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1
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Le VT, Zhan ZJ, Vu TTP, Malik MS, Ou YY. ProtTrans and multi-window scanning convolutional neural networks for the prediction of protein-peptide interaction sites. J Mol Graph Model 2024; 130:108777. [PMID: 38642500 DOI: 10.1016/j.jmgm.2024.108777] [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: 01/10/2024] [Revised: 03/28/2024] [Accepted: 04/16/2024] [Indexed: 04/22/2024]
Abstract
This study delves into the prediction of protein-peptide interactions using advanced machine learning techniques, comparing models such as sequence-based, standard CNNs, and traditional classifiers. Leveraging pre-trained language models and multi-view window scanning CNNs, our approach yields significant improvements, with ProtTrans standing out based on 2.1 billion protein sequences and 393 billion amino acids. The integrated model demonstrates remarkable performance, achieving an AUC of 0.856 and 0.823 on the PepBCL Set_1 and Set_2 datasets, respectively. Additionally, it attains a Precision of 0.564 in PepBCL Set 1 and 0.527 in PepBCL Set 2, surpassing the performance of previous methods. Beyond this, we explore the application of this model in cancer therapy, particularly in identifying peptide interactions for selective targeting of cancer cells, and other fields. The findings of this study contribute to bioinformatics, providing valuable insights for drug discovery and therapeutic development.
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Affiliation(s)
- Van-The Le
- Department of Computer Science and Engineering, Yuan Ze University, Chung-Li, 32003, Taiwan
| | - Zi-Jun Zhan
- Department of Computer Science and Engineering, Yuan Ze University, Chung-Li, 32003, Taiwan
| | - Thi-Thu-Phuong Vu
- Graduate Program in Biomedical Informatics, Yuan Ze University, Chung-Li, 32003, Taiwan
| | - Muhammad-Shahid Malik
- Department of Computer Science and Engineering, Yuan Ze University, Chung-Li, 32003, Taiwan; Department of Computer Science and Engineering, Karakoram International University, Pakistan
| | - Yu-Yen Ou
- Department of Computer Science and Engineering, Yuan Ze University, Chung-Li, 32003, Taiwan; Graduate Program in Biomedical Informatics, Yuan Ze University, Chung-Li, 32003, Taiwan.
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2
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Żukowska J, Moss SJ, Subramanian V, Acharya KR. Molecular basis of selective amyloid-β degrading enzymes in Alzheimer's disease. FEBS J 2024; 291:2999-3029. [PMID: 37622248 DOI: 10.1111/febs.16939] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/31/2023] [Accepted: 08/22/2023] [Indexed: 08/26/2023]
Abstract
The accumulation of the small 42-residue long peptide amyloid-β (Aβ) has been proposed as a major trigger for the development of Alzheimer's disease (AD). Within the brain, the concentration of Aβ peptide is tightly controlled through production and clearance mechanisms. Substantial experimental evidence now shows that reduced levels of Aβ clearance are present in individuals living with AD. This accumulation of Aβ can lead to the formation of large aggregated amyloid plaques-one of two detectable hallmarks of the disease. Aβ-degrading enzymes (ADEs) are major players in the clearance of Aβ. Stimulating ADE activity or expression, in order to compensate for the decreased clearance in the AD phenotype, provides a promising therapeutic target. It has been reported in mice that upregulation of ADEs can reduce the levels of Aβ peptide and amyloid plaques-in some cases, this led to improved cognitive function. Among several known ADEs, neprilysin (NEP), endothelin-converting enzyme-1 (ECE-1), insulin degrading enzyme (IDE) and angiotensin-1 converting enzyme (ACE) from the zinc metalloprotease family have been identified as important. These ADEs have the capacity to digest soluble Aβ which, in turn, cannot form the toxic oligomeric species. While they are known for their amyloid degradation, they exhibit complexity through promiscuous nature and a broad range of substrates that they can degrade. This review highlights current structural and functional understanding of these key ADEs, giving some insight into the molecular interactions that leads to the hydrolysis of peptide substrates, the crucial tasks performed by them and the potential for therapeutic use in the future.
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3
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Limorenko G, Lashuel HA. To target Tau pathologies, we must embrace and reconstruct their complexities. Neurobiol Dis 2021; 161:105536. [PMID: 34718129 DOI: 10.1016/j.nbd.2021.105536] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 10/15/2021] [Accepted: 10/21/2021] [Indexed: 10/20/2022] Open
Abstract
The accumulation of hyperphosphorylated fibrillar Tau aggregates in the brain is one of the defining hallmarks of Tauopathy diseases, including Alzheimer's disease. However, the primary events or molecules responsible for initiation of the pathological Tau aggregation and spreading remain unknown. The discovery of heparin as an effective inducer of Tau aggregation in vitro was instrumental to enabling different lines of research into the role of Tau aggregation in the pathogenesis of Tauopathies. However, recent proteomics and cryogenic electron microscopy (cryo-EM) studies have revealed that heparin-induced Tau fibrils generated in vitro do not reproduce the biochemical and ultrastructural properties of disease-associated brain-derived Tau fibrils. These observations demand that we reassess our current approaches for investigating the mechanisms underpinning Tau aggregation and pathology formation. Our review article presents an up-to-date survey and analyses of 1) the evolution of our understanding of the interactions between Tau and heparin, 2) the various structural and mechanistic models of the heparin-induced Tau aggregation, 3) the similarities and differences between brain-derived and heparin-induced Tau fibrils; and 4) emerging concepts on the biochemical and structural determinants underpinning Tau pathological heterogeneity in Tauopathies. Our analyses identify specific knowledge gaps and call for 1) embracing the complexities of Tau pathologies; 2) reassessment of current approaches to investigate, model and reproduce pathological Tau aggregation as it occurs in the brain; 3) more research towards a better understanding of the naturally-occurring cofactor molecules that are associated with Tau brain pathology initiation and propagation; and 4) developing improved approaches for in vitro production of the Tau aggregates and fibrils that recapitulate and/or amplify the biochemical and structural complexity and diversity of pathological Tau in Tauopathies. This will result in better and more relevant tools, assays, and mechanistic models, which could significantly improve translational research and the development of drugs and antibodies that have higher chances for success in the clinic.
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Affiliation(s)
- Galina Limorenko
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, École Polytechnique Federal de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Hilal A Lashuel
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, École Polytechnique Federal de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
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4
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Padilla-Zambrano HS, García-Ballestas E, Quiñones-Ossa GA, Sibaja-Perez AE, Agrawal A, Moscote-Salazar LR, Menéndez-González M. The Prion-like Properties of Amyloid-beta Peptide and Tau: Is there Any Risk of Transmitting Alzheimer's Disease During Neurosurgical Interventions? Curr Alzheimer Res 2021; 17:781-789. [PMID: 33280597 DOI: 10.2174/1567205017666201204164220] [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: 05/12/2020] [Revised: 10/10/2020] [Accepted: 10/13/2020] [Indexed: 11/22/2022]
Abstract
Recent studies have recognized similarities between the peptides involved in the neuropathology of Alzheimer's disease and prions. The Tau protein and the Amyloid β peptide represent the theoretical pillars of Alzheimer's disease development. It is probable that there is a shared mechanism for the transmission of these substances and the prion diseases development; this presumption is based on the presentation of several cases of individuals without risk factors who developed dementia decades after a neurosurgical procedure. This article aims to present the role of Aβ and Tau, which underlie the pathophysiologic mechanisms involved in the AD and their similarities with the prion diseases infective mechanisms by means of the presentation of the available evidence at molecular (in-vitro), animal, and human levels that support the controversy on whether these diseases might be transmitted in neurosurgical interventions, which may constitute a wide public health issue.
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Affiliation(s)
- Huber S Padilla-Zambrano
- Center for Biomedical Research (CIB), Faculty of Medicine, University of Cartagena, Cartagena, Colombia
| | - Ezequiel García-Ballestas
- Center for Biomedical Research (CIB), Faculty of Medicine, University of Cartagena, Cartagena, Colombia
| | | | - Andrés E Sibaja-Perez
- Center for Biomedical Research (CIB), Faculty of Medicine, University of Cartagena, Cartagena, Colombia
| | - Amit Agrawal
- Department of Neurosurgery, Narayana Medical College, Nellore, Andhra Pradesh, India
| | - Luis R Moscote-Salazar
- Neurosurgeon-Critical Care, Center for Biomedical Research (CIB), Faculty of Medicine, University of Cartagena, Cartagena de Indias, Bolivar, Colombia
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5
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Tsatsanis A, McCorkindale AN, Wong BX, Patrick E, Ryan TM, Evans RW, Bush AI, Sutherland GT, Sivaprasadarao A, Guennewig B, Duce JA. The acute phase protein lactoferrin is a key feature of Alzheimer's disease and predictor of Aβ burden through induction of APP amyloidogenic processing. Mol Psychiatry 2021; 26:5516-5531. [PMID: 34400772 PMCID: PMC8758478 DOI: 10.1038/s41380-021-01248-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 07/17/2021] [Accepted: 07/23/2021] [Indexed: 02/06/2023]
Abstract
Amyloidogenic processing of the amyloid precursor protein (APP) forms the amyloid-β peptide (Aβ) component of pathognomonic extracellular plaques of AD. Additional early cortical changes in AD include neuroinflammation and elevated iron levels. Activation of the innate immune system in the brain is a neuroprotective response to infection; however, persistent neuroinflammation is linked to AD neuropathology by uncertain mechanisms. Non-parametric machine learning analysis on transcriptomic data from a large neuropathologically characterised patient cohort revealed the acute phase protein lactoferrin (Lf) as the key predictor of amyloid pathology. In vitro studies showed that an interaction between APP and the iron-bound form of Lf secreted from activated microglia diverted neuronal APP endocytosis from the canonical clathrin-dependent pathway to one requiring ADP ribosylation factor 6 trafficking. By rerouting APP recycling to the Rab11-positive compartment for amyloidogenic processing, Lf dramatically increased neuronal Aβ production. Lf emerges as a novel pharmacological target for AD that not only modulates APP processing but provides a link between Aβ production, neuroinflammation and iron dysregulation.
