Polycomb Group proteins are retained at specific sites on chromatin in mitosis
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ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE38166 | GEO | 2013/01/04
SECONDARY ACCESSION(S): PRJNA167354
REPOSITORIES: GEO
Similar Datasets
Project description:Epigenetic regulation of gene expression, including by Polycomb Group (PcG) proteins, may depend on heritable chromatin states but how these states can be propagated through mitosis is unclear. Using immunofluorescence and biochemical fractionation, we find PcG proteins associated with mitotic chromosomes in Drosophila S2 cells. Genome-wide sequencing of chromatin immunoprecipitations (ChIP-SEQ) from mitotic cells indicates that Posterior Sex Combs (PSC) and Polyhomeotic (PH) are not present at well-characterized PcG targets including Hox genes in mitosis, but do remain at 11% of their interphase sites. 26% of interphase PSC sites overlap with recently described chromatin domain borders (Sexton et al., 2012), which are genomic regions characterized by low levels of long range contacts. PSC and PH are preferentially retained at these sites in mitosis, including borders flanking both Hox gene clusters. We hypothesize that disruption of long range chromatin contacts in mitosis contributes to PcG protein release from most sites, while persistent binding at sites with minimal long range contacts may nucleate re-establishment of PcG binding and chromosome organization after mitosis. Drosophila S2 cells were colchicine-treated and stained with anti-H3S10p antibody and FACS sorted to give mitotic samples. In parallel asynchronous Drosophila S2 cell cultures were stained for anti-H3 antibody and FACS sorted to give control samples. Chromatin from each of these sorted populations was immunoprecipitated using biotinylated antibodies against PSC. Two replicates of these samples are included. A stable Drosophila S2 cell line expressing biotin-tagged PH was also FACS sorted as above to give mitotic and control samples, and streptavidin-coated beads were used to pulldown biotinlyated PH. Inputs are included for each sample.
2013-01-04 | E-GEOD-38166 | biostudies-arrayexpress
Project description:Chromatin fibres dynamically change their organisation during cell cycle. In interphase nucleus, chromatin fibres are evenly distributed whereas their spatial occupancy are reorganised to form condensed chromosomes in mitosis. This process called chromosome condensation is necessary for an accomplishment of faithful chromosome segregation. One of the Structural Maintenance of Chromosomes complexes, Condensin, is indispensable for chromosome condensation. It remains, however, unknown how Condensin plays its role in shaping mitotic chromosome. Here we show that chromatin fibres change their interacting partners; short-range contacts in interphase nucleus are converted into long-range interactions to shape condensed chromosomes. This conversion of interactions among chromatin fibres results in the formation of larger domains within mitotic chromosomes. Condensin is solely in charge of the conversion and large domain formation in fission yeast mitosis. Our results show how fission yeast Condensin is involved in shaping mitotic chromosomes.
2017-07-13 | GSE94475 | GEO
Project description:Chromatin fibres dynamically change their organisation during cell cycle. In interphase nucleus, chromatin fibres are evenly distributed whereas their spatial occupancy are reorganised to form condensed chromosomes in mitosis. This process called chromosome condensation is necessary for an accomplishment of faithful chromosome segregation. One of the Structural Maintenance of Chromosomes complexes, Condensin, is indispensable for chromosome condensation. It remains, however, unknown how Condensin plays its role in shaping mitotic chromosome. Here we show that chromatin fibres change their interacting partners; short-range contacts in interphase nucleus are converted into long-range interactions to shape condensed chromosomes. This conversion of interactions among chromatin fibres results in the formation of larger domains within mitotic chromosomes. Condensin is solely in charge of the conversion and large domain formation in fission yeast mitosis. Our results show how fission yeast Condensin is involved in shaping mitotic chromosomes.
