The PP2A Regulatory Subunit Tap46, a Component of the TOR Signaling Pathway, Modulates Growth and Metabolism in Plants
The PP2A Regulatory Subunit Tap46, a Component of the TOR Signaling Pathway, Modulates Growth and Metabolism in Plants
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DOI：
10.1105/tpc.110.074005
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发表时间：
2011-01-01
期刊：
影响因子：
11.6
通讯作者：
Pai, Hyun-Sook
中科院分区：
文献类型：
--
作者：
Ahn, Chang Sook;Han, Jeong-A;Pai, Hyun-Sook
Tap 42/α 4是蛋白磷酸酶2A的调节亚基，是雷帕霉素（TOR）蛋白激酶靶点的下游效应子，其在酵母和哺乳动物中与营养和环境条件协调调节细胞生长。在这项研究中，我们的特点是植物Tap 46的功能和磷酸酶调节。Tap 46的耗尽导致生长停滞和急性植物死亡，具有程序性细胞死亡的形态学标记。Tap 46与PP 2A和PP 2A样磷酸酶PP 4和PP 6相互作用。Tap 46沉默以类似于TOR沉默的时间依赖性方式调节细胞PP 2A活性。免疫沉淀全长和缺失形式的拟南芥TOR磷酸化重组Tap 46蛋白在体外，支持Tap 46和TOR之间的功能连接。Tap 46的缺失再现了TOR失活的特征表型，例如对整体翻译的显著抑制以及自噬和氮动员的激活，表明Tap 46可能在控制这些过程中充当TOR信号传导的正效应子。此外，烟草（Nicotiana tabacum）BY-2细胞中的Tap 46沉默导致后期染色质桥形成，表明其在姐妹染色单体分离中的作用。这些发现表明，Tap 46与相关的磷酸酶一起，作为TOR信号通路的一个组成部分，在植物生长和发育中起着至关重要的作用。
Tap42/alpha 4, a regulatory subunit of protein phosphatase 2A, is a downstream effector of the target of rapamycin (TOR) protein kinase, which regulates cell growth in coordination with nutrient and environmental conditions in yeast and mammals. In this study, we characterized the functions and phosphatase regulation of plant Tap46. Depletion of Tap46 resulted in growth arrest and acute plant death with morphological markers of programmed cell death. Tap46 interacted with PP2A and PP2A-like phosphatases PP4 and PP6. Tap46 silencing modulated cellular PP2A activities in a time-dependent fashion similar to TOR silencing. Immunoprecipitated full-length and deletion forms of Arabidopsis thaliana TOR phosphorylated recombinant Tap46 protein in vitro, supporting a functional link between Tap46 and TOR. Tap46 depletion reproduced the signature phenotypes of TOR inactivation, such as dramatic repression of global translation and activation of autophagy and nitrogen mobilization, indicating that Tap46 may act as a positive effector of TOR signaling in controlling those processes. Additionally, Tap46 silencing in tobacco (Nicotiana tabacum) BY-2 cells caused chromatin bridge formation at anaphase, indicating its role in sister chromatid segregation. These findings suggest that Tap46, in conjunction with associated phosphatases, plays an essential role in plant growth and development as a component of the TOR signaling pathway.