Both plants and animals use steroids as signaling molecules to regulate growth and development. While animals often use nuclear receptors for the perception and signal transduction of their steroid hormones, plants rely on cell surface receptors for steroid detection and a phosphorylation cascade to relay the brassinosteroid (BR) signals into the nucleus. Over the last several years, several key regulators of BR signaling have been identified, including BRI1 and BAK1, 2 interacting receptor kinases that function together to mediate steroid perception at the cell surface, BIN2, a GSK3-like kinase that negatively regulates the intracellular transduction of the BR signals, BSU1, a nuclear-localized protein phosphatase that antagonizes the action of BIN2, BES1 and BZR1, 2 BIN2 substrates that control the expression of many BR-responsive genes in the nucleus. Despite these findings, our knowledge on the signaling mechanism of the plant steroid hormones is rather limited. The long-term goal of our research is to delineate the entire plant steroid signaling pathway, and the current proposal is designed to fill 2 main gaps in our current knowledge of the BR signaling mechanism and identify additional regulators of the pathway. A combinatory approach of biochemistry, genetics, and molecular biology, including protein purification, yeast 2-hybrid method, chemical genetics, and genetic interactive screens, will be used 1) To determine how the BRI1-containing BR receptor transmits the plant steroid signals into plant cells, 2) To clone novel BRI1 suppressor genes and investigate the physiological functions of their genes products, 3) To study the biochemical mechanism by which the BIN2 GSK3 kinase is regulated by BRs, and 4) To identify key regulators of the BR-activated BIN2 regulatory mechanism. The successful execution of this proposal will significantly increase our understanding of the plant steroid signaling mechanism, eventually leading to new strategies to improve crop quality and productivity. Given the ubiquity of the GSK3 kinase and the existence of membrane-initiated animal steroid signaling, the discoveries resulted from this proposal may lead to the elucidation of new features of GSK3 regulation and identification of new regulators of steroid action in humans.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM060519-08
Application #
7255407
Study Section
Cellular Signaling and Dynamics Study Section (CSD)
Program Officer
Anderson, James J
Project Start
2000-01-01
Project End
2009-06-30
Budget Start
2007-07-01
Budget End
2008-06-30
Support Year
8
Fiscal Year
2007
Total Cost
$294,684
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Liu, Yidan; Li, Jianming (2013) A conserved basic residue cluster is essential for the protein quality control function of the Arabidopsis calreticulin 3. Plant Signal Behav 8:e23864
Liu, Yidan; Li, Jianming (2013) An in vivo investigation of amino acid residues critical for the lectin function of Arabidopsis calreticulin 3. Mol Plant 6:985-7
Su, Wei; Liu, Yidan; Xia, Yang et al. (2012) The Arabidopsis homolog of the mammalian OS-9 protein plays a key role in the endoplasmic reticulum-associated degradation of misfolded receptor-like kinases. Mol Plant 5:929-40
Hong, Zhi; Kajiura, Hiroyuki; Su, Wei et al. (2012) Evolutionarily conserved glycan signal to degrade aberrant brassinosteroid receptors in Arabidopsis. Proc Natl Acad Sci U S A 109:11437-42
Li, Jianming (2011) Direct involvement of leucine-rich repeats in assembling ligand-triggered receptor-coreceptor complexes. Proc Natl Acad Sci U S A 108:8073-4
Shang, Yun; Lee, Myeong Min; Li, Jianming et al. (2011) Characterization of cp3 reveals a new bri1 allele, bri1-120, and the importance of the LRR domain of BRI1 mediating BR signaling. BMC Plant Biol 11:8
Su, Wei; Liu, Yidan; Xia, Yang et al. (2011) Conserved endoplasmic reticulum-associated degradation system to eliminate mutated receptor-like kinases in Arabidopsis. Proc Natl Acad Sci U S A 108:870-5
Kang, Bin; Wang, Hao; Nam, Kyoung Hee et al. (2010) Activation-tagged suppressors of a weak brassinosteroid receptor mutant. Mol Plant 3:260-8
Peng, Peng; Zhao, Jun; Zhu, Yongyou et al. (2010) A direct docking mechanism for a plant GSK3-like kinase to phosphorylate its substrates. J Biol Chem 285:24646-53
Li, Jianming (2010) Regulation of the nuclear activities of brassinosteroid signaling. Curr Opin Plant Biol 13:540-7

Showing the most recent 10 out of 26 publications