miR‐432‐5p Inhibits the Ferroptosis in Cardiomyocytes Induced by Hypoxia/Reoxygenation via Activating Nrf2/SLC7A11 Axis by Degrading Keap1

Early reperfusion into the myocardium after ischemia causes myocardial ischemia–reperfusion (I/R) injury and ferroptosis was involved. Ischemia activates the expression of a series of oxidative stress genes and their downstream regulatory genes, including ferroptosis‐related genes such as nuclear factor E2‐related factor 2 (Nrf2), glutathione peroxidase 4 (GPX4), and SLC7A11. This study adopted primary cardiomyocytes and I/R in rats to evaluate the ferroptosis and changing of Nrf2‐SLC7A11/heme oxygenase‐1 (HO‐1) in vitro and in vivo. Online analysis tools were used to predict the possible target Kelch‐like ECH‐associated protein 1 (Keap1) of miR‐432‐5p. The mimic of miR‐432‐5p plasmid was constructed to verify the effect of miR‐432‐5p on ferroptosis. We found that hypoxia/reoxygenation (H/R) in cardiomyocytes and I/R in rats induced lipid peroxidation and ferroptosis in cardiomyocytes. The activation of the Nrf2‐SLC7A11/HO‐1 pathway protects cardiomyocytes from ferroptosis. Downregulation of miR‐432‐5p has been confirmed in H/R cardiomyocytes (in vitro) and cardiomyocytes in myocardial infarction rats (in vivo). Upregulation of miR‐432‐5p inhibited ferroptosis of cardiomyocytes induced by RAS‐selective lethal 3 (RSL3), an inhibitor of GPX4 and ferroptosis inducer through decreasing the binding protein of Nrf2, Keap1, which was confirmed by bioinformatics and mutation assay. Knockdown Nrf2 attenuates the protection effect of miR‐432‐5p on H/R cardiomyocytes. Intravenous delivery of liposome carriers of miR‐432‐5p remarkably ameliorated cardiomyocyte impairment in the I/R animal model. In conclusion, miR‐432‐5p inhibits the ferroptosis in cardiomyocytes induced by H/R by activating Nrf2/SLC7A11 axis by degrading Keap1 and is a potential drug target for clinical myocardial infarction treatment.