Protein kinase C-independent pathway for NADPH oxidase activation in guinea pig peritoneal polymorphonuclear leukocytes by cytochalasin D

Cytochalasin D (CD) induced production of the superoxide radical (O2−) in guinea pig polymorphonuclear leukocytes (PMNs). The protein kinase C (PKC) inhibitor GF109203X (GFX) was rarely without effect on CD-induced O2− production. CD as well as PMA induced the translocation of p47phox to the membrane fraction, and this translocation was slightly decreased by GFX. Moreover, the inhibitory effect of a PKCζ antagonist with sequences based on the endogenous PKCζ pseudosubstrate region was weaker than the inhibitory effect on N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced O2− production. On the other hand, the production of O2− induced by CD was more strongly suppressed by the PLD inhibitor ethanol and phosphatidylinositol 3-kinase (PI3-K) inhibitor wortmannin than that induced by fMLP, and the activation of phospholipase D (PLD) by CD was restrained by wortmannin. These findings suggest that NADPH oxidase is activated by CD through a PKC-independent signaling pathway in PMNs, and this pathway involves the activation of PLD through PI3-K.