HBx在HBV感染复制及致癌过程中起重要作用。我们之前的研究揭示了HBx通过其BH3结构域直接结合Bcl-2/xL，上调细胞内钙离子水平来促进HBV复制和细胞死亡。我们新近解析了HBx BH3结构域与Bcl-xL的复合物结构，并鉴定出与之相关的关键氨基酸位点。我们提出“HBx BH3结构域作为影响HBV复制及肝癌转化的潜在靶点”的假设并拟以验证。本项目拟在上述研究基础上，利用基于HepaRG细胞的HBV感染复制模型和支持HBV感染的人肝嵌合鼠模型验证这些位点及其突变体对HBx与Bcl2/xL间相互作用、诱导肝细胞毒性反应、病毒感染和复制能力的影响，并进一步基于SB转座子系统和Fah基因缺陷鼠建立HBx致肝癌模型以探讨BH3结构域在肝癌转化的作用和机制。项目预期成果将阐明HBx BH3结构域在HBV复制和肝癌转化中的作用及机制，为未来进一步发展以HBx BH3为靶点的乙肝治疗新药物奠定基础。

HBx protein plays pivotal roles in the processes of HBV infection, replication and has been implicated in the hepatocarcinogenesis. However, the essential functional domain the HBx is still not very clear. Our previous study demonstrated that the HBx interacted directly with two Bcl-2 family members, Bcl-2 and Bcl-xL through its BH3 domain to increase intracellular calcium level, thereby induced cell death and HBV replication. Recently, we determined the structural details of the complex of HBx BH3 domain and Bcl-xL by X-ray crystallography and identified the crucial amino acids which supported the interaction between BH3 domain and Bcl-xL. Based on these interesting findings, we firstly propose that the BH3 domain in the interaction of HBx and Bcl-2 is the potential target for modulating HBV replication and HCC transformation, thus we would like to prove this hypothesis. In this proposal, we plan to investigate the roles of these amino acids and their variants in the HBx-Bcl-2/xL binding, induction of hepatic cell toxicity, viral infectivity and replication in HepaRG cell model and primary human hepatocyte chimeric FRG mice which both support HBV infection. Moreover, we will establish an HBx induced HCC model in Fah-/- mice by virtue of the sleeping beauty (SB) transposon system, aiming to investigate the function and signature of the HBx BH3 domain on inducing hepatic inflammation and hepatocarcinogenesis. Our expected results will clarify the role and molecular mechanisms of HBx BH3 domain on HBV replication and hepatocarcinogenesis, which will lay solid foundations for further development of new intervening drugs targeting HBx BH3 domain for HBV therapy.