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St. Clair JR, Westacott MJ, Miranda J, Farnsworth NL, Kravets V, Schleicher WE, Dwulet JM, Levitt CH, Heintz A, Ludin NWF, Benninger RKP. Restoring connexin-36 function in diabetogenic environments precludes mouse and human islet dysfunction. J Physiol 2023; 601:4053-4072. [PMID: 37578890 PMCID: PMC10508056 DOI: 10.1113/jp282114] [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: 07/02/2021] [Accepted: 07/27/2023] [Indexed: 08/16/2023] Open
Abstract
The secretion of insulin from β-cells in the islet of Langerhans is governed by a series of metabolic and electrical events, which can fail during the progression of type 2 diabetes (T2D). β-cells are electrically coupled via connexin-36 (Cx36) gap junction channels, which coordinates the pulsatile dynamics of [Ca2+ ] and insulin release across the islet. Factors such as pro-inflammatory cytokines and free fatty acids disrupt gap junction coupling under in vitro conditions. Here we test whether gap junction coupling and coordinated [Ca2+ ] dynamics are disrupted in T2D, and whether recovery of gap junction coupling can recover islet function. We examine islets from donors with T2D, from db/db mice, and islets treated with pro-inflammatory cytokines (TNF-α, IL-1β, IFN-ɣ) or free fatty acids (palmitate). We modulate gap junction coupling using Cx36 over-expression or pharmacological activation via modafinil. We also develop a peptide mimetic (S293) of the c-terminal regulatory site of Cx36 designed to compete against its phosphorylation. Cx36 gap junction permeability and [Ca2+ ] dynamics were disrupted in islets from both human donors with T2D and db/db mice, and in islets treated with pro-inflammatory cytokines or palmitate. Cx36 over-expression, modafinil treatment and S293 peptide all enhanced Cx36 gap junction coupling and protected against declines in coordinated [Ca2+ ] dynamics. Cx36 over-expression and S293 peptide also reduced apoptosis induced by pro-inflammatory cytokines. Critically, S293 peptide rescued gap junction coupling and [Ca2+ ] dynamics in islets from both db/db mice and a sub-set of T2D donors. Thus, recovering or enhancing Cx36 gap junction coupling can improve islet function in diabetes. KEY POINTS: Connexin-36 (Cx36) gap junction permeability and associated coordination of [Ca2+ ] dynamics is diminished in human type 2 diabetes (T2D) and mouse models of T2D. Enhancing Cx36 gap junction permeability protects against disruptions to the coordination of [Ca2+ ] dynamics. A novel peptide mimetic of the Cx36 c-terminal regulatory region protects against declines in Cx36 gap junction permeability. Pharmacological elevation in Cx36 or Cx36 peptide mimetic recovers [Ca2+ ] dynamics and glucose-stimulated insulin secretion in human T2D and mouse models of T2D.
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Affiliation(s)
- Joshua R St. Clair
- Department of Bioengineering, University of Colorado Denver
| Anschutz Medical Campus, Aurora, CO
| | - Matthew J Westacott
- Department of Bioengineering, University of Colorado Denver
| Anschutz Medical Campus, Aurora, CO
| | - Jose Miranda
- Department of Bioengineering, University of Colorado Denver
| Anschutz Medical Campus, Aurora, CO
| | - Nikki L Farnsworth
- Barbara Davis Center for Diabetes, University of Colorado
Denver | Anschutz Medical Campus, Aurora, CO
| | - Vira Kravets
- Department of Bioengineering, University of Colorado Denver
| Anschutz Medical Campus, Aurora, CO
| | - Wolfgang E Schleicher
- Department of Bioengineering, University of Colorado Denver
| Anschutz Medical Campus, Aurora, CO
| | - JaeAnn M Dwulet
- Department of Bioengineering, University of Colorado Denver
| Anschutz Medical Campus, Aurora, CO
| | - Claire H Levitt
- Department of Bioengineering, University of Colorado Denver
| Anschutz Medical Campus, Aurora, CO
| | - Audrey Heintz
- Department of Bioengineering, University of Colorado Denver
| Anschutz Medical Campus, Aurora, CO
| | - Nurin WF Ludin
- Department of Bioengineering, University of Colorado Denver
| Anschutz Medical Campus, Aurora, CO
| | - Richard KP Benninger
- Department of Bioengineering, University of Colorado Denver
| Anschutz Medical Campus, Aurora, CO
- Barbara Davis Center for Diabetes, University of Colorado
Denver | Anschutz Medical Campus, Aurora, CO
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2
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Farnsworth NL, Piscopio RA, Schleicher WE, Ramirez DG, Miranda JG, Benninger RKP. Modulation of Gap Junction Coupling Within the Islet of Langerhans During the Development of Type 1 Diabetes. Front Physiol 2022; 13:913611. [PMID: 35837011 PMCID: PMC9274093 DOI: 10.3389/fphys.2022.913611] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/09/2022] [Indexed: 01/07/2023] Open
Abstract
In type 1 diabetes (T1D), islet dysfunction occurs prior to diabetes onset. Pro-inflammatory cytokines can disrupt insulin secretion and Ca2+ homeostasis. Connexin36 (Cx36) gap junctions electrically couple β-cells to coordinate glucose-stimulated Ca2+ and insulin secretion. Cx36 gap junction coupling can also protect against cytokine-induced apoptosis. Our goal was to determine how islet gap junction coupling and Ca2+ dynamics are altered in mouse models of T1D prior to diabetes. Glucose tolerance was assessed in NOD and immunodeficient NOD-RAG1KO mice at 6-12 weeks age. Glucose-stimulated insulin secretion, Ca2+ dynamics, and gap junction coupling were measured in islets isolated at each age. Gap junction coupling was also measured in islets from mice that underwent transfer of diabetogenic splenocytes and from chromograninA knockout NOD mice. Cell death was measured in islets isolated from wild-type, Cx36 knockout or Cx36 over-expression mice, each treated with a cocktail of pro-inflammatory cytokines and KATP or SERCA activators/inhibitors. NOD mice over-expressing Cx36 were also monitored for diabetes development, and islets assessed for insulitis and apoptosis. NOD and NOD-RAG1KO controls showed similar glucose tolerance at all ages. Ca2+ dynamics and gap junction coupling were disrupted in islets of NOD mice at 9 weeks, compared to controls. Transfer of diabetogenic splenocytes also decreased gap junction coupling. Islets from chromograninA knockout mice displayed normal coupling. Overexpression of Cx36 protected islets from cytokine-induced apoptosis. A knockout of Cx36 amplified cytokine-induced apoptosis, which was reversed by KATP activation or SERCA activation. Cx36 overexpression in NOD mice delayed diabetes development compared to NOD controls. However, apoptosis and insulitis were not improved. Decreases in islet gap junction coupling occur prior to T1D onset. Such decreases alter islet susceptibility to apoptosis due to altered Ca2+. Future studies will determine if increasing Cx36 gap junction coupling in combination with restoring Ca2+ homeostasis protects against islet decline in T1D.
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Affiliation(s)
- Nikki L. Farnsworth
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, United States,Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Robert A. Piscopio
- Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Wolfgang E. Schleicher
- Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - David G. Ramirez
- Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Jose G. Miranda
- Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Richard K. P. Benninger
- Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States,*Correspondence: Richard K. P. Benninger,
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Collares-Buzato CB, Carvalho CP. Is type 2 diabetes mellitus another intercellular junction-related disorder? Exp Biol Med (Maywood) 2022; 247:743-755. [PMID: 35466731 DOI: 10.1177/15353702221090464] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Type 2 diabetes mellitus (T2D) is nowadays a worldwide epidemic and has become a major challenge for health systems around the world. It is a multifactorial disorder, characterized by a chronic state of hyperglycemia caused by defects in the production as well as in the peripheral action of insulin. This minireview highlights the experimental and clinical evidence that supports the novel idea that intercellular junctions (IJs)-mediated cell-cell contacts play a role in the pathogenesis of T2D. It focuses on IJs repercussion for endocrine pancreas, intestinal barrier, and kidney dysfunctions that contribute to the onset and evolution of this metabolic disorder.
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Affiliation(s)
- Carla B Collares-Buzato
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, CEP 13083-970, Brazil
| | - Carolina Pf Carvalho
- Department of Biosciences, Federal University of São Paulo (UNIFESP), Santos, SP, CEP 11015-020, Brazil
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Asrih M, Dusaulcy R, Gosmain Y, Philippe J, Somm E, Jornayvaz FR, Kang BE, Jo Y, Choi MJ, Yi HS, Ryu D, Gariani K. Growth differentiation factor-15 prevents glucotoxicity and connexin-36 downregulation in pancreatic beta-cells. Mol Cell Endocrinol 2022; 541:111503. [PMID: 34763008 DOI: 10.1016/j.mce.2021.111503] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 10/26/2021] [Accepted: 10/29/2021] [Indexed: 01/11/2023]
Abstract
Pancreatic beta cell dysfunction is a hallmark of type 2 diabetes. Growth differentiation factor 15 (GDF15), which is an energy homeostasis regulator, has been shown to improve several metabolic parameters in the context of diabetes. However, its effects on pancreatic beta-cell remain to be identified. We, therefore, performed experiments using cell models and histological sectioning of wild-type and knock-out GDF15 mice to determine the effect of GDF15 on insulin secretion and cell viability. A bioinformatics analysis was performed to identify GDF15-correlated genes. GDF15 prevents glucotoxicity-mediated altered glucose-stimulated insulin secretion (GSIS) and connexin-36 downregulation. Inhibition of endogenous GDF15 reduced GSIS in cultured mouse beta-cells under standard conditions while it had no impact on GSIS in cells exposed to glucolipotoxicity, which is a diabetogenic condition. Furthermore, this inhibition exacerbated glucolipotoxicity-reduced cell survival. This suggests that endogenous GDF15 in beta-cell is required for cell survival but not GSIS in the context of glucolipotoxicity.
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Affiliation(s)
- Mohamed Asrih
- Service of Endocrinology, Diabetes, Nutrition and Patient Therapeutic Education, Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, 1205, Geneva, Switzerland; University of Geneva Medical School, 1211, Geneva, Switzerland
| | - Rodolphe Dusaulcy
- Service of Endocrinology, Diabetes, Nutrition and Patient Therapeutic Education, Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, 1205, Geneva, Switzerland; University of Geneva Medical School, 1211, Geneva, Switzerland
| | - Yvan Gosmain
- Service of Endocrinology, Diabetes, Nutrition and Patient Therapeutic Education, Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, 1205, Geneva, Switzerland; University of Geneva Medical School, 1211, Geneva, Switzerland
| | - Jacques Philippe
- Service of Endocrinology, Diabetes, Nutrition and Patient Therapeutic Education, Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, 1205, Geneva, Switzerland; University of Geneva Medical School, 1211, Geneva, Switzerland
| | - Emmanuel Somm
- Service of Endocrinology, Diabetes, Nutrition and Patient Therapeutic Education, Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, 1205, Geneva, Switzerland; University of Geneva Medical School, 1211, Geneva, Switzerland
| | - François R Jornayvaz
- Service of Endocrinology, Diabetes, Nutrition and Patient Therapeutic Education, Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, 1205, Geneva, Switzerland; University of Geneva Medical School, 1211, Geneva, Switzerland
| | - Baeki E Kang
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, 16419, Suwon, Republic of Korea
| | - Yunju Jo
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, 16419, Suwon, Republic of Korea
| | - Min Jeong Choi
- Research Center for Endocrine and Metabolic Diseases, Chungnam National University Hospital, Chungnam National University School of Medicine, 35015, Daejeon, Republic of Korea; Department of Medical Science, Chungnam National University School of Medicine, 35015, Daejeon, Republic of Korea
| | - Hyon-Seung Yi
- Research Center for Endocrine and Metabolic Diseases, Chungnam National University Hospital, Chungnam National University School of Medicine, 35015, Daejeon, Republic of Korea; Department of Medical Science, Chungnam National University School of Medicine, 35015, Daejeon, Republic of Korea
| | - Dongryeol Ryu
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, 16419, Suwon, Republic of Korea; Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University, 16419, Suwon, Republic of Korea; Samsung Biomedical Research Institute, Samsung Medical Center, 06351, Seoul, Republic of Korea
| | - Karim Gariani
- Service of Endocrinology, Diabetes, Nutrition and Patient Therapeutic Education, Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, 1205, Geneva, Switzerland; University of Geneva Medical School, 1211, Geneva, Switzerland.
