Mitotic Motors in the Drosophila Embryo.

描述(申请人提供)：有丝分裂纺锤体为双极， 使用基于多个微管(MT)的电机的自组织蛋白质机器 蛋白质进行自我组装并分离姐妹染色单体。宏伟的目标 这里提出的工作的一部分是理解这些马达在 有丝分裂的机制。这项提议的概念框架是 纺锤体形态发生，以纺锤体位置的变化为特征 极点，涉及到稳态结构之间的转变。每种稳定状态 结构取决于多个因素产生的力的微妙平衡 拮抗和互补的马达，并通过向上或向上倾斜这种平衡 下调马达的子集会驱动稳定状态之间的转换。 这些转变等同于特定的有丝分裂运动，如 主轴极的重新定位。 具体目标旨在测试这多个要素 电机依赖的暂态稳态假说和提炼电流 描述双极运动在电机中的作用的模型，C-末端运动 纺锤体极定位中的马达和胞浆动力蛋白。目标是1.到 测试额外的有丝分裂马达在极点定位中的作用，2。测试 C-末端动蛋白下调启动后期假说 纺锤体延长，3.采用体内和体外结构-功能测定 验证双极运动蛋白和C-末端运动蛋白使用 滑动灯丝机构来定位主轴极点4.测试 极点定位中电机驱动的MT滑动与MT组件的动力学，以及5. 开发解释电机依赖的主轴极点的定量模型 分离曲线。 我们的研究策略将开发果蝇合胞胚胎期 胚胎，可以进行生化、遗传和细胞学分析 有丝分裂运动功能。研究结果将有助于理解 有丝分裂的基本机制，并可能为深入了解一些 纺锤体功能障碍和染色体分离 特定的出生日期

DESCRIPTION (provided by applicant): The mitotic spindle is a bipolar, self-organizing protein machine that uses multiple microtubule (MT)-based motor proteins to assemble itself and to segregate sister chromatids. The broad aim of the work proposed here is to understand the roles of these motors in the mechanism of mitosis. The conceptual framework underlying the proposal is that spindle morphogenesis, characterized by changes in the positioning of spindle poles, involves transitions between steady state structures. Each steady state structure depends on a delicate balance of forces generated by multiple antagonistic and complementary motors, and tipping this balance by up- or down-regulating subsets of motors drives transitions between steady states. These transitions equate to specific mitotic movements, such as the repositioning of spindle poles. The specific aims are designed to test elements of this multiple motor-dependent transient steady state hypothesis and to refine our current model that describes the role of bipolar kinesin motors, C-terminal kinesin motors and cytoplasmic dynein in spindle pole positioning. The aims are 1. To test the roles of additional mitotic motors in pole positioning, 2. To test the hypothesis that down-regulating the C-terminal kinesin initiates anaphase spindle elongation, 3. To use structure-function assays in vivo and in vitro to test the hypothesis that bipolar kinesins and the C-terminal kinesins use a sliding filament mechanism to position spindle poles 4. To test the roles of motor-driven MT sliding versus MT assembly dynamics in pole positioning, and 5. To develop quantitative models that explain the motor-dependent spindle pole separation curves. Our research strategy will exploit the Drosophila syncytial blastoderm-stage embryo, which is amenable to biochemical, genetic and cytological analysis of mitotic motor function. The results will contribute to an understanding of the basic mechanisms of mitosis and may provide insights into some of the dysfunctions in spindle action and chromosome segregation that characterize certain birth de