title: The Rac effector p67phox regulates phagocyte NADPH oxidase by stimulating Vav1 guanine nucleotide exchange activity.
abstract: The phagocyte NADPH oxidase catalyzes the reduction of molecular oxygen to superoxide and is essential for microbial defense. Electron transport through the oxidase flavocytochrome is activated by the Rac effector p67(phox). Previous studies suggest that Vav1 regulates NADPH oxidase activity elicited by the chemoattractant formyl-Met-Leu-Phe (fMLP). We show that Vav1 associates with p67(phox) and Rac2, but not Rac1, in fMLP-stimulated human neutrophils, correlating with superoxide production. The interaction of p67(phox) with Vav1 is direct and activates nucleotide exchange on Rac, which enhances the interaction between p67(phox) and Vav1. This provides new molecular insights into regulation of the neutrophil NADPH oxidase, suggesting that chemoattractant-stimulated superoxide production can be amplified by a positive feedback loop in which p67(phox) targets Vav1-mediated Rac activation.
authors.affiliation: Cancer Research Institute, 1044 W. Walnut Street, R4 402C, Indianapolis, IN 46202, USA.
authors.forename: Wenyu
authors.initials: W
authors.lastname: Ming
authors.forename: Shijun
authors.initials: S
authors.lastname: Li
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Billadeau
authors.forename: Lawrence A
authors.initials: LA
authors.lastname: Quilliam
authors.forename: Mary C
authors.initials: MC
authors.lastname: Dinauer
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D015971:Gene Expression Regulation, Enzymologic; D006098:Granulocytes / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006801:Humans; D019255:NADPH Oxidases / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism; D010586:Phagocytes / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism / Q000502:physiology*; D051567:Proto-Oncogene Proteins c-vav / Q000502:physiology*; D020744:rac GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D010750:Phosphoproteins; D051567:Proto-Oncogene Proteins c-vav; C496618:VAV1 protein, human; C079789:neutrophil cytosol factor 67K; D019255:NADPH Oxidases; D020744:rac GTP-Binding Proteins