Myocardial infarction cardiomyocytes-derived exosomal miR-328-3p promote apoptosis via Caspase signaling.

Exosomal miRNAs are used as novel non-invasive biomarkers for detection strategies of human disease. Here, we aimed to investigate the potential clinical value of exosomal miRNAs for myocardial infarction (MI) diagnosis and treatment. Differentially expressed miRNAs were obtained from normal cardiomyocytes, MI cardiomyocytes and adjacent normal cardiomyocytes using miRNA microarray analysis. Exosomes were isolated by centrifugation and identified by transmission electron microscopy (TEM) and western blot. The expression of miR-328-3p in exosomes was then verified by qRT-PCR. Cell apoptosis was measured using flow cytometry and TUNEL analysis. The MI severity was confirmed by masson's trichrome staining and echocardiography. MiR-328-3p was significantly increased in the MI cardiomyocytes and adjacent normal cardiomyocytes. We further confirmed miR-328-3p increasing in the exosomes from MI cardiomyocytes, which can be taken into normal cardiomyocytes. Furthermore, exogenous exosomal miR-328-3p increased apoptosis of cardiomyocytes and promoted MI. Genes regulated by miR-328-3p are mainly enriched in Caspase signaling, which is an important apoptosis regulating signaling pathway. Additionally, Caspase-3 inhibitor, Z-DEVD-FMK, reversed apoptosis and MI promoting function of miR-328-3p. Exosomal miR-328-3p is a potential novel diagnostic biomarker and therapeutic target for MI, and Z-DEVD-FMK could reverse the apoptosis progression induced by miR-328-3p. AJTR