POLθ prevents MRE11-NBS1-CtIP-dependent fork breakage in the absence of BRCA2/RAD51 by filling lagging-strand gaps

Mann, Anjali; Ramírez-Otero, Miguel Angel; A, De Antoni; Hanthi, Yodhara Wijesekara; Sannino, Vincenzo; Baldi, Giorgio; Falbo, Lucia; Schrempf, Anna; Bernardo, Sara; Loizou, Joanna I.; Costanzo, Vincenzo

doi:10.1016/j.molcel.2022.09.013

Cited by 55 publications

(47 citation statements)

References 70 publications

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“…However, we found that PFM01, a specific inhibitor of the endonuclease activity of MRE11, also restored the ability of BJ-RAS V12 fibroblasts to incorporate BrdU. It has been recently shown that PFM01 blocks fork breakage in absence of RAD51 (Mann et al, 2022). These data suggest that the cleavage of DNA strands could also contribute to OIS in BJ-RAS V12 cells, presumably through the release of cytosolic DNA.…”

Section: Discussionsupporting

confidence: 50%

Regulation of oncogene-induced senescence by the MRE11 and TREX1 nucleases

Técher

Gopaul

Heuzé

et al. 2023

Preprint

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Oncogene-induced senescence (OIS) is a tumor-suppressive mechanism that arrests cell proliferation in response to oncogene-induced replication stress (RS). OIS also depends on the cGAS-STING pathway, which detects cytosolic DNA and promotes the expression of type I interferons (IFN) and pro-inflammatory cytokines. Whether and how the RS and IFN responses cooperate to promote OIS is currently unknown. Here, we show that the MRE11 nuclease promotes OIS in immortalized human fibroblasts overexpressing the H-RASV12 oncogene both by slowing replication forks and by activating the cGAS-STING pathway in response to RS. Interestingly, overexpression of TREX1, the major nuclease degrading cytosolic DNA, prevented RAS-induced senescence. In contrast, overexpression of a dominant negative mutant of TREX1 was sufficient to induce senescence in human fibroblasts, even in the absence of H-RASV12 induction. Collectively, these data suggest that the RS and IFN responses in OIS are functionally linked through a process involving the nucleases MRE11 and TREX1.

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Section: Discussionsupporting

confidence: 50%

Regulation of oncogene-induced senescence by the MRE11 and TREX1 nucleases

Técher

Gopaul

Heuzé

et al. 2023

Preprint

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“…We believe this provides an opportunity to target both pathways simultaneously to improve tumour eradication and reduce risk of resistance to either therapy individually. Next to a role in DSB repair, POLQ has recently been described to be involved in ssDNA gap fill-in (Belan et al, 2022; Mann et al, 2022; Schrempf et al, 2022). However, it is currently unclear how the two different roles of POLQ contribute to its essential role in BRCA-deficient cells.…”

Section: Discussionmentioning

confidence: 99%

“…This implies that DSB repair by alt-EJ or SSA is essential for survival of HR-deficient cells (Ceccaldi et al, 2015; Feng et al, 2011; Lok et al, 2013; Mateos-Gomez et al, 2015). However, recent studies suggested that increased ssDNA gap formation in absence of PolQ may underlie the synthetic lethality with BRCA-deficiency (Belan et al, 2022; Mann et al, 2022; Schrempf et al, 2022). BRCA-deficient cells are prone to accumulate ssDNA gaps, and toxic levels of these lesion are associated with sensitivity to chemotherapy and PARPi (Cong et al, 2021; Paes Dias et al, 2021; Panzarino et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

EXO1-mediated DNA repair by single-strand annealing is essential for BRCA1-deficient cells

Kooij

Schreuder

Pavani

et al. 2023

Preprint

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Deficiency for the repair of DNA double-strand breaks (DSBs) via homologous recombination (HR) leads to chromosomal instability and diseases such as cancer. Yet, defective HR also results in vulnerabilities that can be exploited for targeted therapy. Here, we identify such a vulnerability and show that BRCA1-deficient cells are dependent on the long-range end-resection factor EXO1 for survival. EXO1 loss results in DNA replication-induced lesions decorated by poly(ADP-ribose)-chains. In cells that lack both BRCA1 and EXO1, this is accompanied by unresolved DSBs due to impaired single-strand annealing (SSA), a DSB repair process that requires the activity of both proteins. In contrast, BRCA2-deficient cells have increased SSA, also in the absence of EXO1, and hence are not dependent on EXO1 for survival. In agreement with our mechanistic data, BRCA1-mutated tumours have elevated EXO1 expression and contain more genomic signatures of SSA compared to BRCA1-proficient tumours. Collectively, our data indicate that EXO1 is a promising novel target for treatment of BRCA1-deficient tumours.

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“…Alternatively, the RAD51-dependent Polα recruitment might always take place at lagging strand before and after the extensive fork degradation by MRE11 (Figure 8F). Interestingly, it has been recently reported that also Polθ can be recruited at the lagging strand to fill-in template gaps in the absence of RAD51 53 . Thus multiple mechanism might contribute to prevent excessive fork reversal and accumulation of template gaps.…”

Section: Discussionmentioning

confidence: 99%

RAD52 prevents accumulation of Polalpha-dependent replication gaps at perturbed replication forks in human cells

Biagi

Malacaria

Aiello

et al. 2023

Preprint

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Replication gaps can arise as a consequence of perturbed DNA replication and their accumulation might undermine the stability of the genome. Loss of RAD52, a protein involved in the regulation of fork reversal, promotes accumulation of parental ssDNA gaps during replication perturbation. Here, we demonstrate that this is due to the engagement of Polalpha downstream of the extensive degradation of perturbed replication forks after their reversal, and is not dependent on PrimPol. Polalpha is hyper-recruited at parental ssDNA in the absence of RAD52, and this recruitment is dependent on fork reversal enzymes and RAD51. Of note, we report that the interaction between Polalpha and RAD51 is stimulated by RAD52 inhibition, and Polalpha-dependent gap accumulation requires nucleation of RAD51 suggesting that it occurs downstream strand invasion. Altogether, our data indicate that RAD51-Polalpha-dependent repriming is essential to promote fork restart and limit DNA damage accumulation when RAD52 function is disabled.

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POLθ prevents MRE11-NBS1-CtIP-dependent fork breakage in the absence of BRCA2/RAD51 by filling lagging-strand gaps

Cited by 55 publications

References 70 publications

Regulation of oncogene-induced senescence by the MRE11 and TREX1 nucleases

Regulation of oncogene-induced senescence by the MRE11 and TREX1 nucleases

EXO1-mediated DNA repair by single-strand annealing is essential for BRCA1-deficient cells

RAD52 prevents accumulation of Polalpha-dependent replication gaps at perturbed replication forks in human cells

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