RTA和LANA共调控let-7a/RBPJ信号在KSHV复制状态转换中的作用

Kaposi’s sarcoma-associated herpesvirus (KSHV) is associated with Kaposi’s sarcoma (KS) and other acquired immunodeficiency syndromes related tumors. KSHV latent infection and lytic replication and the continued infection of new cells are therefore likely to be essential for the maintenance of the population of infected cells and development of viral pathogenesis. The latency-associated nuclear antigen (LANA) and replication and transcription activator (RTA) binding with the recombination signal binding protein for immunoglobulin kappa J region (RBPJ), respectively, which to facilitate lytic replication or latent infection. However, the relationship between expression regulation of LANA, RTA and RBPJ is not clear. Previously, we found LANA increased let-7a while RTA decreases let-7a expression, and RBPJ directly targeted by let-7a. We hypothesized that LANA and RTA co-regulating the let-7a/RBPJ signaling to control KSHV replication status switching. The let-7a/RBPJ is the key signaling pathway of regulating KSHV latent establish, maintenance, and switch to lytic replication. In this proposal, we will explore: the mechanisms of regulating let-7a/RBPJ signaling by RTA or LANA; the effects of KSHV replication status and different RTA and LANA ratio on let-7a/RBPJ signaling; and, the role of let-7a/RBPJ on regulating LANA and RTA expression; the effect of let-7a/RBPJ signaling on KSHV replication status switching. Our data will be useful to further elucidate the mechanism KSHV replication.

卡波氏肉瘤相关疱疹病毒(KSHV)是卡波氏肉瘤等艾滋病常见肿瘤的病原。重组信号序列结合蛋白J kappa (RBPJ)与复制与转录激活因子(RTA)结合促进KSHV裂解复制，与潜伏相关核抗原(LANA)结合则维持潜伏感染。但RTA与LANA对RBPJ表达的影响，以及RBPJ在KSHV复制状态转换中的作用尚不清楚。我们前期研究结果提示RTA和LANA通过共调控let-7a/RBPJ信号，RBPJ表达水平可能是控制KSHV复制状态转换的决定因素。本项目将首先研究RTA、LANA调控let-7a/RBPJ的机制，然后分析RTA与LANA相对量对let-7a/RBPJ信号的影响，以及let-7a/RBPJ在RTA与LANA表达调控中的作用，最后探讨let-7a/RBPJ在KSHV复制状态转换中的作用。本研究将为深入理解KSHV复制调控机制及相关疾病的防治提供新的理论支持。

卡波氏肉瘤相关疱疹病毒(Kaposi’s sarcoma-associated herpesvirus, KSHV)可在宿主体内建立终生潜伏期，但其复制机制尚不完全清楚。潜伏相关核抗原(Latency-associated nuclear antigen, LANA)是潜伏建立和维持的关键因素，其中抑制复制与转录激活子 (replication and transcription activator, RTA)的表达是其重要机制。一种细胞蛋白，免疫球蛋白J区重组信号结合蛋白(recombination signal binding protein for immunoglobulin kappa J region, RBPJ)，在KSHV的溶解性再激活中也是必不可少的。RBPJ与RTA或LANA结合，作为KSHV潜/溶解开关的中介;但RBPJ的表达是否受KSHV调控尚不清楚。我们之前发现microRNA let-7a可以抑制KSHV的裂解复制。在这里，我们发现LANA上调let-7a及其主要转录本，同时降低RBPJ的表达。NOTCH胞内结构域(NICD)的增加以及NF-κB和Lin28B的下调是LANA上调let-7a的原因之一。Let-7a通过直接结合RBPJ的3非翻译区来抑制RBPJ的表达。过表达let-7a或降低RBPJ剂量和时间依赖性抑制KSHV的裂解性再激活。RTA通过降低let-7a增加RBPJ。在KSHV复制过程中，RBPJ表达水平与RTA表达水平呈正相关，与LANA表达水平呈负相关。let-7a表达水平与RBPJ相反。RBPJ的下调抑制了RTA启动子和LANA启动子的自激活，削弱了LANA对RTA启动子的抑制作用。这些结果表明，RTA和LANA争夺let-7a/RBPJ信号来控制KSHV的复制。这些新发现表明，LANA和RTA共同调控KSHV复制，竞争性调控let-7a/RBPJ信号。RTA和LANA调控RBPJ的表达水平在KSHV复制过程中起着重要作用。