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Ma K, Dhawan S. Yo-Yo Dieting: Mixed Messages for β-Cell Plasticity. Diabetes 2022; 71:2253-2255. [PMID: 36265016 PMCID: PMC9630080 DOI: 10.2337/dbi22-0024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 07/25/2022] [Indexed: 01/25/2023]
Affiliation(s)
- Ke Ma
- Department of Diabetes Complications and Metabolism, Arthur Riggs Diabetes and Metabolism Research Institute, City of Hope, Duarte, CA
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute, City of Hope, Duarte, CA
| | - Sangeeta Dhawan
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute, City of Hope, Duarte, CA
- Department of Translational Research and Cellular Therapeutics, Arthur Riggs Diabetes and Metabolism Research Institute, City of Hope, Duarte, CA
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2
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Spaeth JM, Dhawan S. The Yin and Yang of Modulating β-Cell DNA Damage Response and Functional Mass. Diabetes 2022; 71:1614-1616. [PMID: 35881837 PMCID: PMC9490355 DOI: 10.2337/dbi22-0010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 05/01/2022] [Accepted: 05/04/2022] [Indexed: 11/13/2022]
Affiliation(s)
- Jason M. Spaeth
- Department of Biochemistry and Molecular Biology and Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN
- Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN
| | - Sangeeta Dhawan
- Department of Translational Research and Cellular Therapeutics, Arthur Riggs Diabetes and Metabolism Research Institute, City of Hope, Duarte, CA
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute, City of Hope, Duarte, CA
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3
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Marmentini C, Guimarães DSPSF, de Lima TI, Teófilo FBS, da Silva NS, Soares GM, Boschero AC, Kurauti MA. Rosiglitazone protects INS-1E cells from human islet amyloid polypeptide toxicity. Eur J Pharmacol 2022; 928:175122. [PMID: 35764131 DOI: 10.1016/j.ejphar.2022.175122] [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: 02/12/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 11/18/2022]
Abstract
Human islet amyloid polypeptide (hIAPP or amylin) is a hormone co-secreted with insulin by pancreatic β-cells, and is the main component of islet amyloid. Islet amyloid is found in the pancreas of patients with type 2 diabetes and may be involved in β-cell dysfunction and death, observed in this disease. Thus, counteracting islet amyloid toxicity represents a therapeutic approach to preserve β-cell mass and function. In this sense, thiazolidinediones (TZDs), as rosiglitazone, have shown protective effects against other harmful insults to β-cells. For this reason, we investigated whether rosiglitazone could protect β-cells from hIAPP-induced cell death and the underlying mechanisms mediating such effect. Here, we show that rosiglitazone improved the viability of hIAPP-exposed INS-1E cells. This benefit is not dependent on the insulin-degrading enzyme (IDE) since rosiglitazone did not modulate IDE protein content and activity. However, rosiglitazone inhibited hIAPP fibrillation and decreased hIAPP-induced expression of C/EBP homologous protein (CHOP) (CTL 100.0 ± 8.4; hIAPP 182.7 ± 19.1; hIAPP + RGZ 102.8 ± 9.5), activating transcription factor-4 (ATF4) (CTL 100.0 ± 3.1; hIAPP 234.9 ± 19.3; hIAPP + RGZ 129.6 ± 3.0) and phospho-eukaryotic initiation factor 2-alpha (p-eIF2α) (CTL 100.0 ± 31.1; hIAPP 234.1 ± 36.2; hIAPP + RGZ 150.4 ± 18.0). These findings suggest that TZDs treatment may be a promising approach to preserve β-cell mass and function by inhibiting islet amyloid formation and decreasing endoplasmic reticulum stress hIAPP-induced.
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Affiliation(s)
- Carine Marmentini
- Laboratory of Endocrine Pancreas and Metabolism, Obesity and Comorbidities Research Center (OCRC), University of Campinas (UNICAMP), Campinas, Sao Paulo, Brazil
| | - Dimitrius Santiago P S F Guimarães
- Laboratory of Endocrine Pancreas and Metabolism, Obesity and Comorbidities Research Center (OCRC), University of Campinas (UNICAMP), Campinas, Sao Paulo, Brazil
| | - Tanes I de Lima
- Laboratory of Endocrine Pancreas and Metabolism, Obesity and Comorbidities Research Center (OCRC), University of Campinas (UNICAMP), Campinas, Sao Paulo, Brazil
| | - Francisco Breno S Teófilo
- Electron Microscopy Laboratory, Institute of Biology, University of Campinas (UNICAMP), Campinas, Sao Paulo, Brazil
| | - Natália S da Silva
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, Sao Paulo, Brazil
| | - Gabriela M Soares
- Laboratory of Endocrine Pancreas and Metabolism, Obesity and Comorbidities Research Center (OCRC), University of Campinas (UNICAMP), Campinas, Sao Paulo, Brazil
| | - Antonio C Boschero
- Laboratory of Endocrine Pancreas and Metabolism, Obesity and Comorbidities Research Center (OCRC), University of Campinas (UNICAMP), Campinas, Sao Paulo, Brazil
| | - Mirian A Kurauti
- Department of Physiological Sciences, Biological Sciences Center, State University of Maringa (UEM), Maringa, Parana, Brazil.
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4
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Shang C, Lin H, Fang X, Wang Y, Jiang Z, Qu Y, Xiang M, Shen Z, Xin L, Lu Y, Gao J, Cui X. Beneficial effects of cinnamon and its extracts in the management of cardiovascular diseases and diabetes. Food Funct 2021; 12:12194-12220. [PMID: 34752593 DOI: 10.1039/d1fo01935j] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cardiovascular diseases (CVDs) and diabetes are the leading causes of death worldwide, which underlines the urgent necessity to develop new pharmacotherapies. Cinnamon has been an eminent component of spice and traditional Chinese medicine for thousands of years. Numerous lines of findings have elucidated that cinnamon has beneficial effects against CVDs in various ways, including endothelium protection, regulation of immune response, lowering blood lipids, antioxidative properties, anti-inflammatory properties, suppression of vascular smooth muscle cell (VSMC) growth and mobilization, repression of platelet activity and thrombosis and inhibition of angiogenesis. Furthermore, emerging evidence has established that cinnamon improves diabetes, a crucial risk factor for CVDs, by enhancing insulin sensitivity and insulin secretion; regulating the enzyme activity involved in glucose; regulating glucose metabolism in the liver, adipose tissue and muscle; ameliorating oxidative stress and inflammation to protect islet cells; and improving diabetes complications. In this review, we summarized the mechanisms by which cinnamon regulates CVDs and diabetes in order to provide a theoretical basis for the further clinical application of cinnamon.
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Affiliation(s)
- Chang Shang
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China. .,Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Hongchen Lin
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China. .,Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Xuqin Fang
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China. .,Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Yuling Wang
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China. .,Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Zhilin Jiang
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
| | - Yi Qu
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China. .,Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Mi Xiang
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
| | - Zihuan Shen
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China. .,Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Laiyun Xin
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China. .,First Clinical Medical School, Shandong University of Chinese Medicine, Shandong, 250355, China
| | - Yingdong Lu
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
| | - Jialiang Gao
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
| | - Xiangning Cui
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
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5
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Sepehri A, Nepal B, Lazaridis T. Distinct Modes of Action of IAPP Oligomers on Membranes. J Chem Inf Model 2021; 61:4645-4655. [PMID: 34499498 DOI: 10.1021/acs.jcim.1c00767] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Islet amyloid polypeptide (IAPP, also known as amylin) is a peptide hormone that is co-secreted with insulin by pancreatic β-cells and forms amyloid aggregates in type II diabetes. Various lines of evidence indicate that oligomers of this peptide may induce toxicity by disrupting or forming pores in cell membranes, but the structure of these pores is unknown. Here, we create models of pores for both helical and β-structured peptides using implicit membrane modeling and test their stability using multimicrosecond all-atom simulations. We find that the helical peptides behave similarly to antimicrobial peptides; they remain stably inserted in a highly tilted or partially unfolded configuration creating a narrow water channel. Parallel helix orientation creates a somewhat larger pore. An octameric β barrel of parallel β-hairpins is highly stable in the membrane, whereas the corresponding barrel made of antiparallel hairpins is not. We propose that certain experiments probe the helical pore state while others probe the β-structured pore state; this provides a possible explanation for lack of correlation that is sometimes observed between in vivo toxicity and in vitro liposome permeabilization experiments.
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Affiliation(s)
- Aliasghar Sepehri
- Department of Chemistry, City College of New York, New York, New York 10031, United States
| | - Binod Nepal
- Department of Chemistry, City College of New York, New York, New York 10031, United States
| | - Themis Lazaridis
- Department of Chemistry, City College of New York, New York, New York 10031, United States.,Graduate Programs in Chemistry, Biochemistry, and Physics, The Graduate Center, City University of New York, New York, New York, New York 10016, United States
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6
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Gray ALH, Antevska A, Link BA, Bogin B, Burke SJ, Dupuy SD, Collier JJ, Levine ZA, Karlstad MD, Do TD. α-CGRP disrupts amylin fibrillization and regulates insulin secretion: implications on diabetes and migraine. Chem Sci 2021; 12:5853-5864. [PMID: 34168810 PMCID: PMC8179678 DOI: 10.1039/d1sc01167g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 03/13/2021] [Indexed: 11/21/2022] Open
Abstract
Despite being relatively benign and not an indicative signature of toxicity, fibril formation and fibrillar structures continue to be key factors in assessing the structure-function relationship in protein aggregation diseases. The inability to capture molecular cross-talk among key players at the tissue level before fibril formation greatly accounts for the missing link toward the development of an efficacious therapeutic intervention for Type II diabetes mellitus (T2DM). We show that human α-calcitonin gene-related peptide (α-CGRP) remodeled amylin fibrillization. Furthermore, while CGRP and/or amylin monomers reduce the secretion of both mouse Ins1 and Ins2 proteins, CGRP oligomers have a reverse effect on Ins1. Genetically reduced Ins2, the orthologous version of human insulin, has been shown to enhance insulin sensitivity and extend the life-span in old female mice. Beyond the mechanistic insights, our data suggest that CGRP regulates insulin secretion and lowers the risk of T2DM. Our result rationalizes how migraine might be protective against T2DM. We envision the new paradigm of CGRP : amylin interactions as a pivotal aspect for T2DM diagnostics and therapeutics. Maintaining a low level of amylin while increasing the level of CGRP could become a viable approach toward T2DM prevention and treatment.
