title: Differential control of Notch1 gene transcription by Klf4 and Sp3 transcription factors in normal versus cancer-derived keratinocytes.
abstract: In specific cell types like keratinocytes, Notch signaling plays an important pro-differentiation and tumor suppressing function, with down-modulation of the Notch1 gene being associated with cancer development. Besides being controlled by p53, little else is known on regulation of Notch1 gene expression in this context. We report here that transcription of this gene is driven by a TATA-less "sharp peak" promoter and that the minimal functional region of this promoter, which extends from the -342 bp position to the initiation codon, is differentially active in normal versus cancer cells. This GC rich region lacks p53 binding sites, but binds Klf4 and Sp3. This finding is likely to be of biological significance, as Klf4 and, to a lesser extent, Sp3 are up-regulated in a number of cancer cells where Notch1 expression is down-modulated, and Klf4 over-expression in normal cells is sufficient to down-modulate Notch1 gene transcription. The combined knock-down of Klf4 and Sp3 was necessary for the reverse effect of increasing Notch1 transcription, consistent with the two factors exerting an overlapping repressor function through their binding to the Notch1 promoter.
authors.affiliation: Department of Biochemistry, University of Lausanne, Epalinges, Switzerland.
authors.forename: Chiara
authors.initials: C
authors.lastname: Lambertini
authors.forename: Serafino
authors.initials: S
authors.lastname: Pantano
authors.forename: G Paolo
authors.initials: GP
authors.lastname: Dotto
mesh_terms: D045744:Cell Line, Tumor; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D053263:Gene Regulatory Networks; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009369:Neoplasms; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051881:Receptor, Notch1 / Q000235:genetics*; D051705:Sp3 Transcription Factor / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D051881:Receptor, Notch1; D051705:Sp3 Transcription Factor