有氧运动通过上调Dhcr24改善H_(2)O_(2)诱导的心肌细胞凋亡机制研究

Aerobic exercise reduces H_(2)O_(2)-induced cardiomyocyte apoptosis through upregulating Dhcr24 expression

目的研究24-脱氢胆固醇还原酶(Dhcr24)在有氧运动改善心肌梗死后心肌细胞功能中的潜在作用及分子机制。方法通过H_(2)O_(2)建立心肌细胞H9C2凋亡模型,并通过腺苷酸活化蛋白激酶(AMPK)激动剂5-氨基咪唑-4-甲酰胺核苷酸(AICAR)来模拟心肌细胞的运动效果。通过流式细胞术和TUNEL检测心肌细胞凋亡水平;通过Western blot检测心肌细胞凋亡相关蛋白Bcl-2、Bax和Dhcr24表达水平;通过RT-qPCR检测细胞Dhcr24 mRNA表达水平。结果与对照组比较,H_(2)O_(2)诱导的心肌细胞凋亡率增加[(20.75±1.28)%比(5.21±0.34)%,P<0.05],TUNEL阳性粒子数升高,抗凋亡蛋白Bcl-2水平降低,促凋亡蛋白Bax水平升高,Dhcr24水平降低[(0.56±0.07)比(1.00±0.15),P<0.05]。与H_(2)O_(2)诱导的心肌细胞比较,AMPK激活剂AICAR处理后,心肌细胞凋亡率降低[(10.67±2.11)%比(21.82±3.22)%,P<0.05],TUNEL阳性粒子数降低,Dhcr24水平升高。在H_(2)O_(2)和AICAR共同处理的心肌细胞中敲低Dhcr24,降低的细胞凋亡率[(15.71±1.57)%比(9.50±0.89)%,P<0.05]和TUNEL阳性粒子数得到逆转。结论有氧运动对H_(2)O_(2)诱导的心肌细胞凋亡具有明显保护作用,可能与其上调Dhcr24表达有关。

Objective To assess the potential role and molecular mechanism of Dhcr24 in improving cardiomyocyte function after myocardial infarction by aerobic exercise.Methods An in vitro apoptosis model of cardiomyocytes H9C2 was established by H_(2)O_(2)and the exercise effect of cardiomyocytes was simulated by adenosine monophosphate-activated protein kinase(AMPK)agonist 5-aminimidazole-4-formamide nucleotide(AICAR).Cardiomyocyte apoptosis was assessed by using flow cytometry and TUNEL and levels of apoptosis-related proteins(Bcl-2 and Bax)and Dhcr24 were detected by Western blot.Level of Dhcr24 mRNA was assayed by using RT-qPCR.Results Compared with the controls,H_(2)O_(2)increased myocardial cell apoptosis(20.75±1.28 vs.5.21±0.34%;P<0.05)and numbers of TUNEL-positive particles and level of pro-apoptotic protein Bax,but reduced level of anti-apoptotic protein Bcl-2 and Dhcr24(0.56±0.07 vs.1.00±0.15;P<0.05).Moreover,compared with H_(2)O_(2)-induced cardiomyocyte apoptosis,AICAR treatment decreased the apoptotic rate(10.67±2.11 vs.21.82±3.22%;P<0.05)and numbers of TUNEL-positive particles,but increased level of Dhcr24 protein.In cardiomyocytes treated with H_(2)O_(2)and AICAR,knockdown of Dhcr24 expression reversed the decreased apoptosis rate(15.71±1.57 vs.9.50±0.89%;P<0.05)and the numbers of TUNEL-positive particles.Conclusion Aerobic exercise plays a protective role in H_(2)O_(2)-induced cardiomyocyte apoptosis,which could be related to upregulation of Dhcr24 expression.