Reversal of interferon-gamma-resistant phenotype by poly(I:C): possible involvement of ISGF2 (IRF1) in interferon-gamma-mediated induction of the IDO gene.
Indoleamine 2,3-dioxygenase (IDO) is induced in many cell lines by interferon-gamma (IFN-gamma) treatment. IDO mRNA increases rapidly from 4 h after IFN-gamma treatment to at least 24 h after treatment in ME180 cells. The IFN-gamma-resistant mutant of ME180, IR3B6B, expresses only one-sixth the amount of IDO message after IFN-gamma treatment and very low levels of IDO. However, pretreatment of these mutants with poly(I:C) restores normal levels of IDO mRNAs and IDO activity. Since IRF1 mRNA induction is also low in IR3B6B cells after IFN-gamma treatment, we examined whether there was any relationship between IRF1 induction and IDO induction by IFN-gamma. The steady-state level of IRF1 mRNA was elevated by treating IR3B6B cells with poly(I:C) and IFN-gamma. Poly(I:C)-mediated reversal of IFN-gamma-resistant phenotype and induction of IDO and IRF1 messages are inhibited by 2-aminopurine. Transient transfection of IRF1 cDNA in ME180 cells resulted in activation of IDO transcription. Nuclear extracts prepared from IFN-gamma-treated ME180 and IR3B6B cells affected differently the mobility of a 80-bp DNA fragment of the 5' regulatory region of IDO gene. Pretreatment of IR3B6B cells with poly(I:C) and addition of IFN-gamma resulted in increased DNA binding of nuclear proteins to the DNA. Pre- and post-treatment of nuclear extract of IFN-gamma-treated ME180 cells with anti-IRF1 antibody resulted in a super shift in mobility of the probe with the abolishment of normal gel-shift pattern.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Biology, Indiana University, Bloomington 47405.
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D015075:2-Aminopurine / Q000494:pharmacology; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000502:physiology*; D004351:Drug Resistance / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D050856:Interferon Regulatory Factor-1; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010641:Phenotype; D010750:Phosphoproteins / Q000502:physiology*; D010766:Phosphorylation; D011070:Poly I-C / Q000494:pharmacology*; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000502:physiology; D014366:Tryptophan Oxygenase / Q000235:genetics*; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D050856:Interferon Regulatory Factor-1; D010750:Phosphoproteins; D014157:Transcription Factors; D015075:2-Aminopurine; D007371:Interferon-gamma; D014366:Tryptophan Oxygenase; D011070:Poly I-C