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Fenske RJ, Wienkes HN, Peter DC, Schaid MD, Hurley LD, Pennati A, Galipeau J, Kimple ME. Gα z-independent and -dependent Improvements With EPA Supplementation on the Early Type 1 Diabetes Phenotype of NOD Mice. J Endocr Soc 2024; 8:bvae100. [PMID: 38831864 PMCID: PMC11146416 DOI: 10.1210/jendso/bvae100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Indexed: 06/05/2024] Open
Abstract
Prostaglandin E2 (PGE2) is a key mediator of inflammation and is derived from the omega-6 polyunsaturated fatty acid, arachidonic acid (AA). In the β-cell, the PGE2 receptor, Prostaglandin EP3 receptor (EP3), is coupled to the unique heterotrimeric G protein alpha subunit, Gɑz to reduce the production of cyclic adenosine monophosphate (cAMP), a key signaling molecule that activates β-cell function, proliferation, and survival pathways. Nonobese diabetic (NOD) mice are a strong model of type 1 diabetes (T1D), and NOD mice lacking Gɑz are protected from hyperglycemia. Therefore, limiting systemic PGE2 production could potentially improve both the inflammatory and β-cell dysfunction phenotype of T1D. Here, we sought to evaluate the effect of eicosapentaenoic acid (EPA) feeding, which limits PGE2 production, on the early T1D phenotype of NOD mice in the presence and absence of Gαz. Wild-type and Gαz knockout NOD mice were fed a control or EPA-enriched diet for 12 weeks, beginning at age 4 to 5 weeks. Oral glucose tolerance, splenic T-cell populations, islet cytokine/chemokine gene expression, islet insulitis, measurements of β-cell mass, and measurements of β-cell function were quantified. EPA diet feeding and Gɑz loss independently improved different aspects of the early NOD T1D phenotype and coordinated to alter the expression of certain cytokine/chemokine genes and enhance incretin-potentiated insulin secretion. Our results shed critical light on the Gαz-dependent and -independent effects of dietary EPA enrichment and provide a rationale for future research into novel pharmacological and dietary adjuvant therapies for T1D.
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Affiliation(s)
- Rachel J Fenske
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Nutritional Sciences, University of Wisconsin–Madison, Madison, WI 53706, USA
- Clinical Research Unit, University of Wisconsin Hospitals and Clinics, Madison, WI 53792, USA
| | - Haley N Wienkes
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Darby C Peter
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Michael D Schaid
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Nutritional Sciences, University of Wisconsin–Madison, Madison, WI 53706, USA
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Liam D Hurley
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Andrea Pennati
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
- University of Wisconsin Carbone Cancer Center, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Jacques Galipeau
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
- University of Wisconsin Carbone Cancer Center, University of Wisconsin–Madison, Madison, WI 53705, USA
| | - Michelle E Kimple
- Research Service, William S. Middleton Memorial VA Hospital, Madison, WI 53705, USA
- Department of Medicine, University of Wisconsin–Madison, Madison, WI 53705, USA
- Department of Cell and Regenerative Biology, University of Wisconsin–Madison, Madison, WI 53705, USA
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2
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Shapey IM, Summers A, Yiannoullou P, Fullwood C, Augustine T, Rutter MK, van Dellen D. Donor noradrenaline use is associated with better allograft survival in recipients of pancreas transplantation. Ann R Coll Surg Engl 2024; 106:19-28. [PMID: 36927080 PMCID: PMC10757882 DOI: 10.1308/rcsann.2022.0161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2022] [Indexed: 03/18/2023] Open
Abstract
INTRODUCTION Outcomes following pancreas transplantation are suboptimal and better donor selection is required to improve this. Vasoactive drugs (VaD) are commonly used to correct the abnormal haemodynamics of organ donors in intensive care units. VaDs can differentially affect insulin secretion positively (dobutamine) or negatively (noradrenaline). The hypothesis was that some VaDs might induce beta-cell stress or rest and therefore impact pancreas transplant outcomes. The aim of the study was to assess relationships between VaD use and pancreas transplant graft survival. METHODS Data from the UK Transplant Registry on all pancreas transplants performed between 2004 and 2016 with complete follow-up data were included. Univariable- and multivariable-adjusted Cox regression analyses determined risks of graft failure associated with VaD use. RESULTS In 2,183 pancreas transplants, VaDs were used in the following numbers of donors: dobutamine 76 (3.5%), dopamine 84 (3.8%), adrenaline 161 (7.4%), noradrenaline 1,589 (72.8%) and vasopressin 1,219 (55.8%). In multivariable models, adjusted for covariates and the co-administration of other VaDs, noradrenaline use (vs non-use) was a strong predictor of better graft survival (hazard ratio [95% confidence interval] 0.77 [0.64-0.94], p = 0.01). CONCLUSIONS Noradrenaline use was associated with better graft survival in models adjusted for donor and recipient variables - this may be related to inhibition of pancreatic insulin secretion initiating pancreatic beta-cell 'rest'. Further research is required to replicate these findings and establish whether relationships are causal. Identification of alternative methods of inducing beta-cell rest could be valuable in improving graft outcomes.
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Affiliation(s)
- IM Shapey
- University of Manchester, UK
- Manchester University NHS Foundation Trust, UK
| | - A Summers
- Manchester University NHS Foundation Trust, UK
| | | | - C Fullwood
- University of Manchester, UK
- Manchester University NHS Foundation Trust, UK
| | - T Augustine
- Manchester University NHS Foundation Trust, UK
| | - MK Rutter
- University of Manchester, UK
- Manchester University NHS Foundation Trust, UK
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Ramanadham S, Turk J, Bhatnagar S. Noncanonical Regulation of cAMP-Dependent Insulin Secretion and Its Implications in Type 2 Diabetes. Compr Physiol 2023; 13:5023-5049. [PMID: 37358504 PMCID: PMC10809800 DOI: 10.1002/cphy.c220031] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
Impaired glucose tolerance (IGT) and β-cell dysfunction in insulin resistance associated with obesity lead to type 2 diabetes (T2D). Glucose-stimulated insulin secretion (GSIS) from β-cells occurs via a canonical pathway that involves glucose metabolism, ATP generation, inactivation of K ATP channels, plasma membrane depolarization, and increases in cytosolic concentrations of [Ca 2+ ] c . However, optimal insulin secretion requires amplification of GSIS by increases in cyclic adenosine monophosphate (cAMP) signaling. The cAMP effectors protein kinase A (PKA) and exchange factor activated by cyclic-AMP (Epac) regulate membrane depolarization, gene expression, and trafficking and fusion of insulin granules to the plasma membrane for amplifying GSIS. The widely recognized lipid signaling generated within β-cells by the β-isoform of Ca 2+ -independent phospholipase A 2 enzyme (iPLA 2 β) participates in cAMP-stimulated insulin secretion (cSIS). Recent work has identified the role of a G-protein coupled receptor (GPCR) activated signaling by the complement 1q like-3 (C1ql3) secreted protein in inhibiting cSIS. In the IGT state, cSIS is attenuated, and the β-cell function is reduced. Interestingly, while β-cell-specific deletion of iPLA 2 β reduces cAMP-mediated amplification of GSIS, the loss of iPLA 2 β in macrophages (MØ) confers protection against the development of glucose intolerance associated with diet-induced obesity (DIO). In this article, we discuss canonical (glucose and cAMP) and novel noncanonical (iPLA 2 β and C1ql3) pathways and how they may affect β-cell (dys)function in the context of impaired glucose intolerance associated with obesity and T2D. In conclusion, we provide a perspective that in IGT states, targeting noncanonical pathways along with canonical pathways could be a more comprehensive approach for restoring β-cell function in T2D. © 2023 American Physiological Society. Compr Physiol 13:5023-5049, 2023.
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Affiliation(s)
- Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Alabama, USA
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
| | - John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sushant Bhatnagar
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
- Department of Medicine, University of Alabama at Birmingham, Alabama, USA
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4
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Aslanoglou D, Bertera S, Friggeri L, Sánchez-Soto M, Lee J, Xue X, Logan RW, Lane JR, Yechoor VK, McCormick PJ, Meiler J, Free RB, Sibley DR, Bottino R, Freyberg Z. Dual pancreatic adrenergic and dopaminergic signaling as a therapeutic target of bromocriptine. iScience 2022; 25:104771. [PMID: 35982797 PMCID: PMC9379584 DOI: 10.1016/j.isci.2022.104771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 06/10/2022] [Accepted: 07/11/2022] [Indexed: 11/23/2022] Open
Abstract
Bromocriptine is approved as a diabetes therapy, yet its therapeutic mechanisms remain unclear. Though bromocriptine's actions have been mainly attributed to the stimulation of brain dopamine D2 receptors (D2R), bromocriptine also targets the pancreas. Here, we employ bromocriptine as a tool to elucidate the roles of catecholamine signaling in regulating pancreatic hormone secretion. In β-cells, bromocriptine acts on D2R and α2A-adrenergic receptor (α2A-AR) to reduce glucose-stimulated insulin secretion (GSIS). Moreover, in α-cells, bromocriptine acts via D2R to reduce glucagon secretion. α2A-AR activation by bromocriptine recruits an ensemble of G proteins with no β-arrestin2 recruitment. In contrast, D2R recruits G proteins and β-arrestin2 upon bromocriptine stimulation, demonstrating receptor-specific signaling. Docking studies reveal distinct bromocriptine binding to α2A-AR versus D2R, providing a structural basis for bromocriptine's dual actions on β-cell α2A-AR and D2R. Together, joint dopaminergic and adrenergic receptor actions on α-cell and β-cell hormone release provide a new therapeutic mechanism to improve dysglycemia.
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Affiliation(s)
- Despoina Aslanoglou
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Suzanne Bertera
- Institute of Cellular Therapeutics, Allegheny Health Network Research Institute, Allegheny Health Network, Pittsburgh, PA, USA
| | - Laura Friggeri
- Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Marta Sánchez-Soto
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Jeongkyung Lee
- Diabetes and Beta Cell Biology Center, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xiangning Xue
- Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ryan W. Logan
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
| | - J. Robert Lane
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, UK
- Centre of Membrane Protein and Receptors, Universities of Birmingham and Nottingham, Nottingham, UK
| | - Vijay K. Yechoor
- Diabetes and Beta Cell Biology Center, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Peter J. McCormick
- Centre for Endocrinology, William Harvey Research Institute, Bart’s and the London School of Medicine and Dentistry, Queen Mary, University of London, London, UK
| | - Jens Meiler
- Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
- Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - R. Benjamin Free
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - David R. Sibley
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Rita Bottino
- Institute of Cellular Therapeutics, Allegheny Health Network Research Institute, Allegheny Health Network, Pittsburgh, PA, USA
- Imagine Pharma, Pittsburgh, PA, USA
| | - Zachary Freyberg
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Cell Biology, University of Pittsburgh, PA, USA
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5
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Effects of Arachidonic Acid and Its Metabolites on Functional Beta-Cell Mass. Metabolites 2022; 12:metabo12040342. [PMID: 35448529 PMCID: PMC9031745 DOI: 10.3390/metabo12040342] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/06/2022] [Accepted: 04/09/2022] [Indexed: 01/26/2023] Open
Abstract
Arachidonic acid (AA) is a polyunsaturated 20-carbon fatty acid present in phospholipids in the plasma membrane. The three primary pathways by which AA is metabolized are mediated by cyclooxygenase (COX) enzymes, lipoxygenase (LOX) enzymes, and cytochrome P450 (CYP) enzymes. These three pathways produce eicosanoids, lipid signaling molecules that play roles in biological processes such as inflammation, pain, and immune function. Eicosanoids have been demonstrated to play a role in inflammatory, renal, and cardiovascular diseases as well type 1 and type 2 diabetes. Alterations in AA release or AA concentrations have been shown to affect insulin secretion from the pancreatic beta cell, leading to interest in the role of AA and its metabolites in the regulation of beta-cell function and maintenance of beta-cell mass. In this review, we discuss the metabolism of AA by COX, LOX, and CYP, the roles of these enzymes and their metabolites in beta-cell mass and function, and the possibility of targeting these pathways as novel therapies for treating diabetes.
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6
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Keen AC, Pedersen MH, Lemel L, Scott DJ, Canals M, Littler DR, Beddoe T, Ono Y, Shi L, Inoue A, Javitch JA, Lane JR. OZITX, a pertussis toxin-like protein for occluding inhibitory G protein signalling including Gα z. Commun Biol 2022; 5:256. [PMID: 35322196 PMCID: PMC8943041 DOI: 10.1038/s42003-022-03191-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 02/17/2022] [Indexed: 11/18/2022] Open
Abstract
Heterotrimeric G proteins are the main signalling effectors for G protein-coupled receptors. Understanding the distinct functions of different G proteins is key to understanding how their signalling modulates physiological responses. Pertussis toxin, a bacterial AB5 toxin, inhibits Gαi/o G proteins and has proven useful for interrogating inhibitory G protein signalling. Pertussis toxin, however, does not inhibit one member of the inhibitory G protein family, Gαz. The role of Gαz signalling has been neglected largely due to a lack of inhibitors. Recently, the identification of another Pertussis-like AB5 toxin was described. Here we show that this toxin, that we call OZITX, specifically inhibits Gαi/o and Gαz G proteins and that expression of the catalytic S1 subunit is sufficient for this inhibition. We identify mutations that render Gα subunits insensitive to the toxin that, in combination with the toxin, can be used to interrogate the signalling of each inhibitory Gα G protein.
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Affiliation(s)
- Alastair C Keen
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, Nottingham, UK
| | - Maria Hauge Pedersen
- Departments of Psychiatry and Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA
- NNF Center for Basic Metabolic Research, Section for Metabolic Receptology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Laura Lemel
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, Nottingham, UK
| | - Daniel J Scott
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC, 3052, Australia
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, 3052, VIC, 3052, Australia
| | - Meritxell Canals
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, Nottingham, UK
| | - Dene R Littler
- Infection and Immunity Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3052, Australia
| | - Travis Beddoe
- Department of Animal, Plant and Soil Science and Centre for AgriBioscience, La Trobe University, Bundoora, VIC, 3086, Australia
| | - Yuki Ono
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Lei Shi
- Computational Chemistry and Molecular Biophysics Section, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Jonathan A Javitch
- Departments of Psychiatry and Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA.
| | - J Robert Lane
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK.
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, Nottingham, UK.
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7
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Hanson J. [G proteins: privileged transducers of 7-transmembrane spanning receptors]. Biol Aujourdhui 2022; 215:95-106. [PMID: 35275054 DOI: 10.1051/jbio/2021011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Indexed: 06/14/2023]
Abstract
G protein-coupled receptors or GPCR are the most abundant membrane receptors in our genome with around 800 members. They play an essential role in most physiological and pathophysiological phenomena. In addition, they constitute 30% of the targets of currently marketed drugs and remain an important reservoir for new innovative therapies. Their main effectors are heterotrimeric G proteins. These are composed of 3 subunits, α, β and γ, which, upon coupling with a GPCR, dissociate into Gα and Gβγ to activate numerous signaling pathways. This article describes some of the recent advances in understanding the function and role of heterotrimeric G proteins. After a short introduction to GPCRs, the history of the discovery of G proteins is briefly described. Then, the fundamental mechanisms of activation, signaling and regulation of G proteins are reviewed. New paradigms concerning intracellular signaling, specific recognition of G proteins by GPCRs as well as biased signaling are also discussed.
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Affiliation(s)
- Julien Hanson
- Laboratoire de Pharmacologie Moléculaire, GIGA-Molecular Biology of Diseases, Université de Liège, CHU, B34, Tour GIGA (+4), Avenue de l'Hôpital 11, B-4000 Liège, Belgique
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8
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Wisinski JA, Reuter A, Peter DC, Schaid MD, Fenske RJ, Kimple ME. Prostaglandin EP3 receptor signaling is required to prevent insulin hypersecretion and metabolic dysfunction in a non-obese mouse model of insulin resistance. Am J Physiol Endocrinol Metab 2021; 321:E479-E489. [PMID: 34229444 PMCID: PMC8560379 DOI: 10.1152/ajpendo.00051.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
When homozygous for the LeptinOb mutation (Ob), Black-and-Tan Brachyury (BTBR) mice become morbidly obese and severely insulin resistant, and by 10 wk of age, frankly diabetic. Previous work has shown prostaglandin EP3 receptor (EP3) expression and activity is upregulated in islets from BTBR-Ob mice as compared with lean controls, actively contributing to their β-cell dysfunction. In this work, we aimed to test the impact of β-cell-specific EP3 loss on the BTBR-Ob phenotype by crossing Ptger3 floxed mice with the rat insulin promoter (RIP)-CreHerr driver strain. Instead, germline recombination of the floxed allele in the founder mouse-an event whose prevalence we identified as directly associated with underlying insulin resistance of the background strain-generated a full-body knockout. Full-body EP3 loss provided no diabetes protection to BTBR-Ob mice but, unexpectedly, significantly worsened BTBR-lean insulin resistance and glucose tolerance. This in vivo phenotype was not associated with changes in β-cell fractional area or markers of β-cell replication ex vivo. Instead, EP3-null BTBR-lean islets had essentially uncontrolled insulin hypersecretion. The selective upregulation of constitutively active EP3 splice variants in islets from young, lean BTBR mice as compared with C57BL/6J, where no phenotype of EP3 loss has been observed, provides a potential explanation for the hypersecretion phenotype. In support of this, high islet EP3 expression in Balb/c females versus Balb/c males was fully consistent with their sexually dimorphic metabolic phenotype after loss of EP3-coupled Gαz protein. Taken together, our findings provide a new dimension to the understanding of EP3 as a critical brake on insulin secretion.NEW & NOTEWORTHY Islet prostaglandin EP3 receptor (EP3) signaling is well known as upregulated in the pathophysiological conditions of type 2 diabetes, contributing to β-cell dysfunction. Unexpected findings in mouse models of non-obese insulin sensitivity and resistance provide a new dimension to our understanding of EP3 as a key modulator of insulin secretion. A previously unknown relationship between mouse insulin resistance and the penetrance of rat insulin promoter-driven germline floxed allele recombination is critical to consider when creating β-cell-specific knockouts.
