Fluorescent castasterone reveals BRI1 signaling from the plasma membrane Journal Article

Author(s): Irani, Niloufer G; Di Rubbo, Simone; Mylle, Evelien; Van Den Begin, Jos; Schneider-Pizoń, Joanna; Hniliková, Jaroslava; Šíša, Miroslav; Buyst, Dieter; Vilarrasa-Blasi, Josep; Szatmári, Anna-Maria; Van Damme, Daniël; Mishev, Kiril; Codreanu, Mirela-Corina; Kohout, Ladislav; Strnad, Miroslav; Caño-Delgado, Ana I; Friml, Jiří; Madder, Annemieke; Russinova, Eugenia
Article Title: Fluorescent castasterone reveals BRI1 signaling from the plasma membrane
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.
Keywords: Kinetics; Carbocyanines; Fluorescent Dyes; Green Fluorescent Proteins; Protein Transport; Signal Transduction; Dose-Response Relationship, Drug; Microscopy, Confocal; Endocytosis; endosomes; Arabidopsis; Arabidopsis Proteins; Cell Membrane; Plant Growth Regulators; Seedling; Vacuoles; Meristem; Brassinosteroids; Cholestanols; Molecular Structure; Protein Kinases
Journal Title: Nature Chemical Biology
Volume: 8
Issue 6
ISSN: 1552-4469
Publisher: Nature Publishing Group  
Date Published: 2012-06-01
Start Page: 583
End Page: 589
DOI: 10.1038/nchembio.958
Open access: no