Cytoplasmic dynein has been implicated in diverse mitotic functions, several involving its association with kinetochores. Much of the supporting evidence comes from inhibition of dynein regulatory factors. To obtain direct insight into kinetochore dynein function, we expressed a series of dynein tail fragments, which we find displace motor-containing dynein heavy chain (HC) from kinetochores without affecting other subunits, regulatory factors, or microtubule binding proteins. Cells with bipolar mitotic spindles progress to late prometaphase-metaphase at normal rates. However, the dynein tail, dynactin, Mad1, and BubR1 persist at the aligned kinetochores, which is consistent with a role for dynein in self-removal and spindle assembly checkpoint inactivation. Kinetochore pairs also show evidence of misorientation relative to the spindle equator and abnormal oscillatory behavior. Further, kinetochore microtubule bundles are severely destabilized at reduced temperatures. Dynein HC RNAi and injection of anti-dynein antibody in MG132-arrested metaphase cells produced similar effects. These results identify a novel function for the dynein motor in stable microtubule attachment and maintenance of kinetochore orientation during metaphase chromosome alignment.
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机译：细胞质动力蛋白涉及多种有丝分裂功能，其中一些涉及其与动植物的联系。许多支持证据来自抑制动力蛋白调节因子。为了直接了解动线素的动力蛋白功能，我们表达了一系列动力蛋白的尾巴片段，我们发现它们从动植物中取代了含有马达的动力蛋白重链（HC），而不影响其他亚基，调节因子或微管结合蛋白。具有双极有丝分裂纺锤体的细胞以正常速率进展到晚期前中期至中期。但是，动力蛋白的尾巴，动力蛋白，Mad1和BubR1在对齐的动植物上持续存在，这与动力蛋白在自我清除和纺锤体装配检查点失活中的作用一致。线粒体对也显示出相对于主轴赤道方向错误和异常振荡行为的证据。此外，线粒体微管束在降低的温度下严重不稳定。 Dynein HC RNAi和在MG132停滞的中期细胞中注射抗Dynein抗体产生了相似的效果。这些结果确定了动力蛋白在稳定的微管附着和中期染色体对齐过程中保持动线粒体定向中的新功能。
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