Molecular Analysis of Chromosome Segregation

项目摘要 生命依赖于每一次细胞分裂时遗传物质的准确传递。此过程中的错误 导致非整倍体，这与肿瘤发生、出生缺陷和细胞死亡有关。复制 染色体被一种基于微管的分子机器--有丝分裂--捕获并分离 纺锤形。纺锤体是两极的，每个纺锤体极携带着正好互补的染色体 每一个子细胞。在有丝分裂期间，微管从极点成核，并捕获和组织 染色体。动点是位于着丝粒DNA上的大型多蛋白细胞器，与 微管，并将染色体固定在两极。我们的工作重点放在每一端 微管、纺锤体极和动点。 纺锤体的形态发生需要空间控制的微管成核。使用以下组合 重建和体内分析，我们将测试解决微管成核如何的假说 被激活并在空间上受到调控。 动点将染色体连接到微管上，强度和可塑性惊人地结合在一起。 附着物在张力下是可移动和坚固的，但也可以快速地破坏稳定性 监管信号。因此，动粒处于修复错误的纠错机制的中心 不正确的依恋是因为缺乏“适当的”紧张感。鉴定出的蛋白质是 在拉力作用下，连杆强度的测量和充分强度的要求 附件是这个项目的第二个关注点。 我们已经发现，就个体而言，没有动粒蛋白能以强度或寿命结合微管。 要重建天然动点所表现出的微管附着的全部强度，需要 接触微管的蛋白质与微管内部的蛋白质之间的协同作用 动毛虫。我们将使用基于重建的方法和体内分析来测试 对这种协同的亲和力、亲和力和几何形状。通过这种方式，我们将理解整体是如何实现的 比各部分之和更大的性质。此外，通过利用我们重组的动粒，我们 将测试触发纠错的张力信号是如何从 动粒并由修复机构接收。

Project Summary Life depends on the accurate transmission of genetic material at each cell division. Errors in this process lead to aneuploidy, which is implicated in oncogenesis, birth defects and cell death. Duplicated chromosomes are captured and segregated by a microtubule-based molecular machine, the mitotic spindle. The spindle is bipolar and each spindle pole carries an exact complement of chromosomes to each daughter cell. During mitosis, microtubules nucleate from the poles and capture and organize the chromosomes. Kinetochores, large multiprotein organelles located at the centromeric DNA, bind the microtubules and anchor the chromosomes to the poles. Our work focuses on each end of the microtubule, the spindle poles and the kinetochores. Spindle morphogenesis requires spatially controlled microtubule nucleation. Using a combination of reconstitution and in vivo analysis, we will test hypotheses that address how microtubule nucleation is activated and spatially regulated. Kinetochores attach chromosomes to microtubules with a striking combination of strength and plasticity. The attachments are mobile and robust under tension, but can also rapidly destabilize in response to regulatory signals. As such, the kinetochore is at the center of an error correction mechanism that repairs incorrect attachments sensed by a lack of ‘proper’ tension. The identification of the proteins that are under tension, the measurement of the strength of the linkages and the requirements for the full strength of attachments are together the second focus of this project. We have found that individually no kinetochore protein binds the microtubule with strength or longevity. To reconstitute the full strength of microtubule attachment exhibited by native kinetochores requires synergy between proteins in contact with the microtubule with proteins within the interior of the kinetochore. We will use a reconstitution-based approach and in vivo analysis to test the contribution of affinity, avidity and geometry to this synergy. In this way we will understand how the whole achieves greater properties than the sum of the parts. In addition, by exploiting our reconstituted kinetochore, we will test hypotheses for how the tension signal that triggers error correction is transmitted from the kinetochore and received by the repair mechanisms.