title: Dual effect of oxidative stress on NF-kappakB activation in HeLa cells.
abstract: Reactive oxygen species (ROS) has been implicated as an inducer of NF-kappaB activity in numbers of cell types where exposure of cells to ROS such as H(2)O(2) leads to NF-kappaB activation. In contrast, exposure to oxidative stress in certain cell types induced reduction of tumor necrosis factor (TNF)- induced NF-kappaB activation. And various thiol-modifying agents including gold compounds and cyclopentenone prostaglandins inhibit NF-kappaB activation by blocking IkappaB kinase (IKK). To understand such conflicting effect of oxidative stress on NF- kappakB activation, HeLa cells were incubated with H(2)O(2) or diamide and TNF-induced expression of NF-kappaB reporter gene was measured. NF-kappaB activation was significantly blocked by these oxidizing agents, and the inhibition was accompanied with reduced nuclear NF-kappaB and inappropriate cytosolic IkappaB degradation. H(2)O(2) and diamide also inhibited IKK activation in HeLa and RAW 264.7 cells stimulated with TNF and lipopolysaccharide, respectively, and directly blocked IKK activity in vitro. In cells treated with H(2)O(2) alone, nuclear NF-kappaB was induced after 2 h without detectable degradation of cytosolic IkappaBalphaa or activation of IKK. Our results suggest that ROS has a dual effect on NF-kappaB activation in the same HeLa cells: it inhibits acute IKK-mediated NF-kappakB activation induced by inflammatory signals, while longer-term exposure to ROS induces NF-kappaB activity through an IKK-independent pathway.
authors.affiliation: Department of Biochemistry, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Seocho-gu, Seoul 137-701, Korea.
authors.forename: Mi-Sun
authors.initials: MS
authors.lastname: Byun
authors.forename: Kye-Im
authors.initials: KI
authors.lastname: Jeon
authors.forename: Jae-Won
authors.initials: JW
authors.lastname: Choi
authors.forename: Jae-Yong
authors.initials: JY
authors.lastname: Shim
authors.forename: Dae-Myung
authors.initials: DM
authors.lastname: Jue
mesh_terms: D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D003958:Diamide / Q000494:pharmacology; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D020672:I-kappa B Proteins; D016328:NF-kappa B; D016877:Oxidants; D014409:Tumor Necrosis Factor-alpha; D003958:Diamide; D006861:Hydrogen Peroxide; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human