Landscape of DNA methylation on the X chromosome reflects CpG density, functional chromatin state and X-chromosome inactivation.
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE60275 | GEO | 2014/11/29
SECONDARY ACCESSION(S): PRJNA257897
REPOSITORIES: GEO
Similar Datasets
Project description:X chromosome inactivation (XCI) silences most genes on one X chromosome in female mammals, but some genes escape XCI. To identify escape gene in vivo and to explore molecular mechanisms that regulate this process we analyzed the allele-specific expression and chromatin structure of X-linked genes in mouse tissues and cells with skewed XCI and distinguishable alleles based on single nucleotide polymorphisms. Using a new method to estimate allelic expression, we demonstrate a continuum between complete silencing and significant expression from the inactive X (Xi). Few genes (2-3%) escape XCI to a significant level and only a minority differs between mouse tissues, suggesting stringent silencing and escape controls. Allelic profiles of DNase I hypersensitivity and RNA polymerase II occupancy of genes on the Xi correlate with escape from XCI. Allelic binding profiles of the DNA binding protein CCCTC-binding factor (CTCF) in different cell types indicate that CTCF binding at the promoter correlates with escape. Importantly, CTCF binding at the boundary between escape and silenced domains may prevent the spreading of active escape chromatin into silenced domains. Examination of allelic expression in mouse hybrid tissues.
2015-02-20 | E-GEOD-59777 | biostudies-arrayexpress
Project description:X chromosome inactivation (XCI) silences most genes on one X chromosome in female mammals, but some genes escape XCI. To identify escape gene in vivo and to explore molecular mechanisms that regulate this process we analyzed the allele-specific expression and chromatin structure of X-linked genes in mouse tissues and cells with skewed XCI and distinguishable alleles based on single nucleotide polymorphisms. Using a new method to estimate allelic expression, we demonstrate a continuum between complete silencing and significant expression from the inactive X (Xi). Few genes (2-3%) escape XCI to a significant level and only a minority differs between mouse tissues, suggesting stringent silencing and escape controls. Allelic profiles of DNase I hypersensitivity and RNA polymerase II occupancy of genes on the Xi correlate with escape from XCI. Allelic binding profiles of the DNA binding protein CCCTC-binding factor (CTCF) in different cell types indicate that CTCF binding at the promoter correlates with escape. Importantly, CTCF binding at the boundary between escape and silenced domains may prevent the spreading of active escape chromatin into silenced domains. Examination of CTCF and RNA PolIIS5p occupancy in mouse hybrid cells and adult tissues.
2015-02-20 | E-GEOD-59778 | biostudies-arrayexpress
Project description:X chromosome inactivation (XCI) is a dosage compensation mechanism that silences the majority of genes on one X chromosome in each female cell. In order to characterize epigenetic changes that accompany this process, we measured DNA methylation levels in both 45,X Turner syndrome patients, who carry a single active X chromosome (Xa) and normal 46,XX females, who carry one Xa and one inactive X (Xi). Methylated DNA was immunoprecipitated and hybridized to tiling oligonucleotide arrays, generating epigenetic profiles of active and inactive X chromosomes. We observed that XCI is accompanied by changes in DNA methylation specifically at CpG islands. While the majority of CpG islands show increased methylation levels on the Xi, XCI results in reduced methylation at ~20% of CpG islands. Both intra- and inter-genic CpG islands are epigenetically modified, with the biggest increase in methylation occuring at the promoters of genes silenced by XCI. In contrast, genes escaping XCI have low levels of promoter methylation, while genes that undergo polymorphic silencing show intermediate increases in methylation proportionate to their frequency of inactivation. Thus promoter methylation and susceptibility to XCI are correlated. We observed a global correlation between CpG island methylation and the evolutionary age of different X chromosome strata, and that genes escaping XCI show increased methylation within gene bodies. We utilized our epigenetic map to predict both novel genes escaping XCI, and to identify sequence features that may contribute to the XCI process. Finally, as our study included Turner syndrome patients with single X chromosomes of both maternal and paternal origin we searched for parent-of-origin specific methylation differences, but found no evidence to support imprinting on the human X chromosome. Our study provides the first epigenetic profile of active and inactive X chromosomes, giving novel insights into the phenomenon of dosage compensation. Methylated DNA was enriched by immunoprecipitation using antibodies against 5-methylcytosine. meDIP and input DNA was labeled with cy5 and cy3 respectively and hybridized to Nimblegen arrays comprising 2.1 million 50-85mers covering human chromosomes 20, 21, 22, X and Y at a mean density of ~1 probe per 100bp. Resulting log2 fluorescence ratios correspond to methylation levels. Seven patients with Turner syndrome (45,X karyotype), and three normal females (46,XX karyotype) were analyzed. Of the Turner syndrome cases, four had a maternally-derived X, and three had a paternally-derived X chromosome.
