Palmitic Acid Increases Endothelin-1 Expression in Vascular Endothelial Cells through the Induction of Endoplasmic Reticulum Stress and Protein Kinase C Signaling

Abstract

Objective: We investigated the regulation of endothelin-1 (ET-1) expression in in vivo high-fat diet (HFD)-fed mice and in vitro cultured human aortic endothelial cells (HAECs). Methods: Male C57BL/6 mice were fed on standard chow, serum was prepared, and ET-1 levels were analyzed using an ELISA kit. Quantitative PCR was performed using iQ SYBR Green Supermix. Statistical significance was assessed using SPSS, with p < 0.05 considered significant. Results: The serum ET-1 content and endothelial expression of ET-1 mRNA were increased in the HFD-fed mice compared to the chow-fed control mice. Moreover, the mRNA expression of ET-1 was significantly increased in cultured HAECs in response to acute (< 24 h) and chronic (12–16 days) treatments with palmitic acid (PA), one of the most abundant saturated fatty acids in obesity. We found that the induction of ET-1 expression by PA was abolished by pretreating the cells with the endoplasmic reticulum (ER) stress inhibitor 4-phenylbutyric acid or the protein kinase C (PKC) inhibitor Gö 6850. Conclusion: Our findings demonstrate for the first time that PA increases ET-1 expression in endothelial cells through the induction of ER stress and the activation of PKC, providing novel mechanistic insights into the pathogenesis of obesity-associated hypertension and cardiovascular diseases.