G protein-coupled receptor (GPR)40-dependent potentiation of insulin secretion in mouse islets is mediated by protein kinase D1

TY - JOUR

T1 - G protein-coupled receptor (GPR)40-dependent potentiation of insulin secretion in mouse islets is mediated by protein kinase D1

AU - Ferdaoussi, M.

AU - Bergeron, V.

AU - Zarrouki, B.

AU - Kolic, J.

AU - Cantley, J.

AU - Fielitz, J.

AU - Olson, E. N.

AU - Prentki, M.

AU - Biden, T.

AU - MacDonald, P. E.

AU - Poitout, V.

PY - 2012/10

Y1 - 2012/10

N2 - Aims/hypothesis: 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 Gαq/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. Methods: 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. Results: 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. Conclusions/interpretation: 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.

AB - Aims/hypothesis: 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 Gαq/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. Methods: 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. Results: 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. Conclusions/interpretation: 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.

KW - Diacylglycerol

KW - Filamentous actin

KW - G protein-coupled receptor

KW - GPR40

KW - Insulin secretion

KW - Islet

KW - Protein kinase D

KW - Type 2 diabetes

UR - https://www.scopus.com/pages/publications/84866129127

U2 - 10.1007/s00125-012-2650-x

DO - 10.1007/s00125-012-2650-x

M3 - Article

C2 - 22820510

AN - SCOPUS:84866129127

SN - 0012-186X

VL - 55

SP - 2682

EP - 2692

JO - Diabetologia

JF - Diabetologia

IS - 10

ER -