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Dai Z, Ben-Younis A, Vlachaki A, Raleigh D, Thalassinos K. Understanding the structural dynamics of human islet amyloid polypeptide: Advancements in and applications of ion-mobility mass spectrometry. Biophys Chem 2024; 312:107285. [PMID: 38941872 PMCID: PMC11260546 DOI: 10.1016/j.bpc.2024.107285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 05/30/2024] [Accepted: 06/23/2024] [Indexed: 06/30/2024]
Abstract
Human islet amyloid polypeptide (hIAPP) forms amyloid deposits that contribute to β-cell death in pancreatic islets and are considered a hallmark of Type II diabetes Mellitus (T2DM). Evidence suggests that the early oligomers of hIAPP formed during the aggregation process are the primary pathological agent in islet amyloid induced β-cell death. The self-assembly mechanism of hIAPP, however, remains elusive, largely due to limitations in conventional biophysical techniques for probing the distribution or capturing detailed structures of the early, structurally dynamic oligomers. The advent of Ion-mobility Mass Spectrometry (IM-MS) has enabled the characterisation of hIAPP early oligomers in the gas phase, paving the way towards a deeper understanding of the oligomerisation mechanism and the correlation of structural information with the cytotoxicity of the oligomers. The sensitivity and the rapid structural characterisation provided by IM-MS also show promise in screening hIAPP inhibitors, categorising their modes of inhibition through "spectral fingerprints". This review delves into the application of IM-MS to the dissection of the complex steps of hIAPP oligomerisation, examining the inhibitory influence of metal ions, and exploring the characterisation of hetero-oligomerisation with different hIAPP variants. We highlight the potential of IM-MS as a tool for the high-throughput screening of hIAPP inhibitors, and for providing insights into their modes of action. Finally, we discuss advances afforded by recent advancements in tandem IM-MS and the combination of gas phase spectroscopy with IM-MS, which promise to deliver a more sensitive and higher-resolution structural portrait of hIAPP oligomers. Such information may help facilitate a new era of targeted therapeutic strategies for islet amyloidosis in T2DM.
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Affiliation(s)
- Zijie Dai
- Institute of Structural and Molecular Biology, Division of Bioscience, University College London, London WC1E 6BT, UK
| | - Aisha Ben-Younis
- Institute of Structural and Molecular Biology, Division of Bioscience, University College London, London WC1E 6BT, UK
| | - Anna Vlachaki
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Forvie Site, Robinson Way, Cambridge CB2 0PY, UK
| | - Daniel Raleigh
- Institute of Structural and Molecular Biology, Division of Bioscience, University College London, London WC1E 6BT, UK; Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794, United States.
| | - Konstantinos Thalassinos
- Institute of Structural and Molecular Biology, Division of Bioscience, University College London, London WC1E 6BT, UK; Institute of Structural and Molecular Biology, Birkbeck College, University of London, London WC1E 7HX, UK.
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2
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McCalpin SD, Khemtemourian L, Suladze S, Ivanova MI, Reif B, Ramamoorthy A. Zinc and pH modulate the ability of insulin to inhibit aggregation of islet amyloid polypeptide. Commun Biol 2024; 7:776. [PMID: 38937578 PMCID: PMC11211420 DOI: 10.1038/s42003-024-06388-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 05/27/2024] [Indexed: 06/29/2024] Open
Abstract
Aggregation of the human islet amyloid polypeptide (hIAPP) contributes to the development and progression of Type 2 Diabetes (T2D). hIAPP aggregates within a few hours at few micromolar concentration in vitro but exists at millimolar concentrations in vivo. Natively occurring inhibitors of hIAPP aggregation might therefore provide a model for drug design against amyloid formation associated with T2D. Here, we describe the combined ability of low pH, zinc, and insulin to inhibit hIAPP fibrillation. Insulin dose-dependently slows hIAPP aggregation near neutral pH but had less effect on the aggregation kinetics at acidic pH. We determine that insulin alters hIAPP aggregation in two manners. First, insulin diverts the aggregation pathway to large nonfibrillar aggregates with ThT-positive molecular structure, rather than to amyloid fibrils. Second, soluble insulin suppresses hIAPP dimer formation, which is an important early aggregation event. Further, we observe that zinc significantly modulates the inhibition of hIAPP aggregation by insulin. We hypothesize that this effect arose from controlling the oligomeric state of insulin and show that hIAPP interacts more strongly with monomeric than oligomeric insulin.
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Affiliation(s)
- Samuel D McCalpin
- Biophysics Program, University of Michigan, Arbor, MI, 48109, USA
- Department of Chemistry, University of Michigan, Arbor, MI, 48109, USA
| | - Lucie Khemtemourian
- Institute of Chemistry and Biology of Membranes and Nanoobjects (CBMN), CNRS - UMR 5248, Institut Polytechnique Bordeaux, University of Bordeaux, 33600, Pessac, France
| | - Saba Suladze
- Bayerisches NMR Zentrum (BNMRZ) at the Department of Biosciences, School of Natural Sciences, Technische Universität München, Munich, Germany
- Helmholtz-Zentrum München (HMGU), Deutsches Forschungszentrum für Gesundheit und Umwelt, Institute of Structural Biology (STB), Ingolstädter Landstr. 1, 85764, Neuherberg, Germany
| | - Magdalena I Ivanova
- Biophysics Program, University of Michigan, Arbor, MI, 48109, USA
- Department of Neurology, University of Michigan, Arbor, MI, 48109, USA
- Michigan Neuroscience Institute, University of Michigan, Arbor, MI, 48109, USA
| | - Bernd Reif
- Bayerisches NMR Zentrum (BNMRZ) at the Department of Biosciences, School of Natural Sciences, Technische Universität München, Munich, Germany
- Helmholtz-Zentrum München (HMGU), Deutsches Forschungszentrum für Gesundheit und Umwelt, Institute of Structural Biology (STB), Ingolstädter Landstr. 1, 85764, Neuherberg, Germany
| | - Ayyalusamy Ramamoorthy
- Biophysics Program, University of Michigan, Arbor, MI, 48109, USA.
- Department of Chemistry, University of Michigan, Arbor, MI, 48109, USA.
- Department of Neurology, University of Michigan, Arbor, MI, 48109, USA.
- Michigan Neuroscience Institute, University of Michigan, Arbor, MI, 48109, USA.
- Biomedical Engineering, Macromolecular Science and Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
- National High Magnetic Field Laboratory, Department of Chemical and Biomedical Engineering, Institute of Molecular Biophysics, Neuroscience, Florida State University, Tallahassee, FL, 32310, USA.
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3
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Parchure A, Tian M, Stalder D, Boyer CK, Bearrows SC, Rohli KE, Zhang J, Rivera-Molina F, Ramazanov BR, Mahata SK, Wang Y, Stephens SB, Gershlick DC, von Blume J. Liquid-liquid phase separation facilitates the biogenesis of secretory storage granules. J Cell Biol 2022; 221:e202206132. [PMID: 36173346 PMCID: PMC9526250 DOI: 10.1083/jcb.202206132] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 02/03/2023] Open
Abstract
Insulin is synthesized by pancreatic β-cells and stored into secretory granules (SGs). SGs fuse with the plasma membrane in response to a stimulus and deliver insulin to the bloodstream. The mechanism of how proinsulin and its processing enzymes are sorted and targeted from the trans-Golgi network (TGN) to SGs remains mysterious. No cargo receptor for proinsulin has been identified. Here, we show that chromogranin (CG) proteins undergo liquid-liquid phase separation (LLPS) at a mildly acidic pH in the lumen of the TGN, and recruit clients like proinsulin to the condensates. Client selectivity is sequence-independent but based on the concentration of the client molecules in the TGN. We propose that the TGN provides the milieu for converting CGs into a "cargo sponge" leading to partitioning of client molecules, thus facilitating receptor-independent client sorting. These findings provide a new receptor-independent sorting model in β-cells and many other cell types and therefore represent an innovation in the field of membrane trafficking.
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Affiliation(s)
- Anup Parchure
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
| | - Meng Tian
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
| | - Danièle Stalder
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Cierra K. Boyer
- Departments of Pharmacology and Neuroscience, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA
- Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA
| | - Shelby C. Bearrows
- Departments of Pharmacology and Neuroscience, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA
- Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA
| | - Kristen E. Rohli
- Departments of Pharmacology and Neuroscience, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA
- Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA
| | - Jianchao Zhang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI
- Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI
| | - Felix Rivera-Molina
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
| | - Bulat R. Ramazanov
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
| | - Sushil K. Mahata
- Department of Medicine, University of California San Diego, La Jolla, CA
- VA San Diego Healthcare System, San Diego, CA
| | - Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI
- Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI
| | - Samuel B. Stephens
- Departments of Pharmacology and Neuroscience, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA
| | - David C. Gershlick
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Julia von Blume
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
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4
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Linking hIAPP misfolding and aggregation with type 2 diabetes mellitus: a structural perspective. Biosci Rep 2022; 42:231205. [PMID: 35475576 PMCID: PMC9118370 DOI: 10.1042/bsr20211297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 04/12/2022] [Accepted: 04/26/2022] [Indexed: 11/17/2022] Open
Abstract
There are over 40 identified human disorders that involve certain proteins folding incorrectly, accumulating in the body causing damage to cells and organs and causing disease. Type 2 Diabetes Mellitus (T2DM) is one of these protein misfolding disorders (PMDs) and involves human islet amyloid polypeptide (hIAPP) misfolding and accumulating in parts of the body, primarily in the pancreas, causing damage to islet cells and affecting glucose regulation. In this review, we have summarised our current understanding of what causes hIAPP to misfold, what conformations are found in different parts of the body with a particular focus on what is known about the structure of hIAPP and how this links to T2DM. Understanding the molecular basis behind these misfolding events is essential for understanding the role of hIAPP to develop better therapeutics since type 2 diabetes currently affects over 4.9 million people in the United Kingdom alone and is predicted to increase as our population ages.
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5
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Pang H, Li J, Li SJ. Role of the voltage-gated proton channel Hv1 in insulin secretion, glucose homeostasis, and obesity. J Physiol Biochem 2022; 78:593-601. [PMID: 35353324 DOI: 10.1007/s13105-022-00891-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 03/11/2022] [Indexed: 10/18/2022]
Abstract
Diabetes is characterized by an absolutely inadequate insulin secretion (type 1 diabetes mellitus) or a relative deficit in insulin secretion due to insulin resistance (type 2 diabetes mellitus), both of which result in elevated blood glucose. Understanding the molecular mechanisms underlying the pathophysiology of diabetes could lead to the development of new therapeutic approaches. The voltage-gated proton channel Hv1 is an ion channel with specific selectivity for protons, which is regulated by membrane potential and intracellular pH. Recently, our studies showed that Hv1 is expressed in β cells of the endocrine pancreas. Knockout of Hv1 reduces insulin secretion and results in hyperglycemia and glucose intolerance, but not insulin resistance. Furthermore, knockout of Hv1 leads to diet-induced obesity due to inflammation and hepatic steatosis. Increasing evidence suggests that Hv1 plays a pivotal role in glucose homeostasis and lipid metabolism. This review aims to summarize advances made so far in our understanding of the roles of Hv1 in the regulation of insulin secretion in β cells, glucose homeostasis, and obesity.
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Affiliation(s)
- Huimin Pang
- Department of Biophysics, School of Physics, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, 94 Weijin Road, Nankai District, Tianjin, 300071, People's Republic of China
| | - Jinwen Li
- Department of Biophysics, School of Physics, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, 94 Weijin Road, Nankai District, Tianjin, 300071, People's Republic of China
| | - Shu Jie Li
- Department of Biophysics, School of Physics, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, 94 Weijin Road, Nankai District, Tianjin, 300071, People's Republic of China.
