Ontology highlight
ABSTRACT:
PROVIDER: PRJNA256012 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR1520420.fastq.gz | Fastqsanger.gz | |||
| SRR1523642.fastq.gz | Fastqsanger.gz | |||
| SRR1523643.fastq.gz | Fastqsanger.gz | |||
| SRR1523644.fastq.gz | Fastqsanger.gz | |||
| SRR1523645.fastq.gz | Fastqsanger.gz |
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Project description:Condensin-Driven Remodeling of X-Chromosome Topology during Dosage Compensation [ChIP-Seq]
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Project description:Condensin-Driven Remodeling of X-Chromosome Topology during Dosage Compensation [Hi-C]
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Project description:Mechanisms of X chromosome dosage compensation have been studied extensively in a few model species representing clades of shared sex chromosome ancestry. However, the diversity within each clade as a function of sex chromosome evolution is largely unknown. Here, we anchor ourselves to the nematode Caenorhabditis elegans, for which a well-studied mechanism of dosage compensation occurs through a specialized structural maintenance of chromosomes (SMC) complex, and explore the diversity of dosage compensation in the surrounding phylogeny of nematodes. Through phylogenetic analysis of the C. elegans dosage compensation complex and a survey of its epigenetic signatures, including X-specific topologically associating domains (TADs) and X-enrichment of H4K20me1, we found that the condensin-mediated mechanism evolved recently in the lineage leading to Caenorhabditis through an SMC-4 duplication. Intriguingly, an independent duplication of SMC-4 and the presence of X-specific TADs in Pristionchus pacificus suggest that condensin-mediated dosage compensation arose more than once. mRNA-seq analyses of gene expression in several nematode species indicate that dosage compensation itself is ancestral, as expected from the ancient XO sex determination system. Indicative of the ancestral mechanism, H4K20me1 is enriched on the X chromosomes in Oscheius tipulae, which does not contain X-specific TADs or SMC-4 paralogs. Together, our results indicate that the dosage compensation system in C. elegans is surprisingly new, and condensin may have been co-opted repeatedly in nematodes, suggesting that the process of evolving a chromosome-wide gene regulatory mechanism for dosage compensation is constrained.
2024-05-21 | GSE267962 | GEO
Project description:Mechanisms establishing higher-order chromosome structures and their roles in gene regulation are elusive. We analyzed chromosome architecture during nematode X-chromosome dosage compensation, which represses transcription via a dosage-compensation condensin complex (DCC) that binds hermaphrodite Xs and establishes megabase-size topologically associating domains (TADs). We show that DCC binding at high-occupancy sites (rex sites) defines eight TAD boundary locations. Single rex deletions disrupted boundaries, and single insertions created new boundaries, demonstrating one rex site is necessary and sufficient for DCC-dependent boundary formation. Deleting eight rex sites (8rexΔ) recapitulated TAD structure of DCC mutants, permitting analysis when chromosome-wide domain architecture was disrupted but most DCC binding remained. 8rexΔ animals exhibited no changes in X expression and lacked dosage-compensation mutant phenotypes. Hence, TAD boundaries are neither the cause nor consequence of gene repression during dosage compensation. Abrogating TAD structure did, however, reduce thermotolerance, accelerate aging, and shorten lifespan, implicating chromosome architecture in regulating stress responses and aging.
2019-09-05 | GSE128564 | GEO
Project description:Mechanisms of X chromosome dosage compensation have been studied extensively in a few model species representing clades of shared sex chromosome ancestry. However, the diversity within each clade as a function of sex chromosome evolution is largely unknown. Here, we anchor ourselves to the nematode Caenorhabditis elegans, for which a well-studied mechanism of dosage compensation occurs through a specialized structural maintenance of chromosomes (SMC) complex, and explore the diversity of dosage compensation in the surrounding phylogeny of nematodes. Through phylogenetic analysis of the C. elegans dosage compensation complex and a survey of its epigenetic signatures, including X-specific topologically associating domains (TADs) and X-enrichment of H4K20me1, we found that the condensin-mediated mechanism evolved recently in the lineage leading to Caenorhabditis through an SMC-4 duplication. Intriguingly, an independent duplication of SMC-4 and the presence of X-specific TADs in Pristionchus pacificus suggest that condensin-mediated dosage compensation arose more than once. mRNA-seq analyses of gene expression in several nematode species indicate that dosage compensation itself is ancestral, as expected from the ancient XO sex determination system. Indicative of the ancestral mechanism, H4K20me1 is enriched on the X chromosomes in Oscheius tipulae, which does not contain X-specific TADs or SMC-4 paralogs. Together, our results indicate that the dosage compensation system in C. elegans is surprisingly new, and condensin may have been co-opted repeatedly in nematodes, suggesting that the process of evolving a chromosome-wide gene regulatory mechanism for dosage compensation is constrained.
