title: Histone H3 lysine 9 methylation is an epigenetic imprint of facultative heterochromatin.
abstract: Post-translational modifications of histone amino termini are an important regulatory mechanism that induce transitions in chromatin structure, thereby contributing to epigenetic gene control and the assembly of specialized chromosomal subdomains. Methylation of histone H3 at lysine 9 (H3-Lys9) by site-specific histone methyltransferases (Suv39h HMTases) marks constitutive heterochromatin. Here, we show that H3-Lys9 methylation also occurs in facultative heterochromatin of the inactive X chromosome (Xi) in female mammals. H3-Lys9 methylation is retained through mitosis, indicating that it might provide an epigenetic imprint for the maintenance of the inactive state. Disruption of the two mouse Suv39h HMTases abolishes H3-Lys9 methylation of constitutive heterochromatin but not that of the Xi. In addition, HP1 proteins, which normally associate with heterochromatin, do not accumulate with the Xi. These observations suggest the existence of an Suv39h-HP1-independent pathway regulating H3-Lys9 methylation of facultative heterochromatin.
authors.affiliation: Research Institute of Molecular Pathology, The Vienna Biocenter, Dr. Bohrgasse 7, A-1030 Vienna, Austria.
authors.forename: Antoine H F M
authors.initials: AH
authors.lastname: Peters
authors.forename: Jacqueline E
authors.initials: JE
authors.lastname: Mermoud
authors.forename: Dónal
authors.initials: D
authors.lastname: O'Carroll
authors.forename: Michaela
authors.initials: M
authors.lastname: Pagani
authors.forename: Dieter
authors.initials: D
authors.lastname: Schweizer
authors.forename: Neil
authors.initials: N
authors.lastname: Brockdorff
authors.forename: Thomas
authors.initials: T
authors.lastname: Jenuwein
mesh_terms: D000649:Amniocentesis; D000782:Aneuploidy; D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured / Q000648:ultrastructure; D020223:Chromosome Painting; D002894:Chromosomes, Human, Pair 4 / Q000235:genetics; D004303:Dosage Compensation, Genetic; D005260:Female; D005347:Fibroblasts / Q000648:ultrastructure; D005786:Gene Expression Regulation; D006570:Heterochromatin / Q000737:chemistry* / Q000235:genetics; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; D006657:Histones / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives* / Q000737:chemistry*; D008297:Male; D008677:Metaphase; D008745:Methylation; D008780:Methyltransferases / Q000502:physiology; D051379:Mice; D008856:Microscopy, Fluorescence; D009061:Mouth Mucosa / Q000648:ultrastructure; D011233:Precipitin Tests; D011247:Pregnancy; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D011496:Protein Methyltransferases; D012097:Repressor Proteins / Q000502:physiology; D014178:Translocation, Genetic; D014960:X Chromosome / Q000235:genetics / Q000378:metabolism*
chemical_list: D006570:Heterochromatin; D006657:Histones; D020033:Protein Isoforms; D012097:Repressor Proteins; C049907:2-methyllysine; C407843:SUV39H1 protein, human; C498700:Suv39h1 protein, mouse; D000076983:Histone Methyltransferases; D008780:Methyltransferases; D011496:Protein Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; D008239:Lysine