Similar Datasets
Project description:We present the first experimental evidence that loss of DNA methylation at late-replicating regions, widely documented in aging and cancer, is directly driven by cell division. DNA hypomethylation, particularly at low-density CpGs in A:T-rich, partially methylated domains (PMD solo-WCGWs), tracks cumulative population doublings in primary cell culture. Cell cycle deceleration or full arrest resulted in a proportional decrease in the rate of DNA methylation loss. Lower culture oxygen conditions resulted in a slowed rate of methylation loss, suggesting that these CpGs may also be vulnerable to methylation loss during unscheduled, repair-associated methylation maintenance as well as scheduled, replication-associated methylation maintenance. By studying this methylation context in immortalized primary cells, we identified genomic and epigenomic features that are resistant or more susceptible to methylation loss. Finally, we leveraged this extensive DNA methylation dataset to develop a refined metric for the relative cumulative mitotic histories of human cells. These RNA-sequencing data accompany the larger DNA methylation dataset.
2022-07-25 | GSE197512 | GEO
Project description:We present the first experimental evidence that loss of DNA methylation at late-replicating regions, widely documented in aging and cancer, is directly driven by cell division. DNA hypomethylation, particularly at low-density CpGs in A:T-rich, partially methylated domains (PMD solo-WCGWs), tracks cumulative population doublings in primary cell culture. Cell cycle deceleration or full arrest resulted in a proportional decrease in the rate of DNA methylation loss. Lower culture oxygen conditions resulted in a slowed rate of methylation loss, suggesting that these CpGs may also be vulnerable to methylation loss during unscheduled, repair-associated methylation maintenance as well as scheduled, replication-associated methylation maintenance. By studying this methylation context in immortalized primary cells, we identified genomic and epigenomic features that are resistant or more susceptible to methylation loss. Finally, we leveraged this extensive DNA methylation dataset to develop a refined metric for the relative cumulative mitotic histories of human cells. These RNA-sequencing data accompany the larger DNA methylation dataset.
2022-07-25 | GSE197471 | GEO
Project description:DNA methylation loss occurs frequently in cancer genomes, primarily within lamina-associated, late-replicating regions termed partially methylated domains (PMDs). We profiled 39 diverse primary tumors and 8 matched adjacent tissues using whole-genome bisulfite sequencing (WGBS) and analyzed them alongside 343 additional human and 206 mouse WGBS datasets. We identified a local CpG sequence context associated with preferential hypomethylation in PMDs. Analysis of CpGs in this context ('solo-WCGWs') identified previously undetected PMD hypomethylation in almost all healthy tissue types. PMD hypomethylation increased with age, beginning during fetal development, and appeared to track the accumulation of cell divisions. In cancer, PMD hypomethylation depth correlated with somatic mutation density and cell cycle gene expression, consistent with its reflection of mitotic history and suggesting its application as a mitotic clock. We propose that late replication leads to lifelong progressive methylation loss, which acts as a biomarker for cellular aging and which may contribute to oncogenesis.
| S-EPMC5893360 | biostudies-literature
Project description:The methylation state of lysine 20 on histone H4 (H4K20) has been linked to chromatin compaction, transcription, DNA repair and DNA replication. Monomethylation of H4K20 (H4K20me1) is mediated by the cell cycle-regulated histone methyltransferase PR-Set7. PR-Set7 depletion in mammalian cells results in defective S phase progression and the accumulation of DNA damage, which has been partially attributed to defects in origin selection and activation. However, these studies were limited to only a handful of mammalian origins, and it remains unclear how PR-Set7 and H4K20 methylation impact the replication program on a genomic scale. We employed genetic, cytological, and genomic approaches to better understand the role of PR-Set7 and H4K20 methylation in regulating DNA replication and genome stability in Drosophila cells. We find that deregulation of H4K20 methylation had no impact on origin activation throughout the genome. Instead, depletion of PR-Set7 and loss of H4K20me1 results in the accumulation of DNA damage and an ATR-dependent cell cycle arrest. Coincident with the ATR-dependent cell cycle arrest, we find increased DNA damage that is specifically limited to late replicating regions of the Drosophila genome, suggesting that PR-Set7-mediated monomethylation of H4K20 is critical for maintaining the genomic integrity of late replicating domains.
