Microtubule motors and generation of cell polarity

 描述(申请人提供)：细胞极性的产生是一个关键的生物学过程，它定义了正常细胞生长和分化的多个方面。这项建议的主要目标是了解微管和微管马达如何有助于细胞极性的产生和细胞骨架的组织。在之前的资助期间，我们的团队发现细胞中的微管在细胞质中活跃地运输，一个微管作为轨迹，另一个作为运动蛋白的货物。这种运动是由传统的Kinesin(Kinesin-1)提供动力的，Kinesin-1是一种主要的微管马达，以前只涉及细胞器沿微管的运动。在神经元和非神经元细胞的突起形成过程中，需要动蛋白驱动微管的运动。在这里，我们建议研究动蛋白和其他微管马达的微管运动在细胞极性的产生中的作用，特别是在神经元和非神经元细胞的突起形成中的作用。我们最初将使用果蝇S2细胞来鉴定参与微管滑动和突起形成的分子成分，因为这些细胞对RNAi击倒蛋白质高度敏感，而且微管运动和突起形成易于可视化、跟踪、量化和操纵。一旦确定了这些成分，我们将使用果蝇神经元来研究这些成分如何在培养和体内神经发生中促进轴突的形成。我们将使用果蝇遗传学的工具，结合活神经元的成像和微操作来解决这些问题。本项目要研究的三个重叠区域是：(I)运动驱动的微管滑动如何组织极化微管阵列？(Ii)运动驱动的微管滑动在细胞中是如何调节的？(3)微管滑动在损伤后轴突再生中的作用是什么？我们认为，神经元中驱动和调节微管滑动的蛋白质可以作为药物刺激轴突生长的良好新靶点，这是成功治疗神经元损伤和神经退行性疾病所必需的。

 DESCRIPTION (provided by applicant): Generation of cell polarity is a key biological process that defines multiple aspects of normal cell growth, and differentiation. The major goal of this proposal is to understand how microtubules and microtubule motors contribute to generation of cell polarity and organization of the cytoskeleton. During the previous funding period our group discovered that microtubules in the cell are actively transported in the cytoplasm, with one microtubule serving as a track and another as a cargo for a motor protein. This movement is powered by conventional kinesin (kinesin-1), a major microtubule motor that has previously only been implicated in movement of organelles along microtubules. Microtubule movement by kinesin is required for formation of processes by neurons and non-neuronal cells. Here we propose to study the role of microtubule movements by kinesin and other microtubule motors in generation of cell polarity and specifically in formation of processes by neuronal and non-neuronal cells. We will initially use Drosophila S2 cells for identification of molecular components involved in microtubule sliding and formation of processes because these cells are highly sensitive to protein knock-down by RNAi and because microtubule movement and process formation can easily be visualized, tracked, quantified and manipulated. Once the components are identified, we will use Drosophila neurons to study how these components contribute to formation of neurites in culture and neurogenesis in vivo. We will use tools of Drosophila genetics combined with imaging of live neurons and micromanipulation to address these questions. The three overlapping areas to be investigated in this project are: (i) How does motor-driven microtubule sliding organize polarized microtubule arrays? (ii) How is motor-driven microtubule sliding regulated in a cell? (iii) What is the role of microtubule sliding in axon regeneration after injury? We believe that proteins driving and regulating microtubule sliding in neurons could serve as excellent new therapeutic targets for pharmacological stimulation of neurite outgrowth required for successful treatment of neuronal injuries and neurodegenerative diseases.