Choi Eunhee, Lee Hyunsook
Department of Biological Sciences and Research Center for Functional Cellulomics, Seoul National University, San 56-1, Shinlim-dong, Gwanak-ku, Seoul 151-742, Republic of Korea.
FEBS Lett. 2008 May 28;582(12):1700-6. doi: 10.1016/j.febslet.2008.04.028. Epub 2008 Apr 25.
The effect of double-strand DNA breaks (DSBs) on the spindle assembly checkpoint (SAC) has important implications with respect to the relationship between SAC function and chromosome instability of cancer cells. Here, we demonstrate that induction of DSBs in mitosis results in prolonged hyper-phosphorylation of the SAC protein BubR1 and association of BubR1 with kinetochores in mammalian cells. Combining single cell time-lapse microscopy with immunofluorescence, flow cytometry, and Western blot analysis in synchronized cells, we provide evidence that DSBs activate BubR1, leading to prometaphase arrest. Accordingly, elimination of BubR1 expression by siRNA resulted in the abrogation of mitotic delay in response to chromosome damage. These results suggest that BubR1 links DNA damage to kinetochore-associated SAC function.
双链DNA断裂（DSB）对纺锤体组装检查点（SAC）的影响，对于SAC功能与癌细胞染色体不稳定性之间的关系具有重要意义。在此，我们证明在有丝分裂中诱导DSB会导致哺乳动物细胞中SAC蛋白BubR1的超磷酸化延长以及BubR1与动粒的结合。通过将单细胞延时显微镜与免疫荧光、流式细胞术以及同步化细胞中的蛋白质印迹分析相结合，我们提供证据表明DSB激活BubR1，导致前中期停滞。因此，通过小干扰RNA（siRNA）消除BubR1表达可消除对染色体损伤的有丝分裂延迟反应。这些结果表明，BubR1将DNA损伤与动粒相关的SAC功能联系起来。
