Zhiyong Wang   Department of Plant Biology   Carnegie Institution for Science   260 Panama Street   Stanford, CA 94305   Phone: (650) 325-1521 x205   Fax: (650) 325-6857   Email

Brassinosteroid signal transduction and proteomics We are interested in the signal transduction pathways through which hormonal and environmental signals regulate plant growth and development. To gain a comprehensive understanding of the biological system and to provide inter-disciplinary training to students and postdocs, we use a wide range of approaches, including molecular genetics, biochemistry, proteomics, genomics, and cell biology. Our research focuses on the brassinosteroid (BR) signal transduction pathway and proteomic study of signal transduction.
Brassinosteroid is a plant growth hormone	The brassinosteroid signal transduction pathway
BRs are plant steroid hormones that regulate a wide range of developmental and physiological processes. BR deficient mutants, such as det2, show dramatic developmental alterations such as dwarfism, male sterility, delayed flowering, reduced apical dominance, and development of light-grown morphology in the dark. One goal of our research is to gain a complete understanding of the signaling and regulatory pathways through which BRs regulate various developmental and physiological processes. Studies in the last decade have established the BR pathway as one of the best-studied signal transduction pathways in plants. BRs are perceived by the cell-surface receptor kinase BRI1, which initiates a signal transduction cascade that leads to nuclear gene expression and cellular responses. Another receptor kinase, BAK1, interacts with and facilitates activation of BRI1 upon BR binding. BR response is negatively regulated by the GSK3-like kinase BIN2 and positively regulated by the nuclear proteins BZR1 and its homolog BZR2 (also named BES1). In the absence of BRs, BIN2 phosphorylates BZR1 and BZR2 at multiple residues, and phosphorylation inhibits the transcription factors through multiple mechanisms, including degradation by the proteasome, cytoplasmic retention by the 14-3-3 proteins, and inhibiting DNA binding. BR treatment causes dephosphorylation and activation of the BZR1 and BZR2 proteins, most likely by inhibiting BIN2 or activating a phosphatase such as BSU1. Upon dephosphorylation and nuclear localization, BZR1 and its homologs bind specifically to the BR response element (BRRE) and regulate BR responsive gene expression. Our recent proteomic studies using 2-D DIGE and mass spectrometry identified new components of the BR signaling pathway, include the BR-signaling kinases (BSKs) which are substrates of BRI1 that transduce the signal to cytoplasmic components. Using proteomics and genomics tools, we are assembling the complete BR signal transduction pathway from receptor binding at the cell surface to thousands of target genes in the nucleus and to specific developmental and physiological processes. Current research projects include: (1) functional study of proteins that interact with known BR signaling proteins (such as BZR1), which have been identified using yeast two-hybrid screen and tandem affinity purification; (2) Genomic study of BZR1 target genes using chromatin immunoprecipitation-microarray and systems biology study of the BR regulatory pathway; (3) Molecular genetic studies of BR functions in specific plant developmental processes; (4) Proteomic studies of new BR signal transduction components; (5) Biochemical and cell biological studies of BR signaling mechanisms; (6) Proteomic studies of other signaling pathways that regulate plant growth and development. Our studies using molecular genetic, genomic, and proteomic approaches are yielding a detailed understanding of how BR signal is transduced from the cell surface receptor kinase to nuclear transcription factors and how the transcriptional network mediates BR regulation of specific cellular and developmental processes. The powerful proteomic and genomic methods are now used in the lab and through collaborations to dissect additional signal transduction pathways that regulate plant growth.
Identification of Brassinosteroid regulated proteins(left) and plasma membrane proteins(right) using 2-D DIGE Proteins of BR treated and untreated Arabidopsis were labeled with Cy3 and Cy5 dyes and separate by two-dimensional gel electrophoresis.

Selected Publications:

