To further study factors affecting the HCV life cycle in mouse hepatocytes, we AC-7954 established IPK and IRK immortalized mouse hepatocyte lines by transduction with SV40T antigen. The established hepatocytes cell lines showed expression of HNF4, a major hepatocyte transcription factor, required for hepatocyte differentiation and liver-specific gene expression. The maintenance of hepatocellular functions was demonstrated by continuous expression of hepatocyte specific differentiation marker, albumin, and the lack of expression of the bile duct marker, cytokeratin. The close resemblance of these cell lines to primary mouse hepatocytes is crucial to ensure the physiological relevance of factors identified in these cell lines that affect the HCV life cycle. It is worth noting that HCV replication in IPS-1ko was higher than that in IFNARko hepatocytes. Since IPS-1 is present upstream of IFNAR in the IFN-amplification pathway, this higher J6JFH1 replication efficiency in IPS-1ko hepatocytes suggested the presence of an additive factor affecting HCV replication other than the induction of IFNAR-mediated type I IFN. This enhanced replication efficiency was also not accompanied by the induction of other interferon types, but was correlated with the reduction of HCV-induced apoptosis in mouse hepatocytes. This data clearly demonstrates that IPS-1 is playing an important role in the regulation of HCV infection in mouse hepatocytes through two different pathways, the IFN-induction pathways and another new IFN-independent pathway, leading to apoptotic cell death and elimination of HCV-harboring hepatocytes. The cytopathic effect of HCV infection in human cells is still contradictory. Although, some reports showed the induction of apoptosis and cell death by HCV infection in human hepatocytes, others showed suppression of apoptosis by HCV proteins. This TC-I 2014 difference may be due to the different cell lines used in the different studies. Almost all the studies reporting HCV-induced apoptosis used hepatocellular carcinoma cell lines. Since it has been established that the inability to undergo apoptosis is essential for the development of cancer, our use of immortalized, noncancerous hepatocytes may make it possible to reproduce the physiological response of the cells to HCV infection more closely. The IPS-1 regulation of cell death following the introduction of HCV-RNA may also regulate the effector cell function.