title: Modulation of SCF beta-TrCP-dependent I kappaB alpha ubiquitination by hydrogen peroxide.
abstract: Reactive oxygen species are known to participate in the regulation of intracellular signaling pathways, including activation of NF-kappaB. Recent studies have indicated that increases in intracellular concentrations of hydrogen peroxide (H(2)O(2)) have anti-inflammatory effects in neutrophils, including inhibition of the degradation of I kappaB alpha after TLR4 engagement. In the present experiments, we found that culture of lipopolysaccharide-stimulated neutrophils and HEK 293 cells with H(2)O(2) resulted in diminished ubiquitination of I kappaB alpha and decreased SCF(beta-TrCP) ubiquitin ligase activity. Exposure of neutrophils or HEK 293 cells to H(2)O(2) was associated with reduced binding between phosphorylated I kappaB alpha and SCF(beta-TrCP) but no change in the composition of the SCF(beta-TrCP) complex. Lipopolysaccharide-induced SCF(beta-TrCP) ubiquitin ligase activity as well as binding of beta-TrCP to phosphorylated I kappaB alpha was decreased in the lungs of acatalasemic mice and mice treated with the catalase inhibitor aminotriazole, situations in which intracellular concentrations of H(2)O(2) are increased. Exposure to H(2)O(2) resulted in oxidative modification of cysteine residues in beta-TrCP. Cysteine 308 in Blade 1 of the beta-TrCP beta-propeller region was found to be required for maximal binding between beta-TrCP and phosphorylated I kappaB alpha. These findings suggest that the anti-inflammatory effects of H(2)O(2) may result from its ability to decrease ubiquitination as well as subsequent degradation of I kappaB alpha through inhibiting the association between I kappaB alpha and SCF(beta-TrCP).
authors.affiliation: Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-0012, USA.
authors.forename: Sami
authors.initials: S
authors.lastname: Banerjee
authors.forename: Jaroslaw W
authors.initials: JW
authors.lastname: Zmijewski
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Lorne
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Sha
authors.forename: Edward
authors.initials: E
authors.lastname: Abraham
mesh_terms: D020642:Acatalasia / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism*; D055371:Acute Lung Injury / Q000139:chemically induced / Q000378:metabolism*; D000640:Amitrole / Q000494:pharmacology; D000818:Animals; D002374:Catalase / Q000037:antagonists & inhibitors / Q000378:metabolism; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D020672:I-kappa B Proteins / Q000378:metabolism*; D007668:Kidney / Q000166:cytology; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D000072000:NF-KappaB Inhibitor alpha; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects; D016877:Oxidants / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D004791:Enzyme Inhibitors; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D016877:Oxidants; C082161:lipopolysaccharide A; D000072000:NF-KappaB Inhibitor alpha; D006861:Hydrogen Peroxide; D002374:Catalase; D044843:SKP Cullin F-Box Protein Ligases; D000640:Amitrole