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Nature 438, 297-298 (17 November 2005) | doi:10.1038/438297a
Developmental biology: The X-inactivation yo-yo
Wolf Reik1 and Anne C. Ferguson-Smith2
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Abstract
In female mammals, one of two X chromosomes has to be shut down during early development. To what extent does this 'imprinted X-chromosome inactivation' involve the history of the chromosome?
In most mammals, males have the male sex-determining Y chromosome and a single X chromosome, whereas females have two X chromosomes. In females, the resulting imbalance in the 'dosage' of genes on the X chromosomes needs to be compensated so that gene expression from the X chromosome is equivalent in males and females. Mammals have evolved a unique form of dosage compensation, called X-chromosome inactivation, in which one of the two X chromosomes in female cells is silenced epigenetically1 — that is, by factors such as chemical modification of the DNA, or of the histone proteins that package DNA into chromosomes, often involving non-coding RNAs. Many aspects of mammalian X inactivation remain mysterious. But through elegant studies in the mouse, Okamoto and colleagues (page 369 of this issue)2 have unravelled some of the earliest events in the process.
============================
Nature 438, 297-298 (17 November 2005) | doi:10.1038/438297a
Developmental biology: The X-inactivation yo-yo
Wolf Reik1 and Anne C. Ferguson-Smith2
Top of page
Abstract
In female mammals, one of two X chromosomes has to be shut down during early development. To what extent does this 'imprinted X-chromosome inactivation' involve the history of the chromosome?
In most mammals, males have the male sex-determining Y chromosome and a single X chromosome, whereas females have two X chromosomes. In females, the resulting imbalance in the 'dosage' of genes on the X chromosomes needs to be compensated so that gene expression from the X chromosome is equivalent in males and females. Mammals have evolved a unique form of dosage compensation, called X-chromosome inactivation, in which one of the two X chromosomes in female cells is silenced epigenetically1 — that is, by factors such as chemical modification of the DNA, or of the histone proteins that package DNA into chromosomes, often involving non-coding RNAs. Many aspects of mammalian X inactivation remain mysterious. But through elegant studies in the mouse, Okamoto and colleagues (page 369 of this issue)2 have unravelled some of the earliest events in the process.
