Silencing of the mammalian X chromosome.
Mammalian X chromosome inactivation is one of the most striking examples of epigenetic gene regulation. Early in development one of the pair of approximately 160-Mb X chromosomes is chosen to be silenced, and this silencing is then stably inherited through subsequent somatic cell divisions. Recent advances have revealed many of the chromatin changes that underlie this stable silencing of an entire chromosome. The key initiator of these changes is a functional RNA, XIST, which is transcribed from, and associates with, the inactive X chromosome, although the mechanism of association with the inactive X and recruitment of facultative heterochromatin remain to be elucidated. This review describes the unique evolutionary history and resulting genomic structure of the X chromosome as well as the current understanding of the factors and events involved in silencing an X chromosome in mammals.
Chow
Jennifer C
JC
Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada. jchrista@interchange.ubc.ca
Yen
Ziny
Z
Ziesche
Sonia M
SM
Brown
Carolyn J
CJ
D000818:Animals; D005075:Biological Evolution; D041321:Chromosomes, Human, X / Q000235:genetics; D005260:Female; D020868:Gene Silencing; D006570:Heterochromatin / Q000235:genetics; D006801:Humans; D008297:Male; D051379:Mice; D008957:Models, Genetic; D011544:Pseudogenes; D012091:Repetitive Sequences, Nucleic Acid; D013091:Spermatogenesis / Q000235:genetics; D014178:Translocation, Genetic; D014960:X Chromosome / Q000235:genetics*; D049951:X Chromosome Inactivation
D006570:Heterochromatin