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Affiliation(s)
- Amber L H Gray
- Department of Chemistry, University of Tennessee Knoxville TN 37996 USA
| | | | - Benjamin A Link
- Department of Chemistry, University of Tennessee Knoxville TN 37996 USA
| | - Bryan Bogin
- Department of Pathology, Yale School of Medicine New Haven CT 06520 USA
- Department of Molecular Biophysics & Biochemistry, Yale University New Haven CT 0652 USA
| | - Susan J Burke
- Laboratory of Immunogenetics, Pennington Biomedical Research Center Baton Rouge LA 70808 USA
| | - Samuel D Dupuy
- Department of Surgery, Graduate School of Medicine, University of Tennessee Health Science Center Knoxville TN 37920 USA
| | - J Jason Collier
- Laboratory of Islet Biology and Inflammation, Pennington Biomedical Research Center Baton Rouge LA 70808 USA
| | - Zachary A Levine
- Department of Pathology, Yale School of Medicine New Haven CT 06520 USA
- Department of Molecular Biophysics & Biochemistry, Yale University New Haven CT 0652 USA
| | - Michael D Karlstad
- Department of Surgery, Graduate School of Medicine, University of Tennessee Health Science Center Knoxville TN 37920 USA
| | - Thanh D Do
- Department of Chemistry, University of Tennessee Knoxville TN 37996 USA
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7
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Abstract
Islet dysfunction is a hallmark of type 2 diabetes mellitus (T2DM). Compelling evidence suggests that accumulation of islet amyloid in the islets of Langerhans significantly contribute to β-cell dysfunction and diabetes. Emerging evidence implicates a role for cystic fibrosis transmembrane-conductance regulator in the regulation of insulin secretion from pancreatic islets. Impaired first-phase insulin responses and glucose homeostasis have also been reported in cystic fibrosis patients. The transforming growth factor-β protein superfamily is central regulators of pancreatic cell function, and has a key role in pancreas development and pancreatic disease, including diabetes and islet dysfunction. It is also becoming clear that islet inflammation plays a key role in the development of islet dysfunction. Inflammatory changes, including accumulation of macrophages, have been documented in type 2 diabetic islets. Islet dysfunction leads to hyperglycemia and ultimately the development of diabetes. In this review, we describe these risk factors and their associations with islet dysfunction.
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Affiliation(s)
- Fei Hu
- Diabetes Research Center, School of Medicine, Ningbo University, Ningbo, China
| | - Xiaohui Qiu
- Department of nephrology, Ningbo Medical Center Li Huili Eastern Hospital Affiliated to Ningbo University
| | - Shizhong Bu
- Diabetes Research Center, School of Medicine, Ningbo University, Ningbo, China
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8
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Gerst F, Wagner R, Oquendo MB, Siegel-Axel D, Fritsche A, Heni M, Staiger H, Häring HU, Ullrich S. What role do fat cells play in pancreatic tissue? Mol Metab 2019; 25:1-10. [PMID: 31113756 PMCID: PMC6600604 DOI: 10.1016/j.molmet.2019.05.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 04/10/2019] [Accepted: 05/01/2019] [Indexed: 02/07/2023] Open
Abstract
Background It is now generally accepted that obesity is a major risk factor for type 2 diabetes mellitus (T2DM). Hepatic steatosis in particular, as well as visceral and ectopic fat accumulation within tissues, is associated with the development of the disease. We recently presented the first study on isolated human pancreatic adipocytes and their interaction with islets [Gerst, F., Wagner, R., Kaiser, G., Panse, M., Heni, M., Machann, J., et al., 2017. Metabolic crosstalk between fatty pancreas and fatty liver: effects on local inflammation and insulin secretion. Diabetologia 60(11):2240–2251.]. The results indicate that the function of adipocytes depends on the overall metabolic status in humans which, in turn, differentially affects islet hormone release. Scope of Review This review summarizes former and recent studies on factors derived from adipocytes and their effects on insulin-secreting β-cells, with particular emphasis on the human pancreas. The adipocyte secretome is discussed with a special focus on its influence on insulin secretion, β-cell survival and apoptotic β-cell death. Major Conclusions Human pancreatic adipocytes store lipids and release adipokines, metabolites, and pro-inflammatory molecules in response to the overall metabolic, humoral, and neuronal status. The differentially regulated adipocyte secretome impacts on endocrine function, i.e., insulin secretion, β-cell survival and death which interferes with glycemic control. This review attempts to explain why the extent of pancreatic steatosis is associated with reduced insulin secretion in some studies but not in others.
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Affiliation(s)
- Felicia Gerst
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Robert Wagner
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Morgana Barroso Oquendo
- German Center for Diabetes Research (DZD), Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Dorothea Siegel-Axel
- German Center for Diabetes Research (DZD), Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Andreas Fritsche
- German Center for Diabetes Research (DZD), Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Martin Heni
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Harald Staiger
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Institute of Pharmaceutical Sciences, Department of Pharmacy and Biochemistry, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Hans-Ulrich Häring
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Susanne Ullrich
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany.
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9
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Zhang Y, Warnock GL, Ao Z, Park YJ, Safikhan N, Ghahary A, Marzban L. Amyloid formation reduces protein kinase B phosphorylation in primary islet β-cells which is improved by blocking IL-1β signaling. PLoS One 2018; 13:e0193184. [PMID: 29474443 PMCID: PMC5825069 DOI: 10.1371/journal.pone.0193184] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 02/02/2018] [Indexed: 12/31/2022] Open
Abstract
Amyloid formation in the pancreatic islets due to aggregation of human islet amyloid polypeptide (hIAPP) contributes to reduced β-cell mass and function in type 2 diabetes (T2D) and islet transplantation. Protein kinase B (PKB) signaling plays a key role in the regulation of β-cell survival, function and proliferation. In this study, we used human and hIAPP-expressing transgenic mouse islets in culture as two ex vivo models of human islet amyloid formation to: 1. Investigate the effects of amyloid formation on PKB phosphorylation in primary islet β-cells; 2. Test if inhibition of amyloid formation and/or interleukin-1β (IL-1β) signaling in islets can restore the changes in β-cell phospho-PKB levels mediated by amyloid formation. Human and hIAPP-expressing mouse islets were cultured in elevated glucose with an amyloid inhibitor (Congo red) or embedded within collagen matrix to prevent amyloid formation. To block the IL-1β signaling, human islets were treated with an IL-1 receptor antagonist (anakinra) or a glucagon-like peptide-1 agonist (exenatide). β-cell phospho-PKB levels, proliferation, apoptosis, islet IL-1β levels and amyloid formation were assessed. Amyloid formation in both cultured human and hIAPP-expressing mouse islets reduced β-cell phospho-PKB levels and increased islet IL-1β levels, both of which were restored by prevention of amyloid formation either by the amyloid inhibitor or embedding islets in collagen matrix, resulting in improved β-cell survival. Furthermore, inhibition of IL-1β signaling by treatment with anakinra or exenatide increased β-cell phospho-PKB levels, enhanced proliferation and reduced apoptosis in amyloid forming human islets during 7-day culture. These data suggest that amyloid formation leads to reduced PKB phosphorylation in β-cells which is associated with elevated islet IL-1β levels. Inhibitors of amyloid or amyloid-induced IL-1β production may provide a new approach to restore phospho-PKB levels thereby enhance β-cell survival and proliferation in conditions associated with islet amyloid formation such as T2D and clinical islet transplantation.
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Affiliation(s)
- Yun Zhang
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Garth L. Warnock
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Ziliang Ao
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Yoo Jin Park
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Nooshin Safikhan
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Aziz Ghahary
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Lucy Marzban
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- * E-mail:
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10
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Mukherjee A, Morales-Scheihing D, Salvadores N, Moreno-Gonzalez I, Gonzalez C, Taylor-Presse K, Mendez N, Shahnawaz M, Gaber AO, Sabek OM, Fraga DW, Soto C. Induction of IAPP amyloid deposition and associated diabetic abnormalities by a prion-like mechanism. J Exp Med 2017; 214:2591-2610. [PMID: 28765400 PMCID: PMC5584114 DOI: 10.1084/jem.20161134] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 03/24/2017] [Accepted: 06/19/2017] [Indexed: 12/12/2022] Open
Abstract
In this article, Mukherjee et al. show that the pathologic and clinical alterations of type 2 diabetes can be induced in vitro and in vivo by prion-like transmission of IAPP misfolded aggregates, supporting an important role for IAPP aggregation in the disease. Although a large proportion of patients with type 2 diabetes (T2D) accumulate misfolded aggregates composed of the islet amyloid polypeptide (IAPP), its role in the disease is unknown. Here, we show that pancreatic IAPP aggregates can promote the misfolding and aggregation of endogenous IAPP in islet cultures obtained from transgenic mouse or healthy human pancreas. Islet homogenates immunodepleted with anti-IAPP–specific antibodies were not able to induce IAPP aggregation. Importantly, intraperitoneal inoculation of pancreatic homogenates containing IAPP aggregates into transgenic mice expressing human IAPP dramatically accelerates IAPP amyloid deposition, which was accompanied by clinical abnormalities typical of T2D, including hyperglycemia, impaired glucose tolerance, and a substantial reduction on β cell number and mass. Finally, induction of IAPP deposition and diabetic abnormalities were also induced in vivo by administration of IAPP aggregates prepared in vitro using pure, synthetic IAPP. Our findings suggest that some of the pathologic and clinical alterations of T2D might be transmissible through a similar mechanism by which prions propagate in prion diseases.
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Affiliation(s)
- Abhisek Mukherjee
- Mitchell Center for Alzheimer's Disease, Department of Neurology, John P. and Kathrine G. McGovern Medical School, University of Texas Medical School at Houston, Houston, TX
| | - Diego Morales-Scheihing
- Mitchell Center for Alzheimer's Disease, Department of Neurology, John P. and Kathrine G. McGovern Medical School, University of Texas Medical School at Houston, Houston, TX.,Facultad de Medicina, Universidad de los Andes, Las Condes, Santiago, Chile
| | - Natalia Salvadores
- Mitchell Center for Alzheimer's Disease, Department of Neurology, John P. and Kathrine G. McGovern Medical School, University of Texas Medical School at Houston, Houston, TX.,Center for Integrative Biology, Universidad Mayor, Santiago, Chile
| | - Ines Moreno-Gonzalez
- Mitchell Center for Alzheimer's Disease, Department of Neurology, John P. and Kathrine G. McGovern Medical School, University of Texas Medical School at Houston, Houston, TX
| | - Cesar Gonzalez
- Mitchell Center for Alzheimer's Disease, Department of Neurology, John P. and Kathrine G. McGovern Medical School, University of Texas Medical School at Houston, Houston, TX
| | - Kathleen Taylor-Presse
- Mitchell Center for Alzheimer's Disease, Department of Neurology, John P. and Kathrine G. McGovern Medical School, University of Texas Medical School at Houston, Houston, TX
| | - Nicolas Mendez
- Mitchell Center for Alzheimer's Disease, Department of Neurology, John P. and Kathrine G. McGovern Medical School, University of Texas Medical School at Houston, Houston, TX
| | - Mohammad Shahnawaz
- Mitchell Center for Alzheimer's Disease, Department of Neurology, John P. and Kathrine G. McGovern Medical School, University of Texas Medical School at Houston, Houston, TX
| | - A Osama Gaber
- Department of Surgery, Houston Methodist Hospital, Houston, TX
| | - Omaima M Sabek
- Department of Surgery, Houston Methodist Hospital, Houston, TX
| | - Daniel W Fraga
- Department of Surgery, Houston Methodist Hospital, Houston, TX
| | - Claudio Soto
- Mitchell Center for Alzheimer's Disease, Department of Neurology, John P. and Kathrine G. McGovern Medical School, University of Texas Medical School at Houston, Houston, TX .,Facultad de Medicina, Universidad de los Andes, Las Condes, Santiago, Chile
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11
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Md Moin AS, Cory M, Ong A, Choi J, Dhawan S, Butler PC, Butler AE. Pancreatic Nonhormone Expressing Endocrine Cells in Children With Type 1 Diabetes. J Endocr Soc 2017; 1:385-395. [PMID: 28782056 PMCID: PMC5542010 DOI: 10.1210/js.2017-00081] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
It has been proposed that the deficit in β-cell mass in type 1 diabetes (T1D) may be due, in part, to β-cell degranulation to chromogranin-positive hormone-negative (CPHN) cells. The frequency and distribution of pancreatic CPHN cells were investigated in 19 children with T1D compared with 14 nondiabetic (ND) children. We further evaluated these cells for replication and expression of endocrine lineage markers Nkx6.1 and Nkx2.2, and compared these frequencies with those previously reported in CPHN cells in adults with T1D. In contrast to adults’ cells, pancreatic CPHN cells were comparably abundant (percentage of endocrine cells ± standard error of the mean, 1.4 ± 0.2 vs 1.0 ± 0.2 in patients with T1D vs ND subjects, respectively; P = not significant) and comparably distributed in children with T1D vs ND donors. Replication of CPHN cells was detected but unchanged in children with T1D vs ND children, as was the percentage of CPHN cells expressing Nkx6.1 or NKx2.2. In children with T1D, the frequency of pancreatic CPHN cells was not increased, and this differed from adults with T1D.
