title: Suppression of GnRH gene expression in GT1-1 hypothalamic neuronal cells: action of protein kinase C.
abstract: We attempted to elucidate molecular mechanisms of gonadotropin-releasing hormone (GnRH) gene regulation by the protein kinase C (PKC) pathway in GT1-1 cells. Activation of PKC with 12-tetra-decanoylphorbol-13-acetate (TPA) or inhibition with staurosporine or calphostin C down-regulated GnRH mRNA levels. A serial deletion mutant analysis revealed that this suppression was mediated by the proximal region (-187/-69) of the mouse GnRH promoter. TPA transiently induced c-fos mRNA, whereas staurosporine or calphostin C failed to do so. However, PKC inhibitors blocked the TPA-evoked c-fos induction. Over-expression of PKC alpha down-regulated GnRH promoter activity, indicating that PKC activation was sufficient to inhibit GnRH gene expression. These results suggest that both activation and inhibition of PKC decrease the GnRH gene expression in the GT1-1 cells probably through different signal cascade mechanisms.
authors.affiliation: Department of Molecular Biology and Research Center for Cell Differentiation, College of Natural Sciences, Seoul National University, Korea.
authors.forename: W
authors.initials: W
authors.lastname: Sun
authors.forename: Y S
authors.initials: YS
authors.lastname: Choe
authors.forename: Y J
authors.initials: YJ
authors.lastname: Lee
authors.forename: K
authors.initials: K
authors.lastname: Kim
mesh_terms: D000818:Animals; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D007987:Gonadotropin-Releasing Hormone / Q000096:biosynthesis* / Q000235:genetics; D007031:Hypothalamus / Q000378:metabolism*; D007527:Isoenzymes / Q000096:biosynthesis; D008156:Luciferases / Q000096:biosynthesis; D051379:Mice; D009281:Naphthalenes / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000096:biosynthesis / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D009281:Naphthalenes; D016760:Proto-Oncogene Proteins c-fos; D011993:Recombinant Fusion Proteins; D007987:Gonadotropin-Releasing Hormone; D008156:Luciferases; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D019311:Staurosporine; C058819:calphostin C; D013755:Tetradecanoylphorbol Acetate