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Mattocks DAL, Ommi NB, Malloy VL, Nichenametla SN. An antireductant approach ameliorates misfolded proinsulin-induced hyperglycemia and glucose intolerance in male Akita mice. GeroScience 2025; 47:1653-1668. [PMID: 39294474 PMCID: PMC11979071 DOI: 10.1007/s11357-024-01326-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 08/23/2024] [Indexed: 09/20/2024] Open
Abstract
Protein folding in the endoplasmic reticulum (ER) requires a high ratio of oxidized to reduced glutathione (GSSG/rGSH). Since the GSSG/rGSH depends on total glutathione (tGSH = GSSG + rGSH) levels, we hypothesized that limiting GSH biosynthesis will ameliorate protein misfolding by enhancing the ER oxidative milieu. As a proof-of-concept, we used DL-buthionine-(S,R)-sulfoximine (BSO) to inhibit GSH biosynthesis in Akita mice, which are prone to proinsulin misfolding. We conducted a 2-week intervention to investigate if BSO was safe and a 6-week intervention to find its effect on glucose intolerance. In both cohorts, male heterozygous Akita (AK) and wild-type (WT) mice were continuously administered 15 mM BSO. No adverse effects were observed on body weight, food intake, and water intake in either cohort. Unaltered levels of plasma aspartate and alanine aminotransferases, and cystatin-C, indicate that BSO was safe. BSO-induced decreases in tGSH were tissue-dependent with maximal effects in the kidneys, where it altered the expression of genes associated with GSH biosynthesis, redox status, and proteostasis. BSO treatment decreased random blood glucose levels to 80% and 67% of levels in untreated mice in short-term and long-term cohorts, respectively, and 6-h fasting blood glucose to 82% and 74% of levels in untreated mice, respectively. BSO also improved glucose tolerance by 37% in AK mice in the long-term cohort, without affecting insulin tolerance. Neither glucose tolerance nor insulin tolerance were affected in WT. Data indicate that BSO might treat misfolded proinsulin-induced glucose intolerance. Future studies should investigate the effect of BSO on proinsulin misfolding and if it improves glucose intolerance in individuals with Mutant Insulin Diabetes of Youth.
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Affiliation(s)
- Dwight A L Mattocks
- Animal Science Laboratory, Orentreich Foundation for the Advancement of Science Inc., 855, Route 301, Cold Spring-on-Hudson, NY, 10516, USA
| | - Naidu B Ommi
- Animal Science Laboratory, Orentreich Foundation for the Advancement of Science Inc., 855, Route 301, Cold Spring-on-Hudson, NY, 10516, USA
| | - Virginia L Malloy
- Animal Science Laboratory, Orentreich Foundation for the Advancement of Science Inc., 855, Route 301, Cold Spring-on-Hudson, NY, 10516, USA
| | - Sailendra N Nichenametla
- Animal Science Laboratory, Orentreich Foundation for the Advancement of Science Inc., 855, Route 301, Cold Spring-on-Hudson, NY, 10516, USA.
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2
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Zavarzadeh PG, Panchal K, Bishop D, Gilbert E, Trivedi M, Kee T, Ranganathan S, Arunagiri A. Exploring proinsulin proteostasis: insights into beta cell health and diabetes. Front Mol Biosci 2025; 12:1554717. [PMID: 40109403 PMCID: PMC11919908 DOI: 10.3389/fmolb.2025.1554717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2025] [Accepted: 02/13/2025] [Indexed: 03/22/2025] Open
Abstract
Proinsulin misfolding is central to diabetes. This review examines the cellular mechanisms regulating proinsulin proteostasis in pancreatic β-cells, encompassing genetic factors such as insulin gene mutations, and exploring the roles of endoplasmic reticulum (ER) stress and the unfolded protein response (UPR), ER redox balance, mitochondrial function, and the influence of extrinsic factors. Mutations in the INS gene, particularly those affecting cysteine residues, impair folding and disulfide bond formation, often exhibiting dominant-negative effects on the wild-type proinsulin. The importance of ER quality control mechanisms, including chaperones and oxidoreductases, in facilitating proper folding and degradation of misfolded proinsulin is emphasized. Disruptions in these systems, due to genetic mutations, ER stress, or impaired ER-to-Golgi trafficking, lead to proinsulin accumulation and β-cell dysfunction. The unfolded protein response (UPR), especially the PERK and IRE1α-XBP1 pathways, emerges as a central regulator of protein synthesis and ER stress management. The review also discusses the role of mitochondrial health, ER redox state, and extrinsic factors such as diet and medications in influencing proinsulin proteostasis. Finally, the structural insights from NMR and molecular dynamics simulations are discussedhighlighting the dynamics of misfolding and underscoring the importance of disulfide bonds. These mechanistic insights suggest innovative strategies targeting thiol/disulfide redox systems in cells to mitigate protein misfolding diseases including diabetes.
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Affiliation(s)
| | - Kathigna Panchal
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, United States
| | - Dylan Bishop
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, United States
| | - Elizabeth Gilbert
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, United States
| | - Mahi Trivedi
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, United States
| | - Tovaria Kee
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, United States
| | | | - Anoop Arunagiri
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, United States
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3
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Madey YF, Syed SK, Van Horn RD, Pineros AR, Efanov AM. Aggregated proinsulin in pancreatic β-cells is degraded by the autophagy pathway. J Biol Chem 2025; 301:108257. [PMID: 39909373 PMCID: PMC11910096 DOI: 10.1016/j.jbc.2025.108257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2024] [Revised: 01/21/2025] [Accepted: 01/24/2025] [Indexed: 02/07/2025] Open
Abstract
Insulin, a critical metabolic hormone to maintain blood glucose homeostasis, is synthesized and folded in the endoplasmic reticulum (ER) of pancreatic β-cells as the insulin precursor proinsulin (ProIns). ProIns misfolding and aggregation detected in diabetic β-cells induces ER stress and obstructs normal trafficking, processing, and secretion of insulin, which eventually can result in pancreatic β-cell dedifferentiation and death. We have developed quantitative methods to measure misfolded and aggregated ProIns in β-cells by utilizing ProIns oligomer-specific ELISA and proximity ligation assay. Under conditions of induced ER stress, both assays detected significant accumulation of aggregated ProIns in β-cells. ProIns aggregation was also observed in isolated pancreatic islets cultured at high glucose levels. Moreover, high glucose in β-cells downregulated expression of genes mediating clearance of misfolded proteins from the secretory pathway through ER autophagy and ER-associated protein degradation. Inhibition of autophagy in β-cells induced strong induction of misfolded ProIns accumulation, whereas ER-associated degradation inhibition was not effective in generating ProIns aggregates. Finally, we observed subcellular colocalization of aggregated ProIns with protein markers of autophagosomes. Our results indicate that autophagy controls degradation of aggregated misfolded ProIns under conditions of hyperglycemia and diabetes.
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Affiliation(s)
- Yueh-Fu Madey
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA
| | - Samreen K Syed
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA
| | | | - Annie R Pineros
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA
| | - Alexander M Efanov
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA.
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Urbaniak E, Henry S, Lalowski M, Borowiak M. Molecular puzzle of insulin: structural assembly pathways and their role in diabetes. Front Cell Dev Biol 2025; 13:1502469. [PMID: 40052150 PMCID: PMC11882602 DOI: 10.3389/fcell.2025.1502469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2024] [Accepted: 02/03/2025] [Indexed: 03/09/2025] Open
Abstract
Properly folded proteins are essential for virtually all cellular processes including enzyme catalysis, signal transduction, and structural support. The cells have evolved intricate mechanisms of control, such as the assistance of chaperones and proteostasis networks, to ensure that proteins mature and fold correctly and maintain their functional conformations. Here, we review the mechanisms governing the folding of key hormonal regulators or glucose homeostasis. The insulin synthesis in pancreatic β-cells begins with preproinsulin production. During translation, the insulin precursor involves components of the endoplasmic reticulum (ER) translocation machinery, which are essential for proper orientation, translocation, and cleavage of the signal peptide of preproinsulin. These steps are critical to initiate the correct folding of proinsulin. Proinsulin foldability is optimized in the ER, an environment evolved to support the folding process and the formation of disulfide bonds while minimizing misfolding. This environment is intricately linked to ER stress response pathways, which have both beneficial and potentially harmful effects on pancreatic β-cells. Proinsulin misfolding can result from excessive biosynthetic ER load, proinsulin gene mutations, or genetic predispositions affecting the ER folding environment. Misfolded proinsulin leads to deficient insulin production and contributes to diabetes pathogenesis. Understanding the mechanisms of protein folding is critical for addressing diabetes and other protein misfolding-related diseases.
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Affiliation(s)
- Edyta Urbaniak
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
| | - Sara Henry
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
| | - Maciej Lalowski
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
- Meilahti Clinical Proteomics Core Facility, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Malgorzata Borowiak
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
- Center for Cell and Gene Therapy, Stem Cell and Regenerative Medicine Center, Baylor College of Medicine, Texas Children’s Hospital, Methodist Hospital, Houston, TX, United States
- McNair Medical Institute, Baylor College of Medicine, Houston, TX, United States
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Srivastava N, Vomund AN, Peterson OJ, Abousaway O, Li T, Kain L, Stone P, Clement CC, Sharma S, Zhang B, Liu C, Joglekar AV, Campisi L, Hsieh CS, Santambrogio L, Teyton L, Arbelaez AM, Lichti CF, Wan X. A post-translational cysteine-to-serine conversion in human and mouse insulin generates a diabetogenic neoepitope. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.11.07.622538. [PMID: 39605669 PMCID: PMC11601459 DOI: 10.1101/2024.11.07.622538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2024]
Abstract
Type 1 diabetes (T1D) affects a genetically susceptible population that develops autoreactive T cells attacking insulin-producing pancreatic β cells. Increasingly, neoantigens are recognized as critical drivers of this autoimmune response. Here, we report a novel insulin neoepitope generated via post-translational cysteine-to-serine conversion (C>S) in human patients, which is also seen in the autoimmune-prone non-obese diabetic (NOD) mice. This modification is driven by oxidative stress within the microenvironment of pancreatic β cells and is further amplified by T1D-relevant inflammatory cytokines, enhancing neoantigen formation in both pancreatic β cells and dendritic cells. We discover that C>S-modified insulin is specifically recognized by CD4 + T cells in human T1D patients and NOD mice. In humans with established T1D, HLA-DQ8-restricted, C>S-specific CD4 + T cells exhibit an activated memory phenotype and lack regulatory signatures. In NOD mice, these neoepitope-specific T cells can orchestrate islet infiltration and promote diabetes progression. Collectively, these data advance a concept that microenvironment-driven and context-dependent post-translational modifications (PTMs) can generate neoantigens that contribute to organ-specific autoimmunity.
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Rashwan AM, Abumandour MMA, Kandyel R, Choudhary OP, Soliman RM, El Sharaby A, Nomir AG. Implications of endoplasmic reticulum stress and beta-cell loss in immunodeficient diabetic NRG-Akita mice for understanding monogenic diabetes. Int J Surg 2024; 110:6231-6242. [PMID: 38329104 PMCID: PMC11486971 DOI: 10.1097/js9.0000000000001148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 01/26/2024] [Indexed: 02/09/2024]
Abstract
BACKGROUND Immunodeficient mice models have become increasingly important as in vivo models engrafted with human cells or tissues for research. The NOD-Rag1 null Ins2 Akita Il2r null (NRG-Akita) mice is a model combined with immunodeficient NRG and monogenic diabetes Akita mice that develop spontaneous hyperglycemia with progressive loss of pancreatic insulin-producing beta-cells with age. This model is one of the monogenic diabetic models, which has been providing a powerful platform for transplantation experiments of stem cells-generated human β-cells. This research aimed to provide insights into the mechanisms underlying this monogenic diabetes, which remains incompletely understood. METHODS Histological and immunofluorescence analyses were conducted on endocrine pancreatic islets to compare NRG wild-type (Wt) controls with NRG-Akita mice. Our investigation focused on assessing the expression of endocrine hormones, transcription factors, proliferation, ER stress, and apoptosis. RESULTS Histological analyses on NRG-Akita mice revealed smaller islets at 6-weeks-old, due to fewer β-cells in the islets, compared to NRG-Wt controls, which further progressed with age. The proliferation rate decreased, and apoptosis was abundant in β-cells in NRG-Akita mice. Interestingly, our mechanistic analyses revealed that β-cells in NRG-Akita mice progressively accumulated the endoplasmic reticulum (ER) stresses, leading to a decreased expression of pivotal β-cell transcriptional factor PDX1. CONCLUSIONS Altogether, our mechanistic insight into β-cell loss in this model could shed light on essential links between ER stress, proliferation, and cell identity, which might open the door to new therapeutic strategies for various diseases since ER stress is one of the most common features not only in diabetes but also in other degenerative diseases.
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Affiliation(s)
- Ahmed M. Rashwan
- Department of Anatomy and Embryology
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, Japan
| | | | - Ramadan Kandyel
- Department of Zoology, Faculty of Science, Tanta University, Tanta, Egypt
- Department of Biology, Faculty of Arts and Sciences, Najran University, Najran, Saudi Arabia
| | - Om P. Choudhary
- Department of Veterinary Anatomy, College of Veterinary Science, Guru Angad Dev Veterinary and Animal Sciences University, Rampura Phul, Bathinda, Punjab, India
| | - Rofaida M. Soliman
- Department of Animal Medicine, Faculty of Veterinary Medicine, Damanhour University, Damanhour
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Kumar K, Chidambaram R, Parashar S, Ferro-Novick S. RTN3L and CALCOCO1 function in parallel to maintain proteostasis in the endoplasmic reticulum. Autophagy 2024; 20:2067-2075. [PMID: 38818751 PMCID: PMC11346533 DOI: 10.1080/15548627.2024.2353502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 04/22/2024] [Accepted: 05/06/2024] [Indexed: 06/01/2024] Open
Abstract
Reticulophagy is mediated by autophagy receptors that function in one of the two domains of the ER, tubules or flat sheets. Three different conserved mammalian receptors mediate autophagy in ER tubules: RTN3L, ATL3 and CALCOCO1. Previous studies have shown that RTN3L maintains proteostasis by targeting mutant aggregation-prone proteins for autophagy at distinct foci in ER tubules that we named ERPHS (ER-reticulophagy sites). The role for ATL3 and CALCOCO1 in proteostasis has not been addressed. Here we analyzed three different misfolded disease-causing RTN3L substrates and show that ATL3 and CALCOCO1 target the same cargoes for autophagy. Colocalization and knock down studies revealed that RTN3L and ATL3 are both required for the formation of RTN3L-containing ERPHS, while CALCOCO1 is not. We propose that RTN3L, ATL3 and CALCOCO1 work in parallel to maintain proteostasis within the ER network by targeting cargoes at different sites in the tubules.Abbreviation ATL3: atlastin GTPase 3; Baf: bafilomycin A1; CALCOCO1: calcium binding and coiled-coil domain 1; Epr1: ER-phagy receptor 1; ER: endoplasmic reticulum; ERAD: ER-associated protein degradation; ERPHS: ER-reticulophagy sites; LAMP1: lysosomal associated membrane protein 1; PGRMC1: progesterone receptor membrane component 1; POMC: proopiomelanocortin; Pro-AVP: pro-arginine vasopressin; RETREG1: reticulophagy regulator 1; reticulophagy: endoplasmic reticulum selective autophagy; RTN3L: reticulon 3 long isoform; VAPA: VAMP associated protein A.
