title: The transcriptional repressor NIPP1 is an essential player in EZH2-mediated gene silencing.
abstract: EZH2 is a Polycomb group (PcG) protein that promotes the late-stage development of cancer by silencing a specific set of genes, at least in part through trimethylation of associated histone H3 on Lys 27 (H3K27). Nuclear inhibitor of protein phosphatase-1 (NIPP1) is a ubiquitously expressed transcriptional repressor that has binding sites for the EZH2 interactor EED. Here, we examine the contribution of NIPP1 to EZH2-mediated gene silencing. Studies on NIPP1-deficient cells disclose a widespread and essential role of NIPP1 in the trimethylation of H3K27 by EZH2, not only in the onset of this trimethylation during embryonic development, but also in the maintenance of this repressive mark in proliferating cells. Consistent with this notion, EZH2 and NIPP1 silence a common set of genes, as revealed by gene-expression profiling, and NIPP1 is associated with established Polycomb target genes and with genomic regions that are enriched in Polycomb targets. Furthermore, most NIPP1 target genes are trimethylated on H3K27 and the knockdown of either NIPP1 or EZH2 is often associated with a loss of this modification. Our data reveal that NIPP1 is required for the global trimethylation of H3K27 and is implicated in gene silencing by EZH2.
authors.affiliation: Laboratory of Biosignaling & Therapeutics, Department of Molecular Cell Biology, Faculty of Medicine, KULeuven, Leuven, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Nuytten
authors.forename: L
authors.initials: L
authors.lastname: Beke
authors.forename: A
authors.initials: A
authors.lastname: Van Eynde
authors.forename: H
authors.initials: H
authors.lastname: Ceulemans
authors.forename: M
authors.initials: M
authors.lastname: Beullens
authors.forename: P
authors.initials: P
authors.lastname: Van Hummelen
authors.forename: F
authors.initials: F
authors.lastname: Fuks
authors.forename: M
authors.initials: M
authors.lastname: Bollen
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000502:physiology*; D004722:Endoribonucleases / Q000502:physiology*; D000071221:Enhancer of Zeste Homolog 2 Protein; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D020868:Gene Silencing / Q000502:physiology*; D006367:HeLa Cells; D011495:Histone-Lysine N-Methyltransferase / Q000502:physiology; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008239:Lysine / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D009687:Nuclear Proteins / Q000502:physiology; D010749:Phosphoprotein Phosphatases / Q000502:physiology*; D063151:Polycomb Repressive Complex 2; D063146:Polycomb-Group Proteins; D016601:RNA-Binding Proteins / Q000502:physiology*; D012097:Repressor Proteins / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; D006657:Histones; D009687:Nuclear Proteins; D063146:Polycomb-Group Proteins; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D011495:Histone-Lysine N-Methyltransferase; D063151:Polycomb Repressive Complex 2; D004722:Endoribonucleases; D010749:Phosphoprotein Phosphatases; C097081:PPP1R8 protein, human; D008239:Lysine