Primary transcripts of microRNAs encode regulatory peptides

摘要

微RNAs(miRNAs)主要以在信使RNA层面上抑制它们目标基因的表达而为人们所知。它们是从对要大得多的"原始转录体"（pri-miRNAs)的处理而形成的。Jean-Philippe Combier及同事提供的数据表明，pri-miRNAs(至少在植物中）不仅仅是miRNA的一个来源,它们还编码起调控作用的肽（miPEPs)。而且，来自pri-miRNAs的miPEPs似乎还会增强相关的成熟miRNAs的积累，从而也增强其效应。作者演示了两种这样的肽（miPEP171b和miPEP165a)在植物根发育中所起作用。他们还识别出另外五个活性miPEPs,说明这一现象可能具有普遍性。这些发现在农业上可能会有用途，因为由研究人员所生成并引入到植物中的合成miPEP171b和miPEP165a与它们的天然对应物走的是相同的分子路径，对根的发育也有类似的效应。%MicroRNAs (miRNAs) are small regulatory RNA molecules that inhibit the expression of specific target genes by binding to and cleaving their messenger RNAs or otherwise inhibiting their translation into proteins. miRNAs are transcribed as much larger primary transcripts (pri-miRNAs), the function of which is not fully understood. Here we show that plant pri-miRNAs contain short open reading frame sequences that encode regulatory peptides. The pri-miR171b of Medicago truncatula and the pri-miR165a of Arabid-opsis thaliana produce peptides, which we term miPEP171b and miPEP165a, respectively, that enhance the accumulation of their corresponding mature miRNAs, resulting in downregulation of target genes involved in root development. The mechanism of miRNA-encoded peptide (miPEP) action involves increasing transcription of the pri-miRNA. Five other pri-miRNAs of A. thaliana and M. truncatula encode active miPEPs, suggesting that miPEPs are widespread throughout the plant kingdom. Synthetic miPEP171b and miPEP165a peptides applied to plants specifically trigger the accumulation of miR171b and miR165a, leading to reduction of lateral root development and stimulation of main root growth, respectively, suggesting that miPEPs might have agronomical applications.