Linxi Wang1, Li Tang2,3, Yanping Wang1, Lijing Wang1, Xiaoying Liu1, Xiaohong Liu1, Zhou Chen4, Libin Liu1,5. 1. a Department of Endocrinology , Fujian Institute of Endocrinology, Union Hospital of Fujian Medical University , Fuzhou , Fujian , China. 2. b Department of Nephrology , The Xianyang Central Hospital , Shanxi , China. 3. c Xi'an Jiaotong University Health Science Center , Shanxi , China. 4. d Department of Pharmacy , Fujian Medical University , Fuzhou , Fujian , People's Republic of China. 5. e Elderly Health Institute , Fujian Medical University , Fuzhou , Fujian , China.
Abstract
AIMS: Although the insulinotropic role of glucagon-like peptide-1 (GLP-1) in type 2 diabetes mellitus has been substantiated, its role in cardioprotection remains largely unknown. In this study, we explored the effect and mechanism of exendin-4 on tert-butyl hydroperoxide (t-BHP)-induced apoptosis in human umbilical vein endothelial cells (HUVECs). METHODS: HUVECs were treated with 100 µmol/L t-BHP for 4 h, following pretreatment with 2.5-25 nmol/L exendin-4. Cell viability was determined using an dimethyl thiazolyl diphenyl tetrazolium salt (MTT) assay. The percentage of apoptotic cells was determined by fluorescence microscopy after Hoechst/PI staining. Expression of cysteine-aspartic acid protease-3(caspase-3), beta-cell lymphoma 2(Bcl-2), protein kinase B(AKT), and phosphorylated AKT was detected by western blotting. RESULTS: Exendin-4 reduced the percentage of cells undergoing apoptosis when HUVECs were exposed to t-BHP. Exendin-4 downregulated caspase-3 activity and increased Bcl-2 protein levels in t-BHP-treated HUVECs. These exendin-4-mediated effects were blocked in the presence of an inhibitor of phosphoinositide-3 kinase (PI3K). Exendin-4 reversed t-BHP-mediated inhibition of Akt phosphorylation, which was abrogated by the PI3K inhibitor, wortmannin. CONCLUSION: Our findings suggest that exendin-4 reduces t-BHP-induced apoptosis of HUVECs. Additionally, PI3K/Akt-Bcl-2-caspase-3 signaling is involved in the exendin-4-mediated modulation of HUVECs.
AIMS: Although the insulinotropic role of glucagon-like peptide-1 (GLP-1) in type 2 diabetes mellitus has been substantiated, its role in cardioprotection remains largely unknown. In this study, we explored the effect and mechanism of exendin-4 on tert-butyl hydroperoxide (t-BHP)-induced apoptosis in human umbilical vein endothelial cells (HUVECs). METHODS: HUVECs were treated with 100 µmol/L t-BHP for 4 h, following pretreatment with 2.5-25 nmol/L exendin-4. Cell viability was determined using an dimethyl thiazolyl diphenyl tetrazolium salt (MTT) assay. The percentage of apoptotic cells was determined by fluorescence microscopy after Hoechst/PI staining. Expression of cysteine-aspartic acid protease-3(caspase-3), beta-cell lymphoma 2(Bcl-2), protein kinase B(AKT), and phosphorylated AKT was detected by western blotting. RESULTS: Exendin-4 reduced the percentage of cells undergoing apoptosis when HUVECs were exposed to t-BHP. Exendin-4 downregulated caspase-3 activity and increased Bcl-2 protein levels in t-BHP-treated HUVECs. These exendin-4-mediated effects were blocked in the presence of an inhibitor of phosphoinositide-3 kinase (PI3K). Exendin-4 reversed t-BHP-mediated inhibition of Akt phosphorylation, which was abrogated by the PI3K inhibitor, wortmannin. CONCLUSION: Our findings suggest that exendin-4 reduces t-BHP-induced apoptosis of HUVECs. Additionally, PI3K/Akt-Bcl-2-caspase-3 signaling is involved in the exendin-4-mediated modulation of HUVECs.
Authors: Yu Zhao; Yunfei Li; Ling Tong; Xinying Liang; Han Zhang; Lan Li; Guanwei Fan; Yi Wang Journal: Front Physiol Date: 2018-02-06 Impact factor: 4.566