Spatial Regulation of Cytoskeleton During Chemotaxis

描述（由申请人提供）：许多真核细胞进行趋化，直接向可溶性配体移动。这一过程对许多生物学功能都是必需的，包括伤口愈合、轴突引导和盘基骨柱细胞的聚集。趋化性也在关节炎、癌症和多发性硬化症等疾病状态中发挥作用。定向细胞运动需要明确的细胞极性，其中细胞骨架的组成部分不同地定位于迁移细胞的前缘及其后撤。这种极化可以由异三聚体G蛋白偶联膜结合受体的趋化剂结合引发，随后下游信号转导途径的激活直接导致肌动蛋白和肌球蛋白细胞骨架的重组。我们之前的研究表明，通过将肌动蛋白组装的调节因子（如WASP和WIP）集中在细胞皮层的亚结构域，可以实现极化肌动蛋白细胞骨架。本研究的目的是了解在趋化过程中如何调节WASP的亚细胞定位和激活。我们假设PCH家族蛋白、CLP1/2和RacC之间的复杂相互作用导致WASP和ACA的极化运输，从而通过肌动蛋白细胞骨架的极化组织和ACA在盘形骨趋化过程中的不对称分布导致细胞极性的建立。为了验证这一假设，我们提出以下具体目标：1)阐明PCH家族蛋白、CLP1/2和RacC在小泡形成过程中调控WASP功能和定位的作用。2)探讨CLP1/2、RacC和Unc104在WASP-和aca -囊泡转运中的作用。3)研究WASP-和aca -囊泡的极化运输在趋化过程中如何促进细胞极性的建立。预计这些研究不仅将为如何控制高尔基胞外泡形成提供新的见解，而且还将了解在趋化过程中如何通过囊泡运输来实现细胞极性。

DESCRIPTION (provided by applicant): Many eukaryotic cells undergo chemotaxis, directed movement towards a soluble ligand. This process is necessary for many biological functions, including wound healing, axonal guidance, and the aggregation of Dictyostelium cells. Chemotaxis also plays a role in disease states such as arthritis, cancer, and multiple sclerosis. Directional cell movement requires a defined cell polarity in which components of the cytoskeleton are differentially localized at the leading edge of a migrating cell as well as its retracting posterior. This polarization can be initiated by the chemoattractant binding of heterotrimeric G protein-coupled membrane- bound receptors, and subsequent activation of downstream signal transduction pathways direct reorganization of the actin and myosin cytoskeleton. Our previous studies suggested that a polarized actin cytoskeleton is achieved by concentrating regulators of actin assembly such as WASP and WIP in subdomains at the cell cortex. The goal of this study is to understand how the subcellular localization and activation of WASP is regulated during chemotaxis. We hypothesize that a complex interplay between PCH family proteins, CLP1/2, and RacC leads to polarized trafficking of WASP and ACA, resulting in cell polarity establishment via the polarized organization of actin cytoskeleton and asymmetric distribution of ACA during Dictyostelium chemotaxis. To test this hypothesis, we propose the following specific aims: 1) To elucidate the role of PCH family proteins, CLP1/2 and RacC in controlling function and localization of WASP during vesicle formation. 2) To investigate roles of CLP1/2, RacC, and Unc104 in the trafficking of WASP- and ACA-vesicles. 3) To study how polarized trafficking of WASP- and ACA-vesicles contribute to establish cell polarity during chemotaxis. It is anticipated that these studies will serve not only to provide new insights on how exocytic vesicle formation from Golgi is controlled, but also to understand how cellular polarity can be achieved b vesicle trafficking during chemotaxis. PUBLIC HEALTH RELEVANCE: Many cells in our body undergo chemotaxis, directed movement toward a chemical compound which is necessary for many biological functions including wound healing and the development of the nervous system. Chemotaxis also plays a role in disease states such as arthritis, cancer, and multiple sclerosis. Our proposed research would help us understand how cells maintain cell polarity and directed cell movement when they migrate directionally toward a directional cue.