Regulation and Consequences of Cytochrome P450 2E1

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PROJECT SUMMARY Cytochrome P450 2E1 (CYP2E1) is a unique, highly conserved, and highly regulated mammalian P450 monooxygenase. CYP2E1 undergoes extensive post-transcriptional and post-translational regulation, including bimodal targeting to endoplasmic reticulum and mitochondria. There are no known loss of function mutations in the human population, and no known polymorphic variants that change the coding region of the protein, indicating an important endogenous role for CYP2E1. However, knockout of CYP2E1 in rodent models has not yielded a dramatic phenotype, and has been reported to be protective against diet-induced obesity, nonalcoholic fatty liver disease, and ethanol-induced toxicity. Therapeutic targeting of CYP2E1 has been recommended for liver repair after alcoholic liver damage and to improve the efficacy of a ketogenic diet for the treatment of epilepsy. However, there remain major gaps in our understanding of the endogenous function of CYP2E1 that must be addressed before CYP2E1 can be safely inhibited in humans, particularly in the long- term. This proposal addresses these challenges using the expertise of the Hartman lab, resources and reagents we have generated to study CYP2E1, and the expertise of our collaborators. The overall goal of the research program is to discover the endogenous function and regulation of CYP2E1 and the consequences of CYP2E1 activity in mitochondria and endoplasmic reticulum. Overview of research and goals for the next five years: The Hartman Lab opened at MUSC during the beginning of the pandemic. It pursues key questions like: How does the cell decide how much CYP2E1 to send to mitochondria vs. the endoplasmic reticulum? Mechanisms of nascent polypeptide targeting will be determined through genetic and pharmacological approaches. What are the endogenous functions of CYP2E1 in multiple tissues? CYP2E1 is known to metabolize acetone to acetol and methylglyoxal, and to hydroxylate fatty acids at the omega and omega-1 position, but these activities have not been studied in the context of overall cellular metabolism and have generally only focused on liver. We are investigating the tissue-specific endogenous functions in multiple tissues. What are the consequences of CYP2E1 expression in mitochondria and endoplasmic reticulum? Emerging evidence in our lab suggests that for ethanol and acetaminophen, mitochondrial CYP2E1 is a liability for drug-induced cellular damage, but for fatty acids, endoplasmic reticular CYP2E1 drives lipid stress. Therefore, there are organelle-specific liabilities that must be further defined. Together this work will address arising and long-standing fundamental questions about CYP2E1.