Ontology highlight
ABSTRACT:
PROVIDER: PRJNA976756 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:DNA replication timing and 3D chromatin organisation are associated with epigenomic changes across large domains during human differentiation and cancer progression. However, it is unclear if epigenome changes, in particular cancer-associated DNA hypomethylation, is a consequence or cause of changes observed in higher order genome architecture. Here, we compare replication timing profiles and three dimensional (3D) genome organisation, using Hi-C and single cell Repli-Seq in the DNMT1 and DNMT3B DNA methyltransferases double knockout hypomethylated DKO1 colorectal cancer cell line and its parental HCT116 cell line. We find that the hypomethylated cells show a profound loss of replication timing precision, gain of single cell replication timing heterogeneity and loss of chromatin conformation integrity. Discrete regions, that undergo a large change in replication timing in the hypomethylated cells, are associated with a loss of allelic replication timing and shrinking of late replicating Partially Methylated Domain (PMD) boundaries. In contrast, conservation of replication timing after DNA methylation depletion at PMDs is associated with the formation of new H3K9me3/H3K4me3 bivalent domains which may serve to prevent ectopic transcription and maintain cell viability. Together our results show that a loss of global methylation, a common hallmark of cancer, directly impacts on the precision of replication timing and contribute to deregulation of the 3D chromatin architecture.
2021-09-21 | GSE159663 | GEO
Project description:G-quadruplex (or G4) structures are non-canonical DNA structures that form in guanine-rich sequences and threaten genome stability when not properly resolved. G4 unwinding occurs during S phase via an unknown mechanism. Using Xenopus egg extracts, we define a three-step G4 unwinding mechanism that acts during DNA replication. First, the replicative helicase (CMG) stalls at a leading strand G4 structure. Second, the DHX36 helicase mediates the bypass of the CMG past the intact G4 structure, which allows approach of the leading strand to the G4. Third, G4 structure unwinding by the FANCJ helicase enables the DNA polymerase to synthesize past the G4 motif. A G4 on the lagging strand template does not stall CMG, but still requires active DNA replication for unwinding. DHX36 and FANCJ have partially redundant roles, conferring robustness to this pathway. Our data reveal a novel genome maintenance pathway that promotes faithful G4 replication thereby avoiding genome instability.
2022-02-17 | PXD027623 | Pride
Project description:This experiment investigates the genome wide DNA methylation landscape of residual breast cancer cells. Primary mammary epithelial cells taken from female mice with doxycycline-inducible hMyc- and Neu/Her2-oncogenes were grown in 3D organoid cultures. Upon the addition of doxycycline (200ng/mL) to the medium the expression of the oncogenes gets activated and the cells start uncontrolled proliferation resembling tumor growth. Tumor samples were taken after 5 days of oncogene induction. Subsequently, doxycycline was removed from the medium, which silences oncogene expression and results in rapid tumor regression. Residual samples reminiscent to the non-induced (normal) structures were taken after 7 days of de-induction (12 days overall). Non-induced structures were grown and sampled in parallel to the residual structures.
2021-10-03 | E-MTAB-10979 | biostudies-arrayexpress
Project description:In eukaryotes, the nucleus is organized into a three dimensional structure consisting of both local interactions such as those between enhancers and promoters, and long-range higher-order structures such as nuclear bodies. This organization is central to many aspects of nuclear function, including DNA replication, transcription, and cell cycle progression. Nuclear structure intrinsically occurs within single cells; however, measuring such a broad spectrum of 3D DNA interactions on a genome-wide scale and at the single cell level has been a great challenge. To address this, we developed single-cell split-pool recognition of interactions by tag extension (scSPRITE), a new method that enables measurements of genome-wide maps of 3D DNA structure in thousands of individual nuclei. scSPRITE maximizes the number of DNA contacts detected per cell enabling high-resolution genome structure maps within each cells and is easy-to-use and cost-effective. scSPRITE accurately detects chromosome territories, active and inactive compartments, topologically associating domains (TADs), and higher-order structures within single cells. In addition, scSPRITE measures cell-to-cell heterogeneity in genome structure at different levels of resolution and shows that TADs are dynamic units of genome organization that can vary between different cells within a population. scSPRITE will improve our understanding of nuclear architecture and its relationship to nuclear function within an individual nucleus from complex cell types and tissues containing a diverse population of cells.
