Sirt1 promotes autophagy and inhibits apoptosis to protect cardiomyocytes from hypoxic stress
Sirt1 promotes autophagy and inhibits apoptosis to protect cardiomyocytes from hypoxic stress
复制标题
Sirt1促进自噬并抑制细胞凋亡以保护心肌细胞免受缺氧应激
DOI：
10.3892/ijmm.2019.4125
复制
发表时间：
2019-05-01
影响因子：
5.4
通讯作者：
Xiao, Yingbin
中科院分区：
文献类型：
--
作者：
Luo, Guiping;Jian, Zhao;Xiao, Yingbin
Sirtuin1(sirtuin 1，Sirt1)通过多种细胞活动在多种心血管疾病中发挥心脏保护作用。然而，Sirt1在低氧心肌细胞中的治疗意义和潜在的机制仍然不清楚。本研究调查了Sirt1是否调节低氧H9C2心肌细胞和实验性低氧小鼠模型的自噬和凋亡。右室流出道活检取自青紫型或非青紫型先天性心脏病患者。用腺病毒Ad-Sirt1激活Sirt1，用Ad-Sh-Sirt1抑制H9C2细胞Sirt1的表达，观察Sirt1对细胞自噬和细胞凋亡的影响。将Sirt1的药理激活剂SRT1720和Sirt1拮抗剂EX-527分别应用于小鼠，以探讨Sirt1在体内缺氧心肌细胞中的作用。免疫印迹法检测细胞自噬和凋亡相关蛋白的表达水平。采用原位末端标记法和Annexin V/7-氨基放线菌素D流式细胞术检测细胞凋亡。青紫型患者的心脏组织样本显示，与非紫青型对照样本相比，自噬和细胞凋亡增加，Sirt1水平升高。蛋白质印迹分析结果显示，Sirt1促进了缺氧H9C2细胞的自噬通量，减少了细胞凋亡。此外，Sirt1激活了AMPK，AMPK抑制剂化合物C取消了Sirt1对自噬激活的影响。对该机制的进一步探讨揭示了Sirt1至少部分地通过肌醇需要激酶1α(IRE1α)来保护缺氧心肌细胞免受凋亡的影响。与体外实验结果一致的是，Sirt1激活剂SRT1720与缺氧对照组相比，激活了AMPK，抑制了IRE1α，增强了自噬，减少了细胞凋亡。在用Sirt1抑制剂EX-527治疗的低氧小鼠中，观察到相反的变化。这些结果提示Sirt1通过激活AMPK促进自噬，通过IRE1α途径减少缺氧诱导的细胞凋亡，从而保护心肌细胞免受低氧应激的伤害。
Sirtuin 1 (Sirt1) exerts its cardioprotective effects in various cardiovascular diseases via multiple cellular activities. However, the therapeutic implications of Sirt1 in hypoxic cardiomyocytes and the underlying mechanisms remain elusive. The present study investigated whether Sirt1 regulates autophagy and apoptosis in hypoxic H9C2 cardiomyocytes and in an experimental hypoxic mouse model. Right ventricular outflow tract biopsies were obtained from patients with cyanotic or acyanotic congenital heart diseases. Adenovirus Ad-Sirt1 was used to activate Sirt1 and Ad-Sh-Sirt1 was used to inhibit Sirt1 expression in H9C2 cells, in order to investigate the effect of Sirt1 on cellular autophagy and apoptosis. SRT1720, a pharmacological activator of Sirt1 and EX-527, a Sirt1 antagonist, were administered to mice to explore the role of Sirt1 in hypoxic cardiomyocytes in vivo. The levels of autophagy and apoptosis-related proteins were evaluated using western blotting. Apoptosis was investigated by TUNEL staining and Annexin V/7-aminoactinomycin D flow cytometry analysis. Heart tissue samples from cyanotic patients exhibited increased autophagy and apoptosis, as well as elevated Sirt1 levels, compared with the noncyanotic control samples. The data from the western blot analysis revealed that Sirt1 promoted autophagic flux and reduced apoptosis in hypoxic H9C2 cells. In addition, Sirt1 activated AMP-activated protein kinase (AMPK), and the AMPK inhibitor Compound C abolished the effect of Sirt1 on autophagy activation. Further exploration of the mechanism revealed that Sirt1 protects hypoxic cardiomyocytes from apoptosis, at least in part, through inositol requiring kinase enzyme 1α (IRE1α). Consistent with the in vitro results, treatment with the Sirt1 activator SRT1720 activated AMPK, inhibited IRE1α, enhanced autophagy, and decreased apoptosis in the heart tissues of normoxic mice compared with the hypoxia control group. Opposite changes were observed in hypoxic mice treated with the Sirt1 inhibitor EX-527. These results suggested that Sirt1 promoted autophagy via AMPK activation and reduced hypoxia-induced apoptosis via the IRE1α pathway, to protect cardiomyocytes from hypoxic stress.