title: Groucho acts as a corepressor for a subset of negative regulators, including Hairy and Engrailed.
abstract: Relatively little is known about the molecular mechanisms involved in transcriptional repression, despite its importance in development and differentiation. Recent evidence suggests that some transcriptional repressors act by way of adaptor molecules known as corepressors. Here, we use in vivo functional assays to test whether different repressor activities are mediated by the Groucho (Gro) corepressor in the Drosophila embryo. Previously, Gro was proposed to mediate repression by the Hairy-related family of basic helix-loop-helix proteins. Our results indicate not only that repression by Hairy requires Gro, but that a repressor domain from the Engrailed (En) homeodomain protein is also Gro dependent. The latter result correlates with an ability of this En domain to bind to Gro in vitro. In contrast, repressor regions from the Even-skipped, Snail, Krüppel, and Knirps transcription factors are effective in the absence of Gro. These results show that Gro is not generally required for repression, but acts as a specific corepressor for a fraction of negative regulators, including Hairy and En.
authors.affiliation: Imperial Cancer Research Fund (ICRF), London WC2A 3PX, England.
authors.forename: G
authors.initials: G
authors.lastname: Jiménez
authors.forename: Z
authors.initials: Z
authors.lastname: Paroush
authors.forename: D
authors.initials: D
authors.lastname: Ish-Horowicz
mesh_terms: D000818:Animals; D001426:Bacterial Proteins; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins / Q000502:physiology*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018257:Helix-Loop-Helix Motifs; D018398:Homeodomain Proteins / Q000502:physiology*; D019476:Insect Proteins / Q000502:physiology*; D046911:Macromolecular Substances; D011485:Protein Binding; D016601:RNA-Binding Proteins / Q000235:genetics; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins / Q000502:physiology*; D014157:Transcription Factors
chemical_list: D001426:Bacterial Proteins; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D046911:Macromolecular Substances; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C067777:Sxl protein, Drosophila; C106185:engrailed homeobox proteins; C052837:eve protein, Drosophila; C091023:gro protein, Drosophila; C489235:hairy protein, Drosophila; C061841:hairy protein, insect