Condensin positioning at telomeres by shelterin proteins drives sister-telomere disjunction in anaphase
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA803474 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR17886224_1.fastq.gz | Fastqsanger.gz | |||
| SRR17886224_2.fastq.gz | Fastqsanger.gz | |||
| SRR17886225_1.fastq.gz | Fastqsanger.gz | |||
| SRR17886225_2.fastq.gz | Fastqsanger.gz | |||
| SRR17886226_1.fastq.gz | Fastqsanger.gz |
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Project description:The localization of condensin along chromosomes is crucial for their accurate segregation in anaphase. Condensin is enriched at telomeres but how and for what purpose had remained elusive. Here we show that fission yeast condensin accumulates at telomere repeats through the balancing acts of Taz1, a core component of the shelterin complex that ensures telomeric functions, and Mit1, a nucleosome-remodeler associated with shelterin. We further show that condensin takes part in sister-telomere separation in anaphase, and that this event can be uncoupled from the prior separation of chromosomes arms, implying a telomere-specific separation mechanism. Consistent with a cis-acting process, increasing or decreasing condensin occupancy specifically at telomeres modifies accordingly the efficiency of their separation in anaphase. Genetic evidence suggests that condensin promotes sister-telomere separation by counteracting cohesin. Thus, our results reveal a shelterin-based mechanism that enriches condensin at telomeres to drive in cis their separation during mitosis.
2023-10-02 | GSE196149 | GEO
Project description:Sister chromatid cohesion relies on cohesins, a group of proteins that forms a ring-shaped complex embracing sister chromatids. Cohesion is established during S phase and is removed when cohesin Scc1 is cleaved by the protease separase at anaphase onset. During this process, the cohesin subunit Smc3 undergoes a cycle of acetylation: Smc3 acetylation by Eco1 in S phase stabilizes cohesin association with chromosomes, and its deacetylation by Hos1 in anaphase allows re-use of Smc3 in the next cell cycle. Here we find that Smc3 deacetylation by Hos1 has a more immediate effect in early anaphase of budding yeast. Without Hos1, sister chromatid separation and segregation are significantly delayed. Smc3 deacetylation facilitates removal of cohesins from chromosomes, without changing the Scc1 cleavage efficiency, thus promoting dissolution of cohesion. This action is probably due to disengagement of Smc1–3 heads, prompted by de-repression of their ATPase activity. We suggest Scc1 cleavage per se is insufficient for efficient dissolution of cohesion in early anaphase, but subsequent Smc3 deacetylation, which is triggered by Scc1 cleavage, is also required.
2017-11-02 | GSE96841 | GEO
Project description:The accurate segregation of chromosomes during mitosis relies on the attachment of sister chromatids to microtubules from opposite poles, called biorientation. Sister chromatid cohesion resists microtubule forces, generating tension which provides the signal that biorientation has occurred. How tension silences the surveillance pathways that prevent cell cycle progression and correct erroneous kinetochore-microtubule remains unclear. Here we identify SUMOylation as a mechanism that promotes anaphase onset upon biorientation. SUMO ligases modify the tension-sensing pericentromere-localized chromatin protein, shugoshin, to stabilize bioriented sister kinetochore-microtubule attachments and allow entry into anaphase. SUMOylation of shugoshin prevents binding to protein phosphatase 2A (PP2A), while enhancing chromosome passenger complex (CPC) interaction and removal from centromeres. Dissociation of the shugoshin-PP2A interaction is important for stabilizing sister kinetochore biorientation. Therefore, SUMOylation modulates protein interactions within pericentromeres to allow a signalling switch in response to biorientation.
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Project description:Critically short telomeres activate cellular senescence or apoptosis, as mediated by the tumor suppressor p53, but in the absence of this checkpoint response, telomere dysfunction engenders chromosomal aberrations and cancer. Here, analysis of p53-regulated genes activated in the setting of telomere dysfunction identified Zfp365 (ZNF365 in humans) as a direct p53 target that promotes genome stability. Germline polymorphisms in the ZNF365 locus are associated with increased cancer risk, including those associated with telomere dysfunction. On the mechanistic level, ZNF365 suppresses expression of a subset of common fragile sites (CFS) including telomeres. In the absence of ZNF365, defective telomeres engage in aberrant recombination of telomere ends, leading to increased telomere sister chromatid exchange (T-SCE) and formation of anaphase DNA bridges, including ultra-fine DNA bridges (UFB), and ultimately increased cytokinesis failure and aneuploidy. Thus, the p53-ZNF365 axis contributes to genomic stability in the setting of telomere dysfunction. We expressed an inducible p53 allele encoding a p53-estrogen receptor fusion protein (p53ER) that becomes functional upon addition of 4-hydroxytamoxifen (4-OHT) in TKO cells. We chose a time point of 4 hours post-4-OHT induction to catalog potential direct targets.
2013-08-01 | E-GEOD-44599 | biostudies-arrayexpress
Project description:Critically short telomeres activate cellular senescence or apoptosis, as mediated by the tumor suppressor p53, but in the absence of this checkpoint response, telomere dysfunction engenders chromosomal aberrations and cancer. Here, analysis of p53-regulated genes activated in the setting of telomere dysfunction identified Zfp365 (ZNF365 in humans) as a direct p53 target that promotes genome stability. Germline polymorphisms in the ZNF365 locus are associated with increased cancer risk, including those associated with telomere dysfunction. On the mechanistic level, ZNF365 suppresses expression of a subset of common fragile sites (CFS) including telomeres. In the absence of ZNF365, defective telomeres engage in aberrant recombination of telomere ends, leading to increased telomere sister chromatid exchange (T-SCE) and formation of anaphase DNA bridges, including ultra-fine DNA bridges (UFB), and ultimately increased cytokinesis failure and aneuploidy. Thus, the p53-ZNF365 axis contributes to genomic stability in the setting of telomere dysfunction.
