REGULATION OF TBP BY HBV X ON TRANSFORMATION

描述：(改编自调查人员摘要)乙肝病毒 (乙肝病毒)是一种常见的感染源。乙肝病毒蛋白产物X已被证明是 对病毒复制是必不可少的，而且它与 慢性感染的乙肝患者发生肝细胞癌 然而，它在这些事件中扮演的角色还没有得到很好的理解。我们之前的工作是 全面定义了X反式激活RNA聚合酶I的机制 和III启动子。我们有一个有趣的发现，那就是X诱导 通过激活RAS信号转导通路来启动启动子 提高中心转录因子TATA结合的细胞水平 蛋白质(TBP)。细胞TBP的增加增加了RNA PolI和III 转录和差异调控RNAPolII启动子。我们的研究 计划将清楚地描绘X，一种致癌的RAS，如何增加细胞TBP 级别。拟议的目标将严格调查TBP中的每一项事件 最终形成TBP产物的基因表达过程。通过检查 每个过程的个人贡献，以及当X或X 或者致癌的RAS在细胞中表达，我们就会获得很好的定量 X-和致癌RAS介导的TBP增加是如何发生的。我们 有很有希望的新数据表明导致增长的关键一步 TBP是由于TBP启动子活性增加所致。因此，一个主要的焦点是 拟议的研究将考察TBP启动子如何受到X的调控 和致癌的RAS。我们将全面定义X介导的信号转导 调节TBP启动子活性的RAS下游事件。 由于X已经被证明可以转化细胞，而且RAS具有很强的致癌性，我们 也将决定TBP细胞水平的变化如何影响 细胞的转化潜力。焦点形成，在软琼脂中生长， 小鼠肿瘤形成试验将被用来评估是否直接 过表达TBP可增强转化活性或下调 它在细胞中的产生可以阻止RAS诱导的转化。使用突变体 RNAPolII或PolIII中特异缺陷的TBP蛋白 转录，我们将定义细胞基因表达的特定变化 发生在TBP过表达的细胞中，有助于转化。这些 研究承诺为我们的社会做出独特而重要的新贡献 了解HBVX蛋白和致癌RAS的功能 TBP的调节，以及它们对细胞基因活性的影响 到细胞转化。

DESCRIPTION: (Adapted from the investigator's abstract) The Hepatitis B virus (HBV) is a common infectious agent. The HBV protein product, X, has shown to be essential for viral replication, and it is strongly implicated in the development of hepatocellular carcinoma in chronically infected HBV patients, yet its role in these events is not well-understood. Our previous work has comprehensively defined the mechanism for how X transactivated RNA polymerase I and III promoters. We made the interesting discovery that X induces the promoters by activating the Ras signal transduction pathway which then increases the cellular levels of the central transcription factor, TATA-binding protein (TBP). Increases in cellular TBP augment RNA pol I and III transcription and differentially regulate RNA pol II promoters. Our research plan will clearly delineate how X, an oncogenic Ras, increase cellular TBP levels. The proposed aims will rigorously investigate each event in the TBP gene expression process that gives rise to the final TBP product. By examining the individual contribution of each process, and how it differs when either X or oncegenic Ras is expressed in cells, we will obtain a good quantitative picture of how this X- and oncogenic Ras-mediated increase in TBP occurs. We have promising new data indicating that a key step leading to the increase in TBP is due to an increase in TBP promoter activity. Therefore, a major focus of the proposed studies will be to examine how the TBP promoter is regulated by X and by oncogenic Ras. We will comprehensively define the X-mediated signaling events downstream of Ras to the promoter that modulate TBP promoter activity. Since X has been shown to transform cells, and Ras is strongly oncegenic, we will also determine how alterations in the cellular levels of TBP can affect the transformation potential of cells. Focus formation, growth in soft agar, and mouse tumorigenesis assays will be used to assess whether directly overexpressing TBP can enhance transforming activity or whether down-regulating its production in cells can prevent Ras-induced transformation. Using mutant TBP proteins that are specifically defective in RNA pol II or pol III transcription, we will define specific changes in cellular gene expression occurring in TBP-overexpressing cells that contribute to transformation. These studies promise to make unique and important new contributions to our understanding of the function of the HBV X protein and oncegenic Ras, the regulation of TBP, and their consequences on cellular gene activity that leads to cellular transformation.