Cloning and characterization of the human corticotropin-releasing factor-2 receptor complementary deoxyribonucleic acid

Two CRF receptor subtypes (CRF(1) and CRF(2) receptors) with distinct brain localizations and pharmacological profiles have recently been cloned and characterized. For the CRF(2) receptor subtype, at least 2 splice forms with different 5'-coding sequences (CRF(2 alpha) and CRF(2 beta)) have been identified in rat. In this article, we report the genomic structure and the corresponding complementary DNA (cDNA) sequence of the human CRF(2) receptor. The gene coding for human CRF(2) receptor consists of at least 12 exons and spans approximately 30 kilobases. The cDNA sequence in the protein-coding region is 94% identical to that of the reported rat CRF(2 alpha) receptor. At present, there is no evidence for the existence of a CRF(2 beta) receptor homolog in humans. The encoded receptor is 411 amino acids in length and is 70% identical to the human CRF(1) receptor, with least sequence homology in the N-terminal extracellular domain (47% identical). Cells transfected with the full-length human CRF(2) receptor cDNA responded to rat/human CRF and sauvagine by increasing the intracellular cAMP level, with EC(50) values of approximately 20 and 1 nM, respectively. The CRF- and sauvagine-induced accumulation of intracellular cAMP could be competitively inhibited by the CRF receptor antagonist D-Phe-CRF. This pharmacological profile was comparable to that of the rat CRF(2 alpha) receptor. The relative abundance of the CRF, receptor messenger RNA appears to be lower in humans than in rats for the tissues studied thus far.