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Affiliation(s)
- Jaclyn A Wisinski
- Department of Biology, University of Wisconsin-LaCrosse, La Crosse, Wisconsin
| | - Austin Reuter
- Research Service, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin
| | - Darby C Peter
- Research Service, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin
| | - Michael D Schaid
- Research Service, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin
- Interdepartmental Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Rachel J Fenske
- Research Service, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
- Interdepartmental Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Michelle E Kimple
- Research Service, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin
- Interdepartmental Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin
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9
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Pancreatic Islets Exhibit Dysregulated Adaptation of Insulin Secretion after Chronic Epinephrine Exposure. Curr Issues Mol Biol 2021; 43:240-250. [PMID: 34071501 PMCID: PMC8929152 DOI: 10.3390/cimb43010020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 01/11/2023] Open
Abstract
Chronic adrenergic stimulation is the dominant factor in impairment of the β-cell function. Sustained adrenergic exposure generates dysregulated insulin secretion in fetal sheep. Similar results have been shown in Min6 under the elevated epinephrine condition, but impairments after adrenergic removal are still unknown and a high rate of proliferation in Min6 has been ignored. Therefore, we incubated primary rats' islets with half maximal inhibitory concentrations of epinephrine for three days, then determined their insulin secretion responsiveness and related signals two days after removal of adrenaline via radioimmunoassay and qPCR. Insulin secretion was not different between the exposure group (1.07 ± 0.04 ng/islet/h) and control (1.23 ± 0.17 ng/islet/h), but total islet insulin content after treatment (5.46 ± 0.87 ng/islet/h) was higher than control (3.17 ± 0.22 ng/islet/h, p < 0.05), and the fractional insulin release was 36% (p < 0.05) lower after the treatment. Meanwhile, the mRNA expression of Gαs, Gαz and Gβ1-2 decreased by 42.8% 19.4% and 24.8%, respectively (p < 0.05). Uncoupling protein 2 (Ucp2), sulphonylurea receptor 1 (Sur1) and superoxide dismutase 2 (Sod2) were significantly reduced (38.5%, 23.8% and 53.8%, p < 0.05). Chronic adrenergic exposure could impair insulin responsiveness in primary pancreatic islets. Decreased G proteins and Sur1 expression affect the regulation of insulin secretion. In conclusion, the sustained under-expression of Ucp2 and Sod2 may further change the function of β-cell, which helps to understand the long-term adrenergic adaptation of pancreatic β-cell.
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Schaid MD, Green CL, Peter DC, Gallagher SJ, Guthery E, Carbajal KA, Harrington JM, Kelly GM, Reuter A, Wehner ML, Brill AL, Neuman JC, Lamming DW, Kimple ME. Agonist-independent Gα z activity negatively regulates beta-cell compensation in a diet-induced obesity model of type 2 diabetes. J Biol Chem 2020; 296:100056. [PMID: 33172888 PMCID: PMC7948463 DOI: 10.1074/jbc.ra120.015585] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 11/04/2020] [Accepted: 11/10/2020] [Indexed: 12/17/2022] Open
Abstract
The inhibitory G protein alpha-subunit (Gαz) is an important modulator of beta-cell function. Full-body Gαz-null mice are protected from hyperglycemia and glucose intolerance after long-term high-fat diet (HFD) feeding. In this study, at a time point in the feeding regimen where WT mice are only mildly glucose intolerant, transcriptomics analyses reveal islets from HFD-fed Gαz KO mice have a dramatically altered gene expression pattern as compared with WT HFD-fed mice, with entire gene pathways not only being more strongly upregulated or downregulated versus control-diet fed groups but actually reversed in direction. Genes involved in the “pancreatic secretion” pathway are the most strongly differentially regulated: a finding that correlates with enhanced islet insulin secretion and decreased glucagon secretion at the study end. The protection of Gαz-null mice from HFD-induced diabetes is beta-cell autonomous, as beta cell–specific Gαz-null mice phenocopy the full-body KOs. The glucose-stimulated and incretin-potentiated insulin secretion response of islets from HFD-fed beta cell–specific Gαz-null mice is significantly improved as compared with islets from HFD-fed WT controls, which, along with no impact of Gαz loss or HFD feeding on beta-cell proliferation or surrogates of beta-cell mass, supports a secretion-specific mechanism. Gαz is coupled to the prostaglandin EP3 receptor in pancreatic beta cells. We confirm the EP3γ splice variant has both constitutive and agonist-sensitive activity to inhibit cAMP production and downstream beta-cell function, with both activities being dependent on the presence of beta-cell Gαz.
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Affiliation(s)
- Michael D Schaid
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Interdepartmental Graduate Program in Nutritional Sciences, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Cara L Green
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Darby C Peter
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Shannon J Gallagher
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Erin Guthery
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Kathryn A Carbajal
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Jeffrey M Harrington
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Grant M Kelly
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Austin Reuter
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Molly L Wehner
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Allison L Brill
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Joshua C Neuman
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Interdepartmental Graduate Program in Nutritional Sciences, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Dudley W Lamming
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Interdepartmental Graduate Program in Nutritional Sciences, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Michelle E Kimple
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA; Interdepartmental Graduate Program in Nutritional Sciences, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA; Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA; Department of Cell and Regenerative Biology, University of Wisconsin- Madison School of Medicine and Public Health, Madison, Wisconsin, USA.
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11
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Denwood G, Tarasov A, Salehi A, Vergari E, Ramracheya R, Takahashi H, Nikolaev VO, Seino S, Gribble F, Reimann F, Rorsman P, Zhang Q. Glucose stimulates somatostatin secretion in pancreatic δ-cells by cAMP-dependent intracellular Ca 2+ release. J Gen Physiol 2019; 151:1094-1115. [PMID: 31358556 PMCID: PMC6719402 DOI: 10.1085/jgp.201912351] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/11/2019] [Accepted: 07/09/2019] [Indexed: 12/12/2022] Open
Abstract
Somatostatin secretion from pancreatic islet δ-cells is stimulated by elevated glucose levels, but the underlying mechanisms have only partially been elucidated. Here we show that glucose-induced somatostatin secretion (GISS) involves both membrane potential-dependent and -independent pathways. Although glucose-induced electrical activity triggers somatostatin release, the sugar also stimulates GISS via a cAMP-dependent stimulation of CICR and exocytosis of somatostatin. The latter effect is more quantitatively important and in mouse islets depolarized by 70 mM extracellular K+ , increasing glucose from 1 mM to 20 mM produced an ∼3.5-fold stimulation of somatostatin secretion, an effect that was mimicked by the application of the adenylyl cyclase activator forskolin. Inhibiting cAMP-dependent pathways with PKI or ESI-05, which inhibit PKA and exchange protein directly activated by cAMP 2 (Epac2), respectively, reduced glucose/forskolin-induced somatostatin secretion. Ryanodine produced a similar effect that was not additive to that of the PKA or Epac2 inhibitors. Intracellular application of cAMP produced a concentration-dependent stimulation of somatostatin exocytosis and elevation of cytoplasmic Ca2+ ([Ca2+]i). Both effects were inhibited by ESI-05 and thapsigargin (an inhibitor of SERCA). By contrast, inhibition of PKA suppressed δ-cell exocytosis without affecting [Ca2+]i Simultaneous recordings of electrical activity and [Ca2+]i in δ-cells expressing the genetically encoded Ca2+ indicator GCaMP3 revealed that the majority of glucose-induced [Ca2+]i spikes did not correlate with δ-cell electrical activity but instead reflected Ca2+ release from the ER. These spontaneous [Ca2+]i spikes are resistant to PKI but sensitive to ESI-05 or thapsigargin. We propose that cAMP links an increase in plasma glucose to stimulation of somatostatin secretion by promoting CICR, thus evoking exocytosis of somatostatin-containing secretory vesicles in the δ-cell.
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Affiliation(s)
- Geoffrey Denwood
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Andrei Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, UK
| | - Albert Salehi
- Institute of Neuroscience and Physiology, Department of Physiology, Metabolic Research Unit, University of Goteborg, Göteborg, Sweden
| | - Elisa Vergari
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Reshma Ramracheya
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Harumi Takahashi
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Susumo Seino
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Fiona Gribble
- Institute of Metabolic Science, University of Cambridge, Addenbrook's Hospital, Cambridge, UK
| | - Frank Reimann
- Institute of Metabolic Science, University of Cambridge, Addenbrook's Hospital, Cambridge, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
- Institute of Neuroscience and Physiology, Department of Physiology, Metabolic Research Unit, University of Goteborg, Göteborg, Sweden
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
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12
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Tomas A, Jones B, Leech C. New Insights into Beta-Cell GLP-1 Receptor and cAMP Signaling. J Mol Biol 2019; 432:1347-1366. [PMID: 31446075 DOI: 10.1016/j.jmb.2019.08.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 08/06/2019] [Accepted: 08/13/2019] [Indexed: 12/14/2022]
Abstract
Harnessing the translational potential of the GLP-1/GLP-1R system in pancreatic beta cells has led to the development of established GLP-1R-based therapies for the long-term preservation of beta cell function. In this review, we discuss recent advances in the current research on the GLP-1/GLP-1R system in beta cells, including the regulation of signaling by endocytic trafficking as well as the application of concepts such as signal bias, allosteric modulation, dual agonism, polymorphic receptor variants, spatial compartmentalization of cAMP signaling and new downstream signaling targets involved in the control of beta cell function.
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Affiliation(s)
- Alejandra Tomas
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 0NN, UK.
| | - Ben Jones
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 0NN, UK
| | - Colin Leech
- Department of Surgery, State University of New York, Upstate Medical University, Syracuse, NY, 13210, USA
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13
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Karamitri A, Plouffe B, Bonnefond A, Chen M, Gallion J, Guillaume JL, Hegron A, Boissel M, Canouil M, Langenberg C, Wareham NJ, Le Gouill C, Lukasheva V, Lichtarge O, Froguel P, Bouvier M, Jockers R. Type 2 diabetes-associated variants of the MT 2 melatonin receptor affect distinct modes of signaling. Sci Signal 2018; 11:11/545/eaan6622. [PMID: 30154102 DOI: 10.1126/scisignal.aan6622] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Melatonin is produced during the night and regulates sleep and circadian rhythms. Loss-of-function variants in MTNR1B, which encodes the melatonin receptor MT2, a G protein-coupled receptor (GPCR), are associated with an increased risk of type 2 diabetes (T2D). To identify specific T2D-associated signaling pathway(s), we profiled the signaling output of 40 MT2 variants by monitoring spontaneous (ligand-independent) and melatonin-induced activation of multiple signaling effectors. Genetic association analysis showed that defects in the melatonin-induced activation of Gαi1 and Gαz proteins and in spontaneous β-arrestin2 recruitment to MT2 were the most statistically significantly associated with an increased T2D risk. Computational variant impact prediction by in silico evolutionary lineage analysis strongly correlated with the measured phenotypic effect of each variant, providing a predictive tool for future studies on GPCR variants. Together, this large-scale functional study provides an operational framework for the postgenomic analysis of the multiple GPCR variants present in the human population. The association of T2D risk with signaling pathway-specific defects opens avenues for pathway-specific personalized therapeutic intervention and reveals the potential relevance of MT2 function during the day, when melatonin is undetectable, but spontaneous activity of the receptor occurs.
