Widespread rearrangement of 3D chromatin organization underlies Polycomb-mediated stress-induced silencing [Hi-C]
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ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE63515 | GEO | 2015/02/24
SECONDARY ACCESSION(S): PRJNA268118
REPOSITORIES: GEO
Similar Datasets
Project description:Chromosomes of metazoan organisms are partitioned in the interphase nucleus into discrete topologically associating domains (TADs). Borders between TADs are preferentially formed in regions containing high density of active genes and clusters of architectural protein binding sites. Transcription of most genes is turned off during the heat shock response in Drosophila. Here we show that temperature stress induces relocalization of architectural proteins from TAD borders to inside TADs, and this is accompanied by a dramatic rearrangement in the 3D organization of the nucleus. TAD border strength declines, allowing for an increase in long-distance inter-TAD interactions. Similar but quantitatively weaker effects are observed upon inhibition of transcription or depletion of individual architectural proteins. New heat shock-induced inter-TAD interactions result in increased contacts among enhancers and promoters of silenced genes, which recruit Pc and form Pc bodies at the nucleolus. These results suggest that the TAD organization of metazoan genomes is plastic and can be quickly reconfigured to allow new interactions between distant sequences. Analysis of the distribution of architectural proteins, chromatin proteins and histone modifications in Drosophila Kc167 cells. Cells were grown at 25 C (NT) or heat shocked for 20 min at 36.5 C (HS). Both control and reference samples are included. For some of the samples, replicates are also included.
2015-02-24 | E-GEOD-62904 | biostudies-arrayexpress
Project description:Chromosomes of metazoan organisms are partitioned in the interphase nucleus into discrete topologically associating domains (TADs). Borders between TADs are preferentially formed in regions containing high density of active genes and clusters of architectural protein binding sites. Transcription of most genes is turned off during the heat shock response in Drosophila. Here we show that temperature stress induces relocalization of architectural proteins from TAD borders to inside TADs, and this is accompanied by a dramatic rearrangement in the 3D organization of the nucleus. TAD border strength declines, allowing for an increase in long-distance inter-TAD interactions. Similar but quantitatively weaker effects are observed upon inhibition of transcription or depletion of individual architectural proteins. New heat shock-induced inter-TAD interactions result in increased contacts among enhancers and promoters of silenced genes, which recruit Pc and form Pc bodies at the nucleolus. These results suggest that the TAD organization of metazoan genomes is plastic and can be quickly reconfigured to allow new interactions between distant sequences. Analysis of 3D chromatin organization using Hi-C in Drosophila Kc167 cells. Cells were grown at 25 C and heat shocked for 20 min at 36.5 C. Cells were also treated with flavopiridol or triptolide to inhibit transcription elongation or initiation, respectively. Cells were depeleted of Cap-H2 or Rad21 using RNAi. Finally, cells depleted of RAd21 were subjected to heat shock at 36.5 C for 20 min.
2015-02-24 | E-GEOD-63515 | biostudies-arrayexpress
Project description:Chromosomes of metazoan organisms are partitioned in the interphase nucleus into discrete topologically associating domains (TADs). Borders between TADs are preferentially formed in regions containing high density of active genes and clusters of architectural protein binding sites. Transcription of most genes is turned off during the heat shock response in Drosophila. Here we show that temperature stress induces relocalization of architectural proteins from TAD borders to inside TADs, and this is accompanied by a dramatic rearrangement in the 3D organization of the nucleus. TAD border strength declines, allowing for an increase in long-distance inter-TAD interactions. Similar but quantitatively weaker effects are observed upon inhibition of transcription or depletion of individual architectural proteins. New heat shock-induced inter-TAD interactions result in increased contacts among enhancers and promoters of silenced genes, which recruit Pc and form Pc bodies at the nucleolus. These results suggest that the TAD organization of metazoan genomes is plastic and can be quickly reconfigured to allow new interactions between distant sequences.
