ZEB1 Regulates the Latent-Lytic Switch in Infection by Epstein-Barr Virus

Abstract

The immediate-early (IE) BZLF1 gene of Epstein-Barr virus (EBV) regulates the switch between latent and lytic infection by EBV. We previously showed that the cellular transcription factor ZEB1 binds to a sequence element, ZV, located at nt −17 to −12 relative to the transcription initiation site of the BZLF1 promoter, Zp, repressing transcription from Zp in a transient transfection assay. Here, we report the phenotype in the context of a whole EBV genome of a variant of EBV strain B95.8 containing a 2-bp substitution mutation in the ZV element of Zp that reduced, but did not eliminate, ZEB1 binding to Zp. Strikingly, epithelial 293 cells latently infected with the EBV ZV mutant spontaneously produced IE-, early-, and late-gene products and infectious virus, while wild-type (WT)-infected 293 cells did not and have never been reported to do so. Furthermore, treatment with the chemical inducers sodium butyrate and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) led to an additional order-of-magnitude production of infectious virus in the ZV mutant–infected 293 cells, but still no virus in the WT-infected 293 cells. Similarly, ZV mutant–infected Burkitt's lymphoma BJAB cells accumulated at least 10-fold more EBV IE mRNAs than did WT-infected BJAB cells, with TPA or sodium butyrate treatment leading to an additional 5- to 10-fold accumulation of EBV IE mRNAs in the ZV mutant–infected cells. Thus, we conclude that ZEB1 binding to Zp plays a central role in regulating the latent-lytic switch in EBV-infected epithelial and B cells, suggesting ZEB1 as a target for lytic-induction therapies in EBV-associated malignancies.

Epstein-Barr Virus Blocks the Autophagic Flux and Appropriates the Autophagic Machinery To Enhance Viral Replication

“…Of note, 293 and 293/EBV cells were particularly helpful to distinguish the effect on autophagy mediated by ZEBRA per se from the effect mediated by the other EBV lytic genes in the same cell context. It is possible that ZEBRA promotes a complete autophagic flux to degrade transcriptional repressors that hamper EBV lytic replication (37), but further studies will be necessary to address this possibility. Based on our results, we suggest that a possible mechanism underlying the autophagic block observed in cells undergoing EBV replication is the downregulation of Rab7.…”

Cellular MicroRNAs 200b and 429 Regulate the Epstein-Barr Virus Switch between Latency and Lytic Replication

“…BZLF1 can also interact with several cellular proteins, affecting their activities and cellular localization, further contributing to viral reactivation (61, 74). Because of BZLF1's central role in reactivation of EBV out of latency into lytic replication, factors that regulate its expression have been implicated as potential therapeutics for treating patients with EBV-associated malignancies.Our laboratory previously reported that the cellular proteins ZEB1 (also known as ␦EF1, TCF8, AREB6, ZFHEP, NIL-2A, ZFHX1A, and BZP) and ZEB2 (also known as SIP1, SMA-DIP1, ZFHX1B, and KIAA0569) can both bind to a sequence element, termed ZV, located within the BZLF1 promoter, Zp (22,47,48,92); a second element, ZVЈ, synergizes with the ZV element for higher-affinity binding of the ZEBs to Zp via their two zinc fingers (Fig. 1A) (X. Yu, P. McCarthy, D. Gorlen, and J. E. Mertz, unpublished data).…”

Broadening Specificity and Enhancing Cytotoxicity of Adoptive T Cells for Nasopharyngeal Carcinoma Immunotherapy

“…As a first step, we used the TPA þ NaB combination as the most commonly used treatment to trigger EBV lytic reactivation (2,21). Healthy donor-derived LCLs treated for 48 hours with TPA þ NaB showed significantly increased BARF1 mRNA expression (2.5 mean fold-increase, P 0.05; Fig.…”

“…In fact, NPC is relatively rare in most parts of the world, particularly in Europe and North America, while it has a high incidence in southern China and southeast Asia, where it constitutes a significant health problem (1,2). NPC is characterized by several histopathologic entities, with the undifferentiated form being the most frequent (3,4).…”