title: G9a/GLP-dependent histone H3K9me2 patterning during human hematopoietic stem cell lineage commitment.
abstract: G9a and GLP are conserved protein methyltransferases that play key roles during mammalian development through mono- and dimethylation of histone H3 Lys 9 (H3K9me1/2), modifications associated with transcriptional repression. During embryogenesis, large H3K9me2 chromatin territories arise that have been proposed to reinforce lineage choice by affecting high-order chromatin structure. Here we report that in adult human hematopoietic stem and progenitor cells (HSPCs), H3K9me2 chromatin territories are absent in primitive cells and are formed de novo during lineage commitment. In committed HSPCs, G9a/GLP activity nucleates H3K9me2 marks at CpG islands and other genomic sites within genic regions, which then spread across most genic regions during differentiation. Immunofluorescence assays revealed the emergence of H3K9me2 nuclear speckles in committed HSPCs, consistent with progressive marking. Moreover, gene expression analysis indicated that G9a/GLP activity suppresses promiscuous transcription of lineage-affiliated genes and certain gene clusters, suggestive of regulation of HSPC chromatin structure. Remarkably, HSPCs continuously treated with UNC0638, a G9a/GLP small molecular inhibitor, better retain stem cell-like phenotypes and function during in vitro expansion. These results suggest that G9a/GLP activity promotes progressive H3K9me2 patterning during HSPC lineage specification and that its inhibition delays HSPC lineage commitment. They also inform clinical manipulation of donor-derived HSPCs.
authors.affiliation: Molecular and Cell Biology (MCB) Program, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
authors.forename: Xiaoji
authors.initials: X
authors.lastname: Chen
authors.forename: Kyobi
authors.initials: K
authors.lastname: Skutt-Kakaria
authors.forename: Jerry
authors.initials: J
authors.lastname: Davison
authors.forename: Yang-Li
authors.initials: YL
authors.lastname: Ou
authors.forename: Edward
authors.initials: E
authors.lastname: Choi
authors.forename: Punam
authors.initials: P
authors.lastname: Malik
authors.forename: Keith
authors.initials: K
authors.lastname: Loeb
authors.forename: Brent
authors.initials: B
authors.lastname: Wood
authors.forename: George
authors.initials: G
authors.lastname: Georges
authors.forename: Beverly
authors.initials: B
authors.lastname: Torok-Storb
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Paddison
mesh_terms: D000328:Adult; D000818:Animals; D002454:Cell Differentiation; D019070:Cell Lineage; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D006649:Histocompatibility Antigens / Q000235:genetics / Q000378:metabolism*; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D051379:Mice; D011799:Quinazolines / Q000494:pharmacology
chemical_list: D002843:Chromatin; D004791:Enzyme Inhibitors; D006649:Histocompatibility Antigens; D006657:Histones; D011799:Quinazolines; C561310:UNC 0638; C455847:EHMT1 protein, human; C445405:EHMT2 protein, human; D011495:Histone-Lysine N-Methyltransferase