title: Transcriptional dynamics elicited by a short pulse of notch activation involves feed-forward regulation by E(spl)/Hes genes.
abstract: Dynamic activity of signaling pathways, such as Notch, is vital to achieve correct development and homeostasis. However, most studies assess output many hours or days after initiation of signaling, once the outcome has been consolidated. Here we analyze genome-wide changes in transcript levels, binding of the Notch pathway transcription factor, CSL [Suppressor of Hairless, Su(H), in Drosophila], and RNA Polymerase II (Pol II) immediately following a short pulse of Notch stimulation. A total of 154 genes showed significant differential expression (DE) over time, and their expression profiles stratified into 14 clusters based on the timing, magnitude, and direction of DE. E(spl) genes were the most rapidly upregulated, with Su(H), Pol II, and transcript levels increasing within 5-10 minutes. Other genes had a more delayed response, the timing of which was largely unaffected by more prolonged Notch activation. Neither Su(H) binding nor poised Pol II could fully explain the differences between profiles. Instead, our data indicate that regulatory interactions, driven by the early-responding E(spl)bHLH genes, are required. Proposed cross-regulatory relationships were validated in vivo and in cell culture, supporting the view that feed-forward repression by E(spl)bHLH/Hes shapes the response of late-responding genes. Based on these data, we propose a model in which Hes genes are responsible for co-ordinating the Notch response of a wide spectrum of other targets, explaining the critical functions these key regulators play in many developmental and disease contexts.
authors.affiliation: Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Ben E
authors.initials: BE
authors.lastname: Housden
authors.forename: Audrey Q
authors.initials: AQ
authors.lastname: Fu
authors.forename: Alena
authors.initials: A
authors.lastname: Krejci
authors.forename: Fred
authors.initials: F
authors.lastname: Bernard
authors.forename: Bettina
authors.initials: B
authors.lastname: Fischer
authors.forename: Simon
authors.initials: S
authors.lastname: Tavaré
authors.forename: Steven
authors.initials: S
authors.lastname: Russell
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Bray
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D017124:Conserved Sequence / Q000235:genetics; D004268:DNA-Binding Proteins; D004330:Drosophila / Q000235:genetics / Q000254:growth & development; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D012319:RNA Polymerase II; D051880:Receptors, Notch; D012097:Repressor Proteins; C121960:E(spl)m7-HLH protein, Drosophila; C497759:N protein, Drosophila