title: Epstein-Barr virus latent infection membrane protein 1 TRAF-binding site induces NIK/IKK alpha-dependent noncanonical NF-kappaB activation.
abstract: Epstein-Barr virus (EBV) latent infection membrane protein 1 (LMP1)-induced NF-kappaB activation is important for infected cell survival. LMP1 activates NF-kappaB, in part, by engaging tumor necrosis factor (TNF) receptor-associated factors (TRAFs), which also mediate NF-kappaB activation from LTbetaR and CD40. LTbetaR and CD40 activation of p100/NF-kappaB2 is now known to be NIK/IKKalpha-dependent and IKKbeta/IKKgamma independent. In the experiments described here, we found that EBV LMP1 induced p100/NF-kappaB2 processing in human lymphoblasts and HEK293 cells. LMP1-induced p100 processing was NIK/IKKalpha dependent and IKKbeta/IKKgamma 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), IKKbeta was essential for LMP1 up-regulation of macrophage inflammatory protein (MIP)-2, TNFalpha, I-TAC, ELC, MIG, and CXCR4 RNAs. Interestingly, in IKKalpha knockout MEFs, LMP1 hyperinduced MIP-2, TNFalpha, and I-TAC expression, consistent with a role for IKKalpha in down-modulating canonical IKKbeta activation or its effects. In contrast, LMP1 failed to up-regulate CXCR4 and MIG RNA in IKKalpha knockout MEFs, indicating a dependence on noncanonical IKKalpha activation. Furthermore, LMP1 up-regulation of MIP-2 RNA in MEFs was both IKKbeta- and IKKgamma-dependent, whereas LMP1 upregulation of MIG and I-TAC RNA was fully IKKgamma independent. Thus, LMP1 induces typical canonical IKKbeta/IKKgamma-dependent, atypical canonical IKKbeta-dependent/IKKgamma-independent, and noncanonical NIK/IKKalpha-dependent NF-kappaB activations; NIK/IKKalpha-dependent NF-kappaB activation is principally mediated by the LMP1 TRAF-binding site.
authors.affiliation: Department of Microbiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Micah
authors.initials: M
authors.lastname: Luftig
authors.forename: Teruhito
authors.initials: T
authors.lastname: Yasui
authors.forename: Vishal
authors.initials: V
authors.lastname: Soni
authors.forename: Myung-Soo
authors.initials: MS
authors.lastname: Kang
authors.forename: Nils
authors.initials: N
authors.lastname: Jacobson
authors.forename: Ellen
authors.initials: E
authors.lastname: Cahir-McFarland
authors.forename: Brian
authors.initials: B
authors.lastname: Seed
authors.forename: Elliott
authors.initials: E
authors.lastname: Kieff
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism / Q000821:virology; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D006801:Humans; D051550:I-kappa B Kinase; D051379:Mice; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D012313:RNA / Q000235:genetics / Q000378:metabolism; D047990:TNF Receptor-Associated Factor 1; D014763:Viral Matrix Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000097782:NF-kappaB-Inducing Kinase
chemical_list: D051550:I-kappa B Kinase; D016328:NF-kappa B; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D012313:RNA; D047990:TNF Receptor-Associated Factor 1; D014763:Viral Matrix Proteins; D000097782:NF-kappaB-Inducing Kinase; C037662:EBV-associated membrane antigen, Epstein-Barr virus; C496559:CHUK protein, human; C496564:Chuk protein, mouse; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse