Circular RNA RORβ regulates TGFBR1 by decoying miR-140 in alcohol-exposed lungs and fibroblasts

Alcohol ingestion exaggerates transforming growth factor-beta 1 (TGF{beta}1) expression and signaling leading to fibroproliferation. Inhibition of TGF{beta} receptor type 1 (TGF{beta}R1) mitigates the effect of TGF{beta}1 signaling. We showed that alcohol can modulate microRNA (miRNA) expressions. The mechanism by which alcohol modulates microRNA and how it ties to TGF{beta}1 signaling has not been well elucidated. Circular RNA (circRNAs or circ) emerges as a potential therapeutic target based on its stability, tissue specificity, and its ability to modify miRNAs. In this study, we showed that alcohol upregulates TGF{beta}R1 and circRNA form of retinoic acid receptor-related orphan receptor beta (circ-ROR{beta}) in lung fibroblasts (LF) and the lung. We identified miR-140 to have binding sites for both TGF{beta}R1 3 UTR and circ-ROR{beta} and alcohol attenuated miR-140 expression in LF and the lung. We demonstrated that inhibition of circ-ROR{beta} upregulated miR-140 and completely abrogated alcohol-induced miR-140 suppression. We further showed that inhibition of circ-ROR{beta} attenuated alcohol-induced TGF{beta}R1, fibronectin (FN1), and -smooth muscle actin (SMA) expressions and myofibroblast development as seen by an attenuation of SMA stress fiber formation in LF. Taken together, these findings identify circ-ROR{beta}-miR-140-TGF{beta}R1 axis as a novel mechanism by which alcohol induces TGF{beta}1 signaling and promotes FMD. HighlightsAlcohol induces circ-ROR{beta} expression in lung fibroblasts Circ-ROR{beta} regulates TGF{beta}R1 by decoying miR-140 in lung fibroblasts Inhibition of Circ-ROR{beta} restores miR-140 expression Inhibition of Circ-ROR{beta} mitigates alcohol-mediated myofibroblast differentiation This is the first description of circ-ROR{beta} functional significance in lung fibroblast