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Meda P. Gap junction proteins are key drivers of endocrine function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:124-140. [PMID: 28284720 DOI: 10.1016/j.bbamem.2017.03.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 03/03/2017] [Accepted: 03/06/2017] [Indexed: 01/07/2023]
Abstract
It has long been known that the main secretory cells of exocrine and endocrine glands are connected by gap junctions, made by a variety of connexin species that ensure their electrical and metabolic coupling. Experiments in culture systems and animal models have since provided increasing evidence that connexin signaling contributes to control the biosynthesis and release of secretory products, as well as to the life and death of secretory cells. More recently, genetic studies have further provided the first lines of evidence that connexins also control the function of human glands, which are central to the pathogenesis of major endocrine diseases. Here, we summarize the recent information gathered on connexin signaling in these systems, since the last reviews on the topic, with particular regard to the pancreatic beta cells which produce insulin, and the renal cells which produce renin. These cells are keys to the development of various forms of diabetes and hypertension, respectively, and combine to account for the exploding, worldwide prevalence of the metabolic syndrome. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Paolo Meda
- Department of Cell Physiology and Metabolism, University of Geneva Medical School, Switzerland.
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2
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Lamprianou S, Gysemans C, Bou Saab J, Pontes H, Mathieu C, Meda P. Glibenclamide Prevents Diabetes in NOD Mice. PLoS One 2016; 11:e0168839. [PMID: 28006000 PMCID: PMC5178991 DOI: 10.1371/journal.pone.0168839] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 12/07/2016] [Indexed: 12/15/2022] Open
Abstract
Previous work has revealed that Cx36, the sole connexin expressed in the insulin-producing beta cells, enhances the secretion of insulin, and promotes the resistance of beta cells against pro-inflammatory cytokines. In parallel, the anti-diabetic sulphonylurea glibenclamide was shown to promote the assembly and function of Cx36 channels. Here, we assessed whether glibenclamide could protect the insulin-producing cells against conditions mimicking those expected at the onset of type 1 diabetes. We found that the drug 1) protected in vitro the mouse MIN6 cells from the apoptosis and loss of Cx36, which are induced by Th1 cytokines; 2) prevented the development of hyperglycemia as well as the loss of beta cells and Cx36, which rapidly develop with aging in untreated NOD mice; 3) modified the proportion of effector CD4+ and CD8+ T cells in pancreatic draining lymph nodes. The data imply that an early glibenclamide treatment may help protecting beta cells against the autoimmune attack, which triggers the development of type 1 diabetes.
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Affiliation(s)
- Smaragda Lamprianou
- Departement of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
- * E-mail:
| | - Conny Gysemans
- Laboratory of Clinical and Experimental Endocrinology, Katholieke Universiteit Leuven (KULEUVEN), Leuven, Belgium
| | - Joanna Bou Saab
- Departement of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Helena Pontes
- Departement of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Chantal Mathieu
- Laboratory of Clinical and Experimental Endocrinology, Katholieke Universiteit Leuven (KULEUVEN), Leuven, Belgium
| | - Paolo Meda
- Departement of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
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Smink AM, de Haan BJ, Paredes-Juarez GA, Wolters AHG, Kuipers J, Giepmans BNG, Schwab L, Engelse MA, van Apeldoorn AA, de Koning E, Faas MM, de Vos P. Selection of polymers for application in scaffolds applicable for human pancreatic islet transplantation. ACTA ACUST UNITED AC 2016; 11:035006. [PMID: 27173149 DOI: 10.1088/1748-6041/11/3/035006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The liver is currently the site for transplantation of islets in humans. This is not optimal for islets, but alternative sites in humans are not available. Polymeric scaffolds in surgically accessible areas are a solution. As human donors are rare, the polymers should not interfere with functional survival of human-islets. We applied a novel platform to test the adequacy of polymers for application in scaffolds for human-islet transplantation. Viability, functionality, and immune parameters were included to test poly(D,L-lactide-co-ε-caprolactone) (PDLLCL), poly(ethylene oxide terephthalate)/polybutylene terephthalate (PEOT/PBT) block copolymer, and polysulfone. The type of polymer influenced the functional survival of human islets. In islets cultured on PDLLCL the glucagon-producing α-cells and insulin-producing β-cells contained more hormone granules than in islets in contact with PEOT/PBT or polysulfone. This was studied with ultrastructural analysis by electron microscopy (nanotomy) during 7 d of culture. PDLLCL was also associated with statistically significant lower release of double-stranded DNA (dsDNA, a so called danger-associate molecular pattern (DAMP)) from islets on PDLLCL when compared to the other polymers. DAMPs support undesired immune responses. Hydrophilicity of the polymers did not influence dsDNA release. Islets on PDLLCL also showed less cellular outgrowth. These outgrowing cells were mainly fibroblast and some β-cells undergoing epithelial to mesenchymal cell transition. None of the polymers influenced the glucose-stimulated insulin secretion. As PDLLCL was associated with less release of DAMPs, it is a promising candidate for creating a scaffold for human islets. Our study demonstrates that for sensitive, rare cadaveric donor tissue such as pancreatic islets it might be necessary to first select materials that do not influence functionality before proposing the biomaterial for in vivo application. Our presented platform may facilitate this selection of biomaterials.
