Polycomb group (PcG) complexes PRC1 and PRC2 are well known for silencing specific developmental genes. PRC2 is a methyltransferase targeting histone H3K27 and producing H3K27me3, essential for stable silencing. Less well known but quantitatively much more important is the genome-wide role of PRC2 that dimethylates ∼70% of total H3K27. We show that H3K27me2 occurs in inverse proportion to transcriptional activity in most non-PcG target genes and intergenic regions and is governed by opposing roaming activities of PRC2 and complexes containing the H3K27 demethylase UTX. Surprisingly, loss of H3K27me2 results in global transcriptional derepression proportionally greatest in silent or weakly transcribed intergenic and genic regions and accompanied by an increase of H3K27ac and H3K4me1. H3K27me2 therefore sets a threshold that prevents random, unscheduled transcription all over the genome and even limits the activity of highly transcribed genes. PRC1-type complexes also have global roles. Unexpectedly, we find a pervasive distribution of histone H2A ubiquitylated at lysine 118 (H2AK118ub) outside of canonical PcG target regions, dependent on the RING/Sce subunit of PRC1-type complexes. We show, however, that H2AK118ub does not mediate the global PRC2 activity or the global repression and is predominantly produced by a new complex involving L(3)73Ah, a homolog of mammalian PCGF3.
Pubmed ID: 25986499 RIS Download
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Set of software modules for performing common ChIP-seq data analysis tasks across the whole genome, including positional correlation analysis, peak detection, and genome partitioning into signal-rich and signal-poor regions. The tools are designed to be simple, fast and highly modular. Each program carries out a well defined data processing procedure that can potentially fit into a pipeline framework. ChIP-Seq is also freely available on a Web interface.
View all literature mentionsDatabase of Drosophila genetic and genomic information with information about stock collections and fly genetic tools. Gene Ontology (GO) terms are used to describe three attributes of wild-type gene products: their molecular function, the biological processes in which they play a role, and their subcellular location. Additionally, FlyBase accepts data submissions. FlyBase can be searched for genes, alleles, aberrations and other genetic objects, phenotypes, sequences, stocks, images and movies, controlled terms, and Drosophila researchers using the tools available from the "Tools" drop-down menu in the Navigation bar.
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