1. Wenqiang Tang, Tae-Wuk Kim, Juan A Oses-Prieto, Yu Sun, Zhiping Deng, Shengwei Zhu, Ruiju Wang, Alma L. Burlingame, and Zhi-Yong Wang (2008). BSKs mediate signal transduction from the receptor kinase BRI1 in Arabidopsis. Science, 321, 557-560.
2. Gendron, J. M., Haque, A., Gendron, N., Chang, T., Asami, T. Wang, Z-Y. (2008). Chemical genetic dissection of brassinosteroid-ethylene interaction. Molecular Plant 1, 368-379.
3. Wenqiang Tang, Zhiping Deng, Juan A Oses-Prieto, Nagi Suzuki, Shengwei Zhu, Xin Zhang, Alma L. Burlingame, and Zhi-Yong Wang. Proteomic studies of brassinosteroid signal transduction using prefractionation and 2-D DIGE (2008). Molecular Cellular Proteomics 7, 728-738
4. Zhiping Deng, Xin Zhang, Wenqiang Tang, Juan A Oses-Prieto, Nagi Suzuki, Joshua M Gendron, Huanjing Chen, Shenheng Guan, Robert J. Chalkley, T. Kaye Peterman, Alma L. Burlingame, and Zhi-Yong Wang. A Proteomic Study of Brassinosteroid Response in Arabidopsis. Molecular Cellular Proteomics, in press.
5. Joshua M. Gendron and Zhi-Yong Wang (2007). Multiple mechanisms modulate Brassinosteroid signaling. Current Opinion in Plant Biology, 10, 436-441.
6. Srinivas S. Gampala, Tae-Wuk Kim, Jun-Xian He, Wenqiang Tang, Zhiping Deng, Ming-Yi Bai, Shenheng Guan, Sylvie Lalonde, Ying Sun, Joshua M. Gendron, Huanjing Chen, Nakako Shibagaki, Robert J. Ferl, David Ehrhardt, Kang Chong, Alma L. Burlingame, and Zhi-Yong Wang (2007). An Essential Role for 14-3-3 Proteins in Brassinosteroid Signal Transduction in Arabidopsis. Developmental Cell 13, 177-189
7. Ming-Yi Bai, Li-Ying Zhang, Srinivas S. Gampala, Sheng-Wei Zhu, Wen-Yuan Song, Kang Chong, and Zhi-Yong Wang (2007). Functions of OsBZR1 and 14-3-3 proteins in brassinosteroid signaling in rice. Proc Nat Acad Sci 104, 13839-44
8. Zhang X, Chen Y, Wang ZY, Chen Z, Gu H, Qu LJ. (2007) Constitutive expression of CIR1 (RVE2) affects several circadian-regulated processes and seed germination in Arabidopsis. The Plant Journal, 51(3), 512-525
9. Wang ZY, Wang Q, Chong K, Wang F, Wang L, Bai M, Jia C. (2006). The brassinosteroid signal transduction pathway. Cell Res. 16(5): 427-34.
10. Shi, Y-H., Zhu, S-W., Mao, X-Z., Feng, J-X., Zhang, L., Cheng, J., Wei, L-P., Wang, Z-Y., Zhu, Y-X. (2006) Transcriptome Profiling, Molecular Biological and Physiological Studies Reveal a Major Role for Ethylene in Cotton Fiber Cell Elongation. Plant Cell, in press.
11. He, J-X., Gendron, J. M., Sun, Y., Gampala, S. S. L., Gendron, N., Sun, C. Q. and Wang, Z-Y. (2005). BZR1 is a transcriptional repressor with dual roles in brassinosteroid homeostasis and growth responses. Science 307, 1634-1638.
12. Wang Z-Y and He, J-X. (2004). Brassinosteroid signal transduction: choices of signals and receptors. Trends in Plant Science 9 (2), 91-96.
13. He, J-X., Gendron, J. M., Yang, Y. Li, J., Wang, Z-Y. (2002). The GSK3-like kinase BIN2 phosphorylates and destabilizes BZR1, a positive regulator of the brassinosteroid signaling pathway in Arabidopsis. Proc. Nat. Acad. Sci, 99, 10185-10990.
14. Wang, Z-Y., Nakano, T., Gendron, J. M., He, J., Chen, M., Vafeados, D., Yang, Y., Fujioka, S, Yoshida, S., Asami, T., Chory, J. (2002). Nuclear-localized BZR1 mediates brassinosteroid-induced growth and feedback suppression of brassinosteroid biosynthesis. Dev. Cell, 2, 505-513.
15. Wang, Z-Y., Setu, H., Fujioka, S., Yoshida, S., and Chory, J. (2001). BRI1 is a critical component of a plasma membrane receptor for plant steroids. Nature, 410, 380-382.
16. He, Z., Wang, Z-Y., Li, J., Zhu, Q., Lamb, C., Ronald, P., and Chory, J. (2000) Perception of brassinosteroids by the extracellular domain of the receptor kinase BRI1. Science, 288, 2360-3
17. Wang, Z-Y, Tobin, E. M. (1998). Constitutive expression of the CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) gene disrupts circadian rhythms and suppresses its own expression. Cell 93, 1207-1217.
18. Wang, Z-Y., Kenigsbuch, D., Sun, L., Harel, E., Ong, M.S., Tobin, E.M. (1997). A Myb-related transcription factor is involved in the phytochrome regulation of an Arabidopsis Lhcb gene. Plant Cell 9, 491-507.

Group members:

• Zhiyong Wang (PI)
• Zhiping Deng, PDRA
• Tae-Wuk Kim, PDRA
• Yu Sun, PDRA
• Wenqiang Tang, PDRA
• Mingyi Bai, PDRA
• Sunita Patil, M.S. student
• Ruiju Wang, visiting graduate student
• Jiangshu Liu, visiting graduate student
• Yaqi Hao, visiting graduate student
• Min Yuan, visiting graduate student
• Tian Li, visiting graduate student
• Peng Xu, visiting graduate student
• Ulrich Kutschera, visiting professor (http://www.uni-kassel.de/fb19/plantphysiology/)
• Hui Yang, Visiting Professor

Alumni:

• Junxian He, Assistant Professor, the Chinese University of Hong Kong
• Soo-Hwan Kim, Assistant Professor, Yonsei University, Korea
• Srinivas Gampala, Edenspace, Kansas
• Ying Sun, Professor, Hebei Normal University, China
• Joshua Gendron, Postdoc, UCSD