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Zaïmia N, Obeid J, Varrault A, Sabatier J, Broca C, Gilon P, Costes S, Bertrand G, Ravier MA. GLP-1 and GIP receptors signal through distinct β-arrestin 2-dependent pathways to regulate pancreatic β cell function. Cell Rep 2023; 42:113326. [PMID: 37897727 DOI: 10.1016/j.celrep.2023.113326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 09/14/2023] [Accepted: 10/07/2023] [Indexed: 10/30/2023] Open
Abstract
Glucagon-like peptide 1 (GLP-1R) and glucose-dependent insulinotropic polypeptide (GIPR) receptors are G-protein-coupled receptors involved in glucose homeostasis. Diabetogenic conditions decrease β-arrestin 2 (ARRB2) levels in human islets. In mouse β cells, ARRB2 dampens insulin secretion by partially uncoupling cyclic AMP (cAMP)/protein kinase A (PKA) signaling at physiological doses of GLP-1, whereas at pharmacological doses, the activation of extracellular signal-related kinase (ERK)/cAMP-responsive element-binding protein (CREB) requires ARRB2. In contrast, GIP-potentiated insulin secretion needs ARRB2 in mouse and human islets. The GIPR-ARRB2 axis is not involved in cAMP/PKA or ERK signaling but does mediate GIP-induced F-actin depolymerization. Finally, the dual GLP-1/GIP agonist tirzepatide does not require ARRB2 for the potentiation of insulin secretion. Thus, ARRB2 plays distinct roles in regulating GLP-1R and GIPR signaling, and we highlight (1) its role in the physiological context and the possible functional consequences of its decreased expression in pathological situations such as diabetes and (2) the importance of assessing the signaling pathways engaged by the agonists (biased/dual) for therapeutic purposes.
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Affiliation(s)
- Nour Zaïmia
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | - Joelle Obeid
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | - Annie Varrault
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | | | | | - Patrick Gilon
- Université Catholique de Louvain, Institut de Recherche Expérimental et Clinique, Pôle d'Endocrinologie, Diabète, et Nutrition, Brussels, Belgium
| | - Safia Costes
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
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Sanz-González A, Cózar-Castellano I, Broca C, Sabatier J, Acosta GA, Royo M, Hernándo-Muñoz C, Torroba T, Perdomo G, Merino B. Pharmacological activation of insulin-degrading enzyme improves insulin secretion and glucose tolerance in diet-induced obese mice. Diabetes Obes Metab 2023; 25:3268-3278. [PMID: 37493025 DOI: 10.1111/dom.15225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 07/10/2023] [Accepted: 07/10/2023] [Indexed: 07/27/2023]
Abstract
AIM To investigate the use of synthetic preimplantation factor (sPIF) as a potential therapeutic tool for improving glucose-stimulated insulin secretion (GSIS), glucose tolerance and insulin sensitivity in the setting of diabetes. MATERIALS AND METHODS We used a preclinical murine model of type 2 diabetes (T2D) induced by high-fat diet (HFD) feeding for 12 weeks. Saline or sPIF (1 mg/kg/day) was administered to mice by subcutaneously implanted osmotic mini-pumps for 25 days. Glucose tolerance, circulating insulin and C-peptide levels, and GSIS were assessed. In addition, β-cells (Min-6) were used to test the effects of sPIF on GSIS and insulin-degrading enzyme (IDE) activity in vitro. The effect of sPIF on GSIS was also tested in human islets. RESULTS GSIS was enhanced 2-fold by sPIF in human islets ex vivo. Furthermore, continuous administration of sPIF to HFD mice increased circulating levels of insulin and improved glucose tolerance, independently of hepatic insulin clearance. Of note, islets isolated from mice treated with sPIF exhibited restored β-cell function. Finally, genetic (shRNA-IDE) or pharmacological (6bK) inactivation of IDE in Min-6 abolished sPIF-mediated effects on GSIS, showing that both the protein and its protease activity are required for its action. CONCLUSIONS We conclude that sPIF is a promising secretagogue for the treatment of T2D.
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Affiliation(s)
- Alba Sanz-González
- Unidad de Excelencia Instituto de Biomedicina y Genética Molecular (IBGM), Consejo Superior de Investigaciones Científicas (CSIC) y Universidad de Valladolid (UVa), Valladolid, Spain
| | - Irene Cózar-Castellano
- Unidad de Excelencia Instituto de Biomedicina y Genética Molecular (IBGM), Consejo Superior de Investigaciones Científicas (CSIC) y Universidad de Valladolid (UVa), Valladolid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
| | - Christophe Broca
- Laboratory of Cell Therapy for Diabetes (LTCDPRIMS), IRMB Hop. St Eloi, CHU Montpellier, Montpellier, France
| | - Julia Sabatier
- Laboratory of Cell Therapy for Diabetes (LTCDPRIMS), IRMB Hop. St Eloi, CHU Montpellier, Montpellier, France
| | - Gerardo A Acosta
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBERBBN), Barcelona, Spain
- Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain
- Department of Organic Chemistry, University of Barcelona, Barcelona, Spain
| | - Miriam Royo
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBERBBN), Barcelona, Spain
- Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain
| | - Carla Hernándo-Muñoz
- Department of Chemistry, Faculty of Science, University of Burgos, Burgos, Spain
| | - Tomás Torroba
- Department of Chemistry, Faculty of Science, University of Burgos, Burgos, Spain
| | - Germán Perdomo
- Unidad de Excelencia Instituto de Biomedicina y Genética Molecular (IBGM), Consejo Superior de Investigaciones Científicas (CSIC) y Universidad de Valladolid (UVa), Valladolid, Spain
| | - Beatriz Merino
- Unidad de Excelencia Instituto de Biomedicina y Genética Molecular (IBGM), Consejo Superior de Investigaciones Científicas (CSIC) y Universidad de Valladolid (UVa), Valladolid, Spain
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Tariq M, de Souza AH, Bensellam M, Chae H, Jaffredo M, Close AF, Deglasse JP, Santos LRB, Buemi A, Mourad NI, Wojtusciszyn A, Raoux M, Gilon P, Broca C, Jonas JC. Prolonged culture of human pancreatic islets under glucotoxic conditions changes their acute beta cell calcium and insulin secretion glucose response curves from sigmoid to bell-shaped. Diabetologia 2023; 66:709-723. [PMID: 36459178 DOI: 10.1007/s00125-022-05842-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 10/18/2022] [Indexed: 12/04/2022]
Abstract
AIMS/HYPOTHESIS The rapid remission of type 2 diabetes by a diet very low in energy correlates with a marked improvement in glucose-stimulated insulin secretion (GSIS), emphasising the role of beta cell dysfunction in the early stages of the disease. In search of novel mechanisms of beta cell dysfunction after long-term exposure to mild to severe glucotoxic conditions, we extensively characterised the alterations in insulin secretion and upstream coupling events in human islets cultured for 1-3 weeks at ~5, 8, 10 or 20 mmol/l glucose and subsequently stimulated by an acute stepwise increase in glucose concentration. METHODS Human islets from 49 non-diabetic donors (ND-islets) and six type 2 diabetic donors (T2D-islets) were obtained from five isolation centres. After shipment, the islets were precultured for 3-7 days in RPMI medium containing ~5 mmol/l glucose and 10% (vol/vol) heat-inactivated FBS with selective islet picking at each medium renewal. Islets were then cultured for 1-3 weeks in RPMI containing ~5, 8, 10 or 20 mmol/l glucose before measurement of insulin secretion during culture, islet insulin and DNA content, beta cell apoptosis and cytosolic and mitochondrial glutathione redox state, and assessment of dynamic insulin secretion and upstream coupling events during acute stepwise stimulation with glucose [NAD(P)H autofluorescence, ATP/(ATP+ADP) ratio, electrical activity, cytosolic Ca2+ concentration ([Ca2+]c)]. RESULTS Culture of ND-islets for 1-3 weeks at 8, 10 or 20 vs 5 mmol/l glucose did not significantly increase beta cell apoptosis or oxidative stress but decreased insulin content in a concentration-dependent manner and increased beta cell sensitivity to subsequent acute stimulation with glucose. Islet glucose responsiveness was higher after culture at 8 or 10 vs 5 mmol/l glucose and markedly reduced after culture at 20 vs 5 mmol/l glucose. In addition, the [Ca2+]c and insulin secretion responses to acute stepwise stimulation with glucose were no longer sigmoid but bell-shaped, with maximal stimulation at 5 or 10 mmol/l glucose and rapid sustained inhibition above that concentration. Such paradoxical inhibition was, however, no longer observed when islets were acutely depolarised by 30 mmol/l extracellular K+. The glucotoxic alterations of beta cell function were fully reversible after culture at 5 mmol/l glucose and were mimicked by pharmacological activation of glucokinase during culture at 5 mmol/l glucose. Similar results to those seen in ND-islets were obtained in T2D-islets, except that their rate of insulin secretion during culture at 8 and 20 mmol/l glucose was lower, their cytosolic glutathione oxidation increased after culture at 8 and 20 mmol/l glucose, and the alterations in GSIS and upstream coupling events were greater after culture at 8 mmol/l glucose. CONCLUSIONS/INTERPRETATION Prolonged culture of human islets under moderate to severe glucotoxic conditions markedly increased their glucose sensitivity and revealed a bell-shaped acute glucose response curve for changes in [Ca2+]c and insulin secretion, with maximal stimulation at 5 or 10 mmol/l glucose and rapid inhibition above that concentration. This novel glucotoxic alteration may contribute to beta cell dysfunction in type 2 diabetes independently from a detectable increase in beta cell apoptosis.
