Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

GAGA-Associated Factor Fosters Loop Formation in the Drosophila Genome

ABSTRACT: The role of genome organization in the control of gene expression persists as a central mystery of modern biology. Most efforts have focused on the role of boundary elements and CTCF in the compartmentalization of the genome into a series of topological associating domains (TADs). These compartments have been suggested to enable long-range DNA-DNA associations via loop extrusion processes. However, there is emerging evidence for long-range focal contacts, whereby specific DNA sequences associated with promoters and distal enhancers interact to form chromatin loops. One such class of DNAs, tethering elements, binds GAGA-associated factor (GAF). Previous studies provided evidence that GAF possesses amyloid properties in vitro, enabling the formation of loops bridging separate DNA molecules. In this study we investigated the possibility that GAF also functions as a looping factor in Drosophila development. We employed a combination of Micro-C assays, proteasomal degradation, and genome editing to examine the impact of defined GAF mutants on genome topology. These studies suggest that the N-terminal POZ/BTB oligomerization domain is particularly important for long-range interactions of GAF bound to distant GAGA-rich tethering elements. By contrast, the C-terminal low complexity domain (poly Q) plays only a minor role in loop formation. The most striking effects of GAF mutants are observed for long-range promoter-promoter interactions that coordinate the activities of distant paralogous genes.

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE218168 | GEO | 2023/02/14

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Mechanism of homology search expansion during recombinational DNA repair

Project description:Homology search is a central step of DNA double-strand break (DSB) repair by homologous recombination. How it operates in cells remains elusive. Here we developed a Hi-C-based methodology to map single-stranded DNA (ssDNA) contacts genome-wide in S. cerevisiae, which revealed two main homology search phases. Initial search conducted by short Rad51-ssDNA nucleoprotein filaments (NPFs) is confined in cis by cohesin-mediated chromatin loop folding. Progressive growth of stiff NPFs enables exploration of distant genomic sites. Long-range resection drives this transition from local to genome-wide search by increasing the probability of assembly of extensive NPFs. DSB end-tethering promotes coordinated homology search by opposite NPFs. Finally, an autonomous genetic element on chromosome III engages the NPF, which stimulates homology search in its vicinity. This work reveals the mechanism of the progressive expansion of homology search orchestrated by chromatin organizers, long-range resection, end-tethering, specialized genetic elements, and that exploits the stiff NPF structure conferred by Rad51 oligomerization.

2024-07-29 | GSE272969 | GEO

Chromosome-level organization of the regulatory genome in the Drosophila nervous system [Hi-C]

Project description:Here we present evidence for a new level of genome folding, whereby distant domains megabases apart fuse to form meta-domains. Within meta-domains, certain gene promoters pair with structural intergenic elements in the distant TAD. These long-range associations occur in a large fraction of Drosophila neurons, but support transcription in only a subset of cells in the nervous system. Most of the associated genes encode neuronal determinants, including those engaged in axonal guidance and adhesion. Meta-domains are formed by diverse transcription factors that are able to pair over long and flexible distances. We present evidence that one of these factors, GAF, plays a direct role in this process.

2023-08-01 | GSE214704 | GEO

Transcriptional Coupling of Distant Regulatory Genes in Living Embryos

Project description:The prevailing view of metazoan gene regulation is that individual genes are independently regulated by their own dedicated sets of transcriptional enhancers. Past studies reported long-range gene-gene associations, but their functional significance in regulating transcription remains uncertain and controversial. Here we employ quantitative single cell live imaging methods to provide the first demonstration of co-dependent transcriptional dynamics of genes separated by large genomic distances in living embryos. We find extensive physical and functional associations of distant paralogous genes, including co-regulation by shared enhancers and co-transcriptional bursting over distances of nearly 250kb. Regulatory inter-connectivity depends on promoter-proximal tethering elements and perturbations in these elements uncouple transcription and alter the bursting dynamics of distant genes, suggesting a role of genome topology in the formation and stability of co-transcriptional hubs. Transcriptional coupling of distant genes throughout the Drosophila genome underlies a broad spectrum of conserved developmental processes, suggesting a general strategy for long-range integration of gene activities.

2022-02-01 | GSE173518 | GEO

Chromosome-level organization of the regulatory genome in the Drosophila nervous system

Project description:Past studies have identified topologically associating domains (TADs) as basic units of genome organization. Here, we present evidence for a new level of genome folding, whereby distant TAD pairs megabases apart interact to form meta-domains. Within meta-domains, gene promoters and structural intergenic elements present in distant TADs are specifically paired. The associated genes encode neuronal determinants, including those engaged in axonal guidance and adhesion. These long-range associations occur in a large fraction of neurons but support transcription in only a subset of neurons. Meta-domains are formed by diverse transcription factors that are able to pair over long and flexible distances. We present evidence that two such factors, GAF and CTCF, play direct roles in this process. The relative simplicity of higher-order meta-domain interactions in Drosophila, compared with those previously described in mammals, allowed the demonstration that genomes can fold into highly specialized cell type-specific scaffolds that enable megabase-scale regulatory associations.