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Affiliation(s)
- Abu Saleh Md Moin
- Larry L. Hillblom Islet Research Center, University of California Los Angeles, David Geffen School of Medicine, Los Angeles, California 90095
| | - Megan Cory
- Larry L. Hillblom Islet Research Center, University of California Los Angeles, David Geffen School of Medicine, Los Angeles, California 90095
| | - Allison Ong
- Larry L. Hillblom Islet Research Center, University of California Los Angeles, David Geffen School of Medicine, Los Angeles, California 90095
| | - Jennifer Choi
- Larry L. Hillblom Islet Research Center, University of California Los Angeles, David Geffen School of Medicine, Los Angeles, California 90095
| | - Sangeeta Dhawan
- Larry L. Hillblom Islet Research Center, University of California Los Angeles, David Geffen School of Medicine, Los Angeles, California 90095
| | - Peter C Butler
- Larry L. Hillblom Islet Research Center, University of California Los Angeles, David Geffen School of Medicine, Los Angeles, California 90095
| | - Alexandra E Butler
- Larry L. Hillblom Islet Research Center, University of California Los Angeles, David Geffen School of Medicine, Los Angeles, California 90095
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12
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Tomita T. Apoptosis in pancreatic β-islet cells in Type 2 diabetes. Bosn J Basic Med Sci 2016; 16:162-79. [PMID: 27209071 DOI: 10.17305/bjbms.2016.919] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/16/2016] [Accepted: 01/20/2016] [Indexed: 12/25/2022] Open
Abstract
Apoptosis plays important roles in the pathophysiology of Type 2 diabetes mellitus (T2DM). The etiology of T2DM is multifactorial, including obesity-associated insulin resistance, defective insulin secretion, and loss of β-cell mass through β-cell apoptosis. β-cell apoptosis is mediated through a milliard of caspase family cascade machinery in T2DM. The glucose-induced insulin secretion is the principle pathophysiology of diabetes and insufficient insulin secretion results in chronic hyperglycemia, diabetes. Recently, hyperglycemia-induced β-cell apoptosis has been extensively studied on the balance of pro-apoptotic Bcl-2 proteins (Bad, Bid, Bik, and Bax) and anti-apoptotic Bcl family (Bcl-2 and Bcl-xL) toward apoptosis in vitro isolated islets and insulinoma cell culture. Apoptosis can only occur when the concentration of pro-apoptotic Bcl-2 exceeds that of anti-apoptotic proteins at the mitochondrial membrane of the intrinsic pathway. A bulk of recent research on hyperglycemia-induced apoptosis on β-cells unveiled complex details on glucose toxicity on β-cells in molecular levels coupled with cell membrane potential by adenosine triphosphate generation through K+ channel closure, opening Ca2+ channel and plasma membrane depolarization. Furthermore, animal models using knockout mice will shed light on the basic understanding of the pathophysiology of diabetes as a glucose metabolic disease complex, on the balance of anti-apoptotic Bcl family and pro-apoptotic genes. The cumulative knowledge will provide a better understanding of glucose metabolism at a molecular level and will lead to eventual prevention and therapeutic application for T2DM with improving medications.
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Watve M, Bodas A, Diwekar M. Altered autonomic inputs as a cause of pancreatic β-cell amyloid. Med Hypotheses 2013; 82:49-53. [PMID: 24321738 DOI: 10.1016/j.mehy.2013.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 11/03/2013] [Indexed: 01/09/2023]
Abstract
A partial loss of β-cell mass and β-cell dysfunction in Type 2 Diabetes Mellitus (T2DM) is associated with amyloid deposition but whether it is causal or consequential is debated. Although the in vitro polymerization of amylin has been studied in detail, the exact trigger for the mechanism in vivo has not been identified. One suggestion is that an increased load on β-cells results in inefficient handling of proteins leading to misfolding and aggregation, but this hypothesis is faced with certain paradoxes. We suggest an alternative mechanism based on the assumption that polymerization is a spontaneous process. The concentration of the polypeptide in β-cell granules is shown to be sufficient to allow polymerization. However if the rate of turnover in normal cells is greater than the rate of polymerization, amyloid deposition will not be observed. If this is true, it follows that amyloid deposition could be a result of increased retention time of amylin in the β-cell granules. In T2D, the sympathetic inputs are known to increase which could result in suppression of the secretion process. The increase in the retention time due to this suppression can allow polymerization. In addition to this in a prediabetic state parasympathetic stimulation increases β-cell proliferation. This reduces the insulin demand per cell thereby increasing the mean retention time. Thus a combination of contrasting actions of sympathetic and parasympathetic systems could lead to increase in the amyloid deposition. We suggest testable predictions of the alternative hypotheses and the lines of research needed to test them.
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Affiliation(s)
- Milind Watve
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
| | - Arushi Bodas
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Manawa Diwekar
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
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14
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Abstract
Over the past two decades, insulin resistance has been considered essential to the aetiology of type 2 diabetes mellitus (T2DM). However, insulin resistance does not lead to T2DM unless it is accompanied by pancreatic β-cell dysfunction, because healthy β cells can compensate for insulin resistance by increasing in number and functional output. Furthermore, β-cell mass is decreased in patients with diabetes mellitus, suggesting a primary role for β-cell dysfunction in the pathogenesis of T2DM. The dysfunction of β cells can develop through various mechanisms, including oxidative, endoplasmic reticulum or hypoxic stress, as well as via induction of cytokines; these processes lead to apoptosis, uncontrolled autophagy and failure to proliferate. Transdifferentiation between β cells and α cells occurs under certain pathological conditions, and emerging evidence suggests that β-cell dedifferentiation or transdifferentiation might account for the reduction in β-cell mass observed in patients with severe T2DM. FOXO1, a key transcription factor in insulin signalling, is implicated in these mechanisms. This Review discusses advances in our understanding of the contribution of FOXO1 signalling to the development of β-cell failure in T2DM.
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Affiliation(s)
- Tadahiro Kitamura
- Metabolic Signal Research Centre, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15, Showa-machi, Maebashi, Gunma 371-8512, Japan.
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15
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Structural similarities and differences between amyloidogenic and non-amyloidogenic islet amyloid polypeptide (IAPP) sequences and implications for the dual physiological and pathological activities of these peptides. PLoS Comput Biol 2013; 9:e1003211. [PMID: 24009497 PMCID: PMC3757079 DOI: 10.1371/journal.pcbi.1003211] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 07/20/2013] [Indexed: 12/22/2022] Open
Abstract
IAPP, a 37 amino-acid peptide hormone belonging to the calcitonin family, is an intrinsically disordered protein that is coexpressed and cosecreted along with insulin by pancreatic islet β-cells in response to meals. IAPP plays a physiological role in glucose regulation; however, in certain species, IAPP can aggregate and this process is linked to β-cell death and Type II Diabetes. Using replica exchange molecular dynamics with extensive sampling (16 replicas per sequence and 600 ns per replica), we investigate the structure of the monomeric state of two species of aggregating peptides (human and cat IAPP) and two species of non-aggregating peptides (pig and rat IAPP). Our simulations reveal that the pig and rat conformations are very similar, and consist of helix-coil and helix-hairpin conformations. The aggregating sequences, on the other hand, populate the same helix-coil and helix-hairpin conformations as the non-aggregating sequence, but, in addition, populate a hairpin structure. Our exhaustive simulations, coupled with available peptide-activity data, leads us to a structure-activity relationship (SAR) in which we propose that the functional role of IAPP is carried out by the helix-coil conformation, a structure common to both aggregating and non-aggregating species. The pathological role of this peptide may have multiple origins, including the interaction of the helical elements with membranes. Nonetheless, our simulations suggest that the hairpin structure, only observed in the aggregating species, might be linked to the pathological role of this peptide, either as a direct precursor to amyloid fibrils, or as part of a cylindrin type of toxic oligomer. We further propose that the helix-hairpin fold is also a possible aggregation prone conformation that would lead normally non-aggregating variants of IAPP to form fibrils under conditions where an external perturbation is applied. The SAR relationship is used to suggest the rational design of therapeutics for treating diabetes. IAPP, a 37 amino-acid peptide hormone belonging to the calcitonin family, is an intrinsically disordered peptide produced along with insulin by pancreatic islet β-cells in response to meals. In its functional form, IAPP acts as a synergic partner of insulin to reduce blood glucose. IAPP can, however, also play a pathological role, contributing to Type II diabetes (T2D). Knowledge of the structural nature of the physiological and pathological forms of IAPP will facilitate the rational design of novel drugs for therapeutic treatment of T2D. However, because IAPP does not fold to a single structure, but rather co-exists between multiple functional (and toxic) structures, it is extremely challenging for experimental methods to gain detailed structural information. Using a computational approach, we were able to obtain detailed structures of four IAPP variants and propose a novel structural hypothesis for the two opposing roles of this peptide.
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Götz J, Lim YA, Eckert A. Lessons from two prevalent amyloidoses-what amylin and Aβ have in common. Front Aging Neurosci 2013; 5:38. [PMID: 23964237 PMCID: PMC3737661 DOI: 10.3389/fnagi.2013.00038] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 07/16/2013] [Indexed: 11/23/2022] Open
Abstract
The amyloidogenic peptide Aβ plays a key role in Alzheimer's disease (AD) forming insoluble aggregates in the brain. The peptide shares its amyloidogenic properties with amylin that forms aggregates in the pancreas of patients with Type 2 Diabetes mellitus (T2DM). While epidemiological studies establish a link between these two diseases, it is becoming increasingly clear that they also share biochemical features suggesting common pathogenic mechanisms. We discuss commonalities as to how Aβ and amylin deregulate the cellular proteome, how they impair mitochondrial functions, to which receptors they bind, aspects of their clearance and how therapeutic strategies exploit the commonalities between Aβ and amylin. We conclude that research into these two molecules is mutually beneficial for the treatment of AD and T2DM.
