Study of the Role of BRAM1in EBV LMP1-Mediated Functions

The latent membrane protein 1 of Epstein-Barr virus causes cellular transformation and actibates several intracellular signals, including NF-kB and JNK. Using yeast two-hybridk screenign with the LMP1 C-terminal sequence as bait, we demonstrate that Bone Morphogenetic Protein receptor-associatee molecule 1 is an LMP1-interacting protein. BRAM1 associates with LMP1, both in vitro and in vivo, as revealed by confocal microscopy, GST pull-down and co-immunoprecipitation assays. This association mainly involves the C-terminal half of BRAM1 comprising the MYND domain and the CTAR2 region of LMP1, which is critical in LMP1-mediated signaling pathways. BRAM1 interferes with LMP1-mediated NF-kB activtion, but not the JNK signaling pathway. Moreover, BRAM1 inhibits the resistance of LMP1 to TNF- -induced cytotoxicity. Therefore, BRAM1 molecule may function as a negative regulator for LMP1-mediated biological functions. In this proposal, we plan to examine the role of BRAM1 in signaling of LMP1-mediated NF-kB activation and to elucidate the biological role of BRAM1 in LMP1-mediated functions such as cell transformation, cell migration activity and tumor formation ability. In addition, BRAM1 is also associated with BMP receptor. However, the biological role of BRAM1 in BMP signaling is still unclear. BMP signaling involves cellular mediators Smad protein. Using these cellular mediator proteins, we will test if LMP1 can participate in the BMP signaling through these mediators. Finally, we will evaluate the exprssion of BRAM1 in nasopharyngeal carcinoma tissues and ask if there is mutation or modification in BRAM1 molecule occur in the tissue samples. From this study, we should be able to understand the role of a negative regulator in cells expressing LMP1 and the potential of using this molecule as a therapeutic drug for LMP1-positive tumors.

Project ID:PG9204-0408
External Project ID:NHRI-EX92-9214BI