Dynamic turnover of paused pol II complexes at human promoters
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA480845 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR7515430.fastq.gz | Fastqsanger.gz | |||
| SRR7515440.fastq.gz | Fastqsanger.gz | |||
| SRR7515450.fastq.gz | Fastqsanger.gz | |||
| SRR7515460.fastq.gz | Fastqsanger.gz | |||
| SRR7515431.fastq.gz | Fastqsanger.gz |
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Project description:Paused RNA polymerase II that piles up near most human promoters is the target of mechanisms that control entry into productive elongation. Whether paused pol II is a stable or a dynamic target remains unresolved. We report that most 5’-paused pol II throughout the genome is turned over within 2 minutes. This process is revealed under hypertonic conditions that prevent pol II recruitment to promoters. This turnover requires cell viability but is not prevented by inhibiting transcription elongation suggesting that it is mediated at the level of termination. When initiation was prevented by triptolide during recovery from high salt, a novel pre-initiated state of pol II lacking the pausing factor Spt5 accumulated at transcription start sites. We propose that pol II occupancy near 5’ ends is governed by a cycle of ongoing assembly of pre-initiated complexes that transition to pause sites followed by eviction from the DNA template. This model suggests that mechanisms regulating the transition to productive elongation at pause sites operate on a dynamic population of pol II that is turning over at rates far higher than previously suspected. We suggest that a plausible alternative to elongation control via escape from a stable pause, is by escape from premature termination.
2018-09-14 | GSE117006 | GEO
Project description:Paused RNA polymerase II (Pol II) that piles up near most human promoters is the target of mechanisms that control entry into productive elongation. Whether paused Pol II is a stable or dynamic target remains unresolved. We report that most 5' paused Pol II throughout the genome is turned over within 2 min. This process is revealed under hypertonic conditions that prevent Pol II recruitment to promoters. This turnover requires cell viability but is not prevented by inhibiting transcription elongation, suggesting that it is mediated at the level of termination. When initiation was prevented by triptolide during recovery from high salt, a novel preinitiated state of Pol II lacking the pausing factor Spt5 accumulated at transcription start sites. We propose that Pol II occupancy near 5' ends is governed by a cycle of ongoing assembly of preinitiated complexes that transition to pause sites followed by eviction from the DNA template. This model suggests that mechanisms regulating the transition to productive elongation at pause sites operate on a dynamic population of Pol II that is turning over at rates far higher than previously suspected. We suggest that a plausible alternative to elongation control via escape from a stable pause is by escape from premature termination.
| S-EPMC6120720 | biostudies-literature
Project description:Transcription initiation entails chromatin opening followed by pre-initiation complex formation and RNA Polymerase II recruitment. Subsequent polymerase elongation requires additional signals, resulting in increased residence time downstream of the start site, a phenomenon referred to as pausing. Here we harnessed single molecule footprinting to quantify distinct steps of initiation in vivo throughout the drosophila genome. This identifies the impact of promoter structure on initiation dynamics in relation to nucleosomal occupancy. Additionally, perturbation of transcriptional initiation reveals an unexpected high turnover of polymerases at paused promoters--an observation confirmed at the level of nascent RNAs. These observations argue that absence of elongation is largely caused by premature termination rather than stable polymerase stalling. In support of this non-processive model, we observe that induction of the paused heat-shock promoter depends on continuous initiation. Our study provides a framework to quantify protein binding at single molecule resolution and refines concepts of transcriptional pausing.
2017-06-23 | GSE77369 | GEO
Project description:A correlation between histone acetylation and transcription has been noted for a long time, but little is known about what step(s) in the transcription cycle is influenced by acetylation. Here, we have examined the immediate transcriptional response to histone deacetylase (HDAC) inhibition, and find that release of promoter-proximal paused RNA polymerase II (Pol II) into elongation is stimulated, whereas recruitment to gene promoters is not. Although histone acetylation is elevated globally by HDAC inhibition, less than 100 genes respond within 10 min. These genes are highly paused, are strongly associated with the chromatin regulators NURF and Trithorax, display a greater increase in acetylation of the first nucleosomes than other genes, and become transcriptionally activated by HDAC inhibition. Among these rapidly upregulated genes are HDAC1 (Rpd3) and subunits of HDAC-containing co-repressor complexes, demonstrating feedback regulation upon HDAC inhibition. Our results suggest that histone acetylation stimulates transcription of paused genes, and that increased acetylation is not a consequence of their enhanced expression.
2020-03-30 | GSE141871 | GEO
Project description:Heat shock rapidly induces expression of a small set of genes while globally repressing transcription, making it an attractive system for studying alterations in the chromatin landscape that accompany changes in gene regulation. We have characterized these changes using low-salt extraction of intact micrococcal nuclease (MNase)-treated Drosophila S2 cell nuclei to determine the active nucleosomal and subnucleosomal chromatin landscapes. The low-salt-soluble fraction corresponds to classical "active" chromatin and includes distinct size fractions of MNase-protected particles that can be precisely mapped by paired-end sequencing. After heat shock, the distribution of low-salt-soluble nucleosomes showed an overall reduction over gene bodies, consistent with down-regulation of transcription. No global changes were detected in the subnucleosomal landscape upstream of transcriptional start sites, however, we observed a genome-wide reduction of paused RNA Polymerase II from the active chromatin fraction. Furthermore, nucleosome turnover decreased within gene bodies in a pattern similar to that observed when transcription elongation was artificially inhibited. These observations suggest that reduced Pol II affinity and processivity is the dominant nuclear mechanism for genome-wide repression during heat shock. Our ability to precisely map both nucleosomal and subnucleosomal particles directly from classical active chromatin extracts to assay changes in the chromatin landscape provides a simple general strategy for epigenome characterization. High-throughput sequencing (Illumina HiSeq 2000) We have characterized changes to the active nucleosomal and subnucleosomal landscape during the heat shock response in Drosophila cells by genome-wide profiling of low-salt extracted micrococcal nuclease-treated nuclei, paused RNA Polymerase II and CATCH-IT nucleosome turnover.
