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RhoG is a Rho family small GTPase implicated in cytoskeletal regulation, acting either upstream of or in parallel to Rac1. The precise function(s) of RhoG in vivo has not yet been defined. We have identified a novel role for RhoG in signaling the neutrophil respiratory burst stimulated by G protein-coupled receptor agonists. Bone marrow-derived neutrophils from RhoG knockout (RhoG(-/-)) mice exhibited a marked impairment of oxidant generation in response to C5a or fMLP, but normal responses to PMA or opsonized zymosan and normal bacterial killing. Activation of Rac1 and Rac2 by fMLP was diminished in RhoG(-/-) neutrophils only at very early (5 s) time points (by 25 and 32%, respectively), whereas chemotaxis in response to soluble agonists was unaffected by lack of RhoG. Additionally, fMLP-stimulated phosphorylation of protein kinase B and p38MAPK, activation of phospholipase D, and calcium fluxes were equivalent in wild-type and RhoG(-/-) neutrophils. Our results define RhoG as a critical component of G protein-coupled receptor-stimulated signaling cascades in murine neutrophils, acting either via a subset of total cellular Rac relevant to oxidase activation and/or by a novel and as yet undefined interaction with the neutrophil NADPH oxidase.

Type

Journal article

Journal

J Immunol

Publication Date

01/05/2006

Volume

176

Pages

5314 - 5320

Keywords

Animals, Calcium, Catecholamines, Cells, Cultured, Chemotaxis, Leukocyte, Enzyme Activation, Gene Expression Regulation, Enzymologic, Humans, Imidazolines, Mice, Mice, Knockout, NADPH Oxidases, Neutrophils, Phospholipase D, Signal Transduction, Solubility, cdc42 GTP-Binding Protein, rac GTP-Binding Proteins, rho GTP-Binding Proteins