Peroxisome Proliferator-Activated Receptor alpha Reduces Endothelin-1-Caused Cardiomyocyte Hypertrophy by Inhibiting Nuclear Factor-kappa B and Adiponectin

Peroxisome proliferator-activated receptor alpha (PPAR alpha) plays a role in the pathogenesis of cardiac hypertrophy, although its underlying mechanism remains unclear. The purpose of this study was to evaluate the effect of PPAR alpha activation on endothelin-1-(ET-1-) caused cardiomyocyte hypertrophy and explore its underlying mechanisms. Human cardiomyocytes (HCMs) were cultured with or without ET-1, whereafter the inhibitory effects of fenofibrate, a PPAR alpha activator, on cell size and adiponectin protein were tested. We examined the activation of extracellular signal-regulated kinase (ERK) and p38 proteins caused by ET-1 and the inhibition of the ERK and p38 pathways on ET-1- induced cell size and adiponectin expression. Moreover, we investigated the interaction of PPAR alpha with adiponectin and nuclear factor-kappa B (NF-kappa B) by electrophoretic mobility shift assays and coimmunoprecipitation. ET-1 treatment significantly increased cell size, suppressed PPAR alpha expression, and enhanced the expression of adiponectin. Pretreatment with fenofibrate inhibited the increase in cell size and enhancement of adiponectin expression. ET-1 significantly activated the ERK and p38 pathways, whereas PD98059 and SB205380, respectively, inhibited them. Our results suggest that activated PPAR alpha can decrease activation of adiponectin and NF-kappa B and inhibit ET-1- induced cardiomyocyte hypertrophy.