NF-IL6 (C/EBPbeta ) vigorously activates il1b gene expression via a Spi-1 (PU.1) protein-protein tether.
Two classes of transcription factors, ETS and bZIP, stand out as key mediators of monocyte commitment and differentiation. The ETS domain factor Spi-1 (also called PU.1) and the bZIP factor NF-IL6 (also called C/EBPbeta) have been shown to be involved in the transcriptional regulation of interleukin-1beta gene (il1b) and other monocyte-specific genes. We now show that these two factors strongly cooperate on the il1b core promoter (-59/+12) in the absence of direct NF-IL6 binding to DNA. Transient transfection assays, using mutated il1b core promoters, showed that the Spi-1, but not the NF-IL6, binding site is absolutely required for functional cooperativity. Furthermore, the NF-IL6 transactivation domain (TAD) is functionally indispensable and more critical than that of Spi-1. Additionally, TAD-deficient NF-IL6 functions as a dominant negative for Spi-1-mediated activation, suggesting the involvement of the bZIP DNA binding domain. This is supported by the demonstration of in vitro interaction between the NF-IL6 bZIP and Spi-1 winged helix-turn-helix (wHTH) DNA binding domains, arguing that NF-IL6 vigorously activates the il1b core promoter via protein-tethered transactivation mediated by Spi-1.
Yang
Z
Z
New England Baptist Bone & Joint Institute, Division of Hematology and Oncology, Beth Israel Deaconess Medical Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA.
Wara-Aswapati
N
N
Chen
C
C
Tsukada
J
J
Auron
P E
PE
D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D006367:HeLa Cells; D006801:Humans; D007375:Interleukin-1 / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D000099232:Proto-Oncogene Protein Spi-1
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D007375:Interleukin-1; D008070:Lipopolysaccharides; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D013755:Tetradecanoylphorbol Acetate; D015534:Trans-Activators; D014157:Transcription Factors; D000099232:Proto-Oncogene Protein Spi-1