A novel ROP/RAC effector links cell polarity, root-meristern maintenance, and vesicle trafficking
A novel ROP/RAC effector links cell polarity, root-meristern maintenance, and vesicle trafficking
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DOI：
10.1016/j.cub.2007.04.038
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发表时间：
2007-06-05
期刊：
影响因子：
9.2
通讯作者：
Yalovsky, Shaul
中科院分区：
文献类型：
--
作者：
Lavy, Meirav;Bloch, Daria;Yalovsky, Shaul
ROP/RAC GTP酶是植物中细胞极性的主要调节剂，涉及多种信号级联的调节，包括细胞骨架组织、囊泡运输和Ca 2梯度[1-8]。ROP参与分化过程的情况尚不清楚。在这里，我们显示了一种新的ROP/RAC效应器，指定的组成型活性ROPs 1（ICR 1），与GTP结合的ROP相互作用的相互作用。ICR 1敲低或沉默导致细胞变形和根干细胞群的损失。ICR 1表型的异位表达激活ROP，诱导叶表皮铺面和根毛细胞的细胞变形[3，5，6，9]。ICR 1由卷曲螺旋结构域组成，并与自身和外囊泡束缚复合物亚基SEC 3形成复合物[10-13]。ICR 1-SEC 3复合物可以与ROP在体内相互作用。过表达ROP和SEC 3非相互作用的ICR 1突变体的植物具有野生型表型。总之，我们的研究结果表明，ICR 1是一个支架介导的蛋白质复合物的形成所需的细胞极性，连接ROP/RAC GTP酶与囊泡运输和分化。
ROP/RAC GTPases are master regulators of cell polarity in plants, implicated in the regulation of diverse signaling cascades including cytoskeleton organization, vesicle trafficking, and Ca 2 gradients [1-8]. The involvement of ROPs in differentiation processes is yet unknown. Here we show the identification of a novel ROP/RAC effector, designated interactor of constitutive active ROPs 1 (ICR1), that interacts with GTP-bound ROPs. ICR1 knockdown or silencing leads to cell deformation and loss of root stem-cell population. Ectopic expression of ICR1 phenocopies activated ROPs, inducing cell deformation of leaf-epidermis-pavement and root-hair cells [3, 5, 6, 9]. ICR1 is comprised of coiled-coil domains and forms complexes with itself and the exocyst vesicle-tethering complex subunit SEC3 [10-13]. The ICR1-SEC3 complexes can interact with ROPs in vivo. Plants overexpressing a ROP- and SEC3-noninteracting ICR1 mutant have a wild-type phenotype. Taken together, our results show that ICR1 is a scaffold-mediating formation of protein complexes that are required for cell polarity, linking ROP/RAC GTPases with vesicle trafficking and differentiation.