Reduced sphingosine kinase 1 activity in dengue virus type-2 infected cells can be mediated by the 3' untranslated region of dengue virus type-2 RNA

J Gen Virol. 2013 Nov;94(Pt 11):2437-2448. doi: 10.1099/vir.0.055616-0. Epub 2013 Aug 12.

Abstract

Sphingosine kinase 1 (SphK1) is a lipid kinase with important roles including regulation of cell survival. We have previously shown reduced SphK1 activity in cells with an established dengue virus type-2 (DENV-2) infection. In this study, we examined the effect of alterations in SphK1 activity on DENV-2 replication and cell death and determined the mechanisms of the reduction in SphK1 activity. Chemical inhibition or overexpression of SphK1 after established DENV-2 infection had no effect on infectious DENV-2 production, although inhibition of SphK1 resulted in enhanced DENV-2-induced cell death. Reduced SphK1 activity was observed in multiple cell types, regardless of the ability of DENV-2 infection to be cytopathic, and was mediated by a post-translational mechanism. Unlike bovine viral diarrhea virus, where SphK1 activity is decreased by the NS3 protein, SphK1 activity was not affected by DENV-2 NS3 but, instead, was reduced by expression of the terminal 396 bases of the 3' UTR of DENV-2 RNA. We have previously shown that eukaryotic elongation factor 1A (eEF1A) is a direct activator of SphK1 and here DENV-2 RNA co-localized and co-precipitated with eEF1A from infected cells. We propose that the reduction in SphK1 activity late in DENV-2-infected cells is a consequence of DENV-2 out-competing SphK1 for eEF1A binding and hijacking cellular eEF1A for its own replication strategy, rather than a specific host or virus-induced change in SphK1 to modulate viral replication. Nonetheless, reduced SphK1 activity may have important consequences for survival or death of the infected cell.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3' Untranslated Regions / genetics*
  • 3' Untranslated Regions / physiology
  • Animals
  • Apoptosis
  • Cell Line
  • Cells, Cultured
  • Cricetinae
  • Dengue / virology
  • Dengue Virus / genetics
  • Dengue Virus / pathogenicity
  • Dengue Virus / physiology*
  • Down-Regulation*
  • HEK293 Cells
  • Humans
  • Kidney / cytology
  • Kidney / virology
  • Monocytes / virology
  • Peptide Elongation Factor 1 / genetics
  • Peptide Elongation Factor 1 / metabolism*
  • Phosphotransferases (Alcohol Group Acceptor) / genetics
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*
  • RNA, Viral / genetics*
  • RNA, Viral / metabolism
  • Vero Cells
  • Virus Replication*

Substances

  • 3' Untranslated Regions
  • EEF1A1 protein, human
  • Peptide Elongation Factor 1
  • RNA, Viral
  • Phosphotransferases (Alcohol Group Acceptor)
  • sphingosine kinase