Arabidopsis thaliana
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA261254 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR1594160.fastq.gz | Fastqsanger.gz | |||
| SRR1594170.fastq.gz | Fastqsanger.gz | |||
| SRR1594180.fastq.gz | Fastqsanger.gz | |||
| SRR1594190.fastq.gz | Fastqsanger.gz | |||
| SRR1594200.fastq.gz | Fastqsanger.gz |
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Project description:The centromere, as an essential element to control chromosome segregation, is epigenetically determined by CENH3-containing nucleosomes as a functional marker, therefore the accurate deposition of CENH3 is crucial to chromosome transmission. We characterized the deposition of CENH3 in maize by over-expression and mutational analysis. Our results revealed that over-expressing CENH3 in callus is lethal while over-expressing GFP-CENH3 and CENH3-YFP in callus and plants is not and can be partly deposited normally. Different mutations of GFP-CENH3 demonstrated that CENH3-Thr4 in the N terminus was needed for the deposition as a positive phosphorylation site and the last five amino acids in the C terminus are necessary for deposition. The C terminal tail of CENH3 is confirmed to be responsible for the interaction of CENH3 and histone H4, which indicates that CENH3 maintains deposition in centromeres via interacting with H4 to form stable nucleosomes. For GFP-CENH3 and CENH3-YFP, the fused tags at the termini probably affect the structure of CENH3 and reduce its interaction with other proteins, which in turn could decrease proper deposition. Taken together, multiple amino acids or motifs were shown to play essential roles in CENH3 deposition, which is suggested to be affected by numerous factors in maize.
2020-06-01 | GSE133578 | GEO
Project description:Centromeres are essential to ensure proper chromosome segregation in eukaryotes. Their definition relies on the presence of a centromere-specific H3 histone variant CenH3, known as CENP-A in mammals. Its overexpression in aggressive cancers raises questions concerning its effect on chromatin dynamics and contribution to tumorigenesis. We find that CenH3 overexpression in human cells leads to ectopic enrichment at sites of active histone turnover. Furthermore, in over-expressing conditions, we see the formation of a novel heterotypic particle (CenH3-H4/H3.3-H4) that occludes CTCF binding, but this occlusion has only a minor effect on gene expression. Ectopic localization and CTCF occlusion depends on the H3.3 chaperone DAXX, rather than its dedicated chaperone HJURP. This DAXX-dependent occlusion also occurs in naturally overexpressing cancer cells. Furthermore, our cellular model reveals a DAXX-dependent survival advantage when challenged by DNA damage. Our findings illustrate how changes in histone variant levels can disrupt chromatin dynamics in disease and provides a possible mechanism for cell resistance to anti-cancer treatments. Examination of CenH3 ChIP-seq and RNA-seq transcriptional programs in two conditions - WT and CenH3 over-expressing.
2014-02-12 | E-GEOD-42951 | biostudies-arrayexpress
Project description:Centromeres are essential to ensure proper chromosome segregation in eukaryotes. Their definition relies on the presence of a centromere-specific H3 histone variant CenH3, known as CENP-A in mammals. Its overexpression in aggressive cancers raises questions concerning its effect on chromatin dynamics and contribution to tumorigenesis. We find that CenH3 overexpression in human cells leads to ectopic enrichment at sites of active histone turnover. Furthermore, in over-expressing conditions, we see the formation of a novel heterotypic particle (CenH3-H4/H3.3-H4) that occludes CTCF binding, but this occlusion has only a minor effect on gene expression. Ectopic localization and CTCF occlusion depends on the H3.3 chaperone DAXX, rather than its dedicated chaperone HJURP. This DAXX-dependent occlusion also occurs in naturally overexpressing cancer cells. Furthermore, our cellular model reveals a DAXX-dependent survival advantage when challenged by DNA damage. Our findings illustrate how changes in histone variant levels can disrupt chromatin dynamics in disease and provides a possible mechanism for cell resistance to anti-cancer treatments.
2014-02-12 | GSE42951 | GEO
Project description:Accurate chromosome segregation requires assembly of the multiprotein kinetochore complex at centromeres. In most eukaryotes, kinetochore assembly is primed by the histone H3 variant CenH3, which physically interacts with components of the inner kinetochore constitutive-centromere-associated-network (CCAN). Unexpected to its critical function, previous work identified that select eukaryotic lineages, including several insects, have lost CenH3, while having retained homologs of the CCAN. These findings imply alternative CCAN assembly pathways in these organisms that function in CenH3-independent manners. Here, we study the composition and assembly of CenH3-independent kinetochores of Lepidoptera. We show that lepidopteran kinetochores consist of previously identified CCAN homologs as well as additional components including a divergent CENP-T homolog, which are required for accurate mitotic progression. Our study focuses on CENP-T that we find both necessary and sufficient to recruit the Mis12 outer kinetochore complex. In addition, CRISPR-mediated gene editing in Bombyx mori establishes an essential function of CENP-T in vivo. Finally, the retention of CENP-T homologs in other independently-derived CenH3-deficient insects indicates a conserved mechanism of kinetochore assembly between these lineages. Our study provides the first functional insights into CCAN-based kinetochore assembly pathways that function independently of CenH3, thus contributing to the emerging picture of an unexpected plasticity to build a kinetochore.