2011-11-15 | E-GEOD-30755 | biostudies-arrayexpress
Project description:Transcription by RNA Polymerase II (Pol II) in metazoan is regulated in several steps, including preinitiation complex (PIC) formation, initiation, Pol II escape, productive elongation, cotranscriptional RNA-processing and termination. Genome-wide studies have demonstrated that the phenomenon of promoter-bound Pol II pausing is widespread, especially for genes involved in developmental and stimulus-responsive pathways. However, a mechanistic understanding of the paused Pol II states at promoters is limited. For example, at a global level, it’s unclear to what extent the engaged paused Pol II is stably tethered to the promoter or undergoes rapid cycles of initiation and termination. Here we used the small molecule Triptolide (TPL), an XPB/TFIIH inhibitor, to block transcriptional initiation followed by measuring Pol II occupancy by ChIP-seq. This inhibition of initiation enables us to investigate different states of paused Pol II. Specifically, our global analysis reveals that most genes with paused Pol II, as defined by pausing index, show significant clearance of Pol II during the period of TPL treatment. Our study further identifies a group of genes with unexpectedly stably-paused Pol II, with unchanged Pol II occupancy even after one hour of inhibition of initiation. This group of genes constitutes a small portion of all paused genes defined by the conventional criterion of pausing index. These findings could pave the way for evaluating the contribution of different elongation/pausing factors on different states of Pol II pausing in developmental and other stimulus-responsive pathways. ChIP-Seq of total/Ser5P Pol II in HCT116 cells treated with DMSO or TPL in serum starvation/activation or normal conditions. Nascent RNA-seq in HCT116 cells treated with DMSO or TPL in starved condition.
2015-01-05 | E-GEOD-63314 | biostudies-arrayexpress
Project description:We use a metabolic labeling strategy for directly measuring nucleosome turnover to examine the effect of doxorubicin on chromatin dynamics in squamous cell carcinoma cell lines derived from genetically defined mice. We find that doxorubicin enhances nucleosome turnover around gene promoters, and turnover correlates with gene expression level. Keywords: Chromatin affinity-purification on microarray 26 CATCH-IT arrays and 8 expression arrays.
2013-04-19 | E-GEOD-43753 | biostudies-arrayexpress
Project description:In mammalian cells, widespread acceleration of cytoplasmic mRNA degradation is linked to impaired RNA polymerase II (Pol II) transcription. This mRNA decay-induced transcriptional repression occurs during infection with gammaherpesviruses including Kaposi’s sarcoma associated herpesvirus (KSHV) and murine gammaherpesvirus 68 (MHV68), which encode an mRNA endonuclease that initiates widespread RNA decay. Here, we show that MHV68-induced mRNA decay leads to a genome-wide reduction of Pol II occupancy at mammalian promoters. Viral genes, despite the fact that they require Pol II for transcription, escape this transcriptional repression. Protection is not governed by viral promoter sequences; instead, location on the viral genome is both necessary and sufficient to escape the transcriptional repression effects of mRNA decay. We hypothesize that the ability to escape from transcriptional repression is linked to the localization of viral DNA in replication compartments, providing a means for these viruses to counteract decay-induced viral transcript loss.
2019-12-10 | PXD015786 | Pride
Project description:RNA polymerase III transcribes many noncoding RNAs (e.g. tRNAs) important for translational capacity and other functions. Here, we localized RNA polymerase III, alternative TFIIIB complexes (BRF1/2) and TFIIIC in HeLa cells, determining the Pol III transcriptome, defining gene classes, and revealing ‘TFIIIC-only’ sites. Pol III localization in other transformed and primary cell lines revealed both novel and cell-type specific Pol III loci, and one occupied miRNA. Surprisingly, only a fraction of the in silico-predicted Pol III loci are occupied. Interestingly, many occupied Pol III genes reside within an annotated Pol II promoter. Outside of Pol II promoters, occupied Pol III genes overlap with enhancer-like chromatin and enhancer binding proteins such as ETS1 and STAT1. Remarkably, Pol III occupancy scales with the levels of nearby Pol II, active chromatin and CpG content. Taken together, active promoter and enhancer-like chromatin appears to gate Pol III accessibility to the genome. Use of ChIP-array to identify genomic regions bound by RNA Polymerase III machinery
2010-04-14 | E-GEOD-20609 | biostudies-arrayexpress
Project description:We use a metabolic labeling strategy for directly measuring nucleosome turnover to examine the effect of doxorubicin on chromatin dynamics in squamous cell carcinoma cell lines derived from genetically defined mice. We find that doxorubicin enhances nucleosome turnover around gene promoters, and turnover correlates with gene expression level. Keywords: Chromatin affinity-purification on microarray
2013-04-19 | GSE43753 | GEO