Silencing GADD45B Ameliorates Epilepsy by Inhibiting Ferroptosis and Maintaining Mitochondrial Homeostasis Through the HIF-1 Signaling Pathway.

Epilepsy is a chronic brain disorder with unclear pathogenesis and no effective biomarkers. This study aims to identify potential biomarkers and elucidate the regulatory pathways in epilepsy. Epilepsy-associated differentially expressed genes (DEGs) were discovered from the GSE60772, GSE88992, and GSE100202 datasets. Hub genes were determined from a protein-protein interaction (PPI) network, followed by screening of downstream pathways of growth arrest and DNA damage inducible beta (GADD45B). GADD45B was silenced in lithium-pilocarpine-induced epileptic rats and glutamate-treated HT22 cells to investigate its effects on hippocampal neuron injury, ferroptosis, mitochondrial homeostasis, and its downstream signaling pathway. GADD45B as an epilepsy-associated hub gene was highly expressed in the hippocampal tissues of epileptic rats. Silencing GADD45B in epileptic rats suppressed neuronal injury and death. It also decreased Fe2+, malondialdehyde (MDA), 4-hydroxy-2-nonenal (4-HNE), reactive oxygen species (ROS), and hypoxia-inducible factor-1α (HIF-1α) but increased glutathione (GSH) in epileptic rats and HT22 cells, as well as suppressed acyl-CoA synthetase long chain family member 4 (ACSL4) expression and increased glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11) expression. Mitochondrial homeostasis was maintained after silencing GADD45B via suppressing mitofusin 1 (MFN1) and mitofilin. The HIF-1 signaling pathway was a downstream pathway of GADD45B, and its activation reversed the protective effects of GADD45B silencing on glutamate-induced neuronal death, ferroptosis, and mitochondrial homeostasis. Silencing GADD45B attenuates epileptic neuronal death by inhibiting ferroptosis and maintaining mitochondrial homeostasis via inhibiting the HIF-1 signaling pathway, which provides novel insights into epilepsy pathogenesis and potential biomarkers.