The role of XIST in X-inactivation maintenance in B cells (CRISPRi screen)
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE164593 | GEO | 2021/01/12
REPOSITORIES: GEO
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Project description:The long noncoding RNA (lncRNA) XIST establishes X chromosome inactivation (XCI) in female cells in early development and thereafter is thought to be largely dispensable. Here we show XIST is continually required in adult human B cells to silence a subset of X-linked immune genes such as TLR7. XIST-dependent genes lack promoter DNA methylation and require continual XIST-dependent histone deacetylation. XIST RNA-directed proteomics and CRISPRi screen reveal distinctive somatic cell-specific XIST complexes, and identify TRIM28 that mediates Pol II pausing at promoters of X-linked genes in B cells. XIST dysregylation, reflected by escape of XIST-dependent genes, occurs in CD11c+ atypical memory B cells across single-cell transcriptome data in patients with female-biased autoimmunity and COVID-19 infection. XIST inactivation with TLR7 agonism suffices to promote isotype-switched atypical B cells. These results suggest cell-type-specific diversification of lncRNA-protein complexes increase lncRNA functionalities, and expand roles for XIST in sex-differences in biology and medicine.
2021-01-12 | GSE164595 | GEO
Project description:The long noncoding RNA (lncRNA) XIST establishes X chromosome inactivation (XCI) in female cells in early development and thereafter is thought to be largely dispensable. Here we show XIST is continually required in adult human B cells to silence a subset of X-linked immune genes such as TLR7. XIST-dependent genes lack promoter DNA methylation and require continual XIST-dependent histone deacetylation. XIST RNA-directed proteomics and CRISPRi screen reveal distinctive somatic cell-specific XIST complexes, and identify TRIM28 that mediates Pol II pausing at promoters of X-linked genes in B cells. XIST dysregylation, reflected by escape of XIST-dependent genes, occurs in CD11c+ atypical memory B cells across single-cell transcriptome data in patients with female-biased autoimmunity and COVID-19 infection. XIST inactivation with TLR7 agonism suffices to promote isotype-switched atypical B cells. These results suggest cell-type-specific diversification of lncRNA-protein complexes increase lncRNA functionalities, and expand roles for XIST in sex-differences in biology and medicine.
2021-01-12 | GSE164594 | GEO
Project description:In mammals, genes located on the X chromosome are present in one copy in XY males and two in XX females. To balance the dosage of X-linked gene expression between the sexes one of the two X chromosomes in females is silenced by X inactivation initiated by up-regulation of the lncRNA (long non-coding RNA) Xist and recruitment of specific chromatin modifiers for silencing. The inactivated X chromosome becomes heterochromatic and visits a specific nuclear compartment adjacent to the nucleolus. We report a novel role for the X-linked lncRNA Firre in anchoring the inactive mouse X chromosome and preserving one of its main epigenetic features, trimethylation of histone H3 at lysine 27 (H3K27me3). Similar to Dxz4, Firre is expressed from a macrosatellite repeat locus associated with a cluster of CTCF and cohesin binding specifically on the inactive X. CTCF binding initially present in both male and female mouse embryonic stem cells was found to be lost from the active X during development. The Firre and Dxz4 loci on the inactive X were preferentially located adjacent to the nucleolus. Knockdown of Firre RNA disrupted perinucleolar targeting and H3K27me3 levels in mouse fibroblasts, demonstrating an important role for this lncRNA in maintenance of one of the main epigenetic features of the X chromosome. There was no X-linked gene reactivation after Firre knockdown; however, a compensatory increase in the expression of chromatin modifier genes implicated in X silencing was observed. In female ES cells Firre RNA knockdown did not disrupt Xist expression/coating nor silencing of G6pdx during differentiation, suggesting that Firre does not play a role in the onset of X inactivation. We conclude that the X-linked lncRNA Firre helps position the inactive X chromosome near the nucleolus and preserve one of its main epigenetic features. Examination of allelic expression in Patski cells upon Firre knockdown.
