REGULATION OF TBP BY HBV X ON TRANSFORMATION

描述：（改编自研究者摘要）B型肝炎病毒 (HBV)是一种常见的传染源HBV蛋白产物X已被证明是 它是病毒复制所必需的，它与病毒的复制密切相关。 慢性感染HBV患者发生肝细胞癌， 然而，它在这些事件中的作用并没有得到很好的理解。我们之前的工作 全面定义了X如何反式激活RNA聚合酶I的机制， 和III启动子。我们有了一个有趣的发现，X诱导了 启动子通过激活Ras信号转导途径， 增加中央转录因子TATA结合的细胞水平 蛋白（TBP）。细胞TBP增加增加RNA聚合酶I和III 转录和差异调节RNA pol II启动子。我们的研究 计划将清楚地描述X，一种致癌Ras，如何增加细胞TBP 程度.拟议的目标将严格调查TBP中的每个事件 产生最终TBP产物的基因表达过程。通过检查 每个过程的单独贡献，以及当X 或一旦Ras在细胞中表达，我们将获得良好的定量结果。 这张图显示了X和致癌Ras介导的TBP增加是如何发生的。我们 有令人鼓舞的新数据表明，一个关键步骤，导致增加， TBP是由于TBP启动子活性的增加。因此， 拟议的研究将是检查TBP启动子是如何被X调控的， 和致癌Ras。我们将全面定义X介导的信号传导 Ras下游的事件到调节TBP启动子活性的启动子。 由于X已被证明可以转化细胞，而Ras是强烈的一次基因，我们 还将确定TBP细胞水平的改变如何影响 细胞的转化潜力。病灶形成，在软琼脂中生长， 小鼠肿瘤发生试验将用于评估是否直接 过表达TBP可以增强转化活性，或者是否下调 其在细胞中的产生可防止Ras诱导的转化。采用突变体 RNA pol II或pol III特异性缺陷的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过度表达的细胞中，有助于转化。这些 研究承诺作出独特和重要的新贡献，我们的 了解HBV X蛋白和一次基因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.