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Affiliation(s)
- Alexandra M Smink
- Department of Pathology and Medical Biology, Section of Immunoendocrinology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, EA11, 9700 GZ, Groningen, The Netherlands
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Abstract
The pancreas produces enzymes with a digestive function and hormones with a metabolic function, which are produced by distinct cell types of acini and islets, respectively. Within these units, secretory cells coordinate their functioning by exchanging information via signals that flow in the intercellular spaces and are generated either at distance (several neural and hormonal inputs) or nearby the pancreatic cells themselves (inputs mediated by membrane ionic-specific channels and by ionic- and metabolite-permeant pannexin channels and connexin "hemichannels"). Pancreatic secretory cells further interact via the extracellular matrix of the pancreas (inputs mediated by integrins) and directly with neighboring cells, by mechanisms that do not require extracellular mediators (inputs mediated by gap and tight junction channels). Here, we review the expression and function of the connexins and pannexins that are expressed by the main secretory cells of the exocrine and endocrine pancreatic cells. Available data show that the patterns of expression of these proteins differ in acini and islets, supporting distinct functions in the physiological secretion of pancreatic enzymes and hormones. Circumstantial evidence further suggests that alterations in the signaling provided by these proteins are involved in pancreatic diseases.
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Rutter GA, Hodson DJ. Beta cell connectivity in pancreatic islets: a type 2 diabetes target? Cell Mol Life Sci 2015; 72:453-467. [PMID: 25323131 PMCID: PMC11113448 DOI: 10.1007/s00018-014-1755-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/30/2014] [Accepted: 10/01/2014] [Indexed: 12/12/2022]
Abstract
Beta cell connectivity describes the phenomenon whereby the islet context improves insulin secretion by providing a three-dimensional platform for intercellular signaling processes. Thus, the precise flow of information through homotypically interconnected beta cells leads to the large-scale organization of hormone release activities, influencing cell responses to glucose and other secretagogues. Although a phenomenon whose importance has arguably been underappreciated in islet biology until recently, a growing number of studies suggest that such cell-cell communication is a fundamental property of this micro-organ. Hence, connectivity may plausibly be targeted by both environmental and genetic factors in type 2 diabetes mellitus (T2DM) to perturb normal beta cell function and insulin release. Here, we review the mechanisms that contribute to beta cell connectivity, discuss how these may fail during T2DM, and examine approaches to restore insulin secretion by boosting cell communication.
