Chemical inhibition of a subset of Arabidopsis thaliana GSK3-like kinases activates brassinosteroid signaling.

Bert de Rybel (1, 2) , Dominique Audenaert (1, 2) , Grégory Vert (3) , Wilfried Rozhon (4) , Juliane Mayerhofer (4) , Frank Peelman (5, 6) , Silvie Coutuer (1, 2) , Tinneke Denayer (7, 8) , Leentje Jansen (1, 2) , Long Nguyen (9) , Isabelle Vanhoutte (1, 2) , Gerrit T S Beemster (1, 2, 10) , Kris Vleminckx (7, 8) , Claudia Jonak (4) , Joanne Chory (11) , Dirk Inzé (1, 2) , Eugenia Russinova (1, 2) , Tom Beeckman (1, 2)

1 Department of Systems Biology
2 UGENT - Universiteit Gent = Ghent University
3 BPMP - Biochimie et Physiologie Moléculaire des Plantes
4 GMI - Gregor Mendel Institute of Molecular Plant Biology
5 Department of Medical Protein Research
6 Department of Biochemistry
7 Department of Molecular Biomedical Research
8 Department of Molecular Biology
9 VIB
10 Department of Biology
11 Plant Biology Laboratory and Howard Hughes Medical Institute

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.

Mots clés: GSK3; ARABIDOPSIS; BRASSINOSTEROID SIGNALING

Domaines: Biologie végétale

Bert de Rybel, Dominique Audenaert, Grégory Vert, Wilfried Rozhon, Juliane Mayerhofer, et al.. Chemical inhibition of a subset of Arabidopsis thaliana GSK3-like kinases activates brassinosteroid signaling.. Chemistry and Biology, 2009, 16 (6), pp.594-604. ⟨10.1016/j.chembiol.2009.04.008⟩. ⟨hal-00408971⟩