Levesque A A, Compton D A
Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA.
J Cell Biol. 2001 Sep 17;154(6):1135-46. doi: 10.1083/jcb.200106093.
Chromokinesins have been postulated to provide the polar ejection force needed for chromosome congression during mitosis. We have evaluated that possibility by monitoring chromosome movement in vertebrate-cultured cells using time-lapse differential interference contrast microscopy after microinjection with antibodies specific for the chromokinesin Kid. 17.5% of cells injected with Kid-specific antibodies have one or more chromosomes that remain closely opposed to a spindle pole and fail to enter anaphase. In contrast, 82.5% of injected cells align chromosomes in metaphase, progress to anaphase, and display chromosome velocities not significantly different from control cells. However, injected cells lack chromosome oscillations, and chromosome orientation is atypical because chromosome arms extend toward spindle poles during both congression and metaphase. Furthermore, chromosomes cluster into a mass and fail to oscillate when Kid is perturbed in cells containing monopolar spindles. These data indicate that Kid generates the polar ejection force that pushes chromosome arms away from spindle poles in vertebrate-cultured cells. This force increases the efficiency with which chromosomes make bipolar spindle attachments and regulates kinetochore activities necessary for chromosome oscillation, but is not essential for chromosome congression.
染色体驱动蛋白被认为可提供有丝分裂期间染色体汇聚所需的极向弹射力。我们通过延时微分干涉相差显微镜观察脊椎动物培养细胞中的染色体运动，对这种可能性进行了评估。在用针对染色体驱动蛋白Kid的特异性抗体显微注射后，17.5%注射了Kid特异性抗体的细胞有一条或多条染色体与纺锤体极紧密相对，无法进入后期。相比之下，82.5%的注射细胞在中期使染色体排列整齐，进入后期，并且显示出与对照细胞无显著差异的染色体速度。然而，注射细胞缺乏染色体振荡，并且染色体取向不典型，因为在汇聚和中期染色体臂都朝着纺锤体极延伸。此外，在含有单极纺锤体的细胞中，当Kid受到干扰时，染色体会聚集成团且无法振荡。这些数据表明，Kid在脊椎动物培养细胞中产生将染色体臂推离纺锤体极的极向弹射力。这种力提高了染色体形成双极纺锤体附着的效率，并调节染色体振荡所需的动粒活动，但对于染色体汇聚并非必不可少。