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Affiliation(s)
- Guy A Rutter
- Section of Cell Biology, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
| | - David J Hodson
- Section of Cell Biology, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
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Farnsworth NL, Hemmati A, Pozzoli M, Benninger RKP. Fluorescence recovery after photobleaching reveals regulation and distribution of connexin36 gap junction coupling within mouse islets of Langerhans. J Physiol 2014; 592:4431-46. [PMID: 25172942 PMCID: PMC4287745 DOI: 10.1113/jphysiol.2014.276733] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/11/2014] [Indexed: 11/08/2022] Open
Abstract
The pancreatic islets are central to the maintenance of glucose homeostasis through insulin secretion. Glucose‐stimulated insulin secretion is tightly linked to electrical activity in β cells within the islet. Gap junctions, composed of connexin36 (Cx36), form intercellular channels between β cells, synchronizing electrical activity and insulin secretion. Loss of gap junction coupling leads to altered insulin secretion dynamics and disrupted glucose homeostasis. Gap junction coupling is known to be disrupted in mouse models of pre‐diabetes. Although approaches to measure gap junction coupling have been devised, they either lack cell specificity, suitable quantification of coupling or spatial resolution, or are invasive. The purpose of this study was to develop fluorescence recovery after photobleaching (FRAP) as a technique to accurately and robustly measure gap junction coupling in the islet. The cationic dye Rhodamine 123 was used with FRAP to quantify dye diffusion between islet β cells as a measure of Cx36 gap junction coupling. Measurements in islets with reduced Cx36 verified the accuracy of this technique in distinguishing between distinct levels of gap junction coupling. Analysis of individual cells revealed that the distribution of coupling across the islet is highly heterogeneous. Analysis of several modulators of gap junction coupling revealed glucose‐ and cAMP‐dependent modulation of gap junction coupling in islets. Finally, FRAP was used to determine cell population specific coupling, where no functional gap junction coupling was observed between α cells and β cells in the islet. The results of this study show FRAP to be a robust technique which provides the cellular resolution to quantify the distribution and regulation of Cx36 gap junction coupling in specific cell populations within the islet. Future studies utilizing this technique may elucidate the role of gap junction coupling in the progression of diabetes and identify mechanisms of gap junction regulation for potential therapies.
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Affiliation(s)
- Nikki L Farnsworth
- Barbara Davis Center for Childhood Diabetes, University of Colorado, Aurora, CO, USA
| | - Alireza Hemmati
- Department of Bioengineering, University of Colorado, Aurora, CO, USA
| | - Marina Pozzoli
- Department of Bioengineering, University of Colorado, Aurora, CO, USA
| | - Richard K P Benninger
- Barbara Davis Center for Childhood Diabetes, University of Colorado, Aurora, CO, USA Department of Bioengineering, University of Colorado, Aurora, CO, USA
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Nguyen LM, Pozzoli M, Hraha TH, Benninger RK. Decreasing cx36 gap junction coupling compensates for overactive KATP channels to restore insulin secretion and prevent hyperglycemia in a mouse model of neonatal diabetes. Diabetes 2014; 63:1685-97. [PMID: 24458355 PMCID: PMC3994954 DOI: 10.2337/db13-1048] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 01/08/2014] [Indexed: 11/13/2022]
Abstract
Mutations to the ATP-sensitive K(+) channel (KATP channel) that reduce the sensitivity of ATP inhibition cause neonatal diabetes mellitus via suppression of β-cell glucose-stimulated free calcium activity ([Ca(2+)]i) and insulin secretion. Connexin-36 (Cx36) gap junctions also regulate islet electrical activity; upon knockout of Cx36, β-cells show [Ca(2+)]i elevations at basal glucose. We hypothesized that in the presence of overactive ATP-insensitive KATP channels, a reduction in Cx36 would allow elevations in glucose-stimulated [Ca(2+)]i and insulin secretion to improve glucose homeostasis. To test this, we introduced a genetic knockout of Cx36 into mice that express ATP-insensitive KATP channels and measured glucose homeostasis and islet metabolic, electrical, and insulin secretion responses. In the normal presence of Cx36, after expression of ATP-insensitive KATP channels, blood glucose levels rapidly rose to >500 mg/dL. Islets from these mice showed reduced glucose-stimulated [Ca(2+)]i and no insulin secretion. In mice lacking Cx36 after expression of ATP-insensitive KATP channels, normal glucose levels were maintained. Islets from these mice had near-normal glucose-stimulated [Ca(2+)]i and insulin secretion. We therefore demonstrate a novel mechanism by which islet function can be recovered in a monogenic model of diabetes. A reduction of gap junction coupling allows sufficient glucose-stimulated [Ca(2+)]i and insulin secretion to prevent the emergence of diabetes.
