A Rho family GTPase controls actin dynamics and tip growth via two counteracting downstream pathways in pollen tubes.
A Rho family GTPase controls actin dynamics and tip growth via two counteracting downstream pathways in pollen tubes.
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DOI：
10.1083/jcb.200409140
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发表时间：
2005-04-11
影响因子：
7.8
通讯作者：
Yang, Zhenbiao
中科院分区：
文献类型：
--
作者：
Gu, Ying;Fu, Ying;Dowd, Peter;Li, Shundai;Vernoud, Vanessa;Gilroy, Simon;Yang, Zhenbiao
已知神经元细胞、植物细胞和真菌菌丝中的尖端生长需要尖端定位的Rho GT3、钙和丝状肌动蛋白（F-actin），但它们如何相互作用尚不清楚。花粉管是研究顶端生长时空调控和肌动蛋白动态的理想模型。拟南芥Rho基因家族GTdR，ROP 1，通过调控顶端F-肌动蛋白动态来控制花粉管生长。这篇论文表明，ROP 1激活两个抵消途径，涉及尖端定位的ROP 1的直接靶点：RIC 3和RIC 4。RIC 4促进F-肌动蛋白组装，而RIC 3激活导致F-肌动蛋白分解的Ca 2+信号传导。RIC 4或RIC 3的过度产生或耗尽导致尖端生长缺陷，其分别通过RIC 3或RIC 4的过度产生或耗尽而被挽救。因此，ROP 1控制肌动蛋白的动力学和尖端的增长，通过检查和两个途径之间的平衡。这种GT3的双重和拮抗作用可能提供了一种统一的机制，Rho通过这种机制调节真核细胞中依赖于肌动蛋白动力学的各种过程。
Tip growth in neuronal cells, plant cells, and fungal hyphae is known to require tip-localized Rho GTPase, calcium, and filamentous actin (F-actin), but how they interact with each other is unclear. The pollen tube is an exciting model to study spatiotemporal regulation of tip growth and F-actin dynamics. An Arabidopsis thaliana Rho family GTPase, ROP1, controls pollen tube growth by regulating apical F-actin dynamics. This paper shows that ROP1 activates two counteracting pathways involving the direct targets of tip-localized ROP1: RIC3 and RIC4. RIC4 promotes F-actin assembly, whereas RIC3 activates Ca2+ signaling that leads to F-actin disassembly. Overproduction or depletion of either RIC4 or RIC3 causes tip growth defects that are rescued by overproduction or depletion of RIC3 or RIC4, respectively. Thus, ROP1 controls actin dynamics and tip growth through a check and balance between the two pathways. The dual and antagonistic roles of this GTPase may provide a unifying mechanism by which Rho modulates various processes dependent on actin dynamics in eukaryotic cells.