title: Impact of glycated LDL on endothelial nitric oxide synthase in vascular endothelial cells: involvement of transmembrane signaling and endoplasmic reticulum stress.
abstract: Cardiovascular diseases are the major cause of mortality in diabetes patients. Increased levels of glycated low density lipoprotein (glyLDL) are detected in diabetic patients. Endothelial nitric oxide synthase (eNOS) generates nitric oxide, which is responsible to endothelium-dependent vasodilation. The impact of glyLDL on the expression and activity of eNOS in vascular endothelial cells (EC) remains unknown. The present study investigated the effect of glyLDL on the levels of protein, mRNA and activity of eNOS in cultured human umbilical vein EC. The results demonstrated that incubation of EC with physiological concentrations of glyLDL significantly reduced the abundances of eNOS protein in EC with the maximal inhibition at 100μg/ml for 24h. At the optimized condition, glyLDL decreased eNOS mRNA and reduced its activity in EC. Blocking antibody against the receptor for advanced glycation end products (RAGE) prevented glyLDL-induced downregulation of eNOS in EC. GlyLDL increased the translocation of H-Ras from cytoplasm to membrane in EC. Farnesyl-transferase inhibitor-276, an H-Ras antagonist, normalized glyLDL-induced downregulation of eNOS and prevented glyLDL-induced upregulation of H-Ras in EC membrane. Treatment with 4-phenylbutyric acid, an endoplasmic reticulum (ER) stress antagonist, prevented glyLDL-induced eNOS downregulation in EC. The results suggest that diabetes-associated metabolic stress inhibits the production and activity of eNOA in cultured human vascular EC through the activation of RAGE/H-Ras mediated upstream signaling pathway. ER stress induced by glyLDL is possibly involved in eNOS downregulation.
authors: Department of Physiology & Pathophysiology, University of Manitoba, Winnipeg, Canada.
authors: Manoj
authors: M
authors: Mohanan Nair
authors: Department of Internal Medicine, University of Manitoba, Winnipeg, Canada.
authors: Ruozhi
authors: R
authors: Zhao
authors: Department of Internal Medicine, University of Manitoba, Winnipeg, Canada.
authors: Xueping
authors: X
authors: Xie
authors: Department of Physiology & Pathophysiology, University of Manitoba, Winnipeg, Canada; Department of Internal Medicine, University of Manitoba, Winnipeg, Canada. Electronic address: garry.shen@umanitoba.ca.
authors: Garry X
authors: GX
authors: Shen
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D059865:Endoplasmic Reticulum Stress / Q000502:physiology*; D042783:Endothelial Cells / Q000378:metabolism*; D017127:Glycation End Products, Advanced; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D000093844:Glycated Proteins
chemical_list: D017127:Glycation End Products, Advanced; D008077:Lipoproteins, LDL; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; C031797:glycated lipoproteins, LDL; D000093844:Glycated Proteins; C496314:NOS3 protein, human
keywords: Diabetes; Endoplasmic reticulum; Endothelial cells; Glycation; Low density lipoprotein; Nitric oxide synthase