Alternative Splicing Determines The Carboxy Terminus of the Epstein--Barr Virus Nuclear Antigen 5 Species Expressed in the Burkitt's Lymphoma Cell Line Daudi

Abstract

The Daudi strain of Epstein-Barr virus (EBV) possesses a genomic deletion, relative to the B95-8 EBV prototype, that removes the entire Epstein-Barr virus nuclear antigen 2 (EBNA2) open reading frame (ORF) and the sequences encoding the carboxy terminus of EBNA5. Immunoblot analysis carried out in this study indicates that two species of EBNA5 (31 K and 37K) are expressed in Daudi cells. Nucleotide sequence analysis of Daudi cDNA clones has confirmed that, as a consequence of the genomic deletion, exons usually appearing further downstream in EBNA messages (exons U or HF) are spliced directly onto the truncated EBNA50RF. Furthermore, the use of alternative splicing suggests that the two EBNA5 species expressed in Daudi cells possess different carboxy termini.

C-Terminal Region of EBNA-2 Determines the Superior Transforming Ability of Type 1 Epstein-Barr Virus by Enhanced Gene Regulation of LMP-1 and CXCR7

“…In several previous reports, depending on the antibodies used, one or two species of EBNA-LP (around 31 and 37 kDa) have been detected in Daudi cells, both lacking the Y1Y2 domain [87]–[90]. Here we used the 4D3 antibody and observed the 37 kDa isoform (Figure S1, lane 4), which corresponds to a 4-repeat species, as determined by comparison with the EBNA-LPs expressed in B95-8 and in 293 cells transiently transfected with plasmids coding for 3- or 7- repeat EBNA-LP as standards (Figure S1, lanes 1, 2 and 3).…”

The expression of p63 is associated with the differential stage in nasopharyngeal carcinoma and EBV infection

“…Like p53, p63 was rarely mutated but take high expression in NPC. High expression of p53 was indicated in inactive form due to the binding with EBNA5 in Burk's lymphocyte [ 31 , 32 ], and the complex of the two proteins led to increased accumulation of p53 in nuclei. p63 have a high amino acid identity to p53.…”

“…Initial studies suggested that it was involved in pathogenesis of NPC [ 2 , 4 , 28 - 30 ]. The Epstein-Barr virus nuclear antigen 5 (EBNA-5), highly spliced mRNA from the major IR1 (BamHI-W) repeat region of the virus genome, is proved to bind to p53 protein in Burk's lymphocyte [ 31 , 32 ]. The complex of the two proteins can increase the accumulation of the p53 in the nuclear.…”

The B cell-immortalizing functions of Epstein-Barr virus

“…Pearson et al (1987) characterized the protein encoded by the BHRF-1 open reading frame as an early lytic cycle antigen. However, a number of groups have shown that the BHRF-1 appears in highly spliced EBNA-like messages (Bodescot & Perricaudet, 1986;Pearson et al, 1987;Austin et al, 1988;Ring et al, 1992), suggesting that the BHRF-l-encoded protein may be expressed in latently infected B cells. The predicted BHRF-1 translation product has a potential hydrophobic aminoterminal signal sequence, a putative external or luminal domain of approximately 150 amino acids and a 21 residue hydrophobic potential transmembrane domain.…”

“…The non-immortalizing P3HR-1 and Daudi strains of EBV encode mutant EBNA-LP proteins owing to the deletion of the two exons that normally encode its carboxy terminus (Rabson et al, 1982;Jones et al, 1984). In fact, it has recently been shown that the carboxy terminus of the Daudi EBNA-LP species are determined by the alternative splicing of exons encoded downstream of the genomic deletion (Ring et al, 1992). EBNA-LP is highly phosphorylated (Pettiet al, 1990) and has been shown to co-localize in the cell with the retinoblastorna gene product, p 105 ~b (Jiang et al, 1991).…”