Ontology highlight
ABSTRACT:
PROVIDER: PRJNA813416 | ENA |
REPOSITORIES: ENA
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Project description:We sequenced and characterised inter-chromosomal and intra-chromosomal telomere fusions amplified from crisis-stage MCR5HPVE6E7 fibroblasts and DNA repair-compromised HCT116 cell lines nucleofected with plasmids encoding TALEN pairs to induce targeted cleavage at the 17p telomere.
2016-02-24 | E-MTAB-3811 | biostudies-arrayexpress
Project description:Telomeres play crucial roles during tumorigenesis inducing cellular senescence upon telomere shortening and extensive chromosome instability during telomere crisis. However, it has not been investigated if and how cellular transformation and oncogenic stress alters telomeric chromatin composition and function. Here we transform human fibroblasts by consecutive transduction with vectors expressing hTERT, the SV40 early region and activated H-RasV12. Pairwise comparisons of the telomeric proteome during different stages of transformation reveals upregulation of proteins involved in chromatin remodeling, DNA repair and replication at chromosome ends. Depletion of several of these proteins induces telomere fragility indicating their roles in replication of telomeric DNA. Depletion of SAMHD1, which has reported roles in DNA resection and homology directed repair, leads to telomere breakage events in cells deprived of the shelterin component TRF1. Thus our analysis identifies factors, which accumulate at telomeres during cellular transformation to promote telomere replication and repair, resisting oncogene-borne telomere replication stress.
2018-07-13 | PXD010088 | Pride
Project description:The human A-family DNA polymerase M-NM-8 (Pol q) is a large, multidomain enzyme whose physiological function is still unclear despite its in vitro translesion synthesis capacity in front of DNA damage and its involvement in some features of DNA repair after external stress. Here we present evidence that Pol q holds a novel role in the absence of external stress as a critical determinant of the replication timing program in human cells. Pol q binds to chromatin at early G1 and is required for proper formation of pre-replicative complexe and replication origin activation. Pol q-depleted cells show modified spatial organization of chromatin-loop structures at replication factories. Genome-wide analysis of replication timing shows delayed replication of a part of early replicating domains and advanced replication of a part of late replicating domains following Pol q depletion. Our results identify Pol q as one of the first critical human factors discovered in the replication timing programme. Two-condition experiment, siRNA control vs. siRNA polQ cells. Biological replicates: 2 control replicates, 2 transfected replicates.
2014-06-19 | E-GEOD-49693 | biostudies-arrayexpress
Project description:The human A-family DNA polymerase M-NM-8 (Pol q) is a large, multidomain enzyme whose physiological function is still unclear despite its in vitro translesion synthesis capacity in front of DNA damage and its involvement in some features of DNA repair after external stress. Here we present evidence that Pol q holds a novel role in the absence of external stress as a critical determinant of the replication timing program in human cells. Pol q binds to chromatin at early G1 and is required for proper formation of pre-replicative complexe and replication origin activation. Pol q-depleted cells show modified spatial organization of chromatin-loop structures at replication factories. Genome-wide analysis of replication timing shows delayed replication of a part of early replicating domains and advanced replication of a part of late replicating domains following Pol q depletion. Our results identify Pol q as one of the first critical human factors discovered in the replication timing programme. Two-condition experiment, control vs. over expressed polQ cells. Biological replicates: 2 control replicates, 2 transfected replicates.
