Centrosomal control of microtubule dynamics
Centrosomal control of microtubule dynamics
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DOI：
10.1073/pnas.96.1.115
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发表时间：
1999-01-05
影响因子：
11.1
通讯作者：
Borisy, G
中科院分区：
文献类型：
--
作者：
Rodionov, V;Nadezhdina, E;Borisy, G
在许多动物细胞中，微管的负端被中心体覆盖，而正端是自由的，并显示动态不稳定性。我们通过检查从其中去除中心体的细胞质中的MT行为来测试中心体的作用。用Cy 3-微管蛋白注射细胞以荧光标记MT，并通过使用离心程序去核。去核导致含有或缺乏中心体的胞质混合物。研究了成纤维细胞（CHO-K1）和上皮细胞（BSC-1）。在含有中心体的成纤维细胞质中，MT表现出与完整细胞中的MT无区别的动态不稳定性。相反，在缺少中心体的细胞质中，MT在负端以约12 μ m/min的速率被研磨缩短，而在正端以相同的速率生长。从动态不稳定到持续生长的正端行为的变化与负端解聚产生的游离微管蛋白亚基水平升高（无中心体的细胞质中为78%，完整细胞中为44%）相关。与成纤维细胞相反，在从上皮细胞制备的无中心体的胞质中，MT在正末端显示动态不稳定性，而在负末端显示相对稳定性，这可能是由于分布在整个细胞质中的特定负末端稳定因子。一个负-末端解聚机制的作用是消除MT组织中的错误，MT正末端的动态不稳定性是负末端加帽的结果终止于中心体。
In many animal cells, minus ends of micrctubules (MTs) are thought to be capped by the centrosome whereas plus ends are free and display dynamic instability. We tested the role of the centrosome by examining MT behavior in cytoplasts from which the centrosome was removed, Cells were injected with Cy3-tubulin to fluorescently label MTs and were enucleated by using a centrifugation procedure. Enucleation resulted in a mixture of cytoplasts containing or lacking the centrosome. Fibroblast (CHO-K1) and epithelial (BSC-1) cells were investigated. In fibroblast cytoplasts containing the centrosome, MTs showed dynamic instability indistinguishable from that in intact cells. In contrast, in cytoplasts lacking the centrosome, MTs treadmilled-shortened at the minus end at about 12 mu m/min while growing at the plus end at the same rate. The change in behavior of the plus end from dynamic instability to persistent growth correlated with am elevated level of free tubulin subunits (78% in centrosome-free cytoplasts vs. 44% in intact cells) generated by minus-end depolymerization. In contrast to fibroblast cells, in centrosome-free cytoplasts prepared from epithelial cells, MTs displayed dynamic instability at plus ends and relative stability at minus ends presumably because of specific minus-end stability factors distributed throughout the cytoplasm, We suggest that, in fibroblast cells, a minus-end depolymerization mechanism functions to eliminate errors in MT organization and that dynamic instability of MT plus ends is a result of capping of minus ends by the centrosome.