GPR40 is a low-affinity epoxyeicosatrienoic acid receptor in vascular cells

Abstract

Endothelium-derived epoxyeicosatrienoic acids (EETs) have numerous vascular activities mediated by G protein-coupled receptors. Long-chain free fatty acids and EETs activate GPR40, prompting us to investigate the role of GPR40 in some vascular EET activities. 14,15-EET, 11,12-EET, arachidonic acid, and the GPR40 agonist GW9508 increase intracellular calcium concentrations in human GPR40-overexpressing HEK293 cells (EC 50 = 0.58 ± 0.08 µM, 0.91 ± 0.08 µM, 3.9 ± 0.06 µM and 19 ± 0.37 nM, respectively). EETs with cisand trans-epoxides had similar activities, whereas substitution of a thiirane sulfur for the epoxide oxygen decreased the activities. 8,9-EET, 5,6-EET, and the epoxide hydrolysis products 11,12-and 14,15-vicdihydroxyeicosatrienoic acids were less active than 11,12-EET. The GPR40 antagonist GW1100 and siRNA-mediated GPR40 silencing blocked the EET-and GW9508-induced calcium increases. EETs are weak GPR120 agonists. GPR40 expression was detected in human and bovine endothelial cells (ECs), smooth muscle cells, and arteries. 11,12-EET concentration-dependently relaxed preconstricted coronary arteries; however, these relaxations were not altered by GW1100. In human ECs, 11,12-EET increased MAP kinase-mediated ERK phosphorylation, phosphorylation and levels of connexin-43 (Cx43), and expression of cyclooxygenase-2 (COX-2), all of which were inhibited by GW1100 and the MAP kinase inhibitor U0126. Moreover, siRNA-mediated GPR40 silencing decreased 11,12-EETinduced ERK phosphorylation. These results indicated that GPR40 is a low-affinity EET receptor in vascular cells and arteries. We conclude that epoxidation of arachidonic acid to EETs enhances GPR40 agonist activity and that 11,12-EET stimulation of GPR40 increases Cx43 and COX-2 expression in ECs via ERK phosphorylation. INTRODUCTIONhttp://www.jbc.org/cgi

Specific oxylipins enhance vertebrate hematopoiesis via the receptor GPR132

“…However, we were only able to obtain H 3 -9-HODE with a very low specific activity (0.13 Ci/mMol) after HPLC isolation and purification, which impeded accurate assessments of specific binding. Other proposed EET receptors include TRPV/TRPC receptors (41)(42)(43), peroxisome-proliferatoractivated receptors (44), prostaglandin receptors (20,45), and FFAR1 (38,46). FFAR1 had very low expression in our EaHy samples (average FPKM = 0.14).…”

“…sEH shows a strong substrate preference for 14,15-EET over 11,, whereas cyclooxygenases were recently shown to metabolize 11,12-EET, but not 14,15-EET (36). 14,15-EET is a stronger inhibitor of a calcium-regulated potassium channel than 11,12-EET (37), and a stronger activator of free fatty acid receptor 1 (FFAR1, also called GPR40) (38). 11,12-EET, but not other regioisomers, caused changes in the electrical potential of rat tracheal epithelial cells (39) and enhanced endothelial cell migration and tube formation (11).…”

Thematic Review Series: Living History of Lipids The arachidonic acid monooxygenase: from biochemical curiosity to physiological/pathophysiological significance

“…Recently, GPR75 was proposed as a 20-HETE receptor (51) and GPR40 as a low-affinity EET receptor in vascular cells (94). If confirmed, these reports hold far-reaching significance and might portend a new golden age for the P450 eicosanoid field.…”

“…In contrast, after attempts by different groups, selective binding and trans-membrane signaling has been reported only for 14(R),15(S)-EET in guinea pig mononuclear and human U937 cells (95,96). G proteins, mitogenic kinases/phosphatases, cAMP-kinase A, prostanoids, PPAR nuclear receptors, and direct effects on ion-channel activity have been proposed as mediators of EET signaling (6,8,10,14,94); however, a membrane receptor capable of selective high-affinity EET binding and trans-membrane signaling has yet to be unequivocally identified. Complicating these efforts is the ready migration or transport of exogenously added EETs across cell membranes, as shown by their rapid esterification into cellular glycerolipids (39), raising the possibility that extracellular and/or intracellular events could mediate EET functional effects.…”

Hippocampus has lower oxygenation and weaker control of brain blood flow than cortex, due to microvascular differences

“…In order to test for more general functional differences between vascular cells, we examined the mRNA expression profile of mural and endothelial cells using the same single-cell mRNA dataset as above 11 across three broad categories associated with neurovascular function: contractile machinery, ion (potassium and calcium) channels and neurovascular signalling pathways (Supplementary Tables 4 & 5). The latter category included recently identified EET and 20-HETE receptors 16,17 and, given the recent finding that endothelial NMDA receptors can control vascular tone 18 , NMDA receptor subunits. Several genes showed differential expression between V1 and HC, all of which pointed to the vasculature in V1 being more contractile or responsive than in HC ( Supplementary Figure 3; Supplementary Tables 4 & 5).…”