Epstein-Barr virus nuclear antigen 2 transactivates latent membrane protein LMP1

Abstract

Several lines of evidence are compatible with the hypothesis that Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA-2) or leader protein (EBNA-LP) affects expression of the EBV latent infection membrane protein LMP1. We now demonstrate the following. (i) Acute transfection and expression of EBNA-2 under control of simian virus 40 or Moloney murine leukemia virus promoters resulted in increased LMP1 expression in P3HR-1-infected Burkitt's lymphoma cells and the P3HR-1 or Daudi cell line. (ii) Transfection and expression of EBNA-LP alone had no effect on LMP1 expression and did not act synergistically with EBNA-2 to affect LMP1 expression. (iii) LMP1 expression in Daudi and P3HR-l-infected cells was controlled at the mRNA level, and EBNA-2 expression in Daudi cells increased LMP1 mRNA. (iv) No other EBV genes were required for EBNA-2 transactivation of LMP1 since cotransfection of recombinant EBNA-2 expression vectors and genomic LMP1 DNA fragments enhanced LMP1 expression in the EBV-negative B-lymphoma cell lines BJAB, Louckes, and BL30. (v) An EBNA-2-responsive element was found within the-512 to +40 LMP1 DNA since this DNA linked to a chloramphenicol acetyltransferase reporter gene was transactivated by cotransfection with an EBNA-2 expression vector. (vi) The EBV type 2 EBNA-2 transactivated LMP1 as well as the EBV type 1 EBNA-2. (vii) Two deletions within the EBNA-2 gene which rendered EBV transformation incompetent did not transactivate LMP1, whereas a transformation-competent EBNA-2 deletion mutant did transactivate LMP1. LMP1 is a potent effector of B-lymphocyte activation and can act synergistically with EBNA-2 to induce cellular CD23 gene expression. Thus, EBNA-2 transactivation of LMP1 amplifies the biological impact of EBNA-2 and underscores its central role in EBV-induced growth transformation.

Induced CD25 Expression in a Human B‐Lymphoma Cell Line Transfected with the Epstein‐Barr Virus Nuclear Antigen 2 Gene

“…4A). This little or no effect in the transiently EBNA-2-expressing cells in this study is well consistent with the experimental result of EBNA-2 on the activity of SV40 promoter in pSV2CAT mentioned by Wang et al (49).…”

“…It has been recently reported that EBNA-2 exerted a simulatory effect on the level of c-fgr RNA (19) and an interference with the interferon-induced anti-proliferative response (2). It has been also reported that EBNA-2 transactivated the expression of LMP1 and the terminal protein (LMP2) which are encoded by the EBV genome (1,14,49,50). Thus, EBNA-2 is considered to hold multiple effects on the expression of a variety of cellular and viral genes.…”

Expression of epstein‐barr‐virus‐related nuclear antigens and B‐cell markers in lymphomas of SIV‐immunosuppressed monkeys

“…Some simian EB viruses can immortalize B cells in vitro (Rabin et af., 1977), although this remains to be established for cyno-EBV. However, EBNA2 has multiple other functions, including regulation of LMPl expression and EBNA transcription (Wang et at,, 1990). No LMPl reactivity could be demonstrated in the monkey lymphoma cells with 2 monospecific reagents, which is in line with the low homology of the LMP-coding sequence between EBV and cyno-EBV (Feichtinger et al,199%).…”

DNA of lymphoma‐associated herpesvirus (HVMF1) in SIV‐infected monkeys (Macaca fascicularis) shows homologies to EBNA‐1, ‐2 and ‐5 genes

“…In Southern blotting, a homologous DNA region was also detected by a probe covering the right part of the BYRF1-exon. EBNA2 has been shown to be necessary for initiation of EBV-induced immortalization (Cohen et al, 1989), to induce the viral LMP1, the NFkB transcription factor and several cellular proteins, in particular the CD 21-CD 23 complex, which may serve as an autocrine growth factor of EBV-infected B cells (Wang et aL, 1990(Wang et aL, , 1991. It is of interest that a CD23 cross-reacting protein was also found in most monkey lymphomas (Li et al, 1993).…”

“…It is of interest that a CD23 cross-reacting protein was also found in most monkey lymphomas (Li et al, 1993). EBNA2 is also involved in the regulation of several promoters for other latent viral proteins, the BCRZpromoter, and the promoters controlling expression of LMP1, LMP2a and LMP2b (Fahraeus et al, 1990;Wang et al, 1990). One may assume that CYNA2 has similar vital functions.…”