Molecular Analysis of Chromosome Segregation

项目摘要 生命取决于每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 染色体被一个基于微管的分子机器--有丝分裂细胞--捕获并分离。 纺锤体。纺锤体是双极的，每个纺锤体极携带完全互补的染色体， 每个子细胞在有丝分裂过程中，微管从两极成核，并捕获和组织细胞。 染色体着丝粒是位于着丝粒DNA上的大型多蛋白质细胞器， 微管和锚染色体的两极。我们的工作重点是每一个结束 微管、纺锤极和动粒。 纺锤体形态发生需要空间控制的微管成核。结合使用 重建和体内分析，我们将测试假设，解决如何微管成核是 激活并在空间上调节。 动粒将染色体附着在微管上，具有惊人的强度和可塑性。 附件是移动的并且在张力下是坚固的，但是也可以响应于压力而快速地不稳定。 监管信号。因此，动粒处于错误纠正机制的中心， 由于缺乏“适当”的张力而感觉到的不正确的附件。对蛋白质的鉴定 在张力下，连接强度的测量和对全部强度的要求 附件是本项目的第二个重点。 我们已经发现，单个的动粒蛋白没有强度或寿命结合微管。 要重建天然动粒所表现出的微管附着的全部强度， 与微管接触的蛋白质与微管内部的蛋白质之间的协同作用 动粒我们将使用一种基于重组的方法和体内分析来测试 亲和力、贪婪度和几何形状与这种协同作用的关系。这样我们就能理解整体是如何实现的 比各部分的总和更大的属性。此外，通过利用我们重组的动粒， 将测试关于触发纠错的张力信号如何从 动粒并被修复机制接收。

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.