2010-07-20 | E-GEOD-22551 | biostudies-arrayexpress
Project description:Female human ESC-lines can carry active X-chromosomes (Xa) or an XIST-RNA- coated inactive X-chromosome (Xi XIST+ ). Additionally, many ESC-lines have abnormal X-chromosome-inactivation (XCI)-states where the Xi no longer expresses XIST-RNA and has transcriptionally active regions (eroded Xi=Xe). The fate of each XCI-state upon differentiation is unclear because individual lines often contain a mixture of XCI-states. Here, we established homogeneous XiXa, XeXa, and XaXa ESC-lines. We found that these lines were unable to initiate XIST-expression and X-chromosome- wide silencing upon differentiation indicating that the ESC XCI-state is maintained in differentiated cells. Consequently, differentiated XeXa and XaXa cells displayed higher levels of X-linked gene-expression than XiXa cells. Although global transcriptional compensation between X-chromosomes and autosomes is not required for female ESC-differentiation, the degree of X-chromosome- silencing influences differentiation efficiencies. Our data suggest that the Xi XIST+ Xa state is inherent to human ESCs and that all other XCI-states, including XaXa, are abnormal and arise during ESC-derivation or maintenance.
2016-12-15 | GSE91072 | GEO
Project description:X chromosome inactivation (XCI) is a dosage compensation mechanism that silences the majority of genes on one X chromosome in each female cell. In order to characterize epigenetic changes that accompany this process, we measured DNA methylation levels in both 45,X Turner syndrome patients, who carry a single active X chromosome (Xa) and normal 46,XX females, who carry one Xa and one inactive X (Xi). Methylated DNA was immunoprecipitated and hybridized to tiling oligonucleotide arrays, generating epigenetic profiles of active and inactive X chromosomes. We observed that XCI is accompanied by changes in DNA methylation specifically at CpG islands. While the majority of CpG islands show increased methylation levels on the Xi, XCI results in reduced methylation at ~20% of CpG islands. Both intra- and inter-genic CpG islands are epigenetically modified, with the biggest increase in methylation occuring at the promoters of genes silenced by XCI. In contrast, genes escaping XCI have low levels of promoter methylation, while genes that undergo polymorphic silencing show intermediate increases in methylation proportionate to their frequency of inactivation. Thus promoter methylation and susceptibility to XCI are correlated. We observed a global correlation between CpG island methylation and the evolutionary age of different X chromosome strata, and that genes escaping XCI show increased methylation within gene bodies. We utilized our epigenetic map to predict both novel genes escaping XCI, and to identify sequence features that may contribute to the XCI process. Finally, as our study included Turner syndrome patients with single X chromosomes of both maternal and paternal origin we searched for parent-of-origin specific methylation differences, but found no evidence to support imprinting on the human X chromosome. Our study provides the first epigenetic profile of active and inactive X chromosomes, giving novel insights into the phenomenon of dosage compensation.
2010-07-20 | GSE22551 | GEO
Project description:X chromosome inactivation (XCI) silences most genes on one X chromosome in female mammals, but some genes escape XCI. To identify escape gene in vivo and to explore molecular mechanisms that regulate this process we analyzed the allele-specific expression and chromatin structure of X-linked genes in mouse tissues and cells with skewed XCI and distinguishable alleles based on single nucleotide polymorphisms. Using a new method to estimate allelic expression, we demonstrate a continuum between complete silencing and significant expression from the inactive X (Xi). Few genes (2-3%) escape XCI to a significant level and only a minority differs between mouse tissues, suggesting stringent silencing and escape controls. Allelic profiles of DNase I hypersensitivity and RNA polymerase II occupancy of genes on the Xi correlate with escape from XCI. Allelic binding profiles of the DNA binding protein CCCTC-binding factor (CTCF) in different cell types indicate that CTCF binding at the promoter correlates with escape. Importantly, CTCF binding at the boundary between escape and silenced domains may prevent the spreading of active escape chromatin into silenced domains.
2015-02-20 | GSE59778 | GEO
Project description:X chromosome inactivation (XCI) silences most genes on one X chromosome in female mammals, but some genes escape XCI. To identify escape gene in vivo and to explore molecular mechanisms that regulate this process we analyzed the allele-specific expression and chromatin structure of X-linked genes in mouse tissues and cells with skewed XCI and distinguishable alleles based on single nucleotide polymorphisms. Using a new method to estimate allelic expression, we demonstrate a continuum between complete silencing and significant expression from the inactive X (Xi). Few genes (2-3%) escape XCI to a significant level and only a minority differs between mouse tissues, suggesting stringent silencing and escape controls. Allelic profiles of DNase I hypersensitivity and RNA polymerase II occupancy of genes on the Xi correlate with escape from XCI. Allelic binding profiles of the DNA binding protein CCCTC-binding factor (CTCF) in different cell types indicate that CTCF binding at the promoter correlates with escape. Importantly, CTCF binding at the boundary between escape and silenced domains may prevent the spreading of active escape chromatin into silenced domains.
