MicroRNA-101 suppresses liver fibrosis by targeting the TGFβ signalling pathway

Transforming growth factor-beta (TGF beta) is crucial for liver fibrogenesis and the blunting of TGF beta signalling in hepatic stellate cells (HSCs) or hepatocytes can effectively inhibit liver fibrosis. microRNAs (miRNAs) have emerged as key regulators in modulating TGF beta signalling and liver fibrogenesis. However, the regulation of TGF beta receptor I (T beta RI) production by miRNA remains poorly understood. Here we demonstrate that the miR-101 family members act as suppressors of TGF beta signalling by targeting T beta RI and its transcriptional activator Kruppel-like factor 6 (KLF6) during liver fibrogenesis. Using a mouse model of carbon tetrachloride (CCl4)-induced liver fibrosis, we conducted a time-course experiment and observed significant down-regulation of miR-101 in the fibrotic liver as well as in the activated HSCs and injured hepatocytes in the process of liver fibrosis. Meanwhile, up-regulation of T beta RI/KLF6 was observed in the fibrotic liver. Subsequent investigations validated that T beta RI and KLF6 were direct targets of miR-101. Lentivirus-mediated ectopic expression of miR-101 in liver greatly reduced CCl4-induced liver fibrosis, whereas intravenous administration of antisense miR-101 oligonucleotides aggravated hepatic fibrogenesis. Mechanistic studies revealed that miR-101 inhibited profibrogenic TGF beta signalling by suppressing T beta RI expression in both HSCs and hepatocytes. Additionally, miR-101 promoted the reversal of activated HSCs to a quiescent state, as indicated by suppression of proliferation and migration, loss of activation markers and gain of quiescent HSC-specific markers. In hepatocytes, miR-101 attenuated profibrogenic TGF beta signalling and suppressed the consequent up-regulation of profibrogenic cytokines, as well as TGF beta-induced hepatocyte apoptosis and the inhibition of cell proliferation. The pleiotropic roles of miR-101 in hepatic fibrogenesis suggest that it could be a potential therapeutic target for liver fibrosis. Copyright (C) 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.