1
|
Magnuson MA, Osipovich AB. Ca 2+ signaling and metabolic stress-induced pancreatic β-cell failure. Front Endocrinol (Lausanne) 2024; 15:1412411. [PMID: 39015185 PMCID: PMC11250477 DOI: 10.3389/fendo.2024.1412411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Accepted: 06/10/2024] [Indexed: 07/18/2024] Open
Abstract
Early in the development of Type 2 diabetes (T2D), metabolic stress brought on by insulin resistance and nutrient overload causes β-cell hyperstimulation. Herein we summarize recent studies that have explored the premise that an increase in the intracellular Ca2+ concentration ([Ca2+]i), brought on by persistent metabolic stimulation of β-cells, causes β-cell dysfunction and failure by adversely affecting β-cell function, structure, and identity. This mini-review builds on several recent reviews that also describe how excess [Ca2+]i impairs β-cell function.
Collapse
Affiliation(s)
- Mark A. Magnuson
- Department of Molecular Physiology and Biophysics and Center for Stem Cell Biology, Vanderbilt University, Nashville, TN, United States
| | | |
Collapse
|
2
|
|
3
|
Lee JJ, Yang SY, Park J, Ferrell JE, Shin DH, Lee KJ. Calcium Ion Induced Structural Changes Promote Dimerization of Secretagogin, Which Is Required for Its Insulin Secretory Function. Sci Rep 2017; 7:6976. [PMID: 28765527 PMCID: PMC5539292 DOI: 10.1038/s41598-017-07072-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 06/16/2017] [Indexed: 11/29/2022] Open
Abstract
Secretagogin (SCGN), a hexa EF-hand calcium binding protein, plays key roles in insulin secretion in pancreatic β-cells. It is not yet understood how the binding of Ca2+ to human SCGN (hSCGN) promotes secretion. Here we have addressed this question, using mass spectrometry combined with a disulfide searching algorithm DBond. We found that the binding of Ca2+ to hSCGN promotes the dimerization of hSCGN via the formation of a Cys193-Cys193 disulfide bond. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) and molecular dynamics studies revealed that Ca2+ binding to the EF-hands of hSCGN induces significant structural changes that affect the solvent exposure of N-terminal region, and hence the redox sensitivity of the Cys193 residue. These redox sensitivity changes were confirmed using biotinylated methyl-3-nitro-4-(piperidin-1-ylsulfonyl) benzoate (NPSB-B), a chemical probe that specifically labels reactive cysteine sulfhydryls. Furthermore, we found that wild type hSCGN overexpression promotes insulin secretion in pancreatic β cells, while C193S-hSCGN inhibits it. These findings suggest that insulin secretion in pancreatic cells is regulated by Ca2+ and ROS signaling through Ca2+-induced structural changes promoting dimerization of hSCGN.
Collapse
Affiliation(s)
- Jae-Jin Lee
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea
| | - Seo-Yun Yang
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea
| | - Jimin Park
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea
| | - James E Ferrell
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305-5174, USA
| | - Dong-Hae Shin
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea
| | - Kong-Joo Lee
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea.
| |
Collapse
|
4
|
Secretagogin affects insulin secretion in pancreatic β-cells by regulating actin dynamics and focal adhesion. Biochem J 2016; 473:1791-803. [PMID: 27095850 PMCID: PMC4901359 DOI: 10.1042/bcj20160137] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/18/2016] [Indexed: 01/03/2023]
Abstract
Secretagogin (SCGN), a Ca2+-binding protein having six EF-hands, is selectively expressed in pancreatic β-cells and neuroendocrine cells. Previous studies suggested that SCGN enhances insulin secretion by functioning as a Ca2+-sensor protein, but the underlying mechanism has not been elucidated. The present study explored the mechanism by which SCGN enhances glucose-induced insulin secretion in NIT-1 insulinoma cells. To determine whether SCGN influences the first or second phase of insulin secretion, we examined how SCGN affects the kinetics of insulin secretion in NIT-1 cells. We found that silencing SCGN suppressed the second phase of insulin secretion induced by glucose and H2O2, but not the first phase induced by KCl stimulation. Recruitment of insulin granules in the second phase of insulin secretion was significantly impaired by knocking down SCGN in NIT-1 cells. In addition, we found that SCGN interacts with the actin cytoskeleton in the plasma membrane and regulates actin remodelling in a glucose-dependent manner. Since actin dynamics are known to regulate focal adhesion, a critical step in the second phase of insulin secretion, we examined the effect of silencing SCGN on focal adhesion molecules, including FAK (focal adhesion kinase) and paxillin, and the cell survival molecules ERK1/2 (extracellular-signal-regulated kinase 1/2) and Akt. We found that glucose- and H2O2-induced activation of FAK, paxillin, ERK1/2 and Akt was significantly blocked by silencing SCGN. We conclude that SCGN controls glucose-stimulated insulin secretion and thus may be useful in the therapy of Type 2 diabetes.
