eNOS在 EPO调节慢性缺氧心肌细胞线粒体生物合成中的作用机制研究

目的：探讨内皮型一氧化氮合酶（eNOS）在促红细胞生成素（EPO）调节慢性缺氧环境中心肌细胞线粒体生物合成中的作用及其机制。方法采用H9c2心肌细胞，将其于缺氧环境下培养7 d （94％ N2，5％ O2），建立心肌细胞慢性缺氧模型。将心肌细胞根据不同处理分为缺氧对照组（HC），20 U／mL重组人 EPO（rhEPO）处理缺氧组（HE）和20 U／mL rhEPO＋ eNOS shRNA干扰处理缺氧组（HR）。以荧光探针检测线粒体数量变化；RT‐PCR检测线粒体DNA相对表达量；Western blot 检测eNOS总蛋白表达及磷酸化水平（p‐eNOS）变化。结果 rhEPO显著增强eNOS磷酸化水平，增加线粒体数量及其DNA相对拷贝数（P＜0．05）；而同时采用shRNA干扰eNOS后，HR组eNOS总蛋白表达及磷酸化水平较HE组降低（P＜0．05），同时线粒体数量及其DNA相对拷贝数较 HE组减少（P＜0．05）。结论 eNOS的磷酸化激活是EPO增强慢性缺氧心肌细胞线粒体生物合成的重要信号转导机制。

The role of eNOS on the regulatory effects of EPO on mitochondrial biogenesis in cardiomyocytes exposed to chronic hypoxia

Objective To explore the role of endothelial nitric oxide synthase(eNOS) in the regulatory effects of erythropoie‐tin (EPO) on mitochondiral biogenesis in cardiomyocytes exposed to chronic hypoxia .Methods H9c2 cardiomyocytes were cultured in the environment of hypoxia for 1 week(94% N2 ,5% O2 ) ,establishing the chronic hypoxic cardiomyocyte model .All the cells were divided into 3 groups :HC(chronic hypoxic control) ,HEtreated with chronic hypoxia and 20 U/mL recombinant human EPO (rhEPO) ]and HR(cells transfected with eNOS shRNA plasmid and treated with 20 U/mL rhEPO and chronic hypoxia) .Fluores‐cent probe was used to detect the changes of mitochondial number .Mitochondial DNA (mtDNA) relative express level was assayed by RT‐PCR .The expression and phosphorylation of eNOS protein were analyzed with Western blot .Results rhEPO significantly increased the phosphorylation of eNOS and elavated the mitochondialt number and mtDNA (P< 0 .05) .shRNA interference on eNOS significantly blocked all the above changes induced by rhEPO (P<0 .05) .Conclusion Phosphory lation of eNOS is the im‐portant signalling pathway for the enhanced mitochondrial biogenesis in cardiomyocytes exposed to chronic hypoxia by EPO .