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Sisnande T, Brum FL, Matias DO, de Sá Ribeiro F, Moulin TB, Mohana-Borges R, de Magalhães MTQ, Lima LMTR. Spatially resolved distribution of pancreatic hormones proteoforms by MALDI-imaging mass spectrometry. Anal Biochem 2024; 692:115570. [PMID: 38763320 DOI: 10.1016/j.ab.2024.115570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 05/09/2024] [Accepted: 05/13/2024] [Indexed: 05/21/2024]
Abstract
Zinc plays a crucial role both in the immune system and endocrine processes. Zinc restriction in the diet has been shown to lead to degeneration of the endocrine pancreas, resulting in hormonal imbalance within the β-cells. Proteostasismay vary depending on the stage of a pathophysiological process, which underscores the need for tools aimed at directly analyzing biological status. Among proteomics methods, MALDI-ToF-MS can serve as a rapid peptidomics tool for analyzing extracts or by histological imaging. Here we report the optimization of MALDI imaging mass spectrometry analysis of histological thin sections from mouse pancreas. This optimization enables the identification of the major islet peptide hormones as well as the major accumulated precursors and/or proteolytic products of peptide hormones. Cross-validation of the identified peptide hormones was performed by LC-ESI-MS from pancreatic islet extracts. Mice subjected to a zinc-restricted diet exhibited a relatively lower amount of peptide intermediates compared to the control group. These findings provide evidence for a complex modulation of proteostasis by micronutrients imbalance, a phenomenon directly accessed by MALDI-MSI.
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Affiliation(s)
- Tháyna Sisnande
- Laboratório de Biotecnologia Farmacêutica (pbiotech), Faculdade de Farmácia, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil; Programa de Pós-Graduação Em Química Biológica, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil.
| | - Felipe Lopes Brum
- Laboratório de Biotecnologia e Bioengenharia Estrutural (LABGENEST), Instituto de Biofísica Carlos Chagas Filho (IBCCF), Rio de Janeiro, RJ, 21941-902, Brazil.
| | - Daiane O Matias
- Laboratório de Biotecnologia Farmacêutica (pbiotech), Faculdade de Farmácia, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil; Programa de Pós-Graduação Em Química Biológica, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil.
| | - Fernando de Sá Ribeiro
- Laboratório de Biotecnologia Farmacêutica (pbiotech), Faculdade de Farmácia, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil; Programa de Pós-Graduação Em Química Biológica, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil.
| | - Thayana Beninatto Moulin
- Laboratório de Biotecnologia Farmacêutica (pbiotech), Faculdade de Farmácia, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil.
| | - Ronaldo Mohana-Borges
- Laboratório de Biotecnologia e Bioengenharia Estrutural (LABGENEST), Instituto de Biofísica Carlos Chagas Filho (IBCCF), Rio de Janeiro, RJ, 21941-902, Brazil; Centro de Espectrometria de Massa de Biomoléculas (CEMBIO), Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil.
| | - Mariana T Q de Magalhães
- Laboratório de Biofísica de Macromoléculas (LBM), Instituto de Ciências Biomédicas (ICB), Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil.
| | - Luís Maurício T R Lima
- Laboratório de Biotecnologia Farmacêutica (pbiotech), Faculdade de Farmácia, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil; Programa de Pós-Graduação Em Química Biológica, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil; Programa de Pós-Graduação Em Ciências Farmacêuticas, Faculdade de Farmácia, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil.
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2
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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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3
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Groegler J, Callebaut A, James EA, Delong T. The insulin secretory granule is a hotspot for autoantigen formation in type 1 diabetes. Diabetologia 2024; 67:1507-1516. [PMID: 38811417 DOI: 10.1007/s00125-024-06164-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 03/11/2024] [Indexed: 05/31/2024]
Abstract
In type 1 diabetes, the insulin-producing beta cells of the pancreas are destroyed through the activity of autoreactive T cells. In addition to strong and well-documented HLA class II risk haplotypes, type 1 diabetes is associated with noncoding polymorphisms within the insulin gene locus. Furthermore, autoantibody prevalence data and murine studies implicate insulin as a crucial autoantigen for the disease. Studies identify secretory granules, where proinsulin is processed into mature insulin, stored and released in response to glucose stimulation, as a source of antigenic epitopes and neoepitopes. In this review, we integrate established concepts, including the role that susceptible HLA and thymic selection of the T cell repertoire play in setting the stage for autoimmunity, with emerging insights about beta cell and insulin secretory granule biology. In particular, the acidic, peptide-rich environment of secretory granules combined with its array of enzymes generates a distinct proteome that is unique to functional beta cells. These factors converge to generate non-templated peptide sequences that are recognised by autoreactive T cells. Although unanswered questions remain, formation and presentation of these epitopes and the resulting immune responses appear to be key aspects of disease initiation. In addition, these pathways may represent important opportunities for therapeutic intervention.
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Affiliation(s)
- Jason Groegler
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Aïsha Callebaut
- Center for Translational Immunology, Benaroya Research Institute, Seattle, WA, USA
| | - Eddie A James
- Center for Translational Immunology, Benaroya Research Institute, Seattle, WA, USA
| | - Thomas Delong
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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4
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Zhang S, Fu C, Luo Y, Xie Q, Xu T, Sun Z, Su Z, Zhou X. Cryo-EM structure of a eukaryotic zinc transporter at a low pH suggests its Zn 2+-releasing mechanism. J Struct Biol 2023; 215:107926. [PMID: 36464198 DOI: 10.1016/j.jsb.2022.107926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 11/10/2022] [Accepted: 11/28/2022] [Indexed: 12/04/2022]
Abstract
Zinc transporter 8 (ZnT8) is mainly expressed in pancreatic islet β cells and is responsible for H+-coupled uptake (antiport) of Zn2+ into the lumen of insulin secretory granules. Structures of human ZnT8 and its prokaryotic homolog YiiP have provided structural basis for constructing a plausible transport cycle for Zn2+. However, the mechanistic role that protons play in the transport process remains unclear. Here we present a lumen-facing cryo-EM structure of ZnT8 from Xenopus tropicalis (xtZnT8) in the presence of Zn2+ at a luminal pH (5.5). Compared to a Zn2+-bound xtZnT8 structure at a cytosolic pH (7.5), the low-pH structure displays an empty transmembrane Zn2+-binding site with a disrupted coordination geometry. Combined with a Zn2+-binding assay our data suggest that protons may disrupt Zn2+ coordination at the transmembrane Zn2+-binding site in the lumen-facing state, thus facilitating Zn2+ release from ZnT8 into the lumen.
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Affiliation(s)
- Senfeng Zhang
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Chunting Fu
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Yongbo Luo
- The State Key Laboratory of Biotherapy, Department of Geriatrics and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Qingrong Xie
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Tong Xu
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Ziyi Sun
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
| | - Zhaoming Su
- The State Key Laboratory of Biotherapy, Department of Geriatrics and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
| | - Xiaoming Zhou
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
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5
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Ho KH, Jayathilake A, Yagan M, Nour A, Osipovich AB, Magnuson MA, Gu G, Kaverina I. CAMSAP2 localizes to the Golgi in islet β-cells and facilitates Golgi-ER trafficking. iScience 2023; 26:105938. [PMID: 36718359 PMCID: PMC9883185 DOI: 10.1016/j.isci.2023.105938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 12/07/2022] [Accepted: 01/04/2023] [Indexed: 01/09/2023] Open
Abstract
Glucose stimulation induces the remodeling of microtubules, which potentiates insulin secretion in pancreatic β-cells. CAMSAP2 binds to microtubule minus ends to stabilize microtubules in several cultured clonal cells. Here, we report that the knockdown of CAMSAP2 in primary β-cells reduces total insulin content and attenuates GSIS without affecting the releasability of insulin vesicles. Surprisingly, CAMSAP2 knockdown does not change microtubule stability. Unlike in cultured insulinoma cells, CAMSAP2 in primary β-cells predominantly localizes to the Golgi apparatus instead of microtubule minus ends. This novel localization is specific to primary β- but not α-cells and is independent of microtubule binding. Consistent with its specific localization at the Golgi, CAMSAP2 promotes efficient Golgi-ER trafficking in primary β-cells. Moreover, primary β-cells and insulinoma cells likely express different CAMSAP2 isoforms. We propose that a novel CAMSAP2 isoform in primary β-cells has a non-canonical function, which promotes Golgi-ER trafficking to support efficient production of insulin and secretion.
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Affiliation(s)
- Kung-Hsien Ho
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Anissa Jayathilake
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Mahircan Yagan
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Aisha Nour
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Anna B. Osipovich
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Mark A. Magnuson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Guoqiang Gu
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Irina Kaverina
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
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Crawford SA, Wiles TA, Wenzlau JM, Powell RL, Barbour G, Dang M, Groegler J, Barra JM, Burnette KS, Hohenstein AC, Baker RL, Tse HM, Haskins K, Delong T. Cathepsin D Drives the Formation of Hybrid Insulin Peptides Relevant to the Pathogenesis of Type 1 Diabetes. Diabetes 2022; 71:2793-2803. [PMID: 36041196 PMCID: PMC9750942 DOI: 10.2337/db22-0303] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 08/24/2022] [Indexed: 01/11/2023]
Abstract
Hybrid insulin peptides (HIPs) form in pancreatic β-cells through the formation of peptide bonds between proinsulin fragments and other peptides. HIPs have been identified in pancreatic islets by mass spectrometry and are targeted by CD4 T cells in patients with type 1 diabetes (T1D) as well as by pathogenic CD4 T-cell clones in nonobese diabetic (NOD) mice. The mechanism of HIP formation is currently poorly understood; however, it is well established that proteases can drive the formation of new peptide bonds in a side reaction during peptide bond hydrolysis. Here, we used a proteomic strategy on enriched insulin granules and identified cathepsin D (CatD) as the primary protease driving the specific formation of HIPs targeted by disease-relevant CD4 T cells in T1D. We also established that NOD islets deficient in cathepsin L (CatL), another protease implicated in the formation of disease-relevant HIPs, contain elevated levels of HIPs, indicating a role for CatL in the proteolytic degradation of HIPs. In summary, our data suggest that CatD may be a therapeutic target in efforts to prevent or slow the autoimmune destruction of β-cells mediated by HIP-reactive CD4 T cells in T1D.
