miR-146a inhibits mitochondrial dysfunction and myocardial infarction by targeting cyclophilin D

Area of Science:

• Cardiology
• Molecular Biology
• Mitochondrial Medicine

Background:

• Mitochondrial microRNAs (miRNAs) are increasingly linked to cardiovascular diseases.
• The specific role of mitochondrial miRNAs in ischemic heart disease (IHD) is not well understood.

Purpose of the Study:

• To investigate the role of miR-146a in the pathogenesis of ischemic heart disease.
• To elucidate the underlying mechanisms by which miR-146a affects cardiomyocyte apoptosis and mitochondrial function.

Main Methods:

• Mitochondrial and cardiomyocyte fractions were isolated to assess miR-146a levels.
• Cardiomyocyte-specific knockout and overexpression models of miR-146a were used in mice subjected to ischemic reperfusion (I/R) injury.
• Anoxia/reoxygenation models were employed to study cardiomyocyte apoptosis.
• Luciferase reporter assays were performed to identify miR-146a targets.
• Cyclophilin D (CyPD) protein and mRNA levels were analyzed.

Main Results:

• miR-146a levels decreased in cardiomyocytes after I/R injury.
• Loss of miR-146a aggravated I/R-induced myocardial infarction, apoptosis, and cardiac dysfunction.
• Overexpression of miR-146a protected cardiomyocytes against apoptosis by inhibiting the mitochondrial pathway, increasing Bcl-2/Bax ratio, and blocking mitochondrial permeability transition pore opening.
• miR-146a directly targets and downregulates Cyclophilin D protein expression.
• Restoration of CyPD or deletion of CyPD in cardiomyocytes abolished the protective effects of miR-146a.

Conclusions:

• Nuclear miR-146a translocates to mitochondria, where it regulates mitochondrial function and cardiomyocyte apoptosis.
• miR-146a plays a protective role in ischemic heart disease by inhibiting the mitochondria-dependent apoptotic pathway via downregulation of Cyclophilin D.
• miR-146a represents a novel therapeutic target for treating ischemic heart disease.