Abstract
Plant GSK3-like kinases are key regulators that modulate a broad range of physiological processes such as cell growth, stomatal and flower development, responses for abiotic and biotic stress, and carbohydrate metabolism. Arabidopsis Shaggy/GSK3-like kinases (AtSK) consist of ten members that are classified into four subfamilies (I∼IV). Only one of these Arabidopsis GSK3s, BIN2 (also named AtSK21), has been characterized by biochemical and genetic studies. BIN2 acts as a negative regulator in brassinosteroid (BR) signaling that controls cell growth and differentiation. Recent studies suggest that at least seven AtSKs are involved in BR signaling. However, specificities for the substrates and the functional differences of each member of the family remain to be determined. Here we report structural characteristics and distinct function of AtSK12 compared with BIN2. AtSK12 has a longer N-terminal extension, which is absent in BIN2. Transgenic plants overexpressing the AtSK12 mutant carrying deletion of Nterminal region display more severe dwarf phenotypes than those of the wild-type AtSK12. Microscopic analysis reveals that N-terminal-deleted AtSK12 accumulates in the nucleus. This implies that structural difference in the Nterminal region of AtSK members contributes to their subcellular localization. In contrast to BIN2, overexpression of AtSK12 does not cause a stomatal cluster. Furthermore, we show that YODA MAPKKK, which controls stomatal development, interacts with BIN2 but not with AtSK12. Our results suggest that AtSK12 mediates BR-regulated cell growth but not stomatal development while BIN2 regulates both processes. Our study provides evidence that different GSK3 members can have overlapping but non-identical functions.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bergmann, D.C., and Sack, F.D. (2007). Stomatal development. Annu. Rev. Plant. Biol. 58, 163–181.
Choe, S. (2004). Brassinosteroid biosynthesis and metabolism. In Plant Hormones: biosythesis, signal transduction, action! P.J. Davies, ed. (Kluwer Academic, Dordrecht; Boston), pp. 156–178.
Choe, S., Schmitz, R.J., Fujioka, S., Takatsuto, S., Lee, M.O., Yoshida, S., Feldmann, K.A., and Tax, F.E. (2002). Arabidopsis brassinosteroid-insensitive dwarf12 mutants are semidominant and defective in a glycogen synthase kinase 3beta-like kinase. Plant Physiol. 130, 1506–1515.
Cohen, P., and Goedert, M. (2004). GSK3 inhibitors: development and therapeutic potential. Nat. Rev. Drug Discov. 3, 479–487.
De Rybel, B., Audenaert, D., Vert, G., Rozhon, W., Mayerhofer, J., Peelman, F., Coutuer, S., Denayer, T., Jansen, L., Nguyen, L., et al. (2009). Chemical inhibition of a subset of Arabidopsis thaliana GSK3-like kinases activates brassinosteroid signaling. Chem. Biol. 16, 594–604.
Doble, B.W., and Woodgett, J.R. (2003). GSK-3: tricks of the trade for a multi-tasking kinase. J. Cell Sci. 116, 1175–1186.
Gampala, S.S., Kim, T.W., He, J.X., Tang, W., Deng, Z., Bai, M.Y., Guan, S., Lalonde, S., Sun, Y., Gendron, J.M., et al. (2007). An essential role for 14-3-3 proteins in brassinosteroid signal transduction in Arabidopsis. Dev. Cell 13, 177–189.
Gudesblat, G.E., Schneider-Pizon, J., Betti, C., Mayerhofer, J., Vanhoutte, I., van Dongen, W., Boeren, S., Zhiponova, M., de Vries, S., Jonak, C., et al. (2012). SPEECHLESS integrates brassi-nosteroid and stomata signalling pathways. Nat. Cell Biol. 14, 548–554.
He, J.X., Gendron, J.M., Yang, Y., Li, J., and Wang, Z.Y. (2002). The GSK3-like kinase BIN2 phosphorylates and destabilizes BZR1, a positive regulator of the brassinosteroid signaling pathway in Arabidopsis. Proc. Natl. Acad. Sci. USA 99, 10185–10190.
Hur, E.M., and Zhou, F.Q. (2010). GSK3 signalling in neural development. Nat. Rev. Neurosci. 11, 539–551.
Jonak, C., and Hirt, H. (2002). Glycogen synthase kinase 3/SHAGGY-like kinases in plants: an emerging family with novel functions. Trends Plant Sci. 7, 457–461.
Kaidanovich-Beilin, O., and Woodgett, J.R. (2011). GSK-3: functional insights from cell biology and animal models. Front. Mol. Neurosci. 4, 40.
