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J Cell Biol December 5, 2005; 171 (5): 765-71.

Repair of double-strand breaks by nonhomologous end joining in the absence of Mre11.

Di Virgilio M , Gautier J .

Mre11-Rad50-Nbs1 (MRN) complex involvement in nonhomologous end joining (NHEJ) is controversial. The MRN complex is required for NHEJ in Saccharomyces cerevisiae but not in Schizosaccharomyces pombe. In vertebrates, Mre11, Rad50, and Nbs1 are essential genes, and studies have been limited to cells carrying hypomorphic mutations in Mre11 or Nbs1, which still perform several MRN complex-associated activities. In this study, we analyze the effects of Mre11 loss on the mechanism of vertebrate NHEJ by using a chromatinized plasmid double-strand break (DSB) repair assay in cell-free extracts from Xenopus laevis. Mre11-depleted extracts are able to support efficient NHEJ repair of DSBs regardless of the end structure. Mre11 depletion does not alter the kinetics of end joining or the type and frequency of junctions found in repaired products. Finally, Ku70-independent end-joining events are not affected by Mre11 loss. Our data demonstrate that the MRN complex is not required for efficient and accurate NHEJ-mediated repair of DSBs in this vertebrate system.

PubMed ID: 16330708
PMC ID: PMC2171289
Article link: J Cell Biol
Grant support: [+]

Species referenced: Xenopus
Genes referenced: mre11 myh3 nbn rad50

Article Images: [+] show captions
References [+] :
Boulton, Components of the Ku-dependent non-homologous end-joining pathway are involved in telomeric length maintenance and telomeric silencing. 1998, Pubmed