Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA.
Cell. 2013 Apr 25;153(3):562-74. doi: 10.1016/j.cell.2013.04.005.
Translation inhibition is a major but poorly understood mode of action of microRNAs (miRNAs) in plants and animals. In particular, the subcellular location where this process takes place is unknown. Here, we show that the translation inhibition, but not the mRNA cleavage activity, of Arabidopsis miRNAs requires ALTERED MERISTEM PROGRAM1 (AMP1). AMP1 encodes an integral membrane protein associated with endoplasmic reticulum (ER) and ARGONAUTE1, the miRNA effector and a peripheral ER membrane protein. Large differences in polysome association of miRNA target RNAs are found between wild-type and the amp1 mutant for membrane-bound, but not total, polysomes. This, together with AMP1-independent recruitment of miRNA target transcripts to membrane fractions, shows that miRNAs inhibit the translation of target RNAs on the ER. This study demonstrates that translation inhibition is an important activity of plant miRNAs, reveals the subcellular location of this activity, and uncovers a previously unknown function of the ER.
翻译抑制是 microRNAs（miRNAs）在动植物中一种主要但尚未被充分理解的作用模式。特别是，该过程发生的亚细胞位置尚不清楚。在这里，我们表明，拟南芥 miRNA 的翻译抑制，而不是 mRNA 切割活性，需要改变分生组织程序 1（AMP1）。AMP1 编码一种与内质网（ER）相关的整合膜蛋白，以及 ARGONAUTE1，即 miRNA 效应物和外周 ER 膜蛋白。在膜结合多核糖体而非总多核糖体中，发现 miRNA 靶 RNA 的多核糖体结合存在野生型和 amp1 突变体之间的巨大差异。这与 miRNA 靶转录物在膜部分的 AMP1 独立募集一起表明，miRNAs 抑制 ER 上靶 RNA 的翻译。这项研究表明翻译抑制是植物 miRNAs 的一种重要活性，揭示了这种活性的亚细胞位置，并揭示了 ER 的一个以前未知的功能。