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Persistent coxsackievirus B1 infection triggers extensive changes in the transcriptome of human pancreatic ductal cells. iScience 2022; 25:103653. [PMID: 35024587 PMCID: PMC8728469 DOI: 10.1016/j.isci.2021.103653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/02/2021] [Accepted: 12/15/2021] [Indexed: 02/07/2023] Open
Abstract
Enteroviruses, particularly the group B coxsackieviruses (CVBs), have been associated with the development of type 1 diabetes. Several CVB serotypes establish chronic infections in human cells in vivo and in vitro. However, the mechanisms leading to enterovirus persistency and, possibly, beta cell autoimmunity are not fully understood. We established a carrier-state-type persistent infection model in human pancreatic cell line PANC-1 using two distinct CVB1 strains and profiled the infection-induced changes in cellular transcriptome. In the current study, we observed clear changes in the gene expression of factors associated with the pancreatic microenvironment, the secretory pathway, and lysosomal biogenesis during persistent CVB1 infections. Moreover, we found that the antiviral response pathways were activated differently by the two CVB1 strains. Overall, our study reveals extensive transcriptional responses in persistently CVB1-infected pancreatic cells with strong opposite but also common changes between the two strains. Establishment of persistent CVB1 infection in PANC-1 cells using two CVB1 strains Extensive transcriptional responses in persistently CVB1-infected pancreatic cells Changes in pancreatic microenvironment, secretory pathway, and lysosomes Antiviral immune response was activated differently by the two CVB1 strains
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Brito MDF, Torre C, Silva-Lima B. Scientific Advances in Diabetes: The Impact of the Innovative Medicines Initiative. Front Med (Lausanne) 2021; 8:688438. [PMID: 34295913 PMCID: PMC8290522 DOI: 10.3389/fmed.2021.688438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/02/2021] [Indexed: 12/16/2022] Open
Abstract
Diabetes Mellitus is one of the World Health Organization's priority diseases under research by the first and second programmes of Innovative Medicines Initiative, with the acronyms IMI1 and IMI2, respectively. Up to October of 2019, 13 projects were funded by IMI for Diabetes & Metabolic disorders, namely SUMMIT, IMIDIA, DIRECT, StemBANCC, EMIF, EBiSC, INNODIA, RHAPSODY, BEAT-DKD, LITMUS, Hypo-RESOLVE, IM2PACT, and CARDIATEAM. In general, a total of €447 249 438 was spent by IMI in the area of Diabetes. In order to prompt a better integration of achievements between the different projects, we perform a literature review and used three data sources, namely the official project's websites, the contact with the project's coordinators and co-coordinator, and the CORDIS database. From the 662 citations identified, 185 were included. The data collected were integrated into the objectives proposed for the four IMI2 program research axes: (1) target and biomarker identification, (2) innovative clinical trials paradigms, (3) innovative medicines, and (4) patient-tailored adherence programmes. The IMI funded projects identified new biomarkers, medical and research tools, determinants of inter-individual variability, relevant pathways, clinical trial designs, clinical endpoints, therapeutic targets and concepts, pharmacologic agents, large-scale production strategies, and patient-centered predictive models for diabetes and its complications. Taking into account the scientific data produced, we provided a joint vision with strategies for integrating personalized medicine into healthcare practice. The major limitations of this article were the large gap of data in the libraries on the official project websites and even the Cordis database was not complete and up to date.
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Affiliation(s)
| | - Carla Torre
- Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal.,Laboratory of Systems Integration Pharmacology, Clinical & Regulatory Science-Research Institute for Medicines (iMED.ULisboa), Lisbon, Portugal
| | - Beatriz Silva-Lima
- Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal.,Laboratory of Systems Integration Pharmacology, Clinical & Regulatory Science-Research Institute for Medicines (iMED.ULisboa), Lisbon, Portugal
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Gässler A, Quiclet C, Kluth O, Gottmann P, Schwerbel K, Helms A, Stadion M, Wilhelmi I, Jonas W, Ouni M, Mayer F, Spranger J, Schürmann A, Vogel H. Overexpression of Gjb4 impairs cell proliferation and insulin secretion in primary islet cells. Mol Metab 2020; 41:101042. [PMID: 32565358 PMCID: PMC7365933 DOI: 10.1016/j.molmet.2020.101042] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 06/16/2020] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE Altered gene expression contributes to the development of type 2 diabetes (T2D); thus, the analysis of differentially expressed genes between diabetes-susceptible and diabetes-resistant mouse models is an important tool for the determination of candidate genes that participate in the pathology. Based on RNA-seq and array data comparing pancreatic gene expression of diabetes-prone New Zealand Obese (NZO) mice and diabetes-resistant B6.V-ob/ob (B6-ob/ob) mice, the gap junction protein beta 4 (Gjb4) was identified as a putative novel T2D candidate gene. METHODS Gjb4 was overexpressed in primary islet cells derived from C57BL/6 (B6) mice and INS-1 cells via adenoviral-mediated infection. The proliferation rate of cells was assessed by BrdU incorporation, and insulin secretion was measured under low (2.8 mM) and high (20 mM) glucose concentration. INS-1 cell apoptosis rate was determined by Western blotting assessing cleaved caspase 3 levels. RESULTS Overexpression of Gjb4 in primary islet cells significantly inhibited the proliferation by 47%, reduced insulin secretion of primary islets (46%) and INS-1 cells (51%), and enhanced the rate of apoptosis by 63% in INS-1 cells. Moreover, an altered expression of the miR-341-3p contributes to the Gjb4 expression difference between diabetes-prone and diabetes-resistant mice. CONCLUSIONS The gap junction protein Gjb4 is highly expressed in islets of diabetes-prone NZO mice and may play a role in the development of T2D by altering islet cell function, inducing apoptosis and inhibiting proliferation.
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Affiliation(s)
- Anneke Gässler
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany; Department of Endocrinology and Metabolism, Charité-Universitätsmedizin Berlin, Charitéplatz 1, D-10117, Berlin, Germany
| | - Charline Quiclet
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany
| | - Oliver Kluth
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany
| | - Pascal Gottmann
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany
| | - Kristin Schwerbel
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany
| | - Anett Helms
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany
| | - Mandy Stadion
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany
| | - Ilka Wilhelmi
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany
| | - Wenke Jonas
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany
| | - Meriem Ouni
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany
| | - Frank Mayer
- University Outpatient Clinic, Centre of Sports Medicine, University of Potsdam, Am Neuen Palais 10, D-14469, Potsdam, Germany
| | - Joachim Spranger
- Department of Endocrinology and Metabolism, Charité-Universitätsmedizin Berlin, Charitéplatz 1, D-10117, Berlin, Germany
| | - Annette Schürmann
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany; Institute of Nutritional Sciences, University of Potsdam, D-14558, Nuthetal, Germany
| | - Heike Vogel
- Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany; German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, D-85764, München-Neuherberg, Germany; Molecular and Clinical Life Science of Metabolic Diseases, University of Potsdam, Arthur-Scheunert-Allee 114-116, D-14558, Nuthetal, Germany.
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The Connexin 43 Regulator Rotigaptide Reduces Cytokine-Induced Cell Death in Human Islets. Int J Mol Sci 2020; 21:ijms21124311. [PMID: 32560352 PMCID: PMC7352593 DOI: 10.3390/ijms21124311] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/11/2020] [Accepted: 06/15/2020] [Indexed: 01/23/2023] Open
Abstract
Background: Intercellular communication mediated by cationic fluxes through the Connexin family of gap junctions regulates glucose-stimulated insulin secretion and beta cell defense against inflammatory stress. Rotigaptide (RG, ZP123) is a peptide analog that increases intercellular conductance in cardiac muscle cells by the prevention of dephosphorylation and thereby uncoupling of Connexin-43 (Cx43), possibly via action on unidentified protein phosphatases. For this reason, it is being studied in human arrhythmias. It is unknown if RG protects islet cell function and viability against inflammatory or metabolic stress, a question of considerable translational interest for the treatment of diabetes. Methods: Apoptosis was measured in human islets shown to express Cx43, treated with RG or the control peptide ZP119 and exposed to glucolipotoxicity or IL-1β + IFNɣ. INS-1 cells shown to lack Cx43 were used to examine if RG protected human islet cells via Cx43 coupling. To study the mechanisms of action of Cx43-independent effects of RG, NO, IkBα degradation, mitochondrial activity, ROS, and insulin mRNA levels were determined. Results: RG reduced cytokine-induced apoptosis ~40% in human islets. In Cx43-deficient INS-1 cells, this protective effect was markedly blunted as expected, but unexpectedly, RG still modestly reduced apoptosis, and improved mitochondrial function, insulin-2 gene levels, and accumulated insulin release. RG reduced NO production in Cx43-deficient INS-1 cells associated with reduced iNOS expression, suggesting that RG blunts cytokine-induced NF-κB signaling in insulin-producing cells in a Cx43-independent manner. Conclusion: RG reduces cytokine-induced cell death in human islets. The protective action in Cx43-deficient INS-1 cells suggests a novel inhibitory mechanism of action of RG on NF-κB signaling.
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Yang W, Lampe PD, Kensel-Hammes P, Hesson J, Ware CB, Crisa L, Cirulli V. Connexin 43 Functions as a Positive Regulator of Stem Cell Differentiation into Definitive Endoderm and Pancreatic Progenitors. iScience 2019; 19:450-460. [PMID: 31430690 PMCID: PMC6708988 DOI: 10.1016/j.isci.2019.07.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 05/04/2019] [Accepted: 07/18/2019] [Indexed: 01/05/2023] Open
Abstract
Efficient stem cell differentiation into pancreatic islet cells is of critical importance for the development of cell replacement therapies for diabetes. Here, we identify the expression pattern of connexin 43 (Cx43), a gap junction (GJ) channel protein, in human embryonic stem cell (hESC)-derived definitive endoderm (DE) and primitive gut tube cells, representing early lineages for posterior foregut (PF), pancreatic progenitors (PP), pancreatic endocrine progenitors (PE), and islet cells. As the function of GJ channels is dependent on their gating status, we tested the impact of supplementing hESC-derived PP cell cultures with AAP10, a peptide that promotes Cx43 GJ channel opening. We found that this treatment promotes the expression of DE markers FoxA2 and Sox17, leads to a more efficient derivation of DE, and improves the yield of PF, PP, and PE cells. These results demonstrate a functional involvement of GJ channels in the differentiation of embryonic stem cells into pancreatic cell lineages.
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Affiliation(s)
- Wendy Yang
- Department of Medicine, UW Diabetes Institute, University of Washington, 850 Republican Street, S475, Seattle, WA 98109, USA
| | - Paul D Lampe
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Patricia Kensel-Hammes
- Department of Medicine, UW Diabetes Institute, University of Washington, 850 Republican Street, S475, Seattle, WA 98109, USA
| | - Jennifer Hesson
- Institute for Stem Cell and Regenerative Medicine, University of Washington, 850 Republican Street, S480, Seattle, WA 98109, USA
| | - Carol B Ware
- Institute for Stem Cell and Regenerative Medicine, University of Washington, 850 Republican Street, S480, Seattle, WA 98109, USA
| | - Laura Crisa
- Department of Medicine, UW Diabetes Institute, University of Washington, 850 Republican Street, S475, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, 850 Republican Street, S480, Seattle, WA 98109, USA; Department of Pharmacology, University of Washington, Seattle, WA, USA.
| | - Vincenzo Cirulli
- Department of Medicine, UW Diabetes Institute, University of Washington, 850 Republican Street, S475, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, 850 Republican Street, S480, Seattle, WA 98109, USA; Department of Pharmacology, University of Washington, Seattle, WA, USA.
