Contribution of C/EBP proteins to Epstein-Barr virus lytic gene expression and replication in epithelial cells

J Virol. 2006 Feb;80(3):1098-109. doi: 10.1128/JVI.80.3.1098-1109.2006.


The contribution of C/EBP proteins to Epstein-Barr virus (EBV) lytic gene expression and replication in epithelial cells was examined. Nasopharyngeal carcinoma cell lines constitutively expressed C/EBPbeta and had limited C/EBPalpha expression, while the AGS gastric cancer cell line expressed significant levels of both C/EBPalpha and C/EBPbeta. Induction of the lytic cycle in EBV-positive AGS/BX1 cells with phorbol ester and sodium butyrate treatment led to a transient stimulation of C/EBPbeta expression and a prolonged increase in C/EBPalpha expression. In AGS/BX1 cells, endogenous C/EBPalpha and C/EBPbeta proteins were detected associated with the ZTA and oriLyt promoters but not the RTA promoter. Electrophoretic mobility shift assays confirmed binding of C/EBP proteins to multiple sites in the ZTA and oriLyt promoters. The response of these promoters in reporter assays to transfected C/EBPalpha and C/EBPbeta proteins was consistent with the promoter binding assays and emphasized the relative importance of C/EBPs for activation of the ZTA promoter. Mutation of the oriLyt promoter proximal C/EBP site had little effect on ZTA activation of the promoter in a reporter assay. However, this mutation impaired oriLyt DNA replication, suggesting a separate replication-specific contribution for C/EBP proteins. Finally, the overall importance of C/EBP proteins for lytic gene expression was demonstrated using CHOP10 to antagonize C/EBP DNA binding activity. Introduction of CHOP10 significantly impaired induction of the ZTA, RTA, and BMRF1 proteins in chemically treated AGS/BX1 cells. Thus, C/EBPbeta and C/EBPalpha expression are associated with lytic induction in AGS cells, and expression of C/EBP proteins in epithelial cells may contribute to the tendency of these cells to exhibit constitutive low-level ZTA promoter activity.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Antigens, Viral / biosynthesis
  • Antigens, Viral / genetics
  • Base Sequence
  • CCAAT-Enhancer-Binding Proteins / genetics
  • CCAAT-Enhancer-Binding Proteins / metabolism*
  • Cell Line, Tumor
  • DNA, Viral / genetics
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / genetics
  • Epithelial Cells / metabolism
  • Epithelial Cells / virology
  • Gene Expression
  • Genes, Viral
  • HeLa Cells
  • Herpesvirus 4, Human / genetics*
  • Herpesvirus 4, Human / physiology*
  • Humans
  • Immediate-Early Proteins / biosynthesis
  • Immediate-Early Proteins / genetics
  • Promoter Regions, Genetic
  • Trans-Activators / biosynthesis
  • Trans-Activators / genetics
  • Viral Proteins / biosynthesis
  • Viral Proteins / genetics
  • Virus Replication


  • Antigens, Viral
  • BRLF1 protein, Human herpesvirus 4
  • BZLF1 protein, Herpesvirus 4, Human
  • CCAAT-Enhancer-Binding Proteins
  • DNA, Viral
  • DNA-Binding Proteins
  • Epstein-Barr virus early antigen diffuse component
  • Immediate-Early Proteins
  • Trans-Activators
  • Viral Proteins