Tumor necrosis factor gene expression is mediated by protein kinase C following activation by ionizing radiation.
Tumor necrosis factor (TNF) production following X-irradiation has been implicated in the biological response to ionizing radiation. Protein kinase C (PKC) is suggested to participate in TNF transcriptional induction and X-ray-mediated gene expression. We therefore studied radiation-mediated TNF expression in HL-60 cells with diminished PKC activity produced by either pretreatment with protein kinase inhibitors or prolonged 12-O-tetradecanoylphorbol-13-acetate treatment. Both treatments resulted in attenuation of radiation-mediated TNF induction. Consistent with these results, we found no detectable induction of TNF expression following X-irradiation in the HL-60 variant deficient in PKC-mediated signal transduction. The rapid activation of PKC following gamma-irradiation was established using an in vitro assay measuring phosphorylation of a PKC specific substrate. A 4.5-fold increase in PKC activity occurred 15 to 30 s following irradiation, which declined to baseline at 60 s. Two-dimensional gel electrophoresis of phosphoproteins extracted from irradiated cells demonstrated in vivo phosphorylation of the PKC specific substrate Mr 80,000 protein at 45 s following X-irradiation. These findings indicate that signal transduction via the PKC pathway is required for the induction of TNF gene expression by ionizing radiation.
Hallahan
D E
DE
Department of Radiation and Cellular Oncology, University of Chicago, Illinois 60637.
Virudachalam
S
S
Sherman
M L
ML
Huberman
E
E
Kufe
D W
DW
Weichselbaum
R R
RR
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D002460:Cell Line; D015536:Down-Regulation; D004789:Enzyme Activation; D005786:Gene Expression Regulation / Q000528:radiation effects*; D007546:Isoquinolines / Q000494:pharmacology; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D013449:Sulfonamides; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
D007546:Isoquinolines; D010879:Piperazines; D013449:Sulfonamides; D014409:Tumor Necrosis Factor-alpha; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C043204:N-(2-guanidinoethyl)-5-isoquinolinesulfonamide; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate