Arabidopsis thaliana
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA219442 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:Histone variants play crucial roles in gene expression, genome integrity and chromosome segregation. However, to what extent histone variants control chromatin architecture remains largely unknown. Here, we show that the previously uncharacterized histone variant H2A.W plays a crucial role in condensation of heterochromatin. Genome-wide profiling of all four types of H2A variants in Arabidopsis shows that H2A.W specifically associates with heterochromatin. H2A.W recruitment is independent of heterochromatic marks H3K9me2 and DNA methylation. Genetic interactions show that H2A.W acts in synergy with CMT3 mediated methylation to maintain genome integrity. In vitro, H2A.W enhances chromatin condensation through a higher propensity to make fiber-to-fiber interactions via its conserved C-terminal motif. In vivo, elimination of H2A.W causes decondensation of heterochromatin and conversely, ectopic expression of H2A.W promotes heterochromatin condensation. These results demonstrate that H2A.W plays critical roles in heterochromatin by promoting higher order chromatin condensation. Since similar H2A.W C-terminal motifs are present in other variant found in mammals and other organisms our findings impact our understanding of heterochromatin condensation in a wide variety of eukaryotic organisms. Two mRNA-seq samples, two bisulfite-seq samples, six ChIP-seq samples.
2014-07-05 | E-GEOD-50942 | biostudies-arrayexpress
Project description:Histone variants play crucial roles in gene expression, genome integrity and chromosome segregation. However, to what extent histone variants control chromatin architecture remains largely unknown. Here, we show that the previously uncharacterized histone variant H2A.W plays a crucial role in condensation of heterochromatin. Genome-wide profiling of all four types of H2A variants in Arabidopsis shows that H2A.W specifically associates with heterochromatin. H2A.W recruitment is independent of heterochromatic marks H3K9me2 and DNA methylation. Genetic interactions show that H2A.W acts in synergy with CMT3 mediated methylation to maintain genome integrity. In vitro, H2A.W enhances chromatin condensation through a higher propensity to make fiber-to-fiber interactions via its conserved C-terminal motif. In vivo, elimination of H2A.W causes decondensation of heterochromatin and conversely, ectopic expression of H2A.W promotes heterochromatin condensation. These results demonstrate that H2A.W plays critical roles in heterochromatin by promoting higher order chromatin condensation. Since similar H2A.W C-terminal motifs are present in other variant found in mammals and other organisms our findings impact our understanding of heterochromatin condensation in a wide variety of eukaryotic organisms.
2014-07-05 | GSE50942 | GEO
Project description:Heterochromatin of flowering plants is occupied by histone variant H2A.W and marked by DNA and H3K9 methylation. The relative impact of these heterochromatic features on activity of Transposable Elements (TEs) remains largely unknown. We obtained mutants deficient for H2A.W and key components controlling each of the key heterochromatic pathway in Arabidopsis and observed that knock out of individual pathway does not affect in a major manner TEs activity. However, when we combine the loss of H2A.W with any of the other heterochromatin controller we observe synergistic effects on heterochromatin compaction as well TEs activity. H2A.W appears to control expression of all TEs while each other heterochromatin controller target distinct subsets of TEs. We also observe an impact of linker histone H1. We propose that H2A.W acts together with several components of heterochromatin to prevents activity of distinct sets of TEs activity and chromatin architecture. Synergistic action with H2A.W is more prominent specifically in pathways controlled by the plant specific DNA chromomethyltransferases, CMT2 and CMT3.
