Loss of Cohesin regulator PDS5A reveals repressive role of Polycomb loops
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE194268 | GEO | 2023/11/10
REPOSITORIES: GEO
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Project description:R-loops are three-stranded nucleic acid structures that form naturally during transcription, especially over unmethylated CpG-rich promoters. In mESC, such promoters of developmental regulator genes are occupied by the Polycomb-repressor complexes PRC1 and PRC2. Here we have explored the possibility that R-loops form over Polycomb-repressed genes and play a role in their transcriptional silencing. Using single gene and genome-wide analyses, we show that R-loops form at a specific subset of PRC-target genes and contribute to Polycomb occupancy on chromatin. Removal of R-loops leads to an up-regulation of nascent and processed transcripts and the appearance of the elongating form of RNA polymerase II. In contrast, removal of PRC2 does not influence R-loop formation, transcriptional repression and PRC1 recruitment. We finally show that R-loops and PRC1 can repress Polycomb-target genes in the absence of PRC2. Our results uncover an unanticipated synergy between R-loops and PRC1 in Polycomb repression mechanisms.
2019-03-19 | GSE118115 | GEO
Project description:• Polycomb (PcG) regulation is crucial for development across eukaryotes, but how PcG targets are specified is still incompletely understood. The slow timescale of cold-induced Polycomb Repressive Complex 2 silencing during vernalization at Arabidopsis thaliana FLOWERING LOCUS C (FLC) provides an excellent system to elucidate the sequence of events. Association of the DNA binding protein VAL1 to an FLC intronic RY motif within the PcG nucleation region is an important step. VAL1 is associated in vivo with APOPTOSIS AND SPLICING ASSOCIATED PROTEIN (ASAP) complex and Polycomb Repressive Complex 1 (PRC1). Here, we show that ASAP and PRC1 functions are necessary for co-transcriptional repression and chromatin regulation during FLC silencing. ASAP mutants affect FLC transcription in warm conditions, but the rate of FLC silencing in the cold is unaffected. PRC1-mediated H2Aub accumulation increases at the nucleation region upon exposure to cold, but unlike the PRC2-delivered H3K27me3 does not spread across the locus. H2Aub is thus involved in the transition to epigenetic silencing at FLC facilitating H3K27me3 accumulation, which in turn is necessary for long-term epigenetic memory. Overall, our work highlights the importance of the DNA sequence-specific binding protein VAL1 as an assembly platform coordinating the co-transcriptional repression and chromatin regulation necessary for the epigenetic silencing of FLC.
2022-10-13 | PXD036548 | Pride
Project description:Polycomb group (PcG) proteins are highly conserved from flies to mammals and many of these factors have essential roles in early embryonic development. PcG proteins comprise two multimeric complexes, the Polycomb Repressive complexes 1 and 2 (PRC1 and 2), which have been shown to repress transcription through epigenetic modification of chromatin structure. To gain insight into the role of Polycomb in early development, we have identified PRC1 and PRC2 target genes in mouse embryonic stem (ES) cells using genome-scale location analysis. We found that PRC2 occupies many genes that encode key regulators of development including those encoding transcription factors and components of signaling pathways. These genes are repressed and contain nucleosomes methylated at lysine 27 on histone H3. The majority of PRC2 bound and methylated target genes are co-occupied by PRC1 indicating that these complexes function at a similar set of genes in ES cells. Lack of PRC1 or PRC2 subunits in ES cells results in derepression of target genes and loss of pluripotency. These results provide insight into how PcG proteins contribute to the maintenance of stem cell identity.
2006-05-09 | E-WMIT-12 | biostudies-arrayexpress
Project description:Cohesin is crucial for proper chromosome segregation, but also regulates gene transcription and organism development by poorly understood mechanisms. We find that in Drosophila, cohesin functionally interacts with Polycomb group (PcG) silencing proteins at both silenced and active genes. Cohesin unexpectedly facilitates binding of Polycomb Repressive Complex 1 (PRC1) to many active genes. In contrast, cohesin and PRC1 binding are mutually antagonistic at silenced genes. PRC1 depletion decreases phosphorylated RNA polymerase and mRNA at many active genes, but increases them at silenced genes. Cohesin also facilitates long-range interactions between Polycomb Response Elements in the invected-engrailed gene complex where it represses transcription. These multiple distinct cohesin-PcG interactions reveal a previously unrecognized role for PRC1 in facilitating productive gene transcription, and provide new insights into how cohesin and PRC1 control development. We extracted RNA from control and Ph RNAi-treated BG3 cells and measured changes in gene expression following Ph dose depletion by hybridization to Affymetrix arrays. We also extracted RNA from wild-type wing imaginal disc and measured control wing disc expression levels by hybridization to Affymetrix arrays.
