Hepatitis C Virus Exploits Death Receptor 6-mediated Signaling Pathway to Facilitate Viral Propagation.

The life cycle of hepatitis C virus (HCV) is highly dependent on host proteins for virus propagation. By transcriptome sequencing analysis, we identified host genes that were highly differentially expressed in HCV-infected cells. Of these candidates, we selected Death receptor 6 (DR6) for further characterization. DR6 is an orphan member of the tumor necrosis factor receptor superfamily. In the present study, we demonstrated that both mRNA and protein levels of DR6 were increased in the context of HCV replication. We further showed that promoter activity of DR6 was increased by HCV infection. By employing promoter-linked reporter assay, we showed that HCV upregulated DR6 via ROS-mediated NF-κB pathway. Both mRNA and protein levels of DR6 were increased by NS4B or NS5A. However, NS5A but not NS4B specifically interacted with DR6. We showed that HCV modulated JNK, p38 MAPK, STAT3, and Akt signaling pathways in a DR6-dependent manner. Interestingly, Akt signaling cascade was regulated by protein interplay between DR6 and NS5A. Silencing of DR6 expression resulted in decrease of infectious HCV production without affecting viral entry, replication, and translation. Together, these data indicate that HCV modulates DR6 signaling pathway for viral propagation and may contribute to HCV-mediated pathogenesis.