Cloning and expression of the rabbit prostaglandin EP2 receptor

BACKGROUND: Prostaglandin E(2) (PGE(2)) has multiple physiologic roles mediated by G protein coupled receptors designated E-prostanoid, or "EP" receptors. Evidence supports an important role for the EP(2) receptor in regulating fertility, vascular tone and renal function. RESULTS: The full-length rabbit EP(2) receptor cDNA was cloned. The encoded polypeptide contains 361 amino acid residues with seven hydrophobic domains. COS-1 cells expressing the cloned rabbit EP(2) exhibited specific [(3)H]PGE(2) binding with a K(d) of 19.1± 1.7 nM. [(3)H]PGE(2) was displaced by unlabeled ligands in the following order: PGE(2)>>PGD(2)=PGF(2α)=iloprost. Binding of [(3)H]PGE(2) was also displaced by EP receptor subtype selective agonists with a rank order of affinity consistent with the EP2 receptor (butaprost>AH13205>misoprostol>sulprostone). Butaprost free acid produced a concentration-dependent increase in cAMP accumulation in rabbit EP(2) transfected COS-1 cells with a half-maximal effective concentration of 480 nM. RNase protection assay revealed high expression in the ileum, spleen, and liver with lower expression in the kidney, lung, heart, uterus, adrenal gland and skeletal muscle. In situ hybridization localized EP(2) mRNA to the uterine endometrium, but showed no distinct localization in the kidney. EP2 mRNA expression along the nephron was determined by RT-PCR and its expression was present in glomeruli, MCD, tDL and CCD. In cultured cells EP2 receptor was not detected in collecting ducts but was detected in renal interstitial cells and vascular smooth muscle cells. EP2 mRNA was also detected in arteries, veins, and preglomerular vessels of the kidney. CONCLUSION: EP2 expression pattern is consistent with the known functional roles for cAMP coupled PGE(2) effects in reproductive and vascular tissues and renal interstitial cells. It remains uncertain whether it is also expressed in renal tubules.