X‐chromosome Inactivation

Timothy A Hore, Australian National University, Canberra, Australia
Matthew J Wakefield, Walter and Eliza Hall Institute, Melbourne, Australia
Jennifer AM Graves, Australian National University, Canberra, Australia

Published online: May 2008

DOI: 10.1002/9780470015902.a0005795.pub2

X-chromosome inactivation is an epigenetic process that silences the majority of genes on one of the two X-chromosomes in female mammals. This silencing effectively equalizes dosage of X-linked genes in females with that of males, who only possess one X-chromosome and a sex-determining Y-chromosome.

Keywords: dosage compensation; epigenetics; chromatin modification; deoxyribonucleic acid methylation; sex chromosomes; transcriptional regulation

Figure 1. In female cells one X-chromosome is inherited from each parent. Random inactivation means that in some cells the paternally inherited X-chromosome is inactivated, while in other cells the maternal X is inactivated. Cell proliferation and migration continue after inactivation and results in clumps of cells with either the paternal or maternal X inactivated. When the X-chromosomes have different alleles this is apparent as clumps of cells with a different phenotype, such as the coat pattern in tortoiseshell cats.
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    Avner P and Heard E (2001) X-chromosome inactivation: counting, choice and initiation. Nature Reviews Genetics 2: 59–67.
    Heard E, Clerc P and Avner P (1997) X-chromosome inactivation in mammals. Annual Review of Genetics 31: 571–610.
    Ng K, Pullirsch D, Leeb M and Wutz A (2007) Xist and the order of silencing. EMBO Reports 8: 34–39.
 Web Links
    ePath X(inactive)-specific transcript, antisense (TSIX); MIM number: 300181. OMIM: http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=300181
    ePath X(inactive)-specific transcript (XIST); MIM number: 314670. OMIM: http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=314670

Related Sub-Topics:

Developmental Concepts | Molecular Genetics of Common and Complex Disease | Gene and Genome Structure and Organisation | Epigenetics and Disease | Transcriptional Regulation | Chromosomes and Chromatin Modifications | DNA Structure and Function
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Article Title: X‐chromosome Inactivation
 
How to Cite close
Hore, Timothy A, Wakefield, Matthew J, and Graves, Jennifer AM(May 2008) X‐chromosome Inactivation. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0005795.pub2]