title: A role of Pygopus as an anti-repressor in facilitating Wnt-dependent transcription.
abstract: Wnt/beta-catenin signaling controls animal development and tissue homeostasis, and is also an important cancer pathway. Pygopus (Pygo) is a conserved nuclear Wnt signaling component that is essential for Wingless-induced transcription throughout Drosophila development. It associates with Armadillo/beta-catenin and T cell factor (TCF) through the Legless/BCL9 adaptor, but its molecular function in TCF-mediated transcription is unknown. Here, we use a groucho-null allele to show that Groucho represses Wingless target genes during Drosophila development. Interestingly, groucho pygo double-mutants revealed that Pygo is not obligatory for transcriptional and phenotypic Wingless signaling outputs if the interaction between Groucho and Drosophila TCF is compromised genetically. Pygo function is also non-essential for Wingless outputs in the absence of other transcriptional antagonists of Wingless signaling. This indicates an anti-repressor function of Pygo: we propose that Pygo predisposes Drosophila TCF target genes for rapid Wingless-induced transcription, or that it protects them against premature shut-down.
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom.
authors.forename: Juliusz
authors.initials: J
authors.lastname: Mieszczanek
authors.forename: Marc
authors.initials: M
authors.lastname: de la Roche
authors.forename: Mariann
authors.initials: M
authors.lastname: Bienz
mesh_terms: D000818:Animals; D051186:Armadillo Domain Proteins / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D004440:Ecdysone / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D012097:Repressor Proteins / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology; D051153:Wnt Proteins / Q000378:metabolism*; D051155:Wnt1 Protein / Q000378:metabolism
chemical_list: D051186:Armadillo Domain Proteins; D051792:Basic Helix-Loop-Helix Proteins; D029721:Drosophila Proteins; D004440:Ecdysone; D047908:Intracellular Signaling Peptides and Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D051153:Wnt Proteins; D051155:Wnt1 Protein; C495305:ARM protein, Drosophila; C091023:gro protein, Drosophila; C453400:pygo protein, Drosophila; C074622:wg protein, Drosophila