The long-term goal of this project is to understand the molecular network through which brassinosteroid (BR) and other hormonal and environmental signals together control plant growth and development. Steroids are important hormones in both plants and animals. BR regulates a wide range of developmental and physiological processes in plants through a signal transduction pathway from cell-surface receptor kinases (BRI1) to nuclear transcription factors (BZR1 and BZR2/BES1), and through crosstalk with other hormonal and environmental signaling pathways. Using a combination of genetic, genomic, biochemical, and proteomic approaches in the Arabidopsis model system, we have made tremendous progress in understanding the molecular details of how BR binding to BRI1 leads to activation of BZR1 through the evolutionarily conserved BSU1 family of PP1-like phosphatases and GSK3-like kinases. Furthermore, we have identified thousands of genomic targets of BZR1 and revealed at molecular level how the BR signaling pathway is integrated with many other signaling pathways to control cell elongation and various specific developmental programs. For this renewal proposal, we plan to continue using the combinatorial approaches to further advance our understanding of the BR signaling network. We will focus on the mechanisms of signal transduction downstream of receptor kinases, signal integration by interacting transcription factors, and integration of additional signals with the BR pathway. We will achieve the following specific Aims: 1) Elucidate the mechanisms by which the BSU family phosphatases transduce signals from different receptor kinases to distinct or overlapping downstream responses; 2) Identify and characterize the mechanism that mediates BIN2/GSK3 degradation and the functions of additional GSK3 substrates; 3) Gain a mechanistic understanding of transcriptional co-regulation through genome-wide quantitative analysis of transcription factors-DNA interactions and proteomic identification of BZR1-associated nuclear proteins; 4) Elucidate the molecular mechanisms through which sugar and target of rapamycin (TOR) regulates the steroid-dependent growth responses. The experiments outlined in this proposal will further advance our understanding of the molecular mechanisms of signaling specificity and crosstalk downstream of receptor kinases and the mechanisms of signal integration at the level of transcriptional regulation in the nucleus. Thus, this study not only is important for plant biology and agriculture, but also can potentially help us understand fundamental mechanisms of signaling and cellular regulation that are relevant to human health.
Steroids are important hormones in both animals and plants. Brassinosteroid is a major growth--?promoting hormone that controls a wide range of developmental and physiological activities in plants. Brassinosteroid signal transduction uses proteins that are similar to important proteins in humans, and therefore our study of brassinosteroid signaling mechanisms will lead to not only means for improving crop productivity but also knowledge that benefits human health.
|Zhu, Jia-Ying; Li, Yuyao; Cao, Dong-Mei et al. (2017) The F-box Protein KIB1 Mediates Brassinosteroid-Induced Inactivation and Degradation of GSK3-like Kinases in Arabidopsis. Mol Cell 66:648-657.e4|
|Deng, Zhiping; Wang, Zhi-Yong; Kutschera, Ulrich (2017) Seedling development in maize cv. B73 and blue light-mediated proteomic changes in the tip vs. stem of the coleoptile. Protoplasma 254:1317-1322|
|Bu, Shuo-Lei; Liu, Chao; Liu, Ning et al. (2017) Immunopurification and Mass Spectrometry Identifies Protein Phosphatase 2A (PP2A) and BIN2/GSK3 as Regulators of AKS Transcription Factors in Arabidopsis. Mol Plant 10:345-348|
|Ni, Weimin; Xu, Shou-Ling; González-Grandío, Eduardo et al. (2017) PPKs mediate direct signal transfer from phytochrome photoreceptors to transcription factor PIF3. Nat Commun 8:15236|
|Xu, Shou-Ling; Chalkley, Robert J; Maynard, Jason C et al. (2017) Proteomic analysis reveals O-GlcNAc modification on proteins with key regulatory functions in Arabidopsis. Proc Natl Acad Sci U S A 114:E1536-E1543|
|Chaiwanon, Juthamas; Garcia, Veder J; Cartwright, Heather et al. (2016) Immunophilin-like FKBP42/TWISTED DWARF1 Interacts with the Receptor Kinase BRI1 to Regulate Brassinosteroid Signaling in Arabidopsis. Mol Plant 9:593-600|
|Kutschera, Ulrich; Wang, Zhi-Yong (2016) Growth-limiting proteins in maize coleoptiles and the auxin-brassinosteroid hypothesis of mesocotyl elongation. Protoplasma 253:3-14|
|Zhang, Zhenzhen; Zhu, Jia-Ying; Roh, Jeehee et al. (2016) TOR Signaling Promotes Accumulation of BZR1 to Balance Growth with Carbon Availability in Arabidopsis. Curr Biol 26:1854-60|
|Chaiwanon, Juthamas; Wang, Wenfei; Zhu, Jia-Ying et al. (2016) Information Integration and Communication in Plant Growth Regulation. Cell 164:1257-1268|
|Wei, Chuang-Qi; Chien, Chih-Wei; Ai, Lian-Feng et al. (2016) The Arabidopsis B-box protein BZS1/BBX20 interacts with HY5 and mediates strigolactone regulation of photomorphogenesis. J Genet Genomics 43:555-563|
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