Harmful R loops are prevented via different cell cycle specific mechanisms
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PROVIDER: PRJNA670705 | ENA |
REPOSITORIES: ENA
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Project description:R loops induce transcription-replication (T-R) conflicts, but recent reports have suggested that R-loops are caused by T-R conflicts. Identifying how R loops are generated is crucial to know how transcription compromise genome integrity. Genome-wide analyses of conditional yeast mutants reveal that transcription factors, such as the THO complex. prevents R loop formation in G1 and S-phase, whereas the Sen1 DNA-RNA helicase prevents them only in S-phase. Interestingly, damage accumulates asymmetrically downstream of the RF in sen1 cells but symmetrically in the hpr1 THO mutant. Our results unambiguously indicate that: R loops forms co-transcriptionally independently of DNA replication; THO is a general and cell-cycle independent safeguard against R loops, and Sen1, in contrast to previously believed, is an S-phase-specific R loop resolvase. These conclusions have important implications for the mechanism of R loop formation and the role of other factors reported to impact on R loop homeostasis
2021-07-22 | GSE159870 | GEO
Project description: Not available
| S-EPMC8298424 | biostudies-literature
Project description:Non-scheduled R loops represent a major source of DNA damage and replication stress. Cells have different ways to prevent R loop accumulation. One mechanism relies on the conserved THO complex in association with co-transcriptional RNA processing factors including the RNA-dependent ATPase UAP56/DDX39B and histone modifiers such as the SIN3 deacetylase in humans. We investigated the function of UAP56/DDX39B in R loop removal. We show that UAP56 depletion causes R loop accumulation, R loop-mediated genome instability and replication fork stalling. We demonstrate an RNA-DNA helicase activity in UAP56 and that its overexpression suppresses R loops and genome instability induced by depleting 5 different unrelated factors. UAP56/DDX39B localizes to active chromatin and prevents the accumulation of RNA-DNA hybrids over the entire genome. We propose that, in addition to its RNA processing role, UAP56/DDX39B is a key helicase required to eliminate harmful co-transcriptional RNA structures that otherwise would block transcription and replication.
2020-05-25 | GSE127979 | GEO
Project description:The formation of R-loops is a natural consequence of the transcription process, caused by invasion of the DNA duplex by nascent transcripts. These structures have been considered rare transcriptional by-products with potential harmful effects on genome integrity, due to the fragility of the displaced DNA coding strand. However R-loops may also possess beneficial effects as their widespread formation has been detected over CpG island promoters in human genes. Furthermore we have previously shown that R-loops are particularly enriched over G-rich terminator elements. These facilitate RNA polymerase II (Pol II) pausing prior to efficient termination. Here we reveal an unanticipated link between R-loops and RNA interference (RNAi)-dependent H3K9me2 formation over pause site termination regions of mammalian protein coding genes. We show that R-loops induce antisense transcription over these pause elements which in turn lead to the generation of double-strand RNA (dsRNA) and recruitment of Dicer, Ago1, Ago2, and G9a histone lysine methyltransferase (HKMT). Consequently an H3K9me2 repressive mark is formed and Heterochromatin Protein 1γ (HP1γ) is recruited, that reinforces Pol II pausing prior to efficient transcriptional termination. We predict that R-loops promote a chromatin architecture that defines the termination region for a substantial subset of mammalian genes. PolIIS2ph ChIP-seq and input in untreated condition and treated with BIX and RNaseH1 overexpression in HeLa cells. The 4 samples have been multiplexed, pooled and sequenced on 3 lanes of Illumina HiSeq2000.
2014-09-29 | E-GEOD-59878 | biostudies-arrayexpress
Project description:To assess the diurnal gene expression in gills of oyster Crassotrea gigas, gills of 6 oysters were pooled and analyzed by RNa-seq every 4h for 52h (i.e. 13 sampling times). This procedure was executed simultaneously for control oysters fed with the non-harmful algae Heterocapsa triquetra (H.t condition), and for oysters fed with the harmful algae Alexandrium minutum (A.m condition) (L:D 9:15). Alexandrium minutum exposure led to a remodeling of the cycling transcriptome in gills of Crassostrea gigas.
2017-11-20 | E-MTAB-5345 | biostudies-arrayexpress
Project description:UAP56/DDX39b is a major co-transcriptional RNA-DNA helicase that unwinds harmful R loops genome-wide
| PRJNA525976 | ENA
Project description:The formation of R-loops is a natural consequence of the transcription process, caused by invasion of the DNA duplex by nascent transcripts. These structures have been considered rare transcriptional by-products with potential harmful effects on genome integrity, due to the fragility of the displaced DNA coding strand. However R-loops may also possess beneficial effects as their widespread formation has been detected over CpG island promoters in human genes. Furthermore we have previously shown that R-loops are particularly enriched over G-rich terminator elements. These facilitate RNA polymerase II (Pol II) pausing prior to efficient termination. Here we reveal an unanticipated link between R-loops and RNA interference (RNAi)-dependent H3K9me2 formation over pause site termination regions of mammalian protein coding genes. We show that R-loops induce antisense transcription over these pause elements which in turn lead to the generation of double-strand RNA (dsRNA) and recruitment of Dicer, Ago1, Ago2, and G9a histone lysine methyltransferase (HKMT). Consequently an H3K9me2 repressive mark is formed and Heterochromatin Protein 1γ (HP1γ) is recruited, that reinforces Pol II pausing prior to efficient transcriptional termination. We predict that R-loops promote a chromatin architecture that defines the termination region for a substantial subset of mammalian genes.
2014-09-29 | GSE59878 | GEO
Project description:R-loops are transcription by-products that may constitute a threat to genome integrity. In addition to specific enzymes to remove them, eukaryotes rely on a number of mRNP biogenesis factors such as the THO complex, to prevent co-transcriptional R-loop formation. We show in Saccharomyces cerevisiae that R-loops are tightly and specifically linked with histone H3-Ser10 phosphorylation (H3S10P), a mark of chromatin condensation. Importantly, ChIP-chip analyses reveal a clear H3S10P accumulation at the pericentromeric chromatin during the G1-phase of the cell cycle only in R loop-accumulating yeast strains but not in those non-accumulating R-loops, and a significantly higher accumulation during S-phase. Such a difference can also be detected in a number of genes along the genome. ChIP-chip studies were perfomed with antibodies against Histone H3 and the phosphorylated Histone H3 at Serine10 in the yeast S. cerevisiae.
2013-11-13 | E-GEOD-46627 | biostudies-arrayexpress
Project description:Diurnal gills transcriptome of the oyster Crassostrea gigas fed with non-harmful and harmful algae
| PRJEB18614 | ENA
Project description:This SuperSeries is composed of the following subset Series: GSE29182: Identification of active microRNA/transcription factor feed-forward loops during human adipogenesis (mRNA) GSE29185: Identification of active microRNA/transcription factor feed-forward loops during human adipogenesis (miRNA) Refer to individual Series
2011-12-20 | E-GEOD-29186 | biostudies-arrayexpress