Dysregulation of dual-specificity phosphatases by Epstein-Barr virus LMP1 and its impact on lymphoblastoid cell line survival
Journal
Journal of Virology
Journal Volume
94
Journal Issue
4
Date Issued
2020
Author(s)
Lin K.-M.
Lin S.-J.
Lin J.-H.
Lin P.-Y.
Teng P.-L.
Wu H.-E.
Wang Y.-P.
Abstract
The strongest evidence of the oncogenicity of Epstein-Barr virus (EBV) in vitro is its ability to immortalize human primary B lymphocytes into lymphoblastoid cell lines (LCLs). Yet the underlying mechanisms explaining how the virus tempers the growth program of the host cells have not been fully elucidated. The mitogen-activated protein kinases (MAPKs) are implicated in many cellular processes and are constitutively activated in LCLs. We questioned the expression and regulation of the dual-specificity phosphatases (DUSPs), the main negative regulator of MAPKs, during EBV infection and immortalization. Thirteen DUSPs, including 10 typical and 3 atypical types of DUSPs, were tested. Most of them were downregulated after EBV infection. Here, a role of viral oncogene latent membrane protein 1 (LMP1) in limiting DUSP6 and DUSP8 expression was identified. Using MAPK inhibitors, we found that LMP1 activates extracellular signal-regulated kinase (ERK) or p38 to repress the expression of DUSP6 and DUSP8, with corresponding substrate specificity. Morphologically, overexpression of DUSP6 and DUSP8 attenuates the ability of EBV-immortalized LCL cells to clump together. Mechanistically, apoptosis induced by restoring DUSP6 and DUSP8 in LCLs indicated a novel mechanism for LMP1 to provide a survival signal during EBV immortalization. Collectively, this report provides the first description of the interplay between EBV genes and DUSPs and contributes considerably to the interpretation of MAPK regulation in EBV immortalization. IMPORTANCE Infections by the ubiquitous Epstein-Barr virus (EBV) are associated with a wide spectrum of lymphomas and carcinomas. It has been well documented that activation levels of MAPKs are found in cancer cells to translate various external or intrinsic stimuli into cellular responses. Physiologically, the dual-specificity phosphates (DUSPs) exhibit great ability in regulating MAPK activities with respect to their capability of dephosphorylating MAPKs. In this study, we found that DUSPs were generally downregulated after EBV infection. EBV oncogenic latent membrane protein 1 (LMP1) suppressed DUSP6 and DUSP8 expression via MAPK pathway. In this way, LMP1-mediated MAPK activation was a continuous process. Furthermore, DUSP downregulation was found to contribute greatly to prevent apoptosis of EBV-infected cells. To sum up, this report sheds light on a novel molecular mechanism explaining how EBV maintains the unlimited proliferation status of the immortalized cells and provides a new link to understand EBV-induced B cell survival. ? 2020 American Society for Microbiology. All Rights Reserved.
Subjects
EBV
SDGs
Other Subjects
dual specificity phosphatase; dual specificity phosphatase 6; dual specificity phosphatase 8; latent membrane protein 1; mitogen activated protein kinase; mitogen activated protein kinase inhibitor; mitogen activated protein kinase p38; unclassified drug; dual specificity phosphatase; EBV-associated membrane antigen, Epstein-Barr virus; immunoglobulin enhancer binding protein; matrix protein; mitogen activated protein kinase; mitogen activated protein kinase p38; viral protein; apoptosis; Article; B lymphocyte; cell survival; controlled study; enzyme regulation; enzyme specificity; Epstein Barr virus; Epstein Barr virus infection; flow cytometry; human; human cell; in vitro study; Lentivirus infection; lymphoblastoid cell line; morphology; nonhuman; plasmid; priority journal; protein expression; reverse transcription polymerase chain reaction; survival; Western blotting; Epstein Barr virus; genetics; metabolism; physiology; primary cell culture; tumor cell line; virology; virus gene; virus latency; Apoptosis; B-Lymphocytes; Cell Line, Tumor; Dual-Specificity Phosphatases; Epstein-Barr Virus Infections; Extracellular Signal-Regulated MAP Kinases; Genes, Viral; Herpesvirus 4, Human; Humans; Mitogen-Activated Protein Kinases; NF-kappa B; p38 Mitogen-Activated Protein Kinases; Primary Cell Culture; Viral Matrix Proteins; Viral Proteins; Virus Latency
Publisher
American Society for Microbiology
Type
journal article