RNase H enables efficient repair of R-loop induced DNA damage

Amon, Jeremy D.; Koshland, Douglas

doi:10.1101/068742

Cited by 21 publications

(29 citation statements)

References 42 publications

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“…Notably, Top1-dependent removal of DNA torsional stress is critical for stability of the rDNA locus, which explains rDNA genetic instability in CPT-treated cells [54]. RNase H prevents R-loop accumulation in the rDNA of S. pombe and S. cerevisiae (Fig EV3A) [42], and rnh1/201Δ cells display increased markers of DNA damage in the rDNA [15,24,55]. Replication fork collapse triggered by unprocessed R-loops in the rDNA is likely a key reason why HDR is essential in rnh1/201Δ cells.…”

Section: Discussionmentioning

confidence: 99%

“…Lingering RNA primers from Okazaki fragments might also be involved [14]. In some circumstances, R-loops might trigger DSBs independently of replication [24], but repair of these DSBs should not require Mus81 unless this repair occurs by break-induced replication (BIR) [63]. No matter how R-loops cause DSBs, it is reasonable to propose that their persistence at DSBs in rnh1/201Δ cells might interfere with repair [24], making this repair less efficient than at DSBs formed by IR or other clastogens.…”

Section: Discussionmentioning

confidence: 99%

“…In S. cerevisiae, one consequence of RNase H deficiency is an increased number of Rad52 nuclear foci, which indicates increased DNA damage and correlates with an essential requirement for Rad52 in RNase H-deficient cells [9,24,26]. We examined Rad52 foci in fission yeast rnh1Δ cells lacking RNase H1, rnh201Δ cells lacking an essential subunit of RNase H2, or rnh1/201Δ cells lacking both RNase H enzymes.…”

Section: Increased Markers Of Dna Damage In Rnase H-deficient Cellsmentioning

confidence: 99%

“…From these and other data, a model was proposed in which efficient DSB repair requires formation of RNA-DNA hybrids by RNA polymerase II transcription of ssDNA at resected DSBs, followed by RNase H-mediated degradation of the RNA-DNA hybrids [23]. Another recent study also linked RNase H to DSB repair, although in this case RNase H was proposed to specifically promote repair of DSBs caused by unprocessed R-loops [24].…”

Section: Introductionmentioning

confidence: 99%

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RNase H eliminates R‐loops that disrupt DNA replication but is nonessential for efficient DSB repair

et al. 2018

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In , genome stability depends on RNases H1 and H2, which remove ribonucleotides from DNA and eliminate RNA-DNA hybrids (R-loops). In, RNase H enzymes were reported to process RNA-DNA hybrids produced at a double-strand break (DSB) generated by I-PpoI meganuclease. However, it is unclear if RNase H is generally required for efficient DSB repair in fission yeast, or whether it has other genome protection roles. Here, we show that cells, which lack the RNase H enzymes, accumulate R-loops and activate DNA damage checkpoints. Their viability requires critical DSB repair proteins and Mus81, which resolves DNA junctions formed during repair of broken replication forks. "Dirty" DSBs generated by ionizing radiation, as well as a "clean" DSB at a broken replication fork, are efficiently repaired in the absence of RNase H. RNA-DNA hybrids are not detected at a reparable DSB formed by fork collapse. We conclude that unprocessed R-loops collapse replication forks in cells, but RNase H is not generally required for efficient DSB repair.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Increased Markers Of Dna Damage In Rnase H-deficient Cellsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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RNase H eliminates R‐loops that disrupt DNA replication but is nonessential for efficient DSB repair

et al. 2018

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“…R loops have also been implicated in fragile X-associated tremor/ataxia syndrome, where they occur at the FMR1 locus and may affect gene function, leading to neuronal toxicity (Loomis et al 2014). RNase H1 and H2 are also important for R-loop resolution in addition to their roles in rNTP removal from DNA (Chon et al 2013;Amon and Koshland 2016;Williams et al 2016). Importantly, if a main physiologic function of SETX is R-loop resolution, then this implicates R loops as a major source of endogenous genomic damage in the nervous system.…”

Section: R Loops and Transcriptional Damagementioning

confidence: 99%

Genome integrity and disease prevention in the nervous system

2017

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RNases H1 and H2: guardians of the stability of the nuclear genome when supply of dNTPs is limiting for DNA synthesis

Cerritelli

Hage

2020

Curr Genet

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RNA/DNA hybrids are processed by RNases H1 and H2, while single ribonucleosidemonophosphates (rNMPs) embedded in genomic DNA are removed by the error-free, RNase H2-dependent ribonucleotide excision repair (RER) pathway. In the absence of RER, however, topoisomerase 1 (Top1) can cleave single genomic rNMPs in a mutagenic manner.In RNase H2-deficient mice, the accumulation of genomic rNMPs above a threshold of tolerance leads to catastrophic genomic instability that causes embryonic lethality. In humans, deficiencies in RNase H2 induce the autoimmune disorders Aicardi-Goutières syndrome and systemic lupus erythematosus, and cause skin and intestinal cancers.Recently, we reported that in Saccharomyces cerevisiae, the depletion of Rnr1, the major catalytic subunit of ribonucleotide reductase (RNR), which converts ribonucleotides to deoxyribonucleotides, leads to cell lethality in absence of RNases H1 and H2. We hypothesized that under replicative stress and compromised DNA repair that are elicited by an insufficient supply of deoxyribonucleoside-triphosphates (dNTPs), cells cannot survive the accumulation of persistent RNA/DNA hybrids. Remarkably, we found that cells lacking RNase H2 accumulate ~5-fold more genomic rNMPs in absence than in presence of Rnr1.When the load of genomic rNMPs is further increased in presence of a replicative DNA polymerase variant that over-incorporates rNMPs in leading or lagging strand, cells missing both Rnr1 and RNase H2 suffer from severe growth defects. These are reversed in absence of Top1. Thus, in cells lacking RNase H2 and containing a limiting supply of dNTPs, there is a threshold of tolerance for the accumulation of genomic ribonucleotides that is tightly associated with Top1-mediated DNA damage. In this mini-review, we describe the implications of the loss of RNase H2, or RNases H1 and H2, on the integrity of the nuclear genome and viability of budding yeast cells that are challenged with critically low supply of dNTPs. We further propose that our findings in budding yeast could pave the way for the study of the potential role of mammalian RNR in RNase H2-related diseases.

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RNase H enables efficient repair of R-loop induced DNA damage

Cited by 21 publications

References 42 publications

RNase H eliminates R‐loops that disrupt DNA replication but is nonessential for efficient DSB repair

RNase H eliminates R‐loops that disrupt DNA replication but is nonessential for efficient DSB repair

Genome integrity and disease prevention in the nervous system

RNases H1 and H2: guardians of the stability of the nuclear genome when supply of dNTPs is limiting for DNA synthesis

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