CRP is a novel ligand for the oxidized LDL receptor LOX-1.
C-reactive protein (CRP) is a risk factor for cardiovascular events and functions to amplify vascular inflammation through promoting endothelial dysfunction. Lectin-like oxidized low-density lipoprotein (oxLDL) receptor-1 (LOX-1) is the primary endothelial receptor for oxLDL, and both its expression and function are associated with vascular inflammation. As a scavenger receptor, LOX-1 is capable of binding to a variety of structurally unrelated ligands. Evidence is provided that demonstrates that CRP can act as a novel ligand for LOX-1. The direct interaction between these two proteins was demonstrated with purified protein in both ELISA and AlphaScreen assays. This interaction could be disrupted with known LOX-1 ligands, such as oxLDL and carrageenan. Moreover, the CRP interaction with cell surface-expressed LOX-1 was confirmed in cell-based immunofluorescent-binding studies. Mutagenesis studies demonstrated that the arginine residues forming the basic spine structure on the LOX-1 ligand-binding interface were dispensable for CRP binding, suggesting a novel ligand-binding mechanism for LOX-1, distinct from that used for oxLDL binding. The treatment of human endothelial cells with CRP led to the activation of proinflammatory genes including IL-8, ICAM-1, and VCAM-1. The inductions of these genes by CRP were LOX-1 dependent, as demonstrated by their attenuation in cells transfected with LOX-1 small-interfering RNA. Our study identifies and characterizes the direct interaction between LOX-1 and CRP and suggests that this interaction may mediate CRP-induced endothelial dysfunction.
Shih
Heather H
HH
Biological Technologies, Wyeth Research, Cambridge, MA, USA.
Zhang
Songwen
S
Cao
Wei
W
Hahn
Ashleigh
A
Wang
Juan
J
Paulsen
Janet E
JE
Harnish
Douglas C
DC
D000818:Animals; D001120:Arginine; D001665:Binding Sites; D002097:C-Reactive Protein / Q000235:genetics / Q000378:metabolism*; D016466:CHO Cells; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D042783:Endothelial Cells / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics; D016209:Interleukin-8 / Q000235:genetics; D008024:Ligands; D008077:Lipoproteins, LDL / Q000378:metabolism; D009154:Mutation; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D051127:Scavenger Receptors, Class E / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D015854:Up-Regulation; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics
C508606:CXCL8 protein, human; D018836:Inflammation Mediators; D016209:Interleukin-8; D008024:Ligands; D008077:Lipoproteins, LDL; C495137:OLR1 protein, human; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D051127:Scavenger Receptors, Class E; D019010:Vascular Cell Adhesion Molecule-1; C099252:oxidized low density lipoprotein; D018799:Intercellular Adhesion Molecule-1; D002097:C-Reactive Protein; D001120:Arginine