title: LINE-1 activity in facultative heterochromatin formation during X chromosome inactivation.
abstract: During X chromosome inactivation (XCI), Xist RNA coats and silences one of the two X chromosomes in female cells. Little is known about how XCI spreads across the chromosome, although LINE-1 elements have been proposed to play a role. Here we show that LINEs participate in creating a silent nuclear compartment into which genes become recruited. A subset of young LINE-1 elements, however, is expressed during XCI, rather than being silenced. We demonstrate that such LINE expression requires the specific heterochromatic state induced by Xist. These LINEs often lie within escape-prone regions of the X chromosome, but close to genes that are subject to XCI, and are associated with putative endo-siRNAs. LINEs may thus facilitate XCI at different levels, with silent LINEs participating in assembly of a heterochromatic nuclear compartment induced by Xist, and active LINEs participating in local propagation of XCI into regions that would otherwise be prone to escape.
authors.affiliation: Institut Curie, Paris F-75248, France.
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Chow
authors.forename: Constance
authors.initials: C
authors.lastname: Ciaudo
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Fazzari
authors.forename: Nathan
authors.initials: N
authors.lastname: Mise
authors.forename: Nicolas
authors.initials: N
authors.lastname: Servant
authors.forename: Jacob L
authors.initials: JL
authors.lastname: Glass
authors.forename: Matthew
authors.initials: M
authors.lastname: Attreed
authors.forename: Philip
authors.initials: P
authors.lastname: Avner
authors.forename: Anton
authors.initials: A
authors.lastname: Wutz
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Barillot
authors.forename: John M
authors.initials: JM
authors.lastname: Greally
authors.forename: Olivier
authors.initials: O
authors.lastname: Voinnet
authors.forename: Edith
authors.initials: E
authors.lastname: Heard
mesh_terms: D000818:Animals; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000378:metabolism; D005260:Female; D006570:Heterochromatin / Q000378:metabolism*; D006801:Humans; D020084:Long Interspersed Nucleotide Elements; D051379:Mice; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000378:metabolism; D014158:Transcription, Genetic; D014960:X Chromosome / Q000378:metabolism; D049951:X Chromosome Inactivation
chemical_list: D006570:Heterochromatin; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; C077885:XIST non-coding RNA