摘要
Translational repression is a conserved mechanism in microRNA(miRNA)-guided gene silencing.In Arabidopsis,ARGONAUTE1(AGO1),the major miRNA effector,localizes in the cytoplasm for mRNA cleavage and at the endoplasmic reticulum(ER)for translational repression of target genes.However,the mechanism underlying miRNA-mediated translational repression is poorly understood.In particular,how the subcellular partitioning of AGO1 is regulated is largely unexplored.Here,we show that the plant hormone brassinosteroids(BRs)inhibit miRNA-mediated translational repression by negatively regulating the distribution of AGO1 at the ER in Arabidopsis thaliana.We show that the protein levels rather than the transcript levels of miRNA target genes were reduced in BR-deficient mutants but increased under BR treatments.The localization of AGO1 at the ER was significantly decreased under BR treatments while it was increased in the BR-deficient mutants.Moreover,ROTUNDIFOLIA3(ROT3),an enzyme involved in BR biosynthesis,co-localizes with AGO1 at the ER and interacts with AGO1 in a GW motif-dependent manner.Complementation analysis showed that the AGO1-ROT3 interaction is necessary for the function of ROT3.Our findings provide new clues to understand how miRNA-mediated gene silencing is regulated by plant endogenous hormones.
基金
We are grateful to Professors Yijun Qi for providing the AGO1p::GFP-AGO1 seeds,Xuelu Wang for providing the 35S::BKI1-YFP seeds,Jianxiang Liu for providing the 35S::ER-mCherry plasmid,Hong Ma for providing theTOE1-Myc and mTOE1-Myc seeds,Xuemei Chen for providing the 35S::YFP-AGO1 plasmid,Shengben Li for providing the CSD2-HA and mCSD2-HA seeds,Fang Chang for providing the bri1-5 seeds,and Jinzhong Lin for providing ultracentrifuge equipment and technical guidance.This work was supported by grants of the National Natural Science Foundation of China(32025005,31830045,M-0398).
