The distribution of genomic variations in human iPSCs is related to replication timing reorganization during reprogramming
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Hu Li
PROVIDER: E-GEOD-46848 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:Cell fate change involves significant genome reorganization, including change in replication timing, but how these changes are related to genetic variation has not been examined. To study how change in replication timing that occurs during reprogramming impacts the copy number variation (CNV) landscape, we generated genome-wide replication timing profiles of induced pluripotent stem cells (iPSCs) and their parental fibroblasts. A significant portion of the genome changes replication timing as a result of reprogramming, indicative of overall genome reorganization. We found that early and late replicating domains in iPSCs are differentially affected by copy number gains and losses, and that in particular CNV gains accumulate in regions of the genome that change to earlier replication during the reprogramming process. This differential relationship was present irrespective of reprogramming method. Overall, our findings reveal a functional association between reorganization of replication timing and the CNV landscape that emerges during reprogramming. 3 cell lines, all in duplicates
2014-03-28 | E-GEOD-55397 | biostudies-arrayexpress
Project description:The replication timing program, or the order in which DNA is duplicated during S-phase, is associated with various features of chromosome structure and function, including gene expression, histone modifications, and 3-D compartmentalization of chromatin. 3 cell types, with a total of 6 individual replicates
2013-04-16 | E-GEOD-45716 | biostudies-arrayexpress
Project description:Differentiation of mouse embryonic stem cells (mESCs) is accompanied by global changes in replication timing. To elucidate this reorganization process and explore its potential impact on mouse development, we constructed genome-wide replication-timing profiles of 15 independent mouse cell types representing nine different stages of early mouse development, including all three germ layers. Overall, 45% of the genome exhibits significant changes in replication timing between cell types, indicating that replication-timing regulation is more extensive than previously estimated from neural differentiation. Intriguingly, analysis of early and late epiblast cell culture models suggest that the earliest changes in development include extensive lineage-independent early-to-late replication switches that are completed at a stage equivalent to the post-implantation epiblast, prior to germ layer specification and down-regulation of key pluripotency transcription factors (Oct4/Nanog/Sox2). These changes were stable in all subsequent lineages and involved a class of irreversibly silenced genes that were re-positioned closer to the nuclear periphery. Lineage-specific, late-to-early and early-to-late replication switches followed, which created cell-type specific replication profiles. Importantly, partially reprogrammed induced pluripotent stem cells (piPSCs) failed to restore ESC-specific replication timing and transcription programs particularly within regions of lineage-independent early-to-late replication changes, as well as the inactive X-chromosome. We conclude that lineage-independent, early-to-late replication-timing switches that occur in the post-implantation epiblast embody an epigenetic commitment to differentiation prior to germ layer specification. 22 cell lines, with a total of 36 individual replicates (i.e. 14 in duplicates, 8 in single replicates)
2010-05-19 | E-GEOD-17983 | biostudies-arrayexpress
Project description:We have investigated the role of the histone methyltransferase G9a in the establishment of silent nuclear compartments. Following conditional knockout of the G9a methyltransferase in mouse ESCs, 167 genes were significantly up-regulated, and no genes were strongly down-regulated. A partially overlapping set of 119 genes were up-regulated after differentiation of G9a-depleted cells to neural precursors. Promoters of these G9a-repressed genes were AT rich and H3K9me2 enriched but H3K4me3 depleted and were not highly DNA methylated. Representative genes were found to be close to the nuclear periphery, which was significantly enriched for G9a-dependent H3K9me2. Strikingly, although 73% of total genes were early replicating, more than 71% of G9a-repressed genes were late replicating, and a strong correlation was found between H3K9me2 and late replication. However, G9a loss did not significantly affect subnuclear position or replication timing of any non-pericentric regions of the genome, nor did it affect programmed changes in replication timing that accompany differentiation. We conclude that G9a is a gatekeeper for a specific set of genes localized within the late replicating nuclear periphery. 4 cell states each in duplicate (i.e. a total of 8 individual replicates)
2009-11-02 | E-GEOD-18079 | biostudies-arrayexpress
Project description:Extensive changes in replication timing occur during early mouse development, but their biological significance remains uncertain. To identify evolutionarily conserved features of replication timing and their relationships to epigenetic properties in humans, we profiled replication timing genome-wide in four human embryonic stem cell (hESC) lines, hESC-derived neural precursor cells (NPCs), lymphoblastoid cells, and two independently derived human induced pluripotent stem cell lines (hiPSCs). Results confirm the conservation of coordinately replicated megabase-sized units of chromosomes (replication domains) with stable cell type specific molecular boundaries that consolidate into larger replication domains during differentiation. Replication timing changes encompassed units of 400-800 kb and were coordinated with changes in transcription similar to mouse. Moreover, significant cell-type specific conservation of replication timing profiles was observed across regions of conserved synteny, despite significant species variation in the alignment of replication timing to isochore GC/LINE-1 content. Replication profiling also revealed a closer genome-wide epigenetic alignment of hESCs to mouse epiblast-derived stem cells (mEpiSCs) than to mouse ESCs. Finally, we identify a signature of chromatin modifications marking the boundaries of early replicating domains and a remarkably strong link between spatial proximity of chromatin as measured by Hi-C analysis and replication timing. Together, our results reveal evolutionarily conserved elements of the replication program in mammalian early development, demonstrate the power of replication profiling to identify important epigenetic distinctions between closely related stem cell populations (e.g. ESCs vs. EpiSCs), and strengthen the hypothesis that replication domains are structural and functional units of 3D chromosomal architecture. 8 cell types, with a total of 13 individual replicates (i.e. 5 in duplicates, 3 in single replicates)
