MicroRNA-196 Represses Bach1 Protein and Hepatitis C Virus Gene Expression in Human Hepatoma Cells Expressing Hepatitis C Viral Proteins

Liver-Biliary-Pancreatic Center and the Liver, Digestive Diseases, and Metabolism Laboratory, Carolinas Medical Center, Charlotte, NC 28232-2861, USA.
Hepatology (Impact Factor: 11.06). 05/2010; 51(5):1494-504. DOI: 10.1002/hep.23401
Source: PubMed


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.

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    • "Recently, it has been demonstrated that miR-196 targets the 3 UTR of BACH1 mRNA that promoted its down-regulation. This fact induces up-regulation of HO-1 and the inhibition of HCV gene expression (Hou et al., 2010). Additionally, it has been established that miR-122, abundant in hepatic cells, diminishes HCV replication directly by interaction with the viral genome and indirectly pathway through down-regulation of BACH1 by targeting its 3 UTR, which causes up-regulation of HO-1 and protects the infected cell from hepatic injury (Shan et al., 2007). "
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    • "We also discuss the perspectives of miRNA-based therapeutic approaches for viral hepatitis and liver disease. miR-122 and liver physiology miR-122 has a liver-enriched expression and is one of the most abundant miRNAs in the liver, accounting for about 70% and 52% of the whole hepatic miRNome in adult mouse and human, respectively [20] [21] [22]. Consequently, miR-122 plays a central role in liver development, differentiation, homeostasis and functions (Fig. 1). "
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