| 1. |
- Duro, Eris, et al.
(författare)
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Identification of the MMS22L-TONSL Complex that Promotes Homologous Recombination
- 2010
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Ingår i: Molecular Cell. - : Elsevier BV. - 1097-2765 .- 1097-4164. ; 40:4, s. 632-644
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Tidskriftsartikel (refereegranskat)abstract
- Budding yeast Mms22 is required for homologous recombination (HR)-mediated repair of stalled or broken DNA replication forks. Here we identify a human Mms22-like protein (MMS22L) and an MMS22L-interacting protein, NF kappa BIL2/TONSL. Depletion of MMS22L or TONSL from human cells causes a high level of double-strand breaks (DSBs) during DNA replication. Both proteins accumulate at stressed replication forks, and depletion of MMS22L or TONSL from cells causes hypersensitivity to agents that cause S phase-associated DSBs, such as topoisomerase (TOP) inhibitors. In this light, MMS22L and TONSL are required for the HR-mediated repair of replication fork-associated DSBs. In cells depleted of either protein, DSBs induced by the TOP1 inhibitor camptothecin are resected normally, but the loading of the RAD51 recombinase is defective. Therefore, MMS22L and TONSL are required for the maintenance of genome stability when unscheduled DSBs occur in the vicinity of DNA replication forks.
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| 2. |
- Moskwa, Patryk, et al.
(författare)
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miR-182-Mediated Downregulation of BRCA1 Impacts DNA Repair and Sensitivity to PARP Inhibitors
- 2011
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Ingår i: Molecular Cell. - : Elsevier BV. - 1097-2765 .- 1097-4164. ; 41:2, s. 210-220
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Tidskriftsartikel (refereegranskat)abstract
- Expression of BRCA1 is commonly decreased in sporadic breast tumors, and this correlates with poor prognosis of breast cancer patients. Here we show that BRCA1 transcripts are selectively enriched in the Argonaute/miR-182 complex and miR-182 downregulates BRCA1 expression. Antagonizing miR-182 enhances BRCA1 protein levels and protects them from IR-induced cell death, while overexpressing miR-182 reduces BRCA1 protein, impairs homologous recombination-mediated repair, and render cells hypersensitive to IR. The impaired DNA repair phenotype induced by mill 182 overexpression can be fully rescued by overexpressing miR-182-insensitive BRCA1. Consistent with a BRCA1-deficiency phenotype, miR-182-over-expressing breast tumor cells are hypersensitive to inhibitors of poly (ADP-ribose) polymerase 1 (PARP1). Conversely, antagonizing miR-182 enhances BRCA1 levels and induces resistance to PARP1 inhibitor. Finally, a clinical-grade PARP1 inhibitor impacts outgrowth of miR-182-expressing tumors in animal models. Together these results suggest that miR-182-mediated downregulation of BRCA1 impedes DNA repair and may impact breast cancer therapy.
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| 3. |
- Petermann, Eva, et al.
(författare)
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Hydroxyurea-stalled replication forks become progressively inactivated and require two different RAD51-mediated pathways for restart and repair.
- 2010
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Ingår i: Molecular Cell. - : Elsevier BV. - 1097-2765 .- 1097-4164. ; 37:4, s. 492-502
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Tidskriftsartikel (refereegranskat)abstract
- Faithful DNA replication is essential to all life. Hydroxyurea (HU) depletes the cells of dNTPs, which initially results in stalled replication forks that, after prolonged treatment, collapse into DSBs. Here, we report that stalled replication forks are efficiently restarted in a RAD51-dependent process that does not trigger homologous recombination (HR). The XRCC3 protein, which is required for RAD51 foci formation, is also required for replication restart of HU-stalled forks, suggesting that RAD51-mediated strand invasion supports fork restart. In contrast, replication forks collapsed by prolonged replication blocks do not restart, and global replication is rescued by new origin firing. We find that RAD51-dependent HR is triggered for repair of collapsed replication forks, without apparent restart. In conclusion, our data suggest that restart of stalled replication forks and HR repair of collapsed replication forks require two distinct RAD51-mediated pathways.
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