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10
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Loppini A, Filippi S, Stanley HE. Critical transitions in heterogeneous networks: Loss of low-degree nodes as an early warning signal. Phys Rev E 2019; 99:040301. [PMID: 31108675 DOI: 10.1103/physreve.99.040301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Indexed: 06/09/2023]
Abstract
A large number of real networks show abrupt phase transition phenomena in response to environmental changes. In this case, cascading phenomena can induce drastic and discontinuous changes in the system state and lead to collapse. Although complex network theory has been used to investigate these drastic events, we are still unable to predict them effectively. We here analyze collapse phenomena by proposing a minimal two-state dynamic on a complex network and introducing the effect of local connectivities on the evolution of network nodes. We find that a heterogeneous system of interconnected components presents a mixed response to stress and can serve as a control indicator. In particular, before the critical transition point is reached a severe loss of low-degree nodes is observed, masked by the minimal failure of higher-degree nodes. Accordingly, we suggest that a significant reduction in less connected nodes can indicate impending global failure.
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Affiliation(s)
- Alessandro Loppini
- Department of Engineering, Campus Bio-Medico University of Rome, Via A. del Portillo 21, 00128 Rome, Italy
| | - Simonetta Filippi
- Department of Engineering, Campus Bio-Medico University of Rome, Via A. del Portillo 21, 00128 Rome, Italy
- International Center for Relativistic Astrophysics Network-ICRANet, Piazza della Repubblica 10, Pescara I-65122, Italy
| | - H Eugene Stanley
- Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215, USA
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11
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Navarro-Tableros V, Gomez Y, Brizzi MF, Camussi G. Generation of Human Stem Cell-Derived Pancreatic Organoids (POs) for Regenerative Medicine. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1212:179-220. [PMID: 31025308 DOI: 10.1007/5584_2019_340] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Insulin-dependent diabetes mellitus or type 1 diabetes mellitus (T1DM) is an auto-immune condition characterized by the loss of pancreatic β-cells. The curative approach for highly selected patients is the pancreas or the pancreatic islet transplantation. Nevertheless, these options are limited by a growing shortage of donor organs and by the requirement of immunosuppression.Xenotransplantation of porcine islets has been extensively investigated. Nevertheless, the strong xenoimmunity and the risk of transmission of porcine endogenous retroviruses, have limited their application in clinic. Generation of β-like cells from stem cells is one of the most promising strategies in regenerative medicine. Embryonic, and more recently, adult stem cells are currently the most promising cell sources exploited to generate functional β-cells in vitro. A number of studies demonstrated that stem cells could generate functional pancreatic organoids (POs), able to restore normoglycemia when implanted in different preclinical diabetic models. Nevertheless, a gradual loss of function and cell dead are commonly detected when POs are transplanted in immunocompetent animals. So far, the main issue to be solved is the post-transplanted islet loss, due to the host immune attack. To avoid this hurdle, nanotechnology has provided a number of polymers currently under investigation for islet micro and macro-encapsulation. These new approaches, besides conferring PO immune protection, are able to supply oxygen and nutrients and to preserve PO morphology and long-term viability.Herein, we summarize the current knowledge on bioengineered POs and the stem cell differentiation platforms. We also discuss the in vitro strategies used to generate functional POs, and the protocols currently used to confer immune-protection against the host immune attack (micro- and macro-encapsulation). In addition, the most relevant ongoing clinical trials, and the most relevant hurdles met to move towards clinical application are revised.
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Affiliation(s)
- Victor Navarro-Tableros
- 2i3T Società per la gestione dell'incubatore di imprese e per il trasferimento tecnologico Scarl, University of Turin, Turin, Italy
| | - Yonathan Gomez
- Department of Medical Sciences, University of Turin, Turin, Italy
| | | | - Giovanni Camussi
- Department of Medical Sciences, University of Turin, Turin, Italy.
- Fondazione per la Ricerca Biomedica-ONLUS, Turin, Italy.
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12
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Farnsworth NL, Walter R, Piscopio RA, Schleicher WE, Benninger RKP. Exendin-4 overcomes cytokine-induced decreases in gap junction coupling via protein kinase A and Epac2 in mouse and human islets. J Physiol 2019; 597:431-447. [PMID: 30412665 PMCID: PMC6332825 DOI: 10.1113/jp276106] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 11/07/2018] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS The pancreatic islets of Langerhans maintain glucose homeostasis through insulin secretion, where insulin secretion dynamics are regulated by intracellular Ca2+ signalling and electrical coupling of the insulin producing β-cells in the islet. We have previously shown that cytokines decrease β-cell coupling and that compounds which increase cAMP can increase coupling. In both mouse and human islets exendin-4, which increases cAMP, protected against cytokine-induced decreases in coupling and in mouse islets preserved glucose-stimulated calcium signalling by increasing connexin36 gap junction levels on the plasma membrane. Our data indicate that protein kinase A regulates β-cell coupling through a fast mechanism, such as channel gating or membrane organization, while Epac2 regulates slower mechanisms of regulation, such as gap junction turnover. Increases in β-cell coupling with exendin-4 may protect against cytokine-mediated β-cell death as well as preserve insulin secretion dynamics during the development of diabetes. ABSTRACT The pancreatic islets of Langerhans maintain glucose homeostasis. Insulin secretion from islet β-cells is driven by glucose metabolism, depolarization of the cell membrane and an influx of calcium, which initiates the release of insulin. Gap junctions composed of connexin36 (Cx36) electrically couple β-cells, regulating calcium signalling and insulin secretion dynamics. Cx36 coupling is decreased in pre-diabetic mice, suggesting a role for altered coupling in diabetes. Our previous work has shown that pro-inflammatory cytokines decrease Cx36 coupling and that compounds which increase cAMP can increase Cx36 coupling. The goal of this study was to determine if exendin-4, which increases cAMP, can protect against cytokine-induced decreases in Cx36 coupling and altered islet function. In both mouse and human islets, exendin-4 protected against cytokine-induced decreases in coupling and preserved glucose-stimulated calcium signalling. Exendin-4 also protected against protein kinase Cδ-mediated decreases in Cx36 coupling. Exendin-4 preserved coupling in mouse islets by preserving Cx36 levels on the plasma membrane. Exendin-4 regulated Cx36 coupling via both protein kinase A (PKA)- and Epac2-mediated mechanisms in cytokine-treated islets. In mouse islets, modulating Epac2 had a greater impact in mediating Cx36 coupling, while in human islets modulating PKA had a greater impact on Cx36 coupling. Our data indicate that PKA regulates Cx36 coupling through a fast mechanism, such as channel gating, while Epac2 regulates slower mechanisms of regulation, such as Cx36 turnover in the membrane. Increases in Cx36 coupling with exendin-4 may protect against cytokine-mediated β-cell dysfunction to insulin secretion dynamics during the development of diabetes.
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Affiliation(s)
- Nikki L. Farnsworth
- Barbara Davis Center for Childhood DiabetesUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
| | - Rachelle Walter
- Department of BioengineeringUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
| | - Robert A. Piscopio
- Department of BioengineeringUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
| | - Wolfgang E. Schleicher
- Department of BioengineeringUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
| | - Richard K. P. Benninger
- Barbara Davis Center for Childhood DiabetesUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
- Department of BioengineeringUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
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13
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Loppini A, Pedersen MG, Braun M, Filippi S. Gap-junction coupling and ATP-sensitive potassium channels in human β-cell clusters: Effects on emergent dynamics. Phys Rev E 2017; 96:032403. [PMID: 29346932 DOI: 10.1103/physreve.96.032403] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Indexed: 11/07/2022]
Abstract
The importance of gap-junction coupling between β cells in pancreatic islets is well established in mouse. Such ultrastructural connections synchronize cellular activity, confine biological heterogeneity, and enhance insulin pulsatility. Dysfunction of coupling has been associated with diabetes and altered β-cell function. However, the role of gap junctions between human β cells is still largely unexplored. By using patch-clamp recordings of β cells from human donors, we previously estimated electrical properties of these channels by mathematical modeling of pairs of human β cells. In this work we revise our estimate by modeling triplet configurations and larger heterogeneous clusters. We find that a coupling conductance in the range 0.005-0.020 nS/pF can reproduce experiments in almost all the simulated arrangements. We finally explore the consequence of gap-junction coupling of this magnitude between β cells with mutant variants of the ATP-sensitive potassium channels involved in some metabolic disorders and diabetic conditions, translating studies performed on rodents to the human case. Our results are finally discussed from the perspective of therapeutic strategies. In summary, modeling of more realistic clusters with more than two β cells slightly lowers our previous estimate of gap-junction conductance and gives rise to patterns that more closely resemble experimental traces.
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Affiliation(s)
- A Loppini
- Nonlinear Physics and Mathematical Modeling Laboratory, Campus Bio-Medico University of Rome, I-00128 Rome, Italy
| | - M G Pedersen
- Department of Information Engineering, University of Padua, I-35131 Padua, Italy
| | - M Braun
- Alberta Diabetes Institute, Department of Pharmacology, University of Alberta, Edmonton, T6G 2H7 Alberta, Canada
| | - S Filippi
- Nonlinear Physics and Mathematical Modeling Laboratory, Campus Bio-Medico University of Rome, I-00128 Rome, Italy
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14
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Westacott MJ, Farnsworth NL, St Clair JR, Poffenberger G, Heintz A, Ludin NW, Hart NJ, Powers AC, Benninger RKP. Age-Dependent Decline in the Coordinated [Ca 2+] and Insulin Secretory Dynamics in Human Pancreatic Islets. Diabetes 2017; 66:2436-2445. [PMID: 28588099 PMCID: PMC5566297 DOI: 10.2337/db17-0137] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 05/30/2017] [Indexed: 12/25/2022]
Abstract
Aging is associated with increased risk for type 2 diabetes, resulting from reduced insulin sensitivity and secretion. Reduced insulin secretion can result from reduced proliferative capacity and reduced islet function. Mechanisms underlying altered β-cell function in aging are poorly understood in mouse and human islets, and the impact of aging on intraislet communication has not been characterized. Here, we examine how β-cell [Ca2+] and electrical communication are impacted during aging in mouse and human islets. Islets from human donors and from mice were studied using [Ca2+] imaging, static and perifusion insulin secretion assays, and gap junction permeability measurements. In human islets, [Ca2+] dynamics were coordinated within distinct subregions of the islet, invariant with islet size. There was a marked decline in the coordination of [Ca2+] dynamics, gap junction coupling, and insulin secretion dynamics with age. These age-dependent declines were reversed by pharmacological gap junction activation. These results show that human islet function declines with aging, which can reduce insulin action and may contribute to increased risk of type 2 diabetes.
