Regulation of the Arabidopsis GSK3-like Kinase BRASSINOSTEROID-INSENSITIVE 2 through Proteasome-Mediated Protein Degradation
Regulation of the Arabidopsis GSK3-like Kinase BRASSINOSTEROID-INSENSITIVE 2 through Proteasome-Mediated Protein Degradation作者机构：Department of Molecular Cellular and Development Biology University of Michigan Ann Arbor MI 48109-1048 USA Present address: Howard Hughes Medical Institute Department of Molecular Cell and Developmental Biology University of California-Los AngelesLos Angeles CA g0095 USA
出 版 物：《Molecular Plant》 (分子植物（英文版）)
年 卷 期：2008年第1卷第2期
页 面：338-346页
核心收录：
学科分类：0710[理学-生物学] 071010[理学-生物化学与分子生物学] 081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 09[农学] 071007[理学-遗传学] 0901[农学-作物学] 090102[农学-作物遗传育种]
基 金：National Institutes of Health, NIH National Institute of General Medical Sciences, NIGMS, (R01GM060519)
主 题：.Regulates brassinosteroid BR signaling Arabidopsis GSK BR receptor
摘 要：Glycogen synthase kinase 3 （GSK3） is a unique serine/threonine kinase that is implicated in a variety of cellular processes and is regulated by phosphorylation or protein-protein interaction in animal cells. BIN2 is an Arabidopsis GSK3- like kinase that negatively regulates brassinosteroid （BR） signaling. Genetic studies suggested that BIN2 is inhibited in response to BR perception at the cell surface to relieve its inhibitory effects on downstream targets; however, little is known about biochemical mechanisms of its inhibition. Here, we show that BIN2 is regulated by proteasome-mediated protein degradation. Exogenous application of a BR biosynthesis inhibitor and an active BR increased and decreased the amount of BIN2 proteins, respectively. Interestingly, the gain-of-function bin2-1 mutation significantly stabilizes BIN2, making it unresponsive to BR-induced BIN2 depletion. Exogenous application of different plant growth hormones revealed that BIN2 depletion is specifically induced by BR through a functional BR receptor, while treatment of a protea- some inhibitor, MG132, not only prevented the BR-induced BIN2 depletion but also nullified the inhibitory effect of BR on the BIN2 kinase activity. Taken together, our results strongly suggest that proteasome-mediated protein degradation constitutes an important regulatory mechanism for restricting the BIN2 activity.
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