2023-08-01 | GSE228095 | GEO

Polycomb-Dependent Chromatin Looping Contributes to Gene Silencing during Drosophila Development

Project description:Interphase chromatin is organized into topologically associating domains (TADs). Within TADs, chromatin looping interactions are formed between DNA regulatory elements, but their functional importance for the establishment of the 3D genome organization and gene regulation during development is unclear. Using high-resolution Hi-C experiments, we analyze higher order 3D chromatin organization during Drosophila embryogenesis and identify active and repressive chromatin loops that are established with different kinetics and depend on distinct factors: Zelda-dependent active loops are formed before the midblastula transition between transcribed genes over long distances. Repressive loops within polycomb domains are formed after the midblastula transition between polycomb response elements by the action of GAGA factor and polycomb proteins. Perturbation of PRE function by CRISPR/Cas9 genome engineering affects polycomb domain formation and destabilizes polycomb-mediated silencing. Preventing loop formation without removal of polycomb components also decreases silencing efficiency, suggesting that chromatin architecture can play instructive roles in gene regulation during development.

2018-06-08 | GSE103625 | GEO

GAGA Factor maintains promoters in nucleosome-free conformation and allows promoter-proximal pausing [MNase]

Project description:Promoter-proximal pausing of RNA polymerase II (Pol II) is a widespread in higher eukaryotes. Previous studies have shown that GAF is enriched at paused genes, but the role of GAF in pausing has not been well characterized on a genome-wide level. To investigate the role of GAF in pausing, we RNAi-depleted GAF from Drosophila S2 cells, and examined the effects on promoter-proximal polymerase. We confirmed the importance of GAF for pausing on the classic pause model gene Hsp70. To determine the dependence of pausing on GAF genome-wide, we assayed the levels of transcriptionally-engaged polymerase genome-wide using GRO-seq in control and GAF-RNAi cells. We found that promoter-proximal polymerase was significantly reduced on a subset of paused genes with GAF-bound promoters. There is a dramatic change in nucleosome distribution at genes with reduction in pausing upon GAF depletion and intergenic GAF binding sites in GAF knock-down, suggesting that GAF allows the establishment of pausing at these genes by directing nucleosome displacement off of the promoter. In addition, the insulator factor BEAF, BEAF-interacting protein Chriz, and transcription M1BP enrichment on unaffected genes suggests that redundant transcription factors or insulators protect other GAF-bound paused genes from GAF knock-down effects. Three biological replicates of MNase digested chromatin from LacZ-RNAi and GAGA factor-RNAi cells.

2015-04-04 | E-GEOD-58956 | biostudies-arrayexpress

Genome organization controls transcriptional dynamics during development

Project description:Past studies offer contradictory claims for the role of genome organization in the regulation of gene activity. Here, we show through high-resolution chromosome conformation analysis that the Drosophila genome is organized by two independent classes of regulatory sequences, tethering elements and insulators. Quantitative live imaging and targeted genome editing demonstrate that this two-tiered organization is critical for the precise temporal dynamics of Hox gene transcription during development. Tethering elements mediate long-range enhancer-promoter interactions and foster fast activation kinetics. Conversely, the boundaries of topologically associating domains (TADs) prevent spurious interactions with enhancers and silencers located in neighboring TADs. These two levels of genome organization operate independently of one another to ensure precision of transcriptional dynamics and the reliability of complex patterning processes.

2022-02-03 | GSE171396 | GEO

The Genomic Binding Profile of GAGA Element Associated Factor (GAF) in Drosophila S2 cells

Project description:GAGA associated transcription factor (GAF) is a highly abundant and essential protein in Drosophila. GAF recognizes and binds arrays of GA dinucleotides via a zinc finger DNA binding domain to regulate transcription by binding to general TF machinery or recruit nucleosome remodeling factors. We performed GAF ChIP-seq to quantify the intensity of GAF binding at high resolution in S2 cells. In addition, we performed GAF ChIP-seq in S2 cells that were depleted of GAF by RNAi. By quantifying the degree to which all GAF binding sites are susceptible to GAF depletion, we found the cellular degree of depletion does not translate equally to the depletion of GAF at individual chromatin bound sites. For example, some high intensity GAF binding sites were completely unaffected by GAF depletion, while lower affinity binding sites were often ablated upon GAF depletion. These data sets will serve as a valuable resource to others who study the dynamic interplay between GAF and chromatin. We also compared the GAF binding sites to the full set of genomic ChIP data that is available for S2 cells and compared the intensity for each factor and histone modification/variant. Lastly, we investigated the influence that GAF had upon inducible transcription factor binding using the heat shock system. A single mock immunoprecipitation (IP) using non-specific IgG was used as a background dataset for this study (see PMID: 20844575; GSM470838). We performed two independent GAF-ChIP-seq experiments in untreated S2 cells and two replicates in S2 cells that were depleted of GAF by RNAi.

2013-08-01 | E-GEOD-40646 | biostudies-arrayexpress

The Genomic Binding Profile of GAGA Element Associated Factor (GAF) in Drosophila S2 cells

2013-08-01 | GSE40646 | GEO

Drosophila melanogaster

Project description:GAGA-Associated Factor Mediates Long-Range Promoter-Promoter Connectivity

| PRJNA875450 | ENA