Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway 091 524 411, Ireland.
J Cell Biol. 2011 Apr 18;193(2):307-18. doi: 10.1083/jcb.201012093. Epub 2011 Apr 11.
The principal microtubule-organizing center in animal cells, the centrosome, contains centrin, a small, conserved calcium-binding protein unique to eukaryotes. Several centrin isoforms exist and have been implicated in various cellular processes including nuclear export and deoxyribonucleic acid (DNA) repair. Although centrins are required for centriole/basal body duplication in lower eukaryotes, centrin functions in vertebrate centrosome duplication are less clear. To define these roles, we used gene targeting in the hyperrecombinogenic chicken DT40 cell line to delete all three centrin genes in individual clones. Unexpectedly, centrin-deficient cells underwent normal cellular division with no detectable cell cycle defects. Light and electron microscopy analyses revealed no significant difference in centrosome composition or ultrastructure. However, centrin deficiency made DT40 cells highly sensitive to ultraviolet (UV) irradiation, with Cetn3 deficiency exacerbating the sensitivity of Cetn4/Cetn2 double mutants. DNA damage checkpoints were intact, but repair of UV-induced DNA damage was delayed in centrin nulls. These data demonstrate a role for vertebrate centrin in nucleotide excision repair.
动物细胞中的主要微管组织中心是中心体，它包含中心粒蛋白，这是一种存在于真核生物中的小型、保守的钙结合蛋白。存在几种中心粒蛋白同工型，它们与包括核输出和脱氧核糖核酸（DNA）修复在内的各种细胞过程有关。尽管中心粒蛋白对于低等真核生物的中心体/基体的复制是必需的，但中心粒蛋白在脊椎动物中心体复制中的作用还不太清楚。为了确定这些作用，我们使用基因靶向技术在高度易发生重组的鸡 DT40 细胞系中单独的克隆中删除了所有三个中心粒基因。出乎意料的是，缺乏中心粒的细胞进行了正常的细胞分裂，没有检测到细胞周期缺陷。光和电子显微镜分析显示，中心体的组成或超微结构没有明显差异。然而，中心粒的缺乏使 DT40 细胞对紫外线（UV）照射非常敏感，Cetn3 的缺乏使 Cetn4/Cetn2 双突变体的敏感性更加恶化。DNA 损伤检查点完好无损，但中心粒缺失细胞中 UV 诱导的 DNA 损伤的修复被延迟。这些数据表明脊椎动物中心粒蛋白在核苷酸切除修复中发挥作用。
