Signaling mechanisms activated by engagement of NGE-PG

NG 2蛋白聚糖有助于细胞在VI型胶原包被的表面上的扩散和迁移。蛋白聚糖的胞质结构域是NG 2依赖的扩散和迁移的组成部分所需的，这表明该结构域参与了影响细胞骨架机制重排的信号转导。在用抗NG 2单克隆抗体包被的表面上的细胞铺展现在被用于研究当NG 2被基质接合时激活的特异性信号传导机制。本申请提出了旨在鉴定NG 2介导的信号传导机制并定义这些过程对细胞行为的影响的实验。具体目标1侧重于鉴定细胞铺展所需的NG 2胞质结构域的结构元件。这些将通过使用携带关键决定簇缺失和突变的NG 2 cDNA转染的细胞来定义。特异性目标2探测NG 2在激活rho家族GTP酶（rho、rac和cdc 42）中的作用，所述GTP酶是控制肌动蛋白细胞骨架重排的分子。具体目标3检查SH 3结构域。这些分子可能提供NG 2和细胞内信号通路之间的联系。具体目标4研究了NG 2的C末端PDZ结合与含有PDZ结构域的细胞质分子的相互作用。含有PDZ结构域的分子如MUPPI、FAP-1和rhophilin可以提供与信号传导途径的额外联系，以及作为NG 2物理定位于关键细胞微结构域的支架。

The NG2 proteoglycan contributes to cell spreading and migration on surfaces coated with type VI collagen. The cytoplasmic domain of the proteoglycan is required for the NG2-dependent component of spreading and migration, suggesting that this domain is involved in transducing signals that influence rearrangements of cytoskeletal machinery. Cell spreading on surface coated with anti-NG2 monoclonal antibodies is now being used to study specific signaling mechanisms activated upon engaged of NG2 by the substratum. This application proposes experiments designed to identify signaling mechanisms mediated by NG2 and to define the impact of these processes on cell behavior. Specific aim 1 focuses on identifying structural elements of the NG2 cytoplasmic domain that are required for cell spreading. These will be defined by using cells transfected with NG2 cDNAs carrying deletions and mutations in key determinants. Specific aim 2 probes the role of NG2 in activating rho family GTPases (rho, rac, and cdc42), molecules that control rearrangements of the actin cytoskeleton. Specific aim 3 examines the SH3 domains. These molecules may provide the link between NG2 and intracellular signaling pathways. Specific aim 4 investigates the interaction of the C-terminal PDZ-binding of NG2 with cytoplasmic molecules that contain PDZ domains. PDZ domain-containing molecules such as MUPPI, FAP-1 and rhophilin may provide additional links to signaling pathways, as well as serving as scaffolds for the physical localization of NG2 to critical cellular microdomains.