Centromeric chromatin in mitosis reorganizes into a functional structure stabilized by cohesin [NG-Capture-C]
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ABSTRACT:
ORGANISM(S): Gallus gallus
PROVIDER: GSE254659 | GEO | 2024/04/01
REPOSITORIES: GEO
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Project description:Three-dimensional organization of mitotic chromosomes is established by cohesin and condensin complexes. In the centromere, cohesin maintains sister chromatid pairing until anaphase onset, while condensin provides elastic resistance to spindle forces. However, how condensin and cohesin structure vertebrate centromeres remains unclear. By super-resolution imaging, Capture-C analysis and polymer modeling we show that vertebrate centromeres are partitioned into two condensin-dependent subdomains during mitosis. This bipartite sub-structure is found in human, mouse and chicken centromeres, and is therefore a fundamental feature of vertebrate centromere. Super-resolution imaging and electron tomography reveal that bipartite centromeres assemble bipartite kinetochores with each subdomain capable of binding a distinct microtubule bundle. Cohesin helps to link the centromere subdomains, limiting their separation in response to spindle forces and preventing merotelic attachments. The two-domain structure described here may have implications for avoiding chromosomal instability as uncoupling of centromere subdomains is a common feature of lagging chromosomes in cancer cells.
2024-04-01 | GSE254181 | GEO
Project description:Three-dimensional organization of mitotic chromosomes is established by cohesin and condensin complexes. In the centromere, cohesin maintains sister chromatid pairing until anaphase onset, while condensin provides elastic resistance to spindle forces. However, how condensin and cohesin structure vertebrate centromeres remains unclear. By super-resolution imaging, Capture-C analysis and polymer modeling we show that vertebrate centromeres are partitioned into two condensin-dependent subdomains during mitosis. This bipartite sub-structure is found in human, mouse and chicken centromeres, and is therefore a fundamental feature of vertebrate centromere. Super-resolution imaging and electron tomography reveal that bipartite centromeres assemble bipartite kinetochores with each subdomain capable of binding a distinct microtubule bundle. Cohesin helps to link the centromere subdomains, limiting their separation in response to spindle forces and preventing merotelic attachments. The two-domain structure described here may have implications for avoiding chromosomal instability as uncoupling of centromere subdomains is a common feature of lagging chromosomes in cancer cells.
2024-04-01 | GSE254180 | GEO
Project description:The duplication and segregation of chromosomes involve the dynamic re-organization of their internal structure by conserved architectural proteins, such as structural maintenance of chromosomes complexes (i.e., cohesin and condensin). Although the roles of these factors is actively investigated, a genome-wide view of chromosome dynamic architecture at both small and large-scales during cell division remains elusive. Here we report the first comprehensive 4D analysis of the Saccharomyces cerevisiae genome higher-order organization during the cell cycle, and investigate the roles of SMC in the observed structural transitions. During replication, cohesion establishment promotes long-range intra-chromosomal contacts and correlates with the individualization of chromosomes, which culminates at metaphase. Mitotic chromosomes are then abruptly reorganized in anaphase by mechanical forces exerted by the mitotic spindle. The formation of a condensin-dependent loop, that bridges the centromere cluster with the rDNA loci, suggests that condensin-mediated forces may also directly facilitate segregation. This work provides a comprehensive overview of chromosome dynamics during the cell cycle of a unicellular eukaryote that recapitulates and unveils new features of highly conserved stages of the cell division.
2017-07-20 | GSE90902 | GEO
Project description:The biorientation of sister chromatids on the mitotic spindle, essential for accurate sister chromatid segregation, relies on critical centromere components including cohesin, the centromere-specific H3 variant CENP-A, and centromeric DNA. Centromeric DNA is highly variable between chromosomes yet must accomplish a similar function. Moreover, how the 50 nm cohesin ring, proposed to encircle sister chromatids, accommodates inter-sister centromeric distances of hundreds of nanometers on the metaphase spindle is a conundrum. Insight into the 3D organization of centromere components would help resolve how centromeres function on the mitotic spindle. We used ChIP-seq and super-resolution microscopy to examine the geometry of essential centromeric components on human chromosomes. ChIP-seq of SA1, SA2, and Rad21 in human cells demonstrates that cohesin subunits are depleted in -satellite arrays where CENP-A nucleosomes and kinetochores assemble. Cohesin is instead enriched at pericentromeric DNA. Structured illumination microscopy of sister centromeres is consistent, revealing a non-overlapping pattern of CENP-A and cohesin.
