Brca2 (XRCC11) deficiency results in radioresistant DNA synthesis and a higher frequency of spontaneous deletions.
We show here that the radiosensitive Chinese hamster cell mutant (V-C8) of group XRCC11 is defective in the breast cancer susceptibility gene Brca2. The very complex phenotype of V-C8 cells is complemented by a single human chromosome 13 providing the BRCA2 gene, as well as by the murine Brca2 gene. The Brca2 deficiency in V-C8 cells causes hypersensitivity to various DNA-damaging agents with an extreme sensitivity toward interstrand DNA cross-linking agents. Furthermore, V-C8 cells show radioresistant DNA synthesis after ionizing radiation, suggesting that Brca2 deficiency affects cell cycle checkpoint regulation. In addition, V-C8 cells display tremendous chromosomal instability and a high frequency of abnormal centrosomes. The mutation spectrum at the hprt locus showed that the majority of spontaneous mutations in V-C8 cells are deletions, in contrast to wild-type V79 cells. A mechanistic explanation for the genome instability phenotype of Brca2-deficient cells is provided by the observation that the nuclear localization of the central DNA repair protein in homologous recombination, Rad51, is reduced in V-C8 cells.
Kraakman-van der Zwet
Maria
M
Department of Radiation Genetics and Chemical Mutagenesis-MGC, Leiden University Medical Center, The Netherlands.
Overkamp
Wilhelmina J I
WJ
van Lange
Rebecca E E
RE
Essers
Jeroen
J
van Duijn-Goedhart
Annemarie
A
Wiggers
Ingrid
I
Swaminathan
Srividya
S
van Buul
Paul P W
PP
Errami
Abdellatif
A
Tan
Raoul T L
RT
Jaspers
Nicolaas G J
NG
Sharan
Shyam K
SK
Kanaar
Roland
R
Zdzienicka
Malgorzata Z
MZ
D000818:Animals; D024682:BRCA2 Protein / Q000172:deficiency* / Q000235:genetics; D002460:Cell Line; D018385:Centrosome / Q000648:ultrastructure; D002869:Chromosome Aberrations; D022202:Chromosomes, Artificial, Bacterial; D002882:Chromosomes, Human, Pair 13 / Q000235:genetics; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000096:biosynthesis*; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D024522:Genes, BRCA2; D005816:Genetic Complementation Test; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D051379:Mice; D009154:Mutation; D051135:Rad51 Recombinase; D011836:Radiation Tolerance; D017384:Sequence Deletion; D012854:Sister Chromatid Exchange
D024682:BRCA2 Protein; D004268:DNA-Binding Proteins; D004247:DNA; D007041:Hypoxanthine Phosphoribosyltransferase; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; C495154:Rad51 protein, mouse