title: Suppressor of hairless directly activates transcription of enhancer of split complex genes in response to Notch receptor activity.
abstract: We have investigated the functional relationships among three loci that are required for multiple alternative cell fate decisions during adult peripheral neurogenesis in Drosophila: Notch (N), which encodes a transmembrane receptor protein, Suppressor of Hairless [Su(H)], which encodes a DNA-binding transcription factor, and the Enhancer of split gene complex [E(spl)-C], which includes seven transcription units that encode basic helix-loop-helix (bHLH) repressor proteins. We describe several lines of evidence establishing that Su(H) directly activates transcription of E(spl)-C genes in response to N receptor activity. Expression of an activated form of the N receptor leads to elevated and ectopic E(spl)-C transcript accumulation and promoter activity in imaginal discs. We show that the proximal upstream regions of three E(spl)-C genes contain multiple specific binding sites for Su(H). The integrity of these sites, as well as Su(H) gene activity, are required not only for normal levels of expression of E(spl)-C genes in imaginal disc proneural clusters, but also for their transcriptional response to hyperactivity of the N receptor. Our results establish Su(H) as a direct regulatory link between N receptor activity and the expression of E(spl)-C genes, extending the known linear structure of the N cell-cell signaling pathway.
authors.affiliation: Department of Biology, University of California San Diego, La Jolla 92093-0366, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Bailey
authors.forename: J W
authors.initials: JW
authors.lastname: Posakony
mesh_terms: D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila / Q000235:genetics / Q000254:growth & development; D029721:Drosophila Proteins; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D018257:Helix-Loop-Helix Motifs / Q000235:genetics; D007301:Insect Hormones / Q000235:genetics*; D008565:Membrane Proteins / Q000502:physiology*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics; D017933:Peripheral Nervous System / Q000254:growth & development; D011401:Promoter Regions, Genetic; D051880:Receptors, Notch; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic; D014921:Wings, Animal / Q000254:growth & development
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D007301:Insect Hormones; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D051880:Receptors, Notch; D012097:Repressor Proteins; C084530:E(spl)mdelta-HLH protein, Drosophila; C497759:N protein, Drosophila; C088731:Su(H) protein, Drosophila