title: Transcriptional gene silencing by Arabidopsis microrchidia homologues involves the formation of heteromers.
abstract: Epigenetic gene silencing is of central importance to maintain genome integrity and is mediated by an elaborate interplay between DNA methylation, histone posttranslational modifications, and chromatin remodeling complexes. DNA methylation and repressive histone marks usually correlate with transcriptionally silent heterochromatin, however there are exceptions to this relationship. In Arabidopsis, mutation of Morpheus Molecule 1 (MOM1) causes transcriptional derepression of heterochromatin independently of changes in DNA methylation. More recently, two Arabidopsis homologues of mouse microrchidia (MORC) genes have also been implicated in gene silencing and heterochromatin condensation without altering genome-wide DNA methylation patterns. In this study, we show that Arabidopsis microrchidia (AtMORC6) physically interacts with AtMORC1 and with its close homologue, AtMORC2, in two mutually exclusive protein complexes. RNA-sequencing analyses of high-order mutants indicate that AtMORC1 and AtMORC2 act redundantly to repress a common set of loci. We also examined genetic interactions between AtMORC6 and MOM1 pathways. Although AtMORC6 and MOM1 control the silencing of a very similar set of genomic loci, we observed synergistic transcriptional regulation in the mom1/atmorc6 double mutant, suggesting that these epigenetic regulators act mainly by different silencing mechanisms.
authors.affiliation: Department of Molecular, Cell and Developmental Biology and.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Moissiard
authors.affiliation: Department of Molecular, Cell and Developmental Biology and.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bischof
authors.affiliation: Department of Molecular, Cell and Developmental Biology and.
authors.forename: Dylan
authors.initials: D
authors.lastname: Husmann
authors.affiliation: Department of Molecular, Cell and Developmental Biology and.
authors.forename: William A
authors.initials: WA
authors.lastname: Pastor
authors.affiliation: Department of Molecular, Cell and Developmental Biology and.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Hale
authors.affiliation: Department of Molecular, Cell and Developmental Biology and.
authors.forename: Linda
authors.initials: L
authors.lastname: Yen
authors.affiliation: Department of Molecular, Cell and Developmental Biology and.
authors.forename: Hume
authors.initials: H
authors.lastname: Stroud
authors.affiliation: Department of Molecular, Cell and Developmental Biology and.
authors.forename: Ashot
authors.initials: A
authors.lastname: Papikian
authors.affiliation: Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095.
authors.forename: Ajay A
authors.initials: AA
authors.lastname: Vashisht
authors.affiliation: Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095.
authors.forename: James A
authors.initials: JA
authors.lastname: Wohlschlegel
authors.affiliation: Department of Molecular, Cell and Developmental Biology andHoward Hughes Medical Institute, University of California, Los Angeles, CA 90095; and jacobsen@ucla.edu.
authors.forename: Steven E
authors.initials: SE
authors.lastname: Jacobsen
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics*; D019175:DNA Methylation; D004251:DNA Transposable Elements; D044127:Epigenesis, Genetic; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D005838:Genotype; D006570:Heterochromatin / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding
chemical_list: D029681:Arabidopsis Proteins; D004251:DNA Transposable Elements; D006570:Heterochromatin; D000251:Adenosine Triphosphatases; C573242:MORC1 protein, Arabidopsis; C000589492:MORC2 protein, Arabidopsis; C573243:MORC6 protein, Arabidopsis
keywords: epigenetics; plant biology