Mund Rachel, Atkins Sage L, Cao Anwen, Diallo Aminatou, Whitehurst Christopher B
Department of Pathology, Microbiology and Immunology, New York Medical College, New York, NY 10595, USA.
Department of Microbiology and Immunology, University of North Carolina Chapel Hill, Chapel Hill, NC 27599, USA.
Viruses. 2025 Aug 20;17(8):1139. doi: 10.3390/v17081139.
Epstein-Barr Virus (EBV) is a causative agent of infectious mononucleosis and is strongly associated with Burkitt lymphoma, Hodgkin lymphoma, and nasopharyngeal carcinoma. EBV encodes a deubiquitinating enzyme, BPLF1, which is important for infectious virus production, B-cell immortalization, and tumorigenesis. To elucidate BPLF1's role, an affinity-based mass spectrometry screen was performed, which suggested that BPLF1 and mTOR interact. mTOR, a critical mediator within cellular signaling cascades and oncogenesis, exists in two distinct complexes: mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2). Here, we show that BPLF1 has direct deubiquitinating (DUB) activity on mTOR, removing both K48- and K63-ubiquitin linkages. Additionally, WT BPLF1 decreased mTORC1 localization to the lysosome and decreased the phosphorylation of mTORC1 downstream effectors, 4E-BP1 and S6K1. BPLF1 also had DUB activity on Raptor and Rictor, which have both been shown to preferentially cause the formation of mTORC2 over mTORC1 when not ubiquitinated. Immunoprecipitation of mTOR shows decreased mTORC1 formation in the presence of WT BPLF1. Importantly, treatment with rapamycin, an mTORC1 inhibitor, increased infectious virus production, while JR-AB2-011, an mTORC2 inhibitor, reduced infectious virus production. Taken together, these data demonstrate that BPLF1's effect on the mTOR signaling cascade regulates cellular and viral processes during EBV infectivity and replication.
爱泼斯坦-巴尔病毒（EBV）是传染性单核细胞增多症的病原体，与伯基特淋巴瘤、霍奇金淋巴瘤和鼻咽癌密切相关。EBV编码一种去泛素化酶BPLF1，它对传染性病毒的产生、B细胞永生化和肿瘤发生很重要。为了阐明BPLF1的作用，进行了基于亲和的质谱筛选，结果表明BPLF1与mTOR相互作用。mTOR是细胞信号级联和肿瘤发生中的关键介质，以两种不同的复合物形式存在：mTOR复合物1（mTORC1）和mTOR复合物2（mTORC2）。在此，我们表明BPLF1对mTOR具有直接去泛素化（DUB）活性，可去除K48和K63泛素连接。此外，野生型BPLF1减少了mTORC1定位于溶酶体，并降低了mTORC1下游效应物4E-BP1和S6K1的磷酸化。BPLF1对Raptor和Rictor也具有DUB活性，当未被泛素化时，Raptor和Rictor均已被证明优先导致mTORC2而非mTORC1的形成。mTOR的免疫沉淀显示在野生型BPLF1存在下mTORC1的形成减少。重要的是，用mTORC1抑制剂雷帕霉素处理可增加传染性病毒的产生，而mTORC2抑制剂JR-AB2-011则可减少传染性病毒的产生。综上所述，这些数据表明BPLF1对mTOR信号级联的影响在EBV感染性和复制过程中调节细胞和病毒过程。
