Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0575, USA.
Cardiovasc Res. 2012 May 1;94(2):379-90. doi: 10.1093/cvr/cvs096. Epub 2012 Feb 21.
While a wealth of data has uncovered distinct microRNA (miR) expression alterations in hypertrophic and ischaemic/reperfused (I/R) hearts, little is known about miR regulation and response to ischaemic preconditioning (IPC).
We analysed miRs in murine hearts preconditioned with six cycles of 4 min ischaemia via coronary artery occlusion, followed by 4 min reperfusion in vivo. Both miRs within the miR-144/451 cluster were the most elevated among a cohort of 21 dysregulated miRs in preconditioned hearts, compared with shams. To investigate the significance of this finding, we examined IPC-mediated cardioprotection within a miR-144/451-knockout (KO) mouse model. Wild-type (WT) hearts exposed to IPC followed by I/R (30 min/24 h) showed a smaller infarction size compared with mice treated with I/R alone. In contrast, IPC failed to protect miR-144/451-KO hearts against infarct caused by I/R treatment. Thus, the miR-144/451 cluster is required for IPC-elicited cardioprotection. Rac-1, a key component of NADPH oxidase, was mostly up-regulated in KO hearts among three bona fide targets (Rac-1, 14-3-3ζ, and CUGBP2) for both miR-144 and miR-451. Accordingly, reactive oxygen species (ROS) levels were markedly increased in KO hearts upon IPC, compared with IPC-WT hearts. Pre-treatment of KO hearts with a Rac-1 inhibitor NSC23766 (20 mg/kg, ip) reduced IPC-triggered ROS levels and restored IPC-elicited cardioprotection. Using antagomiRs, we showed that miR-451 was largely responsible for IPC-mediated cardioprotection.
Loss of the miR-144/451 cluster limits IPC cardioprotection by up-regulating Rac-1-mediated oxidative stress signalling.
虽然大量数据揭示了肥厚和缺血/再灌注（I/R）心脏中独特的 microRNA（miR）表达改变，但对于 miR 的调节以及对缺血预处理（IPC）的反应知之甚少。
我们通过冠状动脉闭塞对经过六轮 4 分钟缺血的小鼠心脏进行预处理，并在体内进行 4 分钟再灌注，从而分析了预处理心脏中的 miRs。与假手术组相比，miR-144/451 簇内的两个 miR 在 21 个失调的 miR 中升高最明显。为了研究这一发现的意义，我们在 miR-144/451 敲除（KO）小鼠模型中检查了 IPC 介导的心脏保护作用。与单独接受 I/R 治疗的小鼠相比，暴露于 IPC 后再进行 I/R（30 分钟/24 小时）的 WT 心脏的梗死面积较小。相比之下，IPC 未能保护 miR-144/451-KO 心脏免受 I/R 治疗引起的梗死。因此，miR-144/451 簇是 IPC 诱导的心脏保护所必需的。Rac-1 是 NADPH 氧化酶的关键组成部分，是 miR-144 和 miR-451 的三个真正靶标（Rac-1、14-3-3ζ和 CUGBP2）中大多数上调的靶标。因此，与 IPC-WT 心脏相比，KO 心脏中的活性氧（ROS）水平在 IPC 后显著增加。在 KO 心脏中预先用 Rac-1 抑制剂 NSC23766（20mg/kg，ip）预处理可降低 IPC 触发的 ROS 水平并恢复 IPC 诱导的心脏保护作用。使用反义寡核苷酸，我们表明 miR-451 主要负责 IPC 介导的心脏保护。
miR-144/451 簇的缺失通过上调 Rac-1 介导的氧化应激信号限制了 IPC 的心脏保护作用。
