Fc{gamma}R-stimulated activation of the NADPH oxidase: Phosphoinositide- binding protein p40phox regulates NADPH oxidase activity after enzyme assembly on the phagosome

Wei Tian, Xing Jun Li, Natalie D. Stull, Wenyu Ming, Chang Ii Sun, Sarah A. Bissonnette, Michael B. Yaffe, Sergio Grinstein, Simon J. Atkinson, Mary C. Dinauer

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82 Scopus citations

Abstract

The phagocyte NADPH oxidase generates superoxide for microbial killing, and Includes a membrane-bound flavocytochrome b558 and cytosolic p67phox, p47phox and p40phox subunits that undergo membrane translocation upon cellular activation. The function of p40phox, which binds pGphox in resting cells, is incompletely understood. Recent studies showed that phagocytosis-Induced superoxide production is stimulated by p40phox and its binding to phosphatidylinositol-3-phosphate (PI3P), a phosphoinositide enriched in membranes of internalized phagosomes. To better define the role of p40 Phox Fcγ-induced oxidase activation, we used immunofluorescence and real-time imaging of FcγR-induced phagocytosis. YFP-tagged p67 phox and p40phox translocated to granulocyte phagosomes before phagosome internalization and accumulation of a probe for PI3P. p67 phox and p47phox accumulation on nascent and internalized phagosomes did not require p40phox or PI3 kinase activity, although superoxide production before and after phagosome sealing was decreased by mutation of the p40phox PI3P-binding domain or wortmannin. Translocation of p40phox to nascent phagosomes required binding to p67phox but not PI3P, although the loss of PI3P binding reduced p40phox retention after phagosome internalization. We conclude that p40phox functions primarily to regulate FcγR-induced NADPH oxidase activity rather than assembly, and stimulates superoxide production via a PI3P signal that increases after phagosome internalization.

Original languageEnglish
Pages (from-to)3867-3877
Number of pages11
JournalBlood
Volume112
Issue number9
DOIs
StatePublished - Nov 1 2008

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