Histone chaperone NAP1 is required for sister chromatid resolution
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ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE30938 | GEO | 2012/07/26
SECONDARY ACCESSION(S): PRJNA146291
REPOSITORIES: GEO
Similar Datasets
Project description:The fidelity of chromosome duplication through cell divisions requires timely binding and release of the cohesin. Cohesin is a ring-shaped protein complex linking newly replicated sister chromatids to ensure their appropriate transmission through mitosis. Upon commencement of mitosis cohesin is removed from DNA in two steps: first, from chromosome arms resulting in sister chromatid resolution, and, second, from centromers leading to sister chromatid segregation. As DNA of eukaryotic chromosomes is assembled into chromatin, regulation of sister chromatid cohesion-segregation may involve chromatin modifying machinery, but this link is not well understood. Here we report that H2A-H2B histone chaperone NAP1, a factor, which is primarily implicated in chromatin assembly, is required for cohesin release from mitotic chromosome arms. NAP1 and cohesin protein complex interact directly and share multiple binding sites on chromatin. Depletion of the NAP1 hinders cohesin removal during mitosis resulting in accumulation of unresolved sister chromatids. Thus, in addition to its well established functions in chromatin dynamics, histone chaperone NAP1 coordinates cell cycle dependent cohesin release. These results reveal a novel molecular pathway for sister chromatid resolution and emphasizes a role for histone chaperones in control of eukaryotic genome replication and transmission. Genome-wide NAP1 and Cohesin ChIP-chip profiling in Drosophila S2 cells. The supplementary bed file S2_cohesin_sites.bed contains cohesin binding sites obtained by intersecting the sets of significant ChIP-chip peaks for SA (a cohesin subunit; stromalin) and SMC1.
2012-07-25 | E-GEOD-30938 | biostudies-arrayexpress
Project description:FACT mediates cohesin function on chromatin Cohesin is a key regulator of genome architecture with roles in sister chromatid cohesion and the organisation of higher-order structures during interphase and mitosis. The recruitment and mobility of cohesin complexes on DNA are restricted by nucleosomes. Here we show that cohesin role in chromosome organization requires the histone chaperone FACT. Depletion of FACT in metaphase cells affects cohesin stability on chromatin reducing its accumulation at pericentric regions and binding on chromosome arms. Using Hi-C, we show that cohesin-dependent TAD (Topological Associated Domains)-like structures in G1 and metaphase chromosomes are disrupted in the absence of FACT. Surprisingly, sister chromatid cohesion is intact in FACT-depleted cells, although chromosome segregation failure is observed. Our results uncover a role for FACT in genome organisation by facilitating cohesin dependent compartmentalization of chromosomes into loop domains.
2019-10-03 | PXD014896 | Pride
Project description:Cohesin is a key regulator of genome architecture with roles in sister chromatid cohesion and the organisation of higher-order structures during interphase and mitosis. The recruitment and mobility of cohesin complexes on DNA are restricted by nucleosomes. Here we show that cohesin role in chromosome organization requires the histone chaperone FACT. Depletion of FACT in metaphase cells affects cohesin stability on chromatin reducing its accumulation at pericentric regions and binding on chromosome arms. Using Hi-C, we show that cohesin-dependent TAD (Topological Associated Domains)-like structures in G1 and metaphase chromosomes are disrupted in the absence of FACT. Surprisingly, sister chromatid cohesion is intact in FACT-depleted cells, although chromosome segregation failure is observed. Our results uncover a role for FACT in genome organisation by facilitating cohesin dependent compartmentalization of chromosomes into loop domains.
