Differential Regulation of DJ‐1 in Glial Cells upon MHV‐A59 ‐Induced Oxidative Stress

Abstract

Astrocyte and microglial activation are two hallmarks associated with oxidative stress induction in neural cells. Generation of reactive oxygen species (ROS) is one of the molecular outcomes of neurotropic Mouse Hepatitis Virus A59 (MHV‐A59) infection in the Central Nervous System in an experimental animal model for human demyelinating disease Multiple Sclerosis. MHV‐A59 infection has been found to cause encephalitis, meningitis, and hepatitis in acute stage (Day 5–7 post‐infection) and progressive demyelination in chronic stage (Day 30 post‐infection). The virus has shown glial cell tropism leading to its activation, although the role of oxidative stress in this aspect is not well understood. Therefore, our work focuses on the regulation and function of important anti‐oxidative markers like DJ‐1, Nrf2, and HMOX‐1, upon viral infection in animal CNS tissue, isolated cells from tissues, primary culture and cell culture‐based studies. All three genes were found to be upregulated in vivo in mice brain at acute stage (Day 3 and 5) and chronic stage (Day 30) post‐infection. Similar upregulation was also observed in isolated microglia from mice brain, primary astrocytes, and microglia cultured from neonatal mice brain. In vitro studies with DBT astrocytoma cell line and N9 microglia cell line showed oxidative stress generation and upregulation in all three genes at initial time points of viral infection; however all the genes were found to be downregulated at higher time points. DBT cells exhibited decrease in cell viability and oxidative stress generation upon viral infection, and such changes had been observed to be ameliorated when DJ‐1 was stably transfected into DBT cells. Literature studies indicate that XBP1, an ER stress marker, upregulates DJ‐1 expression upon oxidative stress induction. In silico and in vitro studies showed that XBP1 was differentially activated in both DBT and N9 cells and was associated with DJ‐1 promoter upon viral infection in N9 cells. MHV‐A59 has shown tropism for glial cells resulting in their activation, and oxidative stress‐related cellular mechanisms involving these genes can contribute to the activation process of these glial cells. Support or Funding Information This study was supported by the Department of Biotechnology (DBT) and Indian Institute of Science Education and Research Kolkata (IISER Kolkata). Soumya Kundu was supported by University Grant Commission (UGC). Gisha Rose Anthony, Vineeth A. Raveendran, and Rahul Kumar were supported by DST‐INSPIRE fellowship under the banner of IISER Kolkata.