2015-02-20 | GSE59777 | GEO
Project description:Background: During early embryonic development, one of the two X chromosomes in mammalian female cells is inactivated to compensate for a potential imbalance in transcript levels with male cells containing a single X chromosome. We use mouse female Embryonic Stem Cells (ESCs) with nonrandom XCI and polymorphic X chromosomes to study the dynamics of gene silencing over the inactive X chromosome (Xi) by high-resolution allele-specific RNA-Seq. Results: Induction of XCI by differentiation of female ESCs shows that genes proximal to the X-inactivation center (XIC) are silenced earlier than distal genes, while lowly expressed genes show faster XCI dynamics than highly expressed genes. The active X chromosome shows a minor but significant increase in gene activity during differentiation, resulting in complete dosage compensation in differentiated cell types. Genes escaping XCI show little or no silencing during early propagation of XCI. Using allele-specific RNA-Seq of Neural Progenitor Cells (NPCs) generated from the female ESCs, we identify three regions distal to the XIC that stably escape XCI during differentiation of the female ESCs, as well as during propagation of the NPCs. These regions coincide with Topologically Associated Domains (TADs) as determined in the undifferentiated female ESCs. Also the previously characterized human gene clusters escaping XCI correlate with TADs. Conclusions: Together, the dynamics of gene silencing observed over the Xi during XCI provide further insight in the formation and maintenance of the repressive Xi complex. The association of regions of escape with TADs, in mouse and human, suggests a regulatory role for TADs during propagation of XCI. 19 RNA-Seq profiles of mouse ESCs, EpiSCs and NPCs, mostly from distant crosses to allow allele specific mapping. 1 HiC profile of an undifferentiated mouse female ESC line containing a Tsix mutation. Mainly focusing on X inactivation.
2015-06-15 | E-GEOD-60738 | biostudies-arrayexpress
Project description:Female human ESC-lines can carry active X-chromosomes (Xa) or an XIST-RNA-coated inactive X-chromosome (XiXIST+). Additionally, many ESC lines have abnormal X-chromosomeinactivation (XCI)-states where the Xi no longer expresses XIST-RNA and has transcriptionally active regions (eroded Xi=Xe). The fate of each XCI-state upon differentiation is unclear because individual lines often contain a mixture of XCI-states. Here, we established homogeneous XiXa, XeXa, and XaXa ESC-lines. Employing RNA-FISH, RNA-sequencing and DNA methylation analyses, we found that these lines were unable to initiate XIST-expression and X-chromosome-wide silencing upon differentiation indicating that the ESC XCI-state is maintained in differentiated cells. Consequently, differentiated XeXa and XaXa cells displayed higher levels of X-linked gene-expression than XiXa cells. Although global transcriptional compensation between X-chromosomes and autosomes is not required for female ESC-differentiation, the degree of X-chromosome-silencing influences differentiation efficiencies. Our data suggest that the XiXIST+Xa state is inherent to human ESCs and that all other XCI-states, including XaXa, are abnormal and arise during ESC-derivation or maintenance.
2017-01-26 | GSE88932 | GEO
Project description:Female human ESC-lines can carry active X-chromosomes (Xa) or an XIST-RNA-coated inactive X-chromosome (XiXIST+). Additionally, many ESC lines have abnormal X-chromosomeinactivation (XCI)-states where the Xi no longer expresses XIST-RNA and has transcriptionally active regions (eroded Xi=Xe). The fate of each XCI-state upon differentiation is unclear because individual lines often contain a mixture of XCI-states. Here, we established homogeneous XiXa, XeXa, and XaXa ESC-lines. Employing RNA-FISH, RNA-sequencing and DNA methylation analyses, we found that these lines were unable to initiate XIST-expression and X-chromosome-wide silencing upon differentiation indicating that the ESC XCI-state is maintained in differentiated cells. Consequently, differentiated XeXa and XaXa cells displayed higher levels of X-linked gene-expression than XiXa cells. Although global transcriptional compensation between X-chromosomes and autosomes is not required for female ESC-differentiation, the degree of X-chromosome-silencing influences differentiation efficiencies. Our data suggest that the XiXIST+Xa state is inherent to human ESCs and that all other XCI-states, including XaXa, are abnormal and arise during ESC-derivation or maintenance.
2017-01-26 | GSE88931 | GEO