α-ketoglutarate ameliorates spinal motor neuron ferroptosis after sacral plexus transection via enhancing PINK1...

Sacral plexus transection (SPT), mostly caused by high‑energy trauma, induces secondary death of spinal motor neurons in the lumbosacral segments and contributes to poor clinical outcomes after nerve repair. This study aimed to investigate the protective effect of α‑ketoglutarate (AKG) against ferroptosis in spinal motor neurons following SPT and the underlying molecular mechanism. Our results showed that endogenous AKG levels were significantly decreased in the spinal cord of SPT rats and in oxidative stress‑injured motor neurons, accompanied by abnormal expression of core ferroptosis‑related proteins, including downregulated glutathione peroxidase 4 and solute carrier family 7 member 11, upregulated acyl-CoA synthetase long-chain family member 4, as well as Fe²⁺ overload, malondialdehyde accumulation, and glutathione depletion. Exogenous AKG supplementation markedly reversed these anomalies, suppressed ferroptosis, and improved neuronal survival. Mechanistically, AKG specifically enhanced O-GlcNAcylation at the Thr177 site of PTEN‑induced kinase 1 (PINK1) and suppressed its ubiquitin-mediated degradation, which in turn selectively activated PINK1-PRKN-dependent mitophagy to eliminate damaged mitochondria and sustain mitochondrial homeostasis. Furthermore, downregulation of isocitrate dehydrogenase 1 (IDH1) after SPT was identified as a critical upstream event leading to endogenous AKG depletion. This study systematically elucidates the key role of the IDH1‑AKG‑PINK1 O‑GlcNAcylation ‑mitophagy axis in regulating SPT‑induced ferroptosis in spinal motor neurons, providing novel targets and experimental evidence for neuroprotective therapy of sacral plexus injury.Abbreviations: ACSL4: acyl-CoA synthetase long-chain family member 4; AKG: 464748495051525354555657585960616263646566α‑ketoglutarate; BNIP3: BCL2/adenovirus E1B 19 kDa-interacting protein 3; CCK-8: cell counting kit-8; Co-IP: co-immunoprecipitation; Fer-1: ferrostatin-1; FUNDC1: FUN14 domain-containing 1; GLUD1: glutamate dehydrogenase 1; GPX4: glutathione peroxidase 4; GSH: glutathione; IDH1: isocitrate dehydrogenase 1; LC3: microtubuleassociated protein 1 light chain 3; MDA: malondialdehyde; MMP: mitochondrial membrane potential; NIX: NIP3-like protein X; O-GlcNAc: O-linked Nacetylglucosamine; OGT: O-GlcNAc transferase; OSMI-1: O-GlcNAc Transferase Inhibitor-1; PINK1: PTEN-induced kinase 1; PRKN: parkin RBR E3 ubiquitin protein ligase; ROS: reactive oxygen species; RT-qPCR: real-time quantitative polymerase chain reaction; siRNA: small interfering RNA; SLC7A11: solute carrier family 7 outer mitochondrial membrane 20.