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

描述（由申请人提供）：丙型肝炎病毒（HCV）感染困扰着全世界约 1.7 亿人，这些人的慢性病毒感染是肝细胞癌（HCC）的重要原因。 HCV 诱发 HCC 的机制在很大程度上尚不清楚，但病毒诱导宿主细胞信号通路的改变以为病毒创造复制生态位并避免宿主抗病毒程序很可能是该发病机制的重要组成部分。通过基因组规模的 siRNA 筛选，我们已确定宿主蛋白 CARD14 是 HCV RNA 复制的重要因子。 CARD14 是 NF-kB 通路的已知调节因子，但其在生物学中的精确功能尚不清楚。我们的初步数据表明，HCV 感染细胞会导致 NF-kB 激活急剧增加，而这种激活依赖于 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，并且在慢性 HCV 感染期间长期操纵该通路可能是导致癌症发展的因素之一。我们的假设是，HCV RNA 有效复制和预防感染细胞凋亡需要 CARD14 依赖性激活 NF-kB 通路，并且 HCV 对该通路的操纵是 HCC 发展的重要因素。 CARD14如何在NF-kB信号传导中发挥作用、病毒如何操纵该通路以及这种操纵导致基因表达发生哪些变化等细节都是需要解决的重要问题，我们设计了四个具体目标来解决这些重要问题。我们建议验证 CARD14 和 NF-kB 激活之间的联系，绘制 NF-kB 激活和 HCV 复制所需的 CARD14 区域，确定 CARD14 是否作为细胞凋亡调节因子发挥作用，定义作为 CARD14 信号通路一部分的蛋白质，并确定 CARD14 在 HCV 感染期间操纵哪些细胞基因。这些目标的完成将大大加深我们对 HCV 复制的细胞需求、HCV 操纵 NF-kB 信号传导以促进细胞存活以及 CARD14 在这些过程中的功能的理解。这些实验对于HCV感染者发生HCC具有重要的潜在意义。 公共卫生相关性：该项目涉及丙型肝炎病毒与称为 CARD14 的细胞蛋白的相互作用。 CARD14 参与调节细胞存活和生长的重要细胞途径。 HCV与CARD14的相互作用可能对肝细胞癌的发生发展具有重要意义；丙型肝炎感染患者中的一种肝癌。

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. PUBLIC HEALTH RELEVANCE: This project involves the interaction of the hepatitis C virus with a cellular protein called CARD14. CARD14 is involved in an important cellular pathway regulating cell survival and growth. The interaction of HCV and CARD14 may have significance to the development of hepatocellular carcinoma; a form of liver cancer, in hepatitis C infected patients.