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Affiliation(s)
- Mohammad Tariq
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
- Lund University Diabetes Centre, Department of Clinical Sciences, Lund University, Malmö, Sweden
| | - Arnaldo H de Souza
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Mohammed Bensellam
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Heeyoung Chae
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Manon Jaffredo
- CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, University of Bordeaux, Pessac, France
| | - Anne-Françoise Close
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Jean-Philippe Deglasse
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Laila R B Santos
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
- Bio Base Europe Pilot Plant (BBEPP), Ghent, Belgium
| | - Antoine Buemi
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle de chirurgie expérimentale, Université catholique de Louvain, Brussels, Belgium
| | - Nizar I Mourad
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle de chirurgie expérimentale, Université catholique de Louvain, Brussels, Belgium
| | - Anne Wojtusciszyn
- Laboratoire de Thérapie Cellulaire du Diabète, Institut de Médecine Régénérative et Biothérapies, Hôpital St Eloi, CHU Montpellier, Montpellier, France
- Service d'Endocrinologie, Diabétologie et Métabolisme, Centre Hospitalier Universitaire Vaudois and Université de Lausanne, Lausanne, Switzerland
| | - Matthieu Raoux
- CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, University of Bordeaux, Pessac, France
| | - Patrick Gilon
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Christophe Broca
- Laboratoire de Thérapie Cellulaire du Diabète, Institut de Médecine Régénérative et Biothérapies, Hôpital St Eloi, CHU Montpellier, Montpellier, France
| | - Jean-Christophe Jonas
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium.
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Fontcuberta-PiSunyer M, García-Alamán A, Prades È, Téllez N, Alves-Figueiredo H, Ramos-Rodríguez M, Enrich C, Fernandez-Ruiz R, Cervantes S, Clua L, Ramón-Azcón J, Broca C, Wojtusciszyn A, Montserrat N, Pasquali L, Novials A, Servitja JM, Vidal J, Gomis R, Gasa R. Direct reprogramming of human fibroblasts into insulin-producing cells using transcription factors. Commun Biol 2023; 6:256. [PMID: 36964318 PMCID: PMC10039074 DOI: 10.1038/s42003-023-04627-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 02/24/2023] [Indexed: 03/26/2023] Open
Abstract
Direct lineage reprogramming of one somatic cell into another without transitioning through a progenitor stage has emerged as a strategy to generate clinically relevant cell types. One cell type of interest is the pancreatic insulin-producing β cell whose loss and/or dysfunction leads to diabetes. To date it has been possible to create β-like cells from related endodermal cell types by forcing the expression of developmental transcription factors, but not from more distant cell lineages like fibroblasts. In light of the therapeutic benefits of choosing an accessible cell type as the cell of origin, in this study we set out to analyze the feasibility of transforming human skin fibroblasts into β-like cells. We describe how the timed-introduction of five developmental transcription factors (Neurog3, Pdx1, MafA, Pax4, and Nkx2-2) promotes conversion of fibroblasts toward a β-cell fate. Reprogrammed cells exhibit β-cell features including β-cell gene expression and glucose-responsive intracellular calcium mobilization. Moreover, reprogrammed cells display glucose-induced insulin secretion in vitro and in vivo. This work provides proof-of-concept of the capacity to make insulin-producing cells from human fibroblasts via transcription factor-mediated direct reprogramming.
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Affiliation(s)
| | - Ainhoa García-Alamán
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Èlia Prades
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Noèlia Téllez
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
- Faculty of Medicine of University of Vic, Central University of Catalonia (UVic-UCC), Vic, Spain
- Institute of Health Research and Innovation at Central Catalonia (IRIS-CC), Vic, Spain
| | - Hugo Alves-Figueiredo
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, N.L., México
| | | | - Carlos Enrich
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Faculty of Medicine and Health Sciences, Universitat de Barcelona, Barcelona, Spain
| | - Rebeca Fernandez-Ruiz
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Sara Cervantes
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Laura Clua
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Technology (BIST), Barcelona, Spain
| | - Javier Ramón-Azcón
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Technology (BIST), Barcelona, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
| | - Christophe Broca
- CHU Montpellier, Laboratory of Cell Therapy for Diabetes (LTCD), Hospital St-Eloi, Montpellier, France
| | - Anne Wojtusciszyn
- CHU Montpellier, Laboratory of Cell Therapy for Diabetes (LTCD), Hospital St-Eloi, Montpellier, France
- Service of Endocrinology, Diabetes and Metabolism, Lausanne University Hospital, Lausanne, Switzerland
| | - Nuria Montserrat
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Technology (BIST), Barcelona, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina, Instituto de Salud Carlos III, Madrid, Spain
| | - Lorenzo Pasquali
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Anna Novials
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Joan-Marc Servitja
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Josep Vidal
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
- Faculty of Medicine and Health Sciences, Universitat de Barcelona, Barcelona, Spain
- Endocrinology and Nutrition Department, Hospital Clinic of Barcelona, Barcelona, Spain
| | - Ramon Gomis
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
- Faculty of Medicine and Health Sciences, Universitat de Barcelona, Barcelona, Spain
| | - Rosa Gasa
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain.
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Brown MR, Laouteouet D, Delobel M, Villard O, Broca C, Bertrand G, Wojtusciszyn A, Dalle S, Ravier MA, Matveyenko AV, Costes S. The nuclear receptor REV-ERBα is implicated in the alteration of β-cell autophagy and survival under diabetogenic conditions. Cell Death Dis 2022; 13:353. [PMID: 35428762 PMCID: PMC9012816 DOI: 10.1038/s41419-022-04767-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 03/16/2022] [Accepted: 03/25/2022] [Indexed: 01/07/2023]
Abstract
Pancreatic β-cell failure in type 2 diabetes mellitus (T2DM) is associated with impaired regulation of autophagy which controls β-cell development, function, and survival through clearance of misfolded proteins and damaged organelles. However, the mechanisms responsible for defective autophagy in T2DM β-cells remain unknown. Since recent studies identified circadian clock transcriptional repressor REV-ERBα as a novel regulator of autophagy in cancer, in this study we set out to test whether REV-ERBα-mediated inhibition of autophagy contributes to the β-cell failure in T2DM. Our study provides evidence that common diabetogenic stressors (e.g., glucotoxicity and cytokine-mediated inflammation) augment β-cell REV-ERBα expression and impair β-cell autophagy and survival. Notably, pharmacological activation of REV-ERBα was shown to phenocopy effects of diabetogenic stressors on the β-cell through inhibition of autophagic flux, survival, and insulin secretion. In contrast, negative modulation of REV-ERBα was shown to provide partial protection from inflammation and glucotoxicity-induced β-cell failure. Finally, using bioinformatic approaches, we provide further supporting evidence for augmented REV-ERBα activity in T2DM human islets associated with impaired transcriptional regulation of autophagy and protein degradation pathways. In conclusion, our study reveals a previously unexplored causative relationship between REV-ERBα expression, inhibition of autophagy, and β-cell failure in T2DM.
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Affiliation(s)
- Matthew R. Brown
- grid.66875.3a0000 0004 0459 167XDepartment of Physiology and Biomedical Engineering, Mayo Clinic School of Medicine, Mayo Clinic, Rochester, MN USA
| | - Damien Laouteouet
- grid.121334.60000 0001 2097 0141Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Morgane Delobel
- grid.121334.60000 0001 2097 0141Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Orianne Villard
- grid.157868.50000 0000 9961 060XLaboratory of Cell Therapy for Diabetes (LTCD), PRIMS facility, Institute for Regenerative Medicine and Biotherapy (IRMB), University hospital of Montpellier, Montpellier, France ,grid.157868.50000 0000 9961 060XDepartment of Endocrinology, Diabetes, and Nutrition, University Hospital of Montpellier, Montpellier, France
| | - Christophe Broca
- grid.157868.50000 0000 9961 060XLaboratory of Cell Therapy for Diabetes (LTCD), PRIMS facility, Institute for Regenerative Medicine and Biotherapy (IRMB), University hospital of Montpellier, Montpellier, France
| | - Gyslaine Bertrand
- grid.121334.60000 0001 2097 0141Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Anne Wojtusciszyn
- grid.121334.60000 0001 2097 0141Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France ,grid.157868.50000 0000 9961 060XLaboratory of Cell Therapy for Diabetes (LTCD), PRIMS facility, Institute for Regenerative Medicine and Biotherapy (IRMB), University hospital of Montpellier, Montpellier, France ,grid.157868.50000 0000 9961 060XDepartment of Endocrinology, Diabetes, and Nutrition, University Hospital of Montpellier, Montpellier, France
| | - Stéphane Dalle
- grid.121334.60000 0001 2097 0141Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Magalie A. Ravier
- grid.121334.60000 0001 2097 0141Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Aleksey V. Matveyenko
- grid.66875.3a0000 0004 0459 167XDepartment of Physiology and Biomedical Engineering, Mayo Clinic School of Medicine, Mayo Clinic, Rochester, MN USA ,grid.66875.3a0000 0004 0459 167XDivision of Endocrinology, Metabolism, Diabetes, and Nutrition, Department of Medicine, Mayo Clinic, Rochester, MN USA
| | - Safia Costes
- grid.121334.60000 0001 2097 0141Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
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Chae H, Augustin R, Gatineau E, Mayoux E, Bensellam M, Antoine N, Khattab F, Lai BK, Brusa D, Stierstorfer B, Klein H, Singh B, Ruiz L, Pieper M, Mark M, Herrera PL, Gribble FM, Reimann F, Wojtusciszyn A, Broca C, Rita N, Piemonti L, Gilon P. SGLT2 is not expressed in pancreatic α- and β-cells, and its inhibition does not directly affect glucagon and insulin secretion in rodents and humans. Mol Metab 2020; 42:101071. [PMID: 32896668 PMCID: PMC7554656 DOI: 10.1016/j.molmet.2020.101071] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/13/2020] [Accepted: 08/25/2020] [Indexed: 12/22/2022] Open
Abstract
Objective Sodium-glucose cotransporter 2 (SGLT2) inhibitors (SGLT2i), or gliflozins, are anti-diabetic drugs that lower glycemia by promoting glucosuria, but they also stimulate endogenous glucose and ketone body production. The likely causes of these metabolic responses are increased blood glucagon levels, and decreased blood insulin levels, but the mechanisms involved are hotly debated. This study verified whether or not SGLT2i affect glucagon and insulin secretion by a direct action on islet cells in three species, using multiple approaches. Methods We tested the in vivo effects of two selective SGLT2i (dapagliflozin, empagliflozin) and a SGLT1/2i (sotagliflozin) on various biological parameters (glucosuria, glycemia, glucagonemia, insulinemia) in mice. mRNA expression of SGLT2 and other glucose transporters was assessed in rat, mouse, and human FACS-purified α- and β-cells, and by analysis of two human islet cell transcriptomic datasets. Immunodetection of SGLT2 in pancreatic tissues was performed with a validated antibody. The effects of dapagliflozin, empagliflozin, and sotagliflozin on glucagon and insulin secretion were assessed using isolated rat, mouse and human islets and the in situ perfused mouse pancreas. Finally, we tested the long-term effect of SGLT2i on glucagon gene expression. Results SGLT2 inhibition in mice increased the plasma glucagon/insulin ratio in the fasted state, an effect correlated with a decline in glycemia. Gene expression analyses and immunodetections showed no SGLT2 mRNA or protein expression in rodent and human islet cells, but moderate SGLT1 mRNA expression in human α-cells. However, functional experiments on rat, mouse, and human (29 donors) islets and the in situ perfused mouse pancreas did not identify any direct effect of dapagliflozin, empagliflozin or sotagliflozin on glucagon and insulin secretion. SGLT2i did not affect glucagon gene expression in rat and human islets. Conclusions The data indicate that the SGLT2i-induced increase of the plasma glucagon/insulin ratio in vivo does not result from a direct action of the gliflozins on islet cells. Gliflozins (SGLT2 and SGLT1/2 inhibitors) increase plasma glucagon/insulin ratio. SGLT2 is not expressed in rodent and human pancreatic α- and β-cells. SGLT1 is however expressed in human α-cells. SGLT2 and SGLT1/2 inhibitors do not directly affect glucagon and insulin secretion.
