A research article published by Professor Jiejie Li’s group in Plant Physiology discovered villin-mediated actin dynamic is targeted by an auxin transport inhibitor to regulate polar auxin transport
A research article titled “Villins are targets of auxin transport inhibitor” published by Professor Jiejie Li’s group was released in Plant Physiology (IF="6.305)" on July 16th 2019. This study revealed a new mechanistic link between the actin cytoskeleton, vesicle trafficking and auxin transport.
The phytohormone auxin plays critical roles in various plant developmental programs by controlling cell expansion and polarity, as well as organ patterning. Our knowledge of the mechanisms of polar auxin transport has been extended by the use of synthetic auxin transport inhibitors (ATIs). ATIs inhibit auxin efflux and block polar auxin flow between cells. One mode of ATI action is its impact on actin cytoskeleton while different ATIs have distinct impacts on actin organization. However, except for NPA, the precise mechanism of actin remodeling in response to other ATIs remains unclear.
In this study, the mechanistic action of 2,3,5-triiodobenzoic acid (TIBA) on actin dynamics has been explored in detail. By surveying mutants for candidate actin-binding proteins with reduced TIBA sensitivity, the researcher determined that Arabidopsis (Arabidopsis thaliana) villins contribute to TIBA action. By directly interacting with the C-terminal headpiece domain of villins, TIBA causes villin to oligomerize, driving excessive bundling of actin filaments. The resulting changes in actin dynamics impair auxin transport by disrupting the trafficking of PIN auxin efflux carriers and reducing their levels at the plasma membrane (PM). Collectively, this work reveled a new mechanism about an auxin transport inhibitor target villin-mediated actin dynamic to regulate polar auxin transport.
Figure A. Schematic illustration of the positively regulatory mechanisms of TIBA in VLN4-mediated bundling.
Figure B. Mode of TIBA target VLN4-mediated actin dynamic to regulate polar auxin transport.
Professor Jiejie Li is the corresponding author who is affiliated to Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University. Her PhD candidate Minxia Zou is the first author. This research was funded by the Fundamental Research Funds for Central Universities (2016NT07) to JL.