Profilin Regulates Apical Actin Polymerization to Control Polarized Pollen Tube Growth.
Profilin Regulates Apical Actin Polymerization to Control Polarized Pollen Tube Growth.
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DOI：
10.1016/j.molp.2015.09.013
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发表时间：
2015-12
期刊：
影响因子：
27.5
通讯作者：
Xiaonan Liu;Xiaolu Qu;Yuxiang Jiang;Ming Chang;Ruihui Zhang;Youjun Wu;Ying Fu;Shanjin Huang
中科院分区：
文献类型：
--
作者：
Xiaonan Liu;Xiaolu Qu;Yuxiang Jiang;Ming Chang;Ruihui Zhang;Youjun Wu;Ying Fu;Shanjin Huang
花粉管生长是有花植物生殖过程中的重要环节，其生长依赖于顶端肌动蛋白丝的动态变化。顶端肌动蛋白丝被认为参与了小泡融合和定位在花粉管中的调节。然而，调控花粉管顶端肌动蛋白结构构建的分子机制仍不清楚。在这里，我们确定profilin作为一个重要的球员在调节肌动蛋白聚合在顶端膜在花粉管。profilin的下调降低了丝状肌动蛋白的量，诱导顶端肌动蛋白丝的解体，并减少了尖端定向的小泡运输和积累在花粉管中。肌动蛋白动力学的直接可视化显示，起源于顶端膜的肌动蛋白丝的伸长下降profilin突变花粉管。突变profilin，是有缺陷的结合聚-L-脯氨酸只有部分拯救肌动蛋白聚合缺陷profilin突变花粉管，虽然它完全拯救肌动蛋白营业额表型。我们建议，profilin控制在花粉管尖端的肌动蛋白结构的建设，大概是通过有利于formin介导的肌动蛋白聚合在顶端膜。
Pollen tube growth is an essential step during flowering plant reproduction, whose growth depends on a population of dynamic apical actin filaments. Apical actin filaments were thought to be involved in the regulation of vesicle fusion and targeting in the pollen tube. However, the molecular mechanisms that regulate the construction of apical actin structures in the pollen tube remain largely unclear. Here, we identify profilin as an important player in the regulation of actin polymerization at the apical membrane in the pollen tube. Downregulation of profilin decreased the amount of filamentous actin and induced disorganization of apical actin filaments, and reduced tip-directed vesicle transport and accumulation in the pollen tube. Direct visualization of actin dynamics revealed that the elongation of actin filaments originating at the apical membrane decreased in profilin mutant pollen tubes. Mutant profilin that is defective in binding poly-L-proline only partially rescues the actin polymerization defect in profilin mutant pollen tubes, although it fully rescues the actin turnover phenotype. We propose that profilin controls the construction of actin structures at the pollen tube tip, presumably by favoring formin-mediated actin polymerization at the apical membrane.