selective targeting and nuanced design of chemo probes and therapeutics.
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Affiliation(s)
- Ashraf Mohammed
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105, United States
| | - Kelly Churion
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105, United States
| | - Adithi Danda
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105, United States
| | - Steven J. Philips
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105, United States
| | - Aseem Z. Ansari
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105, United States
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37
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Song Z, Zahin T, Li X, Shao M. Accurate Detection of Tandem Repeats from Error-Prone Sequences with EquiRep. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.11.05.621953. [PMID: 39574759 PMCID: PMC11580891 DOI: 10.1101/2024.11.05.621953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2024]
Abstract
A tandem repeat is a sequence of nucleotides that occurs as multiple contiguous and near-identical copies positioned next to each other. These repeats play critical roles in genetic diversity, gene regulation, and are strongly linked to various neurological and developmental disorders. While several methods exist for detecting tandem repeats, they often exhibit low accuracy when the repeat unit length increases or the number of copies is low. Furthermore, methods capable of handling highly mutated sequences remain scarce, highlighting a significant opportunity for improvement. We introduce EquiRep, a tool for accurate detection of tandem repeats from erroneous sequences. EquiRep estimates the likelihood of positions originating from the same position in the unit by self-alignment followed by a novel approach that refines the estimation. The built equivalent classes and the consecutive position information will be then used to build a weighted graph, and the cycle in this graph with maximum bottleneck weight while covering most nucleotide positions will be identified to reconstruct the repeat unit. We test EquiRep on simulated and real HOR and RCA datasets where it consistently outperforms or is comparable to state-of-the-art methods. EquiRep is robust to sequencing errors, and is able to make better predictions for long units and low frequencies which underscores its broad usability for studying tandem repeats.
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Affiliation(s)
- Zhezheng Song
- Department of Computer Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Tasfia Zahin
- Department of Computer Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Xiang Li
- Department of Computer Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Mingfu Shao
- Department of Computer Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
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38
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Lee GB, Park SM, Jung UJ, Kim SR. The Potential of Mesenchymal Stem Cells in Treating Spinocerebellar Ataxia: Advances and Future Directions. Biomedicines 2024; 12:2507. [PMID: 39595073 PMCID: PMC11591855 DOI: 10.3390/biomedicines12112507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2024] [Revised: 10/28/2024] [Accepted: 10/31/2024] [Indexed: 11/28/2024] Open
Abstract
Spinocerebellar ataxia (SCA) is a heterogeneous disorder characterized by impaired balance and coordination caused by cerebellar dysfunction. The absence of treatments approved by the U.S. Food and Drug Administration for SCA has driven the investigation of alternative therapeutic strategies, including stem cell therapy. Mesenchymal stem cells (MSCs), known for their multipotent capabilities, have demonstrated significant potential in treating SCA. This review examines how MSCs may promote neuronal growth, enhance synaptic connectivity, and modulate brain inflammation. Recent findings from preclinical and clinical studies are also reviewed, emphasizing the promise of MSC therapy in addressing the unmet needs of SCA patients. Furthermore, ongoing clinical trials and future directions are proposed to address the limitations of the current approaches.
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Affiliation(s)
- Gi Beom Lee
- School of Life Science and Biotechnology, BK21 FOUR KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea; (G.B.L.); (S.M.P.)
| | - Se Min Park
- School of Life Science and Biotechnology, BK21 FOUR KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea; (G.B.L.); (S.M.P.)
| | - Un Ju Jung
- Department of Food Science and Nutrition, Pukyong National University, Busan 48513, Republic of Korea;
| | - Sang Ryong Kim
- School of Life Science and Biotechnology, BK21 FOUR KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea; (G.B.L.); (S.M.P.)
- Brain Science and Engineering Institute, Kyungpook National University, Daegu 41404, Republic of Korea
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39
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Pan F, Xu P, Roland C, Sagui C, Weninger K. Structural and Dynamical Properties of Nucleic Acid Hairpins Implicated in Trinucleotide Repeat Expansion Diseases. Biomolecules 2024; 14:1278. [PMID: 39456210 PMCID: PMC11505666 DOI: 10.3390/biom14101278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2024] [Revised: 09/26/2024] [Accepted: 10/05/2024] [Indexed: 10/28/2024] Open
Abstract
Dynamic mutations in some human genes containing trinucleotide repeats are associated with severe neurodegenerative and neuromuscular disorders-known as Trinucleotide (or Triplet) Repeat Expansion Diseases (TREDs)-which arise when the repeat number of triplets expands beyond a critical threshold. While the mechanisms causing the DNA triplet expansion are complex and remain largely unknown, it is now recognized that the expandable repeats lead to the formation of nucleotide configurations with atypical structural characteristics that play a crucial role in TREDs. These nonstandard nucleic acid forms include single-stranded hairpins, Z-DNA, triplex structures, G-quartets and slipped-stranded duplexes. Of these, hairpin structures are the most prolific and are associated with the largest number of TREDs and have therefore been the focus of recent single-molecule FRET experiments and molecular dynamics investigations. Here, we review the structural and dynamical properties of nucleic acid hairpins that have emerged from these studies and the implications for repeat expansion mechanisms. The focus will be on CAG, GAC, CTG and GTC hairpins and their stems, their atomistic structures, their stability, and the important role played by structural interrupts.