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Affiliation(s)
- Heeyoung Chae
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Robert Augustin
- Department of Cardiometabolic Disease Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Eva Gatineau
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Eric Mayoux
- Department of Cardiometabolic Disease Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Mohammed Bensellam
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Nancy Antoine
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Firas Khattab
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Bao-Khanh Lai
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Davide Brusa
- Flow Cytometry Platform, Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Birgit Stierstorfer
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Holger Klein
- Global Computational Biology and Data Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Bilal Singh
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Lucie Ruiz
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Michael Pieper
- Department of Cardiometabolic Disease Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Michael Mark
- Department of Cardiometabolic Disease Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Pedro L Herrera
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Fiona M Gribble
- Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
| | - Frank Reimann
- Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
| | - Anne Wojtusciszyn
- Laboratory of Cellular Therapy for Diabetes, University Hospital of Montpellier, Montpellier, France; Department of Endocrinology, Diabetes and Metabolism, Lausanne University Hospital, Lausanne, Switzerland
| | - Christophe Broca
- Laboratory of Cellular Therapy for Diabetes, University Hospital of Montpellier, Montpellier, France
| | - Nano Rita
- San Raffaele Diabetes Research Institute, IRCCS Ospedale San Raffaele, 20132, Milan, Italy
| | - Lorenzo Piemonti
- San Raffaele Diabetes Research Institute, IRCCS Ospedale San Raffaele, 20132, Milan, Italy; Università Vita-Salute San Raffaele, Milan, Italy
| | - Patrick Gilon
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium.
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7
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Castex F, Leroy J, Broca C, Mezghenna K, Duranton F, Lavallard V, Lebreton F, Gross R, Wojtusciszyn A, Lajoix AD. Differential sensitivity of human islets from obese versus lean donors to chronic high glucose or palmitate. J Diabetes 2020; 12:532-541. [PMID: 32090456 DOI: 10.1111/1753-0407.13026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 01/15/2020] [Accepted: 02/19/2020] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Due to the shortage of multi-organ donors, human pancreatic islet transplantation has now been extended to islets originating from obese subjects. In this study, our aim is to compare the respective sensitivity of human islets from lean vs obese donors to chronic high glucose or high palmitate. METHODS Human islets were isolated from pancreases harvested from brain-dead multi-organ donors. Islets were cultured during 72 hours in the presence of moderate (16.7 mmol/L) or high (28 mmoL/L) glucose concentrations, or glucose (5.6 mmoL/L) and palmitate (0.4 mmoL/L), before measurement of their response to glucose. RESULTS We first observed a greater insulin response in islets from obese donors under both basal and high-glucose conditions, confirming their hyperresponsiveness to glucose. When islets from obese donors were cultured in the presence of moderate or high glucose concentrations, insulin response to glucose remained unchanged or was slightly reduced, as opposed to that observed in lean subjects. Moreover, culturing islets from obese donors with high palmitate also induced less reduction in insulin response to glucose than in lean subjects. This partial protection of obese islets is associated with less induction of inducible nitric oxide synthase in islets, together with a greater expression of the transcription factor forkhead box O1 (FOXO1). CONCLUSIONS Our data suggest that in addition to an increased sensitivity to glucose, islets from obese subjects can be considered as more resistant to glucose and fatty acid excursions and are thus valuable candidates for transplantation.
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Affiliation(s)
- Françoise Castex
- Biocommunication in Cardio-Metabolism (BC2M), University Montpellier, Montpellier, France
| | - Jeremy Leroy
- Biocommunication in Cardio-Metabolism (BC2M), University Montpellier, Montpellier, France
| | - Christophe Broca
- Laboratory of Cell Therapy for Diabetes, Institute for Regenerative Medicine & Biotherapy (IRMB), University Montpellier, INSERM, University Hospital Montpellier, Montpellier, France
| | - Karima Mezghenna
- Biocommunication in Cardio-Metabolism (BC2M), University Montpellier, Montpellier, France
| | - Flore Duranton
- Biocommunication in Cardio-Metabolism (BC2M), University Montpellier, Montpellier, France
- RD Néphrologie, Montpellier, France
| | - Vanessa Lavallard
- Department of Surgery, Cell Isolation and Transplantation Center, Geneva University Hospitals and University of Geneva, Genève, Switzerland
| | | | - René Gross
- Biocommunication in Cardio-Metabolism (BC2M), University Montpellier, Montpellier, France
| | - Anne Wojtusciszyn
- Laboratory of Cell Therapy for Diabetes, Institute for Regenerative Medicine & Biotherapy (IRMB), University Montpellier, INSERM, University Hospital Montpellier, Montpellier, France
| | - Anne-Dominique Lajoix
- Biocommunication in Cardio-Metabolism (BC2M), University Montpellier, Montpellier, France
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8
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Figueiredo H, Figueroa ALC, Garcia A, Fernandez-Ruiz R, Broca C, Wojtusciszyn A, Malpique R, Gasa R, Gomis R. Targeting pancreatic islet PTP1B improves islet graft revascularization and transplant outcomes. Sci Transl Med 2020; 11:11/497/eaar6294. [PMID: 31217339 DOI: 10.1126/scitranslmed.aar6294] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 01/16/2019] [Accepted: 05/23/2019] [Indexed: 12/12/2022]
Abstract
Deficient vascularization is a major driver of early islet graft loss and one of the primary reasons for the failure of islet transplantation as a viable treatment for type 1 diabetes. This study identifies the protein tyrosine phosphatase 1B (PTP1B) as a potential modulator of islet graft revascularization. We demonstrate that grafts of pancreatic islets lacking PTP1B exhibit increased revascularization, which is accompanied by improved graft survival and function, and recovery of normoglycemia and glucose tolerance in diabetic mice transplanted with PTP1B-deficient islets. Mechanistically, we show that the absence of PTP1B leads to activation of hypoxia-inducible factor 1α-independent peroxisome proliferator-activated receptor γ coactivator 1α/estrogen-related receptor α signaling and enhanced expression and production of vascular endothelial growth factor A (VEGF-A) by β cells. These observations were reproduced in human islets. Together, these findings reveal that PTP1B regulates islet VEGF-A production and suggest that this phosphatase could be targeted to improve islet transplantation outcomes.
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Affiliation(s)
- Hugo Figueiredo
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), 08036 Barcelona, Spain.,University of Barcelona, 08036 Barcelona, Spain.,Escuela de Medicina y Ciencias de la Salud, Dept. Medicina Cardiovascular y Metabolómica, Tecnológico de Monterrey, 66278 San Pedro Garza García, Nuevo León, Mexico
| | - Ana Lucia C Figueroa
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), 08036 Barcelona, Spain.,University of Barcelona, 08036 Barcelona, Spain
| | - Ainhoa Garcia
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), 08036 Barcelona, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Rebeca Fernandez-Ruiz
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), 08036 Barcelona, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Christophe Broca
- CHU Montpellier, Laboratory of Cell Therapy for Diabetes (LTCD), Hospital St-Eloi, 34295 Montpellier, France
| | - Anne Wojtusciszyn
- CHU Montpellier, Laboratory of Cell Therapy for Diabetes (LTCD), Hospital St-Eloi, 34295 Montpellier, France.,Department of Endocrinology, Diabetes and Nutrition, University Hospital of Montpellier, Lapeyronie Hospital, 34295 Montpellier, France.,Service of Endocrinology, Diabetes and Metabolism, Lausanne University Hospital, 1011 Lausanne, Switzerland
| | - Rita Malpique
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), 08036 Barcelona, Spain
| | - Rosa Gasa
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), 08036 Barcelona, Spain. .,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Ramon Gomis
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), 08036 Barcelona, Spain. .,University of Barcelona, 08036 Barcelona, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain.,Universitat Oberta de Catalunya (UOC), 08018 Barcelona, Spain.,Department of Endocrinology and Nutrition, Hospital Clinic of Barcelona, 08036 Barcelona, Spain
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9
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Sarrabay G, Méchin D, Salhi A, Boursier G, Rittore C, Crow Y, Rice G, Tran TA, Cezar R, Duffy D, Bondet V, Boudhane L, Broca C, Kant BP, VanGijn M, Grandemange S, Richard E, Apparailly F, Touitou I. PSMB10, the last immunoproteasome gene missing for PRAAS. J Allergy Clin Immunol 2019; 145:1015-1017.e6. [PMID: 31783057 DOI: 10.1016/j.jaci.2019.11.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 10/26/2019] [Accepted: 11/08/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Guillaume Sarrabay
- IRMB, Univ Montpellier, INSERM, CHU Montpellier, Montpellier, France; Department of Medical Genetics, Rare Diseases and Personalized Medicine, Rare and Autoinflammatory Diseases Unit, CHU Montpellier, Univ Montpellier, Montpellier, France.