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6
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Integrative structural modelling and visualisation of a cellular organelle. QRB DISCOVERY 2022. [PMID: 37529283 PMCID: PMC10392685 DOI: 10.1017/qrd.2022.10] [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] Open
Abstract
Abstract
Models of insulin secretory vesicles from pancreatic beta cells have been created using the cellPACK suite of tools to research, curate, construct and visualise the current state of knowledge. The model integrates experimental information from proteomics, structural biology, cryoelectron microscopy and X-ray tomography, and is used to generate models of mature and immature vesicles. A new method was developed to generate a confidence score that reconciles inconsistencies between three available proteomes using expert annotations of cellular localisation. The models are used to simulate soft X-ray tomograms, allowing quantification of features that are observed in experimental tomograms, and in turn, allowing interpretation of X-ray tomograms at the molecular level.
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7
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Rodriguez Camargo DC, Chia S, Menzies J, Mannini B, Meisl G, Lundqvist M, Pohl C, Bernfur K, Lattanzi V, Habchi J, Cohen SI, Knowles TPJ, Vendruscolo M, Linse S. Surface-Catalyzed Secondary Nucleation Dominates the Generation of Toxic IAPP Aggregates. Front Mol Biosci 2021; 8:757425. [PMID: 34790701 PMCID: PMC8591229 DOI: 10.3389/fmolb.2021.757425] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 10/12/2021] [Indexed: 01/22/2023] Open
Abstract
The aggregation of the human islet amyloid polypeptide (IAPP) is associated with diabetes type II. A quantitative understanding of this connection at the molecular level requires that the aggregation mechanism of IAPP is resolved in terms of the underlying microscopic steps. Here we have systematically studied recombinant IAPP, with amidated C-terminus in oxidised form with a disulphide bond between residues 3 and 7, using thioflavin T fluorescence to monitor the formation of amyloid fibrils as a function of time and IAPP concentration. We used global kinetic analyses to connect the macroscopic measurements of aggregation to the microscopic mechanisms, and show that the generation of new aggregates is dominated by the secondary nucleation of monomers on the fibril surface. We then exposed insulinoma cells to aliquots extracted from different time points of the aggregation process, finding the highest toxicity at the midpoint of the reaction, when the secondary nucleation rate reaches its maximum. These results identify IAPP oligomers as the most cytotoxic species generated during IAPP aggregation, and suggest that compounds that target secondary nucleation of IAPP could be most effective as therapeutic candidates for diabetes type II.
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Affiliation(s)
- Diana C Rodriguez Camargo
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden.,Wren Therapeutics Limited, Clarendon House, Cambridge, United Kingdom
| | - Sean Chia
- Wren Therapeutics Limited, Clarendon House, Cambridge, United Kingdom.,Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Joseph Menzies
- Wren Therapeutics Limited, Clarendon House, Cambridge, United Kingdom
| | - Benedetta Mannini
- Wren Therapeutics Limited, Clarendon House, Cambridge, United Kingdom.,Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Georg Meisl
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Martin Lundqvist
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Christin Pohl
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Katja Bernfur
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Veronica Lattanzi
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Johnny Habchi
- Wren Therapeutics Limited, Clarendon House, Cambridge, United Kingdom.,Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Samuel Ia Cohen
- Wren Therapeutics Limited, Clarendon House, Cambridge, United Kingdom
| | - Tuomas P J Knowles
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.,Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Michele Vendruscolo
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Sara Linse
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
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8
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Babych M, Nguyen PT, Côté-Cyr M, Kihal N, Quittot N, Golizeh M, Sleno L, Bourgault S. Site-Specific Alkylation of the Islet Amyloid Polypeptide Accelerates Self-Assembly and Potentiates Perturbation of Lipid Membranes. Biochemistry 2021; 60:2285-2299. [PMID: 34264642 DOI: 10.1021/acs.biochem.1c00308] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The accumulation of insoluble amyloids in the pancreatic islets is a pathological hallmark of type II diabetes and correlates closely with the loss of β-cell mass. The predominant component of these amyloid deposits is the islet amyloid polypeptide (IAPP). The factors contributing to the conversion of IAPP from a monomeric bioactive peptide hormone into insoluble amyloid fibrils remain partially elusive. In this study, we investigated the effect of the oxidative non-enzymatic post-translational modification induced by the reactive metabolite 4-hydroxynonenal (HNE) on IAPP aggregation and cytotoxicity. Incubation of IAPP with exogenous HNE accelerated its self-assembly into β-sheet fibrils and led to the formation of a Michael adduct on the His-18 side chain. To model this covalent modification, the imidazole N(π) position of histidine was alkylated using a close analogue of HNE, the octyl chain. IAPP lipidated at His-18 showed a hastened random coil-to-β-sheet conformational conversion into fibrillar assemblies with a distinct morphology, a low level of binding to thioflavin T, and a high surface hydrophobicity. Introducing an octyl chain on His-18 enhanced the ability of the peptide to perturb synthetic lipid vesicles, to permeabilize the plasma membrane, and to induce the death of pancreatic β-cells. Alkylated IAPP triggered the self-assembly of unmodified IAPP by prompting primary nucleation and increased its capacity to perturb the plasma membrane, indicating that only a small proportion of the modified peptide is necessary to shift the balance toward the formation of proteotoxic species. This study underlines the importance of studying IAPP post-translational modifications induced by oxidative metabolites in the context of pancreatic amyloids.
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Affiliation(s)
- Margaryta Babych
- Department of Chemistry, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montreal H3C 3P8, Canada.,Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO, http://proteo.ca/en/
| | - Phuong Trang Nguyen
- Department of Chemistry, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montreal H3C 3P8, Canada.,Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO, http://proteo.ca/en/
| | - Mélanie Côté-Cyr
- Department of Chemistry, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montreal H3C 3P8, Canada.,Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO, http://proteo.ca/en/
| | - Nadjib Kihal
- Department of Chemistry, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montreal H3C 3P8, Canada.,Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO, http://proteo.ca/en/
| | - Noé Quittot
- Department of Chemistry, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montreal H3C 3P8, Canada.,Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO, http://proteo.ca/en/
| | - Makan Golizeh
- Department of Mathematical and Physical Sciences, Concordia University of Edmonton, Edmonton, AB T5B 4E4, Canada
| | - Lekha Sleno
- Department of Chemistry, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montreal H3C 3P8, Canada
| | - Steve Bourgault
- Department of Chemistry, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montreal H3C 3P8, Canada.,Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO, http://proteo.ca/en/
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9
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Westholm E, Wendt A, Eliasson L. Islet Function in the Pathogenesis of Cystic Fibrosis-Related Diabetes Mellitus. CLINICAL MEDICINE INSIGHTS-ENDOCRINOLOGY AND DIABETES 2021; 14:11795514211031204. [PMID: 34345195 PMCID: PMC8280842 DOI: 10.1177/11795514211031204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 06/22/2021] [Indexed: 12/12/2022]
Abstract
Cystic fibrosis-related diabetes mellitus (CFRD) is the most common non-pulmonary
co-morbidity in cystic fibrosis (CF). CF is caused by mutations in the cystic
fibrosis transmembrane conductance regulator gene (CFTR), which
leads to aberrant luminal fluid secretions in organs such as the lungs and
pancreas. How dysfunctional CFTR leads to CFRD is still under debate. Both
intrinsic effects of dysfunctional CFTR in hormone secreting cells of the islets
and effects of exocrine damage have been proposed. In the current review, we
discuss these non-mutually exclusive hypotheses with a special focus on how
dysfunctional CFTR in endocrine cells may contribute to an altered glucose
homeostasis. We outline the proposed role of CFTR in the molecular pathways of
β-cell insulin secretion and α-cell glucagon secretion, and touch upon the
importance of the exocrine pancreas and intra-pancreatic crosstalk for proper
islet function.
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Affiliation(s)
- Efraim Westholm
- Department of Clinical Sciences in Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden
| | - Anna Wendt
- Department of Clinical Sciences in Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden
| | - Lena Eliasson
- Department of Clinical Sciences in Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden
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10
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Lundqvist M, Rodriguez Camargo DC, Bernfur K, Chia S, Linse S. Expression, purification and characterisation of large quantities of recombinant human IAPP for mechanistic studies. Biophys Chem 2021; 269:106511. [PMID: 33360112 DOI: 10.1016/j.bpc.2020.106511] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 01/09/2023]
Abstract
Malfunction and amyloid formation of the Islet Amyloid Polypeptide (IAPP) are factors contributing to Type 2 diabetes. Unravelling the mechanism of IAPP aggregate formation may forward our understanding of this process and its effect on pancreatic β-islet cell. Such mechanistic studies require access to sequence homogeneous and highly pure IAPP. Here we present a new facile protocol for the production of pure recombinant human IAPP at relatively high yield. The protocol uses a His-tagged version of the Npro mutant EDDIE, which drives expression to inclusion bodies, from which the peptide is purified using sonication, refolding and auto-cleavage, removal of EDDIE using Ni-NTA chromatography and reverse-phase HPLC. The purified material is used at multiple concentrations in aggregation kinetics measurements monitored by thioflavin-T fluorescence. Global analysis of the data implies a double nucleation aggregation mechanism including both primary and secondary nucleation.
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Affiliation(s)
- Martin Lundqvist
- Department of Biophysical, Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Diana C Rodriguez Camargo
- Department of Biophysical, Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; Wren Therapeutics Limited, UK
| | - Katja Bernfur
- Department of Biophysical, Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | | | - Sara Linse
- Department of Biophysical, Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; Wren Therapeutics Limited, UK.
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11
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Ntamo Y, Samodien E, Burger J, Muller N, Muller CJF, Chellan N. In vitro Characterization of Insulin-Producing β-Cell Spheroids. Front Cell Dev Biol 2021; 8:623889. [PMID: 33585464 PMCID: PMC7876261 DOI: 10.3389/fcell.2020.623889] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/23/2020] [Indexed: 12/18/2022] Open
Abstract
Over the years, immortalized rodent β-cell lines such as RIN, HIT, MIN, βTC, and INS-1 have been used to investigate pancreatic β-cell physiology using conventional two-dimensional (2D) culture techniques. However, physical and physiological limitations inherent to 2D cell culture necessitates confirmatory follow up studies using sentient animals. Three-dimensional (3D) culture models are gaining popularity for their recapitulation of key features of in vivo organ physiology, and thus could pose as potential surrogates for animal experiments. In this study, we aimed to develop and characterize a rat insulinoma INS-1 3D spheroid model to compare with 2D monolayers of the same cell line. Ultrastructural verification was done by transmission electron microscopy and toluidine blue staining, which showed that both 2D monolayers and 3D spheroids contained highly granulated cells with ultrastructural features synonymous with mature pancreatic β-cells, with increased prominence of these features observed in 3D spheroids. Viability, as assessed by cellular ATP quantification, size profiling and glucose utilization, showed that our spheroids remained viable for the experimental period of 30 days, compared to the limiting 5-day passage period of INS-1 monolayers. In fact, increasing ATP content together with spheroid size was observed over time, without adverse changes in glucose utilization. Additionally, β-cell function, assessed by determining insulin and amylin secretion, showed that the 3D spheroids retained glucose sensing and insulin secretory capability, that was more acute when compared to 2D monolayer cultures. Thus, we were able to successfully demonstrate that our in vitro INS-1 β-cell 3D spheroid model exhibits in vivo tissue-like structural features with extended viability and lifespan. This offers enhanced predictive capacity of the model in the study of metabolic disease, β-cell pathophysiology and the potential treatment thereof.
