Xi'an Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China.
Department of Physiology and Pathophysiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, Shaanxi, 710032, PR China.
Free Radic Biol Med. 2023 Aug 20;205:305-317. doi: 10.1016/j.freeradbiomed.2023.06.016. Epub 2023 Jun 19.
Myocardial ischemia/reperfusion (I/R) injury is characterized by cell death via various cellular mechanisms upon reperfusion. As a new type of cell death, ferroptosis provides new opportunities to reduce myocardial cell death. Ferroptosis is known to be more active during reperfusion than ischemia. However, the mechanisms regulating ferroptosis during ischemia and reperfusion remain largely unknown.
The contribution of ferroptosis in ischemic and reperfused myocardium were detected by administered of Fer-1, a ferroptosis inhibitor to C57BL/6 mice, followed by left anterior descending (LAD) ligation surgery. Ferroptosis was evaluated by measurement of cell viability, ptgs2 mRNA level, iron production, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels. H9C2 cells were exposed to hypoxia/reoxygenation to mimic in vivo I/R. We used LC-MS/MS to identify potential E3 ligases that interacted with frataxin in heart tissue. Cardiac-specific overexpression of frataxin in whole heart was achieved by intracardiac injection of frataxin, carried by adeno-associated virus serotype 9 (AAV9) containing cardiac troponin T (cTnT) promoter.
We showed that regulators of iron metabolism, especially iron regulatory protein activity, were increased in the ischemic myocardium or hypoxia cardiomyocytes. In addition, we found that frataxin, which is involved in iron metabolism, is differentially expressed in the ischemic and reperfused myocardium and involved in the regulation of cardiomyocytes ferroptosis. Furthermore, we identified an E3 ligase, NHL repeat-containing 1 (NHLRC1), that mediates frataxin ubiquitination degradation. Cardiac-specific overexpression of frataxin ameliorated myocardial I/R injury through ferroptosis inhibition.
Through a multi-level study from molecule to animal model, these findings uncover the key role of frataxin in inhibiting cardiomyocyte ferroptosis and provide new strategies and perspectives for the treatment of myocardial I/R injury.
心肌缺血/再灌注（I/R）损伤的特征是再灌注时通过各种细胞机制导致细胞死亡。作为一种新型的细胞死亡方式，铁死亡为减少心肌细胞死亡提供了新的机会。铁死亡在再灌注期间比在缺血期间更为活跃。然而，在缺血和再灌注期间调节铁死亡的机制在很大程度上仍然未知。
通过给予 C57BL/6 小鼠铁死亡抑制剂 Fer-1，并随后进行左前降支（LAD）结扎手术，检测缺血和再灌注心肌中的铁死亡作用。通过测量细胞活力、ptgs2 mRNA 水平、铁生成、丙二醛（MDA）和 4-羟基壬烯醛（4-HNE）水平来评估铁死亡。使用 LC-MS/MS 鉴定与心脏组织中 frataxin 相互作用的潜在 E3 连接酶。通过心肌内注射含有心脏肌钙蛋白 T（cTnT）启动子的腺相关病毒血清型 9（AAV9）来实现心脏特异性过表达 frataxin。
我们发现，铁代谢调节剂，特别是铁调节蛋白活性，在缺血心肌或缺氧心肌细胞中增加。此外，我们发现，frataxin 是铁代谢的关键调节因子，在缺血和再灌注心肌中差异表达，并参与调节心肌细胞铁死亡。此外，我们鉴定出一个 E3 连接酶，NHL 重复包含蛋白 1（NHLRC1），它介导 frataxin 的泛素化降解。心脏特异性过表达 frataxin 通过抑制铁死亡改善心肌 I/R 损伤。
通过从分子到动物模型的多层次研究，这些发现揭示了 frataxin 在抑制心肌细胞铁死亡中的关键作用，并为心肌 I/R 损伤的治疗提供了新的策略和视角。
