CREB2 mediates oxidative neuronal death

Background. Glutamate-induced oxidative cytotoxicity is a major contributor to neuronal loss in neurodegenerative diseases. Although the p53–GADD45α pathway has been implicated in this process, the upstream transcriptional regulators that convert oxidative stress signals into neuronal death remain unclear. CREB2 (also known as ATF4) is a stress-responsive transcription factor, but its involvement in microglia-mediated oxidative neurotoxicity has not been fully elucidated. Methods. We investigated the role of CREB2 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 exogenous glutamate, and CREB2 expression was assessed. Intracellular reactive oxygen species (ROS) levels were quantified using DCFDA fluorescence, and the antioxidant N-acetylcysteine (NAC) was used to determine oxidative dependency. In vivo relevance was validated by KA injection into the hippocampal CA3 region. To examine endogenous glutamate sources, BV2 microglial cells were stimulated with lipopolysaccharide (LPS), and extracellular glutamate in conditioned medium (LPS-CM) was quantified. LPS-CM was subsequently applied to HT22 cells to evaluate its effects on CREB2 expression, ROS generation, and NAC sensitivity. Results. Exogenous glutamate markedly increased CREB2 expression in both HT22 and primary hippocampal neurons, accompanied by elevated ROS levels and neuronal cell death. NAC co-treatment suppressed glutamate-induced CREB2 upregulation and cytotoxicity. Inhibition of p53 by siRNA or PFT-α attenuated glutamate-induced CREB2 expression, whereas CREB2 knockdown abolished GADD45α induction and conferred neuroprotection. In vivo, KA injection led to robust CREB2 upregulation in the damaged hippocampal CA3 region. Notably, LPS-stimulated BV2 microglia released glutamate into the conditioned medium, which increased CREB2 expression and ROS accumulation in HT22 cells; both effects were effectively blocked by NAC. Conclusions. Situated between upstream p53 signaling and downstream GADD45α activation, CREB2 functions as a pivotal mediator of glutamate-induced oxidative neuronal death. These findings identify CREB2 as a potential therapeutic target for neurodegenerative diseases driven by oxidative stress and neuroinflammation.