title: Characterization of 5'-upstream sequence of the latent membrane protein 1 (LMP-1) gene of an Epstein-Barr virus identified in nasopharyngeal carcinoma tissues.
abstract: Sequence variations of the 5'-upstream region of latent membrane protein 1 (LMP-1) in two Epstein-Barr virus (EBV) strains have been reported before (Chen et al., 1992). To investigate the effect of these variations on gene expression, we constructed a series of deletion plasmids encompassing positions -950 to +20 of the LMP-1 promoter region and tested for the ability to drive chloramphenicol acetyltransferase (CAT) gene expression in C33A cells. Results showed that the promoter activities of constructs from NPC strain were 3-fold lower than the corresponding constructs from the B95-8 strain. In addition, the region between -54 and +20 contained the basic, constitutive promoter activity for both strains. Sequence analysis of this region indicated that an activating transcription factor (ATF) binding site, TGACGTAG, which is present in B95-8 strain was changed to TCTCGTAG in NPC strain. A chimeric plasmid study suggested that these sequence variations in the ATF binding site may contribute to the 3-fold increase of CAT activity observed for B95-8 strain. Furthermore, the activity of the promoter constructs was not activated by EBV-encoded nuclear antigen 2 (EBNA-2) in C33A cells. However, the promoter activities were upregulated in B-lymphocyte cells such as CG3 and CA46 cells. The biological significance of this difference in promoter activity of LMP-1 gene between two strains and the involvement of the cellular factors were discussed.
mesh_terms: D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000821:virology*; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D004279:DNA, Viral; D015967:Gene Expression Regulation, Viral; D004854:Herpesvirus 4, Human / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008969:Molecular Sequence Data; D009303:Nasopharyngeal Neoplasms / Q000821:virology*; D011401:Promoter Regions, Genetic; D014407:Tumor Cells, Cultured; D014763:Viral Matrix Proteins / Q000235:genetics*
chemical_list: D004279:DNA, Viral; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D014763:Viral Matrix Proteins; D015500:Chloramphenicol O-Acetyltransferase