Rho GTPase Signaling Activates Microtubule Severing to Promote Microtubule Ordering in Arabidopsis
Rho GTPase Signaling Activates Microtubule Severing to Promote Microtubule Ordering in Arabidopsis
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DOI：
10.1016/j.cub.2013.01.022
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发表时间：
2013-02-18
期刊：
影响因子：
9.2
通讯作者：
Fu, Ying
中科院分区：
文献类型：
--
作者：
Lin, Deshu;Cao, Lingyan;Fu, Ying
背景：有序的皮质微管阵列在细胞分裂和扩张的空间控制中起着关键作用，对植物的生长、形态发生和发育是必不可少的。已知各种发育、激素和机械信号以及大量MT相关蛋白影响皮质MT组织，但其潜在机制尚不清楚。我们以前的研究表明，由ROP6 Rho GTPase及其效应器RIC1介导的生长素信号促进了路面细胞中皮质MT的有序排列，但RIC1如何控制皮质MT组织成有序的阵列尚不清楚。结果：我们的遗传筛选发现保守的MT切断蛋白katanin(KTN1)是ROP6-RIC1信号通路的下游组成部分，导致皮质MT有序排列。KTN1和RIC1蛋白呈重叠定位。体内和体外研究表明，RIC1与KTN1物理上相互作用，并促进KTN1的MT切断活性。活细胞成像揭示了RIC1在促进分支MT的脱落中的作用，这种作用依赖于KTN1。结论：我们已经证明Rho GTPase信号通路调节Katanin介导的MT在植物细胞中的切断，并揭示了支持植物皮质MT的排列和排序的明确的调控机制。我们的发现提供了新的见解，以了解潜在的生长刺激的调节机制，如生长素促进植物中的皮质MT组织成平行阵列。
Background: Ordered cortical microtubule (MT) arrays play a critical role in the spatial control of cell division and expansion and are essential for plant growth, morphogenesis, and development. Various developmental, hormonal, and mechanical signals and a large number of MT-associated proteins are known to impact cortical MT organization, but the underlying mechanisms remain poorly understood. Our previous studies show that auxin signaling, which is mediated by the ROP6 Rho GTPase and its effector RIC1, promotes the ordering of cortical MTs in pavement cells, but it is unknown how RIC1 controls the organization of cortical MTs into well-ordered arrays.Results: Our genetic screens identified the conserved MT-severing protein katanin (KTN1) as a downstream component of the ROP6-RIC1 signaling pathway leading to well-ordered arrangement of cortical MTs. KTN1 and RIC1 proteins displayed overlapping localization. In vivo and in vitro studies showed that RIC1 physically interacts with and promotes the MT-severing activity of KTN1. Live-cell imaging reveals a role for RIC1 in promoting detachment of branched MTs that is known to rely on KTN1.Conclusion: We have demonstrated that a Rho GTPase signaling pathway regulates katanin-mediated MT severing in plant cells and uncovered an explicit regulatory mechanism underpinning the alignment and ordering of cortical MTs in plants. Our findings provide new insights into regulatory mechanisms underlying growth stimuli such as auxin promote the organization of cortical MTs into parallel arrays in plants.