Jaillais Yvon, Fobis-Loisy Isabelle, Miège Christine, Rollin Claire, Gaude Thierry
Reproduction et Développement des Plantes, IFR128 BioSciences Lyon-Gerland, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Claude Bernard Lyon I, Ecole Normale Supérieure de Lyon, Lyon, France.
Nature. 2006 Sep 7;443(7107):106-9. doi: 10.1038/nature05046. Epub 2006 Aug 27.
Polarized cellular distribution of the phytohormone auxin and its carriers is essential for normal plant growth and development. Polar auxin transport is maintained by a network of auxin influx (AUX) and efflux (PIN) carriers. Both auxin transport and PIN protein cycling between the plasma membrane and endosomes require the activity of the endosomal GNOM; however, intracellular routes taken by these carriers remain largely unknown. Here we show that Arabidopsis thaliana SORTING NEXIN 1 (AtSNX1) is involved in the auxin pathway and that PIN2, but not PIN1 or AUX1, is transported through AtSNX1-containing endosomes. We demonstrate that the snx1-null mutant exhibits multiple auxin-related defects and that loss of function of AtSNX1 severely enhances the phenotype of a weak gnom mutant. In root cells, we further show that AtSNX1 localizes to an endosomal compartment distinct from GNOM-containing endosomes, and that PIN2 accumulates in this compartment after treatment with the phosphatidylinositol-3-OH kinase inhibitor wortmannin or after a gravity stimulus. Our data reveal the existence of a novel endosomal compartment involved in PIN2 endocytic sorting and plant development.
植物激素生长素及其载体的极性细胞分布对于植物正常生长发育至关重要。极性生长素运输由生长素内流载体（AUX）和外流载体（PIN）网络维持。生长素运输以及PIN蛋白在质膜和内体之间的循环都需要内体GNOM的活性；然而，这些载体所采用的细胞内途径仍 largely 未知。在这里，我们表明拟南芥分选连接蛋白1（AtSNX1）参与生长素途径，并且PIN2，而非PIN1或AUX1，通过含有AtSNX1的内体进行运输。我们证明snx1缺失突变体表现出多种与生长素相关的缺陷，并且AtSNX1功能丧失严重增强了弱gnom突变体的表型。在根细胞中，我们进一步表明AtSNX1定位于与含有GNOM的内体不同的内体区室，并且在用磷脂酰肌醇-3-OH激酶抑制剂渥曼青霉素处理后或在重力刺激后，PIN2在该区域室中积累。我们的数据揭示了存在一个参与PIN2内吞分选和植物发育的新型内体区室。
