Fas-mediated activation of phospholipase D is coupled to the stimulation of phosphatidylcholine-specific phospholipase C in A20 cells.
The activation of phospholipase D in murine B cell lymphoma A20 cells treated with anti-Fas monoclonal antibody has been investigated. Fas cross-linking resulted in a both dose- and time-dependent increases in phospholipase D activity. There was a nearly maximum saturated rise in phospholipase D activity at the dose of 200 ng/ml anti-Fas monoclonal antibody showing a fourfold increase within 3 h. Fas activation also caused an approximately twofold increase of phosphatidylcholine-specific phospholipase C activity and 1,2-diacylglycerol release, which could be blocked by 30 min pretreatment with the phosphatidylcholine-specific phospholipase C inhibitor D609 (50 microgram/ml). Pretreatment of D609 also effectively inhibited the translocation of protein kinase C betaI and betaII from the cytosol to the membrane and the activation of phospholipase D induced by Fas cross-linking, suggesting that 1, 2-diacylglycerol released from the cellular phosphatidylcholine pool through phosphatidylcholine-specific phospholipase C plays a major role in protein kinase C/phospholipase D activation. Anti-Fas monoclonal antibody failed to elicit phosphoinositide-specific phospholipase C activation and any changes in the intracellular Ca2+ level in A20 cells, indicating that the phosphoinositide-mediated pathway is not involved in this Fas signaling. Therefore, these results suggest that Fas-mediated phospholipase D activation may be a consequence of primary stimulation of phosphatidylcholine-specific phospholipase C and that phospholipase D may play a role in Fas cross-linking signaling downstream from phosphatidylcholine-specific phospholipase C.
College of Medicine, Hanyang University, Seoul, 133-791, Korea. jshan@email.hanyang.ac.kr
J S
JS
Han
B C
BC
Hyun
J H
JH
Kim
I
I
Shin
D000818:Animals; D001952:Bridged-Ring Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004306:Dose-Response Relationship, Immunologic; D051379:Mice; D009636:Norbornanes; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010739:Phospholipase D / Q000378:metabolism*; D010767:Phosphorylcholine / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000502:physiology*; D013859:Thiocarbamates; D013871:Thiones / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism*; D019014:fas Receptor
D001952:Bridged-Ring Compounds; D009636:Norbornanes; D010726:Phosphodiesterase Inhibitors; D018124:Receptors, Tumor Necrosis Factor; D013859:Thiocarbamates; D013871:Thiones; D019014:fas Receptor; D010767:Phosphorylcholine; C046498:tricyclodecane-9-yl-xanthogenate; D010738:Type C Phospholipases; C105598:phosphatidylcholine-specific phospholipase C; D010739:Phospholipase D; D002118:Calcium