Project description:This SuperSeries is composed of the following subset Series: GSE37065: Long-term culture associated gene expression changes in MSC [Affymetrix] GSE37066: Pluripotent Stem Cells Escape From Senescence-Associated DNA Methylation Changes [Illumina] GSE38806: Gene expression profiles of induced pluripotent mesenchymal stromal cells [Affymetrix] Refer to individual Series
Project description:Pluripotent stem cells evade replicative senescence, whereas other primary cells lose their proliferation and differentiation potential after a limited number of cell divisions M-bM-^@M-^S and this is accompanied by specific senescence-associated DNA methylation (SA-DNAm) changes. Here, we investigate SA-DNAm changes in mesenchymal stromal cells (MSC) upon long-term culture, irradiation-induced senescence, immortalization and reprogramming into induced pluripotent stem cells (iPSC) using high density HumanMethylation450 BeadChips. SA-DNAm changes are highly reproducible and occur particularly in intergenic and non-promoter regions of developmental genes. We demonstrate that ionizing irradiation, although associated with a very similar senescence phenotype, does not affect SA-DNAm. Furthermore, overexpression of the catalytic subunit of the human telomerase (TERT) or conditional immortalization with a doxycycline-inducible system (TERT and SV40 TAg) result in telomere extension but do not influence SA-DNAm. In contrast, we demonstrate that reprogramming into iPSC prevented SA-DNAm changes. Our results indicate that replicative senescence is associated with an epigenetically controlled process which stalls cells in a particular differentiated state, whereas irradiation-induced senescence and immortalization are not causally related to this process. Absence of SA-DNAm in pluripotent cells may play a central role for their escape from cellular senescence. Samples were hybridised to the Illumina Infinium 450k Human Methylation Beadchip
Project description:Altered DNA methylation and associated destabilization of genome integrity and function is a hallmark of cancer. Replicative senescence imposes a limit on proliferative potential that all cancer cells must bypass. Compared to proliferating cells, senescent cells exhibit marked chromatin re-organization. Here we show by whole-genome single-nucleotide bisulfite sequencing that replicative senescent human cells exhibit widespread alterations in their DNA methylome. These changes are linked to mislocalization of the maintenance DNA methyltransferase (DNMT1) in cells approaching senescence, altered replication-coupled DNA methylation and de-repression of repetitive satellite sequences. Deficiency of DNMT1 triggers chromatin changes characteristic of senescence and expression of satellite sequences. Most importantly, but paradoxically, gains and losses of methylation in replicative senescence are similar to those in cancer, and this M-bM-^@M-^XreprogrammedM-bM-^@M-^Y methylation landscape is largely retained when cells escape or bypass senescence. In sum, altered regulation of DNMT1 in cells approaching replicative senescence contributes to changes in chromatin structure and function. Consequently, if senescent cells escape the proliferative barrier, they already harbor epigenetic changes likely to promote malignancy. Examination of methylation status in IMR90 cells
Project description:Pluripotent stem cells evade replicative senescence, whereas other primary cells lose their proliferation and differentiation potential after a limited number of cell divisions – and this is accompanied by specific senescence-associated DNA methylation (SA-DNAm) changes. Here, we investigate SA-DNAm changes in mesenchymal stromal cells (MSC) upon long-term culture, irradiation-induced senescence, immortalization and reprogramming into induced pluripotent stem cells (iPSC) using high density HumanMethylation450 BeadChips. SA-DNAm changes are highly reproducible and occur particularly in intergenic and non-promoter regions of developmental genes. We demonstrate that ionizing irradiation, although associated with a very similar senescence phenotype, does not affect SA-DNAm. Furthermore, overexpression of the catalytic subunit of the human telomerase (TERT) or conditional immortalization with a doxycycline-inducible system (TERT and SV40 TAg) result in telomere extension but do not influence SA-DNAm. In contrast, we demonstrate that reprogramming into iPSC prevented SA-DNAm changes. Our results indicate that replicative senescence is associated with an epigenetically controlled process which stalls cells in a particular differentiated state, whereas irradiation-induced senescence and immortalization are not causally related to this process. Absence of SA-DNAm in pluripotent cells may play a central role for their escape from cellular senescence.
