Project description:PcG and TrxG are important epigenetic regulators of genome expression. Here we have determined genomic distributions of PC, E(Z), H3K27me3, TRX, ASH1, RNA Pol II, H3K4me3, H3K27ac in cultured Drosophila ML-DmBG3-c2 cells by hybridization of ChIP products with tiling microarrays.
Project description:We used ChIP on chip assays to determine the genome wide distribution of a large set of PcG and trxG proteins, their associated histone marks and four candidate DNA-binding factors for PcG protein recruitment.
Project description:We used ChIP on chip assays to determine the genome wide distribution of a large set of PcG and trxG proteins, their associated histone marks and four candidate DNA-binding factors for PcG protein recruitment.
Project description:PcG and TrxG are important epigenetic regulators of genome expression. Here we have determined genomic distributions of PC, E(Z), H3K27me3, TRX, ASH1, RNA Pol II, H3K4me3, H3K27ac in cultured Drosophila ML-DmD23-c4 cells by hybridization of ChIP products with tiling microarrays
Project description:PcG and TrxG are important epigenetic regulators of genome expression. Here we have determined genomic distributions of TRX, ASH1, RNA Pol II, H3K4me3, H3K27ac, H3K9ac in cultured Drosophila Sg4 cells by hybridization of ChIP products with tiling microarrays.
Project description:Background: The question of how cells re-establish gene expression states after cell division is still poorly understood. Genetic and molecular analyses have indicated that Trithorax group (TrxG) proteins are critical for the long-term maintenance of active gene expression states in many organisms. A generally accepted model suggests that TrxG proteins contribute to maintenance of transcription by protecting genes from inappropriate Polycomb group (PcG)-mediated silencing, instead of directly promoting transcription. Results: Here we report a physical and functional interaction in Drosophila between two members of the TrxG, the histone methyltransferase ASH1 and the bromodomain and extraterminal family protein FSH. We investigated this interface at the genome level, uncovering a widespread colocalization of both proteins at promoters and PcG-bound intergenic elements. Our integrative analysis of chromatin maps and gene expression profiles revealed that the observed ASH1-FSH binding pattern at promoters is a hallmark of active genes. Inhibition of FSH-binding to chromatin resulted in global down-regulation of transcription. In addition, we found that genes displaying marks of robust PcG-mediated repression also have ASH1 and FSH bound to their promoters. Conclusions: Our data strongly favor a global coactivator function of ASH1 and FSH during transcription, as opposed to the notion that TrxG proteins impede inappropriate PcG-mediated silencing, but are dispensable elsewhere. Instead, our results suggest that PcG repression needs to overcome the transcription-promoting function of ASH1 and FSH in order to silence genes. Refer to individual Series
Project description:We report an ex vivo kinome-wide RNAi screen in Drosophila aimed to identify cell signaling genes that facilitate trxG to counteract PcG mediated repression. From the list of trxG candidates, Ballchen (BALL), a histone kinase, known to phosphorylate histone H2A at threonine 119 (H2AT119p), was characterized as a trxG regulator. BALL co-localizes with Trithorax on chromatin and depletion of BALL results in increased H2AK118 ubiquitination, a histone mark central to PcG mediated gene silencing. Moreover, analysis of genome-wide binding profile of BALL shows an overlap with 85% known binding sites of TRX across the genome. Both BALL and TRX are highly enriched at actively transcribed genes, which also correlate with presence of H3K4me3 and H3K27ac. We propose that BALL mediated signal positively contributes to the maintenance of gene activation by trxG by counteracting the repressive effect of PcG.
Project description:The Polycomb group (PcG) and Trithorax group (TrxG) proteins are key epigenetic regulators controlling silenced and active states of genes in multicellular organisms, respectively. In Drosophila PcG/TrxG proteins are recruited to chromatin via binding to specialized DNA-elements termed Polycomb Response Elements (PREs). While precise mechanisms of PcG/TrxG proteins recruitment remains unknown, the important role is suggested to belong to sequence specific DNA-binding factors. Here, using affinity purification coupled with high throughput mass spectrometry (IP/MS), we isolated factors associated with Combgap, Psq, Zeste and Adf1 PRE DNA-binding Drosophila proteins. As a control we used unspecific IgG. For affinity purification the nuclear extract from Drosophila S2 cells and polyclonal antibodies against Combgap, Psq, Zeste and Adf1 were used.