2017-07-13 | GSE94474 | GEO
Project description:Polycomb Group (PcG) proteins regulate gene expression by modifying chromatin. A key PcG complex, PRC1, has two activities: a ubiquitin ligase activity for histone H2A, and a chromatin compacting/nucleosome bridging activity that can inhibit transcription and chromatin remodeling. In Drosophila, the Posterior Sex Combs (PSC) subunit of PRC1 is central to both activities. The N-terminal homology region (HR) of PSC partners with dRING to form the ubiquitin ligase, while its intrinsically disordered C-terminal region (PSC-CTR) compacts chromatin, and inhibits chromatin remodeling and transcription in vitro. Both the HR and the PSC-CTR are essential in vivo. To understand how these two activities may be coordinated in PRC1, we used cross-linking mass spectrometry (XL-MS) to analyze the conformations of the PSC-CTR in PRC1 and how they change on binding DNA. XL-MS identifies interactions between the PSC-CTR and the core of PRC1, including the PSC HR. New contacts and overall more compacted PSC-CTR conformations are induced by DNA binding. We used chemical acetylation of accessible lysines for MS-based protein footprinting of the PSC-CTR. Protein footprinting reveals an extended, bipartite candidate DNA/chromatin binding surface. Our data suggest a model in which DNA (or chromatin) follows a long path on the flexible PSC-CTR. Intramolecular interactions of the PSC-CTR detected by XL-MS can bring the high affinity DNA/chromatin binding region close to the core of PRC1 without disrupting the interface between the ubiquitin ligase and the nucleosome. Our approach may be applicable to understanding the global organization of other large IDRs that bind nucleic acids.
2020-05-15 | MSV000085418 | MassIVE
Project description:Mitosis entails global alterations to chromosome structure and nuclear architecture, concomitant with transient silencing of transcription. How cells transmit transcriptional states through mitosis remains incompletely understood. While many nuclear factors dissociate from mitotic chromosomes, the observation that certain nuclear factors and chromatin features remain associated with individual loci during mitosis originated the hypothesis that they could provide transcriptional memory through mitosis. To obtain the first genome-wide view of the dynamics of chromatin structure during mitosis, we compared the DNase sensitivity of interphase and mitotic chromatin at two stages of cellular maturation in a rapidly dividingmurine erythroblastmodel. Despite global chromosome condensation visible during mitosis at the microscopic level, the chromatin accessibility landscape is largely unaltered. However, mitotic chromatin accessibility is locally dynamic, with individual loci maintaining none, some, or all of their interphase accessibility. Mitotic reduction in accessibility occurs primarily within narrow, highly hypersensitive sites that frequently coincide with transcription factor binding sites, whereas broader domains of moderate accessibility tend to be more stable. In mitosis, proximal promoters generally maintain their accessibility, whereas distal regulatory elements preferentially lose accessibility. Promoters with the highest degree of accessibility preservation in mitosis tend to also be accessible across many murine tissues in interphase. Transcription factor GATA1 exerts site-specific changes in interphase accessibility that are most pronounced at distal regulatory elements, but does not visibly influence mitotic accessibility. We conclude that features of open chromatin are remarkably stable through mitosis and are modulated at the level of individual genes and regulatory elements. Dnase-Seq data is integrated with Chip-seq [GSE36589, GSE30142] and RNA-seq to examine epigentic changes in mitosis. We performed DNase-seq on two cell lines, G1E and G1E-ER4, both on an asynchronus population, and on a sample of cells in mitosis; each of the 4 experiments in triplicate.
