AP-2α modulates human corticotropin-releasing hormone gene expression in the placenta by direct protein–protein interaction

Abstract

Since AP-2α induces the expression of hPL, hCG and other syncytiotrophoblast-specific marker genes in cytotrophoblast cells during in vitro differentiation, we have examined whether AP-2α also induces hCRH gene expression during differentiation of cytotrophoblast cells. Infection of human cytotrophoblast cells in vitro with an adenovirus expressing AP-2α resulted in a twofold increase in hCRH mRNA levels, while infection with an adenovirus expressing a dominant/negative mutant of AP-2α inhibited basal hCRH mRNA levels by 40% and completely blocked the induction of hCRH mRNA by AP-2α. Transient transfection studies in AtT-20 and HepG2 cells indicated that the induction of hCRH mRNA levels was due, at least in part, to transcriptional activation of the hCRH gene. Gel mobility shift and immunoprecipitation assays strongly suggest that AP-2α induces hCRH gene expression by interacting with CREB and not by binding directly to the hCRH promoter.