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Affiliation(s)
- Samantha A Crawford
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Timothy A Wiles
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Janet M Wenzlau
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Roger L Powell
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Gene Barbour
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Mylinh Dang
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jason Groegler
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jessie M Barra
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL
| | - KaLia S Burnette
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL
| | - Anita C Hohenstein
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Rocky L Baker
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Hubert M Tse
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL
| | - Kathryn Haskins
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Thomas Delong
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO
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7
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Mathiesen DS, Lund A, Holst JJ, Knop FK, Lutz TA, Bagger JI. THERAPY OF ENDOCRINE DISEASE: Amylin and calcitonin - physiology and pharmacology. Eur J Endocrinol 2022; 186:R93-R111. [PMID: 35353712 DOI: 10.1530/eje-21-1261] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 03/30/2022] [Indexed: 11/08/2022]
Abstract
Type 2 diabetes is a common manifestation of metabolic dysfunction due to obesity and constitutes a major burden for modern health care systems, in concert with the alarming rise in obesity worldwide. In recent years, several successful pharmacotherapies improving glucose metabolism have emerged and some of these also promote weight loss, thus, ameliorating insulin resistance. However, the progressive nature of type 2 diabetes is not halted by these new anti-diabetic pharmacotherapies. Therefore, novel therapies promoting weight loss further and delaying diabetes progression are needed. Amylin, a beta cell hormone, has satiating properties and also delays gastric emptying and inhibits postprandial glucagon secretion with the net result of reducing postprandial glucose excursions. Amylin acts through the six amylin receptors, which share the core component with the calcitonin receptor. Calcitonin, derived from thyroid C cells, is best known for its role in humane calcium metabolism, where it inhibits osteoclasts and reduces circulating calcium. However, calcitonin, particularly of salmon origin, has also been shown to affect insulin sensitivity, reduce the gastric emptying rate and promote satiation. Preclinical trials with agents targeting the calcitonin receptor and the amylin receptors, show improvements in several parameters of glucose metabolism including insulin sensitivity and some of these agents are currently undergoing clinical trials. Here, we review the physiological and pharmacological effects of amylin and calcitonin and discuss the future potential of amylin and calcitonin-based treatments for patients with type 2 diabetes and obesity.
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Affiliation(s)
- David S Mathiesen
- Center for Clinical Metabolic Research, Gentofte Hospital, Hellerup, Denmark
| | - Asger Lund
- Center for Clinical Metabolic Research, Gentofte Hospital, Hellerup, Denmark
- Department of Medicine, Gentofte and Herlev Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Filip K Knop
- Center for Clinical Metabolic Research, Gentofte Hospital, Hellerup, Denmark
- Department of Medicine, Gentofte and Herlev Hospital, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Steno Diabetes Center Copenhagen, Gentofte, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas A Lutz
- Institute of Veterinary Physiology, Vetsuisse-Faculty, University of Zurich, Zurich, Switzerland
| | - Jonatan I Bagger
- Center for Clinical Metabolic Research, Gentofte Hospital, Hellerup, Denmark
- Department of Medicine, Gentofte and Herlev Hospital, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Steno Diabetes Center Copenhagen, Gentofte, Denmark
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8
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He X, Ewing AG. Simultaneous Counting of Molecules in the Halo and Dense-Core of Nanovesicles by Regulating Dynamics of Vesicle Opening. Angew Chem Int Ed Engl 2022; 61:e202116217. [PMID: 35129861 PMCID: PMC9306628 DOI: 10.1002/anie.202116217] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Indexed: 01/09/2023]
Abstract
We report the discovery that in the presence of chaotropic anions (SCN- ) the opening of nanometer biological vesicles at an electrified interface often becomes a two-step process (around 30 % doublet peaks). We have then used this to independently count molecules in each subvesicular compartment, the halo and protein dense-core, and the fraction of catecholamine binding to the dense-core is 68 %. Moreover, we differentiated two distinct populations of large dense-core vesicles (LDCVs) and quantified their content, which might correspond to immature (43 %) and mature (30 %) LDCVs, to reveal differences in their biogenesis. We speculate this is caused by an increase in the electrostatic attraction between protonated catecholamine and the negatively charged dense-core following adsorption of SCN- .
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Affiliation(s)
- Xiulan He
- Department of Chemistry and Molecular BiologyUniversity of GothenburgKemivägen 1041296GothenburgSweden
| | - Andrew G. Ewing
- Department of Chemistry and Molecular BiologyUniversity of GothenburgKemivägen 1041296GothenburgSweden
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9
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He X, Ewing AG. Simultaneous Counting of Molecules in the Halo and Dense‐Core of Nanovesicles by Regulating Dynamics of Vesicle Opening. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202116217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Xiulan He
- Department of Chemistry and Molecular Biology University of Gothenburg Kemivägen 10 41296 Gothenburg Sweden
| | - Andrew G. Ewing
- Department of Chemistry and Molecular Biology University of Gothenburg Kemivägen 10 41296 Gothenburg Sweden
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10
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Gaus B, Brüning D, Groß S, Müller M, Rustenbeck I. The changing view of insulin granule mobility: From conveyor belt to signaling hub. Front Endocrinol (Lausanne) 2022; 13:983152. [PMID: 36120467 PMCID: PMC9478610 DOI: 10.3389/fendo.2022.983152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 08/11/2022] [Indexed: 11/28/2022] Open
Abstract
Before the advent of TIRF microscopy the fate of the insulin granule prior to secretion was deduced from biochemical investigations, electron microscopy and electrophysiological measurements. Since Calcium-triggered granule fusion is indisputably necessary to release insulin into the extracellular space, much effort was directed to the measure this event at the single granule level. This has also been the major application of the TIRF microscopy of the pancreatic beta cell when it became available about 20 years ago. To better understand the metabolic modulation of secretion, we were interested to characterize the entirety of the insulin granules which are localized in the vicinity of the plasma membrane to identify the characteristics which predispose to fusion. In this review we concentrate on how the description of granule mobility in the submembrane space has evolved as a result of progress in methodology. The granules are in a state of constant turnover with widely different periods of residence in this space. While granule fusion is associated +with prolonged residence and decreased lateral mobility, these characteristics may not only result from binding to the plasma membrane but also from binding to the cortical actin web, which is present in the immediate submembrane space. While granule age as such affects granule mobility and fusion probability, the preceding functional states of the beta cell leave their mark on these parameters, too. In summary, the submembrane granules form a highly dynamic heterogeneous population and contribute to the metabolic memory of the beta cells.
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Affiliation(s)
- Bastian Gaus
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Braunschweig, Germany
| | - Dennis Brüning
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Braunschweig, Germany
| | - Sofie Groß
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Braunschweig, Germany
| | - Michael Müller
- Institute of Dynamics and Vibrations, Technische Universität Braunschweig, Braunschweig, Germany
| | - Ingo Rustenbeck
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Braunschweig, Germany
- *Correspondence: Ingo Rustenbeck,
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11
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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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12
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Germanos M, Gao A, Taper M, Yau B, Kebede MA. Inside the Insulin Secretory Granule. Metabolites 2021; 11:metabo11080515. [PMID: 34436456 PMCID: PMC8401130 DOI: 10.3390/metabo11080515] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/03/2021] [Accepted: 08/03/2021] [Indexed: 12/19/2022] Open
Abstract
The pancreatic β-cell is purpose-built for the production and secretion of insulin, the only hormone that can remove glucose from the bloodstream. Insulin is kept inside miniature membrane-bound storage compartments known as secretory granules (SGs), and these specialized organelles can readily fuse with the plasma membrane upon cellular stimulation to release insulin. Insulin is synthesized in the endoplasmic reticulum (ER) as a biologically inactive precursor, proinsulin, along with several other proteins that will also become members of the insulin SG. Their coordinated synthesis enables synchronized transit through the ER and Golgi apparatus for congregation at the trans-Golgi network, the initiating site of SG biogenesis. Here, proinsulin and its constituents enter the SG where conditions are optimized for proinsulin processing into insulin and subsequent insulin storage. A healthy β-cell is continually generating SGs to supply insulin in vast excess to what is secreted. Conversely, in type 2 diabetes (T2D), the inability of failing β-cells to secrete may be due to the limited biosynthesis of new insulin. Factors that drive the formation and maturation of SGs and thus the production of insulin are therefore critical for systemic glucose control. Here, we detail the formative hours of the insulin SG from the luminal perspective. We do this by mapping the journey of individual members of the SG as they contribute to its genesis.
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13
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Wasana Jayaweera S, Surano S, Pettersson N, Oskarsson E, Lettius L, Gharibyan AL, Anan I, Olofsson A. Mechanisms of Transthyretin Inhibition of IAPP Amyloid Formation. Biomolecules 2021; 11:biom11030411. [PMID: 33802170 PMCID: PMC8001701 DOI: 10.3390/biom11030411] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/04/2021] [Indexed: 12/18/2022] Open
Abstract
Amyloid-formation by the islet amyloid polypeptide (IAPP), produced by the β-cells in the human pancreas, has been associated with the development of type II diabetes mellitus (T2DM). The human plasma-protein transthyretin (TTR), a well-known amyloid-inhibiting protein, is interestingly also expressed within the IAPP producing β-cells. In the present study, we have characterized the ability of TTR to interfere with IAPP amyloid-formation, both in terms of its intrinsic stability as well as with regard to the effect of TTR-stabilizing drugs. The results show that TTR can prolong the lag-phase as well as impair elongation in the course of IAPP-amyloid formation. We also show that the interfering ability correlates inversely with the thermodynamic stability of TTR, while no such correlation was observed as a function of kinetic stability. Furthermore, we demonstrate that the ability of TTR to interfere is maintained also at the low pH environment within the IAPP-containing granules of the pancreatic β-cells. However, at both neutral and low pH, the addition of TTR-stabilizing drugs partly impaired its efficacy. Taken together, these results expose mechanisms of TTR-mediated inhibition of IAPP amyloid-formation and highlights a potential therapeutic target to prevent the onset of T2DM.
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Affiliation(s)
- Sanduni Wasana Jayaweera
- Department of Medical Biochemistry and Biophysics, Umeå University, 901 87 Umeå, Sweden; (S.W.J.); (S.S.); (N.P.); (E.O.); (L.L.); (A.L.G.)
| | - Solmaz Surano
- Department of Medical Biochemistry and Biophysics, Umeå University, 901 87 Umeå, Sweden; (S.W.J.); (S.S.); (N.P.); (E.O.); (L.L.); (A.L.G.)
| | - Nina Pettersson
- Department of Medical Biochemistry and Biophysics, Umeå University, 901 87 Umeå, Sweden; (S.W.J.); (S.S.); (N.P.); (E.O.); (L.L.); (A.L.G.)
| | - Elvira Oskarsson
- Department of Medical Biochemistry and Biophysics, Umeå University, 901 87 Umeå, Sweden; (S.W.J.); (S.S.); (N.P.); (E.O.); (L.L.); (A.L.G.)
| | - Lovisa Lettius
- Department of Medical Biochemistry and Biophysics, Umeå University, 901 87 Umeå, Sweden; (S.W.J.); (S.S.); (N.P.); (E.O.); (L.L.); (A.L.G.)
| | - Anna L. Gharibyan
- Department of Medical Biochemistry and Biophysics, Umeå University, 901 87 Umeå, Sweden; (S.W.J.); (S.S.); (N.P.); (E.O.); (L.L.); (A.L.G.)
| | - Intissar Anan
- Wallenberg Centre for Molecular Medicine, Umeå University, 901 87 Umeå, Sweden;
| | - Anders Olofsson
- Department of Medical Biochemistry and Biophysics, Umeå University, 901 87 Umeå, Sweden; (S.W.J.); (S.S.); (N.P.); (E.O.); (L.L.); (A.L.G.)
- Correspondence: ; Tel.: +46-70-354-3301
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14
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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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15
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Chen H, Victor AK, Klein J, Tacer KF, Tai DJ, de Esch C, Nuttle A, Temirov J, Burnett LC, Rosenbaum M, Zhang Y, Ding L, Moresco JJ, Diedrich JK, Yates JR, Tillman HS, Leibel RL, Talkowski ME, Billadeau DD, Reiter LT, Potts PR. Loss of MAGEL2 in Prader-Willi syndrome leads to decreased secretory granule and neuropeptide production. JCI Insight 2020; 5:138576. [PMID: 32879135 PMCID: PMC7526459 DOI: 10.1172/jci.insight.138576] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/22/2020] [Indexed: 12/17/2022] Open
Abstract
Prader-Willi syndrome (PWS) is a developmental disorder caused by loss of maternally imprinted genes on 15q11-q13, including melanoma antigen gene family member L2 (MAGEL2). The clinical phenotypes of PWS suggest impaired hypothalamic neuroendocrine function; however, the exact cellular defects are unknown. Here, we report deficits in secretory granule (SG) abundance and bioactive neuropeptide production upon loss of MAGEL2 in humans and mice. Unbiased proteomic analysis of Magel2pΔ/m+ mice revealed a reduction in components of SG in the hypothalamus that was confirmed in 2 PWS patient-derived neuronal cell models. Mechanistically, we show that proper endosomal trafficking by the MAGEL2-regulated WASH complex is required to prevent aberrant lysosomal degradation of SG proteins and reduction of mature SG abundance. Importantly, loss of MAGEL2 in mice, NGN2-induced neurons, and human patients led to reduced neuropeptide production. Thus, MAGEL2 plays an important role in hypothalamic neuroendocrine function, and cellular defects in this pathway may contribute to PWS disease etiology. Moreover, these findings suggest unanticipated approaches for therapeutic intervention.
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Affiliation(s)
- Helen Chen
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - A Kaitlyn Victor
- Department of Neurology, Department of Pediatrics, and Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Jonathon Klein
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Klementina Fon Tacer
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Derek Jc Tai
- Center for Genomic Medicine, Department of Neurology, Department of Pathology, and Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Neurology, Harvard Medical School, Boston, Massachusetts, USA.,Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute, Cambridge, Massachusetts, USA
| | - Celine de Esch
- Center for Genomic Medicine, Department of Neurology, Department of Pathology, and Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Neurology, Harvard Medical School, Boston, Massachusetts, USA.,Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute, Cambridge, Massachusetts, USA
| | - Alexander Nuttle
- Center for Genomic Medicine, Department of Neurology, Department of Pathology, and Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Neurology, Harvard Medical School, Boston, Massachusetts, USA.,Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute, Cambridge, Massachusetts, USA
| | - Jamshid Temirov
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Lisa C Burnett
- Levo Therapeutics, Inc., Skokie, Illinois, USA.,Division of Molecular Genetics, Department of Pediatrics, and Naomi Berrie Diabetes Center, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
| | - Michael Rosenbaum
- Division of Molecular Genetics, Department of Pediatrics, and Naomi Berrie Diabetes Center, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
| | - Yiying Zhang
- Division of Molecular Genetics, Department of Pediatrics, and Naomi Berrie Diabetes Center, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
| | - Li Ding
- Division of Oncology Research and Schulze Center for Novel Therapeutics, Mayo Clinic, Rochester, Minnesota, USA
| | - James J Moresco
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, USA
| | - Jolene K Diedrich
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, USA
| | - John R Yates
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, USA
| | - Heather S Tillman
- Veterinary Pathology Core, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Rudolph L Leibel
- Division of Molecular Genetics, Department of Pediatrics, and Naomi Berrie Diabetes Center, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
| | - Michael E Talkowski
- Center for Genomic Medicine, Department of Neurology, Department of Pathology, and Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Neurology, Harvard Medical School, Boston, Massachusetts, USA.,Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute, Cambridge, Massachusetts, USA
| | - Daniel D Billadeau
- Division of Oncology Research and Schulze Center for Novel Therapeutics, Mayo Clinic, Rochester, Minnesota, USA
| | - Lawrence T Reiter
- Department of Neurology, Department of Pediatrics, and Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Patrick Ryan Potts
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
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16
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Röder C, Kupreichyk T, Gremer L, Schäfer LU, Pothula KR, Ravelli RBG, Willbold D, Hoyer W, Schröder GF. Cryo-EM structure of islet amyloid polypeptide fibrils reveals similarities with amyloid-β fibrils. Nat Struct Mol Biol 2020; 27:660-667. [PMID: 32541895 DOI: 10.1101/2020.02.11.944546] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/30/2020] [Indexed: 05/18/2023]
Abstract
Amyloid deposits consisting of fibrillar islet amyloid polypeptide (IAPP) in pancreatic islets are associated with beta-cell loss and have been implicated in type 2 diabetes (T2D). Here, we applied cryo-EM to reconstruct densities of three dominant IAPP fibril polymorphs, formed in vitro from synthetic human IAPP. An atomic model of the main polymorph, built from a density map of 4.2-Å resolution, reveals two S-shaped, intertwined protofilaments. The segment 21-NNFGAIL-27, essential for IAPP amyloidogenicity, forms the protofilament interface together with Tyr37 and the amidated C terminus. The S-fold resembles polymorphs of Alzheimer's disease (AD)-associated amyloid-β (Aβ) fibrils, which might account for the epidemiological link between T2D and AD and reports on IAPP-Aβ cross-seeding in vivo. The results structurally link the early-onset T2D IAPP genetic polymorphism (encoding Ser20Gly) with the AD Arctic mutation (Glu22Gly) of Aβ and support the design of inhibitors and imaging probes for IAPP fibrils.
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Affiliation(s)
- Christine Röder
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tatsiana Kupreichyk
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Lothar Gremer
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Luisa U Schäfer
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
| | - Karunakar R Pothula
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
| | - Raimond B G Ravelli
- The Multimodal Molecular Imaging Institute, Maastricht University, Maastricht, the Netherlands
| | - Dieter Willbold
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Wolfgang Hoyer
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany.
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany.
- Institut für Physikalische Biologie, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
| | - Gunnar F Schröder
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany.
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany.
