Differentiation-Dependent KLF4 Expression Promotes Lytic Epstein-Barr Virus Infection in Epithelial Cells

• Published in: PLoS pathogens 2015-10, Vol.11 (10), p.e1005195-e1005195
• Main Authors: Nawandar, Dhananjay M, Wang, Anqi, Makielski, Kathleen, Lee, Denis, Ma, Shidong, Barlow, Elizabeth, Reusch, Jessica, Jiang, Ru, Wille, Coral K, Greenspan, Deborah, Greenspan, John S, Mertz, Janet E, Hutt-Fletcher, Lindsey, Johannsen, Eric C, Lambert, Paul F, Kenney, Shannon C
• Format: Article
• Language: English
• Subjects: Adult; Care and treatment; Cell differentiation; Cell Differentiation - physiology; Cell Line; Chromatin Immunoprecipitation; Complications and side effects; Deoxyribonucleic acid; Development and progression; DNA; Epithelial Cells - pathology; Epithelial Cells - virology; Epstein-Barr virus diseases; Epstein-Barr Virus Infections - metabolism; Fluorescent Antibody Technique; Gene expression; Genetic aspects; Host-Pathogen Interactions - physiology; Humans; Immunohistochemistry; In Situ Hybridization, Fluorescence; Infections; Kruppel-Like Transcription Factors - metabolism; Laser Capture Microdissection; Leukoplakia, Hairy - metabolism; Lymphoma; Mutagenesis, Site-Directed; Polymerase Chain Reaction; Positive Regulatory Domain I-Binding Factor 1; Proteins; Repressor Proteins - metabolism; Rodents; Telomerase; Transcription factors; Tumors; Viral infections; Virus Activation - physiology; Virus diseases; Virus Latency - physiology
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1005195

Epstein-Barr virus (EBV) is a human herpesvirus associated with B-cell and epithelial cell malignancies. EBV lytically infects normal differentiated oral epithelial cells, where it causes a tongue lesion known as oral hairy leukoplakia (OHL) in immunosuppressed patients. However, the cellular mechanism(s) that enable EBV to establish exclusively lytic infection in normal differentiated oral epithelial cells are not currently understood. Here we show that a cellular transcription factor known to promote epithelial cell differentiation, KLF4, induces differentiation-dependent lytic EBV infection by binding to and activating the two EBV immediate-early gene (BZLF1 and BRLF1) promoters. We demonstrate that latently EBV-infected, telomerase-immortalized normal oral keratinocyte (NOKs) cells undergo lytic viral reactivation confined to the more differentiated cell layers in organotypic raft culture. Furthermore, we show that endogenous KLF4 expression is required for efficient lytic viral reactivation in response to phorbol ester and sodium butyrate treatment in several different EBV-infected epithelial cell lines, and that the combination of KLF4 and another differentiation-dependent cellular transcription factor, BLIMP1, is highly synergistic for inducing lytic EBV infection. We confirm that both KLF4 and BLIMP1 are expressed in differentiated, but not undifferentiated, epithelial cells in normal tongue tissue, and show that KLF4 and BLIMP1 are both expressed in a patient-derived OHL lesion. In contrast, KLF4 protein is not detectably expressed in B cells, where EBV normally enters latent infection, although KLF4 over-expression is sufficient to induce lytic EBV reactivation in Burkitt lymphoma cells. Thus, KLF4, together with BLIMP1, plays a critical role in mediating lytic EBV reactivation in epithelial cells.