2024-05-21 | GSE267963 | GEO
Project description:Mechanisms establishing higher-order chromosome structures and their roles in gene regulation are elusive. We analyzed chromosome architecture during nematode X-chromosome dosage compensation, which represses transcription via a dosage-compensation condensin complex (DCC) that binds hermaphrodite Xs and establishes megabase-size topologically associating domains (TADs). We show that DCC binding at high-occupancy sites (rex sites) defines eight TAD boundary locations. Single rex deletions disrupted boundaries, and single insertions created new boundaries, demonstrating one rex site is necessary and sufficient for DCC-dependent boundary formation. Deleting eight rex sites (8rexΔ) recapitulated TAD structure of DCC mutants, permitting analysis when chromosome-wide domain architecture was disrupted but most DCC binding remained. 8rexΔ animals exhibited no changes in X expression and lacked dosage-compensation mutant phenotypes. Hence, TAD boundaries are neither the cause nor consequence of gene repression during dosage compensation. Abrogating TAD structure did, however, reduce thermotolerance, accelerate aging, and shorten lifespan, implicating chromosome architecture in regulating stress responses and aging.
2019-09-05 | GSE128566 | GEO
Project description:Mechanisms establishing higher-order chromosome structures and their roles in gene regulation are elusive. We analyzed chromosome architecture during nematode X-chromosome dosage compensation, which represses transcription via a dosage-compensation condensin complex (DCC) that binds hermaphrodite Xs and establishes megabase-size topologically associating domains (TADs). We show that DCC binding at high-occupancy sites (rex sites) defines eight TAD boundary locations. Single rex deletions disrupted boundaries, and single insertions created new boundaries, demonstrating one rex site is necessary and sufficient for DCC-dependent boundary formation. Deleting eight rex sites (8rexΔ) recapitulated TAD structure of DCC mutants, permitting analysis when chromosome-wide domain architecture was disrupted but most DCC binding remained. 8rexΔ animals exhibited no changes in X expression and lacked dosage-compensation mutant phenotypes. Hence, TAD boundaries are neither the cause nor consequence of gene repression during dosage compensation. Abrogating TAD structure did, however, reduce thermotolerance, accelerate aging, and shorten lifespan, implicating chromosome architecture in regulating stress responses and aging.
2019-09-05 | GSE128559 | GEO
Project description:Condensins are multi-subunit protein complexes that regulate chromosome structure throughout cell-cycle. Metazoans contain two types of condensin complexes (I and II) with essential and distinct functions. In C. elegans a third type of condensin (IDC) functions as part of the X chromosome dosage compensation complex1,2. We mapped genome-wide binding sites of the three condensin types in C. elegans embryos. Characteristics of condensin binding are similar between condensin types.
2013-09-16 | GSE45678 | GEO
Project description:The three-dimensional (3D) organization of a genome plays a critical role in regulating gene expression, yet little is known about the machinery and mechanisms that determine higher-order chromosome structure or how structure influences gene expression. Here we exploit the X-chromosome-wide process of dosage compensation to dissect these mechanisms. The dosage compensation complex (DCC) of C. elegans, a condensin complex, binds to both X chromosomes of hermaphrodites via sequence-specific recruitment sites (rex sites) to reduce chromosome-wide gene expression by half. Using genome-wide chromosome conformation capture and single-cell FISH to compare chromosome structure in wild-type and DCC-defective embryos (DC mutants), we show that the DCC remodels X chromosomes of hermaphrodites into a spatial conformation distinct from autosomes. The dosage-compensated X chromosomes are composed of Topologically Associating Domains (TADs) that have sharper boundaries and more regular spacing than TADs on autosomes. Most TAD boundaries on X coincide with the highest-affinity rex sites, and these boundaries are lost or diminished in DC mutants, thereby restoring the topology of X to a native conformation resembling that of autosomes. Although most rex sites engage in multiple strong DCC-dependent long-range interactions, the strongest interactions occur between rex sites at the DCC-dependent TAD boundaries. We propose the DCC actively shapes the topology of the entire X chromosome by forming new TAD boundaries and reinforcing pre-existing weak TAD boundaries through interactions between its highest affinity sites. Such changes in higher-order X-chromosome structure then influence gene expression over long distances.
2015-06-03 | GSE59597 | GEO