Project description:The core Polycomb Repressor Complex 2 (PRC2) is composed of Ezh1/2, Suz12, Eed and is responsible for mediating both H3K27me2 and H3K27me3. However, the mechanisms by which PRC2 demarcates these two repressive modifications in the genome are unknown. In a functional screen, we identified the H3K36 dimethyltransferase Nsd1 as a modulator of PRC2-mediated di- and trimethylation of H3K27. ChIP-Seq analysis following the depletion of Nsd1 revealed a global reduction in H3K36me2 and an increase in H3K27me3 at sites previously marked by H3K27me2. We show that the H3K36me2 at H3K27me2 marks co-occupy regions and provide evidence that the presence of H3K36me2 functions to restrict the spatial distribution of Polycomb mediated H3K27me3 domains.
Project description:The core Polycomb Repressor Complex 2 (PRC2) is composed of Ezh1/2, Suz12, Eed and is responsible for mediating both H3K27me2 and H3K27me3. However, the mechanisms by which PRC2 demarcates these two repressive modifications in the genome are unknown. In a functional screen, we identified the H3K36 dimethyltransferase Nsd1 as a modulator of PRC2-mediated di- and trimethylation of H3K27. ChIP-Seq analysis following the depletion of Nsd1 revealed a global reduction in H3K36me2 and an increase in H3K27me3 at sites previously marked by H3K27me2. We show that the H3K36me2 at H3K27me2 marks co-occupy regions and provide evidence that the presence of H3K36me2 functions to restrict the spatial distribution of Polycomb mediated H3K27me3 domains.
Project description:Polycomb repressive complex 2 (PRC2) is a chromatin-modifying enzyme that catalyzes the methylation of lysine 27 on histone H3 (H3K27me1/2/3). This complex maintains the gene expression profiles in different cell types and plays an essential role in normal organismal development. The mechanisms by which PRC2 targets specific chromatin regions remain unclear. To address this question, we focused on the post-translational modifications (PTMs) of PRC2 subunits. Here we show EED, a core component of PRC2, is acetylated by acetyltransferase CBP/P300 at lysine 19 (K19). The acetylation of EED at K19 (EED-K19ac) reduces the binding affinity between PRC2 and native nucleosomes, causing PRC2 to leave its chromatin targets in vivo. Genome-wide location analysis (ChIP-seq) reveals that K19-acetylated EED preferentially accumulates at highly transcribed genes with low EZH2 and H3K27me3 levels. Using CRISPR/Cas9 technology, we generated mouse embryonic stem cells (mESCs) carrying non-acetylated EED mimic (EED-K19R) and showed acetylation of EED at K19 is necessary for mESC differentiation. In summary, our study reveals a novel mechanism that allows intracellular signalling pathways to regulate cellular differentiation and cell fate decisions by controlling the genomic targeting of PRC2 through acetylating EED.
Project description:Polycomb repressive complex 2 (PRC2) is a chromatin-modifying enzyme that catalyzes the methylation of lysine 27 on histone H3 (H3K27me1/2/3). This complex maintains the gene expression profiles in different cell types and plays an essential role in normal organismal development. The mechanisms by which PRC2 targets specific chromatin regions remain unclear. To address this question, we focused on the post-translational modifications (PTMs) of PRC2 subunits. Here we show EED, a core component of PRC2, is acetylated by acetyltransferase CBP/P300 at lysine 19 (K19). The acetylation of EED at K19 (EED-K19ac) reduces the binding affinity between PRC2 and native nucleosomes, causing PRC2 to leave its chromatin targets in vivo. Genome-wide location analysis (ChIP-seq) reveals that K19-acetylated EED preferentially accumulates at highly transcribed genes with low EZH2 and H3K27me3 levels. Using CRISPR/Cas9 technology, we generated mouse embryonic stem cells (mESCs) carrying non-acetylated EED mimic (EED-K19R) and showed acetylation of EED at K19 is necessary for mESC differentiation. In summary, our study reveals a novel mechanism that allows intracellular signalling pathways to regulate cellular differentiation and cell fate decisions by controlling the genomic targeting of PRC2 through acetylating EED.
