Cloning and characterization of chicken prostaglandin E receptor subtype 3 (EP3) and F receptor (FP)

Abstract

Belonging to the eicosanoids, prostaglandin E2 (PGE2) and F2α (PGF2α) are important chemical mediators regulating many vital physiological processes, from modulation of neurotransmitter release, sodium and water re-absorption to maintenance of pregnancy. Prostaglandin E receptor subtype 3 (EP3) is believed to mainly mediate a decline in intracellular cyclic AMP (cAMP) level via coupling to Gi protein, while prostaglandin F receptor (FP) is believed to affect an increase in intracellular calcium ion level via Gq protein. Though both receptors were identified in mammals and FP in zebrafish, they have yet to be cloned in any avian species. In the present study, using reverse transcriptionpolymerase chain reaction (RT-PCR), the full-length cDNAs for chicken EP3 and both FP receptor isoforms were cloned from adult chicken ovary. Chicken EP3 is 370 amino acids in length and shows high amino acid identities to that of mammals (human, 57%; mouse, 66%; rat, 68%; dog, 63%; cow, 57%; rabbit, 67%). The full-length cDNAs of FP gene encodes a long and short isoforms of 364 and 258 amino acids, respectively. The long isoform shares a high degree of amino acid identities to that of mammals, including human (80%), mouse (77%), rat (78%), dog (81%), and cow (75%), and a low sequence identity to zebrafish (66%). Both long and short FP isoforms are shown to be expressed in all tissues examined. The tissue distribution profile is underway for EP3. The cloning and characterization of EP3 and FP receptors would help us to establish a molecular basis to elucidate the physiological roles of prostaglandin E2 and F2α in target tissues including their actions in chicken ovary.