Pyruvate kinase M2 modulates Japanese encephalitis virus replication in neuronal cells.

Japanese encephalitis is a neuroinflammatory condition caused by the Japanese encephalitis virus (JEV). Pyruvate kinase muscle isozyme M2 (PKM2) is a key modulator of glucose metabolism. The role of PKM2 in the autoimmune response and inflammation is now increasingly being acknowledged. However, its role in modulating virus replication has not been explored. In the current study, we have explored the role of PKM2 in JEV replication. Our results show that endogenous PKM2 expression is significantly upregulated in JEV-infected mouse neuroblastoma cells. Moreover, overexpression and knockdown studies substantiate the negative effect of PKM2 on JEV replication. Additionally, JEV infection induced signal transducers and activators of transcription 3 (STAT3) activation in the infected neuronal cells. Overexpression of PKM2 enhanced STAT3 activation, while its downregulation reduced STAT3 activation in the JEV-infected neuronal cells. The results suggested that the overexpression of PKM2 exhibited elevated levels of TNF-α and IL-1β, whereas the downregulation of PKM2 decreased their expression. The in silico studies revealed the potential interaction between PKM2 and non-structural protein 1 (NS1), which was subsequently validated in vitro by co-immunoprecipitation assay. The microscopic studies also unveiled the cellular co-localization of PKM2 and NS1 in the endoplasmic reticulum of infected cells. Altogether, these findings indicate that PKM2 negatively regulates JEV replication by inducing the expression of proinflammatory cytokines such as TNF-α and IL-1β. The study also establishes PKM2 as a binding partner of the NS1 protein. Thus, the study paves the path towards understanding the multifaceted role of PKM2 in JEV pathology.