title: Transcription factor YY1 functions as a PcG protein in vivo.
abstract: Polycomb group (PcG) proteins function as high molecular weight complexes that maintain transcriptional repression patterns during embryogenesis. The vertebrate DNA binding protein and transcriptional repressor, YY1, shows sequence homology with the Drosophila PcG protein, pleiohomeotic (PHO). YY1 might therefore be a vertebrate PcG protein. We used Drosophila embryo and larval/imaginal disc transcriptional repression systems to determine whether YY1 repressed transcription in a manner consistent with PcG function in vivo. YY1 repressed transcription in Drosophila, and this repression was stable on a PcG-responsive promoter, but not on a PcG-non-responsive promoter. PcG mutants ablated YY1 repression, and YY1 could substitute for PHO in repressing transcription in wing imaginal discs. YY1 functionally compensated for loss of PHO in pho mutant flies and partially corrected mutant phenotypes. Taken together, these results indicate that YY1 functions as a PcG protein. Finally, we found that YY1, as well as Polycomb, required the co-repressor protein CtBP for repression in vivo. These results provide a mechanism for recruitment of vertebrate PcG complexes to DNA and demonstrate new functions for YY1.
authors.affiliation: Department of Biology, Chestnut Hill College, 9601 Germantown Avenue, Philadelphia, PA 19118, USA. atchison@vet.upenn.edu
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Atchison
authors.forename: Ayesha
authors.initials: A
authors.lastname: Ghias
authors.forename: Frank
authors.initials: F
authors.lastname: Wilkinson
authors.forename: Nancy
authors.initials: N
authors.lastname: Bonini
authors.forename: Michael L
authors.initials: ML
authors.lastname: Atchison
mesh_terms: D000429:Alcohol Oxidoreductases; D000818:Animals; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000196:embryology; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian; D050981:Erythroid-Specific DNA-Binding Factors; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000737:chemistry / Q000378:metabolism; D007814:Larva; D008954:Models, Biological; D009154:Mutation; D010641:Phenotype; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D063150:Polycomb Repressive Complex 1; D063146:Polycomb-Group Proteins; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D019076:Transgenes; D050986:YY1 Transcription Factor
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D018398:Homeodomain Proteins; C066770:Pc protein, Drosophila; D010750:Phosphoproteins; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D050986:YY1 Transcription Factor; C113295:pho protein, Drosophila; C471858:phol protein, Drosophila; D000429:Alcohol Oxidoreductases; C096794:C-terminal binding protein; D063150:Polycomb Repressive Complex 1