miR-29c promotes alcohol dehydrogenase gene cluster expression by activating the enhancer within ADH6

Alcohol dehydrogenases (ADHs) play vital roles in alcohol metabolism and alcohol toxicity, yet little is known about miRNA-mediated regulation of ADH gene cluster. Here, we showed that miR-29c might activate ADH gene cluster transcription by targeting an enhancer element within ADH6 gene. miR-29c is differentially expressed in alcoholic liver disease. Following biochemical and molecular evidences demonstrated that miR-29c could increase ADH6 mRNA and protein levels without affecting the stability of ADH6 transcript. Further evidence showed that exogenous miR-29c could move into the nucleus and then unconventionally bound an enhancer element within ADH6 gene. Luciferase reporter assay and chromatin immunoprecipitation data indicated that miR-29c could activate the enhancer and increase the enrichment of RNA Polymerase II at the promoter region of ADH1A , ADH1B , ADH1C , ADH4 , and ADH6 . Finally, exogenous miR-29c transfection promoted the expressions of ADH1A , ADH1B , ADH1C , and ADH4 pre-mRNA and mRNA transcripts in the ADH gene cluster. In conclusion, our data suggest that miR-29c might represent as a novel epigenetic regulator involved in ADH gene cluster activation.