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Affiliation(s)
- Feng Pan
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA; (F.P.); (C.R.)
- Department of Statistics, Florida State University, Tallahassee, FL 32306, USA
| | - Pengning Xu
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA; (F.P.); (C.R.)
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Christopher Roland
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA; (F.P.); (C.R.)
| | - Celeste Sagui
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA; (F.P.); (C.R.)
| | - Keith Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA; (F.P.); (C.R.)
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40
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Pall AE, Bond S, Bailey DK, Stoj CS, Deschamps I, Huggins P, Parsons J, Bradbury MJ, Kosman DJ, Stemmler TL. ATH434, a promising iron-targeting compound for treating iron regulation disorders. Metallomics 2024; 16:mfae044. [PMID: 39317669 DOI: 10.1093/mtomcs/mfae044] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Accepted: 09/22/2024] [Indexed: 09/26/2024]
Abstract
Cytotoxic accumulation of loosely bound mitochondrial Fe2+ is a hallmark of Friedreich's Ataxia (FA), a rare and fatal neuromuscular disorder with limited therapeutic options. There are no clinically approved medications targeting excess Fe2+ associated with FA or the neurological disorders Parkinson's disease and Multiple System Atrophy. Traditional iron-chelating drugs clinically approved for systemic iron overload that target ferritin-stored Fe3+ for urinary excretion demonstrated limited efficacy in FA and exacerbated ataxia. Poor treatment outcomes reflect inadequate binding to excess toxic Fe2+ or exceptionally high affinities (i.e. ≤10-31) for non-pathologic Fe3+ that disrupts intrinsic iron homeostasis. To understand previous treatment failures and identify beneficial factors for Fe2+-targeted therapeutics, we compared traditional Fe3+ chelators deferiprone (DFP) and deferasirox (DFX) with additional iron-binding compounds including ATH434, DMOG, and IOX3. ATH434 and DFX had moderate Fe2+ binding affinities (Kd's of 1-4 µM), similar to endogenous iron chaperones, while the remaining had weaker divalent metal interactions. These compounds had low/moderate affinities for Fe3+(0.46-9.59 µM) relative to DFX and DFP. While all compounds coordinated iron using molecular oxygen and/or nitrogen ligands, thermodynamic analyses suggest ATH434 completes Fe2+ coordination using H2O. ATH434 significantly stabilized bound Fe2+ from ligand-induced autooxidation, reducing reactive oxygen species (ROS) production, whereas DFP and DFX promoted production. The comparable affinity of ATH434 for Fe2+ and Fe3+ position it to sequester excess Fe2+ and facilitate drug-to-protein iron metal exchange, mimicking natural endogenous iron binding proteins, at a reduced risk of autooxidation-induced ROS generation or perturbation of cellular iron stores.
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Affiliation(s)
- Ashley E Pall
- De partment of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USA
| | - Silas Bond
- Alterity Therapeutics Limited, Melbourne, 3000, Australia
| | - Danielle K Bailey
- Department of Biochemistry, University of Buffalo, Buffalo, NY14203, USA
| | - Christopher S Stoj
- Department of Biochemistry, Chemistry and Physics, Niagara University, Lewiston, NY 14109, USA
| | - Isabel Deschamps
- Department of Biochemistry, Chemistry and Physics, Niagara University, Lewiston, NY 14109, USA
| | - Penny Huggins
- Alterity Therapeutics Limited, Melbourne, 3000, Australia
| | - Jack Parsons
- Alterity Therapeutics Limited, Melbourne, 3000, Australia
| | | | - Daniel J Kosman
- Department of Biochemistry, University of Buffalo, Buffalo, NY14203, USA
| | - Timothy L Stemmler
- De partment of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USA
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41
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Salinas L, Montgomery CB, Figueroa F, Thai PN, Chiamvimonvat N, Cortopassi G, Dedkova EN. Sexual dimorphism in a mouse model of Friedreich's ataxia with severe cardiomyopathy. Commun Biol 2024; 7:1250. [PMID: 39363102 PMCID: PMC11449905 DOI: 10.1038/s42003-024-06962-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Accepted: 09/25/2024] [Indexed: 10/05/2024] Open
Abstract
Friedreich's ataxia (FA) is an autosomal recessive disorder caused by reduced frataxin (FXN) expression in mitochondria, where the lethal component is cardiomyopathy. Using the conditional Fxnflox/null::MCK-Cre knock-out (Fxn-cKO) mouse model, we discovered significant sex differences in the progression towards heart failure, with Fxn-cKO males exhibiting a worse cardiac phenotype, low survival rate, kidney and reproductive organ deficiencies. These differences are likely due to a decline in testosterone in Fxn-cKO males. The decrease in testosterone was related to decreased expression of proteins involved in cholesterol transfer into the mitochondria: StAR and TSPO on the outer mitochondrial membrane, and the cholesterol side-chain cleavage enzyme P450scc and ferredoxin on the inner mitochondrial membrane. Expression of excitation-contraction coupling proteins (L-type calcium channel, RyR2, SERCA2, phospholamban and CaMKIIδ) was decreased significantly more in Fxn-cKO males. This is the first study that extensively investigates the sexual dimorphism in FA mouse model with cardiac calcium signaling impairment.
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Grants
- T32 HL086350 NHLBI NIH HHS
- R01 HL085727 NHLBI NIH HHS
- I01 CX001490 CSRD VA
- R01 HL101235 NHLBI NIH HHS
- R01 HL137228 NHLBI NIH HHS
- I01 BX000576 BLRD VA
- S10 OD010389 NIH HHS
- R01 HL085844 NHLBI NIH HHS
- R01 HL155907 NHLBI NIH HHS
- 1R01HL155907-1 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- F32 HL149288 NHLBI NIH HHS
- U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- Friedreich's Ataxia Research Alliance (FARA)
- University of California Davis CRCF Pilot & Feasibility Award 181031 (to END), University of California Innovative Development Award (to END) Harold S. Geneen Charitable Trust Awards Program for Coronary Heart Disease Research (to PNT) VA Merit Review Grant I01 BX000576 and I01 CX001490 (to NC) Research Award from the Rosenfeld Foundation (to NC.
- Pre-doctoral fellowship from NIH R01HL155907-02S1 Diversity Supplement (to LS).
- Pre-doctoral fellowship from NIH T32 HL086350 Training Grant in Basic & Translational Cardiovascular Science
- Postdoctoral fellowship from NIH T32HL086350 Training Grant in Basic & Translational Cardiovascular Science and NIH F32HL149288 and Harold S. Geneen Charitable Trust Awards Program for Coronary Heart Disease Research (to PNT).
- NIH R01 HL085727, HL085844, HL137228, VA Merit Review Grant I01 BX000576 and I01 CX001490, AHA 23SFRNCCS1052478, 23SFRNPCS1060482, and Research Award from the Rosenfeld Foundation (to NC).
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Affiliation(s)
- Lili Salinas
- Department of Molecular Biosciences, University of California, Davis, CA, USA
| | - Claire B Montgomery
- Department of Molecular Biosciences, University of California, Davis, CA, USA
| | - Francisco Figueroa
- Department of Molecular Biosciences, University of California, Davis, CA, USA
| | - Phung N Thai
- Department of Internal Medicine, University of California, Davis, CA, USA
- Department of Veterans Affairs, Northern California Health Care System, Mather, CA, USA
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California, Davis, CA, USA
- Department of Veterans Affairs, Northern California Health Care System, Mather, CA, USA
| | - Gino Cortopassi
- Department of Molecular Biosciences, University of California, Davis, CA, USA
| | - Elena N Dedkova
- Department of Molecular Biosciences, University of California, Davis, CA, USA.
- Department of Basic Sciences, California Northstate University, Elk Grove, CA, USA.
