Species-specific regulation of XIST by the JPX/FTX orthologs
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE200317 | GEO | 2023/02/01
REPOSITORIES: GEO
Similar Datasets
Project description:Evolution of the mammalian sex chromosomes has resulted in a heterologous X and Y pair, where the Y chromosome has lost most of its genes. Hence, there is a need for X-linked gene dosage compensation between XY males and XX females. In placental mammals, this is achieved by random inactivation of one X chromosome (XCI) in all female somatic cells. Up-regulation of Xist transcription on the future inactive X chromosome (Xi) acts against Tsix antisense transcription, and spreading of Xist RNA in cis triggers epigenetic changes leading to XCI. Previously, we have shown that the X-encoded E3 ubiquitin ligase RNF12 is up-regulated in differentiating mouse embryonic stem cells (ESCs) and activates Xist transcription and XCI. Here, we have identified the pluripotency factor REX1 as a key target of RNF12 in the XCI mechanism. RNF12 causes ubiquitination and proteasomal degradation of REX1, and Rnf12 knockout mouse ESCs show an increased level of REX1. Using ChIP-seq, REX1 binding sites were detected in Xist and Tsix regulatory regions. Over-expression of REX1 in female ESCs was found to inhibit Xist transcription and XCI, whereas male Rex1+/- ESCs showed ectopic XCI. From this, we propose that RNF12 causes REX1 breakdown through dose-dependent catalysis, thereby representing an important pathway to initiate XCI. Rex1 and Xist are present only in placental mammals, which points to co-evolution of these two genes and XCI. 2 (one control one pulldown) samples
2012-06-12 | E-GEOD-36417 | biostudies-arrayexpress
Project description:Xist represents a paradigm for long non-coding RNA function in epigenetic regulation, although how it mediates X-chromosome inactivation (XCI) remains largely unexplained. Multiple Xist-RNA binding proteins have recently been identified, including SPEN/SHARP, whose knockdown has been associated with deficient XCI at multiple loci. Here we demonstrate that SPEN is a key orchestrator of XCI in vivo and unravel its mechanism of action. We show that SPEN is essential for initiating gene silencing on the X chromosome in preimplantation mouse embryos and embryonic stem cells. On the other hand, SPEN is dispensable for maintenance of XCI in neural progenitor cells, although it significantly dampens expression of genes that escape from XCI. During initiation of XCI, we show by live-cell imaging and CUT&RUN approaches that SPEN is immediately recruited to the X chromosome upon Xist up-regulation, where it is targeted to enhancers and promoters of actively transcribed genes. SPEN rapidly disengages from chromatin once silencing is accomplished, implying a need for active transcription to tether it to chromatin. We define SPEN’s SPOC (SPEN paralog and ortholog C-terminal) domain as a major effector of SPEN’s gene silencing function, and show that artificial tethering of SPOC to Xist RNA is sufficient to mediate X-linked gene silencing. We identify SPOC’s protein partners which include NCOR/SMRT, the m6A RNA methylation machinery, the NuRD complex, RNA polymerase II and factors involved in regulation of transcription initiation and elongation. We propose that SPEN acts as a molecular integrator for initiation of XCI, bridging Xist RNA with the transcription machinery as well as nucleosome remodelers and histone deacetylases, at active enhancers and promoters.
2021-04-19 | PXD015699 | Pride
Project description:The Xist long noncoding RNA (lncRNA) is essential for X-chromosome inactivation (XCI), the process by which mammals compensate for unequal numbers of sex chromosomes. During XCI, Xist coats the future inactive X (Xi) and recruits Polycomb Repressive Complex 2 (PRC2) to the X-inactivation center (Xic). Currently unclear is how Xist spreads silencing on a 150 Mb scale. Here we generate high-resolution maps of Xist binding across a developmental time course using CHART-seq. In female cells undergoing XCI de novo, Xist follows a two-step mechanism in which it initially targets gene-rich islands before spreading to intervening gene-poor domains. Xist is depleted from genes that escape XCI but frequently concentrates near escapee boundaries. Xist binding was linearly proportional to PRC2 density and H3 lysine 27 trimethylation (H3K27me3), suggesting co-migration of Xist and PRC2. Interestingly, when the Xi is acutely stripped of Xist in post-XCI cells, Xist recovers quickly within both gene-rich and -poor domains on a time scale of hours instead of days, suggesting a previously primed Xi chromatin state. We conclude that Xist spreading takes on distinct stage-specific forms: During initial establishment, Xist follows a two-step mechanism, but during maintenance, Xist spreads rapidly to both gene-rich and -poor regions. Capture hybridization analysis of RNA targets (CHART) and input samples of (differentiating) mouse embryonic stem (ES) cells and immortalized mouse embryonic fibroblasts (MEF) using paired-end 75 nt reads on Illumina HiSeq2500, with 2 replicates per sample (# of samples). RNA-seq of the same cell lines with 50 nt reads on Illumina HiSeq2000, with 2 replicates per sample (2 samples, 4 datasets total). CHIP-seq: Data from GSE36905 was aligned and processed as CHART-seq samples. Resulting coverage tracks (EZH2/K27me3) are linked directly to GSE48649 (bedGraphs linked below).
