Impact of flanking chromosomal sequences on localization and silencing by the ncRNA XIST
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE68109 | GEO | 2015/09/02
SECONDARY ACCESSION(S): PRJNA281759
REPOSITORIES: GEO
Similar Datasets
Project description:We performed RNA-seq and ChIP-seq on clones of human cell lines carrying an inducible XIST transgene on 1p, 8p, or 12q to study the effects of allelic silencing in cis Total gene expression and allelic changes were examined in HT1080 clones carrying an inducible XIST transgene on 1p, 8p, or 12q after induction by doxycycline. A replicate was done for the 8p clone treated with DOX. An additional 1p clone integrated with an empty vector, and an 1p, 8p, and 12q clone without induction were included as controls. ChIP was performed on the 8p clone to investigate the changes in H3K27 acetylation and trimethylation.
2015-09-02 | E-GEOD-68109 | biostudies-arrayexpress
Project description:X-chromosome inactivation is a striking example of epigenetic silencing in which expression of the long non-coding RNA XIST initiates the heterochromatinization and silencing of one of the pair of X chromosomes in mammalian females. To understand how the RNA can establish silencing across millions of basepairs of DNA we have modelled the process by inducing expression of XIST from nine different locations in human HT1080 cells.Localization of XIST, depletion of Cot-1 RNA, perinuclear localization, and ubiquitination of H2A occurs at all sites examined, while recruitment of H3K9me3 was not observed. Recruitment of the heterochromatic features SMCHD1, macroH2A, H3K27me3, and H4K20me1 occurs independently of each other in an integration site-dependent manner. Silencing of flanking reporter genes occurs at all sites, but the spread of silencing to flanking endogenous human genes is variable in extent of silencing as well as extent of spread, with silencing able to skip regions. The spread of H3K27me3 and loss of H3K27ac correlates with the pre-existing levels of the modifications, and overall the extent of silencing correlates with the ability to recruit additional heterochromatic features.The non-coding RNA XIST functions as a cis-acting silencer when expressed from nine different locations throughout the genome. A hierarchy among the features of heterochromatin reveals the importance of interaction with the local chromatin neighborhood for optimal spread of silencing, as well as the independent yet cooperative nature of the establishment of heterochromatin by the non-coding XIST RNA.
| S-EPMC4591629 | biostudies-literature
Project description:Nuclear compartments play diverse roles in regulating gene expression, yet the molecular forces and components driving compartment formation are not well understood. Studying how the lncRNA Xist establishes the inactive-X-chromosome (Xi)-compartment, we found that the Xist RNA-binding-proteins PTBP1, MATR3, TDP43, and CELF1 form a condensate to create an Xi-domain that can be sustained in the absence of Xist. The E-repeat-sequence of Xist serves a multivalent binding-platform for these proteins. Without the E-repeat, Xist initially coats the X-chromosome during XCI onset but subsequently disperses across the nucleus with loss of gene silencing. Recruitment of PTBP1, MATR3, TDP-43 or CELF1 to E-Xist rescues these phenotypes, and requires both self-association of MATR3 and TDP-43 and a heterotypic PTBP1-MATR3-interaction. Together, our data reveal that Xist sequesters itself within the Xi-territory and perpetuates gene silencing by seeding a protein-condensate. Our findings uncover an unanticipated mechanism for epigenetic memory and elucidate the interplay between RNA and RNA-binding-proteins in creating compartments for gene regulation.