2023-10-11 | GSE240957 | GEO
Project description:The ring-shaped cohesin complex links sister chromatids until their timely segregation during mitosis. Cohesin is enriched at centromeres, where it provides the cohesive counter-force to bi-polar tension produced by the mitotic spindle. As a consequence of spindle tension, centromeric sequences transiently split in pre-anaphase cells, in some organisms up to several micrometeres. This ‘centromere breathing’ presents a paradox, how sister sequences separate where cohesin is most enriched. We now show that in the budding yeast S. cerevisiae, cohesin binding diminishes over centromeric sequences that split during breathing. We see no evidence for cohesin translocation to surrounding sequences, suggesting that cohesin is removed from centromeres during breathing. Two pools of cohesin can be distinguished. Cohesin loaded before DNA replication, that has established sister chromatid cohesion, disappears during breathing. In contrast, cohesin loaded after DNA replication is partly retained. As sister centromeres re-associate after transient separation, cohesin is re-loaded in a manner independent of the canonical cohesin loader Scc2/Scc4. Efficient centromere re-association requires the cohesion establishment factor Eco1, suggesting that re-establishment of sister chromatid cohesion contributes to the dynamic behaviour of centromeres in mitosis. These findings provide new insights into cohesin behaviour at centromeres. Keywords: ChIP-chip
2007-09-30 | GSE8661 | GEO
Project description:The centromere is defined by the presence of a centromere-specific histone H3 variant, CENH3. Establishment and maintenance of the centromeric chromatin (CEN chromatin) is determined by poorly understood epigenetic mechanisms. Interestingly, CEN chromatin in several eukaryotes showed euchromatic characteristics although being embedded within pericentromeric heterochromatin. Specifically, H3K4me2 appeared to be a unique histone modification mark associated with animal centromeres. We developed a genomic tiling array for four fully sequenced rice centromeres. A ChIP-chip approach was used to study the patterns of several euchromatic histone modification marks, including H3K4me2, H3K4me3, H3K36me3, and H3K4K9a, associated with rice centromeres. We demonstrate that the CENH3 subdomains within the four centromeres are depleted with the four histone H3 marks. The vast majority of the four histone marks were associated with the genes located in the H3 subdomains within the centromeric cores. Genes in the centromeres showed similar histone modification patterns as those located outside of the centromeres. Thus, the euchromatic characteristics of rice CEN chromatin are trademarks of the transcribed sequences embedded in the H3 subdomains of the centromeres. We propose that the constitutively expressed genes located in rice centromeres may provide a barrier for loading of CENH3 into the H3 subdomains. The separation of CENH3 into the H3 subdomains is favorable for the three dimensional structure and its associated function of rice centromeres.
2011-11-09 | GSE29597 | GEO
Project description:The centromere is defined by the presence of a centromere-specific histone H3 variant, CENH3. Establishment and maintenance of the centromeric chromatin (CEN chromatin) is determined by poorly understood epigenetic mechanisms. Interestingly, CEN chromatin in several eukaryotes showed euchromatic characteristics although being embedded within pericentromeric heterochromatin. Specifically, H3K4me2 appeared to be a unique histone modification mark associated with animal centromeres. We developed a genomic tiling array for four fully sequenced rice centromeres. A ChIP-chip approach was used to study the patterns of several euchromatic histone modification marks, including H3K4me2, H3K4me3, H3K36me3, and H3K4K9a, associated with rice centromeres. We demonstrate that the CENH3 subdomains within the four centromeres are depleted with the four histone H3 marks. The vast majority of the four histone marks were associated with the genes located in the H3 subdomains within the centromeric cores. Genes in the centromeres showed similar histone modification patterns as those located outside of the centromeres. Thus, the euchromatic characteristics of rice CEN chromatin are trademarks of the transcribed sequences embedded in the H3 subdomains of the centromeres. We propose that the constitutively expressed genes located in rice centromeres may provide a barrier for loading of CENH3 into the H3 subdomains. The separation of CENH3 into the H3 subdomains is favorable for the three dimensional structure and its associated function of rice centromeres. We developed a genomic tiling array that covers four rice centromeres (Cen4, Cen5, Cen7, and Cen8) using the NimbleGen 3x720K array based on the NimbleGen HD2 platform. We used four antibodies (H3K4me3, H3K4me2, H3K36me3, H3K4K9ac) to perform ChIP-chip experiments. ChIP was conducted using leaf tissue from two-week old rice seedlings. We have 3 biological replicates for each antibody and 6 technological replicates of hybridization with position exchange on the array. Thus, each histone modification included 18 hybridization experiments.
