ISOLATION AND CHARACTERIZATION OF THE RAT CORTICOTROPIN-RELEASING HORMONE (CRH)-BINDING PROTEIN GENE - TRANSCRIPTIONAL REGULATION BY CYCLICADENOSINE-MONOPHOSPHATE AND CRH

The CRH-binding protein (CRH-BP) antagonizes the ACTH-releasing activi ty of the neuropeptide CRH in vitro. However, the function of CRH-BP i n vivo and the molecular mechanisms that regulate CRH-BP expression ar e not well understood. In this study, the rat CRH-EP gene was characte rized, and CRH-BP promoter sequences were identified. The rat CRH-BP g ene spans almost 12 kilobases and contains 7 exons. Ribonuclease prote ction experiments indicate that transcription of the CRH-BP gene initi ates at multiple sites in rat cerebral cortex. Transfection experiment s with CRH-BP-reporter constructs, containing 88-3500 bp 5' flanking a nd 66 bp 5' untranslated DNA from the rat CRH-BP gene, demonstrate bas al promoter activity in multiple cell lines. CRH-BP-reporter construct s also demonstrate positive regulation of promoter activity by cAMP in a variety of cell lines and by CRH in cells expressing the CRH recept or. The DNA sequences between -341 and -88 bp, including the cAMP resp onse element-like sequence at -127 bp, are required for maximal cAMP a nd CRH regulation of CRH-BP promoter activity. These studies suggest t hat CRH-BP transcription in vivo may be positively regulated by cAMP a nd CRH.