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Affiliation(s)
- Jürgen Götz
- Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland Brisbane, QLD, Australia ; Sydney Medical School, Brain and Mind Research Institute, University of Sydney Sydney, Australia
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17
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Paradis R, Lazar N, Antinozzi P, Perbal B, Buteau J. Nov/Ccn3, a novel transcriptional target of FoxO1, impairs pancreatic β-cell function. PLoS One 2013; 8:e64957. [PMID: 23705021 PMCID: PMC3660386 DOI: 10.1371/journal.pone.0064957] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 04/19/2013] [Indexed: 11/19/2022] Open
Abstract
Type 2 diabetes is characterized by both insulin resistance and progressive deterioration of β-cell function. The forkhead transcription factor FoxO1 is a prominent mediator of insulin signaling in β-cells. We reasoned that identification of FoxO1 target genes in β-cells could reveal mechanisms linking β-cell dysfunction to insulin resistance. In this study, we report the characterization of Nov/Ccn3 as a novel transcriptional target of FoxO1 in pancreatic β-cells. FoxO1 binds to an evolutionarily conserved response element in the Ccn3 promoter to regulate its expression. Accordingly, CCN3 levels are elevated in pancreatic islets of mice with overexpression of a constitutively active form of FoxO1 or insulin resistance. Our functional studies reveal that CCN3 impairs β-cell proliferation concomitantly with a reduction in cAMP levels. Moreover, CCN3 decreases glucose oxidation, which translates into inhibition of glucose-stimulated Ca2+ entry and insulin secretion. Our results identify CCN3, a novel transcriptional target of FoxO1 in pancreatic β-cells, as a potential target for therapeutic intervention in the treatment of diabetes.
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Affiliation(s)
- Renée Paradis
- Department of Medicine, Université Laval, Quebec, Canada
| | - Noureddine Lazar
- Unité de formation et de recherche en Biochimie, Université de Paris 7-D Diderot, Paris, France
| | - Peter Antinozzi
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Bernard Perbal
- Unité de formation et de recherche en Biochimie, Université de Paris 7-D Diderot, Paris, France
| | - Jean Buteau
- Department of Medicine, Université Laval, Quebec, Canada
- * E-mail:
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Jiao L, Zhang X, Huang L, Gong H, Cheng B, Sun Y, Li Y, Liu Q, Zheng L, Huang K. Proanthocyanidins are the major anti-diabetic components of cinnamon water extract. Food Chem Toxicol 2013; 56:398-405. [PMID: 23499750 DOI: 10.1016/j.fct.2013.02.049] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 02/24/2013] [Accepted: 02/26/2013] [Indexed: 10/27/2022]
Abstract
Cinnamon consumption has been found to associate with the attenuation of diabetes mellitus. The misfolding of human islet amyloid polypeptide (hIAPP) is regarded as a causative factor of type 2 diabetes mellitus (T2DM). Here, we investigated whether cinnamon has any beneficial effect on the toxic aggregation of hIAPP. We found that cinnamon water extract (CWE) inhibited the amyloid formation of hIAPP in a dose-dependent manner, and identified proanthocyanidins as the major anti-amyloidogenic compounds of CWE. Proanthocyanidins affected the secondary structures of hIAPP and delayed the structural transition from unstructured coils to β-sheet-rich structures. Further studies showed that proanthocyanidins not only inhibited the formation of hIAPP oligomers, but also significantly attenuated the membrane damaging and cytotoxic effects caused by the hIAPP aggregation. Together, these results suggest a possible way by which cinnamon shows beneficial effects on T2DM, and indicate a potential pharmacological usage of proanthocyanidins as an anti-diabetic drug candidate.
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Affiliation(s)
- Lihua Jiao
- Tongji School of Pharmacy, Huazhong University of Science and Technology, Wuhan 430030, PR China
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Marchetti P, Bugliani M, Boggi U, Masini M, Marselli L. The pancreatic beta cells in human type 2 diabetes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 771:288-309. [PMID: 23393686 DOI: 10.1007/978-1-4614-5441-0_22] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Bell-cell (beta-cell) impairment is central to the development and progression of human diabetes, as a result of the combined effects of genetic and acquired factors. Reduced islet number and/or reduced beta cells amount in the pancreas of individuals with Type 2 diabetes have been consistently reported. This is mainly due to increased beta cell death, not adequately compensated for by regeneration. In addition, several quantitative and/or qualitative defects of insulin secretion have been observed in Type 2 diabetes, both in vivo and ex vivo with isolated islets. All this is associated with modifications of islet cell gene and protein expression. With the identification of several susceptible Type 2 diabetes loci, the role of genotype in affecting beta-cell function and survival has been addressed in a few studies and the relationships between genotype and beta-cell phenotype investigated. Among acquired factors, the importance of metabolic insults (in particular glucotoxicity and lipotoxicity) in the natural history of beta-cell damage has been widely underlined. Continuous improvements in our knowledge of the beta cells in human Type 2 diabetes will lead to more targeted and effective strategies for the prevention and treatment of the disease.
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Affiliation(s)
- Piero Marchetti
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy.
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20
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Magzoub M, Miranker AD. Concentration-dependent transitions govern the subcellular localization of islet amyloid polypeptide. FASEB J 2011; 26:1228-38. [PMID: 22183778 DOI: 10.1096/fj.11-194613] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Islet amyloid polypeptide (IAPP) is a peptide hormone cosecreted with insulin by pancreatic β-cells. In type II diabetes, IAPP aggregates in a process that is associated with β-cell dysfunction and loss of β-cell mass. The relationship between IAPP's conformational landscape and its capacity to mediate cell death remains poorly understood. We have addressed these unknowns by comparing the cytotoxic effects of sequence variants with differing α-helical and amyloid propensities. IAPP was previously shown to oligomerize cooperatively on binding to lipid bilayers. Here, comparable transitions are evident in cell culture and are associated with a change in subcellular localization to the mitochondria under toxic conditions. Notably, we find that this toxic gain of function maps to IAPP's capacity to adopt aggregated membrane-bound α-helical, and not β-sheet, states. Our findings suggest that upon α-helical mediated oligomerization, IAPP acquires cell-penetrating peptide (CPP) properties, facilitating access to the mitochondrial compartment, resulting in its dysfunction.
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Affiliation(s)
- Mazin Magzoub
- Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Ave., New Haven, CT 06520-8114, USA
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21
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Folli F, Okada T, Perego C, Gunton J, Liew CW, Akiyama M, D'Amico A, La Rosa S, Placidi C, Lupi R, Marchetti P, Sesti G, Hellerstein M, Perego L, Kulkarni RN. Altered insulin receptor signalling and β-cell cycle dynamics in type 2 diabetes mellitus. PLoS One 2011; 6:e28050. [PMID: 22140505 PMCID: PMC3227614 DOI: 10.1371/journal.pone.0028050] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 10/31/2011] [Indexed: 12/31/2022] Open
Abstract
Insulin resistance, reduced β-cell mass, and hyperglucagonemia are consistent features in type 2 diabetes mellitus (T2DM). We used pancreas and islets from humans with T2DM to examine the regulation of insulin signaling and cell-cycle control of islet cells. We observed reduced β-cell mass and increased α-cell mass in the Type 2 diabetic pancreas. Confocal microscopy, real-time PCR and western blotting analyses revealed increased expression of PCNA and down-regulation of p27-Kip1 and altered expression of insulin receptors, insulin receptor substrate-2 and phosphorylated BAD. To investigate the mechanisms underlying these findings, we examined a mouse model of insulin resistance in β-cells – which also exhibits reduced β-cell mass, the β-cell-specific insulin receptor knockout (βIRKO). Freshly isolated islets and β-cell lines derived from βIRKO mice exhibited poor cell-cycle progression, nuclear restriction of FoxO1 and reduced expression of cell-cycle proteins favoring growth arrest. Re-expression of insulin receptors in βIRKO β-cells reversed the defects and promoted cell cycle progression and proliferation implying a role for insulin-signaling in β-cell growth. These data provide evidence that human β- and α-cells can enter the cell-cycle, but proliferation of β-cells in T2DM fails due to G1-to-S phase arrest secondary to defective insulin signaling. Activation of insulin signaling, FoxO1 and proteins in β-cell-cycle progression are attractive therapeutic targets to enhance β-cell regeneration in the treatment of T2DM.
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Affiliation(s)
- Franco Folli
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, United States of America
- * E-mail: (RNK); (FF)
| | - Terumasa Okada
- Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Carla Perego
- Department of Molecular Science Applied to Biosystems, Università degli Studi di Milano, Milan, Italy
| | - Jenny Gunton
- Garvan Institute of Medical Research, Sydney, Australia
| | - Chong Wee Liew
- Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Masaru Akiyama
- Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Anna D'Amico
- Department of Molecular Science Applied to Biosystems, Università degli Studi di Milano, Milan, Italy
| | - Stefano La Rosa
- Department of Pathology, Ospedale di Circolo and Department of Human Morphology, University of Insubria, Varese, Italy
| | - Claudia Placidi
- Department of Pathology, Ospedale di Circolo and Department of Human Morphology, University of Insubria, Varese, Italy
| | - Roberto Lupi
- Division of Endocrinology, University of Pisa, Pisa, Italy
| | | | - Giorgio Sesti
- Department of Clinical and Experimental Medicine, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | - Marc Hellerstein
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California, United States of America
| | - Lucia Perego
- Department of Molecular Science Applied to Biosystems, Università degli Studi di Milano, Milan, Italy
| | - Rohit N. Kulkarni
- Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (RNK); (FF)
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Lang F, Ullrich S, Gulbins E. Ceramide formation as a target in beta-cell survival and function. Expert Opin Ther Targets 2011; 15:1061-71. [PMID: 21635197 DOI: 10.1517/14728222.2011.588209] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Ceramide may be synthesized de novo or generated by sphingomyelinase-dependent hydrolysis of sphingomyelin. AREAS COVERED The role of ceramide, ceramide-sensitive signaling and ion channels in β-cell apoptosis, lipotoxicity and amyloid-induced β-cell death. EXPERT OPINION Ceramide participates in β-cell dysfunction and apoptosis after exposure to TNFα, IL-1β and IFN-γ, excessive amyloid and islet amyloid polypeptide or non-esterified fatty acids (lipotoxicity). Knockout of sphingomyelin synthase 1, which converts ceramide to sphingomyelin, leads to impairment of insulin secretion. Increased ceramidase activity or pharmacological inhibition of ceramide synthetase, inhibits β-cell apoptosis. Ceramide contributes to endoplasmatic reticulum (ER) stress, decreased mitochondrial membrane potential in insulin-secreting cells and mitochondrial release of cytochrome c into the cytosol, which are all triggers of apoptotic cell death. Ceramide-dependent signaling involves activation of extracellularly regulated kinases 1 and 2 (ERK1/2), downregulation of Period (Per)-aryl hydrocarbon receptor nuclear translocator (Arnt)-single-minded (Sim) kinase (PASK), activation of okadaic-acid-sensitive protein phosphatase 2A (PP2A) and stimulation of NADPH-oxidase with generation of superoxides and lipid peroxides. Ceramide reduces the activity of voltage gated potassium (Kv)-channels in insulin-secreting cells. The role of ceramide in β-cell survival and function may be therapeutically relevant, because ceramide formation can be suppressed by pharmacological inhibition of ceramide synthetase and/or sphingomyelinase.
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Affiliation(s)
- Florian Lang
- University of Tübingen, Institute of Physiology, Germany.
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23
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Gillard P, Mathieu C. Immune and cell therapy in type 1 diabetes: too little too late? Expert Opin Biol Ther 2011; 11:609-21. [PMID: 21406028 DOI: 10.1517/14712598.2011.560568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Type 1 diabetes is caused by autoimmune destruction of insulin-producing β-cells. Intensive insulin therapy protects most patients against chronic complications of diabetes, but exposes patients to acute complications like hypoglycaemia and impacts on quality of life. Therapies that aim at protecting or restoring endogenous insulin secretion might help in decreasing the risk of severe hypoglycemia and long-term complications. AREAS COVERED This article reviews the literature of clinical immunotherapy and β-cell transplantation in treatment of type 1 diabetes with specific focus on the effect on preserving and restoring β-cell mass. EXPERT OPINION Several studies in recent-onset type 1 diabetic patients have provided proof of principle that immunotherapy can preserve residual functional β-cell mass. The observation that this strategy is most effective early in the disease process opens possibilities of arresting and even preventing type 1 diabetes. In patients with too few or no surviving β-cells, current protocols of β-cell transplantation can restore functional β-cell mass up to 25% of levels in healthy controls. Unfortunately, both strategies to date are followed by progressive decline of endogenous insulin secretion later on. Strategies to restore functional β-cell mass to a higher level and to restore immune tolerance are thus needed.
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Affiliation(s)
- Pieter Gillard
- University Hospital Leuven, Department of Experimental Medicine and Endocrinology, KULeuven, Herestraat 49, B-3000 Leuven, Belgium
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CHOP deletion does not impact the development of diabetes but suppresses the early production of insulin autoantibody in the NOD mouse. Apoptosis 2011; 16:438-48. [DOI: 10.1007/s10495-011-0576-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Ionescu-Tirgoviste C, Despa F. Biophysical alteration of the secretory track in β-cells due to molecular overcrowding: the relevance for diabetes. Integr Biol (Camb) 2010; 3:173-9. [PMID: 21180710 DOI: 10.1039/c0ib00029a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Recent data demonstrate that accumulation of misfolded proteins within the early part of the secretory track of β-cells causes impaired insulin synthesis and development of diabetes. The molecular mechanism of this cellular dysfunction remains largely unknown. Using basic molecular principles and computer simulations, we suggested recently that hyperglycemic conditions can generate substantial molecular crowding effects in the secretory track of β-cells leading to significant alterations of the insulin biosynthesis capabilities. Here, we review the major molecular mechanisms that may be implicated in the alteration of insulin synthesis in susceptible β-cells. Steric repulsions and volume exclusion in the endoplasmic reticulum (ER) increase the propensity of misfolding of proinsulin (the precursor molecule of insulin). In addition, similar forces might act in the next secretory compartments (Golgi and vesicles) leading to (i) altered packaging of proinsulin in vesicles (ii) entrapment of proinsulin convertases and/or restricted accessibility for these convertases to the cleavage sites on the surface of the proinsulin and (iii) depressed kinetic rate of the transformation of the native proinsulin in active insulin and C-peptide. These concepts are expressed in simple mathematical terms relating the kinetic coefficient of proinsulin to insulin conversion to the levels of proinsulin misfolding and hyperglycemic stress. The present approach is useful for understanding molecular phenomena associated with the pathogenesis of diabetes. It also offers practical means for predicting the state of pancreatic β-cells from measurements of the insulin to proinsulin ratio in the blood. This is of immediate clinical relevance and may improve the diagnosis of diabetes.
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Ritzel RA, Jayasinghe S, Hansen JB, Sturis J, Langen R, Butler PC. Beta-cell selective K(ATP)-channel activation protects beta-cells and human islets from human islet amyloid polypeptide induced toxicity. ACTA ACUST UNITED AC 2010; 165:158-62. [PMID: 20619299 DOI: 10.1016/j.regpep.2010.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 06/07/2010] [Accepted: 06/28/2010] [Indexed: 01/09/2023]
Abstract
BACKGROUND AND AIMS In type 2 diabetes mellitus (T2DM) chronic beta-cell stimulation and oligomers of aggregating human islet amyloid polypeptide (h-IAPP) cause beta-cell dysfunction and induce beta-cell apoptosis. Therefore we asked whether beta-cell rest prevents h-IAPP induced beta-cell apoptosis. MATERIALS AND METHODS We induced beta-cell rest with a beta-cell selective K(ATP)-channel opener (K(ATP)CO) in RIN cells and human islets exposed to h-IAPP versus r-IAPP. Apoptosis was quantified by time-lapse video microscopy (TLVM) in RIN cells and TUNEL staining in human islets. Whole islets were also studied with TLVM over 48h to examine islet architecture. RESULTS In RIN cells and human islets h-IAPP induced apoptosis (p<0.001 h-IAPP versus r-IAPP). Concomitant incubation with K(ATP)CO inhibited apoptosis (p<0.001). K(ATP)CO also reduced h-IAPP induced expansion of whole islets (disintegration of islet architecture) by ~70% (p<0.05). Thioflavin-binding assays show that K(ATP)CO does not directly inhibit amyloid formation. CONCLUSIONS Opening of K(ATP)-channels reduces beta-cell vulnerability to apoptosis induced by h-IAPP oligomers. This effect is not due to a direct interaction of K(ATP)CO with h-IAPP, but might be mediated through hyperpolarization of the beta-cell membrane induced by opening of K(ATP)-channels. Induction of beta-cell rest with beta-cell selective K(ATP)-channel openers may provide a strategy to protect beta-cells from h-IAPP induced apoptosis and to prevent beta-cell deficiency in T2DM.
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Affiliation(s)
- Robert A Ritzel
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-7073, USA.
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Rieck S, Kaestner KH. Expansion of beta-cell mass in response to pregnancy. Trends Endocrinol Metab 2010; 21:151-8. [PMID: 20015659 PMCID: PMC3627215 DOI: 10.1016/j.tem.2009.11.001] [Citation(s) in RCA: 251] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Revised: 11/06/2009] [Accepted: 11/09/2009] [Indexed: 12/22/2022]
Abstract
Inadequate beta-cell mass can lead to insulin insufficiency and diabetes. During times of prolonged metabolic demand for insulin, the endocrine pancreas can respond by increasing beta-cell mass, both by increasing cell size and by changing the balance between beta-cell proliferation and apoptosis. In this paper, we review recent advances in our understanding of the mechanisms that control the adaptive expansion of beta-cell mass, focusing on the islet's response to pregnancy, a physiological state of insulin resistance. Functional characterization of factors controlling both beta-cell proliferation and survival might not only lead to the development of successful therapeutic strategies to enhance the response of the beta-cell to increased metabolic loads, but also improve islet transplantation regimens.
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Affiliation(s)
- Sebastian Rieck
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Bedrood S, Jayasinghe S, Sieburth D, Chen M, Erbel S, Butler PC, Langen R, Ritzel RA. Annexin A5 directly interacts with amyloidogenic proteins and reduces their toxicity. Biochemistry 2009; 48:10568-76. [PMID: 19810772 DOI: 10.1021/bi900608m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Protein misfolding is a central mechanism for the development of neurodegenerative diseases and type 2 diabetes mellitus. The accumulation of misfolded alpha-synuclein protein inclusions in the Lewy bodies of Parkinson's disease is thought to play a key role in pathogenesis and disease progression. Similarly, the misfolding of the beta-cell hormone human islet amyloid polypeptide (h-IAPP) into toxic oligomers plays a central role in the induction of beta-cell apoptosis in the context of type 2 diabetes. In this study, we show that annexin A5 plays a role in interacting with and reducing the toxicity of the amyloidogenic proteins, h-IAPP and alpha-synuclein. We find that annexin A5 is coexpressed in human beta-cells and that exogenous annexin A5 reduces the level of h-IAPP-induced apoptosis in human islets by approximately 50% and in rodent beta-cells by approximately 90%. Experiments with transgenic expression of alpha-synuclein in Caenorhabditis elegans show that annexin A5 reduces alpha-synuclein inclusions in vivo. Using thioflavin T fluorescence, electron microscopy, and electron paramagnetic resonance, we provide evidence that substoichiometric amounts of annexin A5 inhibit h-IAPP and alpha-synuclein misfolding and fibril formation. We conclude that annexin A5 might act as a molecular safeguard against the formation of toxic amyloid aggregates.
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Affiliation(s)
- Sahar Bedrood
- Department of Biochemistry and Molecular Biology, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA
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Manesso E, Toffolo GM, Saisho Y, Butler AE, Matveyenko AV, Cobelli C, Butler PC. Dynamics of beta-cell turnover: evidence for beta-cell turnover and regeneration from sources of beta-cells other than beta-cell replication in the HIP rat. Am J Physiol Endocrinol Metab 2009; 297:E323-30. [PMID: 19470833 PMCID: PMC2724115 DOI: 10.1152/ajpendo.00284.2009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Type 2 diabetes is characterized by hyperglycemia, a deficit in beta-cells, increased beta-cell apoptosis, and islet amyloid derived from islet amyloid polypeptide (IAPP). These characteristics are recapitulated in the human IAPP transgenic (HIP) rat. We developed a mathematical model to quantify beta-cell turnover and applied it to nondiabetic wild type (WT) vs. HIP rats from age 2 days to 10 mo to establish 1) whether beta-cell formation is derived exclusively from beta-cell replication, or whether other sources of beta-cells (OSB) are present, and 2) to what extent, if any, there is attempted beta-cell regeneration in the HIP rat and if this is through beta-cell replication or OSB. We conclude that formation and maintenance of adult beta-cells depends largely ( approximately 80%) on formation of beta-cells independent from beta-cell duplication. Moreover, this source adaptively increases in the HIP rat, implying attempted beta-cell regeneration that substantially slows loss of beta-cell mass.