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Affiliation(s)
- Yonela Ntamo
- Biomedical Research and Innovation Platform, South African Medical Research Council, Cape Town, South Africa.,Department of Biochemistry and Microbiology, Faculty of Science and Agriculture, University of Zululand, KwaDlangezwa, South Africa
| | - Ebrahim Samodien
- Biomedical Research and Innovation Platform, South African Medical Research Council, Cape Town, South Africa
| | - Joleen Burger
- Biomedical Research and Innovation Platform, South African Medical Research Council, Cape Town, South Africa.,Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Nolan Muller
- National Health Laboratory Service, Anatomical Pathology, Tygerberg Hospital, Cape Town, South Africa
| | - Christo J F Muller
- Biomedical Research and Innovation Platform, South African Medical Research Council, Cape Town, South Africa.,Department of Biochemistry and Microbiology, Faculty of Science and Agriculture, University of Zululand, KwaDlangezwa, South Africa.,Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Nireshni Chellan
- Biomedical Research and Innovation Platform, South African Medical Research Council, Cape Town, South Africa.,Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
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12
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Milardi D, Gazit E, Radford SE, Xu Y, Gallardo RU, Caflisch A, Westermark GT, Westermark P, Rosa CL, Ramamoorthy A. Proteostasis of Islet Amyloid Polypeptide: A Molecular Perspective of Risk Factors and Protective Strategies for Type II Diabetes. Chem Rev 2021; 121:1845-1893. [PMID: 33427465 DOI: 10.1021/acs.chemrev.0c00981] [Citation(s) in RCA: 117] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The possible link between hIAPP accumulation and β-cell death in diabetic patients has inspired numerous studies focusing on amyloid structures and aggregation pathways of this hormone. Recent studies have reported on the importance of early oligomeric intermediates, the many roles of their interactions with lipid membrane, pH, insulin, and zinc on the mechanism of aggregation of hIAPP. The challenges posed by the transient nature of amyloid oligomers, their structural heterogeneity, and the complex nature of their interaction with lipid membranes have resulted in the development of a wide range of biophysical and chemical approaches to characterize the aggregation process. While the cellular processes and factors activating hIAPP-mediated cytotoxicity are still not clear, it has recently been suggested that its impaired turnover and cellular processing by proteasome and autophagy may contribute significantly toward toxic hIAPP accumulation and, eventually, β-cell death. Therefore, studies focusing on the restoration of hIAPP proteostasis may represent a promising arena for the design of effective therapies. In this review we discuss the current knowledge of the structures and pathology associated with hIAPP self-assembly and point out the opportunities for therapy that a detailed biochemical, biophysical, and cellular understanding of its aggregation may unveil.
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Affiliation(s)
- Danilo Milardi
- Istituto di Cristallografia, Consiglio Nazionale delle Ricerche, Via P. Gaifami 18, 95126 Catania, Italy
| | - Ehud Gazit
- Department of Molecular Microbiology and Biotechnology, The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Yong Xu
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Rodrigo U Gallardo
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Amedeo Caflisch
- Department of Biochemistry, University of Zürich, Zürich CH-8057, Switzerland
| | - Gunilla T Westermark
- Department of Medical Cell Biology, Uppsala University, SE-751 23 Uppsala, Sweden
| | - Per Westermark
- Department of Immunology, Genetics and Pathology, Uppsala University, SE-751 85 Uppsala, Sweden
| | - Carmelo La Rosa
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale Andrea Doria 6, 95125 Catania, Italy
| | - Ayyalusamy Ramamoorthy
- Biophysics, Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 41809-1055, United States
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13
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Roep BO. There Is Something About Insulin Granules. Diabetes 2020; 69:2575-2577. [PMID: 33219101 PMCID: PMC7679780 DOI: 10.2337/dbi20-0039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Bart O Roep
- Department of Diabetes Immunology, Diabetes & Metabolism Research Institute at the Beckman Research Institute, City of Hope National Medical Center, Duarte, CA
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14
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Schumann T, König J, Henke C, Willmes DM, Bornstein SR, Jordan J, Fromm MF, Birkenfeld AL. Solute Carrier Transporters as Potential Targets for the Treatment of Metabolic Disease. Pharmacol Rev 2020; 72:343-379. [PMID: 31882442 DOI: 10.1124/pr.118.015735] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The solute carrier (SLC) superfamily comprises more than 400 transport proteins mediating the influx and efflux of substances such as ions, nucleotides, and sugars across biological membranes. Over 80 SLC transporters have been linked to human diseases, including obesity and type 2 diabetes (T2D). This observation highlights the importance of SLCs for human (patho)physiology. Yet, only a small number of SLC proteins are validated drug targets. The most recent drug class approved for the treatment of T2D targets sodium-glucose cotransporter 2, product of the SLC5A2 gene. There is great interest in identifying other SLC transporters as potential targets for the treatment of metabolic diseases. Finding better treatments will prove essential in future years, given the enormous personal and socioeconomic burden posed by more than 500 million patients with T2D by 2040 worldwide. In this review, we summarize the evidence for SLC transporters as target structures in metabolic disease. To this end, we identified SLC13A5/sodium-coupled citrate transporter, and recent proof-of-concept studies confirm its therapeutic potential in T2D and nonalcoholic fatty liver disease. Further SLC transporters were linked in multiple genome-wide association studies to T2D or related metabolic disorders. In addition to presenting better-characterized potential therapeutic targets, we discuss the likely unnoticed link between other SLC transporters and metabolic disease. Recognition of their potential may promote research on these proteins for future medical management of human metabolic diseases such as obesity, fatty liver disease, and T2D. SIGNIFICANCE STATEMENT: Given the fact that the prevalence of human metabolic diseases such as obesity and type 2 diabetes has dramatically risen, pharmacological intervention will be a key future approach to managing their burden and reducing mortality. In this review, we present the evidence for solute carrier (SLC) genes associated with human metabolic diseases and discuss the potential of SLC transporters as therapeutic target structures.
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Affiliation(s)
- Tina Schumann
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Jörg König
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Christine Henke
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Diana M Willmes
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Stefan R Bornstein
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Jens Jordan
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Martin F Fromm
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Andreas L Birkenfeld
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
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15
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Liquid-liquid phase separation of type II diabetes-associated IAPP initiates hydrogelation and aggregation. Proc Natl Acad Sci U S A 2020; 117:12050-12061. [PMID: 32414928 PMCID: PMC7275713 DOI: 10.1073/pnas.1916716117] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Deposition of some aggregated and misfolded polypeptides (amyloids) is the hallmark of many degenerative diseases. Amyloid assembly is slow, unfavorable, and still poorly understood. Here, we show that liquid–liquid demixing (like oil forming droplets in water) of type II diabetes IAPP amyloid precursors is not dependent on the human amyloidogenic sequence and leads to the formation of a water-filled gel within phase-separated droplets. Both processes then trigger pathological aggregation at the droplet surface, which is modulated by insulin. This localized aggregation propagates to interconnect droplets, leading to a macroscopic meshwork formation with increased local viscosity, eventually percolating the whole system. These processes may be at the heart of the pathology of type II diabetes. Amyloidoses (misfolded polypeptide accumulation) are among the most debilitating diseases our aging societies face. Amyloidogenesis can be catalyzed by hydrophobic–hydrophilic interfaces (e.g., air–water interface in vitro [AWI]). We recently demonstrated hydrogelation of the amyloidogenic type II diabetes-associated islet amyloid polypeptide (IAPP), a hydrophobic–hydrophilic interface-dependent process with complex kinetics. We demonstrate that human IAPP undergoes AWI-catalyzed liquid–liquid phase separation (LLPS), which initiates hydrogelation and aggregation. Insulin modulates these processes but does not prevent them. Using nonamyloidogenic rat IAPP, we show that, whereas LLPS does not require the amyloidogenic sequence, hydrogelation and aggregation do. Interestingly, both insulin and rat sequence delayed IAPP LLPS, which may reflect physiology. By developing an experimental setup and analysis tools, we show that, within the whole system (beyond the droplet stage), macroscopic interconnected aggregate clusters form, grow, fuse, and evolve via internal rearrangement, leading to overall hydrogelation. As the AWI-adsorbed gelled layer matures, its microviscosity increases. LLPS-driven aggregation may be a common amyloid feature and integral to pathology.
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16
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Wang H, Li S, Dai Q, Gonzalez A, Tran ON, Sun H, DeFronzo RA, Dean DD, Yeh CK, Chen XD. Culture on a native bone marrow-derived extracellular matrix restores the pancreatic islet basement membrane, preserves islet function, and attenuates islet immunogenicity. FASEB J 2020; 34:8044-8056. [PMID: 32307751 PMCID: PMC8034411 DOI: 10.1096/fj.201902893r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 03/19/2020] [Accepted: 03/31/2020] [Indexed: 11/11/2022]
Abstract
Islet transplantation in man is limited by multiple factors including islet availability, islet cell damage caused by collagenase during isolation, maintenance of islet function between isolation and transplantation, and allograft rejection. In this study, we describe a new approach for preparing islets that enhances islet function in vitro and reduces immunogenicity. The approach involves culture on native decellularized 3D bone marrow-derived extracellular matrix (3D-ECM), which contains many of the matrix components present in pancreas, prior to islet transplantation. Compared to islets cultured on tissue culture plastic (TCP), islets cultured on 3D-ECM exhibited greater attachment, higher survival rate, increased insulin content, and enhanced glucose-stimulated insulin secretion. In addition, culture of islets on 3D-ECM promoted recovery of vascular endothelial cells within the islets and restored basement membrane-related proteins (eg, fibronectin and collagen type VI). More interestingly, culture on 3D-ECM also selectively decontaminated islets of “passenger” cells (co-isolated with the islets) and restored basement membrane-associated type VI collagen, which were associated with an attenuation in islet immunogenicity. These results demonstrate that this novel approach has promise for overcoming two major issues in human islet transplantation: (a) poor yield of islets from donated pancreas tissue and (b) the need for life-long immunosuppression.
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Affiliation(s)
- Hanzhou Wang
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Shengxian Li
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.,Department of Endocrinology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, People's Republic of China
| | - Qiuxia Dai
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Aaron Gonzalez
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.,Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio, TX, USA
| | - Olivia N Tran
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.,Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio, TX, USA
| | - Haiyan Sun
- Department of Stomatology, Affiliated Hospital of the Academy of Military Medical Sciences, Beijing, People's Republic of China
| | - Ralph A DeFronzo
- Diabetes Division, Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - David D Dean
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.,Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio, TX, USA
| | - Chih-Ko Yeh
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.,Department of Veterans Affairs, South Texas Veterans Health Care System, San Antonio, TX, USA
| | - Xiao-Dong Chen
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.,Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio, TX, USA.,Department of Veterans Affairs, South Texas Veterans Health Care System, San Antonio, TX, USA
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17
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Pelaez-Aguilar A, Valdés-García G, French-Pacheco L, Pastor N, Amero C, Rivillas-Acevedo L. Site-Specific Interactions with Copper Promote Amyloid Fibril Formation for λ6aJL2-R24G. ACS OMEGA 2020; 5:7085-7095. [PMID: 32280849 PMCID: PMC7143407 DOI: 10.1021/acsomega.9b03220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 03/03/2020] [Indexed: 06/11/2023]
Abstract
Light-chain amyloidosis (AL) is one of the most common systemic amyloidoses, and it is characterized by the deposition of immunoglobulin light chain (LC) variable domains as insoluble amyloid fibers in vital organs and tissues. The recombinant protein 6aJL2-R24G contains λ6a and JL2 germline genes and also contains the Arg24 by Gly substitution. This mutation is present in 25% of all amyloid-associated λ6 LC cases, reduces protein stability, and increases the propensity to form amyloid fibers. In this study, it was found that the interaction of 6aJL2-R24G with Cu(II) decreases the thermal stability of the protein and accelerates the amyloid fibril formation, as observed by fluorescence spectroscopy. Isothermal calorimetry titration showed that Cu(II) binds to the protein with micromolar affinity. His99 may be one of the main Cu(II) interaction sites, as observed by nuclear magnetic resonance spectroscopy. The binding of Cu(II) to His99 induces larger fluctuations of the CDR1 and loop C″, as shown by molecular dynamics simulations. Thus, Cu(II) binding may be inducing the loss of interactions between CDR3 and CDR1, making the protein less stable and more prone to form amyloid fibers. This study provides insights into the mechanism of metal-induced aggregation of the 6aJL2-R24G protein and sheds light on the bio-inorganic understanding of AL disease.
