特异解旋酶在G-四链体RNA介导的原癌基因表达调控中的作用及机制

G-四链体（G4）RNA是2014年科学家在人类细胞中证实存在的特殊核酸结构，其中5′-UTR G4参与了众多原癌基因的表达调控，已经成为治疗癌症的新靶标。细胞中有一类高度特异的解旋酶在5′-UTR G4调控的翻译过程中发挥关键作用，并在多种癌细胞内高表达，但目前大家对这些解旋酶的认识极为初步，许多重要问题亟待解决。本项目将选择其中的DHX9作为代表，首先在单分子水平研究DHX9与G4 RNA的动态相互作用，阐明其结合与解旋G4 RNA的分子机制；然后借助探针观察DHX9在细胞内对G4 RNA的解旋，并通过NRAS原癌基因进一步探索DHX9对5′-UTR G4介导的翻译过程的调节作用。此外，本项目将从干扰解旋酶与G4 RNA互作的新角度研究和评估G4 RNA配体。本项目将揭示解旋酶与G4 RNA互作对基因表达的具体调控机制，并为理解G4 RNA与癌症的深层关系和新型靶向药物开发提供依据。

G-quadruplexes (G4s) are non-canonical nucleic acid structures formed through the stacking of Hoogsteen hydrogen bonded G-tetrads in DNA or RNA molecules. The existence of G4 RNA in human cells was confirmed by scientists in 2014. The existence of stable G4 RNA in 5′-UTR is able to repress the protein translation; therefore, it has been well recognized as a new type of anticancer drug target. The folding and unfolding of G4 RNA are precisely regulated by specialized helicases in cells, including the DEAH-Box family helicase DHX9. DHX9 is overexpressed in several types of cancer, and is also a potential therapeutic target. This project is originated from the perspective of interaction between DHX9 and G4 RNA. We will first study the dynamic interaction between DHX9 and G4 RNA at the single-molecular level, and reveal the molecular mechanism of DHX9 binding and unfolding G4 RNA. On this basis, we will further use G4 RNA probe to detect the DHX9-mediated G4 RNA unfolding directly in cells, and further explore the regulatory function of DHX9 in the 5′-UTR G4 mediated NRAS gene translation. In addition, we will also study and evaluate G4 RNA ligands from the perspective of interfering with the interaction between helicase and G4 RNA. This project will shed new light on our current understanding of the interaction between helicases and G4 RNA. This project may also provide new insights into the molecular basis of related diseases and developing new drugs.