1. Chemical inhibition of a subset of Arabidopsis thaliana GSK3-like kinases activates brassinosteroid signaling.
- Author
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De Rybel B, Audenaert D, Vert G, Rozhon W, Mayerhofer J, Peelman F, Coutuer S, Denayer T, Jansen L, Nguyen L, Vanhoutte I, Beemster GT, Vleminckx K, Jonak C, Chory J, Inzé D, Russinova E, and Beeckman T
- Subjects
- Amino Acid Sequence, Aminopyridines chemistry, Arabidopsis Proteins antagonists & inhibitors, Arabidopsis Proteins metabolism, Brassinosteroids, Cholestanols chemistry, DNA-Binding Proteins, Glycogen Synthase Kinase 3 metabolism, Molecular Sequence Data, Nuclear Proteins metabolism, Phosphorylation, Protein Isoforms antagonists & inhibitors, Protein Isoforms metabolism, Protein Kinases metabolism, Sequence Homology, Amino Acid, Signal Transduction, Steroids, Heterocyclic chemistry, Succinates chemistry, Aminopyridines pharmacology, Arabidopsis enzymology, Cholestanols pharmacology, Glycogen Synthase Kinase 3 antagonists & inhibitors, Steroids, Heterocyclic pharmacology, Succinates pharmacology
- Abstract
Glycogen synthase kinase 3 (GSK3) is a key regulator in signaling pathways in both animals and plants. Three Arabidopsis thaliana GSK3s are shown to be related to brassinosteroid (BR) signaling. In a phenotype-based compound screen we identified bikinin, a small molecule that activates BR signaling downstream of the BR receptor. Bikinin directly binds the GSK3 BIN2 and acts as an ATP competitor. Furthermore, bikinin inhibits the activity of six other Arabidopsis GSK3s. Genome-wide transcript analyses demonstrate that simultaneous inhibition of seven GSK3s is sufficient to activate BR responses. Our data suggest that GSK3 inhibition is the sole activation mode of BR signaling and argues against GSK3-independent BR responses in Arabidopsis. The opportunity to generate multiple and conditional knockouts in key regulators in the BR signaling pathway by bikinin represents a useful tool to further unravel regulatory mechanisms.
- Published
- 2009
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