Regulation of IL-2 gene expression and nuclear factor-90 translocation in vaccinia virus-infected cells.
Nuclear factor-90 (NF-90) has been described as a regulatory subunit of a complex containing DNA-dependent protein kinase (DNA-PK), Ku, and NF-45, which are capable of binding the interleukin-2 (IL-2) enhancer region and stimulating IL-2 gene expression. Vaccinia virus (VV) infection of Jurkat cells induced a nuclear factor that bound specifically to the IL-2 promoter sequence and led to the expression of the IL-2 transcript. Induction of this IL-2 promoter binding factor occurred concomitantly with the induction of NF-90 and translocation of NF-90 to the nucleus. Electrophoretic mobility supershift analysis using specific anti-NF-90 serum suggested the presence of NF-90 in the IL-2 promoter binding complex. As NF-90 can bind to double-stranded RNA (dsRNA) and be phosphorylated by the dsRNA-dependent protein kinase, PKR, we investigated whether accumulation of dsRNA in VV-infected cells could regulate IL-2 gene expression. Infection of Jurkat cells with a VV mutant that produces free dsRNA led to similar levels of induced NF-90 within the cell, but the protein remained localized within the cytosol. This mutant did not lead to the accumulation of an IL-2 promoter binding complex or to the synthesis of IL-2 mRNA. Other VV mutants that produced excess dsRNA also inhibited protein binding to the IL-2 enhancer, suggesting that the presence of viral dsRNA has a role in retaining NF-90 in the cytosol and regulating IL-2 gene expression.
Langland
Jeffrey O
JO
Department of Microbiology, Arizona State University, Tempe, AZ 85287-2701, USA.
Kao
Peter
P
Jacobs
Bertram L
BL
D004268:DNA-Binding Proteins / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics*; D019169:Jurkat Cells; D050778:NFATC Transcription Factors; D051903:Nuclear Factor 45 Protein; D050779:Nuclear Factor 90 Proteins; D009687:Nuclear Proteins; D011213:Poxviridae Infections / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D012330:RNA, Double-Stranded / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014616:Vaccinia virus / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; C494013:ILF2 protein, human; D007376:Interleukin-2; D050778:NFATC Transcription Factors; D051903:Nuclear Factor 45 Protein; D050779:Nuclear Factor 90 Proteins; D009687:Nuclear Proteins; D012330:RNA, Double-Stranded; D014157:Transcription Factors