SYNAPTIC SPECIFICITY IN THE SPINAL CORD

我们研究的长期目标是识别神经 涉及终端组件的形成和维护的具体内容 脊髓内突触连接的模式。我们的基本原则 假设是不同的分子存在于不同的 介导选择性突触前神经末梢的群体 与适当的靶神经元相互作用以稳定和维持 特定的突触联系。我们的调查使用了一种单克隆 用于定位和部分表征新型神经末梢的抗体 一种抗原，称为NT75，具有蛋白质的几种特性 参与选择性突触发育。NT75是一种神经元特异性的， 酸性75 KDa，膜蛋白，在 突触发生过程中神经末梢的特定群体和IS 在成年期维持在神经末梢的亚群中。其他内容 然而，需要研究NT75蛋白，才能认为它是一种 调节选择性突触形成和维持的候选者。一 一系列研究将研究NT75在中国的本地化和调控 发育、再生和成体神经末梢。电子显微镜 将鉴定NT75免疫反应在脊髓神经末梢发育中的作用 蛋白质的出现与突触的特定阶段相关 成熟，并在发育过程中保持NT75水平。在背根中 神经节神经元在体外维持，研究将确定NT75是如何 结合神经突起生长调节，适当接触 与不适当的靶细胞、突触形成和突触活动。 更多的研究将确定NT75是否存在于 运动神经末梢，并将研究NT75在 中枢神经系统中的周围神经再生和流产再生。就地 杂交结合互补免疫细胞化学方法将 也可以用来精确测定脊髓和大脑中的神经元 在成年期表达NT75的基因。另一组研究将提纯NT75， 开发更多针对该蛋白质的抗体，并分析膜 NT75的取向，特别是关于蛋白质是否 暴露在神经末梢膜表面。最后，一个cDNAs 将筛选文库以获得用于原位杂交的探针 NT75的氨基酸序列的研究和未来的分析 蛋白。这些研究的结果预计将具有重大意义 对理解涉及的特定分子机制的启示 脊髓选择性突触连接的形成和维持 脐带和大脑。

The long term objective of our studies is the identification of nerve terminal components involved in the formation and maintenance of specific patterns of synaptic connections in the spinal cord. Our fundamental hypothesis is that distinctive molecules are present in different populations of presynaptic nerve terminals which mediate selective interaction with appropriate target neurons to stabilize and maintain specific synaptic linkages. Our investigations have employed a monoclonal antibody to localize and partially characterize a novel nerve terminal antigen, termed NT75, which has several properties expected of a protein involved in selective synaptic development. NT75 is a neuron-specific, acidic 75KDa, membrane protein which makes a conspicuous appearance in selected populations of nerve terminals during synaptogenesis and is maintained in a subpopulation of nerve terminals in adulthood. Additional study of the NT75 protein is needed, however, before it can be considered a candidate for mediating selective synapse formation and maintenance. One set of studies will examine the localization and regulation of NT75 in developing, regenerating and adult nerve terminals. Electron microscopy will identify NT75 immunoreactivity in developing spinal nerve terminals to correlate the appearance of the protein with specific stages of synaptic maturation and with levels of NT75 during development. In dorsal root ganglion neurons maintained in vitro, studies will determine how NT75 is regulated in conjunction with neurite outgrowth, contact with appropriate vs. inappropriate target cells, synapse formation and synaptic activity. Additional studies will determine whether NT75 is present in developing motor nerve terminals and will examine the regulation of NT75 during peripheral nerve regeneration and abortive regeneration in the CNS. In situ hybridization combined with complementary immunocytochemical methods will also be used to determine precisely those neurons in spinal cord and brain which express NT75 in adulthood. Another set of studies will purify NT75, develop additional antibodies to the protein, and analyze the membrane orientation of NT75, especially with regard to whether the protein is exposed on the surface of the nerve terminal membrane. Finally, a cDNA library will be screened to obtain probes for the in situ hybridization studies and for future analyses of the amino acid sequence of the NT75 protein. The results of these studies are expected to have significant implications for understanding specific molecular mechanisms involved in the formation and maintenance of selective synaptic connections in spinal cord and brain.