Regulation of Chromosome Segregation

描述（由申请人提供）：细胞分裂的完美执行对所有生物体的生成和生存至关重要。在每个细胞周期中，染色体必须准确地分配给子细胞，以防止基因组不稳定和非整倍体，这是所有肿瘤和许多出生缺陷的标志。我们的目标是阐明确保准确染色体分离的机制，从而有助于理解人类疾病的基础。我们正在研究芽殖酵母中的染色体分离，因为它适合于遗传和生化分析，并且染色体分离的机制基本上是保守的。染色体分离要求复制染色体（姐妹染色单体）的着丝粒双定向，以便它们结合到来自相反纺锤体两极的微管（MT）上。虽然每对姐妹动粒都必须进行双向MT-动粒附着，但建立、维持和纠正双向错误的机制在很大程度上仍然未知。唯一已知对动粒双定向必需的蛋白质是保守的IpH（Aurora B）蛋白激酶，其定位和活性由SIM 5（INCENP）蛋白调节，并由Glc 7（蛋白磷酸酶I的催化亚基）对抗。我们已经确定了其他可能调节双取向的基因，因为当IpM功能受损时，它们变得必不可少。因此，我们将描述这些基因在双向取向中的作用，并确定它们用于调节双向取向的机制。虽然IpH和Glc 7是动粒双取向的关键，这些酶的分子靶标很少被确定。因此，我们开发了一种方法来纯化动粒，这将使我们能够识别与这些酶和双向相关的翻译后修饰。最后，我们将采取互补的遗传和生物化学方法来了解IpH和Glc 7的活动是如何在空间和时间上协调的，以确保检测和纠正双向缺陷。总的来说，这些研究应该导致更好地了解染色体分离和维持基因组稳定性在所有真核生物。

DESCRIPTION (provided by applicant): The flawless execution of cell division is essential to the generation and survival of all organisms. During every cell cycle, chromosomes must be accurately partitioned to daughter cells to prevent genomic instability and aneuploidy, a hallmark of all tumors and many birth defects. Our goal is to elucidate the mechanisms that ensure accurate chromosome segregation and therefore contribute to understanding the basis of human disease. We are studying chromosome segregation in budding yeast because it is amenable to both genetic and biochemical analyses and the mechanism of chromosome segregation is fundamentally conserved. Chromosome segregation requires that the kinetochores of duplicated chromosomes (sister chromatids) biorient such that they bind to microtubule (MTs) arising from opposite spindle poles. Although it is essential that every pair of sister kinetochores make bioriented MT-kinetochore attachments, the mechanisms that establish, maintain, and correct errors in biorientation are still largely unknown. The only protein known to be essential for kinetochore biorientation is the conserved IpH (Aurora B) protein kinase whose localization and activity is regulated by the SIM 5 (INCENP) protein and opposed by Glc7, the catalytic subunit of protein phosphatase I. We have identified additional genes that likely regulate biorientation because they become essential when IpM function is impaired. We will therefore characterize the role of these genes in biorientation and identify the mechanisms that they use to regulate biorientation. Although IpH and Glc7 are critical for kinetochore biorientation, few molecular targets of these enzymes have been identified. We have therefore developed a method to purify kinetochores that will allow us to identify post-translational modifications associated with these enzymes and biorientation. Finally, we will take complementary genetic and biochemical approaches to understand how the activities of IpH and Glc7 are spatially and temporally coordinated to ensure that biorientation defects are detected and corrected. Taken together, these studies should lead to a better understanding of chromosome segregation and the maintenance of genomic stability in all eukaryotes.