The making of a Barr body: the mosaic of factors that eXIST on the mammalian inactive X chromosome.
During X-chromosome inactivation (XCI), nearly an entire X chromosome is permanently silenced and converted into a Barr body, providing dosage compensation for eutherians between the sexes. XCI is facilitated by the upregulation of the long non-coding RNA gene, XIST, which coats its chromosome of origin, recruits heterochromatin factors, and silences gene expression. During XCI, at least two distinct types of heterochromatin are established, and in this review we discuss the enrichment of facultative heterochromatin marks such as H3K27me3, H2AK119ub, and macroH2A as well as pericentric heterochromatin marks such as HP1, H3K9me3, and H4K20me3. The extremely stable maintenance of silencing is a product of reinforcing interactions within and between these domains. This paper "Xplores" the current knowledge of the pathways involved in XCI, how the pathways interact, and the gaps in our understanding that need to be filled.
Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.|Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
Thomas
T
Dixon-McDougall
Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.|Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
Carolyn
C
Brown
D000107:Acetylation; D000818:Animals; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D020868:Gene Silencing; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D051379:Mice; D063146:Polycomb-Group Proteins / Q000378:metabolism*; D062085:RNA, Long Noncoding / Q000235:genetics / Q000378:metabolism*; D012728:Sex Chromatin / Q000235:genetics / Q000378:metabolism*; D014960:X Chromosome / Q000235:genetics* / Q000378:metabolism; D049951:X Chromosome Inactivation
D004268:DNA-Binding Proteins; D006657:Histones; D063146:Polycomb-Group Proteins; D062085:RNA, Long Noncoding; C077885:XIST non-coding RNA; D004248:DNA (Cytosine-5-)-Methyltransferases; D006655:Histone Deacetylases
X-chromosome Inactivation (XCI); XIST; epigenetics; gene silencing; heterochromatin; hétérochromatine; inactivation du chromosome X; silençage génique; épigénétique