Augmin Triggers Microtubule-Dependent Microtubule Nucleation in Interphase Plant Cells
Augmin Triggers Microtubule-Dependent Microtubule Nucleation in Interphase Plant Cells
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Augmin 触发间期植物细胞中微管依赖性微管成核
DOI：
10.1016/j.cub.2014.09.053
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发表时间：
2014-11-17
期刊：
影响因子：
9.2
通讯作者：
Kong, Zhaosheng
中科院分区：
文献类型：
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作者：
Liu, Ting;Tian, Juan;Kong, Zhaosheng
间期植物细胞需要依赖于微管(MT)的微管蛋白成核，才能在质膜下建立一个高度动态的皮质MT网络，这会影响细胞壁材料的沉积，从而控制细胞的定向扩张模式[1-6]。新形成的MT要么呈40度角，要么与现存的MT平行[7-9]。到目前为止，伽马-微管蛋白复合体如何被招募到皮质MTS的侧壁并启动MT成核一直是一个谜[10]。在这里，我们发现Augmin复合体被招募到大脑皮层MT中，并以分支和平行的形式启动MT成核。增强蛋白复合体与γ-微管蛋白复合体共定位。当增强蛋白复合体的功能受损时，MT成核频率急剧降低，其中支化成核作用最为明显。因此，Augmin基因敲除细胞表现出高度平行和捆绑的MT，取代了野生型细胞中细小的网状MT网络。我们的发现揭示了Augmin复合体在将γ-微管蛋白复合体招募到皮层MT并启动MT成核中的作用机制，他们改变了人们通常认为的Augmin有丝分裂特异性功能的范式，并确立了其在间期植物细胞MT依赖的MT成核中的关键作用。
Microtubule (MT)-dependent MT nucleation by gamma-tubulin is required for interphase plant cells to establish a highly dynamic cortical MT network underneath the plasma membrane, which influences the deposition of cell wall materials and consequently governs patterns of directional cell expansion [1-6]. Newly formed MTs either assume 40 degrees angles or are parallel to the extant ones [7-9]. To date, it has been enigmatic how the gamma-tubulin complex is recruited to the sidewall of cortical MTs and initiates MT nucleation [10]. Here, we discovered that the augmin complex was recruited to cortical MTs and initiated MT nucleation in both branching and parallel forms. The augmin complex overwhelmingly colocalized with the gamma-tubulin complex. When the function of the augmin complex was compromised, MT nucleation frequency was drastically reduced, most obviously for the branching nucleation. Consequently, the augmin knockdown cells displayed highly parallel and bundled MTs, replacing the fine and mesh-like MT network in the wild-type cells. Our findings uncovered a mechanism by which the augmin complex functions in recruiting the gamma-tubulin complex to cortical MTs and initiating MT nucleation, and they shifted the paradigm of the commonly perceived mitotic-specific function of augmin and established its crucial function in MT-dependent MT nucleation in interphase plant cells.