INTERACTIONS OF NEURAL CAMS WITH EXTRACELLULAR PROTEINS

细胞粘附分子（CAM）和细胞外基质（ECM）分子 在神经细胞的粘附和迁移中起重要作用， 组织发生这项工作的长期目标是了解 这些蛋白在神经细胞粘附和迁移过程中的作用 发展Ng-CAM在神经元和雪旺细胞上表达，但在 星形胶质细胞。用特异性抗体进行的扰动实验表明， Ng-CAM参与神经元、星形胶质细胞的粘附和迁移 沿着Bergmann胶质细胞。它的功能对神经元-神经元也很重要 粘附、轴突生长和轴突成束。Ng-CAM与Ng-CAM结合 和星形胶质细胞上的不同配体（异嗜性结合）。 最近的研究表明，Ng-CAM与ECM分子相互作用， 包括1D 1和3F 8硫酸软骨素 蛋白聚糖和层粘连蛋白。本提案的具体目标是： 表征Ng-CAM和其它神经CAM的异嗜性配体，B）以 鉴定和分析Ng-CAM分子的区域， 异嗜性结合，和c）分析这些的潜在作用 神经细胞粘附和迁移的相互作用。的特异性 神经CAMs和这些ECM分子之间的相互作用将进一步 使用其他ECM分子包括蛋白聚糖，层粘连蛋白， 胞浆素和纤连蛋白。针对ECM配体的特异性抗体， 将制备Ng-CAM并用于比较其在组织中的定位 与Ng-CAM和N-CAM，并确定其细胞来源，使用 在培养物中进行生物合成实验。绘制不同的结构和 Ng-CAM分子内的功能区域、蛋白质化学、分子 遗传学和免疫学技术将用于识别 Ng-CAM结合特异性配体，包括1D 1和3F 8 蛋白聚糖和层粘连蛋白。评估特定的潜在作用 Ng-CAM的结构域和异嗜性配体，蛋白质片段， 例如，其代表Ng-CAM的限定区域并结合某些 配体，以及针对Ng-CAM和ECM蛋白的特异性抗体， 将用于神经元粘附、神经突生长和 颗粒细胞在小脑外植体中的迁移。最近发现 1D 1和3F 8蛋白聚糖与神经CAM结合， 神经元粘附增加了细胞表面的CAM 作为蛋白聚糖的受体起作用， 转导因此，放射性标记的蛋白聚糖与细胞的结合 将被测量，神经CAM的参与将被测试， 针对CAM的特异性抗体;结果可能为 进一步研究细胞排斥的分子机制。“调查结果表明， 这些研究和相关研究将成为评估 神经细胞间粘附分子和细胞外基质蛋白之间的相互作用 开发，产生的一些试剂可能是有用的， 改善神经元再生的治疗方案。

Cell adhesion molecules (CAMs) and extracellular matrix (ECM) molecules play important roles in cell adhesion and migration during neural histogenesis. The long-term objective of this work is to understand the roles of these proteins in adhesion and migration of neural cells during development. Ng-CAM is expressed on neurons and Schwann cells but not on astroglia. Perturbation experiments with specific antibodies indicate that Ng-CAM is involved in neuron.astroglia adhesion and migration of neurons along Bergmann glia. Its function is also important for neuron-neuron adhesion, axonal growth, and axonal fasciculation. Ng-CAM binds to Ng-CAM on neurons and to distinct ligands on astroglia (heterophilic binding). Recent studies indicate that Ng-CAM interacts with ECM molecules that are associated with astroglia including the 1D1 and 3F8 chondroitin sulfate proteoglycans and laminin. The specific aims of thiN proposal are a) to characterize heterophilic ligands for Ng-CAM and other neural CAMs, b) to identify and analyze regions of the Ng-CAM molecule that are involved in heterophilic binding, and c) to analyze the potential roles of these interactions in adhesion and migration of neural cells. The specificity of interactions between neural CAMs and these ECM molecules will be further investigated using other ECM molecules including proteoglycans, laminin, cytotactin, and fibronectin. Specific antibodies against ECM ligands for Ng-CAM will be prepared and used to compare their localization in tissues with Ng-CAM and N-CAM, and to determine their cellular origin using biosynthesis experiments in culture. To map different structural and functional regions within the Ng-CAM molecule, protein chemical, molecular genetic, and immunological techniques will be used to identify domains in Ng-CAM that bind to specific ligands including the 1D1 and 3F8 proteoglycans, and laminin. To evaluate potential roles of specific domains of Ng-CAM and the heterophilic ligands, protein fragments, for example, that represent defined regions of Ng-CAM and bind to certain ligands, as well as specific antibodies against Ng-CAM and ECM proteins, will be used in assays for neuronal adhesion, neurite growth, and migration of granule cells in cerebellar explants. The recent discovery that the 1D1 and 3F8 proteoglycans bind to neural CAMs and inhibit neuronal adhesion raises the possibility that CAMs on the cell surface function as receptors for proteoglycans and may be involved in signal transduction. Therefore, binding of radiolabeled proteoglycans to cells will be measured and the involvement of neural CAMs will be tested using specific antibodies against the CAMs; the results may provide clues for further studies of molecular mechanisms of cell "repulsion." The findings of these and related studies will form a basis for evaluating the role of interactions between neural CAMs and ECM proteins during normal development, and some of the reagents generated may be useful in therapeutic protocols to improve neuronal regeneration.