Abstract
Receptor-mediated endocytosis is an integral part of signal transduction as it mediates signal attenuation and provides spatial and temporal dimensions to signaling events. One of the best-studied leucine-rich repeat receptor-like kinases in plants, BRASSINOSTEROID INSENSITIVE 1 (BRI1), perceives its ligand, the brassinosteroid (BR) hormone, at the cell surface and is constitutively endocytosed. However, the importance of endocytosis for BR signaling remains unclear. Here we developed a bioactive, fluorescent BR analog, Alexa Fluor 647-castasterone (AFCS), and visualized the endocytosis of BRI1-AFCS complexes in living Arabidopsis thaliana cells. Impairment of endocytosis dependent on clathrin and the guanine nucleotide exchange factor for ARF GTPases (ARF-GEF) GNOM enhanced BR signaling by retaining active BRI1-ligand complexes at the plasma membrane. Increasing the trans-Golgi network/early endosome pool of BRI1-BR complexes did not affect BR signaling. Our findings provide what is to our knowledge the first visualization of receptor-ligand complexes in plants and reveal clathrin- and ARF-GEF-dependent endocytic regulation of BR signaling from the plasma membrane.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Arabidopsis / enzymology
-
Arabidopsis / metabolism*
-
Arabidopsis / ultrastructure
-
Arabidopsis Proteins / antagonists & inhibitors
-
Arabidopsis Proteins / genetics
-
Arabidopsis Proteins / metabolism*
-
Brassinosteroids / chemistry
-
Brassinosteroids / metabolism
-
Carbocyanines / chemistry*
-
Cell Membrane / metabolism*
-
Cell Membrane / ultrastructure
-
Cholestanols / chemistry
-
Cholestanols / metabolism*
-
Dose-Response Relationship, Drug
-
Endocytosis*
-
Endosomes / enzymology
-
Endosomes / metabolism
-
Endosomes / ultrastructure
-
Fluorescent Dyes / chemistry*
-
Green Fluorescent Proteins / genetics
-
Kinetics
-
Meristem / enzymology
-
Meristem / metabolism
-
Meristem / ultrastructure
-
Microscopy, Confocal
-
Molecular Structure
-
Plant Growth Regulators
-
Protein Kinases / genetics
-
Protein Kinases / metabolism*
-
Protein Transport
-
Seedlings / enzymology
-
Seedlings / metabolism
-
Seedlings / ultrastructure
-
Signal Transduction*
-
Vacuoles / enzymology
-
Vacuoles / metabolism
-
Vacuoles / ultrastructure
Substances
-
Alexa Fluor 647
-
Arabidopsis Proteins
-
Brassinosteroids
-
Carbocyanines
-
Cholestanols
-
Fluorescent Dyes
-
Plant Growth Regulators
-
Green Fluorescent Proteins
-
castasterone
-
Protein Kinases
-
BRI1 protein, Arabidopsis
Associated data
-
PubChem-Substance/135642942