Epstein-Barr virus latent membrane protein 1: Structure and functions

The Epstein-Barr virus latent membrane protein (LMP) 1 is a versatile protein that has profound effects on target cells through its effect on constitutive cellular proteins, e.g. TRAFs, TRADD, RIP, JAK3, BRAM1, and p85. LMP1 can stimulate or inhibit signaling pathways, resulting in transformation of rodent fibroblast cell lines, blockade of differentiation in epithelial cells, upregulation of antiapoptotic proteins, production of cytokines, upregulation of cell surface markers, upregulation of DNA methyltransferase activity, and downregulation of cell adhesion molecules and cyclin-dependent kinases. Overall, this results in greater transformation and survival in LMP1-expressing cells. Within nasopharyngeal carcinoma biopsy tissues, a naturally occurring LMP1 variant has been identified as having a 10-amino acid deletion in the C-terminus that seems to confer greater transformation potential than non-deleted LMP1. The role of LMP1 as a viral oncogene and its interaction with cellular factors are discussed.