IMR Press / FBL / Volume 4 / Issue 1 / DOI: 10.2741/gouillon

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Article
Role of CYP2E1 in the pathogenesis of alcoholic liver disease: modifications by cAMP and ubiquitin-proteasome pathway
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1 Department of Pathology, Harbor-UCLA Medical Center, Torrance, CA 90509, USA
2 Miyamoto Medical Clinic, Kanagawa, Japan
3 University of Nebraska and VA Medical Center, Omaha, NE
4 Department of Biochemistry, University of Nevada, Reno, NE
5 Institute of Environmental Medicine, Division of Molecular Toxicology, Karolinska Institute 17177, Stockholm, Sweden
Front. Biosci. (Landmark Ed) 1999, 4(1), 16–25; https://doi.org/10.2741/gouillon
Published: 1 September 1999
Abstract

The ethanol inducible isoform of cytochrome P450, CYP2E1, may play a role in ethanol-induced liver injury. Therefore, the factors which govern CYP2E1 degradation and turnover were investigated. These factors include cAMP, ubiquitin, proteasomal enzymes and CYP2E1 mRNA. Rats fed ethanol or pair-fed isocaloric dextrose were pair-fed with rats fed ethanol or dextrose treated with cAMP for 2 months. The liver pathology, regenerative activity, fatty acid composition, NFkappaB activation, ubiquitin conjugates and proteasomal enzymes were measured as were the apoprotein levels of CYP2E1, CYP3A, CYP4A and mRNA levels for CYP2E1 and ubiquitin expression. The results showed, that the cAMP treatment ameliorated the increase liver fat storage and changes in the fatty acid composition in the livers of ethanol fed rats. Other histologic features of alcoholic liver disease were not changed. Western blot quantitation showed that the amount of ubiquitin and ubiquitin conjugates were markedly reduced by ethanol treatment. Similarly, ethanol decreased the level of ubiquitin mRNA. cAMP ameliorated the inhibition of the proteasomal enzyme proteolysis caused by ethanol feeding. The ethanol-induced increase in the CYP2E1 protein was partially inhibited by cAMP treatment. cAMP treatment decreased CYP2E1 mRNA levels in both ethanol-fed and pair fed control rats. Likewise NFkappaB activation was not increased by ethanol but cAMP reduced the level of NFkappaB activation. CAMP treatment also reduced CYP4A but not CYP3A. The results support the concept that cAMP treatment partially protects the liver from ethanol-induced fatty liver by reducing CYP2E1 induction through cAMP's effects on CYP2E1 synthesis.

Keywords
Ubiquitin mRNA
CYP2E1 mRNA
26S Proteasome
Peptidases
Alcohol
Hyperplasia
cAMP
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