title: Cooperative roles of vertebrate Fbh1 and Blm DNA helicases in avoidance of crossovers during recombination initiated by replication fork collapse.
abstract: Fbh1 (F-box DNA helicase 1) orthologues are conserved from Schizosaccharomyces pombe to chickens and humans. Here, we report the disruption of the FBH1 gene in DT40 cells. Although the yeast fbh1 mutant shows an increase in sensitivity to DNA damaging agents, FBH1(-)(/)(-) DT40 clones show no prominent sensitivity, suggesting that the loss of FBH1 might be compensated by other genes. However, FBH1(-)(/)(-) cells exhibit increases in both sister chromatid exchange and the formation of radial structures between homologous chromosomes without showing a defect in homologous recombination. This phenotype is reminiscent of BLM(-)(/)(-) cells and suggests that Fbh1 may be involved in preventing extensive strand exchange during homologous recombination. In addition, disruption of RAD54, a major homologous recombination factor in FBH1(-)(/)(-) cells, results in a marked increase in chromosome-type breaks (breaks on both sister chromatids at the same place) following replication fork arrest. Further, FBH1BLM cells showed additive increases in both sister chromatid exchange and the formation of radial chromosomes. These data suggest that Fbh1 acts in parallel with Bloom helicase to control recombination-mediated double-strand-break repair at replication blocks and to reduce the frequency of crossover.
authors.affiliation: Department of Radiation Genetics, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Masaoki
authors.initials: M
authors.lastname: Kohzaki
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hatanaka
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Sonoda
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Yamazoe
authors.forename: Koji
authors.initials: K
authors.lastname: Kikuchi
authors.forename: Nguyen
authors.initials: N
authors.lastname: Vu Trung
authors.forename: Dávid
authors.initials: D
authors.lastname: Szüts
authors.forename: Julian E
authors.initials: JE
authors.lastname: Sale
authors.forename: Hideo
authors.initials: H
authors.lastname: Shinagawa
authors.forename: Masami
authors.initials: M
authors.lastname: Watanabe
authors.forename: Shunichi
authors.initials: S
authors.lastname: Takeda
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002166:Camptothecin / Q000494:pharmacology; D002645:Chickens; D002945:Cisplatin / Q000494:pharmacology; D003434:Crossing Over, Genetic / Q000187:drug effects / Q000528:radiation effects; D004249:DNA Damage; D004265:DNA Helicases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication / Q000187:drug effects / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000378:metabolism; D052218:Fanconi Anemia Complementation Group C Protein / Q000172:deficiency / Q000378:metabolism; D005720:Gamma Rays; D017353:Gene Deletion; D018390:Gene Targeting; D042822:Genomic Instability / Q000187:drug effects / Q000528:radiation effects; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D053484:RecQ Helicases; D014466:Ultraviolet Rays; D014714:Vertebrates / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D052218:Fanconi Anemia Complementation Group C Protein; D008741:Methyl Methanesulfonate; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; D053484:RecQ Helicases; D002945:Cisplatin; D002166:Camptothecin