title: RelB nuclear translocation mediated by C-terminal activator regions of Epstein-Barr virus-encoded latent membrane protein 1 and its effect on antigen-presenting function in B cells.
abstract: Previous studies have shown that Epstein-Barr virus-encoded latent membrane protein 1 (LMP1) is uniquely able to up-regulate the expression of the peptide transporters (referred to as TAP-1 and TAP-2) and major histocompatibility complex (MHC) class I in Burkitt's lymphoma (BL) cell lines. This up-regulation is often accompanied by a restoration of antigen-presenting function as measured by the ability of these cells to present endogenously expressed viral antigen to cytotoxic T lymphocytes. Here we show that the expression of LMP1 resulted in up-regulation and nuclear translocation of RelB that were coincident with increased expression of MHC class I in BL cells. Deletion of the C-terminal activator regions (CTARs) of LMP1 significantly impaired the abilities of LMP1 to translocate RelB into the nucleus and to up-regulate the expression of antigen-processing genes. Further analysis with single-point mutations within the CTARs confirmed that the residues critical for NF-kappa B activation directly contribute to antigen-processing function regulation in BL cells. This LMP1-mediated effect was blocked following expression of either dominant negative I kappa B alpha S32/36A, an NF-kappa B inhibitor, or antisense RelB. These observations indicate that upregulation of antigen-presenting function in B cells mediated by LMP1 is signaled through the NF-kappa B subunit RelB. The data provide a mechanism by which LMP1 modulates immunogenicity of Epstein-Barr virus-infected normal and malignant cells.
authors.affiliation: Tumour Immunology Laboratory, Division of Infectious Diseases and Immunology, Queensland Institute of Medical Research and Joint Oncology Program, University of Queensland, Brisbane, Queensland 4029, Australia.
authors.forename: Saparna
authors.initials: S
authors.lastname: Pai
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: O'Sullivan
authors.forename: Leanne
authors.initials: L
authors.lastname: Cooper
authors.forename: Ranjeny
authors.initials: R
authors.lastname: Thomas
authors.forename: Rajiv
authors.initials: R
authors.lastname: Khanna
mesh_terms: D021581:Active Transport, Cell Nucleus; D017951:Antigen Presentation / Q000235:genetics* / Q000502:physiology; D001402:B-Lymphocytes / Q000276:immunology / Q000821:virology*; D002051:Burkitt Lymphoma / Q000821:virology; D002461:Cell Line, Transformed; D002467:Cell Nucleus / Q000378:metabolism; D020031:Epstein-Barr Virus Infections / Q000821:virology; D015967:Gene Expression Regulation, Viral; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000502:physiology*; D006801:Humans; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051841:Transcription Factor RelB; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014763:Viral Matrix Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C037662:EBV-associated membrane antigen, Epstein-Barr virus; D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; C497593:RELB protein, human; D014157:Transcription Factors; D014763:Viral Matrix Proteins; D051841:Transcription Factor RelB