Roles of Vascular Endothelial Cells in The Formation of Neural Pathways

在发育过程中神经通路的形成过程中，许多促进神经突生长的粘附分子已被记录在案。外周神经为了到达合适的目标而进行长距离的运动，一些粘附分子参与了它们的寻路过程。我们对未成熟血管内皮细胞在管腔形成前对神经通路形成的作用特别感兴趣。包括纤维连接蛋白和玻璃体连接蛋白在内的几种粘附分子已被报道在这些细胞表面表达，我们假设它们参与内皮细胞上的神经突生长。利用体外系统建立了定量评价背根神经节细胞神经突伸长的方法。加入抗体、合成肽或碳水化合物，测量对神经突伸长的抑制程度。最有效的神经突生长抑制剂是玻璃体连接蛋白抗体，RGD肽，这是众所周知的与整合素结合的粘附序列，以及我们实验室生产的EC1单克隆抗体。EC1抗原的特征分析表明其为硫酸肝素蛋白多糖，分子量在400kd以上。由于肝素酶对碳水化合物链的裂解使其免疫反应性和促进神经突的功能消失，因此硫酸肝素聚糖链对神经突的延伸具有重要作用。我们现在正在对EC1蛋白聚糖的肽结构进行测序。

In the formation of neural pathways during development, a number of adhesion molecules which promote neurite outgrowth have been documented. Peripheral nerves travel long distance in order to reach their appropreate targets, and several adhesion molecules are involved in their pathfinding. We are particularly interested in the roles of the immature vascular endothelial cells before lumen formation for the formation of neural pathways. Several adhesion molecules including fibronectin and vitronectin have been reported to be expressed on the surface of these cells, and we postulated that they are involved in neurite outgrowth over endothelial cells.By the use of in vitro system we have established the method for quantitative evaluation of the neurite elongation of the dorsal root ganglion cells. Adding antibodies, synthetic peptides or carbohydrates, the degree of inhibition of the neurite elongation is measured. The most potent inhibitors of neurite outgrowth are vitronectin antibody, RGD peptides, which is well known to be an adhesion sequence for the binding with integrins, and EC1 monoclonal antibody which was produced in our laboratory.The cahracterization of the EC1 antigen revealed that molecule is heparansulfate proteoglycan with the molecular weigh above 400 kD.As the cleavage of the carbohydrate chain by heparitinase removes the immunoreactivity as well as the neurite promoting function, the heparan sulfate glycan chain has an important role for neurite extension. We are now sequencing the peptide structure of EC1 proteoglycan.