Mechanisms of spindle formation

描述（由申请人提供）：有丝分裂是细胞生命的关键阶段。在这个阶段，双极纺锤体结构被组织起来，将重复的染色体分离到两个子细胞中。主轴组织和功能要求精密、坚固和逼真。与纺锤体相关的缺陷可导致染色体分离缺陷或非整倍体，这与某些类型的癌症有关。纺锤体是由微管、微管相关蛋白（MAPs）、分子马达和其他调节蛋白组成的大分子机器。分子马达引起了人们的强烈兴趣，它执行交联和滑动微管以形成双极纺锤体，或解聚微管以保持适当的纺锤体长度，或将染色体携带到相反的纺锤极。令人惊讶的是，虽然我们对有丝分裂中的马达有了很多了解，但我们对map和其他调节蛋白以及它们如何与马达协调以实现正确的纺锤体形成仍然知之甚少。我的实验室使用相对简单的分裂酵母、裂糖酵母和人类培养细胞来研究纺锤体组织和功能的保守机制。这个特别的项目侧重于如何在有丝分裂开始时形成最初的双极纺锤体，这一阶段被称为前期。我们将重点放在有助于纺锤体形成的map上。利用裂变酵母菌作为基因发现工具，我们已经开始定义一个新基因的作用，我们称之为psr1+（极分离调节器1）。我们的研究表明，psr1p在脑电过程中组织了初始双极主轴

DESCRIPTION (provided by applicant): Mitosis is a key stage during the life of a cell. It is the stage where a bipolar spindle structure is organized to segregate duplicated chromosomes into the two daughter cells. Spindle organization and function require exquisite precision, robustness and fidelity. Defects associated with the spindle can lead to defects in chromosomal segregation, or aneuploidy, which has been correlated with some types of cancer. The spindle is a macromolecular machine made of microtubules, microtubule-associated proteins (MAPs), molecular motors and other regulatory proteins. Of intense interest have been molecular motors, which perform work such as cross-linking and sliding microtubules apart to form the bipolar spindle, or to depolymerize microtubules to maintain proper spindle lengths, or to carry chromosomes to opposite spindle poles. Surprisingly, while we have learned much about motors involved in mitosis, we still know very little about the MAPs and other regulatory proteins and how they coordinate with motors to bring about proper spindle formation. My laboratory uses the relatively simple fission yeast Schizosaccharomyces pombe and human cultured cells to address conserved mechanisms of spindle organization and function. This particular project focuses on how the initial bipolar spindle is formed at the start of mitosis, the stage termed prophase. We focus on the MAPs that contribute to spindle formation. Using fission yeast as a gene discovery tool, we have begun to define the roles of a new gene we called psr1+ (poles separation regulator 1). Our work indicates that psr1p organizes the initial bipolar spindle during prophase. Psr1-deletion leads to high frequency of monopolar spindles and subsequent chromosome segregation defects. Fission yeast psr1+ appears to have a human functional homolog. We have begun to characterize a novel human gene we called PSR1. In HeLa cells, siRNA of PSR1 also leads to high frequency of monopolar spindles and subsequent chromosome segregation defects. This proposal aims to combine modern cell and molecular biology techniques in fission yeast and human cultured cells, biochemistry, high-resolution optical live-cell imaging, and innovative microfluidic techniques to control cellular microenvironment, to reach a mechanistic understanding of bipolar spindle formation.