Objective: To explore the role and related mechanism of mammalian sterile 20-like kinase 1(Mst-1)in regulating hypoxia reoxygenation (HR) induced myocardial cell autophagy and apoptosis. Methods: Enzyme digestion method combined with differential adherent method was used to culture neonatal mouse myocardial cells. HR model was established by hypoxia for 24 hours and reoxygenation for 6 hours. The experimental groups including control group (normal cultured cardiomyocytes), Mst-1 empty virus group (cardiomyocytes transfected with recombinant lentiviral empty vector for 48 hours), Mst-1 knockdown group (recombinant lentivirus carrying Mst-1small interfering RNA (siRNA) was transfected into cardiomyocytes for 48 hours), Mst-1 overexpression group (cardiomyocytes were transfected with recombinant lentivirus carrying Mst-1 gene for 48 hours), HR group (cardiomyocytes exposed to HR), Mst-1 knockdown+HR group (HR model of cardiomyocyte was established 48 hours after transfection with recombinant lentivirus carrying Mst-1siRNA) and Mst-1 overexpression+HR group (HR model of cardiomyocyte was established 48 hours after transfection with recombinant lentivirus carrying Mst-1 gene). Real-time fluorescence quantitative RCR (qPCR) and Western blot were used to detect the relative expression of Mst-1 mRNA and protein in the cells, immunofluorescence staining was used to detect cardiomyocyte troponin T (cTnT), and autophagosomes and autophagy enzyme changes. TUNEL method was used to detect myocardial cell apoptosis, Western blot was adopted to detect autophagy-related protein microtubule-related protein 1 light chain 3 (LC3) Ⅱ/LC3 Ⅰ, P62 and apoptosis-related protein cleaved-caspase 9, pro-caspase 9, cleaved-caspase-3, pro-caspase-3, and myeloid leukemia 1 (MCL-1) expression. MCL-1 inhibitor A1210477 was used to validate the signaling pathway of Mst-1 on regulating cardiomyocyte apoptosis and autophagy. Results: Immunofluorescence detection revealed that the cultured cells expressed cardiomyocyte-specific marker cTnT. The expression of Mst-1 in cardiomyocytes increased in HR model. Lentiviral transfection could effectively inhibit or overexpress Mst-1 in treated cells. The levels of autophagosomes and autophagolysosomes in cardiomyocytes undergoing HR and in Mst-1 overexpression+HR group were lower than those of control group, while autophagosomes and autophagolysosomes in cardiomyocytes of Mst-1 knockdown+HR group was significantly higher than in the HR group (all P<0.05). The TUNEL results showed that the proportion of TUNEL positive cells was significantly increased in the HR group and Mst-1 overexpression+HR group than in the control group, while the proportion of TUNEL positive cells was significantly decreased in the Mst-1 knockdown group+HR group as compared to the HR group (all P<0.05). Western blot results showed that the LC3 Ⅱ/LC3 Ⅰ levels were significantly lower, while the expression levels of P62, cleaved-caspase-9 and cleaved-caspase-3 were significantly higher in the HR group and Mst-1 overexpression+HR group than in control group (all P<0.05). The LC3 Ⅱ/LC3 Ⅰ value was significantly higher, and the expression levels of P62, cleaved-caspase-9 and cleaved-caspase-3 were significantly lower in the Mst-1 knockdown+HR group than in the HR group (P both<0.05). The expression level of P-MCL-1 protein was significantly lower in cardiomyocytes of HR and Mst-1 overexpression+HR group than in control group, and the expression level of P-MCL-1 protein was higher in Mst-1 knockdown+HR group than in HR group (P both<0.05). The recovery experiment showed that inhibiting MCL-1 in cells can block the regulatory effect of Mst-1 siRNA on cell autophagy and apoptosis. Conclusion: Inhibiting Mst-1 expression in cardiomyocytes can promote the autophagy of cardiomyocytes induced by hypoxic reoxygenation and reduce the apoptosis of cardiomyocytes via activating McL-1.
