The Drosophila Smad cofactor Schnurri engages in redundant and synergistic  interactions with multiple corepressors.
In Drosophila a large zinc finger protein, Schnurri, functions as a Smad cofactor required for repression of brinker and other negative targets in response to signaling by the transforming growth factor beta ligand, Decapentaplegic. Schnurri binds to the silencer-bound Smads through a cluster of zinc fingers located near its carboxy-terminus and silences via a separate repression domain adjacent to this zinc-finger cluster. Here we show that this repression domain functions through interaction with two corepressors, dCtBP and dSin3A, and that either interaction is sufficient for repression. We also report that Schnurri contains additional repression domains that function through interaction with dCtBP, Groucho, dSin3A and SMRTER. By testing for the ability to rescue a shn RNAi phenotype we provide evidence that these diverse repression domains are both cooperative and partially redundant. In addition we find that Shn harbors a region capable of transcriptional activation, consistent with evidence that Schnurri can function as an activator as well as a repressor.
Laboratory of Genetics, University of Wisconsin, 425G Henry Mall, Madison, WI 53706, USA.
Yi
Y
Cai
Allen
A
Laughon
D000429:Alcohol Oxidoreductases / Q000378:metabolism / Q000502:physiology; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism / Q000502:physiology; D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004330:Drosophila / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D017344:Genes, Insect; D017930:Genes, Reporter; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D056264:Sin3 Histone Deacetylase and Corepressor Complex; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D016335:Zinc Fingers / Q000235:genetics
D000429:Alcohol Oxidoreductases; D051792:Basic Helix-Loop-Helix Proteins; D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D056264:Sin3 Histone Deacetylase and Corepressor Complex; D014157:Transcription Factors; C099683:SIN3A transcription factor; C121508:Smr protein, Drosophila; C091023:gro protein, Drosophila; C094066:shn protein, Drosophila; C096794:C-terminal binding protein