Identifying new phosphorylation substrates of a viral protein kinase encoded by Kaposi’s sarcoma-associated herpesvirus

Kaposi’s sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV8), is the infectious cause of three types of human cancer: Kaposi’s sarcoma, primary effusion lymphoma, and multicentric Castleman’s disease. To aid in viral replication, KSHV encodes a viral serine/threonine protein kinase (vPK), a protein that plays a role in the production of infectious KSHV virions. The vPK protein alters the phosphorylation of several cellular substrates, leading to the augmentation of protein synthesis and the multiplication of virally infected cells. While current research shows that vPK can mimic some cellular kinases to phosphorylate approximately ten different cellular substrates, there are likely more substrates for vPK than what is currently known. This project aimed to confirm two new phosphorylation substrates, nucleophosmin (NPM1) and human antigen R (HUR), which were identified by high-throughput phosphoproteomics. Immunoblotting revealed overall protein levels of NPM1 and HUR did not change in the presence or absence of vPK. Additionally, no apparent effect on the phosphorylation of NPM1 by vPK was observed. These results indicate that vPK may not be affecting the phosphorylation of NPM1. Detection of HUR phosphorylation is still being optimized and it has yet to be determined whether HUR phosphorylation levels are affected in the presence of vPK. The identification of new phosphorylation substrates of vPK, such as NPM1 and HUR, has the potential for the development of new treatments for KSHV-related cancers by targeting vPK kinase activity.Bachelor of Art