Cell-Type-Dependent but CME-Independent Polar Localization of Silicon Transporters in Rice
Cell-Type-Dependent but CME-Independent Polar Localization of Silicon Transporters in Rice
复制标题
水稻中硅转运蛋白的细胞类型依赖性但不依赖 CME 的极性定位
DOI：
10.1093/pcp/pcac032
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发表时间：
2022
影响因子：
4.9
通讯作者：
Ma Jian Feng
中科院分区：
文献类型：
--
作者：
Konishi Noriyuki;Huang Sheng;Yamaji Naoki;Ma Jian Feng
硅（Si）是水稻可持续高产所需的重要营养物质，其吸收是由一对具有极性定位的内流(OsLsi1) -外流（OsLsi2）转运体介导的。然而，它们的极性背后的机制是未知的。在这里，我们发现硅转运体的极性取决于细胞类型。Si的供应并未改变OsLsi1和OsLsi2的极性定位，但降低了它们的蛋白丰度。双重免疫染色显示，OsLsi1和OsLsi2的定位在外胚层的侧极区边缘被Casparian条带分离，而它们在外胚层的横向则略有重叠。当OsLsi1在芽中异位表达时，它在基节和叶鞘的木质部薄壁细胞中显示极性定位，而在韧皮部伴细胞中不显示极性定位。非极性硅转运体大麦HvLsi2和玉米ZmLsi2在水稻中的异位表达导致其极性定位在近端。虽然osap2mgene的敲除突变体表现为矮化表型，但通过对动力蛋白相关蛋白1a的显性负诱导和对接头蛋白2复合体的mu亚基敲除抑制网格蛋白介导的内吞作用（CME），并没有改变OsLsi1和OsLsi2的极性定位。这些结果表明，CME不是硅转运子极性局域化所必需的。综上所述，我们的研究结果表明，与cme无关的机制控制着根细胞外表皮、内表皮和木质部薄壁细胞中Si转运体的极性定位。
Silicon (Si) is an important nutrient required for sustainable and high production of rice and its uptake is mediated by a pair of influx (OsLsi1)–efflux (OsLsi2) transporters showing polar localization. However, the mechanisms underlying their polarity are unknown. Here, we revealed that the polarity of the Si transporters depends on cell types. The polar localization of both OsLsi1 and OsLsi2 was not altered by Si supply, but their protein abundance was reduced. Double immunostaining showed that localization of OsLsi1 and OsLsi2 was separated at the edge of the lateral polar domain by Casparian strips in the endodermis, whereas they were slightly overlapped at the transversal side of the exodermis. When OsLsi1 was ectopically expressed in the shoots, it showed polar localization at the xylem parenchyma cells of the basal node and leaf sheath, but not at the phloem companion cells. Ectopic expression of non-polar Si transporters, barley HvLsi2 and maize ZmLsi2 in rice, resulted in their polar localization at the proximal side. The polar localization of OsLsi1 and OsLsi2 was not altered by inhibition of clathrin-mediated endocytosis (CME) by dominant-negative induction of dynamin-related protein1A and knockout of mu subunit of adaptor protein 2 complex, although the knockout mutants ofOsAP2Mgene showed dwarf phenotype. These results indicate that CME is not required for the polar localization of Si transporters. Taken together, our results indicate that CME-independent machinery controls the polar localization of Si transporters in exodermis, endodermis of root cells and xylem parenchyma cells.