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Affiliation(s)
- Angel
E. Pelaez-Aguilar
- Centro
de Investigación en Dinámica Celular-IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209, Mexico
| | - Gilberto Valdés-García
- Department
of Molecular Medicine and Bioprocesses, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, Mexico
| | - Leidys French-Pacheco
- Centro
de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209, Mexico
| | - Nina Pastor
- Centro
de Investigación en Dinámica Celular-IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209, Mexico
- Department
of Molecular Medicine and Bioprocesses, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, Mexico
| | - Carlos Amero
- Centro
de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209, Mexico
| | - Lina Rivillas-Acevedo
- Centro
de Investigación en Dinámica Celular-IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209, Mexico
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18
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Saitta F, Signorelli M, Fessas D. Hierarchy of interactions dictating the thermodynamics of real cell membranes: Following the insulin secretory granules paradigm up to fifteen-components vesicles. Colloids Surf B Biointerfaces 2019; 186:110715. [PMID: 31841777 DOI: 10.1016/j.colsurfb.2019.110715] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 11/09/2019] [Accepted: 12/07/2019] [Indexed: 11/26/2022]
Abstract
A fifteen-components model membrane that reflected the 80 % of phospholipids present in Insulin Secretory Granules was obtained and thermodynamic exploitation was performed, through micro-DSC, in order to assess the synergic contributions to the stability of a mixed complex system very close to real membranes. Simpler systems were also stepwise investigated, to complete a previous preliminary study and to highlight a hierarchy of interactions that can be now summarized as phospholipid tail unsaturation > phospholipid tail length > phospholipid headgroup > membrane curvature. In particular, Small Unilamellar Vesicles (SUVs) that consisted in phospholipids with different headgroups (choline, ethanolamine and serine), was step by step considered, following inclusion of sphingomyelins and lysophosphatidylcholines together with a more complete fatty acids distribution characterizing the phospholipid bilayer of the Insulin Secretory Granules. The inclusion of cholesterol was finally considered and the influence of three FFAs (stearic, oleic and elaidic acids) was investigated in comparison with simpler systems, highlighting the magnitude of the effects on such a detailed membrane in the frame of Type 2 Diabetes Mellitus alterations.
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Affiliation(s)
- Francesca Saitta
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, DeFENS, Università degli Studi di Milano, Via Celoria 2, 20133, Milano, Italy
| | - Marco Signorelli
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, DeFENS, Università degli Studi di Milano, Via Celoria 2, 20133, Milano, Italy
| | - Dimitrios Fessas
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, DeFENS, Università degli Studi di Milano, Via Celoria 2, 20133, Milano, Italy.
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19
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Šolínová V, Žáková L, Jiráček J, Kašička V. Pressure assisted partial filling affinity capillary electrophoresis employed for determination of binding constants of human insulin hexamer complexes with serotonin, dopamine, arginine, and phenol. Anal Chim Acta 2019; 1052:170-178. [DOI: 10.1016/j.aca.2018.11.026] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/10/2018] [Accepted: 11/12/2018] [Indexed: 11/30/2022]
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20
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Demir C, Dogantekin A, Gurel A, Aydin S, Celiker H. Is there a relationship between serum vaspin levels and insulin resistance in chronic renal failure? Pak J Med Sci 2019; 35:230-235. [PMID: 30881429 PMCID: PMC6408677 DOI: 10.12669/pjms.35.1.96] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Objective Chronic kidney disease (CKD) patients have insulin secretion disorders and resistance to insulin effects, that is responsible for the development of cardiovascular events. Vaspin is an adipocytokine that regulates glucose and lipid metabolism. We aimed to determine the serum vaspin levels and its relationship with insulin resistance in CKD patients. Methods In the study groups, serum vaspin levels, anthropometric parameters and routine blood tests were measured. The serum vaspin levels were examined by the enzyme-linked immunosorbent assay (ELISA) and insulin resistance was determined by the homeostasis model assessment of insulin resistance (HOMA-IR) formula. Results The serum vaspin, HOMA-IR index and insulin levels were observed significantly high in the CKD group in comparison with the control group. No correlation was found between the serum vaspin level and the anthropometric and metabolic values. The serum vaspin level was positively correlated with the fasting plasma glucose and age but without statistical significance. Conclusion Insulin resistance and hyperinsulinemia contribute to the development of cardiovascular complications in CKD. We consider that the increase in the serum vaspin level is a consequence of the reduced renal excretion in the CKD and increases in response to insulin resistance.
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Affiliation(s)
- Can Demir
- Can Demir Hayat Hospital, Internal Medicine Department, Gaziantep, Turkey
| | - Akif Dogantekin
- Akif Dogantekin Emek Hospital, Internal Medicine Department, Gaziantep, Turkey
| | - Ali Gurel
- Ali Gurel Adiyaman University Medical Faculty, Nephrology Department, Adiyaman, Turkey
| | - Suleyman Aydin
- Suleyman Aydin Department of Biochemistry, Firat University Medical Faculty, Elazig, Turkey
| | - Huseyin Celiker
- Huseyin Celiker Deparment of Nephrology, Firat University Medical Faculty, Elazig, Turkey
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21
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Guest PC. Biogenesis of the Insulin Secretory Granule in Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1134:17-32. [PMID: 30919330 DOI: 10.1007/978-3-030-12668-1_2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The secretory granules of pancreatic beta cells are specialized organelles responsible for the packaging, storage and secretion of the vital hormone insulin. The insulin secretory granules also contain more than 100 other proteins including the proteases involved in proinsulin-to insulin conversion, other precursor proteins, minor co-secreted peptides, membrane proteins involved in cell trafficking and ion translocation proteins essential for regulation of the intragranular environment. The synthesis, transport and packaging of these proteins into nascent granules must be carried out in a co-ordinated manner to ensure correct functioning of the granule. The process is regulated by many circulating nutrients such as glucose and can change under different physiological states. This chapter discusses the various processes involved in insulin granule biogenesis with a focus on the granule composition in health and disease.
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Affiliation(s)
- Paul C Guest
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, Brazil.
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22
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Ferri G, Bugliani M, Marchetti P, Cardarelli F. Probing the light scattering properties of insulin secretory granules in single live cells. Biochem Biophys Res Commun 2018; 503:2710-2714. [PMID: 30119894 DOI: 10.1016/j.bbrc.2018.08.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 08/03/2018] [Indexed: 11/22/2022]
Abstract
Light scattering was recently demonstrated to serve as an intrinsic indicator for pancreatic islet cell mass and secretion. The insulin secretory granule (ISG), in particular, was proposed to be a reasonable candidate as the main intracellular source of scattered light due to the densely-packed insulin semi-crystal in the granule lumen. This scenario, if confirmed, would in principle open new perspectives for label-free single-granule imaging, tracking, and analysis. Contrary to such expectations, here we demonstrate that ISGs are not a primary source of scattering in primary human β-cells, as well as in immortalized β-like cells, quantitatively not superior to other intracellular organelles/structures, such as lysosomes and internal membranes. This result is achieved through multi-channel imaging of scattered light along with fluorescence arising from selectively-labelled ISGs. Co-localization and spatiotemporal cross-correlation analysis is performed on these signals, and compared among different cell lines. Obtained results suggest a careful re-thinking of the possibility to exploit intrinsic optical properties originating from ISGs for single-granule imaging purposes.
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Affiliation(s)
- Gianmarco Ferri
- NEST - Scuola Normale Superiore, Istituto Nanoscienze - CNR (CNR NANO), Pisa, Italy; Nanoscopy, Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, Genova, 16163 Italy
| | - Marco Bugliani
- Department of Clinical and Experimental Medicine, Islet Cell Laboratory, University of Pisa, Pisa, Italy
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, Islet Cell Laboratory, University of Pisa, Pisa, Italy
| | - Francesco Cardarelli
- NEST - Scuola Normale Superiore, Istituto Nanoscienze - CNR (CNR NANO), Pisa, Italy.
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23
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Rodriguez Camargo DC, Garg D, Buday K, Franko A, Rodriguez Camargo A, Schmidt F, Cox SJ, Suladze S, Haslbeck M, Mideksa YG, Gemmecker G, Aichler M, Mettenleiter G, Schulz M, Walch AK, Hrabě de Angelis M, Feige MJ, Sierra CA, Conrad M, Tripsianes K, Ramamoorthy A, Reif B. hIAPP forms toxic oligomers in plasma. Chem Commun (Camb) 2018; 54:5426-5429. [PMID: 29745410 PMCID: PMC5970100 DOI: 10.1039/c8cc03097a] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In diabetes, hyperamylinemia contributes to cardiac dysfunction. The interplay between hIAPP, blood glucose and other plasma components is, however, not understood. We show that glucose and LDL interact with hIAPP, resulting in β-sheet rich oligomers with increased β-cell toxicity and hemolytic activity, providing mechanistic insights for a direct link between diabetes and cardiovascular diseases.
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24
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Ge X, Kakinen A, Gurzov EN, Yang W, Pang L, Pilkington EH, Govindan-Nedumpully P, Chen P, Separovic F, Davis TP, Ke PC, Ding F. Zinc-coordination and C-peptide complexation: a potential mechanism for the endogenous inhibition of IAPP aggregation. Chem Commun (Camb) 2018; 53:9394-9397. [PMID: 28745731 DOI: 10.1039/c7cc04291d] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Aggregation of the highly amyloidogenic IAPP is endogenously inhibited inside beta-cell granules at millimolar concentrations. Combining in vitro experiments and computer simulations, we demonstrated that the stabilization of IAPP upon the formation of zinc-coordinated ion molecular complex with C-peptide might be important for the endogenous inhibition of IAPP aggregation.
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Affiliation(s)
- Xinwei Ge
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA.
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25
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IAPP/amylin and β-cell failure: implication of the risk factors of type 2 diabetes. Diabetol Int 2018; 9:143-157. [PMID: 30603362 DOI: 10.1007/s13340-018-0347-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 01/21/2018] [Indexed: 12/12/2022]
Abstract
In type 2 diabetes (T2D), the most significant pathological change in pancreatic islets is amyloid deposits, of which a major component is islet amyloid polypeptide (IAPP), also called amylin. IAPP is expressed in β-cells and co-secreted with insulin. Together with the inhibitory effects of synthetic human IAPP (hIAPP) on insulin secretion, our studies, using hIAPP transgenic mice, in which glucose-stimulated insulin secretion was moderately reduced without amyloid deposit, and hIAPP gene-transfected β-cell lines, in which insulin secretion was markedly impaired without amyloid, predicted that soluble hIAPP-related molecules would exert cytotoxicity on β-cells. Human IAPP is one of the most aggregation-prone peptides that interact with cell membranes. While it is widely reported that soluble hIAPP oligomers promote cytotoxicity, this is still a hypothesis since the mechanisms are not yet fully defined. Several hIAPP transgenic mouse models did not develop diabetes; however, in models with backgrounds characterized for diabetic phenotypes, β-cell function and glucose tolerance did worsen, compared to those in non-transgenic models with similar backgrounds. Together with these findings, many studies on metabolic and molecular disorders induced by risk factors of T2D suggest that in T2D subjects, toxic IAPP oligomers accumulate in β-cells, impair their function, and reduce mass through disruption of cell membranes, resulting in β-cell failure. IAPP might be central to β-cell failure in T2D. Anti-amyloid aggregation therapeutics will be developed to create treatments with more durable and beneficial effects on β-cell function.
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26
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Role of Zinc Homeostasis in the Pathogenesis of Diabetes and Obesity. Int J Mol Sci 2018; 19:ijms19020476. [PMID: 29415457 PMCID: PMC5855698 DOI: 10.3390/ijms19020476] [Citation(s) in RCA: 149] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 01/30/2018] [Accepted: 02/02/2018] [Indexed: 12/11/2022] Open
Abstract
Zinc deficiency is a risk factor for obesity and diabetes. However, until recently, the underlying molecular mechanisms remained unclear. The breakthrough discovery that the common polymorphism in zinc transporter SLC30A8/ZnT8 may increase susceptibility to type 2 diabetes provided novel insights into the role of zinc in diabetes. Our group and others showed that altered ZnT8 function may be involved in the pathogenesis of type 2 diabetes, indicating that the precise control of zinc homeostasis is crucial for maintaining health and preventing various diseases, including lifestyle-associated diseases. Recently, the role of the zinc transporter ZIP13 in the regulation of beige adipocyte biogenesis was clarified, which indicated zinc homeostasis regulation as a possible therapeutic target for obesity and metabolic syndrome. Here we review advances in the role of zinc homeostasis in the pathophysiology of diabetes, and propose that inadequate zinc distribution may affect the onset of diabetes and metabolic diseases by regulating various critical biological events.
