Anti-apoptotic and oncogenic properties of the dsRNA-binding protein of vaccinia virus, E3L.
The vaccinia virus (VV) E3L gene encodes a dsRNA binding protein that inhibits activation of the IFN-induced, dsRNA-dependent protein kinase, (PKR), the 2-5A synthetases/RNase L system and other dsRNA dependent pathways, thus leading to efficient VV replication. To analyse E3L effects over cellular metabolism in a virus-free system, we have generated stable mouse 3T3 cell lines expressing E3L. Expression of E3L in NIH3T3 cells results in inhibition of eIF-2alpha phosphorylation and Ikappa(B)alpha degradation in response to dsRNA. Antiviral responses induced by IFN-alpha/beta were partially impaired in 3T3-E3L cells, as determined by a viability assay upon VSV infection. E3L expression also confers resistance to dsRNA-triggered apoptosis. Interestingly, cells expressing E3L grew faster than control cells, and showed increased expression of cyclin A and decreased levels of p27(Kip1). E3L cooperated with H-ras in a focus formation assay, and NIH3T3 E3L cells formed solid tumors when injected in nude mice. Overall, our findings reveal that interference of E3L protein with several cellular pathways, results in promotion of cellular growth, impairment of antiviral activity and resistance to apoptosis.
García
Maria Angel
MA
Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, (CSIC), Campus Universidad Autónoma, 28049 Madrid, Spain.
Guerra
Susana
S
Gil
Jesús
J
Jimenez
Victoria
V
Esteban
Mariano
M
D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002455:Cell Division / Q000235:genetics; D011905:Genes, ras; D020672:I-kappa B Proteins / Q000235:genetics; D007370:Interferon Type I / Q000494:pharmacology; D051379:Mice; D008819:Mice, Nude; D000072000:NF-KappaB Inhibitor alpha; D009374:Neoplasms, Experimental / Q000235:genetics; D009857:Oncogenes; D012330:RNA, Double-Stranded / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000502:physiology*; D014162:Transfection; D014616:Vaccinia virus / Q000235:genetics*; D014764:Viral Proteins / Q000502:physiology*
C081374:E3L protein, Vaccinia virus; D020672:I-kappa B Proteins; D007370:Interferon Type I; C000606205:Nfkbia protein, mouse; D012330:RNA, Double-Stranded; D016601:RNA-Binding Proteins; D014764:Viral Proteins; D000072000:NF-KappaB Inhibitor alpha