MicroRNA介导mRNA中m6A甲基化形成的机制研究

Multiple types of nucleotide modifications can be added to eukaryotic mRNAs, among which, N6-methyladenosine (m6A) is the most abundance modification. Due to limitations of detection method, very few researches have been conducted so far to study modifications on mRNAs. Previously, we have identified that the formation of m6A on mRNAs is regulated by miRNAs in a sequence-dependent way, which revealed the novel function of miRNAs in regulating mRNA modification. Our preliminary results showed that the function of miRNAs in regulating m6A formation depends on miRNA processing enzyme Dicer. But the other key enzymes in miRNA processing and functional pathways, namely Drosha and AGO, may not involve in this process. In this project, we will integrate multiple methods of bioinformatics and experimental biology, to investigate whether Drosha involves in miRNA mediated m6A formation, to systematic identify miRNAs capable of inducing m6A modification and to characterize their features, to identify nuclear localized proteins that mediate miRNAs to execute their m6A modification functions, and to decipher the mechanism underlying the functions of miRNAs in regulating m6A. The accomplishment of this project will help to reveal the molecular mechanisms of the novel functions of miRNAs in regulating m6A formation, and shed new lights in miRNA functional studies.

真核生物mRNA上存在多种碱基修饰，其中腺嘌呤第6位氮原子上的甲基化修饰 (m6A) 是mRNA上含量最丰富的一种修饰。但以往由于检测方法的局限，关于mRNA修饰的研究还非常少。我们的前期研究发现，miRNA可以在细胞核内通过序列匹配的方式指导mRNA上m6A的形成，揭示了miRNA 在调节mRNA修饰方面的全新功能。初步的结果证明miRNA介导的m6A形成依赖于miRNA加工酶Dicer，但很可能不依赖于Drosha和AGO。本项目中，我们将整合生物信息学与实验生物学方法，明确Drosha蛋白是否参与miRNA介导的m6A的形成，系统鉴定介导m6A形成的miRNA及其特征；发现在细胞核中结合miRNA使其行使RNA甲基化调控作用的蛋白因子，阐释miRNA介导m6A形成的机理。该项目的完成将有助于揭示miRNA在调节m6A形成这一全新功能方面的分子机制，拓展miRNA功能研究的新方向。

腺嘌呤第6位氮原子上的甲基化修饰 (m6A)是真核生物mRNA上含量最丰富的一种修饰，目前已经发现m6A修饰参与生长发育、代谢与免疫、和疾病发生等多种重要生理病理过程的调控。本项目基于申请人团队前期取得的miRNA调控m6A形成这一发现，进一步研究miRNA调控m6A形成的机制。我们系统鉴定了分布在细胞核内并且表达受Dicer调控的miRNA，分析了这些miRNA在调控m6A形成方面的功能，并鉴定了可能参与miRNA介导的m6A修饰形成的蛋白。此外，本项目还研究了m6A修饰在调控小鼠小脑发育中的功能，并发现m6A修饰在调控长时记忆形成效率上发挥重要作用。项目按计划完成研究任务和考核指标，发表研究论文4篇，申请国际专利1项，并且在人才培养方面取得较好成果。