Liver-specific microRNA-122: biogenesis and role in hepatitis C virus replication

MicroRNAs (miRNAs) are short non-coding regulatory RNA molecules. In animals, miRNAs repress gene expression by binding to 3’ untranslated region (UTR) sites. In contrast, the highly expressed liver-specific miR-122 binds to the 5’UTR of hepatitis C virus (HCV) RNA and positively regulates viral replication. miRNAs are generally expressed within introns of protein coding genes, and processed cotranscriptionally.

​However, miR-122 is one of a subset of miRNAs located in long noncoding RNAs, where we find that miRNA processing directly mediates transcription termination. Both the interplay between transcription and miRNA processing and the mechanism of HCV regulation by miR-122 will be discussed.