Small concentrations of oxLDL induce capillary tube formation from endothelial cells via LOX-1-dependent redox-sensitive pathway.
OBJECTIVE
Vascular endothelial growth factor (VEGF), a key angiogenic growth factor, stimulates angiogenesis. Low levels of reactive oxygen species (ROS) function as signaling molecules for angiogenesis. We postulated that low concentrations of oxLDL might induce low levels of ROS and initiate angiogenesis.


RESULTS
An in vitro model of tube formation from human coronary artery endothelial cells (HCAECs) was used. oxLDL (0.1, 1, 2, 5 microg/mL) induced VEGF expression and enhanced tube formation. oxLDL-mediated VEGF expression and tube formation were suppressed by a specific blocking anti-LOX-1 antibody. Anti-LOX-1 antibody also reduced oxLDL-induced increase in the expression of NADPH oxidase (gp91(phox) and p47(phox) subunits) and subsequent intracellular ROS generation, phosphorylation of p38 as well as p44/42MAPK, and NF-kappaB p65 expression. gp91(phox) siRNA had a similar effect. The expression of VEGF and NF-kappaB p65 induced by oxLDL was also inhibited by the specific extracellular signal-regulated kinase (ERK) 1/2 inhibitor U0126 and the p38 MAPK inhibitor SB203580. Importantly, the NADPH oxidase inhibitor apocynin, gp91(phox) siRNA, U0126, and SB203580 all reduced tube formation in response to oxLDL.


CONCLUSIONS
These findings suggest that small concentrations of oxLDL promote capillary tube formation by inducing the expression of VEGF via LOX-1-mediated activation of NADPH oxidase- MAPKs-NF-kappaB pathway.
Dandapat
Abhijit
A
Department of Cardiovascular Medicine, University of Arkansas for Medical Sciences and Central Arkansas Veterans Healthcare System, Little Rock, Ark 72205-7199, USA.
Hu
Changping
C
Sun
Liuqin
L
Mehta
Jawahar L
JL
D002478:Cells, Cultured; D003331:Coronary Vessels / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism*; D006801:Humans; D008077:Lipoproteins, LDL / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D051127:Scavenger Receptors, Class E / Q000502:physiology*; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
D008077:Lipoproteins, LDL; D016328:NF-kappa B; C495137:OLR1 protein, human; D017382:Reactive Oxygen Species; D051127:Scavenger Receptors, Class E; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C099252:oxidized low density lipoprotein; D019255:NADPH Oxidases; D020929:Mitogen-Activated Protein Kinase Kinases