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MicroRNA-323-3p inhibits oxidative stress and apoptosis after myocardial infarction by targeting TGF-β2/JNK pathway
1Department of Intensive Care Unit, Henan Provincial People's Hospital, Zhengzhou, China. lijianguo1817@163.com.
Objective:
Myocardial infarction (MI), which causes irreversible damage and loss of cardiomyocytes, is the most important cause of death in the world. MicroRNA is an important regulator of physiological and pathological activities of cardiovascular system. The aim of this research was to study the effect of microRNA-323-3p (miR-323-3p) on MI and its underlying mechanisms of action.
Materials And Methods:
A rat model of MI was established to measure the expression of miR-323-3p, Bax, Bcl-2, SOD1, and SOD2 in ischemic myocardial tissue, and the cardiac function of rats were tested at seventh day after MI. H9c2 cells were divided into control group, miRNA negative control (NC) transfection group, miR-323-3p mimic (miR-323-3p min) transfection group, and then, treated with H2O2. Oxidative stress and apoptosis of H9c2 cells were observed by Western blot, Real Time-Polymerase Chain Reaction (RT-PCR), flow cytometry, SOD activity assay, TUNEL staining, DHR dye assay, etc. RESULTS: The level of miR-323-3p was decreased in ischemic myocardium, as well as H2O2-treated H9c2 cells. MiR-323-3p overexpression greatly decreased the level of Bax and increased the levels of SOD1, SOD2, and Bcl-2. After treated with miR-323-3p mimic, TUNEL positive cells were greatly reduced, and apoptosis rate of H9c2 cells was greatly decreased. Moreover, SOD levels significantly increased, while ROS production decreased after treatment of miR-323-3p. After intravenous injection of miR-323-3p agomir in rats with MI, the cardiac function of the rats was significantly improved. Western blot and Luciferase reporter gene experiments illustrated that miR-323-3p acts by targeting TGF-β2.
Conclusions:
MiR-323-3p was downregulated in ischemic myocardium and H2O2-treated H9c2 cells, and miR-323-3p overexpression reduced oxidative stress and apoptosis of cardiomyocytes. The protective function was achieved via regulation of TGF-β2/JNK pathway.
Insights
MicroRNA-323-3p (miR-323-3p) protects against myocardial infarction (MI) by reducing cardiomyocyte apoptosis and oxidative stress. Restoring miR-323-3p levels improved cardiac function in a rat MI model.
Area of Science:
- Cardiovascular Biology
- Molecular Medicine
- Biochemistry
Background:
- Myocardial infarction (MI) is a leading cause of mortality worldwide, characterized by irreversible cardiomyocyte damage.
- MicroRNAs (miRNAs) are critical regulators of cardiovascular physiology and pathology.
- Understanding the role of specific miRNAs, like miR-323-3p, in MI is crucial for developing novel therapeutic strategies.
Purpose of the Study:
- To investigate the therapeutic effect of microRNA-323-3p (miR-323-3p) on myocardial infarction (MI).
- To elucidate the underlying molecular mechanisms by which miR-323-3p exerts its protective effects in MI.
- To assess the impact of miR-323-3p modulation on cardiomyocyte apoptosis, oxidative stress, and cardiac function.
Main Methods:
- Established a rat model of MI and analyzed miR-323-3p expression in ischemic tissue.
- Utilized H9c2 cells treated with H2O2 to simulate oxidative stress and apoptosis.
- Assessed cellular and tissue responses using Western blot, RT-PCR, flow cytometry, TUNEL staining, and SOD activity assays.
- Investigated the direct target of miR-323-3p using Western blot and luciferase reporter gene assays.
Main Results:
- miR-323-3p expression was significantly decreased in both ischemic myocardium and H2O2-treated H9c2 cells.
- Overexpression of miR-323-3p reduced Bax levels while increasing Bcl-2, SOD1, and SOD2 expression.
- miR-323-3p treatment decreased apoptosis, reduced reactive oxygen species (ROS) production, and enhanced SOD levels.
- Intravenous administration of miR-323-3p agomir improved cardiac function in rats post-MI.
- miR-323-3p was identified to target TGF-β2.
Conclusions:
- miR-323-3p exhibits a protective role against MI by mitigating oxidative stress and apoptosis in cardiomyocytes.
- Restoration of miR-323-3p levels improved cardiac function in a preclinical MI model.
- The cardioprotective effects of miR-323-3p are mediated through the regulation of the TGF-β2/JNK pathway.
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