Collaboration of homologous recombination and nonhomologous end-joining factors for the survival and integrity of mice and cells
- Chrystelle Couëdel1,
- Kevin D. Mills4,
- Marco Barchi1,
- Lingbo Shen2,
- Adam Olshen3,
- Roger D. Johnson1,5,
- André Nussenzweig6,
- Jeroen Essers7,
- Roland Kanaar7,
- Gloria C. Li2,
- Frederick W. Alt4,8, and
- Maria Jasin1,9
- 1Molecular Biology Program, 2Department of Medical Physics and Department of Radiation Oncology, and 3Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA; 4CBR Institute for Biomedical Research, Boston, Massachusetts 02115, USA; 5Cancer Center and Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA; 6Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA; 7Department of Cell Biology and Genetics, and Department of Radiation Oncology, Erasmus MC, 3000 DR Rotterdam, The Netherlands; 8Howard Hughes Medical Institute, The Children's Hospital, Boston, Massachusetts 02115, USA
Abstract
Homologous recombination (HR) and nonhomologous end-joining (NHEJ) are mechanistically distinct DNA repair pathways that contribute substantially to double-strand break (DSB) repair in mammalian cells. We have combined mutations in factors from both repair pathways, the HR protein Rad54 and the DNA-end-binding factor Ku80, which has a role in NHEJ. Rad54-/-Ku80-/- mice were severely compromised in their survival, such that fewer double mutants were born than expected, and only a small proportion of those born reached adulthood. However, double-mutant mice died at lower frequency from tumors than Ku80 single mutant mice, likely as a result of rapid demise at a young age from other causes. When challenged with an exogenous DNA damaging agent, ionizing radiation, double-mutant mice were exquisitely sensitive to low doses. Tissues and cells from double-mutant mice also showed indications of spontaneous DNA damage. Testes from some Rad54-/-Ku80-/- mice displayed enhanced apoptosis and reduced sperm production, and embryonic fibroblasts from Rad54-/-Ku80-/- animals accumulated foci of γ-H2AX, a marker for DSBs. The substantially increased DNA damage response in the double mutants implies a cooperation of the two DSB repair pathways for survival and genomic integrity in the animal.
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Footnotes
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Supplemental material is available at http://www.genesdev.org.
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Article and publication are at http://www.genesdev.org/cgi/doi/10.1101/gad.1209204.
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↵9 Corresponding author. E-MAIL m-jasin{at}ski.mskcc.org; FAX (212) 717-3317.
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- Accepted April 23, 2004.
- Received April 5, 2004.
- Cold Spring Harbor Laboratory Press