2020-02-18 | PXD016092 | Pride
Project description:Correct localization of the centromeric histone variant CenH3/CENP-A/Cse4 is an important part of faithful chromosome segregation. Mislocalization of CenH3 could lead to ectopic centromere formation and missegregation, and could affect DNA replication and transcription. CENP-A is often overexpressed and mislocalized in cancer genomes, but the underlying mechanisms are not understood. One major regulator of Cse4 deposition is Psh1, an E3 ubiquitin ligase that controls levels of Cse4 to prevent deposition into noncentromeric regions. We present evidence that Chromatin assembly factor-1 (CAF-1), an evolutionarily conserved histone H3/H4 chaperone shown previously to interact with CenH3 in flies and human cells, regulates Cse4 deposition in budding yeast. Yeast CAF-1 (yCAF-1) is a heterotrimeric protein complex consisting of CAC1, CAC2, and CAC3, which interacts with Cse4, and can assemble Cse4 nucleosomes in vitro. yCAF-1 regulates the stability of both soluble and chromatin associated Cse4. Loss of yCAF-1 can rescue growth defects and changes in gene expression associated with Cse4 deposition that occur in the absence of Psh1-mediated proteolysis. Incorporation of Cse4 into promoter nucleosomes at transcriptionally active genes depends on yCAF-1. Overall our findings suggest CAF-1 can act as a CenH3 chaperone, regulating levels and incorporation of CenH3 in chromatin. Furthermore, the misincorporation of CenH3 at promoter regions may have negative consequences for gene expression.
2017-09-01 | GSE98396 | GEO
Project description:Correct localization of the centromeric histone variant CenH3/CENP-A/Cse4 is an important part of faithful chromosome segregation. Mislocalization of CenH3 could lead to ectopic centromere formation and missegregation, and could affect DNA replication and transcription. CENP-A is often overexpressed and mislocalized in cancer genomes, but the underlying mechanisms are not understood. One major regulator of Cse4 deposition is Psh1, an E3 ubiquitin ligase that controls levels of Cse4 to prevent deposition into noncentromeric regions. We present evidence that Chromatin assembly factor-1 (CAF-1), an evolutionarily conserved histone H3/H4 chaperone shown previously to interact with CenH3 in flies and human cells, regulates Cse4 deposition in budding yeast. Yeast CAF-1 (yCAF-1) is a heterotrimeric protein complex consisting of CAC1, CAC2, and CAC3, which interacts with Cse4, and can assemble Cse4 nucleosomes in vitro. yCAF-1 regulates the stability of both soluble and chromatin associated Cse4. Loss of yCAF-1 can rescue growth defects and changes in gene expression associated with Cse4 deposition that occur in the absence of Psh1-mediated proteolysis. Incorporation of Cse4 into promoter nucleosomes at transcriptionally active genes depends on yCAF-1. Overall our findings suggest CAF-1 can act as a CenH3 chaperone, regulating levels and incorporation of CenH3 in chromatin. Furthermore, the misincorporation of CenH3 at promoter regions may have negative consequences for gene expression.
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Project description:Centromeres typically contain repeat sequences, but centromere function does not necessarily depend on these sequences. In aneuploid wheat (Triticum aestivum) and wheat distant hybridization offspring, we found functional centromeres with dramatic changes to centromeric retrotransposon of wheat (CRW) sequences. CRW sequences were greatly reduced in the ditelosomic lines 1BS, 5DS, 5DL, and a wheat-Thinopyrum elongatum addition line. CRWs were completely lost in the ditelosomic line 4DS, but a 994 kb ectopic genomic DNA sequence was involved in de novo centromere formation on the 4DS chromosome. In addition, two ectopic sequences were incorporated in a de novo centromere in a wheat-Th. intermedium addition line. Centromeric sequences were also expanded to the chromosome arm in wide hybridizations. Stable alien chromosomes with two and three regions containing centromeric sequences were found in wheat-Th. elongatum hybrid derivatives, but only one is functional. In wheat-rye (Secale cereale) hybrids, rye centromere specific sequences spread to the chromosome arm and may cause centromere expansion. Thus, distant wheat hybridizations cause frequent and significant changes to the centromere via centromere misdivision, which may affect retention or loss of alien chromosomes in hybrids. ChIP-seq was carried out with anti-CENH3 antibody using material 4DS and control (Chinese Spring, CS as short).
2016-04-02 | E-GEOD-63752 | biostudies-arrayexpress
Project description:During mitosis, the genome is restructured to facilitate chromosome segregation, accompanied by dramatic changes in gene expression. However, the mechanisms that underlie mitotic transcriptional regulation are unclear. In contrast to transcribed genes, centromere regions retain transcriptionally active RNA Polymerase II (RNAPII) in mitosis. Here, we demonstrate that chromosome-localized cohesin is necessary and sufficient to retain active RNAPII on mitotic centromeres. Failure to remove cohesin from mitotic chromosome arms dramatically alters mitotic gene expression, and results in a failure to release elongating RNAPII and nascent transcripts from mitotic chromosomes. We propose that prophase cohesin removal is the key step in reprogramming gene expression as cells transition from G2 to mitosis, and is temporally coupled with chromosome condensation to coordinate chromosome segregation with changes in gene expression.
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2020-01-30 | GSE139846 | GEO
Project description:During mitosis, the genome is restructured to facilitate chromosome segregation, accompanied by dramatic changes in gene expression. However, the mechanisms that underlie mitotic transcriptional regulation are unclear. In contrast to transcribed genes, centromere regions retain transcriptionally active RNA Polymerase II (RNAPII) in mitosis. Here, we demonstrate that chromosome-localized cohesin is necessary and sufficient to retain active RNAPII on mitotic centromeres. Failure to remove cohesin from mitotic chromosome arms dramatically alters mitotic gene expression, and results in a failure to release elongating RNAPII and nascent transcripts from mitotic chromosomes. We propose that prophase cohesin removal is the key step in reprogramming gene expression as cells transition from G2 to mitosis, and is temporally coupled with chromosome condensation to coordinate chromosome segregation with changes in gene expression.
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