title: Regulation of the phagocyte NADPH oxidase activity: phosphorylation of gp91phox/NOX2 by protein kinase C enhances its diaphorase activity and binding to Rac2, p67phox, and p47phox.
abstract: Neutrophils generate microbicidal oxidants through activation of a multicomponent enzyme called NADPH oxidase. During activation, the cytosolic NADPH oxidase components (p47(phox), p67(phox), p40(phox), and Rac2) translocate to the membranes, where they associate with flavocytochrome b(558), which is composed of gp91(phox)/NOX2 and p22(phox), to form the active system. During neutrophil stimulation, p47(phox), p67(phox), p40(phox), and p22(phox) are phosphorylated; however, the phosphorylation of gp91(phox)/NOX2 and its potential role have not been defined. In this study, we show that gp91(phox) is phosphorylated in stimulated neutrophils. The gp91(phox) phosphoprotein is absent in neutrophils from chronic granulomatous disease patients deficient in gp91(phox), which confirms that this phosphoprotein is gp91(phox). The protein kinase C inhibitor GF109203X inhibited phorbol 12-myristate 13-acetate-induced phosphorylation of gp91(phox), and protein kinase C (PKC) phosphorylated the recombinant gp91(phox)- cytosolic carboxy-terminal flavoprotein domain. Two-dimensional tryptic peptide mapping analysis showed that PKC phosphorylated the gp91(phox)-cytosolic tail on the same peptides that were phosphorylated on gp91(phox) in intact cells. In addition, PKC phosphorylation increased diaphorase activity of the gp91(phox) flavoprotein cytosolic domain and its binding to Rac2, p67(phox), and p47(phox). These results demonstrate that gp91(phox) is phosphorylated in human neutrophils by PKC to enhance its catalytic activity and assembly of the complex. Phosphorylation of gp91(phox)/NOX2 is a novel mechanism of NADPH oxidase regulation.
authors.affiliation: INSERM U773, Centre de Recherche Biomédicale Bichat Beaujon CRB3, Université Paris 7, Paris, France.
authors.forename: Houssam
authors.initials: H
authors.lastname: Raad
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Paclet
authors.forename: Tarek
authors.initials: T
authors.lastname: Boussetta
authors.forename: Yolande
authors.initials: Y
authors.lastname: Kroviarski
authors.forename: Françoise
authors.initials: F
authors.lastname: Morel
authors.forename: Mark T
authors.initials: MT
authors.lastname: Quinn
authors.forename: Marie-Anne
authors.initials: MA
authors.lastname: Gougerot-Pocidalo
authors.forename: Pham My-Chan
authors.initials: PM
authors.lastname: Dang
authors.forename: Jamel
authors.initials: J
authors.lastname: El-Benna
mesh_terms: D001665:Binding Sites; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D006105:Granulomatous Disease, Chronic / Q000201:enzymology / Q000378:metabolism; D006801:Humans; D019255:NADPH Oxidases / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism; D010586:Phagocytes / Q000201:enzymology* / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020744:rac GTP-Binding Proteins / Q000378:metabolism*; D000097766:RAC2 GTP-Binding Protein
chemical_list: D019255:NADPH Oxidases; D010750:Phosphoproteins; D011493:Protein Kinase C; D020744:rac GTP-Binding Proteins; D000097766:RAC2 GTP-Binding Protein; C079789:neutrophil cytosol factor 67K