title: G protein-coupled receptor (GPR)40-dependent potentiation of insulin secretion in mouse islets is mediated by protein kinase D1.
abstract: Activation of the G protein-coupled receptor (GPR)40 by long-chain fatty acids potentiates glucose-stimulated insulin secretion (GSIS) from pancreatic beta cells, and GPR40 agonists are in clinical development for type 2 diabetes therapy. GPR40 couples to the G protein subunit Gα(q/11) but the signalling cascade activated downstream is unknown. This study aimed to determine the mechanisms of GPR40-dependent potentiation of GSIS by fatty acids.
  
  
  
  Insulin secretion in response to glucose, oleate or diacylglycerol (DAG) was assessed in dynamic perifusions and static incubations in islets from wild-type (WT) and Gpr40                            (-/-) mice. Depolymerisation of filamentous actin (F-actin) was visualised by phalloidin staining and epifluorescence. Pharmacological and molecular approaches were used to ascertain the roles of protein kinase D (PKD) and protein kinase C delta in GPR40-mediated potentiation of GSIS.
  
  
  
  Oleate potentiates the second phase of GSIS, and this effect is largely dependent upon GPR40. Accordingly, oleate induces rapid F-actin remodelling in WT but not in Gpr40                            (-/-) islets. Exogenous DAG potentiates GSIS in both WT and Gpr40                            (-/-) islets. Oleate induces PKD phosphorylation at residues Ser-744/748 and Ser-916 in WT but not Gpr40                            (-/-) islets. Importantly, oleate-induced F-actin depolymerisation and potentiation of GSIS are lost upon pharmacological inhibition of PKD1 or deletion of Prkd1.
  
  
  
  We conclude that the signalling cascade downstream of GPR40 activation by fatty acids involves activation of PKD1, F-actin depolymerisation and potentiation of second-phase insulin secretion. These results provide important information on the mechanisms of action of GPR40, a novel drug target for type 2 diabetes.
authors: Montreal Diabetes Research Center, CRCHUM, Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada, H1W 4A4.|Department of Medicine, University of Montreal, Montreal, QC, Canada.
authors: M
authors: M
authors: Ferdaoussi
authors: Montreal Diabetes Research Center, CRCHUM, Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada, H1W 4A4.|Department of Medicine, University of Montreal, Montreal, QC, Canada.
authors: V
authors: V
authors: Bergeron
authors: Montreal Diabetes Research Center, CRCHUM, Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada, H1W 4A4.|Department of Medicine, University of Montreal, Montreal, QC, Canada.
authors: B
authors: B
authors: Zarrouki
authors: Department of Pharmacology and the Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada.
authors: J
authors: J
authors: Kolic
authors: Garvan Institute of Medical Research, St Vincent's Hospital, Darlinghurst, Sydney, NSW, Australia.
authors: J
authors: J
authors: Cantley
authors: Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany.|Medical Department, Division of Cardiology, Charité University, Campus Virchow-Klinikum, Berlin, Germany.
authors: J
authors: J
authors: Fielitz
authors: Departments of Molecular Biology, Internal Medicine, and Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors: E N
authors: EN
authors: Olson
authors: Montreal Diabetes Research Center, CRCHUM, Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada, H1W 4A4.|Departments of Nutrition and Biochemistry, University of Montreal, Montreal, QC, Canada.
authors: M
authors: M
authors: Prentki
authors: Garvan Institute of Medical Research, St Vincent's Hospital, Darlinghurst, Sydney, NSW, Australia.
authors: T
authors: T
authors: Biden
authors: Department of Pharmacology and the Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada.
authors: P E
authors: PE
authors: MacDonald
authors: Montreal Diabetes Research Center, CRCHUM, Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada, H1W 4A4. Vincent.poitout@umontreal.ca.|Department of Medicine, University of Montreal, Montreal, QC, Canada. Vincent.poitout@umontreal.ca.|Departments of Nutrition and Biochemistry, University of Montreal, Montreal, QC, Canada. Vincent.poitout@umontreal.ca.
authors: V
authors: V
authors: Poitout
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D004075:Diglycerides / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D019301:Oleic Acid / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology*; D051745:Protein Kinase C-delta / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D000199:Actins; D004075:Diglycerides; C473036:Ffar1 protein, mouse; D007328:Insulin; D043562:Receptors, G-Protein-Coupled; D019301:Oleic Acid; C089212:protein kinase D; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D005947:Glucose