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Arabidopsis Polycomb Repressive Complex 2 binding sites contain putative GAGA factor binding motifs within coding regions of genes

ABSTRACT: Background. Polycomb Repressive Complex 2 (PRC2) is an essential regulator of gene expression that maintains genes in a repressed state by marking chromatin with trimethylated Histone H3 lysine 27 (H3K27me3). In Arabidopsis, loss of PRC2 function leads to pleiotropic effects on growth and development thought to be due to ectopic expression of seed and embryo-specific genes. While there is some understanding of the mechanisms by which specific genes are targeted by PRC2 in animal systems, it is still not clear how PRC2 is recruited to specific regions of plant genomes.Results. We used ChIP-seq to determine the genome-wide distribution of hemagglutinin (HA)-tagged FERTLIZATION INDEPENDENT ENDOSPERM (FIE-HA), the Extra Sex Combs homolog protein present in all Arabidopsis PRC2 complexes. We found that the FIE-HA binding sites co-locate with a subset of the H3K27me3 sites in the genome and the associated genes were more likely to be de-repressed in mutants of PRC2 components. The FIE-HA binding sites are enriched for three sequence motifs including a putative GAGA factor binding site that is also found in Drosophila Polycomb Response Elements (PREs).Conclusions. Our results suggest that PRC2 binding sites in plant genomes share some sequence features with Drosophila PREs. However, RNA was extracted from intermediate phenotype siFIE plants, clf-7 swn-28 and Col using Qiagen Plant RNeasy mini kit. For each sample, three pools of 10-12 plants were used. The siFIE plants were analysed for FIE mRNA by RT-qPCR; the maximum level of FIE mRNA was found to be 10% of wildtype.

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Diana Buzas

PROVIDER: E-GEOD-48857 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Arabidopsis Polycomb Repressive Complex 2 binding sites contain putative GAGA factor binding motifs within coding regions of genes

Project description:Background. Polycomb Repressive Complex 2 (PRC2) is an essential regulator of gene expression that maintains genes in a repressed state by marking chromatin with trimethylated Histone H3 lysine 27 (H3K27me3). In Arabidopsis, loss of PRC2 function leads to pleiotropic effects on growth and development thought to be due to ectopic expression of seed and embryo-specific genes. While there is some understanding of the mechanisms by which specific genes are targeted by PRC2 in animal systems, it is still not clear how PRC2 is recruited to specific regions of plant genomes.Results. We used ChIP-seq to determine the genome-wide distribution of hemagglutinin (HA)-tagged FERTLIZATION INDEPENDENT ENDOSPERM (FIE-HA), the Extra Sex Combs homolog protein present in all Arabidopsis PRC2 complexes. We found that the FIE-HA binding sites co-locate with a subset of the H3K27me3 sites in the genome and the associated genes were more likely to be de-repressed in mutants of PRC2 components. The FIE-HA binding sites are enriched for three sequence motifs including a putative GAGA factor binding site that is also found in Drosophila Polycomb Response Elements (PREs).Conclusions. Our results suggest that PRC2 binding sites in plant genomes share some sequence features with Drosophila PREs. However,

2013-09-01 | GSE48857 | GEO

upregulation of transcripts in the absence of prc2 repressory complex-Dissecting the role of the polycomb repressor

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2010-12-01 | E-GEOD-19851 | biostudies-arrayexpress

EMF1 and PRC2 Cooperate to Repress Key Regulators of Arabidopsis Development

Project description:EMBRYONIC FLOWER1 (EMF1) is a plant specific gene crucial to Arabidopsis vegetative development. Loss of function mutants in the EMF1 gene mimic the phenotype caused by mutations in Polycomb Group protein (PcG) genes, which encode epigenetic repressors that regulate many aspects of eukaryotic development. In Arabidopsis, Polycomb Repressor Complex 2 (PRC2), made of PcG proteins, catalyzes trimethylation of lysine 27 on histone H3 (H3K27me3) and PRC1-like proteins catalyze H2AK119 ubiquitination. Despite functional similarity to PcG proteins, EMF1 lacks sequence homology with known PcG proteins; thus its role in the PcG mechanism is unclear. To study the EMF1 functions and its mechanism of action, we performed genome-wide mapping of EMF1 binding and H3K27me3 modification sites in Arabidopsis seedlings. The EMF1 binding pattern is similar to that of H3K27me3 modification on the chromosomal and genic level. ChIPOTLe peak finding and clustering analyses both show that the highly trimethylated genes also have high enrichment level of EMF1 binding, termed EMF1_K27 genes. EMF1 interacts with regulatory genes, which are silenced to allow vegetative growth, and with genes specifying differentiated cell fates during vegetative development. H3K27me3 marks not only these genes but also some genes that are involved in endosperm development and maternal effects. Transcriptome analysis, coupled with the H3K27me3 pattern, of EMF1_K27 genes in emf1 and PRC2 mutants showed that EMF1 represses gene activities via diverse mechanisms and plays a novel role in the PcG mechanism. All experiments were done using two channels per chip, comparing DNA associated with immunoprecipitated EMF1 to control genomic DNA, DNA associated with immunoprecipitated histone H3 methylated at lysine 27 to control genomic DNA, or total RNA (converted to cDNA) to control genomic DNA. Two or three replicates per experiment are included.

2012-03-01 | E-GEOD-34689 | biostudies-arrayexpress

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Project description:Using Western blot, we found the level of H3K27me3, but not H3K4me3, H3K9me2 and H3K36me3, was specifically reduced in the tor-es mutant. To gain a genome-wide view of the effects of TOR activity on H3K27me3 distribution, we performed quantitative chromatin immunoprecipitation with an exogenous reference genome (ChIP-Rx) followed by deep-sequencing. We find a global reduction of H3K27me3 occupancy in tor-es, whereas the H3K9me2 level was largely unaffected. These results suggest that TOR may be a specific and direct regulator of global deposition of H3K27me3. To investigate the function of TOR phosphorylation of FIE, we complemented the heterozygous fie/+ plants with GFP-FIE or the phosphorylation site mutant (SSTS/AAAA) under the control of the FIE promoter. To provide a parallel comparison with SSTS/AAAA/fie, we generated estradiol-inducible fie-amiR-es transgenic lines, that eliminated FIE protein. Quantitative ChIP-seq analyses revealed greatly reduced H3K27me3 levels across the genome in SSTS/AAAA and fie-amiR-es mutants. And transcriptome profiling by RNA-Seq was conducted to globally identify thousands of genes coordinately dysregulated in the shoots of SSTS/AAAA and fie-amiR-es plants. Furthermore, gene Ontology analysis of 986 TOR-FIE-PRC2 target genes revealed significant enrichment for transcription factors/regulators controlling a broad spectrum of developmental programs.

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