2019-10-11 | GSE118534 | GEO
Project description:Segregation of homologous maternal and paternal centromeres to opposite poles during meiosis I depends on post-replicative crossing over between homologous non-sister chromatids, which creates chiasmata and therefore bivalent chromosomes. Destruction of sister chromatid cohesion along chromosome arms due to proteolytic cleavage of cohesin's Rec8 subunit by separase resolves chiasmata and thereby triggers the first meiotic division. This produces univalent chromosomes, the chromatids of which are held together by centromeric cohesin that has been protected from separase by shugoshin (Sgo1/MEI-S332) proteins. Here we show in both fission and budding yeast that Sgo1 recruits to centromeres a specific form of protein phosphatase 2A (PP2A). Its inactivation causes loss of centromeric cohesin at anaphase I and random segregation of sister centromeres at the second meiotic division. Artificial recruitment of PP2A to chromosome arms prevents Rec8 phosphorylation and hinders resolution of chiasmata. Our data are consistent with the notion that efficient cleavage of Rec8 requires phosphorylation of cohesin and that this is blocked by PP2A at meiosis I centromeres. Keywords: ChIP-chip, Mitosis, Meiosis, Cell cycle, Saccharomyces cerevisiae, Chromosome VI tiling array, Sgo1, Pp2A, Cse4, Ndc10, Rts1, Rec8
2006-05-10 | GSE4791 | GEO
Project description:The three-dimensional organization of the genome supports regulated gene expression, recombination, DNA repair, and chromosome segregation during mitosis. Chromosome conformation capture (Hi-C) has revealed a complex genomic landscape of internal chromosome structures in vertebrate cells yet how sister chromatids topologically interact in replicated chromosomes has remained elusive due to their identical sequences. Here, we present sister-chromatid-sensitive Hi-C (scsHi-C) based on nascent DNA labeling with 4-thio-thymidine. Genome-wide conformation maps of human chromosomes revealed that sister chromatid pairs interact most frequently at the boundaries of topologically associating domains (TADs). Continuous loading of a dynamic cohesin pool separates sister-chromatid pairs inside TADs and is required to focus sister chromatid contacts at TAD boundaries. We identified a subset of TADs that are overall highly paired, characterized by facultative heterochromatin, as well as insulated topological domains that form separately within individual sister chromatids. The rich pattern of sister chromatid topologies and our scsHi-C technology will make it possible to dissect how physical interactions between identical DNA molecules contribute to DNA repair, gene expression, chromosome segregation, and potentially other biological processes.
2020-06-12 | GSE152373 | GEO
Project description:Cohesin stably holds together the sister chromatids from S phase until mitosis. To do so, cohesin must be protected against its cellular antagonist Wapl. Eco1 acetylates cohesinâs Smc3 subunit, which locks together the sister DNAs. We used yeast genetics to dissect how Wapl drives cohesin from chromatin and identified mutants of cohesin that are impaired in ATPase activity but remarkably confer robust cohesion that bypasses the need for the cohesin protectors Eco1 in yeast and Sororin in human cells. We uncover an unexpected functional asymmetry within the heart of cohesinâs highly conserved ABC-like ATPase machinery and show that an activity associated with one of cohesinâs two ATPase sites drives DNA release from cohesin rings. This key mechanism is conserved from yeast to humans. We propose that Eco1 locks cohesin rings around the sister chromatids by counteracting an asymmetric cohesin-associated ATPase activity. Effect of mutations in Smc1 and Smc3 on cohesin loading onto chromosomes
2016-02-18 | E-GEOD-76891 | biostudies-arrayexpress
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.
2022-10-01 | GSE183481 | GEO
Project description:To ensure equal separation of DNA, sister chromatids are held together from S phase to metaphase–anaphase transition by a multiprotein complex called cohesin. This makes it possible to establish chromosome biorientation, counteracts the pulling force of mitotic spindle microtubules, preventing premature sister chromatid separation, and ensures precise segregation of sister DNAs into daughter cells In order to better understand how the sister chromatid cohesion process is regulated we looked for new cohesin interacors. We constructed a yeast strain endogenously expressing TAP-tagged Scc1 (Scc1-TAP). Next, we performed a single-step TAP purification using an untagged strain (mock sample) or a strain expressing Scc1-TAP, followed by identification of co-purifying proteins by MS.
2023-10-24 | PXD037034 | Pride
Project description:The organisation of mammalian genomes into loops and topologically associated domains (TADs) regulates gene expression. The formation and maintenance of loops and TADs depends on the protein complex cohesin, which also holds replicated sister chromatids together from S phase until mitosis. To understand how cohesin functions, it is essential to know how many cohesin complexes and regulators exist in a typical cell and how they are distributed genome-wide. Here, we have used quantitative mass spectrometry, fluorescence-correlation spectroscopy and fluorescence recovery after photobleaching to measure the absolute number and dynamics of core subunits and regulators of the cohesin complex in human cells. We find that 60000 – 134000 cohesin complexes are bound to chromatin per G1 HeLa cell, suggesting that cohesin most likely does not occupy all its binding sites concurrently. We incorporate our data into mathematical models and discuss implications for how cohesin might contribute to genome organisation and sister chromatid cohesion.