- Physics Department, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
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17
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Cryo-EM structure of islet amyloid polypeptide fibrils reveals similarities with amyloid-β fibrils. Nat Struct Mol Biol 2020; 27:660-667. [PMID: 32541895 DOI: 10.1038/s41594-020-0442-4] [Citation(s) in RCA: 111] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/30/2020] [Indexed: 01/09/2023]
Abstract
Amyloid deposits consisting of fibrillar islet amyloid polypeptide (IAPP) in pancreatic islets are associated with beta-cell loss and have been implicated in type 2 diabetes (T2D). Here, we applied cryo-EM to reconstruct densities of three dominant IAPP fibril polymorphs, formed in vitro from synthetic human IAPP. An atomic model of the main polymorph, built from a density map of 4.2-Å resolution, reveals two S-shaped, intertwined protofilaments. The segment 21-NNFGAIL-27, essential for IAPP amyloidogenicity, forms the protofilament interface together with Tyr37 and the amidated C terminus. The S-fold resembles polymorphs of Alzheimer's disease (AD)-associated amyloid-β (Aβ) fibrils, which might account for the epidemiological link between T2D and AD and reports on IAPP-Aβ cross-seeding in vivo. The results structurally link the early-onset T2D IAPP genetic polymorphism (encoding Ser20Gly) with the AD Arctic mutation (Glu22Gly) of Aβ and support the design of inhibitors and imaging probes for IAPP fibrils.
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18
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Zhang J, Tan J, Pei R, Ye S. Acidic Environment Significantly Alters Aggregation Pathway of Human Islet Amyloid Polypeptide at Negative Lipid Membrane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1530-1537. [PMID: 31995712 DOI: 10.1021/acs.langmuir.9b03623] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The misfolding and aggregation of human islet amyloid polypeptide (hIAPP) at cell membrane has a close relationship with the development of type 2 diabetes (T2DM). This aggregation process is susceptible to various physiologically related factors, and systematic studies on condition-mediated hIAPP aggregation are therefore essential for a thorough understanding of the pathology of T2DM. In this study, we combined surface-sensitive amide I and amide II spectral signals from the protein backbone, generated simultaneously in a highly sensitive femtosecond broad-band sum frequency generation vibrational spectroscopy system, to examine the effect of environmental pH on the dynamical structural changes of hIAPP at membrane surface in situ and in real time. Such a combination can directly discriminate the formation of β-hairpin-like monomer and oligomer/fibril at the membrane surface. It is evident that, in an acidic milieu, hIAPP slows down its conformational evolution and alters its aggregation pathway, leading to the formation of off-pathway oligomers. When matured hIAPP aggregates are exposed to basic subphase, partial conversion from β-sheet oligomers into ordered β-sheet fibrillar structures is observed. When exposed to acidic environment, however, hIAPP fibrils partially converse into more loosely patterned β-sheet oligomeric structures.
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Affiliation(s)
- Jiahui Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Junjun Tan
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Ruoqi Pei
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Shuji Ye
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
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19
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Abstract
Mounting evidence implicates hybrid insulin peptides (HIPs) as important autoantigens in the development of type 1 diabetes (T1D). These fusion peptides formed between insulin and other pancreatic beta cell-derived peptides contain non-genomically encoded amino acid sequences, making them plausible targets for autoreactive T cells in T1D. HIPs are detectable by mass spectrometry in human and murine islets and are targeted by diabetes-inducing T cells in non-obese diabetic mice as well as by T cells isolated from the residual pancreatic islets of human organ donors with T1D. The discovery of HIPs comes with numerous new challenges, as well as opportunities to study the pathogenesis of T1D. Here we review the original discovery of HIPs and describe recent studies investigating the role of HIP-reactive T cells in the development of diabetes. We also discuss potential mechanisms that may be responsible for the generation of HIPs in beta cells and describe challenges that need to be addressed in the field of mass spectrometry to enable the discovery of new HIPs. The identification of these potentially disease-driving antigens in T1D is of key interest to the field as it may provide new tools to predict, prevent and potentially reverse the disease.
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Affiliation(s)
- T A Wiles
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz, Aurora, CO, USA
| | - T Delong
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz, Aurora, CO, USA
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20
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Protein Nanofibrils as Storage Forms of Peptide Drugs and Hormones. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1174:265-290. [PMID: 31713202 DOI: 10.1007/978-981-13-9791-2_8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Amyloids are highly organized cross β-sheet protein nanofibrils that are associated with both diseases and functions. Thermodynamically amyloids are stable structures as they represent the lowest free energy state that proteins can attain. However, recent studies suggest that amyloid fibrils can be dissociated by a change in environmental parameters such as pH and ionic strength. This reversibility of amyloids can not only be associated with disease, but function as well. In disease-associated amyloids, fibrils can act as reservoirs of cytotoxic oligomers. Recently, in higher organisms such as mammals, hormones were found to be stored in amyloid-like state, where these were reported to act as a reservoir of functional monomers. These hormone amyloids can dissociate to monomers upon release from the secretory granules, and subsequently bind to their respective receptors and perform their functions. In this book chapter, we describe in detail how these protein nanofibrils represent the densest possible peptide packing and are suitable for long-term storage. Thus, mimicking the feature of amyloids to release functional monomers, it is possible to formulate amyloid-based peptide/protein drugs, which can be used for sustained release.
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21
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Kotuniak R, Fra̧czyk T, Skrobecki P, Płonka D, Bal W. Gly-His-Thr-Asp-Amide, an Insulin-Activating Peptide from the Human Pancreas Is a Strong Cu(II) but a Weak Zn(II) Chelator. Inorg Chem 2018; 57:15507-15516. [DOI: 10.1021/acs.inorgchem.8b02841] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Radosław Kotuniak
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Tomasz Fra̧czyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
- Department of Immunology, Transplantology and Internal Medicine, Medical University of Warsaw, Nowogrodzka 59, 02-006 Warsaw, Poland
| | - Piotr Skrobecki
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Dawid Płonka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Wojciech Bal
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
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22
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Press-Sandler O, Miller Y. Molecular mechanisms of membrane-associated amyloid aggregation: Computational perspective and challenges. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1889-1905. [DOI: 10.1016/j.bbamem.2018.03.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/07/2018] [Accepted: 03/12/2018] [Indexed: 01/02/2023]
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23
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Ilitchev AI, Giammona MJ, Olivas C, Claud SL, Lazar Cantrell KL, Wu C, Buratto SK, Bowers MT. Hetero-oligomeric Amyloid Assembly and Mechanism: Prion Fragment PrP(106-126) Catalyzes the Islet Amyloid Polypeptide β-Hairpin. J Am Chem Soc 2018; 140:9685-9695. [PMID: 29989407 DOI: 10.1021/jacs.8b05925] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Protein aggregation is typically attributed to the association of homologous amino acid sequences between monomers of the same protein. Coaggregation of heterogeneous peptide species can occur, however, and is implicated in the proliferation of seemingly unrelated protein diseases in the body. The prion protein fragment (PrP106-126) and human islet amyloid polypeptide (hIAPP) serve as an interesting model of nonhomologous protein assembly as they coaggregate, despite a lack of sequence homology. We have applied ion-mobility mass spectrometry, atomic force microscopy, circular dichroism, and high-level molecular modeling to elucidate this important assembly process. We found that the prion fragment not only forms pervasive hetero-oligomeric aggregates with hIAPP but also promotes the transition of hIAPP into its amyloidogenic β-hairpin conformation. Further, when PrP106-126 was combined with non-amyloidogenic rIAPP, the two formed nearly identical hetero-oligomers to those seen with hIAPP, despite rIAPP containing β-sheet breaking proline substitutions. Additionally, while rIAPP does not natively form the amyloidogenic β-hairpin structure, it did so in the presence of PrP106-126 and underwent a conformational transition to β-sheet in solution. We also find that PrP106-126 forms hetero-oligomers with the IAPP8-20 fragment but not with the "aggregation hot spot" IAPP20-29 fragment. PrP106-126 apparently induces IAPP into a β-hairpin structure within the PrP:IAPP heterodimer complex and then, through ligand exchange, catalytically creates the amyloidogenic β-hairpin dimer of IAPP in significantly greater abundance than IAPP does on its own. This is a new mechanistic model that provides a critical foundation for the detailed study of hetero-oligomerization and prion-like proliferation in amyloid systems.
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Affiliation(s)
- Alexandre I Ilitchev
- Department of Chemistry and Biochemistry , University of California , Santa Barbara , California 93106 , United States
| | - Maxwell J Giammona
- Department of Chemistry and Biochemistry , University of California , Santa Barbara , California 93106 , United States
| | - Carina Olivas
- Department of Chemistry and Biochemistry , Rowan University , Glassboro , New Jersey 08028 , United States
| | - Sarah L Claud
- Department of Chemistry , Westmont College , Santa Barbara , California 93108 , United States
| | - Kristi L Lazar Cantrell
- Department of Chemistry , Westmont College , Santa Barbara , California 93108 , United States
| | - Chun Wu
- Department of Chemistry and Biochemistry , Rowan University , Glassboro , New Jersey 08028 , United States
| | - Steven K Buratto
- 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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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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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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26
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Christensen M, Skeby KK, Schiøtt B. Identification of Key Interactions in the Initial Self-Assembly of Amylin in a Membrane Environment. Biochemistry 2017; 56:4884-4894. [PMID: 28786287 DOI: 10.1021/acs.biochem.7b00344] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Islet amyloid polypeptide, also known as amylin, forms aggregates that reduce the amount of insulin-producing cells in patients with type II diabetes mellitus. Much remains unknown about the process of aggregation and cytotoxicity, but it is known that certain cell membrane components can alter the rate of aggregation. Using atomistic molecular dynamics simulations combined with the highly mobile membrane mimetic model incorporating enhanced sampling of lipid diffusion, we investigate interaction of amylin peptides with the membrane components as well as the self-assembly of amylin. Consistent with experimental evidence, we find that an initial membrane-bound α-helical state folds into stable β-sheet structures upon self-assembly. Our results suggest the following mechanism for the initial phase of amylin self-assembly. The peptides move around on the membrane with the positively charged N-terminus interacting with the negatively charged lipid headgroups. When the peptides start to interact, they partly unfold and break some of the contacts with the membrane. The initial interactions between the peptides are dominated by aromatic and hydrophobic interactions. Oligomers are formed showing both intra- and interpeptide β-sheets, initially with interactions mainly in the C-terminal domain of the peptides. Decreasing the pH to 5.5 is known to inhibit amyloid formation. At low pH, His18 is protonated, adding a fourth positive charge at the peptide. With His18 protonated, no oligomerization is observed in the simulations. The additional charge gives a strong midpoint anchoring of the peptides to negatively charged membrane components, and the peptides experience additional interpeptide repulsion, thereby preventing interactions.
