title: Protein kinase C inhibits transcription from the RNA polymerase III promoter of the human c-myc gene.
abstract: The c-myc promoter has a unique characteristic showing both RNA polymerase II (pol II) and RNA polymerase III (pol III) activities. Previous studies demonstrated that activating PKC results in upregulation of c-myc expression from its pol II promoter. However, how PKC activation affects expression from the pol III promoter of the c-myc gene is not well understood. This study examines the effect of PKC on the pol III transcription from the c-myc gene by using an in vitro system. We report the inhibition of the c-myc pol III transcript by activating PKC. Further, either a phosphocellulose fraction of HeLa whole cell extract (WCE) enriched for transcription factor TF IIIB, or recombinant TATA-box binding protein could restore the inhibited c-myc pol III transcription under conditions that activate PKC. A role has been proposed for the c-myc pol III transcript in the regulation of c-myc gene expression. Therefore, this report discusses the significance of the downregulation of c-myc expression from its pol III promoter and the possible interplay between the pol II and pol III promoters of this gene.
authors.affiliation: Department of Biological Sciences, Program in Molecular and Cellular Biology, Ohio University, Athens 45701, USA.
authors.forename: G
authors.initials: G
authors.lastname: Xu
authors.forename: Q
authors.initials: Q
authors.lastname: Gai
authors.forename: C B
authors.initials: CB
authors.lastname: James
mesh_terms: D002458:Cell Fractionation; D004789:Enzyme Activation; D005786:Gene Expression Regulation / Q000187:drug effects*; D016259:Genes, myc / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000502:physiology*; D012320:RNA Polymerase III / Q000037:antagonists & inhibitors* / Q000502:physiology; D016385:TATA Box / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D011493:Protein Kinase C; D012320:RNA Polymerase III; D013755:Tetradecanoylphorbol Acetate