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Affiliation(s)
- Matthew J Westacott
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Nikki L Farnsworth
- Barbara Davis Center for Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Joshua R St Clair
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Greg Poffenberger
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN
- VA Tennessee Valley Healthcare System, Nashville, TN
| | - Audrey Heintz
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Nurin W Ludin
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Nathaniel J Hart
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
| | - Alvin C Powers
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN
- VA Tennessee Valley Healthcare System, Nashville, TN
| | - Richard K P Benninger
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
- Barbara Davis Center for Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO
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15
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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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16
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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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17
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Abstract
OBJECTIVES Mechanisms of toxicity and cell damage were investigated in novel clonal human pancreatic beta cell line, 1.1B4, after exposure to streptozotocin, alloxan, ninhydrin, and hydrogen peroxide. METHODS Viability, DNA damage, insulin secretion/content, [Ca]i, and glucokinase/hexokinase, mRNA expression were measured by MTT assay, comet assay, radioimmunoassay, fluorometric imaging plate reader, enzyme-coupled photometry, and real-time polymerase chain reaction, respectively. RESULTS Chemicals significantly reduced 1.1B4 cell viability in a time/concentration-dependent manner. Chronic 18-hour exposure decreased cellular insulin, glucokinase, and hexokinase activities. Chemicals decreased transcription of INS, GCK, PCSK1, PCSK2, and GJA1 (involved in secretory function). Insulin release and [Ca]i responses to nutrients and membrane-depolarizing agents were impaired. Streptozotocin and alloxan up-regulated transcription of genes, SOD1 and SOD2 (antioxidant enzymes). Ninhydrin and hydrogen peroxide up-regulated SOD2 transcription, whereas alloxan and hydrogen peroxide increased CAT transcription. Chemicals induced DNA damage, apoptosis, and increased caspase 3/7 activity. Streptozotocin and alloxan decreased transcription of BCL2 while increasing transcription of BAX. Chemicals did not affect transcription of HSPA4 and HSPA5 and nitrite production. CONCLUSIONS 1.1B4 cells represent a useful model of human beta cells. Chemicals impaired 1.1B4 cell secretory function and activated antioxidant defense and apoptotic pathways without activating endoplasmic reticulum stress response/nitrosative stress.
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18
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Klee P, Bosco D, Guérardel A, Somm E, Toulotte A, Maechler P, Schwitzgebel VM. Activation of Nicotinic Acetylcholine Receptors Decreases Apoptosis in Human and Female Murine Pancreatic Islets. Endocrinology 2016; 157:3800-3808. [PMID: 27471776 DOI: 10.1210/en.2015-2057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Type 1 diabetes (T1DM) results from destruction of most insulin-secreting pancreatic β-cells. The persistence of β-cells decades after the onset of the disease indicates that the resistance of individual cells to the autoimmune insult is heterogeneous and might depend on the metabolic status of a cell at a given moment. The aim of this study is to investigate whether activation of nicotinic acetylcholine receptors (nACh-Rs) could increase β-cell resistance against the adverse environment prevailing at the onset of T1DM. Here, we show that nACh-R activation by nicotine and choline, 2 agonists of the receptor, decreases murine and human β-cell apoptosis induced by proinflammatory cytokines known to be present in the islet environment at the onset of T1DM. The protective mechanism activated by nicotine and choline involves attenuation of mitochondrial outer membrane permeabilization via modulation of endoplasmic reticulum stress, of the activity of B-cell lymphoma 2 family proteins and cytoplasmic calcium levels. Local inflammation and endoplasmic reticulum stress being key determinants of β-cell death in T1DM, we conclude that pharmacological activation of nACh-R could represent a valuable therapeutic option in the modulation of β-cell death in T1DM.
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Affiliation(s)
- Philippe Klee
- Service of Development and Growth (P.K., A.G., E.S., A.T., V.S.), Department of Pediatrics, University Hospital of Geneva and Diabetes Center, University of Geneva, 1211 Geneva, Switzerland; Cell Isolation and Transplantation Center (D.B.), Department of Surgery, University Hospital of Geneva and University of Geneva, 1205 Geneva, Switzerland; and Department of Cell Physiology and Metabolism (P.M.), Geneva University Medical Center, 1205 Geneva, Switzerland
| | - Domenico Bosco
- Service of Development and Growth (P.K., A.G., E.S., A.T., V.S.), Department of Pediatrics, University Hospital of Geneva and Diabetes Center, University of Geneva, 1211 Geneva, Switzerland; Cell Isolation and Transplantation Center (D.B.), Department of Surgery, University Hospital of Geneva and University of Geneva, 1205 Geneva, Switzerland; and Department of Cell Physiology and Metabolism (P.M.), Geneva University Medical Center, 1205 Geneva, Switzerland
| | - Audrey Guérardel
- Service of Development and Growth (P.K., A.G., E.S., A.T., V.S.), Department of Pediatrics, University Hospital of Geneva and Diabetes Center, University of Geneva, 1211 Geneva, Switzerland; Cell Isolation and Transplantation Center (D.B.), Department of Surgery, University Hospital of Geneva and University of Geneva, 1205 Geneva, Switzerland; and Department of Cell Physiology and Metabolism (P.M.), Geneva University Medical Center, 1205 Geneva, Switzerland
| | - Emmanuel Somm
- Service of Development and Growth (P.K., A.G., E.S., A.T., V.S.), Department of Pediatrics, University Hospital of Geneva and Diabetes Center, University of Geneva, 1211 Geneva, Switzerland; Cell Isolation and Transplantation Center (D.B.), Department of Surgery, University Hospital of Geneva and University of Geneva, 1205 Geneva, Switzerland; and Department of Cell Physiology and Metabolism (P.M.), Geneva University Medical Center, 1205 Geneva, Switzerland
| | - Audrey Toulotte
- Service of Development and Growth (P.K., A.G., E.S., A.T., V.S.), Department of Pediatrics, University Hospital of Geneva and Diabetes Center, University of Geneva, 1211 Geneva, Switzerland; Cell Isolation and Transplantation Center (D.B.), Department of Surgery, University Hospital of Geneva and University of Geneva, 1205 Geneva, Switzerland; and Department of Cell Physiology and Metabolism (P.M.), Geneva University Medical Center, 1205 Geneva, Switzerland
| | - Pierre Maechler
- Service of Development and Growth (P.K., A.G., E.S., A.T., V.S.), Department of Pediatrics, University Hospital of Geneva and Diabetes Center, University of Geneva, 1211 Geneva, Switzerland; Cell Isolation and Transplantation Center (D.B.), Department of Surgery, University Hospital of Geneva and University of Geneva, 1205 Geneva, Switzerland; and Department of Cell Physiology and Metabolism (P.M.), Geneva University Medical Center, 1205 Geneva, Switzerland
| | - Valérie M Schwitzgebel
- Service of Development and Growth (P.K., A.G., E.S., A.T., V.S.), Department of Pediatrics, University Hospital of Geneva and Diabetes Center, University of Geneva, 1211 Geneva, Switzerland; Cell Isolation and Transplantation Center (D.B.), Department of Surgery, University Hospital of Geneva and University of Geneva, 1205 Geneva, Switzerland; and Department of Cell Physiology and Metabolism (P.M.), Geneva University Medical Center, 1205 Geneva, Switzerland
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19
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Sato T, Kaneko YK, Sawatani T, Noguchi A, Ishikawa T. Obligatory Role of Early Ca(2+) Responses in H2O2-Induced β-Cell Apoptosis. Biol Pharm Bull 2016; 38:1599-605. [PMID: 26424020 DOI: 10.1248/bpb.b15-00396] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Our previous study using apoptosis analysis suggested that Ca(2+) release through inositol 1,4,5-trisphosphate (IP3) receptors and the subsequent Ca(2+) influx through store-operated channels (SOCs) constitute a triggering signal for H2O2-induced β-cell apoptosis. In the present study, we further examined the obligatory role of early Ca(2+) responses in β-cell apoptosis induction. H2O2 induced elevation of the cytosolic Ca(2+) concentration ([Ca(2+)]c) consisting of two phases: an initial transient [Ca(2+)]c elevation within 30 min and a slowly developing one thereafter. The first phase was almost abolished by 2-aminoethoxydiphenylborate (2-APB), which blocks IP3 receptors and cation channels including SOCs, while the second phase was only partially inhibited by 2-APB. The inhibition by 2-APB of the second phase was not observed when 2-APB was added 30 min after the treatment with H2O2. 2-APB also largely inhibited elevation of the mitochondrial Ca(2+) concentration ([Ca(2+)]m) induced by H2O2 when 2-APB was applied simultaneously with H2O2, but not when applied 30 min after H2O2 application. In addition, 2-APB inhibited the release of mitochondrial cytochrome c to the cytosol induced by H2O2 when 2-APB was applied simultaneously with H2O2 but not 30 min post-treatment. H2O2-induced [Ca(2+)]m elevation and cell death were not inhibited by Ru360, an inhibitor of the mitochondrial calcium uniporter (MCU). These results suggest that the H2O2-induced initial [Ca(2+)]c elevation, occurring within 30 min and mediated by Ca(2+) release through IP3 receptors and subsequent Ca(2+) influx through SOCs, leads to [Ca(2+)]m elevation, possibly through a mechanism independent of MCU, thereby inducing cytochrome c release and consequent apoptosis.
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Affiliation(s)
- Taiji Sato
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, University of Shizuoka
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20
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Striegel DA, Hara M, Periwal V. Adaptation of pancreatic islet cyto-architecture during development. Phys Biol 2016; 13:025004. [PMID: 27063927 DOI: 10.1088/1478-3975/13/2/025004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Plasma glucose in mammals is regulated by hormones secreted by the islets of Langerhans embedded in the exocrine pancreas. Islets consist of endocrine cells, primarily α, β, and δ cells, which secrete glucagon, insulin, and somatostatin, respectively. β cells form irregular locally connected clusters within islets that act in concert to secrete insulin upon glucose stimulation. Varying demands and available nutrients during development produce changes in the local connectivity of β cells in an islet. We showed in earlier work that graph theory provides a framework for the quantification of the seemingly stochastic cyto-architecture of β cells in an islet. To quantify the dynamics of endocrine connectivity during development requires a framework for characterizing changes in the probability distribution on the space of possible graphs, essentially a Fokker-Planck formalism on graphs. With large-scale imaging data for hundreds of thousands of islets containing millions of cells from human specimens, we show that this dynamics can be determined quantitatively. Requiring that rearrangement and cell addition processes match the observed dynamic developmental changes in quantitative topological graph characteristics strongly constrained possible processes. Our results suggest that there is a transient shift in preferred connectivity for β cells between 1-35 weeks and 12-24 months.
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21
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Cigliola V, Populaire C, Pierri CL, Deutsch S, Haefliger JA, Fadista J, Lyssenko V, Groop L, Rueedi R, Thorel F, Herrera PL, Meda P. A Variant of GJD2, Encoding for Connexin 36, Alters the Function of Insulin Producing β-Cells. PLoS One 2016; 11:e0150880. [PMID: 26959991 PMCID: PMC4784816 DOI: 10.1371/journal.pone.0150880] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 02/20/2016] [Indexed: 01/16/2023] Open
Abstract
Signalling through gap junctions contributes to control insulin secretion and, thus, blood glucose levels. Gap junctions of the insulin-producing β-cells are made of connexin 36 (Cx36), which is encoded by the GJD2 gene. Cx36-null mice feature alterations mimicking those observed in type 2 diabetes (T2D). GJD2 is also expressed in neurons, which share a number of common features with pancreatic β-cells. Given that a synonymous exonic single nucleotide polymorphism of human Cx36 (SNP rs3743123) associates with altered function of central neurons in a subset of epileptic patients, we investigated whether this SNP also caused alterations of β-cell function. Transfection of rs3743123 cDNA in connexin-lacking HeLa cells resulted in altered formation of gap junction plaques and cell coupling, as compared to those induced by wild type (WT) GJD2 cDNA. Transgenic mice expressing the very same cDNAs under an insulin promoter revealed that SNP rs3743123 expression consistently lead to a post-natal reduction of islet Cx36 levels and β-cell survival, resulting in hyperglycemia in selected lines. These changes were not observed in sex- and age-matched controls expressing WT hCx36. The variant GJD2 only marginally associated to heterogeneous populations of diabetic patients. The data document that a silent polymorphism of GJD2 is associated with altered β-cell function, presumably contributing to T2D pathogenesis.
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Affiliation(s)
- Valentina Cigliola
- Department of Genetic Medicine and Development, University of Geneva Faculty of Medicine, Geneva, Switzerland
| | - Celine Populaire
- Centre Hospitalier Régional Universitaire Besançon, Besançon, France
| | - Ciro L. Pierri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Samuel Deutsch
- Joint Genome Institute, Walnut Creek, California, United States of America
| | | | - João Fadista
- Department of Clinical Sciences, Diabetes and Endocrinology, Lund University, Malmö, Sweden
| | - Valeriya Lyssenko
- Department of Clinical Sciences, Diabetes and Endocrinology, Lund University, Malmö, Sweden
- Steno Diabetes Center A/S, Gentofte, Denmark
| | - Leif Groop
- Department of Clinical Sciences, Diabetes and Endocrinology, Lund University, Malmö, Sweden
| | - Rico Rueedi
- Department of Computational Biology, University of Lausanne, Rue du Bugnon 27, 1011, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, 1015, Lausanne, Switzerland
| | - Fabrizio Thorel
- Department of Genetic Medicine and Development, University of Geneva Faculty of Medicine, Geneva, Switzerland
| | - Pedro Luis Herrera
- Department of Genetic Medicine and Development, University of Geneva Faculty of Medicine, Geneva, Switzerland
| | - Paolo Meda
- Department of Cell Physiology and Metabolism, University of Geneva Faculty of Medicine, Geneva, Switzerland
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22
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Farnsworth NL, Walter RL, Hemmati A, Westacott MJ, Benninger RKP. Low Level Pro-inflammatory Cytokines Decrease Connexin36 Gap Junction Coupling in Mouse and Human Islets through Nitric Oxide-mediated Protein Kinase Cδ. J Biol Chem 2016; 291:3184-96. [PMID: 26668311 PMCID: PMC4751367 DOI: 10.1074/jbc.m115.679506] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 12/07/2015] [Indexed: 11/06/2022] Open
Abstract
Pro-inflammatory cytokines contribute to the decline in islet function during the development of diabetes. Cytokines can disrupt insulin secretion and calcium dynamics; however, the mechanisms underlying this are poorly understood. Connexin36 gap junctions coordinate glucose-induced calcium oscillations and pulsatile insulin secretion across the islet. Loss of gap junction coupling disrupts these dynamics, similar to that observed during the development of diabetes. This study investigates the mechanisms by which pro-inflammatory cytokines mediate gap junction coupling. Specifically, as cytokine-induced NO can activate PKCδ, we aimed to understand the role of PKCδ in modulating cytokine-induced changes in gap junction coupling. Isolated mouse and human islets were treated with varying levels of a cytokine mixture containing TNF-α, IL-1β, and IFN-γ. Islet dysfunction was measured by insulin secretion, calcium dynamics, and gap junction coupling. Modulators of PKCδ and NO were applied to determine their respective roles in modulating gap junction coupling. High levels of cytokines caused cell death and decreased insulin secretion. Low levels of cytokine treatment disrupted calcium dynamics and decreased gap junction coupling, in the absence of disruptions to insulin secretion. Decreases in gap junction coupling were dependent on NO-regulated PKCδ, and altered membrane organization of connexin36. This study defines several mechanisms underlying the disruption to gap junction coupling under conditions associated with the development of diabetes. These mechanisms will allow for greater understanding of islet dysfunction and suggest ways to ameliorate this dysfunction during the development of diabetes.
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Affiliation(s)
- Nikki L Farnsworth
- From the Barbara Davis Center for Childhood Diabetes, Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045
| | - Rachelle L Walter
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045
| | - Alireza Hemmati
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045
| | - Matthew J Westacott
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045
| | - Richard K P Benninger
- From the Barbara Davis Center for Childhood Diabetes, Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045
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23
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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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24
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Dolenšek J, Špelič D, Skelin Klemen M, Žalik B, Gosak M, Slak Rupnik M, Stožer A. Membrane Potential and Calcium Dynamics in Beta Cells from Mouse Pancreas Tissue Slices: Theory, Experimentation, and Analysis. SENSORS 2015; 15:27393-419. [PMID: 26516866 PMCID: PMC4701238 DOI: 10.3390/s151127393] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/11/2015] [Accepted: 10/14/2015] [Indexed: 12/17/2022]
Abstract
Beta cells in the pancreatic islets of Langerhans are precise biological sensors for glucose and play a central role in balancing the organism between catabolic and anabolic needs. A hallmark of the beta cell response to glucose are oscillatory changes of membrane potential that are tightly coupled with oscillatory changes in intracellular calcium concentration which, in turn, elicit oscillations of insulin secretion. Both membrane potential and calcium changes spread from one beta cell to the other in a wave-like manner. In order to assess the properties of the abovementioned responses to physiological and pathological stimuli, the main challenge remains how to effectively measure membrane potential and calcium changes at the same time with high spatial and temporal resolution, and also in as many cells as possible. To date, the most wide-spread approach has employed the electrophysiological patch-clamp method to monitor membrane potential changes. Inherently, this technique has many advantages, such as a direct contact with the cell and a high temporal resolution. However, it allows one to assess information from a single cell only. In some instances, this technique has been used in conjunction with CCD camera-based imaging, offering the opportunity to simultaneously monitor membrane potential and calcium changes, but not in the same cells and not with a reliable cellular or subcellular spatial resolution. Recently, a novel family of highly-sensitive membrane potential reporter dyes in combination with high temporal and spatial confocal calcium imaging allows for simultaneously detecting membrane potential and calcium changes in many cells at a time. Since the signals yielded from both types of reporter dyes are inherently noisy, we have developed complex methods of data denoising that permit for visualization and pixel-wise analysis of signals. Combining the experimental approach of high-resolution imaging with the advanced analysis of noisy data enables novel physiological insights and reassessment of current concepts in unprecedented detail.
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Affiliation(s)
- Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (J.D.); (M.S.K.); (M.G.); (M.S.R.)
| | - Denis Špelič
- Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (D.Š.); (B.Ž.)
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (J.D.); (M.S.K.); (M.G.); (M.S.R.)
| | - Borut Žalik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (D.Š.); (B.Ž.)
- Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (J.D.); (M.S.K.); (M.G.); (M.S.R.)
- Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (J.D.); (M.S.K.); (M.G.); (M.S.R.)
- Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (J.D.); (M.S.K.); (M.G.); (M.S.R.)
- Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +386-2-2345843
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Babič A, Lamprianou S, Vinet L, Stransky-Heilkron N, Xayaphoummine C, Campo MA, Glombik H, Schulte A, Juretschke HP, Montet X, Meda P, Lange N. Multivalent glibenclamide to generate islet specific imaging probes. Biomaterials 2015; 75:1-12. [PMID: 26474038 DOI: 10.1016/j.biomaterials.2015.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 09/29/2015] [Accepted: 10/01/2015] [Indexed: 12/16/2022]
Abstract
The monitoring of diabetes mellitus, as it develops and becomes clinically evident, remains a major challenge for diagnostic imaging in clinical practice. Here we present a novel approach to beta-cell imaging by targeting the sulphonylurea receptor subtype 1 (SUR1), using multivalent derivatives of the anti-diabetic drug glibenclamide. Since glibenclamide has a high affinity for SUR1 but does not contain a suitable functional group to be linked to an imaging probe, we have synthesized 11 glibenclamide derivatives and evaluated their affinity to SUR1 in MIN6 cells. The most promising compound has been used to obtain multivalent glibenclamide-polyamidoamine (PAMAM) derivatives, containing up to 15 sulphonylurea moieties per dendrimer. The remaining functional groups on the dendrimers can consecutively be used for labeling with reporter groups for different imaging modalities, thus allowing for multifunctional imaging, and for the modification of pharmacokinetic properties. We synthesized fluorochrome-labeled multivalent probes, that demonstrate in cellular assays affinities to SUR1 in the nanomolar range, superior to native glibenclamide. The probes specifically label MIN6 cells, but not HeLa or PANC-1 cells which do not express SUR1. A very low cytotoxicity of the multivalent probes is demonstrated by the persistent release of insulin from MIN6 cells exposed to high glucose concentrations. Furthermore, the probes display positive labeling of beta-cells of primary mouse and human islet-cells ex vivo and of islets of Langerhans in vivo. The data document that multivalent probes based on glibenclamide derivatives provide a suitable platform for further developments of cell-specific probes, and can be adapted for multiple imaging modalities, including those that are now used in the clinics.
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Affiliation(s)
- Andrej Babič
- School of Pharmaceutical Sciences Geneva-Lausanne, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Smaragda Lamprianou
- Department of Cell Physiology and Metabolism, University of Geneva Medical School, Geneva, Switzerland
| | - Laurent Vinet
- Department of Radiology, Geneva University Hospital, Geneva, Switzerland
| | - Nathalie Stransky-Heilkron
- School of Pharmaceutical Sciences Geneva-Lausanne, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Celine Xayaphoummine
- School of Pharmaceutical Sciences Geneva-Lausanne, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Marino A Campo
- School of Pharmaceutical Sciences Geneva-Lausanne, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Heiner Glombik
- Sanofi Germany, Industriepark Höchst, Frankfurt, Germany
| | - Anke Schulte
- Sanofi Germany, Industriepark Höchst, Frankfurt, Germany
| | | | - Xavier Montet
- Department of Radiology, Geneva University Hospital, Geneva, Switzerland
| | - Paolo Meda
- Department of Cell Physiology and Metabolism, University of Geneva Medical School, Geneva, Switzerland
| | - Norbert Lange
- School of Pharmaceutical Sciences Geneva-Lausanne, University of Geneva, University of Lausanne, Geneva, Switzerland.
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Striegel DA, Hara M, Periwal V. The Beta Cell in Its Cluster: Stochastic Graphs of Beta Cell Connectivity in the Islets of Langerhans. PLoS Comput Biol 2015; 11:e1004423. [PMID: 26266953 PMCID: PMC4534467 DOI: 10.1371/journal.pcbi.1004423] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 07/02/2015] [Indexed: 12/25/2022] Open
Abstract
Pancreatic islets of Langerhans consist of endocrine cells, primarily α, β and δ cells, which secrete glucagon, insulin, and somatostatin, respectively, to regulate plasma glucose. β cells form irregular locally connected clusters within islets that act in concert to secrete insulin upon glucose stimulation. Due to the central functional significance of this local connectivity in the placement of β cells in an islet, it is important to characterize it quantitatively. However, quantification of the seemingly stochastic cytoarchitecture of β cells in an islet requires mathematical methods that can capture topological connectivity in the entire β-cell population in an islet. Graph theory provides such a framework. Using large-scale imaging data for thousands of islets containing hundreds of thousands of cells in human organ donor pancreata, we show that quantitative graph characteristics differ between control and type 2 diabetic islets. Further insight into the processes that shape and maintain this architecture is obtained by formulating a stochastic theory of β-cell rearrangement in whole islets, just as the normal equilibrium distribution of the Ornstein-Uhlenbeck process can be viewed as the result of the interplay between a random walk and a linear restoring force. Requiring that rearrangements maintain the observed quantitative topological graph characteristics strongly constrained possible processes. Our results suggest that β-cell rearrangement is dependent on its connectivity in order to maintain an optimal cluster size in both normal and T2D islets. High or low blood glucose levels are detrimental to human health. The hormone-secreting cells primarily responsible for maintaining glucose at physiologically appropriate levels are embedded in small clusters within the pancreas, the so-called islets of Langerhans. These islets have an irregular arrangement of cells, β cells that secrete insulin, α cells that secrete glucagon, and other cells with less well-understood functions. While the arrangement of β cells is irregular, these cells need to be touching for the islet to respond to glucose with insulin secretion. We first use a mathematical formalism called graph theory to show that cell arrangements in islets from diabetic and control donors are significantly different. The question we then address is: Is there some set of moves of islet cells that will preserve the observed arrangement? The aim is to gain insight into the biological processes by which islets are formed and maintained. We find moves on β-cell graphs that leave the same significant aspects of cell arrangements unchanged. These moves turn out to be severely restricted, and suggest that β cells may prefer to move from larger clusters but can move to a cluster of any size, possibly to maximize their exposure to blood vessels.