Collapse
|
5
|
|
6
|
Coupling of metabolic, second messenger pathways and insulin granule dynamics in pancreatic beta-cells: a computational analysis. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 107:293-303. [PMID: 21920379 DOI: 10.1016/j.pbiomolbio.2011.09.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 08/26/2011] [Accepted: 09/01/2011] [Indexed: 12/26/2022]
Abstract
Insulin secretory responses to nutrient stimuli and hormonal modulators in pancreatic beta-cells are controlled by a variety of secondary messengers. We have analyzed numerous mechanisms responsible for regulated exocytosis in these cells and present an integrated mathematical model of cytosolic Ca²⁺, cAMP and granule dynamics. The insulin-containing granules in the beta-cell were divided into four classes: a large "reserve" granule pool, a smaller pool of the morphologically docked granules that is chemically 'primed' for release or the "readily releasable pool", and a pool of "restless newcomer granules" that undergoes preferential exocytosis. The model incorporates glucose and other aspects of metabolism, the cAMP amplifying pathway, insulin granule dynamics and the exocyst concept for granule binding. The values of most of the model parameters were inferred from available experimental data. The model can generate both the fast first phase and slow biphasic insulin secretion found experimentally in response to a step increase of membrane potential or of glucose. The numerical simulations have also reproduced a variety of experimental conditions, such as periodic stimulation by high K⁺ and the potentiation induced in islets by pre-incubation with cAMP pathway activators. The explicit incorporation of Ca²⁺ channels, Ca²⁺ and cAMP dynamics allows the model to be further connected to current models for calcium and metabolic dynamics and provides an interpretation of the roles of the triggering and amplifying pathways of glucose-stimulated insulin secretion. The model may be important in the identification of pharmacological targets for improving insulin secretion in type 2 diabetes.
Collapse
|
7
|
Abstract
Nitric oxide (NO) is a structurally simple, highly versatile molecule that was originally discovered over 30 years ago as an endothelium-derived relaxing factor. In addition to its vasorelaxing effects, NO is now recognized as a key determinant of vascular health, exerting antiplatelet, antithrombotic, and anti-inflammatory properties within the vasculature. This short-lived molecule exerts its inhibitory effect on vascular smooth muscle cells and platelets largely through cyclic guanosine monophosphate-dependent mechanisms, resulting in a multitude of molecular effects by which platelet activation and aggregation are prevented. The biosynthesis of NO occurs via the catalytic activity of NO synthase, an oxidoreductase found in many cell types. NO insufficiency can be attributed to limited substrate/cofactor availability as well as interactions with reactive oxygen species. Impaired NO bioavailability represents the central feature of endothelial dysfunction, a common abnormality found in many vascular diseases. In this review, we present an overview of NO synthesis and biochemistry, discuss the mechanisms of action of NO in regulating platelet and endothelial function, and review the effects of vascular disease states on NO bioavailability.
Collapse
Affiliation(s)
- Richard C Jin
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | | |
Collapse
|
8
|
Bazwinsky-Wutschke I, Wolgast S, Mühlbauer E, Peschke E. Distribution patterns of calcium-binding proteins in pancreatic tissue of non-diabetic as well as type 2 diabetic rats and in rat insulinoma β-cells (INS-1). Histochem Cell Biol 2010; 134:115-27. [DOI: 10.1007/s00418-010-0721-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2010] [Indexed: 12/11/2022]
|
9
|
Gartner W, Vila G, Daneva T, Nabokikh A, Koc-Saral F, Ilhan A, Majdic O, Luger A, Wagner L. New functional aspects of the neuroendocrine marker secretagogin based on the characterization of its rat homolog. Am J Physiol Endocrinol Metab 2007; 293:E347-54. [PMID: 17426113 DOI: 10.1152/ajpendo.00055.2007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Secretagogin is a recently cloned human beta-cell-expressed EF-hand Ca(2+)-binding protein. Converging evidence indicates that it exerts Ca(2+) sensor activity and is involved in regulation of insulin synthesis and secretion. To obtain a potent tool for the extension of its functional analysis in rat in vitro systems, we cloned the rat homolog of human secretagogin. Using comparative sequence analysis, immunostaining, and immunoblotting, we demonstrated a high degree of sequence homology and similar tissue expression patterns of human and rat secretagogin. Highest rat secretagogin expression levels were found in pancreatic beta-cells. On the basis of newly generated anti-rat secretagogin antibodies, we established a rat secretagogin-specific sandwich capture ELISA and demonstrated release of secretagogin from viable Rin-5F cells. Dexamethasone treatment of Rin-5F cells resulted in an increased secretagogin release rate, which was inversely correlated with insulin secretion. In contrast, the secretagogin transcription rate was markedly reduced. This resulted in a decreased intracellular secretagogin content under the influence of dexamethasone. Sucrose gradient cell fractionation analysis of Rin-5F cells confirmed the predominant cytosolic localization of secretagogin, with only limited association of secretagogin with insulin granules. The loss of intracellular secretagogin after dexamethasone treatment affected predominantly the insulin granule-associated secretagogin fractions. The sequence homology and the comparable tissue expression patterns of human and rat secretagogin indicate conserved intracellular functions. The effects of dexamethasone on the total secretagogin content in Rin-5F cells and on its intracellular distribution might result in an impaired Ca(2+) sensitivity of dexamethasone-treated insulin-secreting cells.
