3'UTR A-to-I RNA编辑位点的功能和进化

Adenosine-to-inosine (A-to-I) RNA editing, catalysed by adenosine deaminases acting on RNA (ADAR), recodes the genome-encoded information and promotes functional diversity. A plethora of editing sites has been recently identified by us and others; however, if and which editing sites are functionally important are largely unknown. Previously, we established a pioneering framework to catalog RNA editing sites using RNA sequencing data alone. By applying this framework in different organisms, we revealed a large number of editing sites. We also found that RNA editing sites are highly enriched in 3’UTR regions. Based on these observations, we propose to systematically examine the role of 3’UTR editing sites on gene regulation by combining synthetic biology, high-throughput sequencing and comparative genomics approach. We will use a high-throughput synthetic biology method to examine the effect of tens of thousands of 3’UTR editing sites on both mRNA stability and translational control in human and rhesus macaque. We will also perform RNA-seq, genome-wide RNA structure mapping and ribosome profiling experiments on wild-type and ADARs-deficient human or macaque cells to assess the global effect of RNA editing on mRNA stability and translational control. Finally, we will compare data generated from these two species to understand how functional editing sites evolve. These experiments together will allow us to understand the function and evolution of individual 3’UTR RNA editing sites.

A-to-I RNA编辑使得一个基因序列可能产生多种（两至上千种）不同的RNA，从而促进遗传信息在RNA水平的多样化。转录组测序以及转录组水平定位RNA编辑位点方法的建立揭示了RNA编辑现象的广泛性。但是这些大量新发现的RNA编辑位点的功能和进化还待阐明。我们前期的研究发现大量富集在3’UTR的RNA编辑位点。在此基础上，本项目拟利用合成生物学、大规模测序和比较基因组学等手段，揭示3’UTR RNA编辑位点的功能和进化。通过高通量功能注释3’UTR的方法研究人和猕猴中3’UTR RNA编辑位点对基因表达和翻译所造成的影响。利用RNA-seq、RNA结构谱和核糖体谱技术揭示RNA编辑对mRNA二级结构和基因表达翻译的影响。综合不同数据相互验证和研究RNA编辑位点的生物学意义。比较人和猕猴之间的RNA编辑位点的功能变化研究RNA编辑进化。通过这些研究最终揭示RNA编辑位点的功能和进化。

申请者在本项目中致力于A-to-I RNA编辑，特别是非编码区编辑的功能和进化。项目开展以来取得的主要学术进展有3项：（1）我们揭示了3’UTR的编辑位点可以调控基因表达。在分子机制上，3’UTR的编辑位点可能通过介导mRNA的降解来调控基因表达。（2）我们发现miRNA编辑在人类的多种组织中普遍存在，而在小鼠和果蝇中高水平的RNA编辑只发生在神经组织中。人类神经和非神经组织中被编辑的miRNA分别获得了两组不同的新靶基因，这些靶基因分别与认知和多种器官发育功能密切相关，暗示着miRNA的RNA编辑可能进化出人类特异的调控非神经类组织器官发育的新功能。(3)我们发现miRNA的反义链普遍表达和存在大量的编辑事件，揭示了一个新的miRNA和AT-miRNA相互作用的调控机制。在本基金的支持下，申请者以共同通讯或通讯作者在PLOS Genetics，Genome Research，Nature Structural & Molecular Biology发表论文3篇。研究成果被Science，Nature Structural & Molecular Biology撰文推荐。在本项目支持下本研究团队培养2名博士、2名硕士研究生和1名专职科研人员。我们的研究成果为接下来系统研究RNA编辑的调控和功能打下了坚实的基础。