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Affiliation(s)
- Andrew Tsatsanis
- grid.5335.00000000121885934The ALBORADA Drug Discovery Institute, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK ,grid.9909.90000 0004 1936 8403Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, West Yorkshire UK
| | - Andrew N. McCorkindale
- grid.1013.30000 0004 1936 834XFaculty of Medicine and Health, Charles Perkins Centre and School of Medical Sciences, University of Sydney, Camperdown, NSW Australia
| | - Bruce X. Wong
- grid.5335.00000000121885934The ALBORADA Drug Discovery Institute, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK ,grid.9909.90000 0004 1936 8403Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, West Yorkshire UK ,grid.1008.90000 0001 2179 088XMelbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC Australia
| | - Ellis Patrick
- grid.1013.30000 0004 1936 834XFaculty of Science, School of Mathematics and Statistics, University of Sydney, Camperdown, NSW Australia
| | - Tim M. Ryan
- grid.1008.90000 0001 2179 088XMelbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC Australia
| | - Robert W. Evans
- grid.7728.a0000 0001 0724 6933School of Engineering and Design, Brunel University, London, UK
| | - Ashley I. Bush
- grid.1008.90000 0001 2179 088XMelbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC Australia
| | - Greg T. Sutherland
- grid.1013.30000 0004 1936 834XFaculty of Medicine and Health, Charles Perkins Centre and School of Medical Sciences, University of Sydney, Camperdown, NSW Australia
| | - Asipu Sivaprasadarao
- grid.9909.90000 0004 1936 8403Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, West Yorkshire UK
| | - Boris Guennewig
- grid.1013.30000 0004 1936 834XFaculty of Medicine and Health, Brain and Mind Centre and School of Medical Sciences, The University of Sydney, Camperdown, NSW Australia
| | - James A. Duce
- grid.5335.00000000121885934The ALBORADA Drug Discovery Institute, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK ,grid.9909.90000 0004 1936 8403Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, West Yorkshire UK ,grid.1008.90000 0001 2179 088XMelbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC Australia
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6
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BACE1-AS prevents BACE1 mRNA degradation through the sequestration of BACE1-targeting miRNAs. J Chem Neuroanat 2019; 98:87-96. [PMID: 30959172 DOI: 10.1016/j.jchemneu.2019.04.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 04/03/2019] [Accepted: 04/04/2019] [Indexed: 12/31/2022]
Abstract
Abnormal long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) participate in the pathophysiology of Alzheimer's disease (AD). However, it remains unclear whether these two types of noncoding RNAs functionally interact and which factors mediate these interactions in AD. β-secretase 1 (BACE1) is the enzyme responsible for amyloid plaque formation, which is a central pathological feature of AD. The lncRNA BACE1-AS and some miRNAs have been implicated in the regulation of BACE1. In this study, we reveal that BACE1-AS shares many miRNA-response elements with BACE1. The overexpression of BACE1-AS results in the repression of miRNAs that target BACE1, thus preventing BACE1 mRNA from being degraded. The knockdown of BACE1-AS increases the levels of these miRNAs, thereby reducing the expression of BACE1. Thus, BACE1-AS functions as a competing endogenous RNA (ceRNA). Our results also deepen the understanding of the regulation of BACE1 by BACE1-AS. In addition to increasing the stability of BACE1 mRNA through the formation of RNA duplexes, BACE1-AS can regulate BACE1 indirectly by acting as a ceRNA. Therefore, we propose that BACE1 functions as a ceRNA and forms a network through its associations with protein-coding genes, lncRNAs and miRNAs in the pathophysiology of AD.
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Galvão F, Grokoski KC, da Silva BB, Lamers ML, Siqueira IR. The amyloid precursor protein (APP) processing as a biological link between Alzheimer's disease and cancer. Ageing Res Rev 2019; 49:83-91. [PMID: 30500566 DOI: 10.1016/j.arr.2018.11.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 11/12/2018] [Accepted: 11/26/2018] [Indexed: 01/07/2023]
Abstract
Aging is a risk factor for several illnesses, such as Alzheimer's Disease and various cancers. However, an inverse correlation between malignancies and Alzheimer's Disease has been suggested. This review addressed the potential role of non-amyloidogenic and amyloidogenic pathways of amyloid precursor protein processing as a relevant biochemical mechanism to clarify this association. Amyloidogenic and non-amyloidogenic pathways have been related to Alzheimer's Disease and certain malignancies, respectively. Several known molecules involved in APP processing, including its regulation and final products, were summarized. Among them some candidate mechanisms emerged, such as extracellular-regulated kinase (Erk) and protein kinase C (PKC). Therefore, the imbalance of APP processing may be involved with the negative correlation between cancer and Alzheimer Disease.
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8
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Young TR, Pukala TL, Cappai R, Wedd AG, Xiao Z. The Human Amyloid Precursor Protein Binds Copper Ions Dominated by a Picomolar-Affinity Site in the Helix-Rich E2 Domain. Biochemistry 2018; 57:4165-4176. [DOI: 10.1021/acs.biochem.8b00572] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Tessa R. Young
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Tara L. Pukala
- Discipline of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Roberto Cappai
- Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Anthony G. Wedd
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Zhiguang Xiao
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
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9
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Southam KA, Stennard F, Pavez C, Small DH. Knockout of Amyloid β Protein Precursor (APP) Expression Alters Synaptogenesis, Neurite Branching and Axonal Morphology of Hippocampal Neurons. Neurochem Res 2018; 44:1346-1355. [PMID: 29572646 DOI: 10.1007/s11064-018-2512-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/15/2018] [Accepted: 03/20/2018] [Indexed: 12/23/2022]
Abstract
The function of the β-A4 amyloid protein precursor (APP) of Alzheimer's disease (AD) remains unclear. APP has a number of putative roles in neuronal differentiation, survival, synaptogenesis and cell adhesion. In this study, we examined the development of axons, dendrites and synapses in cultures of hippocampus neutrons derived from APP knockout (KO) mice. We report that loss of APP function reduces the branching of cultured hippocampal neurons, resulting in reduced synapse formation. Using a compartmentalised culture approach, we found reduced axonal outgrowth in cultured hippocampal neurons and we also identified abnormal growth characteristics of isolated hippocampal neuron axons. Although APP has previously been suggested to play an important role in promoting cell adhesion, we surprisingly found that APPKO hippocampal neurons adhered more strongly to a poly-L-lysine substrate and their neurites displayed an increased density of focal adhesion puncta. The findings suggest that the function of APP has an important role in both dendritic and axonal growth and that endogenous APP may regulate substrate adhesion of hippocampal neurons. The results may explain neuronal and synaptic morphological abnormalities in APPKO mice and the presence of abnormal APP expression in dystrophic neurites around amyloid deposits in AD.
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Affiliation(s)
- Katherine A Southam
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, 7000, Australia. .,Faculty of Health, School of Medicine, University of Tasmania, 17 Liverpool Street, Hobart, TAS, 7000, Australia.
| | - Fiona Stennard
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, 7000, Australia
| | - Cassandra Pavez
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, 7000, Australia
| | - David H Small
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, 7000, Australia
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10
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The amyloid precursor protein derivative, APP96-110, is efficacious following intravenous administration after traumatic brain injury. PLoS One 2018; 13:e0190449. [PMID: 29320530 PMCID: PMC5761886 DOI: 10.1371/journal.pone.0190449] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Accepted: 12/14/2017] [Indexed: 12/31/2022] Open
Abstract
Following traumatic brain injury (TBI) neurological damage is ongoing through a complex cascade of primary and secondary injury events in the ensuing minutes, days and weeks. The delayed nature of secondary injury provides a valuable window of opportunity to limit the consequences with a timely treatment. Recently, the amyloid precursor protein (APP) and its derivative APP96-110 have shown encouraging neuroprotective activity following TBI following an intracerebroventricular administration. Nevertheless, its broader clinical utility would be enhanced by an intravenous (IV) administration. This study assessed the efficacy of IV APP96-110, where a dose-response for a single dose of 0.005mg/kg– 0.5mg/kg APP96-110 at either 30 minutes or 5 hours following moderate-severe diffuse impact-acceleration injury was performed. Male Sprague-Dawley rats were assessed daily for 3 or 7 days on the rotarod to examine motor outcome, with a separate cohort of animals utilised for immunohistochemistry analysis 3 days post-TBI to assess axonal injury and neuroinflammation. Animals treated with 0.05mg/kg or 0.5mg/kg APP96-110 after 30 minutes demonstrated significant improvements in motor outcome. This was accompanied by a reduction in axonal injury and neuroinflammation in the corpus callosum at 3 days post-TBI, whereas 0.005mg/kg had no effect. In contrast, treatment with 0.005m/kg or 0.5mg/kg APP96-110 at 5 hours post-TBI demonstrated significant improvements in motor outcome over 3 days, which was accompanied by a reduction in axonal injury in the corpus callosum. This demonstrates that APP96-110 remains efficacious for up to 5 hours post-TBI when administered IV, and supports its development as a novel therapeutic compound following TBI.
