Alcohol induces TGFβ1 via downregulation of miR-1946a in murine lung fibroblast

Exaggerated transforming growth factor-beta 1 (TGF beta 1) expression worsens fibroproliferation following bleomycin-induced lung injury in alcohol-fed mice. MicroRNA (miR)-1946a is predicted to bind to the TGF beta 1 3' untranslated region (UTR), thereby inhibiting its transcription. We hypothesize that alcohol suppresses miR-1946a and induces TGF beta 1. Primary murine lung fibroblasts (PLFs) were cultured +/- alcohol, miR-1946a mimic or inhibitor, and TGF beta 1 signaling inhibitors. miR-1946a was analyzed after alcohol treatment in vitro and in vivo. TGF beta 1 expression and TGF beta 1 3'UTR-luciferase activity was quantified. We showed that alcohol suppressed miR-1946a in the alcohol-fed mouse lungs and PLFs. MiR-1946a inhibitor increased TGF beta 1 expression in the fibroblast. MiR-1946a mimic treatment suppressed TGF beta 1 gene expression and TGF beta 1 3'UTR activity. Overexpression of miR1946a inhibited alcohol-induced TGF beta 1 gene and protein expression as well as alcohol-induced TGF beta 1 and a-smooth muscle actin (SMA) protein expression in PLFs. In conclusion, miR-1946a modulates TGF beta 1 expression through direct interaction with TGF beta 1 3'UTR. These findings identify a novel mechanism by which alcohol induces TGF beta 1 in the lung.