2013-11-04 | E-GEOD-48649 | biostudies-arrayexpress
Project description:During development, transcriptional and chromatin modification changes co-occur but the order and causality of events often remain unclear. We explore the interrelationship of these processes using the paradigm of X-chromosome inactivation (XCI). We initiate XCI in female, mouse embryonic stem cells by inducing Xist expression and monitor changes in transcription and chromatin by allele-specific TT-seq and ChIP-seq respectively. An unprecedented temporal resolution enabled identification of the earliest chromatin alterations during XCI. We demonstrate that HDAC3 interacts with both NCOR1 and NCOR2 and is pre-bound on the X chromosome where it deacetylates histones to promote efficient gene silencing. We also reveal the choreography of polycomb accumulation following Xist RNA coating, with PRC1-associated H2AK119Ub preceding PRC2-associated H3K27me3. Furthermore, polycomb-associated marks accumulate initially at large, intergenic domains and then spreads into genes but only in the context of gene silencing. Our results provide the hierarchy of chromatin events during XCI and demonstrate that some chromatin changes play key roles in mediating transcriptional silencing.
2019-01-17 | PXD011344 | Pride
Project description:Evolution of the mammalian sex chromosomes has resulted in a heterologous X and Y pair, where the Y chromosome has lost most of its genes. Hence, there is a need for X-linked gene dosage compensation between XY males and XX females. In placental mammals, this is achieved by random inactivation of one X chromosome (XCI) in all female somatic cells. Up-regulation of Xist transcription on the future inactive X chromosome (Xi) acts against Tsix antisense transcription, and spreading of Xist RNA in cis triggers epigenetic changes leading to XCI. Previously, we have shown that the X-encoded E3 ubiquitin ligase RNF12 is up-regulated in differentiating mouse embryonic stem cells (ESCs) and activates Xist transcription and XCI. Here, we have identified the pluripotency factor REX1 as a key target of RNF12 in the XCI mechanism. RNF12 causes ubiquitination and proteasomal degradation of REX1, and Rnf12 knockout mouse ESCs show an increased level of REX1. Using ChIP-seq, REX1 binding sites were detected in Xist and Tsix regulatory regions. Over-expression of REX1 in female ESCs was found to inhibit Xist transcription and XCI, whereas male Rex1+/- ESCs showed ectopic XCI. From this, we propose that RNF12 causes REX1 breakdown through dose-dependent catalysis, thereby representing an important pathway to initiate XCI. Rex1 and Xist are present only in placental mammals, which points to co-evolution of these two genes and XCI.
2012-06-12 | GSE36417 | GEO
Project description:Xist is indispensable for X chromosome inactivation (XCI) in female mammalian cells. However, how Xist RNA directs chromosome-wide transcriptional inactivation of the X chromosome is largely unknown. Here, to study chromosome inactivation by Xist, we generated a system where ectopic Xist expression can be induced from several genomic contexts in aneuploid mouse ES cells. We found that ectopic Xist expression from any location on the X chromosome faithfully recapitulated endogenous XCI, showing the potency of Xist to initiate XCI. Genes that escape XCI remain consistently transcriptionally active upon ectopic XCI, regardless of their position relative to Xist transgenes, and the enrichment of CTCF at their promoters is implicated in directing XCI escape. Xist expression from autosomes facilitates their transcriptional silencing to different degrees, and gene density in proximity of the Xist transcription locus plays a central role in determining the efficiency of gene inactivation. We also show that the enrichment of LINE elements together with a specific chromatin environment facilitates Xist-mediated silencing of both X-linked and autosomal genes. These findings provide new insights into the epigenetic mechanisms that mediate XCI and identify genomic features that promote Xist-mediated chromosome-wide gene inactivation
2017-07-04 | GSE92894 | GEO
Project description:X chromosome inactivation (XCI) triggers drastic reorganization of chromatin architecture, which in turn facilitates XCI. However, how the 3D organization is de novo established during XCI in vivo remains poorly understood. Mouse embryos present an ideal model, as they undergo imprinted XCI, X chromosome reactivation (XCR) and subsequent random XCI. Using low-input Hi-C, we revealed a unique chromatin structure of the inactive X chromosome (Xi) during both imprinted and random XCI in early mouse embryos. A bipartite structure featured by two megadomains separated by Xist (X-megadomains), emerges in extraembryonic lineages, derived extraembryonic endoderm (XEN) cells, and also transiently in embryonic lineages. X-megadomains then diminish in adult tissues, where previously reported Dxz4-delineated megadomains (D-megadomains) appear in a strain-specific manner. Mechanistically, X-megadomains coincide with developmentally controlled activities of regulatory regions near Xist (XRRs), and loss of XRR disrupts X-megadomains. CUT&RUN revealed strong enrichment of CTCF and cohesin near Xist, despite global depletion, on Xi in embryos and XEN cells. X-megadomains are also impaired when Xist is silenced, accompanied by global cohesin restoration, or when residual cohesin is degraded, suggesting that X-megadomain formation is promoted by both global cohesin depletion and local cohesin loading. Importantly, the loss of cohesin leads to ectopic activation of regulatory elements and genes near Xist. Hence, these data reveal programming of chromatin architecture during de novo establishment of mammalian XCI in vivo, and suggest that cohesin mediates self-insulation of gene activity of essential escapees amid global silencing.
