Ethanol induction of class I alcohol dehydrogenase expression in the rat occurs through alterations in CCAAT/enhancer binding proteins β and γ

Ling He, Martin J.J. Ronis, Thomas M. Badger

Research output: Contribution to journalArticlepeer-review

Abstract

Alcohol dehydrogenase (ADH) is the principal ethanol-metabolizing enzyme. Ethanol induces rat Class I ADH mRNA and activity by an as yet unknown mechanism. In the current study, adult male rats were fed an ethanol-containing diet by continuous intragastric infusion for 42 days. Hepatic Class I ADH mRNA, protein, and activity levels in the ethanol-infused rats increased 3.9-, 3.3-, and 1.7-fold, respectively (p <0.05). Cis-acting elements within the proximal promoter region of the ADH gene were studied by electrophoretic mobility shift assay (EMSA). Hepatic nuclear extract (HNE) binding to either the consensus or ADH-specific CCAAT/enhancer binding protein (C/EBP) sites was >2.4-fold greater in ethanol-fed rats (p <0.05) than controls. Antibody-specific EMSA assays demonstrated binding of the transcription factor C/EBPβ to the C/EBP site. Western blot immunoblot analysis of HNEs demonstrated 3.5- and 2.3-fold increases in C/EBPβ (LAP) and C/EBPδ (p <0.05), respectively, in ethanol-fed rats compared with controls, whereas levels of the truncated C/EBPβ (LIP) and C/EBPγ were lower in ethanol-fed rats (p <0.05). HNE from ethanol-fed rats increased (3-fold) the in vitro transcription of rat Class I ADH (p <0.05), and mutation of the C/EBP element in the proximal promoter region blocked this effect. Antisera against LIP or C/EBPγ enhanced transcription efficiency (p <0.05). These data provide the first evidence for the mechanism by which ethanol regulates rat hepatic Class I ADH gene expression in vivo. This mechanism involves the C/EBP site and the enhancer binding proteins β and γ.

Original languageEnglish (US)
Pages (from-to)43572-43577
Number of pages6
JournalJournal of Biological Chemistry
Volume277
Issue number46
DOIs
StatePublished - Nov 15 2002
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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