基因君官网
2015年4月4日讯 /生物谷BIOON/ –近日，著名国际学术期刊Nature在线发表了法国科学家的一项最新研究进展，他们发现在植物中miRNA的初级转录本pri-miRNA能够编码一类具有调节功能的多肽，促进miRNA积累，调节基因表达。这一研究发现了pri-miRNA的新功能，为基因调控研究开辟了新的领域，具有重大意义。
MicroRNA（miRNA）是一类具有调节作用的小RNA分子，能够通过结合和切割mRNA，抑制蛋白质翻译过程，从而特异性抑制靶向基因表达。细胞在形成成熟miRNA之前，会先转录出更大的初级转录本（pri-miRNA），但目前对pri-miRNA的功能了解较少。
研究人员发现在植物pri-miRNA中包含短的开放阅读框序列，能够编码一类具有调节功能的多肽。蒺藜苜蓿中表达的Pri-miR171b和拟南芥中表达的pri-miR165a能够产生调节性多肽，研究人员将其命名为miPEP171b和miPEP165a，研究发现这两种调节性多肽能够各自增强它们对应的成熟miRNA的积累，最终导致参与根部发育的相关靶向基因的表达下调。研究人员通过研究证明miPEP的作用机制主要是能够增加pri-miRNA的转录。
随后，他们又发现拟南芥和蒺藜苜蓿中另外5个pri-miRNA也能够编码miPEP，这表明miPEP在植物王国中广泛存在。将合成的miPEP171b和miPEP165a多肽应用于植物，能够特异性触发miR171b和miR165a的积累，导致侧根减少，并刺激主根生长，说明miPEP可能具有重要的农业应用价值。（基因宝jiyinbao.com）
Primary transcripts of microRNAs encode regulatory peptides
Dominique Lauressergues,Jean-Malo Couzigou,Hélène San Clemente,Yves Martinez, Christophe Dunand,Guillaume Bécard& Jean-Philippe Combier
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 proteins1. 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 Arabidopsis 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.