Hepatitis C virus (HCV) directly induces oxidative stress and liver injury. 
Bach1, a basic leucine zipper mammalian transcriptional repressor, negatively 
regulates heme oxygenase 1 (HMOX1), a key cytoprotective enzyme that has 
antioxidant and anti-inflammatory activities. microRNAs (miRNAs) are small 
noncoding RNAs ( approximately 22 nt) that are important regulators of gene 
expression. Whether and how miRNAs regulate Bach1 or HCV are largely unknown. 
The aims of this study were to determine whether miR-196 regulates Bach1, HMOX1, 
and/or HCV gene expression. HCV replicon cell lines (Con1 and 9-13) of the Con1 
isolate and J6/JFH1-based HCV cell culture system were used in this study. The 
effects of miR-196 mimic on Bach1, HMOX1, and HCV RNA, and protein levels were 
measured by way of quantitative real-time polymerase chain reaction (qRT-PCR) 
and Western blotting, respectively. The Dual Glo Luciferase Assay System was 
used to determine reporter activities. miR-196 mimic significantly 
down-regulated Bach1 and up-regulated HMOX1 gene expression and inhibited HCV 
expression. Dual luciferase reporter assays demonstrated that transfection of 
miR-196 mimic resulted in a significant decrease in Bach1 3'-untranslated region 
(UTR)-dependent luciferase activity but not in mutant Bach1 3'-UTR-dependent 
luciferase activity. Moreover, there was no detectable effect of mutant miR-196 
on Bach1 3'-UTR-dependent luciferase activity.
CONCLUSION: miR-196 directly acts on the 3'-UTR of Bach1 messenger RNA and 
translationally represses the expression of this protein, and up-regulates 
HMOX1. miR-196 also inhibits HCV expression in HCV replicon cell lines (genotype 
1b) and in J6/JFH1 (genotype 2a) HCV cell culture system. Thus, miR-196 plays a 
role in both HMOX1/Bach1 expression and the regulation of HCV expression in 
human hepatocytes. Overexpression of miR-196 holds promise as a potential novel 
strategy to prevent or ameliorate hepatitis C infection, and to protect against 
liver injury in chronic HCV infection.