A role for Sp and helix-loop-helix transcription factors in the regulation of the human Id4 gene promoter activity.
Id family helix-loop-helix (HLH) proteins are involved in the regulation of proliferation and differentiation of several cell types. To identify cis- and trans-acting factors that regulate Id4 gene expression, we have analyzed the promoter regulatory sequences of the human Id4 gene in transient transfections and gel mobility shift assays. We have identified two functional elements, both located downstream from the TATA motif, that control Id4 promoter activity. One element contains a consensus E-box, and we demonstrated that the protein complex binding to the E-box contains the bHLH-zip upstream stimulatory factor (USF) transcription factor. Enforced expression of USF1 leads to E-box-mediated stimulation of promoter activity. The E-box also mediated stimulatory effects of several bHLH transcription factors, and co-expression of Id4 blocked the stimulatory effect mediated by the bHLH factors. A second element is a GA motif, located downstream from the transcriptional start sites, mutation of which resulted in a 20-fold increase in transcriptional activity. Gel-shift analysis and transfections into Drosophila Schneider SL2 cells showed that the repressor element is recognized by both Sp1 and Sp3 factors. These data suggest that Id4 transcription control is highly complex, involving both negative and positive regulatory elements, including a novel inhibitory function exerted by Sp1 and Sp3 transcription factors.
Pagliuca
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Department of Genetics, Molecular and General Biology, University of Naples "Federico II," via Mezzocannone 8, 80134 Naples, Italy.
Cannada-Bartoli
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P
Lania
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D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D004268:DNA-Binding Proteins / Q000502:physiology; D004330:Drosophila; D005786:Gene Expression Regulation; D006367:HeLa Cells; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D051796:Inhibitor of Differentiation Proteins; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics*; D016329:Sp1 Transcription Factor / Q000502:physiology*; D051705:Sp3 Transcription Factor; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D014162:Transfection; D051720:Upstream Stimulatory Factors; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; C490128:ID4 protein, human; C086479:Idb4 protein, mouse; D051796:Inhibitor of Differentiation Proteins; D011506:Proteins; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; C497122:Sp3 protein, mouse; D014157:Transcription Factors; C497181:USF1 protein, human; D051720:Upstream Stimulatory Factors; C497183:Usf1 protein, mouse; D051705:Sp3 Transcription Factor