Polycomb associates genome-wide with a specific RNA polymerase II variant, and regulates metabolic genes in ES cells
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE34520 | GEO | 2012/02/01
SECONDARY ACCESSION(S): PRJNA151403
REPOSITORIES: GEO
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Project description:Polycomb repressor complexes (PRCs) are important chromatin modifiers fundamentally implicated in pluripotency and cancer. Polycomb silencing in embryonic stem cells (ESCs) can be accompanied by active chromatin and primed RNA polymerase II (RNAPII), but the relationship between PRCs and RNAPII remains unclear genome-wide. We mapped PRC repression markers and four RNAPII states in ESCs using ChIP-seq, and found that PRC targets exhibit a range of RNAPII variants. First, developmental PRC targets are bound by unproductive RNAPII (S5p(+)S7p(-)S2p(-)) genome-wide. Sequential ChIP, Ring1B depletion, and genome-wide correlations show that PRCs and RNAPII-S5p physically bind to the same chromatin and functionally synergize. Second, we identify a cohort of genes marked by PRC and elongating RNAPII (S5p(+)S7p(+)S2p(+)); they produce mRNA and protein, and their expression increases upon PRC1 knockdown. We show that this group of PRC targets switches between active and PRC-repressed states within the ESC population, and that many have roles in metabolism.
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Project description:This SuperSeries is composed of the following subset Series: GSE34518: Polycomb associates genome-wide with a specific RNA polymerase II variant, and regulates metabolic genes in ES cells (ChIP-Seq) GSE34519: mRNA-seq and expression profile of mouse ES OS25 cells Refer to individual Series
2012-02-01 | E-GEOD-34520 | biostudies-arrayexpress
Project description:Polycomb repressor complexes (PRCs) are important chromatin modifiers fundamentally implicated in pluripotency and cancer. Polycomb silencing in embryonic stem cells (ESCs) can be accompanied by active chromatin and primed RNA polymerase II (RNAPII), but the relationship between PRCs and RNAPII remains unclear at the genome-wide level. We mapped PRC repression markers and four RNAPII states in ESCs using ChIP-seq, and found that PRC-targets exhibit a range of RNAPII variants. Firstly, developmental PRC-targets are bound by unproductive RNAPII (S5p+S7p- S2p-) genome-wide. Sequential ChIP, Ring1B-depletion and genome-wide correlations show that PRCs and RNAPII-S5p physically bind to the same chromatin and functionally synergize. Secondly, we identify a cohort of genes marked by PRC and elongating RNAPII (S5p+S7p+S2p+); they produce mRNA and protein, and their expression increases upon PRC1 knockdown. We show that this novel group of PRC-targets switch between active and PRC-repressed states within the ESC population, and that many have roles in metabolism. **Correction (Mar 14, 2012): Due to curation error, runs for SRX112177 and SRX112179 switched, specifically, Run SRR391034.1 was removed from experiment SRX112177 (GSM850468) and added to experiment SRX112179 (GSM850470) as SRR391034.3 Run SRR391040.1 was removed from experiment SRX112179 (GSM850470) and added to experiment SRX112177 (GSM850468) as SRR391040.3 Examination of 4 different RNAPII modifications (S5p, S7p, 8WG16, S2p), and the histone modifications H2Aub1 and H3K36me3 in mouse ES cells
2012-02-01 | E-GEOD-34518 | biostudies-arrayexpress
Project description:Polycomb repressor complexes (PRCs) are important chromatin modifiers fundamentally implicated in pluripotency and cancer. Polycomb silencing in embryonic stem cells (ESCs) can be accompanied by active chromatin and primed RNA polymerase II (RNAPII), but the relationship between PRCs and RNAPII remains unclear at the genome-wide level. We mapped PRC repression markers and four RNAPII states in ESCs using ChIP-seq, and found that PRC-targets exhibit a range of RNAPII variants. Firstly, developmental PRC-targets are bound by unproductive RNAPII (S5p+S7p- S2p-) genome-wide. Sequential ChIP, Ring1B-depletion and genome-wide correlations show that PRCs and RNAPII-S5p physically bind to the same chromatin and functionally synergize. Secondly, we identify a cohort of genes marked by PRC and elongating RNAPII (S5p+S7p+S2p+); they produce mRNA and protein, and their expression increases upon PRC1 knockdown. We show that this novel group of PRC-targets switch between active and PRC-repressed states within the ESC population, and that many have roles in metabolism. **Correction (Mar 14, 2012): Due to curation error, runs for SRX112177 and SRX112179 switched, specifically, Run SRR391034.1 was removed from experiment SRX112177 (GSM850468) and added to experiment SRX112179 (GSM850470) as SRR391034.3 Run SRR391040.1 was removed from experiment SRX112179 (GSM850470) and added to experiment SRX112177 (GSM850468) as SRR391040.3