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27
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Ke PC, Sani MA, Ding F, Kakinen A, Javed I, Separovic F, Davis TP, Mezzenga R. Implications of peptide assemblies in amyloid diseases. Chem Soc Rev 2017; 46:6492-6531. [PMID: 28702523 PMCID: PMC5902192 DOI: 10.1039/c7cs00372b] [Citation(s) in RCA: 239] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Neurodegenerative disorders and type 2 diabetes are global epidemics compromising the quality of life of millions worldwide, with profound social and economic implications. Despite the significant differences in pathology - much of which are poorly understood - these diseases are commonly characterized by the presence of cross-β amyloid fibrils as well as the loss of neuronal or pancreatic β-cells. In this review, we document research progress on the molecular and mesoscopic self-assembly of amyloid-beta, alpha synuclein, human islet amyloid polypeptide and prions, the peptides and proteins associated with Alzheimer's, Parkinson's, type 2 diabetes and prion diseases. In addition, we discuss the toxicities of these amyloid proteins based on their self-assembly as well as their interactions with membranes, metal ions, small molecules and engineered nanoparticles. Through this presentation we show the remarkable similarities and differences in the structural transitions of the amyloid proteins through primary and secondary nucleation, the common evolution from disordered monomers to alpha-helices and then to β-sheets when the proteins encounter the cell membrane, and, the consensus (with a few exceptions) that off-pathway oligomers, rather than amyloid fibrils, are the toxic species regardless of the pathogenic protein sequence or physicochemical properties. In addition, we highlight the crucial role of molecular self-assembly in eliciting the biological and pathological consequences of the amyloid proteins within the context of their cellular environments and their spreading between cells and organs. Exploiting such structure-function-toxicity relationship may prove pivotal for the detection and mitigation of amyloid diseases.
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Affiliation(s)
- Pu Chun Ke
- ARC Center of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Marc-Antonie Sani
- School of Chemistry, Bio21 Institute, The University of Melbourne, 30 Flemington Rd, Parkville, VIC 3010, Australia
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
| | - Aleksandr Kakinen
- ARC Center of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Ibrahim Javed
- ARC Center of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, The University of Melbourne, 30 Flemington Rd, Parkville, VIC 3010, Australia
| | - Thomas P. Davis
- ARC Center of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, CV4 7AL, United Kingdom
| | - Raffaele Mezzenga
- ETH Zurich, Department of Health Science & Technology, Schmelzbergstrasse 9, LFO, E23, 8092 Zurich, Switzerland
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28
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Patel P, Parmar K, Vyas VK, Patel D, Das M. Combined in silico approaches for the identification of novel inhibitors of human islet amyloid polypeptide (hIAPP) fibrillation. J Mol Graph Model 2017; 77:295-310. [PMID: 28917147 DOI: 10.1016/j.jmgm.2017.09.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 09/01/2017] [Accepted: 09/02/2017] [Indexed: 12/31/2022]
Abstract
Human islet amyloid polypeptide (hIAPP) is a natively unfolded polypeptide hormone of glucose metabolism, which is co-secreted with insulin by the β-cells of the pancreas. In patients with type 2 diabetes, IAPP forms amyloid fibrils because of diabetes-associated β-cells dysfunction and increasing fibrillation, in turn, lead to failure of secretory function of β-cells. This provides a target for the discovery of small organic molecules against protein aggregation diseases. However, the binding mechanism of these molecules with monomers, oligomers and fibrils to inhibit fibrillation is still an open question. In this work, ligand and structure-based in silico approaches were used to identify novel fibrillation inhibitors and/or fibril binding compounds. The best pharmacophore model was used as a 3D search query for virtual screening of a compound database to identify novel molecules having the potential to be therapeutic agents against protein aggregation diseases. Docking and molecular dynamics simulation studies were used to explore the interaction pattern and mechanism of the identified novel small molecules with predicted hIAPP structure, its aggregation prone conformation and fibril forming segments. We show that catechins with galloyl group and molecules having two to three planar apolar rings bind to hIAPP structures and fibril forming segments with greater affinity. The differences in binding affinities of different compounds against several fibril forming segments of the peptide suggest that a mixture of active compounds may be required for treatment of aggregation diseases.
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Affiliation(s)
- Palak Patel
- Institute of Science, Nirma University, Sarkhej-Gandhinagar Highway, Ahmedabad, Gujarat 382481, India
| | - Krupali Parmar
- Institute of Science, Nirma University, Sarkhej-Gandhinagar Highway, Ahmedabad, Gujarat 382481, India
| | - Vivek K Vyas
- Department of Pharmaceutical Chemistry, Institute of Pharmacy, Nirma University, Sarkhej-Gandhinagar Highway, Ahmedabad, Gujarat 382481, India
| | - Dhaval Patel
- Institute of Advanced Research, Koba Institutional Area, Gandhinagar, Gujarat 382007, India
| | - Mili Das
- Institute of Science, Nirma University, Sarkhej-Gandhinagar Highway, Ahmedabad, Gujarat 382481, India.
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29
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Wang B, Pilkington EH, Sun Y, Davis TP, Ke PC, Ding F. Modulating protein amyloid aggregation with nanomaterials. ENVIRONMENTAL SCIENCE. NANO 2017; 4:1772-1783. [PMID: 29230295 PMCID: PMC5722024 DOI: 10.1039/c7en00436b] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Direct exposure or intake of nanopaticles (NPs) to the human body can invoke a series of biological responses, some of which are deleterious, and as such the role of NPs in vivo requires thorough examination. Over the past decade, it has been established that biomolecules such as proteins can bind NPs to form a 'corona', where the structures and dynamics of NP-associated proteins can assign new functionality, systemic distribution and toxicity. However, the behavior and fate of NPs in biological systems are still far from being fully understood. Growing evidence has shown that some natural or artificial NPs could either up- or down-regulate protein amyloid aggregation, which is associated with neurodegenerative diseases like Alzheimer's and Parkinson's diseases, as well as metabolic diseases such as type 2 diabetes. These effects can be either indirect (e.g., through a crowding effect) or direct, depending on the NP composition, size, shape and surface chemistry. However, efforts to design anti-amyloid NPs for biomedical applications have been largely hindered by insufficient understanding of the complex processes, even though proof-of-concept experiments have been conducted. Therefore, exploring the general mechanisms of NP-meditated protein aggregation marks an emerging field in bio-nano research and a new stage of handling nanotechnology that not only aids in elucidating the origin of nanotoxicity, but also provides a foundation for engineering de novo anti-amyloid nanomedicines. In this review, we summarize research on NP-mediated protein amyloid aggregation, with the goal of contributing to sustained nanotechnology and safe nanomedicine against amyloid diseases.
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Affiliation(s)
- Bo Wang
- Department of Physics and Astronomy, Clemson University, Clemson, SC, USA
| | - Emily H Pilkington
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade Parkville, VIC 3052, Australia
| | - Yunxiang Sun
- Department of Physics and Astronomy, Clemson University, Clemson, SC, USA
| | - Thomas P Davis
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade Parkville, VIC 3052, Australia
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, CV4 7AL, UK
| | - Pu Chun Ke
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade Parkville, VIC 3052, Australia
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC, USA
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30
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Xu Y, Toomre DK, Bogan JS, Hao M. Excess cholesterol inhibits glucose-stimulated fusion pore dynamics in insulin exocytosis. J Cell Mol Med 2017; 21:2950-2962. [PMID: 28544529 PMCID: PMC5661106 DOI: 10.1111/jcmm.13207] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 03/28/2017] [Indexed: 01/06/2023] Open
Abstract
Type 2 diabetes is caused by defects in both insulin sensitivity and insulin secretion. Glucose triggers insulin secretion by causing exocytosis of insulin granules from pancreatic β-cells. High circulating cholesterol levels and a diminished capacity of serum to remove cholesterol from β-cells are observed in diabetic individuals. Both of these effects can lead to cholesterol accumulation in β-cells and contribute to β-cell dysfunction. However, the molecular mechanisms by which cholesterol accumulation impairs β-cell function remain largely unknown. Here, we used total internal reflection fluorescence microscopy to address, at the single-granule level, the role of cholesterol in regulating fusion pore dynamics during insulin exocytosis. We focused particularly on the effects of cholesterol overload, which is relevant to type 2 diabetes. We show that excess cholesterol reduced the number of glucose-stimulated fusion events, and modulated the proportion of full fusion and kiss-and-run fusion events. Analysis of single exocytic events revealed distinct fusion kinetics, with more clustered and compound exocytosis observed in cholesterol-overloaded β-cells. We provide evidence for the involvement of the GTPase dynamin, which is regulated in part by cholesterol-induced phosphatidylinositol 4,5-bisphosphate enrichment in the plasma membrane, in the switch between full fusion and kiss-and-run fusion. Characterization of insulin exocytosis offers insights into the role that elevated cholesterol may play in the development of type 2 diabetes.
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Affiliation(s)
- Yingke Xu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.,Department of Bioengineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang University, Hangzhou, China
| | - Derek K Toomre
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Jonathan S Bogan
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.,Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Mingming Hao
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA.,Department of Biochemistry, Weill Cornell Medical College, New York, NY, USA
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31
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Rodriguez Camargo DC, Tripsianes K, Buday K, Franko A, Göbl C, Hartlmüller C, Sarkar R, Aichler M, Mettenleiter G, Schulz M, Böddrich A, Erck C, Martens H, Walch AK, Madl T, Wanker EE, Conrad M, de Angelis MH, Reif B. The redox environment triggers conformational changes and aggregation of hIAPP in Type II Diabetes. Sci Rep 2017; 7:44041. [PMID: 28287098 PMCID: PMC5347123 DOI: 10.1038/srep44041] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 02/03/2017] [Indexed: 12/22/2022] Open
Abstract
Type II diabetes (T2D) is characterized by diminished insulin production and resistance of cells to insulin. Among others, endoplasmic reticulum (ER) stress is a principal factor contributing to T2D and induces a shift towards a more reducing cellular environment. At the same time, peripheral insulin resistance triggers the over-production of regulatory hormones such as insulin and human islet amyloid polypeptide (hIAPP). We show that the differential aggregation of reduced and oxidized hIAPP assists to maintain the redox equilibrium by restoring redox equivalents. Aggregation thus induces redox balancing which can assist initially to counteract ER stress. Failure of the protein degradation machinery might finally result in β-cell disruption and cell death. We further present a structural characterization of hIAPP in solution, demonstrating that the N-terminus of the oxidized peptide has a high propensity to form an α-helical structure which is lacking in the reduced state of hIAPP. In healthy cells, this residual structure prevents the conversion into amyloidogenic aggregates.
