Actin filament bundles are required for microtubule reorientation during growth cone turning to avoid an inhibitory guidance cue.
Actin filament bundles are required for microtubule reorientation during growth cone turning to avoid an inhibitory guidance cue.
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DOI：
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发表时间：
1996-08
影响因子：
4
通讯作者：
J. Challacombe;D. Snow;Paul C. Letourneau
中科院分区：
文献类型：
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作者：
J. Challacombe;D. Snow;Paul C. Letourneau
生长锥通过的细胞外基质含有分子，如硫酸软骨素蛋白聚糖，可以抑制生长锥前进并诱导分支和转向。生长锥的转向伴随着细胞骨架的重排。为了确定肌动蛋白丝和微管的组织中发生的变化，生长锥转向，我们用延时相差显微镜观察胚胎鸡背根神经节神经元生长锥之间的纤维连接蛋白和硫酸软骨素蛋白多糖的底层边界，在存在和不存在的细胞松弛素B。生长锥固定和免疫细胞化学标记，以确定肌动蛋白丝和动态和稳定的微管。我们的研究结果表明，微管重排生长锥内完成转向，以避免硫酸软骨素蛋白聚糖。与在纤连蛋白上迁移的生长锥相比，转向生长锥更窄，并且它们包含更靠近前缘并且更多捆绑的动态微管。细胞松弛素B处理的生长锥侧边沿着的边界，而不是转向，并在侧边生长锥，微管没有捆绑和对齐。我们的结论是，肌动蛋白丝束所需的微管重新定位和生长锥转向，以避免硫酸软骨素蛋白聚糖。
The extracellular matrix through which growth cones navigate contains molecules, such as chondroitin sulfate proteoglycan, that can inhibit growth cone advance and induce branching and turning. Growth cone turning is accompanied by rearrangement of the cytoskeleton. To identify changes in the organization of actin filaments and microtubules that occur as growth cones turn, we used time-lapse phase contrast videomicroscopy to observe embryonic chick dorsal root ganglion neuronal growth cones at a substratum border between fibronectin and chondroitin sulfate proteoglycan, in the presence and absence of cytochalasin B. Growth cones were fixed and immunocytochemically labeled to identify actin filaments and dynamic and stable microtubules. Our results suggest that microtubules are rearranged within growth cones to accomplish turning to avoid chondroitin sulfate proteoglycan. Compared to growth cones migrating on fibronectin, turning growth cones were more narrow, and they contained dynamic microtubules that were closer to the leading edge and were more bundled. Cytochalasin B-treated growth cones sidestepped laterally along the border instead of turning, and in sidestepping growth cones, microtubules were not bundled and aligned. We conclude that actin filament bundles are required for microtubule reorientation and growth cone turning to avoid chondroitin sulfate proteoglycan.