Lan Ke, Kuppers Daniel A, Verma Subhash C, Sharma Nikhil, Murakami Masanao, Robertson Erle S
Department of Microbiology, University of Pennsylvania Medical School, 201E Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA 19104, USA.
J Virol. 2005 Jun;79(12):7453-65. doi: 10.1128/JVI.79.12.7453-7465.2005.
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent contributing to development of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman desease. Following primary infection, latency is typically established. However, the mechanism by which KSHV establishes latency is not understood. We have reported that the latency-associated nuclear antigen (LANA) can repress RTA (for replication and transcription activator) expression by down-regulating its promoter. In this study, we show that RTA is associated with the virion particle. We also show that RTA can activate the LANA promoter and induce LANA expression in transient reporter assays. Additionally, the transcription of RTA correlates with LANA expression in the early stages of de novo infection of KSHV, and induction of LANA transcription is responsive to induction of RTA with an inducible system. This induction in LANA transcription was dependent on recombination signal sequence binding protein Jkappa (RBP-Jkappa), as a RBP-Jkappa-deficient cell line was significantly delayed and inefficient in LANA transcription with expression of RTA. These studies suggest that RTA contributes to establishment of KSHV latency by activating LANA expression in the early stages of infection by utilizing the major effector of the Notch signaling pathway RBP-Jkappa. This describes a feedback mechanism by which LANA and RTA can regulate each other and is likely to be a key event in the establishment of KSHV latency.
卡波西肉瘤相关疱疹病毒(KSHV)是导致卡波西肉瘤、原发性渗出性淋巴瘤和多中心性Castleman病发生的病原体。初次感染后,通常会建立潜伏期。然而,KSHV建立潜伏期的机制尚不清楚。我们曾报道潜伏相关核抗原(LANA)可通过下调其启动子来抑制RTA(复制和转录激活因子)的表达。在本研究中,我们发现RTA与病毒粒子相关。我们还表明,在瞬时报告基因检测中,RTA可激活LANA启动子并诱导LANA表达。此外,在KSHV初次感染的早期阶段,RTA的转录与LANA表达相关,并且利用诱导系统诱导RTA可使LANA转录产生应答。LANA转录的这种诱导依赖于重组信号序列结合蛋白Jkappa(RBP-Jkappa),因为在RTA表达时,RBP-Jkappa缺陷细胞系的LANA转录显著延迟且效率低下。这些研究表明,RTA通过在感染早期利用Notch信号通路的主要效应因子RBP-Jkappa激活LANA表达,从而促进KSHV潜伏期的建立。这描述了一种LANA和RTA相互调节的反馈机制,并且可能是KSHV潜伏期建立过程中的关键事件。