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Affiliation(s)
- Angeliki Karamitri
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS UMR 8104, Paris, France.,Université Paris Descartes, Paris, France
| | - Bianca Plouffe
- Institute for Research in Immunology and Cancer and Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Amélie Bonnefond
- Université Lille, CNRS UMR 8199-EGID, Institut Pasteur de Lille, Lille, France
| | - Min Chen
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS UMR 8104, Paris, France.,Université Paris Descartes, Paris, France
| | - Jonathan Gallion
- Structural Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jean-Luc Guillaume
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS UMR 8104, Paris, France.,Université Paris Descartes, Paris, France
| | - Alan Hegron
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS UMR 8104, Paris, France.,Université Paris Descartes, Paris, France
| | - Mathilde Boissel
- Université Lille, CNRS UMR 8199-EGID, Institut Pasteur de Lille, Lille, France
| | - Mickaël Canouil
- Université Lille, CNRS UMR 8199-EGID, Institut Pasteur de Lille, Lille, France
| | - Claudia Langenberg
- Medical Research Council (MRC) Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge CB2 0QQ, UK
| | - Nicholas J Wareham
- Medical Research Council (MRC) Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge CB2 0QQ, UK
| | - Christian Le Gouill
- Institute for Research in Immunology and Cancer and Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Viktoria Lukasheva
- Institute for Research in Immunology and Cancer and Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Olivier Lichtarge
- Structural Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Philippe Froguel
- Université Lille, CNRS UMR 8199-EGID, Institut Pasteur de Lille, Lille, France. .,Department of Genomics of Common Disease, School of Public Health, Imperial College London, Hammersmith Hospital, W12 0NN London, UK
| | - Michel Bouvier
- Institute for Research in Immunology and Cancer and Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Québec H3C 3J7, Canada.
| | - Ralf Jockers
- Inserm, U1016, Institut Cochin, Paris, France. .,CNRS UMR 8104, Paris, France.,Université Paris Descartes, Paris, France
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14
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Fenske RJ, Kimple ME. Targeting dysfunctional beta-cell signaling for the potential treatment of type 1 diabetes mellitus. Exp Biol Med (Maywood) 2018; 243:586-591. [PMID: 29504478 DOI: 10.1177/1535370218761662] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Since its discovery and purification by Frederick Banting in 1921, exogenous insulin has remained almost the sole therapy for type 1 diabetes mellitus. While insulin alleviates the primary dysfunction of the disease, many other aspects of the pathophysiology of type 1 diabetes mellitus are unaffected. Research aimed towards the discovery of novel type 1 diabetes mellitus therapeutics targeting different cell signaling pathways is gaining momentum. The focus of these efforts has been almost entirely on the impact of immunomodulatory drugs, particularly those that have already received FDA-approval for other autoimmune diseases. However, these drugs can often have severe side effects, while also putting already immunocompromised individuals at an increased risk for other infections. Potential therapeutic targets in the insulin-producing beta-cell have been largely ignored by the type 1 diabetes mellitus field, save the glucagon-like peptide 1 receptor. While there is preliminary evidence to support the clinical exploration of glucagon-like peptide 1 receptor-based drugs as type 1 diabetes mellitus adjuvant therapeutics, there is a vast space for other putative therapeutic targets to be explored. The alpha subunit of the heterotrimeric Gz protein (Gαz) has been shown to promote beta-cell inflammation, dysfunction, death, and failure to replicate in the context of diabetes in a number of mouse models. Genetic loss of Gαz or inhibition of the Gαz signaling pathway through dietary interventions is protective against the development of insulitis and hyperglycemia. The multifaceted effects of Gαz in regards to beta-cell health in the context of diabetes make it an ideal therapeutic target for further study. It is our belief that a low-risk, effective therapy for type 1 diabetes mellitus will involve a multidimensional approach targeting a number of regulatory systems, not the least of which is the insulin-producing beta-cell. Impact statement The expanding investigation of beta-cell therapeutic targets for the treatment and prevention of type 1 diabetes mellitus is fundamentally relevant and timely. This review summarizes the overall scope of research into novel type 1 diabetes mellitus therapeutics, highlighting weaknesses or caveats in current clinical trials as well as describing potential new targets to pursue. More specifically, signaling proteins that act as modulators of beta-cell function, survival, and replication, as well as immune infiltration may need to be targeted to develop the most efficient pharmaceutical interventions for type 1 diabetes mellitus. One such beta-cell signaling pathway, mediated by the alpha subunit of the heterotrimeric Gz protein (Gαz), is discussed in more detail. The work described here will be critical in moving the field forward as it emphasizes the central role of the beta-cell in type 1 diabetes mellitus disease pathology.
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Affiliation(s)
- Rachel J Fenske
- 1 Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.,2 Department of Medicine, Division of Endocrinology, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA.,3 Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA
| | - Michelle E Kimple
- 1 Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.,2 Department of Medicine, Division of Endocrinology, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA.,3 Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA.,4 Department of Cell and Regenerative Biology, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA
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15
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Gnaz couples the circadian and dopaminergic system to G protein-mediated signaling in mouse photoreceptors. PLoS One 2017; 12:e0187411. [PMID: 29088301 PMCID: PMC5663513 DOI: 10.1371/journal.pone.0187411] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/19/2017] [Indexed: 01/08/2023] Open
Abstract
The mammalian retina harbors a circadian clockwork that regulates vision and promotes healthiness of retinal neurons, mainly through directing the rhythmic release of the neurohormones dopamine—acting on dopamine D4 receptors—and melatonin—acting on MT1 and MT2 receptors. The gene Gnaz—a unique Gi/o subfamily member—was seen in the present study to be expressed in photoreceptors where its protein product Gαz shows a daily rhythm in its subcellular localization. Apart from subcellular localization, Gnaz displays a daily rhythm in expression—with peak values at night—in preparations of the whole retina, microdissected photoreceptors and photoreceptor-related pinealocytes. In retina, Gnaz rhythmicity was observed to persist under constant darkness and to be abolished in retina deficient for Clock or dopamine D4 receptors. Furthermore, circadian regulation of Gnaz was disturbed in the db/db mouse, a model of diabetic retinopathy. The data of the present study suggest that Gnaz links the circadian clockwork—via dopamine acting on D4 receptors—to G protein-mediated signaling in intact but not diabetic retina.
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16
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Kowluru A. Role of G-proteins in islet function in health and diabetes. Diabetes Obes Metab 2017; 19 Suppl 1:63-75. [PMID: 28880478 PMCID: PMC5657296 DOI: 10.1111/dom.13011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/03/2017] [Accepted: 05/12/2017] [Indexed: 12/17/2022]
Abstract
Glucose-stimulated insulin secretion (GSIS) involves interplay between metabolic and cationic events. Seminal contributions from multiple laboratories affirm essential roles for small G-proteins (Rac1, Cdc42, Arf6, Rab27A) in GSIS. Activation of these signalling proteins promotes cytoskeletal remodeling, transport and docking of insulin granules on the plasma membrane for exocytotic secretion of insulin. Evidence in rodent and human islets suggests key roles for lipidation (farnesylation and geranylgeranylation) of these G-proteins for their targeting to appropriate cellular compartments for optimal regulation of effectors leading to GSIS. Interestingly, however, inhibition of prenylation appears to cause mislocalization of non-prenylated, but (paradoxically) activated G-proteins, in "inappropriate" compartments leading to activation of stress kinases and onset of mitochondrial defects, loss in GSIS and apoptosis of the islet β-cell. This review highlights our current understanding of roles of G-proteins and their post-translational lipidation (prenylation) signalling networks in islet function in normal health, metabolic stress (glucolipotoxicity and ER stress) and diabetes. Critical knowledge gaps that need to be addressed for the development of therapeutics to halt defects in these signalling steps in β-cells in models of impaired insulin secretion and diabetes are also highlighted and discussed.
