LINE-1 activity in facultative heterochromatin formation during X chromosome inactivation.
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.
Chow
Jennifer C
JC
Institut Curie, Paris F-75248, France.
Ciaudo
Constance
C
Fazzari
Melissa J
MJ
Mise
Nathan
N
Servant
Nicolas
N
Glass
Jacob L
JL
Attreed
Matthew
M
Avner
Philip
P
Wutz
Anton
A
Barillot
Emmanuel
E
Greally
John M
JM
Voinnet
Olivier
O
Heard
Edith
E
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
D006570:Heterochromatin; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; C077885:XIST non-coding RNA