Fatty acid amide hydrolase determines anandamide-induced cell death in the liver.
The endocannabinoid anandamide (AEA) induces cell death in many cell types, but determinants of AEA-induced cell death remain unknown. In this study, we investigated the role of the AEA-degrading enzyme fatty acid amide hydrolase (FAAH) in AEA-induced cell death in the liver. Primary hepatocytes expressed high levels of FAAH and were completely resistant to AEA-induced cell death, whereas primary hepatic stellate cells (HSCs) expressed low levels of FAAH and were highly sensitive to AEA-induced cell death. Hepatocytes that were pretreated or with the FAAH inhibitor URB597 isolated from FAAH(-/-) mice displayed increased AEA-induced reactive oxygen species (ROS) formation and were susceptible to AEA-mediated death. Conversely, overexpression of FAAH in HSCs prevented AEA-induced death. Since FAAH inhibition conferred only partial AEA sensitivity in hepatocytes, we analyzed additional factors that might regulate AEA-induced death. Hepatocytes contained significantly higher levels of glutathione (GSH) than HSCs. Glutathione depletion by dl-buthionine-(S,R)-sulfoximine rendered hepatocytes susceptible to AEA-mediated ROS production and cell death, whereas GSH ethyl ester prevented ROS production and cell death in HSCs. FAAH inhibition and GSH depletion had additive effects on AEA-mediated hepatocyte cell death resulting in almost 70% death after 24 h at 50 microm AEA and lowering the threshold for cell death to 500 nm. Following bile duct ligation, FAAH(-/-) mice displayed increased hepatocellular injury, suggesting that FAAH protects hepatocytes from AEA-induced cell death in vivo. In conclusion, FAAH and GSH are determinants of AEA-mediated cell death in the liver.
Siegmund
Sören V
SV
Department of Medicine, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA.
Seki
Ekihiro
E
Osawa
Yosuke
Y
Uchinami
Hiroshi
H
Cravatt
Benjamin F
BF
Schwabe
Robert F
RF
D000256:Adenoviridae / Q000235:genetics; D000581:Amidohydrolases / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D001095:Arachidonic Acids / Q000494:pharmacology*; D001652:Bile Ducts / Q000473:pathology; D015153:Blotting, Western; D002121:Calcium Channel Blockers / Q000494:pharmacology; D016923:Cell Death; D004305:Dose-Response Relationship, Drug; D063388:Endocannabinoids; D050612:Fatty Acid Transport Proteins / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D022781:Hepatocytes / Q000378:metabolism; D050356:Lipid Metabolism; D008099:Liver / Q000187:drug effects* / Q000201:enzymology* / Q000293:injuries / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009336:Necrosis; D053284:Polyunsaturated Alkamides; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D000099252:Fatty Acid Amide Hydrolases
D000581:Amidohydrolases; D001095:Arachidonic Acids; D002121:Calcium Channel Blockers; D063388:Endocannabinoids; D050612:Fatty Acid Transport Proteins; D005978:Glutathione; D053284:Polyunsaturated Alkamides; D017382:Reactive Oxygen Species; D000099252:Fatty Acid Amide Hydrolases; C078814:anandamide