Role of Hepatitis B virus X protein in HBV replication.

肝细胞癌与慢性B型肝炎感染的关系 乙型肝炎病毒（HBV）引起了人们对了解HBV感染如何增加风险的极大兴趣。 治疗肝癌根据对感染土拨鼠肝炎病毒的土拨鼠的研究， 所有哺乳动物嗜肝DNA病毒（包括人HBV）的X蛋白（HBx）是病毒感染所必需的。 复制的也有证据表明HBx有助于HCC的发展。HBx激活许多 细胞信号级联;然而，这是如何实现的尚不清楚。大多数研究试图 确定HBx在HBV复制过程中的重要作用，并了解HBx如何调节细胞 信号传导途径，在来源于肝肿瘤的肝细胞系中进行。使用永生或 与真正的肝细胞相比，转化的肝细胞缺乏生物相关性。我们 已经证明HBx的关键活性是调节细胞钙信号传导途径。这 一项提案旨在利用原代大鼠肝细胞培养物了解HBx的关键活性，并确定 这些活动如何影响肝细胞生理学和HBV复制。AIM 1中的研究将表征 HBx激活肝细胞中钙信号通路的分子机制，以及这种激活是如何发生的。 影响HBV复制。AIM 2的研究将集中在HBx和线粒体之间的相互作用 以及这如何影响肝细胞生理学和HBV复制。AIM 3特别侧重于监管 通过单独表达或在HBV复制期间表达的HBx引起的细胞凋亡。虽然HBx的基本活动是 与转化细胞相比，肝细胞中可能保存的， 这些活性在原代肝细胞中可能不同。原代大鼠肝细胞研究的结果应 更准确地反映真实感染细胞的状态，阐明不同的HBx活性， 已经报道，并提供了一个更复杂的理解HBx在HBV复制过程中的作用。

The association between hepatocellular carcinoma (HCC) and chronic infection with the human hepatitis B virus (HBV) has generated considerable interest in understanding how infection with HBV increases the risk for liver cancer. Based on studies in woodchucks infected with the woodchuck hepatitis virus, it is assumed that the X protein (HBx) of all mammalian hepadnaviruses, including human HBV, is essential for viral replication. There is also evidence that HBx contributes to the development of HCC. HBx activates many cellular signaling cascades; however, how this is accomplished is unclear. Most studies that sought to identify the essential role of HBx during HBV replication, and understand how HBx regulates cellular signaling pathways, were performed in liver cell lines derived from liver tumors. The use of immortalized or transformed hepatocytes suffers from its lack of biological relevance compared to authentic hepatocytes. We have demonstrated that a key activity of HBx is regulation of cellular calcium signaling pathways. This proposal aims to understand key activities of HBx using cultures of primary rat hepatocytes and to determine how these activities influence hepatocyte physiology and HBV replication. Studies in AIM 1 will characterize the molecular mechanism of HBx activation of calcium signaling pathways in hepatocytes and how this influences HBV replication. Studies in AIM 2 will focus on the interaction between HBx and mitochondria and how this impacts hepatocyte physiology and HBV replication. AIM 3 specifically focuses on regulation of apoptosis by HBx expressed alone or during HBV replication. Although the fundamental activities of HBx are likely preserved in hepatocytes as compared to transformed cells, the magnitude, duration and complexity of these activities may differ in primary hepatocytes. Result from studies in primary rat hepatocytes should more accurately reflect the state of an authentic infected cell, clarify the disparate HBx activites that have been reported, and provide a more sophisticated understanding of the role of HBx during HBV replication.