Project description:The Polycomb repressive complex 2 (PRC2) catalyzes histone H3 Lys27 trimethylation (H3K27me3) to repress gene transcription in multicellular eukaryotes. Despite its importance in gene silencing and cellular differentiation, how PRC2 is recruited to target loci is still not fully understood. Here, we report genome-wide evidence for the recruitment of PRC2 by the transcriptional repressors VIVIPAROUS1/ABI3-LIKE1 (VAL1) and VAL2 in Arabidopsis thaliana. We show that the val1 val2 double mutant possesses somatic embryonic phenotypes and a transcriptome strikingly similar to those of the swn clf double mutant, which lacks the PRC2 catalytic subunits SWINGER (SWN) and CURLY LEAF (CLF). We further show that VAL1 and VAL2 physically interact with SWN and CLF in vivo. Genome-wide binding profiling demonstrated that they colocalize with SWN and CLF at PRC2 target loci. Loss of VAL1 and VAL2 significantly reduces SWN and CLF enrichment at PRC2 target loci and leads to a genome-wide redistribution of H3K27me3 that strongly affects transcription. Finally, we provide evidence that the VAL1/VAL2–RY regulatory system is largely independent of the TRB–Telobox and BPC1–GA/AZF1–Telobox modules for Polycomb silencing in plants. Taken together, our work demonstrates an extensive genome-wide interaction between VAL1/2 and PRC2 and provides mechanistic insights into the establishment of Polycomb silencing in plants.
Project description:PICKLE (PKL), a Chromodomain Helicase DNA binding domain type 3-type (CHD3) chromatin remodeler, noted for an embryonic structure called pickle root in primary root tip in pkl mutant, has been studied for decades. we obtained a comprehensive genome occupancy of PKL by Chromatin immunoprecipitation-sequencing (ChIP-seq), and found PKL co-occupy with the major repressors of seed maturation program, VIVIPAROUS1/ABI3-LIKE1/2 (VAL1/2) in genome. Furthermore, PKL physically interacts with VAL1/2 in vivo and phenotype and transcriptome data indicated that PKL and VAL1/2 function in a common pathway. Moreover, ChIP-seq and ChIP-qPCR results showed that VAL1/2 are necessary for the recruitment of PKL to co-target genes
Project description:Developing Arabidopsis seeds accumulate oils and seed storage proteins synthesized by the pathways of primary metabolism. Seed development and metabolism are positively regulated by transcription factors belonging to the LAFL regulatory network. The VAL gene family encodes repressors of the seed maturation program in germinating seeds, although they are also expressed during seed maturation. VAL1 functions as a repressor of seed metabolism, as val1 mutant seeds accumulated elevated levels of storage proteins compared to the wild type. Two VAL1 splice variants were identified through RNA sequencing analysis: a full-length and a truncated form lacking the plant-homeodomain-like domain associated with epigenetic repression. None of the transcripts encoding the core LAFL network transcription factors were affected in val1 embryos. Instead, activation of VAL1 by FUSCA3 appears to result in repression of a subset of seed maturation genes downstream of core LAFL regulators as 39% of transcripts in the FUSCA3 regulon were de-repressed in the val1 mutant. The LEC1 and LEC2 regulons also responded but to a lesser extent. Additional 832 transcripts that were not LAFL targets were de-repressed in val1 mutant embryos. These transcripts are candidate targets of VAL1, acting through epigenetic and/or transcriptional repression. 2 genotypes, 7 time points, 3 biological and 4 technical replicates
Project description:Developing Arabidopsis seeds accumulate oils and seed storage proteins synthesized by the pathways of primary metabolism. Seed development and metabolism are positively regulated by transcription factors belonging to the LAFL regulatory network. The VAL gene family encodes repressors of the seed maturation program in germinating seeds, although they are also expressed during seed maturation. VAL1 functions as a repressor of seed metabolism, as val1 mutant seeds accumulated elevated levels of storage proteins compared to the wild type. Two VAL1 splice variants were identified through RNA sequencing analysis: a full-length and a truncated form lacking the plant-homeodomain-like domain associated with epigenetic repression. None of the transcripts encoding the core LAFL network transcription factors were affected in val1 embryos. Instead, activation of VAL1 by FUSCA3 appears to result in repression of a subset of seed maturation genes downstream of core LAFL regulators as 39% of transcripts in the FUSCA3 regulon were de-repressed in the val1 mutant. The LEC1 and LEC2 regulons also responded but to a lesser extent. Additional 832 transcripts that were not LAFL targets were de-repressed in val1 mutant embryos. These transcripts are candidate targets of VAL1, acting through epigenetic and/or transcriptional repression.
Project description:14-day-old seedling of WT, val1, val2, and val1val2 were performed RNA-seq to analyzed their differential expression genes in Arabidopsis.
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.
Project description:This SuperSeries is composed of the following subset Series: GSE18588: CpG islands recruit a histone H3 lysine 36 demethylase [Illumina sequencing data] GSE21201: CpG islands recruit a histone H3 lysine 36 demethylase [Agilent data] Refer to individual Series