Garrigues H Jacques, Howard Kellie, Barcy Serge, Ikoma Minako, Moses Ashlee V, Deutsch Gail H, Wu David, Ueda Keiji, Rose Timothy M
Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA.
Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon, USA.
J Virol. 2017 Nov 30;91(24). doi: 10.1128/JVI.01532-17. Print 2017 Dec 15.
The latency-associated nuclear antigen (LANA) of the Kaposi's sarcoma-associated herpesvirus (KSHV) performs a variety of functions to establish and maintain KSHV latency. During latency, LANA localizes to discrete punctate spots in the nucleus, where it tethers viral episomes to cellular chromatin and interacts with nuclear components to regulate cellular and viral gene expression. Using highly sensitive tyramide signal amplification, we determined that LANA localizes to the cytoplasm in different cell types undergoing the lytic cycle of replication after primary infection and after spontaneous, tetradecanoyl phorbol acetate-, or open reading frame 50 (ORF50)/replication transactivator (RTA)-induced activation. We confirmed the presence of cytoplasmic LANA in a subset of cells in lytically active multicentric Castleman disease lesions. The induction of cellular migration by scratch-wounding confluent cell cultures, culturing under subconfluent conditions, or induction of cell differentiation in primary cultures upregulated the number of cells permissive for primary lytic KSHV infection. The induction of lytic replication was characterized by high-level expression of cytoplasmic LANA and nuclear ORF59, a marker of lytic replication. Subcellular fractionation studies revealed the presence of multiple isoforms of LANA in the cytoplasm of ORF50/RTA-activated Vero cells undergoing primary infection. Mass spectrometry analysis demonstrated that cytoplasmic LANA isoforms were full length, containing the N-terminal nuclear localization signal. These results suggest that trafficking of LANA to different subcellular locations is a regulated phenomenon, which allows LANA to interact with cellular components in different compartments during both the latent and the replicative stages of the KSHV life cycle. Kaposi's sarcoma-associated herpesvirus (KSHV) causes AIDS-related malignancies, including lymphomas and Kaposi's sarcoma. KSHV establishes lifelong infections using its latency-associated nuclear antigen (LANA). During latency, LANA localizes to the nucleus, where it connects viral and cellular DNA complexes and regulates gene expression, allowing the virus to maintain long-term infections. Our research shows that intact LANA traffics to the cytoplasm of cells undergoing permissive lytic infections and latently infected cells in which the virus is induced to replicate. This suggests that LANA plays important roles in the cytoplasm and nuclear compartments of the cell during different stages of the KSHV life cycle. Determining cytoplasmic function and mechanism for regulation of the nuclear localization of LANA will enhance our understanding of the biology of this virus, leading to therapeutic approaches to eliminate infection and block its pathological effects.
卡波西肉瘤相关疱疹病毒(KSHV)的潜伏期相关核抗原(LANA)具有多种功能,以建立和维持KSHV潜伏期。在潜伏期,LANA定位于细胞核内离散的点状区域,在那里它将病毒附加体与细胞染色质相连,并与核成分相互作用以调节细胞和病毒基因表达。使用高灵敏度的酪胺信号放大技术,我们确定在初次感染后以及自发、经十四烷酰佛波醇乙酸酯或开放阅读框50(ORF50)/复制反式激活因子(RTA)诱导激活后,处于复制裂解周期的不同细胞类型中,LANA定位于细胞质。我们证实在具有裂解活性的多中心Castleman病病变的一部分细胞中存在细胞质LANA。通过刮擦汇合的细胞培养物诱导细胞迁移、在亚汇合条件下培养或在原代培养物中诱导细胞分化,上调了允许初次裂解性KSHV感染的细胞数量。裂解复制的诱导以细胞质LANA和核ORF59(裂解复制的标志物)的高水平表达为特征。亚细胞分级分离研究显示,在经历初次感染的ORF50/RTA激活的Vero细胞的细胞质中存在多种LANA异构体。质谱分析表明,细胞质LANA异构体是全长的,包含N端核定位信号。这些结果表明,LANA向不同亚细胞位置的转运是一种受调控的现象,这使得LANA在KSHV生命周期的潜伏和复制阶段都能与不同区室中的细胞成分相互作用。卡波西肉瘤相关疱疹病毒(KSHV)可导致与艾滋病相关的恶性肿瘤,包括淋巴瘤和卡波西肉瘤。KSHV利用其潜伏期相关核抗原(LANA)建立终身感染。在潜伏期,LANA定位于细胞核,在那里它连接病毒和细胞DNA复合物并调节基因表达,使病毒能够维持长期感染。我们的研究表明,完整的LANA会转运至允许裂解感染的细胞以及潜伏感染且病毒被诱导复制的细胞的细胞质中。这表明LANA在KSHV生命周期的不同阶段在细胞的细胞质和细胞核区室中发挥重要作用。确定LANA的细胞质功能及其核定位的调控机制将增进我们对这种病毒生物学特性的理解,从而带来消除感染并阻断其病理效应的治疗方法。