Xist Deletional Analysis Reveals an Interdependency between Xist RNA and Polycomb Complexes for Spreading along the Inactive X
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA419343 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR6312640_1.fastq.gz | Fastqsanger.gz | |||
| SRR6312640_2.fastq.gz | Fastqsanger.gz | |||
| SRR6312650_1.fastq.gz | Fastqsanger.gz | |||
| SRR6312650_2.fastq.gz | Fastqsanger.gz | |||
| SRR6312660_1.fastq.gz | Fastqsanger.gz |
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Project description:During X-inactivation, Xist RNA spreads along an entire chromosome to establish silencing. However, the mechanism and functional RNA elements involved in spreading remain undefined. By performing a comprehensive endogenous Xist deletion screen, we identify Repeat B as crucial for spreading Xist and maintaining Polycomb repressive complexes 1 and 2 (PRC1/PRC2) along the inactive X (Xi). Unexpectedly, spreading of these three factors is inextricably linked. Deleting Repeat B or its direct binding partner, HNRNPK, compromises recruitment of PRC1 and PRC2. In turn, ablating PRC1 or PRC2 impairs Xist spreading. Therefore, Xist and Polycomb complexes require each other to propagate along the Xi, suggesting a positive feedback mechanism between RNA initiator and protein effectors. Perturbing Xist/Polycomb spreading causes failure of de novo Xi silencing, with partial compensatory downregulation of the active X, and also disrupts topological Xi reconfiguration. Thus, Repeat B is a multifunctional element that integrates interdependent Xist/ Polycomb spreading, silencing, and changes in chromosome architecture.
2019-03-01 | GSE107217 | GEO
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 X-inactivation, Xist RNA spreads along an entire chromosome to establish silencing. However, the mechanism and functional RNA elements involved in spreading remain undefined. By performing a comprehensive endogenous Xist deletion screen, we identify Repeat B as crucial for spreading Xist and maintaining Polycomb repressive complexes 1 and 2 (PRC1/PRC2) along the inactive X (Xi). Unexpectedly, spreading of these three factors is inextricably linked. Deleting Repeat B or its direct binding partner, HNRNPK, compromises recruitment of PRC1 and PRC2. In turn, ablating PRC1 or PRC2 impairs Xist spreading. Therefore, Xist and Polycomb complexes require each other to propagate along the Xi, suggesting a positive feedback mechanism between RNA initiator and protein effectors. Perturbing Xist/Polycomb spreading causes failure of de novo Xi silencing, with partial compensatory downregulation of the active X, and also disrupts topological Xi reconfiguration. Thus, Repeat B is a multifunctional element that integrates interdependent Xist/Polycomb spreading, silencing, and changes in chromosome architecture.
| S-EPMC6469964 | biostudies-literature
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.
2013-11-04 | GSE48649 | GEO
Project description:3D-topology of DNA in the cell nucleus provides a level of transcription regulation beyond the sequence of the linear DNA. To study the relationship between transcriptional activity and spatial environment of a gene, we have used allele-specific 4C-technology to produce high-resolution topology maps of the active and inactive X-chromosomes in female cells. We found that loci on the active X form multiple long-range interactions, with spatial segregation of active and inactive chromatin. On the inactive X, silenced loci lack preferred interactions, suggesting a unique random organization inside the inactive territory. However, escapees, among which is Xist, are engaged in long-range contacts with each other, enabling identification of novel escapees. Deletion of Xist results in partial re-folding of the inactive X into a conformation resembling the active X, without affecting gene silencing or DNA methylation. Our data point to a role for Xist RNA in shaping the conformation of the inactive X-chromosome independently of transcription. Five or six 4C viewpoints were applied on the mouse female wild type active X-chromosome, the wild type inactive X-chromosome, the conditional Xist X-chromosome and the Xist knock out X-chromosome
2011-06-24 | E-GEOD-29509 | biostudies-arrayexpress
Project description:3D-topology of DNA in the cell nucleus provides a level of transcription regulation beyond the sequence of the linear DNA. To study the relationship between transcriptional activity and spatial environment of a gene, we have used allele-specific 4C-technology to produce high-resolution topology maps of the active and inactive X-chromosomes in female cells. We found that loci on the active X form multiple long-range interactions, with spatial segregation of active and inactive chromatin. On the inactive X, silenced loci lack preferred interactions, suggesting a unique random organization inside the inactive territory. However, escapees, among which is Xist, are engaged in long-range contacts with each other, enabling identification of novel escapees. Deletion of Xist results in partial re-folding of the inactive X into a conformation resembling the active X, without affecting gene silencing or DNA methylation. Our data point to a role for Xist RNA in shaping the conformation of the inactive X-chromosome independently of transcription.
