Gene induction by interferons and double-stranded RNA: selective inhibition by 2-aminopurine.
Transcription of several interferon-inducible human genes is also induced by double-stranded RNA. The nature and the mechanism of action of signals generated by interferons and by double-stranded RNA which mediate the induction of these genes are under investigation. Here we report that 2-aminopurine, a known inhibitor of protein kinases, could selectively block this induction process. Induction of mRNAs 561 and 6-16 in HeLaM cells by double-stranded RNA was completely inhibited by 10 mM 2-aminopurine, whereas cellular protein and RNA syntheses as well as the induction of metallothionein mRNA by CdCl2 were unaffected by this inhibitor. In addition, 2-aminopurine blocked the induction of the same two mRNAs and of mRNAs 2-5(A) synthetase, 2A, and 1-8 by alpha interferon and of mRNAs 2A and 1-8 by gamma interferon in HeLaM cells. The observed inhibition was at the level of transcription, and for establishing efficient inhibition, the 2-aminopurine treatment had to begin at early stages of interferon treatment. In GM2767 cells, 2-aminopurine inhibited induction of mRNAs 561 and 6-16 by double-stranded RNA but not by alpha interferon. These results suggest that double-stranded RNA-induced signal 2 is distinct from the interferon-alpha-induced signal 2 (R. K. Tiwari, J. Kusari, and G. C. Sen, EMBO J. 6:3373-3378, 1987) and that 2-aminopurine can block the former but not the latter. Moreover, it appeared that 2-aminopurine could block the production of signal 1 by interferons. This was confirmed by experiments in which we separately tested the effects of 2-aminopurine on signal 1 and signal 2 production by interferons in HeLaM cells. Although no direct experimental evidence is available as yet, our results are consistent with the hypothesis that the functioning of a protein kinase activity may be necessary for transcriptional induction of genes by double-stranded RNA and for gene induction by interferons in those cells in which signal 1 production is needed.
Tiwari
R K
RK
Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
Kusari
J
J
Kumar
R
R
Sen
G C
GC
D015075:2-Aminopurine / Q000494:pharmacology*; D000225:Adenine / Q000031:analogs & derivatives*; D000818:Animals; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007372:Interferons / Q000494:pharmacology*; D051379:Mice; D011494:Protein Kinases / Q000502:physiology*; D012330:RNA, Double-Stranded / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation
D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D015075:2-Aminopurine; D007372:Interferons; D011494:Protein Kinases; D000225:Adenine