Mechanisms regulating autophagy in alcohol-induced liver injury

University Of Kansas Medical Center, Kansas City KS

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Abstract

DESCRIPTION (provided by applicant): Autophagy is a genetically programmed, evolutionarily conserved process that degrades long-lived cellular proteins and damaged organelles, including mitochondria, as a critical cell survival mechanism in response to stress. We recently reported that ethanol induces autophagy, which reduces ethanol-induced liver injury (Ding et al., 2010a). This is an important finding because alcohol abuse is a major cause of liver disease and a major health problem in the United States. Oxidative stress and mitochondrial damage play important roles in alcohol-induced hepatotoxicity. Cells may protect themselves by removing damaged mitochondria by mechanisms such as autophagy. Therefore modulating the autophagy process could offer new therapeutic treatments for alcoholic liver diseases. However, the mechanisms by which ethanol induces autophagy and how autophagy protects against ethanol-induced liver pathogenesis are not clear. Without such understanding, the potential to ultimately use autophagy in the treatment of alcohol-related liver disease will be limited. Our preliminary studies suggest that the forkhead transcription factor FoxO3a could play a major role in ethanol- induced autophagy. Therefore, the central hypothesis is that ethanol induces autophagy by activating FoxO3a, and autophagic removal of ethanol-induced damaged mitochondria is crucial to protect against ethanol- induced liver pathogenesis. To examine our hypothesis, three specific aims are proposed: 1) determine the mechanisms by which ethanol activates FoxO3a in hepatocytes, 2) determine how ethanol-activated FoxO3a induces autophagy in hepatocytes, and 3) determine the mechanisms by which removal of damaged mitochondria protects against ethanol-induced hepatotoxicity. The research proposed in this application is innovative in the concept that ethanol can activate autophagy as a protective mechanism against its known detrimental effects on the liver. Moreover, we will utilize novel genetic animal models such as GFP-LC3 transgenic and Atg5 liver-specific knockout mice to specifically study the role of autophagy in alcohol-induced liver injury. Furthermore, it focuses on the role of FoxO3a-mediated autophagy pathway in alcoholic liver disease, which has not been studied. The proposed research is significant because the results from this study will lead to the understanding of mechanisms and roles of autophagy in alcohol-induced liver pathogenesis. Ultimately, such knowledge has the potential of offering novel therapeutic approaches for treating alcoholic liver pathogenesis by modulating autophagy.