Unique targeting of cytosolic phospholipase A₂ to plasma membranes mediated by the NADPH oxidase in phagocytes

Cytosolic phospholipase A₂ (cPLA₂)–generated arachidonic acid (AA) has been shown to be an essential requirement for the activation of NADPH oxidase, in addition to its being the major enzyme involved in the formation of eicosanoid at the nuclear membranes. The mechanism by which cPLA₂ regulates NADPH oxidase activity is not known, particularly since the NADPH oxidase complex is localized in the plasma membranes of stimulated cells. The present study is the first to demonstrate that upon stimulation cPLA₂ is transiently recruited to the plasma membranes by a functional NADPH oxidase in neutrophils and in granulocyte-like PLB-985 cells. Coimmunoprecipitation experiments and double labeling immunofluorescence analysis demonstrated the unique colocalization of cPLA₂ and the NADPH oxidase in plasma membranes of stimulated cells, in correlation with the kinetic burst of superoxide production. A specific affinity in vitro binding was detected between GST-p47^phox or GST-p67^phox and cPLA₂ in lysates of stimulated cells. The association between these two enzymes provides the molecular basis for AA released by cPLA₂ to activate the assembled NADPH oxidase. The ability of cPLA₂ to regulate two different functions in the same cells (superoxide generation and eicosanoid production) is achieved by a novel dual subcellular localization of cPLA₂ to different targets.