Yan Wang1, Yan Wang1, Qi Yang, Jiang Tao Yan, Chunxia Zhao, Katherine Cianflone, Dao Wen Wang. 1. Cardiovascular Division of Internal Medicine, Department and The Institute of Hypertension, Tongji Hospital, Tongji Medical College of Huazhong University of Science & Technology, Wuhan 430030, People's Republic of China.
Abstract
OBJECTIVE: Peroxisome proliferator-activated receptors alpha (PPARalpha) is a target gene for atherosclerosis and cardiovascular diseases. However, effects of PPARalpha on endothelial nitric oxide synthase (eNOS) remain unknown. We investigated the eNOS regulation by bezafibrate, a ligand of PPARalpha, and involved signaling pathways. METHODS AND RESULTS: Firstly, in cultured bovine aorta endothelial cells (BAEC), bezafibrate significantly upregulated eNOS at protein, mRNA levels and NO production, respectively, in a concentration-dependent fashion (50-200muM). Next, the effects of bezafibrate on signal pathways and eNOS mRNA stability in BAEC were investigated. Results showed that bezafibrate induced phosphorylation of MAPK. Inhibitors of PPARalpha, PI3 kinase and MAPK, respectively, markedly attenuate bezafibrate-induced upregulation of eNOS. Bezafibrate incubation increased eNOS mRNA half-life, activated eNOS promoter, enhanced phosphorylation of eNOS ser-1179 site, and decreased phosphorylation of eNOS thr-497 site via activating ERK and Akt. CONCLUSIONS: Bezafibrate can upregulate eNOS expression, enhance phosphorylation of eNOS ser-1179, increase NO production and transcription level and stability of eNOS mRNA through pathway dependent of PPARalpha and nongenomic effects mediated by MAPK and PI3K pathways. Hence, PPARalpha ligands exert direct benefits on vessel endothelial functions through an increase in eNOS expression level and phosphorylation of eNOS ser-1179. This mechanism provides additional anti-atherosclerotic and anti-hypertension benefits of bezafibrate in addition of lipid-lowering effects.
OBJECTIVE: Peroxisome proliferator-activated receptors alpha (PPARalpha) is a target gene for atherosclerosis and cardiovascular diseases. However, effects of PPARalpha on endothelial nitric oxide synthase (eNOS) remain unknown. We investigated the eNOS regulation by bezafibrate, a ligand of PPARalpha, and involved signaling pathways. METHODS AND RESULTS: Firstly, in cultured bovine aorta endothelial cells (BAEC), bezafibrate significantly upregulated eNOS at protein, mRNA levels and NO production, respectively, in a concentration-dependent fashion (50-200muM). Next, the effects of bezafibrate on signal pathways and eNOS mRNA stability in BAEC were investigated. Results showed that bezafibrate induced phosphorylation of MAPK. Inhibitors of PPARalpha, PI3 kinase and MAPK, respectively, markedly attenuate bezafibrate-induced upregulation of eNOS. Bezafibrate incubation increased eNOS mRNA half-life, activated eNOS promoter, enhanced phosphorylation of eNOSser-1179 site, and decreased phosphorylation of eNOSthr-497 site via activating ERK and Akt. CONCLUSIONS:Bezafibrate can upregulate eNOS expression, enhance phosphorylation of eNOSser-1179, increase NO production and transcription level and stability of eNOS mRNA through pathway dependent of PPARalpha and nongenomic effects mediated by MAPK and PI3K pathways. Hence, PPARalpha ligands exert direct benefits on vessel endothelial functions through an increase in eNOS expression level and phosphorylation of eNOSser-1179. This mechanism provides additional anti-atherosclerotic and anti-hypertension benefits of bezafibrate in addition of lipid-lowering effects.