2011-06-24 | GSE29509 | GEO
Project description:The noncoding Xist RNA recruits silencing factors to the inactive X (Xi) and facilitates re-organization of Xi structure. Here, we examine the epigenomic landscape of the Xi and assess how Xist alters chromatin accessibility. Interestingly, Xist deletion propels selective chromatin re-accessibility on the Xi, affecting various Xi regions differentially. Re-accessibility is regulated by BRG1, an ATPase subunit of SWI/SNF chromatin remodeling complex. In vitro, RNA binding inhibits the nucleosome remodeling and ATPase activities of BRG1. In vivo, Xist directly interacts with BRG1 and expels BRG1 from the Xi. Xist ablation leads to a selective return of BRG1 in cis, emanating from pre-existing BRG1 sites that are Xist-free. BRG1's return correlates with cohesin re-binding and restoration of topologically associated domains (TADs), and results in formation of de novo Xi "superloops." Thus, Xist RNA binding inhibits BRG1's nucleosome remodeling activity and results in expulsion of the SWI/SNF complex from the Xi.
2019-01-14 | GSE109395 | GEO
Project description:The long noncoding RNA, Xist, is critical for initiation and establishment of X- chromosome inactivation during embryogenesis in mammals but it is unclear whether its continued expression is required for maintaining X inactivation in vivo. By using an inactive X chromosome-linked MeCP2-GFP reporter, which allowed us to enumerate reactivation events in the mouse brain even when they occur in very few cells, we found that deletion of Xist in the brain after establishment of X chromosome inactivation leads to reactivation in 2-5% of neurons and in a smaller fraction of astrocytes. In contrast to global loss of both H3 lysine 27 tri-methylation (H3K27m3) and histone H2A lysine 119 monoubiquitylation (H2AK119ub1) we observed upon Xist deletion, alterations in CpG methylation were subtle, and this was mirrored by only minor alterations in X- chromosome-wide gene expression levels. Our results demonstrate that Xist is required for maintaining tight transcriptional repression on the inactive X-chromosome and that partial loss of X-dosage compensation in the absence of Xist in the brain is well tolerated.
2018-08-28 | GSE119066 | GEO
Project description:JARID2 ChIP-seq profile mediated by Xist was investigated using two separate approaches: In the first approach, we use the TX1072 female embryonic stem cell (ESC) line; this is a genetically polymorphic ESC line derived from a mouse with one X-chromosome (X-chr) from the Mus musculus castaneus (Cast) origin and the other of Mus musculus domesticus, C57BL/6 (BL6) strain origin, containing an inducible promoter on the BL6 Xist allele; differentiation and simultaneous induction of Xist for 4 days results in the inactivation of ONLY the BL6-derived X-chr and coating by JARID2 protein. We analysed this ESC line in the undifferentiated state, in which both X-chrs are active (and not coated by JARID2), and also after 4 days of differentiation under Xist inducible conditions, in which cells display one inactive X-chr from BL6 origin and one Xa of the Cast origin; the presence of SNPs allows for the comparison of the degree and localisation of JARID2 enrichment on the inactive X-chr versus the active X-chr; our results suggests that JARID2 is enriched on the inactive X-chr chromosome-wide and not in confined peaks as elsewhere in the genome; This pattern resembles patterns of Xist enrichment published before (Engreitz et al., 2013). In the second approach, we use a male ESC line that carries an inducible Xist transgene (TG) on chromosome 11 (chr11) (Wutz et al., 2000) in the presence (36:11 WT) or the absence of Eed (36:11 Eed-/-) Induction of Xist TG results in Xist coating and enrichment of JARID2 across the chr11, regardless of the presence of Eed when assess by IF/Xist RNA FISH experiments. We compare inducible and uninducible condition in both the 36:11 WT and Eed-/- ESCs; this way, we could assess the Xist-mediated JARID2 recruitment and the effect of the absence of Eed-/-; Our results shows that Xist induction result in a chromosome-wide enrichment of JARID2 on chr11, in a manner that resembles enrichment on the inactive X-chr; this pattern seem to be independent of EED, showing that in contrast to other regions in the genome where JARID2 occupancy is abrogated in the absence of EED, Xist-mediated JARID2 recruitment is not affected. JARID2 ChIP-seq analysis in differentiating female ESCs (TX1072) and in a male ESC harbouring a Xist transgene on chromosome 11 in WT and Eed-/- genetics settings
2014-01-23 | E-GEOD-52073 | biostudies-arrayexpress
Project description:Xist RNA antagonizes the chromatin remodeler, BRG1, from the inactive X chromosome
| PRJNA430728 | ENA