title: Upregulation of microRNA-22 contributes to myocardial ischemia-reperfusion injury by interfering with the mitochondrial function.
abstract: Mitochondrial oxidative damage is critically involved in cardiac ischemia reperfusion (I/R) injury. MicroRNA-22 (miR-22) has been predicted to potentially target sirtuin-1 (Sirt1) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α), both of which are known to provide protection against mitochondrial oxidative injury. The present study aims to investigate whether miR-22 is involved in the regulation of cardiac I/R injury by regulation of mitochondrial function. We found that miR-22 level was significantly increased in rat hearts subjected to I/R injury, as compared with the sham group. Intra-myocardial injection of 20 ug miR-22 inhibitor reduced I/R injury as evidenced by significant decreases in cardiac infarct size, serum lactate dehydrogenase (LDH) and creatine kinase (CK) levels and the number of apoptotic cardiomyocytes. H9c2 cardiomyocytes exposed to hypoxia/reoxygenation (H/R) insult exhibited an increase in miR-22 expression, which was blocked by reactive oxygen species (ROS) scavenger and p53 inhibitor. In addition, miR-22 inhibitor attenuated, whereas miR-22 mimic aggravated H/R-induced injury in H9c2 cardiomyocytes. MiR-22 inhibitor per se had no significant effect on cardiac mitochondrial function. Mitochondria from rat receiving miR-22 inhibitor 48h before ischemia were found to have a significantly less mitochondrial superoxide production and greater mitochondrial membrane potential and ATP production as compared with rat receiving miR control. In H9c2 cardiomyocyte, it was found that miR-22 mimic aggravated, whilst miR-22 inhibitor significantly attenuated H/R-induced mitochondrial damage. By using real time PCR, western blot and dual-luciferase reporter gene analyses, we identified Sirt1 and PGC1α as miR-22 targets in cardiomyocytes. It was found that silencing of Sirt1 abolished the protective effect of miR-22 inhibitor against H/R-induced mitochondrial dysfunction and cell injury in cardiomyocytes. Taken together, our findings reveal a novel molecular mechanism for cardiac mitochondrial dysfunction during myocardial I/R injury at the miRNA level and demonstrate the therapeutic potential of miR-22 inhibition for acute myocardial I/R injury by maintaining cardiac mitochondrial function.
authors.affiliation: Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China.
authors.forename: Jian-Kui
authors.initials: JK
authors.lastname: Du
authors.affiliation: Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China.
authors.forename: Bin-Hai
authors.initials: BH
authors.lastname: Cong
authors.affiliation: Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Yu
authors.affiliation: Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China.
authors.forename: He
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China.
authors.forename: Long
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China.
authors.forename: Chang-Nan
authors.initials: CN
authors.lastname: Wang
authors.affiliation: Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China.
authors.forename: Xiao-Lu
authors.initials: XL
authors.lastname: Tang
authors.affiliation: School of Kinesiology, The Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai 200438, China.
authors.forename: Jian-Qiang
authors.initials: JQ
authors.lastname: Lu
authors.affiliation: Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China. Electronic address: xiaoyanzhu@smmu.edu.cn.
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Zhu
authors.affiliation: Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China. Electronic address: nixin@smmu.edu.cn.
authors.forename: Xin
authors.initials: X
authors.lastname: Ni
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D003402:Creatine Kinase / Q000097:blood; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D053078:Membrane Potential, Mitochondrial / Q000235:genetics; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000235:genetics*; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000097:blood / Q000235:genetics* / Q000473:pathology; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000473:pathology; D018384:Oxidative Stress / Q000235:genetics; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha / Q000235:genetics*; D051381:Rats; D056564:Sirtuin 1 / Q000235:genetics*; D013481:Superoxides / Q000378:metabolism
chemical_list: C580892:MIRN22 microRNA, rat; D035683:MicroRNAs; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C501429:Ppargc1a protein, rat; D013481:Superoxides; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase; C488368:Sirt1 protein, rat; D056564:Sirtuin 1
keywords: Cardiomyocyte; Ischemia-reperfusion; MicroRNA-22; Mitochondria; PGC1α; Sirt1; p53