2010-03-23 | E-GEOD-20027 | biostudies-arrayexpress
Project description:Facioscapulohumeral muscular dystrophy (FSHD) is linked to contraction of an array of tandem 3.3-kb repeats (D4Z4) at 4q35.2 from 11-100 copies to 1-10 copies. The extent to which D4Z4 contraction at 4q35.2 affects overall 4q35.2 chromatin organization remains unclear. Because DNA replication timing is highly predictive of long-range chromatin interactions, we generated genome-wide replication-timing profiles for FSHD and control myogenic precursor cells. We compared non-immortalized myoblasts from four FSHD patients and three control individuals to each other and to a variety of other human cell types. This study also represents the first genome-wide comparison of replication timing profiles in non-immortalized human cell cultures. Myoblasts from both control and FSHD individuals all shared a myoblast-specific replication profile. In contrast, male and female individuals were readily distinguished by monoallelic differences in replication timing at DXZ4 and other regions across the X chromosome affected by X inactivation. We conclude that replication timing is a robust cell-type specific feature that is unaffected by FSHD-related D4Z4 contraction. Profile comparison of myoblast cultures from four FSHD patients and three control individuals
2011-12-06 | E-GEOD-34197 | biostudies-arrayexpress
Project description:Abnormal replication timing has been observed in cancer but no study has comprehensively evaluated this misregulation. We generated genome-wide replication timing profiles for pediatric leukemias from 17 patients and 3 cell lines, as well as normal B and T cells. Non-leukemic EBV-transformed lymphoblastoid cell lines displayed highly stable replication timing profiles that were more similar to normal T cells than to leukemias. Leukemias were more similar to each other than to B and T cells but were considerably more heterogeneous than non-leukemic controls. Some differences were patient-specific while others were found in all leukemic samples, potentially representing early epigenetic events. Differences encompassed large segments of chromosomes and included genes implicated in other types of cancer. Remarkably, differences that distinguished leukemias aligned in register to the boundaries of developmentally regulated replication timing domains that distinguish normal cell types. Most changes did not coincide with copy number variation or translocations. However, many of the changes that were associated with translocations in some leukemias were also shared between all leukemic samples independent of the genetic lesion, suggesting that they precede and possibly predispose chromosomes to the translocation. Altogether, our results identify sites of abnormal developmental control of DNA replication in cancer that reveal the significance of replication timing boundaries to chromosome structure and function and support the replication domain model of replication timing regulation. They also open new avenues of investigation into the chromosomal basis of cancer and provide a potential novel source of epigenetic cancer biomarkers. Four karyotypically normal B-lymphoblastoid cell types with two replicates each, one peripheral T-lymphoblast replicate, 3 leukemic cell lines with 1-3 replicates each, 17 patient samples with 1-3 replicates each (total of 40 individual replicates)
2012-05-16 | E-GEOD-37987 | biostudies-arrayexpress
Project description:In multicellular organisms, developmental changes to replication timing occur in 400- 800 kb domains across half the genome. While clear examples of epigenetic control of replication timing have been described, a role for DNA sequence in mammalian replication timing has not been substantiated. To assess the role of DNA sequences in directing these changes, we profiled replication timing in mice carrying a genetically rearranged Human Chromosome 21 [Hsa21]. In two distinct mouse cell types, Hsa21 sequences maintained human-specific replication timing, except at points of Hsa21 rearrangement. Changes in replication timing at rearrangements extended up to 900 kb and consistently reconciled with the wild-type replication pattern at developmental boundaries of replication-timing domains. Our results demonstrate DNA sequencedriven regulation of Hsa21 replication timing during development and provide evidence that mammalian chromosomes consist of multiple independent units of replication timing regulation. Profile comparison of fibroblast and T-cell cultures from trans-chromosomic mice and human and mouse controls.
2012-06-04 | E-GEOD-38472 | biostudies-arrayexpress
Project description:The expansion of repressive epigenetic marks has been implicated in heterochromatin formation during embryonic development, but the general applicability of this mechanism is unclear. Here we show that nuclear rearrangement of repressive histone marks H3K9me3 and H3K27me3 into non-overlapping structural layers characterizes senescence-associated heterochromatic foci (SAHF) formation in human fibroblasts. However, the global landscape of these repressive marks remains unchanged upon SAHF formation, suggesting that in somatic cells heterochromatin can be formed through the spatial repositioning of pre-existing repressively marked histones. This model is reinforced by the correlation of pre-senescent replication timing with both the subsequent layered structure of SAHFs and the global landscape of the repressive marks, allowing us to integrate microscopic and genomic information. Furthermore, modulation of SAHF structure does not affect the occupancy of these repressive marks nor vice versa. These experiments reveal that high-order heterochromatin formation and epigenetic remodeling of the genome can be discrete events. Profile comparison of normal growing (control) and Ras-induced senescent IMR90 cells.
2012-06-30 | E-GEOD-38460 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the following subset Series: GSE18076: G9a selectively represses a class of late-replicating genes at the nuclear periphery (Expression) GSE18079: G9a selectively represses a class of late-replicating genes at the nuclear periphery (WG_CGH) Refer to individual Series
2009-11-02 | E-GEOD-18082 | biostudies-arrayexpress