Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) & Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China.
Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) & Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China; Division of Molecular Medicine, Department of Anesthesiology, David Geffen School of Medicine at UCLA, Los Angeles, USA.
J Mol Cell Cardiol. 2015 Apr;81:150-61. doi: 10.1016/j.yjmcc.2015.02.015. Epub 2015 Feb 27.
Moderate enhanced reactive oxygen species (ROS) during early reperfusion trigger the cardioprotection against ischemia/reperfusion (I/R) injury, while the mechanism is largely unknown. Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) contributes to the cardioprotection but whether it is activated by ROS and how it regulates Ca(2+) homeostasis remain unclear. Here we investigated whether the ROS generated during early reperfusion protect the heart/cardiomyocyte against I/R-induced Ca(2+) overload and contractile dysfunction via the activation of JAK2/STAT3 signaling pathway by using a cardioprotective model of intermittent hypobaric hypoxia (IHH) preconditioning. IHH improved the postischemic recovery of myocardial contractile performance in isolated rat I/R hearts as well as Ca(2+) homeostasis and cell contraction in simulated I/R cardiomyocytes. Meanwhile, IHH enhanced I/R-increased STAT3 phosphorylation at tyrosine 705 in the nucleus and reversed I/R-suppressed STAT3 phosphorylation at serine 727 in the nucleus and mitochondria during reperfusion. Moreover, IHH improved I/R-suppressed sarcoplasmic reticulum (SR) Ca(2+)-ATPase 2 (SERCA2) activity, enhanced I/R-increased Bcl-2 expression, and promoted the co-localization and interaction of Bcl-2 with SERCA2 during reperfusion. These effects were abolished by scavenging ROS with N-(2-mercaptopropionyl)-glycine (2-MPG) and/or by inhibiting JAK2 with AG490 during the early reperfusion. Furthermore, IHH-improved postischemic SERCA2 activity and Ca(2+) homeostasis as well as cell contraction were reversed after Bcl-2 knockdown by short hairpin RNA. In addition, the reversal of the I/R-suppressed mitochondrial membrane potential by IHH was abolished by 2-MPG and AG490. These results indicate that during early reperfusion the ROS/JAK2/STAT3 pathways play a crucial role in (i) the IHH-maintained intracellular Ca(2+) homeostasis via the improvement of postischemic SERCA2 activity through the increase of SR Bcl-2 and its interaction with SERCA2; and (ii) the IHH-improved mitochondrial function.
中度增强的活性氧（ROS）在再灌注早期触发对缺血/再灌注（I/R）损伤的心脏保护作用，但机制尚不清楚。Janus 激酶 2（JAK2）/信号转导和转录激活因子 3（STAT3）有助于心脏保护，但它是否被 ROS 激活以及如何调节 Ca（2+）稳态尚不清楚。在这里，我们通过使用间歇性低氧预处理的心脏保护模型研究了再灌注早期产生的 ROS 是否通过激活 JAK2/STAT3 信号通路来保护心脏/心肌细胞免受 I/R 诱导的 Ca（2+）过载和收缩功能障碍，间歇性低氧预处理（IHH）。IHH 改善了离体大鼠 I/R 心脏的缺血后收缩功能恢复以及模拟 I/R 心肌细胞中的 Ca（2+）稳态和细胞收缩。同时，IHH 增强了再灌注期间核内 STAT3 酪氨酸 705 磷酸化和核内及线粒体中 I/R 抑制的 STAT3 丝氨酸 727 磷酸化。此外，IHH 改善了 I/R 抑制的肌浆网（SR）Ca（2+）-ATP 酶 2（SERCA2）活性，增强了 I/R 诱导的 Bcl-2 表达，并促进了再灌注期间 Bcl-2 与 SERCA2 的共定位和相互作用。这些作用在再灌注早期用 N-（2-巯基丙酰基）-甘氨酸（2-MPG）清除 ROS 和/或用 AG490 抑制 JAK2 时被消除。此外，用短发夹 RNA 敲低 Bcl-2 后，IHH 改善的缺血后 SERCA2 活性和 Ca（2+）稳态以及细胞收缩被逆转。此外，IHH 逆转的 I/R 抑制的线粒体膜电位被 2-MPG 和 AG490 消除。这些结果表明，在再灌注早期，ROS/JAK2/STAT3 途径通过增加 SR Bcl-2 及其与 SERCA2 的相互作用来改善缺血后 SERCA2 活性，从而在（i）通过改善缺血后 SERCA2 活性维持细胞内 Ca（2+）稳态方面发挥关键作用；和（ii）IHH 改善的线粒体功能。
