Collaboration of homologous recombination and nonhomologous end-joining factors for the survival and integrity of mice and cells.
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 gamma-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.
Couëdel
Chrystelle
C
Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Mills
Kevin D
KD
Barchi
Marco
M
Shen
Lingbo
L
Olshen
Adam
A
Johnson
Roger D
RD
Nussenzweig
André
A
Essers
Jeroen
J
Kanaar
Roland
R
Li
Gloria C
GC
Alt
Frederick W
FW
Jasin
Maria
M
D000375:Aging / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn; D034961:Antigens, Nuclear / Q000235:genetics / Q000378:metabolism*; D001921:Brain / Q000473:pathology; D002478:Cells, Cultured; D004249:DNA Damage / Q000235:genetics; D004265:DNA Helicases; D004260:DNA Repair / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005313:Fetal Death / Q000235:genetics; D005347:Fibroblasts / Q000502:physiology / Q000528:radiation effects; D006657:Histones / Q000235:genetics / Q000378:metabolism; D000072200:Ku Autoantigen; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011839:Radiation, Ionizing; D011995:Recombination, Genetic; D015996:Survival Rate; D013737:Testis / Q000473:pathology
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D006657:Histones; D009687:Nuclear Proteins; C475961:gamma-H2AX protein, mouse; D004265:DNA Helicases; C103534:Rad54l protein, mouse; C000606510:Xrcc6 protein, mouse; D000072200:Ku Autoantigen