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Affiliation(s)
- Linda M. Nguyen
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Marina Pozzoli
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Thomas H. Hraha
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Richard K.P. Benninger
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
- Barbara Davis Center for Childhood Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO
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Farnsworth NL, Benninger RKP. New insights into the role of connexins in pancreatic islet function and diabetes. FEBS Lett 2014; 588:1278-87. [PMID: 24583073 DOI: 10.1016/j.febslet.2014.02.035] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 02/13/2014] [Accepted: 02/19/2014] [Indexed: 12/22/2022]
Abstract
Multi-cellular systems require complex signaling mechanisms for proper tissue function, to mediate signaling between cells in close proximity and at distances. This holds true for the islets of Langerhans, which are multicellular micro-organs located in the pancreas responsible for glycemic control, through secretion of insulin and other hormones. Coupling of electrical and metabolic signaling between islet β-cells is required for proper insulin secretion and effective glycemic control. β-cell specific coupling is established through gap junctions composed of connexin36, which results in coordinated insulin release across the islet. Islet connexins have been implicated in both Type-1 and Type-2 diabetes; however a clear link remains to be determined. The goal of this review is to discuss recent discoveries regarding the role of connexins in regulating insulin secretion, the regulation of connexins within the islet, and recent studies which support a role for connexins in diabetes. Further studies which investigate the regulation of connexins in the islet and their role in diabetes may lead to novel diabetes therapies which regulate islet function and β-cell survival through modulation of gap junction coupling.
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Affiliation(s)
- Nikki L Farnsworth
- Barbara Davis center for childhood diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, United States
| | - Richard K P Benninger
- Barbara Davis center for childhood diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, United States; Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, United States.
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9
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Allagnat F, Klee P, Cardozo AK, Meda P, Haefliger JA. Connexin36 contributes to INS-1E cells survival through modulation of cytokine-induced oxidative stress, ER stress and AMPK activity. Cell Death Differ 2013; 20:1742-52. [PMID: 24096873 PMCID: PMC3824597 DOI: 10.1038/cdd.2013.134] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/21/2013] [Accepted: 08/25/2013] [Indexed: 12/22/2022] Open
Abstract
Cell-to-cell communication mediated by gap junctions made of Connexin36 (Cx36) contributes to pancreatic β-cell function. We have recently demonstrated that Cx36 also supports β-cell survival by a still unclear mechanism. Using specific Cx36 siRNAs or adenoviral vectors, we now show that Cx36 downregulation promotes apoptosis in INS-1E cells exposed to the pro-inflammatory cytokines (IL-1β, TNF-α and IFN-γ) involved at the onset of type 1 diabetes, whereas Cx36 overexpression protects against this effect. Cx36 overexpression also protects INS-1E cells against endoplasmic reticulum (ER) stress-mediated apoptosis, and alleviates the cytokine-induced production of reactive oxygen species, the depletion of the ER Ca(2+) stores, the CHOP overexpression and the degradation of the anti-apoptotic protein Bcl-2 and Mcl-1. We further show that cytokines activate the AMP-dependent protein kinase (AMPK) in a NO-dependent and ER-stress-dependent manner and that AMPK inhibits Cx36 expression. Altogether, the data suggest that Cx36 is involved in Ca(2+) homeostasis within the ER and that Cx36 expression is downregulated following ER stress and subsequent AMPK activation. As a result, cytokine-induced Cx36 downregulation elicits a positive feedback loop that amplifies ER stress and AMPK activation, leading to further Cx36 downregulation. The data reveal that Cx36 plays a central role in the oxidative stress and ER stress induced by cytokines and the subsequent regulation of AMPK activity, which in turn controls Cx36 expression and mitochondria-dependent apoptosis of insulin-producing cells.