2024-09-10 | GSE206010 | GEO
Project description:X chromosome inactivation (XCI) triggers drastic reorganization of chromatin architecture, which in turn facilitates XCI. However, how the 3D organization is de novo established during XCI in vivo remains poorly understood. Mouse embryos present an ideal model, as they undergo imprinted XCI, X chromosome reactivation (XCR) and subsequent random XCI. Using low-input Hi-C, we revealed a unique chromatin structure of the inactive X chromosome (Xi) during both imprinted and random XCI in early mouse embryos. A bipartite structure featured by two megadomains separated by Xist (X-megadomains), emerges in extraembryonic lineages, derived extraembryonic endoderm (XEN) cells, and also transiently in embryonic lineages. X-megadomains then diminish in adult tissues, where previously reported Dxz4-delineated megadomains (D-megadomains) appear in a strain-specific manner. Mechanistically, X-megadomains coincide with developmentally controlled activities of regulatory regions near Xist (XRRs), and loss of XRR disrupts X-megadomains. CUT&RUN revealed strong enrichment of CTCF and cohesin near Xist, despite global depletion, on Xi in embryos and XEN cells. X-megadomains are also impaired when Xist is silenced, accompanied by global cohesin restoration, or when residual cohesin is degraded, suggesting that X-megadomain formation is promoted by both global cohesin depletion and local cohesin loading. Importantly, the loss of cohesin leads to ectopic activation of regulatory elements and genes near Xist. Hence, these data reveal programming of chromatin architecture during de novo establishment of mammalian XCI in vivo, and suggest that cohesin mediates self-insulation of gene activity of essential escapees amid global silencing.
2024-09-10 | GSE206178 | GEO
Project description:RNA-seqs followed by whole and segmental deletions of XIST genes in human K562 cells. The XIST RNA is a non-coding RNA that induces X chromosome inactivation (XCI). Unlike the mouse Xist RNA, how the human XIST RNA controls XCI in female cells is less well characterized, and the XCI-involving RNA elements remain unclear. To systematically decipher the XCI-involving elements of XIST RNA, ten smaller XIST segments, including repeats A, D, and E; human-specific repeat elements; the promoter; and non-repetitive exons, as well as the entire XIST gene, were homozygously deleted using the Cas9 nuclease and paired guide RNAs at high efficiencies, followed by high-throughput RNA sequencing and fluorescence in-situ hybridization experiments on XIST RNA.
2019-01-25 | GSE65830 | GEO
Project description:Cloning mammals by somatic cell nuclear transfer (SCNT) is highly inefficient. Most SCNT-generated embryos die after implantation because of unidentified, complex epigenetic errors in the process of postimplantation embryonic development. Here, we identified the most upstream level of dysfunction leading to impaired development of clones by using RNA interference (RNAi) against Xist, a gene responsible for X chromosome inactivation (XCI). A prior injection of Xist-specific short interfering (si)RNA into reconstructed oocytes efficiently corrected the SCNT-specific aberrant Xist expression at the morula stage, but failed to do so thereafter at the blastocyst stage. However, we found that shortly after implantation this aberrant XCI status in cloned embryos had been corrected autonomously in both embryonic and extraembryonic tissues, probably through a newly established XCI control for postimplantation embryos. Embryo transfer experiments revealed that the siRNA-treated embryos showed 10 times higher survival than controls as early as embryonic day 5.5 and this high survival persisted until term, resulting in a remarkable improvement in cloning efficiency (12% vs. 1% in controls). Importantly, unlike control clones, these Xist-siRNA clones at birth showed only a limited dysregulation of their gene expression, indicating that correction of Xist expression in preimplantation embryos had a long-term effect on their postnatal normality. Thus, contrary to the general assumption, our results suggest that the fate of cloned embryos is determined almost exclusively before implantation by their XCI status. Furthermore, our strategy provides a promising breakthrough for mammalian SCNT cloning because RNAi treatment of oocytes is readily applicable to most mammal species. Gene expression were measured in mouse in vitro fertilized and somatic cell cloned embryos. Four biological replicates were performed in each group of Xist- or Control-siRNA.
2011-11-17 | E-GEOD-33208 | biostudies-arrayexpress