Group X secretory phospholipase A 2 can induce arachidonic acid release and eicosanoid production without activation of cytosolic phospholipase A 2 alpha

Abstract

Group X secretory phospholipase A 2 (sPLA 2-X) and cytosolic phospholipase A 2 alpha (cPLA 2α) are involved in the release of arachidonic acid (AA) from membrane phospholipids linked to the eicosanoid production in various pathological states. Recent studies have indicated the presence of various types of cross-talk between sPLA 2s and cPLA 2α resulting in effective AA release. Here we examined the dependence of sPLA 2-X-induced potent AA release on the cPLA 2α activation by using specific cPLA 2α or sPLA 2 inhibitors as well as cPLA 2α-deficient mice. We found that Pyrrophenone, a cPLA 2α-specific inhibitor, did not suppress the sPLA 2-X-induced potent AA release and prostaglandin E 2 formation in mouse spleen cells. Furthermore, the amount of AA released by sPLA 2-X from spleen cells was not significantly altered by cPLA 2α deficiency. These results suggest that sPLA 2-X induces potent AA release without activation of cPLA 2α, which might be relevant to eicosanoid production in some pathological states where cPLA 2α is not activated.