目的： 探索小鼠心肌细胞中哺乳动物不育系20样激酶1（mammalian sterile 20-like kinase 1，Mst-1）调控缺氧复氧（hypoxia reoxygenation，HR）诱导的心肌细胞自噬及凋亡机制。 方法： 采用酶消化法结合差速贴壁的方法培养小鼠乳鼠心肌细胞，通过缺氧24 h复氧6 h的方法建立HR模型。实验分组：对照组：正常培养的心肌细胞；Mst-1空病毒组：用重组慢病毒空载体转染心肌细胞48 h；Mst-1敲低组：用携带Mst-1小干扰RNA（siRNA）的重组慢病毒转染心肌细胞48 h；Mst-1过表达组：用携带Mst-1基因的重组慢病毒转染心肌细胞48 h；HR组：建立心肌细胞HR模型；Mst-1敲低+HR组：用携带Mst-1 siRNA的重组慢病毒转染心肌细胞后48 h建立心肌细胞HR模型；Mst-1过表达+HR组：用携带Mst-1基因的重组慢病毒转染心肌细胞后48 h建立心肌细胞HR模型。采用实时荧光定量RCR（qPCR）以及Western blot检测细胞中Mst-1 mRNA及蛋白相对表达量，免疫荧光染色检测心肌细胞标志物心肌肌钙蛋白T（cTnT），及细胞自噬体与自噬溶酶体变化，脱氧核糖核苷酸末端转移酶介导的缺口末端标记（TUNEL）法检测心肌细胞凋亡水平，Western blot检测自噬相关蛋白微管相关蛋白1轻链3（LC3）Ⅱ/LC3Ⅰ，P62及凋亡相关蛋白半胱氨酸天冬氨酸酶剪切体（cleaved-caspase）9、半胱氨酸天冬氨酸酶前体（pro-caspase）9、cleaved-caspase-3、pro-caspase-3，以及髓细胞白血病1基因（MCL-1）的表达情况达。予以MCL-1抑制剂A1210477做回复实验，验证Mst-1通过调控MCL-1参与心肌细胞凋亡及自噬。 结果： 免疫荧光检测发现培养细胞表达心肌细胞特异性标志物cTnT；HR情况下心肌细胞中Mst-1表达增加，慢病毒转染可有效抑制或过表达细胞中Mst-1。HR组与Mst-1过表达+HR组心肌细胞内自噬体及自噬溶酶体含量低于对照组，而Mst-1敲低+HR组心肌细胞内自噬体及自噬溶酶体含量高于HR组（P均<0.05）。TUNEL结果显示，HR组及Mst-1过表达+HR组中TUNEL阳性细胞比例高于对照组，而Mst-1敲低组+HR组中TUNEL阳性细胞比例低于HR组（P均<0.05）。Western blot结果显示，与对照组比较，HR组及Mst-1过表达+HR组细胞中LC3 Ⅱ/LC3 Ⅰ值较低，P62与 cleaved-caspase-9、cleaved-caspase-3表达水平较高（P均<0.05）；与HR组比较，Mst-1敲低+HR组中LC3 Ⅱ/LC3 Ⅰ值较高，P62与cleaved-caspase-9、cleaved-caspase-3表达水平较低（P均<0.05）。HR与Mst-1过表达+HR组心肌细胞中磷酸化（P）MCL-1蛋白表达水平低于对照组，Mst-1敲低+HR组的P-MCL-1蛋白表达水平高于HR组（P均<0.05）。回复实验显示抑制细胞中MCL-1可阻断Mst-1 siRNA 对细胞自噬及凋亡的调节作用。 结论： 抑制心肌细胞中Mst-1的表达，可促进HR诱导的心肌细胞自噬，改善心肌细胞凋亡，该作用可能与其调控MCL-1表达相关。.
Keywords: Apoptosis; Autophagy; Mammalian sterile 20-like kinase 1; Myeloid cell lekemia-1; Myocytes, cardiac.