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Affiliation(s)
- Anjaneyulu Kowluru
- β-Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, and Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan
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17
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Layden BT, Wicksteed B, Mauvais-Jarvis F. Incretin-Based Therapies: Revisiting Their Mode of Action. Endocrinology 2017; 158:1560-1563. [PMID: 28575434 PMCID: PMC5460946 DOI: 10.1210/en.2017-00252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 03/15/2017] [Indexed: 01/15/2023]
Affiliation(s)
- Brian T Layden
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Illinois at Chicago, Chicago, Illinois 60612
- Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois 60612
| | - Barton Wicksteed
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Franck Mauvais-Jarvis
- Diabetes Research and Gender Medicine Laboratory, Section of Endocrinology and Metabolism, Department of Medicine, Tulane University Health Sciences Center, New Orleans, Louisiana 70112
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18
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Fenske RJ, Cadena MT, Harenda QE, Wienkes HN, Carbajal K, Schaid MD, Laundre E, Brill AL, Truchan NA, Brar H, Wisinski J, Cai J, Graham TE, Engin F, Kimple ME. The Inhibitory G Protein α-Subunit, Gαz, Promotes Type 1 Diabetes-Like Pathophysiology in NOD Mice. Endocrinology 2017; 158:1645-1658. [PMID: 28419211 PMCID: PMC5460933 DOI: 10.1210/en.2016-1700] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 04/11/2017] [Indexed: 01/23/2023]
Abstract
The α-subunit of the heterotrimeric Gz protein, Gαz, promotes β-cell death and inhibits β-cell replication when pancreatic islets are challenged by stressors. Thus, we hypothesized that loss of Gαz protein would preserve functional β-cell mass in the nonobese diabetic (NOD) model, protecting from overt diabetes. We saw that protection from diabetes was robust and durable up to 35 weeks of age in Gαz knockout mice. By 17 weeks of age, Gαz-null NOD mice had significantly higher diabetes-free survival than wild-type littermates. Islets from these mice had reduced markers of proinflammatory immune cell infiltration on both the histological and transcript levels and secreted more insulin in response to glucose. Further analyses of pancreas sections revealed significantly fewer terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL)-positive β-cells in Gαz-null islets despite similar immune infiltration in control mice. Islets from Gαz-null mice also exhibited a higher percentage of Ki-67-positive β-cells, a measure of proliferation, even in the presence of immune infiltration. Finally, β-cell-specific Gαz-null mice phenocopy whole-body Gαz-null mice in their protection from developing hyperglycemia after streptozotocin administration, supporting a β-cell-centric role for Gαz in diabetes pathophysiology. We propose that Gαz plays a key role in β-cell signaling that becomes dysfunctional in the type 1 diabetes setting, accelerating the death of β-cells, which promotes further accumulation of immune cells in the pancreatic islets, and inhibiting a restorative proliferative response.
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MESH Headings
- Animals
- Apoptosis/genetics
- Blood Glucose/metabolism
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/pathology
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/pathology
- Female
- GTP-Binding Protein alpha Subunits/genetics
- Insulin-Secreting Cells/metabolism
- Insulin-Secreting Cells/physiology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred NOD
- Mice, Knockout
- Mice, Transgenic
- Streptozocin
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Affiliation(s)
- Rachel J. Fenske
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Mark T. Cadena
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Quincy E. Harenda
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Haley N. Wienkes
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Kathryn Carbajal
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Michael D. Schaid
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Erin Laundre
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Allison L. Brill
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Nathan A. Truchan
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Harpreet Brar
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Jaclyn Wisinski
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Jinjin Cai
- Molecular Medicine Program, Department of Medicine, Division of Endocrinology, Metabolism, and Diabetes, Department of Nutrition, and Department of Biological Chemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112
- George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah 84112
| | - Timothy E. Graham
- Molecular Medicine Program, Department of Medicine, Division of Endocrinology, Metabolism, and Diabetes, Department of Nutrition, and Department of Biological Chemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112
- George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah 84112
| | - Feyza Engin
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Michelle E. Kimple
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin-Madison, Madison, Wisconsin 53705
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin 53705
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19
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Carboneau BA, Breyer RM, Gannon M. Regulation of pancreatic β-cell function and mass dynamics by prostaglandin signaling. J Cell Commun Signal 2017; 11:105-116. [PMID: 28132118 DOI: 10.1007/s12079-017-0377-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 01/16/2017] [Indexed: 01/09/2023] Open
Abstract
Prostaglandins (PGs) are signaling lipids derived from arachidonic acid (AA), which is metabolized by cyclooxygenase (COX)-1 or 2 and class-specific synthases to generate PGD2, PGE2, PGF2α, PGI2 (prostacyclin), and thromboxane A2. PGs signal through G-protein coupled receptors (GPCRs) and are important modulators of an array of physiological functions, including systemic inflammation and insulin secretion from pancreatic islets. The role of PGs in β-cell function has been an active area of interest, beginning in the 1970s. Early studies demonstrated that PGE2 inhibits glucose-stimulated insulin secretion (GSIS), although more recent studies have questioned this inhibitory action of PGE2. The PGE2 receptor EP3 and one of the G-proteins that couples to EP3, GαZ, have been identified as negative regulators of β-cell proliferation and survival. Conversely, PGI2 and its receptor, IP, play a positive role in the β-cell by enhancing GSIS and preserving β-cell mass in response to the β-cell toxin streptozotocin (STZ). In comparison to PGE2 and PGI2, little is known about the function of the remaining PGs within islets. In this review, we discuss the roles of PGs, particularly PGE2 and PGI2, PG receptors, and downstream signaling events that alter β-cell function and regulation of β-cell mass.
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Affiliation(s)
- Bethany A Carboneau
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.,Program in Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Richard M Breyer
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA.,Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, USA
| | - Maureen Gannon
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA. .,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA. .,Program in Developmental Biology, Vanderbilt University, Nashville, TN, USA. .,Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA. .,Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, USA.
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Zhao Y, Fang Q, Straub SG, Lindau M, Sharp GWG. Prostaglandin E1 inhibits endocytosis in the β-cell endocytosis. J Endocrinol 2016; 229:287-94. [PMID: 27068696 DOI: 10.1530/joe-15-0435] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 04/11/2016] [Indexed: 12/23/2022]
Abstract
Prostaglandins inhibit insulin secretion in a manner similar to that of norepinephrine (NE) and somatostatin. As NE inhibits endocytosis as well as exocytosis, we have now examined the modulation of endocytosis by prostaglandin E1 (PGE1). Endocytosis following exocytosis was recorded by whole-cell patch clamp capacitance measurements in INS-832/13 cells. Prolonged depolarizing pulses producing a high level of Ca(2+) influx were used to stimulate maximal exocytosis and to deplete the readily releasable pool (RRP) of granules. This high Ca(2+) influx eliminates the inhibitory effect of PGE1 on exocytosis and allows specific characterization of the inhibitory effect of PGE1 on the subsequent compensatory endocytosis. After stimulating exocytosis, endocytosis was apparent under control conditions but was inhibited by PGE1 in a Pertussis toxin-sensitive (PTX)-insensitive manner. Dialyzing a synthetic peptide mimicking the C-terminus of the α-subunit of the heterotrimeric G-protein Gz into the cells blocked the inhibition of endocytosis by PGE1, whereas a control-randomized peptide was without effect. These results demonstrate that PGE1 inhibits endocytosis and Gz mediates the inhibition.
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Affiliation(s)
- Ying Zhao
- Department of Molecular MedicineCornell University, Ithaca, New York, USA School of Applied and Engineering PhysicsCornell University, Ithaca, New York, USA Laboratory for Nanoscale Cell BiologyMax-Planck-Institute for Biophysical Chemistry, Goettingen, Germany
| | - Qinghua Fang
- School of Applied and Engineering PhysicsCornell University, Ithaca, New York, USA Laboratory for Nanoscale Cell BiologyMax-Planck-Institute for Biophysical Chemistry, Goettingen, Germany
| | - Susanne G Straub
- Department of Molecular MedicineCornell University, Ithaca, New York, USA
| | - Manfred Lindau
- School of Applied and Engineering PhysicsCornell University, Ithaca, New York, USA Laboratory for Nanoscale Cell BiologyMax-Planck-Institute for Biophysical Chemistry, Goettingen, Germany
| | - Geoffrey W G Sharp
- Department of Molecular MedicineCornell University, Ithaca, New York, USA
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21
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Brill AL, Wisinski JA, Cadena MT, Thompson MF, Fenske RJ, Brar HK, Schaid MD, Pasker RL, Kimple ME. Synergy Between Gαz Deficiency and GLP-1 Analog Treatment in Preserving Functional β-Cell Mass in Experimental Diabetes. Mol Endocrinol 2016; 30:543-56. [PMID: 27049466 DOI: 10.1210/me.2015-1164] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A defining characteristic of type 1 diabetes mellitus (T1DM) pathophysiology is pancreatic β-cell death and dysfunction, resulting in insufficient insulin secretion to properly control blood glucose levels. Treatments that promote β-cell replication and survival, thus reversing the loss of β-cell mass, while also preserving β-cell function, could lead to a real cure for T1DM. The α-subunit of the heterotrimeric Gz protein, Gαz, is a tonic negative regulator of adenylate cyclase and downstream cAMP production. cAMP is one of a few identified signaling molecules that can simultaneously have a positive impact on pancreatic islet β-cell proliferation, survival, and function. The purpose of our study was to determine whether mice lacking Gαz might be protected, at least partially, from β-cell loss and dysfunction after streptozotocin treatment. We also aimed to determine whether Gαz might act in concert with an activator of the cAMP-stimulatory glucagon-like peptide 1 receptor, exendin-4 (Ex4). Without Ex4 treatment, Gαz-null mice still developed hyperglycemia, albeit delayed. The same finding held true for wild-type mice treated with Ex4. With Ex4 treatment, Gαz-null mice were protected from developing severe hyperglycemia. Immunohistological studies performed on pancreas sections and in vitro apoptosis, cytotoxicity, and survival assays demonstrated a clear effect of Gαz signaling on pancreatic β-cell replication and death; β-cell function was also improved in Gαz-null islets. These data support our hypothesis that a combination of therapies targeting both stimulatory and inhibitory pathways will be more effective than either alone at protecting, preserving, and possibly regenerating β-cell mass and function in T1DM.
