PPAR-α通过PI3K/Akt/FoxO1信号通路对心肌细胞肥大的负性调控作用

摘要

目的：研究过氧化物酶体增殖物激活受体α(peroxisome proliferators activated receptor alpha, PPAR-α)对心肌细胞肥大的负性调控作用以及与PI3K/Akt/叉头框蛋白O1(Forkhead box O1, FoxO1)信号通路和氧化应激的关系。方法：应用异丙肾上腺素(isoproternol, ISO)诱导心肌细胞肥大；采用Leica图像分析软件测量心肌细胞表面积；应用实时定量聚合酶链式反应(real time quantitative polymerase chain reaction, qRT-PCR)检测心房利钠肽(atrial natriuretic peptide, ANP)、β-肌球蛋白重链(β-myosin heavy chain,β-MHC)、PPAR-α及FoxO1 mRNA表达；采用试剂盒检测心肌细胞超氧化物歧化酶(superoxide dismutase, SOD)活性和丙二醛(malondialdehyde, MDA)含量。结果：(1)ISO诱导心肌细胞肥大，PPAR-αmRNA表达显著下降。(2)应用非诺贝特(Fenofibrate, Feno)上调PPAR-α表达明显抑制ISO诱导的心肌细胞表面积、ANP和β-MHC mRNA表达的增加。(3)ISO诱导心肌细胞肥大，FoxO1表达明显减少；应用Feno预处理可增加FoxO1 mRNA的表达；应用PI3K抑制剂LY预处理亦能明显增加FoxO1 mRNA表达。(4)ISO诱导心肌细胞肥大，心肌细胞SOD活性明显降低，MDA含量明显增加，应用Feno预处理能显著提高SOD活性，降低MDA含量。结论：PPAR-α抑制心肌细胞肥大的作用可能与其抑制PI3K/Akt通路的激活，提高FoxO1的表达，降低氧化应激反应有关。%Objective: To investigate the negative regulation of peroxisome proliferators activated receptor alpha(PPAR-α) on the cardiomyocyte hypertrophy and the interaction of PPAR-α with PI3K/Akt/Forkhead box O1(FoxO1) signaling pathway and the oxidative stress response. Methods: Isoprenaline(ISO) was applied to induce cardiomyocyte hypertrophy. Cell morphology was imaged by phase-contrast microscopy and cell surface area was measured by Leica image analysis software. The expression of atrial natriuretic peptide(ANP), β-myosin heavy chain(β-MHC), PPAR-α, Forkhead box O1(FoxO1) mRNA were assessed by realtime quantitative polymerase chain realtion(qRT-PCR). The activity of superoxide dismutase(SOD) and malondialdebyde(MDA) were detected to discover the change of oxygen free radical. Results: (1) Cardiomyocyte hypertrophy was induced by isoproterenol. The expression of PPAR-α was significantly reduced in cardiomyocyte hypertrophy. (2)Application of Feno upregulated the expression of PPAR-α, which could inhibite cell surface and the expression of ANP, β-MHC mRNA in cardiomyocytes. (3)The expression of FoxO1 was inhibited by ISO. Feno or LY could increase the mRNA expression of FoxO1.(4)ISO could reduce the SOD activity, significantly elevate the expression of MDA. Feno significantly increased SOD activity, decreased the expression of MDA. Conclusion: PPAR-α can inhibit PI3K/Akt signal pathway, elevate the expression of FoxO1 and reduce oxidative stress, resulting in the attenuation of cardiomyocyte hypertrophy.