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X chromosome

About: X chromosome is a research topic. Over the lifetime, 9862 publications have been published within this topic receiving 407354 citations. The topic is also known as: GO:0000805 & chrX.


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Journal Article
TL;DR: It is concluded that the locus for Duchenne muscular dystrophy is at Xp21 and, furthermore, that this site may be particularly susceptible both to chromosome breakage and exchange and to gene mutation.
Abstract: An isolated case of Duchenne muscular dystrophy in a female who has a de novo t(X;5)(p21;q35) translocation is described. The similarities between this patient and four previously reported females with Duchenne muscular dystrophy are discussed. It is concluded that the locus for Duchenne muscular dystrophy is at Xp21 and, furthermore, that this site may be particularly susceptible both to chromosome breakage and exchange and to gene mutation.

143 citations

Journal ArticleDOI
TL;DR: Genome-wide ChIP-seq analyses show a female-specific quantitative increase of H3K27me3 across the X chromosome as XCI proceeds in differentiating female ES cells, and it is demonstrated that this increase is specific to the Xi by allele-specific SNP mapping of the Chip-seq tags.
Abstract: Differentiation of female murine ES cells triggers silencing of one X chromosome through X-chromosome inactivation (XCI). Immunofluorescence studies showed that soon after Xist RNA coating the inactive X (Xi) undergoes many heterochromatic changes, including the acquisition of H3K27me3. However, the mechanisms that lead to the establishment of heterochromatin remain unclear. We first analyze chromatin changes by ChIP-chip, as well as RNA expression, around the X-inactivation center (Xic) in female and male ES cells, and their day 4 and 10 differentiated derivatives. A dynamic epigenetic landscape is observed within the Xic locus. Tsix repression is accompanied by deposition of H3K27me3 at its promoter during differentiation of both female and male cells. However, only in female cells does an active epigenetic landscape emerge at the Xist locus, concomitant with high Xist expression. Several regions within and around the Xic show unsuspected chromatin changes, and we define a series of unusual loci containing highly enriched H3K27me3. Genome-wide ChIP-seq analyses show a female-specific quantitative increase of H3K27me3 across the X chromosome as XCI proceeds in differentiating female ES cells. Using female ES cells with nonrandom XCI and polymorphic X chromosomes, we demonstrate that this increase is specific to the Xi by allele-specific SNP mapping of the ChIP-seq tags. H3K27me3 becomes evenly associated with the Xi in a chromosome-wide fashion. A selective and robust increase of H3K27me3 and concomitant decrease in H3K4me3 is observed over active genes. This indicates that deposition of H3K27me3 during XCI is tightly associated with the act of silencing of individual genes across the Xi.

143 citations

Journal ArticleDOI
TL;DR: Investigation of four adult male HT-1080 fibrosarcoma cell lines expressing ectopic human XIST demonstrates that these postdifferentiation cells can undergo chromosomal inactivation outside of any normal developmental context, and suggests that autosomal in activation may confer a selective disadvantage.
Abstract: It has been believed that XIST RNA requires a discrete window in early development to initiate the series of chromatin-remodeling events that form the heterochromatic inactive X chromosome. Here we investigate four adult male HT-1080 fibrosarcoma cell lines expressing ectopic human XIST and demonstrate that these postdifferentiation cells can undergo chromosomal inactivation outside of any normal developmental context. All four clonal lines inactivated the transgene-containing autosome to varying degrees and with variable stability. One clone in particular consistently localized the ectopic XIST RNA to a discrete chromosome territory that exhibited striking hallmarks of inactivation, including long-range transcriptional inactivation. Results suggest that some postdifferentiation cell lines are capable of de novo chromosomal inactivation; however, long-term retention of autosomal inactivation was less common, which suggests that autosomal inactivation may confer a selective disadvantage. These results have fundamental significance for understanding genomic programming in early development.

143 citations

Journal ArticleDOI
29 Apr 2011-Cell
TL;DR: The findings reveal the spatiotemporal choreography of the X chromosomes during early differentiation and indicate a direct role for pairing in facilitating symmetry-breaking and monoallelic regulation of Xist during random X inactivation.

143 citations

Journal ArticleDOI
TL;DR: Although much is known about the biochemical function of MeCP2, the phenotype of Rett syndrome suggests that it plays an unexplored but critical role in development and maintenance of the nervous system.
Abstract: The identification of mutations in the gene encoding methyl CpG binding protein 2 (MeCP2) in Rett syndrome represents a major advance in the field. The current model predicts that MeCP2 represses transcription by binding methylated CpG residues and mediating chromatin remodeling. A physical interaction between MeCP2, histone deacetylases and the transcriptional co-repressor Sin3A has been demonstrated, as well as an association of MeCP2 with the basal transcription apparatus. It is unclear, however, whether MeCP2-mediated chromatin remodeling is necessary for transcriptional repression in vivo. Eight recurrent missense and nonsense mutations account for >65% of the mutations identified in Rett syndrome probands, and as predicted from the sporadic nature of the disorder, most mutations are de novo. The severity of the phenotype is likely to reflect the pattern of X chromosome inactivation in relevant tissues, although the type and position of the mutation may also play a role. Although much is known about the biochemical function of MeCP2, the phenotype of Rett syndrome suggests that it plays an unexplored but critical role in development and maintenance of the nervous system.

143 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202372
2022124
2021192
2020179
2019190
2018186