Alcoholic liver disease (ALD) is a prominent source of morbidity and mortality in the United States. ALD is a progressive disease encompassing hepatic steatosis, steatohepatitis, fibrosis and cirrhosis. It is now widely accepted the molecular mechanisms underlying ALD are multifactorial including compromised antioxidant systems resulting in overproduction of reactive oxidant species having the potential to damage hepatocellular lipids, proteins and nucleic acids. The oxidant-mediated modification of lipids and the resulting modification of proteins critical for hepatocellular homeostasis are important mechanistic events contributing to initiation and/or progression of ALD. The general working hypothesis underlying the proposed experiments is that protein modification occurring as a consequence of lipid peroxidation plays a significant role in the pathogenesis of ALD. During the previous funding period, significant progress has been made in the development of state-of-the-art proteomic approaches for isolating, identifying and functionally characterizing proteins modified by the lipid peroxidative products 4-hydroxynonenal (4-HNE) and 4-oxononenal. These proteomic approaches will be used to test this hypothesis in the following three specific aims: Experiments in Aim 1 will characterize the functional consequences of 4-HNE modification on proteins targets previously identified including urea cycle enzymes, F0F1 ATPase and ER stress proteins. Studies proposed in Aim 2 will identify the 4-HNE- and 4-ONE-modified proteome in the Total Enteral Nutrition (TEN) model of alcohol-induced steatosis, steatohepatitis or fibrosis to identify protein modifications that are mechanistically involved in these progressive stages of ALD. These studies will employ administration of the hepatoprotectant N-acetylcysteine to identify changes in the 4-HNE or 4-ONE-modified proteomes responsive to this antioxidant. Experiments proposed in Aim 3 will employ this same animal model to characterize the production and cytotoxicity of autoantibodies against 4-HNE and 4-ONE-modified host proteins during ALD characterized by steatosis, steatohepatitis and fibrosis. Experiments proposed in conjunction with this aim use immunoisolation techniques and LC-MS/MS mass spectrometry to identify the specific host proteins which function as autoantigens. Collectively, the mechanistic information derived from these experiments will provide new insight into novel therapeutic strategies to attenuate and or reverse ALD. 7. Project Narrative: The mechanisms by which chronic ethanol ingestion damages the liver are multiple and interactive. The advancement in our knowledge of this disease will evolve from systematic investigations of individual mechanisms which contribute to this complex and progressive disease. It is now clear that oxidative stress is an important component of ALD. Lipid peroxidation is one consequence of oxidative stress resulting in the production of products lipid aldehydes such as 4-HNE and 4-ONE that are important factors in liver injury associated with ALD. The overall goal of this renewal application is to extend our investigation of the mechanisms by which these endogenous compounds are involved in the pathophysiology of early (steatosis) inflammatory (steatohepatitis) as well as late stages of ALD, including fibrosis. Public Health Relevance: The cytochromes P450 are a large superfamily of proteins that in humans are responsible for oxidizing a vast array of compounds, including many endogenous compounds such as steroids, bile acids, vitamins, and xenobiotics such as drugs, anesthetics, solvents, and compounds in our diet. The proposed research will lead to a better understanding of how these enzymes function, especially with their redox partners, cytochrome b5 and cytochrome P450 reductase.

National Institute of Health (NIH)
National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Method to Extend Research in Time (MERIT) Award (R37)
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Special Emphasis Panel (ZRG1-DIG-F (02))
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Radaeva, Svetlana
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University of Colorado Denver
Schools of Pharmacy
United States
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Shearn, Colin T; Fritz, Kristofer S; Shearn, Alisabeth H et al. (2016) Deletion of GSTA4-4 results in increased mitochondrial post-translational modification of proteins by reactive aldehydes following chronic ethanol consumption in mice. Redox Biol 7:68-77
Shearn, Colin T; Orlicky, David J; McCullough, Rebecca L et al. (2016) Liver-Specific Deletion of Phosphatase and Tensin Homolog Deleted on Chromosome 10 Significantly Ameliorates Chronic EtOH-Induced Increases in Hepatocellular Damage. PLoS One 11:e0154152
Ronis, Martin J J; Mercer, Kelly E; Gannon, Brenda et al. (2015) Increased 4-hydroxynonenal protein adducts in male GSTA4-4/PPAR-α double knockout mice enhance injury during early stages of alcoholic liver disease. Am J Physiol Gastrointest Liver Physiol 308:G403-15
Shearn, C T; Orlicky, D J; Saba, L M et al. (2015) Increased hepatocellular protein carbonylation in human end-stage alcoholic cirrhosis. Free Radic Biol Med 89:1144-53
Caro, Andres A; Bell, Matthew; Ejiofor, Shannon et al. (2014) N-acetylcysteine inhibits the up-regulation of mitochondrial biogenesis genes in livers from rats fed ethanol chronically. Alcohol Clin Exp Res 38:2896-906
Shearn, Colin T; Backos, Donald S; Orlicky, David J et al. (2014) Identification of 5' AMP-activated kinase as a target of reactive aldehydes during chronic ingestion of high concentrations of ethanol. J Biol Chem 289:15449-62
Galligan, James J; Fritz, Kristofer S; Backos, Donald S et al. (2014) Oxidative stress-mediated aldehyde adduction of GRP78 in a mouse model of alcoholic liver disease: functional independence of ATPase activity and chaperone function. Free Radic Biol Med 73:411-20
Shearn, Colin T; Mercer, Kelly E; Orlicky, David J et al. (2014) Short term feeding of a high fat diet exerts an additive effect on hepatocellular damage and steatosis in liver-specific PTEN knockout mice. PLoS One 9:e96553
Smathers, Rebecca L; Galligan, James J; Shearn, Colin T et al. (2013) Susceptibility of L-FABP-/- mice to oxidative stress in early-stage alcoholic liver. J Lipid Res 54:1335-45
Shearn, C T; Smathers, R L; Backos, D S et al. (2013) Increased carbonylation of the lipid phosphatase PTEN contributes to Akt2 activation in a murine model of early alcohol-induced steatosis. Free Radic Biol Med 65:680-92

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