哺乳动物中miRNA抑制作用的分子机制及调控网络的演化规律

MicroRNA(miRNA) are small non-coding RNAs that participated in many important biological processes. In this study, we aim to address several fundamental questions related to the biological mechanisms and functional significance of miRNA regulation. We aim to pursue the following questions: 1) General principle of miRNA:target recognition. 2) The molecular mechanisms of the regulation of miRNA on the target genes: degradation of target mRNAs or inhibition of translation. 3) The evolutionary patterns of miRNA:target pairing and the driving forces underlying the evolution of miRNA:target pairing patterns. 4) Functional consequences of miRNA regulation on the stabilities and evolvability of host transcriptome and translatome. 5) Impact of miRNA regulatory variation in on human adaptive evolution and diseases. We will integrate the state-of-the-arts miRNA target prediction algorithms in mammals and conducted evolutionary analysis on currently annotated miRNA and the target sites by comparing genomes of 100 vertebrate species all well as by surveying the genetic variation determined in the 1000 Human Genomes Project. Our efforts will greatly deepen our understanding of the general principle of miRNA:target recognition. We will also integrate our evolutionary genomic analysis with function genomic assays. We will treat cells of different mammalian species with miRNA transfection, knock-down, CRISPR/Cas-9 genome editing technique, and then we will deep sequence the cells under various conditions with functional genomic techniques such as miRNA-Seq, mRNA-Seq, DMS-Seq and Ribo-Seq to profile miRNAs, mRNA transcriptome and translatomes. By integrating information obtained in this study, we will be able to determine whether miRNA regulating their target genes by mRNA degradation or by translational inhibition. Our results will greatly add to our knowledge of general principles of miRNA regulation. Our study will also offer comprehensive information on the role of natural selection on miRNA regulation system, and provide important insights on mechanisms underlying human evolution and disease.

miRNA参与调控许多生命过程，具有重要的生物学功能。本研究将利用整合基因组学方法探讨miRNA生物学的一些未知基本问题：1) miRNA对靶mRNA识别的一般规律；2) miRNA对靶基因抑制作用的分子机制；3) miRNA和靶mRNA结合的演化规律以及自然选择的作用机制；4) miRNA调控对物种转录组及翻译组演化的内在驱动作用；5) miRNA调控系统变异对人类适应性演化和疾病发生的影响。本研究将整合miRNA靶基因多种预测算法，结合演化生物学分析和功能基因组学研究，以哺乳动物细胞系为实验对象，结合CRISPR/Cas9、miRNA-Seq、mRNA-Seq和Ribo-Seq等最新发展出的组学技术，在系统生物学的层面上探究哺乳动物中miRNA抑制作用的分子机制及miRNA调控网络的演化规律。研究结果有助于深入理解自然选择在生命过程中的作用,为人类演化和疾病的发生机制提供理论基础。

miRNA是生物体内源表达的一类长约22碱基的非编码小RNA，广泛参与动植物的生命过程。miRNA通过种子序列互补配对的方式识别靶基因mRNA并调控其表达。由于这种较短的配对方式，一种miRNA通常有上百个靶基因，一个靶基因也可以同时被多个miRNA调控。这种“多对多”的调控机制决定了 miRNA：mRNA相互作用调控网络的复杂性。那么miRNA是如何起源和进化的呢？本项目的主要研究目标是从组学水平上揭示动物miRNA和靶位点的进化驱动和作用规律。