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Project description:Telomeres are nucleoprotein structures at the ends of linear chromosomes. In humans, they consist of TTAGGG repeats, which are bound by dedicated proteins such as the shelterin complex. This complex blocks unwanted DNA damage repair at telomeres, e.g. by suppressing non-homologous end joining (NHEJ) through its subunit TRF2. We here describe ZNF524, a zinc finger protein that directly binds telomeric repeats with nanomolar affinity and reveal the base-specific sequence recognition by co-crystallization with telomeric DNA. ZNF524 localizes to telomeres in vivo, as shown among other approaches by ChIP-seq analysis, and specifically maintains the presence of the TRF2/RAP1 subcomplex at telomeres without affecting the other shelterin members. Loss of ZNF524 concomitantly results in an increase in DNA damage signaling and recombination events. Overall, ZNF524 is a direct telomere-binding protein involved in the maintenance of telomere integrity.
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Project description:Chromosome segregation requires both the separation of sister chromatids and the sustained condensation of chromatids during anaphase. In yeast cells, cohesin is not only required for sister chromatid cohesion but also plays a major role in determining the structure of individual chromatids in metaphase. Separase cleavage is thought to remove all cohesin complexes from chromosomes to initiate anaphase. It is thus not clear how the length and organisation of segregating chromatids are maintained during anaphase in the absence of cohesin. Here we show that degradation of cohesin at the anaphase onset causes aberrant chromatid segregation. Hi-C analysis on segregating chromatids demonstrates that cohesin depletion causes loss of intrachromatid organisation. Surprisingly, TEV-mediated cleavage of cohesin does not dramatically disrupt chromatid organisation in anaphase, explaining why bulk segregation is achieved. In addition, we identified a small pool of cohesin complexes bound to telophase chromosomes in wildtype cells and show that they play a role in the organisation of centromeric regions. Our data demonstrate that in yeast cells, cohesin function is not over in metaphase, but extends to the anaphase period when chromatids are segregating.
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Project description:The dynamic nature of genome organization impacts critical nuclear functions including the regulation of gene expression, replication and DNA damage repair. Despite significant progress, the mechanisms responsible for reorganization of the genome in response to cellular stress, such as aberrant DNA replication, are poorly understood. Here we show that fission yeast cells carrying a mutation in the DNA-binding protein Sap1 show defects in DNA replication progression and genome stability, and display extensive changes in genome organization. Chromosomal regions such as subtelomeres that show defects in replication progression associate with the nuclear envelope in sap1 mutant cells. Moreover, high-resolution Hi-C analysis revealed prominent new interactions between telomeres and chromosomal arm regions containing replication origins proximal to binding sites for Taz1, a component of the Shelterin telomere protection complex. Strikingly, we find that Shelterin components promote interactions between Taz1-associated chromosomal arm regions and telomeres. These analyses reveal an unexpected role for Shelterin in genome reorganization in cells experiencing replication stress, which has important implications for understanding mechanisms governing replication and genome stability.
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Project description:The dynamic nature of genome organization impacts critical nuclear functions including the regulation of gene expression, replication and DNA damage repair. Despite significant progress, the mechanisms responsible for reorganization of the genome in response to cellular stress, such as aberrant DNA replication, are poorly understood. Here we show that fission yeast cells carrying a mutation in the DNA-binding protein Sap1 show defects in DNA replication progression and genome stability, and display extensive changes in genome organization. Chromosomal regions such as subtelomeres that show defects in replication progression associate with the nuclear envelope in sap1 mutant cells. Moreover, high-resolution Hi-C analysis revealed prominent new interactions between telomeres and chromosomal arm regions containing replication origins proximal to binding sites for Taz1, a component of the Shelterin telomere protection complex. Strikingly, we find that Shelterin components promote interactions between Taz1-associated chromosomal arm regions and telomeres. These analyses reveal an unexpected role for Shelterin in genome reorganization in cells experiencing replication stress, which has important implications for understanding mechanisms governing replication and genome stability.
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Project description:The dynamic nature of genome organization impacts critical nuclear functions including the regulation of gene expression, replication and DNA damage repair. Despite significant progress, the mechanisms responsible for reorganization of the genome in response to cellular stress, such as aberrant DNA replication, are poorly understood. Here we show that fission yeast cells carrying a mutation in the DNA-binding protein Sap1 show defects in DNA replication progression and genome stability, and display extensive changes in genome organization. Chromosomal regions such as subtelomeres that show defects in replication progression associate with the nuclear envelope in sap1 mutant cells. Moreover, high-resolution Hi-C analysis revealed prominent new interactions between telomeres and chromosomal arm regions containing replication origins proximal to binding sites for Taz1, a component of the Shelterin telomere protection complex. Strikingly, we find that Shelterin components promote interactions between Taz1-associated chromosomal arm regions and telomeres. These analyses reveal an unexpected role for Shelterin in genome reorganization in cells experiencing replication stress, which has important implications for understanding mechanisms governing replication and genome stability.
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