宿主因子DHX9通过消除病毒转录产物R-loop促进HBV复制的分子机制研究

现有的抗病毒策略未能彻底清除乙型肝炎病毒(HBV)，寻找和鉴定有效抗HBV的新靶点是HBV基础研究的难点和热点。最近研究发现，宿主因子DEAH-box RNA解旋酶9(DHX9)缺失会引发R环(R-loop)累积，调控多种病毒的复制。我们前期研究发现，HBx抑制DHX9经泛素-蛋白酶体途径的降解，上调DHX9水平；DHX9在HBV RNA转录后环节调控HBV复制。我们推测DHX9可能通过消除转录产物R-loop调控HBV复制，可作为抗HBV的潜在靶点。本项目将以“细胞-动物-临床样本”为研究模型，采用分子病毒学、细胞生物学等多学科手段，明确DHX9对HBV复制的影响；研究DHX9对病毒转录产物R环的作用；探讨DHX9对pgRNA转录后从cccDNA上解离和核质转运的影响；评价DHX9解旋酶活性的病毒学功能。本项目的研究结果可为临床上开发乙肝防治的新策略提供理论依据。

Currently, there are no effective antiviral strategies to eliminate hepatitis B virus (HBV) completely. It is a hotspot to screen and identify new targets for effectively control HBV infection in HBV basic research field. Recently, it has been found that depletion of the host factor DEAH-box RNA helicase 9 (DHX9) triggers R-loop accumulation and regulates the replication of certain viruses. We previously found that HBx upregulated DHX9 levels by inhibiting the degradation of DHX9 via the ubiquitin-proteasome pathway; DHX9 regulated HBV replication at the post-transcriptional process of HBV RNA. We hypothesize that DHX9 may regulate HBV replication by resolving the R-loop, which may serve as a potential target against HBV. In this study, we will firstly clarify the effect of DHX9 on HBV replication. Secondly, we will study the effect of DHX9 on the R-loop of viral transcripts. Thirdly, we will investigate the effect of DHX9 on the dissociation of pgRNA from cccDNA and pgRNA transportation. Finally, we will evaluate the helicase activity of DHX9 on HBV replication. Collectively, this study will be expected to offer a new strategy for the prevention and treatment of hepatitis B in clinical practice.