CARD14 is essential for hepatitis C virus replication and activation of NFKB

描述（由申请人提供）：全球约有1.7亿人感染丙型肝炎病毒（HCV），这些人的慢性病毒感染是导致肝细胞癌（HCC）的重要原因。HCV诱导HCC的机制在很大程度上是未知的，但很可能是病毒诱导宿主细胞信号通路的改变，为病毒创造一个复制生态位，避免宿主抗病毒程序，这是这一发病机制的重要组成部分。通过基因组尺度的siRNA筛选，我们发现宿主蛋白CARD14是HCV RNA复制的一个重要因素。CARD14是已知的NF-kB通路的调节因子，但其在生物学中的确切功能尚不清楚。我们的初步数据显示，HCV感染细胞导致NF-kB激活急剧增加，这种激活依赖于CARD14蛋白的存在。许多感染因子改变NF-kB基因表达以促进宿主细胞的存活，慢性HCV感染期间对这一途径的长期操纵可能是导致癌症发展的一个因素。我们的假设是CARD14依赖性NF-kB通路的激活是HCV RNA有效复制和预防感染细胞凋亡所必需的，并且HCV对该通路的操纵是HCC发展的一个重要因素。CARD14如何在NF-kB信号传导中起作用，病毒如何操纵这一途径，以及这种操纵导致的基因表达变化的细节是需要解决的重要问题，我们设计了四个特定的目标来解决这些重要问题。我们打算验证CARD14和NF-kB激活之间的联系，绘制CARD14的哪些区域是NF-kB激活和HCV复制所必需的，确定CARD14是否作为细胞凋亡的调节剂，定义CARD14信号通路的一部分蛋白，并确定在HCV感染期间CARD14操纵的细胞基因。这些目标的完成将大大增加我们对HCV复制的细胞需求，HCV操纵NF-kB信号以促进细胞存活，以及CARD14在这些过程中的功能的理解。这些实验对HCV感染者HCC的发展具有重要的潜在意义。

DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) infection afflicts approximately 170 million people worldwide and chronic virus infection in these individuals is a significant cause of hepatocellular carcinoma (HCC). The mechanisms by which HCV induces HCC are largely unknown, but it is likely that virus induced alteration of host cell signaling pathways to create a replication niche for the virus and avoid the host anti-viral program is an important component of this pathogenesis. Using genomic scale siRNA screening, we have identified the host protein CARD14 as an important factor for HCV RNA replication. CARD14 is a known regulator of the NF-kB pathway, but its precise function in biology is unknown. Our preliminary data shows that infection of cells by HCV leads to a dramatic increase in NF-kB activation, and this activation is dependent on the presence of the CARD14 protein. Many infectious agents alter NF-kB gene expression to promote survival of the host cell, and the long-term manipulation of this pathway during chronic HCV infection may be one factor leading to the development of cancer. Our hypothesis is that CARD14 dependent activation of the NF-kB pathway is required for efficient HCV RNA replication and the prevention of apoptosis in infected cells, and that manipulation of this pathway by HCV is an important factor in the development of HCC. The details of how CARD14 functions in NF-kB signaling, how the virus manipulates this pathway, and what changes in gene expression result from this manipulation are important questions that need to be addressed, and we have designed four specific aims to address these important questions. We propose to validate the connection between CARD14 and NF-kB activation, map what regions of CARD14 are required for NF-kB activation and HCV replication, determine if CARD14 is functioning as a regulator of apoptosis, define proteins that are part of the CARD14 signaling pathway, and determine what cellular genes CARD14 manipulates during HCV infection. The completion of these aims will add considerably to our understanding of the cellular requirements for HCV replication, the manipulation of NF-kB signaling by HCV to promote cell survival, and the function of CARD14 in these processes. These experiments are of great potential significance to the development of HCC in those infected with HCV.