SUN-LB137 Endocannabinoids Induce Endoplasmic Reticulum Stress in Hepatocytes and Human Coronary Artery Endothelial Cells

Abstract

Obesity and diabetes are important risk factors for the development of coronary heart disease and stroke. Plasma endocannabinoid (EC) levels are inappropriately elevated in obesity and diabetes, and are hypothesized to play a causal role in central regulation of weight gain. Importantly, it was recently demonstrated that cannabinoid receptor 1 (CNR1) triggers cell stress and induces apoptosis in kidney tubule cells exposed to palmitic acid and high-glucose (HG). HepG2 and human coronary artery endothelial cells (HCAEC) were treated with tunicamycin (TM), thapsigargin (TG), high-glucose (HG), anandamide (AN), and 2-arachondonyl glycerol (2-AG), and endoplasmic reticulum (ER) stress was measured. In cells treated with TM, AM, and 2-AG and the UPR inhibitors 4-phenylbutyrate (4-PB) and taurodeoxycholic acid (TUDCA), both 4-PB and TUDCA prevented AN and 2-AG from promoting ER stress. ER stress in cells treated with AN and 2-AG, but not TM, was inhibited by the CNR1 antagonist rimonabant. Similar results were obtained with HCAEC. Furthermore, treatment with AN and 2-AG induced inositol requiring enzyme 1α and protein kinase R-like endoplasmic reticulum kinase phosphorylation but had no effect on their expression, while activating transcription factor 6 and binding immunoglobulin protein expression were also induced by AN and 2-AG in both HepG2 and HCAEC. Finally, AN and 2-AG treatment induced CNR1 expression in both cell lines. These results strongly suggest that EC’s promote ER stress and potentially induce liver and endothelial cell dysfunction.