Stitt T N, Gasser U E, Hatten M E
Center for Neurobiology and Behavior, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
Ann N Y Acad Sci. 1991;633:113-21. doi: 10.1111/j.1749-6632.1991.tb15602.x.
The migration of young neurons from their site of origin in proliferative zones out into neuronal layers is a hallmark of cortical development. Neuroanatomic studies show that astroglial fibers provide the primary substrate for neuronal migration. In vitro studies on living cells provide evidence that migrating neurons express distinguishing cytologic features including the formation of a specialized junction at the site of neuron-glia contact and the extension of an active leading process in the direction of migration. Our in vitro functional assays point to a critical role for astrotactin in neuron-glia binding during the developmental periods of glial-guided cell migration and assembly in brain. Other receptor systems, including neural cell adhesion systems, cadherins, and integrins are expressed by granule cells but do not appear to contribute to neuron-glia binding or to glial-guided neuronal migration. A role for astrotactin in glial-guided migration and assembly is supported by our observation that astrotactin is expressed by neurons and not glial cells and by restricted spatiotemporal expression of astrotactin in vivo, wherein astrotactin is expressed by migrating neurons and by neurons during periods of assembly into neuronal layers in developing brain. Understanding the regulation of astrotactin expression and its role in migration will provide fundamental insights into the role of glial-guided migration in the histogenesis of the brain.
年轻神经元从增殖区的起源部位迁移到神经层是皮质发育的一个标志。神经解剖学研究表明，星形胶质纤维为神经元迁移提供了主要基质。对活细胞的体外研究提供了证据，即迁移的神经元表现出独特的细胞学特征，包括在神经元与胶质细胞接触部位形成特殊连接以及在迁移方向上延伸活跃的引导突起。我们的体外功能测定表明，在脑内胶质细胞引导的细胞迁移和组装的发育阶段，astrotactin在神经元与胶质细胞结合中起关键作用。其他受体系统，包括神经细胞黏附系统、钙黏蛋白和整合素，由颗粒细胞表达，但似乎对神经元与胶质细胞的结合或胶质细胞引导的神经元迁移没有贡献。我们观察到astrotactin由神经元而非胶质细胞表达，以及其在体内的时空表达受限，即在发育中的脑内，astrotactin由迁移的神经元以及在组装到神经层阶段的神经元表达，这支持了astrotactin在胶质细胞引导的迁移和组装中的作用。了解astrotactin表达的调控及其在迁移中的作用将为胶质细胞引导的迁移在脑的组织发生中的作用提供基本见解。
