title: AtSNX1 defines an endosome for auxin-carrier trafficking in Arabidopsis.
abstract: 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.
authors.affiliation: 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.
authors.forename: Yvon
authors.initials: Y
authors.lastname: Jaillais
authors.forename: Isabelle
authors.initials: I
authors.lastname: Fobis-Loisy
authors.forename: Christine
authors.initials: C
authors.lastname: Miège
authors.forename: Claire
authors.initials: C
authors.lastname: Rollin
authors.forename: Thierry
authors.initials: T
authors.lastname: Gaude
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D009154:Mutation; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism; D021381:Protein Transport; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; D033921:Vesicular Transport Proteins; D000077191:Wortmannin; C100794:AUX1 protein, Arabidopsis; C116363:PIN1 protein, Arabidopsis; C117013:AT5G57090 protein, Arabidopsis