2014-10-01 | E-GEOD-61885 | biostudies-arrayexpress
Project description:During mitosis, RNA polymerase and most transcription factors are excluded from the chromosomes and transcription ceases. The transcriptional re-activation of the genome, following mitosis, requires the re-setting of cell-type specific programs that were initially established during development. However, only about one-fifth of transcription factors are retained on chromosomes throughout mitosis and a subset of these have been shown to facilitate target gene reactivation during mitotic exit. How such M-bM-^@M-^\bookmarkingM-bM-^@M-^] factors bind to chromatin in mitosis and re-activate transcription is central to the stability of transcriptional programs across multiple cell cycles. We compared a diverse set of transcription factors involved in liver differentiation and found different modes of mitotic chromosome binding. The pioneer transcription factor FoxA1, which is among the first to bind liver genes in development, exhibits virtually complete mitotic chromosome binding, whereas other liver factors bind with a range of efficiencies. Yet genome-wide analysis shows that only about 15% of the FoxA1 interphase target sites are bound in mitosis; the latter include sites at genes for maintaining cell differentiation. FoxA1 mutants that perturb specific and nonspecific DNA binding reveal a significant contribution of nonspecific binding events in mitotic chromatin. Such nonspecific binding appears to spread from interphase FoxA1 targets and may serve as storage sites. The hierarchy of specific binding, nonspecific binding, partial chromatin binding, and failure to bind mitotic chromosomes reflects the temporal sequence of the factorsM-bM-^@M-^Y developmental roles in gene activation. Three replicate chIP-seq data sets each are included for mitotic and asynchronously cycling cells; a single input lane from each condition is also included.
2013-03-31 | E-GEOD-39241 | biostudies-arrayexpress
Project description:From the cell-based investigation, RBPJ is one of the few proteins retained on chromatin during cell division. ChIP-seq experiments were performed to understand the binding pattern of RBPJ between interphase and mitosis and to identify the genes requiring RBPJ binding for the maintenance of transcriptional memory. Our results indicate that ~60% of RBPJ occupancy in interphase is retained on mitotic chromatin, and that accounts for 80% of RBPJ in mitosis. The gene ontology analysis reveals that the genes involved in stem cell maintenance, development and differentiation-related pathways correlated with sites of RBPJ occupancy. GO analysis also suggests that RBPJ plays a role in the metabolism and processing of non-coding RNAs. Motif analysis of RBPJ binding sites reveals that not only RBPJ motif but also CTCF motif are enriched around RBPJ binding sites. From these results, we propose that RBPJ can function as a mitotic bookmark, marking genes for efficient transcriptional activation or repression upon exit from mitosis, and may play a role in higher order chromatin structure by collaborating with CTCF. To compare the genomic RBPJ localization in mitotic and interphase cells, mouse F9 cells were harvested and labeled as cycling cells (containing 95% interphase and 5% mitosis cells); nocodazole treated F9 cells were harvested and labeled as mitotic cells. Cell samples were proceeded to ChIP-seq experiments, and each of the experiment contains a set of ChIP DNA product: input as the background control and IP as the RBPJ binding product. Background noise was substracted and the obtained signal was used for the comparison of interphase and mitosis by statistical analysis. Please note that processed data (*bed) was generated from *rep1 sample (i.e. no processed-data for rep2 sample).
2014-05-14 | E-GEOD-45889 | biostudies-arrayexpress
Project description:Mitosis entails global alterations to chromosome structure and nuclear architecture, concomitant with transient silencing of transcription. How cells transmit transcriptional states through mitosis remains incompletely understood. While many nuclear factors dissociate from mitotic chromosomes, the observation that certain nuclear factors and chromatin features remain associated with individual loci during mitosis originated the hypothesis that they could provide transcriptional memory through mitosis. To obtain the first genome-wide view of the dynamics of chromatin structure during mitosis, we compared the DNase sensitivity of interphase and mitotic chromatin at two stages of cellular maturation in a rapidly dividingmurine erythroblastmodel. Despite global chromosome condensation visible during mitosis at the microscopic level, the chromatin accessibility landscape is largely unaltered. However, mitotic chromatin accessibility is locally dynamic, with individual loci maintaining none, some, or all of their interphase accessibility. Mitotic reduction in accessibility occurs primarily within narrow, highly hypersensitive sites that frequently coincide with transcription factor binding sites, whereas broader domains of moderate accessibility tend to be more stable. In mitosis, proximal promoters generally maintain their accessibility, whereas distal regulatory elements preferentially lose accessibility. Promoters with the highest degree of accessibility preservation in mitosis tend to also be accessible across many murine tissues in interphase. Transcription factor GATA1 exerts site-specific changes in interphase accessibility that are most pronounced at distal regulatory elements, but does not visibly influence mitotic accessibility. We conclude that features of open chromatin are remarkably stable through mitosis and are modulated at the level of individual genes and regulatory elements.
