E2F1 Suppresses EBV Lytic Reactivation through Cellular and Viral Transcriptional Networks

Abstract

Latent EBV infection is causally associated with various B-cell malignancies, while periodic lytic-cycle replication is essential for sustaining viral progeny. Lytic cycle induction represents a promising therapeutic strategy for EBV-associated neoplasms. Therefore, uncovering the mechanisms that regulate EBV lytic-cycle reactivation is pivotal for understanding viral pathogenesis and advancing novel therapies. Our genome-wide transcriptomic analysis reveals that E2F1 expression is transcriptionally activated during EBV latent infection in B-lymphocytes but significantly suppressed during lytic cycle reactivation. While ectopic E2F1 expression suppresses lytic replication, E2F1 depletion markedly accelerates this process. Mechanistically, we establish that E2F1 and the lytic transactivator BZLF1 form a negative transcriptional feedback loop, tightly controlling viral lytic replication. Furthermore, E2F1 positively regulates c-Myc expression and together they repress the leaky BZLF1 expression during latency. Importantly, c-Myc does not influence E2F1 expression, nor does BZLF1 modulate c-Myc transcription, underlining a distinct regulatory hierarchy. In sum, our findings reveal that EBV tightly controls the latent-to-lytic switch through precise regulation of E2F1 expression, positioning E2F1 as a pivotal regulator of both cellular and viral gene expression. SynopsisEBV coordinates the latent-to-lytic switch by sensing E2F1 abundance, which acts as a crucial transcriptional regulator of both cellular and viral gene expressions. O_LIDuring EBV latent infection, E2F1 promotes c-Myc transcription, and together they suppress EBV lytic cycle transactivator BZLF1 expression. C_LIO_LIE2F1 and BZLF1 form a negative feedback loop in order to control each others transcriptions. C_LIO_LIBZLF1-driven controlled E2F1 expression successively inhibits c-Myc level, thereby stimulating EBV lytic cycle reactivation. C_LIO_LIBZLF1 does not regulate c-Myc, nor does c-Myc reciprocally regulate E2F1, emphasizing a unidirectional regulatory hierarchy. C_LI