Abstract
Acute liver failure is a serious clinical problem of which the underlying pathogenesis remains unclear and for which effective therapies are lacking. The Fas receptor/ligand system, which is negatively regulated by AKT, is known to play a prominent role in hepatocytic cell death. We hypothesized that AKT activation may represent a strategy to alleviate Fas-induced fulminant liver failure. We report here that a novel AKT activator, SC79, protects hepatocytes from apoptosis induced by agonistic anti-Fas antibody CH11 (for humans) or Jo2 (for mice) and significantly prolongs the survival of mice given a lethal dose of Jo2. Under Fas-signaling stimulation, SC79 inhibited Fas aggregation, prevented the recruitment of the adaptor molecule Fas-associated death domain (FADD) and procaspase-8 [or FADD-like IL-1β-converting enzyme (FLICE)] into the death-inducing signaling complex (DISC), but SC79 enhanced the recruitment of the long and short isoforms of cellular FLICE-inhibitory protein at the DISC. All of the SC79-induced hepatoprotective and DISC-interruptive effects were confirmed to have been reversed by the Akt inhibitor LY294002. These results strongly indicate that SC79 protects hepatocytes from Fas-induced fatal hepatic apoptosis. The potent alleviation of Fas-mediated hepatotoxicity by the relatively safe drug SC79 highlights the potential of our findings for immediate hepatoprotective translation.