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Affiliation(s)
- Mikkel Christensen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark.,Sino-Danish Center for Education and Research , Beijing, China
| | - Katrine K Skeby
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark
| | - Birgit Schiøtt
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark
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27
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Palivec V, Viola CM, Kozak M, Ganderton TR, Křížková K, Turkenburg JP, Haluŝková P, Žáková L, Jiráĉek J, Jungwirth P, Brzozowski AM. Computational and structural evidence for neurotransmitter-mediated modulation of the oligomeric states of human insulin in storage granules. J Biol Chem 2017; 292:8342-8355. [PMID: 28348075 PMCID: PMC5437240 DOI: 10.1074/jbc.m117.775924] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/23/2017] [Indexed: 11/23/2022] Open
Abstract
Human insulin is a pivotal protein hormone controlling metabolism, growth, and aging and whose malfunctioning underlies diabetes, some cancers, and neurodegeneration. Despite its central position in human physiology, the in vivo oligomeric state and conformation of insulin in its storage granules in the pancreas are not known. In contrast, many in vitro structures of hexamers of this hormone are available and fall into three conformational states: T6, T3Rf3, and R6 As there is strong evidence for accumulation of neurotransmitters, such as serotonin and dopamine, in insulin storage granules in pancreatic β-cells, we probed by molecular dynamics (MD) and protein crystallography (PC) if these endogenous ligands affect and stabilize insulin oligomers. Parallel studies independently converged on the observation that serotonin binds well within the insulin hexamer (site I), stabilizing it in the T3R3 conformation. Both methods indicated serotonin binding on the hexamer surface (site III) as well. MD, but not PC, indicated that dopamine was also a good site III ligand. Some of the PC studies also included arginine, which may be abundant in insulin granules upon processing of pro-insulin, and stable T3R3 hexamers loaded with both serotonin and arginine were obtained. The MD and PC results were supported further by in solution spectroscopic studies with R-state-specific chromophore. Our results indicate that the T3R3 oligomer is a plausible insulin pancreatic storage form, resulting from its complex interplay with neurotransmitters, and pro-insulin processing products. These findings may have implications for clinical insulin formulations.
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Affiliation(s)
- Vladimír Palivec
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Cristina M Viola
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Mateusz Kozak
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Timothy R Ganderton
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Květoslava Křížková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Johan P Turkenburg
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Petra Haluŝková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Jiří Jiráĉek
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic.
| | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic.
| | - Andrzej M Brzozowski
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom.
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28
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Skeby KK, Andersen OJ, Pogorelov TV, Tajkhorshid E, Schiøtt B. Conformational Dynamics of the Human Islet Amyloid Polypeptide in a Membrane Environment: Toward the Aggregation Prone Form. Biochemistry 2016; 55:2031-42. [PMID: 26953503 PMCID: PMC5733697 DOI: 10.1021/acs.biochem.5b00507] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human islet amyloid polypeptide (hIAPP) is a 37-residue peptide hormone, which upon misfolding changes from the physiologically active monomer into pathological amyloid fibril aggregates in the pancreas of type 2 diabetes mellitus patients. During this process, the insulin-producing pancreatic β-cells are damaged; however, the underlying mechanism of this mode of cytotoxicity remains elusive. It is known that anionic lipids accelerate amyloid fibril formation, implicating the importance of the cellular membrane in the process, and that a pH close to the level in the β-cell secretory granules (pH 5.5) inhibits amyloid fibril formation. Using all-atom molecular dynamics simulations, we have investigated the membrane-associated monomer state of α-helical hIAPP, analyzed specific interactions of hIAPP with a mixed anionic-zwitterionic lipid membrane and examined the influence of pH on the structure and dynamics of hIAPP and its interaction with the membrane. We find that hIAPP primarily interacts with the membrane by forming favorable interactions between anionic lipids and the positively charged residues in the N-terminal part of the peptide. Rationalizing experimental findings, the simulations show that the N-terminal part of the peptide interacts with the membrane in the lipid headgroup region. At neutral pH, the C-terminal part of the peptide, which contains the residues that initiate fibril formation, displays a highly dynamic, unfolded state, which interacts with the membrane significantly less than the N-terminal part. Such an unfolded form can be proposed to contribute to the acceleration of fibril formation. At low pH, protonation of His18 mediates a stronger interaction of the C-terminal part with the membrane, resulting in the immobilization of the C-terminal part on the membrane surface that might constitute a mechanism by which low pH inhibits fibril formation.
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Affiliation(s)
- Katrine Kirkeby Skeby
- Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary Nanoscience Center (iNANO) and the Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus, Denmark
| | - Ole Juul Andersen
- Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary Nanoscience Center (iNANO) and the Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus, Denmark
| | - Taras V. Pogorelov
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Birgit Schiøtt
- Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary Nanoscience Center (iNANO) and the Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus, Denmark
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29
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Pithadia A, Brender JR, Fierke CA, Ramamoorthy A. Inhibition of IAPP Aggregation and Toxicity by Natural Products and Derivatives. J Diabetes Res 2016; 2016:2046327. [PMID: 26649317 PMCID: PMC4662995 DOI: 10.1155/2016/2046327] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 04/15/2015] [Indexed: 01/10/2023] Open
Abstract
Fibrillar aggregates of human islet amyloid polypeptide, hIAPP, a pathological feature seen in some diabetes patients, are a likely causative agent for pancreatic beta-cell toxicity, leading to a transition from a state of insulin resistance to type II diabetes through the loss of insulin producing beta-cells by hIAPP induced toxicity. Because of the probable link between hIAPP and the development of type II diabetes, there has been strong interest in developing reagents to study the aggregation of hIAPP and possible therapeutics to block its toxic effects. Natural products are a class of compounds with interesting pharmacological properties against amyloids which have made them interesting targets to study hIAPP. Specifically, the ability of polyphenolic natural products, EGCG, curcumin, and resveratrol, to modulate the aggregation of hIAPP is discussed. Furthermore, we have outlined possible mechanistic discoveries of the interaction of these small molecules with the peptide and how they may mitigate toxicity associated with peptide aggregation. These abundantly found agents have been long used to combat diseases for many years and may serve as useful templates toward developing therapeutics against hIAPP aggregation and toxicity.
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Affiliation(s)
- Amit Pithadia
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Jeffrey R. Brender
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Carol A. Fierke
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
- *Ayyalusamy Ramamoorthy:
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30
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Akter R, Cao P, Noor H, Ridgway Z, Tu LH, Wang H, Wong AG, Zhang X, Abedini A, Schmidt AM, Raleigh DP. Islet Amyloid Polypeptide: Structure, Function, and Pathophysiology. J Diabetes Res 2015; 2016:2798269. [PMID: 26649319 PMCID: PMC4662979 DOI: 10.1155/2016/2798269] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/24/2015] [Indexed: 01/29/2023] Open
Abstract
The hormone islet amyloid polypeptide (IAPP, or amylin) plays a role in glucose homeostasis but aggregates to form islet amyloid in type-2 diabetes. Islet amyloid formation contributes to β-cell dysfunction and death in the disease and to the failure of islet transplants. Recent work suggests a role for IAPP aggregation in cardiovascular complications of type-2 diabetes and hints at a possible role in type-1 diabetes. The mechanisms of IAPP amyloid formation in vivo or in vitro are not understood and the mechanisms of IAPP induced β-cell death are not fully defined. Activation of the inflammasome, defects in autophagy, ER stress, generation of reactive oxygen species, membrane disruption, and receptor mediated mechanisms have all been proposed to play a role. Open questions in the field include the relative importance of the various mechanisms of β-cell death, the relevance of reductionist biophysical studies to the situation in vivo, the molecular mechanism of amyloid formation in vitro and in vivo, the factors which trigger amyloid formation in type-2 diabetes, the potential role of IAPP in type-1 diabetes, the development of clinically relevant inhibitors of islet amyloidosis toxicity, and the design of soluble, bioactive variants of IAPP for use as adjuncts to insulin therapy.