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Affiliation(s)
- Allison L Brill
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Jaclyn A Wisinski
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Mark T Cadena
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Mary F Thompson
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Rachel J Fenske
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Harpreet K Brar
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Michael D Schaid
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Renee L Pasker
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
| | - Michelle E Kimple
- Department of Medicine (A.L.B., J.A.W., M.T.C., M.F.T., H.K.B., R.L.P., M.E.K.), Division of Endocrinology, Diabetes, and Metabolism; Department of Cell and Regenerative Biology (M.E.K.); and Interdisciplinary Graduate Program in Nutritional Sciences (R.J.F., M.D.S., M.E.K.), University of Wisconsin-Madison, Madison; and Research Service (A.L.B., J.A.W., M.T.C., M.F.T., R.J.F., H.K.B., M.D.S., M.E.K.), William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705
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Priyadarshini M, Villa SR, Fuller M, Wicksteed B, Mackay CR, Alquier T, Poitout V, Mancebo H, Mirmira RG, Gilchrist A, Layden BT. An Acetate-Specific GPCR, FFAR2, Regulates Insulin Secretion. Mol Endocrinol 2015; 29:1055-66. [PMID: 26075576 DOI: 10.1210/me.2015-1007] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
G protein-coupled receptors have been well described to contribute to the regulation of glucose-stimulated insulin secretion (GSIS). The short-chain fatty acid-sensing G protein-coupled receptor, free fatty acid receptor 2 (FFAR2), is expressed in pancreatic β-cells, and in rodents, its expression is altered during insulin resistance. Thus, we explored the role of FFAR2 in regulating GSIS. First, assessing the phenotype of wild-type and Ffar2(-/-) mice in vivo, we observed no differences with regard to glucose homeostasis on normal or high-fat diet, with a marginally significant defect in insulin secretion in Ffar2(-/-) mice during hyperglycemic clamps. In ex vivo insulin secretion studies, we observed diminished GSIS from Ffar2(-/-) islets relative to wild-type islets under high-glucose conditions. Further, in the presence of acetate, the primary endogenous ligand for FFAR2, we observed FFAR2-dependent potentiation of GSIS, whereas FFAR2-specific agonists resulted in either potentiation or inhibition of GSIS, which we found to result from selective signaling through either Gαq/11 or Gαi/o, respectively. Lastly, in ex vivo insulin secretion studies of human islets, we observed that acetate and FFAR2 agonists elicited different signaling properties at human FFAR2 than at mouse FFAR2. Taken together, our studies reveal that FFAR2 signaling occurs by divergent G protein pathways that can selectively potentiate or inhibit GSIS in mouse islets. Further, we have identified important differences in the response of mouse and human FFAR2 to selective agonists, and we suggest that these differences warrant consideration in the continued investigation of FFAR2 as a novel type 2 diabetes target.
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Affiliation(s)
- Medha Priyadarshini
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
| | - Stephanie R Villa
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
| | - Miles Fuller
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
| | - Barton Wicksteed
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
| | - Charles R Mackay
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
| | - Thierry Alquier
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
| | - Vincent Poitout
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
| | - Helena Mancebo
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
| | - Raghavendra G Mirmira
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
| | - Annette Gilchrist
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
| | - Brian T Layden
- Division of Endocrinology, Metabolism, and Molecular Medicine (M.P., S.R.V., M.F., B.T.L.), Northwestern University, Chicago, Illinois 60611; Kovler Diabetes Center (B.W.), The University of Chicago, Chicago, Illinois 60637; Monash University (C.R.M.), Clayton, Victoria 3800, Australia; Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, and Department of Medicine (T.A., V.P.), University of Montreal, Quebec, H2X 0A9 Canada; Multispan (H.M.), Hayward, California 94545; Department of Pediatrics and the Herman B Wells Center for Pediatric Research (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 4602; Department of Biochemistry and Molecular Biology (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine (R.G.M.), Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Pharmaceutical Sciences (A.G.), Midwestern University, Downers Grove, Illinois 60515; and Jesse Brown Veterans Affairs Medical Center (B.T.L.), Chicago, Illinois 60612
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Linnemann AK, Neuman JC, Battiola TJ, Wisinski JA, Kimple ME, Davis DB. Glucagon-Like Peptide-1 Regulates Cholecystokinin Production in β-Cells to Protect From Apoptosis. Mol Endocrinol 2015; 29:978-87. [PMID: 25984632 DOI: 10.1210/me.2015-1030] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cholecystokinin (CCK) is a classic gut hormone that is also expressed in the pancreatic islet, where it is highly up-regulated with obesity. Loss of CCK results in increased β-cell apoptosis in obese mice. Similarly, islet α-cells produce increased amounts of another gut peptide, glucagon-like peptide 1 (GLP-1), in response to cytokine and nutrient stimulation. GLP-1 also protects β-cells from apoptosis via cAMP-mediated mechanisms. Therefore, we hypothesized that the activation of islet-derived CCK and GLP-1 may be linked. We show here that both human and mouse islets secrete active GLP-1 as a function of body mass index/obesity. Furthermore, GLP-1 can rapidly stimulate β-cell CCK production and secretion through direct targeting by the cAMP-modulated transcription factor, cAMP response element binding protein (CREB). We find that cAMP-mediated signaling is required for Cck expression, but CCK regulation by cAMP does not require stimulatory levels of glucose or insulin secretion. We also show that CREB directly targets the Cck promoter in islets from obese (Leptin(ob/ob)) mice. Finally, we demonstrate that the ability of GLP-1 to protect β-cells from cytokine-induced apoptosis is partially dependent on CCK receptor signaling. Taken together, our work suggests that in obesity, active GLP-1 produced in the islet stimulates CCK production and secretion in a paracrine manner via cAMP and CREB. This intraislet incretin loop may be one mechanism whereby GLP-1 protects β-cells from apoptosis.
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Affiliation(s)
- Amelia K Linnemann
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
| | - Joshua C Neuman
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
| | - Therese J Battiola
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
| | - Jaclyn A Wisinski
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
| | - Michelle E Kimple
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
| | - Dawn Belt Davis
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
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Truchan NA, Brar HK, Gallagher SJ, Neuman JC, Kimple ME. A single-islet microplate assay to measure mouse and human islet insulin secretion. Islets 2015; 7:e1076607. [PMID: 26452321 PMCID: PMC4708880 DOI: 10.1080/19382014.2015.1076607] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
One complication to comparing β-cell function among islet preparations, whether from genetically identical or diverse animals or human organ donors, is the number of islets required per assay. Islet numbers can be limiting, meaning that fewer conditions can be tested; other islet measurements must be excluded; or islets must be pooled from multiple animals/donors for each experiment. Furthermore, pooling islets negates the possibility of performing single-islet comparisons. Our aim was to validate a 96-well plate-based single islet insulin secretion assay that would be as robust as previously published methods to quantify glucose-stimulated insulin secretion from mouse and human islets. First, we tested our new assay using mouse islets, showing robust stimulation of insulin secretion 24 or 48 h after islet isolation. Next, we utilized the assay to quantify mouse islet function on an individual islet basis, measurements that would not be possible with the standard pooled islet assay methods. Next, we validated our new assay using human islets obtained from the Integrated Islet Distribution Program (IIDP). Human islets are known to have widely varying insulin secretion capacity, and using our new assay we reveal biologically relevant factors that are significantly correlated with human islet function, whether displayed as maximal insulin secretion response or fold-stimulation of insulin secretion. Overall, our results suggest this new microplate assay will be a useful tool for many laboratories, expert or not in islet techniques, to be able to precisely quantify islet insulin secretion from their models of interest.
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Affiliation(s)
- Nathan A Truchan
- Department of Medicine; Division of Endocrinology, Diabetes & Metabolism; University of Wisconsin-Madison; Madison, WI USA
- William S Middleton Memorial Veterans Hospital; Madison, WI USA
| | - Harpreet K Brar
- Department of Medicine; Division of Endocrinology, Diabetes & Metabolism; University of Wisconsin-Madison; Madison, WI USA
- William S Middleton Memorial Veterans Hospital; Madison, WI USA
| | - Shannon J Gallagher
- Department of Medicine; Division of Endocrinology, Diabetes & Metabolism; University of Wisconsin-Madison; Madison, WI USA
- William S Middleton Memorial Veterans Hospital; Madison, WI USA
| | - Joshua C Neuman
- Interdisciplinary Graduate Program in Nutritional Sciences; University of Wisconsin-Madison; Madison, WI USA
- William S Middleton Memorial Veterans Hospital; Madison, WI USA
| | - Michelle E Kimple
- Department of Medicine; Division of Endocrinology, Diabetes & Metabolism; University of Wisconsin-Madison; Madison, WI USA
- Interdisciplinary Graduate Program in Nutritional Sciences; University of Wisconsin-Madison; Madison, WI USA
- William S Middleton Memorial Veterans Hospital; Madison, WI USA
- Correspondence to: Michelle E Kimple;
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Kimple ME, Neuman JC, Linnemann AK, Casey PJ. Inhibitory G proteins and their receptors: emerging therapeutic targets for obesity and diabetes. Exp Mol Med 2014; 46:e102. [PMID: 24946790 PMCID: PMC4081554 DOI: 10.1038/emm.2014.40] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 02/10/2014] [Accepted: 02/17/2014] [Indexed: 12/21/2022] Open
Abstract
The worldwide prevalence of obesity is steadily increasing, nearly doubling between 1980 and 2008. Obesity is often associated with insulin resistance, a major risk factor for type 2 diabetes mellitus (T2DM): a costly chronic disease and serious public health problem. The underlying cause of T2DM is a failure of the beta cells of the pancreas to continue to produce enough insulin to counteract insulin resistance. Most current T2DM therapeutics do not prevent continued loss of insulin secretion capacity, and those that do have the potential to preserve beta cell mass and function are not effective in all patients. Therefore, developing new methods for preventing and treating obesity and T2DM is very timely and of great significance. There is now considerable literature demonstrating a link between inhibitory guanine nucleotide-binding protein (G protein) and G protein-coupled receptor (GPCR) signaling in insulin-responsive tissues and the pathogenesis of obesity and T2DM. These studies are suggesting new and emerging therapeutic targets for these conditions. In this review, we will discuss inhibitory G proteins and GPCRs that have primary actions in the beta cell and other peripheral sites as therapeutic targets for obesity and T2DM, improving satiety, insulin resistance and/or beta cell biology.
