Increasing evidence indicates that complex interactions of multiple genetic, epigenetic and environmental factors contribute too many human diseases, including alcohol-induced liver disease (ALD). The metabolic processes resulting from alcohol metabolism can affect epigenetic events by altering the energy balance in the cell, changing hepatic methionine metabolism, and invoking a state of oxidative stress in the liver. It is our hypothesis that a mechanistic link exists between liver oxidative stress and DNA damage caused by alcohol exposure and the epigenetic regulation of gene expression, which is modulated by genetic variation among individuals with different susceptibilities to ALD. In Aim 1, we will identify epigenetically-regulated genes associated with ALD. Inbred mouse strains sensitive or resistant to alcohol-induced liver injury will be studied to test the hypothesis that liver injury is associated with epigenetic changes caused by alcohol in specific genes, which can be modulated by genetic background. Both whole genome and gene-specific methylation assays will be employed to identify genes that are likely to be differentially expressed and affected by changes in methylation following alcohol treatment. These studies will determine if both genetic and epigenetic mechanisms are controlling the outcome of alcohol toxicity. In Aim 2, we will quantify the relationship between oxidative stress and epigenetic marks associated with ALD. We hypothesize that epigenetic changes caused by alcohol exposure are related to oxidative stress and DNA damage in liver, which can be modulated by genetic variation in anti-oxidant defenses. We will characterize the inter-strain diversity in oxidative stress and DNA methylation phenotypes to establish whether oxidative stress-induced cellular events modulate epigenetic processes and tissue injury within the liver resulting from alcohol exposure. In Aim 3, we will determine whether changes in DNA methylation are required for ALD. The importance of the gene-specific DNA methylation patterns associated with liver injury identified in Aim 1 will be tested by nutritionally modulating methyl donor capacity in a mouse strain sensitive to ALD and the effect of altered DNA methylation on alcohol-induced liver injury will be studied. This will establish whether a causative link exists between gene-specific DNA methylation patterns and liver injury due to alcohol. Collectively, these studies will identify and characterize genetic and epigenetic mechanisms that influence ALD and the potential mechanisms by which alcohol-induced changes in oxidative stress alter gene expression to cause liver injury.