RBYP stimulates PRC1 to shape chromatin-based communication between polycomb repressive complexes [ChIP-seq]
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ABSTRACT: Polycomb Repressive Complexes (PRC), and their chromatin-modifying activities, are essential for the correct regulation of gene expression during cellular differentiation and development. Although their role in transcriptional repression is well described, a detailed molecular understanding of their complex assembly and enzymatic activity has been lacking. We therefore set out to characterize the relationship between PRC1 complex composition and its ability to catalyse H2AK119ub1 for one of the most abundant PRC1 complexes in embryonic stem cells, PCGF1-PRC1. Biochemical reconstitution of the PCGF1-PRC1 complex revealed that RYBP/YAF2 was essential for robust enzymatic activity of the complex. Using calibrated ChIP-seq for H2AK119ub1, we identify that RYBP-dependent PRC1 activity has a widespread role in shaping H2AK119ub1 levels genome-wide in mouse embryonic stem cells. Furthermore, these H2AK119ub1 levels stimulate PRC2 activity as part of an activity-based feedback loop, which we demonstrate is required for maintenance of transcriptional repression. Together, these observations uncover complex-based principles for PRC1 assembly and activity, and further our understanding of Polycomb domain function.
Project description:Polycomb Repressive Complexes (PRC), and their chromatin-modifying activities, are essential for the correct regulation of gene expression during cellular differentiation and development. Although their role in transcriptional repression is well described, a detailed molecular understanding of their complex assembly and enzymatic activity has been lacking. We therefore set out to characterize the relationship between PRC1 complex composition and its ability to catalyse H2AK119ub1 for one of the most abundant PRC1 complexes in embryonic stem cells, PCGF1-PRC1. Biochemical reconstitution of the PCGF1-PRC1 complex revealed that RYBP/YAF2 was essential for robust enzymatic activity of the complex. Using calibrated ChIP-seq for H2AK119ub1, we identify that RYBP-dependent PRC1 activity has a widespread role in shaping H2AK119ub1 levels genome-wide in mouse embryonic stem cells. Furthermore, these H2AK119ub1 levels stimulate PRC2 activity as part of an activity-based feedback loop, which we demonstrate is required for maintenance of transcriptional repression. Together, these observations uncover complex-based principles for PRC1 assembly and activity, and further our understanding of Polycomb domain function. This SuperSeries is composed of the SubSeries listed below.
Project description:Polycomb Repressive Complexes (PRC), and their chromatin-modifying activities, are essential for the correct regulation of gene expression during cellular differentiation and development. Although their role in transcriptional repression is well described, a detailed molecular understanding of their complex assembly and enzymatic activity has been lacking. We therefore set out to characterize the relationship between PRC1 complex composition and its ability to catalyse H2AK119ub1 for one of the most abundant PRC1 complexes in embryonic stem cells, PCGF1-PRC1. Biochemical reconstitution of the PCGF1-PRC1 complex revealed that RYBP/YAF2 was essential for robust enzymatic activity of the complex. Using calibrated ChIP-seq for H2AK119ub1, we identify that RYBP-dependent PRC1 activity has a widespread role in shaping H2AK119ub1 levels genome-wide in mouse embryonic stem cells. Furthermore, these H2AK119ub1 levels stimulate PRC2 activity as part of an activity-based feedback loop, which we demonstrate is required for maintenance of transcriptional repression. Together, these observations uncover complex-based principles for PRC1 assembly and activity, and further our understanding of Polycomb domain function.
Project description:Polycomb Repressive Complexes (PRC), and their chromatin-modifying activities, are essential for the correct regulation of gene expression during cellular differentiation and development. Although their role in transcriptional repression is well described, a detailed molecular understanding of their complex assembly and enzymatic activity has been lacking. We therefore set out to characterize the relationship between PRC1 complex composition and its ability to catalyse H2AK119ub1 for one of the most abundant PRC1 complexes in embryonic stem cells, PCGF1-PRC1. Biochemical reconstitution of the PCGF1-PRC1 complex revealed that RYBP/YAF2 was essential for robust enzymatic activity of the complex. Using calibrated ChIP-seq for H2AK119ub1, we identify that RYBP-dependent PRC1 activity has a widespread role in shaping H2AK119ub1 levels genome-wide in mouse embryonic stem cells. Furthermore, these H2AK119ub1 levels stimulate PRC2 activity as part of an activity-based feedback loop, which we demonstrate is required for maintenance of transcriptional repression. Together, these observations uncover complex-based principles for PRC1 assembly and activity, and further our understanding of Polycomb domain function.
Project description:Polycomb repressive complexes-1 and -2 (PRC1 and 2), silence developmental genes in spatiotemporally regulated manner during metazoan embryogenesis. How PcG proteins contribute to down-regulation of target genes upon differentiation, however, remains elusive. Here, by differentiating embryonic stem cells into embryoid bodies, we reveal a crucial role of a PCGF1 (Polycomb group RING finger protein 1)-containing variant PRC1 complex (PCGF1-PRC1) to facilitate induced down-regulation of a group of genes. Binding of PCGF1-PRC1 results in down-regulation of transcriptional activity, followed by Histone H2AK119 mono-ubiquitination (H2AK119ub1) and subsequent recruitment of PRC2, to initiate PcG-repressive domain formation. Based on these findings, we propose that PCGF1-PRC1 mediates establishment of PcG-repressive domains at target genes during differentiation.
