Identification of new regulators of the three dimensional Polycomb organization by a microscopy-based genome-wide RNAi screen
Ontology highlight
ABSTRACT:
ORGANISM(S): Drosophila melanogaster
SUBMITTER: Giacomo Cavalli
PROVIDER: E-GEOD-55303 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:Polycomb group (PcG) proteins dynamically define cellular identities through epigenetic repression of key developmental genes. PcG target gene repression can be stabilized through the interaction in the nucleus at PcG foci. Here, we report the results of a high-resolution microscopy genome-wide RNAi screen that identifies 129 genes that regulate the nuclear organization of Pc foci. Candidate genes include PcG components and chromatin factors, as well as many novel protein-modifying enzymes, including components of the SUMOylation pathway. In the absence of SUMO Pc foci coagulate into larger aggregates. Conversely, loss of function of the SUMO peptidase velo disperses Pc foci. Moreover, SUMO and velo colocalize with PcG proteins at PREs and Pc SUMOylation affects its chromatin targeting, suggesting that the dynamic regulation of Pc SUMOylation regulates PcG-mediated silencing by modulating the kinetics of Pc binding to chromatin as well as its ability to form Polycomb foci.
2014-04-03 | GSE55303 | GEO
Project description:Leukemias are characterized by bone marrow failure due to oncogenic mutations of hematopoietic stem cells (HSC) or blood precursor cells. HSC differentiation and self-renewal properties are tightly regulated by Polycomb group (PcG) proteins, a well-characterized family of transcriptional epigenetic regulators. PcG proteins form two canonical complexes: Polycomb repressive complex 1 (PRC1), and Polycomb repressive complex 2 (PRC2).CBX proteins link the activity of PRC1 with PRC2, serving as critical regulators of PcG-mediating activity. While the functional role of some CBX proteins in cancer has been largely explored, recent reports support the specific role of CBX2 in human tumors, thus it represent a promising new target for anti-cancer strategies. To date, chromodomain inhibitors have been identified for CBX7 , but no molecules inhibiting CBX2 have been described. Nevertheless, different chromatin-modulating drugs such as histone deacetylase inhibitors (HDACi) are reported to regulate CBX2 targets on chromatin, suggesting that HDACi might be used to indirectly modulate aberrant effects of CBX2 in cancer. We describe a novel SAHA-mediated mechanism of CBX2 post-translational regulation. We found that CBX2 undergoes SAHA-induced SUMO2/3 modification and that CBX2 SUMOylation promotes its ubiquitination and proteasome-dependent degradation. We also identified the specific molecular pathway and key players regulating CBX2 stability, demonstrating that CBX4 and RNF4 act as the E3 SUMO and E3 ubiquitin ligase, respectively. Additionally, CBX2-depleted leukemic cells display impaired proliferation, showing that CBX2 is required for leukemia cell clonogenicity. Our study provides the first evidence of a non-canonical SAHA-mediated anti-tumorigenic activity via CBX2 SUMOylation and degradation
2018-02-27 | PXD008287 | Pride
Project description:The Polycomb group (PcG) and Trithorax group (TrxG) of proteins are required for stable and heritable maintenance of repressed and active gene expression states. Their antagonistic function on gene control, repression for PcG and activity for TrxG, is mediated by binding to chromatin and subsequent epigenetic modification of target loci. Despite our broad knowledge about composition and enzymatic activities of the protein complexes involved, our understanding still lacks important mechanistic detail and a comprehensive view on target genes. In this study, we use an extensive data set of ChIP-seq, RNA-seq, and genome-wide detection of transcription start sites (TSSs) to identify and analyze thousands of binding sites for the PcG proteins and Trithorax from a Drosophila S2 cell line. In addition to finding a preference for stalled promoter regions of annotated genes, we uncover many intergenic PcG-binding sites coinciding with non-annotated transcription start sites. Interestingly, this set includes previously unknown promoters for primary transcripts of microRNA genes, thereby expanding the scope of Polycomb control to non-coding RNAs essential for development, apoptosis and growth. Chromatin from S2 cells was immunoprecipitated using antibodies against Pc, Ph, Psc, Trx-C or H3K4me3. In parallel, we isolated RNA from S2 cells and generated global gene expression profiles by RNA-seq. We also surveyed the Drosophila genome for yet non-annotated transcription start sites (TSSs) using a newly adapted protocol for Illumina sequencing (termed 5M-bM-^@M-^Y-MACE) with RNA isolated from S2 cells and embryos.
