Linker histone H1 prevents R-loop accumulation and genome instability in heterochromatin [ChIP Seq]
Ontology highlight
ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE99004 | GEO | 2017/08/18
SECONDARY ACCESSION(S): PRJNA386953
REPOSITORIES: GEO
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Project description:Genome wide distribution of R-loops in Wild Type and RNAi dH1 Drosophila melanogaster S2 cells
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Project description:Linker histone H1 is an important structural component of chromatin that stabilizes the nucleosome and compacts the nucleofilament into higher-order structures. The biology of histone H1 remains, however, poorly understood. Here we show that Drosophila histone H1 (dH1) prevents genome instability as indicated by the increased γH2Av (H2AvS137P) content and the high incidence of DNA breaks and sister-chromatid exchanges observed in dH1-depleted cells. Increased γH2Av occurs preferentially at heterochromatic elements, which are upregulated upon dH1 depletion, and is due to the abnormal accumulation of DNA:RNA hybrids (R-loops). R-loops accumulation is readily detectable in G1-phase, whereas γH2Av increases mainly during DNA replication. These defects induce JNK-mediated apoptosis and are specific of dH1 depletion since they are not observed when heterochromatin silencing is relieved by HP1a depletion. Altogether, our results suggest that histone H1 prevents R-loops-induced DNA damage in heterochromatin and unveil its essential contribution to maintenance of genome stability.While structural importance of linker histone H1 in packaging eukaryotic genome into chromatin is well known, its biological function remains poorly understood. Here the authors reveal that Drosophila linker histone H1 prevents DNA:RNA hybrids accumulation and genome instability in heterochromatin.
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Project description:This SuperSeries is composed of the SubSeries listed below.
2017-08-18 | GSE99016 | GEO
Project description:Linker histone H1 prevents R-loop accumulation and genome instability in heterochromatin
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Project description:Chromosomal RNAs (cRNAs) are a poorly understood fraction of cellular RNAs that co-purify with chromatin. Here we show that, in Drosophila, cRNAs constitute a heterogeneous group of RNA species that cover ~28% of the genome. Intriguingly, we found that cRNAs are highly enriched in heterochromatic transcripts. Our results show that heterochromatic cRNAs interact with the hnRNP A/B proteins hrp36 and hrp48 to assemble into RNP particles. We also show that depletion of linker histone dH1, a major component of chromatin, impairs assembly of hrp36 and hrp48 onto heterochromatic cRNAs. Concomitantly, impaired cRNAs assembly induces the accumulation of heterochromatic cRNAs and the formation of unscheduled RNA::DNA hybrids (R-loops). Linker histones H1 are known to regulate chromatin structure and compaction and, indeed, we show that dH1 depletion perturbs chromatin organization, reducing nucleosome occupancy and specifically increasing accessibility and 3D interactions within heterochromatin. These perturbations facilitate annealing of cRNAs to the DNA template, enhancing R-loops formation and cRNAs retention at heterochromatin. Altogether, these results unveil the unexpected contribution of linker histones to RNPs assembly and homeostasis of cRNAs.
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Project description:Chromosomal RNAs (cRNAs) are a poorly understood fraction of cellular RNAs that co-purify with chromatin. Here we show that, in Drosophila, cRNAs constitute a heterogeneous group of RNA species that cover ~28% of the genome. Intriguingly, we found that cRNAs are highly enriched in heterochromatic transcripts. Our results show that heterochromatic cRNAs interact with the hnRNP A/B proteins hrp36 and hrp48 to assemble into RNP particles. We also show that depletion of linker histone dH1, a major component of chromatin, impairs assembly of hrp36 and hrp48 onto heterochromatic cRNAs. Concomitantly, impaired cRNAs assembly induces the accumulation of heterochromatic cRNAs and the formation of unscheduled RNA::DNA hybrids (R-loops). Linker histones H1 are known to regulate chromatin structure and compaction and, indeed, we show that dH1 depletion perturbs chromatin organization, reducing nucleosome occupancy and specifically increasing accessibility and 3D interactions within heterochromatin. These perturbations facilitate annealing of cRNAs to the DNA template, enhancing R-loops formation and cRNAs retention at heterochromatin. Altogether, these results unveil the unexpected contribution of linker histones to RNPs assembly and homeostasis of cRNAs.
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Project description:Chromosomal RNAs (cRNAs) are a poorly understood fraction of cellular RNAs that co-purify with chromatin. Here we show that, in Drosophila, cRNAs constitute a heterogeneous group of RNA species that cover ~28% of the genome. Intriguingly, we found that cRNAs are highly enriched in heterochromatic transcripts. Our results show that heterochromatic cRNAs interact with the hnRNP A/B proteins hrp36 and hrp48 to assemble into RNP particles. We also show that depletion of linker histone dH1, a major component of chromatin, impairs assembly of hrp36 and hrp48 onto heterochromatic cRNAs. Concomitantly, impaired cRNAs assembly induces the accumulation of heterochromatic cRNAs and the formation of unscheduled RNA::DNA hybrids (R-loops). Linker histones H1 are known to regulate chromatin structure and compaction and, indeed, we show that dH1 depletion perturbs chromatin organization, reducing nucleosome occupancy and specifically increasing accessibility and 3D interactions within heterochromatin. These perturbations facilitate annealing of cRNAs to the DNA template, enhancing R-loops formation and cRNAs retention at heterochromatin. Altogether, these results unveil the unexpected contribution of linker histones to RNPs assembly and homeostasis of cRNAs.
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Project description:Chromosomal RNAs (cRNAs) are a poorly understood fraction of cellular RNAs that co-purify with chromatin. Here we show that, in Drosophila, cRNAs constitute a heterogeneous group of RNA species that cover ~28% of the genome. Intriguingly, we found that cRNAs are highly enriched in heterochromatic transcripts. Our results show that heterochromatic cRNAs interact with the hnRNP A/B proteins hrp36 and hrp48 to assemble into RNP particles. We also show that depletion of linker histone dH1, a major component of chromatin, impairs assembly of hrp36 and hrp48 onto heterochromatic cRNAs. Concomitantly, impaired cRNAs assembly induces the accumulation of heterochromatic cRNAs and the formation of unscheduled RNA::DNA hybrids (R-loops). Linker histones H1 are known to regulate chromatin structure and compaction and, indeed, we show that dH1 depletion perturbs chromatin organization, reducing nucleosome occupancy and specifically increasing accessibility and 3D interactions within heterochromatin. These perturbations facilitate annealing of cRNAs to the DNA template, enhancing R-loops formation and cRNAs retention at heterochromatin. Altogether, these results unveil the unexpected contribution of linker histones to RNPs assembly and homeostasis of cRNAs.
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Project description:Chromosomal RNAs (cRNAs) are a poorly understood fraction of cellular RNAs that co-purify with chromatin. Here we show that, in Drosophila, cRNAs constitute a heterogeneous group of RNA species that cover ~28% of the genome. Intriguingly, we found that cRNAs are highly enriched in heterochromatic transcripts. Our results show that heterochromatic cRNAs interact with the hnRNP A/B proteins hrp36 and hrp48 to assemble into RNP particles. We also show that depletion of linker histone dH1, a major component of chromatin, impairs assembly of hrp36 and hrp48 onto heterochromatic cRNAs. Concomitantly, impaired cRNAs assembly induces the accumulation of heterochromatic cRNAs and the formation of unscheduled RNA::DNA hybrids (R-loops). Linker histones H1 are known to regulate chromatin structure and compaction and, indeed, we show that dH1 depletion perturbs chromatin organization, reducing nucleosome occupancy and specifically increasing accessibility and 3D interactions within heterochromatin. These perturbations facilitate annealing of cRNAs to the DNA template, enhancing R-loops formation and cRNAs retention at heterochromatin. Altogether, these results unveil the unexpected contribution of linker histones to RNPs assembly and homeostasis of cRNAs.
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