The First Affiliated Hospital of Weifang Medical University, Weifang People's Hospital Cardiovascular Surgery, Weifang, 261000, China.
Shandong Provincial Medicine and Health Key Laboratory of Clinical Anesthesia, School of Anesthesiology, Weifang Medical University, Weifang, 261000, China.
Cell Stress Chaperones. 2022 Sep;27(5):535-544. doi: 10.1007/s12192-022-01290-0. Epub 2022 Jul 16.
Hypoxia/reoxygenation (H/R) is used as an in vivo model of ischemia/reperfusion injury, and myocardial ischemia can lead to heart disease. Calcium overload is an important factor in myocardial ischemia-reperfusion injury and can lead to apoptosis of myocardial cells. Therefore, it is of great clinical importance to find ways to regulate calcium overload and reduce apoptosis of myocardial cells, and thus alleviate myocardial ischemia-reperfusion injury. There is evidence that heat shock protein 70 (HSP70) has a protective effect on the myocardium, but the exact mechanism of this effect is not completely understood. Stromal interaction molecule 1 and inositol 1,4,5-triphosphate receptor (STIM/1IP3R) play an important role in myocardial ischemia-reperfusion injury. Therefore, this study aimed to investigate whether HSP70 plays an anti-apoptotic role in H9C2 cardiomyocytes by regulating the calcium overload pathway through STIM1/IP3R. Rat H9C2 cells were subjected to transient oxygen and glucose deprivation (incubated in glucose-free medium and hypoxia for 6 h) followed by re-exposure to glucose and reoxygenation (incubated in high glucose medium and reoxygenation for 4 h) to simulate myocardial ischemia reperfusion-induced cell injury. H9C2 cell viability was significantly decreased, and lactate dehydrogenase (LDH) release and apoptosis were significantly increased after oxygen and glucose deprivation. Transfection of HSP70 into H9C2 cells could reduce the corresponding effect, increase cell viability and anti-apoptotic signal pathway, and reduce the apoptotic rate and pro-apoptotic signal pathway. After hypoxia and reoxygenation, the expression of STIM1/IP3R and intracellular calcium concentration of HSP70-overexpressed H9C2 cells were significantly lower than those of hypoxia cells. Similarly, direct silencing of STIM1 by siRNA significantly increased cell viability and expression of anti-apoptotic protein Bcl-2 and decreased apoptosis rate and expression of pro-apoptotic protein BAX. These data are consistent with HSP70 overexpression. These results suggest that HSP70 abrogates intracellular calcium overload by inhibiting upregulation of STIM1/IP3R expression, thus reducing apoptosis in H9C2 cells and playing a protective role in cardiomyocytes.
缺氧/复氧（H/R）被用作缺血/再灌注损伤的体内模型，而心肌缺血可导致心脏病。钙超载是心肌缺血再灌注损伤的一个重要因素，可导致心肌细胞凋亡。因此，寻找调节钙超载和减少心肌细胞凋亡的方法，从而减轻心肌缺血再灌注损伤，具有重要的临床意义。有证据表明热休克蛋白 70（HSP70）对心肌具有保护作用，但这种作用的确切机制尚不完全清楚。基质相互作用分子 1 和肌醇 1,4,5-三磷酸受体（STIM/1IP3R）在心肌缺血再灌注损伤中发挥重要作用。因此，本研究旨在通过 STIM1/IP3R 调节钙超载途径，研究 HSP70 是否通过调节钙超载途径发挥抗凋亡作用。用无葡萄糖培养基和缺氧孵育 6 小时（模拟短暂氧和葡萄糖剥夺），再用高葡萄糖培养基和再氧合孵育 4 小时（模拟再灌注）处理大鼠 H9C2 细胞，以模拟心肌缺血再灌注诱导的细胞损伤。氧和葡萄糖剥夺后，H9C2 细胞活力明显降低，乳酸脱氢酶（LDH）释放和细胞凋亡明显增加。HSP70 转染可减轻相应作用，增加细胞活力和抗凋亡信号通路，降低细胞凋亡率和促凋亡信号通路。缺氧和再氧合后，HSP70 过表达 H9C2 细胞的 STIM1/IP3R 表达和细胞内钙离子浓度明显低于缺氧细胞。同样，用 siRNA 直接沉默 STIM1 可显著增加细胞活力和抗凋亡蛋白 Bcl-2 的表达，降低细胞凋亡率和促凋亡蛋白 BAX 的表达。这些数据与 HSP70 过表达一致。这些结果表明，HSP70 通过抑制 STIM1/IP3R 表达的上调来减轻细胞内钙超载，从而减少 H9C2 细胞的凋亡，在心肌细胞中发挥保护作用。
