The role of superoxide radical in TNF-alpha induced NF-kappaB activation.
Electron spin resonable (ESR) spin trapping with 5-(diethioxyphosphoyl)-5-methyl-1-pyrroline N-oxide (DEPMPO) was utilized to investigate the generation of oxygen free radicals from macrophages stimulated by tumor necrosis factor-alpha (TNF-alpha). TNF-alpha stimulated macrophages generated hydroxyl (*OH) and superoxide anion (O2*-) radicals. Incubation of TNF-alpha with macrophages resulted in an activation of DNA binding activity of the nuclear transcription factor NF-kappaB. Superoxide dismutase (SOD), but not catalase or sodium formate, inhibited this NF-kappaB activation, suggesting that O2*- rather than H2O2 or *OH, radicals play the most critical role in this induction. beta-Nicotinamide adenine dinucleotide phosphate (NADPH) did not affect the NF-kappaB activation, while allopurinol, an inhibitor of xanthine oxidase, repressed it, suggesting that xanthine/xanthine oxidase, and not NADPH dependent oxidase, may be a source of O2*- radicals which induce NF-kappaB activation. 02*- is generated via reduction of molecular oxygen by xanthine and xanthine oxidase, as demonstrated by the oxygen consumption assay. The results indicate that TNF-alpha induces oxygen radical generation from macrophages. 02*- seems to play a key role in TNF-alpha-induced NF-kappaB activation in macrophages. Xanthine and xanthine oxidase appears to be a source of O2*- radicals responsible for TNF-alpha-induced NF-kappaB activation.
Wang
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Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA.
Leonard
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SS
Castranova
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Vallyathan
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Shi
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D000818:Animals; D002460:Cell Line; D003497:Cyclic N-Oxides; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D013113:Spin Labels; D013482:Superoxide Dismutase / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D003497:Cyclic N-Oxides; D005609:Free Radicals; D016328:NF-kappa B; D013113:Spin Labels; D014409:Tumor Necrosis Factor-alpha; C098505:5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide; D013482:Superoxide Dismutase