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42
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Mosbach V, Puccio H. A multiple animal and cellular models approach to study frataxin deficiency in Friedreich Ataxia. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119809. [PMID: 39134123 DOI: 10.1016/j.bbamcr.2024.119809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 08/01/2024] [Accepted: 08/02/2024] [Indexed: 08/15/2024]
Abstract
Friedreich's ataxia (FA) is one of the most frequent inherited recessive ataxias characterized by a progressive sensory and spinocerebellar ataxia. The main causative mutation is a GAA repeat expansion in the first intron of the frataxin (FXN) gene which leads to a transcriptional silencing of the gene resulting in a deficit in FXN protein. The nature of the mutation (an unstable GAA expansion), as well as the multi-systemic nature of the disease (with neural and non-neural sites affected) make the generation of models for Friedreich's ataxia quite challenging. Over the years, several cellular and animal models for FA have been developed. These models are all complementary and possess their own strengths to investigate different aspects of the disease, such as the epigenetics of the locus or the pathophysiology of the disease, as well as being used to developed novel therapeutic approaches. This review will explore the recent advancements in the different mammalian models developed for FA.
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Affiliation(s)
- Valentine Mosbach
- Institut NeuroMyoGene-PGNM UCBL-CNRS UMR5261 INSERM U1315, Lyon, France
| | - Hélène Puccio
- Institut NeuroMyoGene-PGNM UCBL-CNRS UMR5261 INSERM U1315, Lyon, France.
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Scott V, Delatycki MB, Tai G, Corben LA. New and Emerging Drug and Gene Therapies for Friedreich Ataxia. CNS Drugs 2024; 38:791-805. [PMID: 39115603 PMCID: PMC11377510 DOI: 10.1007/s40263-024-01113-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/18/2024] [Indexed: 09/06/2024]
Abstract
The life shortening nature of Friedreich Ataxia (FRDA) demands the search for therapies that can delay, stop or reverse its relentless trajectory. This review provides a contemporary position of drug and gene therapies for FRDA currently in phase 1 clinical trials and beyond. Despite significant scientific advances in the specificity of both compounds and targets developed and investigated, challenges remain for the advancement of treatments in a limited recruitment population. Currently therapies focus on reducing oxidative stress and improving mitochondrial function, modulating frataxin controlled metabolic pathways and gene replacement and editing. Approval of omaveloxolone, the first treatment for individuals with FRDA aged 16 years and over, has created much excitement for both those living with FRDA and those that care for them. The process of approval of omaveloxolone by the US Food and Drug Administration highlighted the importance of sensitive outcome measures and the significant role of data from natural history studies.
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Affiliation(s)
- Varlli Scott
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Parkville, VIC, 3052, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Martin B Delatycki
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Parkville, VIC, 3052, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
- Victorian Clinical Genetics Service, Parkville, VIC, Australia
| | - Geneieve Tai
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Parkville, VIC, 3052, Australia
| | - Louise A Corben
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Parkville, VIC, 3052, Australia.
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia.
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Sanz-Alcázar A, Portillo-Carrasquer M, Delaspre F, Pazos-Gil M, Tamarit J, Ros J, Cabiscol E. Deciphering the ferroptosis pathways in dorsal root ganglia of Friedreich ataxia models. The role of LKB1/AMPK, KEAP1, and GSK3β in the impairment of the NRF2 response. Redox Biol 2024; 76:103339. [PMID: 39243573 PMCID: PMC11408871 DOI: 10.1016/j.redox.2024.103339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2024] [Accepted: 09/02/2024] [Indexed: 09/09/2024] Open
Abstract
Friedreich ataxia (FA) is a rare neurodegenerative disease caused by decreased levels of the mitochondrial protein frataxin. Frataxin has been related in iron homeostasis, energy metabolism, and oxidative stress. Ferroptosis has recently been shown to be involved in FA cellular degeneration; however, its role in dorsal root ganglion (DRG) sensory neurons, the cells that are affected the most and the earliest, is mostly unknown. In this study, we used primary cultures of frataxin-deficient DRG neurons as well as DRG from the FXNI151F mouse model to study ferroptosis and its regulatory pathways. A lack of frataxin induced upregulation of transferrin receptor 1 and decreased ferritin and mitochondrial iron accumulation, a source of oxidative stress. However, there was impaired activation of NRF2, a key transcription factor involved in the antioxidant response pathway. Decreased total and nuclear NRF2 explains the downregulation of both SLC7A11 (a member of the system Xc, which transports cystine required for glutathione synthesis) and glutathione peroxidase 4, responsible for increased lipid peroxidation, the main markers of ferroptosis. Such dysregulation could be due to the increase in KEAP1 and the activation of GSK3β, which promote cytosolic localization and degradation of NRF2. Moreover, there was a deficiency in the LKB1/AMPK pathway, which would also impair NRF2 activity. AMPK acts as a positive regulator of NRF2 and it is activated by the upstream kinase LKB1. The levels of LKB1 were reduced when frataxin decreased, in agreement with reduced pAMPK (Thr172), the active form of AMPK. SIRT1, a known activator of LKB1, was also reduced when frataxin decreased. MT-6378, an AMPK activator, restored NRF2 levels, increased GPX4 levels and reduced lipid peroxidation. In conclusion, this study demonstrated that frataxin deficiency in DRG neurons disrupts iron homeostasis and the intricate regulation of molecular pathways affecting NRF2 activation and the cellular response to oxidative stress, leading to ferroptosis.
