Format

Send to

Choose Destination
Diabetologia. 2012 Oct;55(10):2682-2692. doi: 10.1007/s00125-012-2650-x. Epub 2012 Jul 22.

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

Author information

1
Montreal Diabetes Research Center, CRCHUM, Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada, H1W 4A4.
2
Department of Medicine, University of Montreal, Montreal, QC, Canada.
3
Department of Pharmacology and the Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada.
4
Garvan Institute of Medical Research, St Vincent's Hospital, Darlinghurst, Sydney, NSW, Australia.
5
Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany.
6
Medical Department, Division of Cardiology, Charité University, Campus Virchow-Klinikum, Berlin, Germany.
7
Departments of Molecular Biology, Internal Medicine, and Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
8
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, QC, Canada.
9
Montreal Diabetes Research Center, CRCHUM, Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada, H1W 4A4. Vincent.poitout@umontreal.ca.
10
Department of Medicine, University of Montreal, Montreal, QC, Canada. Vincent.poitout@umontreal.ca.
11
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, QC, Canada. Vincent.poitout@umontreal.ca.

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.

PMID:
22820510
PMCID:
PMC3543464
DOI:
10.1007/s00125-012-2650-x
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Springer Icon for PubMed Central
Loading ...
Support Center