MiR-20a-5p overexpression prevented diabetic cardiomyopathy via inhibition of cardiomyocyte apoptosis, hypertrophy, fibrosis and JNK/NF-κB signalling pathway.

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Diabetic cardiomyopathy (DCM) is a common cardiovascular disease. A declined miR-20a-5p was observed in hearts of diabetic mice, while its effect on DCM remains unknown. Herein, we established streptozotocin-induced DCM rat model and high glucose-stimulated H9C2 model of DCM. Then they were treated with adenovirus expressing miR-20a-5p to explore the function of miR-20a-5p. Insulin tolerance test and intraperitoneal glucose tolerance test assay revealed that miR-20a-5p reduced blood glucose level. Besides, miR-20a-5p improved cardiac dysfunction reflected by reduced heart weight/body weight and left ventricular diastolic pressure, and increased left ventricular systolic pressure and ±LV dp/dt max. MiR-20a-5p prevented cardiomyocyte apoptosis, along with the upregulated c-caspase-3, bax and downregulated bcl-2. Moreover, miR-20a-5p alleviated cardiac hypertrophy as the parameters of atrial natriuretic peptide, B-type natriuretic peptide and MyHC-β decreased. Also, miR-20a-5p attenuated the cardiac fibrosis demonstrated by decreased transforming growth factor-β1, collagen I levels and the inflammatory response manifested by reduced interleukin-6, tumour necrosis factor-α and IL-1β production. Furthermore, miR-20a-5p prevented Jun NH2-terminal kinase (JNK) phosphorylation and nuclear factor-κB (NF-κB) p65nuclear translocation. Similarly, the effects of miR-20a-5p on DCM were confirmed in our in vitro experiments. Additionally, ROCK2 is a possible target gene of miR-20a-5p. ROCK2 overexpression reversed the protective effect of miR-20a-5p on DCM. Overall, miR-20a-5p may effectively ameliorate DCM through improving cardiac metabolism, and subsequently inhibiting inflammation, apoptosis, hypertrophy, fibrosis and JNK/NF-κB pathway via modulating ROCK2.