Kinetochore dynein generates a poleward pulling force to facilitate congression and full chromosome alignment
Kinetochore dynein generates a poleward pulling force to facilitate congression and full chromosome alignment
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DOI：
10.1038/cr.2007.65
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发表时间：
2007-08-01
期刊：
影响因子：
44.1
通讯作者：
Zhu, Xueliang
中科院分区：
文献类型：
--
作者：
Li, Yan;Yu, Wei;Zhu, Xueliang
为了进行适当的染色体分离，所有的动点必须实现两极微管(MT)附着，然后在后期开始之前与纺锤体赤道对齐。MT-末端导向的运动dynein/dynactin在早中期结合着动点，长期以来一直与染色体聚集有关。不幸的是，动力蛋白的失活通常会扰乱纺锤体的组织，从而阻碍对其动粒作用的评估。在这里，我们通过RNAi介导的ZW 10的缺失来特异性地消除动粒dynein/dynactin，ZW 10是一种对运动的动粒定位至关重要的蛋白质。延时显微镜显示，尽管染色体的聚集速度与对照细胞相似，但细胞的聚集效率显著降低。此外，尽管细胞的纺锤体正常，但细胞经常无法实现完全的染色体比对。共聚焦显微镜显示，错位的动轴是单一取向的或无连接的，大部分位于纺锤体外，表明从相反的极捕捉MTS是困难的。单星纺锤体上的动点离极点较远，仅表现出轻微的摆动。此外，用其他方法灭活动力蛋白会产生类似的表型。因此，动粒动力蛋白在单方向的动粒上产生向极的拉力，这可能有助于通过促进其适当的微管捕获来促进聚集以及染色体的完全比对，从而促进有效的双极附着。
For proper chromosome segregation, all kinetochores must achieve bipolar microtubule (MT) attachment and subsequently align at the spindle equator before anaphase onset. The MT minus end-directed motor dynein/dynactin binds kinetochores in prometaphase and has long been implicated in chromosome congression. Unfortunately, inactivation of dynein usually disturbs spindle organization, thus hampering evaluation of its kinetochore roles. Here we specifically eliminated kinetochore dynein/dynactin by RNAi-mediated depletion of ZW 10, a protein essential for kinetochore localization of the motor. Time-lapse microscopy indicated markedly-reduced congression efficiency, though congressing chromosomes displayed similar velocities as in control cells. Moreover, cells frequently failed to achieve full chromosome alignment, despite their normal spindles. Confocal microcopy revealed that the misaligned kinetochores were monooriented or unattached and mostly lying outside the spindle, suggesting a difficulty to capture MTs from the opposite pole. Kinetochores on monoastral spindles were dispersed farther away from the pole and exhibited only mild oscillation. Furthermore, inactivating dynein by other means generated similar phenotypes. Therefore, kinetochore dynein produces on monooriented kinetochores a poleward pulling force, which may contribute to efficient bipolar attachment by facilitating their proper microtubule captures to promote congression as well as full chromosome alignment.