Sonoda E, Sasaki M S, Buerstedde J M, Bezzubova O, Shinohara A, Ogawa H, Takata M, Yamaguchi-Iwai Y, Takeda S
Bayer Chair, Department of Molecular Immunology and Allergology, Faculty of Medicine, Kyoto University, Japan.
EMBO J. 1998 Jan 15;17(2):598-608. doi: 10.1093/emboj/17.2.598.
Yeast rad51 mutants are viable, but extremely sensitive to gamma-rays due to defective repair of double-strand breaks. In contrast, disruption of the murine RAD51 homologue is lethal, indicating an essential role of Rad51 in vertebrate cells. We generated clones of the chicken B lymphocyte line DT40 carrying a human RAD51 transgene under the control of a repressible promoter and subsequently disrupted the endogenous RAD51 loci. Upon inhibition of the RAD51 transgene, Rad51- cells accumulated in the G2/M phase of the cell cycle before dying. Chromosome analysis revealed that most metaphase-arrested Rad51- cells carried isochromatid-type breaks. In conclusion, Rad51 fulfils an essential role in the repair of spontaneously occurring chromosome breaks in proliferating cells of higher eukaryotes.
酵母rad51突变体是可存活的,但由于双链断裂修复缺陷而对γ射线极其敏感。相比之下,小鼠RAD51同源物的破坏是致死性的,这表明Rad51在脊椎动物细胞中起重要作用。我们构建了鸡B淋巴细胞系DT40的克隆,其携带在可抑制启动子控制下的人RAD51转基因,随后破坏内源性RAD51基因座。在抑制RAD51转基因后,Rad51缺陷细胞在死亡前在细胞周期的G2/M期积累。染色体分析显示,大多数中期停滞的Rad51缺陷细胞携带等染色单体型断裂。总之,Rad51在高等真核生物增殖细胞中自发发生的染色体断裂修复中起重要作用。