MicroRNA-1278 ameliorates the inflammation of cardiomyocytes during myocardial ischemia by targeting both IL-22 and CXCL14.

Aims: This study aimed to elucidate the role of microRNAs (miRNAs) during myocardial infarction (MI) development in vivo and in vitro.

Main Methods: Differentially expressed miRNAs between heart tissue from the MI mouse model and the control mouse were identified via microarray. Quantitative PCR (qPCR) and western blotting (WB) were performed to examine the expression levels of miRNAs and proteins, respectively. EdU-staining and colony formation assay were performed to assess cell viability and growth. Annexin V- and PI-staining-based flow cytometry was used to assess cell apoptosis. An MI mouse model was also established to study the function of miR-1278 in vivo.

Key Findings: The levels of miR-1278 were reduced in the infarct regions of heart tissues of the MI mouse model and in H 2 O 2 -treated newborn murine ventricular cardiomyocytes (NMVCs) compared to those in the heart tissues of healthy mice and non-treated NMVCs. H 2 O 2 treatment suppressed the proliferation of NMVCs, while miR-1278 upregulation improved it. Moreover, we found that miR-1278 inhibited the upregulation of IL-22 and CXCL14 expression in H 2 O 2 -treated NMVCs by directly binding with the 3'-UTRs of both IL-22 and CXCL14. Furthermore, restoration of IL-22 and CXCL14 in H 2 O 2 -treated NMVCs promoted miR-1278-induced inflammation and apoptosis. Administration of agomiR-1278 to the MI mouse model significantly improved cardiac activity.

Significance: Collectively, our findings illustrate that the expression of miR-1278 is low in H 2 O 2 -treated NMVCs and post-MI cardiac tissues, and the overexpression of miR-1278 in these protects against cell death by modulating IL-22 and CXCL14 expression.

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