TRANSPORTIN1 Promotes the Association of MicroRNA with ARGONAUTE1 in Arabidopsis
TRANSPORTIN1 Promotes the Association of MicroRNA with ARGONAUTE1 in Arabidopsis
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DOI：
10.1105/tpc.16.00384
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发表时间：
2016-10-01
期刊：
影响因子：
11.6
通讯作者：
Qi, Yijun
中科院分区：
文献类型：
--
作者：
Cui, Yuwei;Fang, Xiaofeng;Qi, Yijun
在拟南芥中，microRNA（miRNAs）主要装载到ARGONAUTE 1（AGO 1）中以转录后调节基因表达。我们以前发现，增强的miRNA活性1（EMA 1），一个输入β家族蛋白，负调控miRNA加载到AGO 1。在这项研究中，通过ema 1的抑制筛选，我们确定了另一个输入蛋白B蛋白，TRANSPORTIN 1（TRN 1），作为miRNA途径的调控成分。TRN 1的突变并没有减少miRNA的积累，但它损害了miRNA的活性。我们发现TRN 1与AGO 1相互作用。TRN 1的货物识别所需的三个保守残基的突变降低了其与AGO 1的相互作用，并损害了其调节miRNA活性的功能。有趣的是，TRN 1功能障碍并没有改变miRNA和AGO 1的细胞质-核分布，但减少了与AGO 1相关的miRNA的量。这些结果表明TRN 1通过促进miRNA与AGO 1的结合来正向调节miRNA活性，并且它们揭示了两种importin B家族蛋白在miRNA加载中的相反作用。
In Arabidopsis thaliana, microRNAs (miRNAs) are mainly loaded into ARGONAUTE1 (AGO1) to posttranscriptionally regulate gene expression. We previously found that ENHANCED MiRNA ACTIVITY1 (EMA1), an importin beta family protein, negatively regulates miRNA loading into AGO1. In this study, through a suppressor screening of ema1, we identified another importin b protein, TRANSPORTIN1 (TRN1), as a regulatory component in the miRNA pathway. Mutation of TRN1 did not reduce miRNA accumulation, but it impaired miRNA activity. We found that TRN1 interacted with AGO1. Mutation of the three conserved residues required for cargo recognition of TRN1 reduced its interaction with AGO1 and compromised its function in regulating miRNA activity. Intriguingly, TRN1 dysfunction did not change the cytoplasmic-nuclear distribution of miRNAs and AGO1 but reduced the amount of miRNAs associated with AGO1. These results indicate that TRN1 positively regulates miRNA activity by promoting the association of miRNAs with AGO1, and they reveal opposing roles of two importin b family proteins in miRNA loading.