Mechanisms of Spindle Assembly

遗传物质与子细胞的可靠分离对于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个染色体中的每一个。 子细胞染色体分离是由有丝分裂纺锤体介导的，纺锤体由 微管（MT）和相关蛋白的动态阵列。而主轴装配的通道 尽管细胞类型不同，但所有纺锤体都具有共同的结构特征。MT负端是 集中在两极，而更具活力的正末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蛋白质维持的基本组织， 调节纺锤体MT动力学以及通过移动染色体和MT的马达。剂 改变MT的聚合动力学或运动功能的药物在治疗多发性骨髓瘤中是有效的。 癌的因此，阐明MT动态调节的分子机制， 纺锤体组装过程中的组织不仅对我们理解细胞分裂至关重要， 新一代的抗有丝分裂药物来帮助对抗癌症。尽管我们了解许多 分子调节纺锤体动力学和组织，目前尚不清楚这些活动是如何进行的。 在有丝分裂过程中协调，以确保适当的空间和时间控制。在本提案中，我们将：1） 通过验证假设，定义磷酸化如何控制MCAK的活性和空间调节 MCAK活性受蛋白质构象变化的调节， 并通过MCAK上发生的不同磷酸化修饰在整个有丝分裂中暂时调节。（二） 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， 测试Kif18B和MCAK在纺锤体期间的不同时间调节星形MT动力学的假设， 组装件.我们还将测试MT滑动和MT动力学都有助于调节的模型， 通过测试HSET或Kif18A扰动是否会改变纺锤体MT动力学， 到有丝分裂的进程。3)确定机械手动力学和滑动影响主轴的机制 通过阐明不同MT的MT动力学的机制基础， 亚群受到不同的调控，以及这些调控因子如何改变下游靶点， 关于纺锤体的组织这些研究将为MT动力学如何提供重要的新见解 和MT滑动活动协调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.