Project description:Polycomb repressive complexes-1 and -2 (PRC1 and 2), silence developmental genes in spatiotemporally regulated manner during metazoan embryogenesis. How PcG proteins contribute to down-regulation of target genes upon differentiation, however, remains elusive. Here, by differentiating embryonic stem cells into embryoid bodies, we reveal a crucial role of a PCGF1 (Polycomb group RING finger protein 1)-containing variant PRC1 complex (PCGF1-PRC1) to facilitate induced down-regulation of a group of genes. Binding of PCGF1-PRC1 results in down-regulation of transcriptional activity, followed by Histone H2AK119 mono-ubiquitination (H2AK119ub1) and subsequent recruitment of PRC2, to initiate PcG-repressive domain formation. Based on these findings, we propose that PCGF1-PRC1 mediates establishment of PcG-repressive domains at target genes during differentiation.
Project description:Polycomb repressive complexes-1 and -2 (PRC1 and 2), silence developmental genes in spatiotemporally regulated manner during metazoan embryogenesis. How PcG proteins contribute to down-regulation of target genes upon differentiation, however, remains elusive. Here, by differentiating embryonic stem cells into embryoid bodies, we reveal a crucial role of a PCGF1 (Polycomb group RING finger protein 1)-containing variant PRC1 complex (PCGF1-PRC1) to facilitate induced down-regulation of a group of genes. Binding of PCGF1-PRC1 results in down-regulation of transcriptional activity, followed by Histone H2AK119 mono-ubiquitination (H2AK119ub1) and subsequent recruitment of PRC2, to initiate PcG-repressive domain formation. Based on these findings, we propose that PCGF1-PRC1 mediates establishment of PcG-repressive domains at target genes during differentiation.
Project description:The heterogeneous nature of mammalian PRC1 complexes has hindered our understanding of their biological functions. Here, we present a comprehensive proteomic and genomic analysis that uncovered six major groups of PRC1 complexes each containing a distinct PCGF subunit, a RING1A/B ubiquitin ligase, and a unique set of associated polypeptides. These PRC1 complexes differ in their genomic localization and only a small subset co-localize with H3K27me3. Further biochemical dissection revealed that the six PCGFM-bM-^@M-^SRING1A/B combinations form multiple complexes through association with RYBP or its homolog YAF2, which prevents the incorporation of other canonical PRC1 subunits such as CBX, PHC and SCM. Although both RYBP/YAF2- and CBX/PHC/SCM-containing complexes compact chromatin, only RYBP stimulates the activity of RING1B toward H2AK119ub1, suggesting a central role in PRC1 function. Knockdown of RYBP in ES cells compromised their ability to form embryoid bodies, likely because of defects in cell proliferation and maintenance of H2AK119ub1 level. ChIP-seq experiments of different PRC1 components were performed either on HA-tagged transgenic stable 293T-REx lines or on endogenous subunits using specific antibodies.
Project description:The chromatin modifying activities inherent to polycomb repressive complexes PRC1 and PRC2 play an essential role in gene regulation, cellular differentiation, and development. However, the mechanisms by which these complexes recognize their target sites and function together to form repressive chromatin domains remain poorly understood. Recruitment of PRC1 to target sites has been proposed to occur through a hierarchical process, dependent on the prior nucleation of PRC2 and placement of H3K27me3. Here, using a de novo targeting assay in mouse embryonic stem cells we unexpectedly discover that PRC1-dependent H2AK119ub1 leads to the recruitment of PRC2 and H3K27me3 to effectively initiate a polycomb domain. Genetic ablation of catalytic subunit of the PRC1 complex (RINGA/B) and ChIP-seq analysis of PRC1 and PRC2 components confirmed genome-wide decreases in PRC2 occupancy and H3K27me3 levels at PRC target sites. This activity is restricted to variant PRC1 complexes and genetic ablation experiments reveal that targeting of the variant PCGF1/PRC1 complex by KDM2B to CpG islands is required for polycomb domain formation and normal development. Together these observations provide a surprising new PRC1-dependent logic for PRC2 occupancy and polycomb domain formation. RING1A-/-;RING1Bfl/fl ES cells were treated with 800M-BM-5M tamoxifen for 48hours and compared to untreated control cells by ChIP-seq for RING1B, SUZ12, EZH2 and H3K27me3.
Project description:We assessed the levels of the PRC1 Polycomb mark, RYBP, H2AK119Ub1, and the PRC2 Polycomb mark, H3K27me3, considering the extensive crosstalk between PRC1 and PRC2 activities.
Project description:Polycomb repressive complexes 1 and 2 (PRC1 and 2) repress lineage inappropriate genes during development to maintain proper cellular identities. To reveal the function of a variant PRC1 containing PCGF1 (PCGF1-PRC1), we prepared PCGF1 interacting proteins by immunoprecipitation and characterized them by LC-MS/MS.