Felsenfeld D P, Hynes M A, Skoler K M, Furley A J, Jessell T M
Howard Hughes Medical Institute, Columbia University, New York, New York 10032.
Neuron. 1994 Mar;12(3):675-90. doi: 10.1016/0896-6273(94)90222-4.
Subsets of axons in the embryonic nervous system transiently express the glycoprotein TAG-1, a member of the subfamily of immunoglobulin (Ig)-like proteins that contain both C2 class Ig and fibronectin type III domains. TAG-1 is attached to the cell surface by a glycosylphosphatidylinositol linkage and is secreted by neurons. In vitro studies have shown that substrate-bound TAG-1 promotes neurite outgrowth. We have examined the nature of axonal receptors that mediate the neurite-outgrowth promoting properties of TAG-1. Although TAG-1 can mediate homophilic binding, neurite outgrowth on a substrate of TAG-1 does not depend on the presence of TAG-1 on the axonal surface. Instead, neurite outgrowth on TAG-1 is inhibited by polyclonal antibodies directed against L1 and, independently, by polyclonal and monoclonal antibodies against beta 1-containing integrins. These results provide evidence that TAG-1 can interact with cell surfaces in both a homophilic and heterophilic manner and suggest that neurite extension on TAG-1 requires the function of both integrins and an L1-like molecule.
胚胎神经系统中的轴突亚群会短暂表达糖蛋白TAG-1，它是免疫球蛋白（Ig）样蛋白亚家族的成员，包含C2类Ig和纤连蛋白III型结构域。TAG-1通过糖基磷脂酰肌醇连接附着在细胞表面，并由神经元分泌。体外研究表明，底物结合的TAG-1可促进神经突生长。我们研究了介导TAG-1促进神经突生长特性的轴突受体的性质。尽管TAG-1可以介导同源性结合，但在TAG-1底物上的神经突生长并不依赖于轴突表面TAG-1的存在。相反，针对L1的多克隆抗体以及独立地针对含β1整合素的多克隆和单克隆抗体均可抑制TAG-1上的神经突生长。这些结果提供了证据，表明TAG-1可以以同源和异源方式与细胞表面相互作用，并表明TAG-1上的神经突延伸需要整合素和L1样分子的功能。
