Characterization of Viral Receptors and Signaling Networks in JC Polyomavirus Infection - PROJECT SUMMARY The objective of the proposed research is to determine the mechanisms by which JC polyomavirus (JCPyV) interacts with host-cell receptors to cause JCPyV infection, which leads to the development of progressive multifocal leukoencephalopathy (PML). JCPyV infects the majority of the human population and establishes a lifelong, asymptomatic infection in the kidney of healthy individuals. In immunocompromised individuals, JCPyV can spread to the central nervous system (CNS) and cause a lytic infection in glial cells, resulting in the fatal, demyelinating disease PML. Approximately 5% of individuals with HIV develop PML, which proves to be a terminal AIDS-defining illness, and individuals receiving immunomodulatory therapies for diseases including multiple sclerosis are at heightened risk for PML development. PML can be fatal within one year of symptom onset, especially when underlying immunosuppression is left untreated, and there are currently no approved treatments for this devastating disease. The mechanisms by which JCPyV engages cellular receptors to invade host cells to cause infection is not well characterized. Virus-receptor interactions regulate host cell susceptibility and disease pathogenesis, thus understanding JCPyV interactions with host cell receptors will provide key insight into the mechanisms of JCPyV invasion and infection of host cells. Our previous work elucidated that JCPyV entry is mediated by the 5-hydroxytryptamine 2 subfamily of serotonin receptors (5- HT2Rs) via clathrin-mediated endocytosis and β-arrestin. We also determined that JCPyV infection induces clustering of 5-HT2Rs. Interestingly, G-protein coupled receptors (GPCR), including 5-HT2Rs, can cluster to form hetero- and homodimers as well as oligomers, which is functionally significant to the structural organization of the ligand binding interface, endocytic mechanisms, and activation of and signaling pathways. However, this process is not well characterized for 5-HT2Rs, and how receptor attributes direct viral invasion of host cells and orchestrate the complex processes of viral infection is poorly understood. We hypothesize that JCPyV infection induces ligand-specific cluster patterns of 5-HT2Rs to mediate JCPyV entry, trafficking, and receptor-activated signaling pathways. Three complementary specific aims are proposed in this research plan to understand the mechanisms by which JCPyV utilizes 5-HT2Rs to internalize into host cells and usurp cellular signaling networks to regulate viral trafficking and drive viral replication. This research will enhance our understanding of JCPyV entry and signaling, elucidating how virus-receptor interactions regulate viral infection and disease. These studies could also uncover new antiviral targets or provide rationale for experimental use of on-market 5-HT2R-specific drugs for PML. Outcomes of this work will also provide broader insights into the mechanisms of virus entry of nonenveloped viruses and activation of cellular signaling networks by viruses implicated to utilize GPCR signaling such as coronaviruses, herpesviruses, and Ebola virus, which cause serious human diseases.
