title: Phosphoinositide 3-kinase activity leads to silica-induced NF-kappaB activation through interacting with tyrosine-phosphorylated I(kappa)B-alpha and contributing to tyrosine phosphorylation of p65 NF-kappaB.
abstract: The role of the subunits of phosphoinositide (PI) 3-kinase in NF-kappaB activation in silica-stimulated RAW 264.7 cells was investigated. Results indicate that PI3-kinase activity was increased in response to silica. The p85alpha subunit of PI3-kinase interacted with tyrosine-phosphorylated I(kappa)B-alpha in silica-stimulated cells. PI3-kinase specific inhibitors, such as wortmannin and LY294003, substantially blocked both silica-induced PI3-kinase and NF-kappaB activation. The inhibition of NF-KB activation by PI3-kinase inhibitors was also observed in pervanadate-stimulated but not in LPS-stimulated cells. Furthermore, tyrosine phosphorylation of NF-kappaB p65 was enhanced in cells stimulated with silica, pervanadate or LPS, and wortmannin substantially inhibited the phosphorylation event induced by the first two stimulants but not LPS. Antioxidants, such as superoxide dismutase (SOD), N-acetylcysteine (NAC) and pyrrolidine dithiocarbamate (PDTC), blocked silica-induced PI3-kinase activation, suggesting that reactive oxygen species may be important regulatory molecules in NF-kappaB activation by mediating PI3-kinase activation. Our data suggest that p85 and p110 subunits of PI3-kinase play a role in NF-kappaB activation through interaction with tyrosine-phosphorylated I(kappa)B-alpha and contributing to tyrosine phosphorylation of p65 NF-kappaB.
authors.affiliation: Department of Physiology, College of Medicine, Division of Cell Biology, Ewha Medical Research Center, Ewha Womans University, Seoul, Korea. jihee@mm.ewha.ac.kr
authors.forename: Jihee Lee
authors.initials: JL
authors.lastname: Kang
authors.forename: Hui Su
authors.initials: HS
authors.lastname: Lee
authors.forename: In Soon
authors.initials: IS
authors.lastname: Pack
authors.forename: Kyu Chung
authors.initials: KC
authors.lastname: Hur
authors.forename: Vincent
authors.initials: V
authors.lastname: Castranova
mesh_terms: D000111:Acetylcysteine / Q000737:chemistry; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D020672:I-kappa B Proteins / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008954:Models, Biological; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D011759:Pyrrolidines / Q000494:pharmacology; D017382:Reactive Oxygen Species; D012822:Silicon Dioxide / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000378:metabolism; D013859:Thiocarbamates / Q000494:pharmacology; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism; D000077191:Wortmannin; D019892:eIF-2 Kinase / Q000378:metabolism*
chemical_list: D000730:Androstadienes; D000975:Antioxidants; D004791:Enzyme Inhibitors; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D011759:Pyrrolidines; D017382:Reactive Oxygen Species; D013859:Thiocarbamates; D000072000:NF-KappaB Inhibitor alpha; C020972:pyrrolidine dithiocarbamic acid; D014443:Tyrosine; D012822:Silicon Dioxide; D013482:Superoxide Dismutase; D019869:Phosphatidylinositol 3-Kinases; D019892:eIF-2 Kinase; D000111:Acetylcysteine; D000077191:Wortmannin