Cohesin causes replicative DNA damage by trapping DNA topological stress
Ontology highlight
ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae Schizosaccharomyces pombe
PROVIDER: GSE131558 | GEO | 2020/03/03
REPOSITORIES: GEO
Similar Datasets
Project description:Cohesin causes replicative DNA damage by trapping DNA topological stress
| PRJNA544023 | ENA
Project description:The cohesin complex is mutated in cancer and in a number of rare familiar syndromes collectively known as Cohesinopathies. In the latter case, cohesin deficiencies have been linked to transcriptional alterations affecting Myc and its target genes. Here, we set out to understand to what extent the role of cohesins in controlling cell cycle is dependent on Myc expression and activity. Inactivation of the cohesin complex by silencing the RAD21 subunit led to cell cycle arrest due to both transcriptional impairment of Myc target genes and alterations of replication forks, which were fewer and preferentially unidirectional. Ectopic activation of Myc in RAD21 depleted cells, fully rescued transcription and promoted S-phase entry but failed to sustain S-phase progression thus leading to a strong replicative stress response, which was associated to a robust DNA damage response, DNA damage checkpoint activation and synthetic lethality. Thus, the cohesin complex is dispensable for Myc dependent transcription but essential to prevent Myc induced replicative stress. This suggests the presence of a topological checkpoint orchestrated by cohesins that by regulating Myc level prevents S-phase entry and replicative stress in cohesion compromised cells.
2017-12-22 | GSE89799 | GEO
Project description:The chromosomal condensin complex gives metaphase chromosomes structural stability. In addition, condensin is required for sister chromatid resolution during their segregation in anaphase. How condensin promotes chromosome resolution is poorly understood. Chromosome segregation during anaphase also fails after inactivation of topoisomerase II (topo II), the enzyme that removes catenation between sister chromatids left behind after completion of DNA replication. This has led to the proposal that condensin promotes DNA decatenation, but direct evidence for this is missing and alternative roles for condensin in chromosome resolution have been suggested. Using the budding yeast rDNA as a model, we now show that anaphase bridges in a condensin mutant are resolved by ectopic expression of a foreign (Chlorella virus) but not endogenous topo II. This suggests that catenation prevents sister rDNA segregation, and that yeast topo II is ineffective in decatenating the locus without condensin. Condensin and topo II colocalize along both rDNA and euchromatin, consistent with coordination of their activities. We investigate the physiological consequences of condensin-dependent rDNA decatenation and find that late decatenation determines the late segregation timing of this locus during anaphase. Regulation of decatenation therefore provides a means to finetune segregation timing of chromosomes in mitosis. Keywords: ChIP-chip, Cell Cycle
2008-07-18 | GSE11988 | GEO
Project description:Topological stress can cause replication forks to stall as they converge upon one another during termination of vertebrate DNA synthesis. However, replication forks ultimately overcome topological stress and complete DNA synthesis, suggesting that alternative mechanisms can overcome topological stress. We performed a proteomic analysis of converging replication forks that were stalled by topological stress induced by loss or inhibition of topoisomerase IIα (TOP2α). Plasmid DNA was replicated in mock- or TOP2α-depleted Xenopus egg extracts as previously described (Heintzman et al. 2019). In parallel, replication was performed in the presence of the TOP2 inhibitor ICRF-193 (‘TOP2-i’) as an alternate means of preventing TOP2 activity (Heintzman et al. 2019). Chromatinized plasmid DNA was recovered 18 minutes after the onset of DNA synthesis, when most forks have normally merged but are stalled when TOP2 activity is prevented (Heintzman et al. 2019). Chromatin-bound proteins were recovered (Larsen et al. 2019) then analyzed by chromatin mass spectrometry and quantified by label free quantification.
