Regulation of Cell Migration by the APC-Microtubule Complex

细胞向细胞外信号的定向迁移对于正常组织形态发生是必需的， 修复和异常的调节途径导致严重的病理后果 在肿瘤转移过程中。该建议的重点是腺瘤性结肠息肉病（ARC）的作用， 蛋白质复合物在调节微管和肌动蛋白细胞骨架响应细胞外信号， 刺激细胞迁移和粘附。APC最初被发现是一种肿瘤抑制蛋白， 控制着β-连环蛋白的水平APC是一种大的支架蛋白，具有许多结合伴侣， 调节微管和定向细胞迁移响应细胞外信号。虽然 APC在不同形态学过程中的重要性已经得到了很好的证实，但关于APC如何作用却知之甚少。 细胞外信号影响其与细胞骨架结合伴侣的相互作用和微管的调节 动力学，或APC支架复合物如何影响膜动力学和细胞迁移 我们的假设是，APC通过充当微管骨架来协调微管和肌动蛋白的重组。 细胞骨架调节因子，以及直接响应APC支架的细胞外信号传导组分 被局部募集并激活以指定定向膜延伸。我们提出了一个严格的 APC调节和功能的生化分析结合新的测定以重构APC， 微管动力学在体外和图像与高时空分辨率APC微管动力学在体外 细胞我们建议：1）。定义参与细胞外信号诱导的APC修饰的机制 多蛋白复合物的组成和功能; 2）. APC多蛋白的分解与重组作用 复合组分对微管动力学和F-肌动蛋白结合的体外影响;和3）.描述APC- 介导的微管和F-actin动力学响应细胞外信号的局部变化。 这些研究的意义在于，它们将定义APC中的蛋白质-蛋白质相互作用 在细胞伸展和接触形成期间局部调节细胞骨架重组的复合物，以及 这种复合物的功能如何受到发育和疾病中重要的信号通路的调节。

Directional cell migration towards extracellular signals is essential for normal tissue morphogenesis and repair, and abnormalities in the regulatory pathways involved result in severe pathological consequences during tumor metastasis. This proposal focuses on the role of the adenomatous polyposis coli (ARC) multi- protein complex in regulating microtubule and actin cytoskeletons in response to extracellular signals that stimulate cell migration and adhesion. APC was originally discovered as a tumor suppressor protein that controls the level of beta-catenin. APC is a large scaffolding protein with many binding partners that also regulates microtubules and directional cell migration in response to extracellular signals. Although the importance of APC in diverse morphological processes is well established, very little is known about how extracellular signals affect its interaction with cytoskeletal binding partners and regulation of microtubule dynamics, or how the APC scaffolding complex influences membrane dynamics and cell migration Our hypothesis is that APC coordinates microtubule and actin reorganization by acting as scaffold for cytoskeletal regulators, and that in direct response to extracellular signaling components of the APC scaffold are locally recruited and activated to specify directional membrane extension. We propose a rigorous biochemical analysis of APC regulation and functions combined with novel assays to reconstitute APC- microtubule dynamics in vitro and to image with high spatiotemporal resolution APC-microtubule dynamics in cells. We propose to: 1). Define mechanisms involved in extracellular signal-induced modifications of APC multi-protein complex composition and functions; 2). Dissect and reconstitute effects of APC multi-protein complex components on microtubule dynamics and F-actin binding in vitro; and 3). Characterize APC- mediated localized changes in microtubule and F-actin dynamics in response to extracellular signals. The significance of these proposed studies is that they will define protein-protein interactions in the APC complex that locally regulate cytoskeleton reorganization during cell extension and contact formation, and how the function of this complex is regulated by signaling pathways important in development and disease.