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Affiliation(s)
- Rehana Akter
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Ping Cao
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Harris Noor
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Zachary Ridgway
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Ling-Hsien Tu
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Hui Wang
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Amy G. Wong
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Xiaoxue Zhang
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Andisheh Abedini
- Diabetes Research Program, NYU School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Ann Marie Schmidt
- Diabetes Research Program, NYU School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Daniel P. Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
- Research Department of Structural and Molecule Biology, University College London, Gower Street, London WC1E 6BT, UK
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31
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Rivera-Fuentes P, Wrobel AT, Zastrow ML, Khan M, Georgiou J, Luyben TT, Roder JC, Okamoto K, Lippard SJ. A Far-Red Emitting Probe for Unambiguous Detection of Mobile Zinc in Acidic Vesicles and Deep Tissue. Chem Sci 2015; 6:1944-1948. [PMID: 25815162 PMCID: PMC4372157 DOI: 10.1039/c4sc03388d] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 01/02/2015] [Indexed: 12/12/2022] Open
Abstract
Imaging mobile zinc in acidic environments remains challenging because most small-molecule optical probes display pH-dependent fluorescence. Here we report a reaction-based sensor that detects mobile zinc unambiguously at low pH. The sensor responds reversibly and with a large dynamic range to exogenously applied Zn2+ in lysosomes of HeLa cells, endogenous Zn2+ in insulin granules of MIN6 cells, and zinc-rich mossy fiber boutons in hippocampal tissue from mice. This long-wavelength probe is compatible with the green-fluorescent protein, enabling multicolor imaging, and facilitates visualization of mossy fiber boutons at depths of >100 µm, as demonstrated by studies in live tissue employing two-photon microscopy.
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Affiliation(s)
- Pablo Rivera-Fuentes
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA .
| | - Alexandra T. Wrobel
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA .
| | - Melissa L. Zastrow
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA .
| | - Mustafa Khan
- Lunenfeld-Tanenbaum Research Institute , Mount Sinai Hospital , Toronto , ON M5G 1X5 , Canada
| | - John Georgiou
- Lunenfeld-Tanenbaum Research Institute , Mount Sinai Hospital , Toronto , ON M5G 1X5 , Canada
| | - Thomas T. Luyben
- Lunenfeld-Tanenbaum Research Institute , Mount Sinai Hospital , Toronto , ON M5G 1X5 , Canada
- Department of Molecular Genetics , Faculty of Medicine , University of Toronto , Toronto , ON M5S 1A8 , Canada
| | - John C. Roder
- Lunenfeld-Tanenbaum Research Institute , Mount Sinai Hospital , Toronto , ON M5G 1X5 , Canada
- Department of Molecular Genetics , Faculty of Medicine , University of Toronto , Toronto , ON M5S 1A8 , Canada
| | - Kenichi Okamoto
- Lunenfeld-Tanenbaum Research Institute , Mount Sinai Hospital , Toronto , ON M5G 1X5 , Canada
- Department of Molecular Genetics , Faculty of Medicine , University of Toronto , Toronto , ON M5S 1A8 , Canada
| | - Stephen J. Lippard
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA .
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32
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Blanco EH, Peinado JR, Martín MG, Lindberg I. Biochemical and cell biological properties of the human prohormone convertase 1/3 Ser357Gly mutation: a PC1/3 hypermorph. Endocrinology 2014; 155:3434-47. [PMID: 24932808 PMCID: PMC4138575 DOI: 10.1210/en.2013-2151] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Satiety and appetite signaling are accomplished by circulating peptide hormones. These peptide hormones require processing from larger precursors to become bioactive, often by the proprotein convertase 1/3 (PC1/3). Several subcellular maturation steps are necessary for PC1/3 to achieve its optimal enzymatic activity. Certain PC1/3 variants found in the general population slightly attenuate its enzymatic activity and are associated with obesity and diabetes. However, mutations that increase PC1/3 activity and/or affect its specificity could also have physiological consequences. We here present data showing that the known human Ser357Gly PC1/3 mutant (PC1/3(S357G)) represents a PC1/3 hypermorph. Conditioned media from human embryonic kidney-293 cells transfected with PC1/3(WT) and PC1/3(S357G) were collected and enzymatic activity characterized. PC1/3(S357G) exhibited a lower calcium dependence; a higher pH optimum (neutral); and a higher resistance to peptide inhibitors than the wild-type enzyme. PC1/3(S357G) exhibited increased cleavage to the C-terminally truncated form, and kinetic parameters of the full-length and truncated mutant enzymes were also altered. Lastly, the S357G mutation broadened the specificity of the enzyme; we detected PC2-like specificity on the substrate proCART, the precursor of the cocaine- and amphetamine regulated transcript neuropeptide known to be associated with obesity. The production of another anorexigenic peptide normally synthesized only by PC2, αMSH, was increased when proopiomelanocortin was coexpressed with PC1/3(S357G). Considering the aberrant enzymatic profile of PC1/3(S357G), we hypothesize that this enzyme possesses unusual processing activity that may significantly change the profile of circulating peptide hormones.
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Affiliation(s)
- Elias H Blanco
- Department of Anatomy and Neurobiology (E.H.B., J.R.P., I.L.), University of Maryland Medical School, Baltimore, Maryland 21201; and Department of Pediatrics (M.G.M.), Division of Gastroenterology and Nutrition, Mattel Children's Hospital and the David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095
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33
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Fujita-Yoshigaki J, Matsuki-Fukushima M, Yokoyama M, Katsumata-Kato O. The sorting mechanism underlying the separation of salivary proteins into secretory granules in parotid glands. J Oral Biosci 2014. [DOI: 10.1016/j.job.2014.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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34
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Cao P, Marek P, Noor H, Patsalo V, Tu LH, Wang H, Abedini A, Raleigh DP. Islet amyloid: from fundamental biophysics to mechanisms of cytotoxicity. FEBS Lett 2013; 587:1106-18. [PMID: 23380070 DOI: 10.1016/j.febslet.2013.01.046] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/22/2013] [Accepted: 01/23/2013] [Indexed: 12/21/2022]
Abstract
Pancreatic islet amyloid is a characteristic feature of type 2 diabetes. The major protein component of islet amyloid is the polypeptide hormone known as islet amyloid polypeptide (IAPP, or amylin). IAPP is stored with insulin in the β-cell secretory granules and is released in response to the stimuli that lead to insulin secretion. IAPP is normally soluble and is natively unfolded in its monomeric state, but forms islet amyloid in type 2 diabetes. Islet amyloid is not the cause of type 2 diabetes, but it leads to β-cell dysfunction and cell death, and contributes to the failure of islet cell transplantation. The mechanism of IAPP amyloid formation is not understood and the mechanisms of cytotoxicity are not fully defined.
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Affiliation(s)
- Ping Cao
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
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Sutton KA, Jungnickel MK, Jovine L, Florman HM. Evolution of the voltage sensor domain of the voltage-sensitive phosphoinositide phosphatase VSP/TPTE suggests a role as a proton channel in eutherian mammals. Mol Biol Evol 2012; 29:2147-55. [PMID: 22396523 DOI: 10.1093/molbev/mss083] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The voltage-sensitive phosphoinositide phosphatases provide a mechanism to couple changes in the transmembrane electrical potential to intracellular signal transduction pathways. These proteins share a domain architecture that is conserved in deuterostomes. However, gene duplication events in primates, including humans, give rise to the paralogs TPTE and TPTE2 that retain protein domain organization but, in the case of TPTE, have lost catalytic activity. Here, we present evidence that these human proteins contain a functional voltage sensor, similar to that in nonmammalian orthologs. However, domains of these human proteins can also generate a noninactivating outward current that is not observed in zebra fish or tunicate orthologs. This outward current has the anticipated characteristics of a voltage-sensitive proton current and is due to the appearance of a single histidine residue in the S4 transmembrane segment of the voltage sensor. Histidine is observed at this position only during the eutherian radiation. Domains from both human paralogs generate proton currents. This apparent gain of proton channel function during the evolution of the TPTE protein family may account for the conservation of voltage sensor domains despite the loss of phosphatase activity in some human paralogs.
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Affiliation(s)
- Keith A Sutton
- Department of Cell Biology, University of Massachusetts Medical School, MA, USA
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Gerbino A, Maiellaro I, Carmone C, Caroppo R, Debellis L, Barile M, Busco G, Colella M. Glucose increases extracellular [Ca2+] in rat insulinoma (INS-1E) pseudoislets as measured with Ca2+-sensitive microelectrodes. Cell Calcium 2012; 51:393-401. [PMID: 22361140 DOI: 10.1016/j.ceca.2012.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 12/29/2011] [Accepted: 01/08/2012] [Indexed: 11/24/2022]
Abstract
Secretory granules of pancreatic β-cells contain high concentrations of Ca2+ ions that are co-released with insulin in the extracellular milieu upon activation of exocytosis. As a consequence, an increase in the extracellular Ca2+ concentration ([Ca2+]ext) in the microenvironment immediately surrounding β-cells should be expected following the exocytotic event. Using Ca2+-selective microelectrodes we show here that both high glucose and non-nutrient insulinotropic agents elicit a reversible increase of [Ca2+]ext within rat insulinoma (INS-1E) β-cells pseudoislets. The glucose-induced increases in [Ca2+]ext are blocked by pretreatment with different Ca2+ channel blockers. Physiological agonists acting as positive or negative modulators of the insulin secretion and drugs known to intersect the secretory machinery at different levels also induce [Ca2+]ext changes as predicted on the basis of their described action on insulin secretion. Finally, the glucose-induced [Ca2+]ext increase is strongly inhibited after disruption of the actin web, indicating that the dynamic [Ca2+]ext changes recorded in INS-1E pseudoislets by Ca2+-selective microelectrodes occur mainly as a consequence of exocytosis of Ca2+-rich granules. In conclusion, our data directly demonstrate that the extracellular spaces surrounding β-cells constitute a restricted domain where Ca2+ is co-released during insulin exocytosis, creating the basis for an autocrine/paracrine cell-to-cell communication system via extracellular Ca2+ sensors.
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Affiliation(s)
- Andrea Gerbino
- Department of Biosciences, Biotechnology and Pharmacological Sciences, University of Bari, Via G. Amendola 165/A, 70126 Bari, Italy.
