AI Article Synopsis
- X chromosome inactivation (XCI) is a process where one of the two X chromosomes in female mammals is silenced to balance gene dosage with males.
- There are two types of XCI in mice: imprinted XCI, which happens in early embryos, and random XCI, which occurs in cells after the embryo implants.
- This review explores the mechanisms behind both types of XCI, including when silencing starts, the role of the Tsix gene in regulating random XCI, and new findings about how X chromosomes interact during this process.
Article Abstract
X chromosome inactivation (XCI) is the phenomenon through which one of the two X chromosomes in female mammals is silenced to achieve dosage compensation with males. XCI is a highly complex, tightly controlled and developmentally regulated process. The mouse undergoes two forms of XCI: imprinted, which occurs in all cells of the preimplantation embryo and in the extraembryonic lineage, and random, which occurs in somatic cells after implantation. This review presents results and hypotheses that have recently been proposed concerning important aspects of both imprinted and random XCI in mice. We focus on how imprinted XCI occurs during preimplantation development, including a brief discussion of the debate as to when silencing initiates. We also discuss regulation of random XCI, focusing on the requirement for Tsix antisense transcription through the Xist locus, on the regulation of Xist chromatin structure by Tsix and on the effect of Tsix regulatory elements on choice and counting. Finally, we review exciting new data revealing that X chromosomes co-localize during random XCI. To conclude, we highlight other aspects of X-linked gene regulation that make it a suitable model for epigenetics at work.
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| http://dx.doi.org/10.1016/j.ydbio.2006.07.011 | DOI Listing |
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