Khan, M., Rozhon, W., Bigeard, J., Pflieger, D., Husar, S., Pitzschke, A., Teige, M., Jonak, C., Hirt, H., and Poppenberger, B. (2013). Brassinosteroid-regulated GSK3/Shaggy-like kinases phosphorylate mitogen-activated protein (MAP) kinase kinases, which control stomata development in Arabidopsis thaliana. J. Biol. Chem. 288, 7519–7527.
Kim, T.W., and Wang, Z.Y. (2010). Brassinosteroid signal transduction from receptor kinases to transcription factors. Annu. Rev. Plant Biol. 61, 681–704.
Kim, T.W., Guan, S., Sun, Y., Deng, Z., Tang, W., Shang, J.X., Sun, Y., Burlingame, A.L., and Wang, Z.Y. (2009). Brassinosteroid signal transduction from cell-surface receptor kinases to nuclear transcription factors. Nat. Cell Biol. 11, 1254–1260.
Kim, T.W., Guan, S., Burlingame, A.L., and Wang, Z.Y. (2011). The CDG1 kinase mediates brassinosteroid signal transduction from BRI1 receptor kinase to BSU1 phosphatase and GSK3-like kinase BIN2. Mol. Cell 43, 561–571.
Kim, T.W., Michniewicz, M., Bergmann, D.C., and Wang, Z.Y. (2012). Brassinosteroid regulates stomatal development by GSK3-mediated inhibition of a MAPK pathway. Nature 482, 419–422.
Lampard, G.R., Macalister, C.A., and Bergmann, D.C. (2008). Arabidopsis stomatal initiation is controlled by MAPK-mediated regulation of the bHLH SPEECHLESS. Science 322, 1113–1116.
Li, J., and Nam, K.H. (2002). Regulation of brassinosteroid signaling by a GSK3/SHAGGY-like kinase. Science 295, 1299–1301.
Peng, P., Yan, Z., Zhu, Y., and Li, J. (2008). Regulation of the Arabidopsis GSK3-like kinase BRASSINOSTEROID-INSENSITIVE 2 through proteasome-mediated protein degradation. Mol. Plant 1, 338–346.
Perez-Perez, J.M., Ponce, M.R., and Micol, J.L. (2002). The UCU1 Arabidopsis gene encodes a SHAGGY/GSK3-like kinase required for cell expansion along the proximodistal axis. Dev. Biol. 242, 161–173.
Rozhon, W., Mayerhofer, J., Petutschnig, E., Fujioka, S., and Jonak, C. (2010). ASKtheta, a group-III Arabidopsis GSK3, functions in the brassinosteroid signalling pathway. Plant J. 62, 215–223.
Ryu, H., Kim, K., Cho, H., Park, J., Choe, S., and Hwang, I. (2007). Nucleocytoplasmic shuttling of BZR1 mediated by phosphorylation is essential in Arabidopsis brassinosteroid signaling. Plant Cell 19, 2749–2762.
Saidi, Y., Hearn, T.J., and Coates, J.C. (2012). Function and evolution of’ green’ GSK3/Shaggy-like kinases. Trends Plant Sci. 17, 39–46.
Sutherland, C. (2011). What are the bona fide GSK3 substrates? Int. J. Alzheimers Dis. 2011, 505607.
Tang, W., Kim, T.W., Oses-Prieto, J.A., Sun, Y., Deng, Z., Zhu, S., Wang, R., Burlingame, A.L., and Wang, Z.Y. (2008). BSKs mediate signal transduction from the receptor kinase BRI1 in Arabidopsis. Science 321, 557–560.
Vert, G., and Chory, J. (2006). Downstream nuclear events in brassinosteroid signalling. Nature 441, 96–100.
Wang, Z.Y., Bai, M.Y., Oh, E., and Zhu, J.Y. (2012). Brassinosteroid signaling network and regulation of photomorphogenesis. Annu. Rev. Genet. 46, 701–724.
Yoo, M.J., Albert, V.A., Soltis, P.S., and Soltis, D.E. (2006). Phylogenetic diversification of glycogen synthase kinase 3/SHAGGYlike kinase genes in plants. BMC Plant Biol. 6, 3.
Zhao, J., Peng, P., Schmitz, R.J., Decker, A.D., Tax, F.E., and Li, J. (2002). Two putative BIN2 substrates are nuclear components of brassinosteroid signaling. Plant Physiol. 130, 1221–1229.
Author information
Authors and Affiliations
Corresponding author
About this article
Cite this article
Youn, JH., Kim, TW., Kim, EJ. et al. Structural and functional characterization of arabidopsis GSK3-like kinase AtSK12. Mol Cells 36, 564–570 (2013). https://doi.org/10.1007/s10059-013-0266-8
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10059-013-0266-8