Mechanisms of Spindle Assembly

将遗传物质忠实地分离到子代细胞对生物体的生存至关重要。 细胞必须复制其每条染色体的DNA，并将一个拷贝分配给两条染色体中的每一条 子代细胞。染色体分离是由有丝分裂纺锤体介导的，纺锤体由一个 微管及其相关蛋白的动态阵列。而主轴装配的路径 根据细胞类型的不同，所有的纺锤体都有共同的结构特征。MT减号结束为 聚焦于两极，而更具活力的正端与纺锤体上的染色体相互作用 赤道。正确的纺锤体功能依赖于由以下蛋白质维持的潜在组织 调节纺锤体MT的动态，以及通过移动染色体和MT的马达。代理 改变MTS的聚合动力学或运动功能对多发性硬化症的治疗是有效的 癌症。因此，阐明MT动态调控的分子机制和 纺锤体组装过程中的组织将不仅对我们理解细胞分裂至关重要，而且对 新一代的抗有丝分裂药物有助于抗击癌症。尽管我们对许多 调节纺锤体动力学和组织的分子，目前还不知道这些活动是如何进行的 在有丝分裂期间进行协调，以确保适当的空间和时间控制。在本提案中，我们将：1) 通过检验假设确定磷酸化如何控制MCAK的活性和空间调节 MCAK活性受蛋白质构象变化的调节，这种变化在空间上既受调控 并在整个有丝分裂过程中通过MCAK上发生的不同的磷酸化修饰来实现。2) 通过以下方式定义MT动力学和滑动的变化如何影响纺锤体组织和有丝分裂进程 Kif18B和MCAK在纺锤体不同时间调控星体MT动力学的假设检验 集合。我们还将检验MT滑动和MT动力学都有助于调节 通过测试HSET或Kif18A扰动是否改变了主轴MT动力学并对 到有丝分裂进程。3)定义MT动力学和滑动影响主轴的机制 通过阐明不同机器翻译动力学的机制基础来组织 子群体受到不同的监管，以及这些监管机构如何改变下游的行动目标 关于纺锤形组织。总之，这些研究将为MT动力学提供重要的新见解 MT滑动活动是协调的，以确保适当的有丝分裂进程。

The faithful segregation of genetic material to daughter cells is essential for the survival of an organism. The cell must replicate the DNA of each of its chromosomes and distribute one copy to each of the two daughter cells. Chromosome segregation is mediated by the mitotic spindle, which is composed of a dynamic array of microtubules (MTs) and associated proteins. While the pathways for spindle assembly differ depending on the cell type, all spindles share common structural features. The MT minus ends are focused into two poles, while the more dynamic plus ends interact with chromosomes at the spindle equator. Proper spindle function relies on an underlying organization that is maintained by proteins that regulate spindle MT dynamics as well as by the motors that move the chromosomes and the MTs. Agents that alter the polymerization dynamics of MTs or motor function are effective in the treatment of multiple cancers. Therefore, elucidating the molecular mechanism of the regulation of MT dynamics and organization during spindle assembly will be crucial not only to our understanding of cell division but also for the generation of new anti-mitotic drugs to help combat cancer. Despite our understanding of many of the molecules that regulate spindle dynamics and organization, it is not known how these activities are coordinated during mitosis to insure proper spatial and temporal control. In the present proposal we will: 1) Define how phosphorylation controls the activity and spatial regulation of MCAK by testing the hypothesis that MCAK activity is regulated by conformational changes in the protein that are regulated both spatially and temporally throughout mitosis by the different phosphorylation modifications that occur on MCAK. 2) Define how changes in MT dynamics and sliding affect spindle organization and mitotic progression by testing the hypothesis that Kif18B and MCAK regulate astral MT dynamics at distinct times during spindle assembly. We will also test the model that both MT sliding and MT dynamics contribute to the regulation of spindle length by testing whether HSET or Kif18A perturbation alters spindle MT dynamics and contributes to mitotic progression. 3) Define the mechanisms by which MT dynamics and sliding affect spindle organization by elucidating the mechanistic basis of how the MT dynamics of the different MT subpopulations are differentially regulated and how these regulators alter the downstream targets that act on spindle organization. Together these studies will provide significant new insight into how MT dynamics and MT sliding activities are coordinated to insure proper mitotic progression.