Forkhead factor regulation in oral viral infection

The oral cavity is the initial site of infection for many pathogens, including viruses. Kaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic virus that is shed in saliva, which is the primary route for spread between individuals. While in most cell types KSHV establishes a lifelong latent infection, in primary human gingival

epithelial cells (HGEP) KSHV can establish a lytic infection, with sustained viral gene expression driven by the essential lytic viral factor replication and transcription activator (RTA). Importantly, lytic KSHV infection of oral epithelial cells leads to the production and release of new infectious virions, a key early step in KSHV infection

that can lead to viral spread and chronic infection of other cell types in the human body. Despite the clinical and biological importance of oral infection as an initial step in KSHV infection, little is known about the host-pathogen interactions and their control mechanisms during KSHV infection of oral epithelial cells. Through genome-wide

transcriptome analysis, one member of the forkhead box family of transcription factors (FOX TFs) was identified as rapidly and robustly induced upon de novo KSHV infection in HGEP cells. The FOX factors comprise a family TFs responsible for many cellular processes including cell growth and differentiation. However, little is known

about the roles of FOX TFs in the context of viral infection. Preliminary data revealed that a large number of predicted target genes of the FOX TF are de-regulated during KSHV infection. Many of these targets encode key regulators of critical cellular functions. While the identified FOX TF is highly induced upon KSHV infection of

oral cells, it is expressed at very low levels in uninfected oral cells, suggesting a rapid transcriptional switch driven by viral infection. The purpose of this project is to dissect the mechanism of FOX TF silencing in uninfected oral epithelial cells, and to determine how lytic viral infection disrupts this silencing, thereby promoting rapid

alterations of normal cellular functions in infected oral epithelial cells. To examine repressive mechanisms in the oral cavity, Aim 1 focuses on identification of epigenetic enzymes that restrict FOX TF expression. It is hypothesized that viral factors disrupt the silencing of these host epigenetic enzymes during lytic infections. Aim

2 will identify how specific KSHV proteins induce the expression of FOX TF. A combination of genome-wide studies coupled with KSHV mutants will be used to analyze how KSHV infection affects FOX TF regulatory regions to result in FOX TF induction. In summary, this study will identify a novel viral mechanism in which the

virus exploits a central host transcription factor to deregulate key cellular processes during lytic infection. The completion of this project will provide in-depth training in epigenetics, virology and genomics approaches. These skills will be enhanced in the outstanding research environment provided by the Comprehensive Training

Program in Oral Biology at the University of Florida College of Dentistry, which incorporates tailored mentorship and excellent clinical and research training to prepare the applicant for a career as a clinician-scientist.