TY - JOUR
T1 - Stimulus-dependent regulation of the phagocyte NADPH oxidase by a VAV1, Rac1, and PAK1 signaling axis.
AU - Roepstorff, Kirstine
AU - Rasmussen, Izabela Zorawska
AU - Sawada, Makoto
AU - Cudre-Maroux, Cristophe
AU - Salmon, Patrick
AU - Bokoch, Gary
AU - van Deurs, Bo
AU - Vilhardt, Frederik
N1 - Keywords: Amino Acid Substitution; Animals; Antigen-Antibody Complex; Carcinogens; Cell Line; Guanine Nucleotide Dissociation Inhibitors; Humans; Lim Kinases; Membrane Glycoproteins; Mice; Microglia; Mutation, Missense; N-Formylmethionine Leucyl-Phenylalanine; NADPH Oxidase; Neuropeptides; Phagocytes; Proto-Oncogene Proteins c-vav; Receptors, IgG; Respiratory Burst; Signal Transduction; Superoxides; Tetradecanoylphorbol Acetate; p21-Activated Kinases; rac GTP-Binding Proteins; rac1 GTP-Binding Protein
PY - 2008
Y1 - 2008
N2 - The p21-activated kinase-1 (PAK1) is best known for its role in the regulation of cytoskeletal and transcriptional signaling pathways. We show here in the microglia cell line Ra2 that PAK1 regulates NADPH oxidase (NOX-2) activity in a stimulus-specific manner. Thus, conditional expression of PAK1 dominant-positive mutants enhanced, whereas dominant-negative mutants inhibited, NADPH oxidase-mediated superoxide generation following formyl-methionyl-leucylphenylalanine or phorbol 12-myristate 13-acetate stimulation. Both Rac1 and the GTP exchange factor VAV1 were required as upstream signaling proteins in the formyl-methionyl-leucyl-phenylalanine-induced activation of endogenous PAK1. In contrast, PAK1 mutants had no effect on superoxide generation downstream of FcgammaR signaling during phagocytosis of IgG-immune complexes. We further present evidence that the effect of PAK1 on the respiratory burst is mediated through phosphorylation of p47(Phox), and we show that expression of a p47(Phox) (S303D/S304D/S320D) mutant, which mimics phosphorylation by PAK1, induced basal superoxide generation in vivo. In contrast PAK1 substrates LIMK-1 or RhoGDI are not likely to contribute to the PAK1 effect on NADPH oxidase activation. Collectively, our findings define a VAV1-Rac1-PAK1 signaling axis in mononuclear phagocytes regulating superoxide production in a stimulus-dependent manner.
AB - The p21-activated kinase-1 (PAK1) is best known for its role in the regulation of cytoskeletal and transcriptional signaling pathways. We show here in the microglia cell line Ra2 that PAK1 regulates NADPH oxidase (NOX-2) activity in a stimulus-specific manner. Thus, conditional expression of PAK1 dominant-positive mutants enhanced, whereas dominant-negative mutants inhibited, NADPH oxidase-mediated superoxide generation following formyl-methionyl-leucylphenylalanine or phorbol 12-myristate 13-acetate stimulation. Both Rac1 and the GTP exchange factor VAV1 were required as upstream signaling proteins in the formyl-methionyl-leucyl-phenylalanine-induced activation of endogenous PAK1. In contrast, PAK1 mutants had no effect on superoxide generation downstream of FcgammaR signaling during phagocytosis of IgG-immune complexes. We further present evidence that the effect of PAK1 on the respiratory burst is mediated through phosphorylation of p47(Phox), and we show that expression of a p47(Phox) (S303D/S304D/S320D) mutant, which mimics phosphorylation by PAK1, induced basal superoxide generation in vivo. In contrast PAK1 substrates LIMK-1 or RhoGDI are not likely to contribute to the PAK1 effect on NADPH oxidase activation. Collectively, our findings define a VAV1-Rac1-PAK1 signaling axis in mononuclear phagocytes regulating superoxide production in a stimulus-dependent manner.
U2 - 10.1074/jbc.M708281200
DO - 10.1074/jbc.M708281200
M3 - Journal article
C2 - 18160398
VL - 283
SP - 7983
EP - 7993
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 12
ER -