Metabolic regulation of Epstein-Barr Virus-infected tonsillar B cells by EBNA-LP

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Epstein-Barr Virus (EBV) infects over 90% of adults worldwide and initially establishes infection in the oral cavity, including tonsillar B cells. Upon infecting naïve B cells, EBV expresses viral proteins including EBV Nuclear Antigens (EBNAs), transcriptional co-activators that promote B cell maturation and establish latently infected memory B cell reservoirs. EBV-associated malignancies include infectious mononucleosis, and, in immune compromised hosts, tumorigenesis including lymphomas. Recently, it has been appreciated that EBV induces metabolic changes upon infection. Our lab has discovered that EBV upregulates oxidative phosphorylation (OXPHOS) in order to promote cell proliferation and avoid arrest. Similarly, naïve B cells also require increased OXPHOS upon activation by antigen in order to undergo germinal center remodeling and produce memory B cells. Therefore, the ultimate goal of this proposal is to elucidate the molecular mechanisms by which EBV alters OXPHOS, which will enhance our understanding of EBV requirements for latency, and the role of metabolism in B cell maturation. Intriguingly, the viral protein EBNA-Leader Protein (EBNA-LP) is required for infection of naïve B cells, but not memory B cells – although the essential role of EBNA-LP is not well characterized. Our preliminary data suggests the viral protein EBNA-Leader Protein (EBNA-LP) may be essential in upregulation OXPHOS through transcriptional co-activation of metabolic genes. Our data suggests that EBNA-LP binds transcription factors that regulate expression of OXPHOS-related genes including NRF1, ERRα, and YY1 and then recruits chromatin remodeling factors such as P300. This mechanism of transcriptional co-activation mimics the PGC family of proteins, which uses leucine-rich motifs to bind the same OXPHOS transcription factors and recruit remodelers. Our preliminary data supports this model in that EBNA-LP contains multiple leucine-rich motifs, which may be required for binding these transcription factors. Additionally, EBNA-LP forms nuclear bodies, or membraneless organelles, that may be essential for EBNA-LP to regulate transcription, including OXPHOS genes. Our preliminary data suggests that EBNA-LP contains a post-translational modification, hydroxyproline, which promotes protein oligomerization and higher order structures in modified substrates such as collagen. Therefore, I propose that hydroxyprolination of EBNA-LP is required to form EBNA-LP nuclear bodies and co-activate transcription. My overall hypothesis is that EBNA-LP induces transcription of OXPHOS genes by using leucine-rich motifs to mimic the cellular PGC family of proteins, and through forming nuclear bodies upon hydroxyprolination. In Aim 1, I will assess the role of leucine-rich motifs in mediating transcription of OXPHOS genes and upregulation of cellular OXPHOS in tonsillar B cells. In Aim 2, I will determine the role of hydroxyprolination of EBNA-LP in formation of nuclear bodies and metabolic regulation in infected cells. These studies will elucidate novel mechanisms by which a viral protein regulates transcription and B cell metabolism and will provide insight towards understanding EBV-related malignancies.