Project description:We report here the genome wide mapping of histone PTMs and chromatin bound factors in pluripotent control and H3K27R base edited mouse embryonic stem cells (mESCs) and epiblast-like cells (EpiLCs) using ChIP-Seq technology. We have deposited results from chromatin immunoprecipitations done using antibodies against Rpb1 (Pol-II), Med1,H3.3, H3K27me1, H3K27me2, H3K27me3 and H3K27ac (rabbit and mouse monoclonal antibodies). We show the loss of all H3K27 from H3.1/2/3 results in loss of associated K27 methylation and acetylation as expected. In such cells, there are only modest changes to MED1 or RNA Pol-II binding or activity that correlate with transcriptional status, suggesting that H3K27ac is not required to initiate or maintain transcription of genes, while loss of H3K27me3 associates with derepression of Polycomb target genes.
Project description:These data include the genome wide location of different histone modifications by ChIP sequencing in mouse ES cells, and RNA Seq data generated from wild type and EED KO mouse ES cells and knocked down for unrelated protein and Setd2 protein. ChIP-Seq: Immuno-precipitation of formaldehyde cross-linked chromatin prepared from wild type mouse E14 ES cells, wild type E36 ES cells, EED KO E36 ES cells, wild type Embryoid bodies (Ebs), EED KO Embryoid bodies (Ebs EED KO) using specific antibody against different histone modifications. RNA-Seq: Total RNA extracted from wild type E36 ES cells, EED KO E36 ES cells, wild type E36 Embryoid bodies (Ebs), EED KO Embryoid bodies (Ebs EED KO), E14 Ctrl KD, E14 Setd2 KD.
Project description:Polycomb Repressive Complex 2 (PRC2) plays an essential role in development by catalysing trimethylation of histone H3 lysine 27 (H3K27me3), resulting in gene repression. PRC2 consists of two sub-complexes, PRC2.1 and PRC2.2, in which the PRC2 core associates with distinct ancillary subunits such as MTF2 and JARID2, respectively. Both MTF2, present in PRC2.1, and JARID2, present in PRC2.2, play a role in core PRC2 recruitment to target genes in mouse embryonic stem cells (mESCs). However, it remains unclear how these distinct sub-complexes cooperate to establish H3K27me3 domains. Here, we combine a range of Polycomb mutant mESCs with chemical inhibition of PRC2 catalytic activity, to systematically dissect their relative contributions to PRC2 binding to target loci. We find that PRC2.1 and PRC2.2 mediate two distinct paths for recruitment, with mutually reinforced binding. Part of the cross-talk between PRC2.1 and PRC2.2 occurs via their catalytic product H3K27me3, which is bound by the PRC2 core-subunit EED, thereby mediating a positive feedback. Strikingly, removal of either JARID2 or H3K27me3 only has a minor effect on PRC2 recruitment, whereas their combined ablation largely attenuates PRC2 recruitment. This strongly suggests an unexpected redundancy between JARID2 and EED-H3K27me3-mediated recruitment of PRC2. Furthermore, we demonstrate that all core PRC2 recruitment occurs through the combined action of MTF2-mediated recruitment of PRC2.1 to DNA and PRC1-mediated recruitment of JARID2-containing PRC2.2. Both axes of binding are supported by EED-H3K27me3 positive feedback, but to a different degree. Finally, we provide evidence that PRC1 and PRC2 mutually reinforce reciprocal binding. Together, these data disentangle the interdependent and cooperative interactions between Polycomb complexes that are important to establish Polycomb repression at target sites.
