title: Panspecies small-molecule disruptors of heterochromatin-mediated transcriptional gene silencing.
abstract: Heterochromatin underpins gene repression, genome integrity, and chromosome segregation. In the fission yeast Schizosaccharomyces pombe, conserved protein complexes effect heterochromatin formation via RNA interference-mediated recruitment of a histone H3 lysine 9 methyltransferase to cognate chromatin regions. To identify small molecules that inhibit heterochromatin formation, we performed an in vivo screen for loss of silencing of a dominant selectable kanMX reporter gene embedded within fission yeast centromeric heterochromatin. Two structurally unrelated compounds, HMS-I1 and HMS-I2, alleviated kanMX silencing and decreased repressive H3K9 methylation levels at the transgene. The decrease in methylation caused by HMS-I1 and HMS-I2 was observed at all loci regulated by histone methylation, including centromeric repeats, telomeric regions, and the mating-type locus, consistent with inhibition of the histone deacetylases (HDACs) Clr3 and/or Sir2. Chemical-genetic epistasis and expression profiles revealed that both compounds affect the activity of the Clr3-containing Snf2/HDAC repressor complex (SHREC). In vitro HDAC assays revealed that HMS-I1 and HMS-I2 inhibit Clr3 HDAC activity. HMS-I1 also alleviated transgene reporter silencing by heterochromatin in Arabidopsis and a mouse cell line, suggesting a conserved mechanism of action. HMS-I1 and HMS-I2 bear no resemblance to known inhibitors of chromatin-based activities and thus represent novel chemical probes for heterochromatin formation and function.
authors.affiliation: Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Emilie
authors.initials: E
authors.lastname: Castonguay
authors.affiliation: Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Sharon A
authors.initials: SA
authors.lastname: White
authors.affiliation: MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kagansky
authors.affiliation: Institute for Research in Immunology and Cancer, Department of Medicine, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: St-Cyr
authors.affiliation: Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Area de Genética, Campus de Teatinos, Málaga, Spain.
authors.forename: Araceli G
authors.initials: AG
authors.lastname: Castillo
authors.affiliation: Department of Molecular Biology, Science III, Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland.
authors.forename: Christiane
authors.initials: C
authors.lastname: Brugger
authors.affiliation: Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Rachel
authors.initials: R
authors.lastname: White
authors.affiliation: Department of Biosciences and Nutrition, Karolinska Institutet, Novum, Huddinge, Sweden.
authors.forename: Carolina
authors.initials: C
authors.lastname: Bonilla
authors.affiliation: Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Michaela
authors.initials: M
authors.lastname: Spitzer
authors.affiliation: Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: William C
authors.initials: WC
authors.lastname: Earnshaw
authors.affiliation: Department of Molecular Biology, Science III, Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schalch
authors.affiliation: Department of Biosciences and Nutrition, Karolinska Institutet, Novum, Huddinge, Sweden.
authors.forename: Karl
authors.initials: K
authors.lastname: Ekwall
authors.affiliation: Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom Institute for Research in Immunology and Cancer, Department of Medicine, Université de Montréal, Montréal, Québec, Canada md.tyers@umontreal.ca robin.allshire@ed.ac.uk.
authors.forename: Mike
authors.initials: M
authors.lastname: Tyers
authors.affiliation: Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom md.tyers@umontreal.ca robin.allshire@ed.ac.uk.
authors.forename: Robin C
authors.initials: RC
authors.lastname: Allshire
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D042002:Chromatin Assembly and Disassembly; D019175:DNA Methylation; D004146:Dioxanes / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects*; D020868:Gene Silencing / Q000187:drug effects*; D006570:Heterochromatin / Q000737:chemistry / Q000187:drug effects*; D006574:Heterocyclic Compounds, 2-Ring / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism; D006657:Histones / Q000235:genetics / Q000378:metabolism; D051379:Mice; D010879:Piperazines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D012568:Schizosaccharomyces / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D013876:Thiophenes / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*
chemical_list: C000596711:2-(2,3-dihydrobenzo(b)(1,4)dioxin-6-yl)-6-methylimidazo(1,2-a)pyridine; D018797:Cell Cycle Proteins; C115302:Clr3 protein, S pombe; D004146:Dioxanes; D006570:Heterochromatin; D006574:Heterocyclic Compounds, 2-Ring; D006657:Histones; C000596712:N-(benzo(b)thiophen-2-yl)-4-(2-chloro-6-fluorobenzyl)piperazine-1-carboxamide; D010879:Piperazines; D011725:Pyridines; D029702:Schizosaccharomyces pombe Proteins; D013876:Thiophenes; C526400:sir2 protein, S pombe; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase