High glucose induces apoptosis in AC16 human cardiomyocytes via macrophage migration inhibitory factor and c-Jun N-terminal kinase

1. It is known that high glucose can induce cardiomyocyte apoptosis and that macrophage migration inhibitory factor (MIF) may be involved in the development of diabetes. However, the relationship between high glucose and MIF in diabetic cardiomyopathy remains unclear. 2. In the present study, AC16 human cardiomyocytes were cultured in the presence of 25 mmol/L glucose for 20, 30 and 60 min before being subjected to western blot analyses to determine MIF expression and c-Jun N-terminal kinase (JNK) activation. In addition, AC16 cells were pretreated with 2.5 μmol/L SP600125 (a JNK inhibitor), 40 μmol/L (s,r)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1; an MIF antagonist) or 0.1% dimethylsulphoxide (DMSO; vehicle) for 1 h prior to exposure to 25 mmol/L glucose and culture for 72 h, followed by annexin V-fluorescein isothiocyanate/propidium iodide staining and flow cytometry analysis. Caspase 3 activity and phosphorylation of JNK were also analysed by western blotting. 3. The high concentration of glucose increased expression of endogenous MIF and JNK phosphorylation in AC16 cardiomyocytes. Pretreatment of cells with SP600125 and ISO-1 reduced glucose-induced apoptosis and caspase 3 activity. Furthermore, JNK phosphorylation was attenuated by inhibition of endogenous MIF. 4. In conclusion, myocardial cell apoptosis induced by high glucose involves the overexpression of MIF and activation of the JNK signalling pathway. The identification of a high glucose-MIF-JNK pathway will help determine potential new targets in the treatment of diabetic cardiomyopathy.