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Pawlowski M, Meuth SG, Duning T. Cerebrospinal Fluid Biomarkers in Alzheimer's Disease-From Brain Starch to Bench and Bedside. Diagnostics (Basel) 2017; 7:diagnostics7030042. [PMID: 28703785 PMCID: PMC5617942 DOI: 10.3390/diagnostics7030042] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 06/21/2017] [Accepted: 07/06/2017] [Indexed: 12/13/2022] Open
Abstract
Alzheimer’s disease is the most common cause of dementia. Over the last three decades, research has advanced dramatically and provided a detailed understanding of the molecular events underlying the pathogenesis of Alzheimer’s disease. In parallel, assays for the detection of biomarkers that reflect the typical Alzheimer’s disease-associated pathology have been developed and validated in myriads of clinical studies. Such biomarkers complement clinical diagnosis and improve diagnostic accuracy. The use of biomarkers will become even more important with the advent of disease-modifying therapies. Such therapies will likely be most beneficial when administered early in the disease course. Here, we summarise the development of the core Alzheimer’s disease cerebrospinal fluid biomarkers: amyloid-β and tau. We provide an overview of their role in cellular physiology and Alzheimer’s disease pathology, and embed their development as cerebrospinal fluid biomarkers into the historical context of Alzheimer’s disease research. Finally, we summarise recommendations for their use in clinical practice, and outline perspectives for novel cerebrospinal fluid candidate biomarkers.
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Affiliation(s)
- Matthias Pawlowski
- Department of Neurology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, Münster 48149, Germany.
| | - Sven G Meuth
- Department of Neurology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, Münster 48149, Germany.
| | - Thomas Duning
- Department of Neurology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, Münster 48149, Germany.
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12
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Oliveira J, Costa M, de Almeida MSC, da Cruz e Silva OA, Henriques AG. Protein Phosphorylation is a Key Mechanism in Alzheimer’s Disease. J Alzheimers Dis 2017; 58:953-978. [DOI: 10.3233/jad-170176] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Joana Oliveira
- Department of Medical Sciences, Neuroscience and Signalling Laboratory, iBiMED, University of Aveiro, Aveiro, Portugal
| | - Márcio Costa
- Department of Medical Sciences, Neuroscience and Signalling Laboratory, iBiMED, University of Aveiro, Aveiro, Portugal
| | | | - Odete A.B. da Cruz e Silva
- Department of Medical Sciences, Neuroscience and Signalling Laboratory, iBiMED, University of Aveiro, Aveiro, Portugal
| | - Ana Gabriela Henriques
- Department of Medical Sciences, Neuroscience and Signalling Laboratory, iBiMED, University of Aveiro, Aveiro, Portugal
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13
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Plummer S, Van den Heuvel C, Thornton E, Corrigan F, Cappai R. The Neuroprotective Properties of the Amyloid Precursor Protein Following Traumatic Brain Injury. Aging Dis 2016; 7:163-79. [PMID: 27114849 PMCID: PMC4809608 DOI: 10.14336/ad.2015.0907] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 09/07/2015] [Indexed: 01/16/2023] Open
Abstract
Despite the significant health and economic burden that traumatic brain injury (TBI) places on society, the development of successful therapeutic agents have to date not translated into efficacious therapies in human clinical trials. Injury to the brain is ongoing after TBI, through a complex cascade of primary and secondary injury events, providing a valuable window of opportunity to help limit and prevent some of the severe consequences with a timely treatment. Of note, it has been suggested that novel treatments for TBI should be multifactorial in nature, mimicking the body's own endogenous repair response. Whilst research has historically focused on the role of the amyloid precursor protein (APP) in the pathogenesis of Alzheimer's disease, recent advances in trauma research have demonstrated that APP offers considerable neuroprotective properties following TBI, suggesting that APP is an ideal therapeutic candidate. Its acute upregulation following TBI has been shown to serve a beneficial role following trauma and has lead to significant advances in understanding the neuroprotective and neurotrophic functions of APP and its metabolites. Research has focused predominantly on the APP derivative sAPPα, which has consistently demonstrated neuroprotective and neurotrophic functions both in vitro and in vivo following various traumatic insults. Its neuroprotective activity has been narrowed down to a 15 amino acid sequence, and this region is linked to both heparan binding and growth-factor-like properties. It has been proposed that APP binds to heparan sulfate proteoglycans to exert its neuroprotective action. APP presents us with a novel therapeutic compound that could overcome many of the challenges that have stalled development of efficacious TBI treatments previously.
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Affiliation(s)
- Stephanie Plummer
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Corinna Van den Heuvel
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Emma Thornton
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Frances Corrigan
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Roberto Cappai
- Department of Pathology, the University of Melbourne, Victoria, Australia
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14
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Gonçalves R, Vasques J, Trindade P, Serfaty C, Campello-Costa P, Faria-Melibeu A. Nicotine-induced plasticity in the retinocollicular pathway: Evidence for involvement of amyloid precursor protein. Neuroscience 2016; 313:1-9. [DOI: 10.1016/j.neuroscience.2015.11.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/12/2015] [Accepted: 11/13/2015] [Indexed: 10/22/2022]
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15
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Dawkins E, Gasperini R, Hu Y, Cui H, Vincent AJ, Bolós M, Young KM, Foa L, Small DH. The N-terminal fragment of the β-amyloid precursor protein of Alzheimer's disease (N-APP) binds to phosphoinositide-rich domains on the surface of hippocampal neurons. J Neurosci Res 2014; 92:1478-89. [PMID: 24916405 DOI: 10.1002/jnr.23422] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 04/22/2014] [Accepted: 05/09/2014] [Indexed: 11/11/2022]
Abstract
The function of the β-amyloid precursor protein (APP) of Alzheimer's disease is poorly understood. The secreted ectodomain fragment of APP (sAPPα) can be readily cleaved to produce a small N-terminal fragment (N-APP) that contains heparin-binding and metal-binding domains and that has been found to have biological activity. In the present study, we examined whether N-APP can bind to lipids. We found that N-APP binds selectively to phosphoinositides (PIPs) but poorly to most other lipids. Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2 )-rich microdomains were identified on the extracellular surface of neurons and glia in primary hippocampal cultures. N-APP bound to neurons and colocalized with PIPs on the cell surface. Furthermore, the binding of N-APP to neurons increased the level of cell-surface PI(4,5)P2 and phosphatidylinositol 3,4,5-trisphosphate. However, PIPs were not the principal cell-surface binding site for N-APP, because N-APP binding to neurons was not inhibited by a short-acyl-chain PIP analogue, and N-APP did not bind to glial cells which also possessed PI(4,5)P2 on the cell surface. The data are explained by a model in which N-APP binds to two distinct components on neurons, one of which is an unidentified receptor and the second of which is a PIP lipid, which binds more weakly to a distinct site within N-APP. Our data provide further support for the idea that N-APP may be an important mediator of APP's biological activity.
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Affiliation(s)
- Edgar Dawkins
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia
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16
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Dawkins E, Small DH. Insights into the physiological function of the β-amyloid precursor protein: beyond Alzheimer's disease. J Neurochem 2014; 129:756-69. [PMID: 24517464 PMCID: PMC4314671 DOI: 10.1111/jnc.12675] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 02/02/2014] [Accepted: 02/03/2014] [Indexed: 12/21/2022]
Abstract
The β-amyloid precursor protein (APP) has been extensively studied for its role as the precursor of the β-amyloid protein (Aβ) of Alzheimer's disease. However, the normal function of APP remains largely unknown. This article reviews studies on the structure, expression and post-translational processing of APP, as well as studies on the effects of APP in vitro and in vivo. We conclude that the published data provide strong evidence that APP has a trophic function. APP is likely to be involved in neural stem cell development, neuronal survival, neurite outgrowth and neurorepair. However, the mechanisms by which APP exerts its actions remain to be elucidated. The available evidence suggests that APP interacts both intracellularly and extracellularly to regulate various signal transduction mechanisms. This article reviews studies on the structure, expression and post-translational processing of β-amyloid precursor protein (APP), as well as studies on the effects of APP in vitro and in vivo. We conclude that the published data provide strong evidence that APP has a trophic function. APP is likely to be involved in neural stem cell development, neuronal survival, neurite outgrowth and neurorepair. However, the mechanisms by which APP exerts its actions remain to be elucidated. The available evidence suggests that APP interacts both intracellularly and extracellularly to regulate various signal transduction mechanisms.
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Affiliation(s)
- Edgar Dawkins
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia
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17
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Hasebe N, Fujita Y, Ueno M, Yoshimura K, Fujino Y, Yamashita T. Soluble β-amyloid Precursor Protein Alpha binds to p75 neurotrophin receptor to promote neurite outgrowth. PLoS One 2013; 8:e82321. [PMID: 24358169 PMCID: PMC3864954 DOI: 10.1371/journal.pone.0082321] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 11/01/2013] [Indexed: 11/18/2022] Open
Abstract
Background The cleavage of β-amyloid precursor protein (APP) generates multiple proteins: Soluble β-amyloid Precursor Protein Alpha (sAPPα), sAPPβ, and amyloid β (Aβ). Previous studies have shown that sAPPα and sAPPβ possess neurotrophic properties, whereas Aβ is neurotoxic. However, the underlying mechanism of the opposing effects of APP fragments remains poorly understood. In this study, we have investigated the mechanism of sAPPα-mediated neurotrophic effects. sAPPα and sAPPβ interact with p75 neurotrophin receptor (p75NTR), and sAPPα promotes neurite outgrowth. Methods and Findings First, we investigated whether APP fragments interact with p75NTR, because full-length APP and Aβ have been shown to interact with p75NTR in vitro. Both sAPPα and sAPPβ were co-immunoprecipitated with p75NTR and co-localized with p75NTR on COS-7 cells. The binding affinity of sAPPα and sAPPβ for p75NTR was confirmed by enzyme-linked immunosorbent assay (ELISA). Next, we investigated the effect of sAPPα on neurite outgrowth in mouse cortical neurons. Neurite outgrowth was promoted by sAPPα, but sAPPα was uneffective in a knockdown of p75NTR. Conclusion We conclude that p75NTR is the receptor for sAPPα to mediate neurotrophic effects.
