The Drosophila CLASP homologue, Mast/Orbit regulates the dynamic behaviour of interphase microtubules by promoting the pause state
The Drosophila CLASP homologue, Mast/Orbit regulates the dynamic behaviour of interphase microtubules by promoting the pause state
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DOI：
10.1002/cm.20208
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发表时间：
2007-08-01
影响因子：
--
通讯作者：
Sunkel, Claudio E.
中科院分区：
文献类型：
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作者：
Sousa, Aureliana;Reis, Rita;Sunkel, Claudio E.
一组重要的微管相关蛋白是正端跟踪蛋白，其中包括Mast/Orbit/CLASPS家族等。这些蛋白质中有几个在间期和有丝分裂过程中对微管的动态特性具有重要的调节作用，但其确切的机制仍有待阐明。为了研究MAST在间期微管行为调控中的作用，我们利用RNAi技术在稳定表达GFP-α-微管蛋白的果蝇S2培养细胞中进行RNAi，并在体内跟踪微管的行为。肥大耗竭的细胞表现为微管密度显著降低，间期微管排列异常，很少到达细胞皮质。对动力学参数的分析表明，在没有Mast的情况下，微管是高度动态的，不断生长或收缩。这些变化的特征是到暂停状态的转换频率和从暂停状态的转换频率严重降低。此外，对冷处理后的微管聚合的分析表明，由于肥大耗尽的细胞在返回常温后不久就会形成微管，因此成核不需要肥大。综上所述，这些结果表明，MAST通过特定地促进暂停状态，在减少微管的动态行为方面发挥了重要作用。
An important group of microtubule associated proteins are the plus-end tracking proteins which includes the Mast/Orbit/CLASPs family amongst others. Several of these proteins have important functions during interphase and mitosis in the modulation of the dynamic properties of microtubules, however, the precise mechanism remains to be elucidated. To investigate the role of Mast in the regulation of microtubule behaviour during interphase, we used RNAi in Drosophila S2 culture cells stably expressing GFP-alpha-tubulin and followed the behaviour of microtubules in vivo. Mast depleted cells show a significant reduction of microtubule density and an abnormal interphase microtubule array that rarely reaches the cell cortex. Analysis of the dynamic parameters revealed that in the absence of Mast, microtubules are highly dynamic, constantly growing or shrinking. These alterations are characterized by a severe reduction in the transition frequencies to and from the pause state. Moreover, analysis of de novo microtubule polymerization after cold treatment showed that Mast is not required for nucleation since Mast depleted cells nucleate microtubules soon after return to normal temperature. Taken together these results suggest that Mast plays an essential role in reducing the dynamic behaviour of microtubules by specifically promoting the pause state.