INTERACTIONS OF NEURAL CAMS WITH EXTRACELLULAR PROTEINS

细胞黏附分子和细胞外基质分子 在神经细胞黏附和迁移中发挥重要作用 组织发生学。这项工作的长期目标是理解 这些蛋白在神经细胞黏附和迁移中的作用 发展。NG-CAM表达于神经元和雪旺细胞，而不表达于 星形星云。特定抗体的扰动实验表明 NG-CAM参与神经元、星形胶质细胞的黏附和迁移 沿着Bergmann Glia。它的功能对神经元-神经元也很重要 粘连、轴突生长和轴突丛生。NG-CAM与NG-CAM结合 神经元上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 与星形胶质细胞相关，包括1D1和3F8硫酸软骨素 蛋白多糖和层粘连蛋白。Thin提案的具体目标是a) 表征Ng-CAM和其他神经钙调素的异亲配体，b)至 鉴定和分析Ng-CAM分子中参与 异亲结合，以及c)分析这些潜在的作用 神经细胞黏附和迁移中的相互作用。它的特殊性 神经凸轮和这些细胞外基质分子之间的相互作用将进一步 使用其他ECM分子进行研究，包括蛋白多糖、层粘连蛋白、 细胞肌动蛋白和纤维连接蛋白。抗ECM配体的特异性抗体 将制备NG-CAM并用于比较它们在组织中的定位 使用Ng-CAM和N-CAM，并使用 培养中的生物合成实验。映射不同的结构和 Ng-CAM分子、蛋白质化学、分子内的功能区 遗传和免疫学技术将被用来识别 与包括1D1和3F8在内的特定配体结合的NG-CAM 蛋白多糖和层粘连蛋白。评估特定人员的潜在角色 Ng-CAM的结构域和异亲配体，蛋白质片段，用于 例如，代表Ng-CAM的定义区域并与某些 配体，以及针对Ng-CAM和ECM蛋白的特异性抗体， 将用于神经元黏附、神经突起生长和 小脑外植体中颗粒细胞的迁移。最新的发现 1D1和3F8蛋白多糖与神经钙调蛋白结合并抑制 神经元黏附增加了细胞表面CaM的可能性 作为蛋白多糖的受体，可能参与信号转导 转导。因此，放射性标记的蛋白多糖与细胞的结合 将被测量，并将测试神经凸轮的参与 针对细胞间黏附分子的特异性抗体；结果可能为 进一步研究细胞“排斥”的分子机制。调查结果 这些研究和相关研究将构成评估 正常状态下神经钙调素与细胞外基质蛋白的相互作用 开发，产生的一些试剂可能在 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.