Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

H3K27me3 is not required for recruitment of Polycomb repressor complex 1 to target loci in mouse embryonic stem cells

ABSTRACT: 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

ORGANISM(S): Mus musculus

SUBMITTER: Stephen Taylor

PROVIDER: E-GEOD-23716 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

RYBP-PRC1 complexes mediate H2A ubiquitylation at polycomb target sites independently of PRC2 and H3K27me3.

Tavares Lígia L Dimitrova Emilia E Oxley David D Webster Judith J Poot Raymond R Demmers Jeroen J Bezstarosti Karel K Taylor Stephen S Ura Hiroki H Koide Hiroshi H Wutz Anton A Vidal Miguel M Elderkin Sarah S Brockdorff Neil N

Cell 20120209 4

Polycomb-repressive complex 1 (PRC1) has a central role in the regulation of heritable gene silencing during differentiation and development. PRC1 recruitment is generally attributed to interaction of the chromodomain of the core protein Polycomb with trimethyl histone H3K27 (H3K27me3), catalyzed by a second complex, PRC2. Unexpectedly we find that RING1B, the catalytic subunit of PRC1, and associated monoubiquitylation of histone H2A are targeted to closely overlapping sites in wild-type and PR ...[more]

PMID: 22325148

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Project description:Two distinct Polycomb complexes, PRC1 and PRC2, collaborate to maintain epigenetic repression of key developmental loci in embryonic stem cells (ESCs). PRC1 and PRC2 have histone modifying activities, catalyzing mono-ubiquitination of histone H2A (H2AK119u1) and trimethylation of H3 lysine 27 (H3K27me3) respectively. Compared to H3K27me3, localization and role of H2AK119ub1 is not fully understood in ESCs. Here we present genome-wide H2AK119u1 maps in ESCs and identify a group of genes at which H2AK119u1 is deposited in a Ring1-dependent manner. These genes are a distinctive subset of genes with H3K27me3 enrichment and are the central targets of Polycomb silencing that are required to maintain ESC identity. We further show that the H2A ubiquitination activity of PRC1 is dispensable for its target binding and its activity to compact chromatin at Hox loci, but is indispensable for efficient repression of target genes and thereby ESC maintenance. These data demonstrate that multiple effector mechanisms including H2A ubiquitination and chromatin compaction combine to mediate PRC1-dependent repression of genes that are crucial for the maintenance of ESC identity. Utilization of these diverse effector mechanisms might provide a means to maintain a repressive state that is robust yet highly responsive to developmental cues during ES cell self-renewal and differentiation. This SuperSeries is composed of the following subset Series: GSE38224: Expression data from Ring1A(-/-);Ring1B(fl/fl);R26::CreERT2 ES cells expressing either of mock, WT or mutant Ring1B construct before or after OHT treatment GSE38504: ChIP-on-chip analysis of Ring1B, Ring1A, H2AK119u1 and H3K27me3 in mouse ES cells Total RNAs were extracted from the respective ES cells, and were subjected to microarray analysis using Affymetrix GeneChip Mouse Genome 430A 2.0 arrays. ChIP on chip analysis was carried out using the Mouse Promoter ChIP-on-chip Microarray Set (G4490A, Agilent, Palo Alto, Calif., USA). MEFs were subjected to ChIP assay using various antibodies. Purified immunoprecipitated and input DNA was subjected to T7 RNA polymerase-based amplification. Labeling, hybridization and washing were carried out according to the Agilent mammalian ChIP-on-chip protocol (ver.9.0). Scanned images were quantified with Agilent Feature Extraction software under standard conditions.

Dataset Information

H3K27me3 is not required for recruitment of Polycomb repressor complex 1 to target loci in mouse embryonic stem cells

Publications

RYBP-PRC1 complexes mediate H2A ubiquitylation at polycomb target sites independently of PRC2 and H3K27me3.

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