2015-03-05 | E-GEOD-66172 | biostudies-arrayexpress
Project description:In mammals, genes located on the X chromosome are present in one copy in XY males and two in XX females. To balance the dosage of X-linked gene expression between the sexes one of the two X chromosomes in females is silenced by X inactivation initiated by up-regulation of the lncRNA (long non-coding RNA) Xist and recruitment of specific chromatin modifiers for silencing. The inactivated X chromosome becomes heterochromatic and visits a specific nuclear compartment adjacent to the nucleolus. We report a novel role for the X-linked lncRNA Firre in anchoring the inactive mouse X chromosome and preserving one of its main epigenetic features, trimethylation of histone H3 at lysine 27 (H3K27me3). Similar to Dxz4, Firre is expressed from a macrosatellite repeat locus associated with a cluster of CTCF and cohesin binding specifically on the inactive X. CTCF binding initially present in both male and female mouse embryonic stem cells was found to be lost from the active X during development. The Firre and Dxz4 loci on the inactive X were preferentially located adjacent to the nucleolus. Knockdown of Firre RNA disrupted perinucleolar targeting and H3K27me3 levels in mouse fibroblasts, demonstrating an important role for this lncRNA in maintenance of one of the main epigenetic features of the X chromosome. There was no X-linked gene reactivation after Firre knockdown; however, a compensatory increase in the expression of chromatin modifier genes implicated in X silencing was observed. In female ES cells Firre RNA knockdown did not disrupt Xist expression/coating nor silencing of G6pdx during differentiation, suggesting that Firre does not play a role in the onset of X inactivation. We conclude that the X-linked lncRNA Firre helps position the inactive X chromosome near the nucleolus and preserve one of its main epigenetic features. Examination of allelic protein-binding or histone modification profiles in Patski cells.
2015-02-26 | E-GEOD-66262 | 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:Many large noncoding RNAs (lncRNAs) regulate chromatin, but the mechanisms by which they localize to genomic targets remain unexplored. Here we investigate the localization mechanisms of Xist during X-chromosome inactivation (XCI), a paradigm of lncRNA-mediated chromatin regulation. During the maintenance of XCI, Xist binds broadly across the X-chromosome. During initiation of XCI, Xist initially transfers to distal regions across the X-chromosome that are not defined by specific sequences. Instead, Xist identifies these regions by exploiting the three-dimensional conformation of the X-chromosome. Xist initially accumulates on the periphery of actively transcribed regions and requires its silencing domain to spread across active regions. This suggests a model where Xist coats the entire X-chromosome by searching in three dimensions, modifying chromosome structure, and spreading to newly accessible locations. We examined the genomic localization of the Xist lncRNA using RNA Antisense Purification (RAP) in multiple cell contexts: 1) differentiated female cells (MLFs); 2) a time-course of Xist localization in male embryonic stem (ES) cells where the endogenous Xist promoter is replaced by a tet-inducible one (pSM33); 3) a time-course of Xist localization in differentiating female ES cells (F1 2-1); and 4) wild-type (delXF6) and A-repeat deletion (delSXC9) Xist transgenes incorporated into the Hprt locus under the control of a tet-inducible promoter.
2013-05-30 | E-GEOD-46918 | biostudies-arrayexpress
Project description:Imprinted X-inactivation is a paradigm of transgenerational epigenetic inheritance in mammals and silences genes exclusively on the paternally-inherited X-chromosome. Here, we test the hypothesis that oocyte-derived maternal Polycomb repressive complex 2 (PRC2) protein EED orchestrates the selective inactivation of the paternal-X in mouse embryos. In maternal Eed null (Eedm-/-) but not zygotic Eed null female and male embryos, the maternal X-chromosome ectopically induced Xist lncRNA, which silences X-linked genes. Subsequently, Xist was silenced from one of the two X-chromosomes in females and from the sole maternal-X in males. As a result, later-stage female Eedm-/- embryos displayed random X-inactivation. The kinetics of Xist RNA induction in Eedm-/- embryos resemble that of early human embryos, which lack oocyte-derived PRC2 and only undergo random X-inactivation. Thus, expression of PRC2 genes in the oocyte and transmission of the gene products to the embryo may dictate the occurrence of imprinted X-inactivation in mammals.
