CONSEQUENCE OF HBV ACTIVATION OF RAS ON GENE EXPRESSION

描述：（改编自研究者摘要）B型肝炎 乙型肝炎病毒是一种感染超过3亿人的病原体 世界范围内。 慢性感染可导致肝坏死和肝细胞 carcinoma. HBV基因产物之一，X蛋白，反式激活 大量的细胞和病毒基因，但这种机制， 发生的事情仍然不被理解。 令人信服的证据支持这样一种观点， X蛋白在建立感染中具有关键作用， 在肝细胞癌发展中的作用。 因此， 这种蛋白质在细胞基因反式激活中的功能是 这对我们理解X在发病机制中的作用至关重要。 的 研究人员最近证明，X介导了 TATA结合蛋白（TBP）的细胞水平，TBP是一种参与 所有细胞基因的转录，这种蛋白质是限制， RNA聚合酶III基因的表达。 X介导的RNA聚合酶的增加 III基因表达和TBP依赖于细胞的X-激活， 蛋白激酶 研究者的目的是确定信号通路 以及这一事件对基因活性和TBP的影响 程度. 拟议的研究将确定：（1）在什么水平X调节 TBP的细胞增加;（2）是否X介导的事件都是 依赖于Ras信号转导通路的激活;（3） X是否激活Sos-Grb 2复合物，以及这是否是必要的， 基因诱导;以及（4）RNA pol III基因诱导和增加是否 在细胞中，TBP仅通过激活信号蛋白介导。 拟议的研究将全面评估 RNA pol III基因的X-激活，X-介导的TBP增加， 激活Ras。调查人员还将检查X是否能激活 RNA pol I基因表达。 这些结果可以证明，首先， 时间，一个全新的一类细胞基因，是由X。如果是则 研究者还将确定X诱导是否也依赖于 Ras激活和TBP水平升高。 拟议的实验将 使用大鼠1细胞和/或果蝇S-2细胞进行， 瞬时转染或遗传改变以表达表达载体 X或其他基因。 这些研究的目标可能是确定 X蛋白的一个关键功能是允许HBV侵入细胞 转录机制，并最终改变的生长特性， cell. 这些基础研究将直接影响HBV感染者的治疗 患者 随着许多新的抗Ras治疗剂的开发， 调查，这些研究可以为潜在的新用途开辟道路。 这些化合物：通过抑制X介导的Ras活化， 慢性HBV感染者的发病机制。

DESCRIPTION: (adapted from the investigator's abstract) The hepatitis B virus (HBV) is an infectious agent affecting over 300 million people world-wide. Chronic infection can lead to liver necrosis and hepatocellular carcinoma. One of the HBV gene products, the X protein, transactivates a large number of cellular and viral genes, yet the mechanism by which this occurs is still not understood. Compelling evidence supports the view that the X protein has a critical role in establishing infection and a direct role in the development of hepatocellular carcinoma. Therefore, uncovering the function of this protein in the transactivation of cellular genes is critical to our understanding the role of X in pathogenesis. The investigator has recently demonstrated that X mediates an increase in the cellular levels of the TATA-binding protein (TBP), a factor involved in the transcription of all cellular genes, and that this protein is limiting for the expression of RNA pol III genes. Both X-mediated increases in RNA pol III gene expression and TBP are dependent upon X-activation of cellular protein kinases. The investigator's aim is to define the signaling pathway activated by X and the consequence of this event on gene activity and TBP levels. The proposed studies will determine: (1) at what level X regulates the cellular increase in TBP; (2) whether both the X-mediated events are dependent upon the activation of the Ras signal transduction pathway; (3) whether X activates Sos-Grb2 complexes and whether this is necessary for gene induction; and (4) whether RNA pol III gene induction and the increase in cellular TBP is mediated exclusively by activating signaling proteins. The proposed studies will comprehensively assess the relationship between X-activation of RNA pol III genes, X-mediated increases in TBP, and the activation of Ras. The investigator will also examine whether X can activate RNA pol I gene expression. These results could demonstrate, for the first time, a whole new class of cellular genes that are induced by X. If so, the investigator will also determine whether induction by X is also dependent upon Ras activation and increased TBP levels. The proposed experiments will be carried out using rat 1 cells and/or Drosopholia S-2 cells that are transiently transfected or genetically altered to express expression vectors for X or other genes. The goal of the studies will potentially be to define a key function of the X protein that allows HBV to intrude into the cellular transcription machinery and ultimately alter the growth properties of the cell. These basic studies will directly impact treatment of HBV-infected patients. With the many new anti-Ras therapeutic agents under investigation, these studies could lead the way for a potential new use of these compounds: by inhibiting X mediated Ras activation to prevent pathogenesis in individuals chronically infected with HBV.