Project description:Polycomb Repressive Complex 2 (PRC2) plays an essential role in development by catalysing trimethylation of histone H3 lysine 27 (H3K27me3), resulting in gene repression. PRC2 consists of two sub-complexes, PRC2.1 and PRC2.2, in which the PRC2 core associates with distinct ancillary subunits such as MTF2 and JARID2, respectively. Both MTF2, present in PRC2.1, and JARID2, present in PRC2.2, play a role in core PRC2 recruitment to target genes in mouse embryonic stem cells (mESCs). However, it remains unclear how these distinct sub-complexes cooperate to establish H3K27me3 domains. Here, we combine a range of Polycomb mutant mESCs with chemical inhibition of PRC2 catalytic activity, to systematically dissect their relative contributions to PRC2 binding to target loci. We find that PRC2.1 and PRC2.2 mediate two distinct paths for recruitment, with mutually reinforced binding. Part of the cross-talk between PRC2.1 and PRC2.2 occurs via their catalytic product H3K27me3, which is bound by the PRC2 core-subunit EED, thereby mediating a positive feedback. Strikingly, removal of either JARID2 or H3K27me3 only has a minor effect on PRC2 recruitment, whereas their combined ablation largely attenuates PRC2 recruitment. This strongly suggests an unexpected redundancy between JARID2 and EED-H3K27me3-mediated recruitment of PRC2. Furthermore, we demonstrate that all core PRC2 recruitment occurs through the combined action of MTF2-mediated recruitment of PRC2.1 to DNA and PRC1-mediated recruitment of JARID2-containing PRC2.2. Both axes of binding are supported by EED-H3K27me3 positive feedback, but to a different degree. Finally, we provide evidence that PRC1 and PRC2 mutually reinforce reciprocal binding. Together, these data disentangle the interdependent and cooperative interactions between Polycomb complexes that are important to establish Polycomb repression at target sites.
Project description:Eed (embryonic ectoderm development) is a core component of the Polycomb Repressive Complex 2 (PRC2) which catalyzes the methylation of histone H3 lysine 27 (H3K27). Trimethylated H3K27 (H3K27me3) can act as a signal for PRC1 recruitment in the process of gene silencing and chromatin condensation. Previous studies with Eed KO ESCs revealed a failure to down-regulate a limited list of pluripotency factors in differentiating ESCs. Our aim was to analyze the consequences of Eed KO for ESC differentiation. To this end we first analyzed ESC differentiation in the absence of Eed and employed in silico data to assess pluripotency gene expression and H3K27me3 patterns. We linked these data to expression analyses of wildtype and Eed KO ESCs. We observed that in wildtype ESCs a subset of pluripotency genes including Oct4, Nanog, Sox2 and Oct4 target genes progressively gain H3K27me3 during differentiation. These genes remain expressed in differentiating Eed KO ESCs. This suggests that the deregulation of a limited set of pluripotency factors impedes ESC differentiation. Global analyses of H3K27me3 and Oct4 ChIP-seq data indicate that in ESCs the binding of Oct4 to promoter regions is not a general predictor for PRC2-mediated silencing during differentiation. However, motif analyses suggest a binding of Oct4 together with Sox2 and Nanog at promoters of genes that are PRC2-dependently silenced during differentiation. In summary, our data further characterize Eed function in ESCs by showing that Eed/PRC2 is essential for the onset of ESC differentiation. RNAs obtained from undifferentiated (d0) wild type and Eed KO ESCs and from day 3 (d3) and day 7 (d7) respective Ebs were subjected to Affymetrix Mouse Gene 1.0 ST Array. 24 samples in total.
Project description:The established hierarchical model explaining co-occupancy of Polycomb repressor complexes 1 and 2 (PRC 1 and 2) at target loci proposes that the chromodomain of the polycomb protein, a core PRC1 subunit, recognises the H3K27me3 histone modification catalysed by PRC2. We used chromatin immunoprecipitation to analyse PRC1 occupancy at target loci in Eed-/- mouse embryonic stem cells (ESCs) that lack H3K27me3. Occupancy of the core PRC1 proteins Ring1B and Mel18 was strongly reduced, consistent with the hierarchical model. However, levels of H2A ubiquitylation (H2AK119u1), the histone modification catalysed by PRC1, were similar to wild-type cells, suggesting PRC1 recruitment is independent of H3K27me3. ChIP-sequencing analysis of Ring1B occupancy genome wide substantiated this conclusion, demonstrating significant Ring1B levels at polycomb target loci in Eed-/- ESCs. Thus PRC1 and PRC2 are recruited independently to sites that they co-occupy. We conclude that the primary function of H3K27me3 is to increase the residency of PRC1 at target loci and thereby to contribute to the stability of PRC1 mediated silencing. Examination of Ring1B binding in WT, Eed ko and Input of ESCs Examination of CBX7 in WT and Eed ko of ESCs