Coordinated Actin Regulation in Directed Neural Crest Cell Migration

项目总结 细胞迁移是发育和疾病的关键，但我们对这一复杂动态的理解 活动相当有限。细胞培养研究发现了肌动蛋白细胞骨架的关键调节因子，包括 Rho家族的GTP酶(RhoA、rac1和CDC42)，影响特定的细胞迁移过程。然而， 这些调节因子的体内活动以及它们如何协调以促进有效的细胞迁移并不是 理解得很详细。长期的目标是理解协调定向的分子机制。 细胞迁移。为了实现这一目标，本提案的总体目标是确定CDC42ep1、 CDC42的效应蛋白与其他肌动蛋白调节蛋白相互作用以协调神经脊细胞的迁移。近期 实验室的研究表明，在非洲爪哇期间，cdc42ep1在神经脊细胞的定向迁移中是必不可少的。 胚胎发生。利用该体内细胞迁移系统，发现了两个cdc42ep1亚细胞池 在突出的前部，另一个在细胞体和后部。这两个cdc42ep1池与cdc42相互作用 和Septin细丝，这些相互作用可以影响CDC42ep1在 两个细胞质池。因此，这一提议的中心假设是，CDC42ep1坐标为CDC42- 前缘介导的膜突起和后缘的Septin-肌动蛋白细胞骨架组织 边缘，以促进定向神经脊细胞迁移。核心假说将通过追求 以下三个具体目标：1)确定CDC42和CDC42ep1之间的反馈调节及其影响 极化肌动蛋白动力学与神经脊细胞定向迁移的研究2)确定了肌动蛋白极化的机制 CDC42ep1和Septin细丝在控制细胞极性和神经元定向迁移中的协同作用 以及3)确定隔膜细丝在调节细胞的形成和发育中的作用和机制。 肌动蛋白应激纤维的收缩性能。这项工作是与齐甘科夫实验室的密切合作，其中一个地貌动力学 将开发细胞迁移模型来测试各种分子机制，并指导进一步的实验 设计。通过以定量的方式将体内实验和计算机实验紧密结合，建议的 研究将揭示CDC42ep1如何整合CDC42和Septin的活动来组织的机制 前部和后部的肌动蛋白动态变化促进神经脊细胞迁移。本研究 将填补在定向细胞迁移中如何协调局部细胞骨架排列的知识空白。这 知识并不局限于神经脊迁移，而是可以应用于其他迁移过程，以提供 一般情况下，对体内细胞迁移的机械理解。因此，这项研究不仅对 了解神经脊相关出生缺陷的发生发展，也有助于提高我们对 许多人类疾病，涉及在其他情况下细胞迁移的失调。

PROJECT SUMMARY Cell migration is critical to development and disease, and yet yet our understanding for this complex dynamic event is rather limited. Cell culture studies have uncovered crucial regulators of actin cytoskeleton, including the Rho family of GTPases (RhoA, Rac1, and Cdc42), that influence particular processes of cell migration. However, in vivo activities of these regulators and how they coordinate to promote efficient cell migration are not understood in detail. The long-term goal is to understand the molecular mechanisms that coordinate directed cell migration. To achieve this goal, the overall objective of this proposal is to determine how Cdc42ep1, an effector protein for Cdc42, interacts with other actin regulators to coordinate neural crest cell migration. Recent study from the lab revealed that Cdc42ep1 is essential in directed migration of neural crest cells during Xenopus embryogenesis. Using this in vivo cell migration system, two subcellular pools of Cdc42ep1 were revealed, one at the protrusive front and the other at the cell body and rear. These two pools of Cdc42ep1 interacts with Cdc42 and septin filaments, respectively, and these interactions can influence the balance of Cdc42ep1 between the two cytoplasmic pools. Therefore, the central hypothesis for this proposal is that Cdc42ep1 coordinates Cdc42- mediated membrane protrusion at the leading edge and the septin-actin cytoskeleton organization at the trailing edge to promote directed neural crest cell migration. The central hypothesis will be tested by pursuing the following three specific aims: 1) Determine the feedback regulation between Cdc42 and Cdc42ep1 and its impact on polarized actin dynamics and directed neural crest cell migration; 2) Determine the mechanisms of cooperation between Cdc42ep1 and septin filaments in controlling cell polarity and directional migration of neural crest cells; and 3) Determine the function and mechanism of septin filaments in regulating the formation and contractility of actin stress fibers. This work is a close collaboration with Tsygankov lab, where a morphodynamic cell migration model will be developed to test various molecular mechanisms and guide further experimental designs. By tightly integrating the in vivo and in silico experiments in a quantitative manner, the proposed research will uncover the mechanisms of how Cdc42ep1 integrates activities of Cdc42 and septin to organize actin dynamics at the protrusive front and the retractive rear to promote neural crest cell migration. This study will fill the knowledge gap of how local cytoskeletal arrangements are coordinated in directed cell migration. This knowledge is not limited to neural crest migration, but can be applied to other migration processes to provide a mechanistic understanding of in vivo cell migration in general. Therefore, the study will not only be critical for understanding the development of neural crest related birth defects, but also help improve our understanding of numerous human diseases that involve dysregulated cell migration in other contexts.