The cytoprotective effects of oleoylethanolamide in insulin-secreting cells do not require activation of GPR119.
OBJECTIVE
β-cells express a range of fatty acid-responsive G protein-coupled receptors, including GPR119, which regulates insulin secretion and is seen as a potential therapeutic target in type 2 diabetes. The long-chain unsaturated fatty acid derivative oleoylethanolamide (OEA) is an endogenous agonist of GPR119 and, under certain conditions, some long-chain unsaturated fatty acids can promote β-cell cytoprotection. It is not known, however, if OEA is cytoprotective in β-cells. The present study has examined this and determined whether GPR119 is involved.


METHODS
Clonal rat insulin-secreting cell lines, BRIN-BD11 or INS-1E, were exposed to fatty acids complexed with BSA. cAMP levels, insulin release and cell viability were measured. Protein expression was studied by Western blotting and receptor expression by RT-PCR.


RESULTS
GPR119 was expressed in both BRIN-BD11 and INS-1E cells and OEA was cytoprotective in these cells. However, cytoprotection was not reproduced by any of a range of selective, synthetic ligands of GPR119. The cytoprotective response to OEA was lost during exposure to inhibitors of fatty acid amide hydrolase (FAAH) suggesting that OEA per se is not the cytoprotective species but that release of free oleate is required. Similar data were obtained with anandamide, which was cytoprotective only under conditions favouring release of free arachidonate.


CONCLUSIONS
Activation of GPR119 is not required to mediate the cytoprotective actions of OEA in BRIN-BD11 or INS-1E cells. Rather, OEA is internalised and subjected to hydrolysis by FAAH to release free oleate, which then mediates the cytoprotection.
Institute of Biomedical & Clinical Sciences, Peninsula Medical School, University of Exeter, Plymouth, Devon, UK.
Virginia M
VM
Stone
Shalinee
S
Dhayal
David M
DM
Smith
Carol
C
Lenaghan
Katy J
KJ
Brocklehurst
Noel G
NG
Morgan
D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D019610:Cytoprotection / Q000187:drug effects*; D063388:Endocannabinoids; D005227:Fatty Acids / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects* / Q000378:metabolism; D009829:Oleic Acids / Q000494:pharmacology*; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000494:pharmacology
D063388:Endocannabinoids; D005227:Fatty Acids; C532423:GPR119 protein, rat; D007328:Insulin; D009829:Oleic Acids; D043562:Receptors, G-Protein-Coupled; C488250:oleoylethanolamide; D012710:Serum Albumin, Bovine; D000242:Cyclic AMP