2020-09-03 | GSE137305 | GEO
Project description:The Polycomb repressive complexes PRC1 and PRC2 play a key role in chromosome silencing by Xist RNA. Previously we have shown that initation of Polycomb recruitment is mediated by the PCGF3/5-PRC1 complex, which catalyses chromosome-wide H2A ubiquitylation (H2AK119u1), signalling recruitment of other PRC1 complexes, and PRC2. However, the molecular basis for PCGF3/5-PRC1 recruitment by Xist RNA remains unknown. Here we define the Xist RNA Polycomb Interaction Domain (XR-PID), a 600 nt element encompassing the Xist B-repeat element. XR-PID is required for Polycomb recruitment by Xist RNA, Xist-mediated chromosome silencing. We identify the RNA-binding protein hnRNPK as the principal XR-PID binding factor required to recruit PCGF3/5-PRC1. Accordingly, synthetically tethering hnRNPK to Xist RNA lacking the B-repeat is sufficient for Xist-dependent Polycomb recruitment. Our findings resolve the molecular mechanism for Polycomb recruitment by Xist RNA, providing key insights into chromatin modification by non-coding RNA.
2017-12-08 | GSE99924 | GEO
Project description:Xist transgenes (Tg) integrated into an autosome can induce transcriptional silencing of flanking genes. We investigate an autosomal integration of Xist Tg that is compatible with mouse viability but causes male sterility in homozygous transgenic mice. We show ectopic Xist expression in the transgenic male cells along with a transcriptional reduction of genes clustered in two regions of Chromosome 1. RNA-seq and DNA Fluorescent in situ Hybridization (FISH) confirms that Xist Tg is associated with Chromosome 1.
2021-04-01 | GSE156393 | GEO
Project description:Purpose: Compare the transcriptome of homogeneous XIST+ and XIST- hES cell populations. Methods: We isolated homogeneous XIST+ and XIST- cell populations. The XIST+ cells correspond to cells with a XIST cloud and one ATRX pinpoint. The XIST- cells correspond to cells with no XIST cloud and one ATRX pinpoint. Results: We took advantage of the clonal pattern of X-chromosome inactivation in H9 cells and analyzed the data in an allelic manner. By comparing the RNA-Seq data with known H9 SNPs, we identified genomic positions which were relaxed from XCI in XIST- cells compared to XIST+ cells. Conclusions: Genic as well as unannotated transcripts are massively relaxed from XCI in H9 cells when XIST expression is lost, however, this reactivation is only partial and a large region around the centromere is protected from relaxation of silencing. Total RNA (rRNA depleted) profiles of XIST+ and XIST- human embryonic stem cells
2012-12-21 | E-GEOD-39757 | 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. 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:An Xist-dependent protein assembly mediates Xist localization and gene silencing
| PRJNA565139 | ENA
Project description:Xist RNA, which directs the process of X chromosome inactivation in mammals, localizes in cis over the chromosome from which it is transcribed, recruiting chromatin modifiers to silence underlying genes. To analyze cis-limited Xist RNA localization we have developed time-resolved super-resolution imaging of individual Xist RNA molecules in single cells. Using this approach, we quantify fundamental parameters underpinning Xist RNA dynamics, demonstrating a feedback mechanism linking Xist RNA synthesis and degradation, and an unusual coupling behavior that physically links temporally separated Xist RNA molecules. Additionally, we show that the protein SPEN, a key factor for Xist-mediated gene-silencing, has a separable function in Xist RNA localization, stability and in coupling behavior. Our results provide important insights towards understanding the unique and unusual behavior of Xist RNA.
2021-06-12 | GSE154656 | GEO
Project description:As the master regulator of X-chromosome inactivation (XCI), the Xist RNA is expressed nearly ubiquitously in female mice. Xist is only absent in the germ line and at the pluripotent state. Xist is generally assumed to be expressed “by default” in females, while being actively repressed in the few tissues where it is silent. Whether activating mechanisms also contribute remained largely unknown. Through a pooled CRISPR screen we identify the GATA family of transcription factors as potent direct activators of Xist. We describe a GATA-responsive regulatory element (RE79), located ~100 kb upstream of the Xist promoter. In cell lines derived from the two extraembryonic lineages, XEN and TS cells, where imprinted Xist expression is maintained, RE79 is bound by different sets of GATA factors expressed in those tissues. Here we use a CRISPR activation screen targeting X-chromosomal genes on differentiating XO mouse embryonic stem cells to identify putative Xist activators.
2022-01-26 | GSE194013 | GEO