Epstein–Barr virus-transforming protein latent infection membrane protein 1 activates transcription factor NF-κB through a pathway that includes the NF-κB-inducing kinase and the IκB kinases IKKα and IKKβ (original) (raw)
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Proceedings of the National Academy of Sciences, 2003
Epstein–Barr virus (EBV) latent infection membrane protein 1 (LMP1)-induced NF-κB activation is important for infected cell survival. LMP1 activates NF-κB, in part, by engaging tumor necrosis factor (TNF) receptor-associated factors (TRAFs), which also mediate NF-κB activation from LTβR and CD40. LTβR and CD40 activation of p100/NF-κB2 is now known to be NIK/IKKα-dependent and IKKβ/IKKγ independent. In the experiments described here, we found that EBV LMP1 induced p100/NF-κB2 processing in human lymphoblasts and HEK293 cells. LMP1-induced p100 processing was NIK/IKKα dependent and IKKβ/IKKγ independent. Furthermore, the LMP1 TRAF-binding site was required for p100 processing and p52 nuclear localization, whereas the LMP1 death domain-binding site was not. Moreover, the LMP1 TRAF-binding site preferentially caused RelB nuclear accumulation. In murine embryo fibroblasts (MEFs), IKKβ was essential for LMP1 up-regulation of macrophage inflammatory protein (MIP)-2, TNFα, I-TAC, ELC, MIG,...
Epstein–Barr virus latent membrane protein 1 activation of NF-κB through IRAK1 and TRAF6
Proceedings of the National Academy of Sciences, 2003
Epstein–Barr virus latent membrane protein 1 (LMP1) activation of NF-κB is critical for Epstein–Barr virus-infected B lymphocyte survival. LMP1 activates the IκB kinase complex and NF-κB through two cytoplasmic signaling domains that engage tumor necrosis factor receptor-associated factor (TRAF)1/2/3/5 or TRADD and RIP. We now use cells lacking expression of TRAF2, TRAF5, TRAF6, IKKα, IKKβ, IKKγ, TAB2, IL-1 receptor-associated kinase (IRAK)1, or IRAK4 to assess their roles in LMP1-mediated NF-κB activation. LMP1-induced RelA nuclear translocation was similar in IKKα knockout (KO) and WT murine embryo fibroblasts (MEFs) but substantially deficient in IKKβ KO MEFs. NF-κB-dependent promoter responses were also substantially deficient in IKKβ KO MEFs but were hyperactive in IKKα KO MEFs. More surprisingly, NF-κB responses were near normal in TRAF2 and TRAF5 double-KO MEFs, IKKγ KO MEFs, TAB2 KO MEFs, and IRAK4 KO MEFs but were highly deficient in TRAF6 KO MEFs and IRAK1 KO HEK293 cells....
Epstein-Barr virus latent membrane protein 1 activation of NF- B through IRAK1 and TRAF6
Proceedings of the National Academy of Sciences, 2003
P rimary Epstein-Barr Virus (EBV) infection of B lymphocytes causes their long-term proliferation through expression of several proteins, including latent infection integral membrane protein 1 (LMP1). LMP1 is critical for EBV-infected cell activation, adhesion, and survival (1). EBV is causally associated with lymphoid and epithelial malignancies, including posttransplant lymphoproliferative disorders, Hodgkin's disease, anaplastic nasopharyngeal carcinoma, and gastric carcinomas; LMP1 is usually expressed in the malignant cells (2). LMP1 can transform rodent fibroblasts to anchorage, contact, and serum-independent growth and to tumorigenicity in nude mice (3). LMP1 expression in human B lymphoblasts alters cell growth, and transgenic expression in murine B cells causes hyperplasia and lymphoma (4).
Proceedings of The National Academy of Sciences, 2004
Epstein-Barr virus (EBV) latent infection membrane protein 1 (LMP1)-induced NF-B activation is important for infected cell survival. LMP1 activates NF-B, in part, by engaging tumor necrosis factor (TNF) receptor-associated factors (TRAFs), which also mediate NF-B activation from LTR and CD40. LTR and CD40 activation of p100/NF-B2 is now known to be NIK/IKK-dependent and IKK/IKK independent. In the experiments described here, we found that EBV LMP1 induced p100/NF-B2 processing in human lymphoblasts and HEK293 cells. LMP1-induced p100 processing was NIK/IKK dependent and IKK/IKK independent. Furthermore, the LMP1 TRAF-binding site was required for p100 processing and p52 nuclear localization, whereas the LMP1 death domain-binding site was not. Moreover, the LMP1 TRAF-binding site preferentially caused RelB nuclear accumulation. In murine embryo fibroblasts (MEFs), IKK was essential for LMP1 up-regulation of macrophage inflammatory protein (MIP)-2, TNF, I-TAC, ELC, MIG, and CXCR4 RNAs. Interestingly, in IKK knockout MEFs, LMP1 hyperinduced MIP-2, TNF, and I-TAC expression, consistent with a role for IKKα in down-modulating canonical IKKβ activation or its effects. In contrast, LMP1 failed to up-regulate CXCR4 and MIG RNA in IKKα knockout MEFs, indicating a dependence on noncanonical IKKα activation. Furthermore, LMP1 up-regulation of MIP-2 RNA in MEFs was both IKKβ- and IKKγ-dependent, whereas LMP1 upregulation of MIG and I-TAC RNA was fully IKKγ independent. Thus, LMP1 induces typical canonical IKKβ/IKKγ-dependent, atypical canonical IKKβ-dependent/IKKγ-independent, and noncanonical NIK/IKKα-dependent NF-κB activations; NIK/IKKα-dependent NF-κB activation is principally mediated by the LMP1 TRAF-binding site.
