title: Distinct in vivo requirements for establishment versus maintenance of transcriptional repression.
abstract: Low-level ectopic expression of the Runt transcription factor blocks activation of the Drosophila melanogaster segmentation gene engrailed (en) in odd-numbered parasegments and is associated with a lethal phenotype. Here we show, by using a genetic screen for maternal factors that contribute in a dose-dependent fashion to Runt-mediated repression, that there are two distinct steps in the repression of en by Runt. The initial establishment of repression is sensitive to the dosage of the zinc-finger transcription factor Tramtrack. By contrast, the co-repressor proteins Groucho and dCtBP, and the histone deacetylase Rpd3, do not affect establishment but instead maintain repression after the blastoderm stage. The distinction between establishment and maintenance is confirmed by experiments with Runt derivatives that are impaired specifically for either co-repressor interaction or DNA binding. Other transcription factors can also establish repression in Rpd3-deficient embryos, which indicates that the distinction between establishment and maintenance may be a general feature of eukaryotic transcriptional repression.
authors.affiliation: Department of Biochemistry and Cell Biology and the Center for Developmental Genetics, Stony Brook University, Stony Brook, New York 11794-5140, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Wheeler
authors.forename: Christine
authors.initials: C
authors.lastname: VanderZwan
authors.forename: Xiaoti
authors.initials: X
authors.lastname: Xu
authors.forename: Deborah
authors.initials: D
authors.lastname: Swantek
authors.forename: W Daniel
authors.initials: WD
authors.lastname: Tracey
authors.forename: J Peter
authors.initials: JP
authors.lastname: Gergen
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D020868:Gene Silencing / Q000502:physiology*; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases; D018398:Homeodomain Proteins / Q000235:genetics*; D008297:Male; D009687:Nuclear Proteins; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C063459:En protein, Drosophila; C091023:gro protein, Drosophila; C080833:run protein, Drosophila; C075878:ttk protein, Drosophila; C512966:HDAC1 protein, Drosophila