| | - Déborah Méchin
- IRMB, Univ Montpellier, INSERM, CHU Montpellier, Montpellier, France; Department of Medical Genetics, Rare Diseases and Personalized Medicine, Rare and Autoinflammatory Diseases Unit, CHU Montpellier, Univ Montpellier, Montpellier, France
| | - Aicha Salhi
- Dermatology Department, Alger Medicine University, Alger, Algeria
| | - Guilaine Boursier
- IRMB, Univ Montpellier, INSERM, CHU Montpellier, Montpellier, France; Department of Medical Genetics, Rare Diseases and Personalized Medicine, Rare and Autoinflammatory Diseases Unit, CHU Montpellier, Univ Montpellier, Montpellier, France
| | - Cécile Rittore
- IRMB, Univ Montpellier, INSERM, CHU Montpellier, Montpellier, France; Department of Medical Genetics, Rare Diseases and Personalized Medicine, Rare and Autoinflammatory Diseases Unit, CHU Montpellier, Univ Montpellier, Montpellier, France
| | - Yanick Crow
- Laboratory of Neurogenetics and Neuroinflammation, Paris Descartes University, Institut Imagine, Paris, France
| | - Gillian Rice
- Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Tu-Anh Tran
- IRMB, Univ Montpellier, INSERM, CHU Montpellier, Montpellier, France; Immunology Department, CHU Nîmes, Univ Montpellier, Nîmes, France; Paediatrics Department, University Hospital Nîmes, Nîmes, France
| | - Renaud Cezar
- IRMB, Univ Montpellier, INSERM, CHU Montpellier, Montpellier, France; Immunology Department, CHU Nîmes, Univ Montpellier, Nîmes, France
| | - Darragh Duffy
- ICD Unit, Inserm U1223, Institut Pasteur, Paris, France
| | | | | | - Christophe Broca
- IRMB, Univ Montpellier, INSERM, CHU Montpellier, Montpellier, France
| | - Benjamin P Kant
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mariëlle VanGijn
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Sylvie Grandemange
- IRMB, Univ Montpellier, INSERM, CHU Montpellier, Montpellier, France; Department of Medical Genetics, Rare Diseases and Personalized Medicine, Rare and Autoinflammatory Diseases Unit, CHU Montpellier, Univ Montpellier, Montpellier, France
| | - Eric Richard
- Institut de Recherche en Cancérologie de Montpellier, INSERM U1194, Univ Montpellier, Institut régional du Cancer de Montpellier, Montpellier, France
| | - Florence Apparailly
- IRMB, Univ Montpellier, INSERM, CHU Montpellier, Montpellier, France; Clinical Department for Osteoarticular Diseases and Biotherapy, University Hospital Lapeyronie, Montpellier, France
| | - Isabelle Touitou
- IRMB, Univ Montpellier, INSERM, CHU Montpellier, Montpellier, France; Department of Medical Genetics, Rare Diseases and Personalized Medicine, Rare and Autoinflammatory Diseases Unit, CHU Montpellier, Univ Montpellier, Montpellier, France
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10
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Ruiz L, Gurlo T, Ravier MA, Wojtusciszyn A, Mathieu J, Brown MR, Broca C, Bertrand G, Butler PC, Matveyenko AV, Dalle S, Costes S. Proteasomal degradation of the histone acetyl transferase p300 contributes to beta-cell injury in a diabetes environment. Cell Death Dis 2018; 9:600. [PMID: 29789539 PMCID: PMC5964068 DOI: 10.1038/s41419-018-0603-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 03/09/2018] [Accepted: 04/17/2018] [Indexed: 12/25/2022]
Abstract
In type 2 diabetes, amyloid oligomers, chronic hyperglycemia, lipotoxicity, and pro-inflammatory cytokines are detrimental to beta-cells, causing apoptosis and impaired insulin secretion. The histone acetyl transferase p300, involved in remodeling of chromatin structure by epigenetic mechanisms, is a key ubiquitous activator of the transcriptional machinery. In this study, we report that loss of p300 acetyl transferase activity and expression leads to beta-cell apoptosis, and most importantly, that stress situations known to be associated with diabetes alter p300 levels and functional integrity. We found that proteasomal degradation is the mechanism subserving p300 loss in beta-cells exposed to hyperglycemia or pro-inflammatory cytokines. We also report that melatonin, a hormone produced in the pineal gland and known to play key roles in beta-cell health, preserves p300 levels altered by these toxic conditions. Collectively, these data imply an important role for p300 in the pathophysiology of diabetes.
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Affiliation(s)
- Lucie Ruiz
- IGF, CNRS, INSERM, University of Montpellier, Montpellier, France
| | - Tatyana Gurlo
- Larry L. Hillblom Islet Research Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Magalie A Ravier
- IGF, CNRS, INSERM, University of Montpellier, Montpellier, France
| | - Anne Wojtusciszyn
- IGF, CNRS, INSERM, University of Montpellier, Montpellier, France.,Laboratory of Cell Therapy for Diabetes (LTCD), Institute for Regenerative Medicine and Biotherapy (IRMB), University Hospital of Montpellier, Montpellier, France.,Department of Endocrinology, Diabetes, and Nutrition, University Hospital of Montpellier, Montpellier, France
| | - Julia Mathieu
- IGF, CNRS, INSERM, University of Montpellier, Montpellier, France
| | - Matthew R Brown
- Department of Physiology and Biomedical Engineering, Mayo Clinic School of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Christophe Broca
- Laboratory of Cell Therapy for Diabetes (LTCD), Institute for Regenerative Medicine and Biotherapy (IRMB), University Hospital of Montpellier, Montpellier, France
| | | | - Peter C Butler
- Larry L. Hillblom Islet Research Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Aleksey V Matveyenko
- Department of Physiology and Biomedical Engineering, Mayo Clinic School of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Stéphane Dalle
- IGF, CNRS, INSERM, University of Montpellier, Montpellier, France
| | - Safia Costes
- IGF, CNRS, INSERM, University of Montpellier, Montpellier, France.
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11
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Broca C, Varin E, Armanet M, Tourrel-Cuzin C, Bosco D, Dalle S, Wojtusciszyn A. Correction: proteasome dysfunction mediates high glucose-induced apoptosis in rodent Beta cells and human islets. PLoS One 2014; 9:e102652. [PMID: 25000098 PMCID: PMC4085027 DOI: 10.1371/journal.pone.0102652] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
[This corrects the article DOI: 10.1371/journal.pone.0092066.].
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12
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Broca C, Varin E, Armanet M, Tourrel-Cuzin C, Bosco D, Dalle S, Wojtusciszyn A. Proteasome dysfunction mediates high glucose-induced apoptosis in rodent beta cells and human islets. PLoS One 2014; 9:e92066. [PMID: 24642635 PMCID: PMC3958412 DOI: 10.1371/journal.pone.0092066] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 02/17/2014] [Indexed: 01/23/2023] Open
Abstract
The ubiquitin/proteasome system (UPS), a major cellular protein degradation machinery, plays key roles in the regulation of many cell functions. Glucotoxicity mediated by chronic hyperglycaemia is detrimental to the function and survival of pancreatic beta cells. The aim of our study was to determine whether proteasome dysfunction could be involved in beta cell apoptosis in glucotoxic conditions, and to evaluate whether such a dysfunction might be pharmacologically corrected. Therefore, UPS activity was measured in GK rats islets, INS-1E beta cells or human islets after high glucose and/or UPS inhibitor exposure. Immunoblotting was used to quantify polyubiquitinated proteins, endoplasmic reticulum (ER) stress through CHOP expression, and apoptosis through the cleavage of PARP and caspase-3, whereas total cell death was detected through histone-associated DNA fragments measurement. In vitro, we found that chronic exposure of INS-1E cells to high glucose concentrations significantly decreases the three proteasome activities by 20% and leads to caspase-3-dependent apoptosis. We showed that pharmacological blockade of UPS activity by 20% leads to apoptosis in a same way. Indeed, ER stress was involved in both conditions. These results were confirmed in human islets, and proteasome activities were also decreased in hyperglycemic GK rats islets. Moreover, we observed that a high glucose treatment hypersensitized beta cells to the apoptotic effect of proteasome inhibitors. Noteworthily, the decreased proteasome activity can be corrected with Exendin-4, which also protected against glucotoxicity-induced apoptosis. Taken together, our findings reveal an important role of proteasome activity in high glucose-induced beta cell apoptosis, potentially linking ER stress and glucotoxicity. These proteasome dysfunctions can be reversed by a GLP-1 analog. Thus, UPS may be a potent target to treat deleterious metabolic conditions leading to type 2 diabetes.
