Activation of SSAT1/ALOX15 Axis Aggravates Cerebral Ischemia/Reperfusion Injury via Triggering Neuronal Ferroptosis

an iron-dependent form of non-apoptotic cell death, is reportedly responsible for cerebral ischemia/reperfusion (I/R) injury. Evidence has shown that spermidine/spermine N1-acetyltransferase 1 (SSAT1) activation-induced ferroptosis is associated with upregulation of arachidonate 15-Lipoxygenase (ALOX15). Our previous study has revealed that upregulation of ALOX15 contributes to cerebral I/R injury via inducing microglial activation. The current study aimed to investigate the role of SSAT1/ALOX15 axis in neuronal ferroptosis after I/R. We found that the expression of SSAT1 was upregulated in the cortical penumbra of mice subjected to transient middle cerebral artery occlusion and reperfusion (tMCAO/R). Knockdown of SSAT1 mitigated I/R-induced cerebral infarction and neurological impairments, as well as decreased cortical iron contents, reactive oxygen species (ROS) generation and 4-Hydroxynonenal (4-HNE) level. Further in vitro evidence revealed that knockdown of SSAT1 downregulated the expression of ALOX15 in the primary cortical neurons exposed to tertbutylhydroksyperoxide (TBH). In addition, loss of neuronal viability and production of lipid hydroperoxides were inhibited in TBH-treated neurons when SSAT1 was knocked down. Mechanistically, SSAT1 overexpression decreased the expression levels of two key ferroptotic repressors, glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11) in TBH-stimulated neurons. Treatment with the ALOX15 inhibitor PD146176 or ferroptosis inhibitor ferrostatin-1 partially reversed SSAT1 upregulation-induced ferroptosis and viability loss in TBH-treated neurons. These results together indicate that the activation of SSAT1/ALOX15 axis may aggravate cerebral I/R injury via triggering neuronal ferroptosis, providing novel insights into cerebral injury associated with lipid per oxidation.(c) 2022 IBRO. Published by Elsevier Ltd. All rights reserved.