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Affiliation(s)
- Kamal Kumar
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Ravi Chidambaram
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Smriti Parashar
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Susan Ferro-Novick
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
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Rohli KE, Stubbe NJ, Walker EM, Pearson GL, Soleimanpour SA, Stephens SB. A metabolic redox relay supports ER proinsulin export in pancreatic islet β cells. JCI Insight 2024; 9:e178725. [PMID: 38935435 PMCID: PMC11383593 DOI: 10.1172/jci.insight.178725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 06/18/2024] [Indexed: 06/29/2024] Open
Abstract
ER stress and proinsulin misfolding are heralded as contributing factors to β cell dysfunction in type 2 diabetes, yet how ER function becomes compromised is not well understood. Recent data identify altered ER redox homeostasis as a critical mechanism that contributes to insulin granule loss in diabetes. Hyperoxidation of the ER delays proinsulin export and limits the proinsulin supply available for insulin granule formation. In this report, we identified glucose metabolism as a critical determinant in the redox homeostasis of the ER. Using multiple β cell models, we showed that loss of mitochondrial function or inhibition of cellular metabolism elicited ER hyperoxidation and delayed ER proinsulin export. Our data further demonstrated that β cell ER redox homeostasis was supported by the metabolic supply of reductive redox donors. We showed that limiting NADPH and thioredoxin flux delayed ER proinsulin export, whereas thioredoxin-interacting protein suppression restored ER redox and proinsulin trafficking. Taken together, we propose that β cell ER redox homeostasis is buffered by cellular redox donor cycles, which are maintained through active glucose metabolism.
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Affiliation(s)
- Kristen E Rohli
- Fraternal Order of Eagles Diabetes Research Center
- Interdisciplinary Graduate Program in Genetics, and
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, USA
| | | | - Emily M Walker
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, and
| | - Gemma L Pearson
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, and
| | - Scott A Soleimanpour
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, and
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
- VA Ann Arbor Healthcare System, Ann Arbor, Michigan, USA
| | - Samuel B Stephens
- Fraternal Order of Eagles Diabetes Research Center
- Interdisciplinary Graduate Program in Genetics, and
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, USA
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9
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Dobson JR, Jacobson DA. Disrupted Endoplasmic Reticulum Ca 2+ Handling: A Harβinger of β-Cell Failure. BIOLOGY 2024; 13:379. [PMID: 38927260 PMCID: PMC11200644 DOI: 10.3390/biology13060379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/17/2024] [Accepted: 05/17/2024] [Indexed: 06/28/2024]
Abstract
The β-cell workload increases in the setting of insulin resistance and reduced β-cell mass, which occurs in type 2 and type 1 diabetes, respectively. The prolonged elevation of insulin production and secretion during the pathogenesis of diabetes results in β-cell ER stress. The depletion of β-cell Ca2+ER during ER stress activates the unfolded protein response, leading to β-cell dysfunction. Ca2+ER is involved in many pathways that are critical to β-cell function, such as protein processing, tuning organelle and cytosolic Ca2+ handling, and modulating lipid homeostasis. Mutations that promote β-cell ER stress and deplete Ca2+ER stores are associated with or cause diabetes (e.g., mutations in ryanodine receptors and insulin). Thus, improving β-cell Ca2+ER handling and reducing ER stress under diabetogenic conditions could preserve β-cell function and delay or prevent the onset of diabetes. This review focuses on how mechanisms that control β-cell Ca2+ER are perturbed during the pathogenesis of diabetes and contribute to β-cell failure.
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Affiliation(s)
| | - David A. Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA;
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Ojaghi M, Pamenter ME. Hypoxia impairs blood glucose homeostasis in naked mole-rat adult subordinates but not queens. J Exp Biol 2024; 227:jeb247537. [PMID: 38680085 PMCID: PMC11166464 DOI: 10.1242/jeb.247537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 04/12/2024] [Indexed: 05/01/2024]
Abstract
Naked mole-rats (NMRs) are among the most hypoxia-tolerant mammals and metabolize only carbohydrates in hypoxia. Glucose is the primary building block of dietary carbohydrates, but how blood glucose is regulated during hypoxia has not been explored in NMRs. We hypothesized that NMRs mobilize glucose stores to support anaerobic energy metabolism in hypoxia. To test this, we treated newborn, juvenile and adult (subordinate and queen) NMRs in normoxia (21% O2) or hypoxia (7, 5 or 3% O2), while measuring metabolic rate, body temperature and blood [glucose]. We also challenged animals with glucose, insulin or insulin-like growth factor-1 (IGF-1) injections and measured the rate of glucose clearance in normoxia and hypoxia. We found that: (1) blood [glucose] increases in moderate hypoxia in queens and pups, but only in severe hypoxia in adult subordinates and juveniles; (2) glucose tolerance is similar between developmental stages in normoxia, but glucose clearance times are 2- to 3-fold longer in juveniles and subordinates than in queens or pups in hypoxia; and (3) reoxygenation accelerates glucose clearance in hypoxic subordinate adults. Mechanistically, (4) insulin and IGF-1 reduce blood [glucose] in subordinates in both normoxia but only IGF-1 impacts blood [glucose] in hypoxic queens. Our results indicate that insulin signaling is impaired by hypoxia in NMRs, but that queens utilize IGF-1 to overcome this limitation and effectively regulate blood glucose in hypoxia. This suggests that sexual maturation impacts blood glucose handling in hypoxic NMR queens, which may allow queens to spend longer periods of time in hypoxic nest chambers.
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Affiliation(s)
- Mohammad Ojaghi
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 9A7
| | - Matthew E. Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 9A7
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada, K1H 8M5
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11
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Arunagiri A, Alam M, Haataja L, Draz H, Alasad B, Samy P, Sadique N, Tong Y, Cai Y, Shakeri H, Fantuzzi F, Ibrahim H, Jang I, Sidarala V, Soleimanpour SA, Satin LS, Otonkoski T, Cnop M, Itkin‐Ansari P, Kaufman RJ, Liu M, Arvan P. Proinsulin folding and trafficking defects trigger a common pathological disturbance of endoplasmic reticulum homeostasis. Protein Sci 2024; 33:e4949. [PMID: 38511500 PMCID: PMC10955614 DOI: 10.1002/pro.4949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/23/2024] [Accepted: 02/14/2024] [Indexed: 03/22/2024]
Abstract
Primary defects in folding of mutant proinsulin can cause dominant-negative proinsulin accumulation in the endoplasmic reticulum (ER), impaired anterograde proinsulin trafficking, perturbed ER homeostasis, diminished insulin production, and β-cell dysfunction. Conversely, if primary impairment of ER-to-Golgi trafficking (which also perturbs ER homeostasis) drives misfolding of nonmutant proinsulin-this might suggest bi-directional entry into a common pathological phenotype (proinsulin misfolding, perturbed ER homeostasis, and deficient ER export of proinsulin) that can culminate in diminished insulin storage and diabetes. Here, we've challenged β-cells with conditions that impair ER-to-Golgi trafficking, and devised an accurate means to assess the relative abundance of distinct folded/misfolded forms of proinsulin using a novel nonreducing SDS-PAGE/immunoblotting protocol. We confirm abundant proinsulin misfolding upon introduction of a diabetogenic INS mutation, or in the islets of db/db mice. Whereas blockade of proinsulin trafficking in Golgi/post-Golgi compartments results in intracellular accumulation of properly-folded proinsulin (bearing native disulfide bonds), impairment of ER-to-Golgi trafficking (regardless whether such impairment is achieved by genetic or pharmacologic means) results in decreased native proinsulin with more misfolded proinsulin. Remarkably, reversible ER-to-Golgi transport defects (such as treatment with brefeldin A or cellular energy depletion) upon reversal quickly restore the ER folding environment, resulting in the disappearance of pre-existing misfolded proinsulin while preserving proinsulin bearing native disulfide bonds. Thus, proper homeostatic balance of ER-to-Golgi trafficking is linked to a more favorable proinsulin folding (as well as trafficking) outcome.
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Affiliation(s)
- Anoop Arunagiri
- Division of Metabolism, Endocrinology & DiabetesUniversity of Michigan Medical CenterAnn ArborMichiganUSA
| | - Maroof Alam
- Division of Metabolism, Endocrinology & DiabetesUniversity of Michigan Medical CenterAnn ArborMichiganUSA
| | - Leena Haataja
- Division of Metabolism, Endocrinology & DiabetesUniversity of Michigan Medical CenterAnn ArborMichiganUSA
| | - Hassan Draz
- Division of Metabolism, Endocrinology & DiabetesUniversity of Michigan Medical CenterAnn ArborMichiganUSA
| | - Bashiyer Alasad
- Division of Metabolism, Endocrinology & DiabetesUniversity of Michigan Medical CenterAnn ArborMichiganUSA
| | - Praveen Samy
- Division of Metabolism, Endocrinology & DiabetesUniversity of Michigan Medical CenterAnn ArborMichiganUSA
| | - Nadeed Sadique
- Division of Metabolism, Endocrinology & DiabetesUniversity of Michigan Medical CenterAnn ArborMichiganUSA
| | - Yue Tong
- ULB Center for Diabetes Research, Medical Faculty; and Division of EndocrinologyErasmus Hospital, Universite Libre de BruxellesBrusselsBelgium
| | - Ying Cai
- ULB Center for Diabetes Research, Medical Faculty; and Division of EndocrinologyErasmus Hospital, Universite Libre de BruxellesBrusselsBelgium
| | - Hadis Shakeri
- ULB Center for Diabetes Research, Medical Faculty; and Division of EndocrinologyErasmus Hospital, Universite Libre de BruxellesBrusselsBelgium
| | - Federica Fantuzzi
- ULB Center for Diabetes Research, Medical Faculty; and Division of EndocrinologyErasmus Hospital, Universite Libre de BruxellesBrusselsBelgium
| | - Hazem Ibrahim
- Stem Cells and Metabolism Research Program, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Insook Jang
- Degenerative Diseases ProgramCenter for Genetic Disorders and Aging Research, Sanford Burnham Prebys Medical Discovery InstituteLa JollaCaliforniaUSA
| | - Vaibhav Sidarala
- Division of Metabolism, Endocrinology & DiabetesUniversity of Michigan Medical CenterAnn ArborMichiganUSA
| | - Scott A. Soleimanpour
- Division of Metabolism, Endocrinology & DiabetesUniversity of Michigan Medical CenterAnn ArborMichiganUSA
| | - Leslie S. Satin
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMichiganUSA
| | - Timo Otonkoski
- Stem Cells and Metabolism Research Program, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Miriam Cnop
- ULB Center for Diabetes Research, Medical Faculty; and Division of EndocrinologyErasmus Hospital, Universite Libre de BruxellesBrusselsBelgium
| | - Pamela Itkin‐Ansari
- Development, Aging and Regeneration ProgramCenter for Genetic Disorders and Aging Research, Sanford Burnham Prebys Medical Discovery InstituteLa JollaCaliforniaUSA
| | - Randal J. Kaufman
- Degenerative Diseases ProgramCenter for Genetic Disorders and Aging Research, Sanford Burnham Prebys Medical Discovery InstituteLa JollaCaliforniaUSA
| | - Ming Liu
- Department of Endocrinology and MetabolismTianjin Medical University General HospitalTianjinChina
| | - Peter Arvan
- Division of Metabolism, Endocrinology & DiabetesUniversity of Michigan Medical CenterAnn ArborMichiganUSA
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Bhavsar D, Kutre S, Shikhare P, Kumar S, Behera SK, Chauthe SK. Pharmacoinformatics approach for type 2 diabetes mellitus therapeutics using phytocompounds from Costus genus: an in-silico investigation. J Biomol Struct Dyn 2024:1-17. [PMID: 38511497 DOI: 10.1080/07391102.2024.2330712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 03/08/2024] [Indexed: 03/22/2024]
Abstract
Type 2 Diabetes Mellitus (T2DM), as a significant health concern globally, particularly in India, underscoring the vital need for effective therapeutics. Current drug therapies for T2DM may have limitations, leading researchers to explore natural products as alternatives. In this study. We have investigated the anti-diabetic compounds from the Costus genus, known as the insulin plant, which is abundant in southern India. The bioinformatics tools and software used for in-silico analysis to identify potential therapeutic compounds and hub genes associated with T2DM in the Indian population that could cut short the in-vitro and in-vivo experimental approaches in near future. The systematic review and combinatorial in-silico analysis revealed IGF2BP2, INS and TCF as the key targets that are associated with T2DM. The compounds stigmasterol, cycloartenol, and diosgenone were explored to be potent among all the 38 phytocompounds from genus Costus with binding energies -8.48, -10.07, and -10.31 kcal/mol against IGF2BP2, INS and TCF. The molecular dynamics (MD) simulation studies of these complexes demonstrated stable and consistent dynamic behavior, particularly in the INS-cycloartenol, IGF2BP2-stigmasterol and TCF7L2-diosgenone complexes. The identified compounds and associated targets represent potential candidates for T2DM therapeutics in the Indian population. The pharmacoinformatics approach presented in the study could streamline the drug discovery process by prioritizing compounds for further experimental validation.
