Gap-filling and bypass at the replication fork are both active mechanisms for tolerance of low-dose ultraviolet-induced DNA damage in the human genome

Quinet, Annabel; Vessoni, Alexandre Teixeira; Rocha, Clarissa Ribeiro Reily; Gottifredi, Vanesa; Biard, Denis; Sarasin, Alain; Menck, Carlos Frederico Martins; Stary, Anne

doi:10.1016/j.dnarep.2013.12.005

Cited by 60 publications

(88 citation statements)

References 55 publications

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“…The TLS polη is the preferred choice for TLS across CPDs (35). Polη depletion impairs DNA elongation after UV doses like the one used in this study (33). In our experimental settings, polη depletion did not affect DNA elongation in sham-irradiated samples (Fig.…”

Section: Resultsmentioning

confidence: 76%

“…To date, DNA elongation after UV irradiation in mammals has been almost exclusively linked to DNA damage tolerance events involving TLS polymerases. Previous reports have demonstrated that DNA elongation after UV irradiation is impaired when the TLS polymerase polη or Rev1 (DNA directed polymerase) is absent (33,34). The molecular basis of such events has been fairly well elucidated: UV irradiation provokes helix-distorting lesions, such as cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs).…”

Section: Resultsmentioning

confidence: 99%

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Rad51 recombinase prevents Mre11 nuclease-dependent degradation and excessive PrimPol-mediated elongation of nascent DNA after UV irradiation

Vallerga

Mansilla

Federico

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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After UV irradiation, DNA polymerases specialized in translesion DNA synthesis (TLS) aid DNA replication. However, it is unclear whether other mechanisms also facilitate the elongation of UVdamaged DNA. We wondered if Rad51 recombinase (Rad51), a factor that escorts replication forks, aids replication across UV lesions. We found that depletion of Rad51 impairs S-phase progression and increases cell death after UV irradiation. Interestingly, Rad51 and the TLS polymerase polη modulate the elongation of nascent DNA in different ways, suggesting that DNA elongation after UV irradiation does not exclusively rely on TLS events. In particular, Rad51 protects the DNA synthesized immediately before UV irradiation from degradation and avoids excessive elongation of nascent DNA after UV irradiation. In Rad51-depleted samples, the degradation of DNA was limited to the first minutes after UV irradiation and required the exonuclease activity of the double strand break repair nuclease (Mre11). The persistent dysregulation of nascent DNA elongation after Rad51 knockdown required Mre11, but not its exonuclease activity, and PrimPol, a DNA polymerase with primase activity. By showing a crucial contribution of Rad51 to the synthesis of nascent DNA, our results reveal an unanticipated complexity in the regulation of DNA elongation across UV-damaged templates.PrimPol | polκ | polη | DNA damage tolerance | DNA replication T he DNA-binding protein Rad51 is a central component of homologous recombination repair (HRR). HRR repairs doublestrand breaks (DSBs) in an error-free way and processes one-ended DSBs to reactivate collapsed replication forks (1). During HRR, DSBs are processed by the 3′-to-5′ exonuclease activity of the double strand break repair nuclease (Mre11) to generate protruding 3′ ssDNA at DSBs. The ssDNA is then coated with Rad51, a factor that catalyzes homology search and strand invasion. The loading and stabilization of Rad51/ssDNA complexes are supported by multiple mediators, such as the tumor suppressor BRCA2 (breast cancer 2) (1). Moreover, Rad51 promotes XPF1-and Exo1-mediated DSB formation after gemcitabine-induced irreversible ribonucleotide reductase inhibition, thus promoting cell death (2). The signals that redirect Rad51 into a DSB formation pathway rather than DSB repair are not yet known.The functions of Rad51 are not limited to the processing/ generation of DSBs. Over the past few years, it has become evident that Rad51 escorts ongoing replication forks regardless of the presence of DSBs (3-5). Specifically, Rad51 protects persistently stalled replication forks from Mre11-mediated nucleolytic degradation and facilitates replication fork restart when the replication-halting agent hydroxyurea (HU) or aphidicolin (APH) is removed (6-19). Such novel functions of Rad51 require many HRR factors, including BCRA2, FANCD2 (Fanconi Anemia Complementation group protein D2), CtIP, BRCA1, and the WRN helicase, but are independent of HRR effectors, such as Rad54 (6, 7). Rad51-dependent fork-restart and fork-protection ...

