MICROTUBULE-ASSOCIATED COUPLERS AND AXONAL TRANSPORT

已知轴突运输系统在维持 轴突的结构和功能的完整性。有缺陷的轴突运输 系统可能与某些神经退行性变的病因有关 与暴露于神经毒性有关的疾病和周围神经病 化学制品。尽管许多关于轴突运输的信息 成分(特别是蛋白质)是用放射性物质获得的。 示踪技术，结构和分子基础轴突运输 仍然难以捉摸。 最近，我们报道了一种与微管(MT)相关的 轴突中的“耦合器”。这种结构将MTS与其他细胞骨架连接起来 以及各种膜结合细胞器(MBO) 并重新分布，以便与治疗后轴突中的MTS保持联系 B，B‘-亚氨基二丙腈(IDPN)。这些发现以及 先前的研究表明，成色剂参与了 轴突快速运输的动力。该计划的主要目标 建议的研究是为了加深我们对(1)结构的理解， 轴突内成色剂的组成和功能及(2) 神经生长和轴突过程中细胞骨架元件的偶联剂 运输。计划采取以下主要办法：(1)更加迅速和 改进的固定方法将用于揭示 参与轴突运输。(2)MTS与神经丝的分离 B，B“-亚氨基二丙腈诱导体系将作为模型体系 研究MTS、NFS和偶联剂在神经生长和修复中的单独作用 轴突运输。(3)相关时间推移电影显微技术和电子技术 显微镜将被用来直接联系神经生长的变化。 随着车钩的数量和分布的变化而变化的速率 轴突细胞骨架的组织状态。(4)免疫细胞化学 将使用技术来检查成色剂的组成。 这些研究将有助于阐明神经的结构和分子基础。 生长和轴突运输，这反过来将揭示新的曙光 与某些神经毒性和神经毒性相关的轴突病变的潜在原因 神经退行性疾病，可能至少部分是由于 轴突运输系统有缺陷。

The axonal transport system is known to play a key role in maintaining the structural and functional integrity of axons. A defective axonal transport system may contribute to the etiology of certain nerve degenerative diseases and peripheral neuropathies associated with exposure to neurotoxic chemicals. Although much information on the transport of axonal constituents (especially proteins) has been obtained using radioactive tracer techniques, the structural and molecular bases axonal transport remain elusive. Recently, we reported the discovery of a microtubule (MT)-associated "coupler" in axons. This structure links MTs to other cytoskeletal components as well as to various types of membrane-bound organelles (MBOs) and redistributes so as to remain associated with MTs in axons treated with B,B'-iminodipropionitrile (IDPN). These findings along with those of previous studies suggest that couplers are involved in the generation of motive forces for fast axonal transport. The main objectives of the proposed study are to further our understanding of (1) the structure, composition and function of couplers in axons and (2) the relationship of couplers to cytoskeletal elements during nerve growth and axonal transport. The following major approaches are planned: (1) More rapid and improved fixation methods will be used to reveal structures that participate in axonal transport. (2) Segregation of MTs and neurofilaments induced with B,B"-iminodipropionitrile will be used as a model system to study the individual roles of MTs, NFs and couplers in nerve growth and axonal transport. (3) Correlated time-lapse cinemicrography and electron microscopy will be used to relate directly variations in the nerve growth rate with changes in the number and distribution of couplers and the organizational state of the axonal cytoskeleton. (4) Immunocytochemical techniques will be used to examine the composition of couplers. The studies will help elucidate the structural and molecular bases of nerve growth and axonal transport which, in turn, will shed new light on the underlying causes of axonopathies associated with certain neurotoxic and nerve degenerative diseases which may be due, at least in part, to a defective axonal transport system.