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Affiliation(s)
- Erica Manesso
- 1Department of Information Engineering, University of Padua, Padua, Italy
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Soong R, Brender JR, Macdonald PM, Ramamoorthy A. Association of highly compact type II diabetes related islet amyloid polypeptide intermediate species at physiological temperature revealed by diffusion NMR spectroscopy. J Am Chem Soc 2009; 131:7079-85. [PMID: 19405534 DOI: 10.1021/ja900285z] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Self-association of human islet amyloid polypeptide (hIAPP) is correlated with the development of type II diabetes by the disruption of cellular homeostasis in islet cells through the formation of membrane-active oligomers. The toxic species of hIAPP responsible for membrane damage has not been identified. In this study, we show by pulsed field gradient NMR spectroscopy that the monomeric form of the toxic, amyloidogenic human variant of IAPP (hIAPP) adopts a temperature dependent compact folded conformation that is absent in both the nontoxic and nonamyloidogenic rat variant of IAPP and absent in hIAPP at low temperatures, suggesting this compact form of monomeric hIAPP may be linked to its later aggregation and cytotoxicity. In addition to the monomeric form of hIAPP, a large oligomeric species greater than 100 nm in diameter is also present but does not trigger the nucleation-dependent aggregation of IAPP at 4 degrees C, indicating the large oligomeric species may be an off-pathway intermediate that has been predicted by kinetic models of IAPP fiber formation. Furthermore, analysis of the polydispersity of the calculated diffusion values indicates small oligomeric species of hIAPP are absent in agreement with a recent ultracentrifugation study. The absence of small oligomeric species in solution suggests the formation of small, well-defined ion channels by hIAPP may proceed by aggregation of monomeric IAPP on the membrane, rather than by the insertion of preformed structured oligomers from the solution state as has been proposed for other amyloidogenic proteins.
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Affiliation(s)
- Ronald Soong
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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31
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Sphingomyelinase dependent apoptosis following treatment of pancreatic beta-cells with amyloid peptides Aß1-42 or IAPP. Apoptosis 2009; 14:878-89. [DOI: 10.1007/s10495-009-0364-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Matveyenko AV, Gurlo T, Daval M, Butler AE, Butler PC. Successful versus failed adaptation to high-fat diet-induced insulin resistance: the role of IAPP-induced beta-cell endoplasmic reticulum stress. Diabetes 2009; 58:906-16. [PMID: 19151199 PMCID: PMC2661593 DOI: 10.2337/db08-1464] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Obesity is a known risk factor for type 2 diabetes. However, most obese individuals do not develop diabetes because they adapt to insulin resistance by increasing beta-cell mass and insulin secretion. Islet pathology in type 2 diabetes is characterized by beta-cell loss, islet amyloid derived from islet amyloid polypeptide (IAPP), and increased beta-cell apoptosis characterized by endoplasmic reticulum (ER) stress. We hypothesized that IAPP-induced ER stress distinguishes successful versus unsuccessful islet adaptation to insulin resistance. RESEARCH DESIGN AND METHODS To address this, we fed wild-type (WT) and human IAPP transgenic (HIP) rats either 10 weeks of regular chow or a high-fat diet and prospectively examined the relations among beta-cell mass and turnover, beta-cell ER stress, insulin secretion, and insulin sensitivity. RESULTS A high-fat diet led to comparable insulin resistance in WT and HIP rats. WT rats compensated with increased insulin secretion and beta-cell mass. In HIP rats, in contrast, neither beta-cell function nor mass compensated for the increased insulin demand, leading to diabetes. The failure to increase beta-cell mass in HIP rats was the result of ER stress-induced beta-cell apoptosis that increased in proportion to diet-induced insulin resistance. CONCLUSIONS IAPP-induced ER stress distinguishes the successful versus unsuccessful islet adaptation to a high-fat diet in rats. These studies are consistent with the hypothesis that IAPP oligomers contribute to increased beta-cell apoptosis and beta-cell failure in humans with type 2 diabetes.
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Affiliation(s)
- Aleksey V Matveyenko
- Larry Hillblom Islet Research Center, David Geffen School of Medicine at the University of California, Los Angeles, Los Angeles, California, USA.
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Brender JR, Hartman K, Reid KR, Kennedy RT, Ramamoorthy A. A single mutation in the nonamyloidogenic region of islet amyloid polypeptide greatly reduces toxicity. Biochemistry 2009; 47:12680-8. [PMID: 18989933 DOI: 10.1021/bi801427c] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Islet amyloid polypeptide (IAPP or amylin) is a 37-residue peptide secreted with insulin by beta-cells in the islets of Langerhans. The aggregation of the peptide into either amyloid fibers or small soluble oligomers has been implicated in the death of beta-cells during type 2 diabetes through disruption of the cellular membrane. The actual form of the peptide responsible for beta-cell death has been a subject of controversy. Previous research has indicated that the N-terminal region of the peptide (residues 1-19) is primarily responsible for the membrane-disrupting effect of the hIAPP peptide and induces membrane disruption to a similar extent as the full-length peptide without forming amyloid fibers when bound to the membrane. The rat version of the peptide, which is both noncytotoxic and nonamyloidogenic, differs from the human peptide by only one amino acid residue: Arg18 in the rat version while His18 in the human version. To elucidate the effect of this difference, we have measured in this study the effects of the rat and human versions of IAPP(1-19) on islet cells and model membranes. Fluorescence microscopy shows a rapid increase in intracellular calcium levels of islet cells after the addition of hIAPP(1-19), indicating disruption of the cellular membrane, while the rat version of the IAPP(1-19) peptide is significantly less effective. Circular dichroism experiments and dye leakage assays on model liposomes show that rIAPP(1-19) is deficient in binding to and disrupting lipid membranes at low but not at high peptide to lipid ratios, indicating that the ability of rIAPP(1-19) to form small aggregates necessary for membrane binding and disruption is significantly less than hIAPP(1-19). At pH 6.0, where H18 is likely to be protonated, hIAPP(1-19) resembles rIAPP(1-19) in its ability to cause membrane disruption. Differential scanning calorimetry suggests a different mode of binding to the membrane for rIAPP(1-19) compared to hIAPP(1-19). Human IAPP(1-19) has a minimal effect on the phase transition of lipid vesicles, suggesting a membrane orientation of the peptide in which the mobility of the acyl chains of the membrane is relatively unaffected. Rat IAPP(1-19), however, has a strong effect on the phase transition of lipid vesicles at low concentrations, suggesting that the peptide does not easily insert into the membrane after binding to the surface. Our results indicate that the modulation of the peptide orientation in the membrane by His18 plays a key role in the toxicity of nonamyloidogenic forms of hIAPP.
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Affiliation(s)
- Jeffrey R Brender
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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Schulthess FT, Katz S, Ardestani A, Kawahira H, Georgia S, Bosco D, Bhushan A, Maedler K. Deletion of the mitochondrial flavoprotein apoptosis inducing factor (AIF) induces beta-cell apoptosis and impairs beta-cell mass. PLoS One 2009; 4:e4394. [PMID: 19197367 PMCID: PMC2632884 DOI: 10.1371/journal.pone.0004394] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Accepted: 12/15/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Apoptosis is a hallmark of beta-cell death in both type 1 and type 2 diabetes mellitus. Understanding how apoptosis contributes to beta-cell turnover may lead to strategies to prevent progression of diabetes. A key mediator of apoptosis, mitochondrial function, and cell survival is apoptosis inducing factor (AIF). In the present study, we investigated the role of AIF on beta-cell mass and survival using the Harlequin (Hq) mutant mice, which are hypomorphic for AIF. METHODOLOGY/PRINCIPAL FINDINGS Immunohistochemical evaluation of pancreata from Hq mutant mice displayed much smaller islets compared to wild-type mice (WT). Analysis of beta-cell mass in these mice revealed a greater than 4-fold reduction in beta-cell mass together with an 8-fold increase in beta-cell apoptosis. Analysis of cell cycle dynamics, using BrdU pulse as a marker for cells in S-phase, did not detect significant differences in the frequency of beta-cells in S-phase. In contrast, double staining for phosphorylated Histone H3 and insulin showed a 3-fold increase in beta-cells in the G2 phase in Hq mutant mice, but no differences in M-phase compared to WT mice. This suggests that the beta-cells from Hq mutant mice are arrested in the G2 phase and are unlikely to complete the cell cycle. beta-cells from Hq mutant mice display increased sensitivity to hydrogen peroxide-induced apoptosis, which was confirmed in human islets in which AIF was depleted by siRNA. AIF deficiency had no effect on glucose stimulated insulin secretion, but the impaired effect of hydrogen peroxide on beta-cell function was potentiated. CONCLUSIONS/SIGNIFICANCE Our results indicate that AIF is essential for maintaining beta-cell mass and for oxidative stress response. A decrease in the oxidative phosphorylation capacity may counteract the development of diabetes, despite its deleterious effects on beta-cell survival.
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Affiliation(s)
- Fabienne T. Schulthess
- Centre for Biomolecular Interactions, University of Bremen, Bremen, Germany
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Sophie Katz
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Amin Ardestani
- Centre for Biomolecular Interactions, University of Bremen, Bremen, Germany
| | - Hiroshi Kawahira
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Senta Georgia
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Domenico Bosco
- Cell Isolation and Transplantation Center, Department of Surgery, University of Geneva School of Medicine, Genèva, Switzerland
| | - Anil Bhushan
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Kathrin Maedler
- Centre for Biomolecular Interactions, University of Bremen, Bremen, Germany
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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Schulthess FT, Paroni F, Sauter NS, Shu L, Ribaux P, Haataja L, Strieter RM, Oberholzer J, King CC, Maedler K. CXCL10 impairs beta cell function and viability in diabetes through TLR4 signaling. Cell Metab 2009; 9:125-39. [PMID: 19187771 DOI: 10.1016/j.cmet.2009.01.003] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 11/05/2008] [Accepted: 01/14/2009] [Indexed: 12/20/2022]
Abstract
In type 1 and type 2 diabetes (T1/T2DM), beta cell destruction by apoptosis results in decreased beta cell mass and progression of the disease. In this study, we found that the interferon gamma-inducible protein 10 plays an important role in triggering beta cell destruction. Islets isolated from patients with T2DM secreted CXCL10 and contained 33.5-fold more CXCL10 mRNA than islets from control patients. Pancreatic sections from obese nondiabetic individuals and patients with T2DM and T1DM expressed CXCL10 in beta cells. Treatment of human islets with CXCL10 decreased beta cell viability, impaired insulin secretion, and decreased insulin mRNA. CXCL10 induced sustained activation of Akt, JNK, and cleavage of p21-activated protein kinase 2 (PAK-2), switching Akt signals from proliferation to apoptosis. These effects were not mediated by the commonly known CXCL10 receptor CXCR3 but through TLR4. Our data suggest CXCL10 as a binding partner for TLR4 and as a signal toward beta cell failure in diabetes.
