Tashiro T, Komiya Y
Department of Molecular and Cellular Neurobiology, Gunma University School of Medicine, Japan.
Mol Neurobiol. 1992 Summer-Fall;6(2-3):301-11. doi: 10.1007/BF02780559.
The organization of the axonal cytoskeleton was investigated by analyzing the solubility and transport profile of the major cytoskeletal proteins in motor axons of the rat sciatic nerve under normal and regenerating conditions. When extracted with the Triton-containing buffer at low temperature, 50% of tubulin and 30% of actin were recovered in the insoluble form resistant to further depolymerizing treatments. Most of this cold-insoluble form was transported in slow component a (SCa), the slower of the two subcomponents of slow axonal transport, whereas the cold-soluble form showed a biphasic distribution between SCa and SCb (slow component b). Changes in slow transport during regeneration were studied by injuring the nerve either prior to (experiment I) or after (experiment II) radioactive labeling. In experiment I where the transport of proteins synthesized in response to injury was examined, selective acceleration of SCb was detected together with an increase in the relative proportion of this component. In experiment II where the response of the preexisting cytoskeleton was examined, a shift from SCa to SCb of the cold-soluble form was observed. The differential distribution and response of the two forms of tubulin and actin suggest that the cold-soluble form may be more directly involved in axonal transport.
通过分析正常和再生条件下大鼠坐骨神经运动轴突中主要细胞骨架蛋白的溶解性和运输情况，对轴突细胞骨架的组织进行了研究。当在低温下用含 Triton 的缓冲液提取时，50%的微管蛋白和 30%的肌动蛋白以不溶性形式回收，这种形式对进一步的解聚处理具有抗性。这种冷不溶性形式的大部分在慢速运输成分 a（SCa）中运输，SCa 是慢速轴突运输的两个亚成分中较慢的一个，而冷溶性形式在 SCa 和 SCb（慢速运输成分 b）之间呈现双相分布。通过在放射性标记之前（实验 I）或之后（实验 II）损伤神经来研究再生过程中慢速运输的变化。在实验 I 中，检测了对损伤做出反应而合成的蛋白质的运输，发现 SCb 有选择性加速，同时该成分的相对比例增加。在实验 II 中，检测了预先存在的细胞骨架的反应，观察到冷溶性形式从 SCa 向 SCb 的转变。两种形式的微管蛋白和肌动蛋白的差异分布和反应表明，冷溶性形式可能更直接参与轴突运输。
