Cancer predispositions in humans and severe DNA damage phenotypes in yeast result from defects in the Mre11-Rad50-Nbs1 (MRN) complex. MRN plays central and essential roles in repairing DNA double-strand breaks (DSBs) during homologous recombination repair as well as acting in meiosis, antibody hypermutation, telomere maintenance, and DNA damage signaling through ATM kinase. Yet, detailed mechanistic insights into these diverse MRN functions remain limited. The Mre11 nuclease complex with the Rad50 ATPase is conserved from archaea to humans and is regulated by Nbs1 in S. pombe and humans. We propose three Specific Aims to advance knowledge of MRN structural biochemistry, conformations, and interactions relevant to DNA damage repair and signaling functions. To accomplish these Aims, we will apply advanced biophysical techniques, including synchrotron solution X-ray scattering and atomic resolution crystal structure technologies in concert with genetic and mutational analyses in yeast. The proposed integrated biophysical and genetic studies will test hypotheses regarding Mre11's role in DNA target specificity and processing, Rad50's role in ATP-induced conformational controls and architectural interactions, and Nbs1's role in modulating Mre11 and Rad50 activities. The expected results will characterize functionally key Mre11, Rad50 and Nbs1 protein-protein and protein-DNA interfaces, conformations, and interaction architectures. Furthermore, the DNA damage sensitivity observed in the absence of any one member of the MRN complex suggests that our results will form a platform to test the utility of inhibitors that increase cellular sensitivity to ionizing radiation and other DNA damaging agents used for cancer radiotherapy and chemotherapy. Overall the results will connect MRN to cellular outcomes and human disease by defining interactions and mechanisms controlling genetic integrity, cancer resistance, radiotherapy resistance, and predispositions to cancer.

Public Health Relevance

Major goals for cancer research for the past decade have been the identification of the molecular underpinnings of cancer and the development of novel approaches to intervention. A major advance has been the characterization of the Mre11-Rad50-Nbs1 (MRN) complex as a critical suppressor of tumorigenesis and a resistance factor for current therapies. The proposed research will provide insights into the molecular mechanisms for MRN functions relevant to both cancer avoidance and interventions.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
Project #
Application #
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Knowlton, John R
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Scripps Research Institute
La Jolla
United States
Zip Code
Petersen, Janni; Russell, Paul (2016) Growth and the Environment of Schizosaccharomyces pombe. Cold Spring Harb Protoc 2016:pdb.top079764
Guo, Lan; Ganguly, Abantika; Sun, Lingling et al. (2016) Global Fitness Profiling Identifies Arsenic and Cadmium Tolerance Mechanisms in Fission Yeast. G3 (Bethesda) 6:3317-3333
Mejia-Ramirez, Eva; Limbo, Oliver; Langerak, Petra et al. (2015) Critical Function of γH2A in S-Phase. PLoS Genet 11:e1005517
Sánchez, Arancha; Roguev, Assen; Krogan, Nevan J et al. (2015) Genetic Interaction Landscape Reveals Critical Requirements for Schizosaccharomyces pombe Brc1 in DNA Damage Response Mutants. G3 (Bethesda) 5:953-62
Lafrance-Vanasse, Julien; Williams, Gareth J; Tainer, John A (2015) Envisioning the dynamics and flexibility of Mre11-Rad50-Nbs1 complex to decipher its roles in DNA replication and repair. Prog Biophys Mol Biol 117:182-93
Sánchez, Arancha; Russell, Paul (2015) Ku stabilizes replication forks in the absence of Brc1. PLoS One 10:e0126598
Tainer, John A (2015) Dynamic structures in DNA damage responses & cancer. Prog Biophys Mol Biol 117:129-33
Shibata, Atsushi; Moiani, Davide; Arvai, Andrew S et al. (2014) DNA double-strand break repair pathway choice is directed by distinct MRE11 nuclease activities. Mol Cell 53:7-18
Wang, Lanfeng; Limbo, Oliver; Fei, Jia et al. (2014) Regulation of the Rhp26ERCC6/CSB chromatin remodeler by a novel conserved leucine latch motif. Proc Natl Acad Sci U S A 111:18566-71
Deshpande, Rajashree A; Williams, Gareth J; Limbo, Oliver et al. (2014) ATP-driven Rad50 conformations regulate DNA tethering, end resection, and ATM checkpoint signaling. EMBO J 33:482-500

Showing the most recent 10 out of 33 publications