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Background/Aims: Micro RNAs (miRNAs) play a very important role in myocardial ischemia/ reperfusion injury (MIRI), including in inflammation, apoptosis, and angiogenesis. Previous studies have demonstrated up-regulation of miR-327 in renal ischemia/reperfusion injury and MIRI. Via TargetScan, we found RP105 is a possible target gene of miR-327; our previous studies have also confirmed that RP105 acted as a cardioprotective protein in MIRI by reducing inflammation. However, the regulatory effect of miR-327 on RP105 has not previously been proposed. In our study, we aimed to identify the regulatory effect of miR-327 on RP105 protein in MIRI rats. Methods: Sixty male Sprague-Dawley rats were randomly divided into five groups, which were pre-treated with saline (sham and ischemia/reperfusion group), adenovirus-expressing miR-327-RNAi (Ad-miR-327-i group), control (Ad-NC group), or primiR-327 (Ad-miR-327 group) treatments. Three d'ys later, the rat MIRI model was established by ischemia for 30 min, followed by reperfusion for 3 h. Myocardium and plasma were harvested and assessed. Results: miR-327 was increased by nearly 3-fold both in myocardium and plasma, which down-regulated RP105 in a 3'-untranslated region-dependent manner, and down-regulation of miR-327 via adenovirus transfection indirectly suppressed the TLR4/ TLR2-MyD88-NF-κB signaling axis activation via up-regulation of RP105, which subsequently resulted in reduced myocardial infarct size, attenuated cardiomyocyte destruction, and alleviated inflammation. In contrast, up-regulation of miR-327 induced the opposite effect. [ABSTRACT FROM AUTHOR]

Background/Aims: Oxidative stress is strongly implicated in the pathogenesis of myocardial damage caused by ischemia reperfusion (I/R). Previous studies have confirmed that cardiac CD47 drives left ventricular heart failure. However, the role for CD47 in myocardial I/R injury (MIRI) has not previously been proposed. This study was designed to investigate whether down-regulation of CD47 using RNA interference (RNAi) technology can relieve inhibition of nitric oxide signaling and attenuate myocardial damage in a rat model of I/R. Methods: Male Sprague-Dawley rats (n = 40) were randomly allocated to four groups and pre-treated either with saline (Sham and I/R groups), or adenovirus expressing either control (Ad-EGFP-N) or CD47-targeting (Ad-EGFP-CD47) RNAi. After four days, the rat MIRI model was established by occluding the left anterior descending coronary artery for 30 min, followed by reperfusion for 3 h. Heart tissue was harvested and assessed by immunohistochemistry, western blot, and quantitative RT-PCR. Outcome measures included infarct size, myocardial enzyme (creatine kinase, creatine kinase-MB, and lactate dehydrogenase) levels in serum, markers of oxidative stress, and morphological changes to the myocardium. Results: Delivery of Ad-EGFP-CD47 RNAi into the myocardium remarkably decreased CD47 expression levels. Down-regulation of CD47 was significantly associated with reduced infarct size and serum levels of myocardial enzymes, increased activity of endothelial nitric oxide synthase, increased levels of nitric oxide, and decreased levels of oxidative stress. Conclusion: These data indicate that down-regulation of CD47 exerts a protective effect against MIRI, which may be attributable to attenuation of oxidative stress via activation of the eNOS/NO signaling pathway. [ABSTRACT FROM AUTHOR]