Spreading of X-chromosome inactivation via a hierarchy of defined Polycomb stations
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE36905 | GEO | 2012/11/01
SECONDARY ACCESSION(S): PRJNA157029
REPOSITORIES: GEO
Similar Datasets
Project description:Binding of Polycomb repressive complex 2 (PRC2) and chromatin composition of the inactive X (Xi) before, during and after X chromosome inactivation reveal that spreading is driven by a combination of Xi-specific strong and moderate Ezh2 sites. Sequence context of these sites shows a moderate enrichment of SINEs and simple repeats. The general pattern of Ezh2 and H3K27me3 distribution over the chromosome reflect a graded concentration originating from strong Ezh2 sites, around which moderate sites are clustered, suggesting a hierarchy of Ezh2 sites govern spreading. ChIP-seq of Ezh2 and H3K27me3 as well as the three active marks H3K4me3, H3K36me3 and RNA-POLII-serine5 phosphorylation (RNA-polII-S5P) in female cell lines: undifferentiated embryonic stem (ES) cells (d0), differentiating ES cells (d7) and a transformed embryonic fibroblast cell line (MEF).
2012-11-01 | E-GEOD-36905 | 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.
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: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:Understanding the targeting and spreading patterns of lncRNAs on chromatin requires a technique that can detect both high intensity binding sites and reveal genome-wide spreading patterns with high confidence. We developed an improved hybridization capture protocol to determine lncRNA localization using biotinylated LNA-containing oligonucleotides that hybridize to the target RNA and enhance capture specificity by including a protecting oligonucleotide that competitively displaces contaminating species, leading to highly specific RNA capture. This approach revealed the spreading pattern of roX2, a lncRNA involved in dosage compensation in D. melanogaster, how this pattern relates to chromatin features, and how spreading of roX2 changes upon cellular stress. Upon heat shock, roX2 displays reduced spreading on X chromosome and surprising relocalization to sites on autosomes, revealing how this improved hybridization capture approach can reveal previously uncharacterized changes in the targeting and spreading of lncRNAs on chromatin. This SuperSeries is composed of the SubSeries listed below.
2020-03-11 | GSE120220 | GEO
Project description:The inactive X chromosome (Xi) serves as a model for establishment and maintenance of repressed chromatin and the function of polycomb repressive complexes (PRC1/2). Here we show that Xi transiently relocates from the nuclear periphery towards the interior during its replication, in a process dependent on CIZ1. Compromised relocation of Xi in CIZ1-null primary mouse embryonic fibroblasts is accompanied by loss of PRC-mediated H2AK119Ub1 and H3K27me3, increased solubility of PRC2 catalytic subunit EZH2, and genome-wide deregulation of polycomb-regulated genes. Xi position in S phase is also corrupted in cells adapted to long-term culture (WT or CIZ1-null), and also accompanied by specific changes in EZH2 and its targets. The data are consistent with the idea that chromatin relocation during S phase contributes to maintenance of epigenetic landscape in primary cells, and that elevated soluble EZH2 is part of an error-prone mechanism by which modifying enzyme meets template when chromatin relocation is compromised.
2018-11-07 | GSE122235 | GEO
Project description:Heterochromatin spreading, the expansion of gene-silencing structures from DNA-encoded nucleation sites, occurs in distinct settings. Spreading re-establishes gene-poor constitutive heterochromatin every cell cycle, but also invades gene-rich euchromatin de novo to steer cell fate decisions. How chromatin context, i.e. euchromatic, heterochromatic, or different nucleator types, influences the determinants of this process remains poorly understood. Previously, we documented distinct behaviors of heterochromatin spreading in different contexts using a single-cell heterochromatin spreading sensor (Greenstein et al. 2018). In this work, building on this sensor system, we now genetically identify the factors that positively or negatively alter the propensity of a nucleation site to spread heterochromatin. We find that different chromatin contexts are dependent on unique sets of genes for the regulation of heterochromatin spreading. Further, we find that spreading in constitutive heterochromatin requires Clr6 histone deacetylase complexes containing the Fkh2 transcription factor, while the Clr3 deacetylase is globally required for silencing. Fkh2 acts by recruiting Clr6 to nucleation-distal chromatin sites. Our results segregate the pathways that control lateral heterochromatin spreading from those that instruct DNA-directed assembly in nucleation.
