Brassinosteroid-regulated GSK3/Shaggy-like Kinases Phosphorylate Mitogen-activated Protein (MAP) Kinase Kinases, Which Control Stomata Development in Arabidopsis thaliana
Brassinosteroid-regulated GSK3/Shaggy-like Kinases Phosphorylate Mitogen-activated Protein (MAP) Kinase Kinases, Which Control Stomata Development in Arabidopsis thaliana
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DOI：
10.1074/jbc.m112.384453
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发表时间：
2013-03-15
影响因子：
4.8
通讯作者：
Poppenberger, Brigitte
中科院分区：
文献类型：
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作者：
Khan, Mamoona;Rozhon, Wilfried;Poppenberger, Brigitte
油菜素内酯（BRs）是协调植物基本发育程序的类固醇激素。在这项研究中，我们发现除了BRs在调节细胞伸长和细胞分裂事件中的作用外，BRs还在拟南芥气孔发育过程中控制细胞命运决定。野生型拟南芥气孔分布遵循单细胞间隔规律；也就是说，相邻气孔之间至少间隔有一个铺装细胞。这一规律在BR缺失和BR信号缺失的拟南拟菜突变体中被中断，导致气孔聚集。我们证明BIN2及其同源物GSK3/Shaggy-like激酶参与BR信号传导，可以磷酸化MAPK激酶MKK4和MKK5，这是MAPK模块YODA-MKK4/5-MPK3/6的成员，控制气孔发育和模式。BIN2磷酸化了MKK4中的GSK3/Shaggy-like kinase识别基序，从而降低了MKK4对其底物MPK6的活性。在体内，我们发现MKK4和MKK5作用于BR信号的下游，因为它们的过表达挽救了BR缺乏植物的气孔模式缺陷。研究人员提出了一个模型，其中gsk3介导的MKK4和MKK5的磷酸化使BRs信号的内源性或环境信号动态整合到由YODA-MKK4/5-MPK3/6模块控制的细胞命运决定中。
Brassinosteroids (BRs) are steroid hormones that coordinate fundamental developmental programs in plants. In this study we show that in addition to the well established roles of BRs in regulating cell elongation and cell division events, BRs also govern cell fate decisions during stomata development in Arabidopsis thaliana. In wild-type A. thaliana, stomatal distribution follows the one-cell spacing rule; that is, adjacent stomata are spaced by at least one intervening pavement cell. This rule is interrupted in BR-deficient and BR signaling-deficient A. thaliana mutants, resulting in clustered stomata. We demonstrate that BIN2 and its homologues, GSK3/Shaggy-like kinases involved in BR signaling, can phosphorylate the MAPK kinases MKK4 and MKK5, which are members of the MAPK module YODA-MKK4/5-MPK3/6 that controls stomata development and patterning. BIN2 phosphorylates a GSK3/Shaggy-like kinase recognition motif in MKK4, which reduces MKK4 activity against its substrate MPK6 in vitro. In vivo we show that MKK4 and MKK5 act downstream of BR signaling because their overexpression rescued stomata patterning defects in BR-deficient plants. A model is proposed in which GSK3-mediated phosphorylation of MKK4 and MKK5 enables for a dynamic integration of endogenous or environmental cues signaled by BRs into cell fate decisions governed by the YODA-MKK4/5-MPK3/6 module.