Mitotic Motors in the Drosophila Embryo.

描述（由申请人提供）：有丝分裂纺锤体是双极的， 自组织蛋白质机器，使用多个微管（MT）为基础的电机 蛋白质组装本身和分离姐妹染色单体。广泛的目标 这里提出的工作是了解这些马达在 有丝分裂的机制该建议的基本概念框架是， 纺锤体形态发生，以纺锤体位置变化为特征 极点，涉及稳态结构之间的过渡。每个稳态 结构取决于多种力量的微妙平衡， 拮抗和互补的马达，并通过向上或向下倾斜这种平衡， 下调马达的子集驱动稳态之间的转换。 这些转变等同于特定的有丝分裂运动，例如 主轴杆的重新定位。 具体的目标是为了测试这个多重的元素 依赖于电机的瞬态稳态假设，并完善我们的电流 描述双极驱动蛋白在马达中的作用的模型， 马达和细胞质动力蛋白在纺锤体极定位中的作用。目标是1。到 测试额外的有丝分裂马达在磁极定位中的作用，2.测试 下调C-末端驱动蛋白启动细胞分裂后期的假说 纺锤体伸长，3.使用体内和体外结构-功能分析， 测试双极驱动蛋白和C-末端驱动蛋白使用 滑动细丝机构以定位主轴杆4。测试的作用 电机驱动的MT滑动与MT组件动力学在极定位，和5。 开发定量模型，解释电机依赖的主轴极 分离曲线 我们的研究策略将利用果蝇合胞胚盘阶段 胚胎，这是经得起生化，遗传和细胞学分析， 有丝分裂运动功能研究结果将有助于了解 有丝分裂的基本机制，并可能提供一些见解， 纺锤体功能障碍和染色体分离， 某些出生地

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