Drosophila melanogaster S2 cells nucleosome occupancy data after simulation by heat killed Salmonella typhimurium
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ABSTRACT:
ORGANISM(S): Drosophila melanogaster
SUBMITTER: Jonathan Dennis
PROVIDER: E-GEOD-64507 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:The innate immune response is among the strongest genomic responses and is conserved across all metazoa. Although transcription during the innate immune response has been well studied, the associated chromatin reorganizations are largely uncharacterized. Here we show that Drosophila S2 cells stimulated with Staphylococcus aureus display a dynamic change in genome-wide nucleosome occupancy and sensitivity. We found a widespread and transient nucleosomal loss peaking at 30 minutes post stimulation, and we demonstrated that the regulatory potentials of nucleosomes differ following stimulation. In addition, we identified differentially sensitive nucleosomes with response-specific potentials. Our results provide high-resolution nucleosome-distribution maps of the fly genome, revealing chromatin's role in: the innate immune response to Gram-positive bacteria, response-specific regulatory-factor binding, and nucleosome sensitivity. We identify functional chromatin regulatory features associated with immune response, and lay a foundation for a framework linking general and locus-specific roles for nucleosomes in immune regulation. Drsophila S2 cells at 0hr, 30minutes, 1hr and 4hr post heat-killed Staphylococcus aureus stimulation
2015-02-28 | E-GEOD-66367 | biostudies-arrayexpress
Project description:In eukaryotes, nucleosomes participate in all DNA-templated events by regulating access to the underlying DNA sequence. However, the dynamics of nucleosomes during a genome response has not been well characterized . We stimulated Drosophila S2 cells with heat-killed Gram-negative bacteria Salmonella typhimurium, and mapped genome-wide nucleosome occupancy at high temporal resolution by MNase-seq using Illumina HiSeq 2500. We show widespread nucleosome occupancy change in S2 cells during the immune response, with the biggest nucleosomal loss occurring at 4hr post stimulation.
2014-12-24 | GSE64507 | GEO
Project description:The experiment was performed to assess the importance of nucleosome eviction for the binding of condensin to chromatin during mitosis. The condensin complex associates with chromatin during mitosis to ensure chromosome condensation and accurate segregation, but how this binding is achieved remains poorly understood. Our study indicates that transcription co-activators Gcn5 and Mst2 assist condensin binding during mitosis by evicting nucleosomes. To reach this conclusion, we mapped nucleosomes, during mitosis, in wild-type and gcn5mst2 mutant strains. This experiment allowed us (1) to identify nucleosome-depleted regions (ndrs) during mitosis and to show that condensin tends to colocalize with ndr at the 3ends of genes, and (2) to confirm the importance of nucleosome eviction from ndrs by gcn5 and mst2, during mitosis, for the binding of condensin to chromatin.this experiment determines the patterns of nucleosomes in wild type and mutant fission yeast cells arrested in early mitosis. We analysed wild-type cells, cells lacking Gcn5 histone acetylatransferase (gcn5D) and cells lacking both Gcn5 and Mst2 histone acetyltransferases (Gcn5Dmst2D). All cells used in this study expressed a GFP-tagged version of condensin (Cnd2-GFP) and were blocked in early mitosis at 19C by the nda3-KM311 mutation. Mitotic indexes were determined by scoring the accumulation of Cnd2-GFP in the nucleus. Mitotic cells were collected and chromatin was digested by increasing amount of MNase to produce mononucleosomes. Mononucleosomal DNA was purified on an agarose gel and sequence on an Illumina Nextseq 500 apparatus. Three replicates of wild type, gcn5D and gcn5Dmst2D were analysed. Nucleosome patterns were determined in wild-type cells, cells lacking Gcn5 and cells lacking both Gcn5 and Mst2.
