Dual Role of miR-122 in Molecular Pathogenesis of Viral Hepatitis

The hepatic microrna (mirna), mir-122, is the most abundant mirna within the liver, where it accounts for 70% of the total mirna pool. it is known that mir-122, as an unusual host factor, increases the abundance of hepatitis c virus (hcv) rna in hcv infection by binding directly to the 5’-utr of the viral ge- nome. therefore, it has been suggested as a potential target for the treatment of hepatitis c. however, recent evidence shows that mir-122 decreases hbv replication through the inhibitory effect of p53 on hbv transcription, and consequently it acts as a tumor-suppressor through both a decrease in hbv replication and by directly targeting cyclin g1, as well as wnt/beta-catenin, and ndrg3 pathways. this paper will briefly discuss the underlying mechanisms for the dual role of mir-122 in viral hepatitis, and explains why therapeutic applications of mir-122 may differ based on the underlying disease.