Co-opted transposons help perpetuate conserved higher-order chromosomal structures
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE141550 | GEO | 2019/12/08
REPOSITORIES: GEO
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Project description:BackgroundTransposable elements (TEs) make up half of mammalian genomes and shape genome regulation by harboring binding sites for regulatory factors. These include binding sites for architectural proteins, such as CTCF, RAD21, and SMC3, that are involved in tethering chromatin loops and marking domain boundaries. The 3D organization of the mammalian genome is intimately linked to its function and is remarkably conserved. However, the mechanisms by which these structural intricacies emerge and evolve have not been thoroughly probed.ResultsHere, we show that TEs contribute extensively to both the formation of species-specific loops in humans and mice through deposition of novel anchoring motifs, as well as to the maintenance of conserved loops across both species through CTCF binding site turnover. The latter function demonstrates the ability of TEs to contribute to genome plasticity and reinforce conserved genome architecture as redundant loop anchors. Deleting such candidate TEs in human cells leads to the collapse of conserved loop and domain structures. These TEs are also marked by reduced DNA methylation and bear mutational signatures of hypomethylation through evolutionary time.ConclusionsTEs have long been considered a source of genetic innovation. By examining their contribution to genome topology, we show that TEs can contribute to regulatory plasticity by inducing redundancy and potentiating genetic drift locally while conserving genome architecture globally, revealing a paradigm for defining regulatory conservation in the noncoding genome beyond classic sequence-level conservation.
| S-EPMC6979391 | biostudies-literature
Project description:Co-opted transposons help perpetuate conserved higher-order chromosomal structures
| PRJNA593858 | ENA
Project description:It is increasingly being recognized that physical interactions between distant chromosomal loci influence the expressivity of the genome. Thus, multiple enhancers may converge on a single gene promoter 1,2 and a single enhancer can stochastically loop to multiple promoters 3. Regulatory elements from neighboring domains or from other chromosomes may interact to generate chromatin structures poised for transcription4-8 or repression 9-11. However, a broader perspective on the formation and function of such networks remains largely unexplored. Using the high-resolution 4C (Circular Chromosome Conformation Capture) analysis, we identify here a genome-wide physical network between genomically imprinted domains impinging H19 imprinting control region (ICR). Sequences interacting with the H19 ICR constitutively map at or within most of known imprinted domains both in mouse embryonic stem cells and in vitro-derived embryoid bodies, despite distinct differences in chromatin environments. Moreover, all-to-all 3D DNA FISH analyses revealed that imprinted domains from 7 different chromosomes co-localize with each other in pair-wise patterns, highlighting the dynamic nature of these interactions. The observed interaction network is dependent on CTCF binding sites within the maternally inherited H19 ICR allele and delays reprogramming of epigenetic features at imprinted domains during male germline development. As other imprinted regions can interact with each other in an H19 ICR-dependent manner, the H19 ICR emerges as an organizer of chromosomal networks by specifically recognizing and reconfiguring imprinted domains. We propose that an ancient key regulatory region, such as the H19 ICR, gradually impacted epigenetic modifications via long-range interactions in the germline to facilitate the recruitment of imprinted genes and their formation in clusters during mammalian radiation. Furthermore, the perspective of epigenetic lesions de-stabilizing such chromosomal networks may advance our understanding of how quantitative traits influence human diseases, such as cancer.
2009-12-14 | GSE14074 | GEO
Project description:Snake venoms contain complex mixtures of proteins that play vital roles in the survival of venomous snakes. In line with their diverse pharmacological activities, the protein compositions of snake venoms can be highly variable, and efforts to characterise the primary structures of such proteins are extensive and ongoing. In addition, a significant knowledge gap exists in terms of higher-order interactionsbetweenproteinsproposedto modulate venom potency, which poses a challenge for treatment of envenomation and development of successful therapeutic applications.Here we use a multifaceted mass spectrometrybased approach to characteriseproteinsfrom the medically significant venomsof Collett’s snake Pseudechis collettiand the puff adder Bitis arietans.Following chromatographic fractionation and bottom-up proteomics identification, native mass spectrometry identified, among other components, a 117 kDa non-covalent L-amino acid oxidase dimer in the P. collettivenom and a 60 kDa C-type lectin tetramer in the B. arietansvenom. Furthermore, a 27.7 kDa covalently-linked phospholipase A2(PLA2) dimer was identified in P. collettivenom, and thePLA2species were shownto adopt a highly compact geometry based on ion mobility measurements. Exploration of the catalytic efficiencies of the monomeric and dimeric forms of PLA2revealed that the dimeric PLA2 possessed greater bioactivity than the monomeric PLA2s.This work contributes to ongoing efforts to catalogue the protein components of snake venoms, and notably,itemphasises the importance of understanding higher-order protein interactions in venomsand the utility of a combined mass spectrometric approachfor this task.
2020-02-17 | PXD016503 | Pride
Project description:We used 4C sequencing technology for high-throughput profiling of HHV6A integration in both HEK293T cells and SMC cells. We identified genome-wide host-virus and virus-virus interactions profiles.
