研究DNA5'端flap结构特异性宿主DNA修复酶在HBV-CCCDNA形成中的作用机制

HBV-CCCDNA是HBV持续性复制的主要原因之一，目前尚无靶向CCCDNA的抗HBV药物。因此了解CCCDNA的形成机制对控制和治愈HBV感染有重大意义。由RCDNA至CCCDNA转变过程中，剪切RCDNA的5’端flap结构是关键步骤，需要多种宿主DNA修复酶的参与。已知宿主flap endonuclease 1(FEN-1)有此功能，并在体外细胞实验显示,FEN-1基因沉默可减少CCCDNA形成，但不能完全抑制。与FEN-1类似，Human exonuclease 1(hEXO1)也可以剪切DNA 5’端flap结构，而且在剪切的方式上更有利于CCCDNA的形成。但hEXO1在CCCDNA形成中的作用机制尚不明确, 且未见相关研究报道。本课题拟研究hEXO1以及其与FEN-1和其他宿主DNA修复酶在CCCDNA形成中的协同作用，探究CCCDNA形成机制。

HBV CCCDNA is one of reasons of persistent HBV infection, and currently, no anti-HBV drug is available to eliminate them. HBV RCDNA is considered as the precursor of CCCDNA and digestion of RC DNA 5’flap structure is a key step in conversion of RCDNA to CCCDNA. Recently, flap endonuclease 1(FEN-1) have been shown to remove the flap structure in vitro, and reduction of FEN-1 gene expression could reduce, but not completely, the production of CCCDNA. Human exonuclease 1(hEXO1) is an another host DNA repair enzyme that can remove the flap structure and, theoretically, hEXO1 is more suitable than FEN-1 for HBV CCCDNA formation basis on its unique digestion mode in removal of flap structure. So far, the hEXO1 have not been studied in HBV CCCDNA formation yet. Thus, the proposal here is to explore the role of hEXO1 as well as other DNA repair enzymes in CCCDNA formation.