DGCR8蛋白及其mRNA的自我调控新机制研究

DGCR8, a double strand RNA binding protein, is one of the key molecules that process miRNAs. By using HITS-CLIP method, we found that DGCR8 could interact with one hairpin structure in DGCR8 mRNA coding region directly. This haipin RNA has no inhibitory effect on the expression of its host gene. When the key binding sequence was deleted, the expression level of mRNA and protein decreased. All these results imply that there is a new auto-regulation mechanism between DGCR8 protein and DGCR8 mRNA. DGCR8 protein can interact with the hairpin structure in DGCR8 mRNA coding region, lead to no cleavage of mRNA, but enhance the DGCR8 mRNA stability and improve the expression of DGCR8 protein itself. On the basis of these results, we will detect the interaction between DGCR8 protein and DGCR8 mRNA, analyze the molecular mechanism of DGCR8 auto-regulation, reveal the new function of DGCR8 enhancing mRNA stability. In addition, we will investigate the regulation effect of this hairpin RNA on DGCR8 activity. In a word, the implementation of this project will contribute to clarifing the new auto-regulation mechanism between DGCR8 protein and its mRNA, enriching the knowledge of gene expresion regulation.

双链RNA结合蛋白DGCR8是miRNA前体加工的核心分子，运用HITS-CLIP技术我们意外发现DGCR8可以与其自身mRNA编码区的一个类似于miRNA前体的发夹结构直接相互作用。但与miRNA前体不同，该发夹结构对宿主基因表达并没有抑制作用，而在缺失了DGCR8结合的核心序列后，mRNA的稳定性下降，蛋白表达降低。这提示细胞内可能存在一个DGCR8蛋白-mRNA的自我调控模式，即DGCR8通过与其自身mRNA上发夹结构的相互作用，不介导RNA切割，反而增强其稳定性，促进自身的表达。本项目拟在前期研究基础上，分析DGCR8蛋白通过与自身RNA发夹结构的相互作用，调控自身表达的分子机制,揭示DGCR8调控mRNA稳定性的新功能；同时探讨该发夹RNA对DGCR8蛋白活性的调控作用。本项目的实施将揭示DGCR8蛋白与自身mRNA的自我调控新模式，发现DGCR8的新功能，丰富对基因调控的认识。

经过四年研究，本项目发现DGCR8蛋白确实可以与其自身mRNA 2052-2113nt区域的二级结构相互作用，而且DGCR8蛋白可通过与该区域结合增强自身的表达。同时还发现RNA分子可以介导或抑制p53与其它蛋白质之间的相互作用，而hnRNPC则可通过与p53相互作用调控其表达，同时调控细胞凋亡及增殖。本项目主要发现DGCR8可与自身mRNA相互作用，并调控自身的表达，而且发现RNA分子可以调控蛋白分子之间的相互作用，从而调控蛋白质的表达。这是一种新的RNA调控模式，扩展了我们对RNA分子作用途径的认识。