Free fatty acid receptor 1 (FFA(1)R/GPR40) and its involvement in fatty-acid-stimulated insulin secretion.
Free fatty acids (FFA) have generally been proposed to regulate pancreatic insulin release by an intracellular mechanism involving inhibition of CPT-1. The recently de-orphanized G-protein coupled receptor, FFA(1)R/GPR40, has been shown to be essential for fatty-acid-stimulated insulin release in MIN6 mouse insulinoma cells. The CPT-1 inhibitor, 2-bromo palmitate (2BrP), was investigated for its ability to interact with mouse FFA(1)R/GPR40. It was found to inhibit phosphatidyl inositol hydrolysis induced by linoleic acid (LA) (100 muM in all experiments) in HEK293 cells transfected with FFA(1)R/GPR40 and in the MIN6 subclone, MIN6c4. 2BrP also inhibited LA-stimulated insulin release from mouse pancreatic islets. Mouse islets were subjected to antisense intervention by treatment with a FFA(1)R/GPR40-specific morpholino oligonucleotide for 48 h. Antisense treatment of islets suppressed LA-stimulated insulin release by 50% and by almost 100% when islets were pretreated with LA for 30 min before applying the antisense. Antisense treatment had no effect on tolbutamide-stimulated insulin release. Confocal microscopy using an FFA(1)R/GPR40-specific antibody revealed receptor expression largely localized to the plasma membrane of insulin-producing cells. Pretreating the islets with LA for 30 min followed by antisense oligonucleotide treatment for 48 h reduced the FFA(1)R/GPR40 immunoreactivity to background levels. The results demonstrate that FFA(1)R/GPR40 is inhibited by the CPT-1 inhibitor, 2BrP, and confirm that FFA(1)R/GPR40 is indeed necessary, at least in part, for fatty-acid-stimulated insulin release.
Salehi
A
A
Section of Diabetes and Endocrinology, BMC B11, 22184 Lund, Sweden.
Flodgren
E
E
Nilsson
N E
NE
Jimenez-Feltstrom
J
J
Miyazaki
J
J
Owman
C
C
Olde
B
B
D000818:Animals; D002460:Cell Line; D005227:Fatty Acids / Q000378:metabolism*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism; D019787:Linoleic Acid / Q000378:metabolism; D051379:Mice; D016376:Oligonucleotides, Antisense / Q000378:metabolism; D010168:Palmitates / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*
D005227:Fatty Acids; C473036:Ffar1 protein, mouse; D007004:Hypoglycemic Agents; D007328:Insulin; D016376:Oligonucleotides, Antisense; D010168:Palmitates; D010716:Phosphatidylinositols; D043562:Receptors, G-Protein-Coupled; C022776:2-bromopalmitate; D019787:Linoleic Acid