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

A Shibata, D (Davide) Moiani, AS Arvai, J Perry, SM Harding, MM Genois, R Maity, Sari Van Rossum - Fikkert, Aryandi Kertokalio, F Romoli, A Ismail, E Ismalaj, E Petricci, MJ Neale, RG Bristow, JY Masson, C.L. Wyman, PA Jeggo, JA Tainer

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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 non-homologous 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 languageUndefined/Unknown
Pages (from-to)7-18
Number of pages12
JournalMolecular Cell
Issue number1
Publication statusPublished - 2014

Research programs

  • EMC MGC-01-12-03
  • EMC MM-03-32-04

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