DNA Double-Strand Break Repair Pathway Choice Is Directed by Distinct MRE11 Nuclease Activities

Atsushi Shibata, Davide Moiani, Andrew S. Arvai, Jefferson Perry, Shane M. Harding, Marie Michelle Genois, Ranjan Maity, Sari van Rossum-Fikkert, Aryandi Kertokalio, Filippo Romoli, Amani Ismail, Ermal Ismalaj, Elena Petricci, Matthew J. Neale, Robert G. Bristow, Jean Yves Masson, Claire Wyman, Penny A. Jeggo, John A. Tainer

Research output: Contribution to journalArticlepeer-review


MRE11 within the MRE11-RAD50-NBS1 (MRN) complex acts in DNA double-strand break repair (DSBR), detection, and signaling; yet, how its endo- and exonuclease activities regulate DSBR by nonhomologous end-joining (NHEJ) versus homologous recombination (HR) remains enigmatic. Here, we employed structure-based design with a focused chemical library to discover specific MRE11 endo- or exonuclease inhibitors. With these inhibitors, we examined repair pathway choice at DSBs generated in G2 following radiation exposure. While nuclease inhibition impairs radiation-induced replication protein A (RPA) chromatin binding, suggesting diminished resection, the inhibitors surprisingly direct different repair outcomes. Endonuclease inhibition promotes NHEJ in lieu of HR, while exonuclease inhibition confers a repair defect. Collectively, the results describe nuclease-specific MRE11 inhibitors, define distinct nuclease roles in DSB repair, and support a mechanism whereby MRE11 endonuclease initiates resection, thereby licensing HR followed by MRE11 exonuclease and EXO1/BLM bidirectional resection toward and away from the DNA end, which commits to HR.

Original languageEnglish
Pages (from-to)7-18
Number of pages12
JournalMolecular Cell
Issue number1
Publication statusPublished - 9 Jan 2014

Research Beacons, Institutes and Platforms

  • Manchester Cancer Research Centre


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