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Affiliation(s)
- Noriko Hasebe
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
- Department of Anesthesiology and Critical Care Medicine, Graduate School of Medicine, Osaka University, Osaka, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo, Japan
| | - Yuki Fujita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo, Japan
| | - Masaki Ueno
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo, Japan
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Kazuhiro Yoshimura
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yuji Fujino
- Department of Anesthesiology and Critical Care Medicine, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo, Japan
- * E-mail:
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18
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Dezonne RS, Stipursky J, Araujo APB, Nones J, Pavão MSG, Porcionatto M, Gomes FCA. Thyroid hormone treated astrocytes induce maturation of cerebral cortical neurons through modulation of proteoglycan levels. Front Cell Neurosci 2013; 7:125. [PMID: 23964200 PMCID: PMC3740295 DOI: 10.3389/fncel.2013.00125] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 07/23/2013] [Indexed: 11/17/2022] Open
Abstract
Proper brain neuronal circuitry formation and synapse development is dependent on specific cues, either genetic or epigenetic, provided by the surrounding neural environment. Within these signals, thyroid hormones (T3 and T4) play crucial role in several steps of brain morphogenesis including proliferation of progenitor cells, neuronal differentiation, maturation, migration, and synapse formation. The lack of thyroid hormones during childhood is associated with several impair neuronal connections, cognitive deficits, and mental disorders. Many of the thyroid hormones effects are mediated by astrocytes, although the mechanisms underlying these events are still unknown. In this work, we investigated the effect of 3, 5, 3′-triiodothyronine-treated (T3-treated) astrocytes on cerebral cortex neuronal differentiation. Culture of neural progenitors from embryonic cerebral cortex mice onto T3-treated astrocyte monolayers yielded an increment in neuronal population, followed by enhancement of neuronal maturation, arborization and neurite outgrowth. In addition, real time PCR assays revealed an increase in the levels of the heparan sulfate proteoglycans, Glypican 1 (GPC-1) and Syndecans 3 e 4 (SDC-3 e SDC-4), followed by a decrease in the levels of the chondroitin sulfate proteoglycan, Versican. Disruption of glycosaminoglycan chains by chondroitinase AC or heparanase III completely abolished the effects of T3-treated astrocytes on neuronal morphogenesis. Our work provides evidence that astrocytes are key mediators of T3 actions on cerebral cortex neuronal development and identified potential molecules and pathways involved in neurite extension; which might eventually contribute to a better understanding of axonal regeneration, synapse formation, and neuronal circuitry recover.
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Affiliation(s)
- Rômulo S Dezonne
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
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19
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Abstract
Biochemical and genetic evidence establishes a central role of the amyloid precursor protein (APP) in Alzheimer disease (AD) pathogenesis. Biochemically, deposition of the β-amyloid (Aβ) peptides produced from proteolytic processing of APP forms the defining pathological hallmark of AD; genetically, both point mutations and duplications of wild-type APP are linked to a subset of early onset of familial AD (FAD) and cerebral amyloid angiopathy. As such, the biological functions of APP and its processing products have been the subject of intense investigation, and the past 20+ years of research have met with both excitement and challenges. This article will review the current understanding of the physiological functions of APP in the context of APP family members.
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Affiliation(s)
- Ulrike C Müller
- Institute for Pharmacy and Molecular Biotechnology, University of Heidelberg, D-69120 Heidelberg, Germany.
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20
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Amyloid β precursor protein as a molecular target for amyloid β--induced neuronal degeneration in Alzheimer's disease. Neurobiol Aging 2013; 34:2525-37. [PMID: 23714735 DOI: 10.1016/j.neurobiolaging.2013.04.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 04/17/2013] [Accepted: 04/20/2013] [Indexed: 11/23/2022]
Abstract
A role of amyloid β (Aβ) peptide aggregation and deposition in Alzheimer's disease (AD) pathogenesis is widely accepted. Significantly, abnormalities induced by aggregated Aβ have been linked to synaptic and neuritic degeneration, consistent with the "dying-back" pattern of degeneration that characterizes neurons affected in AD. However, molecular mechanisms underlying the toxic effect of aggregated Aβ remain elusive. In the last 2 decades, a variety of aggregated Aβ species have been identified and their toxic properties demonstrated in diverse experimental systems. Concurrently, specific Aβ assemblies have been shown to interact and misregulate a growing number of molecular effectors with diverse physiological functions. Such pleiotropic effects of aggregated Aβ posit a mayor challenge for the identification of the most cardinal Aβ effectors relevant to AD pathology. In this review, we discuss recent experimental evidence implicating amyloid β precursor protein (APP) as a molecular target for toxic Aβ assemblies. Based on a significant body of pathologic observations and experimental evidence, we propose a novel pathologic feed-forward mechanism linking Aβ aggregation to abnormalities in APP processing and function, which in turn would trigger the progressive loss of neuronal connectivity observed early in AD.
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21
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Rice HC, Young-Pearse TL, Selkoe DJ. Systematic evaluation of candidate ligands regulating ectodomain shedding of amyloid precursor protein. Biochemistry 2013; 52:3264-77. [PMID: 23597280 DOI: 10.1021/bi400165f] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Despite intense interest in the proteolysis of the β-Amyloid Precursor Protein (APP) in Alzheimer's disease, how the normal processing of this type I receptor-like glycoprotein is physiologically regulated remains ill-defined. In recent years, several candidate protein ligands for APP, including F-spondin, Reelin, β1 Integrin, Contactins, Lingo-1, and Pancortin, have been reported. However, a cognate ligand for APP that regulates its processing by α- or β-secretase has yet to be widely confirmed in multiple laboratories. Here, we developed new assays in an effort to confirm a role for one or more of these candidate ligands in regulating APP ectodomain shedding in a biologically relevant context. A comprehensive quantification of APPsα and APPsβ, the immediate products of secretase processing, in both non-neuronal cell lines and primary neuronal cultures expressing endogenous APP yielded no evidence that any of these published candidate ligands stimulate ectodomain shedding. Rather, Reelin, Lingo-1, and Pancortin-1 emerged as the most consistent ligands for significantly inhibiting ectodomain shedding. These findings led us to conduct further detailed analyses of the interactions of Reelin and Lingo-1 with APP.
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Affiliation(s)
- Heather C Rice
- Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School , Boston, Massachusetts 02115, United States
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22
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Cui H, Freeman C, Jacobson GA, Small DH. Proteoglycans in the central nervous system: role in development, neural repair, and Alzheimer's disease. IUBMB Life 2013; 65:108-20. [PMID: 23297096 DOI: 10.1002/iub.1118] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 11/20/2012] [Indexed: 12/25/2022]
Abstract
Proteoglycans (PGs) are major components of the cell surface and extracellular matrix and play critical roles in development and maintenance of the central nervous system (CNS). PGs are a family of proteins, all of which contain a core protein to which glycosaminoglycan side chains are covalently attached. PGs possess diverse physiological roles, particularly in neural development, and are also implicated in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD). The main functions of PGs in the CNS are reviewed as are the roles of PGs in brain injury and in the development or treatment of AD.
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Affiliation(s)
- Hao Cui
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia
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23
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Reinhard C, Borgers M, David G, De Strooper B. Soluble amyloid-β precursor protein binds its cell surface receptor in a cooperative fashion with glypican and syndecan proteoglycans. J Cell Sci 2013; 126:4856-61. [DOI: 10.1242/jcs.137919] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Proteolytic processing of amyloid-β precursor protein (APP) generates the amyloid-β peptide, which plays a central role in Alzheimer's disease. The physiological function of APP and its proteolytic fragments however remains barely understood. Here we show that, based on its binding characteristics, the secreted ectodomain of APP (sAPP) is a novel member of the heparin-binding growth factor superfamily. Like other members, sAPP binds in a bivalent manner to the plasma membrane with two different subdomains. The N-terminal growth factor-like domain (GFLD) is necessary and sufficient for protein-receptor binding, whereas the E2-domain mediates interaction with membrane-anchored heparan sulfate proteoglycans (HSPGs). The membrane-anchored HSPGs function as low-affinity co-receptors for sAPP and enhance the affinity to the sAPP receptor. Our findings provide a solid basis for the further identification of this receptor.