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Affiliation(s)
- Drashti Bhavsar
- Department of Natural Products, National Institute of Pharmaceutical Education and Research, Ahmedabad, Gujarat, India
| | - Suraj Kutre
- Department of Natural Products, National Institute of Pharmaceutical Education and Research, Ahmedabad, Gujarat, India
| | - Priti Shikhare
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Ahmedabad, Gujarat, India
| | - Sunil Kumar
- Division of Agricultural Bioinformatics, ICAR-Indian Agricultural Statistics Research Institute (IASRI), New Delhi, India
| | - Santosh Kumar Behera
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Ahmedabad, Gujarat, India
| | - Siddheshwar Kisan Chauthe
- Department of Natural Products, National Institute of Pharmaceutical Education and Research, Ahmedabad, Gujarat, India
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13
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Yilmaz E. Endoplasmic Reticulum Stress and Obesity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1460:373-390. [PMID: 39287859 DOI: 10.1007/978-3-031-63657-8_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2024]
Abstract
In recent years, the world has seen an alarming increase in obesity and is closely associated with insulin resistance, which is a state of low-grade inflammation, the latter characterized by elevated levels of proinflammatory cytokines in blood and tissues. A shift in energy balance alters systemic metabolic regulation and the important role that chronic inflammation, endoplasmic reticulum (ER) dysfunction, and activation of the unfolded protein response (UPR) plays in this process.Why obesity is so closely associated with insulin resistance and inflammation is not understood well. This suggests that there are probably many causes for obesity-related insulin resistance and inflammation. One of the faulty mechanisms is protein homeostasis, protein quality control system included protein folding, chaperone activity, and ER-associated degradation leading to endoplasmic reticulum (ER) stress.The ER is a vast membranous network responsible for the trafficking of a wide range of proteins and plays a central role in integrating multiple metabolic signals critical in cellular homeostasis. Conditions that may trigger unfolded protein response activation include increased protein synthesis, the presence of mutant or misfolded proteins, inhibition of protein glycosylation, imbalance of ER calcium levels, glucose and energy deprivation, hypoxia, pathogens, or pathogen-associated components and toxins. Thus, characterizing the mechanisms contributing to obesity and identifying potential targets for its prevention and treatment will have a great impact on the control of associated conditions, particularly T2D.
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Affiliation(s)
- Erkan Yilmaz
- Biotechnology Institute, Ankara University, Kecioren, Ankara, Turkey.
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14
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Cota P, Caliskan ÖS, Bastidas-Ponce A, Jing C, Jaki J, Saber L, Czarnecki O, Taskin D, Blöchinger AK, Kurth T, Sterr M, Burtscher I, Krahmer N, Lickert H, Bakhti M. Insulin regulates human pancreatic endocrine cell differentiation in vitro. Mol Metab 2024; 79:101853. [PMID: 38103636 PMCID: PMC10765254 DOI: 10.1016/j.molmet.2023.101853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/21/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023] Open
Abstract
OBJECTIVE The consequences of mutations in genes associated with monogenic forms of diabetes on human pancreas development cannot be studied in a time-resolved fashion in vivo. More specifically, if recessive mutations in the insulin gene influence human pancreatic endocrine lineage formation is still an unresolved question. METHODS To model the extremely reduced insulin levels in patients with recessive insulin gene mutations, we generated a novel knock-in H2B-Cherry reporter human induced pluripotent stem cell (iPSC) line expressing no insulin upon differentiation to stem cell-derived (SC-) β cells in vitro. Differentiation of iPSCs into the pancreatic and endocrine lineage, combined with immunostaining, Western blotting and proteomics analysis phenotypically characterized the insulin gene deficiency in SC-islets. Furthermore, we leveraged FACS analysis and confocal microscopy to explore the impact of insulin shortage on human endocrine cell induction, composition, differentiation and proliferation. RESULTS Interestingly, insulin-deficient SC-islets exhibited low insulin receptor (IR) signaling when stimulated with glucose but displayed increased IR sensitivity upon treatment with exogenous insulin. Furthermore, insulin shortage did not alter neurogenin-3 (NGN3)-mediated endocrine lineage induction. Nevertheless, lack of insulin skewed the SC-islet cell composition with an increased number in SC-β cell formation at the expense of SC-α cells. Finally, insulin deficiency reduced the rate of SC-β cell proliferation but had no impact on the expansion of SC-α cells. CONCLUSIONS Using iPSC disease modelling, we provide first evidence of insulin function in human pancreatic endocrine lineage formation. These findings help to better understand the phenotypic impact of recessive insulin gene mutations during pancreas development and shed light on insulin gene function beside its physiological role in blood glucose regulation.
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Affiliation(s)
- Perla Cota
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany
| | - Özüm Sehnaz Caliskan
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Institute of Diabetes and Obesity, Helmholtz Munich, Neuherberg, Germany
| | - Aimée Bastidas-Ponce
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Changying Jing
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; Munich medical research school (MMRS), Ludwig Maximilian University (LMU), Munich, Germany
| | - Jessica Jaki
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Lama Saber
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany
| | - Oliver Czarnecki
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany
| | - Damla Taskin
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany
| | - Anna Karolina Blöchinger
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Thomas Kurth
- Center for Molecular and Cellular Bioengineering (CMCB), Technology Platform Core Facility Electron Microscopy and Histology, Technische Universität Dresden, Dresden, Germany
| | - Michael Sterr
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Ingo Burtscher
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Natalie Krahmer
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Institute of Diabetes and Obesity, Helmholtz Munich, Neuherberg, Germany
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany.
| | - Mostafa Bakhti
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany.
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15
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Vaňková M, Vejražková D, Lukášová P, Včelák J, Chocholová D, Bendlová B. Age-Related Changes in Proinsulin Processing in Normoglycemic Individuals. Physiol Res 2023; 72:S389-S397. [PMID: 38116775 DOI: 10.33549/physiolres.935181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024] Open
Abstract
In order to understand the pathological changes associated with glucose homeostasis in old age, it is necessary to know the natural changes in the processing of proinsulin to mature insulin. While there is abundant information about insulin production and function in diabetics, the situation in healthy adults and the elderly has surprisingly rarely been investigated. The aim of the study was to determine how proinsulin secretion changes in individuals with normal glucose tolerance during the process of natural aging. A total of 761 individuals (539 women, 222 men) aged 18-90 years with normal fasting glycemia (less than 5.6 mmol/l) were divided into five groups according to age. Body composition and levels of fasting blood glucose, proinsulin, insulin, and C-peptide were determined, and the ratios of proinsulin to both insulin and C-peptide were calculated. The homeostasis model of ?-cell function (HOMA F) and peripheral insulin resistance (HOMA R) were calculated. The effect of age was assessed using an ANOVA model consisting of the factors sex, age, and sex × age interaction. Statgraphics Centurion v. XVIII statistical software was used. Glycemia, insulin, C-peptide and HOMA R increased in both sexes up to 75 years. On the contrary, proinsulin levels as well as proinsulin/insulin and proinsulin/C-peptide ratios decreased with age up to 75 years. In normoglycemic and normotolerant people, both women and men, the aging process is associated with decreased insulin sensitivity compensated by potentiation of insulin production. In older age, there is also a gradual decrease in circulating proinsulin, which can be explained by its more efficient processing into active insulin by matured healthy beta cells.
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Affiliation(s)
- M Vaňková
- Institute of Endocrinology, Prague, Czech Republic, Faculty of Science, Charles University, Prague, Czech Republic
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16
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Knupp J, Pletan ML, Arvan P, Tsai B. Autophagy of the ER: the secretome finds the lysosome. FEBS J 2023; 290:5656-5673. [PMID: 37920925 PMCID: PMC11044768 DOI: 10.1111/febs.16986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 09/20/2023] [Accepted: 10/23/2023] [Indexed: 11/04/2023]
Abstract
Lysosomal degradation of the endoplasmic reticulum (ER) and its components through the autophagy pathway has emerged as a major regulator of ER proteostasis. Commonly referred to as ER-phagy and ER-to-lysosome-associated degradation (ERLAD), how the ER is targeted to the lysosome has been recently clarified by a growing number of studies. Here, we summarize the discoveries of the molecular components required for lysosomal degradation of the ER and their proposed mechanisms of action. Additionally, we discuss how cells employ these machineries to create the different routes of ER-lysosome-associated degradation. Further, we review the role of ER-phagy in viral infection pathways, as well as the implication of ER-phagy in human disease. In sum, we provide a comprehensive overview of the current field of ER-phagy.
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Affiliation(s)
- Jeffrey Knupp
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Madison L Pletan
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, USA
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17
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Tang Q, Shi W, Liu M, Tang L, Ren W, Shi S. Mitochondrial protein MPV17 promotes β-cell apoptosis in diabetogenesis. Clin Sci (Lond) 2023; 137:1195-1208. [PMID: 37522959 PMCID: PMC10415165 DOI: 10.1042/cs20230164] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 07/25/2023] [Accepted: 07/31/2023] [Indexed: 08/01/2023]
Abstract
MPV17 is a mitochondrial inner membrane protein, and its deficiency can cause mitochondrial DNA (mtDNA) depletion, increase reactive oxygen species (ROS), and promote apoptosis in several cell types, suggesting that MPV17 plays a protective role in cells although the underlying mechanism remains unknown. To test whether MPV17 is also protective in diabetic kidney disease, we treated Mpv17-deficient mice with streptozotocin (STZ) and surprisingly found that they were resistant to diabetes. Mpv17 deficiency was also found to confer resistance to the diabetes induced by an insulin mutation (Ins2Akita), which represents a mouse model of monogenic diabetes characterized by proinsulin misfolding and β-cell failure. In both STZ and Ins2Akita models, Mpv17 mutants had significantly less severe β-cell loss and apoptosis compared with the wild-type mice. We next showed that MPV17 is expressed in β-cells of mice normally, suggesting that MPV17 acts β-cells autonomously to facilitate apoptosis. Consistently, Mpv17 knockdown improved the viability and ameliorated the apoptosis of cultured MIN6 cells treated with STZ and palmitic acid (PA), respectively, accompanied by prevention of caspase 3 activation. The proapoptotic effect of MPV17 in β-cells is in contrast with its known anti-apoptotic effect in other cell types. Thus, we have identified a novel regulator of β-cell death in diabetes development.
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Affiliation(s)
- Qiaoli Tang
- Department of Nephrology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medcine, University of Science and Technology of China, Hefei, China
- National Clinical Research Center for Kidney Diseases, Nanjing University School of Medicine, Nanjing, China
| | - Wanting Shi
- National Clinical Research Center for Kidney Diseases, Nanjing University School of Medicine, Nanjing, China
| | - Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Liqin Tang
- Department of Nephrology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medcine, University of Science and Technology of China, Hefei, China
| | - Wei Ren
- Department of Nephrology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medcine, University of Science and Technology of China, Hefei, China
| | - Shaolin Shi
- National Clinical Research Center for Kidney Diseases, Nanjing University School of Medicine, Nanjing, China
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, U.S.A
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18
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Rudinskiy M, Molinari M. ER-to-lysosome-associated degradation in a nutshell: mammalian, yeast, and plant ER-phagy as induced by misfolded proteins. FEBS Lett 2023; 597:1928-1945. [PMID: 37259628 DOI: 10.1002/1873-3468.14674] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 05/10/2023] [Accepted: 05/22/2023] [Indexed: 06/02/2023]
Abstract
Conserved catabolic pathways operate to remove aberrant polypeptides from the endoplasmic reticulum (ER), the major biosynthetic organelle of eukaryotic cells. The best known are the ER-associated degradation (ERAD) pathways that control the retrotranslocation of terminally misfolded proteins across the ER membrane for clearance by the cytoplasmic ubiquitin/proteasome system. In this review, we catalog folding-defective mammalian, yeast, and plant proteins that fail to engage ERAD machineries. We describe that they rather segregate in ER subdomains that eventually vesiculate. These ER-derived vesicles are captured by double membrane autophagosomes, engulfed by endolysosomes/vacuoles, or fused with degradative organelles to clear cells from their toxic cargo. These client-specific, mechanistically diverse ER-phagy pathways are grouped under the umbrella term of ER-to-lysosome-associated degradation for description in this essay.
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Affiliation(s)
- Mikhail Rudinskiy
- Università della Svizzera italiana, Lugano, Switzerland
- Institute for Research in Biomedicine, Bellinzona, Switzerland
- Department of Biology, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Maurizio Molinari
- Università della Svizzera italiana, Lugano, Switzerland
- Institute for Research in Biomedicine, Bellinzona, Switzerland
- School of Life Sciences, École Polytechnique Fédérale de Lausanne, Switzerland
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19
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Zhu S, Li Y, Zhang F, Xiong C, Gao H, Yao Y, Qian W, Ding C, Chen S. Raman spectromics method for fast and label-free genotype screening. BIOMEDICAL OPTICS EXPRESS 2023; 14:3072-3085. [PMID: 37342689 PMCID: PMC10278603 DOI: 10.1364/boe.493524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/22/2023] [Accepted: 05/22/2023] [Indexed: 06/23/2023]
Abstract
It is now understood that genes and their various mutations are associated with the onset and progression of diseases. However, routine genetic testing techniques are limited by their high cost, time consumption, susceptibility to contamination, complex operation, and data analysis difficulties, rendering them unsuitable for genotype screening in many cases. Therefore, there is an urgent need to develop a rapid, sensitive, user-friendly, and cost-effective method for genotype screening and analysis. In this study, we propose and investigate a Raman spectroscopic method for achieving fast and label-free genotype screening. The method was validated using spontaneous Raman measurements of wild-type Cryptococcus neoformans and its six mutants. An accurate identification of different genotypes was achieved by employing a one-dimensional convolutional neural network (1D-CNN), and significant correlations between metabolic changes and genotypic variations were revealed. Genotype-specific regions of interest were also localized and visualized using a gradient-weighted class activation mapping (Grad-CAM)-based spectral interpretable analysis method. Furthermore, the contribution of each metabolite to the final genotypic decision-making was quantified. The proposed Raman spectroscopic method demonstrated huge potential for fast and label-free genotype screening and analysis of conditioned pathogens.
