THE EPSTEIN-BARR-VIRUS ONCOGENE PRODUCT LATENT MEMBRANE-PROTEIN-1 ENGAGES THE TUMOR-NECROSIS-FACTOR RECEPTOR-ASSOCIATED DEATH DOMAIN PROTEIN TO MEDIATE B-LYMPHOCYTE GROWTH TRANSFORMATION AND ACTIVATE NF-KAPPA-B

The Epstein-Barr virus latent membrane protein 1 (LMP1) is essential f or the transformation of B lymphocytes into lymphoblastoid cell lines, Previous data are consistent with a model that LMP1 is a constitutive ly activated receptor that transduces signals for transformation throu gh its carboxyl-terminal cytoplasmic tail, One transformation effector site (TES1), located within the membrane proximal 45 residues of the cytoplasmic tail, constitutively engages tumor necrosis factor recepto r-associated factors. Signals from TES1 are sufficient to drive initia l proliferation of infected resting B lymphocytes, but most lymphoblas toid cells infected with a virus that does not express the 155 residue s beyond TES1 fail to grow as long-term cell lines, We now find that m utating two tyrosines to an isoleucine at the carboxyl end of the cyto plasmic tail cripples the ability of EBV to cause lymphoblastoid cell outgrowth, thereby marking a second transformation effector site, TES2 , A yeast two-hybrid screen identified TES2 interacting proteins, incl uding the tumor necrosis factor receptor-associated death domain prote in (TRADD), TRADD was the only protein that interacted with wild-type TES2 and not with isoleucine-mutated TES2, TRADD associated with wild- type LMP1 but not with isoleucine-mutated LMP1 in mammalian cells, and TRADD constitutively associated with LMP1 in EBV-transformed cells, I n transfection assays, TRADD and TES2 synergistically mediated high-le vel NF-kappa B activation, These results indicate that LMP1 appropriat es TRADD to enable efficient long-term lymphoblastoid cell outgrowth. High-level NF-kappa B activation also appears to be a critical compone nt of long-term outgrowth.