Key result
Small interference RNAs targeting Csk, Jak1, and Vrk1, and a Csk inhibitor, significantly reduced viral RNA and protein levels in HCV replicon-bearing cells.
Csk, Jak1, and Vrk1 are identified as host cell factors required for HCV replication, with Csk likely mediating its effect through Fyn.
Host factors may enable new HCV antivirals; leaves open in vivo efficacy and clinical translation.
The propagation of the hepatitis C virus (HCV) is a complex process that requires both host and viral proteins. To facilitate identification of host cell factors that are required for HCV replication, we screened a panel of small interference RNAs that preferentially target human protein kinases using an HCV replicon expressing the firefly luciferase gene as a genetic reporter. Small interference RNAs specific for three human kinases, Csk, Jak1, and Vrk1, were identified that reproducibly reduce viral RNA and viral protein levels in HCV replicon-bearing cells. Treatment of replicon cells with a small molecule inhibitor of Csk also resulted in a significant reduction in HCV RNA and proteins, further supporting a role for Csk in HCV replication. The effects of siRNAs targeting eight kinases known to be negatively regulated by Csk were then examined; knock down of one of these kinases, Fyn, resulted in up-regulation of the HCV replicon, suggesting that Csk mediates its effect on HCV replication through Fyn. This conclusion was further corroborated by demonstration that replicon cells treated with Csk inhibitor contained lower levels of the phosphorylated form of Fyn than control cells.
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Supeková et al. (2007) studied Hepatitis C Virus (HCV) replication. Small interference RNAs targeting human protein kinases (Csk, Jak1, Vrk1) and Csk inhibitor vs. Control cells was evaluated on Viral RNA and viral protein levels. Small interference RNAs targeting Csk, Jak1, and Vrk1, and a Csk inhibitor, significantly reduced viral RNA and protein levels in HCV replicon-bearing cells.