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24
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Evin G, Li QX. Platelets and Alzheimer’s disease: Potential of APP as a biomarker. World J Psychiatry 2012; 2:102-13. [PMID: 24175176 PMCID: PMC3782192 DOI: 10.5498/wjp.v2.i6.102] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 07/13/2012] [Accepted: 07/23/2012] [Indexed: 02/05/2023] Open
Abstract
Platelets are the first peripheral source of amyloid precursor protein (APP). They possess the proteolytic machinery to produce Aβ and fragments similar to those produced in neurons, and thus offer an ex-vivo model to study APP processing and changes associated with Alzheimer’s disease (AD). Platelet process APP mostly through the α-secretase pathway to release soluble APP (sAPP). They produce small amounts of Aβ, predominantly Aβ40 over Aβ42. sAPP and Aβ are stored in α-granules and are released upon platelet activation by thrombin and collagen, and agents inducing platelet degranulation. A small proportion of full-length APP is present at the platelet surface and this increases by 3-fold upon platelet activation. Immunoblotting of platelet lysates detects APP as isoforms of 130 kDa and 106-110 kDa. The ratio of these of APP isoforms is significantly lower in patients with AD and mild cognitive impairment (MCI) than in healthy controls. This ratio follows a decrease that parallels cognitive decline and can predict conversion from MCI to AD. Alterations in the levels of α-secretase ADAM10 and in the enzymatic activities of α- and β-secretase observed in platelets of patients with AD are consistent with increased processing through the amyloidogenic pathway. β-APP cleaving enzyme activity is increased by 24% in platelet membranes of patients with MCI and by 17% in those with AD. Reports of changes in platelet APP expression with MCI and AD have been promising so far and merit further investigation as the search for blood biomarkers in AD, in particular at the prodromal stage, remains a priority and a challenge.
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Affiliation(s)
- Geneviève Evin
- Geneviève Evin, Qiao-Xin Li, Department of Pathology and Mental Health Research Institute, The University of Melbourne, Parkville 3010, Australia
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25
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Abstract
Compelling evidence from in vivo model systems within the past decade shows that the APP family of proteins is important for synaptic development and function in the central and peripheral nervous systems. The synaptic role promises to be complex and multifaceted for several reasons. The three family members have overlapping and redundant functions in mammals. They have both adhesive and signaling properties and may, in principle, act as both ligands and receptors. Moreover, they bind a multitude of synapse-specific proteins, and we predict that additional interacting protein partners will be discovered. Transgenic mice with modified or abolished expression of APP and APLPs have synaptic defects that are readily apparent. Studies of the neuromuscular junction (NMJ) in these transgenic mice have revealed molecular and functional deficits in neurotransmitter release, in organization of the postsynaptic receptors, and in coordinated intercellular development. The results summarized here from invertebrate and vertebrate systems confirm that the NMJ with its accessibility, large size, and homogeneity provides a model synapse for identifying and analyzing molecular pathways of APP actions.
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26
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Chasseigneaux S, Allinquant B. Functions of Aβ, sAPPα and sAPPβ : similarities and differences. J Neurochem 2011; 120 Suppl 1:99-108. [PMID: 22150401 DOI: 10.1111/j.1471-4159.2011.07584.x] [Citation(s) in RCA: 159] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Amyloid peptide (Aβ) is derived from the cleavage of amyloid precursor protein (APP), which also generates the soluble peptide APPβ (sAPPβ). An antagonist and major APP metabolic pathway involves cleavage by alpha secretase, which releases sAPPα. Although soluble Aβ oligomers are neurotoxic, Aβ monomers share similar properties with sAPPα. These include neurotrophic and neuroprotective effects, as well as stimulation of neural-progenitor proliferation. The properties of Aβ monomers and the neurotrophic capacity of sAPPβ to stimulate axonal outgrowth suggest that Aβ production is not deleterious per se. Consequently, therapeutic strategies for Alzheimer's disease that are targeted at Aβ-cleaving enzymes should modulate rather than inhibit Aβ generation. These strategies should focus on the factors that induce the conversion of Aβ monomers into toxic soluble oligomers. Another interesting therapeutic approach is to focus on the mechanisms of the different properties of sAPPα. Indeed, increasing sAPPα levels could shift proliferating cells towards tumorigenesis. In contrast to its neuroprotective effects, sAPPα is also able to activate microglia, leading to neurotoxicity. Understanding the mechanisms that underlie the different properties of sAPPα could therefore lead to the development of therapeutic strategies against Alzheimer's disease, which could be curative as well as preventive.
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Affiliation(s)
- Stéphanie Chasseigneaux
- INSERM UMR 894, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
| | - Bernadette Allinquant
- INSERM UMR 894, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
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27
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Cui H, Hung AC, Klaver DW, Suzuki T, Freeman C, Narkowicz C, Jacobson GA, Small DH. Effects of heparin and enoxaparin on APP processing and Aβ production in primary cortical neurons from Tg2576 mice. PLoS One 2011; 6:e23007. [PMID: 21829577 PMCID: PMC3146518 DOI: 10.1371/journal.pone.0023007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 07/11/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is caused by accumulation of Aβ, which is produced through sequential cleavage of β-amyloid precursor protein (APP) by the β-site APP cleaving enzyme (BACE1) and γ-secretase. Enoxaparin, a low molecular weight form of the glycosaminoglycan (GAG) heparin, has been reported to lower Aβ plaque deposition and improve cognitive function in AD transgenic mice. METHODOLOGY/PRINCIPAL FINDINGS We examined whether heparin and enoxaparin influence APP processing and inhibit Aβ production in primary cortical cell cultures. Heparin and enoxaparin were incubated with primary cortical cells derived from Tg2576 mice, and the level of APP and proteolytic products of APP (sAPPα, C99, C83 and Aβ) was measured by western blotting. Treatment of the cells with heparin or enoxaparin had no significant effect on the level of total APP. However, both GAGs decreased the level of C99 and C83, and inhibited sAPPα and Aβ secretion. Heparin also decreased the level of β-secretase (BACE1) and α-secretase (ADAM10). In contrast, heparin had no effect on the level of ADAM17. CONCLUSIONS/SIGNIFICANCE The data indicate that heparin and enoxaparin decrease APP processing via both α- and β-secretase pathways. The possibility that GAGs may be beneficial for the treatment of AD needs further study.
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Affiliation(s)
- Hao Cui
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia
- School of Pharmacy, University of Tasmania, Hobart, Tasmania, Australia
| | - Amos C. Hung
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia
| | - David W. Klaver
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Toshiharu Suzuki
- Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Craig Freeman
- Division of Immunology and Genetics, The John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | | | - Glenn A. Jacobson
- School of Pharmacy, University of Tasmania, Hobart, Tasmania, Australia
| | - David H. Small
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia
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Ori A, Wilkinson MC, Fernig DG. A systems biology approach for the investigation of the heparin/heparan sulfate interactome. J Biol Chem 2011; 286:19892-904. [PMID: 21454685 DOI: 10.1074/jbc.m111.228114] [Citation(s) in RCA: 183] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A large body of evidence supports the involvement of heparan sulfate (HS) proteoglycans in physiological processes such as development and diseases including cancer and neurodegenerative disorders. The role of HS emerges from its ability to interact and regulate the activity of a vast number of extracellular proteins including growth factors and extracellular matrix components. A global view on how protein-HS interactions influence the extracellular proteome and, consequently, cell function is currently lacking. Here, we systematically investigate the functional and structural properties that characterize HS-interacting proteins and the network they form. We collected 435 human proteins interacting with HS or the structurally related heparin by integrating literature-derived and affinity proteomics data. We used this data set to identify the topological features that distinguish the heparin/HS-interacting network from the rest of the extracellular proteome and to analyze the enrichment of gene ontology terms, pathways, and domain families in heparin/HS-binding proteins. Our analysis revealed that heparin/HS-binding proteins form a highly interconnected network, which is functionally linked to physiological and pathological processes that are characteristic of higher organisms. Therefore, we then investigated the existence of a correlation between the expansion of domain families characteristic of the heparin/HS interactome and the increase in biological complexity in the metazoan lineage. A strong positive correlation between the expansion of the heparin/HS interactome and biosynthetic machinery and organism complexity emerged. The evolutionary role of HS was reinforced by the presence of a rudimentary HS biosynthetic machinery in a unicellular organism at the root of the metazoan lineage.
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Affiliation(s)
- Alessandro Ori
- Institute of Integrative Biology and Centre for Glycobiology, University of Liverpool, Liverpool, United Kingdom
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29
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Klaver DW, Wilce MC, Cui H, Hung AC, Gasperini R, Foa L, Small DH. Is BACE1 a suitable therapeutic target for the treatment of Alzheimer's disease? Current strategies and future directions. Biol Chem 2010; 391:849-59. [DOI: 10.1515/bc.2010.089] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Abstract
Alzheimer's disease (AD) is characterized by the extracellular deposition of the β-amyloid protein (Aβ). Aβ is a fragment of a much larger precursor protein, the amyloid precursor protein (APP). Sequential proteolytic cleavage of APP by β-secretase and γ-secretase liberates Aβ from APP. The aspartyl protease BACE1 (β-site APP-cleaving enzyme 1) catalyses the rate-limiting step in the production of Aβ, and as such it is considered to be a major target for drug development in Alzheimer's disease. However, the development of a BACE1 inhibitor therapy is problematic for two reasons. First, BACE1 has been found to have important physiological roles. Therefore, inhibition of the enzyme could have toxic consequences. Second, the active site of BACE1 is relatively large, and many of the bulky compounds that are needed to inhibit BACE1 activity are unlikely to cross the blood-brain barrier. This review focuses on the structure BACE1, current therapeutic strategies based on developing active-site inhibitors, and new approaches to therapy involving targeting the expression or post-translational regulation of BACE1.
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30
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Klaver DW, Wilce MCJ, Gasperini R, Freeman C, Juliano JP, Parish C, Foa L, Aguilar MI, Small DH. Glycosaminoglycan-induced activation of the β-secretase (BACE1) of Alzheimer’s disease. J Neurochem 2010; 112:1552-61. [DOI: 10.1111/j.1471-4159.2010.06571.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Zhang H, Ding J, Tian W, Wang L, Huang L, Ruan Y, Lu T, Sha Y, Zhang D. Ganglioside GM1 binding the N-terminus of amyloid precursor protein. Neurobiol Aging 2008; 30:1245-53. [PMID: 18077059 DOI: 10.1016/j.neurobiolaging.2007.11.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 10/29/2007] [Accepted: 11/03/2007] [Indexed: 11/24/2022]
Abstract
Secreted amyloid precursor protein (APPs) plays a role in several neuronal functions, including the promotion of synaptogenesis, neurite outgrowth and neuroprotection. Previous study has demonstrated that ganglioside GM1 inhibits the secretion of APPs; however the underlying mechanism remains unknown. Here we reported that GM1 can bind cellular full length APP and APPs secreted from APP(695) stably-transfected SH-SY5Y cells. To characterize the GM1-APP interaction further, we expressed and purified recombinant fragments of the N-terminal APP. Immunoprecipitation experiments revealed that GM1 was able to bind the recombinant APP(18-81) fragment. Moreover, the synthetic peptide APP(52-81) could inhibit the binding. Therefore, the binding site for GM1 appears to be located within residues 52-81 of APP. Furthermore, we found that only GM1, but not GD1a, GT1b and ceramide, binds APP-N-terminus, indicating that the specific binding depends on the sugar moiety of GM1. Fluorescent studies revealed a decrease in the intrinsic fluorescence intensity of the APP(52-81) peptide in phosphatidylcholine (PC)/GM1 vesicles. By using FTIR techniques, we found that the major secondary structure of the APP(52-81) peptide was altered in PC/GM1 vesicles. Our results demonstrate that GM1 binds the N-terminus of APP and induces a conformational change. These findings suggest that secreted APP is decreased by membrane GM1 binding to its precursor protein and provide a possible molecular mechanism to explain the involvement of GM1 in APP proteolysis and pathogenesis of Alzheimer's disease.
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Affiliation(s)
- Handi Zhang
- Institute of Mental Health, Peking University, Key Laboratories for Mental Health, Ministry of Health, Beijing, China
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Turner PR, Bourne K, Garama D, Carne A, Abraham WC, Tate WP. Production, purification and functional validation of human secreted amyloid precursor proteins for use as neuropharmacological reagents. J Neurosci Methods 2007; 164:68-74. [PMID: 17537517 DOI: 10.1016/j.jneumeth.2007.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 03/30/2007] [Accepted: 04/02/2007] [Indexed: 11/21/2022]
Abstract
The secreted fragment of the amyloid precursor protein (sAPPalpha) generated following cleavage by alpha-secretase is an important mediator of cell function and is both neurotrophic and neuroprotective. HEK 293T cells have been stably integrated with a fragment of the APP gene to produce and secrete either sAPPalpha, or the alternative cleavage product sAPPbeta. Heparin binding domains on the proteins have been utilised to develop a one-step fast-performance-liquid-chromatography (FPLC) purification of sAPPs from the conditioned media. Immunoblotting analyses with a sAPP specific antibody coupled with highly sensitive silver staining techniques have validated the expression and purification strategy. Functional activity of the purified fragments was demonstrated by their ability to protect COS-7 and SH-SY5Y (neuroblastoma) cells against the adverse effects of glucose deprivation in a cell viability assay. The purified sAPPs also activated the NFkappaB transcription factor in COS-7 cells transfected with a luciferase reporter plasmid, with sAPPalpha the more potent activator as expected. The simple protocol to produce these mammalian expressed proteins will facilitate their use as potential neuropharmacological reagents in the elucidation of biochemical pathways modulated by sAPPs, and in the study of Alzheimer's disease mechanisms in general.
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Affiliation(s)
- Paul R Turner
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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Bjelik A, Pákáski M, Bereczki E, Gonda S, Juhász A, Rimanóczy A, Zana M, Janka Z, Sántha M, Kálmán J. APP mRNA splicing is upregulated in the brain of biglycan transgenic mice. Neurochem Int 2007; 50:1-4. [PMID: 16962684 DOI: 10.1016/j.neuint.2006.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 07/06/2006] [Accepted: 07/14/2006] [Indexed: 12/01/2022]
Abstract
Many of the risk factors for cerebrovascular disease and atherosclerosis also increase the risk of Alzheimer's disease, characterized by the cerebral deposition of beta-amyloid plaques resulting from the abnormal processing of the transmembrane amyloid precursor protein (APP). The initiating event of cholesterol-induced atherosclerosis is the retention and accumulation of atherogenic apolipoprotein B (apoB) together with low-density lipoproteins in the vascular intima. Biglycan, a member of the small leucine-rich protein family, was suspected of contributing to this process. The individual and combined overexpressions of biglycan and apoB-100 were therefore examined on the cortical APP mRNA levels of transgenic mice by means of semiquantitative PCR. As compared with the control littermates, transgenic biglycan mice had significantly increased cortical APP695 (122%) and APP770 (157%) mRNA levels, while the double transgenic (apoB(+/-)xbiglycan(+/-)) mice did not exhibit any changes. These results provide the first experimental evidence that the atherogenic risk factor biglycan alters APP splicing and may participate in the pathogenesis of both Alzheimer and vascular dementias.
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Affiliation(s)
- Annamária Bjelik
- Alzheimer's Disease Research Centre, Department of Psychiatry, Albert Szent-Györgyi Center for Medical and Pharmaceutical Sciences, University of Szeged, 6 Semmelweis u., Szeged H-6725, Hungary.
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Gralle M, Oliveira CLP, Guerreiro LH, McKinstry WJ, Galatis D, Masters CL, Cappai R, Parker MW, Ramos CHI, Torriani I, Ferreira ST. Solution Conformation and Heparin-induced Dimerization of the Full-length Extracellular Domain of the Human Amyloid Precursor Protein. J Mol Biol 2006; 357:493-508. [PMID: 16436282 DOI: 10.1016/j.jmb.2005.12.053] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 09/19/2005] [Accepted: 12/14/2005] [Indexed: 11/24/2022]
Abstract
Proteolytic cleavage of the amyloid precursor protein (APP) by beta and gamma-secretases gives rise to the beta-amyloid peptide, considered to be a causal factor in Alzheimer's disease. Conversely, the soluble extracellular domain of APP (sAPPalpha), released upon its cleavage by alpha-secretase, plays a number of important physiological functions. Several APP fragments have been structurally characterized at atomic resolution, but the structures of intact APP and of full-length sAPPalpha have not been determined. Here, ab initio reconstruction of molecular models from high-resolution solution X-ray scattering (SAXS) data for the two main isoforms of sAPPalpha (sAPPalpha(695) and sAPPalpha(770)) provided models of sufficiently high resolution to identify distinct structural domains of APP. The fragments for which structures are known at atomic resolution were fitted within the solution models of full-length sAPPalpha, allowing localization of important functional sites (i.e. glycosylation, protease inhibitory and heparin-binding sites). Furthermore, combined results from SAXS, analytical ultracentrifugation (AUC) and size-exclusion chromatography (SEC) analysis indicate that both sAPPalpha isoforms are monomeric in solution. On the other hand, SEC, bis-ANS fluorescence, AUC and SAXS measurements showed that sAPPalpha forms a 2:1 complex with heparin. A conformational model for the sAPPalpha:heparin complex was also derived from the SAXS data. Possible implications of such complex formation for the physiological dimerization of APP and biological signaling are discussed in terms of the structural models proposed.
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Affiliation(s)
- Matthias Gralle
- Instituto de Bioquímica Médica, Programa de Bioquímica e Biofísica Celular, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21944-590, Brazil
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36
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Trinkaus-Randall V, Walsh MT, Steeves S, Monis G, Connors LH, Skinner M. Cellular response of cardiac fibroblasts to amyloidogenic light chains. THE AMERICAN JOURNAL OF PATHOLOGY 2005; 166:197-208. [PMID: 15632012 PMCID: PMC1602293 DOI: 10.1016/s0002-9440(10)62244-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Amyloidoses are a group of disorders characterized by abnormal folding of proteins that impair organ function. We investigated the cellular response of primary cardiac fibroblasts to amyloidogenic light chains and determined the corresponding change in proteoglycan expression and localization. The cellular response to 11 urinary immunoglobulin light chains of kappa1, lambda6, and lambda 3 subtypes was evaluated. The localization of the light chains was monitored by conjugating them to Oregon Green 488 and performing live cell confocal microscopy. Sulfation of the proteoglycans was determined after elution over Q1-columns with a single-step salt gradient (1.5 mol/L NaCl) via dimethylmethylene blue. Light chains were detected inside cells within 4 hours and demonstrated perinuclear localization. Over 80% of the cells showed intracellular localization of the amyloid light chains. The light chains induced sulfation of the secreted glycosaminoglycans, but the cell fraction possessed only minimal sulfation. Furthermore, the light chains caused a translocation of heparan sulfate proteoglycan to the nucleus. The conformation and thermal stability of light chains was altered when they were incubated in the presence of heparan sulfate and destabilization of the amyloid light chains was detected. These studies indicate that internalization of the light chains mediates the expression and localization of heparan sulfate proteoglycans.
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Affiliation(s)
- Vickery Trinkaus-Randall
- Department of Biochemistry, Boston University School of Medicine, L904, 80 E. Concord Street, Boston, MA 02118, USA.