2016-04-18 | E-MTAB-4620 | biostudies-arrayexpress
Project description:Nucleosome structure and positioning play pivotal roles in gene regulation, DNA repair and other essential processes in eukaryotic cells. Nucleosomal DNA is thought to be uniformly inaccessible to DNA binding and processing factors, such as MNase. Here, we show, however, that nucleosome accessibility and sensitivity to MNase varies. Digestion of Drosophila chromatin with two distinct concentrations of MNase revealed two types of nucleosomes: sensitive and resistant. MNase-resistant nucleosome arrays are less accessible to low concentrations of MNase, whereas MNase-sensitive arrays are degraded by high concentrations. MNase-resistant nucleosomes assemble on sequences depleted of A/T and enriched in G/C containing dinucleotides. In contrast, MNase-sensitive nucleosomes form on A/T rich sequences represented by transcription start and termination sites, enhancers and DNase hypersensitive sites. Lowering of cell growth temperature to ~10°C stabilizes MNase-sensitive nucleosomes suggesting that variations in sensitivity to MNase are related to either thermal fluctuations in chromatin fiber or the activity of enzymatic machinery. In the vicinity of active genes and DNase hypersensitive sites nucleosomes are organized into synchronous, periodic arrays. These patterns are likely to be caused by “phasing” nucleosomes off a potential barrier formed by DNA-bound factors and we provide an extensive biophysical framework to explain this effect. Mnase-seq, Mnase-ChIP-seq of Drosophila melanogaster embryo and S2 cells chromatin
2015-09-17 | E-GEOD-69177 | biostudies-arrayexpress
Project description:Differential gene transcription enables development and homeostasis in all animals and is regulated by two major classes of distal cis-regulatory DNA elements (CREs), enhancers and silencers. While enhancers have been thoroughly characterized, the properties and mechansisms of silencers remain largely unknown. By an unbiased genome-wide functional screen in Drosophila melanogaster S2 cells, we discover a class of silencers that bind one of three transcription factors (TFs) and are generally not included in chromatin-defined CRE catalogs, as they mostly lack detectable DNA accessibility. The silencer-binding TF CG11247, which we term Saft, safeguards cell fate decisions in vivo and functions via a highly-conserved domain we term ZAC and the corepressor G9a, independently of G9a’s H3K9-methyltransferase activity. Overall, our identification of silencers with unexpected properties and mechanisms has important implications for the understanding and future study of repressive CREs, as well as the functional annotation of animal genomes.
2024-11-13 | PXD048161 | Pride
Project description:A conserved hallmark of eukaryotic chromatin architecture is the distinctive array of well-positioned nucleosomes downstream of transcription start sites (TSS). Recent studies indicate that trans-acting factors establish this stereotypical array. Here, we present the first genome-wide in vitro and in vivo nucleosome maps for the ciliate Tetrahymena thermophila. In contrast with previous studies in yeast, we find that the stereotypical nucleosome array is preserved in the in vitro reconstituted map, which is governed only by the DNA sequence preferences of nucleosomes. Remarkably, this average in vitro pattern arises from subsets of nucleosomes, rather than the whole array, being present in individual Tetrahymena genes. Variation in GC content contributes to the positioning of these sequence-directed nucleosomes, and affects codon usage and amino acid composition in genes. We propose that these ‘seed’ nucleosomes may aid the AT-rich Tetrahymena genome – which is intrinsically unfavorable for nucleosome formation – in establishing nucleosome arrays in vivo in concert with trans-acting factors, while minimizing changes to the coding sequences they are embedded within. All data are from the macronuclear genome. Datasets: 1) Log-phase cells, fixed chromatin, light MNase digest; 2) Log-phase cells, native chromatin, heavy MNase digest; 3) Starved cells, fixed chromatin, light MNase digest; 4) Starved cells, native chromatin, heavy MNase digest; 5) in vitro reconstituted chromatin, 50ul reaction, 4:10 histone:DNA ratio, light MNase digest; 6) in vitro reconstituted chromatin, 50ul reaction, 7:10 histone:DNA ratio, light MNase digest; 7) in vitro reconstituted chromatin, 150ul reaction, 4:10 histone:DNA ratio, light MNase digest; 8) in vitro reconstituted chromatin, 150ul reaction, 4:10 histone:DNA ratio, heavy MNase digest; Control dataset: 9): MNase-digested naked DNA
2015-07-30 | E-GEOD-64061 | biostudies-arrayexpress
Project description:The occupancy of nucleosomes governs access to the eukaryotic genomes and results from a combination of biophysical features and the effect of ATP-dependent remodeling complexes. Most promoter regions show a conserved pattern characterized by a nucleosome-depleted region (NDR) flanked by nucleosomal arrays. The conserved RSC remodeler was reported to be critical to establish NDR in vivo in budding yeast but other evidences suggested that this activity may not be conserved in fission yeast. By reanalysing and expanding previously published data, we propose that NDR formation is dependent on RSC in both yeast species. We also discuss the most prominent biological role of RSC and the possibility that non-essential subunits define alternate versions of the complex. Samples from mononucleosomal DNA from S. pombe strains h- kanR-tetO-snf21-Tap-natR ura4::rTetR-tup11 were sequenced (Illumina NextSeq 500 platform) using the pair-end read protocol