2020-08-12 | GSE154353 | GEO
Project description:The interior of the neuronal cell nucleus is a highly organized 3-dimensional (3D) structure in which regions of the genome that are millions of bases apart participate in specialized sub-structures with dedicated functions. To investigate neuronal chromatin organization and dynamics in vivo, we generated bitransgenic mice that express histone GFP-tagged H2B in principal neurons of the forebrain. Surprisingly, the expression of this chimeric histone in mature neurons causes chromocenter declustering and disrupts the association of heterochromatin with the nuclear lamina. The loss of these structures does not affect neuronal viability but is associated with specific transcriptional and behavioral deficits related to serotonergic dysfunction. Overall, our results demonstrate that the 3D-organization of chromatin in the neuronal nucleus supports an additional level of epigenetic regulation of gene expression that critically influences neuronal function and indicate that some loci associated with neuropsychiatric disorders may be particularly sensitive to changes in chromatin architecture. Genome-wide profiling by high throughput sequencing of H3K27me3 in the adult hippocampus of CaMKII-tTA/tetO-H2BGFP (H2BGFP) and their wild-type littermates mice (WT). Chromatin immunoprecipitation (ChIP) was carried out using pooled hippocampal tissue from 3 mice (one hippocampus per mouse). One DNA library was constructed per genotype. Each DNA library was prepared from pooled immunoprecipitated DNA from 4 independent ChIP assays. In total, tissue from 12 different mice was used to prepare each DNA library. 60% of a lane was used to perform single end (1x50bp) multiplex sequencing in HiSeq 2500 apparatus (Illumina). Each library, was sequenced in duplicate (in two independent sequencing runs. Technical replicates).
2014-07-18 | E-GEOD-56809 | biostudies-arrayexpress
Project description:To ensure efficient genome duplication, cells have evolved a multitude of factors that promote unperturbed DNA replication, and protect, repair and restart damaged forks. Here we identify DONSON as a novel fork protection factor, and report biallelic DONSON mutations in individuals with microcephalic dwarfism. We demonstrate that DONSON is a component of the replisome that stabilises forks during normal genome replication. Loss of DONSON leads to severe replication-associated DNA damage arising from nucleolytic cleavage of stalled replication forks. Furthermore, ATR-dependent ,signalling in response to replication stress is impaired in DONSON-deficient cells, resulting in decreased checkpoint activity, and potentiating chromosomal instability. Hypomorphic mutations substantially reduce DONSON protein levels and impair fork stability in patient cells, consistent with defective DNA replication underlying the disease phenotype In summary, we identify mutations in DONSON as a common cause of microcephalic dwarfism, and establish DONSON as a critical replication fork protein required for mammalian DNA replication and genome stability
2017-03-28 | MSV000080704 | MassIVE
Project description:The chromatins are folded into three-dimensional (3D) structures, and aberrant chromatin 3D folding has been shown in cancer. We performed ATAC-seq and TOP2A ChIP-seq to profile the potential effects of different anthracyclines on the chromatin. We identified that unique anthracycline variants selectively target chromatin looping anchors via disrupting CTCF binding, suggesting an additional potential therapeutic effect on the 3D genome. We further performed Hi-C experiments, and data from K562 cells treated with the selective anthracycline drugs indicate that the global 3D chromatin organizations were disrupted dramatically, as exemplified by the disruption of distal regulation of the Myc gene. Furthermore, AML patients receiving anthracycline drugs showed altered chromatin structures around potential looping anchors, which linked to distinct clinical outcomes. Our data indicate that anthracyclines are potent and selective epigenomic targeting drugs and can further target the 3D genome for anticancer effects, which could be explored for personalized medicine to treat tumors with aberrant 3D chromatin structures.
2025-01-14 | GSE285987 | GEO
Project description:DNA replication timing and 3D chromatin organisation are associated with epigenomic changes across large domains during human differentiation and cancer progression. However, it is unclear if epigenome changes, in particular cancer-associated DNA hypomethylation, is a consequence or cause of changes observed in higher order genome architecture. Here, we compare replication timing profiles and three dimensional (3D) genome organisation, using Hi-C and single cell Repli-Seq in the DNMT1 and DNMT3B DNA methyltransferases double knockout hypomethylated DKO1 colorectal cancer cell line and its parental HCT116 cell line. We find that the hypomethylated cells show a profound loss of replication timing precision, gain of single cell replication timing heterogeneity and loss of chromatin conformation integrity. Discrete regions, that undergo a large change in replication timing in the hypomethylated cells, are associated with a loss of allelic replication timing and shrinking of late replicating Partially Methylated Domain (PMD) boundaries. In contrast, conservation of replication timing after DNA methylation depletion at PMDs is associated with the formation of new H3K9me3/H3K4me3 bivalent domains which may serve to prevent ectopic transcription and maintain cell viability. Together our results show that a loss of global methylation, a common hallmark of cancer, directly impacts on the precision of replication timing and contribute to deregulation of the 3D chromatin architecture.
2021-09-21 | GSE158010 | GEO