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Affiliation(s)
- Arabela Sanz-Alcázar
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, Catalonia, Spain.
| | | | - Fabien Delaspre
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, Catalonia, Spain.
| | - Maria Pazos-Gil
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, Catalonia, Spain.
| | - Jordi Tamarit
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, Catalonia, Spain.
| | - Joaquim Ros
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, Catalonia, Spain.
| | - Elisa Cabiscol
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, Catalonia, Spain.
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Vicente-Acosta A, Herranz-Martín S, Pazos MR, Galán-Cruz J, Amores M, Loria F, Díaz-Nido J. Glial cell activation precedes neurodegeneration in the cerebellar cortex of the YG8-800 murine model of Friedreich ataxia. Neurobiol Dis 2024; 200:106631. [PMID: 39111701 DOI: 10.1016/j.nbd.2024.106631] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Revised: 07/31/2024] [Accepted: 08/02/2024] [Indexed: 08/15/2024] Open
Abstract
Friedreich ataxia is a hereditary neurodegenerative disorder resulting from reduced levels of the protein frataxin due to an expanded GAA repeat in the FXN gene. This deficiency causes progressive degeneration of specific neuronal populations in the cerebellum and the consequent loss of movement coordination and equilibrium, which are some of the main symptoms observed in affected individuals. Like in other neurodegenerative diseases, previous studies suggest that glial cells could be involved in the neurodegenerative process and disease progression in patients with Friedreich ataxia. In this work, we followed and characterized the progression of changes in the cerebellar cortex in the latest version of Friedreich ataxia humanized mouse model, YG8-800 (Fxnnull:YG8s(GAA)>800), which carries a human FXN transgene containing >800 GAA repeats. Comparative analyses of behavioral, histopathological, and biochemical parameters were conducted between the control strain Y47R and YG8-800 mice at different time points. Our findings revealed that YG8-800 mice exhibit an ataxic phenotype characterized by poor motor coordination, decreased body weight, cerebellar atrophy, neuronal loss, and changes in synaptic proteins. Additionally, early activation of glial cells, predominantly astrocytes and microglia, was observed preceding neuronal degeneration, as was increased expression of key proinflammatory cytokines and downregulation of neurotrophic factors. Together, our results show that the YG8-800 mouse model exhibits a stronger phenotype than previous experimental murine models, reliably recapitulating some of the features observed in humans. Accordingly, this humanized model could represent a valuable tool for studying Friedreich ataxia molecular disease mechanisms and for preclinical evaluation of possible therapies.
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Affiliation(s)
- Andrés Vicente-Acosta
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Nicolás Cabrera 1, 28049 Madrid, Spain; Laboratorio de Apoyo a la Investigación, Hospital Universitario Fundación Alcorcón, Budapest 1, Alcorcón, 28922 Madrid, Spain
| | - Saúl Herranz-Martín
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Nicolás Cabrera 1, 28049 Madrid, Spain; Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Maria Ruth Pazos
- Laboratorio de Apoyo a la Investigación, Hospital Universitario Fundación Alcorcón, Budapest 1, Alcorcón, 28922 Madrid, Spain
| | - Jorge Galán-Cruz
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Nicolás Cabrera 1, 28049 Madrid, Spain; Departamento de Biología Molecular, Universidad Autónoma de Madrid, Francisco Tomás y Valiente, 7, Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain
| | - Mario Amores
- Laboratorio de Apoyo a la Investigación, Hospital Universitario Fundación Alcorcón, Budapest 1, Alcorcón, 28922 Madrid, Spain
| | - Frida Loria
- Laboratorio de Apoyo a la Investigación, Hospital Universitario Fundación Alcorcón, Budapest 1, Alcorcón, 28922 Madrid, Spain.
| | - Javier Díaz-Nido
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Nicolás Cabrera 1, 28049 Madrid, Spain; Departamento de Biología Molecular, Universidad Autónoma de Madrid, Francisco Tomás y Valiente, 7, Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain; Instituto de Investigación Sanitaria Puerta de Hierro, Segovia de Arana, Hospital Universitario Puerta de Hierro, Joaquín Rodrigo 1, Majadahonda, 28222 Madrid, Spain.
