CREB2 Functions as a Central Mediator of Oxidative Neuronal Death Triggered by Microglial Glutamate Release Under Neuroinflammatory Conditions

Glutamate-induced oxidative cytotoxicity is a major driver of neuronal loss in neurodegenerative diseases, yet the upstream transcriptional regulators linking oxidative stress to neuronal death remain unclear despite the known involvement of the p53-GADD45α pathway. CREB2 (ATF4) is a stress-responsive transcription factor, but its role in microglia-mediated oxidative neurotoxicity has not been fully defined. Here, we investigated CREB2 function in oxidative glutamate toxicity using HT22 hippocampal neurons, primary mouse hippocampal cells, and a kainic acid (KA)-injected rat model. Oxidative stress was induced by glutamate, intracellular ROS levels were quantified with DCFDA, and the antioxidant N-acetylcysteine (NAC) was used to confirm oxidative dependency. Microglia-derived glutamate was assessed by stimulating BV2 cells with lipopolysaccharide (LPS) and applying glutamate-containing conditioned medium (LPS-CM) to HT22 cells. Exogenous glutamate robustly increased CREB2 expression in HT22 and primary neurons, accompanied by ROS accumulation and cell death, whereas NAC suppressed these effects. Inhibition of p53 by siRNA or pifithrin-α (PFT-α) attenuated glutamate-induced CREB2 upregulation, and CREB2 knockdown blocked GADD45α induction and protected neurons. In Vivo, KA injection caused robust CREB2 upregulation in the damaged CA3 region. Importantly, conditioned medium from LPS-activated BV2 microglia increased CREB2 expression and ROS levels in HT22 cells in an NAC-sensitive manner, supporting a glutamate-associated oxidative mechanism rather than receptor-mediated excitotoxicity. Collectively, these results suggest that CREB2 functions between upstream p53 signaling and downstream GADD45α activation as a redox-sensitive mediator of oxidative neuronal death, and may represent a potential therapeutic target in neurodegenerative diseases associated with oxidative stress and neuroinflammation.