Study the Regulation of De Novo Methyltransferases-Dnmt3a and Dnmt3b by Latent Membrane Protein 1 of Epstein-Barr Virus

Latent membrane protein 1 (LMP1) is an oncogene of Epstein-Barr virus (EBV); it can activate several signaling pathways through its C-terminus to achieve transformation of cells. In our recent study, LMP1 induces cell migration via a mechanism that involves activation of DNA methyltransferases (DNMT) 1, 3a and 3b, resulting in hypermethylation and silencing of a cellular E-cadherin gene, which indicates that LMP1 regulates cellular genes via DNA methylation machinery. The activation of de novo methyltransferase- dnmt3a and dnmt3b genes is now considered as the key step toward transformation of cells. In addition, it has been reported that differential splicing isoforms and promoter polymorphisms of dnmt3a and dnmt3b could account to predisposition to certain cancers or affect their enzymatic activity. However, the mechanisms responsible for initiation of activation of dnmt3a and dnmt3b are still obscure and significance of differential splicing variants or polymorphism of de novo methyltransferases are emergent to be explored in EBV associated NPC. In order to elucidate the regulation of dnmt3a and dnmt3b genes, to identify the splicing isoforms of dnmt genes in NPC biopsies, to examine if LMP1 can induce certain types of splicing isoforms, and to investigate if polymorphisms of dnmt genes exists in EBV associated diseases, the activation of dnmt3a and dnmt3b by LMP1 will be served as a model system in this project to elucidate the signaling involving in regulation of both de novo methyltransferases and also to identify either the splicing isoform or polymorphism exist in LMP1-expressing cells. The specific aims of this three-year project are listed as follows. (1). To identify the major transcripts of dnmt3a and dnmt3b genes in LMP1-expressing cells (2). To examine the significance of the polymorphisms of dnmt promoters region and splicing isoforms of dnmt transcripts in LMP1-expressing cells or NPC biopies. (3). To determine the major promoter usage of de novo dnmt genes in LMP1-expressing cells (4). To evaluate signaling pathways involved in LMP1-mediated activation of dnmt3a and dnmt3b promoters. (5). To correlate the expression of LMP1-activated downstream signaling mediators involved in regulation of dnmt genes, expression of dnmt genes and LMP1 genes in NPC biopsies.

Project ID:PC9308-2230
External Project ID:NSC93-2321-B182-006