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Linker histone H1 prevents R-loop accumulation and genome instability in heterochromatin.

ABSTRACT: 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 ?H2Av (H2AvS137P) content and the high incidence of DNA breaks and sister-chromatid exchanges observed in dH1-depleted cells. Increased ?H2Av 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 ?H2Av 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.

SUBMITTER: Bayona-Feliu A

PROVIDER: S-EPMC5561251 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Linker histone H1 prevents R-loop accumulation and genome instability in heterochromatin.

Bayona-Feliu Aleix A Casas-Lamesa Anna A Reina Oscar O Bernués Jordi J Azorín Fernando F

Nature communications 20170818 1

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 heter ...[more]

PMID: 28819201

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Project description:Parental exposure to environmental stress can result in an increased diseases risk in the offspring. Although literature on maternal contribution to hereditary diseases are growing, the paternal contribution is frequently underrecognized. Since human studies reported that 80% of transmitted mutations arise in the paternal germline, it is crucial to understand the mechanism underlying the paternally inherited genome instability. Ionizing radiation (IR) is a major source of mutagenesis through inducing DNA double-strand breaks (DSBs). Here, we used sex-separated C. elegans mutants to investigate the paternal contribution to IR-induced transgenerational effects. Specifically, we found that paternal exposure to IR leads to a transgenerational embryonic lethality, and this effect is only observed when the radiation exposure occurred close to the time of fertilization. In the offspring of the irradiated males (F1 generation), we detected various genome instability phenotypes, including DNA fragmentation, chromosomal rearrangement, and aneuploidy. These phenotypes are attributed to the usage of two error-prone repair machinery, the polymerase-theta mediated end joining (TMEJ) and the non-homologous End Joining (NHEJ). Surprisingly, depletion of a human histone H1.0 ortholog, HIS-24, can significantly rescue this transgenerational embryonic lethality. Moreover, this rescue effect is associated with the downregulation of heterochromatin marker histone 3 lysine 9 di-methylation (H3K9me2), and the knocking-down of heterochromatin protein, HPL-1, could mimic the rescue effect of HIS-24 depletion. We also noticed that removal of the histone H1 and heterochromatin marker could activate the error-free repair machinery, Homologous Recombination repair (HR), thus improving the viability of the offspring carrying paternally inherited DNA damage. Altogether, our work sheds light on the importance of paternal radiation exposure on the health of offspring. In addition, our work establishes a previously unknown mechanism underlying the transgenerational genome instability and provides a potential therapeutic target for preventing the hereditary diseases caused by paternal radiation exposure.

Dataset Information

Linker histone H1 prevents R-loop accumulation and genome instability in heterochromatin.

Publications

Linker histone H1 prevents R-loop accumulation and genome instability in heterochromatin.

Similar Datasets

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