title: Prdm3 and Prdm16 are H3K9me1 methyltransferases required for mammalian heterochromatin integrity.
abstract: Heterochromatin serves important functions, protecting genome integrity and stabilizing gene expression programs. Although the Suv39h methyltransferases (KMTs) are known to ensure pericentric H3K9me3 methylation, the mechanisms that initiate and maintain mammalian heterochromatin organization remain elusive. We developed a biochemical assay and used in vivo analyses in mouse embryonic fibroblasts to identify Prdm3 and Prdm16 as redundant H3K9me1-specific KMTs that direct cytoplasmic H3K9me1 methylation. The H3K9me1 is converted in the nucleus to H3K9me3 by the Suv39h enzymes to reinforce heterochromatin. Simultaneous depletion of Prdm3 and Prdm16 abrogates H3K9me1 methylation, prevents Suv39h-dependent H3K9me3 trimethylation, and derepresses major satellite transcription. Most strikingly, DNA-FISH and electron microscopy reveal that combined impairment of Prdm3 and Prdm16 results in disintegration of heterochromatic foci and disruption of the nuclear lamina. Our data identify Prdm3 and Prdm16 as H3K9me1 methyltransferases and expose a functional framework in which anchoring to the nuclear periphery helps maintain the integrity of mammalian heterochromatin.
authors.affiliation: Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany.
authors.forename: Inês
authors.initials: I
authors.lastname: Pinheiro
authors.forename: Raphaël
authors.initials: R
authors.lastname: Margueron
authors.forename: Nicholas
authors.initials: N
authors.lastname: Shukeir
authors.forename: Michael
authors.initials: M
authors.lastname: Eisold
authors.forename: Christoph
authors.initials: C
authors.lastname: Fritzsch
authors.forename: Florian M
authors.initials: FM
authors.lastname: Richter
authors.forename: Gerhard
authors.initials: G
authors.lastname: Mittler
authors.forename: Christel
authors.initials: C
authors.lastname: Genoud
authors.forename: Susumu
authors.initials: S
authors.lastname: Goyama
authors.forename: Mineo
authors.initials: M
authors.lastname: Kurokawa
authors.forename: Jinsook
authors.initials: J
authors.lastname: Son
authors.forename: Danny
authors.initials: D
authors.lastname: Reinberg
authors.forename: Monika
authors.initials: M
authors.lastname: Lachner
authors.forename: Thomas
authors.initials: T
authors.lastname: Jenuwein
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D055786:Gene Knockout Techniques; D006367:HeLa Cells; D006570:Heterochromatin; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D000074008:MDS1 and EVI1 Complex Locus Protein; D051379:Mice; D034881:Nuclear Lamina / Q000378:metabolism; D011519:Proto-Oncogenes; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D006570:Heterochromatin; D006657:Histones; D000074008:MDS1 and EVI1 Complex Locus Protein; C063575:MECOM protein, human; C416371:PRDM16 protein, human; C521133:Prdm16 protein, mouse; D014157:Transcription Factors; D011495:Histone-Lysine N-Methyltransferase