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Affiliation(s)
- Diana C Rodriguez Camargo
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany
| | - Konstantinos Tripsianes
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, Brno 62500, Czech Republic
| | - Katalin Buday
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | - Andras Franko
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,German Center for Diabetes Research (DZD e.V.), Neuherberg 85764, Germany
| | - Christoph Göbl
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany
| | - Christoph Hartlmüller
- Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany
| | - Riddhiman Sarkar
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany
| | - Michaela Aichler
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | | | - Michael Schulz
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | - Annett Böddrich
- Max-Delbrück-Center Berlin (MDC), Robert-Rössle-Str. 10, Berlin 13125, Germany
| | - Christian Erck
- Synaptic Systems GmbH, Rudolf-Wissell-Straße 28, Göttingen, 37079, Germany
| | - Henrik Martens
- Synaptic Systems GmbH, Rudolf-Wissell-Straße 28, Göttingen, 37079, Germany
| | - Axel Karl Walch
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | - Tobias Madl
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany.,Institute of Molecular Biology &Biochemistry, Center of Molecular Medicine, Medical University of Graz, Austria
| | - Erich E Wanker
- Max-Delbrück-Center Berlin (MDC), Robert-Rössle-Str. 10, Berlin 13125, Germany
| | - Marcus Conrad
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | - Martin Hrabě de Angelis
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,German Center for Diabetes Research (DZD e.V.), Neuherberg 85764, Germany.,Technische Universität München, Center of Life and Food Sciences Weihenstephan, Freising 85354, Germany
| | - Bernd Reif
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany
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32
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Eliasson L, Esguerra JLS, Wendt A. Lessons from basic pancreatic beta cell research in type-2 diabetes and vascular complications. Diabetol Int 2017; 8:139-152. [PMID: 30603317 DOI: 10.1007/s13340-017-0304-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 01/08/2017] [Indexed: 12/14/2022]
Abstract
The changes in life-style with increased access of food and reduced physical activity have resulted in the global epidemic of obesity. Consequently, individuals with type 2 diabetes and cardiovascular disease have also escalated. A central organ in the development of diabetes is the pancreas, and more specifically the pancreatic beta cells within the islets of Langerhans. Beta cells have been assigned the important task of secreting insulin when blood glucose is increased to lower the glucose level. An early sign of diabetes pathogenesis is lack of first phase insulin response and reduced second phase secretion. In this review, which is based on the foreign investigator award lecture given at the JSDC meeting in Sendai in October 2016, we discuss a possible cellular explanation for the reduced first phase insulin response and how this can be influenced by lipids. Moreover, since patients with cardiovascular disease and high levels of cholesterol are often treated with statins, we summarize recent data regarding effects on statins on glucose homeostasis and insulin secretion. Finally, we suggest microRNAs (miRNAs) as central players in the adjustment of beta cell function during the development of diabetes. We specifically discuss miRNAs regarding their involvement in insulin secretion regulation, differential expression in type 2 diabetes, and potential as biomarkers for prediction of diabetes and cardiovascular complications.
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Affiliation(s)
- Lena Eliasson
- Islet Cell Exocytosis, Department of Clinical Sciences Malmö, Lund University Diabetes Centre, Lund University, Clinical Research Centre, SUS 91-11, Box 50332, 202 13 Malmö, Sweden
| | - Jonathan Lou S Esguerra
- Islet Cell Exocytosis, Department of Clinical Sciences Malmö, Lund University Diabetes Centre, Lund University, Clinical Research Centre, SUS 91-11, Box 50332, 202 13 Malmö, Sweden
| | - Anna Wendt
- Islet Cell Exocytosis, Department of Clinical Sciences Malmö, Lund University Diabetes Centre, Lund University, Clinical Research Centre, SUS 91-11, Box 50332, 202 13 Malmö, Sweden
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33
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Du W, Zhou M, Zhao W, Cheng D, Wang L, Lu J, Song E, Feng W, Xue Y, Xu P, Xu T. HID-1 is required for homotypic fusion of immature secretory granules during maturation. eLife 2016; 5. [PMID: 27751232 PMCID: PMC5094852 DOI: 10.7554/elife.18134] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 10/17/2016] [Indexed: 02/06/2023] Open
Abstract
Secretory granules, also known as dense core vesicles, are generated at the trans-Golgi network and undergo several maturation steps, including homotypic fusion of immature secretory granules (ISGs) and processing of prehormones to yield active peptides. The molecular mechanisms governing secretory granule maturation are largely unknown. Here, we investigate a highly conserved protein named HID-1 in a mouse model. A conditional knockout of HID-1 in pancreatic β cells leads to glucose intolerance and a remarkable increase in the serum proinsulin/insulin ratio caused by defective proinsulin processing. Large volume three-dimensional electron microscopy and immunofluorescence imaging reveal that ISGs are much more abundant in the absence of HID-1. We further demonstrate that HID-1 deficiency prevented secretory granule maturation by blocking homotypic fusion of immature secretory granules. Our data identify a novel player during the early maturation of immature secretory granules.
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Affiliation(s)
- Wen Du
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Maoge Zhou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Wei Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Dongwan Cheng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Lifen Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jingze Lu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Eli Song
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Wei Feng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yanhong Xue
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Pingyong Xu
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.,Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Tao Xu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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34
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Bennet H, Mollet IG, Balhuizen A, Medina A, Nagorny C, Bagge A, Fadista J, Ottosson-Laakso E, Vikman P, Dekker-Nitert M, Eliasson L, Wierup N, Artner I, Fex M. Serotonin (5-HT) receptor 2b activation augments glucose-stimulated insulin secretion in human and mouse islets of Langerhans. Diabetologia 2016; 59:744-54. [PMID: 26733006 DOI: 10.1007/s00125-015-3847-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 12/04/2015] [Indexed: 12/22/2022]
Abstract
AIMS/HYPOTHESIS The Gq-coupled 5-hydroxytryptamine 2B (5-HT2B) receptor is known to regulate the proliferation of islet beta cells during pregnancy. However, the role of serotonin in the control of insulin release is still controversial. The aim of the present study was to explore the role of the 5-HT2B receptor in the regulation of insulin secretion in mouse and human islets, as well as in clonal INS-1(832/13) cells. METHODS Expression of HTR2B mRNA and 5-HT2B protein was examined with quantitative real-time PCR, RNA sequencing and immunohistochemistry. α-Methyl serotonin maleate salt (AMS), a serotonin receptor agonist, was employed for robust 5-HT2B receptor activation. Htr2b was silenced with small interfering RNA in INS-1(832/13) cells. Insulin secretion, Ca(2+) response and oxygen consumption rate were determined. RESULTS Immunohistochemistry revealed that 5-HT2B is expressed in human and mouse islet beta cells. Activation of 5-HT2B receptors by AMS enhanced glucose-stimulated insulin secretion (GSIS) in human and mouse islets as well as in INS-1(832/13) cells. Silencing Htr2b in INS-1(832/13) cells led to a 30% reduction in GSIS. 5-HT2B receptor activation produced robust, regular and sustained Ca(2+) oscillations in mouse islets with an increase in both peak distance (period) and time in the active phase as compared with control. Enhanced insulin secretion and Ca(2+) changes induced by AMS coincided with an increase in oxygen consumption in INS-1(832/13) cells. CONCLUSIONS/INTERPRETATION Activation of 5-HT2B receptors stimulates GSIS in beta cells by triggering downstream changes in cellular Ca(2+) flux that enhance mitochondrial metabolism. Our findings suggest that serotonin and the 5-HT2B receptor stimulate insulin release.
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Affiliation(s)
- Hedvig Bennet
- Lund University Diabetes Centre, Department of Clinical Sciences, Unit of Diabetes and Celiac disease, Clinical Research Centre, Jan Waldenströms gata 35, Clinical Research Centre House 91:10, Skåne University Hospital Malmö, SE-20502, Malmö, Sweden.
| | - Inês G Mollet
- Lund University Diabetes Centre, Islet Cell Exocytosis, Malmö, Sweden
| | - Alexander Balhuizen
- Lund University Diabetes Centre, Department of Clinical Sciences, Unit of Diabetes and Celiac disease, Clinical Research Centre, Jan Waldenströms gata 35, Clinical Research Centre House 91:10, Skåne University Hospital Malmö, SE-20502, Malmö, Sweden
| | - Anya Medina
- Lund University Diabetes Centre, Department of Clinical Sciences, Unit of Diabetes and Celiac disease, Clinical Research Centre, Jan Waldenströms gata 35, Clinical Research Centre House 91:10, Skåne University Hospital Malmö, SE-20502, Malmö, Sweden
| | - Cecilia Nagorny
- Lund University Diabetes Centre, Molecular Metabolism, Malmö, Sweden
| | - Annika Bagge
- Lund University Diabetes Centre, Molecular Metabolism, Malmö, Sweden
| | - Joao Fadista
- Lund University Diabetes Centre, Diabetes and Endocrinology, Malmö, Sweden
| | | | - Petter Vikman
- Lund University Diabetes Centre, Diabetes and Endocrinology, Malmö, Sweden
| | - Marloes Dekker-Nitert
- Lund University Diabetes Centre, Diabetes and Endocrinology, Malmö, Sweden
- Royal Brisbane Clinical School, UQ Centre for Clinical Research, The University of Queensland, Herston, QLD, Australia
| | - Lena Eliasson
- Lund University Diabetes Centre, Islet Cell Exocytosis, Malmö, Sweden
| | - Nils Wierup
- Lund University Diabetes Centre, Neuroendocrine Cell Biology, Malmö, Sweden
| | - Isabella Artner
- Lund University Diabetes Centre, Stem Cell Center, Biomedical Centre (BMC), Lund, Sweden
| | - Malin Fex
- Lund University Diabetes Centre, Department of Clinical Sciences, Unit of Diabetes and Celiac disease, Clinical Research Centre, Jan Waldenströms gata 35, Clinical Research Centre House 91:10, Skåne University Hospital Malmö, SE-20502, Malmö, Sweden
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35
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Rulifson IC, Cao P, Miao L, Kopecky D, Huang L, White RD, Samayoa K, Gardner J, Wu X, Chen K, Tsuruda T, Homann O, Baribault H, Yamane H, Carlson T, Wiltzius J, Li Y. Identification of Human Islet Amyloid Polypeptide as a BACE2 Substrate. PLoS One 2016; 11:e0147254. [PMID: 26840340 PMCID: PMC4739698 DOI: 10.1371/journal.pone.0147254] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 01/03/2016] [Indexed: 11/19/2022] Open
Abstract
Pancreatic amyloid formation by islet amyloid polypeptide (IAPP) is a hallmark pathological feature of type 2 diabetes. IAPP is stored in the secretory granules of pancreatic beta-cells and co-secreted with insulin to maintain glucose homeostasis. IAPP is innocuous under homeostatic conditions but imbalances in production or processing of IAPP may result in homodimer formation leading to the rapid production of cytotoxic oligomers and amyloid fibrils. The consequence is beta-cell dysfunction and the accumulation of proteinaceous plaques in and around pancreatic islets. Beta-site APP-cleaving enzyme 2, BACE2, is an aspartyl protease commonly associated with BACE1, a related homolog responsible for amyloid processing in the brain and strongly implicated in Alzheimer's disease. Herein, we identify two distinct sites of the mature human IAPP sequence that are susceptible to BACE2-mediated proteolytic activity. The result of proteolysis is modulation of human IAPP fibrillation and human IAPP protein degradation. These results suggest a potential therapeutic role for BACE2 in type 2 diabetes-associated hyperamylinaemia.