2022-12-31 | GSE116643 | GEO
Project description:DNA double strand break (DSB) repair depends on the ataxia telangiectasia mutated (ATM) kinase that phosphorylates the conserved C-terminal SQ motif present in the histone variant H2A.X [1-7]. In constitutive heterochromatin of mammals, DSB repair is delayed and relies on phosphorylation of the proteins HP1 and KAP1 by ATM [2, 8-14]. However, KAP1 is not conserved in plants and the HP1 related protein Like-HP1 (LHP1) is not localized at constitutive heterochromatin [15], suggesting that in plants, alternative mechanisms could be responsible for repair of DSBs in heterochromatin. In Arabidopsis, constitutive heterochromatin is marked by H3K9 methylation, and the plant-specific histone variants H2A.W which are distinguished by their C-terminal motif KSPKK and required for heterochromatin compaction [16-18]. We report that the Arabidopsis histone variant H2A.W.7 is confined to heterochromatin and carries a SQ motif that is phosphorylated by ATM. In response to DNA damage, phosphorylation of H2A.W.7 takes place in heterochromatin while H2A.X phosphorylation takes place primarily in euchromatin. We propose that H2A.W.7 evolved in addition to H2A.X to facilitate DNA damage response in highly condensed heterochromatin, thus playing a role similar to KAP1 and HP1 phosphorylation in mammals. These data support the idea of the functional diversification of histone variants and their role in spatial compartmentalization of chromatin related functions in eukaryotes.
2017-03-02 | GSE95557 | GEO
Project description:Diversification of histone variants is marked by the acquisition of distinct motifs and features through convergent evolution. H2A variants tend to be associated with defined domains of the genome. Specific features distinguish H2A variants in eukaryotes but whether evolution of these features predated the evolution of deposition mechanisms or vice-versa has remained unclear.In flowering plants, the variant H2A.W is tightly associated with heterochromatin. H2A.W evolved in land plants through acquisition of an extended C-terminal tail enriched with basic residues and a KSPK motif. Here, we used a synthetic approach in fission yeast, which lacks H2A.W and its dedicated deposition mechanism, to recapitulate the evolutionary steps that led to H2A.W and to assess the impact of the KSPK motif on heterochromatin composition and its properties. In conclusion, the acquisition of the KSPK motif in yeast promotes chromatin properties that are comparable to the properties and function of H2A.W in plant heterochromatin. Hence, the KSPK motif could have been selected before the evolution of direct heterochromatin deposition mechanisms. We propose that the acquisition of functional histone variant motifs can confer properties which affect only specific chromatin states, thereby driving the evolution of specific deposition mechanisms.
2020-08-23 | GSE152081 | GEO
Project description:Diversification of histone variants is marked by the acquisition of distinct motifs and features through convergent evolution. H2A variants tend to be associated with defined domains of the genome. Specific features distinguish H2A variants in eukaryotes but whether evolution of these features predated the evolution of deposition mechanisms or vice-versa has remained unclear.In flowering plants, the variant H2A.W is tightly associated with heterochromatin. H2A.W evolved in land plants through acquisition of an extended C-terminal tail enriched with basic residues and a KSPK motif. Here, we used a synthetic approach in fission yeast, which lacks H2A.W and its dedicated deposition mechanism, to recapitulate the evolutionary steps that led to H2A.W and to assess the impact of the KSPK motif on heterochromatin composition and its properties. In conclusion, the acquisition of the KSPK motif in yeast promotes chromatin properties that are comparable to the properties and function of H2A.W in plant heterochromatin. Hence, the KSPK motif could have been selected before the evolution of direct heterochromatin deposition mechanisms. We propose that the acquisition of functional histone variant motifs can confer properties which affect only specific chromatin states, thereby driving the evolution of specific deposition mechanisms.
2020-08-23 | GSE152085 | GEO
Project description:Diversification of histone variants is marked by the acquisition of distinct motifs and features through convergent evolution. H2A variants tend to be associated with defined domains of the genome. Specific features distinguish H2A variants in eukaryotes but whether evolution of these features predated the evolution of deposition mechanisms or vice-versa has remained unclear.In flowering plants, the variant H2A.W is tightly associated with heterochromatin. H2A.W evolved in land plants through acquisition of an extended C-terminal tail enriched with basic residues and a KSPK motif. Here, we used a synthetic approach in fission yeast, which lacks H2A.W and its dedicated deposition mechanism, to recapitulate the evolutionary steps that led to H2A.W and to assess the impact of the KSPK motif on heterochromatin composition and its properties. In conclusion, the acquisition of the KSPK motif in yeast promotes chromatin properties that are comparable to the properties and function of H2A.W in plant heterochromatin. Hence, the KSPK motif could have been selected before the evolution of direct heterochromatin deposition mechanisms. We propose that the acquisition of functional histone variant motifs can confer properties which affect only specific chromatin states, thereby driving the evolution of specific deposition mechanisms.
