Background： Tumor necrosis factor-α （TNF-α） plays an important role in progressive contractile dysfunction in several cardiac diseases. The cytotoxic effects of TNF-α are suggested to be partly mediated by reactive oxygen species （ROS）- and mitochondria-dependent apoptosis. Glucagon-like peptide- 1 （GLP-1） or its analogue exhibits protective effects on the cardiovascular system. The objective of the study was to assess the effects ofexenatide, a GLP- 1 analogue, on oxidative stress, and apoptosis in TNF-α-treated cardiomyocytes in vitro. Methods： Isolated neonatal rat cardiomyocytes were divided into three groups： Control group, with cells cultured in normal conditions without intervention; TNF-α group, with cells incubated with TNF-α （40 ng/ml） for 6, 12, or 24 h without pretreatment with exenatide; and exenatide group, with cells pretreated with exenatide （100 nmol/L） 30 mins before TNF-α （40 ng/ml） stimulation. We evaluated apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling （TUNEL） assay and flow cytometry, measured ROS production and mitochondrial membrane potential （MMP） by specific the fluorescent probes, and assessed the levels of proteins by Western blotting for all the groups. Results： Exenatide pretreatment significantly reduced cardiomyocyte apoptosis as measured by flow cytometry and TUNEL assay at 12 h and 24 h. Also, exenatide inhibited excessive ROS production and maintained MMP. Furthermore, declined cytochrome-c release and cleaved caspase-3 expression and increased bcl-2 expression with concomitantly decreased Bax activation were observed in exenatide-pretreated cultures. Conclusion： These results suggested that exenatide exerts a protective effect on cardiomyocytes, preventing TNF-α-induced apoptosis; the anti-apoptotic effects may be associated with protection ofmitochondrial function.
Yuan-Yuan Cao Zhang-Wei Chen Yan-Hua Gao Xing-Xu Wang Jian-Ying Ma Shu-Fu Chang Ju-Ying Qian Jun-Bo Ge
microRNA-210(miR-210)has generally been reported to be associated with cell survival under hypoxia.However,there are few data regarding the role of miR-210 in the survival of mesenchymal stem cells(MSCs)under oxidative stress conditions.Thus,we sought to investigate whether miR-210 over-expression could protect MSCs against oxidative stress injury and what the primary mechanisms involved are.The results showed that over-expression of miR-210 significantly reduced the apoptosis of MSCs under oxidative stress,accompanied by obvious increases in cell viability and superoxide dismutase activity and remarkable decreases in malonaldehyde content and reactive oxygen species production,resulting in a noticeable reduction of apoptotic indices when compared with the control.Moreover,the above beneficial effects of miR-210 could be significantly reduced by c-Met pathway repression.Collectively,these results showed that miR-210 over-expression improved MSC survival under oxidative stress through antioxidation and c-Met pathway activation,indicating the potential development of a novel approach to enhance the efficacy of MSC-based therapy for injured myocardium.
