Abstract
In this study we examined the effect of oxidized low density lipoprotein (ox-LDL) on the intracellular production of reactive oxygen species (ROS) in bovine aortic endothelial cells (BAECs) and whether this increase occurs through its binding to the endothelial receptor lectin-like ox-LDL receptor-1 (LOX-1). Furthermore, this study also aimed to ascertain whether the binding of ox-LDL to LOX-1 is associated with NF-kappaB activation. ox-LDL induced a significant dose-dependent increase in ROS production after a 30-s incubation with BAECs (p < 0.01). ROS formation was markedly reduced in BAECs incubated with anti-LOX-1 monoclonal antibody (p < 0.001), while control nonimmune IgG produced no effect. ox-LDL induced a time- and dose-dependent significant increase in ROS formation only in CHO-K1 cells stably expressing bovine LOX-1 (p < 0.001), while no increase was present in CHO-K1 cells. The activation of the transcription factor NF-kappaB in BAECs was evident after a 5-min incubation with ox-LDL and was attenuated by anti-LOX-1 monoclonal antibody. The conclusion is that one of the pathophysiological consequences of ox-LDL binding to LOX-1 may be the activation of NF-kappaB through an increased ROS production.
Highlights
Oxidation of low density lipoprotein (LDL)1 is believed to play an important role in the pathogenesis of atherosclerosis [1,2,3,4,5]
To test the specificity of DCF increase induced by oxidized LDL (ox-LDL) in bovine aortic endothelial cells (BAECs), we preincubated BAECs with different antioxidants, known to work as radical scavengers
We showed that ox-LDL increased the intracellular formation of reactive oxygen species (ROS) in aortic endothelial cells
Summary
Oxidation of low density lipoprotein (LDL) is believed to play an important role in the pathogenesis of atherosclerosis [1,2,3,4,5]. Ox-LDL has been shown to activate NF-B [15,16,17] and increase the production of superoxide radicals (O2.) in endothelial [18] and nonendothelial cells [19, 20] It is not clear, if these effects are unspecifically related to some peroxidative products of the lipoprotein or due to a more specific mechanism. A novel receptor for ox-LDL, designated lectin-like ox-LDL receptor-1 (LOX-1) was cloned from cultured bovine aortic endothelial cells (BAECs) [21]. It has a type II membrane protein structure with a short N-terminal cytosolic domain and a long C-terminal extracellular domain but is distinct from type I and type II scavenger receptors [21]. Since intracellularly ROS play a major role in the translocation of NF-B [13, 22], this study aimed to ascertain whether the binding of ox-LDL to LOX-1 is associated with NF-B activation
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