1. Fluorescent castasterone reveals BRI1 signaling from the plasma membrane
- Author
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Mirela-Corina Codreanu, Jiří Friml, Miroslav Strnad, Annemieke Madder, Daniël Van Damme, Anna-Mária Szatmári, Dieter Buyst, Evelien Mylle, Joanna Schneider-Pizoń, Ana I. Caño-Delgado, Ladislav Kohout, Simone Di Rubbo, Jaroslava Hniliková, Jos Van den Begin, Miroslav Sisa, Niloufer G. Irani, Eugenia Russinova, Josep Vilarrasa-Blasi, and Kiril Mishev
- Subjects
Green Fluorescent Proteins ,Meristem ,Endocytic cycle ,Arabidopsis ,Endosomes ,GTPase ,Endocytosis ,Clathrin ,chemistry.chemical_compound ,Plant Growth Regulators ,Brassinosteroids ,Brassinosteroid ,Molecular Biology ,Fluorescent Dyes ,Microscopy, Confocal ,Dose-Response Relationship, Drug ,Molecular Structure ,biology ,Arabidopsis Proteins ,Cell Membrane ,fungi ,Cell Biology ,Receptor-mediated endocytosis ,Carbocyanines ,Cell biology ,Kinetics ,Protein Transport ,chemistry ,Seedlings ,Vacuoles ,biology.protein ,Guanine nucleotide exchange factor ,Signal transduction ,Protein Kinases ,Cholestanols ,Signal Transduction - 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.
- Published
- 2012