| S-EPMC5009726 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2011-08-06 | GSE27538 | GEO
Project description:Heterochromatin is believed to be associated with increased levels of cytosine methylation. With the recent availability of genome-wide, high-resolution molecular data reflecting chromatin organization and methylation, such relationships can be explored systematically. As well-defined surrogates for heterochromatin, we tested the relationship between DNA replication timing and DNase hypersensitivity with cytosine methylation in two human cell types, unexpectedly finding the later-replicating, more heterochromatic regions to be less methylated than early replicating regions. When we integrated gene-expression data into the study, we found that regions of increased gene expression were earlier replicating, as previously identified, and that transcription-targeted cytosine methylation in gene bodies contributes to the positive correlation with early replication. A self-organizing map (SOM) approach was able to identify genomic regions with early replication and increased methylation, but lacking annotated transcripts, loci missed in simple two variable analyses, possibly encoding unrecognized intergenic transcripts. We conclude that the relationship of cytosine methylation with heterochromatin is not simple and depends on whether the genomic context is tandemly repetitive sequences often found near centromeres, which are known to be heterochromatic and methylated, or the remaining majority of the genome, where cytosine methylation is targeted preferentially to the transcriptionally active, euchromatic compartment of the genome.
| S-EPMC3205568 | biostudies-literature
Project description:The methylation state of lysine 20 on histone H4 (H4K20) has been linked to cell cycle progression, Origin Recognition Complex (ORC) binding, and replication origin regulation. Monomethylation of H4K20 (H4K20me1) is mediated by the cell cycle-regulated histone methyltransferase PR-Set7, which is essential for genome integrity and cell cycle progression. PR-Set7 depletion in mammalian cells results in defective S-phase progression and the accumulation of DNA damage, which could be partially attributed to a defect in pre-Replication Complex (pre-RC) formation and origin activity. However, these studies were limited to a handful of mammalian origins, and it remains unclear how PR-Set7 and H4K20 methylation impact the replication program on a genomic scale. Using Drosophila Kc167 cells, we employed genetic, cytological, and genomic approaches to better understand the role of PR-Set7 and H4K20 methylation in regulating DNA replication and governing genome stability. We find that depletion of Drosophila PR-Set7 and loss of H4K20me1 result in the accumulation of DNA damage and an ATR-dependent cell cycle arrest. The cell cycle arrest occurs during the second S-phase following loss of PR-Set7 activity, suggesting that accumulation of nascent H4K20 is recalcitrant to the DNA replication program. Deregulation of H4K20 methylation had no impact on origin activation throughout the genome; instead, we found that the DNA damage marker, phosphorylated H2A.v (γ-H2A.v), accumulated specifically in late replicating domains in the absence of PR-Set7. This suggests that the molecular basis for the cell cycle arrest and accumulation of DNA damage resulting from loss of PR-Set7 is stochastic fork collapse within late replicating domains.
2015-10-08 | GSE73668 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below.
2023-06-27 | GSE231780 | GEO
Project description: Not available
| S-BSST966 | biostudies-other
Project description:In mammals sequences that are either late replicating or highly recombining have high rates of evolution at putatively neutral sites. As early replicating domains and highly recombining domains both tend to be GC rich we a priori expect these two variables to covary. If so, the relative contribution of either of these variables to the local neutral substitution rate might have been wrongly estimated owing to covariance with the other. Against our expectations, we find that sex-averaged recombination rates show little or no correlation with replication timing, suggesting that they are independent determinants of substitution rates. However, this result masks significant sex-specific complexity: late replicating domains tend to have high recombination rates in females but low recombination rates in males. That these trends are antagonistic explains why sex-averaged recombination is not correlated with replication timing. This unexpected result has several important implications. First, although both male and female recombination rates covary significantly with intronic substitution rates, the magnitude of this correlation is moderately underestimated for male recombination and slightly overestimated for female recombination, owing to covariance with replicating timing. Second, the result could explain why male recombination is strongly correlated with GC content but female recombination is not. If to explain the correlation between GC content and replication timing we suppose that late replication forces reduced GC content, then GC promotion by biased gene conversion during female recombination is partly countered by the antagonistic effect of later replicating sequence tending increase AT content. Indeed, the strength of the correlation between female recombination rate and local GC content is more than doubled by control for replication timing. Our results underpin the need to consider sex-specific recombination rates and potential covariates in analysis of GC content and rates of evolution.
| S-EPMC3176772 | biostudies-literature