LINE-1 Activity in Facultative Heterochromatin Formation during X Chromosome Inactivation

作者：Chow Jennifer C; Ciaudo Constance; Fazzari Melissa J; Mise Nathan; Servant Nicolas; Glass Jacob L; Attreed Matthew; Avner Philip; Wutz Anton; Barillot Emmanuel; Greally John M; Voinnet Olivier; Heard Edith^*

来源：Cell, 2010, 141(6): 956-969.

DOI：10.1016/j.cell.2010.04.042

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.

• 出版日期2010-6-11