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Affiliation(s)
- Shanshan Zhu
- Research Institute of Medical and Biological Engineering, Ningbo University, Ningbo 315211, China
- College of Medicine and Biological Information Engineering, Northeastern University, Shenyang 110169, China
- Health Science Center, Ningbo University, Ningbo 315211, China
- Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Provincial Key Laboratory of Photonics Technology, Fujian Normal University, Fuzhou 350117, China
| | - Yanjian Li
- College of Life and Health Sciences, Northeastern University, Shenyang 110169, China
| | - Fengdi Zhang
- College of Medicine and Biological Information Engineering, Northeastern University, Shenyang 110169, China
| | - Changchun Xiong
- College of Electrical Engineering and Computer Science, Ningbo University, Ningbo 315211, China
| | - Han Gao
- College of Medicine and Biological Information Engineering, Northeastern University, Shenyang 110169, China
| | - Yudong Yao
- Research Institute of Medical and Biological Engineering, Ningbo University, Ningbo 315211, China
| | - Wei Qian
- Research Institute of Medical and Biological Engineering, Ningbo University, Ningbo 315211, China
| | - Chen Ding
- College of Life and Health Sciences, Northeastern University, Shenyang 110169, China
| | - Shuo Chen
- College of Medicine and Biological Information Engineering, Northeastern University, Shenyang 110169, China
- Key Laboratory of Intelligent Computing in Medical Image, Ministry of Education, Shenyang 110169, China
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20
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Ataie-Ashtiani S, Forbes B. A Review of the Biosynthesis and Structural Implications of Insulin Gene Mutations Linked to Human Disease. Cells 2023; 12:cells12071008. [PMID: 37048081 PMCID: PMC10093311 DOI: 10.3390/cells12071008] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/13/2023] [Accepted: 03/15/2023] [Indexed: 03/29/2023] Open
Abstract
The discovery of the insulin hormone over 100 years ago, and its subsequent therapeutic application, marked a key landmark in the history of medicine and medical research. The many roles insulin plays in cell metabolism and growth have been revealed by extensive investigations into the structure and function of insulin, the insulin tyrosine kinase receptor (IR), as well as the signalling cascades, which occur upon insulin binding to the IR. In this review, the insulin gene mutations identified as causing disease and the structural implications of these mutations will be discussed. Over 100 studies were evaluated by one reviewing author, and over 70 insulin gene mutations were identified. Mutations may impair insulin gene transcription and translation, preproinsulin trafficking and proinsulin sorting, or insulin-IR interactions. A better understanding of insulin gene mutations and the resultant pathophysiology can give essential insight into the molecular mechanisms underlying impaired insulin biosynthesis and insulin-IR interaction.
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21
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Yang J, Zhen J, Feng W, Fan Z, Ding L, Yang X, Huang Y, Shu H, Xie J, Li X, Qiao J, Fan Y, Sun J, Li N, Liu T, Wang S, Zhang X, Arvan P, Liu M. IER3IP1 is critical for maintaining glucose homeostasis through regulating the endoplasmic reticulum function and survival of β cells. Proc Natl Acad Sci U S A 2022; 119:e2204443119. [PMID: 36322741 PMCID: PMC9659391 DOI: 10.1073/pnas.2204443119] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 10/06/2022] [Indexed: 05/04/2023] Open
Abstract
Recessive mutations in IER3IP1 (immediate early response 3 interacting protein 1) cause a syndrome of microcephaly, epilepsy, and permanent neonatal diabetes (MEDS). IER3IP1 encodes an endoplasmic reticulum (ER) membrane protein, which is crucial for brain development; however, the role of IER3IP1 in β cells remains unknown. We have generated two mouse models with either constitutive or inducible IER3IP1 deletion in β cells, named IER3IP1-βKO and IER3IP1-iβKO, respectively. We found that IER3IP1-βKO causes severe early-onset, insulin-deficient diabetes. Functional studies revealed a markedly dilated β-cell ER along with increased proinsulin misfolding and elevated expression of the ER chaperones, including PDI, ERO1, BiP, and P58IPK. Islet transcriptome analysis confirmed by qRT-PCR revealed decreased expression of genes associated with β-cell maturation, cell cycle, and antiapoptotic genes, accompanied by increased expression of antiproliferation genes. Indeed, multiple independent approaches further demonstrated that IER3IP1-βKO impaired β-cell maturation and proliferation, along with increased condensation of β-cell nuclear chromatin. Inducible β-cell IER3IP1 deletion in adult (8-wk-old) mice induced a similar diabetic phenotype, suggesting that IER3IP1 is also critical for function and survival even after β-cell early development. Importantly, IER3IP1 was decreased in β cells of patients with type 2 diabetes (T2D), suggesting an association of IER3IP1 deficiency with β-cell dysfunction in the more-common form of diabetes. These data not only uncover a critical role of IER3IP1 in β cells but also provide insight into molecular basis of diabetes caused by IER3IP1 mutations.
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Affiliation(s)
- Jing Yang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Jinyang Zhen
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Wenli Feng
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Zhenqian Fan
- Department of Endocrinology, The Second Hospital of Tianjin Medical University, Tianjin 300211, China
| | - Li Ding
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Xiaoyun Yang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Yumeng Huang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Hua Shu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Jing Xie
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Xin Li
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Jingting Qiao
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Yuxin Fan
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Jinhong Sun
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Na Li
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Tengli Liu
- Organ Transplant Center, Tianjin First Central Hospital, Nankai University, Tianjin 300192, China
- NHC Key Laboratory for Critical Care Medicine, Tianjin First Central Hospital, Tianjin 300384, China
| | - Shusen Wang
- Organ Transplant Center, Tianjin First Central Hospital, Nankai University, Tianjin 300192, China
- NHC Key Laboratory for Critical Care Medicine, Tianjin First Central Hospital, Tianjin 300384, China
- Human Islet Resource Center, Tianjin First Central Hospital, Tianjin 300384, China
| | - Xiaona Zhang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI 48105
| | - Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
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22
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Wong HS, Freeman DA, Zhang Y. Not just a cousin of the naked mole-rat: Damaraland mole-rats offer unique insights into biomedicine. Comp Biochem Physiol B Biochem Mol Biol 2022; 262:110772. [PMID: 35710053 PMCID: PMC10155858 DOI: 10.1016/j.cbpb.2022.110772] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/07/2022] [Accepted: 06/09/2022] [Indexed: 11/26/2022]
Abstract
Evolutionary medicine has been a fast-growing field of biological research in the past decade. One of the strengths of evolutionary medicine is to use non-traditional model organisms which often exhibit unusual characteristics shaped by natural selection. Studying these unusual traits could provide valuable insight to understand biomedical questions, since natural selection likely discovers solutions to those complex biological problems. Because of many unusual traits, the naked mole-rat (NMR) has attracted attention from different research areas such as aging, cancer, and hypoxia- and hypercapnia-related disorders. However, such uniqueness of NMR physiology may sometimes make the translational study to human research difficult. Damaraland mole-rat (DMR) shares multiple characteristics in common with NMR, but shows higher degree of similarity with human in some aspects of their physiology. Research on DMR could therefore offer alternative insights and might bridge the gap between experimental findings from NMR to human biomedical research. In this review, we discuss studies of DMR as an extension of the current set of model organisms to help better understand different aspects of human biology and disease. We hope to encourage researchers to consider studying DMR together with NMR. By studying these two similar but evolutionarily distinct species, we can harvest the power of convergent evolution and avoid the potential biased conclusions based on life-history of a single species.
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Affiliation(s)
- Hoi-Shan Wong
- Nine Square Therapeutics, South San Francisco, CA 94080, United States of America.
| | - David A Freeman
- Department of Biological Sciences, The University of Memphis, Memphis, TN 38152, United States of America
| | - Yufeng Zhang
- College of Health Sciences, The University of Memphis, Memphis, TN 38152, United States of America.
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Xu X, Arunagiri A, Haataja L, Alam M, Ji S, Qi L, Tsai B, Liu M, Arvan P. Proteasomal degradation of wild-type proinsulin in pancreatic beta cells. J Biol Chem 2022; 298:102406. [PMID: 35988641 PMCID: PMC9486123 DOI: 10.1016/j.jbc.2022.102406] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 11/22/2022] Open
Abstract
Preproinsulin entry into the endoplasmic reticulum yields proinsulin, and its subsequent delivery to the distal secretory pathway leads to processing, storage, and secretion of mature insulin. Multiple groups have reported that treatment of pancreatic beta cell lines, rodent pancreatic islets, or human islets with proteasome inhibitors leads to diminished proinsulin and insulin protein levels, diminished glucose-stimulated insulin secretion, and changes in beta-cell gene expression that ultimately lead to beta-cell death. However, these studies have mostly examined treatment times far beyond that needed to achieve acute proteasomal inhibition. Here, we report that although proteasomal inhibition immediately downregulates new proinsulin biosynthesis, it nevertheless acutely increases beta-cell proinsulin levels in pancreatic beta cell lines, rodent pancreatic islets, and human islets, indicating rescue of a pool of recently synthesized WT INS gene product that would otherwise be routed to proteasomal disposal. Our pharmacological evidence suggests that this disposal most likely reflects ongoing endoplasmic reticulum–associated protein degradation. However, we found that within 60 min after proteasomal inhibition, intracellular proinsulin levels begin to fall in conjunction with increased phosphorylation of eukaryotic initiation factor 2 alpha, which can be inhibited by blocking the general control nonderepressible 2 kinase. Together, these data demonstrate that a meaningful subfraction of newly synthesized INS gene product undergoes rapid proteasomal disposal. We propose that free amino acids derived from proteasomal proteolysis may potentially participate in suppressing general control nonderepressible 2 kinase activity to maintain ongoing proinsulin biosynthesis.
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Affiliation(s)
- Xiaoxi Xu
- The Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI 48105; Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China 300052
| | - Anoop Arunagiri
- The Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI 48105
| | - Leena Haataja
- The Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI 48105
| | - Maroof Alam
- The Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI 48105
| | - Shuhui Ji
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China 300052
| | - Ling Qi
- Departments of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Billy Tsai
- Departments of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China 300052.
| | - Peter Arvan
- The Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI 48105.
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Svikle Z, Peterfelde B, Sjakste N, Baumane K, Verkauskiene R, Jeng CJ, Sokolovska J. Ubiquitin-proteasome system in diabetic retinopathy. PeerJ 2022; 10:e13715. [PMID: 35873915 PMCID: PMC9306563 DOI: 10.7717/peerj.13715] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 06/21/2022] [Indexed: 01/22/2023] Open
Abstract
Diabetic retinopathy (DR) is the most common complication of diabetes, being the most prevalent reason for blindness among the working-age population in the developed world. Despite constant improvement of understanding of the pathogenesis of DR, identification of novel biomarkers of DR is needed for improvement of patient risk stratification and development of novel prevention and therapeutic approaches. The ubiquitin-proteasome system (UPS) is the primary protein quality control system responsible for recognizing and degrading of damaged proteins. This review aims to summarize literature data on modifications of UPS in diabetes and DR. First, we briefly review the structure and functions of UPS in physiological conditions. We then describe how UPS is involved in the development and progression of diabetes and touch upon the association of UPS genetic factors with diabetes and its complications. Further, we focused on the effect of diabetes-induced hyperglycemia, oxidative stress and hypoxia on UPS functioning, with examples of studies on DR. In other sections, we discussed the association of several other mechanisms of DR (endoplasmic reticulum stress, neurodegeneration etc) with UPS modifications. Finally, UPS-affecting drugs and remedies are reviewed. This review highlights UPS as a promising target for the development of therapies for DR prevention and treatment and identifies gaps in existing knowledge and possible future study directions.
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Affiliation(s)
- Zane Svikle
- Faculty of Medicine, University of Latvia, Riga, Latvia
| | - Beate Peterfelde
- Faculty of Medicine, University of Latvia, Riga, Latvia,Ophthalmology Department, Riga East University Hospital, Riga, Latvia
| | | | - Kristine Baumane
- Faculty of Medicine, University of Latvia, Riga, Latvia,Ophthalmology Department, Riga East University Hospital, Riga, Latvia
| | - Rasa Verkauskiene
- Institute of Endocrinology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Chi-Juei Jeng
- Ophthalmology Department, Taipei Medical University Shuang Ho Hospital, Ministry of Health and Welfare, Taipei, The Republic of China (Taiwan),College of Medicine, Graduate Institute of Clinical Medicine, National Taiwan University, Taipei, Taiwan
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25
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Moon S, Jung HS. Endoplasmic Reticulum Stress and Dysregulated Autophagy in Human Pancreatic Beta Cells. Diabetes Metab J 2022; 46:533-542. [PMID: 35929171 PMCID: PMC9353561 DOI: 10.4093/dmj.2022.0070] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 05/28/2022] [Indexed: 11/08/2022] Open
Abstract
Pancreatic beta cell homeostasis is crucial for the synthesis and secretion of insulin; disruption of homeostasis causes diabetes, and is a treatment target. Adaptation to endoplasmic reticulum (ER) stress through the unfolded protein response (UPR) and adequate regulation of autophagy, which are closely linked, play essential roles in this homeostasis. In diabetes, the UPR and autophagy are dysregulated, which leads to beta cell failure and death. Various studies have explored methods to preserve pancreatic beta cell function and mass by relieving ER stress and regulating autophagic activity. To promote clinical translation of these research results to potential therapeutics for diabetes, we summarize the current knowledge on ER stress and autophagy in human insulin-secreting cells.
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Affiliation(s)
- Seoil Moon
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - Hye Seung Jung
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
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26
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Ramzy A, Edeer N, Baker RK, O’Dwyer S, Mojibian M, Verchere CB, Kieffer TJ. Insulin Null β-cells Have a Prohormone Processing Defect That Is Not Reversed by AAV Rescue of Proinsulin Expression. Endocrinology 2022; 163:6569864. [PMID: 35435956 PMCID: PMC9119694 DOI: 10.1210/endocr/bqac051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Indexed: 11/19/2022]
Abstract
Up to 6% of diabetes has a monogenic cause including mutations in the insulin gene, and patients are candidates for a gene therapy. Using a mouse model of permanent neonatal diabetes, we assessed the efficacy of an adeno-associated virus (AAV)-mediated gene therapy. We used AAVs with a rat insulin 1 promoter (Ins1) regulating a human insulin gene (INS; AAV Ins1-INS) or native mouse insulin 1 (Ins1; AAV Ins-Ins1) to deliver an insulin gene to β-cells of constitutive insulin null mice (Ins1-/-Ins2-/-) and adult inducible insulin-deficient mice [Ins1-/-Ins2f/f PdxCreER and Ins1-/-Ins2f/f mice administered AAV Ins1-Cre)]. Although AAV Ins1-INS could successfully infect and confer insulin expression to β-cells, insulin null β-cells had a prohormone processing defect. Secretion of abundant proinsulin transiently reversed diabetes. We reattempted therapy with AAV Ins1-Ins1, but Ins1-/-Ins2-/- β-cells still had a processing defect of both replaced Ins1 and pro-islet amyloid polypeptide (proIAPP). In adult inducible models, β-cells that lost insulin expression developed a processing defect that resulted in impaired proIAPP processing and elevated circulating proIAPP, and cells infected with AAV Ins1-Ins1 to rescue insulin expression secreted proinsulin. We assessed the subcellular localization of prohormone convertase 1/3 (PC1/3) and detected defective sorting of PC1/3 to glycogen-containing vacuoles and retention in the endoplasmic reticulum as a potential mechanism underlying defective processing. We provide evidence that persistent production of endogenous proinsulin within β-cells is necessary for β-cells to be able to properly store and process proinsulin.
