Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2) association with RBP-J is essential for regulation of virus and cell gene transcription and B lymphocyte transformation into infinitely proliferating lymphoblastoid cells (LCLs). To identify EBNA2-regulated cell genes in LCLs, an EBV recombinant that expresses EBNA2 with its C terminus fused in frame to a 4-hydroxytamoxifen (4HT)-dependent mutant estrogen receptor (E2HTF) was used to transform primary B lymphocytes to LCLs. In the presence of 4HT, E2HTF expression level and effects on the LMP1 promoter in transfected BJAB lymphoblasts were similar to EBNA2. In 4HT-supplemented medium, E2HTF EBV recombinant infected LCLs were also similar to EBNA2 LCLs in outgrowth but required higher serum and a restricted range of cell concentrations for consistent growth. In medium without 4HT, E2HTF localized to the cytoplasm, c-myc levels substantially decreased within 6 h, cells stopped growing, and levels of other EBNAs and LMP1 remained stable for 24 h. Over this 24-h period, 30 cell RNAs decreased 2-fold, and 51 other RNAs decreased 1.5-fold. These RNAs encode proteins important in cell adhesion or signaling, transcription, RNA processing, cell-cycle regulation, and survival. Real-time RT-PCR confirmed EBNA2-dependent expression of eight RNAs.
RBP-J ͞CBF1 ͉ c-mycI n primary human infection, Epstein-Barr virus (EBV) establishes a latency III (LTIII) infection in B lymphocytes, which is characterized by expression of EBV-encoded nuclear antigens (EBNAs), integral membrane proteins (LMP1 and LMP2), small RNAs (EBERs), and Bam A rightward transcripts. LTIII-infected cell lymphoproliferation is limited by T cell immune responses to EBNAs and LMPs (1, 2). EBNA2 and EBNALP are the first EBV proteins expressed in B lymphocyte infection (1). EBNALP and EBNA2 enhance their upstream promoters, Cp or Wp, which results in transcription of not only EBNALP and EBNA2 but also EBNA3A, EBNA3B, EBNA3C, and EBNA1 (for review see ref. 1). EBNA2 and EBNALP also turn on the EBV LMP1, LMP2B, and LMP2A promoters. EBNA2 directly or indirectly up-regulates B lymphocyte CD21, CD23, c-myc, AML2, BATF, IL16, IL18r, c-fgr, cyclin D2, cdk4, TNF-␣, lymphotoxin, HES1, and G-CSF RNAs (1, 3-7).EBNA2 stably associates with the sequence-specific DNA binding protein RBP-J ͞CBF1 (1), which has at least one cognate site within 500 bp upstream of the Cp, LMP1, LMP2A, and CD23 promoters and within the first intron of the CD21 promoter. EBNALP coactivates with EBNA2 by interaction with the EBNA2 acidic transcriptional activation domain, association with HA95 and PKA, and displacement of HP1␣ from PML bodies (1,(8)(9)(10). The EBNA2 acidic transcriptional activation domain recruits basal and activation-related transcription factors, TAF40, TFIIB, TFIIH, p300͞CBP, PCAF histone acetyltransferases, and a p100 transcription coactivator to promoters (1, 11). The EBNA2 RBP-J association and acidic activating domains are essential for B lymphocyte conversion to lymphoblastoid cells (LCLs) (1). Furthermore, EBNA3A polypept...