Role of LOX-1 in monocyte adhesion-triggered redox, Akt/eNOS and Ca2+ signaling pathways in endothelial cells.
This study was conducted to examine the role of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in monocyte adhesion-induced redox-sensitive, Akt/eNOS and Ca2+ signaling pathways in endothelial cells (ECs). LOX-1 was blocked by an antibody-neutralizing LOX-1 TS92 or small interfering RNA. In cultured human aortic ECs, monocyte adhesion activated Rac1 and p47(phox), and increased NADPH oxidase activity and reactive oxygen species (ROS) generation within 30 min and NF-kappaB phosphorylation within 1 h, resulting in redox-sensitive gene expression. Akt and eNOS phosphorylation was induced 15 min after adding monocytes and returned to control level after 30 min, whereas NO production was not altered by monocyte adhesion. Blockade of LOX-1 blunted the monocyte adhesion-triggered redox-sensitive signaling pathway and Akt/eNOS phosphorylation in ECs. Both endothelial intracellular Ca2+ mobilization and Ca2+ influx caused by monocyte attachment were markedly attenuated by pretreatment of ECs with TS92. This suggests that LOX-1 is involved in redox-sensitive, Akt/eNOS and Ca2+ signaling pathways in monocyte adhesion to ECs independent of oxidized low-density lipoprotein (ox-LDL). Furthermore, blockade of Ca2+ inhibited monocyte adhesion-triggered Rac1 and p47(phox) activation and ROS generation in ECs, whereas Ca2+ signaling was suppressed by blockade of NADPH oxidase and ROS generation. Finally, TS92 blocked the monocyte adhesion to ECs stimulated with or without tumor necrosis factor-alpha or ox-LDL. We provide evidence that LOX-1 plays a role in redox-sensitive, Akt/eNOS and Ca2+ signaling pathways in monocyte adhesion to ECs independent of the ox-LDL-LOX-1 axis.
Sakamoto
Nobuo
N
First Department of Internal Medicine, Fukushima Medical University, Fukushima 960-1295, Japan.
Ishibashi
Toshiyuki
T
Sugimoto
Koichi
K
Sawamura
Tatsuya
T
Sakamoto
Takayuki
T
Inoue
Nobutaka
N
Saitoh
Shu-Ichi
S
Kamioka
Masashi
M
Uekita
Hironori
H
Ohkawara
Hiroshi
H
Suzuki
Koji
K
Teramoto
Tamio
T
Maruyama
Yukio
Y
Takeishi
Yasuchika
Y
D000906:Antibodies; D020013:Calcium Signaling; D002448:Cell Adhesion; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000201:enzymology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D009000:Monocytes / Q000201:enzymology*; D019255:NADPH Oxidases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D051127:Scavenger Receptors, Class E / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D000906:Antibodies; D016328:NF-kappa B; C495137:OLR1 protein, human; C107953:RAC1 protein, human; D017382:Reactive Oxygen Species; D051127:Scavenger Receptors, Class E; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D051057:Proto-Oncogene Proteins c-akt; D020830:rac1 GTP-Binding Protein