Encounters between dynamic cortical microtubules promote ordering of the cortical array through angle-dependent modifications of microtubule behavior
Encounters between dynamic cortical microtubules promote ordering of the cortical array through angle-dependent modifications of microtubule behavior
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DOI：
10.1105/tpc.104.026930
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发表时间：
2004-12-01
期刊：
影响因子：
11.6
通讯作者：
Cyr, R
中科院分区：
文献类型：
--
作者：
Dixit, R;Cyr, R
有序的皮层微管排列对正常植物形态发生至关重要，但这些排列是如何形成的尚不清楚。单个皮质微管的动力学是随机的，不能完全解释观察到的顺序；然而，利用表达MBD-DsRed（哺乳动物MAP4与Discosoma sp红色荧光蛋白融合的微管结合区域）或YFP-TUA6（与拟南芥α -微管蛋白6异构体融合的黄色荧光蛋白）微管标记的烟草细胞，我们发现了微管间的相互作用，改变了它们的随机行为。当皮层微管的生长正端遇到先前存在的皮层微管时，就会发生微管间的相互作用。重要的是，这种碰撞的结果取决于它们发生的角度：大角度碰撞的特点是微管接触时间比浅角度碰撞短约7倍，大角度碰撞导致微管解聚的可能性是浅角度碰撞的两倍。因此，大角度碰撞促进微管不稳定，而浅角度碰撞促进微管稳定和对齐。根据观察到的细胞中横向和纵向取向皮质微管的行为，对模拟微管的行为进行蒙特卡罗建模，揭示了这些微管间相互作用的简单规则对于促进动态微管自组织成平行构型是必要和充分的。
Ordered cortical microtubule arrays are essential for normal plant morphogenesis, but how these arrays form is unclear. The dynamics of individual cortical microtubules are stochastic and cannot fully account for the observed order; however, using tobacco (Nicotiana tabacum) cells expressing either the MBD-DsRed (microtubule binding domain of the mammalian MAP4 fused to the Discosoma sp red fluorescent protein) or YFP-TUA6 (yellow fluorescent protein fused to the Arabidopsis alpha-tubulin 6 isoform) microtubule markers, we identified intermicrotubule interactions that modify their stochastic behaviors. The intermicrotubule interactions occur when the growing plus-ends of cortical microtubules encounter previously existing cortical microtubules. Importantly, the outcome of such encounters depends on the angle at which they occur: steep-angle collisions are characterized by approximately sevenfold shorter microtubule contact times compared with shallow-angle encounters, and steep-angle collisions are twice as likely to result in microtubule depolymerization. Hence, steep-angle collisions promote microtubule destabilization, whereas shallow-angle encounters promote both microtubule stabilization and coalignment. Monte Carlo modeling of the behavior of simulated microtubules, according to the observed behavior of transverse and longitudinally oriented cortical microtubules in cells, reveals that these simple rules for intermicrotubule interactions are necessary and sufficient to facilitate the self-organization of dynamic microtubules into a parallel configuration.