Similar Datasets
Project description:DNA methylation undergoes dramatic age-related changes, first described more than four decades ago. Loss of DNA methylation within partially methylated domains (PMDs), late-replicating regions of the genome attached to the nuclear lamina, advances with age in normal tissues, and is further exacerbated in cancer. We present here experimental evidence that this DNA hypomethylation is directly driven by proliferation-associated DNA replication. Within PMDs, loss of DNA methylation at low-density CpGs in A:T-rich immediate context (PMD solo-WCGWs) tracks cumulative population doublings in primary cell culture. Cell cycle deceleration results in a proportional decrease in the rate of DNA hypomethylation. Blocking DNA replication via Mitomycin C treatment halts methylation loss. Loss of methylation continues unabated after TERT immortalization until finally reaching a severely hypomethylated equilibrium. Ambient oxygen culture conditions increases the rate of methylation loss compared to low-oxygen conditions, suggesting that some methylation loss may occur during unscheduled, oxidative damage repair-associated DNA synthesis. Finally, we present and validate a model to estimate the relative cumulative replicative histories of human cells, which we call "RepliTali" (Replication Times Accumulated in Lifetime).
| S-EPMC9643452 | biostudies-literature
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: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: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:Cell division drives DNA methylation loss in late-replicating domains in primary human cells
| PRJNA810863 | ENA
Project description:Cell division drives DNA methylation loss in late-replicating domains in primary human cells [methylation array]
| PRJNA810865 | ENA
Project description:Cell division drives DNA methylation loss in late-replicating domains in primary human cells [RNA-seq]
| PRJNA810446 | ENA
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:Transposable elements (TE) are typically silenced by DNA methylation and repressive histone modifications in differentiated healthy human tissues. However, TE expression increases in a wide range of cancers and is correlated with global hypomethylation of cancer genomes. We assessed expression and DNA methylation of TEs in fibroblast cells that were serially transduced with hTERT, SV40, and HRASR24C to immortalize and then transform them, modeling the different steps of the tumorigenesis process. RNA sequencing and whole-genome bisulfite sequencing were performed at each stage of transformation. TE expression significantly increased as cells progressed through transformation, with the largest increase in expression after the final stage of transformation, consistent with data from human tumors. The upregulated TEs were dominated by endogenous retroviruses [long terminal repeats (LTR)]. Most differentially methylated regions (DMR) in all stages were hypomethylated, with the greatest hypomethylation in the final stage of transformation. A majority of the DMRs overlapped TEs from the RepeatMasker database, indicating that TEs are preferentially demethylated. Many hypomethylated TEs displayed a concordant increase in expression. Demethylation began during immortalization and continued into transformation, while upregulation of TE transcription occurred in transformation. Numerous LTR elements upregulated in the model were also identified in The Cancer Genome Atlas datasets of breast, colon, and prostate cancer. Overall, these findings indicate that TEs, specifically endogenous retroviruses, are demethylated and transcribed during transformation.SignificanceAnalysis of epigenetic and transcriptional changes in a transformation model reveals that transposable element expression and methylation are dysregulated during oncogenic transformation.
| S-EPMC10527578 | biostudies-literature