Regulation of Microtubules by Rho GTPases

该项目的总体目标是了解Rho家族的小GTP酶如何调节稳定性， 微管（MT）在细胞极化过程中的组织。MT的动态使他们能够 细胞极化过程中对外部信号的反应，但对这些信号如何转导知之甚少 MT或参与MT重排的蛋白质。细胞迁移到体外伤口中是一种 一个模型系统，用于研究调节MT的信号，作为可溶性、基质和细胞相关的贡献 因素是可以分解的。在上一个资助期内，我们发现两次重组的流动电话在伤口， 边缘迁移成纤维细胞，异常稳定MT亚群的形成和MT的重新定向 组织中心（MTOC），都是由血清溶血磷脂酸（LPA）触发，但分别 由Rho和Cdc42 GTP酶调节。这两种重排被认为涉及MT的相互作用， 结束于细胞皮层，这一过程被称为MT捕获。我们鉴定了mDia、EB 1、APC、GSK 30和新的 PKC作为Rho下游工作的因子和Cdc42下游工作的两个独立途径;一个 涉及部分），动力蛋白和动力蛋白在细胞中心维持MTOC，其他涉及MRCK， 肌动蛋白和肌球蛋白II在核的一种新的奖励运动中发挥作用。目前的目标是进一步 通过以下方式探索MT稳定化的机制：探索mDia对MT和肌动蛋白的活性是如何影响 通过测试mDia是否可以直接影响MT稳定以及EB1和APC是否可以 影响mDia对MT的活性。我们还将测试mDia、EB1和APC之间的复合物是否是 并筛选可能有助于MT稳定的其他蛋白质。的 通过确定Par6、动力蛋白和动力蛋白调节MTOC浓度的机制，将探索Par6、动力蛋白和动力蛋白调节MTOC浓度的机制。 6调节动力蛋白和动力肌动蛋白，是否有其他蛋白调节动力蛋白和动力肌动蛋白，以及动力蛋白是否 而dynactin通过皮层MT捕获维持细胞中心的MTOC。了解Rho GTP如何 它们刺激的调节MT的途径将提供关于 细胞在细胞迁移过程中传递信号以控制细胞骨架系统，这是一个重要的过程， 发育、伤口愈合和转移。

The overall goal of this project is to understand how small GTPases of the Rho family regulate the stabilityand organization of microtubules (MTs) during cell polarization. The dynamics of MTs gives them the ability to response to external signals during cell polarization, yet little is known about how these signals are transduced to MTs or the proteins that are involved in MT rearrangements. Cells migration into an hi vitro wound is a model system for studying the signals regulating MT as the contribution of soluble, matrix and cell-associated factors can be dissected. In the previous grant period, we found that the two rearrangements of MTs in wound edge migrating fibroblasts, formation of a subset of unusually stable MTs and reorientation of the MT organizing center (MTOC), are both triggered by serum lysophosphatidic acid (LPA), but are separately regulated by Rho and Cdc42 GTPases. Both of these rearrangements are thought to involve interactions of MT ends with the cell cortex, a process termed MT capture. We identified mDia, EB1, APC, GSK30 and novel PKCs as factors working downstream of Rho and two separate pathways working downstream of Cdc42; one involving Part), dynein and dynactin maintenance of the MTOC at the cell center, the other involving MRCK, actin and myosin II functioning in a novel reward movement of the nucleus. The current aims are to further explore the mechanism of MT stabilization by: exploring how mDia's activity toward MTs and actin is apportioned, by testing whether mDia can directly affect MT stabilization and whether EB1 and APC may affect mDia's activity toward MTs. We will also test whether complexes between mDia, EB1 and APC are regulated by GSK3P and and screen for additional proteins that may contribute to MT stabilization. The mechanism of Par6, dynein and dynactin regulated MTOC centration will be explored by determining how Par 6 regulates dynein and dynactin, whether additional proteins regulate dynein and dynactin and whether dynein and dynactin maintain the MTOC at the cell center by cortical MT capture. Understanding how Rho GTPases and the pathways they stimulate act to regulate MTs will provide new information about the fundamental ways cells transduce signals to control cytoskeletal systems during cell migration, a process of importance for development, wound healing and metastasis.