PPARβ/δ attenuates palmitate-induced endoplasmic reticulum stress and induces autophagic markers in human cardiac cells

• Main Authors: Palomer, Xavier, Capdevila-Busquets, Eva, Botteri, Gaia, Salvadó, Laia, Barroso, Emma, Davidson, Mercy M., Michalik, Liliane, Wahli, Walter, Vázquez-Carrera, Manuel
• Other Authors: Lee Kong Chian School of Medicine (LKCMedicine)
• Format: Article
• Language: English
• Published: 2014
• Subjects: DRNTU::Science::Medicine
• Online Access: https://hdl.handle.net/10356/105877; http://hdl.handle.net/10220/20939
• Institution: Nanyang Technological University

Background: Chronic endoplasmic reticulum (ER) stress contributes to the apoptotic cell death in the myocardium, thereby playing a critical role in the development of cardiomyopathy. ER stress has been reported to be induced after high-fat diet feeding in mice and also after saturated fatty acid treatment in vitro. Therefore, since several studies have shown that peroxisome proliferator-activated receptor (PPAR)β/δ inhibits ER stress, the main goal of this study consisted in investigating whether activation of this nuclear receptor was able to prevent lipid-induced ER stress in cardiac cells. Methods and results: Wild-type and transgenic mice with reduced PPARβ/δ expression were fed a standard diet or a high-fat diet for two months. For in vitro studies, a cardiomyocyte cell line of human origin, AC16, was treated with palmitate and the PPARβ/δ agonist GW501516. Our results demonstrate that palmitate induced ER stress in AC16 cells, a fact which was prevented after PPARβ/δ activation with GW501516. Interestingly, the effect of GW501516 on ER stress occurred in an AMPK-independent manner. The most striking result of this study is that GW501516 treatment also upregulated the protein levels of beclin 1 and LC3II, two well-known markers of autophagy. In accordance with this, feeding on a high-fat diet or suppression of PPARβ/δ in knockout mice induced ER stress in the heart. Moreover, PPARβ/δ knockout mice also displayed a reduction in autophagic markers. Conclusion: Our data indicate that PPARβ/δ activation might be useful to prevent the harmful effects of ER stress induced by saturated fatty acids in the heart by inducing autophagy.