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Indelicato E, Wanschitz J, Löscher W, Boesch S. Skeletal Muscle Involvement in Friedreich Ataxia. Int J Mol Sci 2024; 25:9915. [PMID: 39337401 PMCID: PMC11432698 DOI: 10.3390/ijms25189915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2024] [Revised: 09/06/2024] [Accepted: 09/09/2024] [Indexed: 09/30/2024] Open
Abstract
Friedreich Ataxia (FRDA) is an inherited neuromuscular disorder triggered by a deficit of the mitochondrial protein frataxin. At a cellular level, frataxin deficiency results in insufficient iron-sulfur cluster biosynthesis and impaired mitochondrial function and adenosine triphosphate production. The main clinical manifestation is a progressive balance and coordination disorder which depends on the involvement of peripheral and central sensory pathways as well as of the cerebellum. Besides the neurological involvement, FRDA affects also the striated muscles. The most prominent manifestation is a hypertrophic cardiomyopathy, which also represents the major determinant of premature mortality. Moreover, FRDA displays skeletal muscle involvement, which contributes to the weakness and marked fatigue evident throughout the course of the disease. Herein, we review skeletal muscle findings in FRDA generated by functional imaging, histology, as well as multiomics techniques in both disease models and in patients. Altogether, these findings corroborate a disease phenotype in skeletal muscle and support the notion of progressive mitochondrial damage as a driver of disease progression in FRDA. Furthermore, we highlight the relevance of skeletal muscle investigations in the development of biomarkers for early-phase trials and future therapeutic strategies in FRDA.
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Affiliation(s)
- Elisabetta Indelicato
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, 6020 Innsbruck, Austria;
| | - Julia Wanschitz
- Unit for Neuromuscular Disorders and Clinical Neurophysiology, Department of Neurology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Wolfgang Löscher
- Unit for Neuromuscular Disorders and Clinical Neurophysiology, Department of Neurology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Sylvia Boesch
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, 6020 Innsbruck, Austria;
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Monfrini E, Baso G, Ronchi D, Meneri M, Gagliardi D, Quetti L, Verde F, Ticozzi N, Ratti A, Di Fonzo A, Comi GP, Ottoboni L, Corti S. Unleashing the potential of mRNA therapeutics for inherited neurological diseases. Brain 2024; 147:2934-2945. [PMID: 38662782 PMCID: PMC11969220 DOI: 10.1093/brain/awae135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 03/10/2024] [Accepted: 03/21/2024] [Indexed: 09/04/2024] Open
Abstract
Neurological monogenic loss-of-function diseases are hereditary disorders resulting from gene mutations that decrease or abolish the normal function of the encoded protein. These conditions pose significant therapeutic challenges, which may be resolved through the development of innovative therapeutic strategies. RNA-based technologies, such as mRNA replacement therapy, have emerged as promising and increasingly viable treatments. Notably, mRNA therapy exhibits significant potential as a mutation-agnostic approach that can address virtually any monogenic loss-of-function disease. Therapeutic mRNA carries the information for a healthy copy of the defective protein, bypassing the problem of targeting specific genetic variants. Moreover, unlike conventional gene therapy, mRNA-based drugs are delivered through a simplified process that requires only transfer to the cytoplasm, thereby reducing the mutagenic risks related to DNA integration. Additionally, mRNA therapy exerts a transient effect on target cells, minimizing the risk of long-term unintended consequences. The remarkable success of mRNA technology for developing coronavirus disease 2019 vaccines has rekindled interest in mRNA as a cost-effective method for delivering therapeutic proteins. However, further optimization is required to enhance mRNA delivery, particularly to the CNS, while minimizing adverse drug reactions and toxicity. In this comprehensive review, we delve into past, present and ongoing applications of mRNA therapy for neurological monogenic loss-of-function diseases. We also discuss the promises and potential challenges presented by mRNA therapeutics in this rapidly advancing field. Ultimately, we underscore the full potential of mRNA therapy as a game-changing therapeutic approach for neurological disorders.