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Affiliation(s)
- Christophe Broca
- CNRS UMR 5203, INSERM U661, and Montpellier 1 & 2 University, Institute of Functional Genomics, Montpellier, France
- Laboratory for Diabetes Cell Therapy, Institute for Research in Biotherapy, University Hospital St-Eloi, Montpellier, France
| | - Elodie Varin
- CNRS UMR 5203, INSERM U661, and Montpellier 1 & 2 University, Institute of Functional Genomics, Montpellier, France
- Laboratory for Diabetes Cell Therapy, Institute for Research in Biotherapy, University Hospital St-Eloi, Montpellier, France
| | - Mathieu Armanet
- Laboratory for Diabetes Cell Therapy, Institute for Research in Biotherapy, University Hospital St-Eloi, Montpellier, France
| | - Cécile Tourrel-Cuzin
- B2PE Laboratory (Biology & Pathology of Endocrine Pancreas), BFA Unit, Univ. Paris-Diderot, CNRS EAC4413, Paris, France
| | - Domenico Bosco
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Stéphane Dalle
- CNRS UMR 5203, INSERM U661, and Montpellier 1 & 2 University, Institute of Functional Genomics, Montpellier, France
- Laboratory for Diabetes Cell Therapy, Institute for Research in Biotherapy, University Hospital St-Eloi, Montpellier, France
| | - Anne Wojtusciszyn
- CNRS UMR 5203, INSERM U661, and Montpellier 1 & 2 University, Institute of Functional Genomics, Montpellier, France
- Laboratory for Diabetes Cell Therapy, Institute for Research in Biotherapy, University Hospital St-Eloi, Montpellier, France
- Department of Endocrinology-Diabetes-Nutrition, University Hospital Lapeyronie, Montpellier, France
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13
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Quoyer J, Longuet C, Broca C, Linck N, Costes S, Varin E, Bockaert J, Bertrand G, Dalle S. GLP-1 mediates antiapoptotic effect by phosphorylating Bad through a beta-arrestin 1-mediated ERK1/2 activation in pancreatic beta-cells. J Biol Chem 2009; 285:1989-2002. [PMID: 19915011 DOI: 10.1074/jbc.m109.067207] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Strategies based on activating GLP-1 receptor (GLP-1R) are intensively developed for the treatment of type 2 diabetes. The exhaustive knowledge of the signaling pathways linked to activated GLP-1R within the beta-cells is of major importance. In beta-cells, GLP-1 activates the ERK1/2 cascade by diverse pathways dependent on either Galpha(s)/cAMP/cAMP-dependent protein kinase (PKA) or beta-arrestin 1, a scaffold protein. Using pharmacological inhibitors, beta-arrestin 1 small interfering RNA, and islets isolated from beta-arrestin 1 knock-out mice, we demonstrate that GLP-1 stimulates ERK1/2 by two temporally distinct pathways. The PKA-dependent pathway mediates rapid and transient ERK1/2 phosphorylation that leads to nuclear translocation of the activated kinases. In contrast, the beta-arrestin 1-dependent pathway produces a late ERK1/2 activity that is restricted to the beta-cell cytoplasm. We further observe that GLP-1 phosphorylates the cytoplasmic proapoptotic protein Bad at Ser-112 but not at Ser-155. We find that the beta-arrestin 1-dependent ERK1/2 activation engaged by GLP-1 mediates the Ser-112 phosphorylation of Bad, through p90RSK activation, allowing the association of Bad with the scaffold protein 14-3-3, leading to its inactivation. beta-Arrestin 1 is further found to mediate the antiapoptotic effect of GLP-1 in beta-cells through the ERK1/2-p90RSK-phosphorylation of Bad. This new regulatory mechanism engaged by activated GLP-1R involving a beta-arrestin 1-dependent spatiotemporal regulation of the ERK1/2-p90RSK activity is now suspected to participate in the protection of beta-cells against apoptosis. Such signaling mechanism may serve as a prototype to generate new therapeutic GLP-1R ligands.
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Affiliation(s)
- Julie Quoyer
- INSERM, U661, Equipe Avenir, CNRS, UMR5203, Institut de Génomique Fonctionnelle, Université Montpellier I and II, 34094 Montpellier Cedex 5, France
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14
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Masiello P, Broca C, Gross R, Ribes G. Streptozotocin and nicotinamide-induced diabetic syndrome in adult rats: A novel alternative NIDDM animal model particularly suitable for pharmacological research. Exp Clin Endocrinol Diabetes 2009. [DOI: 10.1055/s-0029-1211907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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15
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Costes S, Vandewalle B, Tourrel-Cuzin C, Broca C, Linck N, Bertrand G, Kerr-Conte J, Portha B, Pattou F, Bockaert J, Dalle S. Degradation of cAMP-responsive element-binding protein by the ubiquitin-proteasome pathway contributes to glucotoxicity in beta-cells and human pancreatic islets. Diabetes 2009; 58:1105-15. [PMID: 19223597 PMCID: PMC2671045 DOI: 10.2337/db08-0926] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 02/10/2009] [Indexed: 01/09/2023]
Abstract
OBJECTIVE In type 2 diabetes, chronic hyperglycemia is detrimental to beta-cells, causing apoptosis and impaired insulin secretion. The transcription factor cAMP-responsive element-binding protein (CREB) is crucial for beta-cell survival and function. We investigated whether prolonged exposure of beta-cells to high glucose affects the functional integrity of CREB. RESEARCH DESIGN AND METHODS INS-1E cells and rat and human islets were used. Gene expression was analyzed by RT-PCR and Western blotting. Apoptosis was detected by cleaved caspase-3 emergence, DNA fragmentation, and electron microscopy. RESULTS Chronic exposure of INS-1E cells and rat and human islets to high glucose resulted in decreased CREB protein expression, phosphorylation, and transcriptional activity associated with apoptosis and impaired beta-cell function. High-glucose treatment increased CREB polyubiquitination, while treatment of INS-1E cells with the proteasome inhibitor MG-132 prevented the decrease in CREB content. The emergence of apoptosis in INS-1E cells with decreased CREB protein expression knocked down by small interfering RNA suggested that loss of CREB protein content induced by high glucose contributes to beta-cell apoptosis. Loading INS-1E cells or human islets with a cell-permeable peptide mimicking the proteasomal targeting sequence of CREB blocked CREB degradation and protected INS-1E cells and human islets from apoptosis induced by high glucose. The insulin secretion in response to glucose and the insulin content were preserved in human islets exposed to high glucose and loaded with the peptide. CONCLUSIONS These studies demonstrate that the CREB degradation by the ubiquitin-proteasome pathway contributes to beta-cell dysfunction and death upon glucotoxicity and provide new insight into the cellular mechanisms of glucotoxicity.
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Affiliation(s)
- Safia Costes
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
| | | | | | - Christophe Broca
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
| | - Nathalie Linck
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
| | - Gyslaine Bertrand
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
| | | | | | | | - Joel Bockaert
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
| | - Stéphane Dalle
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
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16
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Broca C, Quoyer J, Costes S, Linck N, Varrault A, Deffayet PM, Bockaert J, Dalle S, Bertrand G. beta-Arrestin 1 is required for PAC1 receptor-mediated potentiation of long-lasting ERK1/2 activation by glucose in pancreatic beta-cells. J Biol Chem 2008; 284:4332-42. [PMID: 19074139 DOI: 10.1074/jbc.m807595200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In pancreatic beta-cells, the pituitary adenylate cyclase-activating polypeptide (PACAP) exerts a potent insulin secretory effect via PAC(1) and VPAC receptors (Rs) through the Galpha(s)/cAMP/protein kinase A pathway. Here, we investigated the mechanisms linking PAC(1)R to ERK1/2 activation in INS-1E beta-cells and pancreatic islets. PACAP caused a transient (5 min) increase in ERK1/2 phosphorylation via PAC(1)Rs and promoted nuclear translocation of a fraction of cytosolic p-ERK1/2. Both protein kinase A- and Src-dependent pathways mediated this transient ERK1/2 activation. Moreover, PACAP potentiated glucose-induced long-lasting ERK1/2 activation. Blocking Ca(2+) influx abolished glucose-induced ERK1/2 activation and PACAP potentiating effect. Glucose stimulation during KCl depolarization showed that, in addition to the triggering signal (rise in cytosolic [Ca(2+)]), the amplifying pathway was also involved in glucose-induced sustained ERK1/2 activation and was required for PACAP potentiation. The finding that at 30 min glucose-induced p-ERK1/2 was detected in both cytosol and nucleus while the potentiating effect of PACAP was only observed in the cytosol, suggested the involvement of the scaffold protein beta-arrestin. Indeed, beta-arrestin 1 (beta-arr1) depletion (in beta-arr1 knockout mouse islets or in INS-1E cells by siRNA) completely abolished PACAP potentiation of long-lasting ERK1/2 activation by glucose. Finally, PACAP potentiated glucose-induced CREB transcriptional activity and IRS-2 mRNA expression mainly via the ERK1/2 signaling pathway, and likewise, beta-arr1 depletion reduced the PACAP potentiating effect on IRS-2 expression. These results establish for the first time that PACAP potentiates glucose-induced long-lasting ERK1/2 activation via a beta-arr1-dependent pathway and thus provide new insights concerning the mechanisms of PACAP and glucose actions in pancreatic beta-cells.
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Affiliation(s)
- Christophe Broca
- Institut de Génomique Fonctionnelle, CNRS, Unité Mixte de Recherche 5203, INSERM, U661, Université Montpellier I, and Université Montpellier II, 34094 Montpellier Cedex 5, France
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17
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Costes S, Broca C, Bertrand G, Lajoix AD, Bataille D, Bockaert J, Dalle S. ERK1/2 control phosphorylation and protein level of cAMP-responsive element-binding protein: a key role in glucose-mediated pancreatic beta-cell survival. Diabetes 2006; 55:2220-30. [PMID: 16873684 DOI: 10.2337/db05-1618] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
cAMP-responsive element-binding protein (CREB) is required for beta-cell survival by regulating expression of crucial genes such as bcl-2 and IRS-2. Using MIN6 cells and isolated rat pancreatic islets, we investigated the signaling pathway that controls phosphorylation and protein level of CREB. We observed that 10 mmol/l glucose-induced CREB phosphorylation was totally inhibited by the protein kinase A (PKA) inhibitor H89 (2 micromol/l) and reduced by 50% with the extracellular signal-regulated kinase (ERK)1/2 inhibitor PD98059 (20 micromol/l). This indicates that ERK1/2, reported to be located downstream of PKA, participates in the PKA-mediated CREB phosphorylation elicited by glucose. In ERK1/2-downregulated MIN6 cells by siRNA, glucose-stimulated CREB phosphorylation was highly reduced and CREB protein content was decreased by 60%. In MIN6 cells and islets cultured for 24-48 h in optimal glucose concentration (10 mmol/l), which promotes survival, blockade of ERK1/2 activity with PD98059 caused a significant decrease in CREB protein level, whereas CREB mRNA remained unaffected (measured by real-time quantitative PCR). This was associated with loss of bcl-2 mRNA and protein contents, caspase-3 activation, and emergence of ultrastructural apoptotic features detected by electron microscopy. Our results indicate that ERK1 and -2 control the phosphorylation and protein level of CREB and play a key role in glucose-mediated pancreatic beta-cell survival.
