Inhibition Of Hepatitis B Virus Gene Expression And Replication By Hepatocyte Nuclear Factor 6

Hepatitis B virus (HBV), a small enveloped DNA virus, chronically infects more than 350 million people worldwide and causes liver diseases from hepatitis to cirrhosis and liver cancer. Although effective vaccines against HBV has been developed decades ago, the chronic HBV infection is still a major global health burden. Current anti-HBV therapies including interferon and nuclear acid analogues suffer from side effects or low respondency. Moreover, none of the drugs can curechronic HBV infection and eradicate HBV from the liver of the patients. Thus, it is necessay to investigate the genome replication and virus-host interactions to facilitate the development of new therapeutic methods to chronic HBV infection.HBV is a member of Hepadnaviridae and replicates in human liver. The transcription and replication of HBV are regulated by various ubiquitous or liver enriched transcription factors. Liver enriched transcription factors include hepatocyte nuclear factors (HNFs), CCAAT/Element binding proteins (C/EBP), and D-site binding proteins. Among these factors, HNF1, HNF3, HNF4 and C/EBP alpha have been shown to regulate HBV replication through transcriptional or posttranscriptional mechanisms.Here, we report that hepatocyte nuclear factor 6 (HNF6), a liver-enriched transcription factor, can inhibit HBV gene expression and DNA replication. Overexpression of HNF6 inhibited, while knockdown of HNF6 expression enhanced HBV gene expression and replication in hepatoma cells. Mechanistically, SP2 promoter was inhibited by HNF6, which partly accounts for the inhibition on S mRNA. Detailed analysis showed that a cis element on HBV genome (nt 3009-3019) was responsible for the inhibition of SP2 promoter by HNF6. Moreover, further analysis showed that HNF6 reduced viral pregenomic RNA (pgRNA) posttranscriptionally via accelerating the degradation of HBV pgRNA independent of La protein. Furthermore, by using truncated mutation analyses, we demonstrated that the N-terminal region of HNF6 was responsible for its inhibitory effects. Importantly, introduction of an HNF6 expression construct with HBV genome into the mouse liver using hydrodynamic injection resulted in a significant reduction in viral gene expression and DNA replication. Overall, our data demonstrated that HNF6 is a novel host factor that can restrict HBV replication via both transcriptional and posttranscriptional mechanisms.