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Affiliation(s)
- Ingrid C. Rulifson
- Amgen, Cardiometabolic Disorders, South San Francisco, California, United States of America
| | - Ping Cao
- Amgen, Molecular Structure and Characterization, South San Francisco, California, United States of America
| | - Li Miao
- Amgen, Cardiometabolic Disorders, South San Francisco, California, United States of America
| | - David Kopecky
- Amgen, Medicinal Chemistry, Thousand Oaks, California, United States of America
| | - Linda Huang
- Amgen, Molecular Structure and Characterization, South San Francisco, California, United States of America
| | - Ryan D. White
- Amgen, Medicinal Chemistry, Cambridge, Massachusetts, United States of America
| | - Kim Samayoa
- Amgen, Pathology, South San Francisco, California, United States of America
| | - Jonitha Gardner
- Amgen, Cardiometabolic Disorders, South San Francisco, California, United States of America
| | - Xiaosu Wu
- Amgen, Cardiometabolic Disorders, South San Francisco, California, United States of America
| | - Kui Chen
- Amgen, Discovery Technologies, Thousand Oaks, California, United States of America
| | - Trace Tsuruda
- Amgen, Biologics, Thousand Oaks, California, United States of America
| | - Oliver Homann
- Amgen, Genome Analysis Unit, South San Francisco, California, United States of America
| | - Helene Baribault
- Amgen, Cardiometabolic Disorders, South San Francisco, California, United States of America
| | - Harvey Yamane
- Amgen, Biologics, Thousand Oaks, California, United States of America
| | - Tim Carlson
- Amgen, Pharmacokinetics and Drug Metabolism, South San Francisco, California, United States of America
| | - Jed Wiltzius
- Amgen, Genome Analysis Unit, South San Francisco, California, United States of America
| | - Yang Li
- Amgen, Cardiometabolic Disorders, South San Francisco, California, United States of America
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36
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Rivillas-Acevedo L, Sánchez-López C, Amero C, Quintanar L. Structural Basis for the Inhibition of Truncated Islet Amyloid Polypeptide Aggregation by Cu(II): Insights into the Bioinorganic Chemistry of Type II Diabetes. Inorg Chem 2015; 54:3788-96. [DOI: 10.1021/ic502945k] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Lina Rivillas-Acevedo
- Departamento de Química, Centro de Investigación y de Estudios Avanzados (Cinvestav), México, D.F., México
- Centro de Investigaciones Químicas,
Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos México
| | - Carolina Sánchez-López
- Departamento de Química, Centro de Investigación y de Estudios Avanzados (Cinvestav), México, D.F., México
| | - Carlos Amero
- Centro de Investigaciones Químicas,
Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos México
| | - Liliana Quintanar
- Departamento de Química, Centro de Investigación y de Estudios Avanzados (Cinvestav), México, D.F., México
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37
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Inhibition of IAPP aggregation by insulin depends on the insulin oligomeric state regulated by zinc ion concentration. Sci Rep 2015; 5:8240. [PMID: 25649462 PMCID: PMC4316164 DOI: 10.1038/srep08240] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 01/12/2015] [Indexed: 12/14/2022] Open
Abstract
While islet amyloid polypeptide (IAPP) aggregation is associated with β-cell death in type-II diabetes (T2D), environmental elements of β-cell granules — e.g. high concentrations of insulin and Zn2+ — inhibit IAPP aggregation in healthy individuals. The inhibition by insulin is experimentally known, but the role of Zn2+ is controversial as both correlations and anti-correlations at the population level are observed between T2D risk and the activity of a β-cell specific zinc ion transporter, ZnT8. Since Zn2+ concentration determines insulin oligomer equilibrium, we computationally investigated interactions of IAPP with different insulin oligomers and compared with IAPP homodimer formation. We found that IAPP binding with insulin oligomers competes with the formation of both higher-molecular-weight insulin oligomers and IAPP homodimers. Therefore, zinc deficiency due to loss-of-function ZnT8 mutations shifts insulin oligomer equilibrium toward zinc-free monomers and dimers, which bind IAPP monomers more efficiently compared to zinc-bound hexamers. The hetero-molecular complex formation prevents IAPP from self-association and subsequent aggregation, reducing T2D risk.
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38
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Distribution Profile of Inositol 1,4,5-Trisphosphate Receptor/Ca2+ Channels in α and β Cells of Pancreas: Dominant Localization in Secretory Granules and Common Error in Identification of Secretory Granule Membranes. Pancreas 2015; 44:158-65. [PMID: 25222134 DOI: 10.1097/mpa.0000000000000224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES The α and β cells of pancreatic islet release important hormones in response to intracellular Ca increases that result from Ca releases through the inositol 1,4,5-trisphoshate receptor (IP3R)/Ca channels. Yet no systematic studies on distribution of IP3R/Ca channels have been done, prompting us to investigate the distribution of all 3 IP3R isoforms. METHODS Immunogold electron microscopy was performed to determine the presence and the relative concentrations of all 3 IP3R isoforms in 2 major organelles secretory granules (SGs) and the endoplasmic reticulum of α and β cells of rat pancreas. RESULTS All 3 IP3R isoforms were present in SG membranes of both cells, and the IP3R concentrations in SGs were ∼2-fold higher than those in the endoplasmic reticulum. Moreover, large halos shown in the electron microscope images of insulin-containing SGs of β cells were gap spaces that resulted from separation of granule membranes from the surrounding cytoplasm. CONCLUSIONS These results strongly suggest the important roles of SGs in IP3-induced, Ca-dependent regulatory secretory pathway in pancreas. Moreover, the accurate location of SG membranes of β cells was further confirmed by the location of another integral membrane protein synaptotagmin V and of membrane phospholipid PI(4,5)P2.
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39
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Abstract
Pancreatic β cells contain the highest amount of zinc among cells within the human body, and hence, the relationship between zinc and diabetes has been of great interest. To date, many studies of zinc and diabetes have been reported, including studies demonstrating that diabetic patients and mice have a decreased amount of zinc in the pancreas. Zinc may counteract the deleterious effects of oxidative stress, which contributes to reduced insulin resistance, and may also protect pancreatic β cells from glucolipotoxicity. Recently, we have shown that SLC30A8/zinc transporter 8, which is a transporter expressed on the surface of insulin granules, plays a key role in zinc transport into insulin granules and in the regulation of hepatic insulin clearance. Here, we review the role of zinc in whole-body maintenance and the latest information on the relationship between zinc and diabetes.
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Affiliation(s)
- Motoyuki Tamaki
- Department of Metabolism & Endocrinology, Juntendo University Graduate School of Medicine
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40
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Susa AC, Wu C, Bernstein SL, Dupuis NF, Wang H, Raleigh DP, Shea JE, Bowers MT. Defining the molecular basis of amyloid inhibitors: human islet amyloid polypeptide-insulin interactions. J Am Chem Soc 2014; 136:12912-9. [PMID: 25144879 PMCID: PMC4183647 DOI: 10.1021/ja504031d] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Indexed: 11/28/2022]
Abstract
Human islet amyloid polypeptide (hIAPP or Amylin) is a 37 residue hormone that is cosecreted with insulin from the pancreatic islets. The aggregation of hIAPP plays a role in the progression of type 2 diabetes and contributes to the failure of islet cell grafts. Despite considerable effort, little is known about the mode of action of IAPP amyloid inhibitors, and this has limited rational drug design. Insulin is one of the most potent inhibitors of hIAPP fibril formation, but its inhibition mechanism is not understood. In this study, the aggregation of mixtures of hIAPP with insulin, as well as with the separate A and B chains of insulin, were characterized using ion mobility spectrometry-based mass spectrometry and atomic force microscopy. Insulin and the insulin B chain target the hIAPP monomer in its compact isoform and shift the equilibrium away from its extended isoform, an aggregation-prone conformation, and thus inhibit hIAPP from forming β-sheets and subsequently amyloid fibrils. All-atom molecular modeling supports these conclusions.
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Affiliation(s)
- Anna C. Susa
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Chun Wu
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Summer L. Bernstein
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Nicholas F. Dupuis
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Hui Wang
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Daniel P. Raleigh
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Joan-Emma Shea
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Michael T. Bowers
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
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41
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Li Y, Xu W, Mu Y, Zhang JZH. Acidic pH retards the fibrillization of human Islet Amyloid Polypeptide due to electrostatic repulsion of histidines. J Chem Phys 2014; 139:055102. [PMID: 23927287 DOI: 10.1063/1.4817000] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The human Islet Amyloid Polypeptide (hIAPP) is the major constituent of amyloid deposits in pancreatic islets of type-II diabetes. IAPP is secreted together with insulin from the acidic secretory granules at a low pH of approximately 5.5 to the extracellular environment at a neutral pH. The increased accumulation of extracellular hIAPP in diabetes indicates that changes in pH may promote amyloid formation. To gain insights and underlying mechanisms of the pH effect on hIAPP fibrillogenesis, all-atom molecular dynamics simulations in explicit solvent model were performed to study the structural properties of five hIAPP protofibrillar oligomers, under acidic and neutral pH, respectively. In consistent with experimental findings, simulation results show that acidic pH is not conducive to the structural stability of these oligomers. This provides a direct evidence for a recent experiment [L. Khemtemourian, E. Domenech, J. P. F. Doux, M. C. Koorengevel, and J. A. Killian, J. Am. Chem. Soc. 133, 15598 (2011)], which suggests that acidic pH inhibits the fibril formation of hIAPP. In addition, a complementary coarse-grained simulation shows the repulsive electrostatic interactions among charged His18 residues slow down the dimerization process of hIAPP by twofold. Besides, our all-atom simulations reveal acidic pH mainly affects the local structure around residue His18 by destroying the surrounding hydrogen-bonding network, due to the repulsive interactions between protonated interchain His18 residues at acidic pH. It is also disclosed that the local interactions nearby His18 operating between adjacent β-strands trigger the structural transition, which gives hints to the experimental findings that the rate of hIAPP fibril formation and the morphologies of the fibrillar structures are strongly pH-dependent.
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Affiliation(s)
- Yang Li
- State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China
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42
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Squires PE, Jones PM, Younis MYG, Hills CE. The calcium-sensing receptor and β-cell function. VITAMINS AND HORMONES 2014; 95:249-67. [PMID: 24559921 DOI: 10.1016/b978-0-12-800174-5.00010-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
In addition to its central role controlling systemic calcium homeostasis, the extracellular calcium-sensing receptor (CaSR) can be found on multiple cell types not associated with controlling plasma calcium. The endocrine pancreas is one such tissue, and it is apparent that the receptor plays an important role in regulating β-cell function. During exocytosis, divalent cations are coreleased with insulin and their concentration within the restricted intercellular compartments of the pancreatic islet increases sufficiently to activate the CaSR on neighboring cells. Acute and chronic activation of the receptor has multiple effects on the β-cell, from increasing cadherin-based cell-cell adhesion to directly altering the expression and function of various potassium and voltage-dependent calcium channels. The promiscuous activation of multiple binding partners improves cell adhesion, cell coupling, and cell-to-cell communication within the islet and is the basis for the effect of the CaSR on β-cell function and improved glucose responsiveness.
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Affiliation(s)
- Paul E Squires
- School of Life Sciences, University of Warwick, Coventry, United Kingdom.
| | - Peter M Jones
- Diabetes & Nutritional Sciences Division, School of Medicine, King's College London, London, United Kingdom
| | - Mustafa Y G Younis
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Claire E Hills
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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43
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Xu W, Zhang C, Morozova-Roche L, Zhang JZH, Mu Y. pH-dependent conformational ensemble and polymorphism of amyloid-β core fragment. J Phys Chem B 2013; 117:8392-9. [PMID: 23786168 DOI: 10.1021/jp404034x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Characterization of amyloid oligomeric species is important due to its possible responsibility for the toxicity of amyloid proteins, whereas it is difficult to detect by current spectroscopic techniques. The pH-dependent tetramerization and fibrillation of the central hydrophobic segment of Alzheimer amyloid β-peptide (Aβ(12-24)) were respectively explored by all-atom replica exchange molecular dynamics simulations and by fluorescence and atomic force microscopy measurements. Our combined study shows that more β-sheet structures in the early event of tetramerization is linked directly to the high propensity to form amyloid fibrils in the consequent fibrillation. Both tetramerization and fibrillation are strongly regulated by pH. At pH 5.0, Aβ(12-24) has two opposite terminal charges. The electrostatic attraction between the side-chains of His13/His14 and Glu22/Asp23 thus acts as a "pattern keeper", resulting in high propensity of amyloid formation. These results suggest that pH effects most likely by affecting the ionization properties of the Aβ(12-24) peptide. Specifically, the pH-dependent equilibrium conformational distribution of different aggregate species are well-investigated in detail. Our findings also give hints to other experimental findings that the kinetics and morphologies of Aβ fibril formation are strongly pH-dependent.
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Affiliation(s)
- Weixin Xu
- State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China
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44
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Tu LH, Raleigh DP. Role of aromatic interactions in amyloid formation by islet amyloid polypeptide. Biochemistry 2013; 52:333-42. [PMID: 23256729 DOI: 10.1021/bi3014278] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aromatic-aromatic and aromatic-hydrophobic interactions have been proposed to play a role in amyloid formation by a range of polypeptides, including islet amyloid polypeptide (IAPP or amylin). IAPP is responsible for amyloid formation in patients with type 2 diabetes. The polypeptide is 37 residues long and contains three aromatic residues, Phe-15, Phe-23, and Tyr-37. The ability of all single aromatic to leucine mutants, all double aromatic to leucine mutants, and the triple leucine mutant to form amyloid were examined. Amyloid formation was almost twice as rapid for the F15L mutant as for the wild type but was almost 3-fold slower for the Y37L mutant and almost 2-fold slower for the F23L mutant. Amyloid fibrils formed from each of the single mutants were effective at seeding amyloid formation by wild-type IAPP, implying that the fibril structures are similar. The F15L/F23L double mutant has a larger effect than the F15L/Y37L double mutant on the rate of amyloid formation, even though a Y37L substitution has more drastic consequences in the wild-type background than does the F23L mutation, suggesting nonadditive effects between the different sites. The triple leucine mutant and the F23L/Y37L double mutant are the slowest to form amyloid. F15 has been proposed to make important contacts early in the aggregation pathway, but the data for the F15L mutant indicate that they are not optimal. A set of variants containing natural and unnatural amino acids at position 15, which were designed to conserve hydrophobicity, but alter α-helix and β-sheet propensity, were analyzed to determine the properties of this position that control the rate of amyloid formation. There is no correlation between β-sheet propensity at this position and the rate of amyloid formation, but there is a correlation with α-helical propensity.
