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Alquier T, Peyot ML, Latour MG, Kebede M, Sorensen CM, Gesta S, Ronald Kahn C, Smith RD, Jetton TL, Metz TO, Prentki M, Poitout V. Deletion of GPR40 impairs glucose-induced insulin secretion in vivo in mice without affecting intracellular fuel metabolism in islets. Diabetes 2009; 58:2607-15. [PMID: 19720802 PMCID: PMC2768167 DOI: 10.2337/db09-0362] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE The G-protein-coupled receptor GPR40 mediates fatty acid potentiation of glucose-stimulated insulin secretion, but its contribution to insulin secretion in vivo and mechanisms of action remain uncertain. This study was aimed to ascertain whether GPR40 controls insulin secretion in vivo and modulates intracellular fuel metabolism in islets. RESEARCH DESIGN AND METHODS Insulin secretion and sensitivity were assessed in GPR40 knockout mice and their wild-type littermates by hyperglycemic clamps and hyperinsulinemic euglycemic clamps, respectively. Transcriptomic analysis, metabolic studies, and lipid profiling were used to ascertain whether GPR40 modulates intracellular fuel metabolism in islets. RESULTS Both glucose- and arginine-stimulated insulin secretion in vivo were decreased by approximately 60% in GPR40 knockout fasted and fed mice, without changes in insulin sensitivity. Neither gene expression profiles nor intracellular metabolism of glucose and palmitate in isolated islets were affected by GPR40 deletion. Lipid profiling of isolated islets revealed that the increase in triglyceride and decrease in lyso-phosphatidylethanolamine species in response to palmitate in vitro was similar in wild-type and knockout islets. In contrast, the increase in intracellular inositol phosphate levels observed in wild-type islets in response to fatty acids in vitro was absent in knockout islets. CONCLUSIONS These results indicate that deletion of GPR40 impairs insulin secretion in vivo not only in response to fatty acids but also to glucose and arginine, without altering intracellular fuel metabolism in islets, via a mechanism that may involve the generation of inositol phosphates downstream of GPR40 activation.
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Affiliation(s)
- Thierry Alquier
- Montréal Diabetes Research Center, Research Centre of the Montréal University Hospital, University of Montréal, Montréal, QC, Canada
- Department of Medicine, University of Montréal, Montréal, QC, Canada
| | - Marie-Line Peyot
- Montréal Diabetes Research Center, Research Centre of the Montréal University Hospital, University of Montréal, Montréal, QC, Canada
| | - Martin G. Latour
- Montréal Diabetes Research Center, Research Centre of the Montréal University Hospital, University of Montréal, Montréal, QC, Canada
| | - Melkam Kebede
- Montréal Diabetes Research Center, Research Centre of the Montréal University Hospital, University of Montréal, Montréal, QC, Canada
- Department of Medicine, University of Montréal, Montréal, QC, Canada
| | - Christina M. Sorensen
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington
| | - Stephane Gesta
- Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
| | - C. Ronald Kahn
- Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
| | - Richard D. Smith
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington
| | - Thomas L. Jetton
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont College of Medicine, Burlington, Vermont
| | - Thomas O. Metz
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington
| | - Marc Prentki
- Montréal Diabetes Research Center, Research Centre of the Montréal University Hospital, University of Montréal, Montréal, QC, Canada
- Department of Nutrition, University of Montréal, Montréal, QC, Canada
| | - Vincent Poitout
- Montréal Diabetes Research Center, Research Centre of the Montréal University Hospital, University of Montréal, Montréal, QC, Canada
- Department of Medicine, University of Montréal, Montréal, QC, Canada
- Corresponding author: Vincent Poitout,
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252
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Liaw CW, Connolly DT. Sequence Polymorphisms Provide a Common Consensus Sequence for GPR41 and GPR42. DNA Cell Biol 2009; 28:555-60. [DOI: 10.1089/dna.2009.0916] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- Chen W. Liaw
- Arena Pharmaceuticals, Inc., San Diego, California
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254
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Morgan NG, Dhayal S. G-protein coupled receptors mediating long chain fatty acid signalling in the pancreatic beta-cell. Biochem Pharmacol 2009; 78:1419-27. [PMID: 19660440 DOI: 10.1016/j.bcp.2009.07.020] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/27/2009] [Accepted: 07/27/2009] [Indexed: 11/16/2022]
Abstract
It is increasingly clear that some of the effects of both free and derivatised long chain fatty acids in pancreatic beta-cells are mediated by a group of G-protein coupled receptors. Some of these display close structural homology while others are more divergent. This Commentary reviews the expression and functional roles of three such molecules, GPR40, GPR119 and GPR120. GPR40 is the best characterised of this group and appears to mediate the acute stimulatory effects of long chain fatty acids on insulin secretion. GPR40 has also been proposed as a potential mediator of fatty acid toxicity but this is more controversial. GPR119 is also involved in stimulation of insulin secretion and responds primarily to ethanolamide derivatives of long chain fatty acids and also to some lysophospholipids rather than to free fatty acids. It may represent a useful target for the development of new insulin secretagogues aimed to enhance insulin release in patients with type 2 diabetes. GPR120 is the most enigmatic of the lipid-responsive cell-surface receptors and its function remains to be established. It has been proposed to play a cytoprotective role in certain other cell types but it is unclear whether it fulfils a similar function in beta-cells.