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Affiliation(s)
- Adam Ramzy
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Nazde Edeer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Robert K Baker
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Shannon O’Dwyer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Majid Mojibian
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - C Bruce Verchere
- Department of Pathology and Laboratory Medicine, BC Children’s Hospital Research Institute, Vancouver, BC, Canada
- Department of Surgery, University of British Columbia, Vancouver, BC, Canada
| | - Timothy J Kieffer
- Correspondence: Timothy J. Kieffer, PhD, Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada.
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27
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Fuselier T, Mota de Sa P, Qadir MMF, Xu B, Allard C, Meyers MM, Tiano JP, Yang BS, Gelfanov V, Lindsey SH, Dimarchi RD, Mauvais-Jarvis F. Efficacy of glucagon-like peptide-1 and estrogen dual agonist in pancreatic islets protection and pre-clinical models of insulin-deficient diabetes. Cell Rep Med 2022; 3:100598. [PMID: 35492248 PMCID: PMC9043999 DOI: 10.1016/j.xcrm.2022.100598] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/18/2022] [Accepted: 03/15/2022] [Indexed: 02/06/2023]
Abstract
We study the efficacy of a glucagon-like peptide-1 (GLP-1) and estrogen dual agonist (GLP1-E2) in pancreatic islet protection. GLP1-E2 provides superior protection from insulin-deficient diabetes induced by multiple low-dose streptozotocin (MLD-STZ-diabetes) and by the Akita mutation in mice than a GLP-1 monoagonist. GLP1-E2 does not protect from MLD-STZ-diabetes in estrogen receptor-α (ERα)-deficient mice and fails to prevent diabetes in Akita mice following GLP-1 receptor (GLP-1R) antagonism, demonstrating the requirement of GLP-1R and ERα for GLP1-E2 antidiabetic actions. In the MIN6 β cell model, GLP1-E2 activates estrogen action following clathrin-dependent, GLP-1R-mediated internalization and lysosomal acidification. In cultured human islet, proteomic bioinformatic analysis reveals that GLP1-E2 amplifies the antiapoptotic pathways activated by monoagonists. However, in cultured mouse islets, GLP1-E2 provides antiapoptotic protection similar to monoagonists. Thus, GLP1-E2 promotes GLP-1 and E2 antiapoptotic signals in cultured islets, but in vivo, additional GLP1-E2 actions in non-islet cells expressing GLP-1R are instrumental to prevent diabetes.
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Affiliation(s)
- Taylor Fuselier
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA
| | - Paula Mota de Sa
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Healthcare System Medical Center, New Orleans, LA 70119, USA
| | - M M Fahd Qadir
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Healthcare System Medical Center, New Orleans, LA 70119, USA
| | - Beibei Xu
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA
| | - Camille Allard
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA
| | - Mathew M Meyers
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Joseph P Tiano
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Bin S Yang
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN 46241, USA
| | - Vasily Gelfanov
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN 46241, USA
| | - Sarah H Lindsey
- Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA; Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | | | - Franck Mauvais-Jarvis
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Healthcare System Medical Center, New Orleans, LA 70119, USA.
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28
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Dhayalan B, Glidden MD, Zaykov AN, Chen YS, Yang Y, Phillips NB, Ismail-Beigi F, Jarosinski MA, DiMarchi RD, Weiss MA. Peptide Model of the Mutant Proinsulin Syndrome. I. Design and Clinical Correlation. Front Endocrinol (Lausanne) 2022; 13:821069. [PMID: 35299972 PMCID: PMC8922534 DOI: 10.3389/fendo.2022.821069] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 01/17/2022] [Indexed: 12/16/2022] Open
Abstract
The mutant proinsulin syndrome is a monogenic cause of diabetes mellitus due to toxic misfolding of insulin's biosynthetic precursor. Also designated mutant INS-gene induced diabetes of the young (MIDY), this syndrome defines molecular determinants of foldability in the endoplasmic reticulum (ER) of β-cells. Here, we describe a peptide model of a key proinsulin folding intermediate and variants containing representative clinical mutations; the latter perturb invariant core sites in native proinsulin (LeuB15→Pro, LeuA16→Pro, and PheB24→Ser). The studies exploited a 49-residue single-chain synthetic precursor (designated DesDi), previously shown to optimize in vitro efficiency of disulfide pairing. Parent and variant peptides contain a single disulfide bridge (cystine B19-A20) to provide a model of proinsulin's first oxidative folding intermediate. The peptides were characterized by circular dichroism and redox stability in relation to effects of the mutations on (a) in vitro foldability of the corresponding insulin analogs and (b) ER stress induced in cell culture on expression of the corresponding variant proinsulins. Striking correlations were observed between peptide biophysical properties, degree of ER stress and age of diabetes onset (neonatal or adolescent). Our findings suggest that age of onset reflects the extent to which nascent structure is destabilized in proinsulin's putative folding nucleus. We envisage that such peptide models will enable high-resolution structural studies of key folding determinants and in turn permit molecular dissection of phenotype-genotype relationships in this monogenic diabetes syndrome. Our companion study (next article in this issue) employs two-dimensional heteronuclear NMR spectroscopy to define site-specific perturbations in the variant peptides.
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Affiliation(s)
- Balamurugan Dhayalan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Michael D. Glidden
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | | | - Yen-Shan Chen
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Yanwu Yang
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Nelson B. Phillips
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Faramarz Ismail-Beigi
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Mark A. Jarosinski
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | | | - Michael A. Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
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Dhayalan B, Weiss MA. Diabetes-Associated Mutations in Proinsulin Provide a "Molecular Rheostat" of Nascent Foldability. Curr Diab Rep 2022; 22:85-94. [PMID: 35119630 DOI: 10.1007/s11892-022-01447-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/04/2022] [Indexed: 11/28/2022]
Abstract
PURPOSE OF REVIEW Diabetes mellitus (DM) due to toxic misfolding of proinsulin variants provides a monogenic model of endoplasmic reticulum (ER) stress. The mutant proinsulin syndrome (also designated MIDY; Mutant INS-gene-induced Diabetes of Youth or Maturity-onset diabetes of the young 10 (MODY10)) ordinarily presents as permanent neonatal-onset DM, but specific amino-acid substitutions may also present later in childhood or adolescence. This review highlights structural mechanisms of proinsulin folding as inferred from phenotype-genotype relationships. RECENT FINDINGS MIDY mutations most commonly add or remove a cysteine, leading to a variant polypeptide containing an odd number of thiol groups. Such variants are associated with aberrant intermolecular disulfide pairing, ER stress, and neonatal β-cell dysfunction. Non-cysteine-related (NCR) mutations (occurring in both the B and A domains of proinsulin) define distinct determinants of foldability and vary in severity. The range of ages of onset, therefore, reflects a "molecular rheostat" connecting protein biophysics to quality-control ER checkpoints. Because in most mammalian cell lines even wild-type proinsulin exhibits limited folding efficiency, molecular barriers to folding uncovered by NCR MIDY mutations may pertain to β-cell dysfunction in non-syndromic type 2 DM due to INS-gene overexpression in the face of peripheral insulin resistance. Recent studies of MIDY mutations and related NCR variants, combining molecular and cell-based approaches, suggest that proinsulin has evolved at the edge of non-foldability. Chemical protein synthesis promises to enable comparative studies of "non-foldable" proinsulin variants to define key steps in wild-type biosynthesis. Such studies may create opportunities for novel therapeutic approaches to non-syndromic type 2 DM.
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Affiliation(s)
- Balamurugan Dhayalan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Michael A Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA.
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, 47907, USA.
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Lal RA, Moeller HP, Thomson EA, Horton TM, Lee S, Freeman R, Prahalad P, Poon ASY, Annes JP. Novel Pathogenic De Novo INS p.T97P Variant Presenting With Severe Neonatal DKA. Endocrinology 2022; 163:bqab246. [PMID: 34888628 PMCID: PMC9017997 DOI: 10.1210/endocr/bqab246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Indexed: 11/19/2022]
Abstract
Pathogenic INS gene mutations are causative for mutant INS-gene-induced diabetes of youth (MIDY). We characterize a novel de novo heterozygous INS gene mutation (c.289A>C, p.T97P) that presented in an autoantibody-negative 5-month-old male infant with severe diabetic ketoacidosis. In silico pathogenicity prediction tools provided contradictory interpretations, while structural modeling indicated a deleterious effect on proinsulin folding. Transfection of wildtype and INS p.T97P expression and luciferase reporter constructs demonstrated elevated intracellular mutant proinsulin levels and dramatically impaired proinsulin/insulin and luciferase secretion. Notably, proteasome inhibition partially and selectively rescued INS p.T97P-derived luciferase secretion. Additionally, expression of INS p.T97P caused increased intracellular proinsulin aggregate formation and XBP-1s protein levels, consistent with induction of endoplasmic reticulum stress. We conclude that INS p.T97P is a newly identified pathogenic A-chain variant that is causative for MIDY via disruption of proinsulin folding and processing with induction of the endoplasmic reticulum stress response.
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Affiliation(s)
- Rayhan A Lal
- Division of Endocrinology, Department of Medicine, Stanford University, Stanford, CA, USA
- Division of Endocrinology, Department of Pediatrics, Stanford University, Stanford, CA, USA
- Stanford Diabetes Research Center, Stanford, CA, USA
| | - Hannah P Moeller
- Stanford Diabetes Research Center, Stanford, CA, USA
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
| | - Ella A Thomson
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Timothy M Horton
- Division of Endocrinology, Department of Medicine, Stanford University, Stanford, CA, USA
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Sooyeon Lee
- Division of Endocrinology, Department of Medicine, Stanford University, Stanford, CA, USA
| | - Raquel Freeman
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Priya Prahalad
- Division of Endocrinology, Department of Pediatrics, Stanford University, Stanford, CA, USA
- Stanford Diabetes Research Center, Stanford, CA, USA
| | - Ada S Y Poon
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Justin P Annes
- Division of Endocrinology, Department of Medicine, Stanford University, Stanford, CA, USA
- Stanford Diabetes Research Center, Stanford, CA, USA
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Ngoc CTB, Dung VC, De Franco E, Lan NN, Thao BP, Khanh NN, Flanagan SE, Craig ME, Hoang NH, Dien TM. Genetic Etiology of Neonatal Diabetes Mellitus in Vietnamese Infants and Characteristics of Those With INS Gene Mutations. Front Endocrinol (Lausanne) 2022; 13:866573. [PMID: 35518939 PMCID: PMC9063464 DOI: 10.3389/fendo.2022.866573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/09/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Neonatal diabetes mellitus (NDM) is a rare (1:90,000 newborns) but potentially devastating metabolic disorder characterized by hyperglycemia combined with low levels of insulin. Dominantly-acting insulin (INS) gene mutations cause permanent NDM through single amino acid changes in the protein sequence leading to protein misfolding, which is retained within the endoplasmic reticulum (ER), causing ER stress and β-cell apoptosis. Over 90 dominantly-acting INS gene mutations have been identified in individuals with permanent NDM. PATIENTS AND METHODS The study included 70 infants diagnosed with NDM in the first year of life between May 2008 and May 2021 at the Vietnam National Children's Hospital. Sequencing analysis of all the genes known to cause NDM was performed at the Exeter Genomic Laboratory, UK. Clinical characteristics, molecular genetics, and annual data relating to glycemic control (HbA1c) and severe hypoglycemia of those with INS mutations were collected. The main outcomes of interest were HbA1c, daily insulin dose, growth, and cognitive/motor development. RESULTS Fifty-five of 70 infants (78.5%) with NDM harbored a mutation in a known disease-causing gene and of these, 10 had six different de novo heterozygous INS mutations. Mean gestational age was 38.1 ± 2.5 weeks and mean birth weight was 2.8 ± 0.5 g. They presented with NDM at 20 ± 17 weeks of age; 6/10 had diabetic ketoacidosis with pH 7.13 ± 0.26; plasma glucose level 32.6 ± 14.3 mmol/l and HbA1C 81 ± 15% mmol/mol. After 5.5 ± 4.8 years of insulin treatment, 9/10 have normal development with a developmental quotient of 80-100% and HbA1C 64 ± 7.3 mmol/mol, 9/10 have normal height, weight, and BMI on follow-up. CONCLUSIONS We report a series of Vietnamese NDM cases with dominant INS mutations. INS mutations are the third commonest cause of permanent NDM. We recommend screening of the INS gene in all children diagnosed with diabetes in the first year of life.
