Dr. Chen, Steve S.-L.

Emeritus Research Fellow

Specialty:
  • Retrovirology
  • HCV
  • Virus-host Interactions
  • Virus Assembly and Budding

Education and Positions:
  • Ph.D., Biochemistry,  Purdue University


Highlight Detail
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Human Choline Kinase-alpha Promotes Hepatitis C Virus RNA Replication through Modulating Membranous Viral Replication Complex Formation

Dr. Chen, Steve S.-L.
Journal of Virology, Aug 03, 2016

Hepatitis C virus (HCV) infection reorganizes cellular membranes to create an active viral replication site named the “membranous web” (MW). The role that human choline kinase-α (hCKa) plays in HCV replication remains elusive. Here, we first showed that hCKa activity, not the CDP-choline pathway, promoted viral RNA replication. Confocal microscopy and subcellular fractionation of HCV-infected cells revealed that a small fraction of hCKα colocalized with the viral replication complex (RC) on the endoplasmic reticulum (ER) and that HCV infection increased hCKα localization to the ER. In the pTM-NS3-NS5B model, NS3-NS5B expression increased the localization of the wild-type, not the inactive D288A mutant, hCKα on the ER, and hCKα activity was required for effective trafficking of hCKα and NS5A to the ER. Coimmunoprecipitation showed that hCKα was recruited onto the viral RC presumably through its binding to NS5A domain 1. hCKα silencing or treatment with CK37, an hCKα activity inhibitor, abolished HCV-induced MW formation. In addition, hCKα depletion hindered NS5A localization on the ER, interfered with NS5A and NS5B colocalization, and mitigated NS5A-NS5B interactions but had no apparent effect on NS5A-NS4B and NS4B-NS5B interactions. Nevertheless, hCKα activity was not essential for the binding of NS5A to hCKα or NS5B. These findings demonstrate that hCKα forms a complex with NS5A and that hCKα activity enhances the targeting of the complex to the ER, where hCKα protein, not activity, mediates NS5A binding to NS5B, thereby promoting functional membranous viral RC assembly and viral RNA replication.