X chromosome inactivation and the Xist gene.
Recent years have seen rapid progress towards understanding the molecular mechanisms involved in X chromosome inactivation (X inactivation). This progress has largely revolved around the discovery of the X inactive specific transcript (Xist) gene, which is known now to represent the master switch locus regulating X inactivation. In adult cells Xist is transcribed exclusively from the inactive X chromosome. The transcript has no apparent protein-coding potential and is retained in the nucleus in close association with the domain occupied by the inactive X chromosome. It is thus thought to represent a functional RNA molecule which acts as the primary signal responsible for the propagation of X inactivation. Developmental regulation of Xist correlates with the developmental timing of X inactivation. Recent results have demonstrated that Xist is both necessary and sufficient for X inactivation. Goals for the future are to understand the mechanism of Xist regulation which underlies the establishment of appropriate X inactivation patterns and to determine how Xist RNA participates in the process of propagating inactivation in cis.
Brockdorff
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Imperial College School of Medicine, MRC Clinical Sciences Centre, Hammersmith Hospital, London. nbrockdo@hgmp.mrc.ac.uk
Duthie
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SM
D000818:Animals; D004303:Dosage Compensation, Genetic; D007173:Imprinting, Psychological; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D014157:Transcription Factors / Q000235:genetics*; D014960:X Chromosome / Q000235:genetics*
D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D014157:Transcription Factors; C077885:XIST non-coding RNA