Exosomes from GATA-4-overexpressing bone marrow mesenchymal stem cells suppress the apoptosis of cardiomyocytes by inhibiting the expression of Ap2m1 via miR-330-3p / 医学研究生学报

ABSTRACT

Objective Exosomes secreted from mouse bone marrow mesenchymal stem cells (BMSC) overexpressing the cardiomyocyte transcription factor GATA-4 (BMSCGATA-4-exosome) may play a key role in repairing myocardial injury. This study aimed to investigate the molecular regulatory network of BMSCGATA-4-exosome for inhibiting the apoptosis of cardiomyocytes. Methods Exosomes extracted from GATA-4-overexpressing BMSCs of the mouse cultured with miR-330-3p-mimic were cultured with myocardial cells under hypoxic and serum-free conditions for 24 hours (the experimental group), the overexpressed GATA-4, empty vector and BMSCs were taken as the confounding factor control (CFC), the myocardial cells cultured under hypoxic and serum-free conditions for 24 hours were used as the positive control, and those cultured under the normal condition for 24 hours as the negative control. The apoptosis rates of myocardial cells in different groups were measured by flow cytometry, the expression levels of miR-330-3p in the myocardial cells determined by RT-PCR, and those of the corresponding miR-330-3p target gene Ap2m1 and transcriptional protein Cnot4 detected by Western blot. Results CD29 was expressed in 99.71% of the mouse BMSCs, CD44 in 97.28%, SCA-1 in 99.40%, and CD11b overexpressed in only 0.1%. The early apoptosis rate of myocardial cells was significantly higher in the experimental than in the negative control group ([7.90 ± 0.34]% vs [2.30 ± 0.09]%, P < 0.05) but lower than in the positive control ([51.48 ± 0.40]%), BMSC ([18.32 ± 3.03]%), empty vector ([16.99 ± 2.93]%) and overexpressed GATA-4 groups ([10.22 ± 0.35]%) (P < 0.05). The expression of miR-330-3p in the myocardial cells was markedly higher in the experimental ([396.10 ± 1.02]%) than in the negative control ([1.37 ± 0.33]%), positive control ([0.26±0.32]%), BMSC ([1.40 ± 0.42]%), empty vector ([1.41 ± 0.27]%) and overexpressed GATA-4 groups ([3.80 ± 0.62]%) (P < 0.05). The expressions of Ap2m1 and Cont4 in the myocardial cells were remarkably decreased in the experimental group compared with those in the other five groups (P < 0.05). Conclusion Overexpressed BMSCGATA-4-exosomes suppress the apoptosis of myocardial cells by inhibiting the expression of the Ap2m1 protein via miR-330-3p.