Phorbolester stimulates the activity of human corticotropin-releasing hormone gene promoter via 3',5'-cyclic adenosine monophosphate response element in transiently transfected chicken macrophages.

Abstract

We previously characterized the transcriptional activity of the human CRH (hCRH) gene promoter in the mouse anterior pituitary cell line AtT20. Here, we show that phorbolester stimulated through the cAMP response element (CRE), located between -227 and -220 relative to the putative cap site, about 2.6-fold the expression of a chimeric hCRH-chloramphenicol-acetyl-transferase gene which was transiently transfected into chicken macrophages (HD11 cell line). The induction was dependent on the cell types, and was not observed when AtT20 were used as target cells. Elevated mouse c-fos protein expressed from a cotransfecting plasmid pRSVfos or human c-jun protein expressed from RSVjun led to 2.1-fold and 3.1-fold stimulation of the activity of the hCRH promoter. Tetradecanoyl-phorbol-13-acetate stimulated the c-fos and c-jun transactivation by a factor of 10 and 2.6, indicating a modification of c-fos and c-jun is required for the transactivation induced by protein kinase C activation. Mutation within the cAMP response element abolished this transcriptional activation. This result suggests an involvement of the protein kinase C pathway in the regulation of the CRH gene expression.