2010-12-21 | E-GEOD-24521 | biostudies-arrayexpress
Project description:Polycomb group (PcG) proteins maintain transcriptional repression of developmentally important genes and have been implicated in cell proliferation and stem-cell self-renewal. We used a genome-wide approach to map binding patterns of PcG proteins (Pc, esc and Sce) in Drosophila Kc cells. We found that Pc associates with large genomic regions of up to ~150kb in size, hereafter referred to as “Pc-domains”. Sce and esc accompany Pc in most of these domains. PcG-bound chromatin is trimethylated at histone H3 lysine 27 and in general transcriptionally silent. Furthermore, PcG proteins preferentially bind to developmental genes. Many of these encode transcriptional regulators and key components of signal transduction pathways, including Wingless, Hedgehog, Notch and Delta. We also identify several new putative functions of PcG proteins, such as in steroid hormone biosynthesis. These results highlight the extensive involvement of PcG proteins in the coordination of development through the formation of large repressive chromatin domains. Keywords: DamID, Chromatin immunoprecipitation, ChIP-chip
2006-04-20 | GSE4564 | GEO
Project description:SUMOylation, a post-translational protein modification, is dramatically upregulated and critically involved in heat stress response conservatively among species. Previous studies in Arabidopsis indicated that numerous chromatin associated proteins are SUMOylation substrates and most of heat-enhancing SUMOylation reactions occur in nucleus. However, the global functional connection between gene expression regulation and SUMOylation on chromatin is completely unknown in plant cells. Here we show a genome-wide relationship of chromatin-associated SUMOylation and transcription switches under room temperature, heat stress, and recovering conditions in Arabidopsis. The SUMO-associated chromatin sites, characterized via whole-genome ChIP-seq assays, are generally correlated with active chromatin markers. In response to heat stress, we found chromatin-associated SUMO signals increased at promoter-transcriptional start site regions and decreased in the gene bodies. Further RNA-seq analysis supported the role of chromatin-associated SUMOylation in activation of transcription during rapid responses to high temperature. Changing of SUMO signals on chromatin is correlated with upregulation of heat-responsive genes and downregulation of growth-related genes. Disruption of the SUMO ligase gene SIZ1 abolishes SUMO signals on chromatin and attenuates the rapid transcriptional responses to heat stress. Interestingly, the SUMO signal peaks are enriched in DNA elements recognized by distinguished groups of transcription factors under different temperature conditions. Collectively, our data provide evidence that SUMOylation on chromatin regulates transcription switches during development and heat stress response, improving our understanding on the precise roles of SUMOylation in plant cells.
2020-08-04 | GSE140507 | GEO
Project description:SUMOylation, a post-translational protein modification, is dramatically upregulated and critically involved in heat stress response conservatively among species. Previous studies in Arabidopsis indicated that numerous chromatin associated proteins are SUMOylation substrates and most of heat-enhancing SUMOylation reactions occur in nucleus. However, the global functional connection between gene expression regulation and SUMOylation on chromatin is completely unknown in plant cells. Here we show a genome-wide relationship of chromatin-associated SUMOylation and transcription switches under room temperature, heat stress, and recovering conditions in Arabidopsis. The SUMO-associated chromatin sites, characterized via whole-genome ChIP-seq assays, are generally correlated with active chromatin markers. In response to heat stress, we found chromatin-associated SUMO signals increased at promoter-transcriptional start site regions and decreased in the gene bodies. Further RNA-seq analysis supported the role of chromatin-associated SUMOylation in activation of transcription during rapid responses to high temperature. Changing of SUMO signals on chromatin is correlated with upregulation of heat-responsive genes and downregulation of growth-related genes. Disruption of the SUMO ligase gene SIZ1 abolishes SUMO signals on chromatin and attenuates the rapid transcriptional responses to heat stress. Interestingly, the SUMO signal peaks are enriched in DNA elements recognized by distinguished groups of transcription factors under different temperature conditions. Collectively, our data provide evidence that SUMOylation on chromatin regulates transcription switches during development and heat stress response, improving our understanding on the precise roles of SUMOylation in plant cells.