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Affiliation(s)
- Can Thi Bich Ngoc
- The Center of Endocrinology, Metabolism, Genetics, and Molecular Therapy, Vietnam National Children’s Hospital, Hanoi, Vietnam
- Pediatric Department, Hanoi Medical University, Hanoi, Vietnam
| | - Vu Chi Dung
- The Center of Endocrinology, Metabolism, Genetics, and Molecular Therapy, Vietnam National Children’s Hospital, Hanoi, Vietnam
| | - Elisa De Franco
- Institute of Biomedical and Clinical Science, College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | - Nguyen Ngoc Lan
- Institute of Genome Research, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
| | - Bui Phuong Thao
- The Center of Endocrinology, Metabolism, Genetics, and Molecular Therapy, Vietnam National Children’s Hospital, Hanoi, Vietnam
| | - Nguyen Ngoc Khanh
- The Center of Endocrinology, Metabolism, Genetics, and Molecular Therapy, Vietnam National Children’s Hospital, Hanoi, Vietnam
| | - Sarah E. Flanagan
- Institute of Biomedical and Clinical Science, College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | - Maria E. Craig
- Institute of Endocrinology and Diabetes, The Children’s Hospital at Westmead/Discipline of Child and Adolescent Health, University of Sydney, Sydney, NSW, Australia
- School of Clinical Medicine, University of New South Wales Medicine and Health, Discipline of Paediatrics and Child Health, Sydney, NSW, Australia
| | - Nguyen Huy Hoang
- Institute of Genome Research, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
| | - Tran Minh Dien
- The Center of Endocrinology, Metabolism, Genetics, and Molecular Therapy, Vietnam National Children’s Hospital, Hanoi, Vietnam
- *Correspondence: Tran Minh Dien,
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32
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Li H, Sun S. Protein Aggregation in the ER: Calm behind the Storm. Cells 2021; 10:cells10123337. [PMID: 34943844 PMCID: PMC8699410 DOI: 10.3390/cells10123337] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 02/06/2023] Open
Abstract
As one of the largest organelles in eukaryotic cells, the endoplasmic reticulum (ER) plays a vital role in the synthesis, folding, and assembly of secretory and membrane proteins. To maintain its homeostasis, the ER is equipped with an elaborate network of protein folding chaperones and multiple quality control pathways whose cooperative actions safeguard the fidelity of protein biogenesis. However, due to genetic abnormalities, the error-prone nature of protein folding and assembly, and/or defects or limited capacities of the protein quality control systems, nascent proteins may become misfolded and fail to exit the ER. If not cleared efficiently, the progressive accumulation of misfolded proteins within the ER may result in the formation of toxic protein aggregates, leading to the so-called “ER storage diseases”. In this review, we first summarize our current understanding of the protein folding and quality control networks in the ER, including chaperones, unfolded protein response (UPR), ER-associated protein degradation (ERAD), and ER-selective autophagy (ER-phagy). We then survey recent research progress on a few ER storage diseases, with a focus on the role of ER quality control in the disease etiology, followed by a discussion on outstanding questions and emerging concepts in the field.
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Affiliation(s)
- Haisen Li
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA;
| | - Shengyi Sun
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA;
- Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Correspondence:
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Alam M, Arunagiri A, Haataja L, Torres M, Larkin D, Kappler J, Jin N, Arvan P. Predisposition to Proinsulin Misfolding as a Genetic Risk to Diet-Induced Diabetes. Diabetes 2021; 70:2580-2594. [PMID: 34462258 PMCID: PMC8564407 DOI: 10.2337/db21-0422] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 08/10/2021] [Indexed: 02/06/2023]
Abstract
Throughout evolution, proinsulin has exhibited significant sequence variation in both C-peptide and insulin moieties. As the proinsulin coding sequence evolves, the gene product continues to be under selection pressure both for ultimate insulin bioactivity and for the ability of proinsulin to be folded for export through the secretory pathway of pancreatic β-cells. The substitution proinsulin-R(B22)E is known to yield a bioactive insulin, although R(B22)Q has been reported as a mutation that falls within the spectrum of mutant INS-gene-induced diabetes of youth. Here, we have studied mice expressing heterozygous (or homozygous) proinsulin-R(B22)E knocked into the Ins2 locus. Neither females nor males bearing the heterozygous mutation developed diabetes at any age examined, but subtle evidence of increased proinsulin misfolding in the endoplasmic reticulum is demonstrable in isolated islets from the heterozygotes. Moreover, males have indications of glucose intolerance, and within a few weeks of exposure to a high-fat diet, they developed frank diabetes. Diabetes was more severe in homozygotes, and the development of disease paralleled a progressive heterogeneity of β-cells with increasing fractions of proinsulin-rich/insulin-poor cells as well as glucagon-positive cells. Evidently, subthreshold predisposition to proinsulin misfolding can go undetected but provides genetic susceptibility to diet-induced β-cell failure.
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Affiliation(s)
- Maroof Alam
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI
| | - Anoop Arunagiri
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI
| | - Leena Haataja
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI
| | - Mauricio Torres
- Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI
| | - Dennis Larkin
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI
| | - John Kappler
- Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO
- Department of Immunology and Genomic Medicine, National Jewish Health, Denver, CO
| | - Niyun Jin
- Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO
- Department of Immunology and Genomic Medicine, National Jewish Health, Denver, CO
| | - Peter Arvan
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI
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Amirruddin NS, Tan WX, Tan YS, Gardner DSL, Bee YM, Verma CS, Hoon S, Lee KO, Teo AKK. Progressive endoplasmic reticulum stress over time due to human insulin gene mutation contributes to pancreatic beta cell dysfunction. Diabetologia 2021; 64:2534-2549. [PMID: 34448879 DOI: 10.1007/s00125-021-05530-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 05/14/2021] [Indexed: 10/20/2022]
Abstract
AIMS/HYPOTHESIS We studied the effects of heterozygous human INS gene mutations on insulin secretion, endoplasmic reticulum (ER) stress and other mechanisms in both MIN6 and human induced pluripotent stem cells (hiPSC)-derived beta-like cells, as well as the effects of prolonged overexpression of mutant human INS in MIN6 cells. METHODS We modelled the structure of mutant C109Y and G32V proinsulin computationally to examine the in silico effects. We then overexpressed either wild-type (WT), mutant (C109Y or G32V), or both WT and mutant human preproinsulin in MIN6 cells, both transiently and stably over several weeks. We measured the levels of human and rodent insulin secreted, and examined the transcript and protein levels of several ER stress and apoptotic markers. We also reprogrammed human donor fibroblasts heterozygous for the C109Y mutation into hiPSCs and differentiated these into pancreatic beta-like cells, which were subjected to single-cell RNA-sequencing and transcript and protein analyses for ER stress and apoptotic markers. RESULTS The computational modelling studies, and short-term and long-term expression studies in beta cells, revealed the presence of ER stress, organelle changes and insulin processing defects, resulting in a decreased amount of insulin secreted but not the ability to secrete insulin. By 9 weeks of expression of mutant human INS, dominant-negative effects of mutant INS were evident and beta cell insulin secretory capacity declined. INS+/C109Y patient-derived beta-like cells and single-cell RNA-sequencing analyses then revealed compensatory upregulation in genes involved in insulin secretion, processing and inflammatory response. CONCLUSIONS/INTERPRETATION The results provide deeper insights into the mechanisms of beta cell failure during INS mutation-mediated diabetes disease progression. Decreasing spliced X-box binding protein 1 (sXBP1) or inflammatory response could be avenues to restore the function of the remaining WT INS allele.
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Affiliation(s)
- Nur Shabrina Amirruddin
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore
| | - Wei Xuan Tan
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore
| | - Yaw Sing Tan
- Bioinformatics Institute, A*STAR, Singapore, Republic of Singapore
| | - Daphne Su-Lyn Gardner
- Department of Endocrinology, Singapore General Hospital, Singapore, Republic of Singapore
| | - Yong Mong Bee
- Department of Endocrinology, Singapore General Hospital, Singapore, Republic of Singapore
| | - Chandra Shekhar Verma
- Bioinformatics Institute, A*STAR, Singapore, Republic of Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Republic of Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Republic of Singapore
| | - Shawn Hoon
- Molecular Engineering Laboratory, IMCB, A*STAR, Singapore, Republic of Singapore
| | - Kok Onn Lee
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore
| | - Adrian Kee Keong Teo
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore.
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore.
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore.
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PGRMC1 acts as a size-selective cargo receptor to drive ER-phagic clearance of mutant prohormones. Nat Commun 2021; 12:5991. [PMID: 34645803 PMCID: PMC8514460 DOI: 10.1038/s41467-021-26225-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 09/20/2021] [Indexed: 02/06/2023] Open
Abstract
The reticulon-3 (RTN3)-driven targeting complex promotes clearance of misfolded prohormones from the endoplasmic reticulum (ER) for lysosomal destruction by ER-phagy. Because RTN3 resides in the cytosolic leaflet of the ER bilayer, the mechanism of selecting misfolded prohormones as ER-phagy cargo on the luminal side of the ER membrane remains unknown. Here we identify the ER transmembrane protein PGRMC1 as an RTN3-binding partner. Via its luminal domain, PGRMC1 captures misfolded prohormones, targeting them for RTN3-dependent ER-phagy. PGRMC1 selects cargos that are smaller than the large size of other reported ER-phagy substrates. Cargos for PGRMC1 include mutant proinsulins that block secretion of wildtype proinsulin through dominant-negative interactions within the ER, causing insulin-deficiency. Chemical perturbation of PGRMC1 partially restores WT insulin storage by preventing ER-phagic degradation of WT and mutant proinsulin. Thus, PGRMC1 acts as a size-selective cargo receptor during RTN3-dependent ER-phagy, and is a potential therapeutic target for diabetes.
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36
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Herlea-Pana O, Eeda V, Undi RB, Lim HY, Wang W. Pharmacological Inhibition of Inositol-Requiring Enzyme 1α RNase Activity Protects Pancreatic Beta Cell and Improves Diabetic Condition in Insulin Mutation-Induced Diabetes. Front Endocrinol (Lausanne) 2021; 12:749879. [PMID: 34675883 PMCID: PMC8524045 DOI: 10.3389/fendo.2021.749879] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/20/2021] [Indexed: 12/25/2022] Open
Abstract
β-cell ER stress plays an important role in β-cell dysfunction and death during the pathogenesis of diabetes. Proinsulin misfolding is regarded as one of the primary initiating factors of ER stress and unfolded protein response (UPR) activation in β-cells. Here, we found that the ER stress sensor inositol-requiring enzyme 1α (IRE1α) was activated in the Akita mice, a mouse model of mutant insulin gene-induced diabetes of youth (MIDY), a monogenic diabetes. Normalization of IRE1α RNase hyperactivity by pharmacological inhibitors significantly ameliorated the hyperglycemic conditions and increased serum insulin levels in Akita mice. These benefits were accompanied by a concomitant protection of functional β-cell mass, as shown by the suppression of β-cell apoptosis, increase in mature insulin production and reduction of proinsulin level. At the molecular level, we observed that the expression of genes associated with β-cell identity and function was significantly up-regulated and ER stress and its associated inflammation and oxidative stress were suppressed in islets from Akita mice treated with IRE1α RNase inhibitors. This study provides the evidence of the in vivo efficacy of IRE1α RNase inhibitors in Akita mice, pointing to the possibility of targeting IRE1α RNase as a therapeutic direction for the treatment of diabetes.
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Affiliation(s)
- Oana Herlea-Pana
- Department of Medicine, Division of Endocrinology, Harold Hamm Diabetes Center, Oklahoma City, OK, United States
| | - Venkateswararao Eeda
- Department of Medicine, Division of Endocrinology, Harold Hamm Diabetes Center, Oklahoma City, OK, United States
| | - Ram Babu Undi
- Department of Physiology, Harold Hamm Diabetes Center, The University of Oklahoma Health Science Center, Oklahoma City, OK, United States
| | - Hui-Ying Lim
- Department of Physiology, Harold Hamm Diabetes Center, The University of Oklahoma Health Science Center, Oklahoma City, OK, United States
| | - Weidong Wang
- Department of Medicine, Division of Endocrinology, Harold Hamm Diabetes Center, Oklahoma City, OK, United States
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37
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Dhayalan B, Chatterjee D, Chen YS, Weiss MA. Structural Lessons From the Mutant Proinsulin Syndrome. Front Endocrinol (Lausanne) 2021; 12:754693. [PMID: 34659132 PMCID: PMC8514764 DOI: 10.3389/fendo.2021.754693] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/13/2021] [Indexed: 12/30/2022] Open
Abstract
Insight into folding mechanisms of proinsulin has been provided by analysis of dominant diabetes-associated mutations in the human insulin gene (INS). Such mutations cause pancreatic β-cell dysfunction due to toxic misfolding of a mutant proinsulin and impairment in trans of wild-type insulin secretion. Anticipated by the "Akita" mouse (a classical model of monogenic diabetes mellitus; DM), this syndrome illustrates the paradigm endoreticulum (ER) stress leading to intracellular proteotoxicity. Diverse clinical mutations directly or indirectly perturb native disulfide pairing leading to protein misfolding and aberrant aggregation. Although most introduce or remove a cysteine (Cys; leading in either case to an unpaired thiol group), non-Cys-related mutations identify key determinants of folding efficiency. Studies of such mutations suggest that the hormone's evolution has been constrained not only by structure-function relationships, but also by the susceptibility of its single-chain precursor to impaired foldability. An intriguing hypothesis posits that INS overexpression in response to peripheral insulin resistance likewise leads to chronic ER stress and β-cell dysfunction in the natural history of non-syndromic Type 2 DM. Cryptic contributions of conserved residues to folding efficiency, as uncovered by rare genetic variants, define molecular links between biophysical principles and the emerging paradigm of Darwinian medicine: Biosynthesis of proinsulin at the edge of non-foldability provides a key determinant of "diabesity" as a pandemic disease of civilization.
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Affiliation(s)
| | | | | | - Michael A. Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
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38
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Yong J, Johnson JD, Arvan P, Han J, Kaufman RJ. Therapeutic opportunities for pancreatic β-cell ER stress in diabetes mellitus. Nat Rev Endocrinol 2021; 17:455-467. [PMID: 34163039 PMCID: PMC8765009 DOI: 10.1038/s41574-021-00510-4] [Citation(s) in RCA: 142] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/06/2021] [Indexed: 02/06/2023]
Abstract
Diabetes mellitus is characterized by the failure of insulin-secreting pancreatic β-cells (or β-cell death) due to either autoimmunity (type 1 diabetes mellitus) or failure to compensate for insulin resistance (type 2 diabetes mellitus; T2DM). In addition, mutations of critical genes cause monogenic diabetes. The endoplasmic reticulum (ER) is the primary site for proinsulin folding; therefore, ER proteostasis is crucial for both β-cell function and survival under physiological and pathophysiological challenges. Importantly, the ER is also the major intracellular Ca2+ storage organelle, generating Ca2+ signals that contribute to insulin secretion. ER stress is associated with the pathogenesis of diabetes mellitus. In this Review, we summarize the mutations in monogenic diabetes that play causal roles in promoting ER stress in β-cells. Furthermore, we discuss the possible mechanisms responsible for ER proteostasis imbalance with a focus on T2DM, in which both genetics and environment are considered important in promoting ER stress in β-cells. We also suggest that controlled insulin secretion from β-cells might reduce the progression of a key aspect of the metabolic syndrome, namely nonalcoholic fatty liver disease. Finally, we evaluate potential therapeutic approaches to treat T2DM, including the optimization and protection of functional β-cell mass in individuals with T2DM.