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Affiliation(s)
- Noel G Morgan
- Institute of Biomedical & Clinical Science, John Bull Building, Peninsula Medical School, Plymouth PL6 8BU, UK.
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255
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Wellendorph P, Johansen LD, Bräuner-Osborne H. Molecular pharmacology of promiscuous seven transmembrane receptors sensing organic nutrients. Mol Pharmacol 2009; 76:453-65. [PMID: 19487246 DOI: 10.1124/mol.109.055244] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A number of highly promiscuous seven transmembrane (7TM) receptors have been cloned and characterized within the last few years. It is noteworthy that many of these receptors are activated broadly by amino acids, proteolytic degradation products, carbohydrates, or free fatty acids and are expressed in taste tissue, the gastrointestinal tract, endocrine glands, adipose tissue, and/or kidney. These receptors thus hold the potential to act as sensors of food intake, regulating, for example, release of incretin hormones from the gut, insulin/glucagon from the pancreas, and leptin from adipose tissue. The promiscuous tendency in ligand recognition of these receptors is in contrast to the typical specific interaction with one physiological agonist seen for most receptors, which challenges the classic "lock-and-key" concept. We here review the molecular mechanisms of nutrient sensing of the calcium-sensing receptor, the G protein-coupled receptor family C, group 6, subtype A (GPRC6A), and the taste1 receptor T1R1/T1R3, which are sensing L-alpha-amino acids, the carbohydrate-sensing T1R2/T1R3 receptor, the proteolytic degradation product sensor GPR93 (also termed GPR92), and the free fatty acid (FFA) sensing receptors FFA1, FFA2, FFA3, GPR84, and GPR120. The involvement of the individual receptors in sensing of food intake has been validated to different degrees because of limited availability of specific pharmacological tools and/or receptor knockout mice. However, as a group, the receptors represent potential drug targets, to treat, for example, type II diabetes by mimicking food intake by potent agonists or positive allosteric modulators. The ligand-receptor interactions of the promiscuous receptors of organic nutrients thus remain an interesting subject of emerging functional importance.
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Affiliation(s)
- Petrine Wellendorph
- UNIK centre for life-style diseases, Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
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256
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Smith NJ, Stoddart LA, Devine NM, Jenkins L, Milligan G. The action and mode of binding of thiazolidinedione ligands at free fatty acid receptor 1. J Biol Chem 2009; 284:17527-39. [PMID: 19398560 DOI: 10.1074/jbc.m109.012849] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The endogenous ligands for free fatty acid receptor 1 (FFA1) are medium and longer chain free fatty acids. However, a range of selective, small molecule ligands have recently been developed as tool compounds to explore the therapeutic potential of this receptor, whereas clinically employed thiazolidinedione "glitazone" drugs are also agonists at FFA1. Each of these classes of agonist was able to promote phosphorylation of the ERK1/2 mitogen-activated protein (MAP) kinases in cells able to express human FFA1 on demand. However, although both lauric acid and the synthetic agonist GW9508X produced rapid and transient ERK1/2 MAP kinase phosphorylation, the thiazolidinedione rosiglitazone produced responses that were sustained for a substantially longer period. Despite this difference, the effects of each ligand required FFA1 and were transduced in each case predominantly via G proteins of the Galphaq/Galpha11 family. Different glitazone drugs also displayed markedly different efficacy and kinetics of sustainability of ERK1/2 MAP kinase phosphorylation. A number of orthosteric binding site mutants of FFA1 were generated, and despite variations in the changes of potency and efficacy of the three ligand classes in different functional end point assays, these were consistent with rosiglitazone also binding at the orthosteric site. Four distinct polymorphic variants of human FFA1 have been described. Despite previous indications that these display differences in function and pharmacology, they all responded in entirely equivalent ways to lauric acid, rosiglitazone, and GW9508X in measures of ERK1/2 MAP kinase phosphorylation, enhancement of binding of [35S]GTPgammaS (guanosine 5'-O-(3-[35S]thio)triphosphate) to Galphaq, and elevation of intracellular [Ca2+], suggesting that individuals expressing each variant are likely to respond equivalently to orthosteric agonists of FFA1.
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Affiliation(s)
- Nicola J Smith
- Molecular Pharmacology Group, Neuroscience and Molecular Pharmacology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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