Subcellular trafficking of the Arabidopsis auxin influx carrier AUX1 uses a novel pathway distinct from PIN1
Subcellular trafficking of the Arabidopsis auxin influx carrier AUX1 uses a novel pathway distinct from PIN1
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DOI：
10.1105/tpc.106.042770
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发表时间：
2006-11-01
期刊：
影响因子：
11.6
通讯作者：
Friml, Jiri
中科院分区：
文献类型：
--
作者：
Kleine-Vehn, Juergen;Dhonukshe, Pankaj;Friml, Jiri
植物激素生长素的定向流动介导了多种发育过程，包括模式和向性。生长素转运组分AUX 1和PIN-FORMED 1在拟南芥根细胞顶膜和基底膜上的定位支持了细胞间生长素流动的方向性。在这里，我们研究了AUX 1的极性运输机制。实时活细胞分析沿着亚细胞标记物显示，AUX 1位于原始韧皮部细胞的顶端质膜以及所有细胞类型中高尔基体和内体的高度动态亚群。AUX 1的质膜和细胞内池通过肌动蛋白依赖性组成性运输相互连接，这对囊泡运输抑制剂布雷菲德菌素A不敏感。AUX 1亚细胞动力学不受生长素流入抑制剂NOA的影响，但被生长素流出抑制剂TIBA和PBA阻断。此外，生长素转运抑制剂和干扰膜的甾醇组成破坏极性AUX 1分布在质膜。与PIN 1运输相比，AUX 1动力学对运输抑制剂表现出不同的敏感性，并且独立于内体运输调节剂ARF GEF GNOME。因此，AUX 1在植物中使用不同于PIN运输的新的运输途径，为生长素运输的精细调节提供了额外的机制。
The directional flow of the plant hormone auxin mediates multiple developmental processes, including patterning and tropisms. Apical and basal plasma membrane localization of AUXIN-RESISTANT1 (AUX1) and PIN-FORMED1 (PIN1) auxin transport components underpins the directionality of intercellular auxin flow in Arabidopsis thaliana roots. Here, we examined the mechanism of polar trafficking of AUX1. Real-time live cell analysis along with subcellular markers revealed that AUX1 resides at the apical plasma membrane of protophloem cells and at highly dynamic subpopulations of Golgi apparatus and endosomes in all cell types. Plasma membrane and intracellular pools of AUX1 are interconnected by actin-dependent constitutive trafficking, which is not sensitive to the vesicle trafficking inhibitor brefeldin A. AUX1 subcellular dynamics are not influenced by the auxin influx inhibitor NOA but are blocked by the auxin efflux inhibitors TIBA and PBA. Furthermore, auxin transport inhibitors and interference with the sterol composition of membranes disrupt polar AUX1 distribution at the plasma membrane. Compared with PIN1 trafficking, AUX1 dynamics display different sensitivities to trafficking inhibitors and are independent of the endosomal trafficking regulator ARF GEF GNOM. Hence, AUX1 uses a novel trafficking pathway in plants that is distinct from PIN trafficking, providing an additional mechanism for the fine regulation of auxin transport.