title: Role of protein kinase C activity in tumor necrosis factor-alpha gene expression. Involvement at the transcriptional level.
abstract: Primary rat astrocytes express TNF-alpha protein in response to various stimuli including a combined treatment with IFN-gamma and LPS, or IFN-gamma and IL-1 beta. This study was undertaken to further elucidate the mechanisms underlying TNF-alpha gene expression in the astrocyte, and to determine the intracellular signaling pathways involved in IFN-gamma/LPS and/or IFN-gamma/IL-1 beta induction of the TNF-alpha gene. We demonstrate that TNF-alpha mRNA is rapidly induced, and mRNA levels peak after 2 h of stimulation. De novo protein synthesis is not required for TNF-alpha expression because the inclusion of cycloheximide does not prevent expression of the gene and acts to superinduce TNF-alpha mRNA levels. IFN-gamma/LPS induces transcriptional activation of the TNF-alpha gene as assessed by nuclear run-on experiments. Cycloheximide acts to increase both transcription of the TNF-alpha gene and stability of TNF-alpha mRNA thereby resulting in increased TNF-alpha steady state mRNA levels. Two protein kinase C (PKC) inhibitors, H7 and staurosporine, abrogate IFN-gamma/LPS- and IFN-gamma/IL-1 beta-induced TNF-alpha expression in a dose-dependent manner. PKC activity is required for transcription of the TNF-alpha gene, and does not appear to be involved in TNF-alpha mRNA stabilization. Taken together, these data demonstrate that TNF-alpha gene expression in primary rat astrocytes is induced in a PKC-dependent manner.
authors.affiliation: Department of Cell Biology, University of Alabama, Birmingham 35294.
authors.forename: I Y
authors.initials: IY
authors.lastname: Chung
authors.forename: J
authors.initials: J
authors.lastname: Kwon
authors.forename: E N
authors.initials: EN
authors.lastname: Benveniste
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D001483:Base Sequence; D003513:Cycloheximide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D007371:Interferon-gamma / Q000502:physiology; D007375:Interleukin-1 / Q000502:physiology; D007546:Isoquinolines / Q000494:pharmacology; D008070:Lipopolysaccharides; D008969:Molecular Sequence Data; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology*; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D015290:Second Messenger Systems / Q000187:drug effects / Q000502:physiology; D019311:Staurosporine; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
chemical_list: D000470:Alkaloids; D007375:Interleukin-1; D007546:Isoquinolines; D008070:Lipopolysaccharides; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D003513:Cycloheximide; D011493:Protein Kinase C; D019311:Staurosporine