2020-08-23 | GSE152083 | GEO
Project description:In flowering plants, heterochromatin is demarcated by the histone variant H2A.W, elevated levels of the linker histone H1, and specific epigenetic modifications, such as high levels of DNA methylation at both CG and non-CG sites. How H2A.W regulates heterochromatin organization and interacts with other heterochromatic features is unclear. Here, we create an h2a.w null mutant via CRISPR-Cas9, h2a.w-2, to analyze the in vivo function of H2A.W. We find that H2A.W antagonizes deposition of H1 at heterochromatin and that non-CG methylation and accessibility are moderately decreased in h2a.w-2 heterochromatin. Compared to H1 loss alone, combined loss of H1 and H2A.W greatly increases accessibility and facilitates non-CG DNA methylation in heterochromatin, suggesting co-regulation of heterochromatic features by H2A.W and H1. Our results suggest that H2A.W helps maintain optimal heterochromatin accessibility and DNA methylation by promoting chromatin compaction together with H1, while also inhibiting excessive H1 incorporation.
2021-03-26 | GSE146948 | GEO
Project description:Programmed constitutive heterochromatin silencing is essential for eukaryotic genome regulation, yet the initial step of this process is ambiguous. A large proportion of R-loops (RNA:DNA hybrids) had been unexpectedly identified within Arabidopsis pericentromeric heterochromatin with unknown functions. Through a genome-wide R-loop profiling screen, we find DDM1 (Decrease in DNA Methylation 1) is the primary restrictor of pericentromeric R-loops via its RNA:DNA helicase activity. Low levels of pericentromeric R-loops resolved by DDM1 co-transcriptionally can prime constitutive heterochromatin silencing. Furthermore, we demonstrate that DDM1 physically excludes histone H2A variant H2A.Z, and promotes H2A.W deposition for faithful heterochromatin initiation soon after R-loop clearance. The dual functions of DDM1 in R-loop resolution and H2A.Z eviction are essential for sperm nuclei structure maintenance in mature pollen. Our work unravels the co-transcriptional R-loop resolution coupled with accurate H2A variants deposition is the primary step of constitutive heterochromatin silencing in Arabidopsis, which might be conserved across eukaryotes.
2023-08-21 | GSE218066 | GEO
Project description:Programmed constitutive heterochromatin silencing is essential for eukaryotic genome regulation, yet the initial step of this process is ambiguous. A large proportion of R-loops (RNA:DNA hybrids) had been unexpectedly identified within Arabidopsis pericentromeric heterochromatin with unknown functions. Through a genome-wide R-loop profiling screen, we find DDM1 (Decrease in DNA Methylation 1) is the primary restrictor of pericentromeric R-loops via its RNA:DNA helicase activity. Low levels of pericentromeric R-loops resolved by DDM1 co-transcriptionally can prime constitutive heterochromatin silencing. Furthermore, we demonstrate that DDM1 physically excludes histone H2A variant H2A.Z, and promotes H2A.W deposition for faithful heterochromatin initiation soon after R-loop clearance. The dual functions of DDM1 in R-loop resolution and H2A.Z eviction are essential for sperm nuclei structure maintenance in mature pollen. Our work unravels the co-transcriptional R-loop resolution coupled with accurate H2A variants deposition is the primary step of constitutive heterochromatin silencing in Arabidopsis, which might be conserved across eukaryotes.
2023-08-21 | GSE217682 | GEO