2012-02-01 | GSE34518 | GEO
Project description:Despite the important role of Polycomb in genome-wide silencing, little is known of the specific biochemical mechanism by which it inactivates transcription. Here we address how recombinant Polycomb repressive complex 1 (PRC1) inhibits activated RNA polymerase II preinitiation complex (PIC) assembly using immobilized H3K27-methylated chromatin templates in vitro. Recombinant PRC1 inhibited transcription, but had little effect on binding of the activator as reported previously. In contrast, Mediator and the general transcription factors were blocked during assembly or dissociated from preassembled PICs. Importantly, among the PIC components, Tata Binding Protein (TBP) was the most resistant to eviction by PRC1. Immobilized template experiments using purified PRC1, transcription factor II D (TFIID), and Mediator indicate that PRC1 blocks the recruitment of Mediator, but not TFIID. We conclude that PRC1 functions to block or dissociate PICs by interfering with Mediator, but leaves TBP and perhaps TFIID intact, highlighting a specific mechanism for PRC1 transcriptional silencing. Analysis of published genome-wide datasets from mouse embryonic stem cells revealed that the Ring1b subunit of PRC1 and TBP co-enrich at developmental genes. Further, genes enriched for Ring1b and TBP are expressed at significantly lower levels than those enriched for Mediator, TBP, and Ring1b. Collectively, the data are consistent with a model in which PRC1 and TFIID could co-occupy genes poised for activation during development.
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Project description:Polycomb repression in mouse embryonic stem cells (ESCs) is tightly associated with promoter co-occupancy of RNA polymerase II (RNAPII) which is thought to prime genes for activation during early development. However, it is unknown whether RNAPII poising is a general feature of Polycomb repression, or is lost during differentiation. Here, we map the genome-wide occupancy of RNAPII and Polycomb from pluripotent ESCs to non-dividing functional dopaminergic neurons. We find that poised RNAPII complexes are ubiquitously present at Polycomb-repressed genes at all stages of neuronal differentiation. We observe both loss and acquisition of RNAPII and Polycomb at specific groups of genes reflecting their silencing or activation. Strikingly, RNAPII remains poised at transcription factor genes which are silenced in neurons through Polycomb repression, and have major roles in specifying other, non-neuronal lineages. We conclude that RNAPII poising is intrinsically associated with Polycomb repression throughout differentiation. Our work suggests that the tight interplay between RNAPII poising and Polycomb repression not only instructs promoter state transitions, but also may enable promoter plasticity in differentiated cells.
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Project description:Polycomb group (PcG) proteins initiate the formation of repressed chromatin domains and regulate developmental gene expression. A mammalian PcG protein, Enhancer of Zeste homolog 2 (Ezh2), triggers transcriptional repression by catalyzing the addition of methyl groups onto lysine-27 of histone H3 (H3K27me2/3)1. This action facilitates the binding of other PcG proteins to histone H3 and compaction of chromatin. Interestingly, there exists a paralog of Ezh2, termed Ezh1, whose primary function remains unclear. Here, we provide evidence for genome-wide association of Ezh1 with active epigenetic marks, RNA polymerase II (PolII) and mRNA production. Ezh1 depletion reduced global PolII occupancy within gene bodies and resulted in delayed transcriptional activation during differentiation of skeletal muscle cells. Conversely, ectopic expression of wild-type Ezh1 led to premature gene activation and rescued PolII-elongation defects in Ezh1-depleted cells. Collectively, these findings reveal an unanticipated role of a PcG protein in promoting mRNA transcription. Examination of 3 different histone modifications, 3 modified forms of RNA polymerase II, Ezh1, Ezh2 and mRNA levels in a skeletal muscle cells at various developmental stages.
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