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Affiliation(s)
- Safia Costes
- INSERM U661, Equipe Avenir, Institut de Génomique Fonctionnelle, 141, rue de la cardonille, 34094 Montpellier Cedex 5, France
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18
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Abstract
The aim of this study was to determine whether epiregulin, a novel member of EGF-related growth factor family, was able to affect proliferation and secretory function of rat insulinoma INS-1E and RINm5F cell lines. A 24 h treatment with epiregulin resulted in a stimulation of INS-1E and RINm5F cells proliferation; this effect was completely blocked in the presence of an anti-epiregulin antibody which did not affect basal DNA synthesis in the absence of added ligand. In acute experiments, epiregulin was able to potentiate insulin release in the presence of glucose or arginine, in the two cell lines. Finally, in the two cell lines expressing ErbB receptors, we demonstrated that only EGFR/ErbB1 was activated by epiregulin. Thus, epiregulin appears as a new growth and insulinotropic factor in pancreatic beta cell lines.
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Affiliation(s)
- Emmanuelle Kuntz
- European Centre for the Study of Diabetes, Faculty of Medicine, Strasbourg, France
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19
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Metz L, Vermaelen M, Lambert K, Broca C, Sirvent P, Raynaud E, Mercier J. Endurance training increases lactate transport in male Zucker fa/fa rats. Biochem Biophys Res Commun 2005; 331:1338-45. [PMID: 15883022 DOI: 10.1016/j.bbrc.2005.04.054] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Indexed: 11/17/2022]
Abstract
The purpose of this study was to investigate the effect of endurance training (10 weeks) on previously reported alterations of lactate exchange in obese Zucker fa/fa rats. We used sarcolemmal vesicles to measure lactate transport capacity in control sedentary rats, Zucker (fa/fa), and endurance trained Zucker (fa/fa) rats. Monocarboxylate transporter (MCT) 1 and 4 content was measured in sarcolemmal vesicles and skeletal muscle. Training increased citrate synthase activity in soleus and in red tibialis anterior, and improved insulin sensitivity measured by intraperitoneal glucose tolerance test. Endurance training increased lactate influx in sarcolemmal vesicles at 1 mM of external lactate concentration and increased MCT1 expression on sarcolemmal vesicles. Furthermore, muscular lactate level was significantly decreased after training in red tibialis anterior and extensor digitorum longus. This study shows that endurance training improves impairment of lactate transport capacity that is found in insulin resistance state like obesity and type 2 diabetes.
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Affiliation(s)
- Lore Metz
- Département de Physiologie des Interactions, EA 701 Muscles et Pathologies chroniques, Institut de biologie, CS 89508, 34060 Montpellier cedex 2, France.
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20
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Costes S, Longuet C, Broca C, Faruque O, Hani EH, Bataille D, Dalle S. Cooperative effects between protein kinase A and p44/p42 mitogen-activated protein kinase to promote cAMP-responsive element binding protein activation after beta cell stimulation by glucose and its alteration due to glucotoxicity. Ann N Y Acad Sci 2005; 1030:230-42. [PMID: 15659802 DOI: 10.1196/annals.1329.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Long-term hyperglycemia, a major characteristic of the diabetic state, contributes to the deterioration of the beta cell function, a concept known as beta cell glucotoxicity. We used the MIN6 beta cell line and isolated rat islets to clarify the signaling mechanism(s) used by glucose to activate cAMP-responsive element binding protein (CREB), a transcription factor crucial for beta cell biology, and to evaluate the possible downregulation of this mechanism mediated by long-term hyperglycemia. We report that glucose (10 mM) induces an increase in cytosolic calcium concentration that leads to cAMP-induced protein kinase A (PKA) activation, promoting nuclear translocation of activated ERK1/2. The observation that glucose-induced CREB phosphorylation was totally inhibited by the PKA inhibitor H89 (2 microM) and reduced by 50% with the ERK1/2 inhibitor PD98059 (20 microM) indicates that ERK1/2, located downstream of PKA, cooperates with PKA and is responsible for half of the PKA-mediated CREB phosphorylation elicited by glucose in MIN6 beta cells. We also found that exposure of mu cells for 24 h to high glucose (25 mM) induced a 70% decrease in cellular ERK1/2 and a 50% decrease in CREB content. In high-glucose-treated, ERK1/2- and CREB-downregulated beta cells, there was a loss of glucose (10 mM, 5 min)-stimulated ERK1/2 and CREB phosphorylation that was associated with nuclear apoptotic characteristics. Since we have shown that activation of ERK1/2 is crucial for CREB phosphorylation, loss of the ERK1/2-CREB signaling pathway in beta cells due to long-term hyperglycemia is likely to exacerbate beta cell failure in diabetic states by affecting physiologically relevant gene expression and by inducing apoptosis.
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Affiliation(s)
- Safia Costes
- Unité Institut National de la Santé et de la Recherche Médicale U376, CHU Arnaud-de-Villeneuve, 371 rue du Doyen Gaston Giraud, 34295 Cedex 5 Montpellier, France
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21
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Longuet C, Broca C, Costes S, Hani EH, Bataille D, Dalle S. Extracellularly regulated kinases 1/2 (p44/42 mitogen-activated protein kinases) phosphorylate synapsin I and regulate insulin secretion in the MIN6 beta-cell line and islets of Langerhans. Endocrinology 2005; 146:643-54. [PMID: 15498890 DOI: 10.1210/en.2004-0841] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The p44/p42 MAPKs (ERK1/2) cascade regulates beta-cell nuclear events, which modulates cell differentiation and gene transcription, whereas its implication in processes occurring in the cytoplasm, such as activation of the exocytotic machinery, is still unclear. Using the MIN6 beta-cell line and isolated rat islets of Langerhans, we investigated whether glucose, by activating the ERK1/2 cascade, induces phosphorylation of cytoplasmic proteins implicated in exocytosis of insulin granules such as synapsin I. We observed that the majority of ERK1/2 activity induced by glucose remains in the cytoplasm and physically interacts with synapsin I, allowing phosphorylation of the substrate. Therefore, we reexamined the potential requirement of ERK1/2 for insulin secretion. Blocking activation of ERK1/2 using MEK1/2, the MAPK kinase inhibitor PD98059 or using small interfering RNA-mediated silencing of ERK1 and ERK2 expressions resulted in partial inhibition of glucose-induced insulin release, indicating that ERK1/2 pathway participates also in the regulation of insulin secretion. Moreover, using the pancreatic islet perifusion model, we found that the ERK1/2 activity participates in the first and second phases of insulin release induced by glucose. Taken together, our results demonstrate new aspects of the glucose-dependent actions of ERK1/2 in beta-cells exerted on cytoplasmic proteins, including synapsin I, and participating in the overall glucose-induced insulin secretion.
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Affiliation(s)
- Christine Longuet
- Unité Institut National de la Santé et de la Recherche Médecale U376, Centre Hospitalier Universitaire Arnaud de Villeneuve, 371 Rue du Doyen Gaston Giraud, 34295 Montpellier Cedex 5, France
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22
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Broca C, Breil V, Cruciani-Guglielmacci C, Manteghetti M, Rouault C, Derouet M, Rizkalla S, Pau B, Petit P, Ribes G, Ktorza A, Gross R, Reach G, Taouis M. Insulinotropic agent ID-1101 (4-hydroxyisoleucine) activates insulin signaling in rat. Am J Physiol Endocrinol Metab 2004; 287:E463-71. [PMID: 15082420 DOI: 10.1152/ajpendo.00163.2003] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
ID-1101 (4-hydroxyisoleucine), an amino acid extracted from fenugreek seeds, exhibits an interesting glucose-dependent insulin-stimulating activity. The present study was undertaken to investigate a possible extrapancreatic effect of ID-1101 on insulin signaling and action besides its previously described insulinotropic action. Insulin-sensitizing effects of ID-1101 were investigated in rat in vivo by three different approaches: 1) using euglycemic hyperinsulinemic clamps in two different rat models of insulin resistance, i.e., Zucker fa/fa rats and rats fed a sucrose-lipid diet; 2) measuring liver and muscle phosphatidylinositol (PI) 3-kinase activity after an acute injection of ID-1101 in normal and insulin-resistant diabetic rats; and 3) after chronic treatment in two rat models of insulin resistance. Euglycemic hyperinsulinemic clamp experiments revealed that ID-1101 can improve insulin resistance through an increase of peripheral glucose utilization rate in sucrose-lipid-fed rats and by decreasing hepatic glucose production in Zucker fa/fa rats. Moreover, we demonstrated that a single injection of ID-1101 activates the PI 3-kinase activity in liver and muscle from normal rats but also in muscle from diabetic rats. Finally, chronic ID-1101 treatment significantly reduced insulinemia in type 2 diabetic rats and reduced the progression of hyperinsulinemia in insulin-resistant obese Zucker fa/fa rats. These findings clearly demonstrate that ID-1101 can reduce insulin resistance through activation of the early steps of insulin signaling in peripheral tissues and in liver. In summary, ID-1101, besides its insulinotropic effect, directly improves insulin sensitivity, making it a potentially very valuable therapeutic agent for diabetes treatment.
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Affiliation(s)
- Christophe Broca
- Laboratoire de Pharmacologie, Centre de Pharmacologie et Biotechnologies pour la Santé-Unite Mixte de Recherche 5160 Centre National de la Recherche Scientifique, Faculté de Médecine, 34060 Montpellier, France.
