Human microRNA hsa-miR-125a-5p interferes with expression of hepatitis B virus surface antigen

TLDR

MicroRNAs regulate gene expression post‑transcriptionally and have been implicated in antiviral defense mechanisms. The study aimed to identify human liver microRNA target sites within the HBV genome using the MiRanda algorithm. Seven potential target sites were found clustered in a 995‑bp region overlapping the polymerase and surface antigen ORFs, conserved across common HBV subtypes, and were validated in HepG2, HuH‑7, and PLC/PRF/5 cells using luciferase reporter assays. The microRNA hsa‑miR‑125a‑5p bound the viral sequence, markedly reduced reporter activity, inhibited viral translation, and down‑regulated surface antigen expression, supporting a role for host miRNAs in HBV infection and suggesting new therapeutic avenues.

Abstract

MicroRNAs are small non-coding RNAs that modulate gene expression at post-transcriptional level, playing a crucial role in cell differentiation and development. Recently, some reports have shown that a limited number of mammalian microRNAs are also involved in anti-viral defense. In this study, the analysis of the hepatitis B virus (HBV) genome by the computer program MiRanda led to the identification of seven sites that are potential targets for human liver microRNAs. These sites were found to be clustered in a 995-bp segment within the viral polymerase ORF and the overlapping surface antigen ORF, and conserved among the most common HBV subtypes. The HBV genomic targets were then subjected to a validation test based on cultured hepatic cells (HepG2, HuH-7 and PLC/PRF/5) and luciferase reporter genes. In this test, one of the selected microRNAs, hsa-miR-125a-5p, was found to interact with the viral sequence and to suppress the reporter activity markedly. The microRNA was then shown to interfere with the viral translation, down-regulating the expression of the surface antigen. Overall, these results support the emerging concept that some mammalian microRNAs play a role in virus-host interaction. Furthermore, they provide the basis for the development of new strategies for anti-HBV intervention.