Project description:Altered DNA methylation and associated destabilization of genome integrity and function is a hallmark of cancer. Replicative senescence imposes a limit on proliferative potential that all cancer cells must bypass. Compared to proliferating cells, senescent cells exhibit marked chromatin re-organization. Here we show by whole-genome single-nucleotide bisulfite sequencing that replicative senescent human cells exhibit widespread alterations in their DNA methylome. These changes are linked to mislocalization of the maintenance DNA methyltransferase (DNMT1) in cells approaching senescence, altered replication-coupled DNA methylation and de-repression of repetitive satellite sequences. Deficiency of DNMT1 triggers chromatin changes characteristic of senescence and expression of satellite sequences. Most importantly, but paradoxically, gains and losses of methylation in replicative senescence are similar to those in cancer, and this ‘reprogrammed’ methylation landscape is largely retained when cells escape or bypass senescence. In sum, altered regulation of DNMT1 in cells approaching replicative senescence contributes to changes in chromatin structure and function. Consequently, if senescent cells escape the proliferative barrier, they already harbor epigenetic changes likely to promote malignancy.
Project description:Primary cells enter replicative senescence after a limited number of cell divisions. This process is associated with reproducible changes in DNA methylation (DNAm) at specific sites in the genome. The mechanism that drives senescence-associated DNAm changes remains unknown and may arise through drift in DNAm or through regulated, senescence dependent modifications at specific sites in the genome. In this study, we analyzed the reorganization of nuclear architecture and DNA methylation during long-term culture of human fibroblasts and mesenchymal stromal cells (MSCs). [MethylCap-seq] Fibroblasts of two female donors (both 43 years old) were culture expanded and DNA was harvested of 10,000,000 cells at early passage (P3 or P5) and late passage (P30 and P33). DNA methylation changes were subsequently analyzed by MethylCap-Seq.
Project description:DNA methylation is an epigenetic modification that specifies the basic state of pluripotent stem cells and regulates the developmental transition from stem cells to various cell types. In flowering plants, the shoot apical meristem (SAM) contains a pluripotent stem cell population which generates the aerial part of plants including the germ cells. Under appropriate conditions, the SAM undergoes a developmental transition from a leaf-forming vegetative SAM to an inflorescence- and flower-forming reproductive SAM. While SAM characteristics are largely altered in this transition, the complete picture of DNA methylation remains elusive. Here, by analyzing whole-genome DNA methylation of isolated rice SAMs in the vegetative and reproductive stages, we found that methylation at CHH sites is kept high, particularly at transposable elements (TEs), in the vegetative SAM relative to the differentiated leaf, and increases in the reproductive SAM via the RNA-dependent DNA methylation pathway. We also found that half of the TEs that were highly methylated in gametes had already undergone CHH hypermethylation in the SAM. Our results indicate that changes in DNA methylation begin in the SAM long before germ cell differentiation to protect the genome from harmful TEs.
Project description:Pathogenic mutations in lamin A/C (LMNA) lead to nuclear structural abnormalities, mesenchymal tissue damage, and laminopathies, which have numerous tissue-specific and progeria phenotypes. However, how LMNA mutations lead to accelerated mesenchymal-derived cell senescence remains unclear. Here, we established a replicative senescence model in vitro using induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs) from patients with homozygous LMNA p.R527C mutation (LMNA R527C iMSCs). R527C iMSCs exhibited marked cell senescence and stemness potential attenuation, accompanied by immunophenotypic changes when expanded to passage 13 in vitro. Proteome analysis revealed that DNA replication, nuclear structure, and chromatin-related gene sets were the most significant changes in R527C iMSCs during replicative senescence, and pathways such as cell cycle, DNA replication, cell adhesion, and inflammation might play important roles in senescence.
Project description:Cells in culture undergo replicative senescence. In this study, we analyzed functional, genetic and epigenetic sequels of long‐term culture in human mesenchymal stem cells (MSC). Already within early passages the fibroblastoid colony‐ forming unit (CFU‐f) frequency and the differentiation potential of MSC declined significantly. Relevant chromosomal aberrations were not detected by karyotyping and SNP‐microarrays. Subsequently, we have compared DNA‐methylation profiles with the Infinium HumanMethylation27 Bead Array and the profiles differed markedly in MSC derived from adipose tissue and bone marrow. Notably, all MSC revealed highly consistent senescence‐associated modifications at specific CpG sites. These DNA‐methylation changes correlated with histone marks of previously published data sets, such as trimethylation of H3K9, H3K27 and EZH2 targets. Taken together, culture expansion of MSC has profound functional implications ‐ these are hardly reflected by genomic instability but they are associated with highly reproducible DNA‐methylation changes which correlate with repressive histone marks. Therefore replicative senescence seems to be epigenetically controlled. 8 samples of mesenchymal stem cells (MSC) from human adipose tissue