Prostaglandin E2 glyceryl ester is an endogenous agonist of the nucleotide receptor P2Y6

Abstract

Cyclooxygenase-2 catalyses the biosynthesis of prostaglandins from arachidonic acid but also the biosynthesis of prostaglandin glycerol esters (PG-Gs) from 2-arachidonoylglycerol. Previous studies identified PG-Gs as signalling molecules involved in inflammation. Thus, the glyceryl ester of prostaglandin E2, PGE2-G, mobilizes Ca2+ and activates protein kinase C and ERK, suggesting the involvement of a G protein-coupled receptor (GPCR). To identify the endogenous receptor for PGE2-G, we performed a subtractive screening approach where mRNA from PGE2-G response-positive and -negative cell lines was subjected to transcriptome-wide RNA sequencing analysis. We found several GPCRs that are only expressed in the PGE2-G responder cell lines. Using a set of functional readouts in heterologous and endogenous expression systems, we identified the UDP receptor P2Y6 as the specific target of PGE2-G. We show that PGE2-G and UDP are both agonists at P2Y6, but they activate the receptor with extremely different EC50 values of ~1 pM and ~50 nM, respectively. The identification of the PGE2-G/P2Y6 pair uncovers the signalling mode of PG-Gs as previously under-appreciated products of cyclooxygenase-2.

P2Y1‐like nucleotide receptors—Structures, molecular modeling, mutagenesis, and oligomerization

“…An updated P2Y 6 R model based on the X‐ray crystal structure of P2Y 1 R and P2Y 12 R, as well as several supplementary templates, was recently used to predict the binding sites of UDP and prostaglandin E2 glyceryl ester (PGE 2 ‐G, 1.13 ) . The docking studies suggested a binding pocket for UDP between TMIII, VI and VII, similar to those predicted for the P2Y 1 R and P2Y 2 R. The uridine moiety was oriented toward TMIII.…”

“…Brüser et al performed mutagenesis and molecular modeling studies to delineate the binding modes of the glyceryl ester of prostaglandin E2 (PGE 2 ‐G, 1.13 ) and UDP, after identification of PGE 2 ‐G as a potent endogenous agonist of the human P2Y 6 R (EC 50 ≈ 1 pM) . Four residues were mutated to alanine: Tyr75, Phe252, Tyr262, and Arg287.…”

Update of P2Y receptor pharmacology: IUPHAR Review 27

“…Currently, there is no crystal structure for pyrimidine nucleotide receptors. However, recent mutational and docking studies suggest that the conserved R 7.39 in P2Y 1 ‐like receptors is also involved in UDP binding in P2Y 6 receptors (Bruser et al, 2017) and agonist binding of P2Y 2 receptors (Rafehi, Neumann, et al, 2017) indicating that the binding pocked is very similar at least within the two P2Y receptor groups.…”

Human leukocytes differentially express endocannabinoid-glycerol lipases and hydrolyze 2-arachidonoyl-glycerol and its metabolites from the 15-lipoxygenase and cyclooxygenase pathways

“…Aside from its hydrolysis into AA, 2‐AG can be metabolized by eicosanoid biosynthetic enzymes from the cyclooxygenase (COX)‐2 and 15‐lipoxygenase (15‐LO) pathways, leading to eicosanoid‐glycerols (G), such as PG‐Gs or 15‐hydroxy‐eicosatetraenoyl‐glycerol (15‐HETE‐G) . In this regard, 15‐HETE‐G, PGD 2 ‐G, and PGE 2 ‐G activate cell surface or nuclear receptors . Noteworthy, some of these metabolites exert anti‐inflammatory effects, although additional investigations are required to completely understand their biologic effects in health and disease.…”