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Affiliation(s)
- Deborah A. Striegel
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Manami Hara
- Department of Medicine, University of Chicago, Chicago, Illinois, United States of America
| | - Vipul Periwal
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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27
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Different gap junction-propagated effects on cisplatin transfer result in opposite responses to cisplatin in normal cells versus tumor cells. Sci Rep 2015. [PMID: 26215139 PMCID: PMC4517168 DOI: 10.1038/srep12563] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Previous work has shown that gap junction intercellular communication (GJIC) enhances cisplatin (Pt) toxicity in testicular tumor cells but decreases it in non-tumor testicular cells. In this study, these different GJIC-propagated effects were demonstrated in tumor versus non-tumor cells from other organ tissues (liver and lung). The downregulation of GJIC by several different manipulations (no cell contact, pharmacological inhibition, and siRNA suppression) decreased Pt toxicity in tumor cells but enhanced it in non-tumor cells. The in vivo results using xenograft tumor models were consistent with those from the above-mentioned cells. To better understand the mechanism(s) involved, we studied the effects of GJIC on Pt accumulation in tumor and non-tumor cells from the liver and lung. The intracellular Pt and DNA-Pt adduct contents clearly increased in non-tumor cells but decreased in tumor cells when GJIC was downregulated. Further analysis indicated that the opposite effects of GJIC on Pt accumulation in normal versus tumor cells from the liver were due to its different effects on copper transporter1 and multidrug resistance-associated protein2, membrane transporters attributed to intracellular Pt transfer. Thus, GJIC protects normal organs from cisplatin toxicity while enhancing it in tumor cells via its different effects on intracellular Pt transfer.
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28
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Vinet L, Lamprianou S, Babič A, Lange N, Thorel F, Herrera PL, Montet X, Meda P. Targeting GLP-1 receptors for repeated magnetic resonance imaging differentiates graded losses of pancreatic beta cells in mice. Diabetologia 2015; 58:304-12. [PMID: 25413047 PMCID: PMC4287680 DOI: 10.1007/s00125-014-3442-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 10/17/2014] [Indexed: 12/22/2022]
Abstract
AIMS/HYPOTHESIS Non-invasive imaging of beta cells is a much-needed development but is one that faces significant biological and technological hurdles. A relevant imaging method should at least allow for an evaluation over time of the mass of beta cells under physiological and pathological conditions, and for an assessment of novel therapies. We, therefore, investigated the ability of a new MRI probe to repeatedly measure the loss of beta cells in a rodent model. METHODS We developed an innovative nanoparticle probe that targets the glucagon-like peptide 1 receptor, and can be used for both fluorescence imaging and MRI. Using fluorescence, we characterised the specificity and biodistribution of the probe. Using 1.5 T MRI, we longitudinally imaged the changes in insulin content in male and female mice of the RIP-DTr strain, which mimic the changes expected in type 1 and type 2 diabetes, respectively. RESULTS We showed that this probe selectively labelled beta cells in situ, imaged in vivo native pancreatic islets and evaluated their loss after diphtheria toxin administration, in a model of graded beta cell deletion. Thus, using clinical MRI, the probe quantitatively differentiates, in the same mouse strain, between female animals featuring a 50% loss of beta cells and the males featuring an almost complete loss of beta cells. CONCLUSIONS/INTERPRETATION The approach addresses several of the hurdles that have so far limited the non-invasive imaging of beta cells, including the potential to repeatedly monitor the very same animals using clinically available equipment, and to differentiate graded losses of beta cells.
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Affiliation(s)
- Laurent Vinet
- Department of Genetic Medicine and Development, University of Geneva, Geneva, CMU, 1 rue Michel-Servet, CH-1211, Geneva 4, Switzerland,
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29
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Pseudoislet formation enhances gene expression, insulin secretion and cytoprotective mechanisms of clonal human insulin-secreting 1.1B4 cells. Pflugers Arch 2015; 467:2219-28. [DOI: 10.1007/s00424-014-1681-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/08/2014] [Accepted: 12/18/2014] [Indexed: 12/31/2022]
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30
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Gerber PA, Bellomo EA, Hodson DJ, Meur G, Solomou A, Mitchell RK, Hollinshead M, Chimienti F, Bosco D, Hughes SJ, Johnson PRV, Rutter GA. Hypoxia lowers SLC30A8/ZnT8 expression and free cytosolic Zn2+ in pancreatic beta cells. Diabetologia 2014; 57:1635-44. [PMID: 24865615 PMCID: PMC4079946 DOI: 10.1007/s00125-014-3266-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 04/23/2014] [Indexed: 12/16/2022]
Abstract
AIMS/HYPOTHESIS Hypoxic damage complicates islet isolation for transplantation and may contribute to beta cell failure in type 2 diabetes. Polymorphisms in the SLC30A8 gene, encoding the secretory granule zinc transporter 8 (ZnT8), influence type 2 diabetes risk, conceivably by modulating cytosolic Zn(2+) levels. We have therefore explored the role of ZnT8 and cytosolic Zn(2+) in the response to hypoxia of pancreatic islet cells. METHODS Human, mouse or rat islets were isolated and exposed to varying O2 tensions. Cytosolic free zinc was measured using the adenovirally expressed recombinant targeted zinc probe eCALWY4. Gene expression was measured using quantitative (q)RT-PCR, western (immuno-) blotting or immunocytochemistry. Beta cells were identified by insulin immunoreactivity. RESULTS Deprivation of O2 (1% vs 5% or 21%) for 24 h lowered free cytosolic Zn(2+) concentrations by ~40% (p < 0.05) and ~30% (p < 0.05) in mouse and human islet cells, respectively. Hypoxia similarly decreased SLC30A8 mRNA expression in islets, and immunoreactivity in beta cells. Implicating lowered ZnT8 levels in the hypoxia-induced fall in cytosolic Zn(2+), genetic ablation of Slc30a8 from mouse islets lowered cytosolic Zn(2+) by ~40% (p < 0.05) and decreased the induction of metallothionein (Mt1, Mt2) genes. Cell survival in the face of hypoxia was enhanced in small islets of older (>12 weeks) Slc30a8 null mice vs controls, but not younger animals. CONCLUSIONS/INTERPRETATION The response of pancreatic beta cells to hypoxia is characterised by decreased SLC30A8 expression and lowered cytosolic Zn(2+) concentrations. The dependence on ZnT8 of hypoxia-induced changes in cell survival may contribute to the actions of SLC30A8 variants on diabetes risk in humans.
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Affiliation(s)
- Philipp A. Gerber
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
- Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital Zurich, Zurich, Switzerland
| | - Elisa A. Bellomo
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
| | - David J. Hodson
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
| | - Gargi Meur
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
| | - Antonia Solomou
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
| | - Ryan K. Mitchell
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
| | - Michael Hollinshead
- Section of Microscopy, Department of Medicine, Imperial College London, London, UK
| | | | - Domenico Bosco
- Cell Isolation and Transplantation Centre, Department of Surgery, Geneva University Hospital, Geneva, Switzerland
| | - Stephen J. Hughes
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
- DRWF Human Islet Isolation Facility, Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford, UK
- Oxford NIHR Biomedical Research Centre, Oxford, UK
| | - Paul R. V. Johnson
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
- DRWF Human Islet Isolation Facility, Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford, UK
- Oxford NIHR Biomedical Research Centre, Oxford, UK
| | - Guy A. Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
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Benninger RKP, Piston DW. Cellular communication and heterogeneity in pancreatic islet insulin secretion dynamics. Trends Endocrinol Metab 2014; 25:399-406. [PMID: 24679927 PMCID: PMC4112137 DOI: 10.1016/j.tem.2014.02.005] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 02/21/2014] [Accepted: 02/25/2014] [Indexed: 11/20/2022]
Abstract
Coordinated pulses of electrical activity and insulin secretion are a hallmark of the islet of Langerhans. These coordinated behaviors are lost when β cells are dissociated, which also leads to increased insulin secretion at low glucose levels. Islets without gap junctions exhibit asynchronous electrical activity similar to dispersed cells, but their secretion at low glucose levels is still clamped off, putatively by a juxtacrine mechanism. Mice lacking β cell gap junctions have near-normal average insulin levels, but are glucose intolerant due to reduced first-phase and pulsatile insulin secretion, illustrating the importance of temporal dynamics. Here, we review the quantitative data on islet synchronization and the current mathematical models that have been developed to explain these behaviors and generate greater understanding of the underlying mechanisms.
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Affiliation(s)
- Richard K P Benninger
- Department of Bioengineering and Barbara Davis Center, University of Colorado Anschutz Medical campus, Aurora, CO, USA.
| | - David W Piston
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN, USA.
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32
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d Oliveira RB, Carvalho CPDF, Polo CC, Dorighello GDG, Boschero AC, d Oliveira HCF, Collares-Buzato CB. Impaired compensatory beta-cell function and growth in response to high-fat diet in LDL receptor knockout mice. Int J Exp Pathol 2014; 95:296-308. [PMID: 24853046 PMCID: PMC4170972 DOI: 10.1111/iep.12084] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Accepted: 04/06/2014] [Indexed: 12/28/2022] Open
Abstract
In this study, we investigated the effect of low density lipoprotein receptor (LDLr) deficiency on gap junctional connexin 36 (Cx36) islet content and on the functional and growth response of pancreatic beta-cells in C57BL/6 mice fed a high-fat (HF) diet. After 60 days on regular or HF diet, the metabolic state and morphometric islet parameters of wild-type (WT) and LDLr-/- mice were assessed. HF diet-fed WT animals became obese and hypercholesterolaemic as well as hyperglycaemic, hyperinsulinaemic, glucose intolerant and insulin resistant, characterizing them as prediabetic. Also they showed a significant decrease in beta-cell secretory response to glucose. Overall, LDLr-/- mice displayed greater susceptibility to HF diet as judged by their marked cholesterolaemia, intolerance to glucose and pronounced decrease in glucose-stimulated insulin secretion. HF diet induced similarly in WT and LDLr-/- mice, a significant decrease in Cx36 beta-cell content as revealed by immunoblotting. Prediabetic WT mice displayed marked increase in beta-cell mass mainly due to beta-cell hypertrophy/replication. Nevertheless, HF diet-fed LDLr-/- mice showed no significant changes in beta-cell mass, but lower islet-duct association (neogenesis) and higher beta-cell apoptosis index were seen as compared to controls. The higher metabolic susceptibility to HF diet of LDLr-/- mice may be explained by a deficiency in insulin secretory response to glucose associated with lack of compensatory beta-cell expansion.
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Affiliation(s)
- Ricardo B d Oliveira
- Department of Histology and Embryology, University of Campinas (UNICAMP), Campinas, SP, Brazil
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33
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Saito C, Shinzawa K, Tsujimoto Y. Synchronized necrotic death of attached hepatocytes mediated via gap junctions. Sci Rep 2014; 4:5169. [PMID: 24893927 PMCID: PMC4044626 DOI: 10.1038/srep05169] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 05/14/2014] [Indexed: 01/08/2023] Open
Abstract
Extensive studies have unveiled the intracellular molecular signaling pathways of cell death. To better understand cell death in tissues, it is important to investigate the influence of neighboring cells on the response to death stimuli. By time-lapse microscopy, we found that cells in couplets (two hepatocytes attached to each other) died independently when stimulated with anti-Fas antibody and staurosporine, whereas acetaminophen (APAP) and aryl alcohol caused synchronized cell death although its timing varied among different couplets. Synchronized death of couplets was not caused by APAP when hepatocytes were deficient in both Connexin26 and Connexin32, indicating a crucial role of gap junctions in the synchronized death process. We also demonstrated that APAP-sensitive male hepatocytes were protected by attachment to APAP-insensitive female hepatocytes, with this protection being dependent on gap junctions. These findings indicate that APAP-induced and aryl alcohol-induced necrotic death of hepatocytes is modulated by attached neighboring cells via gap junctions.
