Nucleosomes are context-specific, H2A.Z modulated barriers to RNA polymerase
Ontology highlight
ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE49106 | GEO | 2014/03/06
SECONDARY ACCESSION(S): PRJNA213006
REPOSITORIES: GEO
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Project description:Nucleosomes are barriers to transcription in vitro, however, their effects on RNA polymerase in vivo are unknown. Here we describe a simple and general strategy to comprehensively map the positions of elongating and arrested RNA Polymerase II (RNAPII) at nucleotide resolution. Our results suggest that nucleosomes present significant, context-specific barriers to RNAPII in vivo that can be tuned by the incorporation of H2A.Z. 8 sets of two replicates each of paired-end and 3 sets of two replicates each of single-end samples were sequenced and analyzed.
2014-03-06 | E-GEOD-49106 | biostudies-arrayexpress
Project description:Micrococcal nuclease (MNase) is commonly used to map nucleosomes genome-wide, but nucleosome maps are affected by the degree of digestion. It has been proposed that many yeast promoters are not nucleosome-free but occupied by easily digested, unstable, “fragile” nucleosomes. We analyzed the histone content of all MNase-sensitive complexes by MNase-ChIP-seq and Sonication-ChIP-seq. We find that yeast promoters are predominantly bound by non-histone protein complexes, with little evidence for fragile nucleosomes. We do detect MNase-sensitive nucleosomes elsewhere in the genome, including transcription termination sites. However, they have high A/T-content, suggesting that MNase sensitivity does not indicate instability, but the preference of MNase for A/T-rich DNA, such that A/T-rich nucleosomes are digested faster than G/C-rich nucleosomes. We confirm our observations by analyzing ChIP-exo, chemical mapping and ATAC-seq data from other laboratories. Thus, histone ChIP-seq experiments are essential to distinguish nucleosomes from other DNA-binding proteins that protect against MNase.
2016-12-15 | GSE83123 | GEO
Project description:All histone-DNA contacts in a nucleosome must be disrupted for RNA polymerase II (RNAPII) to transcribe through chromatin. However, the structural transitions of the nucleosome during transcription in vivo are unknown. To identify nucleosomal intermediates formed during transcription in vivo, we mapped subnucleosomal protections in Drosophila cells using Micrococcal Nuclease followed by deep sequencing. At the first nucleosome position downstream of the transcription start site, we identified hexasomes lacking an H2A/H2B dimer. Inhibiting topoisomerases or depleting histone chaperones increased dimer loss, whereas inhibiting release of paused RNAPII or reducing RNAPII elongation decreased dimer loss. Our results suggest that positive torsion generated by elongating RNAPII evicts the distal H2A/H2B dimer in vivo. We also identified diagnostic subnucleosomal particle remnants in cell-free human DNA data as a relic of transcribed genes from the tissue-of-origin. Thus the identification of subnucleosomal particle fragments from nuclease protection data represents a general strategy for structural epigenomics.
2017-12-22 | GSE98351 | GEO
Project description:Deregulation of RNA Polymerase II (RNAPII) by oncogenic signaling leads to collisions of RNAPII with DNA synthesis machinery (transcription-replication conflicts, TRCs). TRCs can result in DNA damage and underlie genomic instability in tumor cells. Here we provide evidence that elongating RNAPII promotes activation of the ATM kinase at TRCs to drive DNA repair. We show the ATPase Wrnip1 that binds and protects stalled replication forks, associates with RNAPII and limits ATM activation. Wrnip1 binding to elongating RNAPII requires catalytic activity of the ubiquitin ligase Huwe1. Mutation of Huwe1 promotes the transfer of Wrnip1 onto replisome and induces TRCs stimulating ATM activation on RNAPII. This mechanism is evoked early upon replicative stress to induce Wrnip1 translocation and ATM signaling at TRCs. Thus, although primarily considered as genotoxic events, TRCs can provide a mechanism to maintain genome stability under replicative stress.
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Project description:Deregulation of RNA Polymerase II (RNAPII) by oncogenic signaling leads to collisions of RNAPII with DNA synthesis machinery (transcription-replication conflicts, TRCs). TRCs can result in DNA damage and underlie genomic instability in tumor cells. Here we provide evidence that elongating RNAPII promotes activation of the ATM kinase at TRCs to drive DNA repair. We show the ATPase Wrnip1 that binds and protects stalled replication forks, associates with RNAPII and limits ATM activation. Wrnip1 binding to elongating RNAPII requires catalytic activity of the ubiquitin ligase Huwe1. Mutation of Huwe1 promotes the transfer of Wrnip1 onto replisome and induces TRCs stimulating ATM activation on RNAPII. This mechanism is evoked early upon replicative stress to induce Wrnip1 translocation and ATM signaling at TRCs. Thus, although primarily considered as genotoxic events, TRCs can provide a mechanism to maintain genome stability under replicative stress.
