Hepatocyte Metabolic Stress Response to Alcoholic Fatty Liver - Abstract Alcoholic liver disease (ALD) is one of the most prevalent chronic liver diseases, accounting for more than half-million deaths worldwide each year. To date, there exist no effective medical interventions; thereby, posing a serious threat to public health. ALD represents a broad-spectrum hepatic disorder from alcoholic fatty liver (AFL), alcoholic steatohepatitis (ASH) to cirrhosis, the development of which is largely determined by the duration, quantity, and pattern of substance abuse. AFL, the 1st stage of ALD, is characterized by the massive accumulation of macrovesicular lipid droplets in hepatocytes without histological features of inflammation. AFL develops as soon as 2 weeks of alcohol abuse and can also undergo a rapid and complete resolution upon abstinence. However, if abstinence cannot be achieved, AFL, in turn, serves as the foundation for the development of advanced stages of ALD such as ASH and cirrhosis, which are associated with extremely high mortality and morbidity rate as well as poor reversibility even with long-term abstinence. With the opportunity to efficiently mitigate the disease burden of ALD, AFL represents an attractive therapeutic target. To this end, furthering our understanding of AFL pathophysiology serves as a critical milestone. In this study, we established a novel in vitro study model of AFL with a highly physiological culture system of terminally differentiated human hepatocyte (HH), then applied for the elucidation of hepatocyte-intrinsic response to the metabolic stress inflicted by AFL. Cellular response to metabolic stress is a coordinated adaptation process obligatory for homeostatic maintenance; thus, the failure leads to cell injury. While the induction of transcriptome changes is an undoubtedly important process in stress response, the synthesis of respective proteins is ultimately required to execute the designated gene functions. Consequently, we conducted an integrative analysis of polysome profiling and mRNA-sequencing to elucidate the concordance between transcriptome change and mRNAs translated by ribosomes. Our analysis revealed that AFL induces a significant dysregulation of translatome, suggesting that the transcriptome change is discordantly processed at the protein translation machinery. This observation led to our hypothesis that “AFL dysregulation of translatome results in a global alteration of the proteome, which acts in concert to impair the stress response and leads to the cytotoxicity.” Accordingly, this exploratory proposal is designed to elucidate the mechanism and significance of translatome alteration as the critical pathophysiology of AFL through the following specific aims: Aim 1: Determine the molecular mechanism of dysregulated translatome in HH of AFL, and Aim 2: Define the correlation between transcriptome, translatome and quantitative proteomics of AFL HH. The successful completion of the proposed studies will provide unique and novel insights on AFL pathophysiology and a framework for further investigation with in vivo models as well as translational studies involving clinical specimens.
