Alcoholic liver disease (ALD) is a major cause of liver related morbidity and mortality; however treatment options are currently limited due to an incomplete understanding of the molecular drivers of ALD pathogenesis. Insulin resistance is one of the few known factors linked with ALD progression and dysregulated lipid synthesis is linked with the development of insulin resistance in experimental models. Our experimental mouse alcohol feeding model reveals hepatic steatosis (the earliest histologic stage of ALD) and insulin resistance develop coordinate with the upregulation of the hepatic lipid droplet protein Perilipin 2 (Plin2) and an increase in liver ceramides, both of which are known to promote steatosis and insulin resistance. Consistent with a functional role for Plin2 in alcoholic steatosi, we found that alcohol-fed Plin2 KO mice were resistant to steatosis, increases in liver ceramides and glucose intolerance. While the regulators of Plin2 in alcoholic steatosis are unknown, our preliminary results show the cellular energy regulator AMP-activated protein kinase (AMPK) is downregulated in alcohol-fed mice prior to Plin2 elevation and pharmacologic AMPK activation reduces Plin2 transcription in ethanol-treated VL-17A human hepatoma cells. Additionally, in vitro and in vivo studies suggest pharmacological blockade of ceramide synthesis elevates Plin2 levels. Based on these data, we hypothesize that there is positive feedback between hepatic Plin2 and ceramides and that alcohol's inhibition of AMPK regulates this process. We will investigate our hypothesis through three interrelated Specific Aims: (1) Specific Aim 1: To investigate the mechanistic basis of AMPK mediated regulation of Plin2 transcription in vitro using ethanol-treated human hepatoma cells. (2) To investigate the effect of hepatic AMPK activation and inhibition on Plin2, ceramides and lipid metabolism in vivo; and (3) To determine the effect of hepatic ceramide reduction on Plin2 expression and lipid metabolism. To accomplish these Specific Aims, we will use a combination of novel genetic, molecular biology and pharmacological approaches; lipidomics analyses; and metabolic phenotyping to understand the in vivo functional consequences of our models. Successful accomplishment of these Specific Aims will advance our understanding of the contribution of lipids and associated proteins per se to alcohol liver pathology and can provide insight into early targets for therapeutic intervention. Concurrently with performing the experimental aims, I will complete a career development program under the guidance of an advisory committee with nationally and internationally recognized NIH-funded researchers from the University of Pennsylvania and Thomas Jefferson University. This structured program combined with my co-mentors' clinical experience in hepatology and gastroenterology make me uniquely positioned to become a leading investigator capable of NIH-funded independent investigation at a leading academic center with a research focus on alcohol-mediated lipid biology.
Alcoholic liver disease (ALD) is a major cause of liver related mortality, however much remains to be learned about the underlying causes. This application is designed to identify new therapeutic targets using innovative experimental strategies to identify how alcohol alters lipid metabolism to promote disease progression.
| Correnti, Jason M; Gottshall, Lauren; Lin, Annie et al. (2018) Ethanol and C2 ceramide activate fatty acid oxidation in human hepatoma cells. Sci Rep 8:12923 |
| Williams, Bianca; Correnti, Jason; Oranu, Amanke et al. (2018) A novel role for ceramide synthase 6 in mouse and human alcoholic steatosis. FASEB J 32:130-142 |