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23
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Dalle S, Longuet C, Costes S, Broca C, Faruque O, Fontés G, Hani EH, Bataille D. Glucagon promotes cAMP-response element-binding protein phosphorylation via activation of ERK1/2 in MIN6 cell line and isolated islets of Langerhans. J Biol Chem 2004; 279:20345-55. [PMID: 14988413 DOI: 10.1074/jbc.m312483200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
By using the MIN6 cell line and pancreatic islets, we show that in the presence of a low glucose concentration, corresponding to physiological glucagon release from alpha cells, glucagon treatment of the beta cell caused a rapid, time-dependent phosphorylation and activation of p44/p42 mitogen-activated protein kinase (ERK1/2) independently from extracellular calcium influx. Inhibition of either cAMP-dependent protein kinase (PKA) or MEK completely blocked ERK1/2 activation by glucagon. However, no significant activation of several upstream activators of MEK, including Shc-p21(Ras) and phosphatidylinositol 3-kinase, was observed in response to glucagon treatment. Chelation of intracellular calcium (intracellular [Ca(2+)]) reduced glucagon-mediated ERK1/2 activation. In addition, internalization of glucagon receptors through clathrin-coated pits formation is required for ERK1/2 activation. Remarkably, glucagon promotes the nuclear translocation of ERK1/2 and induces the phosphorylation of cAMP-response element-binding protein (CREB). Miniglucagon, produced from glucagon and released together with the mother hormone from the alpha cells in low glucose situations, blocks the insulinotropic effect of glucagon, whereas it does not inhibit the glucagon-induced PKA/ERK1/2/CREB pathway. We conclude that glucagon-induced ERK1/2 activation is mediated by PKA and that an increase in [Ca(2+)](i) is required for maximal ERK activation. Our results uncover a novel mechanism by which the PKA/ERK1/2 signaling network engaged by glucagon, in situation of low glucose concentration, regulates phosphorylation of CREB, a transcription factor crucial for normal beta cell function and survival.
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Affiliation(s)
- Stéphane Dalle
- Unité INSERM U376, CHU Arnaud-de-Villeneuve, 371 Rue du Doyen Gaston Giraud, 34295 Montpellier Cedex 5, France
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24
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Broca C, Brennan L, Petit P, Newsholme P, Maechler P. Mitochondria-derived glutamate at the interplay between branched-chain amino acid and glucose-induced insulin secretion. FEBS Lett 2003; 545:167-72. [PMID: 12804769 DOI: 10.1016/s0014-5793(03)00526-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In pancreatic beta-cells, glutamate has been proposed to mediate insulin secretion as a glucose-derived factor, although it is also considered for its sole catabolic function. Hence, changes in cellular glutamate levels are a matter of debate. Here, we investigated the effects of glucose and the glutamate precursor glutamine on kinetics of glutamate levels together with insulin secretion in INS-1E beta-cells. Preincubation at low (1 mM) glucose resulted in reduced cellular glutamate levels, which were doubled by exposure to glutamine. In glutamine-deprived cells, 5 mM glucose restored glutamate concentrations. Incubation at 15 mM glucose increased cellular glutamate, along with stimulation of insulin secretion, following both glutamine-free and glutamine-rich preincubations. Nuclear magnetic resonance (NMR) spectroscopy of INS-1E cells exposed to 15 mM D-[1-(13)C]glucose revealed glutamate as the major glucose metabolic product. Branched-chain amino acids, such as leucine, reduced cellular glutamate levels at low and intermediate glucose. This study demonstrates that glucose stimulates glutamate generation, whereas branched-chain amino acids promote competitive glutamate expenditure.
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Affiliation(s)
- Christophe Broca
- DBC-9100, Department of Internal Medicine, University Medical Centre, 1 rue Michel Servet, CH-1211 Geneva 4, Switzerland
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25
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Chevassus H, Roig A, Belloc C, Lajoix AD, Broca C, Manteghetti M, Petit P. P2Y receptor activation enhances insulin release from pancreatic beta-cells by triggering the cyclic AMP/protein kinase A pathway. Naunyn Schmiedebergs Arch Pharmacol 2002; 366:464-9. [PMID: 12382076 DOI: 10.1007/s00210-002-0620-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2002] [Accepted: 07/02/2002] [Indexed: 11/27/2022]
Abstract
Adenine nucleotides stimulate insulin secretion by binding to P2 receptors of the pancreatic beta-cells; the stimulus-secretion coupling is not yet clearly established and may depend on the receptor subtype. The aim of the present study was to further investigate the mechanism whereby P2Y receptor agonists enhance glucose-induced insulin secretion. Experiments were performed in rat pancreatic islets and in the INS-1 secreting cell line in the presence of a slightly stimulating glucose concentration (8.3 mmol/l). In isolated islets, the P2Y receptor agonist ADPbetaS (50 micromol/l) induced a significant fivefold increase in the cyclic AMP (cAMP) content, from 43.4+/-3.7 fmol/10 islets in controls to 210.6+/-12.0; it still induced a 4.5-fold increase in cAMP content in the absence of calcium. In another series of experiments, ADPbetaS (50 micromol/l) significantly increased glucose-induced insulin secretion from 7.7+/-0.6 ng/3 islets in controls to 11.2+/-1.0. The adenylyl cyclase inhibitor SQ 22,536 (9-[tetrahydro-2-furanyl]-9 H-purin-6-amine; 100 micromol/l), which was ineffective alone, completely prevented the stimulating effect of ADPbetaS. In a set of experiments in which ADPbetaS increased glucose-induced insulin secretion from 10.0+/-0.7 ng/3 islets to 12.6+/-0.8, the inhibitor of cAMP-dependent protein kinase, TPCK (tos-phe-chloromethylketone; 3 micromol/l), which was ineffective alone, also prevented the stimulating effect of ADPbetaS. In incubated INS-1 cells, the P2Y receptor ligand ATPalphaS increased significantly both the content of cAMP and the release of insulin, in a concentration-dependent manner in the range of 50-150 micromol/l; the insulin release was significantly correlated with the cAMP content. In conclusion, the present results show that P2Y receptor agonists, ADPbetaS and ATPalphaS, amplify glucose-induced insulin secretion by activating beta-cell adenylyl cyclase and the subsequent cAMP/protein kinase A signaling pathway.
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Affiliation(s)
- H Chevassus
- Laboratory of Pharmacology, Research Unit UPRES EA 1677 and UMR CNRS 5094, Faculty of Medicine, Montpellier I University, 4 Boulevard Henri IV, 34060 Montpellier Cedex 1, France
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26
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Lajoix AD, Reggio H, Chardès T, Péraldi-Roux S, Tribillac F, Roye M, Dietz S, Broca C, Manteghetti M, Ribes G, Wollheim CB, Gross R. A neuronal isoform of nitric oxide synthase expressed in pancreatic beta-cells controls insulin secretion. Diabetes 2001; 50:1311-23. [PMID: 11375331 DOI: 10.2337/diabetes.50.6.1311] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Evidence is presented showing that a neuronal isoform of nitric oxide synthase (NOS) is expressed in rat pancreatic islets and INS-1 cells. Sequencing of the coding region indicated a 99.8% homology with rat neuronal NOS (nNOS) with four mutations, three of them resulting in modifications of the amino acid sequence. Double-immunofluorescence studies demonstrated the presence of nNOS in insulin-secreting beta-cells. Electron microscopy studies showed that nNOS was mainly localized in insulin secretory granules and to a lesser extent in the mitochondria and the nucleus. We also studied the mechanism involved in the dysfunction of the beta-cell response to arginine and glucose after nNOS blockade with N(G)-nitro-L-arginine methyl ester. Our data show that miconazole, an inhibitor of nNOS cytochrome c reductase activity, either alone for the experiments with arginine or combined with sodium nitroprusside for glucose, is able to restore normal secretory patterns in response to the two secretagogues. Furthermore, these results were corroborated by the demonstration of a direct enzyme-substrate interaction between nNOS and cytochrome c, which is strongly reinforced in the presence of the NOS inhibitor. Thus, we provide immunochemical and pharmacological evidence that beta-cell nNOS exerts, like brain nNOS, two catalytic activities: a nitric oxide production and an NOS nonoxidating reductase activity, both of which are essential for normal beta-cell function. In conclusion, we suggest that an imbalance between these activities might be implicated in beta-cell dysregulation involved in certain pathological hyperinsulinic states.
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Affiliation(s)
- A D Lajoix
- Unité mixte de recherche 5094 du Centre National de la Recherche Scientifique (CNRS), Université Montpellier I, 34060 Montpellier Cedex 1, France
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27
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Broca C, Manteghetti M, Gross R, Baissac Y, Jacob M, Petit P, Sauvaire Y, Ribes G. 4-Hydroxyisoleucine: effects of synthetic and natural analogues on insulin secretion. Eur J Pharmacol 2000; 390:339-45. [PMID: 10708743 DOI: 10.1016/s0014-2999(00)00030-3] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
4-Hydroxyisoleucine, a peculiar amino acid extracted from fenugreek seeds and never found in mammalian tissues, exhibits interesting insulinotropic activity. To investigate the structural requirements for this stimulating effect, the insulinotropic activity of the major isomer (2S,3R,4S) of 4-hydroxyisoleucine, in the presence of 8. 3 mM glucose, was compared to that of (1) its minor isomer (2R,3R, 4S) (2) its lactone form, (3) classical structurally related amino acids, and (4) synthetic monomethylated analogues. In the isolated, ex vivo, perfused rat pancreas, only the major isomer of 4-hydroxyisoleucine (200 microM) potentiated insulin release. On incubated isolated rat islets, the threshold concentration for a significant increase (P<0.05) in insulin release was 200 microM for (2S,3R,4S) 4-hydroxyisoleucine, 500 microM for (2S,4R) and (2S,4S) gamma-hydroxynorvalines as well as (2S,3S) and (2S,3R) gamma-hydroxyvalines, and 1 mM or more for other congeners. In conclusion, the insulinotropic properties of 4-hydroxyisoleucine, in the micromolar range, are seen only in the presence of the linear major isoform; they also require carbon alpha in S-configuration, full methylation and carbon gamma-hydroxylation.
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Affiliation(s)
- C Broca
- UMR 9921 du Centre National de la Recherche Scientifique, Montpellier, France.
