血清-葡萄糖剥夺抑制热休克蛋白90致心肌细胞损伤

Serum-Glucose Deprivation Damaged H9c2 Cardiomyocytes by Inhibiting Heat Shock Protein 90

目的探讨热休克蛋白90(HSP90)表达下调是否参与血清-葡萄糖剥夺(SGD)引起的心肌细胞损伤。方法用血清-葡萄糖剥夺处理H9c2心肌细胞,建立缺血性心肌细胞损伤的体外模型;在血清-葡萄糖剥夺处理前,应用HSP90选择性抑制剂17-AAG预处理心肌细胞60 min;CCK-8比色法检测细胞存活率;Fluo-3AM染色结合荧光显微镜照相术检测细胞内游离钙水平;Western blot检测HSP90和葡萄糖调节蛋白78(GRP78)的表达。结果血清-葡萄糖剥夺处理24 h可明显抑制H9c2心肌细胞内HSP90的表达,诱导细胞内钙超载及上调内质网应激蛋白GRP78的表达。选择性HSP90抑制剂17-AAG预处理不仅可以加重血清-葡萄糖剥夺引起的心肌细胞存活率降低,而且进一步加重血清-葡萄糖剥夺引起的H9c2心肌细胞内钙超载及内质网应激蛋白GRP78的表达上调。结论抑制HSP90可能是血清-葡萄糖剥夺损伤心肌细胞的重要机制之一。

Aim To investigate whether the downregulation of heat shock protein 90 （HSP90） was involved in cardiac cell injury induced by serum-glucose deprivation （SGD）. Methods H9c2 cardiomyocytes （H9c2 ceils） were treated with SGD to establish an in vitro model of ischemic cardiac cell injury. H9c2 cells were pretreated with 17-AAG （ a selective inhibitor of HSP90） for 60 min before exposure of cells to SGD. Cell viability was detected by CCK-8. The intracellular level of free calcium was measured by Fluo-3AM staining and photofluorography. The expressions of HSP90 and glucose-regulated protein 78 （ GPR78 ） were tested by Western blot assay. Results Treatment of H9c2 cells with SGD for 24 h significantly induced downregulation of HSP90 expression, overload of intracellular calcium, and upregulation of GRP78 expression, which is a marker of endoplasmic reticulum stress. Pretreatment with 17-AAG, a selective HSP90 inhibitor, not only aggravated SGD-induced decrease in the viability of H9c2 cells, but also enhanced SGD-induced over- load of intracellular calcium and upregulation of GRP78 expression in H9c2 cells. Conclusion Inhibition of HSP90 may be one of the key mechanisms, by which H9c2 cells were damaged by SGD.