Adhesion molecule expression in fibroblasts: alteration in fibroblast biology after transfection with LOX-1 plasmids.
The endothelial lectinlike, oxidatively (ox-) modified LDL receptor LOX-1 is a critical player in the pathogenesis of atherosclerosis and myocardial ischemia. Ox-LDL binding of LOX-1 results in the expression of various adhesion molecules, which attract monocytes to endothelial cells, an initial step in atherogenesis. We wished to examine the role of the ox-LDL/LOX-1 signaling pathway in fibroblasts, which naturally express low levels of LOX-1. Rat cardiac fibroblasts were transfected with either cytomegalovirus (CMV)-LOX-1wt (amino acids [aa] 1 to 273) or CMV-LOX-1(1-261) (an ox-LDL-binding negative mutant, aa 1 to 261) plasmid. Western blots showed that LOX-1 protein expression was increased significantly in cells transfected with CMV-LOX-1wt or CMV-LOX-1(1-261) plasmid (P<0.01 vs control). Fibroblasts transfected with CMV-LOX-1wt showed ox-LDL binding, whereas fibroblasts without transfection and those transfected with CMV-LOX-1(1-261) did not bind ox-LDL. Compared with untransfected cells, ox-LDL treatment (50 microg/mL, 24 hours) markedly induced the expression of the leukocyte adhesion molecules intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM)-1 as well as matrix metalloproteinase (MMP)-1 in cells transfected with CMV-LOX-1wt (P<0.05) but not in cells transfected with CMV-LOX-1(1-261). Concurrently, ox-LDL treatment enhanced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) (P<0.05 vs control) in CMV-LOX-1wt-transfected cells. These data suggest that in cardiac fibroblasts, ox-LDL binds to LOX-1 and activates p38 MAPK, followed by the expression of ICAM-1, VCAM-1, and MMP-1. Thus, fibroblasts transform into an endothelial phenotype on transfection with CMV-LOX-1wt and subsequent exposure to ox-LDL. This study provides a useful model system (plasmid-transfected fibroblasts) to study the molecular biology of LOX-1.
Chen
Kui
K
Department of Internal Medicine, University of Arkansas for Medical Sciences, Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, USA.
Chen
Jiawei
J
Liu
Yong
Y
Xie
Jin
J
Li
Dayuan
D
Sawamura
Tatsuya
T
Hermonat
Paul L
PL
Mehta
Jawahar L
JL
D000818:Animals; D002232:Carbocyanines; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D010957:Plasmids; D051381:Rats; D051127:Scavenger Receptors, Class E / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D002232:Carbocyanines; D024042:Collagen Type I; D008077:Lipoproteins, LDL; D051127:Scavenger Receptors, Class E; D019010:Vascular Cell Adhesion Molecule-1; C099252:oxidized low density lipoprotein; D018799:Intercellular Adhesion Molecule-1; C064633:1,1'-dipropyl-3,3,3',3'-tetramethylindocarbocyanine; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020781:Matrix Metalloproteinase 1