Gadd45α silencing alleviates cerebral ischemia–reperfusion injury by suppressing FOXO1 signaling

Cerebral ischemia-reperfusion (I/R) injury remains a major therapeutic challenge, primarily due to complex mechanisms involving oxidative stress and apoptosis. Growth arrest and DNA damage-inducible protein α (Gadd45α), a stress sensor linked to cellular stress responses, has been implicated in I/R injury, yet its precise role in ischemic stroke is incompletely understood. This study aimed to elucidate the function and underlying mechanisms of Gadd45α in cerebral I/R injury using both in vivo and in vitro models. In rats subjected to middle cerebral artery occlusion (MCAO) and in neurons exposed to oxygen-glucose deprivation/reperfusion (OGD/R), Gadd45α expression was significantly upregulated. Lentivirus-mediated knockdown of Gadd45α (sh-Gadd45α) reduced infarct volumes, improved neurological function and increased miniature excitatory postsynaptic current (mEPSC) amplitude. In primary cortical neurons exposed to OGD/R, Gadd45α knockdown decreased reactive oxygen species (ROS) production, DNA damage, and apoptosis, while Gadd45α overexpression exacerbated these effects. Mechanistically, Gadd45α directly interacts with forkhead box O1 (FOXO1) and positively regulates its transcriptional activity. Gadd45α knockdown attenuated the ischemia-induced upregulation of both total FOXO1 and its phosphorylated form (p-FOXO1), thereby suppressing FOXO1 signaling and mitigating cerebral I/R injury. Furthermore, FOXO1 overexpression reversed the neuroprotective effects of Gadd45α silencing, confirming that FOXO1 acts as a critical downstream mediator. These findings demonstrate that Gadd45α silencing alleviates cerebral I/R injury by suppressing FOXO1 signaling, suggesting the Gadd45α/FOXO1 axis as a promising therapeutic target for ischemic stroke.