GPR120 Agonist GW9508 Ameliorated Cellular Senescence Induced by Ox-LDL

Oxidized low-density lipoprotein (ox-LDL)-induced endothelial senescence is involved in the pathogenesis of atherosclerosis and many cardiovascular diseases. G-protein-coupled receptor 120 (GPR120), a type of orphan G-protein-coupled receptors (GPRs), plays a vital role in mediating anti-inflammatory and insulin-sensitizing effects. The biological function of GPR120 in vascular endothelial cells is largely unknown. The human aortic endothelial cells (HAECs) were treated with ox-LDL (100 μg/mL) in the presence or absence of GW9508 (50 μM) or AH9614 (1 μM) for 24 h. The LDH assay was used to determine cell death. The dihydroethidium (DHE) staining assay was used to measure intracellular levels of reactive oxidative species (ROS), and a senescence β-galactosidase assay kit was used to determine endothelial senescence. Gene and protein expressions were measured using real-time polymerase chain reaction (PCR) and western blot analysis, respectively. Ox-LDL treatment decreased the expression of GPR120 by more than half in HAECs. Typically, 100 μg/mL of ox-LDL- induced 35.2% LDH release, which was reduced to 16.9% by 50 μM GW9508, the agonist of GPR120. Importantly, GW9508 relieved cytotoxicity and suppressed the ox-LDL-induced increase in the activity of senescence-associated β-galactosidase (SA-β-Gal) (from 3.3-fold to 1.6-fold of the control group) and the generation of cellular reactive oxidative species (ROS) (from 3.8-fold to 1.6-fold of the control group). Furthermore, we found that GW9508 ameliorated ox-LDL-induced endothelial cell cycle arrest at the G0/G1 phase and the expression of key senescence proteins, including p53 and plasminogen activator inhibitor-1(PAI-1). Mechanistically, we showed that GW9508 promoted ox-LDL-induced transcriptional factor NF-E2-related factor 2 (NRF2) (increase by 47.3%) translocation into the nucleus. The effect of GW9508 is dependent on its receptor GPR120, the blockage of which by its specific antagonist, AH7614, abolished the antisenescence effect of GW9508. Collectively, this study revealed the protective effect of GPR120 activation in vascular endothelial cells, implying that GPR120 is a promising therapeutic target for the treatment of cardiovascular diseases.