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DOI: 10.3934/genet.2015.2.110
Imprinted X chromosome inactivation: evolution of mechanisms in distantly related mammals
Abstract
In females, X chromosome inactivation (XCI) ensures transcriptional silencing of one of the two Xs (either in a random or imprinted fashion) in somatic cells. Comparing this silencing between species has offered insight into different mechanisms of X inactivation, providing clues into the evolution of this epigenetic process in mammals. Long-noncoding RNAs have emerged as a common theme in XCI of therian mammals (eutherian and marsupial). Eutherian X inactivation is regulated by the noncoding RNA product of XIST, within a cis-acting master control region called the X inactivation center (XIC). Marsupials XCI is XIST independent. Instead, XCI is controlled by the long-noncoding RNA Rsx, which appears to be a functional analog of the eutherian XIST gene, insofar that its transcript coats the inactive X and represses activity of genes in cis. In this review we discuss XCI in eutherians, and contrast imprinted X inactivation in mouse and marsupials. We provide particular focus on the evolution of genomic elements that confer the unique epigenetic features that characterize the inactive X chromosome.
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Keywords
X chromosome - XCI - imprinting - noncoding RNA - epigenetic regulation - marsupial - XIST - RSX - X inactivation center - evolutionAbbreviations
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Conflict of Interest
The authors declare no conflict of interest.
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Publication History
Received: 03 November 2014
Accepted: 01 March 2015
Article published online:
10 May 2021
© 2015. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)
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