Roles of the nuclear RNA-binding proteins hnRNP M and ILF3 in Zika virus infection

• Author / Creator

  Roughead, Brett CS

• Zika virus is a positive-sense RNA virus belonging to the Flaviviridae family of viruses, which include Dengue, Yellow Fever, Hepatitis C and West Nile viruses. Growing evidence suggests viral infection results in the subversion of numerous host cell factors to aid in viral replication. Despite the cytoplasmic replication cycle of ZIKV in infected cells, numerous host cell proteins implicated in the progression of the viral infection are host nuclear factors. We have focused on two nuclear factors, protein isoforms encoded by the interleukin enhancer-binding factor 3 (ILF3) gene, and the heterogeneous nuclear ribonucleoprotein M (hnRNP M). These proteins bind to RNA in host cells, and both of these proteins interact with ZIKV plus-strand viral RNA (+vRNA). Our goal has been to determine the possible roles of these proteins in ZIKV infection using a human tissue culture model system. NF90/NF110, encoded by the ILF3 gene, are double-stranded RNA binding proteins implicated in transcription, translation, and host immune responses. Using immunofluorescence imaging, we show that NF90/NF110 relocalizes from the nucleus to the cytoplasm following infection. This redistribution of NF90/NF110 to the cytoplasm facilitates an association with ZIKV double-stranded RNA intermediates. In our examination of the depletion of NF90/NF110, we observed a resultant increase in ZIKV viral production suggesting these protein isoforms function to suppress viral infection.
  hnRNP M also interacts with ZIKV +vRNA. However, during ZIKV infection we do not observe a detectable change in the nuclear localization of hnRNP M suggesting the bulk of hnRNP M appears to be physically separated from that of the ZIKV +vRNA. Thus, the observed physical interactions of hnRNP M with the ZIKV +vRNA may be transient or occur between a subpopulation of hnRNP M and the viral RNA. Consistent with their association, depletion of hnRNP M from cells inhibits ZIKV production. This observation is possibly mediated through an increased responsiveness of the interferon- and dsRNA-induced protein kinase R (PKR) immune pathway. In support of this, we observed an increase in the levels of phosphorylated-PKR early in ZIKV infection in populations depleted of hnRNP M. These data suggest a pro-viral role of hnRNP M in the ZIKV life cycle.

• Subjects / Keywords

  • Zika virus
  • ZIKV
  • ILF3
  • hnRNP M
  • nuclear factor

• Graduation date

  Spring 2021

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-gcr6-a118

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.