XAB2 prevents abortive recombinational repair of replication-associated DNA double-strand breaks and its loss is synthetic lethal with RAD52 inhibition

Sharma, A. B.; Erasimus, H.; Pinto, L.; Caron, M.-C.; Neumann, K.; Nazarov, P. V.; Klink, B.; Fritah, S.; Herold-Mende, C. C.; Niclou, S. P.; Calsou, P.; Masson, J.-Y.; Britton, S.; Van Dyck, E.

doi:10.1101/2020.04.10.035410

bioRxiv · 10.1101/2020.04.10.035410

XAB2 prevents abortive recombinational repair of replication-associated DNA double-strand breaks and its loss is synthetic lethal with RAD52 inhibition

Sharma, A. B.·Erasimus, H.·Pinto, L.·Caron, M.-C.·Neumann, K.·Nazarov, P. V.·Klink, B.·Fritah, S.·Herold-Mende, C. C.·Niclou, S. P.·Calsou, P.·Masson, J.-Y.·Britton, S.·Van Dyck, E.

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Abstract

Unrepaired O6-methylguanine lesions induced by the alkylating chemotherapy agent temozolomide lead to replication-associated single-ended DNA double-strand breaks (seDSBs) that are repaired predominantly through RAD51-mediated homologous recombination (HR). Here, we show that loss of the pre-mRNA splicing and DNA repair protein XAB2 leads to increased temozolomide sensitivity in glioblastoma cells, which reflects abortive HR due to Ku retention on resected seDSBs. XAB2-dependent Ku eviction also occurred at seDSBs generated by the topoisomerase I poison campthotecin and operated in parallel to an ATM-dependent pathway previously described. Although Ku retention elicited by loss of XAB2 did not prevent RAD51 focus formation, the resulting RAD51-ssDNA associations were unproductive, leading to increased engagement of non-homologous-end-joining in S/G2 and genetic instability. Overexpression of RAD51 or the single-stranded DNA annealing factor RAD52 rescued the XAB2 defects. RAD52 depletion led to severe temozolomide sensitivity, whereas a synthetic lethality interaction was observed between RAD52 and XAB2.

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Sharma, A. B., Erasimus, H., Pinto, L., Caron, M.-C., Neumann, K., Nazarov, P. V., Klink, B., Fritah, S., Herold-Mende, C. C., Niclou, S. P., Calsou, P., Masson, J.-Y., Britton, S., Van Dyck, E.. 2020-04-11. XAB2 prevents abortive recombinational repair of replication-associated DNA double-strand breaks and its loss is synthetic lethal with RAD52 inhibition. https://doi.org/10.1101/2020.04.10.035410

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