Project description:Paired-end sequencing study of nucleosomes from MNase-digested nuclei. Nucleosomal DNA from wild type and Rsc8-depleted cells was subjected to paired-end sequencing.
Project description:The nucleosome plays a central role in genome regulation. Traditional methods for mapping nucleosomes depend on the resistance of the nucleosome core to micrococcal nuclease (MNase). However, the lengths of the protected DNA fragments are heterogeneous, limiting the accuracy of nucleosome position information. To resolve this problem, we removed residual linker DNA by simultaneous digestion of yeast chromatin with MNase and exonuclease III (ExoIII). Paired-end sequencing of mono-nucleosomes revealed not only core particles (145-147 bp), but also intermediate particles in which ~8 bp project from one side (154 bp) or both sides (161 bp) of the nucleosome core. We term these particles "pseudo-chromatosomes" because they are present in yeast lacking linker histone. They are also observed after MNase-ExoIII digestion of chromatin reconstituted using recombinant core histones. We propose that the pseudo-chromatosome provides a DNA framework to facilitate H1 binding. Comparison of budding yeast nucleosome sequences obtained using micrococcal nuclease (MNase-seq) and MNase + exonuclease III (ExoIII) (MNase-ExoIII-seq): wild type cells and hho1-null cells. Nucleosome sequences from native chromatin and H1-depleted chromatin from mouse liver. Nucleosome sequences from a plasmid reconstituted into nucleosomes using recombinant yeast histones or native chicken erythrocyte histones.
Project description:Paired-end sequencing study of (1) nucleosome core particles and under-digested chromatin from MNase-treated nuclei; (2) ChIP samples for HA-tagged histone H4 and H2B; (3) ChIP for the Rpb3 subunit of Pol II. Nucleosomal DNA and immunopurified sonicated DNA fragments were subjected to paired-end sequencing.
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
Project description:Altered chromatin structure is a hallmark of cancer, and inappropriate regulation of chromatin structure may represent the origin of transformation. Several important studies have mapped human nucleosome distributions genome wide, but the genome-wide role of chromatin structure in cancer progression has not been addressed. We developed a MNase-Sequence Capture method, mTSS-seq, to map genome-wide nucleosome distribution in primary human lung and colon adenocarcinoma tissue. Here, we confirm that nucleosome redistribution is an early, widespread event in lung (LAC) and colon (CRC) adenocarcinoma. These altered nucleosome architectures are consistent between LAC and CRC patient samples indicating that they may serve as important early adenocarcinoma markers. We demonstrate that the nucleosome alterations are driven by the underlying DNA sequence and potentiate transcription factor binding. We conclude that DNA-directed nucleosome redistributions are widespread early in cancer progression. We have proposed an entirely new hierarchical model for chromatin-mediated genome regulation. â Nucleosome distribution mapping in primary patient tissue at all transcription start sites in the human genome Please note that two processed data files '4137N_ALLcombined.bed' and '4137T_ALLcombined.bed' (linked as Series supplementary file) are processed bed files combined from three 4137N_*_hiseq samples (total 6 raw data files) and three 4137T_*_hiseq samples (total 6 raw data files), respectively.
Project description:All eukaryotic cells divide a finite number of times, termed replicative aging, but the reason for this is not clear. Consistent with the decreased total histone protein levels in aged Saccharomyces cerevisiae, which is a cause of aging (1), we find that nucleosome occupancy decreases 50% across the whole genome during replicative aging by spike-in controlled MNase sequencing. Nucleosomes become fuzzier or move to sequences predicted to better accommodate histone octamers. All yeast genes are induced during aging. Genes that are repressed in young cells are most induced, accompanied by nucleosome loss from their promoters that have unique chromatin organization. Contrary to the loss of mitochondrial function during aging, mitochondrial DNA content increases and unprecedented levels of large-scale chromosomal alterations and increased retrotransposition are observed. Mnase-Seq experiments were carried out for young yeast, old yeast, and old yeast with histone over expression, 3 replicates were done for each category. RNA-Seq were carried out for the same categories of yeast cells but with 2 replicates for each. Genome-Seq were done for the young and old yeast with 2 replicates for each.
Project description:This SuperSeries is composed of the following subset Series: GSE37465: Global Regulation of Nucleosome Organization And Transcription By The Yeast Ssn6-Tup1 Corepressor (MNase-Seq) GSE37466: Global Regulation of Nucleosome Organization And Transcription By The Yeast Ssn6-Tup1 Corepressor (expression) Refer to individual Series
Project description:Gene expression analysis of control fibroblasts (NFH2), one AD-derived fibroblasts (NFH-46), NFH2-derived control-iPS cells (OiPS3, OiPS6), NFH46-derived AD-iPS cells (iPS5 and iPS 26B), hESCs (H1 and H9). Total mRNA obtained from AD fibroblasts (NFH-46) and control fibroblasts (NFH-2), from pluripotent stem cells AD-iPS cells (iPS5 and iPS 26B), control-iPS cells (OiPS3, OiPS6), and hESCs (H1 and H9).