Coordinated Actin Regulation in Directed Neural Crest Cell Migration

项目摘要 细胞迁移对发育和疾病至关重要，但我们对这种复杂动态的理解 事件相当有限。细胞培养研究已经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，Rac 1和Cdc 42），影响细胞迁移的特定过程。然而，在这方面， 这些调节剂的体内活性以及它们如何协调以促进有效的细胞迁移， 详细了解。长期的目标是了解分子机制，协调定向 细胞迁移为了实现这一目标，本提案的总体目标是确定Cdc 42 ep 1， Cdc 42的效应蛋白与其他肌动蛋白调节因子相互作用以协调神经嵴细胞迁移。最近 来自实验室的研究表明，Cdc 42 ep 1在非洲爪蟾的神经嵴细胞定向迁移中是必不可少的。 胚胎发生使用这种体内细胞迁移系统，揭示了Cdc 42 ep 1的两个亚细胞池，一个是 一个在电池的前部，另一个在电池的主体和后部。这两个Cdc 42 ep 1库与Cdc 42相互作用 和隔蛋白丝，这些相互作用可以影响Cdc 42 ep 1之间的平衡， 两个细胞质池。因此，该提议的中心假设是Cdc 42 ep 1与Cdc 42- 介导的膜突起在前缘和septin-actin细胞骨架组织在尾部 边缘，以促进定向神经嵴细胞迁移。中心假设将通过以下方式进行检验： 具体目标如下：1）确定Cdc 42和Cdc 42 ep 1之间的反馈调节及其影响 极化肌动蛋白动力学和定向神经嵴细胞迁移; 2）确定 Cdc 42 ep 1与septin丝在调控细胞极性和神经元定向迁移中的协同作用 3）探讨隔蛋白丝在调节嵴细胞形成和分化中的作用和机制。 肌动蛋白应力纤维的收缩性。这项工作是与Tsygankov实验室的密切合作，在那里， 细胞迁移模型将被开发以测试各种分子机制并指导进一步的实验 的设计.通过以定量方式紧密整合体内和计算机实验， 研究将揭示Cdc 42 ep 1如何整合Cdc 42和septin的活动， 肌动蛋白动力学在膨胀的前部和缩回的后部，以促进神经嵴细胞迁移。本研究 将填补知识空白的地方细胞骨架安排是如何协调定向细胞迁移。这 知识不限于神经嵴迁移，而是可以应用于其他迁移过程，以提供 对体内细胞迁移的一般机制的理解。因此，这项研究不仅对以下方面至关重要： 了解神经嵴发育相关的出生缺陷，也有助于提高我们对 许多人类疾病涉及在其他情况下失调的细胞迁移。

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.