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Affiliation(s)
- Fabienne T Schulthess
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
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Saisho Y, Manesso E, Gurlo T, Huang CJ, Toffolo GM, Cobelli C, Butler PC. Development of factors to convert frequency to rate for beta-cell replication and apoptosis quantified by time-lapse video microscopy and immunohistochemistry. Am J Physiol Endocrinol Metab 2009; 296:E89-96. [PMID: 18940937 PMCID: PMC4043232 DOI: 10.1152/ajpendo.90697.2008] [Citation(s) in RCA: 10] [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] [Indexed: 01/09/2023]
Abstract
An obstacle to development of methods to quantify beta-cell turnover from pancreas tissue is the lack of conversion factors for the frequency of beta-cell replication or apoptosis detected by immunohistochemistry to rates of replication or apoptosis. We addressed this obstacle in islets from 1-mo-old rats by quantifying the relationship between the rate of beta-cell replication observed directly by time-lapse video microscopy (TLVM) and the frequency of beta-cell replication in the same islets detected by immunohistochemistry using antibodies against Ki67 and insulin in the same islets fixed immediately after TLVM. Similarly, we quantified the rate of beta-cell apoptosis by TLVM and then the frequency of apoptosis in the same islets using TdT-mediated dUTP nick-end labeling and insulin. Conversion factors were developed by regression analysis. The conversion factor from Ki67 labeling frequency (%) to actual replication rate (%events/h) is 0.025 +/- 0.003 h(-1). The conversion factor from TdT-mediated dUTP nick-end labeling frequency (%) to actual apoptosis rate (%events/h) is 0.41 +/- 0.05 h(-1). These conversion factors will permit development of models to evaluate beta-cell turnover in fixed pancreas tissue.
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Affiliation(s)
- Yoshifumi Saisho
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 900 Weyburn Place #A, Los Angeles, CA 90024-2852, USA
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Udayasankar J, Kodama K, Hull RL, Zraika S, Aston-Mourney K, Subramanian SL, Tong J, Faulenbach MV, Vidal J, Kahn SE. Amyloid formation results in recurrence of hyperglycaemia following transplantation of human IAPP transgenic mouse islets. Diabetologia 2009; 52:145-53. [PMID: 19002432 PMCID: PMC4950742 DOI: 10.1007/s00125-008-1185-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Accepted: 09/26/2008] [Indexed: 10/21/2022]
Abstract
AIMS/HYPOTHESIS Islet transplantation is a potential cure for diabetes; however, rates of graft failure remain high. The aim of the present study was to determine whether amyloid deposition is associated with reduced beta cell volume in islet grafts and the recurrence of hyperglycaemia following islet transplantation. METHODS We transplanted a streptozotocin-induced mouse model of diabetes with 100 islets from human IAPP (which encodes islet amyloid polypeptide) transgenic mice that have the propensity to form islet amyloid (n = 8-12) or from non-transgenic mice that do not develop amyloid (n = 6-10) in sets of studies that lasted 1 or 6 weeks. RESULTS Plasma glucose levels before and for 1 week after transplantation were similar in mice that received transgenic or non-transgenic islets, and at that time amyloid was detected in all transgenic grafts and, as expected, in none of the non-transgenic grafts. However, over the 6 weeks following transplantation, plasma glucose levels increased in transgenic but remained stable in non-transgenic islet graft recipients (p < 0.05). At 6 weeks, amyloid was present in 92% of the transgenic grafts and in none of the non-transgenic grafts. Beta cell volume was reduced by 30% (p < 0.05), beta cell apoptosis was twofold higher (p < 0.05), and beta cell replication was reduced by 50% (p < 0.001) in transgenic vs non-transgenic grafts. In summary, amyloid deposition in islet grafts occurs prior to the recurrence of hyperglycaemia and its accumulation over time is associated with beta cell loss. CONCLUSIONS/INTERPRETATION Islet amyloid formation may explain, in part, the non-immune loss of beta cells and recurrence of hyperglycaemia following clinical islet transplantation.
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Affiliation(s)
- J Udayasankar
- VA Puget Sound Health Care System 151, Seattle, WA 98108, USA
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Affiliation(s)
- Susan Bonner-Weir
- Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts, USA.
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Sordi V, Bertuzzi F, Piemonti L. Diabetes mellitus: an opportunity for therapy with stem cells? Regen Med 2008; 3:377-97. [PMID: 18462060 DOI: 10.2217/17460751.3.3.377] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In both Type 1 and 2 diabetes, insufficient numbers of insulin-producing beta-cells are a major cause of defective control of blood glucose and its complications. Restoration of damaged beta-cells by endocrine pancreas regeneration would be an ideal therapeutic option. The possibility of generating insulin-secreting cells with adult pancreatic stem or progenitor cells has been investigated extensively. The conversion of differentiated cells such as hepatocytes into beta-cells is being attempted using molecular insights into the transcriptional make-up of beta-cells. Additionally, the enhanced proliferation of beta-cells in vivo or in vitro is being pursued as a strategy for regenerative medicine for diabetes. Advances have also been made in directing the differentiation of embryonic stem cells into beta-cells. Although progress is encouraging, major gaps in our understanding of developmental biology of the pancreas and adult beta-cell dynamics remain to be bridged before a therapeutic application is made possible.
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Affiliation(s)
- Valeria Sordi
- Laboratory of Experimental Surgery, San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
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Human but not rat amylin shares neurotoxic properties with Aβ42 in long-term hippocampal and cortical cultures. FEBS Lett 2008; 582:2188-94. [DOI: 10.1016/j.febslet.2008.05.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2008] [Revised: 04/22/2008] [Accepted: 05/05/2008] [Indexed: 11/17/2022]
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Haataja L, Gurlo T, Huang CJ, Butler PC. Islet amyloid in type 2 diabetes, and the toxic oligomer hypothesis. Endocr Rev 2008; 29:303-16. [PMID: 18314421 PMCID: PMC2528855 DOI: 10.1210/er.2007-0037] [Citation(s) in RCA: 469] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Type 2 diabetes (T2DM) is characterized by insulin resistance, defective insulin secretion, loss of beta-cell mass with increased beta-cell apoptosis and islet amyloid. The islet amyloid is derived from islet amyloid polypeptide (IAPP, amylin), a protein coexpressed and cosecreted with insulin by pancreatic beta-cells. In common with other amyloidogenic proteins, IAPP has the propensity to form membrane permeant toxic oligomers. Accumulating evidence suggests that these toxic oligomers, rather than the extracellular amyloid form of these proteins, are responsible for loss of neurons in neurodegenerative diseases. In this review we discuss emerging evidence to suggest that formation of intracellular IAPP oligomers may contribute to beta-cell loss in T2DM. The accumulated evidence permits the amyloid hypothesis originally developed for neurodegenerative diseases to be reformulated as the toxic oligomer hypothesis. However, as in neurodegenerative diseases, it remains unclear exactly why amyloidogenic proteins form oligomers in vivo, what their exact structure is, and to what extent these oligomers play a primary or secondary role in the cytotoxicity in what are now often called unfolded protein diseases.
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Affiliation(s)
- Leena Haataja
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 900 Weyburn Place #A, Los Angeles, California 90024-2852, USA
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Apostolidou M, Jayasinghe SA, Langen R. Structure of alpha-helical membrane-bound human islet amyloid polypeptide and its implications for membrane-mediated misfolding. J Biol Chem 2008; 283:17205-10. [PMID: 18442979 DOI: 10.1074/jbc.m801383200] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human islet amyloid polypeptide (hIAPP) misfolding is thought to play an important role in the pathogenesis of type II diabetes mellitus. It has recently been shown that membranes can catalyze the misfolding of hIAPP via an alpha-helical intermediate of unknown structure. To better understand the mechanism of membrane-mediated misfolding, we used site-directed spin labeling and EPR spectroscopy to generate a three-dimensional structural model of this membrane-bound form. We find that hIAPP forms a single alpha-helix encompassing residues 9-22. The helix is flanked by N- and C-terminal regions that do not take up a clearly detectable secondary structure and are less ordered. Residues 21 and 22 are located in a transitional region between the alpha-helical structure and C terminus and exhibit significant mobility. The alpha-helical structure presented here has important implications for membrane-mediated aggregation. Anchoring hIAPP to the membrane not only increases the local concentration but also reduces the encounter between peptides to essentially a two-dimensional process. It is significant to note that the alpha-helical membrane-bound form leaves much of an important amyloidogenic region of hIAPP (residues 20-29) exposed for misfolding. Misfolding of this and other regions is likely further aided by the low dielectric environment near the membrane that is known to promote secondary structure formation. Based upon these considerations, a structural model for membrane-mediated aggregation is discussed.
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Affiliation(s)
- Melania Apostolidou
- Department of Biochemistry and Molecular Biology, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA
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Marzo N, Ortega S, Stratmann T, García A, Ríos M, Giménez A, Gomis R, Mora C. Cyclin-dependent kinase 4 hyperactivity promotes autoreactivity in the immune system but protects pancreatic cell mass from autoimmune destruction in the nonobese diabetic mouse model. THE JOURNAL OF IMMUNOLOGY 2008; 180:1189-98. [PMID: 18178859 DOI: 10.4049/jimmunol.180.2.1189] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cyclin-dependent kinase 4 (Cdk4) plays a central role in perinatal pancreatic beta cell replication, thus becoming a potential target for therapeutics in autoimmune diabetes. Its hyperactive form, Cdk4R24C, causes beta cell hyperplasia without promoting hypoglycemia in a nonautoimmune-prone mouse strain. In this study, we explore whether beta cell hyperproliferation induced by the Cdk4R24C mutation balances the autoimmune attack against beta cells inherent to the NOD genetic background. To this end, we backcrossed the Cdk4R24C knockin mice, which have the Cdk4 gene replaced by the Cdk4R24C mutated form, onto the NOD genetic background. In this study, we show that NOD/Cdk4R24C knockin mice exhibit exacerbated diabetes and insulitis, and that this exacerbated diabetic phenotype is solely due to the hyperactivity of the NOD/Cdk4R24C immune repertoire. Thus, NOD/Cdk4R24C splenocytes confer exacerbated diabetes when adoptively transferred into NOD/SCID recipients, compared with NOD/wild-type (WT) donor splenocytes. Accordingly, NOD/Cdk4R24C splenocytes show increased basal proliferation and higher activation markers expression compared with NOD/WT splenocytes. However, to eliminate the effect of the Cdk4R24C mutation specifically in the lymphocyte compartment, we introduced this mutation into NOD/SCID mice. NOD/SCID/Cdk4R24C knockin mice develop beta cell hyperplasia spontaneously. Furthermore, NOD/SCID/Cdk4R24C knockin females that have been adoptively transferred with NOD/WT splenocytes are more resistant to autoimmunity than NOD/SCID WT female. Thus, the Cdk4R24C mutation opens two avenues in the NOD model: when expressed specifically in beta cells, it provides a new potential strategy for beta cell regeneration in autoimmune diabetes, but its expression in the immune repertoire exacerbates autoimmunity.