2023-02-21 | PXD031170 | Pride
Project description:During S-phase, active rDNA transcription conflicts with rDNA replication along hundreds of copies of tandemly arrayed rDNA genes. Ttf1 prevents conflicting collisions by binding to specific ‘Sal-boxes’, thus forming replication-fork-barriers. However, understanding of how Ttf1 is displaced from ‘Sal-boxes’ to allow replication-fork progression remains elusive. Here we report that Bms1, a nucleolar GTPase, interacts with Ttf1 to disassociate the Ttf1-DNA complex. GTPase-activity compromised zebrafish Bms1 mutants display ‘Sal-boxes’ accumulation of Ttf1 and resultant replication-fork stall. However, genomic DNA undergo over-replication that in turn activates DNA-damage response and arrests cell cycle at the S-phase, causing a small liver in bms1 mutants. We propose that Ttf1 and Bms1 together impose a nucleolar checkpoint on cell cycle progression through balancing S-phase rDNA transcription and replication.
2022-02-02 | GSE176455 | GEO
Project description:Structural Maintenance of Chromosomes (SMC) complexes - cohesin, condensin and SMC5/6 - are important for many aspects of the chromosomal organization. These complexes are composed of Smc and non-Smc element (Nse) subunits. The Nse1 subunit of SMC5/6 contains a variant RING domain, characteristic of ubiquitin ligases. Human NSE1 has been shown to possess ubiquitin ligase activity in vitro; however, other studies were unable to show such activity. Here, we confirm Nse1 ubiquitin-ligase activity in vitro using purified Schizosaccharomyces pombe proteins. We demonstrate that the Nse1 ligase activity is stimulated by Nse3 and Nse4, it specifically utilizes Ubc13/Mms2 E2 enzyme and Nse1 interacts directly with ubiquitin. We identify Nse1 mutation (R188E) that specifically disrupts its E3 activity, and show that the Nse1-dependent ubiquitination is particularly important under replication stress. Moreover, we identify Nse4 (lysine K181) as the first known SMC5/6-associated Nse1 substrate. Interestingly, abolition of Nse4 modification at K181 leads to suppression of DNA-damage sensitivity of other SMC5/6 mutants. Altogether, this study brings new evidence for Nse1 ubiquitin ligase activity, significantly advancing our under-standing of this enigmatic SMC5/6 function.
2022-01-24 | PXD029573 | Pride
Project description:The extreme length of chromosomal DNA requires organizing mechanisms to both promote functional genetic interactions and ensure faithful chromosome segregation when cells divide. Microscopy and genome wide contact frequency (Hi-C) analyses indicate that intra-chromosomal looping of DNA is a primary pathway of chromosomal organization during all stages of the cell cycle (Dekker, J. & Mirny, L. . Cell 164, 1110–1121 (2016). Although the enzymatic pathways required for DNA loop formation are yet to be fully characterized, the activity of the SMC family of proteins has been consistently associated with this process in interphase and mitosis. Here we use Hi-C to study the reorganization of budding yeast chromosome conformation in early mitosis and the role of SMCs in this process. Using polymer simulations, we find that the differences between interphase and mitotic Hi-C maps can be explained by the formation of intra-chromosomal (cis-) loops in mitotic chromosomes. We demonstrate that mitotic SMC cohesin activity is required for formation of cis-loops, independently of sister-chromatid cohesion. In contrast, SMC condensin is not required for loop formation in these early mitotic cells. Rather condensin activity promotes distinct higher order structures in the chromosomes at centromeres and in the rDNA proximal regions. Thus we demonstrate that cohesin-dependent cis-loops provide the primary higher order organization of budding yeast mitotic chromosomes, independently of condensin and sister chromatid cohesion.
