Biochemical Evidence for Translational Repression by Arabidopsis MicroRNAs
Biochemical Evidence for Translational Repression by Arabidopsis MicroRNAs
复制标题
DOI：
10.1105/tpc.108.063412
复制
发表时间：
2009-06-01
期刊：
影响因子：
11.6
通讯作者：
Robaglia, Christophe
中科院分区：
文献类型：
--
作者：
Lanet, Elodie;Delannoy, Etienne;Robaglia, Christophe
微小RNA（miRNAs）通过RNA沉默在转录后调控基因表达，这是一种在真核生物中保守的机制。主流模型认为，大多数动物miRNAs通过阻断mRNA翻译来影响基因表达，而大多数植物miRNAs则触发mRNA裂解。在这里，通过对拟南芥进行多聚核糖体分级分离，我们发现一部分成熟的miRNAs和AGO1（ARGONAUTE1）可能通过它们的mRNA靶标与多聚核糖体相关联。我们观察到在一个ago1亚效等位基因突变体中，几种不同的miRNA靶标在mRNA和蛋白质水平上的积累都增强了。相比之下，在表达黄瓜花叶病毒2b切割抑制蛋白的转基因植物中，翻译抑制持续存在，但裂解没有发生。一致地，我们发现miR168与多聚核糖体的关联在ago1中缺失，但在2b植物中得以维持，这表明翻译抑制与miRNAs和AGO1在多聚核糖体中的存在相关。这项工作为植物miRNA途径中的翻译成分提供了直接的生化证据。
MicroRNAs (miRNAs) regulate gene expression posttranscriptionally through RNA silencing, a mechanism conserved in eukaryotes. Prevailing models entail most animal miRNAs affecting gene expression by blocking mRNA translation and most plant miRNAs, triggering mRNA cleavage. Here, using polysome fractionation in Arabidopsis thaliana, we found that a portion of mature miRNAs and ARGONAUTE1 (AGO1) is associated with polysomes, likely through their mRNA target. We observed enhanced accumulation of several distinct miRNA targets at both the mRNA and protein levels in an ago1 hypomorphic mutant. By contrast, translational repression, but not cleavage, persisted in transgenic plants expressing the slicing-inhibitor 2b protein from Cucumber mosaic virus. In agreement, we found that the polysome association of miR168 was lost in ago1 but maintained in 2b plants, indicating that translational repression is correlated with the presence of miRNAs and AGO1 in polysomes. This work provides direct biochemical evidence for a translational component in the plant miRNA pathway.