From the Division of Chemotherapy, Faculty of Pharmacy, Keio University, 1-5-30 Shibakoen, Minato-ku, Tokyo 105-8512 and.
From the Division of Chemotherapy, Faculty of Pharmacy, Keio University, 1-5-30 Shibakoen, Minato-ku, Tokyo 105-8512 and
J Biol Chem. 2018 Jan 12;293(2):662-676. doi: 10.1074/jbc.M117.802900. Epub 2017 Nov 28.
Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus-8 (HHV-8) causes a persistent infection, presenting latent and lytic replication phases during its life cycle. KSHV-related diseases are associated with deregulated expression of inflammatory cytokines, including IL-6 and IL-10, but the mechanisms underlying this dysregulation are unclear. Herein, we report a molecular mechanism for KSHV-induced gene expression. KSHV replication and transcription activator (K-RTA) is a molecular switch for the initiation of expression of viral lytic genes, and we describe, for the first time, that K-RTA significantly activates the promoter of the human gene. Of note, mutations involving a basic region of K-RTA reduced the association of K-RTA with the promoter. Moreover, the host-cell transcription factors, specificity proteins (SP) 1 and 3, play a pivotal cooperative role in K-RTA-mediated transactivation of the promoter. K-RTA can interact with SP1 and SP3 directly , and electrophoresis mobility shift assays (EMSAs) revealed co-operative interaction involving K-RTA, SP1, and SP3 in binding to the promoter. As DNase I footprinting assays indicated that K-RTA did not affect SP3 binding to the promoter, SP3 can function to recruit K-RTA to the promoter. These findings indicate that K-RTA can directly contribute to up-regulation via a functional interplay with the cellular transcription factors SP1 and SP3.
卡波济肉瘤相关疱疹病毒(KSHV)/人类疱疹病毒-8(HHV-8)导致持续性感染,在其生命周期中呈现潜伏和裂解复制阶段。KSHV 相关疾病与炎症细胞因子(包括 IL-6 和 IL-10)的失调表达有关,但这种失调的机制尚不清楚。在此,我们报告了 KSHV 诱导基因表达的分子机制。KSHV 复制和转录激活剂(K-RTA)是启动病毒裂解基因表达的分子开关,我们首次描述 K-RTA 可显著激活人基因的启动子。值得注意的是,涉及 K-RTA 碱性区的突变会降低 K-RTA 与基因启动子的结合。此外,宿主细胞转录因子特异性蛋白(SP)1 和 3 在 K-RTA 介导的基因启动子的转录激活中起着关键的协同作用。K-RTA 可以直接与 SP1 和 SP3 相互作用,电泳迁移率变动分析(EMSA)显示 K-RTA、SP1 和 SP3 之间存在协同相互作用,参与结合基因启动子。DNase I 足迹实验表明 K-RTA 不影响 SP3 结合基因启动子,因此 SP3 可以募集 K-RTA 到基因启动子。这些发现表明,K-RTA 可以通过与细胞转录因子 SP1 和 SP3 的功能相互作用,直接促进基因的上调。