Characterization of the lipolytic pathways that mediate free fatty acid release during Fas/CD95-induced apoptosis.
We have undertaken a study to characterize the lipolytic pathway responsible for the generation of free fatty acids (FFA) during Fas/CD95-induced apoptosis in Jurkat cells. It was initially shown that the cellular lipid fraction that suffered the major quantitative decrease during Fas-induced apoptosis was that of phosphatidylcholine (PC). In addition, the secretion of palmitic acid-derived FFA was largely prevented by D609, an inhibitor of PC-specific phospholipase C (PC-PLC) and also by the diacylglycerol lipase (DAGL) inhibitor RHC-80267, suggesting that the secretion of these FFA during Fas-induced apoptosis is mediated by the generation of DAG by a PC-PLC activity and, sequentially, by a 1-DAGL activity which generates the FFA from its sn-1 position. The endocannabinoid 2-arachidonoyl glycerol (2-AG) should be generated as a sub-product of this pathway, but it did not accumulate inside the cells nor was secreted into the supernatant. Interestingly, the complete inhibition of free AA secretion during Fas-induced apoptosis was only achieved by using the AA trifluoromethylketone, which not only inhibits all types of phospholipase-A(2) (PLA(2)) activities, but also the described lytic activities on 2-AG. Using a combination of RHC-80267 and the iPLA(2)-specific inhibitor bromoenol lactone, it was shown that the DAGL pathway also cooperates with iPLA(2) in the generation of free arachidonate.
Iturralde
M
M
Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, 50009 Spain.
Pardo
J
J
Lacasa
E
E
Barrio
G
G
Alava
M A
MA
Piñeiro
A
A
Naval
J
J
Anel
A
A
D017209:Apoptosis / Q000187:drug effects; D001095:Arachidonic Acids / Q000494:pharmacology; D001952:Bridged-Ring Compounds / Q000494:pharmacology; D003512:Cyclohexanones / Q000494:pharmacology; D063388:Endocannabinoids; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005989:Glycerides / Q000494:pharmacology; D006801:Humans; D019169:Jurkat Cells; D007659:Ketones / Q000494:pharmacology; D050356:Lipid Metabolism / Q000187:drug effects; D008066:Lipolysis / Q000187:drug effects; D008071:Lipoprotein Lipase / Q000037:antagonists & inhibitors; D008954:Models, Biological; D009636:Norbornanes; D019308:Palmitic Acid / Q000494:pharmacology; D010712:Phosphatidic Acids / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism; D013859:Thiocarbamates; D013871:Thiones / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D019014:fas Receptor / Q000378:metabolism*
C480312:11-hexadecenyl trifluoromethyl ketone; D001095:Arachidonic Acids; D001952:Bridged-Ring Compounds; D003512:Cyclohexanones; D063388:Endocannabinoids; D004791:Enzyme Inhibitors; D005230:Fatty Acids, Nonesterified; D005989:Glycerides; D007659:Ketones; D009636:Norbornanes; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D013859:Thiocarbamates; D013871:Thiones; D019014:fas Receptor; D019308:Palmitic Acid; C046498:tricyclodecane-9-yl-xanthogenate; C036535:1,6-bis(cyclohexyloximinocarbonyl)hexane; C094503:glyceryl 2-arachidonate; D008071:Lipoprotein Lipase; D010738:Type C Phospholipases