Impaired NADPH oxidase activity in Rac2-deficient murine neutrophils does not result from defective translocation of p47phox and p67 phox and can be rescued by exogenous arachidonic acid

Chaekyun Kim, Mary C. Dinauer

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Rac2 is a hematopoietic-specific Rho-GTPase that plays a stimulus-specific role in regulating reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation and other functional responses in neutropliils. In this study, rac2-/- neutropliils were shown to have significantly decreased NADPH oxidase activity and actin remodeling in response to exogenous arachidonic acid (AA), as previously observed for phorbol 12-myristate 13-acetate (PMA) or formyl-Met-Leu-Phe (fMLP) as agonists. PMA-, fMLP-, or AA-induced translocation of p47phox and p67phox to the plasma membrane was not impaired in rac2-/- neutrophils. Combined stimulation of rac2-/- neutrophils with exogenous AA and PMA had a synergistic effect on NADPH oxidase activity, and superoxide production increased to a level that was at least as high as wild-type cells and had no effect on fMLP-elicited enzyme activity. Membrane translocation of p47phox and p67phox as well as Rac1 activation was not increased further by combined PMA and AA stimulation. Inhibitor studies were consistent with important roles for phorbol ester-activated protein kinase C (PKC) isoforms and an atypical isoform, PKCζ, in superoxide production by wild-type and rac2-/- neutrophils stimulated with AA and PMA. In addition, PMA-stimulated release of AA and cyloplasmic phospholipase A2 expression in rac2-/- neutrophils were similar to wild-type, suggesting that deficient AA production by PMA-stimulated rac2-/- neutrophils does not explain the effect of exogenous AA on oxidase activity. Although not required for translocation of p47phox and p67phox, Rac2 is necessary for optimal activity of the assembled oxidase complex, an effect that can be replaced by exogenous AA, which may act directly or via an exogenous AA-induced mediator.

Original languageEnglish
Pages (from-to)223-234
Number of pages12
JournalJournal of Leukocyte Biology
Volume79
Issue number1
DOIs
StatePublished - Jan 1 2006
Externally publishedYes

Keywords

  • PKC
  • Rho-GTPase
  • Superoxide anion
  • cPLA

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