FEN1在经典非同源末端连接修复通路中的作用机制研究

深入研究错综复杂的DNA损伤修复通路及相应参与蛋白在具体通路中的功能及作用机制，不仅有助于完善对DNA修复系统的认知、探究肿瘤形成的诱因，还将为肿瘤耐药性问题的解决、肿瘤个体化治疗方案的设计提供坚实的理论基础。结构特异性核酸酶FEN1在DNA复制和修复过程中起重要作用，据报道，FEN1参与BER及AEE修复通路。FEN1在c-NHEJ修复通路中也具有潜在功能，但具体的作用方式及机制尚不明确。前期研究中，我们发现FEN1缺失细胞株在DNA发生双链断裂损伤后生存率降低。同时，FEN1与c-NHEJ修复通路中的核心蛋白KU70、RECQL5相互作用。结构拟合分析发现FEN1的C端R320~E338区域与KU70蛋白形成结合区域。接下来，我们拟构建FEN1各种突变体，设计体内及体外实验检测c-NHEJ修复通路的缺陷情况及相应细胞表型，以期阐明FEN1在c-NHEJ修复通路中的作用机制。

Fully understanding the function and mechanism of complicated DNA damage repair pathways and participants is not only good for consummating the knowledge of DNA repair system and studying the causes of oncogenesis, but it is also helpful for solving problems like drug resistance in cancer, and designing personalized therapy strategies for cancer patients. As a structure specific nuclease, FEN1 is vital in DNA replication and DNA repair progress. So far, FEN1 is clearly described in BER and AEE repair pathways. FEN1 is also believed as a participant in c-NHEJ repair pathway, however, what is the specific function and mechanism is still unknown. Our preliminary data show that the survival rate of 293T cell line without FEN1 expression was decreased after DNA double strand break induction. Also, FEN1 could bind NHEJ pathway core components like KU70 and RECQL5 after CPT treatment. Based on the structure analysis, we found that the C terminal of FEN1 (R320~E338) could directly bind KU70 protein. Next, we plan to construct FEN1 mutants, design in vitro and in vivo experiments, to detect c-NHEJ repair efficiencies and relevant cellular phenotypes.