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Affiliation(s)
- Nuria Marzo
- Institut d'Investigacions Biomèdiques August Pi i Sunyer and University of Barcelona, Barcelona, Spain
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Marchetti P, Dotta F, Lauro D, Purrello F. An overview of pancreatic beta-cell defects in human type 2 diabetes: Implications for treatment. ACTA ACUST UNITED AC 2008; 146:4-11. [PMID: 17889380 DOI: 10.1016/j.regpep.2007.08.017] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2007] [Revised: 08/07/2007] [Accepted: 08/09/2007] [Indexed: 12/12/2022]
Abstract
Type 2 diabetes is the most common form of diabetes in humans. It results from a combination of factors that impair beta-cell function and tissue insulin sensitivity. However, growing evidence is showing that the beta-cell is central to the development and progression of this form of diabetes. Reduced islet and/or insulin-containing cell mass or volume in Type 2 diabetes has been reported by several authors. Furthermore, studies with isolated Type 2 diabetic islets have consistently shown both quantitative and qualitative defects of glucose-stimulated insulin secretion. The impact of genotype in affecting beta-cell function and survival is a very fast growing field or research, and several gene polymorphisms have been associated with this form of diabetes. Among acquired factors, glucotoxicity, lipotoxicity and altered IAPP processing are likely to play an important role. Interestingly, however, pharmacological intervention can improve several defects of Type 2 diabetes islet cells in vitro, suggesting that progression of the disease might not be relentless.
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Affiliation(s)
- Piero Marchetti
- Department of Endocrinology and Metabolism, Metabolic Unit, University of Pisa, Pisa, Italy.
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Huang CJ, Haataja L, Gurlo T, Butler AE, Wu X, Soeller WC, Butler PC. Induction of endoplasmic reticulum stress-induced beta-cell apoptosis and accumulation of polyubiquitinated proteins by human islet amyloid polypeptide. Am J Physiol Endocrinol Metab 2007; 293:E1656-62. [PMID: 17911343 DOI: 10.1152/ajpendo.00318.2007] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The islet in type 2 diabetes is characterized by an approximately 60% beta-cell deficit, increased beta-cell apoptosis, and islet amyloid derived from islet amyloid polypeptide (IAPP). Human IAPP (hIAPP) but not rodent IAPP (rIAPP) forms toxic oligomers and amyloid fibrils in an aqueous environment. We previously reported that overexpression of hIAPP in transgenic rats triggered endoplasmic reticulum (ER) stress-induced apoptosis in beta-cells. In the present study, we sought to establish whether the cytotoxic effects of hIAPP depend on its propensity to oligomerize, rather than as a consequence of protein overexpression. To accomplish this, we established a novel homozygous mouse model overexpressing rIAPP at a comparable expression rate and, on the same background, as a homozygous transgenic hIAPP mouse model previously reported to develop diabetes associated with beta-cell loss. We report that by 10 wk of age hIAPP mice develop diabetes with a deficit in beta-cell mass due to increased beta-cell apoptosis. The rIAPP transgenic mice counterparts do not develop diabetes or have decreased beta-cell mass. Both rIAPP and hIAPP transgenic mice have increased expression of BiP, but only hIAPP transgenic mice have elevated ER stress markers (X-box-binding protein-1, nuclear localized CCAAT/enhancer binding-protein homologous protein, active caspase-12, and accumulation of ubiquitinated proteins). These findings indicate that the beta-cell toxic effects of hIAPP depend on the propensity of IAPP to aggregate, but not on the consequence of protein overexpression.
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Affiliation(s)
- Chang-Jiang Huang
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 900 Weyburn Pl. #A, Los Angeles, CA 90024, USA
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The replication of beta cells in normal physiology, in disease and for therapy. ACTA ACUST UNITED AC 2007; 3:758-68. [PMID: 17955017 DOI: 10.1038/ncpendmet0647] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Accepted: 09/03/2007] [Indexed: 02/06/2023]
Abstract
Replication of beta cells is an important source of beta-cell expansion in early childhood. The recent linkage of type 2 diabetes with several transcription factors involved in cell cycle regulation implies that growth of the beta-cell mass in early childhood might be an important determinant of risk for type 2 diabetes. Under some circumstances, including obesity and pregnancy, the beta-cell mass is adaptively increased in adult humans. The mechanisms by which this adaptive growth occurs and the relative contributions of beta-cell replication or of mechanisms independent of beta-cell replication are unknown. Also, although there is interest in the potential for beta-cell regeneration as a therapeutic approach in both type 1 and 2 diabetes, little is yet known about the potential sources of new beta cells in adult humans. In common with other cell types, replicating beta cells have an increased vulnerability to apoptosis, which is likely to limit the therapeutic value of inducing beta-cell replication in the proapoptotic environment of type 1 and 2 diabetes unless applied in conjunction with a strategy to suppress increased apoptosis.
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Cecchi C, Pensalfini A, Stefani M, Baglioni S, Fiorillo C, Cappadona S, Caporale R, Nosi D, Ruggiero M, Liguri G. Replicating neuroblastoma cells in different cell cycle phases display different vulnerability to amyloid toxicity. J Mol Med (Berl) 2007; 86:197-209. [PMID: 17885746 DOI: 10.1007/s00109-007-0265-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Revised: 08/29/2007] [Accepted: 09/03/2007] [Indexed: 01/03/2023]
Abstract
A key role of mitotic activation in neuronal cell death in early stages of Alzheimer's disease (AD) has been suggested. Apparently, terminally differentiated neurons are precluded from mitotic division, yet some phenotypic markers of cell cycling are present in AD-vulnerable brain areas. In this paper, we investigated whether dividing human neuroblastoma cells are preferentially vulnerable to amyloid aggregate toxicity in some specific cell cycle stage(s). Our data indicate that Abeta1-40/42 aggregates added to the cell culture media bind to the plasma membrane and are internalized faster in the S than in the G2/M and G1 cells possibly as a result of a lower content in membrane cholesterol in the former. Earlier and sharper increases in reactive oxygen species production triggered a membrane oxidative injury and a significant impairment of antioxidant capacity, eventually culminating with apoptotic activation in S and, to a lesser extent, in G2/M exposed cells. G1 cells appeared more resistant to the amyloid-induced oxidative attack possibly because of their higher antioxidant capacity. The high vulnerability of S cells to aggregate toxicity extends previous data suggesting that neuronal loss in AD could result from mitotic reactivation of terminally differentiated neurons with arrest in the S phase.
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Affiliation(s)
- Cristina Cecchi
- Department of Biochemical Sciences, University of Florence, Viale Morgagni 50, 50134, Florence, Italy.
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Huang CJ, Lin CY, Haataja L, Gurlo T, Butler AE, Rizza RA, Butler PC. High expression rates of human islet amyloid polypeptide induce endoplasmic reticulum stress mediated beta-cell apoptosis, a characteristic of humans with type 2 but not type 1 diabetes. Diabetes 2007; 56:2016-27. [PMID: 17475933 DOI: 10.2337/db07-0197] [Citation(s) in RCA: 317] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Endoplasmic reticulum (ER) stress-induced apoptosis may be a common cause of cell attrition in diseases characterized by misfolding and oligomerisation of amyloidogenic proteins. The islet in type 2 diabetes is characterized by islet amyloid derived from islet amyloid polypeptide (IAPP) and increased beta-cell apoptosis. We questioned the following: 1) whether IAPP-induced beta-cell apoptosis is mediated by ER stress and 2) whether beta-cells in type 2 diabetes are characterized by ER stress. RESEARCH DESIGN AND METHODS The mechanism of IAPP-induced apoptosis was investigated in INS-1 cells and human IAPP (HIP) transgenic rats. ER stress in humans was investigated by beta-cell C/EBP homologous protein (CHOP) expression in 7 lean nondiabetic, 12 obese nondiabetic, and 14 obese type 2 diabetic human pancreata obtained at autopsy. To assure specificity for type 2 diabetes, we also examined pancreata from eight cases of type 1 diabetes. RESULTS IAPP induces beta-cell apoptosis by ER stress in INS-1 cells and HIP rats. Perinuclear CHOP was rare in lean nondiabetic (2.6 +/- 2.0%) and more frequent in obese nondiabetic (14.6 +/- 3.0%) and obese diabetic (18.5 +/- 3.6%) pancreata. Nuclear CHOP was not detected in lean nondiabetic and rare in obese nondiabetic (0.08 +/- 0.04%) but six times higher (P < 0.01) in obese diabetic (0.49 +/- 0.17%) pancreata. In type 1 diabetic pancreata, perinuclear CHOP was rare (2.5 +/- 2.3%) and nuclear CHOP not detected. CONCLUSIONS ER stress is a mechanism by which IAPP induces beta-cell apoptosis and is characteristic of beta-cells in humans with type 2 diabetes but not type 1 diabetes. These findings are consistent with a role of protein misfolding in beta-cell apoptosis in type 2 diabetes.
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Affiliation(s)
- Chang-jiang Huang
- Larry Hillblom Islet Research Center, University of California, Los Angeles, Los Angeles, CA 90024-2852., USA
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Jayasinghe SA, Langen R. Membrane interaction of islet amyloid polypeptide. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:2002-9. [PMID: 17349968 DOI: 10.1016/j.bbamem.2007.01.022] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 01/26/2007] [Accepted: 01/30/2007] [Indexed: 10/23/2022]
Abstract
Increasing evidence suggests that the misfolding and deposition of IAPP plays an important role in the pathogenesis of type II, or non-insulin-dependent diabetes mellitus (T2DM). Membranes have been implicated in IAPP-dependent toxicity in several ways: Lipid membranes have been shown to promote the misfolding and aggregation of IAPP. Thus, potentially toxic forms of IAPP can be generated when IAPP interacts with cellular membranes. In addition, membranes have been implicated as the target of IAPP toxicity. IAPP has been shown to disrupt membrane integrity and to permeabilize membranes. Since disruption of cellular membranes is highly toxic, such a mechanism has been suggested to explain the observed IAPP toxicity. Here, we review IAPP-membrane interaction in the context of (1) catalyzing IAPP misfolding and (2) being a potential origin of IAPP toxicity.
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Affiliation(s)
- Sajith A Jayasinghe
- Department of Chemistry and Biochemistry, California State University, 333 South Twin Oaks Valley Road, San Marcos, CA 92096, USA
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50
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Kaput J, Dawson K. Complexity of type 2 diabetes mellitus data sets emerging from nutrigenomic research: a case for dimensionality reduction? Mutat Res 2007; 622:19-32. [PMID: 17559889 PMCID: PMC1994901 DOI: 10.1016/j.mrfmmm.2007.02.033] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Accepted: 02/13/2007] [Indexed: 02/07/2023]
Abstract
Nutrigenomics promises personalized nutrition and an improvement in preventing, delaying, and reducing the symptoms of chronic diseases such as diabetes. Nutritional genomics is the study of how foods affect the expression of genetic information in an individual and how an individual's genetic makeup affects the metabolism and response to nutrients and other bioactive components in food. The path to those promises has significant challenges, from experimental designs that include analysis of genetic heterogeneity to the complexities of food and environmental factors. One of the more significant complications in developing the knowledge base and potential applications is how to analyze high-dimensional datasets of genetic, nutrient, metabolomic (clinical), and other variables influencing health and disease processes. Type 2 diabetes mellitus (T2DM) is used as an illustration of the challenges in studying complex phenotypes with nutrigenomics concepts and approaches.
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Affiliation(s)
- Jim Kaput
- Center of Excellence in Nutritional Genomics, University of California at Davis, Davis, CA 95616, USA.
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