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28
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Broca C, Gross R, Petit P, Sauvaire Y, Manteghetti M, Tournier M, Masiello P, Gomis R, Ribes G. 4-Hydroxyisoleucine: experimental evidence of its insulinotropic and antidiabetic properties. Am J Physiol 1999; 277:E617-23. [PMID: 10516120 DOI: 10.1152/ajpendo.1999.277.4.e617] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We have recently shown in vitro that 4-hydroxyisoleucine (4-OH-Ile), an amino acid extracted from fenugreek seeds, potentiates insulin secretion in a glucose-dependent manner. The present study was designed to investigate whether 4-OH-Ile could exert in vivo insulinotropic and antidiabetic properties. For this purpose, intravenous or oral glucose tolerance tests (IVGTTs and OGTTs, respectively) were performed not only in normal animals but also in a type II diabetes rat model. During IVGTT in normal rats or OGTT in normal dogs, 4-OH-Ile (18 mg/kg) improved glucose tolerance. The lactonic form of 4-OH-Ile was ineffective in normal rats. In non-insulin-dependent diabetic (NIDD) rats, a single intravenous administration of 4-OH-Ile (50 mg/kg) partially restored glucose-induced insulin response without affecting glucose tolerance; a 6-day subchronic administration of 4-OH-Ile (50 mg/kg, daily) reduced basal hyperglycemia, decreased basal insulinemia, and slightly, but significantly, improved glucose tolerance. In vitro, 4-OH-Ile (200 microM) potentiated glucose (16.7 mM)-induced insulin release from NIDD rat-isolated islets. So, the antidiabetic effects of 4-OH-Ile on NIDD rats result, at least in part, from a direct pancreatic B cell stimulation.
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Affiliation(s)
- C Broca
- Unité Mixte de Recherche 9921 du Centre National de la Recherche Scientifique, Faculté de Médecine UPRES EA 1677, 34060 Montpellier, France. broca2zeus.sc.univ-montp1.fr
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Demêmes D, Broca C. Calcitonin gene-related peptide immunoreactivity in the rat efferent vestibular system during development. Brain Res Dev Brain Res 1998; 108:59-67. [PMID: 9693784 DOI: 10.1016/s0165-3806(98)00030-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The organization of the efferent fiber network during postnatal development was investigated by immunocytochemical detection of the calcitonin gene-related peptide (CGRP) in rat vestibular receptors from postnatal day 0 (PD 0) to adulthood. CGRP was detected at birth in a few efferent fibers below the sensory epithelia of cristae and maculae. Thereafter, the nerve fibers in the cristae progressively invaded the epithelia with an apex to base gradient from PD 2 to PD 4. There was also a rearrangement of the fibers during maturation of the efferent innervation, such that after reaching the surface of the epithelium, they turned back and moved towards the base of the sensory cells, producing numerous synaptic contacts. Analysis of surface preparations of utricules showed the irregular and asymmetric topographic organization of the efferent fiber network and the extensive, complex distribution of this innervation. The presence and broad distribution of CGRP in the epithelium at critical stages of development and synaptogenesis suggests that it is involved in the maturation of vestibular receptors.
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Affiliation(s)
- D Demêmes
- INSERM U 432, UM 2, Montpellier, France.
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Sauvaire Y, Petit P, Broca C, Manteghetti M, Baissac Y, Fernandez-Alvarez J, Gross R, Roye M, Leconte A, Gomis R, Ribes G. 4-Hydroxyisoleucine: a novel amino acid potentiator of insulin secretion. Diabetes 1998; 47:206-10. [PMID: 9519714 DOI: 10.2337/diab.47.2.206] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We report the characterization of a new insulinotropic compound, 4-hydroxyisoleucine. This amino acid has been extracted and purified from fenugreek seeds, which are known in traditional medicine for their antidiabetic properties. 4-Hydroxyisoleucine increases glucose-induced insulin release, in the concentration range of 100 micromol/l to 1 mmol/l, through a direct effect on isolated islets of Langerhans from both rats and humans. The stimulating effect of 4-hydroxyisoleucine was strictly glucose dependent; indeed, ineffective at low (3 mmol/l) or basal (5 mmol/l) glucose concentrations, the amino acid potentiated the insulin secretion induced by supranormal (6.6-16.7 mmol/l) concentrations of glucose. In addition, in the isolated perfused rat pancreas, we could show 1) that the pattern of insulin secretion induced by 4-hydroxyisoleucine was biphasic, 2) that this effect occurred in the absence of any change in pancreatic alpha- and delta-cell activity, and 3) that the more glucose concentration was increased, the more insulin response was amplified. Moreover, 4-hydroxyisoleucine did not interact with other agonists of insulin secretion (leucine, arginine, tolbutamide, glyceraldehyde). Therefore, we conclude that 4-hydroxyisoleucine insulinotropic activity might, at least in part, account for fenugreek seeds' antidiabetic properties. This secretagogue may be considered as a novel drug with potential interest for the treatment of NIDDM.
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Affiliation(s)
- Y Sauvaire
- Laboratoire de Recherche sur les Substances Naturelles Végétales, Université Montpellier II, France
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Masiello P, Broca C, Gross R, Roye M, Manteghetti M, Hillaire-Buys D, Novelli M, Ribes G. Experimental NIDDM: development of a new model in adult rats administered streptozotocin and nicotinamide. Diabetes 1998; 47:224-9. [PMID: 9519717 DOI: 10.2337/diab.47.2.224] [Citation(s) in RCA: 411] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We took advantage of the partial protection exerted by suitable dosages of nicotinamide against the beta-cytotoxic effect of streptozotocin (STZ) to create a new experimental diabetic syndrome in adult rats that appears closer to NIDDM than other available animal models with regard to insulin responsiveness to glucose and sulfonylureas. Among the various dosages of nicotinamide tested in 3-month-old Wistar rats (100-350 mg/kg body wt), the dosage of 230 mg/kg, given intraperitoneally 15 min before STZ administration (65 mg/kg i.v.) yielded a maximum of animals with moderate and stable nonfasting hyperglycemia (155 +/- 3 vs. 121 +/- 3 mg/dl in controls; P < 0.05) and 40% preservation of pancreatic insulin stores. We also evaluated beta-cell function both in vitro and in vivo 4-9 weeks after inducing diabetes. In the isolated perfused pancreas, insulin response to glucose elevation (5-11 mmol/l) was clearly present, although significantly reduced with respect to controls (P < 0.01). Moreover, the insulin response to tolbutamide (0.19 mmol/l) was similar to that observed in normal pancreases. Perfused pancreases from diabetic animals also exhibited a striking hypersensitivity to arginine infusion (7 mmol/l). In rats administered STZ plus nicotinamide, intravenous glucose tolerance tests revealed clear abnormalities in glucose tolerance and insulin responsiveness, which were interestingly reversed by tolbutamide administration (40 mg/kg i.v.). In conclusion, this novel NIDDM syndrome with reduced pancreatic insulin stores, which is similar to human NIDDM in that it has a significant response to glucose (although abnormal in kinetics) and preserved sensitivity to tolbutamide, may provide a particularly advantageous tool for pharmacological investigations of new insulinotropic agents.
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Affiliation(s)
- P Masiello
- Istituto di Patologia Generale, University of Pisa, Italy
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Gross R, Roye M, Manteghetti M, Broca C, Hillaire-Buys D, Masiello P, Ribes G. Mechanisms involved in the effect of nitric oxide synthase inhibition on L-arginine-induced insulin secretion. Br J Pharmacol 1997; 120:495-501. [PMID: 9031755 PMCID: PMC1564475 DOI: 10.1038/sj.bjp.0700911] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
1. A constitutive nitric oxide synthase (NOSc) pathway negatively controls L-arginine-stimulated insulin release by pancreatic beta cells. We investigated the effect of glucose on this mechanism and whether it could be accounted for by nitric oxide production. 2. NOSc was inhibited by N omega-nitro-L-arginine methyl ester (L-NAME), and sodium nitroprusside (SNP) was used as a palliative NO donor to test whether the effects of L-NAME resulted from decreased NO production. 3. In the rat isolated perfused pancreas, L-NAME (5 mM) strongly potentiated L-arginine (5 mM)-induced insulin secretion at 5 mM glucose, but L-arginine and L-NAME exerted only additive effects at 8.3 mM glucose. At 11 mM glucose, L-NAME significantly inhibited L-arginine-induced insulin secretion. Similar data were obtained in rat isolated islets. 4. At high concentrations (3 and 300 microM), SNP increased the potentiation of arginine-induced insulin output by L-NAME, but not at lower concentrations (3 or 30 nM). 5. L-Arginine (5 mM) and L-ornithine (5 mM) in the presence of 5 mM glucose induced monophasic beta cell responses which were both significantly reduced by SNP at 3 nM but not at 30 nM; in contrast, the L-ornithine effect was significantly increased by SNP at 3 microM. 6. Simultaneous treatment with L-ornithine and L-arginine provoked a biphasic insulin response. 7. At 5 mM glucose, L-NAME (5 mM) did not affect the L-ornithine secretory effect, but the amino acid strongly potentiated the alteration by L-NAME of L-arginine-induced insulin secretion. 8. L-Citrulline (5 mM) significantly reduced the second phase of the insulin response to L-NAME (5 mM) + L-arginine (5 mM) and to L-NAME + L-arginine + SNP 3 microM. 9. The intermediate in NO biosynthesis, NG-hydroxy-L-arginine (150-300 microM) strongly counteracted the potentiation by L-NAME of the secretory effect of L-arginine at 5 mM glucose. 10. We conclude that the potentiation of L-arginine-induced insulin secretion resulting from the blockade of NOSc activity in the presence of a basal glucose concentration (1) is strongly modulated by higher glucose concentrations, (2) is not due to decreased NO production but (3) is probably accounted for by decreased levels of NG-hydroxy-L-arginine or L-citrulline, resulting in the attenuation of an inhibitory effect on arginase activity.
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Affiliation(s)
- R Gross
- UMR 9921 du CNRS, Montpellier, France
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