2021-09-24 | GSE184379 | GEO
Project description:We conducted quantitative ChIP-seq to study the impact of the CXCdel mutation and SETD2 inhibition on H3K27me3 spreading. In addition, we performed standard ChIP-seq for EZH2 in wt and CXCdel Karpas-422 and K562 cell lines.
2023-02-08 | GSE199809 | GEO
Project description:Polycomb-group proteins play critical roles in gene silencing through the deposition of histone H3 lysine 27 trimethylation (H3K27me3) and chromatin compaction. This process is essential for embryonic stem cells (ESCs) pluripotency, differentiation, and development. Polycomb repressive complex 2 (PRC2) can both read and write H3K27me3, enabling processive spread of H3K27me3 on linear genome and epigenetic memory. Long-range Polycomb-associated DNA contacts have also been described, but their regulation and role in gene silencing remains unclear. Here, we develop H3K27me3 HiChIP and apply optical reconstruction of chromatin architecture to reveal long-range Polycomb-associated DNA loops that span tens to hundreds of megabases and across multiple topological associated domains in mouse ESCs and human induced pluripotent stem cells. H3K27me3 loop anchors are enriched for Polycomb nucleation points and coincide with key developmental genes, such as Hmx1, Wnt6 and Hoxa. Genetic deletion of H3K27me3 loop anchors causes spatially proximal partner chromosomal loci to break apart, and alters H3K27me3 deposition, both locally and megabases away on the same chromosome. A selective EZH2 mutant deficient in RNA binding but intact H3K27me3 enzymatic activity leads to global alteration in H3K27me3 loops, decreased spatial proximity, and failure to spread Polycomb from PRC2 nucleation points to partner loci at developmental genes. Together, these results suggest PRC2 acts as a “genomic wormhole”, using RNA binding to enhance long range chromosome folding and H3K27me3 spreading. Developmental gene loci have novel roles in Polycomb spreading, emerging as key architectural elements of the epigenome.
2022-05-13 | GSE150906 | GEO
Project description:Polycomb-group proteins play critical roles in gene silencing through the deposition of histone H3 lysine 27 trimethylation (H3K27me3) and chromatin compaction. This process is essential for embryonic stem cells (ESCs) pluripotency, differentiation, and development. Polycomb repressive complex 2 (PRC2) can both read and write H3K27me3, enabling processive spread of H3K27me3 on linear genome and epigenetic memory. Long-range Polycomb-associated DNA contacts have also been described, but their regulation and role in gene silencing remains unclear. Here, we develop H3K27me3 HiChIP and apply optical reconstruction of chromatin architecture to reveal long-range Polycomb-associated DNA loops that span tens to hundreds of megabases and across multiple topological associated domains in mouse ESCs and human induced pluripotent stem cells. H3K27me3 loop anchors are enriched for Polycomb nucleation points and coincide with key developmental genes, such as Hmx1, Wnt6 and Hoxa. Genetic deletion of H3K27me3 loop anchors causes spatially proximal partner chromosomal loci to break apart, and alters H3K27me3 deposition, both locally and megabases away on the same chromosome. A selective EZH2 mutant deficient in RNA binding but intact H3K27me3 enzymatic activity leads to global alteration in H3K27me3 loops, decreased spatial proximity, and failure to spread Polycomb from PRC2 nucleation points to partner loci at developmental genes. Together, these results suggest PRC2 acts as a “genomic wormhole”, using RNA binding to enhance long range chromosome folding and H3K27me3 spreading. Developmental gene loci have novel roles in Polycomb spreading, emerging as key architectural elements of the epigenome.
2022-05-13 | GSE150905 | GEO