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.

中文翻译：

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miR-432-5p 通过降解 Keap1 激活 Nrf2/SLC7A11 轴抑制缺氧/复氧诱导的心肌细胞铁死亡

缺血后心肌的早期再灌注会导致心肌缺血再灌注（I/R）损伤并涉及铁死亡。缺血会激活一系列氧化应激基因及其下游调控基因的表达，包括铁死亡相关基因，如核因子E2相关因子2（Nrf2）、谷胱甘肽过氧化物酶4（GPX4）和SLC7A11。本研究采用大鼠原代心肌细胞和I/R来评价体内外铁死亡和Nrf2-SLC7A11/血红素加氧酶-1（HO-1 ）的变化。使用在线分析工具预测 miR-432-5p 的可能靶标 Kelch 样 ECH 相关蛋白 1 (Keap1)。构建miR-432-5p模拟质粒以验证miR-432-5p对铁死亡的影响。我们发现心肌细胞缺氧/复氧 (H/R) 和大鼠 I/R 会诱导心肌细胞脂质过氧化和铁死亡。Nrf2-SLC7A11/HO-1 通路的激活可保护心肌细胞免于铁死亡。miR-432-5p 的下调已在 H/R 心肌细胞（体外）和心肌梗塞大鼠的心肌细胞（体内）中得到证实。生物信息学和突变分析证实，miR-432-5p的上调可抑制由GPX4抑制剂和铁死亡诱导剂RAS-选择性致死3（RSL3）诱导的心肌细胞铁死亡，这是通过减少Nrf2、Keap1的结合蛋白来抑制的。敲低 Nrf2 会减弱 miR-432-5p 对 H/R 心肌细胞的保护作用。静脉内递送 miR-432-5p 脂质体载体可显着改善 I/R 动物模型中的心肌细胞损伤。总之，miR-432-5p通过降解Keap1激活Nrf2/SLC7A11轴来抑制H/R诱导的心肌细胞铁死亡，是临床心肌梗死治疗的潜在药物靶点。