Proceedings of the National Academy of Sciences of the United States of America, 1996
Latent infection membrane protein 1 (LMP1), the Epstein-Barr virus transforming protein, associates with tumor necrosis factor receptor (TNFR) associated factor 1 (TRAF1) and TRAF3. Since TRAF2 has been implicated in TNFR-mediated NF-KcB activation, we have evaluated the role of TRAF2 in LMPl-mediated NF-ucB activation. TRAF2 binds in vitro to the LMP1 carboxyl-terminal cytoplasmic domain (CT), coprecipitates with LMP1 in B lymphoblasts, and relocalizes to LMP1 plasma membrane patches. A dominant negative TRAF2 deletion mutant that lacks amino acids 6-86 (TRAF2A6-86) inhibits NF-KB activation from the LMP1 CT and competes with TRAF2 for LMP1 binding. TRAF2A6-86 inhibits NF-,cB activation mediated by the first 45 amino acids of the LMP1 CT by more than 75% but inhibits NF-ucB activation through the last 55 amino acids of the CT by less than 40%o. A TRAF interacting protein, TANK, inhibits NF-.cB activation by more than 70%16 from both LMP1 CT domains. These data implicate TRAF2 aggregation in NF-cB activation by the first 45 amino acids of the LMP1 CT and suggest that a different TRAF-related pathway may be involved in NF-KB activation by the last 55 amino acids of the LMP1 CT.
Journal of Virology
In this study, we investigated the induction of cellular gene expression by the Epstein-Barr Virus (EBV) latent membrane protein 1 (LMP1). Previously, LMP1 was shown to induce the expression of ICAM-1, LFA-3, CD40, and EBI3 in EBV-negative Burkitt lymphoma (BL) cells and of the epidermal growth factor receptor (EGF-R) in epithelial cells. We now show that LMP1 expression also increased Fas and tumor necrosis factor receptor-associated factor 1 (TRAF1) in BL cells. LMP1 mediates NF-κB activation via two independent domains located in its C-terminal cytoplasmic tail, a TRAF-interacting site that associates with TRAF1, -2, -3, and -5 through a PXQXT/S core motif and a TRADD-interacting site. In EBV-transformed B cells or transiently transfected BL cells, significant amounts of TRAF1, -2, -3, and -5 are associated with LMP1. In epithelial cells, very little TRAF1 is expressed, and only TRAF2, -3, and -5, are significantly complexed with LMP1. The importance of TRAF binding to the PXQXT/...
Journal of Biological Chemistry, 2003
Latent membrane protein 1 (LMP1), an Epstein-Barr virus transforming protein, is able to activate NF-B through its carboxyl-terminal activation region 1 (CTAR1) and 2 (CTAR2), but the exact role of each domain is not fully understood. Here we show that LMP1 activates NF-B in different NF-B essential modulator (NEMO)-defective cell lines, but not in cells lacking both IB kinase 1 (IKK1) and 2 (IKK2). Mutational studies reveal that CTAR1, but not CTAR2, mediates NEMOindependent NF-B activation and that this process largely depends on IKK1. Retroviral expression of LMP1 mutants in cells lacking either functional NF-B inducing kinase (NIK), NEMO, IKK1, or IKK2 further illustrates distinct signals from the two activation regions of LMP1 for persistent NF-B activation. One originates in CTAR2, operates through the canonical NEMO-dependent pathway, and induces NFKB2 p100 production; the second signal originates in CTAR1, utilizes NIK and IKK1, and induces the processing of p100. Our results thus help clarify how two functional domains of LMP1 persistently activate NF-B through distinct signaling pathways. Latent membrane protein-1 (LMP1) 1 is an oncogenic transmembrane protein encoded by Epstein-Barr virus (1-3) that is known to activate NF-B (4, 5), the c-Jun NH 2-terminal kinase pathway (6), and its downstream transcription factors such as AP-1 (6-8), Janus-activating tyrosine kinase 3 and signal transducer and activator of transcription (9), and p38 mitogenactivated protein kinase (10). Previous studies demonstrated that NF-B activation by LMP1 plays a pivotal role in its transforming activity (11-13). LMP1 is a constitutively active
Biological Chemistry, 2000
The pro-apoptotic tumor necrosis factor (TNF)-receptor 1-associated death domain protein (TRADD) was initially identified as the central signaling adapter molecule of TNF-receptor 1 (TNFR1). Upon stimulation with the pro-inflammatory cytokine TNFα, TRADD is recruited to the activated TNFR1 by direct interaction between the death domains of both molecules. TRADD mediates TNFR1 activation of NF-κB and c-Jun N-terminal kinase (JNK), as well as caspase-dependent apoptosis. Surprisingly, TRADD is also recruited by latent membrane protein 1 (LMP1), the major oncoprotein of the human Epstein-Barr tumor virus. By mimicking a constitutively active receptor, LMP1 is essential for B-cell transformation by the virus, activating NF-κB, phosphatidylinositol 3-kinase, JAK/STAT and mitogen-activated protein kinase signaling. In contrast to TNFR1, LMP1's interaction with TRADD is independent of a functional death domain. The unique structure of the LMP1-TRADD complex dictates an unusual type of ...