2019-05-02 | GSE123173 | GEO
Project description:X chromosome inactivation (XCI) is a dosage compensation mechanism in female cells to regulate X-linked gene expression. We report here that subcultures from established lines of female hESCs displayed variations (0-100%) in the expression of XCI markers such as XIST RNA coating and enrichment of histone H3 lysine 27 trimethylation (H3K27me3) on inactive X chromosome. Surprisingly, regardless of the presence or absence of XCI markers in different cultures, all female hESCs we examined (H7, H9, and HSF6 cells) exhibit a mono-allelic expression pattern for a majority of X-linked genes. Our results suggest that these established female hESCs have completed XCI during the process of derivation and/or propagation, and the XCI pattern of lines we investigated is already non-random. However, XIST gene expression in subsets of female hESCs is unstable and subject to epigenetic silencing through DNA methylation. Concomitant with the loss of XCI markers including XIST expression and H3K27me3, approximately 12% of X-linked CpG islands become hypomethylated and a subset of previously silenced X-linked alleles are reactivated, resulting a significant elevation of gene expression dosage. Because changes in dosage compensation of X-linked genes could impair somatic cell function, we propose that XCI status should be routinely checked in subcultures of female hESCs, with cultures displaying XCI markers better suited for use in regenerative medicine. Keywords: Genotyping, gene expression and DNA methylation We used Affymetrix Genotyping array for looking for X-linked SNPs with HSF6, H7 and H9 genomic DNA, Agilent Gene expression array for comparing gene expression patten changes between HSF6 hESCs with X-inactiation and HSF6 hESCs without X-inactivation (3 repeats). Finally, mDIP-Chip method was used to detect X-linked CpG island methylation changes differences between hESCs with X-inactivation and hESCs without X-inactivation using Agilent CpG island array (3 repeats, and one of them has dye swap)
2010-05-26 | E-GEOD-9637 | biostudies-arrayexpress
Project description:XIST long non-coding RNA is responsible for X chromosome inactivation (XCI) in placental mammals, yet it accumulates on both X chromosomes in human female pre-implantation embryos without triggering X chromosome silencing. The long non-coding RNA XACT co-accumulates with XIST on active Xs and may antagonize XIST function. Here we used human ES cells in a naïve state of pluripotency to assess the function of XIST and XACT in shaping the X chromosome chromatin and transcriptional landscapes during pre-implantation development. We show that XIST triggers the deposition of polycomb-mediated repressive histone modifications and attenuates transcription of most X-linked genes in a SPEN-dependent manner, while XACT deficiency does not significantly affect XIST activity or X-linked gene expression. Our study demonstrates that XIST is functional prior to XCI, confirms the existence of a transient process of X chromosome dosage compensation, and reveals that X chromosome inactivation and dampening rely on the same set of factors.
2024-04-24 | GSE246641 | GEO
Project description:XIST long non-coding RNA is responsible for X chromosome inactivation (XCI) in placental mammals, yet it accumulates on both X chromosomes in human female pre-implantation embryos without triggering X chromosome silencing. The long non-coding RNA XACT co-accumulates with XIST on active Xs and may antagonize XIST function. Here we used human ES cells in a naïve state of pluripotency to assess the function of XIST and XACT in shaping the X chromosome chromatin and transcriptional landscapes during pre-implantation development. We show that XIST triggers the deposition of polycomb-mediated repressive histone modifications and attenuates transcription of most X-linked genes in a SPEN-dependent manner, while XACT deficiency does not significantly affect XIST activity or X-linked gene expression. Our study demonstrates that XIST is functional prior to XCI, confirms the existence of a transient process of X chromosome dosage compensation, and reveals that X chromosome inactivation and dampening rely on the same set of factors.
2024-04-24 | GSE246640 | GEO