Interaction of nuclear proteins with an AP-1/CRE-like promoter sequence in the human TNF-alpha gene.
The tumor necrosis factor alpha (TNF-alpha) promoter contains an AP-1/CRE-like binding site, TGAGCTCA. AP-1 elements generally transduce signals involving protein kinase C; the CRE site mediates a cAMP response, involving protein kinase A. Thus, this element has the potential to receive signals through divergent signaling pathways. Nuclear protein binding studies using extracts from THP-1 monocytic cells treated with lipopolysaccharide (LPS), which stimulates, or dexamethasone (Dex) or pentoxifylline (PTX), which inhibit TNF production, respectively, suggest that two low-mobility complexes could be involved in regulation through this promoter region. PTX and Dex increase binding of both these complexes compared with untreated cells; approximately 2 hours after LPS induction, the upper complex becomes undetectable. This upper complex is composed of ATF2 (activating transcription factor 2, a cyclic AMP responsive element binding protein) homodimers; the lower is a heterodimer of jun/ATF2. LPS induces c-jun and thus may enhance formation of jun/ATF2 complexes, which could be activating complexes. In this case, the simultaneous presence of both complexes, which would occur in the presence of Dex or PTX, could reduce the amount of TNF transcription through competitive binding. Through in vitro competitive binding studies comparing the binding affinities of the TNF promoter sequence and a consensus CRE, we further suggest how variation of endogenous binding sequences from consensus may be an important property for regulatory control of particular genes.
Department of Clinical Investigation, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030.
C L
CL
Newell
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AB
Deisseroth
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Lopez-Berestein
D051697:Activating Transcription Factor 1; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D001483:Base Sequence; D001667:Binding, Competitive; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D004268:DNA-Binding Proteins; D003907:Dexamethasone / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D015479:Leukemia, Myelomonocytic, Acute / Q000378:metabolism / Q000473:pathology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009841:Oligonucleotides / Q000378:metabolism; D010431:Pentoxifylline / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D016760:Proto-Oncogene Proteins c-fos / Q000276:immunology; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics* / Q000276:immunology; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics* / Q000276:immunology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism
D051697:Activating Transcription Factor 1; D000906:Antibodies; D004268:DNA-Binding Proteins; D008070:Lipopolysaccharides; D009687:Nuclear Proteins; D009841:Oligonucleotides; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone; D017868:Cyclic AMP-Dependent Protein Kinases; D010431:Pentoxifylline