2017-03-22 | GSE87311 | GEO
Project description:During chromosome duplication the parental DNA molecule becomes over-wound, or positively supercoiled, in the region ahead of the advancing replication fork. To allow fork progression this superhelical tension has to be removed by topoisomerases, which operate by introducing transient DNA breaks. Positive supercoiling can also be diminished if the advancing fork rotates along the DNA helix, but then sister chromatid intertwinings form in its wake. Despite these insights it remains largely unknown how replicationinduced superhelical stress is dealt with on linear, eukaryotic chromosomes. Here we show that this stress increases with the length of budding yeast chromosomes. This opens for the possibility that superhelical tension is handled on a chromosome scale and not only within topologically closed chromosomal domains as the current view predicts. We found that inhibition of type I topoisomerases leads to a late replication delay of longer, but not shorter chromosomes. This phenotype is also displayed by cells expressing mutated versions of the cohesin- and condensin–related Smc5/6 complex. The chromosomal association of the Smc5/6 complex is shown to increase in response to chromosome lengthening, chromosome circularization, or inactivation of Topoisomerase 2, all having the potential to increase the number of sister chromatid intertwinings 3. Furthermore, non-functional Smc6 reduces the accumulation of intertwined sister plasmids after one round of replication in the absence of Topoisomerase 2 function. Our results demonstrate that the length of a chromosome influences the need of superhelical tension release in Saccharomyces cerevisiae, and allow us to propose a model where the Smc5/6 complex facilitates fork rotation by sequestering nascent chromatid intertwinings which form behind the replication machinery. Smc6、Nse4, and Scc2 profiles with or without topological tension was analyzed (in top2 mutant, cells with circular chromosome, and fragmented chromosome) . 17 ChIP samples and corresponding WCE fractions have been analyzed.
2011-02-28 | E-GEOD-26263 | biostudies-arrayexpress
Project description:Genome compartmentalization mediated by the cohesin complex plays an essential role in the maintenance of genome integrity and transcriptional regulation. Recurrent somatic mutations in multiple members of the cohesin complex are frequent genetic drivers in several types of cancer, including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), but the cellular consequences of cohesin mutations have not been determined and no therapies have been identified with selective efficacy in cohesin-mutant cancers. Using quantitative proteomics and genome-wide genetic screens in genetically engineered models of STAG2-mutant AML, we identify changes in cohesin complex composition and dependency on STAG1, DNA damage repair, master transcription factors, and RNA splicing machinery. Consistent with these findings, loss of STAG2 leads to DNA replication fork stalling and is associated with increased levels of dsDNA breaks and activation of DNA damage checkpoints, as well as aberrant splicing. Genetic or pharmacologic perturbation of DNA damage repair or splicing creates a synthetic vulnerability for cohesin-mutant cells in vitro and in vivo. Finally, STAG2 loss leads to a global reduction in cohesin binding to chromatin and expansion of super-enhancers, and mutant cohesin complexes spatially co-localize with super-enhancer enriched factors, DNA damage and splicing machinery. Our findings inform the biology of cohesins in cancer cells, and highlight novel therapeutic possibilities for cohesin-mutant malignancies.
| MSV000082970 | MassIVE
Project description:The dramatic change in morphology of chromosomal DNAs between interphase and mitosis is one of the defining features of the eukaryotic cell cycle. Two types of enzymes, namely cohesin and condensin confer the topology of chromosomal DNA by extruding DNA loops. While condensin normally configures chromosomes exclusively during mitosis, cohesin does so during interphase. The processivity of cohesin’s loop extrusion during interphase is limited by a regulatory factor called WAPL, which induces cohesin to dissociate from chromosomes via a mechanism that requires dissociation of its kleisin from the neck of SMC3. We show here that a related mechanism may be responsible for blocking condensin II from acting during interphase. Cells derived from patients affected by microcephaly caused by mutations in the MCPH1 gene undergo premature chromosome condensation but it has never been established for certain whether MCPH1 regulates condensin II directly. We show that deletion of Mcph1 in mouse embryonic stem cells unleashes an activity of condensin II that triggers formation of compact chromosomes in G1 and G2 phases, which is accompanied by enhanced mixing of A and B chromatin compartments, and that this occurs even in the absence of CDK1 activity. Crucially, inhibition of condensin II by MCPH1 depends on the binding of a short linear motif within MCPH1 to condensin II’s NCAPG2 subunit. We show that the activities of both Cohesin and Condensin II may be restricted during interphase by similar types of mechanisms as MCPH1’s ability to block condensin II’s association with chromatin is abrogated by the fusion of SMC2 with NCAPH2. Remarkably, in the absence of both WAPL and MCPH1, cohesin and condensin II transform chromosomal DNAs of G2 cells into chromosomes with a solenoidal axis showing that both cohesin and condensin must be tightly regulated to adjust the structure of chromatids for their successful segregation.
2021-11-19 | GSE188988 | GEO