LncRNA ENSSSCG00000035331 Alleviates Hippocampal Neuronal Ferroptosis and Brain Injury Following Porcine Cardiopulmonary Resuscitation by Regulating the miR ‐let7a/ GPX4 Axis

BACKGROUND: Following successful cardiopulmonary resuscitation, those survivors of cardiac arrest (CA) often suffer from severe brain injury, and the latter can result in significant mortality and morbidity. Emerging evidence implicates that ferroptosis is involved in the pathogenesis of post-resuscitation brain injury, and its regulatory mechanisms remain to be investigated. Recently, some studies manifested that long noncoding RNAs could be critical regulators of cell ferroptosis in diverse ischemia-reperfusion injuries of vital organs. This study was designed to explore the role and mechanism of a newly screened long noncoding RNA ENSSSCG00000035331 in alleviating post-resuscitation hippocampal neuronal ferroptosis and further investigate its potential regulation by a novel antioxidant sulforaphane. METHODS AND RESULTS: Healthy male pigs and mice were used to establish the models of CA and resuscitation in vivo. A hypoxia/reoxygenation (H/R) model using primary porcine hippocampal neurons was constructed to replicate post-resuscitation brain injury in vitro. We found that the expression of ENSSSCG00000035331 was significantly decreased in the post-resuscitation impaired hippocampus using RNA sequencing analysis and verification. Subsequently, ENSSSCG00000035331 overexpression significantly reduced ferroptosis-related ferrous iron and reactive oxygen species production while markedly increased glutathione and further alleviated post-resuscitation brain injury. Mechanistically, ENSSSCG00000035331 interacted with miR-let7a, then inhibited its binding with glutathione peroxidase 4 (GPX4) mRNA and finally promoted the recovery of the latter's translation after H/R stimulation. In addition, sulforaphane treatment significantly increased ENSSSCG00000035331 and GPX4 expression while markedly decreased miR-let7a expression and hippocampal neuronal ferroptosis and finally alleviated post-resuscitation brain injury. CONCLUSIONS: Our findings highlighted that ENSSSCG00000035331 was a critical regulator of hippocampal neuronal ferroptosis after CA and resuscitation by targeting the miR-let7a/GPX4 axis, and additionally, sulforaphane might be a promising therapeutic agent for alleviating post-resuscitation brain injury by regulating the signaling axis mentioned above.