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Herms J, Anliker B, Heber S, Ring S, Fuhrmann M, Kretzschmar H, Sisodia S, Müller U. Cortical dysplasia resembling human type 2 lissencephaly in mice lacking all three APP family members. EMBO J 2004; 23:4106-15. [PMID: 15385965 PMCID: PMC524337 DOI: 10.1038/sj.emboj.7600390] [Citation(s) in RCA: 251] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2004] [Accepted: 08/09/2004] [Indexed: 11/09/2022] Open
Abstract
The Alzheimer's disease beta-amyloid precursor protein (APP) is a member of a larger gene family that includes the amyloid precursor-like proteins, termed APLP1 and APLP2. We previously documented that APLP2-/-APLP1-/- and APLP2-/-APP-/- mice die postnatally, while APLP1-/-APP-/- mice and single mutants were viable. We now report that mice lacking all three APP/APLP family members survive through embryonic development, and die shortly after birth. In contrast to double-mutant animals with perinatal lethality, 81% of triple mutants showed cranial abnormalities. In 68% of triple mutants, we observed cortical dysplasias characterized by focal ectopic neuroblasts that had migrated through the basal lamina and pial membrane, a phenotype that resembles human type II lissencephaly. Moreover, at E18.5 triple mutants showed a partial loss of cortical Cajal Retzius (CR) cells, suggesting that APP/APLPs play a crucial role in the survival of CR cells and neuronal adhesion. Collectively, our data reveal an essential role for APP family members in normal brain development and early postnatal survival.
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Affiliation(s)
- Jochen Herms
- Zentrum für Neuropathologie und Prionforschung, Universität München, München, Germany
| | - Brigitte Anliker
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Frankfurt, Germany
| | - Sabine Heber
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Frankfurt, Germany
| | - Sabine Ring
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Frankfurt, Germany
| | - Martin Fuhrmann
- Zentrum für Neuropathologie und Prionforschung, Universität München, München, Germany
| | - Hans Kretzschmar
- Zentrum für Neuropathologie und Prionforschung, Universität München, München, Germany
| | - Sangram Sisodia
- Department of Neurobiology, Pharmacology and Physiology, University of Chicago, Chicago, IL, USA
| | - Ulrike Müller
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Frankfurt, Germany
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Deutschordenstr. 46, 60528 Frankfurt, Germany. Tel.: +49 69 96769 317; Fax: +49 69 96769 441; E-mail:
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Scholefield Z, Yates EA, Wayne G, Amour A, McDowell W, Turnbull JE. Heparan sulfate regulates amyloid precursor protein processing by BACE1, the Alzheimer's beta-secretase. ACTA ACUST UNITED AC 2003; 163:97-107. [PMID: 14530380 PMCID: PMC2173449 DOI: 10.1083/jcb.200303059] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cleavage of amyloid precursor protein (APP) by the Alzheimer's β-secretase (BACE1) is a key step in generating amyloid β-peptide, the main component of amyloid plaques. Here we report evidence that heparan sulfate (HS) interacts with β-site APP-cleaving enzyme (BACE) 1 and regulates its cleavage of APP. We show that HS and heparin interact directly with BACE1 and inhibit in vitro processing of peptide and APP substrates. Inhibitory activity is dependent on saccharide size and specific structural characteristics, and the mechanism of action involves blocking access of substrate to the active site. In cellular assays, HS specifically inhibits BACE1 cleavage of APP but not alternative cleavage by α-secretase. Endogenous HS immunoprecipitates with BACE1 and colocalizes with BACE1 in the Golgi complex and at the cell surface, two of its putative sites of action. Furthermore, inhibition of cellular HS synthesis results in enhanced BACE1 activity. Our findings identify HS as a natural regulator of BACE1 and suggest a novel mechanism for control of APP processing.
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Affiliation(s)
- Zoe Scholefield
- School of Biosciences, University of Birmingham, Birmingham, UK
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39
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Das A, Smalheiser NR, Markaryan A, Kaplan A. Evidence for binding of the ectodomain of amyloid precursor protein 695 and activated high molecular weight kininogen. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1571:225-38. [PMID: 12090937 DOI: 10.1016/s0304-4165(02)00256-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
To identify ligands that bind to the N-terminal portion of human amyloid precursor protein (APP), we sought binding partners for a fragment of the ectodomain of human APP695 (sAPP(695)T). The probe bound to fragments of high molecular weight kininogen (HK) in rat cortical membrane preparations in vitro. Laser confocal microscopy indicated that APP and HK colocalize near cerebral blood vessels, in the neuropil, and in many neurons of rat brain. sAPP(695)T bound to human activated kininogen (HKa) (K(d)=0.3+/-0.1 nM), but not to inactivated or low molecular weight kininogen. Binding was specific for the light chain sequence of HKa. Biotinylated human HKa also bound to sAPP(695) (K(d)=0.3+/-0.5 nM). sAPP(695) and HKa form tight complexes in solution that can be coimmunoprecipitated. These results support the hypothesis that forms of APP and kininogen can interact in brain tissue. Considering the implications of APP in neurite outgrowth, the APP-HKa interaction could modulate neurogenesis.
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Affiliation(s)
- Arpita Das
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA.
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40
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Sambamurti K, Greig NH, Lahiri DK. Advances in the cellular and molecular biology of the beta-amyloid protein in Alzheimer's disease. Neuromolecular Med 2002; 1:1-31. [PMID: 12025813 DOI: 10.1385/nmm:1:1:1] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2001] [Accepted: 10/10/2001] [Indexed: 02/08/2023]
Abstract
Alzheimer's disease (AD) is a progressive senile dementia characterized by deposition of a 4 kDa peptide of 39-42 residues known as amyloid beta-peptide (Abeta) in the form of senile plaques and the microtubule associated protein tau as paired helical filaments. Genetic studies have identified mutations in the Abeta precursor protein (APP) as the key triggers for the pathogenesis of AD. Other genes such as presenilins 1 and 2 (PS1/2) and apolipoprotein E (APOE) also play a critical role in increased Abeta deposition. Several biochemical and molecular studies using transfected cells and transgenic animals point to mechanisms by which Abeta is generated and aggregated to trigger the neurodegeneration that may cause AD. Three important enzymes collectively known as "secretases" participate in APP processing. An enzymatic activity, beta-secretase, cleaves APP on the amino side of Abeta producing a large secreted derivative, sAPPbeta, and an Abeta-bearing membrane-associated C-terminal derivative, CTFbeta, which is subsequently cleaved by the second activity, gamma-secretase, to release Abeta. Alternatively, a third activity, alpha-secretase, cleaves APP within Abeta to the secreted derivative sAPPalpha and membrane-associated CTFalpha. The predominant secreted APP derivative is sAPPalpha in most cell-types. Most of the secreted Abeta is 40 residues long (Abeta40) although a small percentage is 42 residues in length (Abeta42). However, the longer Abeta42 aggregates more readily and was therefore considered to be the pathologically important form. Advances in our understanding of APP processing, trafficking, and turnover will pave the way for better drug discovery for the eventual treatment of AD. In addition, APP gene regulation and its interaction with other proteins may provide useful drug targets for AD. The emerging knowledge related to the normal function of APP will help in determining whether or not the AD associated changes in APP metabolism affect its function. The present review summarizes our current understanding of APP metabolism and function and their relationship to other proteins involved in AD.
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Affiliation(s)
- Kumar Sambamurti
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.
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41
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Lahiri DK, Nall C, Chen D, Zaphiriou M, Morgan C, Nurnberger JI. Developmental expression of the beta-amyloid precursor protein and heat-shock protein 70 in the cerebral hemisphere region of the rat brain. Ann N Y Acad Sci 2002; 965:324-33. [PMID: 12105108 DOI: 10.1111/j.1749-6632.2002.tb04174.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Alzheimer's disease (AD) is characterized by depositions of the amyloid beta protein (A beta) in the brain in the form of extracellular plaques and cerebrovascular amyloid. A beta (approximately 4 kDa) is derived from a family of large (approximately 110 kDa) beta-amyloid precursor proteins (APP), which are integral membrane glycoproteins. Although a connection between AD and alcoholism has recently been suggested, this relationship has not been explored at the molecular level. Our hypothesis is that APP has a role in brain development and that abnormal APP levels may be involved in dementia associated with AD and alcoholism. We compared the profile of total APP levels between ethanol naïve alcohol-preferring (P) and alcohol-nonpreferring (NP) rats. We also investigated the possibility that APP levels can be regulated in an age-dependent manner in young rats. We studied the distribution of two proteins in the cerebral hemisphere region of the rat brain at various developmental periods. Six groups composed of the following different ages of rats were used: 7, 14, 21, 36, 43, and 78 (postnatal) days. Cell extracts from different regions of the brain were subjected to Western immunoblotting using mAb22C11. Our results suggest that levels of high-molecular-weight APP bands were greater in brain extracts from 7-day-old P rats than in other samples tested, and that the distribution of APP levels was more uneven in brain extracts from different ages of P than from NP rats. These initial results suggest that APP may play an important role in the early development of the rat brain and the alcohol-preferring trait may influence APP processing in the developing brain.
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Affiliation(s)
- D K Lahiri
- Laboratory of Molecular Neurogenetics, Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana 46202-4887, USA.
