Structural organization of the inactive X chromosome in the mouse

Author: Luca Giorgetti, Bryan R. Lajoie, Ava C. Carter, Mikael Attia, Ye Zhan, Jin Xu, Chong Jian Chen, Noam Kaplan, Howard Y. Chang, Edith Heard & Job Dekker
Date Published: July-2016
Source: Nature

X-chromosome inactivation (XCI) involves major reorganization of the X chromosome as it becomes silent and heterochromatic. During female mammalian development, XCI is triggered by upregulation of the non-coding Xist RNA from one of the two X chromosomes. Xist coats the chromosome in cis and induces silencing of almost all genes via its A-repeat region1, 2, although some genes (constitutive escapees) avoid silencing in most cell types, and others (facultative escapees) escape XCI only in specific contexts3. A role for Xist in organizing the inactive X (Xi) chromosome has been proposed4, 5, 6. Recent chromosome conformation capture approaches have revealed global loss of local structure on the Xi chromosome and formation of large mega-domains, separated by a region containing the DXZ4 macrosatellite.