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

Abstract：

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 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. 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.

journal_name

Diabetologia

journal_title

Diabetologia

authors

Ferdaoussi M,Bergeron V,Zarrouki B,Kolic J,Cantley J,Fielitz J,Olson EN,Prentki M,Biden T,MacDonald PE,Poitout V

doi

10.1007/s00125-012-2650-x

subject

Has Abstract

pub_date

2012-10-01 00:00:00

pages

2682-2692

issue

eissn

0012-186X

issn

1432-0428

pii

10.1007/s00125-012-2650-x

journal_volume

pub_type

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