Identification and Autoregulation of Receptor for OX-LDL in Cultured Human Coronary Artery Endothelial Cells

• Published in: Biochemical and biophysical research communications Vol. 248; no. 3; pp. 511 - 514
• Main Authors: Mehta, J.L., Li, D.Y.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 30.07.1998
• Subjects: Cells, Cultured; Coronary Vessels; Endothelium, Vascular - cytology; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Homeostasis; Humans; Kinetics; Lipoproteins, LDL - metabolism; Lipoproteins, LDL - pharmacology; Polymerase Chain Reaction; Receptors, LDL - analysis; Receptors, LDL - biosynthesis; Receptors, LDL - metabolism; Receptors, Oxidized LDL; RNA, Messenger - biosynthesis; Scavenger Receptors, Class E; Transcription, Genetic - drug effects
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1998.9004

Although macrophages scavenge oxidatively modified low density lipoprotein (ox-LDL) via specific receptors, the uptake of ox-LDL by endothelial cells is thought to be mediated by a different receptor (LOX-1). We examined the presence of LOX-1 on cultured human coronary artery endothelial cells (HCAECs) by RT-PCR, radioligand blot, and binding assays. LOX-1 mRNA and protein were consistently identified in HCAECs. [125I]-ox-LDL binding assay also identified high affinity binding sites for LOX-1 on HCAECs (KD:1.71 × 10−8M: Bmax:29.7 ng/mg protein). There was no change in LOX-1 expression in HCAECs treated with native-LDL. In contrast, incubation of HCAECs with ox-LDL (10–40 μg/ml) increased LOX-1 expression (mRNA and protein). The upregulation of LOX-1 expression appeared to be dependent on ox-LDL concentration. Higher concentration (100 μg/ml) however, decreased LOX-1 expression, perhaps related to its cytotoxic effect. These observations indicate that ox-LDL upregulates its own receptor on HCAECs. This phenomenon may explain enhanced uptake of ox-LDL by HCAECs in hyperlipidemia resulting in cellular dysfunction.