Dynamics of nucleosome positioning maturation following genomic replication
Ontology highlight
ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
SUBMITTER: Marta Radman-Livaja
PROVIDER: E-GEOD-79384 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:Replication of the eukaryotic genome occurs in the context of chromatin, a nucleoprotein packaging state consisting of repeating nucleosomes. Chromatin is commonly thought to carry epigenetic information from one generation to the next, although it is unclear how such information survives the disruptions of nucleosomal architecture that occur during genomic replication. Here, we sought to directly measure a key aspect of chromatin structure dynamics during replication â how rapidly nucleosome positions are established on the newly-replicated daughter genomes. By isolating newly-synthesized DNA marked with the nucleotide analogue EdU, we characterize nucleosome positions on both daughter genomes of budding yeast during a time course of chromatin maturation. We find that nucleosomes rapidly adopt their mid log positions at highly-transcribed genes, and that this process was impaired upon treatment with the transcription inhibitor thiolutin, consistent with a role for transcription in positioning nucleosomes in vivo. Additionally, experiments in the Hir1Î background reveal a role for HIR in nucleosome spacing. Using strand-specific EdU libraries, we characterize nucleosome positions on the leading and lagging strand daughter genomes, uncovering differences in chromatin maturation dynamics between the two daughter genomes at hundreds of genes. Our data define the maturation dynamics of newly-replicated chromatin, and support a role for transcription in sculpting the chromatin template. We have mapped changes in nucleosome positions on newly replicated DNA in a timecourse after genome replication. We have used Micrococcal Nuclease footprinting of cross linked chromatin to determine nucleosome positions and EdU (ethylene deoxy uridine) to mark nascent DNA strands. EdU incorporated into nascent DNA strands was biotinylated with Click chemistry and nascent DNA strand fragments were subsequently isolated using Streptavidin coated magnetic beads.
2016-08-25 | E-GEOD-74090 | biostudies-arrayexpress
Project description:Replication of the eukaryotic genome occurs in the context of chromatin, a nucleoprotein packaging state consisting of repeating nucleosomes. Chromatin is commonly thought to carry epigenetic information from one generation to the next, although it is unclear how such information survives the disruptions of nucleosomal architecture that occur during genomic replication. Here, we sought to directly measure a key aspect of chromatin structure dynamics during replication – how rapidly nucleosome positions are established on the newly-replicated daughter genomes. By isolating newly-synthesized DNA marked with the nucleotide analogue EdU, we characterize nucleosome positions on both daughter genomes of budding yeast during a time course of chromatin maturation. We find that nucleosomes rapidly adopt their mid log positions at highly-transcribed genes, and that this process was impaired upon treatment with the transcription inhibitor thiolutin, consistent with a role for transcription in positioning nucleosomes in vivo. Additionally, experiments in the Hir1Δ background reveal a role for HIR in nucleosome spacing. Using strand-specific EdU libraries, we characterize nucleosome positions on the leading and lagging strand daughter genomes, uncovering differences in chromatin maturation dynamics between the two daughter genomes at hundreds of genes. Our data define the maturation dynamics of newly-replicated chromatin, and support a role for transcription in sculpting the chromatin template.
2016-08-25 | GSE74090 | GEO
Project description:Replication of the eukaryotic genome occurs in the context of chromatin, a nucleoprotein packaging state consisting of repeating nucleosomes. Chromatin is commonly thought to carry epigenetic information from one generation to the next, although it is unclear how such information survives the disruptions of nucleosomal architecture that occur during genomic replication. Here, we sought to directly measure a key aspect of chromatin structure dynamics during replication – how rapidly nucleosome positions are established on the newly-replicated daughter genomes. By isolating newly-synthesized DNA marked with the nucleotide analogue EdU, we characterize nucleosome positions on both daughter genomes of budding yeast during a time course of chromatin maturation. We find that nucleosomes rapidly adopt their mid log positions at highly-transcribed genes, and that this process was impaired upon treatment with the transcription inhibitor thiolutin, consistent with a role for transcription in positioning nucleosomes in vivo. Additionally, experiments in the Hir1-delta background reveal a role for HIR in nucleosome spacing. Using strand-specific EdU libraries, we characterize nucleosome positions on the leading and lagging strand daughter genomes, uncovering differences in chromatin maturation dynamics between the two daughter genomes at hundreds of genes. Our data define the maturation dynamics of newly-replicated chromatin, and support a role for transcription in sculpting the chromatin template.