2014-10-28 | E-GEOD-53070 | biostudies-arrayexpress
Project description:In Saccharomyces cerevisiae, Elevated Levels of Aneuploidy and Chromosome Rearrangements are Separable Genome Instability Events Controlled by the Tel1 and Mec1 Kinases Cancer cells often have elevated frequencies of chromosomal aberrations, and it is likely that loss of genome stability is one driving force behind tumorigenesis. Deficiencies in DNA replication, DNA repair, or cell cycle checkpoints can all contribute to increased rates of chromosomal duplications, deletions and translocations. The Saccharomyces cerevisiae proteins Tel1 and Mec1 (homologues of the human ATM and ATR proteins, respectively) are known to participate in the DNA damage response, replication checkpoint, and telomere maintenance pathways and are critical to maintain genome stability. In the absence of induced DNA damage, tel1 mec1 diploid yeast strains exhibit extremely high rates of chromosome aneuploidy. There is a significant bias towards trisomy of chromosomes II, VIII, X, and XII, whereas the smallest chromosomes I and VI are commonly monosomic. tel1 mec1 strains also demonstrate elevated levels of chromosome rearrangements, including translocations as well as interstitial duplications and deletions. Restoring wild-type telomere length with the Cdc13-Est2 fusion protein substantially reduces the amount of chromosome rearrangements in tel1 mec1 strains. This result suggests that most of the rearrangements are initiated by telomere-telomere fusions. However, the telomere defects associated with tel1 mec1 strains do not cause the high rate of aneuploidy, as restoring proper telomere function does not prevent cells from becoming aneuploid. Our data demonstrate that the same mutant genotype can produce both high levels of chromosome rearrangements and high levels of aneuploidy, and these two types of events occur through separate mechanisms.
2009-09-03 | GSE17903 | GEO
Project description:Alternative Lengthening of Telomeres (ALT) cancer cells are a subset of cancers that depend on the homologous recombination mechanism to extend their telomere length independent of telomerase. ALT cells contain elevated levels of the telomeric-repeat containing long noncoding RNA (TERRA), which is an RNA transcribed by RNA polymerase II and can form RNA:DNA (R-loops) hybrids at telomeres. Lines of evidence have shown that the formation of R-loops at telomeres could be one of the mechanisms to trigger DNA repair to lengthen telomeres. We perform iDRiP-MS, a method to capture specific RNA interacting protein by UV light crosslinking using antisense probe capture (Chu et al., 2017a; Minajigi et al., 2015), to explore the TERRA interactomes in human ALT cancer cell. Our TERRA interactome data reveals that TERRA interacts with an extensive subset of DNA repair proteins in ALT cells including the endonuclease XPF, suggesting that TERRA R-loops activate DDR via XPF to promote homologous recombination and telomere replication to drive ALT.
2022-09-28 | PXD028882 | Pride
Project description:Genome catastrophe driven by break-induced-replication during a telomere crisis
| PRJNA417592 | ENA
Project description:Telomere dysfunction and fusion during the progression of chronic lymphocytic leukaemia: evidence for a telomere crisis
| PRJNA127433 | ENA
Project description:Telomere end-protection by the shelterin complex prevents DNA damage signalling and promiscuous repair at chromosome ends. Evidence suggests that the 3’ single-stranded telomere end can assemble into a lasso-like t-loop configuration, which has been proposed to safeguard chromosome ends from being recognized as DNA double strand breaks. Mechanisms must also exist to transiently disassemble t-loops to allow faithful telomere replication and to permit telomerase access to the 3’-end to solve the end replication problem. However, the regulation and physiological importance of t-loops in end-protection remains uncertain. Here, we identify a CDK phosphorylation site in the shelterin subunit, TRF2 (Ser365), whose dephosphorylation in S-phase by the PP6C/R3 phosphatase provides a narrow window during which the helicase RTEL1 is able to transiently access and unwind t-loops to facilitate telomere replication. Re-phosphorylation of TRF2 on Ser365 outside of S-phase is required to release RTEL1 from telomeres, which not only protects t-loops from promiscuous unwinding and inappropriate ATM activation, but also counteracts replication conflicts at DNA secondary structures arising within telomeres and across the genome. Hence, a phospho-switch in TRF2 coordinates assembly and disassembly of t-loops during the cell cycle, which protects telomeres from replication stress and an unscheduled DNA damage response.
2019-11-25 | PXD014843 | Pride