MicroRNAs Inhibit the Translation of Target mRNAs on the Endoplasmic Reticulum in Arabidopsis

• Published in: Cell Vol. 153; no. 3; pp. 562 - 574
• Main Authors: Li, Shengben, Liu, Lin, Zhuang, Xiaohong, Yu, Yu, Liu, Xigang, Cui, Xia, Ji, Lijuan, Pan, Zhiqiang, Cao, Xiaofeng, Mo, Beixin, Zhang, Fuchun, Raikhel, Natasha, Jiang, Liwen, Chen, Xuemei
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 25.04.2013
• Subjects: animals; Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Carboxypeptidases - genetics; Carboxypeptidases - metabolism; endoplasmic reticulum; Endoplasmic Reticulum - metabolism; Genetic Pleiotropy; mechanism of action; membrane proteins; meristems; messenger RNA; microRNA; MicroRNAs - metabolism; mutants; Mutation; plants (botany); polyribosomes; Polyribosomes - metabolism; Protein Biosynthesis; RNA, Messenger - metabolism; RNA, Plant - metabolism; translation (genetics)
• ISSN: 0092-8674; 1097-4172; 1097-4172
• 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. [Display omitted] [Display omitted] •miRNA-mediated translation inhibition, but not translation in general, requires AMP1•AMP1 is dispensable for miRNA-mediated target RNA cleavage•AMP1 is an integral membrane protein that is localized to the rough ER•AMP1 inhibits the loading of miRNA target transcripts onto membrane-bound polysomes The integral ER membrane protein AMP1 is required for translational repression of miRNA target transcripts, indicating that the ER is an important locus of translational repression.