Direct induction of interferon-gamma- and interferon-alpha/beta-inducible genes by double-stranded RNA.
Using Northern analysis, we here show that the inducibility by double-stranded (ds) RNA of interferon-alpha/beta-inducible genes is not restricted to a few genes but extends to all the genes known to be stimulated by IFN type I in fibroblasts. Moreover, we show that some genes, preferentially regulated by IFN-gamma, are also activated by dsRNA. We present a series of arguments demonstrating that the induction by dsRNA is not mediated by IFN. In addition to the fact that this induction occurs in the presence of cycloheximide and/or anti-IFN-alpha/beta antibodies in fibroblasts, we observed that, in IFN-resistant Daudi cells, ISG15 and IP-10 genes which are not induced by IFN-beta, are still inducible by dsRNA. dsRNA is also still active on 2-5 AS and ISG15 genes in cells carrying homozygous deletions of IFN alpha/beta genes. Actinomycin D experiments and nuclear in vitro elongation assays reveal that the induction by dsRNA involves, as its early step, a transcriptional event. This induction was found not to require protein synthesis, suggesting that activation of preexisting cellular factors is involved. The opposite inducibility by dsRNA of IFN-beta and 2',5'-oligoadenylate (2-5A) synthetase genes in serum-deprived fibroblasts indicates that pathways of induction by dsRNA of these two genes are not identical. Inhibition by 2-aminopurine of the induction of IFN-inducible mRNAs by IFN-beta or dsRNA suggests the participation of a protein kinase in their mechanism of action.
Unité 245 INSERM, Centre INSERM, Hôpital St.-Antoine, Paris, France.
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D015075:2-Aminopurine / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D007370:Interferon Type I / Q000235:genetics* / Q000494:pharmacology; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000494:pharmacology; D007371:Interferon-gamma / Q000235:genetics* / Q000494:pharmacology; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D011070:Poly I-C / Q000494:pharmacology; D012330:RNA, Double-Stranded / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins; D014158:Transcription, Genetic; D014709:Vero Cells
D007370:Interferon Type I; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D015345:Oligonucleotide Probes; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D011994:Recombinant Proteins; D015075:2-Aminopurine; D007371:Interferon-gamma; D003513:Cycloheximide; D011070:Poly I-C