Regulation of human corticotropin-releasing hormone gene expression by 3',5'-cyclic adenosine monophosphate in a transformed mouse corticotroph cell line.
In order to characterize potential mechanisms regulating the expression of the human CRH (hCRH) gene, an intact genomic fragment including 5'-flanking sequence of the hCRH gene was stably transfected into the mouse corticotroph AtT20 cell line. The exogenous hCRH gene was expressed at a high frequency with accurate and efficient transcription in transformed cells. Northern blot analysis revealed a single species of CRH mRNA of 1.6 kilobases which was identical in size to human placental CRH mRNA. S1 analysis demonstrated a single cap site in both placenta and transformed AtT20 cells, corresponding to a site 23 base pairs downstream of the TATA box. Treatment with 8-bromo cAMP and phorbol ester resulted in a dose-dependent increase in CRH secretion during a 1-h incubation. Treatment with forskolin or 8-bromo-cAMP also produced a dose-dependent 4- to 10-fold increase in CRH mRNA levels, which was rapid (1 h) and sustained (6, 12, 24, and 48 h). These effects in a well characterized continuous cell culture system demonstrate pretranslational regulation of CRH expression by a cAMP-dependent pathway.
Dorin
R I
RI
Department of Medicine and Biochemistry, University of New Mexico School of Medicine, Albuquerque 87108.
Takahashi
H
H
Nakai
Y
Y
Fukata
J
J
Naitoh
Y
Y
Imura
H
H
D000818:Animals; D015152:Blotting, Northern; D002461:Cell Line, Transformed; D003346:Corticotropin-Releasing Hormone / Q000235:genetics*; D000242:Cyclic AMP / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D051379:Mice; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D014158:Transcription, Genetic; D014162:Transfection
D012333:RNA, Messenger; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP