MicroRNA-194 protects against chronic hepatitis B-related liver damage by promoting hepatocyte growth via ACVR2B.

Persistent infection with the hepatitis B virus leads to liver cirrhosis and hepatocellular carcinoma. MicroRNAs (miRNAs) play an important role in a variety of biological processes; however, the role of miRNAs in chronic hepatitis B (CHB)-induced liver damage remains poorly understood. Here, we investigated the role of miRNAs in CHB-related liver damage. Microarray analysis of the expression of miRNAs in 22 CHB patients and 33 healthy individuals identified miR-194 as one of six differentially expressed miRNAs. miR-194 was up-regulated in correlation with increased liver damage in the plasma or liver tissues of CHB patients. In mice subjected to 2/3 partial hepatectomy, miR-194 was up-regulated in liver tissues in correlation with hepatocyte growth and in parallel with the down-regulation of the activin receptor ACVR2B. Overexpression of miR-194 in human liver HL7702 cells down-regulated ACVR2B mRNA and protein expression, promoted cell proliferation, acceleratedG1 to S cell cycle transition, and inhibited apoptosis, whereas knockdown of miR-194 had the opposite effects. Luciferase reporter assays confirmed that ACVR2B is a direct target of miR-194, and overexpression of ACVR2B significantly repressed cell proliferation and G1 to S phase transition and induced cell apoptosis. ACVR2B overexpression abolished the effect of miR-194, indicating that miR-194 promotes hepatocyte proliferation and inhibits apoptosis by down-regulating ACVR2B. Taken together, these results indicate that miR-194 plays a crucial role in hepatocyte proliferation and liver regeneration by targeting ACVR2B and may represent a novel therapeutic target for the treatment of CHB-related liver damage.