Similar Datasets
Project description:Down-regulation (DR) of PREP1 (aka PKNOX1) tumor suppressor induces H2Ax foci in human fibroblasts. Here we have analyzed the effect of PREP1 DR on DNA replication using cell cycle analysis, Repliseq, DNA combing, ChIP-seq, RNA-seq and immunofluorescence (IF). In human cells, PREP1 DR similarly affects both the rate of DNA replication and the progression of cells through the S phase. Genome wide, PREP1 DR induces late to early DNA replication shifts in normally late-replicated genomic regions amounting to 25% of the genome, in addition to unscheduled origins firing. A concomitant strong increase of unidirectional replication forks explains the appearance of DNA damage foci. The DNA target of PREP1 DR is the Lamin Associated DNA, in agreement with the simultaneous decrease of Lamin B1. Therefore PREP1 is a novel regulator of replication timing and Lamin B1 level, which ChIP-seq and RNA-seq data indicate as independent from its transcriptional activity. This activity must constitute the basis for its tumor suppression function.
2018-02-28 | GSE101774 | GEO
Project description:Down-regulation (DR) of PREP1 (aka PKNOX1) tumor suppressor induces H2Ax foci in human fibroblasts. Here we have analyzed the effect of PREP1 DR on DNA replication using cell cycle analysis, Repliseq, DNA combing, ChIP-seq, RNA-seq and immunofluorescence (IF). In human cells, PREP1 DR similarly affects both the rate of DNA replication and the progression of cells through the S phase. Genome wide, PREP1 DR induces late to early DNA replication shifts in normally late-replicated genomic regions amounting to 25% of the genome, in addition to unscheduled origins firing. A concomitant strong increase of unidirectional replication forks explains the appearance of DNA damage foci. The DNA target of PREP1 DR is the Lamin Associated DNA, in agreement with the simultaneous decrease of Lamin B1. Therefore PREP1 is a novel regulator of replication timing and Lamin B1 level, which ChIP-seq and RNA-seq data indicate as independent from its transcriptional activity. This activity must constitute the basis for its tumor suppression function.
2018-02-28 | GSE101773 | GEO
Project description:Down-regulation (DR) of PREP1 (aka PKNOX1) tumor suppressor induces H2Ax foci in human fibroblasts. Here we have analyzed the effect of PREP1 DR on DNA replication using cell cycle analysis, Repliseq, DNA combing, ChIP-seq, RNA-seq and immunofluorescence (IF). In human cells, PREP1 DR similarly affects both the rate of DNA replication and the progression of cells through the S phase. Genome wide, PREP1 DR induces late to early DNA replication shifts in normally late-replicated genomic regions amounting to 25% of the genome, in addition to unscheduled origins firing. A concomitant strong increase of unidirectional replication forks explains the appearance of DNA damage foci. The DNA target of PREP1 DR is the Lamin Associated DNA, in agreement with the simultaneous decrease of Lamin B1. Therefore PREP1 is a novel regulator of replication timing and Lamin B1 level, which ChIP-seq and RNA-seq data indicate as independent from its transcriptional activity. This activity must constitute the basis for its tumor suppression function.
2018-02-28 | GSE101775 | GEO
Project description:PREP1 down-regulation changes the DNA replication timing of Lamin-associated DNA and induces DNA damage
| PRJNA395422 | ENA
Project description:The synthesis of middle-to-late-replicating DNA can be affected independently of the rest of the genome by down-regulating the tumor suppressor PREP1 (PKNOX1). Indeed, DNA combing shows that PREP1 down-regulation affects DNA replication rate, increases the number of simultaneously firing origins and the asymmetry of DNA replication, leading to DNA damage. Genome-wide analysis of replication timing by Repli-seq shows that, upon PREP1 down-regulation, 25% of the genome is replicated earlier in the S-phase. The targeted DNA sequences correspond to Lamin-Associated Domains (LADs), and include late-replicating (LRRs) and temporal transition regions (TTRs). Notably, the distribution of PREP1 DNA binding sites and of its target genes indicates that DNA replication defects are independent of the overall PREP1 transcriptional activity. Finally, PREP1 down-regulation causes a substantial decrease in Lamin B1 levels. This suggests that DNA is released from the nuclear lamina earlier than in the control cells and is available for replication, thus explaining timing defects and DNA damage.This is the first evidence that the replication timing of a specific fraction of the human genome is affected by PREP1 tumor suppressor. This previously unknown function might significantly contribute to the genomic instability observed in human tumors.
| S-EPMC5816642 | biostudies-literature
Project description:The human LMNA gene encodes the essential nuclear envelope proteins lamin A and C (lamin A/C). Mutations in LMNA result in altered nuclear morphology, but how this impacts the mechanisms that maintain genomic stability is unclear. Here, we report that lamin A/C-deficient cells have a normal response to ionizing radiation but are sensitive to agents that cause interstrand cross-links (ICLs) or replication stress. In response to treatment with ICL agents (cisplatin, camptothecin, and mitomycin), lamin A/C-deficient cells displayed normal ?-H2AX focus formation but a higher frequency of cells with delayed ?-H2AX removal, decreased recruitment of the FANCD2 repair factor, and a higher frequency of chromosome aberrations. Similarly, following hydroxyurea-induced replication stress, lamin A/C-deficient cells had an increased frequency of cells with delayed disappearance of ?-H2AX foci and defective repair factor recruitment (Mre11, CtIP, Rad51, RPA, and FANCD2). Replicative stress also resulted in a higher frequency of chromosomal aberrations as well as defective replication restart. Taken together, the data can be interpreted to suggest that lamin A/C has a role in the restart of stalled replication forks, a prerequisite for initiation of DNA damage repair by the homologous recombination pathway, which is intact in lamin A/C-deficient cells. We propose that lamin A/C is required for maintaining genomic stability following replication fork stalling, induced by either ICL damage or replicative stress, in order to facilitate fork regression prior to DNA damage repair.