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Affiliation(s)
- Chieko Saito
- Japan Society for the Promotion of Science (JSPS), Japan
- Department of Medical Genetics, Osaka University Medical School, Osaka, Japan
| | - Koei Shinzawa
- Department of Medical Genetics, Osaka University Medical School, Osaka, Japan
| | - Yoshihide Tsujimoto
- Department of Medical Genetics, Osaka University Medical School, Osaka, Japan
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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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35
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Stamper IJ, Jackson E, Wang X. Phase transitions in pancreatic islet cellular networks and implications for type-1 diabetes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:012719. [PMID: 24580269 PMCID: PMC4172977 DOI: 10.1103/physreve.89.012719] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Indexed: 06/03/2023]
Abstract
In many aspects the onset of a chronic disease resembles a phase transition in a complex dynamic system: Quantitative changes accumulate largely unnoticed until a critical threshold is reached, which causes abrupt qualitative changes of the system. In this study we examine a special case, the onset of type-1 diabetes (T1D), a disease that results from loss of the insulin-producing pancreatic islet β cells. Within each islet, the β cells are electrically coupled to each other via gap-junctional channels. This intercellular coupling enables the β cells to synchronize their insulin release, thereby generating the multiscale temporal rhythms in blood insulin that are critical to maintaining blood glucose homeostasis. Using percolation theory we show how normal islet function is intrinsically linked to network connectivity. In particular, the critical amount of β-cell death at which the islet cellular network loses site percolation is consistent with laboratory and clinical observations of the threshold loss of β cells that causes islet functional failure. In addition, numerical simulations confirm that the islet cellular network needs to be percolated for β cells to synchronize. Furthermore, the interplay between site percolation and bond strength predicts the existence of a transient phase of islet functional recovery after onset of T1D and introduction of treatment, potentially explaining the honeymoon phenomenon. Based on these results, we hypothesize that the onset of T1D may be the result of a phase transition of the islet β-cell network.
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Affiliation(s)
- I. J. Stamper
- Department of Physics, the University of Alabama at Birmingham, Birmingham, Alabama, USA
- The Comprehensive Diabetes Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Elais Jackson
- Department of Computer and Information Sciences, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Xujing Wang
- Department of Physics, the University of Alabama at Birmingham, Birmingham, Alabama, USA
- The Comprehensive Diabetes Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
- Systems Biology Center, the National Heart, Lung, and Blood Institute, the National Institutes of Health, Bethesda, Maryland, USA
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36
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Pérez-Armendariz EM. Connexin 36, a key element in pancreatic beta cell function. Neuropharmacology 2013; 75:557-66. [PMID: 23973309 DOI: 10.1016/j.neuropharm.2013.08.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 08/05/2013] [Accepted: 08/07/2013] [Indexed: 12/01/2022]
Abstract
The prevalence of diabetes at a global scale has markedly increased during the last three decades. Diabetes is a chronic disease that includes a group of metabolic disorders, in which high serum glucose levels is a common factor. Insulin is the only hormone that decreases serum glucose levels. Therefore, it is relevant to deepen our understanding of cell mechanisms that regulate insulin production and release. Insulin is produced in pancreatic islet beta cells. They are excitable cells and most of them are electrically coupled through gap junction channels. Connexin 36 (Cx36) has been identified at junctional membranes of islet beta cells in both rodents and humans. Co-localization of Cx36 with Cx30.2 has been recently identified. Functional studies in Cx36 deficient mice have provided direct evidence that Cx36 gap junction channels are necessary for the synchronization of [Ca(2+)]i oscillations in islet beta cells. The latter allows for the generation of insulin pulses in a single perfused islet. Moreover, Cx36 deficient mice were found to have altered serum insulin pulse dynamics and to be glucose intolerant. In addition, Cx36 has been recently identified as an early gene that is specifically expressed in embryonic beta cells, whose transcript and protein are upregulated in unison with the main wave of beta cell differentiation. In conclusion, Cx36 is critical for endocrine pancreatic function and may represent a molecular target for future prevention and treatment of diabetes. This article is part of the Special Issue Section entitled 'Current Pharmacology of Gap Junction Channels and Hemichannels'.
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Affiliation(s)
- E Martha Pérez-Armendariz
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, UNAM, México D.F. 04510, Mexico; Hospital General de México, Hospital General de México/Unidad de Medicina Experimental, Facultad de Medicina, UNAM, Dr Balmis 148, Colonia Doctores, Delegación Cuahutémoc, CP 06726 Ciudad de México, Mexico; Departamento of Biología Celular yTisular, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, UNAM, Mexico D.F. 04510, Mexico.
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37
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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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38
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Vasu S, McClenaghan NH, McCluskey JT, Flatt PR. Cellular responses of novel human pancreatic β-cell line, 1.1B4 to hyperglycemia. Islets 2013; 5:170-7. [PMID: 23985558 DOI: 10.4161/isl.26184] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The novel human-derived pancreatic β-cell line, 1.1B4 exhibits insulin secretion and β-cell enriched gene expression. Recent investigations of the cellular responses of this novel cell line to lipotoxicity and cytokine toxicity revealed similarities to primary human β cells. The current study has investigated the responses of 1.1B4 cells to chronic 48 and 72 h exposure to hyperglycemia to probe mechanisms of human β-cell dysfunction and cell death. Exposure to 25 mM glucose significantly reduced insulin content (p<0.05) and glucokinase activity (p<0.01) after 72 h. Basal insulin release was unaffected but acute secretory response to 16.7 mM glucose was impaired (p<0.05). Insulin release stimulated by alanine, GLP-1, KCl, elevated Ca (2+) and forskolin was also markedly reduced after exposure to hyperglycemia (p<0.001). In addition, PDX1 protein expression was reduced by 58% by high glucose (p<0.05). Effects of hyperglycemia on secretory function were accompanied by decreased mRNA expression of INS, GCK, PCSK1, PCSK2, PPP3CB, GJA1, ABCC8, and KCNJ11. In contrast, exposure to hyperglycemia upregulated the transcription of GPX1, an antioxidant enzyme involved in detoxification of hydrogen peroxide and HSPA4, a molecular chaperone involved in ER stress response. Hyperglycemia-induced DNA damage was demonstrated by increased % tail DNA and olive tail moment, assessed by comet assay. Hyperglycemia-induced apoptosis was evident from increased activity of caspase 3/7 and decreased BCL2 protein. These observations reveal significant changes in cellular responses and gene expression in novel human pancreatic 1.1B4 β cells exposed to hyperglycemia, illustrating the usefulness of this novel human-derived cell line for studying human β-cell biology and diabetes.
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Affiliation(s)
- Srividya Vasu
- SAAD Centre for Pharmacy and Diabetes; University of Ulster; Coleraine, Northern Ireland, UK
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39
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Endothelial control of vasodilation: integration of myoendothelial microdomain signalling and modulation by epoxyeicosatrienoic acids. Pflugers Arch 2013; 466:389-405. [PMID: 23748495 DOI: 10.1007/s00424-013-1303-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 05/24/2013] [Accepted: 05/26/2013] [Indexed: 12/17/2022]
Abstract
Endothelium-derived epoxyeicosatrienoic acids (EETs) are fatty acid epoxides that play an important role in the control of vascular tone in selected coronary, renal, carotid, cerebral and skeletal muscle arteries. Vasodilation due to endothelium-dependent smooth muscle hyperpolarization (EDH) has been suggested to involve EETs as a transferable endothelium-derived hyperpolarizing factor. However, this activity may also be due to EETs interacting with the components of other primary EDH-mediated vasodilator mechanisms. Indeed, the transfer of hyperpolarization initiated in the endothelium to the adjacent smooth muscle via gap junction connexins occurs separately or synergistically with the release of K(+) ions at discrete myoendothelial microdomain signalling sites. The net effects of such activity are smooth muscle hyperpolarization, closure of voltage-dependent Ca(2+) channels, phospholipase C deactivation and vasodilation. The spatially localized and key components of the microdomain signalling complex are the inositol 1,4,5-trisphosphate receptor-mediated endoplasmic reticulum Ca(2+) store, Ca(2+)-activated K(+) (KCa), transient receptor potential (TRP) and inward-rectifying K(+) channels, gap junctions and the smooth muscle Na(+)/K(+)-ATPase. Of these, TRP channels and connexins are key endothelial effector targets modulated by EETs. In an integrated manner, endogenous EETs enhance extracellular Ca(2+) influx (thereby amplifying and prolonging KCa-mediated endothelial hyperpolarization) and also facilitate the conduction of this hyperpolarization to spatially remote vessel regions. The contribution of EETs and the receptor and channel subtypes involved in EDH-related microdomain signalling, as a candidate for a universal EDH-mediated vasodilator mechanism, vary with vascular bed, species, development and disease and thus represent potentially selective targets for modulating specific artery function.
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40
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Regulation of gap junctions in melanoma and their impact on Melan-A/MART-1-specific CD8⁺ T lymphocyte emergence. J Mol Med (Berl) 2013; 91:1207-20. [PMID: 23744108 DOI: 10.1007/s00109-013-1058-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 05/15/2013] [Accepted: 05/16/2013] [Indexed: 10/26/2022]
Abstract
UNLABELLED Gap junctions (GJs) enable intercellular communication between adjacent cells through channels of connexins. Using a three-dimensional construct, we previously showed that endothelial and tumor cells formed GJs, allowing melanoma-specific T lymphocytes to recognize and kill melanoma-derived endothelial cells. We demonstrate here on histological sections of melanoma biopsies that GJ formation occurs in vivo between tumor and endothelial cells and between T lymphocytes and target cells. We also show an in vitro increase of GJ formation in melanoma and endothelial cells following dacarbazin and interferon gamma (IFN-γ) treatment or hypoxic stress induction. Our data indicate that although connexin 43 (Cx43), the main GJ protein of the immune system, was localized at the immunological synapse between T lymphocyte and autologous melanoma cells, its over-expression or inhibition of GJs does not interfere with cytotoxic T lymphocyte (CTL) clone lytic function. In contrast, we showed that inhibition of GJs by oleamide during stimulation of resting PBMCs with Melan-A natural and analog peptides resulted in a decrease in antigen (Ag) specific CD8(+) T lymphocyte induction. These Ag-specific CD8(+) cells displayed paradoxically stronger reactivity as revealed by CD107a degranulation and IFN-γ secretion. These findings indicate that Cx43 does not affect lytic function of differentiated CTL, but reveal a major role for GJs in the regulation of antigen CD8(+)-naïve T lymphocyte activation. KEY MESSAGE GJ formation occurs in vivo between T lymphocytes and tumor cells Cx43 localized at the immunological synapse between T and autologous melanoma cells Inhibition of GJs resulted in a decrease in Ag-specific CD8(+) T lymphocyte induction A role for GJs in the regulation of antigen CD8(+)-naïve T lymphocyte activation.
