Hanlon Paul R, Fu Ping, Wright Gary L, Steenbergen Charles, Arcasoy Murat O, Murphy Elizabeth
Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA.
FASEB J. 2005 Aug;19(10):1323-5. doi: 10.1096/fj.04-3545fje. Epub 2005 Jun 9.
Langendorff-perfused rat hearts treated with EPO exhibited significantly improved postischemic recovery of left ventricular developed pressure (LVDP) and reduced infarct size compared with control hearts. Perfusion with the mitogen/extracellular signal-regulated kinase (MEK) inhibitor U0126 just before and concomitant with EPO treatment abolished EPO-induced phosphorylation of the MEK substrate extracellular signal-regulated kinase (ERK) but had no effect of EPO-mediated cardioprotection. EPO treatment of the perfused hearts induced translocation of protein kinase C (PKC) epsilon isoform to the membrane fraction of the hearts and the protective effect of EPO was significantly inhibited by the PKC catalytic inhibitor chelerythrine added before and concomitant with EPO. These data demonstrate that EPO-mediated activation of the PKC signaling pathway before or during ischemia is required for the cardioprotective effect of EPO during ischemia-reperfusion injury. Perfusion with the phosphatidylinositol 3-kinase (PI3K) inhibitors LY294002 or wortmannin just before and concomitant with EPO treatment attenuated EPO-induced phosphorylation of the PI3K substrate Akt but had no effect on EPO-mediated cardioprotection. However, when wortmannin was added during EPO treatment and continued during reperfusion, EPO-mediated cardioprotection was significantly inhibited. We also show that postischemia EPO treatment at the onset of reperfusion significantly improved recovery of LVDP and reduced infarct size. Postischemia cardioprotection by EPO required the PI3K pathway but was not affected by inhibition of PKC at the time of EPO treatment.
与对照心脏相比，用促红细胞生成素（EPO）处理的Langendorff灌注大鼠心脏在缺血后左心室舒张末压（LVDP）的恢复显著改善，梗死面积减小。在EPO处理前及处理过程中用丝裂原/细胞外信号调节激酶（MEK）抑制剂U0126灌注，可消除EPO诱导的MEK底物细胞外信号调节激酶（ERK）的磷酸化，但对EPO介导的心脏保护作用无影响。EPO处理灌注心脏可诱导蛋白激酶C（PKC）ε亚型转位至心脏的膜部分，并且在EPO处理前及处理过程中添加PKC催化抑制剂白屈菜红碱可显著抑制EPO的保护作用。这些数据表明，在缺血前或缺血期间EPO介导的PKC信号通路激活是EPO在缺血再灌注损伤期间发挥心脏保护作用所必需的。在EPO处理前及处理过程中用磷脂酰肌醇3激酶（PI3K）抑制剂LY294002或渥曼青霉素灌注，可减弱EPO诱导的PI3K底物Akt的磷酸化，但对EPO介导的心脏保护作用无影响。然而，当在EPO处理期间添加渥曼青霉素并在再灌注期间持续使用时，EPO介导的心脏保护作用被显著抑制。我们还表明，在再灌注开始时进行缺血后EPO处理可显著改善LVDP的恢复并减小梗死面积。EPO的缺血后心脏保护作用需要PI3K通路，但在EPO处理时不受PKC抑制的影响。
