Cortactin in Cell Motility and Invasion

描述：本研究项目的重点是了解F-肌动蛋白结合蛋白Cortactin如何在细胞运动和肿瘤细胞侵袭中发挥作用。这项拟议研究的长期目标集中在皮质肌动蛋白及其相关蛋白在片状脂溢症中与信号转导和运动有关的作用，以及皮质肌动蛋白过表达如何影响细胞运动、黏附和肿瘤细胞侵袭性。本申请专门介绍了皮质肌动蛋白在基于Arp2/3-F-肌动蛋白的皮质细胞骨架组织中的功能，以及皮质肌动蛋白如何调节正常和肿瘤细胞的运动。Cortactin是包括Src在内的多种酪氨酸激酶的底物，在30%的头颈部鳞状细胞癌(HNSCC)中过表达。根据初步数据推测，皮质肌动蛋白通过酪氨酸磷酸化以及Arp2/3-F-肌动蛋白网络的激活和保护来动态调节皮质肌动蛋白细胞骨架。本文将通过对成纤维细胞和HNSCC细胞系的生化和细胞生物学分析，探讨Cortactin在细胞迁移过程中调节和稳定皮质Arp2/3-F-actin网络的作用，以及由于Cortactin过度表达而产生的Arp2/3-F-actin网络的动态调节增强导致HNSCC侵袭性增加的假设。在目标1中，我们将研究皮质肌动蛋白酪氨酸磷酸化是否影响Arp2/3肌动蛋白的核活性及其与Arp2/3-F-肌动蛋白网络的关系，如果皮质肌动蛋白酪氨酸磷酸化影响板脂蛋白动力学，并确定皮质肌动蛋白是否保护Arp2/3-F-肌动蛋白网络不被ADF/cofilin蛋白分解。目的2将检查RNAi产生的皮质肌动蛋白表达降低或消除的细胞，以确定皮质肌动蛋白如何影响皮质肌动蛋白细胞骨架、细胞迁移和黏附。目的3通过检测在高表达Cortactin的HNSCC细胞系中Arp2/3复合体的结合和激活是否增强，以及在HNSCC中高表达Cortactin是否导致细胞侵袭和细胞外基质蛋白分解增加，来研究Cortactin过表达如何影响HNSCC的侵袭性。这些拟议目标的完成将使我们更好地了解Cortactin在细胞迁移和肿瘤细胞侵袭/转移中的作用。

DESCRIPTION: The focus of this research project is to understand how cortactin, an F-actin-binding protein, functions in cell motility and tumor cell invasion. The long-term goal of the proposed research centers on the role of cortactin and associated proteins in lamellipodia function as it pertains to signal transduction and motility, and how cortactin overexpression influences cell motility, adhesion and tumor cell invasiveness. This application specifically addresses the function of cortactin in the organization of the Arp2/3-F-actin based cortical cytoskeleton and how cortactin serves to regulate normal and tumor cell movement. Cortactin is a substrate for multiple tyrosine kinases, including Src, and is over expressed in 30% of head and neck squamous cell carcinomas (HNSCCs). Based on preliminary data, it is posited that cortactin dynamically regulates the cortical actin cytoskeleton by a mechanism that involves tyrosine phosphorylation along with activation and protection of Arp2/3-F-actin networks. The studies described here will use biochemical and cell biological analysis of fibroblast and HNSCC cell lines to explore the hypothesis that cortactin functions to regulate and stabilize cortical Arp2/3-F-actin networks during cell migration, and that enhanced dynamic regulation of Arp2/3-F-actin networks resultant from cortactin overexpression leads to increased invasion of HNSCC. In Aim 1, we will address if cortactin tyrosine phosphorylation affects Arp2/3 actin nucleation activity and its association with Arp2/3-F-actin networks, if cortactin tyrosine phosphorylation influences lamellipodia dynamics, and determine if cortactin protects Arp2/3-F-actin networks from disassembly by ADF/cofilin proteins. Aim 2 will examine cells with reduced or eliminated cortactin expression derived by RNAi to determine how cortactin impacts the cortical actin cytoskeleton, cell migration and adhesion. Aim 3 will examine how cortactin overexpression affects the invasive properties of HNSCC by determining if Arp2/3 complex association and activation are enhanced in HNSCC cell lines overexpressing cortactin, and to determine if cell invasion and extracellular matrix proteolysis is increased as a result of cortactin overexpression in HNSCC. Completion of the proposed Aims will provide a better understanding of how cortactin functions in cell migration and tumor cell invasion/metastasis.