Ceramide does not inhibit protein kinase C beta-dependent phospholipase D activity stimulated by anti-Fas monoclonal antibody in A20 cells

We have investigated the roles of ceramide in Fas signalling leading to pho spholipase D (PLD) activation in A20 cells. Upon stimulation of Fas signall ing by anti-Fas monoclonal antibody, sphingomyelin hydrolysis and activatio n of PLD were induced. Also, the translocation of protein kinase C (PKC) be taI and beta II and the elevation of diacylglycerol (DAG) content were indu ced by Fas cross-linking. When phosphatidylcholine-specific phospholipase C (PC-PLC) was inhibited by D609, the Fas-induced changes in PLD activity, D AG content, and PKC translocation were inhibited. In contrast, D609 had no effect on Fas-induced alterations in sphingolipid metabolism, suggesting th at changes in ceramide content do not account for Fas-induced PLD activatio n. Furthermore, CG-ceramide had no effect on Fas-induced PLD activation and PKC translocation. Taken together, these data might suggest that ceramide generated by Fas cross-linking does not affect PKC P-dependent PLD activity stimulated by anti-Fas monoclonal antibody in A20 cells. (C) 2000 Elsevier Science Inc. All rights reserved.