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Affiliation(s)
- Michelle E Kimple
- Department of Medicine-Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA
| | - Joshua C Neuman
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Amelia K Linnemann
- Department of Medicine-Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA
| | - Patrick J Casey
- Duke University Medical Center Department of Pharmacology and Cancer Biology, Durham, NC, USA
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Engelstoft MS, Park WM, Sakata I, Kristensen LV, Husted AS, Osborne-Lawrence S, Piper PK, Walker AK, Pedersen MH, Nøhr MK, Pan J, Sinz CJ, Carrington PE, Akiyama TE, Jones RM, Tang C, Ahmed K, Offermanns S, Egerod KL, Zigman JM, Schwartz TW. Seven transmembrane G protein-coupled receptor repertoire of gastric ghrelin cells. Mol Metab 2013; 2:376-92. [PMID: 24327954 DOI: 10.1016/j.molmet.2013.08.006] [Citation(s) in RCA: 241] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 08/26/2013] [Indexed: 12/18/2022] Open
Abstract
The molecular mechanisms regulating secretion of the orexigenic-glucoregulatory hormone ghrelin remain unclear. Based on qPCR analysis of FACS-purified gastric ghrelin cells, highly expressed and enriched 7TM receptors were comprehensively identified and functionally characterized using in vitro, ex vivo and in vivo methods. Five Gαs-coupled receptors efficiently stimulated ghrelin secretion: as expected the β1-adrenergic, the GIP and the secretin receptors but surprisingly also the composite receptor for the sensory neuropeptide CGRP and the melanocortin 4 receptor. A number of Gαi/o-coupled receptors inhibited ghrelin secretion including somatostatin receptors SSTR1, SSTR2 and SSTR3 and unexpectedly the highly enriched lactate receptor, GPR81. Three other metabolite receptors known to be both Gαi/o- and Gαq/11-coupled all inhibited ghrelin secretion through a pertussis toxin-sensitive Gαi/o pathway: FFAR2 (short chain fatty acid receptor; GPR43), FFAR4 (long chain fatty acid receptor; GPR120) and CasR (calcium sensing receptor). In addition to the common Gα subunits three non-common Gαi/o subunits were highly enriched in ghrelin cells: GαoA, GαoB and Gαz. Inhibition of Gαi/o signaling via ghrelin cell-selective pertussis toxin expression markedly enhanced circulating ghrelin. These 7TM receptors and associated Gα subunits constitute a major part of the molecular machinery directly mediating neuronal and endocrine stimulation versus metabolite and somatostatin inhibition of ghrelin secretion including a series of novel receptor targets not previously identified on the ghrelin cell.
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Key Words
- 7TM, seven transmembrane segment
- BAC, bacterial artificial chromosome
- CCK, cholecystokinin
- CFMB, (S)-2-(4-chlorophenyl)-3,3-dimethyl-N-(5-phenylthiazol-2-yl)butamide
- CGRP, calcitonin gene-related peptide
- CHBA, 3-chloro-5-hydroxybenzoic acid
- Enteroendocrine
- G protein signaling
- GIP, glucose-dependent insulinotropic polypeptide
- GLP-1, glucagon-like peptide 1
- GPCR
- Ghrelin
- Metabolites
- PTx, Bordetella pertussis toxin
- PYY, peptide YY
- Secretion
- hrGFP, humanized Renilla reniformis green fluorescent protein
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Affiliation(s)
- Maja S Engelstoft
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section for Metabolic Receptology and Enteroendocrinology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark ; Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark
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27
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Kimple ME, Keller MP, Rabaglia MR, Pasker RL, Neuman JC, Truchan NA, Brar HK, Attie AD. Prostaglandin E2 receptor, EP3, is induced in diabetic islets and negatively regulates glucose- and hormone-stimulated insulin secretion. Diabetes 2013; 62:1904-12. [PMID: 23349487 PMCID: PMC3661627 DOI: 10.2337/db12-0769] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BTBR mice develop severe diabetes in response to genetically induced obesity due to a failure of the β-cells to compensate for peripheral insulin resistance. In analyzing BTBR islet gene expression patterns, we observed that Pgter3, the gene for the prostaglandin E receptor 3 (EP3), was upregulated with diabetes. The EP3 receptor is stimulated by prostaglandin E2 (PGE2) and couples to G-proteins of the Gi subfamily to decrease intracellular cAMP, blunting glucose-stimulated insulin secretion (GSIS). Also upregulated were several genes involved in the synthesis of PGE2. We hypothesized that increased signaling through EP3 might be coincident with the development of diabetes and contribute to β-cell dysfunction. We confirmed that the PGE2-to-EP3 signaling pathway was active in islets from confirmed diabetic BTBR mice and human cadaveric donors, with increased EP3 expression, PGE2 production, and function of EP3 agonists and antagonists to modulate cAMP production and GSIS. We also analyzed the impact of EP3 receptor activation on signaling through the glucagon-like peptide (GLP)-1 receptor. We demonstrated that EP3 agonists antagonize GLP-1 signaling, decreasing the maximal effect that GLP-1 can elicit on cAMP production and GSIS. Taken together, our results identify EP3 as a new therapeutic target for β-cell dysfunction in T2D.
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Affiliation(s)
- Michelle E. Kimple
- Department of Medicine, University of Wisconsin, Madison, Madison, Wisconsin
- Corresponding author: Michelle E. Kimple, , or Alan D. Attie,
| | - Mark P. Keller
- Department of Biochemistry, University of Wisconsin, Madison, Madison, Wisconsin
| | - Mary R. Rabaglia
- Department of Biochemistry, University of Wisconsin, Madison, Madison, Wisconsin
| | - Renee L. Pasker
- Department of Medicine, University of Wisconsin, Madison, Madison, Wisconsin
| | - Joshua C. Neuman
- Department of Nutritional Sciences, University of Wisconsin, Madison, Madison, Wisconsin
| | - Nathan A. Truchan
- Department of Medicine, University of Wisconsin, Madison, Madison, Wisconsin
| | - Harpreet K. Brar
- Department of Medicine, University of Wisconsin, Madison, Madison, Wisconsin
| | - Alan D. Attie
- Department of Biochemistry, University of Wisconsin, Madison, Madison, Wisconsin
- Corresponding author: Michelle E. Kimple, , or Alan D. Attie,
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Straub SG, Sharp GWG. Evolving insights regarding mechanisms for the inhibition of insulin release by norepinephrine and heterotrimeric G proteins. Am J Physiol Cell Physiol 2012; 302:C1687-98. [PMID: 22492651 DOI: 10.1152/ajpcell.00282.2011] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Norepinephrine has for many years been known to have three major effects on the pancreatic β-cell which lead to the inhibition of insulin release. These are activation of K(+) channels to hyperpolarize the cell and prevent the gating of voltage-dependent Ca(2+) channels that increase intracellular Ca(2+) concentration ([Ca(2+)](i)) and trigger release; inhibition of adenylyl cyclases, thus preventing the augmentation of stimulated insulin release by cyclic AMP; and a "distal" effect that occurs downstream of increased [Ca(2+)](i) to inhibit exocytosis. All three are mediated by the pertussis toxin (PTX)-sensitive heterotrimeric Gi and Go proteins. The distal inhibitory effect on exocytosis is now known to be due to the binding of G protein βγ subunits to the synaptosomal-associated protein of 25 kDa (SNAP-25) on the soluble NSF attachment protein receptor (SNARE) complex. Recent studies have uncovered two more actions of norepinephrine on the β-cell: 1) retardation of the refilling of the readily releasable granule pool after it has been discharged, an action that is mediated by Gαi(1) and/or Gαi(2); and 2) inhibition of endocytosis that is mediated by Gz. Of importance also are new findings that Gαo regulates the number of docked granules in the β-cell, and that Gαo(2) maintains a tonic inhibitory influence on secretion. The latter provides another explanation as to why PTX, which blocks the effect of Gαo(2), was initially called "islet activating protein." Finally, there is clear evidence that overexpression of α(2A)-adrenergic receptors in β-cells can cause type 2 diabetes.
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Affiliation(s)
- Susanne G Straub
- Department of Molecular Medicine, Cornell University, Ithaca, New York 14853-6401, USA
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29
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Kimple ME, Moss JB, Brar HK, Rosa TC, Truchan NA, Pasker RL, Newgard CB, Casey PJ. Deletion of GαZ protein protects against diet-induced glucose intolerance via expansion of β-cell mass. J Biol Chem 2012; 287:20344-55. [PMID: 22457354 DOI: 10.1074/jbc.m112.359745] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Insufficient plasma insulin levels caused by deficits in both pancreatic β-cell function and mass contribute to the pathogenesis of type 2 diabetes. This loss of insulin-producing capacity is termed β-cell decompensation. Our work is focused on defining the role(s) of guanine nucleotide-binding protein (G protein) signaling pathways in regulating β-cell decompensation. We have previously demonstrated that the α-subunit of the heterotrimeric G(z) protein, Gα(z), impairs insulin secretion by suppressing production of cAMP. Pancreatic islets from Gα(z)-null mice also exhibit constitutively increased cAMP production and augmented glucose-stimulated insulin secretion, suggesting that Gα(z) is a tonic inhibitor of adenylate cyclase, the enzyme responsible for the conversion of ATP to cAMP. In the present study, we show that mice genetically deficient for Gα(z) are protected from developing glucose intolerance when fed a high fat (45 kcal%) diet. In these mice, a robust increase in β-cell proliferation is correlated with significantly increased β-cell mass. Further, an endogenous Gα(z) signaling pathway, through circulating prostaglandin E activating the EP3 isoform of the E prostanoid receptor, appears to be up-regulated in insulin-resistant, glucose-intolerant mice. These results, along with those of our previous work, link signaling through Gα(z) to both major aspects of β-cell decompensation: insufficient β-cell function and mass.
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Affiliation(s)
- Michelle E Kimple
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705, USA.
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30
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Lin YR, Kim K, Yang Y, Ivessa A, Sadoshima J, Park Y. Regulation of longevity by regulator of G-protein signaling protein, Loco. Aging Cell 2011; 10:438-47. [PMID: 21255223 DOI: 10.1111/j.1474-9726.2011.00678.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Regulator of G-protein signaling (RGS) proteins contribute to G-protein signaling pathways as activators or repressors with GTPase-activating protein (GAP) activity. To characterize whether regulation of RGS proteins influences longevity in several species, we measured stress responses and lifespan of RGS-overexpressing and RGS-lacking mutants. Reduced expression of Loco, a RGS protein of Drosophila melanogaster, resulted in a longer lifespan for both male and female flies, also exhibiting stronger resistance to three different stressors (starvation, oxidation, and heat) and higher manganese-containing superoxide dismutase (MnSOD) activity. In addition, this reduction in Loco expression increased fat content and diminished cAMP levels. In contrast, overexpression of both genomic and cDNA loco gene significantly shortened the lifespan with weaker stress resistance and lower fat content. Deletion analysis of the Loco demonstrated that its RGS domain is required for the regulation of longevity. Consistently, when expression of RGS14, mammalian homologue of Loco, was reduced in rat fibroblast cells, the resistance to oxidative stress increased with higher MnSOD expression. The changes of yeast Rgs2 expression, which shares a conserved RGS domain with the fly Loco protein, also altered lifespan and stress resistance in Saccharomyces cerevisiae. Here, we provide the first evidence that RGS proteins with GAP activity affect both stress resistance and longevity in several species.
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Affiliation(s)
- Yuh-Ru Lin
- Department of Cell Biology and Molecular Medicine, UMDNJ-New Jersey Medical School, Newark, 07101, USA
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31
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Augmented glucose-induced insulin release in mice lacking G(o2), but not G(o1) or G(i) proteins. Proc Natl Acad Sci U S A 2011; 108:1693-8. [PMID: 21220323 DOI: 10.1073/pnas.1018903108] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Insulin secretion by pancreatic β cells is a complex and highly regulated process. Disruption of this process can lead to diabetes mellitus. One of the various pathways involved in the regulation of insulin secretion is the activation of heterotrimeric G proteins. Bordetella pertussis toxin (PTX) promotes insulin secretion, suggesting the involvement of one or more of three G(i) and/or two G(o) proteins as suppressors of insulin secretion from β cells. However, neither the mechanism of this inhibitory modulation of insulin secretion nor the identity of the G(i/o) proteins involved has been elucidated. Here we show that one of the two splice variants of G(o), G(o2), is a key player in the control of glucose-induced insulin secretion by β cells. Mice lacking G(o2)α, but not those lacking α subunits of either G(o1) or any G(i) proteins, handle glucose loads more efficiently than wild-type (WT) mice, and do so by increased glucose-induced insulin secretion. We thus provide unique genetic evidence that the G(o2) protein is a transducer in an inhibitory pathway that prevents damaging oversecretion of insulin.
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32
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Zhao Y, Fang Q, Straub SG, Lindau M, Sharp GWG. Hormonal inhibition of endocytosis: novel roles for noradrenaline and G protein G(z). J Physiol 2010; 588:3499-509. [PMID: 20643775 DOI: 10.1113/jphysiol.2010.190116] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The modulation of endocytosis following exocytosis by noradrenaline (NA), a physiological inhibitor of insulin secretion, was investigated in INS 832/13 cells using patch-clamp capacitance measurements. Endocytosis was inhibited by NA in a pertussis toxin-insensitive manner. Dialysing a synthetic peptide mimicking the C-terminus of the α-subunit of G(z) into the cells blocked the inhibition of endocytosis by NA. Cell-attached capacitance measurements indicated that inhibition by NA was due to a decreased number of endocytotic events without a change in vesicle size. Analysis of fission pore closure kinetics revealed two distinct fission modes, with NA selectively inhibiting the rapid fission pore closure events. Comparison of the actions of NA and deltamethrin, a calcineurin antagonist and potent inhibitor of endocytosis, demonstrated that they inhibit endocytosis by different mechanisms. These findings establish novel actions for NA and G(z) in insulin-secreting cells and possibly other cell types.
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Affiliation(s)
- Ying Zhao
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853-6401, USA
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33
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Zhao Y, Fang Q, Straub SG, Lindau M, Sharp GWG. Noradrenaline inhibits exocytosis via the G protein βγ subunit and refilling of the readily releasable granule pool via the α(i1/2) subunit. J Physiol 2010; 588:3485-98. [PMID: 20643776 DOI: 10.1113/jphysiol.2010.190090] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The molecular mechanisms responsible for the 'distal' effect by which noradrenaline (NA) blocks exocytosis in the β-cell were examined by whole-cell and cell-attached patch clamp capacitance measurements in INS 832/13 β-cells. NA inhibited Ca(2+)-evoked exocytosis by reducing the number of exocytotic events, without modifying vesicle size. Fusion pore properties also were unaffected. NA-induced inhibition of exocytosis was abolished by a high level of Ca(2+) influx, by intracellular application of antibodies against the G protein subunit Gβ and was mimicked by the myristoylated βγ-binding/activating peptide mSIRK. NA-induced inhibition was also abolished by treatment with BoNT/A, which cleaves the C-terminal nine amino acids of SNAP-25, and also by a SNAP-25 C-terminal-blocking peptide containing the BoNT/A cleavage site. These data indicate that inhibition of exocytosis by NA is downstream of increased [Ca(2+)](i) and is mediated by an interaction between Gβγ and the C-terminus of SNAP-25, as is the case for inhibition of neurotransmitter release. Remarkably, in the course of this work, a novel effect of NA was discovered. NA induced a marked retardation of the rate of refilling of the readily releasable pool (RRP) of secretory granules. This retardation was specifically abolished by a Gα(i1/2) blocking peptide demonstrating that the effect is mediated via activation of Gα(i1) and/or Gα(i2).
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Affiliation(s)
- Ying Zhao
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853-6401, USA
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34
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Ernst SJ, Aguilar-Bryan L, Noebels JL. Sodium channel beta1 regulatory subunit deficiency reduces pancreatic islet glucose-stimulated insulin and glucagon secretion. Endocrinology 2009; 150:1132-9. [PMID: 18988673 PMCID: PMC2654754 DOI: 10.1210/en.2008-0991] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Glucose-stimulated insulin and glucagon release regulates glucose homeostasis by an excitation-secretion coupling pathway beginning with ATP-sensitive K(+) channel closure, membrane depolarization, and entry of calcium ions to stimulate exocytosis. The contribution of voltage-gated sodium channels to this release pathway is still being elucidated. We demonstrate that loss of Scn1b, a major regulatory subunit expressed with Na(v)1.7 protein in mouse pancreatic islets, reduces glucose-stimulated insulin and glucagon secretion in vitro and in vivo, resulting in severe fed and fasting hypoglycemia. This genetic mouse model is the first to demonstrate that sodium channelopathy impairs the physiological excitation-release coupling pathway for pancreatic insulin and glucagon release.
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Affiliation(s)
- Sara J Ernst
- Departments of Molecular and Human Genetics, Developmental Neurogenetics Laboratory, Baylor College of Medicine, Houston, Texas 77030, USA
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35
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Mohammed JS, Wang Y, Harvat TA, Oberholzer J, Eddington DT. Microfluidic device for multimodal characterization of pancreatic islets. LAB ON A CHIP 2009; 9:97-106. [PMID: 19209341 PMCID: PMC3759253 DOI: 10.1039/b809590f] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
A microfluidic device to perfuse pancreatic islets while simultaneously characterizing their functionality through fluorescence imaging of the mitochondrial membrane potential and intracellular calcium ([Ca(2+)](i)) in addition to enzyme linked immunosorbent assay (ELISA) quantification of secreted insulin was developed and characterized. This multimodal characterization of islet function will facilitate rapid assessment of tissue quality immediately following isolation from donor pancreas and allow more informed transplantation decisions to be made which may improve transplantation outcomes. The microfluidic perfusion chamber allows flow rates of up to 1 mL min(-1), without any noticeable perturbation or shear of islets. This multimodal quantification was done on both mouse and human islets. The ability of this simple microfluidic device to detect subtle variations in islet responses in different functional assays performed in short time-periods demonstrates that the microfluidic perfusion chamber device can be used as a new gold standard to perform comprehensive islet analysis and obtain a more meaningful predictive value for islet functionality prior to transplantation into recipients, which is currently difficult to predict using a single functional assay.
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