Molecular Analysis of the Kinetochore-Microtubule Interface

描述（由申请人提供）：人体中的每个细胞包含46个不同的染色体，即大单位的DNA，编码该细胞生长、分裂和执行其特殊功能的指令。在有丝分裂过程中，当细胞分裂时，这些染色体中的每一条都必须准确地分配给两个新的子细胞。如果这一过程发生错误，即使是一个染色体，所产生的子细胞将失去或获得数千个基因和它们所包含的指令。这种类型的染色体分离错误可导致细胞死亡，并被认为有助于肿瘤发生。事实上，多达70%的肿瘤被观察到具有异常数目的染色体。为了促进DNA在有丝分裂过程中的分离，染色体必须与称为微管的棒状聚合物产生物理附着，微管提供了移动染色体的结构和力量。破坏这些微管与染色体连接的能力的抗有丝分裂药物通常用于癌症化疗。然而，由于微管在神经系统中的额外作用，许多这些药物具有有害的继发性影响。染色体分离的一个关键因素是一个大的蛋白质结构，称为动粒，形成染色体和微管之间的界面。预计对动粒活性的抑制靶向癌细胞，同时避免与微管结合化疗药物相关的剂量限制性神经元毒性。事实上，针对几种动粒蛋白的抑制剂目前正在临床试验中。确定每种人动粒蛋白的特异性活性对于提供它们在染色体分离中的功能的背景、评价用于诊断和治疗疾病的最佳靶标以及产生适合于分离小分子抑制剂的测定是至关重要的。拟议的工作将分析与微管产生相互作用所需的人类动粒蛋白的功能和调节。这项工作将集中在两个关键的，最近确定的群体的kinetochore相关的蛋白质，结合微管聚合物直接。这些研究将定义这些蛋白质的特性，并确定这些蛋白质与微管相互作用的机制，剖析控制着丝粒微管附着的上游激酶对它们的调节，并检查它们在人类细胞中的功能。总的来说，这些研究将确定运动编排微管相互作用的基础，最终为癌症的诊断和治疗实验提供基础。

DESCRIPTION (provided by applicant): Each cell in the human body contains 46 different chromosomes, large units of DNA that encode instructions for that cell to grow, divide, and carry out its specialized functions. During mitosis, when a cell divides, each of these chromosomes must be accurately distributed to the two new daughter cells. If this process occurs incorrectly for even a single chromosome, the resulting daughter cells will lose or gain thousands of genes and the instructions that they contain. This type of error in chromosome segregation can result in the death of the cell and is thought to contribute to tumorigenesis. Indeed, as many as 70% of tumors are observed to have abnormal numbers of chromosomes. To facilitate the segregation of DNA during mitosis, chromosomes must generate physical attachments to rod-like polymers termed microtubules that provide the structure and forces to move the chromosomes. Anti-mitotic drugs that disrupt the ability of these microtubules to connect with the chromosomes are routinely used for cancer chemotherapy. However, many of these drugs have deleterious secondary affects due to additional roles for microtubules in the nervous system. A key player in chromosome segregation is a large proteinaceous structure termed the kinetochore that forms the interface between the chromosomes and the microtubules. Inhibition of kinetochore activities is predicted target cancer cells while avoiding the dose-limiting neuronal toxicity associated with microtubule-binding chemotherapy drugs. Indeed, inhibitors against several kinetochore proteins are currently in clinical trials. Determining the specific activities of each human kinetochore protein is crucial to provide a context for their functions in chromosome segregation, to evaluate the best targets for the diagnosis and treatment of disease, and to generate assays suitable for the isolation of small molecule inhibitors. The proposed work will analyze the function and regulation of the human kinetochore proteins that are required to generate interactions with microtubules. This work will focus on two key, recently identified groups of kinetochore-associated proteins that bind to microtubule polymers directly. These studies will define the properties of these proteins and determine the mechanisms by which these proteins interact with microtubules, dissect their regulation by upstream kinases that control kinetochore-microtubule attachments, and examine their functions in human cells. In total, these studies will define the basis for kinetochore-microtubule interactions that will ultimately provide the foundation for experiments on the diagnosis and treatment of cancer.