2015-02-24 | GSE62904 | GEO
Project description:Topologically associating domains (TADs) are widely recognized as fundamental elements of the 3D structure of the eukaryotic genome. However, while the structural importance of the insulator protein CTCF together with cohesin at TAD borders in mammalian cells is well established, the absence of such co-localization at most TAD borders in recent Hi-C studies of D. melanogaster is enigmatic, raising the possibility that these TAD border elements are not generally conserved among metazoans. Using in situ Hi-C with sub-kb resolution, we show that the genome of D. melanogaster is almost completely partitioned into more than 4,000 TADs (median size, 13 kb), nearly 7-fold more than previously identified. The overwhelming majority of these TADs are demarcated by pairs of Drosophila-specific insulator proteins, BEAF-32/CP190 or BEAF-32/Chromator, indicating that these proteins may play an analogous role in Drosophila as that of the CTCF/cohesin pair in mammals. Moreover, we find that previously identified TADs enriched for inactive chromatin are predominantly assembled from the higher-level interactions between smaller TADs. In contrast, the closely-spaced small TADs in regions previously thought to be unstructured “inter-TADs” are organized in an open configuration with far fewer TAD-TAD interactions. Such structures can also be identified in some “inter-TAD” regions of the mammalian genome, suggesting that larger assemblages of small self-interacting TADs separated by a “burst” of adjacent small, weakly interacting TADs may be a conserved, basic characteristic of the higher order folding of the metazoan genome.
2017-11-22 | GSE101317 | GEO
Project description:The DNA in humans and many animals is compartmentalised in topologically associating domains (TADs). In Drosophila, several architectural proteins are enriched at TAD borders, but we are still missing evidence that these proteins have a functional role in TAD maintenance. Here, we show that depletion of BEAF-32, Cp190 and Chro leads to changes in TAD organisation and chromatin loops. Their depletion affects mainly TAD borders in heterochromatin, while euchromatin TAD borders are resilient to these mutants. Furthermore, transcriptomic data identified thousands of genes displaying differential expression in these mutants and that majority of differentially expressed genes are in TADs that are reorganised. In contrast, we observed a lower effect on gene expression by the loss of chromatin loops. Our work identified for the first time a functional role for architectural proteins at TAD borders in Drosophila and a strong link between TAD reorganisation and changes in gene expression.
2022-02-07 | GSE147059 | GEO
Project description:Recent advances enabled by Hi-C technique have unraveled principles of chromosomal folding, which were since linked to many genomic processes. In particular, Hi-C revealed that chromosomes of animals are organized into Topologically Associating Domains (TADs), evolutionary conserved compact chromatin domains that influence gene expression. However, mechanisms that underlie partitioning of the genome into TADs remain poorly understood. To explore principals of TAD folding in Drosophila melanogaster, we performed Hi-C and PolyA+ RNA-seq in four cell lines of various origins (S2, Kc167, DmBG3-c2, and OSC). Contrary to previous studies, we find that regions between TADs (i.e. the inter-TADs and TAD boundaries) in Drosophila are only weakly enriched with the insulator protein dCTCF, while another insulator protein Su(Hw) is preferentially present within TADs. However, Drosophila inter-TADs harbor active chromatin and constitutively transcribed (housekeeping) genes. Accordingly, we find that binding of insulator proteins dCTCF and Su(Hw) predict TAD boundaries much worse than the active chromatin marks (in the minimal case, H3K4me3 and total RNA) do. Moreover, inter-TADs correspond to decompacted interbands of polytene chromosomes, whereas TADs mostly correspond to densely packed bands. Collectively, our results suggest that TADs are condensed chromatin domains depleted in active chromatin marks, separated by regions of active chromatin that cannot be organized into compact structures, possibly due to high levels of histone acetylation. Finally, we test this hypothesis by polymer simulations, and find that TAD partitioning can be explained by different modes of inter-nucleosomal interactions for active and inactive chromatin. Hi-C experiments, PolyA+ RNA profiling and mapping of chromosomal rearrangements in four Drosophila melanogaster cell lines.
2015-10-26 | E-GEOD-69013 | biostudies-arrayexpress
Project description:Compartmentalisation of the genome as topologically associating domains (TADs) may have a regulatory role in development and cellular functioning, but the mechanism involved in TAD establishment is still unclear. Here, we present the first high-resolution contact map of Drosophila melanogaster neuronal cells (BG3) and identify different classes of TADs by comparing this to genome organisation in embryonic cells (Kc167). We find new interactions during differentiation in neuronal cells, which are reflected as enhanced long-range interactions. This is supported by pronounced enrichment of CTCF at TAD borders. Furthermore, we observed strong divergent transcription, together with RNA Polymerase II occupancy, and an increase in DNA accessibility at the TAD borders. Interestingly, TAD borders that are specific to neuronal cells are enriched in enhancers controlled by neuronal specific transcription factors. Our results suggest that TADs are dynamic across developmental stages and reflect the interplay between insulators, transcriptional states and enhancer activities.
2019-01-18 | GSE122603 | GEO
Project description:Genome organization is driven by forces affecting transcriptional state, but the relationship between transcription and genome architecture remains unclear. Here, we identified the Drosophila transcription factor Motif 1 Binding Protein (M1BP) in physical association with the gypsy chromatin insulator core complex, including the universal insulator protein CP190. M1BP is required for enhancer-blocking and barrier activities of the gypsy insulator as well as its proper nuclear localization. Genome-wide, M1BP specifically colocalizes with CP190 at Motif 1-containing promoters, which are enriched at topologically associating domain (TAD) borders. M1BP facilitates CP190 chromatin binding at many shared sites and vice versa. Both factors promote Motif 1-dependent gene expression and transcription near TAD borders genome-wide. Finally, loss of M1BP reduces chromatin accessibility and increases both inter- and intra-TAD local genome compaction. Our results reveal physical and functional interaction between CP190 and M1BP to activate transcription at TAD borders and mediate chromatin insulator-dependent genome organization.
2021-06-07 | PXD026497 | Pride
Project description:Drosophila Argonaute2 (AGO2) is known to regulate expression of certain loci in an RNA interference-independent manner, but its genome-wide function on chromatin remains unknown. Here, we identified RNA Polymerase II (Pol II) and LaminB as AGO2 nuclear interactors. AGO2 and LaminB attenuate transcription at borders between both LaminB-associated domains (LADs) and topologically-associated domains (TADs). We identified a somatic target of AGO2 transcriptional repression, nht, which is immersed in a LAD located within a repressive TAD. Null mutation of AGO2 leads to ectopic expression of spermatogenesis genes dependent on nht. Finally, depletion of either AGO2 or LaminB results in reduced looping interactions within the TAD as well as ectopic inter-TAD interactions. Overall, our findings reveal coordination of AGO2 and LaminB to dictate overall genome architecture and thereby regulate gene expression.
2018-02-27 | GSE101365 | GEO
Project description:Three-dimensional genome structure plays an important role in gene regulation. Globally chromosomes are organized into active and inactive compartments, while at the gene level looping interactions connect promoters to regulatory elements. Topologically Associating Domains (TADs), typically several hundred kilobases in size form an intermediate level of organization. Major questions include how TADs are formed and what their relation is with looping interactions between genes and regulatory elements. Here we performed a focused 5C analysis of a 2.8 Mb region on chromosome 7 surrounding CFTR in a panel of cell types. We find that the same TAD boundaries are present in all cell types, indicating that TADs represent a universal chromosome architecture. Further, we find that these TAD boundaries are present irrespective of expression and looping of genes located between them. In contrast looping interactions between promoters and regulatory elements are cell-type specific and occur mostly within TADs. This is exemplified by the CFTR promoter that in different cell types interacts with distinct sets of distal cell type-specific regulatory elements that are all located within the same TAD. Finally, we find that long-range associations between loci located in different TADs are also detected but these display much lower interaction frequencies than looping interactions within TADs. Interestingly, interactions between TADs are also highly cell type-specific and often involve loci clustered around TAD boundaries. These data point to key roles of invariant TAD boundaries in constraining as well as mediating cell type-specific long-range interactions and gene regulation. We investigated a 2.8 Mb region on Chromosome 7 (hg18 chr7: 115797757-118405450) containing the ENCODE region ENm001 42. The 5C experiment was designed to interrogate looping interactions between HindIII fragments containing transcription start sites (TSSs) and any other HindIII restriction fragment (distal fragments) in the target region. Libraries were generated for five cell lines: Caco2, Calu3, Capan1, GM12878 and HepG2, with two biological replicates for each line. 5C probes were designed at HindIII restriction sites (AAGCTT) using 5C primer design tools previously developed and made publicly available online at our My5C website (http://my5C.umassmed.edu). Probes were designed based on the ENCODE manual region 1 (ENM001) design 25 with additional probes placed throughout the region when appropriate. We also added probes to extend the analysis to include a 700 Kb gene desert region located directly adjacent to ENM001. Probe settings were: U-BLAST, 3; S-BLAST, 100; 15-MER, 3,000; MIN_FSIZE, 250; MAX_FSIZE, 20,000; OPT_TM, 65; OPT_PSIZE, 40. We designed 74 reverse 5C probes, and 605 forward 5C probes.
2016-01-07 | E-GEOD-75634 | biostudies-arrayexpress