Sanchez Erica L, Pulliam Thomas H, Dimaio Terri A, Thalhofer Angel B, Delgado Tracie, Lagunoff Michael
Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, USA.
Department of Microbiology, University of Washington, Seattle, Washington, USA.
J Virol. 2017 Apr 28;91(10). doi: 10.1128/JVI.02237-16. Print 2017 May 15.
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS). KSHV infection induces and requires multiple metabolic pathways, including the glycolysis, glutaminolysis, and fatty acid synthesis (FAS) pathways, for the survival of latently infected endothelial cells. To determine the metabolic requirements for productive KSHV infection, we induced lytic replication in the presence of inhibitors of different metabolic pathways. We found that glycolysis, glutaminolysis, and FAS are all required for maximal KSHV virus production and that these pathways appear to participate in virus production at different stages of the viral life cycle. Glycolysis and glutaminolysis, but not FAS, inhibit viral genome replication and, interestingly, are required for different early steps of lytic gene expression. Glycolysis is necessary for early gene transcription, while glutaminolysis is necessary for early gene translation but not transcription. Inhibition of FAS resulted in decreased production of extracellular virions but did not reduce intracellular genome levels or block intracellular virion production. However, in the presence of FAS inhibitors, the intracellular virions are noninfectious, indicating that FAS is required for virion assembly or maturation. KS tumors support both latent and lytic KSHV replication. Previous work has shown that multiple cellular metabolic pathways are required for latency, and we now show that these metabolic pathways are required for efficient lytic replication, providing novel therapeutic avenues for KS tumors. KSHV is the etiologic agent of Kaposi's sarcoma, the most common tumor of AIDS patients. KS spindle cells, the main tumor cells, all contain KSHV, mostly in the latent state, during which there is limited viral gene expression. However, a percentage of spindle cells support lytic replication and production of virus and these cells are thought to contribute to overall tumor formation. Our previous findings showed that latently infected cells are sensitive to inhibitors of cellular metabolic pathways, including glycolysis, glutaminolysis, and fatty acid synthesis. Here we found that these same inhibitors block the production of infectious virus from lytically infected cells, each at a different stage of viral replication. Therefore, inhibition of specific cellular metabolic pathways can both eliminate latently infected cells and block lytic replication, thereby inhibiting infection of new cells. Inhibition of metabolic pathways provides novel therapeutic approaches for KS tumors.
卡波西肉瘤相关疱疹病毒（KSHV）是卡波西肉瘤（KS）的病原体。KSHV感染诱导并依赖多种代谢途径，包括糖酵解、谷氨酰胺分解和脂肪酸合成（FAS）途径，以维持潜伏感染的内皮细胞存活。为了确定KSHV有效感染的代谢需求，我们在存在不同代谢途径抑制剂的情况下诱导裂解复制。我们发现糖酵解、谷氨酰胺分解和FAS对于最大程度的KSHV病毒产生都是必需的，并且这些途径似乎在病毒生命周期的不同阶段参与病毒产生。糖酵解和谷氨酰胺分解而非FAS抑制病毒基因组复制，有趣的是，它们是裂解基因表达不同早期步骤所必需的。糖酵解对于早期基因转录是必需的，而谷氨酰胺分解对于早期基因翻译而非转录是必需的。抑制FAS导致细胞外病毒粒子产量降低，但并未降低细胞内基因组水平或阻断细胞内病毒粒子产生。然而，在存在FAS抑制剂的情况下，细胞内病毒粒子无感染性，这表明FAS对于病毒粒子组装或成熟是必需的。KS肿瘤支持KSHV的潜伏和裂解复制。先前的研究表明潜伏需要多种细胞代谢途径，我们现在表明这些代谢途径对于有效的裂解复制也是必需的，这为KS肿瘤提供了新的治疗途径。KSHV是卡波西肉瘤的病原体，卡波西肉瘤是艾滋病患者最常见的肿瘤。KS梭形细胞是主要的肿瘤细胞，都含有KSHV，大多处于潜伏状态，在此期间病毒基因表达有限。然而，一定比例的梭形细胞支持裂解复制和病毒产生，并且这些细胞被认为对整体肿瘤形成有贡献。我们先前的研究结果表明，潜伏感染的细胞对包括糖酵解、谷氨酰胺分解和脂肪酸合成在内的细胞代谢途径抑制剂敏感。在这里我们发现，这些相同的抑制剂在病毒复制的不同阶段阻断了裂解感染细胞产生有感染性的病毒。因此，抑制特定的细胞代谢途径既能消除潜伏感染的细胞又能阻断裂解复制，从而抑制新细胞的感染。抑制代谢途径为KS肿瘤提供了新的治疗方法。
