NF-κB Serves as a Cellular Sensor of Kaposi's Sarcoma-Associated Herpesvirus Latency and Negatively Regulates K-Rta by Antagonizing the RBP-Jκ Coactivator
NF-κB Serves as a Cellular Sensor of Kaposi's Sarcoma-Associated Herpesvirus Latency and Negatively Regulates K-Rta by Antagonizing the RBP-Jκ Coactivator
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DOI：
10.1128/jvi.01999-08
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发表时间：
2009-05-01
影响因子：
5.4
通讯作者：
Kung, Hsing-Jien
中科院分区：
文献类型：
--
作者：
Izumiya, Yoshihiro;Izumiya, Chie;Kung, Hsing-Jien
成功的病毒复制依赖于有利的细胞环境;因此，病毒必须对其宿主细胞的状态敏感。我们研究了病毒和细胞调节因子之间的相互作用决定了从卡波西肉瘤相关疱疹病毒（KSHV）潜伏期到裂解性复制的转变。立即早期基因产物K-Rta是表达的第一个病毒蛋白，并且是再活化的必要因素;因此，该病毒蛋白处于作为细胞生理学的病毒传感器的关键位置。我们的方法旨在定义宿主转录因子，即，宿主传感器，其调节病毒启动子上的K-Rta活性。为此，我们开发了一个面板的报告质粒含有所有83个假定的病毒启动子的全面调查的响应K-Rta和细胞转录因子。有趣的是，NF-κ B家族的成员被证明是K-Rta反式激活的强负调节因子，除了两个病毒启动子（Ori-RNA和K12）。当NF-κ B表达被诱导时，K-Rta向ORF 57和K-bZIP启动子的募集，而不是K12启动子的募集，显著受损。许多由NF-κ B调节的K-Rta响应性启动子含有RBP-J κ结合位点的序列，RBP-J κ结合位点是一种主要的共激活因子，其通过与NF-κ B重叠的共有基序将K-Rta锚定到靶启动子。凝胶迁移实验表明NF-κ B抑制RBP-J κ的结合并与RBP-J κ形成复合物。我们的研究结果支持一个模型，其中K-Rta/RBP-J κ和NF-κ B活性之间的平衡决定KSHV再激活。该模型的一个重要特征是病毒启动子上RBP-J κ和NF-κ B之间的相互作用控制由K-Rta介导的病毒基因表达。
Successful viral replication is dependent on a conducive cellular environment; thus, viruses must be sensitive to the state of their host cells. We examined the idea that an interplay between viral and cellular regulatory factors determines the switch from Kaposi's sarcoma-associated herpesvirus (KSHV) latency to lytic replication. The immediate-early gene product K-Rta is the first viral protein expressed and an essential factor in reactivation; accordingly, this viral protein is in a key position to serve as a viral sensor of cellular physiology. Our approach aimed to define a host transcription factor, i.e., host sensor, which modulates K-Rta activity on viral promoters. To this end, we developed a panel of reporter plasmids containing all 83 putative viral promoters for a comprehensive survey of the response to both K-Rta and cellular transcription factors. Interestingly, members of the NF-kappa B family were shown to be strong negative regulators of K-Rta transactivation for all but two viral promoters (Ori-RNA and K12). Recruitment of K-Rta to the ORF57 and K-bZIP promoters, but not the K12 promoter, was significantly impaired when NF-kappa B expression was induced. Many K-Rta-responsive promoters modulated by NF-kappa B contain the sequence of the RBP-J kappa binding site, a major coactivator which anchors K-Rta to target promoters via consensus motifs which overlap with that of NF-kappa B. Gel shift assays demonstrated that NF-kappa B inhibits the binding of RBP-J kappa and forms a complex with RBP-J kappa. Our results support a model in which a balance between K-Rta/RBP-J kappa and NF-kappa B activities determines KSHV reactivation. An important feature of this model is that the interplay between RBP-J kappa and NF-kappa B on viral promoters controls viral gene expression mediated by K-Rta.