2016-08-24 | E-GEOD-84912 | biostudies-arrayexpress
Project description:Chromatin architectural proteins interact with nucleosomes to modulate chromatin accessibility and higher-order chromatin structure. While these proteins are almost certainly important for gene regulation they have been studied far less than the core histone proteins. Here we describe the genomic distributions and functional roles of two chromatin architectural proteins: histone H1 and the high mobility group protein HMGD1, in Drosophila S2 cells. Using ChIP-seq, biochemical and gene specific approaches, we find that HMGD1 binds to highly accessible regulatory chromatin and active promoters. In contrast, H1 is primarily associated with heterochromatic regions marked with repressive histone marks. However, the ratio of HMGD1 to H1 is better correlated with chromatin accessibility, gene expression and nucleosome spacing variation than either protein alone suggesting a competitive mechanism between these proteins. Indeed, we show that HMGD1 and H1 compensate each other’s absence by binding reciprocally to chromatin resulting in changes to nucleosome repeat length and distinct gene expression patterns. Collectively our data suggest that dynamic and mutually exclusive binding of H1 and HMGD1 to nucleosomes and linker sequences may control the fluid chromatin structure that is required for transcriptional regulation. This study thus provides a framework to further study the interplay between chromatin architectural proteins and epigenetics in gene regulation. ChIP-seq of HMGD1 and Histone H1 bound nucleosomes as well as MNase-seq of total nucleosome in Drosophila S2 cells
2013-12-01 | E-GEOD-49526 | biostudies-arrayexpress
Project description:Background The rearrangement of nucleosomes along the DNA fiber profoundly affects gene expression, but little is known about how signaling reshapes the chromatin landscape, in 3D space and over time, to allow the establishment of new transcriptional programs. Results Using micrococcal nuclease treatment and high-throughput sequencing, we map genome-wide changes in nucleosome positioning in primary human endothelial cells stimulated with tumour necrosis factor alpha (TNFalpha) - a proinflammatory cytokine that signals through nuclear factor kappaB (NF-kappaB). Within 10 minutes, nucleosomes reposition at regions both proximal and distal to NF-kappaB binding sites, before the transcription factor quantitatively binds thereon. Similarly, in long TNFalpha-responsive genes, repositioning precedes transcription by pioneering elongating polymerases and appears to nucleate from intragenic enhancer clusters resembling super-enhancers. By 30 minutes, widespread repositioning occurs throughout Mbp-long chromosomal segments, with consequential effects on 3D structure, detected using chromosome conformation capture. Conclusions Whilst nucleosome repositioning is viewed as a local phenomenon, our results point to effects occurring over multiple scales. Here, we present data in support of a TNFalpha-induced priming mechanism, mostly independent of NF-kappaB binding and/or elongating RNA polymerases, leading to a plastic network of interactions that affects DNA accessibility over large domains. MNase-Seq of HUVEC cells after stimulation with TNFα for 0, 10 or 30 min. Biological replicates for 0 and 30 min.
2014-11-05 | E-GEOD-53343 | biostudies-arrayexpress
Project description:Histone acetylation and nucleosome remodeling play a pivotal role in transcriptional regulation. While histone acetylase and ATP-dependent chromatin remodeling activities have been well characterized, how the two activities are coordinated remains to be uncovered. We discovered ATP-dependent histone H2A acetylation activity in Drosophila nuclear extracts. This activity was column-purified and demonstrated to be composed of CBP and SMARCAD1, which belongs to the Etl1 subfamily of the Snf2 family of helicase-related proteins. SMARCAD1 enhanced acetylation of H2A K5 and K8 by CBP in nucleosomes in an ATP-dependent fashion. Expression array analysis of S2 cells having ectopically expressed SMARCAD1 revealed up-regulated genes. Using native genome templates of these up-regulated genes, we found that SMARCAD1 activates their transcription in vitro. Knockdown analysis of SMARCAD1 and CBP indicated overlapping gene control, and ChIP-seq analysis of these commonly controlled genes showed that CBP is recruited to the promoter prior to SMARCAD1. Moreover, Drosophila genetic experiments demonstrated interaction between SMARCAD1/Etl1 and CBP/nej during development. The interplay between the remodeling activity of SMARCAD1 and histone acetylation by CBP sheds light on chromatin and the genome-integrity network. Examination of 2 different protein in 1 cell type.
2016-03-17 | E-GEOD-72666 | biostudies-arrayexpress