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Cellular Mechanisms for the Biogenesis and Transport of Synaptic and Dense-Core Vesicles. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 299:27-115. [DOI: 10.1016/b978-0-12-394310-1.00002-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Nanga RPR, Brender JR, Vivekanandan S, Ramamoorthy A. Structure and membrane orientation of IAPP in its natively amidated form at physiological pH in a membrane environment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2337-42. [PMID: 21723249 DOI: 10.1016/j.bbamem.2011.06.012] [Citation(s) in RCA: 210] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 06/09/2011] [Accepted: 06/14/2011] [Indexed: 11/25/2022]
Abstract
Human islet amyloid polypeptide is a hormone coexpressed with insulin by pancreatic beta-cells. For reasons not clearly understood, hIAPP aggregates in type II diabetics to form oligomers that interfere with beta-cell function, eventually leading to the loss of insulin production. The cellular membrane catalyzes the formation of amyloid deposits and is a target of amyloid toxicity through disruption of the membrane's structural integrity. Therefore, there is considerable current interest in solving the 3D structure of this peptide in a membrane environment. NMR experiments could not be directly utilized in lipid bilayers due to the rapid aggregation of the peptide. To overcome this difficulty, we have solved the structure of the naturally occurring peptide in detergent micelles at a neutral pH. The structure has an overall kinked helix motif, with residues 7-17 and 21-28 in a helical conformation, and with a 3(10) helix from Gly 33-Asn 35. In addition, the angle between the N- and C-terminal helices is constrained to 85°. The greater helical content of human IAPP in the amidated versus free acid form is likely to play a role in its aggregation and membrane disruptive activity.
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Abstract
Gut microbiota is an assortment of microorganisms inhabiting the length and width of the mammalian gastrointestinal tract. The composition of this microbial community is host specific, evolving throughout an individual's lifetime and susceptible to both exogenous and endogenous modifications. Recent renewed interest in the structure and function of this "organ" has illuminated its central position in health and disease. The microbiota is intimately involved in numerous aspects of normal host physiology, from nutritional status to behavior and stress response. Additionally, they can be a central or a contributing cause of many diseases, affecting both near and far organ systems. The overall balance in the composition of the gut microbial community, as well as the presence or absence of key species capable of effecting specific responses, is important in ensuring homeostasis or lack thereof at the intestinal mucosa and beyond. The mechanisms through which microbiota exerts its beneficial or detrimental influences remain largely undefined, but include elaboration of signaling molecules and recognition of bacterial epitopes by both intestinal epithelial and mucosal immune cells. The advances in modeling and analysis of gut microbiota will further our knowledge of their role in health and disease, allowing customization of existing and future therapeutic and prophylactic modalities.
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Affiliation(s)
- Inna Sekirov
- Michael Smith Laboratories, Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
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Abstract
ATP is released from pancreatic acini in response to cholinergic and hormonal stimulation. The same stimuli cause exocytosis of ZG (zymogen granules) and release of digestive enzymes. The aim of the present study was to determine whether ZG stored ATP and to characterize the uptake mechanism for ATP transport into the ZG. ZG were isolated and the ATP content was measured using luciferin/luciferase assays and was related to protein in the sample. The estimate of ATP concentration in freshly isolated granules was 40-120 microM. The ATP uptake had an apparent Km value of 4.9+/-2.1 mM when granules were incubated without Mg2+ and a Km value of 0.47+/-0.05 mM in the presence of Mg2+, both in pH 6.0 buffers. The uptake of ATP was significantly higher at pH 7.2 compared with pH 6.0 solutions. The anion transport blockers DIDS (4,4'-di-isothiocyanostilbene-2,2'-disulfonate) and Evans Blue inhibited ATP transport. Western blot analysis on the ZG showed the presence of VNUT (vesicular nucleotide transporter). Together, these findings indicate that VNUT may be responsible for the ATP uptake into ZG. Furthermore, the present study shows the presence of ATP together with digestive enzymes in ZG. This indicates that co-released ATP would regulate P2 receptors in pancreatic ducts and, thus, ductal secretion, and this would aid delivery of enzymes to the duodenum.
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Medawala W, McCahill P, Giebink A, Meyer J, Ku CJ, Spence DM. A Molecular Level Understanding of Zinc Activation of C-peptide and its Effects on Cellular Communication in the Bloodstream. Rev Diabet Stud 2009; 6:148-58. [PMID: 20039004 DOI: 10.1900/rds.2009.6.148] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Inspired by previous reports, our group has recently demonstrated that C-peptide exerts beneficial effects upon interactions with red blood cells (RBCs). These effects can be measured in RBCs obtained from animal models of both type 1 diabetes and type 2 diabetes, though to different extents. To date, the key metrics that have been measured involving C-peptide and RBCs include an increase in glucose uptake by these cells and a subsequent increase in adenosine triphosphate (ATP) release. Importantly, to date, our group has only been able to elicit these beneficial effects when the C-peptide is prepared in the presence of Zn2+. The C-peptide-induced release of ATP is of interest when considering that ATP is a purinergic signaling molecule known to stimulate the production of nitric oxide (NO) in the endothelium and in platelets. This NO production has been shown to participate in smooth muscle relaxation and subsequent vessel dilation. Furthermore, NO is a well-established platelet inhibitor. The objective of this review is to provide information pertaining to C-peptide activity on RBCs. Special attention is paid to the necessity of Zn2+ activation, and the origin of that activation in vivo. Finally, a mechanism is proposed that explains how C-peptide is exerting its effects on other cells in the bloodstream, particularly on endothelial cells and platelets, via its ability to stimulate the release of ATP from RBCs.
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Affiliation(s)
- Wathsala Medawala
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
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Deriy LV, Gomez EA, Jacobson DA, Wang X, Hopson JA, Liu XY, Zhang G, Bindokas VP, Philipson LH, Nelson DJ. The granular chloride channel ClC-3 is permissive for insulin secretion. Cell Metab 2009; 10:316-23. [PMID: 19808024 PMCID: PMC2778193 DOI: 10.1016/j.cmet.2009.08.012] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Revised: 07/06/2009] [Accepted: 08/18/2009] [Indexed: 11/29/2022]
Abstract
Insulin secretion from pancreatic beta cells is dependent on maturation and acidification of the secretory granule, processes necessary for prohormone convertase cleavage of proinsulin. Previous studies in isolated beta cells revealed that acidification may be dependent on the granule membrane chloride channel ClC-3, in a step permissive for a regulated secretory response. In this study, immuno-EM of beta cells revealed colocalization of ClC-3 and insulin on secretory granules. Clcn3(-/-) mice as well as isolated islets demonstrate impaired insulin secretion; Clcn3(-/-) beta cells are defective in regulated insulin exocytosis and granular acidification. Increased amounts of proinsulin were found in the majority of secretory granules in the Clcn3(-/-) mice, while in Clcn3(+/+) cells, proinsulin was confined to the immature secretory granules. These results demonstrate that in pancreatic beta cells, chloride channels, specifically ClC-3, are localized on insulin granules and play a role in insulin processing as well as insulin secretion through regulation of granular acidification.
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Affiliation(s)
- Ludmila V Deriy
- Department of Neurobiology, Pharmacology, and Physiology, The University of Chicago, Chicago, IL 60637, USA
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Genetically encoded FRET sensors to monitor intracellular Zn2+ homeostasis. Nat Methods 2009; 6:737-40. [PMID: 19718032 DOI: 10.1038/nmeth.1368] [Citation(s) in RCA: 339] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 07/20/2009] [Indexed: 12/18/2022]
Abstract
We developed genetically encoded fluorescence resonance energy transfer (FRET)-based sensors that display a large ratiometric change upon Zn(2+) binding, have affinities that span the pico- to nanomolar range and can readily be targeted to subcellular organelles. Using this sensor toolbox we found that cytosolic Zn(2+) was buffered at 0.4 nM in pancreatic beta cells, and we found substantially higher Zn(2+) concentrations in insulin-containing secretory vesicles.
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Meyer JA, Subasinghe W, Sima AAF, Keltner Z, Reid GE, Daleke D, Spence DM. Zinc-activated C-peptide resistance to the type 2 diabetic erythrocyte is associated with hyperglycemia-induced phosphatidylserine externalization and reversed by metformin. MOLECULAR BIOSYSTEMS 2009; 5:1157-62. [PMID: 19756305 DOI: 10.1039/b908241g] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Insulin resistance can broadly be defined as the diminished ability of cells to respond to the action of insulin in transporting glucose from the bloodstream into cells and tissues. Here, we report that erythrocytes (ERYs) obtained from type 2 diabetic rats display an apparent resistance to Zn(2+)-activated C-peptide. Thus, the aims of this study were to demonstrate that Zn(2+)-activated C-peptide exerts potentially beneficial effects on healthy ERYs and that these same effects on type 2 diabetic ERYs are enhanced in the presence of metformin. Incubation of ERYs (obtained from type 2 diabetic BBZDR/Wor-rats) with Zn(2+)-activated C-peptide followed by chemiluminescence measurements of ATP resulted in a 31.2 +/- 4.0% increase in ATP release from these ERYs compared to a 78.4 +/- 4.9% increase from control ERYs. Glucose accumulation in diabetic ERYs, measured by scintillation counting of (14)C-labeled glucose, increased by 35.8 +/- 1.3% in the presence of the Zn(2+)-activated C-peptide, a value significantly lower than results obtained from control ERYs (64.3 +/- 5.1%). When Zn(2+)-activated C-peptide was exogenously added to diabetic ERYs, immunoassays revealed a 32.5 +/- 8.2% increase in C-peptide absorbance compared to a 64.4 +/- 10.3% increase in control ERYs. Phosphatidylserine (PS) externalization and metformin sensitization of Zn(2+)-activated C-peptide were examined spectrofluorometrically by measuring the binding of FITC-labeled annexin to PS. The incubation of diabetic ERYs with metformin prior to the addition of Zn(2+)-activated C-peptide resulted in values that were statistically equivalent to those of controls. Summarily, data obtained here demonstrate an apparent resistance to Zn(2+)-activated C-peptide by the ERY that is corrected by metformin.
