Nucleotide sequence and structural organization of the human vasopressin pituitary receptor (V3) gene

In the pituitary, vasopressin triggers ACTH release through a specific rece ptor subtype, termed V3 or V1b. We cloned the V3 cDNA and showed that its e xpression was almost exclusive to pituitary corticotrophs and some corticot roph tumors. To study the determinants of this tissue specificity, we have now cloned the gene for the human (h) V3 receptor and characterized its str ucture. It is composed of two exons, spanning 10 kb, with the coding region interrupted between transmembrane domains 6 and 7. We established that the transcription initiation site is located 498 nucleotides upstream of the i nitiator codon and showed that two polyadenylation sites may be used, while the most frequent is the most downstream. Sequence analysis of the promote r region showed no TATA box but identified consensus binding motifs for Sp1 , CREB, and half sites of the estrogen receptor binding site. However compa rison with another corticotroph-specific gene, proopiomelanocortin, did not identify common regulatory elements in the two promoters except for a shor t GC-rich region. Unexpectedly, hV3 gene analysis revealed that a formerly cloned 'artifactual' hV3 cDNA indeed corresponded to a spliced antisense tr anscript, overlapping the 5' part of the coding sequence in exon 1 and the promoter region. This transcript, hV3rev, was detected in normal pituitary and in many corticotroph tumors expressing hV3 sense mRNA and may therefore play a role in hV3 gene expression. (C) 2000 Elsevier Science B.V. All rig hts reserved.