2014-10-01 | GSE61885 | GEO
Project description:During mitosis, RNA polymerase and most transcription factors are excluded from the chromosomes and transcription ceases. The transcriptional re-activation of the genome, following mitosis, requires the re-setting of cell-type specific programs that were initially established during development. However, only about one-fifth of transcription factors are retained on chromosomes throughout mitosis and a subset of these have been shown to facilitate target gene reactivation during mitotic exit. How such “bookmarking” factors bind to chromatin in mitosis and re-activate transcription is central to the stability of transcriptional programs across multiple cell cycles. We compared a diverse set of transcription factors involved in liver differentiation and found different modes of mitotic chromosome binding. The pioneer transcription factor FoxA1, which is among the first to bind liver genes in development, exhibits virtually complete mitotic chromosome binding, whereas other liver factors bind with a range of efficiencies. Yet genome-wide analysis shows that only about 15% of the FoxA1 interphase target sites are bound in mitosis; the latter include sites at genes for maintaining cell differentiation. FoxA1 mutants that perturb specific and nonspecific DNA binding reveal a significant contribution of nonspecific binding events in mitotic chromatin. Such nonspecific binding appears to spread from interphase FoxA1 targets and may serve as storage sites. The hierarchy of specific binding, nonspecific binding, partial chromatin binding, and failure to bind mitotic chromosomes reflects the temporal sequence of the factors’ developmental roles in gene activation. Gene expression was assessed in asynchronously cycling cells in order to determine whether FoxA1 is disposed to bind to high- or low-expressed genes during mitosis. Heatmap analysis shows that FoxA1's mitotic targets are among the highest-expressed genes in asynchronous cells. Total RNA was collected from three different plates with asynchronous HUH7 cells using the RNeasy mini kit (Qiagen Valencia CA). Expression microarrays were performed with a Human Gene 1.OST array (Affymetrix) at the UPenn Microarray Core Facility and assessed using Partek.
2013-03-31 | E-GEOD-39208 | biostudies-arrayexpress
Project description:Background: Structural maintenance of chromosomes (SMC) complexes are central organizers of chromatin architecture throughout the cell cycle. The SMC family member condensin is best known for establishing long-range chromatin interactions in mitosis. These compact chromatin and create mechanically stable chromosomes. How condensin contributes to chromatin organization in interphase is less well understood. Results: Here, we use efficient conditional depletion of fission yeast condensin to determine its contribution to interphase chromatin organization. We deplete condensin in G2 arrested cells to preempt confounding effects from cell cycle progression without condensin. Genome-wide chromatin interaction mapping, using Hi-C, reveals condensin-mediated chromatin interactions in interphase that are qualitatively similar to those observed in mitosis, but quantitatively far less prevalent. Despite its low abundance, chromatin mobility tracking shows that condensin markedly confines interphase chromatin movements. Without condensin, chromatin behaves as an unconstrained Rouse polymer with excluded volume, while condensin constrains its mobility. Unexpectedly, we find that condensin is required during interphase to prevent ongoing transcription from eliciting a DNA damage response. Conclusions: In addition to establishing mitotic chromosome architecture, condensin-mediated long-range chromatin interactions contribute to shaping chromatin organization in interphase. The resulting structure confines chromatin mobility and protects the genome from transcription-induced DNA damage. This adds to the important roles of condensin in maintaining chromosome stability.
2020-09-14 | GSE143338 | GEO