SYNAPTIC SPECIFICITY IN THE SPINAL CORD

我们研究的长期目标是识别神经 参与形成和维持特定的 脊髓中突触连接的模式。我们的根本 一种假说认为，不同的分子存在于不同的 突触前神经末梢的群体，其介导选择性 与适当的靶神经元相互作用以稳定和维持 特殊的突触连接我们的研究使用了一种 用于定位和部分表征新型神经末梢的抗体 抗原，称为NT 75，它具有蛋白质的几种预期特性 参与选择性突触发育。NT75是神经元特异性的， 酸性75KDa的膜蛋白，其在细胞膜中的显著外观， 选择群体的神经末梢在突触和 维持在成年期的神经末梢亚群中。额外 然而，在NT75蛋白被认为是一种 候选人介导选择性突触的形成和维护。一 一组研究将检查NT75的本地化和监管， 发育、再生和成熟的神经末梢。电子显微镜 将鉴定NT75在发育中的脊神经末梢中的免疫反应性， 将蛋白质的出现与突触的特定阶段相关联， 在发育过程中与NT75的水平。背根 神经节神经元维持在体外，研究将确定NT75是如何在神经元中发挥作用的。 调节与神经突生长，接触适当的 vs.不适当的靶细胞、突触形成和突触活性。 进一步的研究将确定NT75是否存在于发展中国家， 运动神经末梢，并将检查NT75的调节过程中 周围神经再生和中枢神经系统再生失败。原位 杂交结合互补免疫细胞化学方法将 也可用于精确测定脊髓和大脑中的神经元 在成年期表达NT75。另一组研究将纯化NT 75， 开发针对蛋白质的额外抗体，并分析膜 NT75的方向，特别是关于蛋白质是否是 暴露在神经末梢膜的表面。最后，一个cDNA 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。 对理解参与的特定分子机制的影响 脊髓选择性突触连接的形成和维持 脊髓和大脑

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.