title: Gene silencing triggers polycomb repressive complex 2 recruitment to CpG islands genome wide.
abstract: Polycomb group (PcG) proteins are required for normal differentiation and development and are frequently deregulated in cancer. PcG proteins are involved in gene silencing; however, their role in initiation and maintenance of transcriptional repression is not well defined. Here, we show that knockout of the Polycomb repressive complex 2 (PRC2) does not lead to significant gene expression changes in mouse embryonic stem cells (mESCs) and that it is dispensable for initiating silencing of target genes during differentiation. Transcriptional inhibition in mESCs is sufficient to induce genome-wide ectopic PRC2 recruitment to endogenous PcG target genes found in other tissues. PRC2 binding analysis shows that it is restricted to nucleosome-free CpG islands (CGIs) of untranscribed genes. Our results show that it is the transcriptional state that governs PRC2 binding, and we propose that it binds by default to nontranscribed CGI genes to maintain their silenced state and to protect cell identity.
authors.affiliation: Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark; Centre for Epigenetics, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark.
authors.forename: Eva Madi
authors.initials: EM
authors.lastname: Riising
authors.affiliation: Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark; Centre for Epigenetics, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark.
authors.forename: Itys
authors.initials: I
authors.lastname: Comet
authors.affiliation: Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark; Centre for Epigenetics, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark; The Danish Stem Cell Center (DanStem), Blegdamsvej 3, 2200 Copenhagen, Denmark.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Leblanc
authors.affiliation: Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark; Centre for Epigenetics, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark.
authors.forename: Xudong
authors.initials: X
authors.lastname: Wu
authors.affiliation: Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark; The Bioinformatics Centre, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark.
authors.forename: Jens Vilstrup
authors.initials: JV
authors.lastname: Johansen
authors.affiliation: Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark; Centre for Epigenetics, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark; The Danish Stem Cell Center (DanStem), Blegdamsvej 3, 2200 Copenhagen, Denmark. Electronic address: kristian.helin@bric.ku.dk.
authors.forename: Kristian
authors.initials: K
authors.lastname: Helin
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D018899:CpG Islands; D004004:Dichlororibofuranosylbenzimidazole / Q000494:pharmacology; D004224:Diterpenes / Q000494:pharmacology; D053595:Embryonic Stem Cells / Q000378:metabolism*; D044127:Epigenesis, Genetic; D004852:Epoxy Compounds / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D055786:Gene Knockout Techniques; D020868:Gene Silencing / Q000187:drug effects; D016678:Genome; D051379:Mice; D009707:Nucleosomes / Q000235:genetics* / Q000378:metabolism*; D010616:Phenanthrenes / Q000494:pharmacology; D063151:Polycomb Repressive Complex 2 / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics / Q000502:physiology
chemical_list: D004224:Diterpenes; D004852:Epoxy Compounds; D009707:Nucleosomes; D010616:Phenanthrenes; C001899:triptolide; D004004:Dichlororibofuranosylbenzimidazole; D063151:Polycomb Repressive Complex 2