CLONING AND EXPRESSION OF THE RABBIT PROSTAGLANDIN EP(4) RECEPTOR

Prostaglandin E(2) (PGE(2)) is an important regulator of systemic hemo dynamics and epithelial ion transport. To further investigate the mech anism of PGE(2) action, a clone encoding a PGE(2) receptor was isolate d from a rabbit kidney cortex cDNA library. Expression of the full-len gth cDNA in COS-1 cells yielded a ligand-binding profile typical for a butaprost-insensitive G(3)-coupled E-prostanoid (EP) receptor. Misopr ostol-free acid, a receptor-selective PGE analogue, produced concentra tion-dependent increases in adenosine 3',5'-cyclic monophosphate produ ction. The data are consistent with the receptor being an EP(4) subtyp e. Ribonuclease protection assays demonstrated that this receptor gene is highly expressed in intestine, uterus, and thymus, with lower but significant expression in kidney, whole adrenal, lung, spleen, and sto mach. In situ hybridization in kidney revealed intense hybridization t o glomeruli and urothelium of the renal pelvis. This prostanoid recept or was also highly expressed in the duodenal epithelium and adrenal co rtex. The tissue distribution suggests a functional role for this rece ptor in mediating glomerular effects of PGE(2) and effects on aldoster one secretion, intestinal transport, and immune function.