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Affiliation(s)
- Ling-Hsien Tu
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, USA
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45
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Giebink AW, Vogel PA, Medawala W, Spence DM. C-peptide-stimulated nitric oxide production in a cultured pulmonary artery endothelium is erythrocyte mediated and requires Zn(2+). Diabetes Metab Res Rev 2013; 29:44-52. [PMID: 23007928 DOI: 10.1002/dmrr.2359] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 08/23/2012] [Indexed: 12/13/2022]
Abstract
BACKGROUND C-peptide has been shown to stimulate the production of nitric oxide (NO) in aortic endothelial cells via activation of endothelial nitric oxide synthase (eNOS) through an increased calcium influx. Here, results obtained using cultured bovine pulmonary artery endothelial cells (bPAECs) suggest that C-peptide does not induce eNOS activation directly in cultured pulmonary artery endothelium. However, C-peptide has been shown to stimulate the release of ATP from erythrocytes, a well-documented stimulus of eNOS activity in the pulmonary endothelium. Therefore, studies were performed to examine if C-peptide can indirectly stimulate NO production in a cultured pulmonary endothelium that is erythrocyte mediated. METHODS NO production and free intracellular calcium changes were monitored in immobilized bPAECs using specific intracellular fluorescent probes after stimulation with adenosine triphosphate (ATP), calcium ionophore A23187, or C-peptide. A microfluidic device enabled immobilized bPAECs to interact with flowing erythrocytes in the presence and absence of C-peptide to determine the role of the erythrocyte in C-peptide-stimulated NO production in cultured bPAECs. RESULTS ATP and the calcium ionophore stimulate significant increases in both intracellular NO production and influx of free calcium in cultured bPAECs. In contrast, C-peptide, ranging from physiological to above physiological concentrations, was unable to stimulate NO production or calcium influx in the bPAECs. However, when erythrocytes were pre-incubated with a mixture containing physiological concentrations of C-peptide with Zn(2+) and haemodynamically pumped beneath bPAECs cultured on a microfluidic device, an 88.6 ± 7.5% increase in endothelial NO production was observed. CONCLUSIONS C-peptide does not affect NO production in bPAECs directly but can impact NO production through an erythrocyte-mediated mechanism. Furthermore, in the absence of Zn(2+), C-peptide does not stimulate this NO production directly or indirectly. These results suggest that C-peptide, in the presence of Zn(2+), may be a determinant in purinergic receptor signalling via its ability to stimulate the release of ATP from erythrocytes.
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Affiliation(s)
- Adam W Giebink
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
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Dunkelberger EB, Buchanan LE, Marek P, Cao P, Raleigh DP, Zanni MT. Deamidation accelerates amyloid formation and alters amylin fiber structure. J Am Chem Soc 2012; 134:12658-67. [PMID: 22734583 DOI: 10.1021/ja3039486] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Deamidation of asparagine and glutamine is the most common nonenzymatic, post-translational modification. Deamidation can influence the structure, stability, folding, and aggregation of proteins and has been proposed to play a role in amyloid formation. However there are no structural studies of the consequences of deamidation on amyloid fibers, in large part because of the difficulty of studying these materials using conventional methods. Here we examine the effects of deamidation on the kinetics of amyloid formation by amylin, the causative agent of type 2 diabetes. We find that deamidation accelerates amyloid formation and the deamidated material is able to seed amyloid formation by unmodified amylin. Using site-specific isotope labeling and two-dimensional infrared (2D IR) spectroscopy, we show that fibers formed by samples that contain deamidated polypeptide contain reduced amounts of β-sheet. Deamidation leads to disruption of the N-terminal β-sheet between Ala-8 and Ala-13, but β-sheet is still retained near Leu-16. The C-terminal sheet is disrupted near Leu-27. Analysis of potential sites of deamidation together with structural models of amylin fibers reveals that deamidation in the N-terminal β-sheet region may be the cause for the disruption of the fiber structure at both the N- and C-terminal β-sheet. Thus, deamidation is a post-translational modification that creates fibers that have an altered structure but can still act as a template for amylin aggregation. Deamidation is very difficult to detect with standard methods used to follow amyloid formation, but isotope-labeled IR spectroscopy provides a means for monitoring sample degradation and investigating the structural consequences of deamidation.
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Affiliation(s)
- Emily B Dunkelberger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706-1396, United States
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Figueroa H, Peddi D, Osborne JM, Wilson BM, Pesaru RR, Kurva B, Ramaraju S, Milletti MC, Heyl DL. Modeling the Interface between Islet Amyloid Polypeptide and Insulin-Based Aggregation Inhibitors: Correlation to Aggregation Kinetics and Membrane Damage. J Chem Inf Model 2012; 52:1298-307. [DOI: 10.1021/ci300119c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Hector Figueroa
- Chemistry Department, Eastern Michigan University, Ypsilanti, Michigan 48197, United States
| | - Durgaprasad Peddi
- Chemistry Department, Eastern Michigan University, Ypsilanti, Michigan 48197, United States
| | - Joshua M. Osborne
- Chemistry Department, Eastern Michigan University, Ypsilanti, Michigan 48197, United States
| | - Brenan M. Wilson
- Chemistry Department, Eastern Michigan University, Ypsilanti, Michigan 48197, United States
| | - Ranadheer Reddy Pesaru
- Chemistry Department, Eastern Michigan University, Ypsilanti, Michigan 48197, United States
| | - Balakrishna Kurva
- Chemistry Department, Eastern Michigan University, Ypsilanti, Michigan 48197, United States
| | - Swathi Ramaraju
- Chemistry Department, Eastern Michigan University, Ypsilanti, Michigan 48197, United States
| | - Maria C. Milletti
- Chemistry Department, Eastern Michigan University, Ypsilanti, Michigan 48197, United States
| | - Deborah L. Heyl
- Chemistry Department, Eastern Michigan University, Ypsilanti, Michigan 48197, United States
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Cao P, Raleigh DP. Analysis of the inhibition and remodeling of islet amyloid polypeptide amyloid fibers by flavanols. Biochemistry 2012; 51:2670-83. [PMID: 22409724 DOI: 10.1021/bi2015162] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Islet amyloid polypeptide (IAPP, amylin) is responsible for amyloid formation in type 2 diabetes and in transplanted islets. The flavanol (-)-epigallocatechin-3-gallate [EGCG; (2R,3R)-5,7-dihydroxy-2-(3,4,5-trihydroxyphenyl)-3,4-dihydro-2H-1-benzopyran-3-yl 3,4,5-trihydroxybenzoate] is an effective inhibitor of amyloid formation by IAPP; however, the interactions required for the inhibition of IAPP amyloid formation and for the remodeling of amyloid fibers are not known. A range of features have been proposed to be critical for EGCG protein interactions, including interactions with aromatic residues, interactions with amino groups, or sulfhydryls. Using a set of IAPP analogues, we show that none of these are required. Studies in which EGCG is added to the lag phase of amyloid formation shows that it interacts with intermediates as well as with monomers and amyloid. The features of EGCG required for effective inhibition were examined. The stereoisomer of EGCG, (-)-gallocatechin gallate (GCG), is an effective inhibitor, although less so than EGCG. Removing the gallate ester moiety leads to EGC which is a less effective inhibitor. Removing only the 3-hydroxyl group of the trihydroxyphenyl ring leads to a compound that has more pronounced effects on the lag phase than EGC but is less effective at reducing the amount of amyloid. Elimination of both the 3-hydroxy group and the gallate ester results in loss of activity. EGCG remodels IAPP amyloid fibers but does not fully resolubilize them to unstructured monomers, and the remodeling is not the reverse of amyloid assembly. The ability of the compounds to remodel IAPP amyloid closely follows their relative ability to inhibit amyloid formation.
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Affiliation(s)
- Ping Cao
- Department of Chemistry, Stony Brook University, Nicolls Road Stony Brook, New York 11794-3400, United States
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Brender JR, Salamekh S, Ramamoorthy A. Membrane disruption and early events in the aggregation of the diabetes related peptide IAPP from a molecular perspective. Acc Chem Res 2012; 45:454-62. [PMID: 21942864 DOI: 10.1021/ar200189b] [Citation(s) in RCA: 304] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aggregation of proteins is tightly controlled in living systems, and misfolded proteins are normally removed before aggregation of the misfolded protein can occur. But for reasons not clearly understood, in some individuals this degradation process breaks down, and misfolded proteins accumulate in insoluble protein aggregates (amyloid deposits) over time. Of the many proteins expressed in humans, a small but growing number have been found to form the long, highly ordered β-sheet protein fibers that comprise amyloid deposits. Despite a lack of obvious sequence similarity, the amyloid forms of diverse proteins are strikingly similar, consisting of long, highly ordered insoluble fibers with a characteristic crossed β-sheet pattern. Amyloidogenesis has been the focus of intense basic and clinical research, because a high proportion of amyloidogenic proteins have been linked to common degenerative diseases, including Alzheimer's disease, type II diabetes, and Parkinson's disease. The apparent link between amyloidogenic proteins and disease was initially attributed to the amyloid form of the protein; however, increasing evidence suggests that the toxicity is due to intermediates generated during the assembly of amyloid fibers. These intermediates have been proposed to attack cells in a variety of ways, such as by generating inflammation, creating reactive oxygen species, and overloading the misfolded protein response pathway. One common, well-studied mechanism is the disruption of the plasma and organelle membranes. In this Account, we examine the early molecular-level events in the aggregation of the islet amyloid polypeptide (IAPP, also called amylin) and its ensuing disruption of membranes. IAPP is a 37-residue peptide secreted in conjunction with insulin; it is highly amyloidogenic and often found in amyloid deposits in type II diabetics. IAPP aggregates are highly toxic to the β-cells that produce insulin, and thus IAPP is believed to be one of the factors involved in the transition from early to later stages of type II diabetes. Using variants of IAPP that are combinations of toxic or non-toxic and amyloidogenic or nonamyloidogenic forms, we have shown that formation of amyloid fibers is a sufficient but not necessary condition for the disruption of β-cells. Instead, the ability to induce membrane disruption in model membranes appears to be related to the peptide's ability to stabilize curvature in the membrane, which in turn is related to the depth of penetration in the membrane. Although many similarities exist between IAPP and other amyloidogenic proteins, one important difference appears to be the role of small oligomers in the assembly process of amyloid fibers. In many amyloidogenic proteins, small oligomers form a distinct metastable intermediate that is frequently the most toxic species; however, in IAPP, small oligomers appear to be transient and are rapidly converted to amyloid fibers. Moreover, the aggregation and toxicity of IAPP is controlled by other cofactors present in the secretory granule from which it is released, such as zinc and insulin, in a control mechanism that is somehow unbalanced in type II diabetics. Investigations into this process are likely to give clues to the mysterious origins of type II diabetes at the molecular level.
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Affiliation(s)
- Jeffrey R. Brender
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Samer Salamekh
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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Yoo SH, Hur YS. Enrichment of the inositol 1,4,5-trisphosphate receptor/Ca2+ channels in secretory granules and essential roles of chromogranins. Cell Calcium 2012; 51:342-50. [DOI: 10.1016/j.ceca.2011.12.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 12/07/2011] [Accepted: 12/10/2011] [Indexed: 11/26/2022]
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