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Section: Resultsmentioning

confidence: 76%

Section: Resultsmentioning

confidence: 99%

Rad51 recombinase prevents Mre11 nuclease-dependent degradation and excessive PrimPol-mediated elongation of nascent DNA after UV irradiation

Vallerga

Mansilla

Federico

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Flow cytometry experiments were performed as previously described (27,28). For the cell cycle analysis by the concomitant PI-BrdU staining, a pulse of 10 μM bromodeoxyuridine (BrdU, Sigma-Aldrich) was performed for 20 min after the second UVC irradiation.…”

Section: Methodsmentioning

confidence: 99%

Predominant role of DNA polymerase eta and p53-dependent translesion synthesis in the survival of ultraviolet-irradiated human cells

Lerner

Francisco

Soltys

et al. 2016

Nucleic Acids Research

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Genome lesions trigger biological responses that help cells manage damaged DNA, improving cell survival. Pol eta is a translesion synthesis (TLS) polymerase that bypasses lesions that block replicative polymerases, avoiding continued stalling of replication forks, which could lead to cell death. p53 also plays an important role in preventing cell death after ultraviolet (UV) light exposure. Intriguingly, we show that p53 does so by favoring translesion DNA synthesis by pol eta. In fact, the p53-dependent induction of pol eta in normal and DNA repair-deficient XP-C human cells after UV exposure has a protective effect on cell survival after challenging UV exposures, which was absent in p53- and Pol H-silenced cells. Viability increase was associated with improved elongation of nascent DNA, indicating the protective effect was due to more efficient lesion bypass by pol eta. This protection was observed in cells proficient or deficient in nucleotide excision repair, suggesting that, from a cell survival perspective, proper bypass of DNA damage can be as relevant as removal. These results indicate p53 controls the induction of pol eta in DNA damaged human cells, resulting in improved TLS and enhancing cell tolerance to DNA damage, which parallels SOS responses in bacteria.

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“…Third, Chk1 contributes to the recruitment of Pol η to replication factories after UV irradiation (Speroni et al, 2012). Fourth, the depletion of Chk1 impairs DNA elongation after UV-irradiation (Speroni et al, 2012), a phenotype reminiscent of that of UV-irradiated XPV fibroblasts (Quinet et al, 2014). Intriguingly, the fork elongation and Pol η foci phenotypes reported by (Speroni et al, 2012) do not correlate with reduced PCNA ubiquitination.…”

Section: Chk1 Function During Dna Replicationmentioning

confidence: 99%

The fork and the kinase: A DNA replication tale from a CHK1 perspective

Besteiro

Gottifredi

2015

Mutation Research/Reviews in Mutation Research

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Replication fork progression is being continuously hampered by exogenously introduced and naturally occurring DNA lesions and other physical obstacles. The checkpoint kinase 1 (Chk1) is activated at replication forks that encounter damaged-DNA. Chk1 inhibits the initiation of new replication factories and stimulates the firing of dormant origins (those in the vicinity of stalled forks). Chk1 also avoids fork collapse into DSBs (double strand breaks) and promotes fork elongation. At the molecular level, the current model considers stalled forks as the site of Chk1 activation and the nucleoplasm as the location where Chk1 phosphorylates target proteins. This model certainly serves to explain how Chk1 modulates origin firing, but how Chk1 controls the fate of stalled forks is less clear. Interestingly, recent reports demonstrating that Chk1 phosphorylates chromatin-bound proteins and even holds kinase-independent functions might shed light on how Chk1 contributes to the elongation of damaged DNA. Such findings unveil a puzzling connection between Chk1 and DNA-lesion bypass, which might be central to promoting fork elongation and checkpoint attenuation. In summary, the multifaceted and versatile functions of Chk1 at ongoing forks and replication origins determine the extent and quality of the cellular response to replication stress.

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Gap-filling and bypass at the replication fork are both active mechanisms for tolerance of low-dose ultraviolet-induced DNA damage in the human genome

Cited by 60 publications

References 55 publications

Rad51 recombinase prevents Mre11 nuclease-dependent degradation and excessive PrimPol-mediated elongation of nascent DNA after UV irradiation

Rad51 recombinase prevents Mre11 nuclease-dependent degradation and excessive PrimPol-mediated elongation of nascent DNA after UV irradiation

Predominant role of DNA polymerase eta and p53-dependent translesion synthesis in the survival of ultraviolet-irradiated human cells

The fork and the kinase: A DNA replication tale from a CHK1 perspective

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