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Affiliation(s)
- Jing Yong
- Degenerative Diseases Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - James D Johnson
- Department of Cellular and Physiological Sciences & Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Peter Arvan
- Division of Metabolism Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - Jaeseok Han
- Soonchunhyang Institute of Medi-bio Science (SIMS), Soonchunhyang University, Cheonan-si, Choongchungnam-do, Republic of Korea.
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA.
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39
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Ikle JM, Gloyn AL. 100 YEARS OF INSULIN: A brief history of diabetes genetics: insights for pancreatic beta-cell development and function. J Endocrinol 2021; 250:R23-R35. [PMID: 34196608 PMCID: PMC9037733 DOI: 10.1530/joe-21-0067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 06/30/2021] [Indexed: 12/30/2022]
Abstract
Since the discovery of insulin 100 years ago, our knowledge and understanding of diabetes have grown exponentially. Specifically, with regards to the genetics underlying diabetes risk, our discoveries have paralleled developments in our understanding of the human genome and our ability to study genomics at scale; these advancements in genetics have both accompanied and led to those in diabetes treatment. This review will explore the timeline and history of gene discovery and how this has coincided with progress in the fields of genomics. Examples of genetic causes of monogenic diabetes are presented and the continuing expansion of allelic series in these genes and the challenges these now cause for diagnostic interpretation along with opportunities for patient stratification are discussed.
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Affiliation(s)
- Jennifer M Ikle
- Division of Endocrinology, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA
| | - Anna L Gloyn
- Division of Endocrinology, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA
- Stanford Diabetes Research Center, Stanford University, Stanford, California, USA
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40
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Ramzy A, Kieffer TJ. Altered islet prohormone processing: A cause or consequence of diabetes? Physiol Rev 2021; 102:155-208. [PMID: 34280055 DOI: 10.1152/physrev.00008.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Peptide hormones are first produced as larger precursor prohormones that require endoproteolytic cleavage to liberate the mature hormones. A structurally conserved but functionally distinct family of nine prohormone convertase enzymes (PCs) are responsible for cleavage of protein precursors of which PC1/3 and PC2 are known to be exclusive to neuroendocrine cells and responsible for prohormone cleavage. Differential expression of PCs within tissues define prohormone processing; whereas glucagon is the major product liberated from proglucagon via PC2 in pancreatic α-cells, proglucagon is preferentially processed by PC1/3 in intestinal L cells to produce glucagon-like peptides 1 and 2 (GLP-1, GLP-2). Beyond our understanding of processing of islet prohormones in healthy islets, there is convincing evidence that proinsulin, proIAPP, and proglucagon processing is altered during prediabetes and diabetes. There is predictive value of elevated circulating proinsulin or proinsulin : C-peptide ratio for progression to type 2 diabetes and elevated proinsulin or proinsulin : C-peptide is predictive for development of type 1 diabetes in at risk groups. After onset of diabetes, patients have elevated circulating proinsulin and proIAPP and proinsulin may be an autoantigen in type 1 diabetes. Further, preclinical studies reveal that α-cells have altered proglucagon processing during diabetes leading to increased GLP-1 production. We conclude that despite strong associative data, current evidence is inconclusive on the potential causal role of impaired prohormone processing in diabetes, and suggest that future work should focus on resolving the question of whether altered prohormone processing is a causal driver or merely a consequence of diabetes pathology.
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Affiliation(s)
- Adam Ramzy
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.,Department of Surgery, University of British Columbia, Vancouver, BC, Canada.,School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
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41
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Song J. Adenosine triphosphate energy-independently controls protein homeostasis with unique structure and diverse mechanisms. Protein Sci 2021; 30:1277-1293. [PMID: 33829608 PMCID: PMC8197423 DOI: 10.1002/pro.4079] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/30/2021] [Accepted: 04/02/2021] [Indexed: 02/06/2023]
Abstract
Proteins function in the crowded cellular environments with high salt concentrations, thus facing tremendous challenges of misfolding/aggregation which represents a pathological hallmark of aging and an increasing spectrum of human diseases. Recently, intrinsically disordered regions (IDRs) were recognized to drive liquid-liquid phase separation (LLPS), a common principle for organizing cellular membraneless organelles (MLOs). ATP, the universal energy currency for all living cells, mysteriously has concentrations of 2-12 mM, much higher than required for its previously-known functions. Only recently, ATP was decoded to behave as a biological hydrotrope to inhibit protein LLPS and aggregation at mM. We further revealed that ATP also acts as a bivalent binder, which not only biphasically modulates LLPS driven by IDRs of human and viral proteins, but also bind to the conserved nucleic-acid-binding surfaces of the folded proteins. Most unexpectedly, ATP appears to act as a hydration mediator to antagonize the crowding-induced destabilization as well as to enhance folding of proteins without significant binding. Here, this review focuses on summarizing the results of these biophysical studies and discussing their implications in an evolutionary context. By linking triphosphate with unique hydration property to adenosine, ATP appears to couple the ability for establishing hydrophobic, π-π, π-cation and electrostatic interactions to the capacity in mediating hydration of proteins, which is at the heart of folding, dynamics, stability, phase separation and aggregation. Consequently, ATP acquired a category of functions at ~mM to energy-independently control protein homeostasis with diverse mechanisms, thus implying a link between cellular ATP concentrations and protein-aggregation diseases.
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Affiliation(s)
- Jianxing Song
- Department of Biological Sciences, Faculty of ScienceNational University of SingaporeSingaporeSingapore
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42
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Støy J, De Franco E, Ye H, Park SY, Bell GI, Hattersley AT. In celebration of a century with insulin - Update of insulin gene mutations in diabetes. Mol Metab 2021; 52:101280. [PMID: 34174481 PMCID: PMC8513141 DOI: 10.1016/j.molmet.2021.101280] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/17/2021] [Accepted: 06/17/2021] [Indexed: 02/06/2023] Open
Abstract
Background While insulin has been central to the pathophysiology and treatment of patients with diabetes for the last 100 years, it has only been since 2007 that genetic variation in the INS gene has been recognised as a major cause of monogenic diabetes. Both dominant and recessive mutations in the INS gene are now recognised as important causes of neonatal diabetes and offer important insights into both the structure and function of insulin. It is also recognised that in rare cases, mutations in the INS gene can be found in patients with diabetes diagnosed outside the first year of life. Scope of Review This review examines the genetics and clinical features of monogenic diabetes resulting from INS gene mutations from the first description in 2007 and includes information from 389 patients from 292 families diagnosed in Exeter with INS gene mutations. We discuss the implications for diagnosing and treating this subtype of monogenic diabetes. Major Conclusions The dominant mutations in the INS gene typically affect the secondary structure of the insulin protein, usually by disrupting the 3 disulfide bonds in mature insulin. The resulting misfolded protein results in ER stress and beta-cell destruction. In contrast, recessive INS gene mutations typically result in no functional protein being produced due to reduced insulin biosynthesis or loss-of-function mutations in the insulin protein. There are clinical differences between the two genetic aetiologies, between the specific mutations, and within patients with identical mutations.
Dominant and recessive mutations in the insulin (INS) gene are important causes of neonatal diabetes. Associated phenotypes are variable in terms of age at diabetes onset, birth weight and treatment requirements. Dominant mutations affect the secondary structure of the insulin protein, resulting in beta-cell ER stress and destruction. Recessive mutations result in reduced insulin biosynthesis or loss-of-function mutations of the insulin protein. The studies of these forms of diabetes offer important insights into the structure, biosynthesis and secretion of insulin.
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Affiliation(s)
- Julie Støy
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark.
| | - Elisa De Franco
- Institute of Biomedical and Clinical Science, College of Medicine and Health, University of Exeter, Exeter, United Kingdom.
| | - Honggang Ye
- Department of Medicine, The University of Chicago, Chicago, IL, USA.
| | - Soo-Young Park
- Department of Medicine, The University of Chicago, Chicago, IL, USA.
| | - Graeme I Bell
- Department of Medicine, The University of Chicago, Chicago, IL, USA.
| | - Andrew T Hattersley
- Institute of Biomedical and Clinical Science, College of Medicine and Health, University of Exeter, Exeter, United Kingdom.
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Rodriguez-Calvo T, Chen YC, Verchere CB, Haataja L, Arvan P, Leete P, Richardson SJ, Morgan NG, Qian WJ, Pugliese A, Atkinson M, Evans-Molina C, Sims EK. Altered β-Cell Prohormone Processing and Secretion in Type 1 Diabetes. Diabetes 2021; 70:1038-1050. [PMID: 33947721 PMCID: PMC8173804 DOI: 10.2337/dbi20-0034] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Accepted: 02/26/2021] [Indexed: 02/06/2023]
Abstract
Analysis of data from clinical cohorts, and more recently from human pancreatic tissue, indicates that reduced prohormone processing is an early and persistent finding in type 1 diabetes. In this article, we review the current state of knowledge regarding alterations in islet prohormone expression and processing in type 1 diabetes and consider the clinical impact of these findings. Lingering questions, including pathologic etiologies and consequences of altered prohormone expression and secretion in type 1 diabetes, and the natural history of circulating prohormone production in health and disease, are considered. Finally, key next steps required to move forward in this area are outlined, including longitudinal testing of relevant clinical populations, studies that probe the genetics of altered prohormone processing, the need for combined functional and histologic testing of human pancreatic tissues, continued interrogation of the intersection between prohormone processing and autoimmunity, and optimal approaches for analysis. Successful resolution of these questions may offer the potential to use altered prohormone processing as a biomarker to inform therapeutic strategies aimed at personalized intervention during the natural history of type 1 diabetes and as a pathogenic anchor for identification of potential disease-specific endotypes.
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Affiliation(s)
- Teresa Rodriguez-Calvo
- Institute of Diabetes Research, Helmholtz Zentrum Muenchen - German Research Center for Environmental Health, Munich-Neuherberg, Germany
| | - Yi-Chun Chen
- Department of Surgery, University of British Columbia and BC Children's Hospital Research Institute, Vancouver, Canada
| | - C Bruce Verchere
- Departments of Surgery and Pathology and Laboratory Medicine, University of British Columbia, Centre for Molecular Medicine and Therapeutics, and BC Children's Hospital Research Institute, Vancouver, Canada
| | - Leena Haataja
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI
| | - Pia Leete
- Exeter Centre of Excellence for Diabetes, Institute of Biomedical & Clinical Science, University of Exeter Medical School, Exeter, U.K
| | - Sarah J Richardson
- Exeter Centre of Excellence for Diabetes, Institute of Biomedical & Clinical Science, University of Exeter Medical School, Exeter, U.K
| | - Noel G Morgan
- Exeter Centre of Excellence for Diabetes, Institute of Biomedical & Clinical Science, University of Exeter Medical School, Exeter, U.K
| | - Wei-Jun Qian
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA
| | - Alberto Pugliese
- Diabetes Research Institute, Leonard M. Miller School of Medicine, University of Miami, Miami, FL
| | - Mark Atkinson
- Departments of Pathology and Pediatrics, Diabetes Institute, University of Florida, Gainesville, FL
| | - Carmella Evans-Molina
- Center for Diabetes and Metabolic Diseases, Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN
- Departments of Cellular and Integrative Physiology, Medicine, and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN
- Richard L. Roudebush VA Medical Center, Indianapolis, IN
| | - Emily K Sims
- Center for Diabetes and Metabolic Diseases, Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN
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Dhayalan B, Chatterjee D, Chen YS, Weiss MA. Diabetes mellitus due to toxic misfolding of proinsulin variants. Mol Metab 2021:101229. [PMID: 33823319 DOI: 10.1016/j.molmet.2021.101229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/10/2021] [Accepted: 03/29/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Dominant mutations in the human insulin gene (INS) lead to pancreatic β-cell dysfunction and diabetes mellitus (DM) due to toxic misfolding of a mutant proinsulin. Analogous to a classical mouse model of monogenic DM ("Akita"), this syndrome highlights the susceptibility of β-cells to endoreticulum (ER) stress due to protein misfolding and aberrant aggregation. SCOPE OF REVIEW Diverse clinical mutations directly or indirectly perturb native disulfide pairing. Whereas most introduce or remove a cysteine (Cys; leading in either case to an unpaired thiol group), non-Cys-related mutations identify key determinants of folding efficiency. Studies of such mutations suggest that the hormone's evolution has been constrained not only by structure-function relationships but also by the susceptibility of its single-chain precursor to impaired foldability. An intriguing hypothesis posits that INS overexpression in response to peripheral insulin resistance likewise leads to chronic ER stress and β-cell dysfunction in the natural history of nonsyndromic Type 2 DM. MAJOR CONCLUSIONS Cryptic contributions of conserved residues to folding efficiency, as uncovered by rare genetic variants, define molecular links between biophysical principles and the emerging paradigm of Darwinian medicine: Biosynthesis of proinsulin at the edge of nonfoldability provides a key determinant of "diabesity" as a pandemic disease of civilization.
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Affiliation(s)
- Balamurugan Dhayalan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Deepak Chatterjee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Yen-Shan Chen
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Michael A Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Bourgeois S, Sawatani T, Van Mulders A, De Leu N, Heremans Y, Heimberg H, Cnop M, Staels W. Towards a Functional Cure for Diabetes Using Stem Cell-Derived Beta Cells: Are We There Yet? Cells 2021; 10:cells10010191. [PMID: 33477961 PMCID: PMC7835995 DOI: 10.3390/cells10010191] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/12/2021] [Indexed: 02/06/2023] Open
Abstract
Diabetes mellitus is a pandemic metabolic disorder that results from either the autoimmune destruction or the dysfunction of insulin-producing pancreatic beta cells. A promising cure is beta cell replacement through the transplantation of islets of Langerhans. However, donor shortage hinders the widespread implementation of this therapy. Human pluripotent stem cells, including embryonic stem cells and induced pluripotent stem cells, represent an attractive alternative beta cell source for transplantation. Although major advances over the past two decades have led to the generation of stem cell-derived beta-like cells that share many features with genuine beta cells, producing fully mature beta cells remains challenging. Here, we review the current status of beta cell differentiation protocols and highlight specific challenges that are associated with producing mature beta cells. We address the challenges and opportunities that are offered by monogenic forms of diabetes. Finally, we discuss the remaining hurdles for clinical application of stem cell-derived beta cells and the status of ongoing clinical trials.
