线粒体融合素2通过Ras-PI3K-Akt信号途径抑制缺血再灌注诱导的乳鼠心肌细胞凋亡

目的：研究线粒体融合素2（Mfn2）基因对缺血再灌注诱导的乳鼠心肌细胞凋亡的影响及其相关的信号通路。方法：乳鼠心肌细胞经缺氧/复氧（H/Re）处理模拟心肌缺血再灌注损伤。用Mfn2基因的重组腺病毒（Adv-Mfn2）感染经缺氧复氧处理的乳鼠心肌细胞。采用TUNEL染色、ELISA、流式细胞术等方法检测Mfn2对缺血再灌注诱导的乳鼠心肌细胞凋亡的影响。Western blot分析线粒体凋亡路径中Bcl-2蛋白、Bax蛋白、Caspase-9以及磷酸化蛋白激酶B（p-Akt）的表达变化。结果：TUNEL染色发现Adv-Mfn2感染乳鼠心肌细胞后,细胞凋亡较H/Re组和Adv-LacZ组显著减少。ELISA和流式细胞仪检测结果表明,Adv-Mfn2组心肌细胞凋亡较H/Re组及Adv-LacZ组明显减少,且这一作用呈时间依赖性。Western blot结果显示,Adv-Mfn2组中Bcl-2蛋白表达较H/Re组和Adv-LacZ感染组上升,Bax蛋白表达下降,各组中Caspase-9的表达变化与Bax相同,Adv-Mfn2组的p-Akt蛋白表达水平则较H/Re组和Adv-LacZ感染组明显上升。结论：Mfn2基因主要通过正向调控RasPI3K-Akt信号通路,促进Akt的磷酸化水平,使Bcl-2蛋白表达量增加,Bax蛋白表达量降低,抑制Caspase-9活化,从而抑制缺血再灌注诱导的乳鼠心肌细胞凋亡。

Mfn2 gene transfer inhibites neonatal rat cardiomyocytes apoptosis induced by ischemia/reperfusion via activation of the Ras-PI3K-Akt signaling pathway

AIM. To investigate the effect of Mfn2 gene transfer on inhibiting the apoptosis of cardiomyocytes induced by ischemia/reperfusion. METHODS： Treating neonatal rat cardio- myocytes by hypoxia/reoxygenation to simulating myocardial ischemia/reperfusion injury. And then the cardiomyocytes were infected by adenovirus-mediated Mfn2 （ Adv-Mfn2 ）.TUNEL staining, cell death ELISA and FACS analysis were used to investigate the role of AdvMfn2 gene transfer on neonatal rat cardiomyocytes apoptosis. Western blot was used to analyze the protein expression of Bcl-2, Bax, cleaved caspase-9 and p-Akt. RESULTS： TUNEL staining evidenced that there were less positive-apoptoic cardiomyocytes in Adv-Mfn2 group than in H/Re group and Adv-LacZ group （P〈0.01）. ELISA and FACS results showed that cardiomyocytes apoptosis in Adv-Mfn2 group was significantly reduced compared with H/Re group and Adv-LacZ group, and this effect was time-dependent （P〈0.01）. The protein expression of Bcl-2 and phosphorylated Akt were significantly upregulated in Adv-Mfn2 group （P 〈 0.05）, whereas Bax and cleaved caspase-9 protein expressions were significantly downregulated in Adv-Mfn2 group （P〈0.05）.CONCLUSION： Mfn2 gene promotes the protein expression of Bcl-2 and phosphorylated Akt, supppres the protein expression of Bax and cleaved caspase-9 via activation of the Ras-PIaKAkt signaling pathway to inhibite neonatal rat cardiomyocytes apoptosis induced by ischemia/ reperfusion.