Cell fusion-mediated pluripotent reprogramming triggers ordered changes in chromatin and gene expression across the human inactive X chromosome
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ABSTRACT:
PROVIDER: PRJNA310338 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR3137100.fastq.gz | Fastqsanger.gz | |||
| SRR3137100_1.fastq.gz | Fastqsanger.gz | |||
| SRR3137100_2.fastq.gz | Fastqsanger.gz | |||
| SRR3137101_1.fastq.gz | Fastqsanger.gz | |||
| SRR3137101_2.fastq.gz | Fastqsanger.gz |
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Project description:Erasure of epigenetic memory is required to convert somatic cells towards pluripotency. Reactivation of the inactive X chromosome (Xi) has been used to model epigenetic reprogramming in mouse, but human studies are hampered by Xi epigenetic instability and difficulties in tracking partially reprogrammed iPSCs. Here we used cell fusion to examine the earliest events in the reprogramming-induced Xi reactivation of human female fibroblasts. We show a rapid and widespread loss of Xi-associated H3K27me3 and XIST in fused cells that precedes the bi-allelic expression of selected Xi-genes by many heterokaryons (30-50%). After cell division, RNA-FISH and RNA-Seq analysis confirmed that Xi reactivation remained partial and showed that induction of human pluripotency-specific XACT transcripts occurred, but was rare (1%). These data effectively separate pre- and post-mitotic events in reprogramming-induced Xi reactivation, and suggest a hierarchy where early events such as XIST-delocalisation, are required but are insufficient to establish stable human X reactivation. We performed RNA-sequencing of human fibroblast clones derived from TERT-immortalised NHDF17914 (Lonza) before and at 5 days after fusion with mouse ESC (E14Tg2a:puroR). Two biological replicates were performed and sequenced.
2016-07-01 | E-GEOD-77443 | biostudies-arrayexpress
Project description:Erasure of epigenetic memory is required to convert somatic cells towards pluripotency. Reactivation of the inactive X chromosome (Xi) has been used to model epigenetic reprogramming in mouse, but human studies are hampered by Xi epigenetic instability and difficulties in tracking partially reprogrammed iPSCs. Here we used cell fusion to examine the earliest events in the reprogramming-induced Xi reactivation of human female fibroblasts. We show a rapid and widespread loss of Xi-associated H3K27me3 and XIST in fused cells that precedes the bi-allelic expression of selected Xi-genes by many heterokaryons (30-50%). After cell division, RNA-FISH and RNA-Seq analysis confirmed that Xi reactivation remained partial and showed that induction of human pluripotency-specific XACT transcripts occurred, but was rare (1%). These data effectively separate pre- and post-mitotic events in reprogramming-induced Xi reactivation, and suggest a hierarchy where early events such as XIST-delocalisation, are required but are insufficient to establish stable human X reactivation.
2016-07-01 | GSE77443 | GEO
Project description:Unfolding the inactive X chromosome
| PRJNA478454 | ENA
Project description:Erasure of epigenetic memory is required to convert somatic cells towards pluripotency. Reactivation of the inactive X chromosome (Xi) has been used to model epigenetic reprogramming in mouse, but human studies are hampered by Xi epigenetic instability and difficulties in tracking partially reprogrammed iPSCs. Here we use cell fusion to examine the earliest events in the reprogramming-induced Xi reactivation of human female fibroblasts. We show that a rapid and widespread loss of Xi-associated H3K27me3 and XIST occurs in fused cells and precedes the bi-allelic expression of selected Xi-genes by many heterokaryons (30-50%). After cell division, RNA-FISH and RNA-seq analyses confirm that Xi reactivation remains partial and that induction of human pluripotency-specific XACT transcripts is rare (1%). These data effectively separate pre- and post-mitotic events in reprogramming-induced Xi reactivation and reveal a complex hierarchy of epigenetic changes that are required to reactivate the genes on the human Xi chromosome.
