Li Yao, Hao Hao, Yu Haozhen, Yu Lu, Ma Heng, Zhang Haitao
Clinical Medical College of Air Force, Anhui Medical University, Hefei, China.
Department of Pathology and Pathophysiology, School of Basic Medical Sciences, Fourth Military Medical University, Xi'an, China.
Front Cardiovasc Med. 2022 Mar 22;9:824657. doi: 10.3389/fcvm.2022.824657. eCollection 2022.
Necroptosis contribute to the pathogenesis of myocardial ischemia/reperfusion (MI/R) injury. Ginsenoside Rg2 has been reported to have cardioprotective effects against MI/R injury; however, the underlying mechanism remains unclear. This work aimed to investigate the effect of ginsenoside Rg2 on necroptosis induced by MI/R and to explore the mechanism. In this study, hypoxia/reoxygenation (H/R) injury model was established in H9c2 cells. , male C57/BL6 mice were subjected to myocardial ischemia 30 min/reperfusion 4 h. Rg2 (50 mg/kg) or vehicle was intravenously infused 5 min before reperfusion. Cardiac function and the signaling pathway involved in necroptosis were investigated. Compared with H/R group, Rg2 significantly inhibited H/R-induced cardiomyocyte death. Rg2 treatment effectively inhibited the phosphorylation of RIP1, RIP3, and MLKL in H/R cardiomyocytes, and inhibited RIP1/RIP3 complex (necrosome) formation. In mice, Rg2 treatment manifested significantly lower ischemia/reperfusion (I/R)-induced myocardial necroptosis, as evidenced by decrease in phosphorylation of RIP1, RIP3, and MLKL, inhibited lactate dehydrogenase (LDH) release and Evans blue dye (EBD) penetration. Mechanically, an increased level of tumor necrosis factor α (TNFα), interleukin (IL)-1β, IL-6, and MCP-1 were found in MI/R hearts, and Rg2 treatment significantly inhibit the expression of these factors. We found that TNFα-induced phosphorylation of RIP1, RIP3, and MLKL was negatively correlated with transforming growth factor-activated kinase 1 (TAK1) phosphorylation, and inhibition of TAK1 phosphorylation led to necroptosis enhancement. More importantly, Rg2 treatment significantly increased TAK1 phosphorylation, enhanced TAK1 binding to RIP1 while inhibiting RIP1/RIP3 complex, ultimately reducing MI/R-induced necroptosis. These findings highlight a new mechanism of Rg2-induced cardioprotection: reducing the formation of RIP1/RIP3 necrosome by regulating TAK1 phosphorylation to block necroptosis induced by MI/R.
坏死性凋亡参与心肌缺血/再灌注（MI/R）损伤的发病机制。据报道，人参皂苷Rg2对MI/R损伤具有心脏保护作用；然而，其潜在机制仍不清楚。本研究旨在探讨人参皂苷Rg2对MI/R诱导的坏死性凋亡的影响并探索其机制。在本研究中，在H9c2细胞中建立缺氧/复氧（H/R）损伤模型。此外，对雄性C57/BL6小鼠进行30分钟心肌缺血/4小时再灌注。在再灌注前5分钟静脉注射Rg2（50mg/kg）或溶剂。研究心脏功能和坏死性凋亡相关的信号通路。与H/R组相比，Rg2显著抑制H/R诱导的心肌细胞死亡。Rg2处理有效抑制H/R心肌细胞中RIP1、RIP3和MLKL的磷酸化，并抑制RIP1/RIP3复合物（坏死小体）的形成。在小鼠中，Rg2处理显著降低缺血/再灌注（I/R）诱导的心肌坏死性凋亡，表现为RIP1、RIP3和MLKL磷酸化降低、乳酸脱氢酶（LDH）释放减少和伊文思蓝染料（EBD）渗透受抑制。机制上，在MI/R心脏中发现肿瘤坏死因子α（TNFα）、白细胞介素（IL）-1β、IL-6和单核细胞趋化蛋白-1水平升高，Rg2处理显著抑制这些因子的表达。我们发现TNFα诱导的RIP1、RIP3和MLKL磷酸化与转化生长因子激活激酶1（TAK1）磷酸化呈负相关，抑制TAK1磷酸化导致坏死性凋亡增强。更重要的是，Rg2处理显著增加TAK1磷酸化，增强TAK1与RIP1的结合，同时抑制RIP1/RIP3复合物，最终减少MI/R诱导的坏死性凋亡。这些发现突出了Rg2诱导心脏保护的新机制：通过调节TAK1磷酸化减少RIP1/RIP3坏死小体的形成，以阻断MI/R诱导的坏死性凋亡。