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41
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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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42
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Ngamjariyawat A, Turpaev K, Vasylovska S, Kozlova EN, Welsh N. Co-culture of neural crest stem cells (NCSC) and insulin producing beta-TC6 cells results in cadherin junctions and protection against cytokine-induced beta-cell death. PLoS One 2013; 8:e61828. [PMID: 23613946 PMCID: PMC3629122 DOI: 10.1371/journal.pone.0061828] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 03/13/2013] [Indexed: 01/31/2023] Open
Abstract
Purpose Transplantation of pancreatic islets to Type 1 diabetes patients is hampered by inflammatory reactions at the transplantation site leading to dysfunction and death of insulin producing beta-cells. Recently we have shown that co-transplantation of neural crest stem cells (NCSCs) together with the islet cells improves transplantation outcome. The aim of the present investigation was to describe in vitro interactions between NCSCs and insulin producing beta-TC6 cells that may mediate protection against cytokine-induced beta-cell death. Procedures Beta-TC6 and NCSC cells were cultured either alone or together, and either with or without cell culture inserts. The cultures were then exposed to the pro-inflammatory cytokines IL-1β and IFN-γ for 48 hours followed by analysis of cell death rates (flow cytometry), nitrite production (Griess reagent), protein localization (immunofluorescence) and protein phosphorylation (flow cytometry). Results We observed that beta-TC6 cells co-cultured with NCSCs were protected against cytokine-induced cell death, but not when separated by cell culture inserts. This occurred in parallel with (i) augmented production of nitrite from beta-TC6 cells, indicating that increased cell survival allows a sustained production of nitric oxide; (ii) NCSC-derived laminin production; (iii) decreased phospho-FAK staining in beta-TC6 cell focal adhesions, and (iv) decreased beta-TC6 cell phosphorylation of ERK(T202/Y204), FAK(Y397) and FAK(Y576). Furthermore, co-culture also resulted in cadherin and beta-catenin accumulations at the NCSC/beta-TC6 cell junctions. Finally, the gap junction inhibitor carbenoxolone did not affect cytokine-induced beta-cell death during co-culture with NCSCs. Conclusion In summary, direct contacts, but not soluble factors, promote improved beta-TC6 viability when co-cultured with NCSCs. We hypothesize that cadherin junctions between NCSC and beta-TC6 cells promote powerful signals that maintain beta-cell survival even though ERK and FAK signaling are suppressed. It may be that future strategies to improve islet transplantation outcome may benefit from attempts to increase beta-cell cadherin junctions to neighboring cells.
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Affiliation(s)
| | - Kyril Turpaev
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden, and Science For Life Laboratory (SciLifeLab), Uppsala University, Uppsala, Sweden
- Center for Theoretical Problems of Physicochemical Pharmacology Russian Academy of Sciences, Moscow, Russia
| | | | - Elena N. Kozlova
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
- * E-mail: (NW); (ENK)
| | - Nils Welsh
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden, and Science For Life Laboratory (SciLifeLab), Uppsala University, Uppsala, Sweden
- * E-mail: (NW); (ENK)
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43
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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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44
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Haefliger JA, Martin D, Favre D, Petremand Y, Mazzolai L, Abderrahmani A, Meda P, Waeber G, Allagnat F. Reduction of connexin36 content by ICER-1 contributes to insulin-secreting cells apoptosis induced by oxidized LDL particles. PLoS One 2013; 8:e55198. [PMID: 23383107 PMCID: PMC3559396 DOI: 10.1371/journal.pone.0055198] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 12/19/2012] [Indexed: 12/14/2022] Open
Abstract
Connexin36 (Cx36), a trans-membrane protein that forms gap junctions between insulin-secreting beta-cells in the Langerhans islets, contributes to the proper control of insulin secretion and beta-cell survival. Hypercholesterolemia and pro-atherogenic low density lipoproteins (LDL) contribute to beta-cell dysfunction and apoptosis in the context of Type 2 diabetes. We investigated the impact of LDL-cholesterol on Cx36 levels in beta-cells. As compared to WT mice, the Cx36 content was reduced in islets from hypercholesterolemic ApoE-/- mice. Prolonged exposure to human native (nLDL) or oxidized LDL (oxLDL) particles decreased the expression of Cx36 in insulin secreting cell-lines and isolated rodent islets. Cx36 down-regulation was associated with overexpression of the inducible cAMP early repressor (ICER-1) and the selective disruption of ICER-1 prevented the effects of oxLDL on Cx36 expression. Oil red O staining and Plin1 expression levels suggested that oxLDL were less stored as neutral lipid droplets than nLDL in INS-1E cells. The lipid beta-oxidation inhibitor etomoxir enhanced oxLDL-induced apoptosis whereas the ceramide synthesis inhibitor myriocin partially protected INS-1E cells, suggesting that oxLDL toxicity was due to impaired metabolism of the lipids. ICER-1 and Cx36 expressions were closely correlated with oxLDL toxicity. Cx36 knock-down in INS-1E cells or knock-out in primary islets sensitized beta-cells to oxLDL-induced apoptosis. In contrast, overexpression of Cx36 partially protected INS-1E cells against apoptosis. These data demonstrate that the reduction of Cx36 content in beta-cells by oxLDL particles is mediated by ICER-1 and contributes to oxLDL-induced beta-cell apoptosis.
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Affiliation(s)
| | - David Martin
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Dimitri Favre
- Department of Cellular Biology and Morphology, University of Lausanne, Lausanne, Switzerland
| | - Yannick Petremand
- Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - Lucia Mazzolai
- Service of Vascular Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Amar Abderrahmani
- European Genomic Institute for Diabetes, UMR 8199, University of Lille Nord de France, Lille, France
| | - Paolo Meda
- Department of Cell Physiology and Metabolism, University Medical Center, Geneva, Switzerland
| | - Gérard Waeber
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Florent Allagnat
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
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45
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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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46
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Hernández-Salinas R, Vielma AZ, Arismendi MN, Boric MP, Sáez JC, Velarde V. Boldine prevents renal alterations in diabetic rats. J Diabetes Res 2013; 2013:593672. [PMID: 24416726 PMCID: PMC3876708 DOI: 10.1155/2013/593672] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 11/06/2013] [Indexed: 11/18/2022] Open
Abstract
Diabetic nephropathy alters both structure and function of the kidney. These alterations are associated with increased levels of reactive oxygen species, matrix proteins, and proinflammatory molecules. Inflammation decreases gap junctional communication and increases hemichannel activity leading to increased membrane permeability and altering tissue homeostasis. Since current treatments for diabetic nephropathy do not prevent renal damage, we postulated an alternative treatment with boldine, an alkaloid obtained from boldo with antioxidant, anti-inflammatory, and hypoglycemic effects. Streptozotocin-induced diabetic and control rats were treated or not treated with boldine (50 mg/Kg/day) for ten weeks. In addition, mesangial cells were cultured under control conditions or in high glucose concentration plus proinflammatory cytokines, with or without boldine (100 µmol/L). Boldine treatment in diabetic animals prevented the increase in glycemia, blood pressure, renal thiobarbituric acid reactive substances and the urinary protein/creatinine ratio. Boldine also reduced alterations in matrix proteins and markers of renal damage. In mesangial cells, boldine prevented the increase in oxidative stress, the decrease in gap junctional communication, and the increase in cell permeability due to connexin hemichannel activity induced by high glucose and proinflammatory cytokines but did not block gap junction channels. Thus boldine prevented both renal and cellular alterations and could be useful for preventing tissue damage in diabetic subjects.
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Affiliation(s)
- Romina Hernández-Salinas
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda Bernardo O'Higgins, No. 340, 6513677 Santiago, Chile
| | - Alejandra Z. Vielma
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda Bernardo O'Higgins, No. 340, 6513677 Santiago, Chile
| | - Marlene N. Arismendi
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda Bernardo O'Higgins, No. 340, 6513677 Santiago, Chile
| | - Mauricio P. Boric
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda Bernardo O'Higgins, No. 340, 6513677 Santiago, Chile
| | - Juan C. Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda Bernardo O'Higgins, No. 340, 6513677 Santiago, Chile
- Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso, Valparaíso, Chile
- *Juan C. Sáez: and
| | - Victoria Velarde
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda Bernardo O'Higgins, No. 340, 6513677 Santiago, Chile
- *Victoria Velarde:
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Spray DC, Hanstein R, Lopez-Quintero SV, Stout RF, Suadicani SO, Thi MM. Gap junctions and Bystander Effects: Good Samaritans and executioners. ACTA ACUST UNITED AC 2012; 2:1-15. [PMID: 23565352 DOI: 10.1002/wmts.72] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The "Bystander" and "Good Samaritan" effects involve the transfer of toxic or beneficial compounds from one cell to a generally adjacent other through gap junction channels and through extracellular routes. The variety of injuries in which bystander cell killing or protection occurs has greatly expanded in the last decade to include infectious agents and therapeutic compounds, radiation injury, chaperones in cell therapy and apoptosis in development. This has been accompanied by the appreciation that both gap junction mediated and paracrine routes are used for the signaling of the "kiss of life" and the "kiss of death" and that manipulations of these pathways and the molecules that use them may find therapeutic utility in treatment of a variety of pathological conditions.
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Affiliation(s)
- David C Spray
- Dominick P. Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461 ; Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461
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Proteomic and metabolomic responses to connexin43 silencing in primary hepatocyte cultures. Arch Toxicol 2012; 87:883-94. [DOI: 10.1007/s00204-012-0994-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 11/27/2012] [Indexed: 12/29/2022]
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Guay C, Jacovetti C, Nesca V, Motterle A, Tugay K, Regazzi R. Emerging roles of non-coding RNAs in pancreatic β-cell function and dysfunction. Diabetes Obes Metab 2012; 14 Suppl 3:12-21. [PMID: 22928560 DOI: 10.1111/j.1463-1326.2012.01654.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Pancreatic β-cells play a central role in glucose homeostasis by tightly regulating insulin release according to the organism's demand. Impairment of β-cell function due to hostile environment, such as hyperglycaemia and hyperlipidaemia, or due to autoimmune destruction of β-cells, results in diabetes onset. Both environmental factors and genetic predisposition are known to be involved in the development of the disease, but the exact mechanisms leading to β-cell dysfunction and death remain to be characterized. Non-coding RNA molecules, such as microRNAs (miRNAs), have been suggested to be necessary for proper β-cell development and function. The present review aims at summarizing the most recent findings about the role of non-coding RNAs in the control of β-cell functions and their involvement in diabetes. We will also provide a perspective view of the future research directions in the field of non-coding RNAs. In particular, we will discuss the implications for diabetes research of the discovery of a new communication mechanism based on cell-to-cell miRNA transfer. Moreover, we will highlight the emerging interconnections between miRNAs and epigenetics and the possible role of long non-coding RNAs in the control of β-cell activities.
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Affiliation(s)
- C Guay
- Department of Cellular Biology and Morphology, University of Lausanne, Lausanne, Switzerland
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Sam AH, Gunner DJ, King A, Persaud SJ, Brooks L, Hostomska K, Ford HE, Liu B, Ghatei MA, Bloom SR, Bewick GA. Selective ablation of peptide YY cells in adult mice reveals their role in beta cell survival. Gastroenterology 2012; 143:459-68. [PMID: 22562022 DOI: 10.1053/j.gastro.2012.04.047] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 03/31/2012] [Accepted: 04/24/2012] [Indexed: 12/29/2022]
Abstract
BACKGROUND AND AIMS In the pancreas, peptide YY (PYY) is expressed by a subpopulation of nonbeta cells in the islets of Langerhans. We investigated the function of these cells in the pancreas of adult mice. METHODS We generated mice in which administration of diphtheria toxin (DT) led to specific ablation of PYY-expressing cells. We investigated the effects of loss of PYY cells on glucose homeostasis. RESULTS Loss of PYY cells in adult mice resulted in severe hyperglycemia, which was associated with significant loss of pancreatic insulin and disruption of islet morphology. In vitro administration of DT to isolated islets significantly reduced numbers of PYY-expressing cells and levels of insulin. Administration of either pancreatic polypeptide (a strong agonist of the receptor Y(4)) or PYY(3-36) (a selective agonist of the receptor Y(2)) did not restore loss of pancreatic insulin following administration of DT. However, a long-acting PYY analogue reduced the loss of insulin, and administration of this analogue reduced the hyperglycemia and insulin loss induced by streptozotocin in mice. CONCLUSIONS PYY appears to regulate beta cell function and survival via the receptor Y(1/2). These findings might be developed to treat and prevent loss of beta cells in patients with diabetes mellitus.
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