2020-08-04 | GSE140506 | GEO
Project description:Polycomb group (PcG) proteins maintain transcriptional repression of developmentally important genes and have been implicated in cell proliferation and stem-cell self-renewal. We used a genome-wide approach to map binding patterns of PcG proteins (Pc, esc and Sce) in Drosophila Kc cells. We found that Pc associates with large genomic regions of up to ~150kb in size, hereafter referred to as âPc-domainsâ. Sce and esc accompany Pc in most of these domains. PcG-bound chromatin is trimethylated at histone H3 lysine 27 and in general transcriptionally silent. Furthermore, PcG proteins preferentially bind to developmental genes. Many of these encode transcriptional regulators and key components of signal transduction pathways, including Wingless, Hedgehog, Notch and Delta. We also identify several new putative functions of PcG proteins, such as in steroid hormone biosynthesis. These results highlight the extensive involvement of PcG proteins in the coordination of development through the formation of large repressive chromatin domains. Keywords: DamID, Chromatin immunoprecipitation, ChIP-chip To study PcG binding profiles we used DamID, which is based on the ability of a chromatin protein fused to E.coli DNA adenine methyltransferase (Dam) to methylate the native binding site of the chromatin protein. Dam-fusion proteins are expressed at very low levels to avoid mistargeting. Subsequently, methylated DNA fragments are isolated, labeled and hybridized to a microarray. Methylated DNA fragments from cells transfected with Dam alone served as reference. Genomic binding sites of the protein can then be identified based on the targeted methylation pattern. For detailed background information on DamID, see: van Steensel, B., Delrow, J. & Henikoff, S. Chromatin profiling using targeted DNA adenine methyltransferase. Nat Genet 27, 304-8 (2001); van Steensel, B. & Henikoff, S. Identification of in vivo DNA targets of chromatin proteins using tethered dam methyltransferase. Nat Biotechnol 18, 424-8 (2000).
2010-06-11 | E-GEOD-4564 | biostudies-arrayexpress
Project description:We made Polycomb (PC) and histone H3 lysine 27 trimethylation (H3K27me3) chromatin binding maps in central brain tissue from 3rd instar larvae, allowing us to make a direct comparison to our 4C data (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE23166). Our results demonstrate that our PC and H3K27me3 maps are highly similar, and fit with previously identified hallmarks of PcG-bound chromatin, namely: PC and H3K27me3 co-occur in the genome as large contiguous domains that largely repress transcription of the underlying genes, which encode important regulators of development. Keywords: Genome binding/occupancy profiling by genome tiling array DamID experiments for Polycomb were performed in Drosophila larval brain tissue. Samples were hybridized to 380k NimbleGen arrays with 300 bp probe spacing.
2011-12-31 | E-GEOD-23298 | biostudies-arrayexpress
Project description:Chromatin insulators and Polycomb group (PcG) complexes control nuclear organization to effect changes in gene expression. In Drosophila, RNA silencing pathways influence long range interactions mediated by PcG proteins and nuclear localization of the gypsy insulator; however, the underlying mechanisms are unknown. Here, we identify a singular requirement for Argonaute2 (AGO2) for the activity of the CCCTC-binding factor (CTCF)/Centrosomal protein 190 (CP190) dependent Fab-8 insulator. AGO2 and CP190 interact physically, and genome wide localization of AGO2 by chromatin immunoprecipitation and sequencing (ChIP-seq) reveals extensive colocalization of AGO2 with insulators and Polycomb Response Elements (PREs) but minimal overlap with regions of endogenous small interfering RNA (endo-siRNA) production. Finally, depletion of either CTCF or CP190 results in loss of AGO2 association with insulators, PREs, and other cis-regulatory regions. Our findings suggest that Dicer-independent recruitment of AGO2 to chromatin by insulator proteins promotes the definition of transcriptional domains throughout the genome. ChIP-seq of AGO2 in two Drosophila cell types (S2 and S3)
2011-08-15 | E-GEOD-22623 | biostudies-arrayexpress
Project description:Polycomb group (PcG) proteins are critical epigenetic regulators of development. Here we compared genomic distribution of Polycomb (Pc) protein in cultured Drosophila cells lacking Su(z)12 protein to that of the wild type.
2016-09-15 | GSE83247 | GEO