2020-12-09 | GSE162821 | GEO
Project description:Eukaryotic genomes are packaged into a 3-dimensional structure in the nucleus. Current methods for studying genome-wide structure are based on proximity ligation. However, this approach can fail to detect known structures, such as interactions with nuclear bodies, because these DNA regions can be too far apart to directly ligate. Accordingly, our overall understanding of genome organization remains incomplete. Here, we develop split-pool recognition of interactions by tag extension (SPRITE), a method that enables genome-wide detection of higher-order interactions within the nucleus. Using SPRITE, we recapitulate known structures identified by proximity ligation and identify additional interactions occurring across larger distances, including two hubs of inter-chromosomal interactions that are arranged around the nucleolus and nuclear speckles. We show that a substantial fraction of the genome exhibits preferential organization relative to these nuclear bodies. Our results generate a global model whereby nuclear bodies act as inter-chromosomal hubs that shape the overall packaging of DNA in the nucleus.
| S-EPMC6548320 | biostudies-literature
Project description:Higher order repeats (HORs) containing tandems of primary and secondary repeat units (head-to-tail "tandem within tandem pattern"), referred to as regular HORs, are typical for primate alpha satellite DNAs and most pronounced in human genome. Regular HORs are known to be a result of recent evolutionary processes. In non-primate genomes mostly so called complex HORs have been found, without head to tail tandem of primary repeat units. In beetle Tribolium castaneum, considered as a model case for genome studies, large tandem repeats have been identified, but no HORs have been reported. Here, using our novel robust repeat finding algorithm Global Repeat Map, we discover two regular and six complex HORs in T. castaneum. In organizational pattern, the integrity and homogeneity of regular HORs in T. castaneum resemble human regular HORs (with T. castaneum monomers different from human alpha satellite monomers), involving a wider range of monomer lengths than in human HORs. Similar regular higher order repeat structures have previously not been found in insects. Some of these novel HORs in T. castaneum appear as most regular among known HORs in non-primate genomes, although with substantial riddling. This is intriguing, in particular from the point of view of role of non-coding repeats in modulation of gene expression.
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Project description:Three-dimensional chromosomal conformations regulate transcription by moving enhancers and regulatory elements into spatial proximity with target genes. Here we describe activity-regulated long-range loopings bypassing up to 0.5 Mb of linear genome to modulate NMDA glutamate receptor GRIN2B expression in human and mouse prefrontal cortex. Distal intronic and 3' intergenic loop formations competed with repressor elements to access promoter-proximal sequences, and facilitated expression via a "cargo" of AP-1 and NRF-1 transcription factors and TALE-based transcriptional activators. Neuronal deletion or overexpression of Kmt2a/Mll1 H3K4- and Kmt1e/Setdb1 H3K9-methyltransferase was associated with higher-order chromatin changes at distal regulatory Grin2b sequences and impairments in working memory. Genetic polymorphisms and isogenic deletions of loop-bound sequences conferred liability for cognitive performance and decreased GRIN2B expression. Dynamic regulation of chromosomal conformations emerges as a novel layer for transcriptional mechanisms impacting neuronal signaling and cognition.
| S-EPMC4258154 | biostudies-literature
Project description:Human telomeres contain the repeat DNA sequence 5'-d(TTAGGG), with duplex regions that are several kilobases long terminating in a 3' single-stranded overhang. The structure of the single-stranded overhang is not known with certainty, with disparate models proposed in the literature. We report here the results of an integrated structural biology approach that combines small-angle X-ray scattering, circular dichroism (CD), analytical ultracentrifugation, size-exclusion column chromatography and molecular dynamics simulations that provide the most detailed characterization to date of the structure of the telomeric overhang. We find that the single-stranded sequences 5'-d(TTAGGG)n, with n = 8, 12 and 16, fold into multimeric structures containing the maximal number (2, 3 and 4, respectively) of contiguous G4 units with no long gaps between units. The G4 units are a mixture of hybrid-1 and hybrid-2 conformers. In the multimeric structures, G4 units interact, at least transiently, at the interfaces between units to produce distinctive CD signatures. Global fitting of our hydrodynamic and scattering data to a worm-like chain (WLC) model indicates that these multimeric G4 structures are semi-flexible, with a persistence length of ?34 Å. Investigations of its flexibility using MD simulations reveal stacking, unstacking, and coiling movements, which yield unique sites for drug targeting.
| S-EPMC7897503 | biostudies-literature
Project description:We develop Split-Pool Recognition of Interactions by Tag Extension (SPRITE), which enables genome-wide detection of higher-order interactions that occur simultaneously within the nucleus in a proximity-ligation independent manner. We generated SPRITE maps in two mammalian cell types – mouse embryonic stem cells (mES) and human lymphoblastoid cells (GM12878). We generated ~1.5 billion sequencing reads from each sample and recapitulate known genome structures identified by Hi-C, including chromosome territories, compartments, topologically associated domains, and loop structures, and identify that many of these occur within higher-order structures in the nucleus. Because SPRITE does not rely on proximity-ligation, we find that SPRITE identifies interactions that occur across larger spatial distances than can be observed by Hi-C. These long-range interactions include two major hubs of inter-chromosomal interactions. We extended SPRITE to enable simultaneous measurements of RNA and DNA interactions and observe ribosomal RNA interactions across specific regions on the genome that correspond to DNA organization around the nucleolus. We show that gene-dense regions that are highly transcribed by PolII organize around nuclear speckles and gene poor, and therefore transcriptionally inactive, regions that are centromere-proximal organize around the nucleolus. In addition to the regions that directly associate around these nuclear bodies, we find that a substantial fraction of the genome exhibits preferential spatial positioning in the nucleus relative to each of these nuclear bodies and that the spatial preferences identified by SPRITE are highly correlated with 3D distances measured by microscopy.
2018-06-07 | GSE114242 | GEO