Live cell microscopy analysis of radiation-induced DNA double-strand break motion
Live cell microscopy analysis of radiation-induced DNA double-strand break motion
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DOI：
10.1073/pnas.0810987106
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发表时间：
2009-03-03
影响因子：
11.1
通讯作者：
Taucher-Schoiz, G.
中科院分区：
文献类型：
--
作者：
Jakob, B.;Splinter, J.;Taucher-Schoiz, G.
我们通过活细胞显微镜分析研究了人类细胞DNA损伤处理的时空组织。在未受辐射的U2OS骨肉瘤和HeLa癌细胞中，DNA修复蛋白病灶呈快速受限的布朗样运动，且不受辐射影响。通过分析辐照后12小时活细胞中GFP-53BP1病灶的运动活性，我们发现受损染色质位点的移动速度更慢，在暴露于密集或稀疏电离辐射后，平均平方位移约为0.6 μ m(2)/h，很可能是由染色质的正常扩散驱动的。偶见与整个细胞核形态变化有关的较大平移运动。此外，在辐照细胞中没有形成修复团簇的普遍趋势。我们得出结论，在DNA双链断裂修复过程中，带电粒子引入多个受损位点后，受损染色质结构域的远程位移通常不会发生。偶尔和部分短暂出现的辐射诱导焦点簇形成可能代表染色质沿离子轨迹的高迁移率。这些观察结果支持了一个假设，即DNA断裂的空间接近是辐射诱导染色体交换形成所必需的。
We studied the spatiotemporal organization of DNA damage processing by live cell microscopy analysis in human cells. In unirradiated U2OS osteosarcoma and HeLa cancer cells, a fast confined and Brownian-like motion of DNA repair protein foci was observed, which was not altered by radiation. By analyzing the motional activity of GFP-53BP1 foci in live cells up to 12-h after irradiation, we detected an additional slower mobility of damaged chromatin sites showing a mean square displacement of approximate to 0.6 mu m(2)/h after exposure to densely- or sparsely-ionizing radiation, most likely driven by normal diffusion of chromatin. Only occasionally, larger translational motion connected to morphological changes of the whole nucleus could be observed. In addition, there was no general tendency to form repair clusters in the irradiated cells. We conclude that long-range displacements of damaged chromatin domains do not generally occur during DNA double-strand break repair after introduction of multiple damaged sites by charged particles. The occasional and in part transient appearance of cluster formation of radiation-induced foci may represent a higher mobility of chromatin along the ion trajectory. These observations support the hypothesis that spatial proximity of DNA breaks is required for the formation of radiation-induced chromosomal exchanges.