Epstein-Barr virus EBNA-3C is targeted to and regulates expression from the bidirectional LMP-1/2B promoter.
Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA-3C) is essential for EBV-mediated immortalization of human B lymphocytes and regulates both the cell cycle and transcription. Transient reporter gene assays have implicated a pivotal role for EBNA-3C in the regulation of transcription of the majority of latency-associated genes expressed during the EBV growth program, including the viral oncoprotein LMP-1. To examine the regulation of latency gene expression by EBNA-3C, we generated an EBV-positive cell line that inducibly expresses EBNA-3C. This cell line allowed us to examine expression from the endogenous latency gene promoters in the context of an actual latent infection and the presence of other EBNA proteins, in particular EBNA-2, which is presumed to coregulate transcription with EBNA-3C. EBNA-3C induced the expression of both LMP-1 and LMP-2B mRNAs from the bidirectional LMP-1/LMP-2B promoter. In contrast, no effect was seen on expression from the common EBNA promoter Cp, which is responsive to EBNA-3C in reporter assays. Activation of LMP expression was not the consequence of increases in EBNA-2, PU.1 or Spi-B transcription factors, all of which are believed to be critical for activation of LMP-1. Chromatin immunoprecipitation assays furthermore indicated that EBNA-3C is present at the bidirectional LMP-1/LMP-2B promoter. These results indicate that EBNA-3C directly activates the expression of LMP-1 and LMP-2B but is unlikely to significantly regulate EBNA expression via Cp under normal growth conditions.
Jiménez-Ramírez
Carmilia
C
Department of Biochemistry, MS 340, 332 North Lauderdale Street, Memphis, TN 38105, USA.
Brooks
Andrew J
AJ
Forshell
Linus Plym
LP
Yakimchuk
Konstantin
K
Zhao
Bo
B
Fulgham
Tacha Zi
TZ
Sample
Clare E
CE
D000956:Antigens, Viral / Q000378:metabolism* / Q000502:physiology; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D019309:Epstein-Barr Virus Nuclear Antigens / Q000032:analysis; D015967:Gene Expression Regulation, Viral; D004854:Herpesvirus 4, Human / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000032:analysis; D012367:RNA, Viral / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000032:analysis; D014157:Transcription Factors / Q000032:analysis; D014763:Viral Matrix Proteins / Q000096:biosynthesis / Q000235:genetics*; D014764:Viral Proteins / Q000032:analysis; D000099232:Proto-Oncogene Protein Spi-1
D000956:Antigens, Viral; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D019309:Epstein-Barr Virus Nuclear Antigens; D011518:Proto-Oncogene Proteins; D012367:RNA, Viral; D015534:Trans-Activators; D014157:Transcription Factors; D014763:Viral Matrix Proteins; D014764:Viral Proteins; D000099232:Proto-Oncogene Protein Spi-1; C402641:EBNA-2 protein, Human herpesvirus 4; C498774:EBNA-3C, epstein-barr virus; C037662:EBV-associated membrane antigen, Epstein-Barr virus; C076877:SPIB protein, human