Epstein-Barr virus (EBV) is the causative agent of mononucleosis and is associated with human cancers, such as Burkitt lymphoma. EBV, a gammaherpesvirus, persists latently in B cells. Reactivation from latency is required for the virus to spread, and is a potential therapy for EBV-positive cancers. The EBV lytic cycle is induced in cell culture by various stimuli, including sodium butyrate. Butyrate is a short-chain fatty acid (SCFA) and histone deacetylase (HDAC) inhibitor, although this activity has not been proven sufficient to activate EBV. Another SCFA and HDAC inhibitor, valproic acid (VPA), does not reactivate EBV. In fact, VPA blocks viral reactivation by butyrate. It is unknown how butyrate promotes lytic activation and why butyrate and VPA have differing effects on EBV reactivation. Therefore, this project will investigate three possible mechanisms for the effects of SCFAs on EBV in Burkitt lymphoma cells.
Specific Aim 1 is to determine if short-chain fatty acids block Epstein-Barr virus reactivation by inducing histone modifications that repress gene expression.
This aim will identify the effects of SCFAs on histone modifications, such as lysine methylation, at the viral transactivator gene promoters and if those modifications influence EBV reactivation.
Specific Aim 2 is to determine how cellular gene expression in B cells is affected by SCFAs. Cellular genes differentially regulated by butyrate and VPA will be examined for a role in EBV reactivation.
Specific Aim 3 is to determine whether SCFAs alter activation of kinase signaling pathways in B cells. Protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) signaling are implicated in EBV reactivation. The effects of SCFAs on the activation PKC signaling will be investigated by studying inositol metabolism, phospholipase C activation, intracellular calcium levels, and kinase activation. The proposed work addresses mechanistic pathways for the effects for SCFAs on Burkitt lymphoma cells and on EBV lytic reactivation. Accomplishment of these aims will provide insight into regulation of B cells by SCFAs, endogenous stimuli that control EBV reactivation, and cellular targets for the treatment of EBV-associated cancers. In addition, these mechanistic studies on SCFAs and HDAC inhibitors may help to explain the connection between diet and carcinogenesis and provide clues to how SCFAs can be applied for clinical use.
Epstein-Barr virus (EBV) causes mononucleosis and can cause human cancers, such as Burkitt lymphoma, Hodgkin disease, nasopharyngeal carcinoma, and lymphoproliferative disease in immunocompromised patients. EBV persists in a latent state, but reactivation is required for the virus to spread. This application aims to understand how EBV is reactivated, and accomplishment of this research may lead to treatments for EBV-associated cancers.
|Gorres, Kelly L; Daigle, Derek; Mohanram, Sudharshan et al. (2014) Activation and repression of Epstein-Barr Virus and Kaposi's sarcoma-associated herpesvirus lytic cycles by short- and medium-chain fatty acids. J Virol 88:8028-44|