| S-EPMC4987517 | biostudies-literature
Project description:X-chromosome inactivation (XCI) entails a massive structural reorganization of the inactive X (Xi). However the molecular architecture of the Xi is unknown. Here we show that the Xi lacks typical autosomal features such as active/inactive compartments and topologically associating domains (TADs), except around a small number of genes that escape XCI and remain expressed. Escaping genes form TADs and retain DNA accessibility at promoter-proximal and CTCF binding sites, indicating that these loci can avoid Xist-mediated erasure of chromosomal structure. We further show that genesilencing competent Xist RNA is sufficient to induce segregation of the Xi into two ‘mega-domains’ separated by a boundary that includes the DXZ4 macrosatellite. Deletion of this boundary prior to XCI results in fusion of the megadomains and altered patterns of escape that correlate with changes in TAD structure following differentiation and XCI . Our results suggest a critical role for the boundary locus and Xist RNA in shaping the structure of the Xi and modulating escape from XCI. Our findings also point to roles of transcription and CTCF binding in TAD formation in the context of facultative heterochromatin.
2016-07-18 | GSE72697 | GEO
Project description:A subset of genomic regions, including one of the female X chromosomes and all imprinted genes, are expressed exclusively from a single allele in somatic cells of mammals. To evaluate structural changes associated with allelic silencing, we used mouse F1 hybrid systems in which X inactivation is skewed and alleles can be distinguished based on single nucleotide polymorphisms to analyze chromatin contacts by a new Hi-C assay that uses DNase I for chromatin fragmentation. Both DNase Hi-C and in situ DNase Hi-C reveal a radically different conformation between the two female mouse X chromosomes. Two superdomains of frequent intrachromosomal contacts separated by a hinge region are specifically observed on the inactive X chromosome both in vivo (brain) and in vitro (Patski cells). A bipartite 3D organization of the inactive X has been also reported in human lymphoblastoid cells, suggesting that this conserved structure probably plays an important role in maintenance of gene silencing on the inactive X. Interestingly, we found that the genomic content of the superdomains differs between species, but that part of the hinge region is conserved and located near the Dxz4/DXZ4 locus that binds CTCF on the inactive X. In mouse, the hinge region also contains a minisatellite Ds-TR adjacent to a promoter with strong CTCF binding. Both Dxz4 and Ds-TR bind nucleophosmin and are enriched in nucleolus-associated chromatin, suggesting anchoring to the nucleolus. Genes that escape X inactivation do not cluster but are preferentially located near the periphery of the 3D structure. Regions enriched in CTCF or RNA polymerase are also preferentially located on the periphery of the inactive X while LINE1 elements are preferentially on the interior. Genes subject to silencing exhibit fewer detectable intrachromosomal contacts than escape genes. This transcription-coupled pattern is also evident for imprinted genes, in which more chromatin contacts are detected on the expressed allele, suggesting greater constraint on the organization of expressed genomic regions.
2015-07-16 | GSE68992 | GEO
Project description:Comparison of human iPSC lines, ESC and fibroblasts to determine their expression patterns. All early passage female lines profiled expressed XIST RNA which is an indicator of an inactive X chromosome. Genes on the X-chromosome were also analyzed for overall levels of gene expression compared to human fibroblasts.
2010-08-19 | GSE22246 | GEO
Project description:Comparison of human iPSC lines, ESC and fibroblasts to determine their expression patterns. All early passage female lines profiled expressed XIST RNA which is an indicator of an inactive X chromosome. Genes on the X-chromosome were also analyzed for overall levels of gene expression compared to human fibroblasts. hiPSC lines were generated and extracted for RNA with TriZOL and hybridization on Affymetrix arrays.
2010-08-18 | E-GEOD-22246 | biostudies-arrayexpress
Project description:Whole-chromosome methylation patterns of the mouse inactive X
| PRJEB71972 | ENA
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