Journal ArticleDOI
X-chromosome inactivation: counting, choice and initiation
Philip Avner,Edith Heard +1 more
TLDR
In many sexually dimorphic species, a mechanism is required to ensure equivalent levels of gene expression from the sex chromosomes, and in mammals, such dosage compensation is achieved by X-chromosome inactivation, a process that presents a unique medley of biological puzzles.Abstract:
In many sexually dimorphic species, a mechanism is required to ensure equivalent levels of gene expression from the sex chromosomes. In mammals, such dosage compensation is achieved by X-chromosome inactivation, a process that presents a unique medley of biological puzzles: how to silence one but not the other X chromosome in the same nucleus; how to count the number of X's and keep only one active; how to choose which X chromosome is inactivated; and how to establish this silent state rapidly and efficiently during early development. The key to most of these puzzles lies in a unique locus, the X-inactivation centre and a remarkable RNA — Xist — that it encodes.read more
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Journal ArticleDOI
Co-evolution of X-chromosome inactivation and imprinting in mammals
Wolf Reik,Annabelle Lewis +1 more
TL;DR: It is proposed that non-coding RNAs and histone modifications were adopted for the imprinting of growth suppressors on the X chromosome and on autosomes, and provides a unified hypothesis for the evolution of X-chromosome inactivation and imprinting.
Journal ArticleDOI
Ring1b-mediated H2A Ubiquitination Associates with Inactive X Chromosomes and Is Involved in Initiation of X Inactivation
TL;DR: Evidence is provided that supports H2A ubiquitination as a novel epigenetic marker for the inactive X chromosome (Xi) and links H2a ubiquitinations to initiation of X inactivation and the association of Ring1b and ubH2A with Xi is mitotically stable in non-differentiated TS cells.
Journal ArticleDOI
The role of histones in chromatin remodelling during mammalian spermiogenesis.
TL;DR: A new testis-specific 'histone code' can be generated combining both histone variants and histone post-translational modifications, and possible functional significance of the global chromatin alterations occurring prior to histone replacement during spermiogenesis is discussed.
Journal ArticleDOI
Comparative sequence analysis of the X-inactivation center region in mouse, human, and bovine.
Corinne Chureau,Marine Prissette,Agnès Bourdet,Valérie Barbe,Laurence Cattolico,Louis Jones,André Eggen,Philip Avner,Laurent Duret +8 more
TL;DR: The distribution of repeated elements, especially LINE repeats, in the mouse Xic region when compared to the rest of the genome does not support the hypothesis of a role for these repeat elements in the spreading of X inactivation and an asymmetric distribution of LINE elements on the two DNA strands was observed in the three species.
Journal ArticleDOI
Xite, X-inactivation intergenic transcription elements that regulate the probability of choice.
Yuya Ogawa,Jeannie T. Lee +1 more
TL;DR: It is proposed that allele-specific Xite action promotes Tsix asymmetry and generates X chromosome inequality, and Xite is a candidate for the Xce, the classical modifier of XCI ratios.
References
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Journal ArticleDOI
Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG-binding protein 2.
Ruthie E. Amir,Ignatia B. Van den Veyver,Mimi Wan,Charles Q. Tran,Uta Francke,Huda Y. Zoghbi +5 more
TL;DR: This study reports the first disease-causing mutations in RTT and points to abnormal epigenetic regulation as the mechanism underlying the pathogenesis of RTT.
Journal ArticleDOI
Demethylation of the zygotic paternal genome
TL;DR: It is shown that the paternal genome in the mouse is significantly and actively demethylated within 6–8 hours of fertilization, before the onset of DNA replication, whereas the maternal genome is dem methylated after several cleavage divisions.
Journal ArticleDOI
Requirement for Xist in X chromosome inactivation
Graeme D. Penny,Graham F. Kay,Graham F. Kay,Steven A. Sheardown,Sohaila Rastan,Sohaila Rastan,Neil Brockdorff +6 more
TL;DR: Evidence for gene targeting of Xist, the proposed candidate for the X inactivation centre, is provided, and its absolute requirement in the process of X chromosome inactivation is provided.
Journal ArticleDOI
Chromosome instability and immunodeficiency syndrome caused by mutations in a DNA methyltransferase gene.
Guoliang Xu,Timothy H. Bestor,Déborah Bourc'his,Chih-Lin Hsieh,Niels Tommerup,Merete Bugge,Maj Hultén,Xiaoyan Qu,James J. Russo,E. Viegas-Péquignot +9 more
TL;DR: It is shown that five unrelated ICF patients have mutations in both alleles of the gene that encodes DNA methyltransferase 3B (refs 5, 6), which is the only genetic disorder known to involve constitutive abnormalities of genomic methylation patterns.
Journal ArticleDOI
Tsix , a gene antisense to Xist at the X-inactivation centre
TL;DR: Tsix RNA is a 40-kb RNA originating 15 kb downstream of Xist and transcribed across the Xist locus and has features suggesting a role in regulating the early steps of X inactivation, but not the silencing step.