title: Lipopolysaccharide induced LOX-1 expression via TLR4/MyD88/ROS activated p38MAPK-NF-κB pathway.
abstract: Lectin-like receptor for oxidized low density lipoprotein (LOX-1) plays a key role in endothelial ox-LDL endocytosis, endothelial dysfunction and atherogenesis. In the present study, the effect of lipopolysaccharide (LPS) on LOX-1 expression and the underlying molecular pathways were investigated. Human umbilical vein endothelial cells (HUVECs) were treated with LPS and the protein expressions of LOX-1, TLR4, TLR2, MyD88, Nox4, Nox2, PI3K, p38MAPK, JNK, ERK, Nrf1, Nrf2 and p65 were examined by Western blotting. The intracellular reactive oxygen species (ROS) production was examined by flow cytometry with fluorescence probe DCFH2-DA. The role of TLR4, MyD88 and Nox4 were determined with specific siRNA. The endothelial ox-LDL uptake and the endothelial-monocyte adhesion were evaluated with DiI-ox-LDL and Hoechst 33342 respectively. The effect of LPS on LOX-1 expression in aorta tissue was also studied with male C57/BL6 mice by intraperitoneal injection of LPS. The results showed that LPS induced LOX-1 protein expression in a time- and concentration-dependent manner. The mRNA expression of LOX-1 was also upregulated. The protein expression of LOX-1 and phosphorylated p38MAPK, p65 was significantly enhanced by LPS both in vitro and in vivo. LPS induced LOX-1 expression was blocked by siRNA for TLR4, MyD88, and Nox4 and inhibitors for p38MAPK, NF-κB, cyclooxygenase-2, and NADPH oxidase. Both LPS induced ox-LDL uptake and endothelial-monocyte adhesion were significantly inhibited by anti-LOX-1 antibody. LPS dramatically induced LOX-1 protein expression in aorta tissues. In conclusion, our data suggested that LPS induces LOX-1 expression via TLR4/MyD88/ROS activated p38MAPK/NF-κB pathway in endothelial cells, which provides new regulatory mechanisms for LOX-1 expression.
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
authors.forename: Wenwen
authors.initials: W
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
authors.forename: Guixin
authors.initials: G
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China. Electronic address: xpchen@umac.mo.
authors.forename: Xiuping
authors.initials: X
authors.lastname: Chen
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000378:metabolism; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008077:Lipoproteins, LDL / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000378:metabolism; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism*; D019255:NADPH Oxidases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D051127:Scavenger Receptors, Class E / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides; D008077:Lipoproteins, LDL; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D051127:Scavenger Receptors, Class E; D051197:Toll-Like Receptor 4; C099252:oxidized low density lipoprotein; D051546:Cyclooxygenase 2; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D048051:p38 Mitogen-Activated Protein Kinases
keywords: Endothelial cells; LOX-1; Lipopolysaccharide; ROS