Heterozygous deletion of the SHOX gene enhancer in two females with clinical heterogeneity associating with skewed XCI and escaping XCI
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ABSTRACT:
PROVIDER: PRJNA576166 | ENA |
REPOSITORIES: ENA
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Project description:Skewed X-chromosome inactivation (XCI) plays an important role in the phenotypic heterogeneity of X-linked disorders. However, the role of skewed XCI in XCI–escaping gene SHOX regulation is unclear. Here, we focused on a heterozygous deletion of SHOX gene enhancer with clinical heterogeneity. Using SNP array, we detected that the female proband with Leri-Weill dyschondrosteosis (LWD) carried an 857 kb deletion on Xp22.3 (encompassing SHOX enhancer) and a 5,707 kb large-fragment deletion on Xq25q26. XCI analysis revealed that the X-chromosome with the Xq25q26 large-fragment deletion was completely inactivated, which forced the complete activation of the other X-chromosome carrying SHOX enhancer deletion. While the Xp22.3 deletion locates on the escaping XCI region, under the combined action of skewed XCI and escaping XCI, transcription of SHOX gene was mainly from the activated X-chromosome with SHOX enhancer defect, involving in the formation of LWD phenotype. Interestingly, this SHOX enhancer deletion was inherited from her healthy mother, who also demonstrated completely skewed XCI. However, the X-chromosome with SHOX enhancer deletion was inactivated, and the normal X-chromosome was activated. Combing with escaping XCI, her phenotype was almost normal. In summary, this study was a rare report of SHOX gene enhancer deletion in a family with clinical heterogeneity due to skewed inactivation of different X-chromosomes, which can help in the genetic counseling and prenatal diagnosis of disorders in females with SHOX defect.
2019-10-08 | GSE138489 | GEO
Project description: Not available
| S-EPMC6852097 | biostudies-literature
Project description:In this study, we reprogrammed fibroblasts from two azoospermic Klinefelter syndrome (KS) patients, and two healthy male and one healthy female donor with an efficient integration-free method using episomal plasmids and laminin-521 (LN521). Whole genome transcriptomics analysis showed differentially expressed genes between KS and healthy male donors with enrichment in gene ontology (GO) terms associated with fertility, cardiovascular development, ossification and brain development, for both KS hiPSCs and fibroblasts, correlating with the KS clinical phenotype. Thorough XCI analysis combining transcriptomics data, RNA FISH and H3K27me3 staining, revealed skewed XCI in one KS fibroblast line and variability in XCI state of KS hiPSCs similar to female hiPSCs, showing either XaXi or XaXe status. Furthermore, we found up-regulated X-linked genes involved in nervous system development, synaptic transmission as well as metabolic processes supporting the potential use of KS derived hiPSC as an in vitro model for KS.
2019-10-05 | E-MTAB-7340 | 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:Studies of regulation of mouse X inactivation and genes escaping XCI
| PRJNA256185 | ENA
Project description:The spatial proximity between regulatory elements and their target genes has a profound affect on gene expression. X Chromosome Inactivation (XCI) is an epigenetic process by which an entire chromosome is rendered, for the most part, transcriptionally silent. A few genes are known to escape XCI and the mechanism for this escape remains unclear. Here, using mouse trophectodermal stem cells, we address whether specific chromosomal interactions facilitate escape from XCI by bringing escape-specific regulatory elements in close proximity to gene promoters. Our results suggest a model where escape from XCI occurs within topologically associated domains. As such, escaping genes and the regulatory sequences required for their escape are likely located within close linear proximity to each other. The datasets provided include those generated from allele-specific 4C-Seq of genes escaping XCI, genes subject to XCI, and non-genic regions of the X chromosome. FASTQ files, text files containing genomic coordiantes, and BED aligmnets are provided. All sequences were mapped relative to mouse genome build mm9. Deep sequencing of circular chromosome conformation capture (4C-Seq) of genes escaping X inactivation in mouse trophoblast stem cells
2014-03-26 | E-GEOD-49111 | 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.
2010-07-20 | GSE22551 | GEO
Project description:X chromosome inactivation (XCI) is a dosage compensation phenomenon that occurs in females. Initiation of XCI depends on Xist RNA, which triggers silencing of one of the two X chromosomes, except for XCI escape genes that continue to be biallelically expressed. In the soma XCI is stably maintained with continuous Xist expression. How Xist impacts XCI maintenance remains an open question. Here we conditionally deleted Xist in hematopoietic system of mice and report differentiation and cell cycle defects in female hematopoietic stem and progenitor cells (HPSCs). By utilizing female HSPCs and mouse embryonic fibroblasts, we find that X-linked genes show variable tolerance to Xist loss. Specifically, XCI escape genes exhibit preferential transcriptional upregulation, which associates with low H3K27me3 occupancy, and high chromatin accessibility that accommodates preexisting binding of transcription factors such as Yin Yang 1 (YY1) at the basal state. We conclude that Xist is necessary for gene-specific silencing during XCI maintenance and impacts lineage-specific cell differentiation and proliferation during hematopoiesis.
2022-07-15 | GSE184772 | GEO
Project description:X chromosome inactivation (XCI) is a dosage compensation phenomenon that occurs in females. Initiation of XCI depends on Xist RNA, which triggers silencing of one of the two X chromosomes, except for XCI escape genes that continue to be biallelically expressed. In the soma XCI is stably maintained with continuous Xist expression. How Xist impacts XCI maintenance remains an open question. Here we conditionally deleted Xist in hematopoietic system of mice and report differentiation and cell cycle defects in female hematopoietic stem and progenitor cells (HPSCs). By utilizing female HSPCs and mouse embryonic fibroblasts, we find that X-linked genes show variable tolerance to Xist loss. Specifically, XCI escape genes exhibit preferential transcriptional upregulation, which associates with low H3K27me3 occupancy, and high chromatin accessibility that accommodates preexisting binding of transcription factors such as Yin Yang 1 (YY1) at the basal state. We conclude that Xist is necessary for gene-specific silencing during XCI maintenance and impacts lineage-specific cell differentiation and proliferation during hematopoiesis.
2022-07-15 | GSE184770 | GEO
Project description:Human embryonic stem cells (hESCs) exhibit a skewed X chromosome inactivation (XCI) have recently been reported. Whether there is any copy number variation (CNV), loss of heterozygousity (LOH) and single nucleotide variant (SNV) in those epigenetically distinct cells and whether these abnormalities have any correlation to skewed XCI in hESCs is currently unknown.
2014-10-01 | E-MTAB-1992 | biostudies-arrayexpress