DRP1-Dependent Endocytosis is Essential for Polar Localization and Boron-Induced Degradation of the Borate Transporter BOR1 in Arabidopsis thaliana
DRP1-Dependent Endocytosis is Essential for Polar Localization and Boron-Induced Degradation of the Borate Transporter BOR1 in Arabidopsis thaliana
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DOI：
10.1093/pcp/pcw121
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发表时间：
2016-09-01
影响因子：
4.9
通讯作者：
Takano, Junpei
中科院分区：
文献类型：
--
作者：
Yoshinari, Akira;Fujimoto, Masaru;Takano, Junpei
硼（B）对植物是必需的，但过量有毒。硼酸盐外排转运蛋白BOR 1在各种根细胞中表达，并在低硼条件下定位于质膜（PM）的内/中柱侧结构域。当B供应充足时，BOR 1通过内吞作用迅速降解。认为BOR 1的极性定位和降解分别对于有效的B转运和避免B毒性是重要的。在这项研究中，我们首先分析了BOR 1在根，子叶和下胚轴的亚细胞定位，并揭示了极性定位在各种细胞类型。我们还发现，BOR 1的内部极性是在根分生组织胞质分裂完成后建立的。此外，可变角度落射荧光显微镜可视化BOR 1-绿色荧光蛋白（GFP）的颗粒在PM中具有显着的横向运动，但在有限的区域。重要的是，BOR 1-GFP颗粒的一部分与参与网格蛋白包被的囊泡的断裂的蛋白相关蛋白1A（DRP 1A）共定位，并且它们一起从PM中消失。为了研究DRP 1A介导的内吞作用对BOR 1定位和降解的贡献，我们开发了DRP 1A K47 A变体的诱导型表达系统。DRP 1A变体延长网格蛋白在PM上的停留时间并抑制膜脂质的内吞作用。显性负性DRP 1A阻断了BOR 1的内吞作用，并干扰了其极性定位和B诱导的降解。我们的研究结果提供了深入了解内吞机制，调节亚细胞定位和丰富的矿物质转运蛋白的营养稳态在植物细胞。
Boron (B) is essential for plants but toxic in excess. The borate efflux transporter BOR1 is expressed in various root cells and localized to the inner/stele-side domain of the plasma membrane (PM) under low-B conditions. BOR1 is rapidly degraded through endocytosis upon sufficient B supply. The polar localization and degradation of BOR1 are considered important for efficient B translocation and avoidance of B toxicity, respectively. In this study, we first analyzed the subcellular localization of BOR1 in roots, cotyledons and hypocotyls, and revealed a polar localization in various cell types. We also found that the inner polarity of BOR1 is established after completion of cytokinesis in the root meristem. Moreover, variable-angle epifluorescence microscopy visualized BOR1-green fluorescent protein (GFP) as particles in the PM with significant lateral movements but in restricted areas. Importantly, a portion of BOR1-GFP particles co-localized with DYNAMIN-RELATED PROTEIN 1A (DRP1A), which is involved in scission of the clathrin-coated vesicles, and they disappeared together from the PM. To examine the contribution of DRP1A-mediated endocytosis to BOR1 localization and degradation, we developed an inducible expression system of the DRP1A K47A variant. The DRP1A variant prolonged the residence time of clathrin on the PM and inhibited endocytosis of membrane lipids. The dominant-negative DRP1A blocked endocytosis of BOR1 and disturbed its polar localization and B-induced degradation. Our results provided insight into the endocytic mechanisms that modulate the subcellular localization and abundance of a mineral transporter for nutrient homeostasis in plant cells.