Interferon consensus sequence-binding protein, a member of the interferon regulatory factor family, suppresses interferon-induced gene transcription.
We previously isolated a cDNA clone encoding interferon consensus sequence-binding protein (ICSBP), a member of the interferon regulatory factor (IRF) family, that binds to the interferon (IFN)-stimulated response element (ISRE) of many IFN-regulated genes. In this investigation, we studied the functional role of ICSBP by transient cotransfection of ICSBP cDNA with IFN-responsive reporter genes into the human embryonal carcinoma cell line N-Tera2. These cells were shown not to express ICSBP or IRF-2, thus allowing functional analysis of transfected cDNAs. Cotransfection of ICSBP into cells treated with retinoic acid or any of the IFNs (alpha, beta, or gamma) repressed expression of a chloramphenicol acetyltransferase reporter driven by the major histocompatibility complex class I gene promoter. Similarly, ICSBP repressed expression of chloramphenicol acetyltransferase reporters driven by the ISREs of the 2'-5' oligoadenylate synthetase, guanylate-binding protein, and ISG-15 genes in IFN-treated cells. The repression was dependent on the presence of the ISRE in the reporter. Deletion analysis showed that the putative N-terminal DNA binding domain of ICSBP by itself is capable of mediating the repression. Using the same cotransfection conditions as for ICSBP, a similar repression of these reporters was observed with IRF-2. Finally, ICSBP repressed the IRF-1-mediated induction of major histocompatibility complex class I and IFN-beta reporters in the absence of IFN or retinoic acid. Taken together, these results suggest that ICSBP is a negative regulatory factor capable of repressing transcription of target genes induced by IFN, retinoic acid, or IRF-1.
Nelson
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N
Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
Marks
M S
MS
Driggers
P H
PH
Ozato
K
K
D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000502:physiology*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004742:Enhancer Elements, Genetic; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects*; D005805:Genes, MHC Class I; D006801:Humans; D066298:In Vitro Techniques; D050856:Interferon Regulatory Factor-1; D050836:Interferon Regulatory Factor-2; D050835:Interferon Regulatory Factors; D016899:Interferon-beta / Q000235:genetics; D007372:Interferons / Q000494:pharmacology*; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010750:Phosphoproteins / Q000502:physiology; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics*; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000187:drug effects; D000099185:Interferon Regulatory Factor-8
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D050856:Interferon Regulatory Factor-1; D050836:Interferon Regulatory Factor-2; D050835:Interferon Regulatory Factors; D016899:Interferon-beta; D007372:Interferons; D009838:Oligodeoxyribonucleotides; D010750:Phosphoproteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; D000099185:Interferon Regulatory Factor-8; C494257:IRF1 protein, human; C494229:IRF2 protein, human