title: Regulation of phagocyte NADPH oxidase by hydrogen peroxide through a Ca(2+)/c-Abl signaling pathway.
abstract: The importance of H(2)O(2) as a cellular signaling molecule has been demonstrated in a number of cell types and pathways. Here we explore a positive feedback mechanism of H(2)O(2)-mediated regulation of the phagocyte respiratory burst NADPH oxidase (NOX2). H(2)O(2) induced a dose-dependent stimulation of superoxide production in human neutrophils, as well as in K562 leukemia cells overexpressing NOX2 system components. Stimulation was abrogated by the addition of catalase, the extracellular Ca(2+) chelator BAPTA, the T-type Ca(2+) channel inhibitor mibefradil, the PKCdelta inhibitor rottlerin, or the c-Abl nonreceptor tyrosine kinase inhibitor imatinib mesylate or by overexpression of a dominant-negative form of c-Abl. H(2)O(2) induced phosphorylation of tyrosine 311 on PKCdelta and this activating phosphorylation was blocked by treatment with rottlerin, imatinib mesylate, or BAPTA. Rac GTPase activation in response to H(2)O(2) was abrogated by BAPTA, imatinib mesylate, or rottlerin. In conclusion, H(2)O(2) stimulates NOX2-mediated superoxide generation in neutrophils and K562/NOX2 cells via a signaling pathway involving Ca(2+) influx and c-Abl tyrosine kinase acting upstream of PKCdelta. This positive feedback regulatory pathway has important implications for amplifying the innate immune response and contributing to oxidative stress in inflammatory disorders.
authors.affiliation: Department of Medicine, University of Texas Health Science Center, and South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio, TX 78229-3900, USA. AkoulouzeBik@uthscsa.edu
authors.forename: Amina
authors.initials: A
authors.lastname: El Jamali
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Valente
authors.forename: Robert A
authors.initials: RA
authors.lastname: Clark
mesh_terms: D002118:Calcium / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D010586:Phagocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010766:Phosphorylation; D051745:Protein Kinase C-delta / Q000378:metabolism; D016315:Proto-Oncogene Proteins c-abl / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D013481:Superoxides / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
chemical_list: D008562:Membrane Glycoproteins; D013481:Superoxides; D014443:Tyrosine; D006861:Hydrogen Peroxide; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D016315:Proto-Oncogene Proteins c-abl; D051745:Protein Kinase C-delta; D002118:Calcium