Loss of the miR-144/451 cluster impairs ischaemic preconditioning-mediated cardioprotection by targeting Rac-1

• Published in: Cardiovascular research 2012-05, Vol.94 (2), p.379-390
• Main Authors: Wang, Xiaohong, Zhu, Hongyan, Zhang, Xiaowei, Liu, Yong, Chen, Jing, Medvedovic, Mario, Li, Hongliang, Weiss, Mitchell J, Ren, Xiaoping, Fan, Guo-Chang
• Format: Article
• Language: English
• Subjects: Animals; Blotting, Western; Ischemic Preconditioning, Myocardial - methods; Mice; Mice, Knockout; MicroRNAs - metabolism; Myocardial Infarction - metabolism; Myocardial Infarction - prevention & control; Myocardial Reperfusion Injury - metabolism; Myocardial Reperfusion Injury - prevention & control; Myocardium - metabolism; Original : Spotlight on Reducing Myocardial Ischaemia/Reperfusion Injury; Oxidative Stress - physiology; Reactive Oxygen Species - metabolism
• ISSN: 0008-6363; 1755-3245
• DOI: 10.1093/cvr/cvs096

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.