Redox Control of Seizure-Induced Neuroinflammation

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Mitochondrial Reactive Oxygen Species in Epilepsy-Associated Astrogliosis The parent grant focuses on the interplay between neuroinflammation and redox status. The supplemental research addresses a related but distinct goal to investigate the role of mitochondria in seizure-induced neuroinflammation. Mitochondria integrate the energy requirements of neuronal cells and circuits with nutrients, ions, inflammatory mediators and redox status. Mitochondrial dysfunction, oxidative stress and neuroinflammation have been linked with pathophysiological hyperexcitability associated with epilepsy. Neuroinflammation specifically has been identified as a therapeutic target for epilepsy, however the detailed mechanisms underlying seizure-induced neuroinflammation, including upregulation of astrocyte- specific glial fibrillary acidic protein (GFAP), remain at large. One clue regarding upregulation of GFAP arises from recent studies in our laboratory showing a robust transcriptional upregulation of GFAP in mice lacking the anti-oxidant mitochondrial manganese superoxide dismutase-2 (Sod2) in forebrain neurons, a finding replicated in primary neuronal-glial culture. In contrast, mixed cultures in which neurons were selectively depleted displayed no such upregulation. The goal of this project is to determine if mitochondrial reactive oxygen species (mtROS) generated within neurons can activate neuroinflammation via upregulation of GFAP expression as a result of posttranslational redox modification of a conserved cysteine (Cys294) in GFAP, resulting in long-lasting neuroinflammation. Aim 1 will determine if neuronal mtROS is sufficient to induce GFAP upregulation and astrogliosis in vitro using mixed rat neuronal culture and in vivo using Nex-Cre/Sod2f/f mice microinjected with viral vectors driving GCaMP6f within astrocytes. Aim 2 will determine if this astrogliosis involves redox modification of GFAP protein by mutating Cys294. These studies will reveal novel redox-based therapeutic targets to treat epilepsy.