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Affiliation(s)
- Edoardo Monfrini
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan 20122, Italy
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, Milan 20122, Italy
| | - Giacomo Baso
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, Milan 20122, Italy
| | - Dario Ronchi
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan 20122, Italy
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, Milan 20122, Italy
| | - Megi Meneri
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, Milan 20122, Italy
- Stroke Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan 20122, Italy
| | - Delia Gagliardi
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, Milan 20122, Italy
| | - Lorenzo Quetti
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan 20122, Italy
| | - Federico Verde
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, Milan 20122, Italy
- Department of Neurology, Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan 20149, Italy
| | - Nicola Ticozzi
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, Milan 20122, Italy
- Department of Neurology, Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan 20149, Italy
| | - Antonia Ratti
- Department of Neurology, Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan 20149, Italy
- Department Medical Biotechnology and Translational Medicine, University of Milan, Milan 20100, Italy
| | - Alessio Di Fonzo
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan 20122, Italy
| | - Giacomo P Comi
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan 20122, Italy
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, Milan 20122, Italy
| | - Linda Ottoboni
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, Milan 20122, Italy
| | - Stefania Corti
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, Milan 20122, Italy
- Department of Neuroscience, Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan 20122, Italy
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Beaudin M, Dupre N, Manto M. The importance of synthetic pharmacotherapy for recessive cerebellar ataxias. Expert Rev Neurother 2024; 24:897-912. [PMID: 38980086 DOI: 10.1080/14737175.2024.2376840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Accepted: 07/02/2024] [Indexed: 07/10/2024]
Abstract
INTRODUCTION The last decade has witnessed major breakthroughs in identifying novel genetic causes of hereditary ataxias, deepening our understanding of disease mechanisms, and developing therapies for these debilitating disorders. AREAS COVERED This article reviews the currently approved and most promising candidate pharmacotherapies in relation to the known disease mechanisms of the most prevalent autosomal recessive ataxias. Omaveloxolone is an Nrf2 activator that increases antioxidant defense and was recently approved for treatment of Friedreich ataxia. Its therapeutic effect is modest, and further research is needed to find synergistic treatments that would halt or reverse disease progression. Promising approaches include upregulation of frataxin expression by epigenetic mechanisms, direct protein replacement, and gene replacement therapy. For ataxia-telangiectasia, promising approaches include splice-switching antisense oligonucleotides and small molecules targeting oxidative stress, inflammation, and mitochondrial function. Rare recessive ataxias for which disease-modifying therapies exist are also reviewed, emphasizing recently approved therapies. Evidence supporting the use of riluzole and acetyl-leucine in recessive ataxias is discussed. EXPERT OPINION Advances in genetic therapies for other neurogenetic conditions have paved the way to implement feasible approaches with potential dramatic benefits. Particularly, as we develop effective treatments for these conditions, we may need to combine therapies, consider newborn testing for pre-symptomatic treatment, and optimize non-pharmacological approaches.
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Affiliation(s)
- Marie Beaudin
- Department of Neurology and Neurological Sciences, Stanford School of Medicine, Stanford, CA, USA
| | - Nicolas Dupre
- Neuroscience axis, CHU de Québec-Université Laval, Québec, QC, Canada
- Department of Medicine, Faculty of Medicine, Université Laval, Quebec, QC, Canada
| | - Mario Manto
- Service des Neurosciences, Université de Mons, Mons, Belgique
- Unité des Ataxies Cérébelleuses, Service de Neurologie, CHU-Charleroi, Charleroi, Belgique
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Polesel M, Wildschut MHE, Doucerain C, Kuhn M, Flace A, Sá Zanetti L, Steck AL, Wilhelm M, Ingles-Prieto A, Wiedmer T, Superti-Furga G, Manolova V, Dürrenberger F. Image-based quantification of mitochondrial iron uptake via Mitoferrin-2. Mitochondrion 2024; 78:101889. [PMID: 38692382 DOI: 10.1016/j.mito.2024.101889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 04/26/2024] [Accepted: 04/28/2024] [Indexed: 05/03/2024]
Abstract
