Elucidation of Circulatory miRNA Levels Regulating NFATC3/ANP/BNP Signaling Nexus for the Early Diagnosis of Myocardial Infarction

Abstract

Myocardial infarction (MI), also known as heart attack, is caused by reduced or complete cessation of blood flow to the part of myocardium. MicroRNAs (miRNAs) are key regulators in various cellular mechanisms and have the potential to be used as diagnostic markers in certain diseases such as MI, atherosclerosis, heart failure coronary artery disease, hypertrophy and fibrosis. The present research was conducted to study the early diagnostic potential of circulatory miRNAs which were dysregulated in MI patients and isoproterenol induced MI rat model. The expression of miRNA-1 and miRNA-15a was markedly upregulated in the blood of MI patients while the expression of miRNA-98 was significantly downregulated in MI patients’ blood and isoproterenol induced MI rats’ blood and tissue. By using bioinformatics tool, TargetScan, it was confirmed that NFATC3, BCL2 and ET-1 were the putative targets of miRNA-1, miRNA-15a and miRNA-98, respectively. The decreased levels of NFATC3 and BCL2 in circulation were confirmed by qRT-PCR. In blood, the increased level of ET-1 and its downstream targets ANP and BNP were confirmed by qRT-PCR. The increased protein expressions of NFATC3 and ET-1 in tissue and serum sample were evaluated by western blotting in isoproterenol induced MI rat model. The toxic potential of isoproterenol for MI induction in rat was confirmed by disrupted heart tissue histology, increased reactive oxygen species (ROS) and decreased antioxidative enzymes such as super oxide dismutase (SOD), catalase (CAT), peroxidase (POD), reduced glutathione (GSH) and ascorbate peroxidase (APX) in rat serum and tissue homogenates samples. In serum samples, the liver function tests and lipid profiling were also done to check the elevated levels of enzymes in isoproterenol induced MI rat model. Concludingly, this study provides future insights for miRNA research that will advance the development of diagnostic markers for the early detection of MI in patients