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Affiliation(s)
- Stephanie Bourgeois
- Beta Cell Neogenesis (BENE) Research Group, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium; (S.B.); (A.V.M.); (N.D.L.); (Y.H.); (H.H.)
| | - Toshiaki Sawatani
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, 1070 Brussels, Belgium; (T.S.); (M.C.)
| | - Annelore Van Mulders
- Beta Cell Neogenesis (BENE) Research Group, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium; (S.B.); (A.V.M.); (N.D.L.); (Y.H.); (H.H.)
| | - Nico De Leu
- Beta Cell Neogenesis (BENE) Research Group, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium; (S.B.); (A.V.M.); (N.D.L.); (Y.H.); (H.H.)
- Department of Endocrinology, University Hospital Brussels, 1090 Brussels, Belgium
- Department of Endocrinology, ASZ Aalst, 9300 Aalst, Belgium
| | - Yves Heremans
- Beta Cell Neogenesis (BENE) Research Group, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium; (S.B.); (A.V.M.); (N.D.L.); (Y.H.); (H.H.)
| | - Harry Heimberg
- Beta Cell Neogenesis (BENE) Research Group, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium; (S.B.); (A.V.M.); (N.D.L.); (Y.H.); (H.H.)
| | - Miriam Cnop
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, 1070 Brussels, Belgium; (T.S.); (M.C.)
- Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Willem Staels
- Beta Cell Neogenesis (BENE) Research Group, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium; (S.B.); (A.V.M.); (N.D.L.); (Y.H.); (H.H.)
- Service of Pediatric Endocrinology, Department of Pediatrics, KidZ Health Castle, Universitair Ziekenhuis Brussel (UZ Brussel), 1090 Brussels, Belgium
- Correspondence: ; Tel.: +32-0-24774473
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Liu M, Huang Y, Xu X, Li X, Alam M, Arunagiri A, Haataja L, Ding L, Wang S, Itkin-Ansari P, Kaufman RJ, Tsai B, Qi L, Arvan P. Normal and defective pathways in biogenesis and maintenance of the insulin storage pool. J Clin Invest 2021; 131:142240. [PMID: 33463547 PMCID: PMC7810482 DOI: 10.1172/jci142240] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Both basal and glucose-stimulated insulin release occur primarily by insulin secretory granule exocytosis from pancreatic β cells, and both are needed to maintain normoglycemia. Loss of insulin-secreting β cells, accompanied by abnormal glucose tolerance, may involve simple exhaustion of insulin reserves (which, by immunostaining, appears as a loss of β cell identity), or β cell dedifferentiation, or β cell death. While various sensing and signaling defects can result in diminished insulin secretion, somewhat less attention has been paid to diabetes risk caused by insufficiency in the biosynthetic generation and maintenance of the total insulin granule storage pool. This Review offers an overview of insulin biosynthesis, beginning with the preproinsulin mRNA (translation and translocation into the ER), proinsulin folding and export from the ER, and delivery via the Golgi complex to secretory granules for conversion to insulin and ultimate hormone storage. All of these steps are needed for generation and maintenance of the total insulin granule pool, and defects in any of these steps may, weakly or strongly, perturb glycemic control. The foregoing considerations have obvious potential relevance to the pathogenesis of type 2 diabetes and some forms of monogenic diabetes; conceivably, several of these concepts might also have implications for β cell failure in type 1 diabetes.
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Affiliation(s)
- Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Yumeng Huang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Xiaoxi Xu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Xin Li
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Maroof Alam
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Anoop Arunagiri
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Leena Haataja
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Li Ding
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Shusen Wang
- Organ Transplant Center, Tianjin First Central Hospital, Tianjin, China
| | | | - Randal J. Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Billy Tsai
- Department of Cell and Developmental Biology, and
| | - Ling Qi
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Peter Arvan
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
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Yang Y, Shu H, Hu J, Li L, Wang J, Chen T, Zhen J, Sun J, Feng W, Xiong Y, Huang Y, Li X, Zhang K, Fan Z, Guo H, Liu M. A Novel Nonsense INS Mutation Causes Inefficient Preproinsulin Translocation Into the Endoplasmic Reticulum. Front Endocrinol (Lausanne) 2021; 12:774634. [PMID: 35069438 PMCID: PMC8769375 DOI: 10.3389/fendo.2021.774634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 12/06/2021] [Indexed: 11/13/2022] Open
Abstract
Preproinsulin (PPI) translocation across the membrane of the endoplasmic reticulum (ER) is the first and critical step of insulin biosynthesis. Inefficient PPI translocation caused by signal peptide (SP) mutations can lead to β-cell failure and diabetes. However, the effect of proinsulin domain on the efficiency of PPI translocation remains unknown. With whole exome sequencing, we identified a novel INS nonsense mutation resulting in an early termination at the 46th residue of PPI (PPI-R46X) in two unrelated patients with early-onset diabetes. We examined biological behaviors of the mutant and compared them to that of an established neonatal diabetes causing mutant PPI-C96Y. Although both mutants were retained in the cells, unlike C96Y, R46X did not induce ER stress or form abnormal disulfide-linked proinsulin complexes. More importantly, R46X did not interact with co-expressed wild-type (WT) proinsulin in the ER, and did not impair proinsulin-WT folding, trafficking, and insulin production. Metabolic labeling experiments established that, despite with an intact SP, R46X failed to be efficiently translocated into the ER, suggesting that proinsulin domain downstream of SP plays an important unrecognized role in PPI translocation across the ER membrane. The study not only expends the list of INS mutations associated with diabetes, but also provides genetic and biological evidence underlying the regulation mechanism of PPI translocation.
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Affiliation(s)
- Ying Yang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Hua Shu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Jingxin Hu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Lei Li
- Department of Endocrinology, The Second Part of Jilin University First Hospital, Jilin, China
| | - Jianyu Wang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Tingting Chen
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Jinyang Zhen
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Jinhong Sun
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Wenli Feng
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Yi Xiong
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Yumeng Huang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Xin Li
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Kai Zhang
- Department of Technology Services, RSR Tianjin Biotech Co., Tianjin, China
| | - Zhenqian Fan
- Department of Endocrinology and Metabolism, The Second Hospital of Tianjin Medical University, Tianjin, China
- *Correspondence: Ming Liu, ; Zhenqian Fan, ; Hui Guo,
| | - Hui Guo
- Department of Endocrinology, The Second Part of Jilin University First Hospital, Jilin, China
- *Correspondence: Ming Liu, ; Zhenqian Fan, ; Hui Guo,
| | - Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
- *Correspondence: Ming Liu, ; Zhenqian Fan, ; Hui Guo,
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Poothong J, Jang I, Kaufman RJ. Defects in Protein Folding and/or Quality Control Cause Protein Aggregation in the Endoplasmic Reticulum. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2021; 59:115-143. [PMID: 34050864 DOI: 10.1007/978-3-030-67696-4_6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Protein aggregation is now a common hallmark of numerous human diseases, most of which involve cytosolic aggregates including Aβ (AD) and ⍺-synuclein (PD) in Alzheimer's disease and Parkinson's disease. However, it is also evident that protein aggregation can also occur in the lumen of the endoplasmic reticulum (ER) that leads to specific diseases due to loss of protein function or detrimental effects on the host cell, the former is inherited in a recessive manner where the latter are dominantly inherited. However, the mechanisms of protein aggregation, disaggregation and degradation in the ER are not well understood. Here we provide an overview of factors that cause protein aggregation in the ER and how the ER handles aggregated proteins. Protein aggregation in the ER can result from intrinsic properties of the protein (hydrophobic residues in the ER), oxidative stress or nutrient depletion. The ER has quality control mechanisms [chaperone functions, ER-associated protein degradation (ERAD) and autophagy] to ensure only correctly folded proteins exit the ER and enter the cis-Golgi compartment. Perturbation of protein folding in the ER activates the unfolded protein response (UPR) that evolved to increase ER protein folding capacity and efficiency and degrade misfolded proteins. Accumulation of misfolded proteins in the ER to a level that exceeds the ER-chaperone folding capacity is a major factor that exacerbates protein aggregation. The most significant ER resident protein that prevents protein aggregation in the ER is the heat shock protein 70 (HSP70) homologue, BiP/GRP78, which is a peptide-dependent ATPase that binds unfolded/misfolded proteins and releases them upon ATP binding. Since exogenous factors can also reduce protein misfolding and aggregation in the ER, such as chemical chaperones and antioxidants, these treatments have potential therapeutic benefit for ER protein aggregation-associated diseases.
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Affiliation(s)
- Juthakorn Poothong
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Insook Jang
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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Zhao XY, Yu TT, Liu S, Liu YJ, Liu JJ, Qin J. Effect of liraglutide on endoplasmic reticulum stress in the renal tissue of type 2 diabetic rats. World J Diabetes 2020; 11:611-621. [PMID: 33384768 PMCID: PMC7754169 DOI: 10.4239/wjd.v11.i12.611] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/28/2020] [Accepted: 10/21/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Liraglutide is a glucagon-like peptide 1 receptor agonist analog that has been found to have a therapeutic effect in diabetes. In addition to its ability to treat diabetes, liraglutide has beneficial effects on the cardiovascular system and kidney as well as other beneficial effects, but its specific mechanism is not clear. In this study, a rat model of type 2 diabetes was established by administration of a high-sugar, high-fat diet combined with low-dose streptozotocin (STZ) to observe the effect of liraglutide on the kidneys of type 2 diabetes rats and the possible underlying mechanisms.
AIM To explore whether liraglutide has a protective effect on type 2 diabetic rat kidneys and the underlying mechanisms.
METHODS Eight-week-old male Sprague-Dawley rats were randomly divided into a control group, model group, low-dose liraglutide group, and high-dose liraglutide group. Control rats were fed a standard diet, while model group and intervention group rats were fed high-sugar, high-fat feed for 1 mo and then intraperitoneally injected with 40 mg/kg STZ to induce type 2 diabetes. The low-dose and high-dose intervention groups received 100 µg/kg and 200 µg/kg liraglutide, respectively, once daily by subcutaneous injection. The control and model groups were given an equivalent volume of physiological saline for 8 wk. Pathological changes in renal tissues were observed by hematoxylin and eosin staining and periodic acid-Schiff staining, and GRP78 and caspase-12 expression was detected by Western blot and reverse transcription-polymerase chain reaction (RT-PCR).
RESULTS Western blot analysis showed that GRP78 and caspase-12 protein expression in kidney tissue was significantly higher in model rats than in normal rats and lower in the liraglutide-treated groups than in the model group, with a more significant decrease being observed in the high-dose group than in the low-dose group. RT-PCR showed that the mRNA expression of GRP78 and caspase-12 was higher in model rats than in control rats and lower in the liraglutide-treated groups than in the model group, with the high-dose group exhibiting a more significant decrease than the low-dose group.
CONCLUSION Liraglutide may delay the progression of diabetic nephropathy by reducing endoplasmic reticulum stress and protect the kidneys in a dose-dependent manner.
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Affiliation(s)
- Xuan-Ye Zhao
- Department of Endocrinology, Shanxi Provincial People's Hospital, Taiyuan 030012, Shanxi Province, China
| | - Ting-Ting Yu
- Department of Endocrinology, Shanxi Provincial People's Hospital, Taiyuan 030012, Shanxi Province, China
| | - Sheng Liu
- Department of Endocrinology, Shanxi Provincial People's Hospital, Taiyuan 030012, Shanxi Province, China
| | - Yao-Ji Liu
- Department of Endocrinology, Shanxi Provincial People's Hospital, Taiyuan 030012, Shanxi Province, China
| | - Jing-Jin Liu
- Department of Endocrinology, Shanxi Provincial People's Hospital, Taiyuan 030012, Shanxi Province, China
| | - Jie Qin
- Department of Endocrinology, Shanxi Provincial People's Hospital, Taiyuan 030012, Shanxi Province, China
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Wang H, Saint-Martin C, Xu J, Ding L, Wang R, Feng W, Liu M, Shu H, Fan Z, Haataja L, Arvan P, Bellanné-Chantelot C, Cui J, Huang Y. Biological behaviors of mutant proinsulin contribute to the phenotypic spectrum of diabetes associated with insulin gene mutations. Mol Cell Endocrinol 2020; 518:111025. [PMID: 32916194 PMCID: PMC7734662 DOI: 10.1016/j.mce.2020.111025] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 08/30/2020] [Accepted: 08/31/2020] [Indexed: 02/06/2023]
Abstract
Insulin gene mutation is the second most common cause of neonatal diabetes (NDM). It is also one of the genes involved in maturity-onset diabetes of the young (MODY). We aim to investigate molecular behaviors of different INS gene variants that may correlate with the clinical spectrum of diabetes phenotypes. In this study, we concentrated on two previously uncharacterized MODY-causing mutants, proinsulin-p.Gly44Arg [G(B20)R] and p.Pro52Leu [P(B28)L] (a novel mutant identified in one French family), and an NDM causing proinsulin-p.(Cys96Tyr) [C(A7)Y]. We find that these proinsulin mutants exhibit impaired oxidative folding in the endoplasmic reticulum (ER) with blocked ER export, ER stress, and apoptosis. Importantly, the proinsulin mutants formed abnormal intermolecular disulfide bonds that not only involved the mutant proinsulin, but also the co-expressed WT-proinsulin, forming misfolded disulfide-linked proinsulin complexes. This impaired the intracellular trafficking of WT-proinsulin and limited the production of bioactive mature insulin. Notably, although all three mutants presented with similar defects in folding, trafficking, and dominant negative behavior, the degrees of these defects appeared to be different. Specifically, compared to MODY mutants G(B20)R and P(B28)L that partially affected folding and trafficking of co-expressed WT-proinsulin, the NDM mutant C(A7)Y resulted in an almost complete blockade of the ER export of WT-proinsulin, decreasing insulin production, inducing more severe ER stress and apoptosis. We thus demonstrate that differences in cell biological behaviors among different proinsulin mutants correlate with the spectrum of diabetes phenotypes caused by the different INS gene mutations.
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Affiliation(s)
- Heting Wang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Cécile Saint-Martin
- Department of Genetics, Sorbonne University, Pitié-Salpêtrière Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Jialu Xu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Li Ding
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Ruodan Wang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Wenli Feng
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China; Tianjin Institute of Endocrinology, Tianjin, China
| | - Hua Shu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Zhenqian Fan
- Department of Endocrinology and Metabolism, The Second Hospital of Tianjin Medical University, Tianjin, China
| | - Leena Haataja
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Christine Bellanné-Chantelot
- Department of Genetics, Sorbonne University, Pitié-Salpêtrière Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France.
| | - Jingqiu Cui
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China.
| | - Yumeng Huang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China.
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