An IFN-gamma-inducible transcription factor, IFN consensus sequence binding protein (ICSBP), stimulates IL-12 p40 expression in macrophages.
IL-12 is a cytokine that links innate and adaptive immunity. Its subunit p40 is induced in macrophages following IFN-gamma/LPS stimulation. Here we studied the role for IFN consensus sequence binding protein (ICSBP), an IFN-gamma/LPS-inducible transcription factor of the IFN regulatory factor (IRF) family in IL-12 p40 transcription. Macrophage-like cells established from ICSBP-/- mice did not induce IL-12 p40 transcripts, nor stimulated IL-12 p40 promoter activity after IFN-gamma/LPS stimulation, although induction of other inducible genes was normal in these cells. Transfection of ICSBP led to a marked induction of both human and mouse IL-12 p40 promoter activities in ICSBP+/+ and ICSBP-/- cells, even in the absence of IFN-gamma/LPS stimulation. Whereas IRF-1 alone was without effect, synergistic enhancement of promoter activity was observed following cotransfection of ICSBP and IRF-1. Deletion analysis of the human promoter indicated that the Ets site, known to be important for activation by IFN-gamma/LPS, also plays a role in the ICSBP activation of IL-12 p40. A DNA affinity binding assay revealed that endogenous ICSBP is recruited to the Ets site through protein-protein interaction. Last, transfection of ISCBP alone led to induction of the endogenous IL-12 p40 mRNA in the absence of IFN-gamma and LPS. Taken together, our results show that ICSBP induced by IFN-gamma/LPS, acts as a principal activator of IL-12p40 transcription in macrophages.
Wang
I M
IM
Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Contursi
C
C
Masumi
A
A
Ma
X
X
Trinchieri
G
G
Ozato
K
K
D000818:Animals; D002460:Cell Line; D016384:Consensus Sequence / Q000276:immunology; D004268:DNA-Binding Proteins / Q000502:physiology; D004357:Drug Synergism; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D050856:Interferon Regulatory Factor-1; D050836:Interferon Regulatory Factor-2; D050835:Interferon Regulatory Factors; D007371:Interferon-gamma / Q000494:pharmacology*; D018664:Interleukin-12 / Q000096:biosynthesis* / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D046911:Macromolecular Substances; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D010750:Phosphoproteins / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000276:immunology; D011518:Proto-Oncogene Proteins / Q000502:physiology; D050783:Proto-Oncogene Proteins c-ets; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic / Q000276:immunology; D015533:Transcriptional Activation / Q000276:immunology; D014162:Transfection / Q000276:immunology; D000099185:Interferon Regulatory Factor-8
D004268:DNA-Binding Proteins; D050856:Interferon Regulatory Factor-1; D050836:Interferon Regulatory Factor-2; D050835:Interferon Regulatory Factors; D007371:Interferon-gamma; D018664:Interleukin-12; D008070:Lipopolysaccharides; D046911:Macromolecular Substances; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D012097:Repressor Proteins; D014157:Transcription Factors; D000099185:Interferon Regulatory Factor-8; C494257:IRF1 protein, human; C494229:IRF2 protein, human; C494258:Irf1 protein, mouse; C494230:Irf2 protein, mouse