Ketelaar Tijs, Allwood Ellen G, Anthony Richard, Voigt Boris, Menzel Diedrik, Hussey Patrick J
The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, University of Durham, South Road, Durham, DH1 3LE, UK.
Curr Biol. 2004 Jan 20;14(2):145-9. doi: 10.1016/j.cub.2004.01.004.
Cell division, growth, and cytoplasmic organization require a dynamic actin cytoskeleton. The filamentous actin (F-actin) network is regulated by actin binding proteins that modulate actin dynamics. These actin binding proteins often have cooperative interactions. In particular, actin interacting protein 1 (AIP1) is capable of capping F-actin and enhancing the activity of the small actin modulating protein, actin depolymerising factor (ADF) in vitro. Here, we analyze the effect of the inducible expression of AIP1 RNAi in Arabidopsis plants to assess AIP1s role in vivo. In intercalary growing cells, the normal actin organization is disrupted, and thick bundles of actin appear in the cytoplasm. Moreover, in root hairs, there is the unusual appearance of actin cables ramifying the root hair tip. We suggest that the reduction in AIP1 results in a decrease in F-actin turnover and the promotion of actin bundling. This distortion of the actin cytoskeleton causes severe plant developmental abnormalities. After induction of the Arabidopis RNAi lines, the cells in the leaves, roots, and shoots fail to expand normally, and in the severest phenotypes, the plants die. Our data suggest that AIP1 is essential for the normal functioning of the actin cytoskeleton in plant development.
细胞分裂、生长和细胞质组织需要动态的肌动蛋白细胞骨架。丝状肌动蛋白（F-肌动蛋白）网络受调节肌动蛋白动力学的肌动蛋白结合蛋白调控。这些肌动蛋白结合蛋白常常具有协同相互作用。特别地，肌动蛋白相互作用蛋白1（AIP1）能够封端F-肌动蛋白并在体外增强小肌动蛋白调节蛋白肌动蛋白解聚因子（ADF）的活性。在此，我们分析拟南芥植株中AIP1 RNA干扰的诱导表达的影响，以评估AIP1在体内的作用。在居间生长的细胞中，正常的肌动蛋白组织被破坏，细胞质中出现粗的肌动蛋白束。此外，在根毛中，有异常的肌动蛋白束分支到根毛尖端。我们认为AIP1的减少导致F-肌动蛋白周转减少并促进肌动蛋白成束。肌动蛋白细胞骨架的这种扭曲导致严重的植物发育异常。在诱导拟南芥RNA干扰株系后，叶、根和茎中的细胞不能正常扩展，在最严重的表型中，植株死亡。我们的数据表明AIP1对于植物发育中肌动蛋白细胞骨架的正常功能是必不可少的。
