Glucocorticoid repression of 3',5'-cyclic-adenosine monophosphate-dependent human corticotropin-releasing-hormone gene promoter activity in a transfected mouse anterior pituitary cell line.
The regulation of the expression of the human corticotropin-releasing-hormone gene (hCRH) was studied in a mouse anterior pituitary cell line (AtT20) after transiently transfection with a chimeric gene containing the hCRH gene promoter fused to the bacterial chloramphenicol acetyltransferase (CAT) gene. Expression of the chimeric hCRH-CAT gene in AtT20 cells was enhanced by the cAMP analog (8-bromo-cAMP) about 5-fold but not by phorbol 12-myristate-13-acetate. The cAMP phosphodiesterase inhibitor isobutylmethylxanthine also strongly stimulated 15-fold the expression of the chimeric hCRH-CAT gene. Coincubation of cAMP analog and isobutylmethylxanthine resulted in a moderate 2-fold synergistic enhancement of CAT activity. Sequence comparison of the hCRH gene revealed a core sequence for a cAMP responsive element 5'-TGACGTCA-3' at -221 relative to the cap site. This regulatory element also confers cAMP inducibility on a heterologous promoter when placed upstream of the thymidine kinase promoter from herpes simplex virus. Finally, treatment with 0.5 microM dexamethasone reduced CAT activity about 2.0-fold in cAMP-stimulated cells. This result suggests that cAMP and glucocorticoids coordinately control hCRH gene expression.
University of Karlsruhe (L.P.V.), Institute for Genetics and Toxicology, Federal Republic of Germany.
L P
LP
Van
D H
DH
Spengler
F
F
Holsboer
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003346:Corticotropin-Releasing Hormone / Q000235:genetics*; D000242:Cyclic AMP / Q000494:pharmacology*; D004274:DNA, Recombinant; D003907:Dexamethasone / Q000494:pharmacology*; D004357:Drug Synergism; D005786:Gene Expression Regulation / Q000187:drug effects*; D051379:Mice; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection
D004274:DNA, Recombinant; D015124:8-Bromo Cyclic Adenosine Monophosphate; D003907:Dexamethasone; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP; D015500:Chloramphenicol O-Acetyltransferase; D013755:Tetradecanoylphorbol Acetate; D015056:1-Methyl-3-isobutylxanthine