2016-08-25 | GSE79384 | GEO
Project description:Previous studies indicate that eukaryotic promoters display a stereotypical chromatin landscape characterized by a well-positioned +1 nucleosome near the transcription start site and an upstream -1 nucleosome that together demarcate a nucleosome-free (or depleted) region. Here we present evidence that there are two distinct types of promoters distinguished by the resistance of the -1 nucleosome to micrococcal nuclease digestion. These different architectures are characterized by two sequence motifs that are broadly deployed at one set of promoters where a nuclease-sensitive ("fragile") nucleosome forms, but concentrated in a more narrow, nucleosome-free region at all other promoters. The RSC nucleosome remodeler acts through the motifs to establish stable +1 and -1 nucleosome positions, while binding of a small set of general regulatory (pioneer) factors at fragile nucleosome promoters plays a key role in their destabilization. We propose that the fragile nucleosome promoter architecture is adapted for regulation of highly expressed, growth-related genes. MNase-seq profiles obtained with various MNase concentrations from wild-type cells and cells depleted of different factors. ChIP-seq using anti-RNA polymerase II antibody, anti-histone H2A antibody, and anti-histone H3 antibody.
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Project description:Faithful DNA replication is essential for normal cell division and differentiation. In eukaryotic cells, DNA replication takes place on chromatin. This poses the critical question as to how DNA replication can progress through chromatin, which is inhibitory to all DNA-dependent processes. Here, we have developed a novel genome-wide method to measure chromatin accessibility to micrococcal nuclease that is normalized for nucleosome density, NCAM (Normalized Chromatin Accessibility to MNase) assay. This method enabled us to discover that chromatin accessibility increases specifically at and ahead of DNA replication forks in normal S phase and during replication stress. We further found that Mec1, a key regulatory ATR-like kinase in the S-phase checkpoint, is required for both normal chromatin accessibility around replication forks and replication fork rate during replication stress. In this study we sought to analyze the chromatin structural changes that take place at sites of DNA replication. To this end, we obtained yeast cell populations synchronously undergoing DNA replication by M-NM-1-factor G1 arrest and release. In order to analyze chromatin structure at sites of DNA replication we first mapped the genomic locations undergoing DNA replication to high-resolution, strand-specific microarrays tiling chromosomes III, VI, and XII, covering ~14% of the genome. Two complementary approaches were taken: (1) we mapped fork positions by chromatin immunoprecipitation (ChIP) of a FLAG-tagged DNA polymerase 1 (Pol1), a replication fork component and (2) we mapped the sites of active DNA synthesis by generating DNA copy number profiles. We then analyzed chromatin structure at the sites of DNA replication by Micrococcal nuclease mononucleosome mapping and by generating histone H3 density maps. We further generated a Normalized Chromatin Accessibility to MNase (NCAM) signal by normalizing MNase mononucleosome signal for histone H3 density. NCAM signal represents a measure of nucleosome accessibility to MNase that is normalized for nucleosome content. These three approaches allowed us to assess potential changes in nucleosome positioning, nucleosome density, and nucleosome accessibility during DNA replication. We searched for changes in chromatin structure by comparing, during S phase, regions undergoing DNA replication to those not yet replicated, and also by comparing the same region before replication (not replicated, G1 arrested control) and during DNA replication in S phase. We typically harvested S phase cells at 30 or 60 minutes after release from G1 arrest. Experimental conditions included releasing cells into rich media at 24M-BM-0C or into rich media containing 200 mM Hydroxyurea (HU). Both conditions slowed down replication fork rate and made these experiments feasible. For each strain, samples for the different experiments (Chromatin for Pol1 and H3 ChIP, in vivo MNase digestion, and DNA for DNA copy number profiles) were harvested simultaneously for each time point. Therefore, comparisons between time points for each strain must be made using samples from the same replicate experiment. Our analysis included WT cells, as well as S phase checkpoint mutants (M-NM-^Tmec1 M-NM-^Tsml1 and mec1-100 M-NM-^Tsml1), as well as control strains (M-NM-^Tsml1).
2013-01-17 | E-GEOD-43548 | biostudies-arrayexpress
Project description:The distribution of nucleosomes along the genome is a significant aspect of chromatin structure and is thought to influence gene regulation through modulation of DNA accessibility. However, properties of nucleosome organization remain poorly understood, particularly in mammalian genomes where nucleosome positions have not been examined beyond isolated loci and promoter regions. Towards this goal we used tiled microarrays to identify stable nucleosome positions along the HOX gene clusters in human cell lines. We show that nucleosome positions exhibit sequence properties and long-range organization that are different from those characterized in other organisms. Despite overall variability of inter-nucleosome distances, specific loci contain regular nucleosomal arrays with 195bp periodicity. Moreover, such arrays tend to occur preferentially toward the 3’ ends of genes. Through comparison of different cell lines, we find that increased gene expression correlates with increased positioning of nucleosomes, suggesting an unexpected role for transcription in the establishment of well-positioned nucleosomes. Keywords: human chromatin nucleosome positions, nucleosomes, ChIP-chip
2008-02-20 | GSE10042 | GEO
Project description:Eukaryotic cells package their genomes around histone octamers. In response to DNA damage checkpoint kinase-induced core histone degradation leads to a 20-40% reduction in nucleosome density in yeast. To gain insights into this process we report the first comprehensive proteomic analysis of yeast chromatin and the alterations that occur in response to DNA damage. We analyzed the protein content of formaldehyde cross-linked chromatin using tandem mass tag (TMT), multiplexing and high-resolution mass spectrometry (MS), after sucrose gradient enrichment of the chromatin fraction. Quantitative damage-induced changes in the chromatin-bound proteome (called chromatome), were compared among wild-type cells and those defective for the INO80 remodeler (arp8Δ), or high mobility group box proteins (Nhp6a and Nhp6b, nhp6ΔΔ). We find massive changes in the chromatome in response to Zeocin, which are strongly attenuated in cells lacking a functional INO80 remodeler.
2021-02-02 | PXD022369 | Pride
Project description:Nucleosome positioning dictates the DNA accessibility for regulatory proteins, and thus is critical for gene expression and regulation. It has been well documented that only a subset of nucleosomes are reproducibly positioned (phased) in eukaryotic genomes. The most prominent example of phased nucleosomes is the context of genes, where phased nucleosomes flank the transcriptional starts sites (TSSs). It is unclear, however, what factors influence nucleosome phasing in regions that are not close to genes. We performed a combinational mapping of nucleosome positioning and DNase I hypersensitive sites (DHSs) across the rice genome. We discovered that DHSs located in a variety of contexts, both genic and intergenic, were flanked by strongly phased nucleosome arrays. Our results support the barrier model for nucleosome organization as a general feature of eukaryote genomes, including plant genomes, and not limited to TSSs. Specifically, regions bound with regulatory proteins, including intergenic regions, can serve as barriers that organize phased nucleosome arrays on both sides. Our results also suggest that rice DHSs often span a single, phased nucleosome, similar to the H2A.Z-containing nucleosomes observed in DHSs in the human genome. We propose that genome-wide nucleosome positioning in the eukaryotic genomes is orchestrated by genomic regions associated with regulatory proteins. Rice chromatin was digested by micrococcal nuclease (MNase) into mono-nucleosome size. Mono-nucleosomal DNA was isolated and sequenced (MNase-seq) using Illumina sequencing platforms. We obtained a total of 38 million (M) single-end reads from our first MNase-seq experiment and mapped ~26 M to unique positions in the rice genome. We also conducted pair-end sequencing of an independent MNase-seq library, obtained 274 M paired-end reads, and mapped ~231 M read pairs to unique positions in the rice genome.We applied a strategy of combinational mapping of nucleosome positioning and DHSs (GSE26610) to examine whether nucleosome positioning is associated with all cis-regulatory elements in the rice genome. All datasets used in the analysis were developed using rice leaf tissue in the same developmental stage
2014-05-01 | E-GEOD-53027 | biostudies-arrayexpress
Project description:Mammalian genomes contain billions of basepairs of DNA that must be highly compacted as chromatin to fit into the nano-scale of the nucleus, but yet be accessible to allow for transcription to occur. Binding to nucleosomal DNA is critical for ÔpioneerÕ transcription factors such as Foxa1 and Foxa2 to regulate chromatin structure and gene activation. Here we report the genome-wide map of nucleosome positions in the mouse liver, with emphasis on transcriptional start sites, CpG islands, Foxa2 binding sites, and their correlation with gene expression. Despite the heterogeneity of liver tissue, we could clearly discern the nucleosome pattern of the predominant liver cell, the hepatocyte. By analyzing nucleosome occupancy and the distributions of heterochromatin protein 1 (Hp1), CBP, and p300 in Foxa1/2-deficient livers we find, surprisingly, that the maintenance of nucleosome position and chromatin structure surrounding Foxa2 binding sites is independent of Foxa1/2. Original data matrix is in the archive: E-MTAB-514.additional.zip
2011-05-05 | E-MTAB-514 | biostudies-arrayexpress
Project description:Nucleosomes in active chromatin are dynamic, but whether they have distinct structural conformations is unknown. To identify nucleosomes with alternative structures genome-wide, we used H4S47C-anchored cleavage mapping, which revealed that nucleosomes at 5% of budding yeast nucleosome positions have asymmetric histone-DNA interactions. These asymmetric interactions are enriched at nucleosome positions that flank promoters. Micrococcal nuclease (MNase) sequence-based profiles of asymmetric nucleosome positions revealed a corresponding asymmetry in MNase protection near the dyad axis, suggesting that the loss of DNA contacts around H4S47 is accompanied by protection of the DNA from MNase. Chromatin immunoprecipitation mapping of selected nucleosome remodelers indicated that asymmetric nucleosomes are bound by the RSC chromatin remodeling complex, which is required for maintaining nucleosomes at asymmetric positions. These results imply that the asymmetric nucleosome-RSC complex is a metastable intermediate representing partial unwrapping and protection of nucleosomal DNA on one side of the dyad axis during chromatin remodeling. We have analyzed the chromatin landscape of the yeast genome using paired-end MNase-seq and the chromatin binding of yeast remodelers Swr1, Ino80 and RSC at base-pair resolution using native chromatin immunoprecipitation followed by sequencing (N-ChIP-seq).
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