Kinesins Have a Dual Function in Organizing Microtubules during Both Tip Growth and Cytokinesis in Physcomitrella patens
Kinesins Have a Dual Function in Organizing Microtubules during Both Tip Growth and Cytokinesis in Physcomitrella patens
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DOI：
10.1105/tpc.113.121723
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发表时间：
2014-03-01
期刊：
影响因子：
11.6
通讯作者：
Doonan, John H.
中科院分区：
文献类型：
--
作者：
Hiwatashi, Yuji;Sato, Yoshikatsu;Doonan, John H.
微管（MT）在细胞壁材料的各向异性沉积中发挥着至关重要的作用，从而影响生长方向。多种尖端生长细胞表现出高度极化的细胞生长，并且 MT 与调节方向性和扩张有关。然而，尖端生长的植物细胞中 MT 动力学的分子机制仍不清楚。在这里，我们发现，通过生长的 MT 正端的聚结，高动态 MT 束在苔藓小立碗藓茎细胞的极化扩张区中循环形成。此外，植物特异性驱动蛋白 (KINID1) 对于胞质分裂时 MT 的正常组织至关重要，也调节尖端 MT 束的周转以及细胞生长的方向性和速率。 MT 的正端向扩展区生长，KINID1 对于该区中心 MT 单个相干焦点的稳定性是必要的，其形成与 KINID1 的积累一致。我们认为依赖于 KINID 的 MT 捆绑对于正确的生长方向以及促进生长本身至关重要。我们的研究结果表明，两个局部细胞壁沉积过程，即尖端生长和胞质分裂，以前被认为在功能和进化上是不同的，但它们具有共同的和植物特有的 MT 调节成分。
Microtubules (MTs) play a crucial role in the anisotropic deposition of cell wall material, thereby affecting the direction of growth. A wide range of tip-growing cells display highly polarized cell growth, and MTs have been implicated in regulating directionality and expansion. However, the molecular machinery underlying MT dynamics in tip-growing plant cells remains unclear. Here, we show that highly dynamic MT bundles form cyclically in the polarized expansion zone of the moss Physcomitrella patens caulonemal cells through the coalescence of growing MT plus ends. Furthermore, the plant-specific kinesins (KINID1) that are is essential for the proper MT organization at cytokinesis also regulate the turnover of the tip MT bundles as well as the directionality and rate of cell growth. The plus ends of MTs grow toward the expansion zone, and KINID1 is necessary for the stability of a single coherent focus of MTs in the center of the zone, whose formation coincides with the accumulation of KINID1. We propose that KINID-dependent MT bundling is essential for the correct directionality of growth as well as for promoting growth per se. Our findings indicate that two localized cell wall deposition processes, tip growth and cytokinesis, previously believed to be functionally and evolutionarily distinct, share common and plant-specific MT regulatory components.