2023-07-31 | PXD037812 | Pride
Project description:Deregulation of RNA Polymerase II (RNAPII) by oncogenic signaling leads to collisions of RNAPII with DNA synthesis machinery (transcription-replication conflicts, TRCs). TRCs can result in DNA damage and underlie genomic instability in tumor cells. Here we provide evidence that elongating RNAPII promotes activation of the ATM kinase at TRCs to drive DNA repair. We show the ATPase Wrnip1 that binds and protects stalled replication forks, associates with RNAPII and limits ATM activation. Wrnip1 binding to elongating RNAPII requires catalytic activity of the ubiquitin ligase Huwe1. Mutation of Huwe1 promotes the transfer of Wrnip1 onto replisome and induces TRCs stimulating ATM activation on RNAPII. This mechanism is evoked early upon replicative stress to induce Wrnip1 translocation and ATM signaling at TRCs. Thus, although primarily considered as genotoxic events, TRCs can provide a mechanism to maintain genome stability under replicative stress.
2023-07-31 | PXD037680 | Pride
Project description:Every nucleosome across the genome must be disrupted and reformed when the replication fork passes, but how chromatin organization is re-established following replication is unknown. To address this problem, we have developed Mapping In vivo Nascent Chromatin with EdU and sequencing (MINCE-seq) to characterize the genome-wide location of nucleosomes and other chromatin proteins behind replication forks at high temporal and spatial resolution. We find that the characteristic chromatin landscape at Drosophila promoters and enhancers is lost upon replication. The most conspicuous changes are at promoters that have high levels of RNA polymerase II (RNAPII) stalling and DNA accessibility and show specific enrichment for the BRM remodeler. Enhancer chromatin is also disrupted during replication, suggesting a role for transcription factor (TF) competition in nucleosome re-establishment. Thus, the characteristic nucleosome landscape emerges from a uniformly packaged genome by the action of TFs, RNAPII and remodelers minutes after replication fork passage.
2016-04-07 | GSE76120 | GEO
Project description:Nucleosomes are context-specific, H2A.Z modulated barriers to RNA polymerase
| PRJNA213006 | ENA
Project description:Eukaryotic DNA is wrapped around histone octamers to form nucleosomes, which are separated by linker DNA bound by histone H1. In many species, the DNA exhibits methylation of CG dinucleotides, which is epigenetically inherited via a semiconservative mechanism. How methyltransferases access DNA within nucleosomes remains mysterious. Here we show that methylation of nucleosomes requires DDM1/Lsh nucleosome remodelers in Arabidopsis thaliana and mouse. We also show that removal of histone H1, which partially restores methylation in ddm1 mutants, does so primarily in the linker DNA between nucleosomes. In h1ddm1 compound mutants, substantial portions of the genome exhibit dramatically periodic methylation that approaches wild-type levels in linker DNA but is virtually absent in nucleosomes. We also present evidence that de novo methylation supplements semiconservative maintenance of CG methylation across generations. Overall, our results demonstrate that nucleosomes and H1 are barriers to DNA methylation, which are overcome by DDM1/Lsh nucleosome remodelers.
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Project description:To separate replicated sister chromatids during mitosis, eukaryotes and prokaryotes have structural maintenance of chromosome (SMC) condensin complexes that were recently shown to organize chromosomes by a process known as DNA loop extrusion. In rapidly dividing bacterial cells, the process of separating sister chromatids occurs concomitantly with ongoing transcription. How transcription interferes with the condensin loop extrusion process is largely unexplored, but recent experiments show that sites of high transcription may directionally affect condensin loop extrusion. We quantitatively investigate different mechanisms of interaction between condensin and elongating RNA polymerases (RNAP) and find that RNAPs are likely steric barriers that can push and interact with condensins. Supported by new Hi-C and ChIP-seq data for cells after transcription inhibition and RNAP degradation, we argue that translocating condensins must bypass transcribing RNAPs within ~2 seconds of an encounter at rRNA genes and within ~10 seconds at protein coding genes. Thus, while individual RNAPs have little effect on the progress of loop extrusion, long, highly transcribed operons can significantly impede the extrusion process. Our data and quantitative models further suggest that bacterial condensin loop extrusion occurs by two independent, uncoupled motor activities; the motors translocate on DNA in opposing directions and function together to enlarge chromosomal loops, each independently bypassing steric barriers in their path. Our study provides a quantitative link between transcription and 3D genome organization and proposes a mechanism of interactions between SMC complexes and elongating transcription machinery relevant from bacteria to higher eukaryotes.
2019-09-23 | GSE117854 | GEO