Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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H2A.Z Mapping During G0/G1 and Mitosis

ABSTRACT: We report genome wide mapping of the histone variant H2A.Z during G0/G1 and mitosis in T24 bladder cancer cells. The results show that the broad enrichment pattern of H2A.Z near transcription start sites of active genes is maintained during mitosis. Furthermore, using H2A.Z localization to visualize nucleosome positioning near the start site, we see that the +1 nucleosome of active genes shifts upstream to occupy the transcription start sites during mitosis and the nucleosome depleted region is shortened. H2A.Z is also maintained on the -2 nucleosome which also shifts towrds the transcription start site during mitosis, further contributing to the shorteneing of the nucleosome depleted region. Examination of H2A.Z duing G0/G1 and mitosis in bladder cancer cells

ORGANISM(S): Homo sapiens

SUBMITTER: Benjamin Berman

PROVIDER: E-GEOD-19568 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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H2A.Z maintenance during mitosis reveals nucleosome shifting on mitotically silenced genes.

Kelly Theresa K TK Miranda Tina Branscombe TB Liang Gangning G Berman Benjamin P BP Lin Joy C JC Tanay Amos A Jones Peter A PA

Molecular cell 20100901 6

Profound chromatin changes occur during mitosis to allow for gene silencing and chromosome segregation followed by reactivation of memorized transcription states in daughter cells. Using genome-wide sequencing, we found H2A.Z-containing +1 nucleosomes of active genes shift upstream to occupy TSSs during mitosis, significantly reducing nucleosome-depleted regions. Single-molecule analysis confirmed nucleosome shifting and demonstrated that mitotic shifting is specific to active genes that are sil ...[more]

PMID: 20864037

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Project description:While it has been clearly established that well positioned H2A.Z-containing nucleosomes flank the nucleosome depleted region (NDR) at the transcriptional start site (TSS) of active mammalian genes 1,2, how this chromatin-based information is transmitted through the cell cycle is unknown. We show here that in trophoblast stem (TS) cells, the level of H2A.Z at promoters decreases during S phase coinciding with homotypic (H2A.Z/H2A.Z) nucleosomes flanking the TSS becoming heterotypic (H2A.Z/H2A). Surprisingly, these nucleosomes remain heterotypic at M phase. At the TSS, we identify an unstable heterotypic H2A.Z-containing nucleosome in G1 which, strikingly, is lost following DNA replication. These dynamic changes in H2A.Z at the TSS mirror a global expansion of the NDR at S and M which, unexpectedly, is unrelated to transcriptional activity. Coincident with the loss of H2A.Z at promoters, it is targeted to the centromere when mitosis begins. We surveyed whole genome expression using microarrays, in combination with H2A.Z ChIP-Seq (Illumina) data, to study the H2A.Z distribution on promoters of coding genes in different stages of the cell cycle in Trophoblast Stem (TS) cells. These data are published in Nekrasov et al., H2AZ inheritance during the cell cycle and it's impact on promoter organization and dynamics, Nature Structural and Molecular Biology (in press: accepted for publication on 24 Sep 2012). Mouse Trophoblast stem (TS) cells were grown in cell culture medium. By adding specific drugs cells were arrested at particular stages of the cell cycle: G1; S and M. Total RNA was extracted from TS cells arrested at G1; S and M stages of cell cycle using TRizol (Invitrogen) extraction protocol and purified further the by RNAeasy Extraction Kit (Qiagen). RNA quality was assesed on Bioanalyzer total RNA chip. RNA samples were reverse transcribed and resulted cDNA samples were subjected to DNA microarray analysis (in triplicate) using the GeneChip Mouse Gene 1.0 ST Array (Affymetrix). Robust Multichip Average (RMA) correction and probe set summaries were obtained using Affymetrix Power Tools software annotation (Affymetrix) based on the mm9 mouse genome. Unless otherwise stated, all subsequent expression analyses (see Supplementary Methods) were performed in the R statistical computing environment (version 2.11.1).

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.

Dataset Information

H2A.Z Mapping During G0/G1 and Mitosis

Publications

H2A.Z maintenance during mitosis reveals nucleosome shifting on mitotically silenced genes.

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