title: Brca2 (XRCC11) deficiency results in radioresistant DNA synthesis and a higher frequency of spontaneous deletions.
abstract: 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.
authors.affiliation: Department of Radiation Genetics and Chemical Mutagenesis-MGC, Leiden University Medical Center, The Netherlands.
authors.forename: Maria
authors.initials: M
authors.lastname: Kraakman-van der Zwet
authors.forename: Wilhelmina J I
authors.initials: WJ
authors.lastname: Overkamp
authors.forename: Rebecca E E
authors.initials: RE
authors.lastname: van Lange
authors.forename: Jeroen
authors.initials: J
authors.lastname: Essers
authors.forename: Annemarie
authors.initials: A
authors.lastname: van Duijn-Goedhart
authors.forename: Ingrid
authors.initials: I
authors.lastname: Wiggers
authors.forename: Srividya
authors.initials: S
authors.lastname: Swaminathan
authors.forename: Paul P W
authors.initials: PP
authors.lastname: van Buul
authors.forename: Abdellatif
authors.initials: A
authors.lastname: Errami
authors.forename: Raoul T L
authors.initials: RT
authors.lastname: Tan
authors.forename: Nicolaas G J
authors.initials: NG
authors.lastname: Jaspers
authors.forename: Shyam K
authors.initials: SK
authors.lastname: Sharan
authors.forename: Roland
authors.initials: R
authors.lastname: Kanaar
authors.forename: Malgorzata Z
authors.initials: MZ
authors.lastname: Zdzienicka
mesh_terms: 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
chemical_list: D024682:BRCA2 Protein; D004268:DNA-Binding Proteins; D004247:DNA; D007041:Hypoxanthine Phosphoribosyltransferase; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; C495154:Rad51 protein, mouse