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.
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.
Flinders Medical Science and Technology, School of Medicine, Flinders University, University Drive, Bedford Park, Adelaide, South Australia 5042, Australia.
J M
JM
Carr
School of Molecular and Biomedical Science, University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia.
T
T
Kua
Flinders Medical Science and Technology, School of Medicine, Flinders University, University Drive, Bedford Park, Adelaide, South Australia 5042, Australia.
J N
JN
Clarke
Flinders Medical Science and Technology, School of Medicine, Flinders University, University Drive, Bedford Park, Adelaide, South Australia 5042, Australia.
J K
JK
Calvert
Centre for Cancer Biology, S.A. Pathology, Frome Rd, Adelaide, South Australia 5000, Australia.
J R
JR
Zebol
Centre for Cancer Biology, S.A. Pathology, Frome Rd, Adelaide, South Australia 5000, Australia.|School of Molecular and Biomedical Science, University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia.
M R
MR
Beard
School of Pharmacy and Medical Science, University of South Australia, Adelaide, South Australia 5001, Australia.|Centre for Cancer Biology, S.A. Pathology, Frome Rd, Adelaide, South Australia 5000, Australia.|School of Molecular and Biomedical Science, University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia.
S M
SM
Pitson
D020413:3' Untranslated Regions / Q000235:genetics* / Q000502:physiology; D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D002478:Cells, Cultured; D006224:Cricetinae; D003715:Dengue / Q000821:virology; D003716:Dengue Virus / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D015536:Down-Regulation; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000821:virology; D009000:Monocytes / Q000821:virology; D020648:Peptide Elongation Factor 1 / Q000235:genetics / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D014709:Vero Cells; D014779:Virus Replication; D000099157:Sphingosine Kinase
D020413:3' Untranslated Regions; D020648:Peptide Elongation Factor 1; D017853:Phosphotransferases (Alcohol Group Acceptor); D012367:RNA, Viral; D000099157:Sphingosine Kinase; C094814:EEF1A1 protein, human