2011-11-09 | E-GEOD-29597 | biostudies-arrayexpress
Project description:Centromeres play an essential role in cell division by specifying the site of kinetochore formation on each chromosome so that chromosomes can attach to the mitotic spindle for segregation. Centromeres are defined epigenetically by the histone H3 variant CEntromere Protein A (CENP-A). Dividing cells maintain the centromere by depositing new CENP-A each cell cycle to replenish CENP-A diluted by replication. The CENP-A nucleosome serves as the primary signal to the machinery responsible for its replenishment. Vertebrate centromeres are frequently built on repetitive sequences organized in tandem arrays. Repetitive centromeric DNA has been suggested to play a role in centromere maintenance and in de novo centromere formation, but this has been difficult to dissect because of the difficulty in manipulating centromere in cells. Extracts from Xenopus laevis eggs are able to assemble centromeres and kinetochores in vitro and thus provide a useful system for studying the role of centromeric DNA in centromere formation. However centromeric sequences in X. laevis have not been extensively characterized.. In this study we characterize repeat sequences found at X. laevis centromeres. We utilize a k-mer based approach in order to uncover the previously unknown diversity of X. laevis centromeric sequences. We validate centromere localization of repeat sequences by in situ hybridization and identify the location of the centromeric repetitive array on each chromosome by mapping the distribution of centromere enriched k-mers on the Xenopus genome. Our identification of X. laevis centromere sequences enables previously unapproachable genomic studies of centromeres. The k-mer based approach that we used to investigate centromeric repetitive DNA is suitable for the analysis of other repetitive sequences found across the genome or the study of repeats in other organisms.
2020-06-24 | GSE153058 | GEO
Project description:Condensin molecules are loaded onto the genome to mediate essential changes in chromosome condensation during mitosis, but it is not clear why there are two forms of vertebrate condensin that become differentially distributed on chromosomes. We report here that condensin II, the form of condensin present in the nucleus throughout the cell cycle, functions specifically at active genes. Condensin II is loaded at transcriptionally active promoters in embryonic stem cells (ESCs), migrates through these genes in a transcription-dependent fashion and accumulates in transcription termination regions. Unlike cohesin, which is also loaded at active promoters, condensin II has little influence on transcription. We conclude that condensin II is loaded and distributed across actively transcribed chromatin and thus serves to specifically condense this euchromatic portion of chromosomes during the cell division cycle. ChIP-Seq data for Condensin II and Cohesin in v6.5 ESCs treated or not with the RNA polymerase II elongation inhibitor flavopiridol.
2012-02-09 | E-GEOD-30919 | biostudies-arrayexpress
Project description:The condensin complex is well known to be essential for correct packaging and segregation of chromosomes during mitosis and meiosis in all eukaryotes. To date, the genome wide location and the nature of condensin binding sites has remained elusive in vertebrate systems. A detailed knowledge of condensin binding sites is essential to understand the as-yet enigmatic function of this complex and to define its greater role in chromosome architecture. To address this, we have used next generation sequencing to map condensin I in chicken DT40 cells. Unexpectedly, we found condensin I binds predominately to promoter sequences in mitotic cells. We also found a striking enrichment at both centromeres and telomeres, highlighting the importance of the complex in chromosome segregation. Taken together, the results show condensin I is largely absent from heterochromatic regions. These results reveal for the first time the condensin I binding sites in the vertebrate genome, and demonstrate the importance of the complex in genome segregation and suggest a novel function in gene regulation. Condensin associated DNA from chicken DT40 cells were affinity purified using streptavidin and deep sequenced by Illumina Hiseq2000
2013-10-03 | E-GEOD-45552 | biostudies-arrayexpress