The HIV-1 Nef protein and phagocyte NADPH oxidase activation

Article Article scientifique Article The HIV-1 Nef protein and phagocyte NADPH oxidase activation eng 2002 author Vilhardt Frederik author Plastre Olivier 641822 author Sawada Makoto author Suzuki Kazuo author Wiznerowicz Maciej 133514 author Kiyokawa Etsuko 133411 author Trono Didier 116006 author Krause Karl-Heinz 23022 42136-42143 10.1074/jbc.M200862200 12207012 0021-9258 http://www.jbc.org/content/277/44/42136.full.pdf Nef, a multifunctional HIV protein, activates the Vav/Rac/p21-activated kinase (PAK) signaling pathway. Given the potential role of this pathway in the activation of the phagocyte NADPH oxidase, we have investigated the effect of the HIV-1 Nef protein on the phagocyte respiratory burst. Microglia (cell line and primary culture) were transduced with lentiviral expression vectors. Expression of Nef did not activate the NADPH oxidase by itself but led to a massive enhancement of the responses to a variety of stimuli (Ca(2+) ionophore, formyl peptide, endotoxin). These effects were not caused by up-regulation of phagocyte NADPH oxidase subunits. Nef mutants lacking motifs involved in the interaction with Vav and PAK failed to reproduce the effects of wild type Nef, suggesting a role for the Vav/Rac/PAK signaling pathway. The following results suggest a key role for Rac in the priming effect of Nef. (i) Inactivation of Rac by Clostridium difficile toxin B abolished the Nef effect. (ii) The fraction of activated Rac1 was increased in Nef-transduced cells, and (iii) the dominant positive Rac1(V12) mutant mimicked the effect of Nef. These results are to our knowledge the first analysis of the effect of Rac activation on the NADPH oxidase in intact phagocytes. Rac activation is not sufficient to stimulate the phagocyte NADPH oxidase; however, it markedly enhances the NADPH oxidase response to other stimuli. Amino Acid Motifs Animals Cell Line Enzyme Activation Gene Products, nef/ physiology HIV-1/ physiology Mice Microglia/enzymology NADPH Oxidase/ metabolism Oncogene Proteins/physiology Phagocytes/ enzymology Protein Subunits Proto-Oncogene Proteins c-vav Superoxides/metabolism nef Gene Products, Human Immunodeficiency Virus rac1 GTP-Binding Protein/physiology src Homology Domains Dewey 616.07 true The Journal of biological chemistry 277 44 c24220cf-8133-4a76-92d6-0fb3e52c6946 Article Restricted file1.pdf 320224 application/pdf restrictedAccess

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The HIV-1 Nef protein and phagocyte NADPH oxidase activation	The Journal of biological chemistry			2002	577	0

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Kiyokawa, Etsuko