MiR-24 Protects Cardiomyocytes Against Hypoxia/Reoxygenation-Induced Injury Through Regulating Mitogen-Activated Protein Kinase 14

Abstract

This study aimed to explore the function of miR-24 in hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury. We constructed a cardiomyocyte model of H/R using the primary cardiomyocytes isolated from Sprague-Dawley rats. To explore the role of miR-24, cells were transfected with a miR-24 mimic or miR-24 inhibitor. The RNA expression levels of miR-24 and Mapk14 were determined using qRT-PCR. The proliferation and apoptosis of cells were determined using a CCK8 assay and a flow cytometer. The TargetScan website was used to predict the targets of miR-24. A dual-luciferase reporter gene assay was conducted to verify whether Mapk14 is indeed a target of miR-24. A Western blot was applied for protein detection. H/R exposure decreased the expression of miR-24 in rat cardiomyocytes. Transfection of the miR-24 mimic into cardiomyocytes reduced H/R-induced injury as evidenced by an increase in proliferation and a decrease in the apoptotic rate. By contrast, transfection of the miR-24 inhibitor aggravated H/R-induced injury. The expression of Bcl-2 was increased while the levels of Bax and Active-caspase 3 were reduced in the H/R+ miR-24 mimic group compared to those in the H/R group. H/R+miR-24 inhibitor group showed the opposite results. Mapk14 was identified as a target of miR-24. The mRNA level of Mapk14 and its protein (p38 MAPK) level were negatively affected by miR-24. Furthermore, we discovered that depletion of Mapk14 reduced the promoting effect of the miR-24 inhibitor on cell apoptosis. Overall, our results illustrated that miR-24 could attenuate H/R-induced injury partly by regulating Mapk14.

Functional Role of microRNAs in Regulating Cardiomyocyte Death

“…Hypoxia-reoxygenation was shown to reduce miR-24 expression in rat cardiomyocytes, whereas miR-24 mimics increase Bcl-2 protein levels and decrease apoptosis [64]; equally important, Mitogen-Activated Protein Kinase 14 (MAPK14) is a target gene of miR-24 and its expression is negatively regulated by this miR [64]. Notably, miR-135a overexpression is known to decrease cell apoptosis, lactate dehydrogenase levels, Troponin I, and inflammation following isoproterenol treatment [65]; luciferase assay analyses validated Toll-like receptor 4 (TLR4) as the specific target gene of miR-135a [65].…”

Exploring Myocardial Ischemia‐Reperfusion Injury Mechanism of Cinnamon by Network Pharmacology, Molecular Docking, and Experiment Validation

“…MAPK14, also known as p38a, is involved in cell proliferation, apoptosis, and the inflammatory response. An increasing number of studies have highlighted the significance of MAPK14 in the treatment of myocardial inflammatory diseases [ 60 , 61 ]. Therefore, PTGS2, GSK3B, and MAPK14 may serve as target proteins related to MIRI.…”

Research progress of IGF‐1 and cerebral ischemia

“…Anti-apoptosis was induced by increasing the expression of anti-apoptotic protein Bcl-2 and decreasing the expression of pre-apoptotic protein Bax (Qin SQ, et al, 2020). In addition, IGF-1 can also block apoptosis signal transduction by blocking the activation of Caspsase-9 (Poulaki V, et al, 2002) and Caspase-8.…”

“…Anti-apoptosis (Qin SQ, et al, 2020) Block apoptosis signal transduction by blocking the activation of Caspsase-9…”