title: Auxin transport inhibitors impair vesicle motility and actin cytoskeleton dynamics in diverse eukaryotes.
abstract: Many aspects of plant development, including patterning and tropisms, are largely dependent on the asymmetric distribution of the plant signaling molecule auxin. Auxin transport inhibitors (ATIs), which interfere with directional auxin transport, have been essential tools in formulating this concept. However, despite the use of ATIs in plant research for many decades, the mechanism of ATI action has remained largely elusive. Using real-time live-cell microscopy, we show here that prominent ATIs such as 2,3,5-triiodobenzoic acid (TIBA) and 2-(1-pyrenoyl) benzoic acid (PBA) inhibit vesicle trafficking in plant, yeast, and mammalian cells. Effects on micropinocytosis, rab5-labeled endosomal motility at the periphery of HeLa cells and on fibroblast mobility indicate that ATIs influence actin cytoskeleton. Visualization of actin cytoskeleton dynamics in plants, yeast, and mammalian cells show that ATIs stabilize actin. Conversely, stabilizing actin by chemical or genetic means interferes with endocytosis, vesicle motility, auxin transport, and plant development, including auxin transport-dependent processes. Our results show that a class of ATIs act as actin stabilizers and advocate that actin-dependent trafficking of auxin transport components participates in the mechanism of auxin transport. These studies also provide an example of how the common eukaryotic process of actin-based vesicle motility can fulfill a plant-specific physiological role.
authors.affiliation: Zentrum für Molekularbiologie der Pflanzen (ZMBP), Universität Tübingen, Auf der Morgenstelle 3, D-72076 Tübingen, Germany.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Dhonukshe
authors.forename: Ilya
authors.initials: I
authors.lastname: Grigoriev
authors.forename: Rainer
authors.initials: R
authors.lastname: Fischer
authors.forename: Motoki
authors.initials: M
authors.lastname: Tominaga
authors.forename: David G
authors.initials: DG
authors.lastname: Robinson
authors.forename: Jirí
authors.initials: J
authors.lastname: Hasek
authors.forename: Tomasz
authors.initials: T
authors.lastname: Paciorek
authors.forename: Jan
authors.initials: J
authors.lastname: Petrásek
authors.forename: Daniela
authors.initials: D
authors.lastname: Seifertová
authors.forename: Ricardo
authors.initials: R
authors.lastname: Tejos
authors.forename: Lee A
authors.initials: LA
authors.lastname: Meisel
authors.forename: Eva
authors.initials: E
authors.lastname: Zazímalová
authors.forename: Theodorus W J
authors.initials: TW
authors.lastname: Gadella
authors.forename: York-Dieter
authors.initials: YD
authors.lastname: Stierhof
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueda
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Oiwa
authors.forename: Anna
authors.initials: A
authors.lastname: Akhmanova
authors.forename: Roland
authors.initials: R
authors.lastname: Brock
authors.forename: Anne
authors.initials: A
authors.lastname: Spang
authors.forename: Jirí
authors.initials: J
authors.lastname: Friml
mesh_terms: D000199:Actins / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism; D001692:Biological Transport; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism*; D004705:Endocytosis; D007210:Indoleacetic Acids / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism
chemical_list: D000199:Actins; D007210:Indoleacetic Acids