Collapse
Affiliation(s)
- W Gartner
- Medical University Vienna, Department of Medicine III, Waehringer Guertel 18-20, A-1090 Vienna, Austria
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Abstract
The energy-dependent release of granule contents from activated platelets is a well-established component of normal hemostasis and thrombosis. A role for membrane fusion in this process has been presumed for decades, but only recently have the mechanisms of platelet membrane fusion been investigated at the molecular level. Such studies have demonstrated that platelet membrane fusion is controlled by lipid components of the membrane bilayer, by transmembrane proteins termed SNARE proteins, and by chaperone proteins that interact with SNARE proteins. This core membrane fusion machinery is controlled by activation-dependent changes in cytoskeletal organization, intracellular calcium levels, kinase activity, and intracellular protease activity. Through these mechanisms, interactions of ligands with their cognate cell-surface receptors are transmitted to the membrane fusion machinery to facilitate membrane fusion and secretion of granule contents from platelets.
Collapse
Affiliation(s)
- Robert Flaumenhaft
- Center for Hemostasis and Thrombosis Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass 02115, USA.
| |
Collapse
|
11
|
Iino S, Sudo T, Niwa T, Fukasawa T, Hidaka H, Niki I. Annexin XI may be involved in Ca2+ - or GTP-gammaS-induced insulin secretion in the pancreatic beta-cell. FEBS Lett 2000; 479:46-50. [PMID: 10940386 DOI: 10.1016/s0014-5793(00)01877-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The aim of this study was to investigate possible involvement of annexin XI in the insulin secretory machinery. In fluorescence immunocytochemistry, annexin XI was found in the cytoplasm of pancreatic endocrine cells and a pancreatic beta-cell line, MIN6, in a granular pattern. MIN6 cells also possessed weak and diffused annexin XI immunoreactivity in the cytoplasm. Immunoelectron microscopy revealed annexin XI in the insulin granules. Insulin secretion from streptolysin-O-permeabilized MIN6 cells was inhibited by anti-annexin XI antibody, when the release was stimulated by either Ca2+ or GTP-gammaS, but not by a protein kinase C-activating phorbol ester. Inhibition of insulin release by anti-annexin XI antibody was reproduced in permeabilized rat islets. These findings suggest that annexin XI may be involved in the regulation of insulin secretion from the pancreatic beta-cells.
Collapse
Affiliation(s)
- S Iino
- First Department of Anatomy, Nagoya University School of Medicine, Japan
| | | | | | | | | | | |
Collapse
|
12
|
Niki I. Ca2+ signaling and the insulin secretory cascade in the pancreatic beta-cell. JAPANESE JOURNAL OF PHARMACOLOGY 1999; 80:191-7. [PMID: 10461763 DOI: 10.1254/jjp.80.191] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Recent progress in electrophysiological and microscopic techniques have enabled us to estimate exocytotic and pre-exocytotic events in the secretory machinery in single pancreatic beta-cells. We have been studying mechanisms involved in the regulation of insulin granule movement, which supplies release-ready granules, by direct visualization of granule traffic in living beta-cells and found the movement to be regulated by a mechanism different from that controlling exocytosis. From the obtained findings together with those from electrophysiological approaches, a new understanding of the role of the crucial second messenger Ca2+, and other second messengers, as well as resultant protein phosphorylation has been generated. The aim of this review is to describe a synergistic network for the control of insulin release by second messengers and protein kinases.
Collapse
Affiliation(s)
- I Niki
- Department of Pharmacology, Nagoya University School of Medicine, Japan
| |
Collapse
|