2013-04-25 | E-GEOD-42105 | biostudies-arrayexpress
Project description:Polycomb complexes establish chromatin modifications for maintaining gene repression and are essential for embryonic development in mice. Here we use pluripotent embryonic stem (ES) cells to demonstrate an unexpected redundancy between Polycomb repressive complex 1 (PRC1) and PRC2 during the formation of differentiated cells. ES cells lacking the function of either PRC1 or PRC2 can differentiate into cells of the three germ layers, whereas simultaneous loss of PRC1 and PRC2 abrogates differentiation. On the molecular level the differentiation defect is caused by the derepression of a set of genes that is redundantly repressed by PRC1 and PRC2 in ES cells. Furthermore, we find that genomic repeats are Polycomb targets and show that in the absence of Polycomb complexes endogenous MLV elements can mobilize. This indicates a contribution of the PcG system to the defense against parasitic DNA and a potential role of genomic repeats in Polycomb mediated gene regulation. RNA from wt and PcG mutant ES cells was extracted using Trizol and hybridized to an Affymetrix Mouse 430_2.0 chip. Labeling, hybridization and primary data analysis were performed by a commercial provider (Atlas Biolabs, Berlin). Before RNA extraction, the undifferentiated ES cell state was confirmed by colony morphology. All genotypes were hybridized in biological triplicates.
2009-11-30 | E-GEOD-19076 | biostudies-arrayexpress
Project description:Cohesin is crucial for proper chromosome segregation, but also regulates gene transcription and organism development by poorly understood mechanisms. We find that in Drosophila, cohesin functionally interacts with Polycomb group (PcG) silencing proteins at both silenced and active genes. Cohesin unexpectedly facilitates binding of Polycomb Repressive Complex 1 (PRC1) to many active genes. In contrast, cohesin and PRC1 binding are mutually antagonistic at silenced genes. PRC1 depletion decreases phosphorylated RNA polymerase and mRNA at many active genes, but increases them at silenced genes. Cohesin also facilitates long-range interactions between Polycomb Response Elements in the invected-engrailed gene complex where it represses transcription. These multiple distinct cohesin-PcG interactions reveal a previously unrecognized role for PRC1 in facilitating productive gene transcription, and provide new insights into how cohesin and PRC1 control development. ChIP-chip of cohesin, Polycomb group proteins, and RNA Polymerase II was performed in whole wing imaginal discs in developing wing imaginal disc, revealing that cohesin and Polycomb Repressive Complex 1 (PRC1) components co-bind with cohesin proteins at active genes. We then measured cohesin, Pc, and H3K27me3 separately in anterior and posterior wing imaginal discs and compared their binding at the invected-engrailed complex, which is silenced in the anterior disc, and expressed in its posterior. This confirmed that cohesin and PRC1 (Pc) co-bind at inv-en in its active state, and H3K27me3 and PRC1 (Pc) co-target inv-en in its silenced state. Comparison of binding between Pc-RJ and Pc-VP was performed, and revealed that Pc-VP is subject to epitope masking specifically at active genes. Finally, we measured cohesin and Pc binding in Drosophila ML-DmBG3-c2 cells, and found that they co-bind active genes in this cell line in as well as in wing imaginal discs. ChIP-chip of cohesin subunit Rad21 after PRC1 component Ph depletion, and ChIP-chip of PRC1 subunit Pc after Rad21 RNAi depletion, revealed that these two complexes affect one another's binding. Finally, ChIP-chip of Rpb3 (representing total Pol II) and Ser2P-Pol II (representing elongating Pol II) after PRC1 component Ph depletion revealed that PRC1 restrains entry of non-phosphorylated Pol II into gene bodies.
