Role of PI3Kα and sarcolemmal ATP-sensitive potassium channels in epoxyeicosatrienoic acid mediated cardioprotection
Role of PI3Kα and sarcolemmal ATP-sensitive potassium channels in epoxyeicosatrienoic acid mediated cardioprotection
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DOI：
10.1016/j.yjmcc.2012.04.008
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发表时间：
2012-07-01
影响因子：
5
通讯作者：
Seubert, John M.
中科院分区：
文献类型：
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作者：
Batchu, Sri N.;Chaudhary, Ketul R.;Seubert, John M.
目的：环氧二十碳三烯酸 (EET) 是花生四烯酸的细胞色素 P450 环氧化酶代谢物，具有已知的心脏保护特性。虽然其机制仍不清楚，但有证据表明磷酸肌醇 3-激酶 (PI3K) 和肌膜 ATP 敏感钾通道 (pmK(ATP)) 很重要。然而，特定 PI3K 异构体的作用和相应的细胞内机制仍然未知。 方法和结果：为了研究这一点，小鼠心脏在 Langendorff 模式下灌注 40 分钟基线，并经历 20 或 30 分钟整体无流量缺血，然后再灌注 40 分钟。用 11,12-EET (1 μM) 灌注的 C57BL6 小鼠改善了缺血后恢复，而与 PI3K α 抑制剂 PI-103 (0.1 μM) 共灌注则消除了 EET 介导的作用。相反，阻断 PI3K β 或 PI3K γ 亚型未能抑制 EET 介导的心脏保护作用。除了改善缺血后恢复外，在 EET 处理的心脏中还发现 p-Akt 水平增加、钙调神经磷酸酶活性降低以及促凋亡蛋白 BAD 向线粒体的易位减少。将 11,12-EET 灌注至 Kir6.2 缺陷小鼠 (pmK(ATP)) 未能改善缺血后恢复、降低钙调神经磷酸酶活性和促凋亡蛋白 BAD 易位，但仍观察到 p-Akt 水平升高。膜片钳实验表明，11,12-EET 不能激活经 PI-103 预处理的肌细胞中的 pmK(ATP) 电流。 H9c2 细胞的机制研究表明，与对照组相比，11,12-EET 限制缺氧复氧引发的 Ca2+ 积累，并维持线粒体 Delta psi m。 PI-103 和格列本脲（10 μM，pmK(ATP) 抑制剂）均消除了 EET 细胞保护作用。结论：我们的数据表明，EET 介导的心脏保护作用涉及激活 pmK(ATP) 上游的 PI3K α，从而防止 Ca2+ 过载并维持线粒体功能。 (c) 2012 Elsevier Ltd. 保留所有权利。
Aims: Epoxyeicosatrienoic acids (EETs) are cytochrome P450 epoxygenase metabolites of arachidonic acid that have known cardioprotective properties. While the mechanism(s) remains unknown, evidence suggests that phosphoinositide 3-kinase (PI3K) and sarcolemmal ATP-sensitive potassium channels (pmK(ATP)) are important. However the role of specific PI3K isoforms and corresponding intracellular mechanisms remains unknown.Methods and results: To study this, mice hearts were perfused in Langendorff mode for 40 min of baseline and subjected to 20 or 30 min of global no-flow ischemia followed by 40 min of reperfusion. C57BL6 mice perfused with 11,12-EET (1 mu M) had improved postischemic recovery, whereas co-perfusion with PI3K alpha inhibitor, PI-103 (0.1 mu M), abolished the EET-mediated effect. In contrast, blocking of PI3K beta or PI3K gamma isoforms failed to inhibit EET-mediated cardioprotection. In addition to the improved post-ischemic recovery, increased levels of p-Akt, decreased calcineurin activity and decreased translocation of proapoptotic protein BAD to mitochondria were noted in EET-treated hearts. Perfusion of 11,12-EET to Kir6.2 deficient mice (pmK(ATP)) failed to improve postischemic recovery, decrease calcineurin activity and translocation of proapoptotic protein BAD, however increased levels of p-Akt were still observed. Patch-clamp experiments demonstrated that 11,12-EET could not activate pmK(ATP) currents in myocytes pre-treated with PI-103. Mechanistic studies in H9c2 cells demonstrate that 11,12-EET limits anoxia-reoxygenation triggered Ca2+ accumulation and maintains mitochondrial Delta psi m compared to controls. Both PI-103 and glibenclamide (10 mu M, pmK(ATP) inhibitor) abolished EET cytoprotection.Conclusion: Together our data suggest that EET-mediated cardioprotection involves activation of PI3K alpha, upstream of pmK(ATP), which prevents Ca2+ overload and maintains mitochondrial function. (c) 2012 Elsevier Ltd. All rights reserved.