Research article

Cloning and expression of the rabbit prostaglandin EP2 receptor

Youfei Guan¹ , Brett A Stillman² , Yahua Zhang¹ , André Schneider¹ , Osamu Saito¹ , Linda S Davis¹ , Reyadh Redha¹ , Richard M Breyer^1,2 and Matthew D Breyer^1,3

¹Division of Nephrolgy, Veterans Administration Medical Center, and Vanderbilt University School of Medicine, Nashville, Tennessee, USA37232-2372, USA

²Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA37232-2372, USA

³Department of Molecular Physiology and Biophysics, Veterans Administration Medical Center, and Vanderbilt University School of Medicine, Nashville, Tennessee, USA37232-2372, USA

author email corresponding author email

BMC Pharmacology 2002, 2:14doi:10.1186/1471-2210-2-14

Published:	27 June 2002

Abstract

Background

Prostaglandin E₂ (PGE₂) has multiple physiologic roles mediated by G protein coupled receptors designated E-prostanoid, or "EP" receptors. Evidence supports an important role for the EP₂ receptor in regulating fertility, vascular tone and renal function.

Results

The full-length rabbit EP₂ receptor cDNA was cloned. The encoded polypeptide contains 361 amino acid residues with seven hydrophobic domains. COS-1 cells expressing the cloned rabbit EP₂ exhibited specific [³H]PGE₂ binding with a K_d of 19.1± 1.7 nM. [³H]PGE₂ was displaced by unlabeled ligands in the following order: PGE₂>>PGD₂=PGF_2α=iloprost. Binding of [³H]PGE₂ 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 EP₂ 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 EP₂ 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 PGE₂ effects in reproductive and vascular tissues and renal interstitial cells. It remains uncertain whether it is also expressed in renal tubules.