Ding Ning, Zhang Bailong
Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China.
Front Plant Sci. 2023 Jan 19;14:1096772. doi: 10.3389/fpls.2023.1096772. eCollection 2023.
In plants, microRNAs (miRNAs) associate with ARGONAUTE (AGO) proteins and act as sequence-specific repressors of target gene expression, at the post-transcriptional level through target transcript cleavage and/or translational inhibition. MiRNAs are mainly transcribed by DNA-dependent RNA polymerase II (POL II) and processed by DICER LIKE1 (DCL1) complex into 21∼22 nucleotide (nt) long. Although the main molecular framework of miRNA biogenesis and modes of action have been established, there are still new requirements continually emerging in the recent years. The studies on the involvement factors in miRNA biogenesis indicate that miRNA biogenesis is not accomplished separately step by step, but is closely linked and dynamically regulated with each other. In this article, we will summarize the current knowledge on miRNA biogenesis, including gene transcription, primary miRNA (pri-miRNA) processing, miRNA AGO1 loading and nuclear export; and miRNA metabolism including methylation, uridylation and turnover. We will describe how miRNAs are produced and how the different steps are regulated. We hope to raise awareness that the linkage between different steps and the subcellular regulation are becoming important for the understanding of plant miRNA biogenesis and modes of action.
在植物中，微小RNA（miRNA）与AGO蛋白结合，并作为靶基因表达的序列特异性阻遏物，通过在转录后水平切割靶转录本和/或抑制翻译发挥作用。miRNA主要由DNA依赖性RNA聚合酶II（POL II）转录，并由Dicer-like1（DCL1）复合体加工成21至22个核苷酸（nt）长。尽管miRNA生物合成的主要分子框架和作用模式已经确立，但近年来仍不断有新的需求出现。对参与miRNA生物合成的因子的研究表明，miRNA生物合成并非一步一步单独完成，而是相互紧密联系且动态调控的。在本文中，我们将总结关于miRNA生物合成的现有知识，包括基因转录、初级miRNA（pri-miRNA）加工、miRNA与AGO1装载及核输出；以及miRNA代谢，包括甲基化、尿苷化和周转。我们将描述miRNA是如何产生的以及不同步骤是如何被调控的。我们希望提高人们的认识，即不同步骤之间的联系和亚细胞调控对于理解植物miRNA生物合成及作用模式正变得越来越重要。
