ABSTRACT
In this study, the regulation of miR-15b-5p on myocardial ischemia reperfusion (I/R) injury-induced arrhythmia and myocardial apoptosis was investigated in mice. We observed the change in miR-15b-5p expression after mice suffered from myocardial I/R injury and the change in myocardial injury, infarct size, apoptosis, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), superoxide dismutase (SOD) and malondialdehyde (MDA) after down-regulation of miR-15b-5p expression. The negative regulation of miR-15b-5p to KCNJ2 as well as whether cardioprotective effect formed by miR-15b-5p down-regulation relied on the increase of KNCJ2 expression were measured by dual-luciferase reporter assay system. miR-15b-5p expression increased and KCNJ2 mRNA and protein expressions decreased after myocardial ischemia reperfusion (all P < 0.05). miR-15b-5p negatively regulated KCNJ2 in a targeted way. Down-regulating miR-15b-5p expression or increasing KCNJ2 expression significantly decreased the incidence of arrhythmia, infarct size and apoptosis after myocardial I/R and lowered MDA content in the myocardial tissue as well as IL-6 and TNF-α content in the blood (all P < 0.05). KCNJ2 gene knockout reversed the above cardioprotective effect formed by miR-15b-5p down-regulation (P < 0.05). Down-regulating miR-15b-5p expression or up-regulating KCNJ2 expression improves arrhythmia after mice suffered from myocardial I/R injury and inhibits myocardial apoptosis.
Subject(s)
Apoptosis , Arrhythmias, Cardiac/genetics , Down-Regulation , MicroRNAs/genetics , Myocardial Reperfusion Injury/genetics , Animals , Arrhythmias, Cardiac/pathology , Male , Mice , Mice, Inbred C57BL , Myocardial Reperfusion Injury/pathology , Myocardium/pathologyABSTRACT
BACKGROUND: Everolimus, a derivative of sirolimus, is a potent immunosuppressant that has important anti-proliferative properties. In the present study, we demonstrated the inhibiting neointimal hyperplasia in injured carotid arteries in rats by using two different doses of everolimus administrated via the oral route for a long time. METHODS: A rat model of carotid artery injury was established by balloon inflation. Eighty rats were randomly divided into the sham-operated group (n = 20), injury group (n = 20), low dosage of everolimus group (n = 20), and high dosage of everolimus group (n = 20). The low dose of everolimus (1.5 mg/kg) was given one day before injuring the carotid artery by balloon, followed by 0.75 mg/kg per day for 28 days via intragastric gavage. High dose everolimus (2.5 mg/kg) was given one day before injuring the carotid artery by balloon, followed by 1 mg/kg per day for 28 days. Expression of eukaryotic translation initiation factor 4E (eIF-4E) and phosphorylation of ribosomal protein S6 kinase 1 (P70S6K) were determined by reverse transcription-polymerase chain reaction and Western blotting analysis. RESULTS: In the injured carotid artery, neointimal hyperplasia was normally observed four weeks after injury. Everolimus inhibited neointimal hyperplasia after balloon injury in a dose dependent manner. At the same time, the study demonstrated that everolimus reduced the expression of P-P70S6K, eIF-4E, transforming growth factor (TGF)-ß1 and of proliferating cell nuclear antigen (PCNA). CONCLUSIONS: Everolimus significantly inhibited neointimal hyperplasia of the injured carotid artery. The effect depended on dosage and was associated with the reduction of phosphorylation of P70S6K and the eIF-4E expression level.
