Auxin transport inhibitors impair vesicle motility and actin cytoskeleton dynamics in diverse eukaryotes.
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.
Dhonukshe
Pankaj
P
Zentrum für Molekularbiologie der Pflanzen (ZMBP), Universität Tübingen, Auf der Morgenstelle 3, D-72076 Tübingen, Germany.
Grigoriev
Ilya
I
Fischer
Rainer
R
Tominaga
Motoki
M
Robinson
David G
DG
Hasek
Jirí
J
Paciorek
Tomasz
T
Petrásek
Jan
J
Seifertová
Daniela
D
Tejos
Ricardo
R
Meisel
Lee A
LA
Zazímalová
Eva
E
Gadella
Theodorus W J
TW
Stierhof
York-Dieter
YD
Ueda
Takashi
T
Oiwa
Kazuhiro
K
Akhmanova
Anna
A
Brock
Roland
R
Spang
Anne
A
Friml
Jirí
J
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
D000199:Actins; D007210:Indoleacetic Acids