2019-11-13 | PXD012712 | Pride
Project description:Cohesin holds sister chromatids together to enable their accurate segregation in mitosis. How, and where, cohesin binds to chromosomes are still poorly understood, and recent genome-wide surveys have revealed an apparent disparity between its chromosomal association patterns in different organisms. Here, we present the high-resolution analysis of cohesin localisation along fission yeast chromosomes. This reveals that several determinants, thought specific for distinct organisms, come together to shape the overall distribution. Cohesin is detected at chromosomal loading sites, characterised by the cohesin loader Mis4/Ssl3, in regions of strong transcriptional activity. Cohesin also responds to transcription by downstream translocation and accumulation at convergent transcriptional terminators surrounding the loading sites. As cells enter mitosis, a fraction of cohesin leaves chromosomes in a cleavage-independent reaction, while a substantial pool of cohesin dissociates when it is cleaved at anaphase onset. As a unique feature, centromeric cohesin spreads out onto chromosome arms during mitosis as the heterochromatin protein Swi6 dissociates from centromeres. Together, this allows us to suggest conserved mechanisms for chromosomal cohesin binding in eukaryotes. After DNA replication in S phase, sister chromatids are held together by the cohesin complex. This allows DNA break repair by homologous recombination in G2 and bipolar attachment of the spindle to sister kinetochores in mitosis. At anaphase onset, sister chromatid cohesion is resolved to trigger chromosome segregation. Cohesin is an essential, conserved protein complex consisting of at least five subunits, Psm1, Psm3, Rad21, Psc3 and Pds5 in fission yeast (orthologs of budding yeast Smc1, Smc3, Scc1, Scc3 and Pds5, respectively). Chromatin immunoprecipitations against three different subunits of the cohesin complex, fused to two different epitope tags (Rad21-Pk9 -> GSM333001, Rad21-HA3 -> GSM333004, Psc3-Pk9 -> GSM333005 and Pds5-Pk9 -> GSM333006), yielded a reproducible binding pattern between approximately half of all available convergently transcribed gene pairs (in the following called convergent sites). The pattern was almost indistinguishable between exponentially growing cell populations (GSM333004, GSM333005, GSM333006) and cells arrested in G2 using the thermosensitive cdc25-22 mutation (GSM333001). To understand why some, but not all, convergent sites are bound by cohesin, we analysed whether fission yeast cohesin responds to Pol II transcription by downstream translocation, like in budding yeast. As an example, we analysed cohesin at the convergent site between the rad21 and pof3 genes. rad21 expression is high during G1 and S phase, but low in G2. In cells arrested in G2 using the cdc25-22 allele, only a small cohesin peak was detectable that largely overlapped with the rad21 ORF (GSM333001). In contrast, in cells arrested in G1 using the cdc10-129 allele, the rad21 ORF was clear of cohesin and instead a large cohesin peak accumulated downstream of rad21 (GSM333007). It has been suggested that transcriptional readthrough at convergent sites promotes double stranded RNA-dependent heterochromatin formation, which in turn underlies cohesin recruitment. We therefore tested whether the heterochromatin protein Swi6, thought to recruit cohesin, played a role in generating the observed cohesin pattern. We grew wild type and swi6Î cells in synthetic medium lacking thiamine, conditions under which the nmt2 gene is transcribed at the nmt2/avn2 convergent site that has been studied as an example. In contrast to the prediction, the cohesin pattern along chromosome arms, including the nmt2/avn2 convergent site, remained unchanged in swi6Î cells (GSM333008). We detected only small amounts of cohesin at the nmt2/avn2 convergent site, a class 1 convergent site following the above classification. At the centromeric repeats, cohesin levels were reduced in the absence of Swi6. These findings are consistent with previous reports implicating Swi6 in cohesin recruitment to centromeric heterochromatin, but not chromosome arms. To compare cohesinâs pattern to its likely sites of chromosomal loading, we analysed the localisation of the cohesin loader subunits Mis4 and Ssl3. The two subunits showed a largely overlapping pattern of binding. Chromatin immunoprecipitation was performed against epitope-tagged Mis4-Pk9 (GSM333163) and Ssl3-Pk9 (GSM334196) from exponentially proliferating cells. As a control, cells without epitope-tagged protein were grown under identical conditions and processed in parallel for chromatin immunoprecipitation with an α-Pk antibody (GSM333230). The untagged control sample yielded trace amounts of immunoprecipitated DNA, which after amplification led to several strong peaks often in intergenic low complexity regions. Several of these peaks overlapped with Mis4/Ssl3 peaks, which were excluded from the analysis. Peaks in low complexity regions were not observed in chromatin immunoprecipitates of cohesin subunits (compare GSM333001). In the search for an underlying determinant of Mis4/Ssl3 binding sites, we noticed a striking correlation with tRNA and ribosomal protein genes. Mis4/Ssl3 binding sites at tRNA genes overlapped with the binding profile of the Pol III transcription factor TFIIIC subunit Sfc6 (GSM334198), while at ribosomal protein genes it colocalised with the forkhead domain containing protein Fhl1 (GSM334307). Fhl1 is a possible fission yeast ortholog of the transcription factor Fhl1 that controls ribosomal protein gene expression in budding yeast. We found Sfc6 also associated with ribosomal protein genes, and Fhl1 with tRNA genes, though with weaker signal intensities. We do not currently know whether Sfc6 contributes to transcriptional control of ribosomal protein genes, and Fhl1 to that of tRNA genes, or whether the weaker levels of association may reflect indirect association, mediated by interactions between ribosomal protein and tRNA gene loci. Similar to budding yeast, Mis4/Ssl3 binding sites are also binding sites for the chromosomal condensin complex (GSM334197), which may mediate such interactions. Having identified the binding sites of the Mis4/Ssl3 cohesin loader, we wanted to analyse its relationship with the cohesin distribution along chromosome arms. If Mis4/Ssl3 cohesin loading sites promote cohesin binding in their surrounding, deletion of a loading site should alter this pattern. To test this, we deleted a 489 bp sequence, containing two adjacent tRNA genes that form a Mis4/Ssl3 and cohesin binding site, on the left arm of chromosome 2. In response to the deletion, Mis4/Ssl3 binding to this locus disappeared (GSM334308). Cohesin was also no longer detected at this site (GSM334309), consistent with the notion that cohesin loading had been disrupted. However, the cohesin distribution at convergent sites surrounding the former loading site remained unchanged. This suggests that establishment of the cohesin pattern did not depend on a specific Mis4/Ssl3 binding site. Despite the tRNA deletion, residual Mis4/Ssl3 remained detectable in the vicinity of this site (GSM334308). Cohesin loading by Mis4/Ssl3 might therefore be less restricted to its peaks of binding than the pattern suggests. Alternatively, other determinants, e.g. gene orientation and their transcriptional activity, might define cohesin distribution at this locus. We next addressed how cohesin on fission yeast chromosomes responds to loss of sister chromatid cohesion during mitosis and whether cohesin removal in mitosis affected certain regions of the chromosome more than others. In order to follow cohesin through mitosis, we arrested a cell population in G2 using the thermosensitive cdc25-22 mutation and released the culture into synchronous mitotic progression at permissive temperature.The cohesin pattern remained largely unchanged throughout G2, metaphase and anaphase, although the height of peaks along chromosome arms decreased. This suggests that cohesin is not removed from a subset of its binding sites during mitosis, but that its association among most binding sites was uniformly reduced. A noticeable change to the cohesin pattern during mitosis became apparent around centromeres. Over a region of approximately 50 kb surrounding the centromeres, cohesin appeared to spread along chromosome arms, showing little preference for convergent sites. The spreading started as cells entered metaphase (GSM334316) and became most pronounced during anaphase (GSM334317). We also observed a similar, although less pronounced, spreading around centromeres in cells arrested in G1 using the cdc10-129 thermosensitive mutation (GSM333007). This suggests that spreading of cohesin around centromeres is cell cycle stage specific. Cohesin is enriched at the centromeric repeat regions (GSM333001), tethered by the heterochromatin protein Swi6, possibly after being loaded at core centromere sequences, where we observed strong Mis4/Ssl3 accumulation (GSM333163 & GSM334196). In mitosis, Swi6 levels are reduced after aurora B kinase-dependent phosphorylation of histone H3, and it reaccumulates as cells enter the subsequent S phase. To test whether loss of Swi6-dependent
2010-05-14 | E-GEOD-13517 | biostudies-arrayexpress