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Affiliation(s)
- F Allagnat
- Department of Medicine, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne. Switzerland
| | - P Klee
- Department of Cell Physiology and Metabolism, University of Geneva, Medical Center, Geneva, Switzerland
| | - A K Cardozo
- Laboratoire de Médecine Expérimentale, Université Libre de Bruxelles, Brussels, Belgium
| | - P Meda
- Department of Cell Physiology and Metabolism, University of Geneva, Medical Center, Geneva, Switzerland
| | - J-A Haefliger
- Department of Medicine, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne. Switzerland
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Haefliger JA, Rohner-Jeanrenaud F, Caille D, Charollais A, Meda P, Allagnat F. Hyperglycemia downregulates Connexin36 in pancreatic islets via the upregulation of ICER-1/ICER-1γ. J Mol Endocrinol 2013; 51:49-58. [PMID: 23613279 DOI: 10.1530/jme-13-0054] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Channels formed by the gap junction protein Connexin36 (CX36) contribute to the proper control of insulin secretion. We previously demonstrated that chronic exposure to glucose decreases Cx36 levels in insulin-secreting cells in vitro. Here, we investigated whether hyperglycemia also regulates Cx36 in vivo. Using a model of continuous glucose infusion in adult rats, we showed that prolonged (24-48 h) hyperglycemia reduced the Cx36 gene Gjd2 mRNA levels in pancreatic islets. Accordingly, prolonged exposure to high glucose concentrations also reduced the expression and function of Cx36 in the rat insulin-producing INS-1E cell line. The glucose effect was blocked after inhibition of the cAMP/PKA pathway and was associated with an overexpression of the inducible cAMP early repressor ICER-1/ICER-1γ, which binds to a functional cAMP-response element in the promoter of the Cx36 gene Gjd2. The involvement of this repressor was further demonstrated using an antisense strategy of ICER-1 inhibition, which prevented glucose-induced downregulation of Cx36. The data indicate that chronic exposure to glucose alters the in vivo expression of Cx36 by the insulin-producing β-cells through ICER-1/ICER-1γ overexpression. This mechanism may contribute to the reduced glucose sensitivity and altered insulin secretion, which contribute to the pathophysiology of diabetes.
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Affiliation(s)
- Jacques-Antoine Haefliger
- Service of Internal Medicine, Department of Physiology, University Hospital Lausanne, Lausanne, Switzerland
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Cigliola V, Chellakudam V, Arabieter W, Meda P. Connexins and β-cell functions. Diabetes Res Clin Pract 2013; 99:250-9. [PMID: 23176806 DOI: 10.1016/j.diabres.2012.10.016] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 10/15/2012] [Indexed: 11/20/2022]
Abstract
Proper functioning of pancreatic islets requires that numerous β-cells are properly coordinated. With evolution, many mechanisms have converged, which now allow individual β-cells to sense the state of activity of their neighbors as well as the changes taking place in the extracellular medium, and to regulate accordingly their own function. Here, we review one such mechanism for intercellular coordination, which depends on connexins. These integral membrane proteins accumulate at sites of close apposition between adjacent islet cell membranes, referred to as gap junctions. Recent evidence demonstrates that connexin-dependent signaling is relevant for the in vivo control of insulin biosynthesis and release, as well as for the survival of β-cells under stressing conditions. The data suggest that alterations of this signaling may be implicated in the β-cell alterations which characterize most forms of diabetes, raising the tantalizing possibility that targeting of the direct intercellular communications β-cells establish within each pancreatic islet may provide a novel, therapeutically useful strategy.
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Affiliation(s)
- Valentina Cigliola
- Department of Cell Physiology and Metabolism, University of Geneva School of Medicine, 1 rue Michel-Servet, Geneva, Switzerland
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Meda P. Protein-mediated interactions of pancreatic islet cells. SCIENTIFICA 2013; 2013:621249. [PMID: 24278783 PMCID: PMC3820362 DOI: 10.1155/2013/621249] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 12/10/2012] [Indexed: 05/29/2023]
Abstract
The islets of Langerhans collectively form the endocrine pancreas, the organ that is soley responsible for insulin secretion in mammals, and which plays a prominent role in the control of circulating glucose and metabolism. Normal function of these islets implies the coordination of different types of endocrine cells, noticeably of the beta cells which produce insulin. Given that an appropriate secretion of this hormone is vital to the organism, a number of mechanisms have been selected during evolution, which now converge to coordinate beta cell functions. Among these, several mechanisms depend on different families of integral membrane proteins, which ensure direct (cadherins, N-CAM, occludin, and claudins) and paracrine communications (pannexins) between beta cells, and between these cells and the other islet cell types. Also, other proteins (integrins) provide communication of the different islet cell types with the materials that form the islet basal laminae and extracellular matrix. Here, we review what is known about these proteins and their signaling in pancreatic β -cells, with particular emphasis on the signaling provided by Cx36, given that this is the integral membrane protein involved in cell-to-cell communication, which has so far been mostly investigated for effects on beta cell functions.
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Affiliation(s)
- Paolo Meda
- Department of Cell Physiology and Metabolism, University of Geneva School of Medicine, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland
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