Gene-selective histone H3 acetylation in the absence of increase in global histone acetylation in liver of rats chronically fed alcohol.

AIMS

The aim of this study was to determine the effect of chronic ethanol feeding on acetylation of histone H3 at lysine 9 (H3-Lys9) at promoter and coding regions of genes for class I alcohol dehydrogenase (ADH I), inducible nitric oxide synthase (iNOS), Bax, p21, c-met and hepatocyte growth factor in the rat liver.

METHODS

Rats were fed ethanol-containing liquid diet (5%, w/v) for 1-4 weeks. The global level of acetylation of H3-Lys9 in the liver was examined by western blot analysis. The levels of mRNA for various genes were measured by real-time reverse transcriptase-polymerase chain reaction. The association of acetylated histone H3-Lys9 with the different regions of genes was monitored by chromatin immunoprecipitation assay.

RESULTS

Chronic ethanol treatment increased mRNA expression of genes for iNOS, c-jun and ADH 1. Chronic ethanol treatment did not cause increase in global acetylation of H3-Lys9, but significantly increased the association of acetylated histone H3-Lys9 in the ADH I gene, both in promoter and in coding regions. In contrast, chronic ethanol treatment did not significantly increase the association of acetylated histone H3-Lys9 with iNOS and c-jun genes.

CONCLUSION

Chronic ethanol exposure increased the gene-selective association of acetylated H3-Lys9 in the absence of global histone acetylation. Thus, not all genes expressed by ethanol are linked to transcription via histone H3 acetylation at Lys9.