Identification of HNRNPK as Regulator of Hepatitis C Virus Particle Production

PLoS Pathog. 2015 Jan 8;11(1):e1004573. doi: 10.1371/journal.ppat.1004573. eCollection 2015 Jan.

Abstract

Hepatitis C virus (HCV) is a major cause of chronic liver disease affecting around 130 million people worldwide. While great progress has been made to define the principle steps of the viral life cycle, detailed knowledge how HCV interacts with its host cells is still limited. To overcome this limitation we conducted a comprehensive whole-virus RNA interference-based screen and identified 40 host dependency and 16 host restriction factors involved in HCV entry/replication or assembly/release. Of these factors, heterogeneous nuclear ribonucleoprotein K (HNRNPK) was found to suppress HCV particle production without affecting viral RNA replication. This suppression of virus production was specific to HCV, independent from assembly competence and genotype, and not found with the related Dengue virus. By using a knock-down rescue approach we identified the domains within HNRNPK required for suppression of HCV particle production. Importantly, HNRNPK was found to interact specifically with HCV RNA and this interaction was impaired by mutations that also reduced the ability to suppress HCV particle production. Finally, we found that in HCV-infected cells, subcellular distribution of HNRNPK was altered; the protein was recruited to sites in close proximity of lipid droplets and colocalized with core protein as well as HCV plus-strand RNA, which was not the case with HNRNPK variants unable to suppress HCV virion formation. These results suggest that HNRNPK might determine efficiency of HCV particle production by limiting the availability of viral RNA for incorporation into virions. This study adds a new function to HNRNPK that acts as central hub in the replication cycle of multiple other viruses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cells, Cultured
  • HEK293 Cells
  • Hepacivirus / drug effects
  • Hepacivirus / physiology*
  • Heterogeneous-Nuclear Ribonucleoprotein K
  • Humans
  • Protein Binding
  • RNA Interference
  • RNA, Small Interfering / pharmacology
  • RNA, Viral / metabolism
  • Ribonucleoproteins / antagonists & inhibitors
  • Ribonucleoproteins / physiology*
  • Virion / drug effects
  • Virion / physiology*
  • Virus Assembly / drug effects
  • Virus Assembly / genetics*
  • Virus Replication / drug effects
  • Virus Replication / genetics

Substances

  • Heterogeneous-Nuclear Ribonucleoprotein K
  • RNA, Small Interfering
  • RNA, Viral
  • Ribonucleoproteins
  • HNRNPK protein, human

Grant support

Work by RB was supported by the Deutsche Forschungsgemeinschaft FOR1202, TP1; BA 1505/4-2), the BMBF (project ViroQuant, contract no. 0313923) and the EU (project SysPatho, contract no. 260429). The work of LK was funded by ViroQuant (BMBF, 0313923) and SysPatho (European Union, 7th framework program, 260429). Work of MP was supported by the Postdoc Fellowship of the Medical Faculty of Heidelberg. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript