miR-450a-2-3p targets ERK(1/2) to ameliorate ISO-induced cardiac fibrosis in mice

Abstract Objective: Cardiac fibrosis is a significant contributor to atrial fibrillation (AF). Our aim is to identify biomarkers for AF using bioinformatic methods and explore the regulatory mechanism of miR-450a-2-3p in cardiac fibrosis in mice. Methods: Two datasets, GSE115574 and GSE79768, were obtained from the Gene Expression Omnibus (GEO) database and subsequently merged for further analysis. Differential gene expression analysis was performed to identify genes that were differentially expressed (DEGs) and genes that were differentially expressed in relation to miR-450a-2-3p (MRDEGs). To investigate the underlying mechanism of cardiac fibrosis, a mouse model was established by treating mice with isoproterenol (ISO) and miR-450a-2-3p agomir. Results: A total of 127 DEGs and 31 MRDEGs were identified and subjected to functional enrichment analysis using Gene Ontology (GO) and pathway analysis using Kyoto Encyclopedia of Genes and Genomes (KEGG) to determine the functions and pathways involved in atrial fibrillation (AF). In animal experiments, histological staining using H&E and Masson's trichrome, as well as quantification of collagen volume fraction (CVF), were performed. The increased expression of α-smooth muscle actin (α-SMA), collagen type I (col1), collagen type III (col3), and extracellular signal-regulated kinase (ERK) 1/2 at both the mRNA and protein levels indicated the presence of significant myocardial fibrosis in mice induced with isoproterenol (ISO). However, after the overexpression of miR-450a-2-3p agomir through caudal vein injection, there was a notable improvement in the cardiac morphology of the treated group. The expression levels of α-SMA, col1, col3, and ERK1/2 also significantly decreased, as confirmed by Western blot and RT-qPCR analyses. Conclusion: Our study elucidates the mechanistic connection between ISO-induced myocardial fibrosis and the miR-450a-2-3p/ERK (1/2) signaling pathway, highlighting their role in the development of cardiac fibrosis. Modulating miR-450a-2-3p expression and inhibiting ERK (1/2) activation represent promising approaches for therapeutic intervention in atrial fibrillation.