The Epstein-Barr virus immediate-early protein BZLF1 induces expression of E2F-1 and other proteins involved in cell cycle progression in primary keratinocytes and gastric carcinoma cells.
The Epstein-Barr virus (EBV) immediate-early protein BZLF1 mediates the switch between the latent and lytic forms of EBV infection and has been previously shown to induce a G(1)/S block in cell cycle progression in some cell types. To examine the effect of BZLF1 on cellular gene expression, we performed microarray analysis on telomerase-immortalized human keratinocytes that were mock infected or infected with a control adenovirus vector (AdLacZ) or a vector expressing the EBV BZLF1 protein (AdBZLF1). Cellular genes activated by BZLF1 expression included E2F-1, cyclin E, Cdc25A, and a number of other genes involved in cell cycle progression. Immunoblot analysis confirmed that BZLF1 induced expression of E2F-1, cyclin E, Cdc25A, and stem loop binding protein (a protein known to be primarily expressed during S phase) in telomerase-immortalized keratinocytes. Similarly, BZLF1 increased expression of E2F-1, cyclin E, and stem loop binding protein (SLBP) in primary tonsil keratinocytes. In contrast, BZLF1 did not induce E2F-1 expression in normal human fibroblasts. Cell cycle analysis revealed that while BZLF1 dramatically blocked G(1)/S progression in normal human fibroblasts, it did not significantly affect cell cycle progression in primary human tonsil keratinocytes. Furthermore, in EBV-infected gastric carcinoma cells, the BZLF1-positive cells had an increased number of cells in S phase compared to the BZLF1-negative cells. Thus, in certain cell types (but not others), BZLF1 enhances expression of cellular proteins associated with cell cycle progression, which suggests that an S-phase-like environment may be advantageous for efficient lytic EBV replication in some cell types.
Mauser
Amy
A
Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295, USA.
Holley-Guthrie
Elizabeth
E
Zanation
Adam
A
Yarborough
Wendall
W
Kaufmann
William
W
Klingelhutz
Aloysius
A
Seaman
William T
WT
Kenney
Shannon
S
D000256:Adenoviridae / Q000235:genetics; D017209:Apoptosis; D001402:B-Lymphocytes / Q000166:cytology / Q000821:virology; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D019927:Cyclin E / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000502:physiology*; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D016193:G1 Phase; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D016196:S Phase; D013274:Stomach Neoplasms / Q000378:metabolism / Q000473:pathology; D019098:Telomerase / Q000235:genetics; D015534:Trans-Activators / Q000502:physiology*; D014157:Transcription Factors / Q000096:biosynthesis*; D016159:Tumor Suppressor Protein p53 / Q000032:analysis; D014764:Viral Proteins
C063676:BZLF1 protein, Herpesvirus 4, Human; D018797:Cell Cycle Proteins; D019927:Cyclin E; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D014764:Viral Proteins; D019098:Telomerase