HEPATITIS B VIRUS AND HEPATOCELLULAR CARCINOMA

慢性感染乙肝病毒是一个重要的危险因素 在肝细胞癌的发生发展中起重要作用。我们提出了一个模型 关于乙肝病毒在肝癌中的作用，从我们的论证中得出 反式激活因子X蛋白(HBX)与XAP-1/UV-DDB细胞相互作用 参与核苷酸切除修复(NER)的蛋白质，以及HBx 表达抑制正常的NER。我们假设HBX与XAP-1结合 为乙肝病毒的生命周期提供功能，并使蛋白质相互作用 使DNA修复瘫痪，并在不经意间促进了 肝细胞癌。我们将使用几种方法测试该模型， 具体目的如下：(1)HBx对细胞DNA修复的影响。这个 负责抑制NER的HBx结构域将使用 突变的HBx蛋白。色素性干皮病患者的成纤维细胞 将被用于确定HBx是否通过一种 参与XAP-1的通路。HBX对突变频率的影响将是 利用我们的HBVX转基因小鼠进行了测试。HBX有可能 干扰DNA修复需要改变P53介导的途径 将会被检查。(2)功能相互作用的研究 肝脏细胞XAP-1和HBx蛋白的研究。小鼠 XAP-1将被克隆。细胞DNA修复分析将测量功能 HBx-XAP-1蛋白在肝脏内相互作用对HBx的影响 转基因小鼠。HBx表达在肝再生中的作用 将会受到考验。(3)DNA修复蛋白XAP-1作用的确定 在乙肝病毒的生命周期中。XAP-1在乙肝病毒部分修复中的作用 将对双链DNA基因组进行测试。一组HBx突变蛋白 将用于调查HBX对XAP-1的要求 激活。 拟议的计划建立在我们的乙肝相关肝细胞癌模型的基础上，并建议 一种间接作用于人肿瘤病毒的新作用机制 作为乙肝病毒。这些实验将为了解乙肝病毒对人类健康的影响提供新的见解。 肝细胞、病毒复制和肝细胞癌的发展。

Chronic infection with hepatitis B virus (HBV) is an important risk factor in the development of hepatocellular carcinoma (HCC). We present a model for the role of HBV in HCC, derived from our demonstration that the HBV transactivator X protein (HBx) interacts with XAP-1/UV-DDB, a cellular protein involved in nucleotide excision repair (NER), and that HBx expression inhibits normal NER. We hypothesize that HBx binds XAP-1 to provide a function to the HBV life cycle, and that the protein interaction cripples DNA repair and inadvertently contributes to the development of HCC. We will test the model utilizing several approaches and the following specific aims: (1) Effect of HBx on cellular DNA repair. The domains of HBx responsible for inhibition of NER will be mapped using mutant HBx proteins. Fibroblasts from Xeroderma pigmentosum (XP) patients will be used to determine whether HBx inhibits DNA synthesis through a pathway involving XAP-1. The effect of HBx on mutation frequency will be tested utilizing our HBV X transgenic mice. The possibility that HBx interference of DNA repair requires alteration of a p53-mediated pathway will be examined. (2) Investigation of functional interactions between cellular XAP-1 and HBx proteins in the liver using a mouse model. Murine XAP-1 will be cloned. Cellular DNA repair assays will measure functional effects of HBx-XAP-1 protein interactions within the livers of HBV X transgenic mice. The effect of HBx expression during liver regeneration will be tested. (3) Determination of a role for DNA repair protein XAP-1 in the HBV life cycle. A role for XAP-1 in the repair of the HBV partial double-stranded DNA genome will be tested. A panel of HBx mutant proteins will be used to investigate the requirement for XAP-1 in HBx transactivation. The proposed program builds on our model of HBV-related HCC and suggests a novel mechanism of action for indirect-acting human tumor viruses such as HBV. The experiments will provide new insights into HBV effects on hepatocytes, viral replication, and the development of HCC.