2013-04-25 | E-GEOD-42104 | biostudies-arrayexpress
Project description:The transcriptional repressors Polycomb Repressive Complex 1 (PRC1) and PRC2 are required to maintain cell fate during embryonic development. PRC1 and PRC2 catalyse distinct histone modifications, establishing repressive chromatin at shared targets. Loss of PRC1, but not PRC2, from mouse embryonic stem cells (mESCs) triggers exit from pluripotency. How PRC2 and PRC1, which consists of distinct “variant PRC1” (vPRC1) and “canonical PRC1” (cPRC1) complexes, cooperate to silence genes and support mESC self-renewal is unclear. Here, we report that independent pathways composed of vPRC1 and cPRC1/PRC2 repress shared target genes. Individual loss of vPRC1, cPRC1, or PRC2 disrupts only one pathway and does not impair mESC pluripotency. However, loss of both pathways leads to mESC differentiation and activation of a subset of poised target genes co-occupied by relatively high levels of PRC1/PRC2. Thus, parallel pathways explains the differential requirements for PRC1 and PRC2, and provides robust silencing of poised, lineage-specific genes.
2020-04-02 | GSE136584 | GEO
Project description:Polycomb complexes establish chromatin modifications for maintaining gene repression and are essential for embryonic development in mice. Here we use pluripotent embryonic stem (ES) cells to demonstrate an unexpected redundancy between Polycomb repressive complex 1 (PRC1) and PRC2 during the formation of differentiated cells. ES cells lacking the function of either PRC1 or PRC2 can differentiate into cells of the three germ layers, whereas simultaneous loss of PRC1 and PRC2 abrogates differentiation. On the molecular level the differentiation defect is caused by the derepression of a set of genes that is redundantly repressed by PRC1 and PRC2 in ES cells. Furthermore, we find that genomic repeats are Polycomb targets and show that in the absence of Polycomb complexes endogenous MLV elements can mobilize. This indicates a contribution of the PcG system to the defense against parasitic DNA and a potential role of genomic repeats in Polycomb mediated gene regulation.
2009-12-01 | GSE19076 | GEO
Project description:Polycomb Repressive Complexes 1 and 2 (PRC1 and PRC2) are histone-modifying and -binding complexes that mediate the formation of facultative heterochromatin and are required for silencing of developmental genes and maintenance of cell fate. Multiple pathways of RNA decay work together to establish and maintain heterochromatin in fission yeast, including a recently identified role for a conserved RNA degradation complex called the rixosome or RIX1 complex. Whether RNA degradation also plays a role in the stability of mammalian heterochromatin remains unknown. Here we show that the rixosome contributes to silencing of many Polycomb targets in human cells. The rixosome associates with human PRC complexes and is enriched at promoters of Polycomb target genes. Importantly, depletion of either the rixosome or Polycomb results in accumulation of paused and elongating RNA polymerase at Polycomb-target genes. We identify point mutations in the RING1B subunit of PRC1 that disrupt the interaction between PRC1 and the rixosome and result in diminished silencing, suggesting that direct recruitment of the rixosome to chromatin is required for silencing. Finally, we show that the RNA kinase activity of the rixosome and the XRN2 exoribonuclease, which degrades RNAs with 5’ mono-phosphate groups generated by the rixosome, are required for silencing. Our findings suggest that rixosome-mediated degradation of nascent RNA is conserved from fission yeast to human, although in human cells the rixosome degrades RNA in facultative rather than constitutive heterochromatin.
2022-01-19 | PXD027966 | Pride
Project description:Polycomb Repressive Complexes 1 and 2 (PRC1 and PRC2) are histone-modifying and -binding complexes that mediate the formation of facultative heterochromatin and are required for silencing of developmental genes and maintenance of cell fate. Multiple pathways of RNA decay work together to establish and maintain heterochromatin in fission yeast, including a recently identified role for a conserved RNA degradation complex called the rixosome or RIX1 complex. Whether RNA degradation also plays a role in the stability of mammalian heterochromatin remains unknown. Here we show that the rixosome contributes to silencing of many Polycomb targets in human cells. The rixosome associates with human PRC complexes and is enriched at promoters of Polycomb target genes. Importantly, depletion of either the rixosome or Polycomb results in accumulation of paused and elongating RNA polymerase at Polycomb-target genes. We identify point mutations in the RING1B subunit of PRC1 that disrupt the interaction between PRC1 and the rixosome and result in diminished silencing, suggesting that direct recruitment of the rixosome to chromatin is required for silencing. Finally, we show that the RNA kinase activity of the rixosome and the XRN2 exoribonuclease, which degrades RNAs with 5’ mono-phosphate groups generated by the rixosome, are required for silencing. Our findings suggest that rixosome-mediated degradation of nascent RNA is conserved from fission yeast to human, although in human cells the rixosome degrades RNA in facultative rather than constitutive heterochromatin.
2022-01-20 | PXD029403 | Pride