Spatial Regulation of Cytoskeleton During Chemotaxis

描述(申请人提供)：许多真核细胞经历趋化，定向移动到一个可溶的配体。这一过程是许多生物学功能所必需的，包括伤口愈合、轴突引导和网状茎基细胞的聚集。趋化性在关节炎、癌症和多发性硬化症等疾病状态中也发挥着作用。细胞的定向运动需要一个明确的细胞极性，其中细胞骨架的成分差异化地定位在迁移细胞的前缘及其后部。这种极化可以通过异源三聚体G蛋白偶联的膜结合受体的化学吸引结合，以及随后激活下游信号转导通路直接重组肌动蛋白和肌球蛋白细胞骨架来启动。我们以前的研究表明，极化的肌动蛋白细胞骨架是通过将肌动蛋白组装的调节因子如WASP和WIP集中在细胞皮质的亚域中而实现的。本研究的目的是了解WASP的亚细胞定位和激活在趋化过程中是如何调节的。我们推测，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，导致在Dictyostelial趋化性过程中，通过肌动蛋白细胞骨架的极化组织和ACA的不对称分布来建立细胞极性。为了验证这一假设，我们提出了以下具体目标：1)阐明PCH家族蛋白、CLP1/2和rACC在囊泡形成过程中控制WASP功能和定位的作用。2)研究CLP1/2、rACC和Unc104在WASP-囊泡和ACA-囊泡运输中的作用。3)研究WASP-囊泡和ACA-囊泡的极化转运在趋化过程中对细胞极性的影响。预计这些研究不仅将为如何控制高尔基体胞外囊泡的形成提供新的见解，而且还将有助于理解在趋化过程中如何通过囊泡运输来实现细胞极性。 公共卫生相关性：我们体内的许多细胞经历趋化性，定向移动到一种化合物，这是许多生物学功能所必需的，包括伤口愈合和神经系统的发育。趋化性在关节炎、癌症和多发性硬化症等疾病状态中也发挥着作用。我们提出的研究将帮助我们理解细胞如何维持细胞极性，以及当细胞朝着方向线索定向迁移时如何定向细胞运动。

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.