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42
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Abstract
The amyloid precursor protein (APP) gene and its protein products have multiple functions in the central nervous system and fulfil criteria as neuractive peptides: presence, release and identity of action. There is increased understanding of the role of secretases (proteases) in the metabolism of APP and the production of its peptide fragments. The APP gene and its products have physiological roles in synaptic action, development of the brain, and in the response to stress and injury. These functions reveal the strategic importance of APP in the workings of the brain and point to its evolutionary significance.
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Affiliation(s)
- P K Panegyres
- Department of Neuropathology, Royal Perth Hospital, Western Australia.
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44
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Park K, Verchere CB. Identification of a heparin binding domain in the N-terminal cleavage site of pro-islet amyloid polypeptide. Implications for islet amyloid formation. J Biol Chem 2001; 276:16611-6. [PMID: 11145957 DOI: 10.1074/jbc.m008423200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Islet amyloid deposits are a characteristic pathologic lesion of the pancreas in type 2 diabetes and are composed primarily of the islet beta cell peptide islet amyloid polypeptide (IAPP or amylin) as well as the basement membrane heparan sulfate proteoglycan perlecan. Impaired processing of the IAPP precursor has been implicated in the mechanism of islet amyloid formation. The N- and C-terminal cleavage sites where pro-IAPP is processed by prohormone convertases contain a series of basic amino acid residues that we hypothesized may interact with heparan sulfate proteoglycans. This possibility was tested using affinity chromatography by applying synthetic fragments of pro-IAPP to heparin-agarose and heparan sulfate-Sepharose. An N-terminal human pro-IAPP fragment (residues 1-30) was retained by both heparin-agarose and heparan sulfate-Sepharose, eluting at 0.18 m NaCl at pH 7.5. Substitution of alanine residues for two basic residues in the N-terminal cleavage site abolished heparin and heparan sulfate binding activity. At pH 5.5, the affinity of the wild-type peptide for heparin/heparan sulfate was increased, implying a role for histidine residues at positions 6 and 28 of pro-IAPP. A C-terminal pro-IAPP fragment (residues 41-67) had no specific affinity for either heparin or heparan sulfate, and the N- or C-terminal fragments had only weak affinity for chondroitin sulfate. These data suggest that monomeric N-terminal human pro-IAPP contains a heparin binding domain that is lost during normal processing of pro-IAPP.
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Affiliation(s)
- K Park
- Department of Pathology and Laboratory Medicine and the British Columbia Research Institute for Children's and Women's Health, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
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45
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Park K, Verchere CB. Identification of a Heparin Binding Domain in the N-terminal Cleavage Site of Pro-islet Amyloid Polypeptide. J Biol Chem 2001. [DOI: 10.1074/jbc.m008423200%20m008423200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Abstract
Current assumptions and conclusions in several active areas of amyloid research are examined to see how consistent the data from chosen in vitro and in vivo model systems are with clinical and anatomic observations. These areas include the assembly of amyloid-like fibrils in vitro, the nucleation phenomenon, amyloid fibril structure in vivo and in vitro, common structural components of the amyloids, and the regression of tissue amyloid and proteolysis of amyloid proteins. Divergences and congruencies are highlighted, which in turn suggests caution in the interpretation of present data, greater collaboration and communication among investigators, and, additional areas and techniques for investigation.
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Affiliation(s)
- R Kisilevsky
- Department of Pathology, Queen's University, The Syl and Molly Apps Research Center, Kingston General Hospital, Ontario, Kingston, K7L 3N6, Canada
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47
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Storey E, Cappai R. The amyloid precursor protein of Alzheimer's disease and the Abeta peptide. Neuropathol Appl Neurobiol 1999; 25:81-97. [PMID: 10215996 DOI: 10.1046/j.1365-2990.1999.00164.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Alzheimer's disease is characterized by the accumulation of beta amyloid peptides in plaques and vessel walls and by the intraneuronal accumulation of paired helical filaments composed of hyperphosphorylated tau. In this review, we concentrate on the biology of amyloid precursor protein, and on the central role of amyloid in the pathogenesis of Alzheimer's disease. Amyloid precursor protein (APP) is part of a super-family of transmembrane and secreted proteins. It appears to have a number of roles, including regulation of haemostasis and mediation of neuroprotection. APP also has potentially important metal and heparin-binding properties, and the current challenge is to synthesize all these varied activities into a coherent view of its function. Cleavage of amyloid precursor protein by beta-and gamma-secretases results in the generation of the Abeta (betaA4) peptide, whereas alpha-secretase cleaves within the Abeta sequence and prevents formation from APP. Recent findings indicate that the site of gamma-secretase cleavage is critical to the development of amyloid deposits; Abeta1-42 is much more amyloidogenic than Abeta1-40. Abeta1-42 formation is favoured by mutations in the two presenilin genes (PS1 and PS2), and by the commonest amyloid precursor protein mutations. Transgenic mouse models of Alzheimer's disease incorporating various mutations in the presenilin gene now exist, and have shown amyloid accumulation and cognitive impairment. Neurofibrillary tangles have not been reproduced in these models, however. While aggregated Abeta is neurotoxic, perhaps via an oxidative mechanism, the relationship between such toxicity and neurofibrillary tangle formation remains a subject of ongoing research.
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Affiliation(s)
- E Storey
- Van Cleef/Roet Centre for Nervous Diseases, Monash University (Alfred Hospital Campus), Prahran, Victoria, Australia
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48
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Henry A, Li QX, Galatis D, Hesse L, Multhaup G, Beyreuther K, Masters CL, Cappai R. Inhibition of platelet activation by the Alzheimer's disease amyloid precursor protein. Br J Haematol 1998; 103:402-15. [PMID: 9827912 DOI: 10.1046/j.1365-2141.1998.01005.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The amyloid precursor protein (APP) of Alzheimer's disease is abundantly expressed in the platelet alpha-granule where its role remains unclear. This study describes a novel function for APP in regulating human platelet activation. Preincubation of platelet-rich plasma with recombinant secreted APP (sAPP) isoforms dose-dependently inhibited platelet aggregation and secretion induced by ADP or adrenaline. Similarly, sAPP potently inhibited low-dose thrombin-induced activation in washed platelet suspensions, indicating that the activity does not require plasma cofactors. There were no functional differences between sAPP forms with or without the Kunitz protease inhibitor domain or derived from either alpha- or beta-secretase cleavage. In fact, the N-terminal cysteine-rich region of APP (residues 18-194) was as effective as the entire sAPP region in the inhibition of platelet activation. The inhibitory activity of sAPP correlated with a significant reduction in the agonist-induced production of the arachidonic acid (AA) metabolites thromboxane B2 and prostaglandin E2. However, sAPP did not affect AA-induced platelet aggregation or secretion, indicating the enzymatic conversion of AA was not inhibited. The addition of a threshold dose of AA reversed the sAPP-inhibition of agonist-induced platelet activation. This suggests that sAPP decreases the availability of free AA, although the mechanism is not yet known. These data provide evidence that the release of sAPP upon platelet degranulation may result in negative feedback regulation during platelet activation.
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Affiliation(s)
- A Henry
- Department of Pathology, University of Melbourne and Mental Health Research Institute of Victoria, Parkville, Australia
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49
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Abstract
Chronic low-level lead exposure is toxic to the developing nervous system. The amyloid beta precursor protein (A beta PP) plays a pivotal role in this developmental process, both as a neurotrophic/neuroprotective factor and as a mediator of cell adhesion. In this study, we have used an in vitro system to examine the interaction between chronic low-level lead and the expression and function of A beta PP. Chronic exposure of the HN9 mouse hippocampal cell line to lead chloride (10(-14) M to 10(-6) M) for 96 hours resulted in a 50% increase in the levels of the particulate form of the protein with a parallel decrease in the soluble form (A beta PP). This effect of lead was reversible following the removal of the toxin. This increase in membrane-bound A beta PP was also paralleled by an increase in cell adhesivity to a fibronectin substrate. In addition, A beta PP also acted to attenuate lead toxicity. Cells which secreted high levels of the protein were resistant to lead toxicity when compared with control cells suggesting that the protein may be acting to chelate the metal and thus attenuating its toxic action within the cell.
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Affiliation(s)
- F D Davey
- Department of Pharmacology and Neuroscience, University of Dundee, Ninewells Hospital Medical School, Scotland, UK
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50
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Postuma RB, Martins RN, Cappai R, Beyreuther K, Masters CL, Strickland DK, Mok SS, Small DH. Effects of the amyloid protein precursor of Alzheimer's disease and other ligands of the LDL receptor-related protein on neurite outgrowth from sympathetic neurons in culture. FEBS Lett 1998; 428:13-6. [PMID: 9645465 DOI: 10.1016/s0014-5793(98)00475-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The amyloid protein precursor (APP) of Alzheimer's disease can stimulate neurite outgrowth in vitro. The receptor responsible for this effect has not been identified. Kunitz protease inhibitor (KPI)-containing forms of APP bind to the low-density lipoprotein receptor-related protein (LRP). As LRP may regulate neurite outgrowth, we examined whether the effects of APP are mediated by LRP. Inhibitors of LRP decreased neurite outgrowth from chick sympathetic neurons. Most LRP ligands (alpha2-macroglobulin, lactoferrin, and lipoprotein lipase) stimulated outgrowth. However, in soluble form, the KPI-containing APP751 was a weak inhibitor of outgrowth. In substrate-bound form, both APP751 and APP695 (which does not bind to LRP) stimulated outgrowth. Thus the effect of substrate-bound APP on neurite outgrowth is not mediated by LRP.
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Affiliation(s)
- R B Postuma
- Department of Pathology, University of Melbourne, and the Mental Health Research Institute of Victoria, Parkville, Australia
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