CCAAT/enhancer binding protein binds and activates the promoter of the rat class I alcohol dehydrogenase gene

CCAAT/enhancer binding protein (C/EBP), a DNA binding protein originally isolated from rat liver, activates the transcription of a number of liver-specific genes. We studied the effect of C/EBP on the transcription of the rat class I alcohol dehydrogenase gene. Purified C/EBP was shown to bind to a segment of the rat class I alcohol dehydrogenase gene promoter between position -10 and -22. Nuclear extracts isolated from rat liver contained a heat stable factor(s) that also bound to this sequence. Cotransfection experiments in HepG2 cells showed transactivation of alcohol dehydrogenase promoter-CAT fusion constructs by an expression vector containing wild-type C/EBP. Expression vector containing a mutated C/EBP that failed to bind DNA also failed to activate the promoter. These experiments demonstrate that C/EBP expression can activate the rat class I alcohol dehydrogenase gene promoter.