Cyclic adenosine 3 ',5 '-monophosphate (cAMP) and cAMP responsive element-binding protein are involved in the transcriptional regulation of gonadotropin-releasing hormone (GnRH) receptor by GnRH and mitogen-activated proteinkinase signal transduction pathway in GGH(3) cells

Stimulation of mouse GnRH receptor promoter by a GnRH agonist (Buserelin), or by a cAMP analogue, significantly increased reporter (luciferase) activi ty. Overexpression of Raf-1, ERK1, or ERK2 partially blocked Buserelin-stim ulated luciferase activity. In contrast, treatment with a mitogen-activated protein kinase (MAPK) kinase inhibitor (PD 98059) activated basal and Buse relin-stimulated luciferase activity in a dose-dependent manner. Transient transfection of the deleted cAMP response element expression vector followe d by pretreatment with PD98059 prior to Buserelin stimulation showed that t he transcriptional response was decreased compared to wild-type promoter. A gel-mobility shift assay using a probe containing the cAMP response elemen t showed the presence of two specific protein-DNA complexes that contain on e or more members of the cAMP responsive element-binding (CREB) protein fam ily. These results suggest that cAMP and CREB participate in the GnRH activ ation of GnRH receptor promoter activity and that the MAPK cascade is invol ved in the negative regulation of basal and GnRH-stimulated GnRH receptor t ranscriptional activity.