| S-EPMC3592031 | biostudies-literature
Project description:The tolerance pathway allows bypassing deleterious lesions that block replicative DNA polymerases. In eukaryotes tolerance is controlled by ubiquitylation of the DNA replication factor PCNA4. Here, we show that PCNAK164-ubiquitin proteases (PCNA-DUBs) Ubp10 and Ubp12 localise to replication forks. In particular, the main PCNA-DUB, Ubp10, associates primarily to nascent lagging strands. We also found that cells deficient for PCNA deubiquitylation show both increased interaction of TLS polymerase ζ-associated Rev1 with lagging strands and Rad52-dependent template switching events. This evidence reveals a fork-coupled layer of DDT regulation allowing strand-specific pathway choices.
2019-10-29 | GSE90157 | GEO
Project description:DNA replication is initiated at replication origins on chromosomes at their scheduled time during S phase of the cell cycle. Replication timing control is highly conserved among eukaryotes but the underlying mechanisms are not fully understood. Recent studies have revealed that some telomere-binding proteins regulate replication timing at late-replicating origins throughout the genome. To investigate the molecular basis of this process, we analyzed the effects of excessive elongation of telomere DNA on replication timing by deleting telomere-associated shelterin proteins in Schizosaccharomyces pombe. We found that rap1∆ and poz1∆ cells showed abnormally accelerated replication at internal late origins but not at subtelomere regions. These defects were suppressed by removal of telomere DNA and by deletion of the telomere-binding protein Taz1. Furthermore, Sds21-a counter protein phosphatase against Dbf4-dependent kinase (DDK)-accumulated at elongated telomeres in a Taz1-dependent manner but was depleted at internal late origins, indicating that highly elongated telomeres sequester Sds21 at telomeres and perturb replication timing at internal regions. These results demonstrate that telomere DNA length is an important determinant of replication timing at internal regions of chromosomes in eukaryotes.
| S-EPMC6617677 | biostudies-literature
Project description:Organismal aging entails a gradual decline of normal physiological functions and a major contributor to this decline is withdrawal of the cell cycle, known as senescence. Senescence can result from telomere diminution leading to a finite number of population doublings, known as replicative senescence (RS), or from oncogene overexpression, as a protective mechanism against cancer. Senescence is associated with large-scale chromatin re-organization and changes in gene expression. Replication stress is a complex phenomenon, defined as the slowing or stalling of replication fork progression and/or DNA synthesis, which has serious implications for genome stability, and consequently in human diseases. Aberrant replication fork structures activate the replication stress response leading to the activation of dormant origins, which is thought to be a safeguard mechanism to complete DNA replication on time. However, the relationship between replicative stress and the changes in the spatiotemporal program of DNA replication in senescence progression remains unclear. Here, we studied the DNA replication program during senescence progression in proliferative and pre-senescent cells from donors of various ages by single DNA fiber combing of replicated DNA, origin mapping by sequencing short nascent strands and genome-wide profiling of replication timing (TRT). We demonstrate that, progression into RS leads to reduced replication fork rates and activation of dormant origins, which are the hallmarks of replication stress. However, with the exception of a delay in RT of the CREB5 gene in all pre-senescent cells, RT was globally unaffected by replication stress during entry into either oncogene-induced or RS. Consequently, we conclude that RT alterations associated with physiological and accelerated aging, do not result from senescence progression. Our results clarify the interplay between senescence, aging and replication programs and demonstrate that RT is largely resistant to replication stress.
| S-EPMC6133336 | biostudies-literature
Project description:Protein acetylation is a reversible process regulated by histone deacetylases (HDAC) that is often altered in human cancers. Suberoylanilide hydroxamic acid (SAHA) is the first HDAC inhibitor to be approved for clinical use as an anticancer agent. Given that histone acetylation is a key determinant of chromatin structure, we investigated how SAHA may affect DNA replication and integrity to gain deeper insights into the basis for its anticancer activity. Nuclear replication factories were visualized with confocal immunofluorescence microscopy and single-replicon analyses were conducted by genome-wide molecular combing after pulse labeling with two thymidine analogues. We found that pharmacologic concentrations of SAHA induce replication-mediated DNA damage with activation of histone gammaH2AX. Single DNA molecule analyses indicated slowdown in replication speed along with activation of dormant replication origins in response to SAHA. Similar results were obtained using siRNA-mediated depletion of HDAC3 expression, implicating this HDAC member as a likely target in the SAHA response. Activation of dormant origins was confirmed by molecular analyses of the beta-globin locus control region. Our findings demonstrate that SAHA produces profound alterations in DNA replication that cause DNA damage, establishing a critical link between robust chromatin acetylation and DNA replication in human cancer cells.
| S-EPMC2880188 | biostudies-literature