Iron is a trace element that is critical for most living organisms and plays a key role in a wide variety of metabolic processes. In the mitochondrion, iron is involved in producing iron-sulfur clusters and synthesis of heme and kept within physiological ranges by concerted activity of multiple molecules. Mitochondrial iron uptake is mediated by the solute carrier transporters Mitoferrin-1 (SLC25A37) and Mitoferrin-2 (SLC25A28). While Mitoferrin-1 is mainly involved in erythropoiesis, the cellular function of the ubiquitously expressed Mitoferrin-2 remains less well defined. Furthermore, Mitoferrin-2 is associated with several human diseases, including cancer, cardiovascular and metabolic diseases, hence representing a potential therapeutic target. Here, we developed a robust approach to quantify mitochondrial iron uptake mediated by Mitoferrin-2 in living cells. We utilize HEK293 cells with inducible expression of Mitoferrin-2 and measure iron-induced quenching of rhodamine B[(1,10-phenanthroline-5-yl)-aminocarbonyl]benzyl ester (RPA) fluorescence and validate this assay for medium-throughput screening. This assay may allow identification and characterization of Mitoferrin-2 modulators and could enable drug discovery for this target.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Alvaro Ingles-Prieto
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Tabea Wiedmer
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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Paparella G, Stragà C, Pesenti N, Dal Molin V, Martorel GA, Merotto V, Genova C, Piazza A, Piccoli G, Panzeri E, Rufini A, Testi R, Martinuzzi A. A Pilot Phase 2 Randomized Trial to Evaluate the Safety and Potential Efficacy of Etravirine in Friedreich Ataxia Patients. CHILDREN (BASEL, SWITZERLAND) 2024; 11:958. [PMID: 39201893 PMCID: PMC11352957 DOI: 10.3390/children11080958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2024] [Revised: 08/01/2024] [Accepted: 08/07/2024] [Indexed: 09/03/2024]
Abstract
BACKGROUND A drug repositioning effort supported the possible use of the anti-HIV drug etravirine as a disease-modifying drug for Friedreich ataxia (FRDA). Etravirine increases frataxin protein and corrects the biochemical defects in cells derived from FRDA patients. Because of these findings, and since etravirine displays a favorable safety profile, we conducted a pilot open-label phase 2 clinical trial assessing the safety and potential efficacy of etravirine in FRDA patients. METHODS Thirty-five patients were stratified into three severity groups and randomized to etravirine 200 mg/day or 400 mg/day. They were treated for 4 months. Safety endpoints were the number and type of adverse events and number of dropouts. Efficacy endpoints were represented by changes in peak oxygen uptake and workload as measured by incremental exercise test, SARA score, cardiac measures, measures of QoL and disability. Data were collected 4 months before the start of the treatment (T - 4), at the start (T0), at the end (T4) and 4 months after the termination of the treatment (T + 4). RESULTS Etravirine was reasonably tolerated, and adverse events were generally mild. Four months of etravirine treatment did not significantly increase the peak oxygen uptake but was associated with a change in the progression of the SARA score (p value < 0.001), compared to the 4 months pre- and post-treatment. It also significantly increased peak workload (p value = 0.021). No changes in the cardiac measures were observed. Health and QoL measures showed a worsening at the suspension of the drug. CONCLUSIONS In this open trial etravirine treatment was safe, reasonably well tolerated and appreciably improved neurological function and exercise performance. Even though a placebo effect cannot be ruled out, these results suggest that etravirine may represent a potential therapeutic agent in FRDA deserving testing in a randomized placebo-controlled clinical trial.
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Affiliation(s)
- Gabriella Paparella
- Department of Conegliano, Scientific Institute IRCCS E. Medea, 31015 Conegliano, Treviso, Italy; (G.P.)
| | - Cristina Stragà
- Department of Conegliano, Scientific Institute IRCCS E. Medea, 31015 Conegliano, Treviso, Italy; (G.P.)
| | - Nicola Pesenti
- Department of Statistics and Quantitative Methods, Division of Biostatistics, Epidemiology and Public Health, University of Milano-Bicocca, 20126 Milan, Milan, Italy
| | - Valentina Dal Molin
- Department of Conegliano, Scientific Institute IRCCS E. Medea, 31015 Conegliano, Treviso, Italy; (G.P.)
| | - Gian Antonio Martorel
- Department of Conegliano, Scientific Institute IRCCS E. Medea, 31015 Conegliano, Treviso, Italy; (G.P.)
| | - Vasco Merotto
- Department of Conegliano, Scientific Institute IRCCS E. Medea, 31015 Conegliano, Treviso, Italy; (G.P.)
| | - Cristina Genova
- Department of Conegliano, Scientific Institute IRCCS E. Medea, 31015 Conegliano, Treviso, Italy; (G.P.)
| | - Arianna Piazza
- Department of Conegliano, Scientific Institute IRCCS E. Medea, 31015 Conegliano, Treviso, Italy; (G.P.)
| | - Giuseppe Piccoli
- Department of Conegliano, Scientific Institute IRCCS E. Medea, 31015 Conegliano, Treviso, Italy; (G.P.)
| | - Elena Panzeri
- Department of Bosisio Parini, Scientific Institute IRCCS E. Medea, 23842 Bosisio Parini, Lecco, Italy
| | - Alessandra Rufini
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Roberto Testi
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Andrea Martinuzzi
- Department of Conegliano, Scientific Institute IRCCS E. Medea, 31015 Conegliano, Treviso, Italy; (G.P.)
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