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Affiliation(s)
- Jennifer A Meyer
- Department of Chemistry, Michigan State University, 229 Chemistry Building, East Lansing, MI 48824, USA
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Hutton JC, Wong R, Davidson HW. Isolation of dense core secretory vesicles from pancreatic endocrine cells by differential and density gradient centrifugation. ACTA ACUST UNITED AC 2009; Chapter 3:Unit 3.32. [PMID: 19283733 DOI: 10.1002/0471143030.cb0332s42] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Methods are presented for the separation of dense core secretory vesicles from insulin-secreting tissues (insulin granules) based on a combination of differential and density gradient centrifugation on various media. Emphasis is given to the use of transplantable tumors, tissue culture cell lines, and pancreatic islets as a tissue source.
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Affiliation(s)
- John C Hutton
- Barbara Davis Center for Childhood Diabetes, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado, USA
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Ravier MA, Tsuboi T, Rutter GA. Imaging a target of Ca2+ signalling: dense core granule exocytosis viewed by total internal reflection fluorescence microscopy. Methods 2008; 46:233-8. [PMID: 18854212 PMCID: PMC2597054 DOI: 10.1016/j.ymeth.2008.09.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2008] [Accepted: 09/12/2008] [Indexed: 12/20/2022] Open
Abstract
Ca2+ ions are the most ubiquitous second messenger found in all cells, and play a significant role in controlling regulated secretion from neurons, endocrine, neuroendocrine and exocrine cells. Here, we describe microscopic techniques to image regulated secretion, a target of Ca2+ signalling. The first of these, total internal reflection fluorescence (TIRF), is well suited for optical sectioning at cell–substrate regions with an unusually thin region of fluorescence excitation (<150 nm). It is thus particularly useful for studies of regulated hormone secretion. A brief summary of this approach is provided, as well as a description of the physical basis for the technique and the tools to implement TIRF using a standard fluorescence microscope. We also detail the different fluorescent probes which can be used to detect secretion and how to analyze the data obtained. A comparison between TIRF and other imaging modalities including confocal and multiphoton microscopy is also included.
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Affiliation(s)
- Magalie A Ravier
- Unit of Endocrinology and Metabolism, University of Louvain Faculty of Medicine, UCL 55.30 Avenue Hippocrate 55, B-1200 Brussels, Belgium
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47
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Knight JD, Williamson JA, Miranker AD. Interaction of membrane-bound islet amyloid polypeptide with soluble and crystalline insulin. Protein Sci 2008; 17:1850-6. [PMID: 18765820 DOI: 10.1110/ps.036350.108] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Islet amyloid polypeptide (IAPP, also known as amylin) is the major protein component of pancreatic amyloid fibers in type II diabetes and is normally cosecreted with insulin from the beta-cells of the pancreas. IAPP forms amyloid fibrils rapidly at concentrations well below those found in vivo, yet progression of type II diabetes occurs over many years. Insulin, a known inhibitor of IAPP fibrillogenesis, exists as a dense crystalline or near-crystalline core in the secretory vesicle, while IAPP localizes to the region between the crystal and the secretory vesicle membrane. In vitro, IAPP fibrillogenesis is both accelerated by lipid membranes and inhibited by monomeric insulin. In this work, we investigate insulin-IAPP-lipid interactions in vitro under conditions chosen to approximate native secretory vesicle physiology and the amyloid disease state. The effect of insulin on IAPP fibrillogenesis is investigated using fluorescence spectrometry. Additionally, interactions of IAPP and lipids with crystalline insulin are studied using fluorescence microscopy. We find that, while soluble states of insulin and IAPP do not interact significantly, large assemblies of either insulin (crystals) or IAPP (fibers) can lead to stable IAPP-insulin interactions. The results raise the possibility of multiple physiological interactions between these two beta-cell hormones.
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Affiliation(s)
- Jefferson D Knight
- Department of Pharmacology, Yale University, New Haven, Connecticut 06520-8066, USA
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Warner JD, Peters CG, Saunders R, Won JH, Betzenhauser MJ, Gunning WT, Yule DI, Giovannucci DR. Visualizing form and function in organotypic slices of the adult mouse parotid gland. Am J Physiol Gastrointest Liver Physiol 2008; 295:G629-40. [PMID: 18669626 PMCID: PMC2536791 DOI: 10.1152/ajpgi.90217.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
An organotypic slice preparation of the adult mouse parotid salivary gland amenable to a variety of optical assessments of fluid and protein secretion dynamics is described. The semi-intact preparation rendered without the use of enzymatic treatment permitted live-cell imaging and multiphoton analysis of cellular and supracellular signals. Toward this end we demonstrated that the parotid slice is a significant addition to the repertoire of tools available to investigators to probe exocrine structure and function since there is currently no cell culture system that fully recapitulates parotid acinar cell biology. Importantly, we show that a subpopulation of the acinar cells of parotid slices can be maintained in short-term culture and retain their morphology and function for up to 2 days. This in vitro model system is a significant step forward compared with enzymatically dispersed acini that rapidly lose their morphological and functional characteristics over several hours, and it was shown to be long enough for the expression and trafficking of exogenous protein following adenoviral infection. This system is compatible with a variety of genetic and physiological approaches used to study secretory function.
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Affiliation(s)
- Jennifer D. Warner
- Department of Neurosciences, University of Toledo College of Medicine, Health Science Campus, Toledo, Ohio; and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - Christian G. Peters
- Department of Neurosciences, University of Toledo College of Medicine, Health Science Campus, Toledo, Ohio; and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - Rudel Saunders
- Department of Neurosciences, University of Toledo College of Medicine, Health Science Campus, Toledo, Ohio; and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - Jong Hak Won
- Department of Neurosciences, University of Toledo College of Medicine, Health Science Campus, Toledo, Ohio; and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - Matthew J. Betzenhauser
- Department of Neurosciences, University of Toledo College of Medicine, Health Science Campus, Toledo, Ohio; and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - William T. Gunning
- Department of Neurosciences, University of Toledo College of Medicine, Health Science Campus, Toledo, Ohio; and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - David I. Yule
- Department of Neurosciences, University of Toledo College of Medicine, Health Science Campus, Toledo, Ohio; and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - David R. Giovannucci
- Department of Neurosciences, University of Toledo College of Medicine, Health Science Campus, Toledo, Ohio; and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
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Bacová Z, Orecná M, Hafko R, Strbák V. Cell swelling-induced signaling for insulin secretion bypasses steps involving G proteins and PLA2 and is N-ethylmaleimide insensitive. Cell Physiol Biochem 2007; 20:387-96. [PMID: 17762166 DOI: 10.1159/000107523] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2007] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND This study was undertaken to examine putative mechanisms of calcium independent signal transduction pathway of cell swelling-induced insulin secretion. METHODS The role of phospholipase A(2), G proteins, and soluble N-ethylmaleimide-sensitive-factor attachment protein receptor (SNARE) in insulin secretion induced by 30% hypotonic medium was studied using isolated rat pancreatic islets. RESULTS In contrast to glucose stimulation, osmotically induced insulin secretion from pancreatic islets was not inhibited by 10 micromol/l bromoenol lactone, an iPLA(2) (Ca(2+) independent phospholipase) inhibitor. Similarly, preincubation of islets for 20 hours with 25 microg/ml mycophenolic acid to inhibit GTP synthesis fully abolished glucose-induced insulin secretion but was without effect on hypotonicity stimulated insulin release. Glucose-induced insulin secretion was prevented by preincubation with 20 nmol/l tetanus toxin (TeTx), a metalloprotease inactivating soluble SNARE. Cell swelling-induced insulin secretion was inhibited by TeTx in the presence of calcium ions but not in calcium depleted medium. The presence of N-ethylmaleimide (NEM, 5 mmol/l, another inhibitor of SNARE proteins) in the medium resulted in high basal insulin secretion and lacking response to glucose stimulation. In contrast, high basal insulin secretion from NEM treated islets further increased after hypotonic stimulation. CONCLUSION G proteins and iPLA(2) - putative mediators of Ca(2+) independent signaling pathway participate in glucose but not in hypotonicity-induced insulin secretion. Hypotonicity-induced insulin secretion is sensitive to clostridial neurotoxin TeTx but is resistant to NEM.
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Affiliation(s)
- Zuzana Bacová
- Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovakia
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50
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Kim T, Gondré-Lewis MC, Arnaoutova I, Loh YP. Dense-core secretory granule biogenesis. Physiology (Bethesda) 2006; 21:124-33. [PMID: 16565478 DOI: 10.1152/physiol.00043.2005] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The dense-core secretory granule is a key organelle for secretion of hormones and neuropeptides in endocrine cells and neurons, in response to stimulation. Cholesterol and granins are critical for the assembly of these organelles at the trans-Golgi network, and their biogenesis is regulated quantitatively by posttranscriptional and posttranslational mechanisms.
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Affiliation(s)
- Taeyoon Kim
- Section on Cellular Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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