title: Endothelial nitric oxide deficiency reduces MMP-13-mediated cleavage of ICAM-1 in vascular endothelium: a role in atherosclerosis.
abstract: OBJECTIVE
  Lack of endothelial nitric oxide synthase worsens atherosclerosis at least by increasing monocyte adhesion to endothelial cells. The purpose of this study was to elucidate the molecular mechanism elicited by NO.
  
  
  RESULTS
  We evaluated atherosclerosis in apoE and NOS3/apoE-deficient mice fed with high-cholesterol diet. We found significant increase in aortic lesion size, and infiltration of macrophages in NOS3/apoE-null mice when compared to apoE-deficient animals. To test the relevance of cellular adhesion as well as extracellular matrix degradation, we evaluated ICAM-1, VCAM-1, PECAM-1, MMP-2, MMP-9, MMP-12, MT1-MMP, and MMP-13 levels in mouse aortas. Lack of NO inhibits MMP-13 and increases ICAM-1 levels in atherosclerosis as compared to apoE-null mice. Ectopically expression of ICAM-1 in eukaryotic cells revealed that extracellular domain of ICAM-1 harbors a substrate recognized by MMP-13. Incubation of COS-7 cells expressing ectopic ICAM-1 in the presence of active MMP-13 induced inhibition of RAW 264.7 cell adhesion to COS-7 monolayers. MALDI-TOF MS analysis combined to Liquid chromatography coupled to Ion Trap MS on ICAM-1 incubated with MMP-13 allowed us to determine the cleavage sites of MMP-13 at positions E61 and G98 of ICAM-1. G98 is part of a PDGQS moiety, which shows homology with the consensus PDGLS substrate located at the MMP-13 cleaved site of type II collagen I-alpha.
  
  
  CONCLUSIONS
  Taking together, these results point toward MMP-13 as a mechanism for the NO-mediated protection of atherosclerosis.
authors.affiliation: Fundación Centro Nacional de Investigaciones Cardiovasculares, Melchor Fernández Almagro 3, 28029 Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Tarín
authors.forename: Monica
authors.initials: M
authors.lastname: Gomez
authors.forename: Enrique
authors.initials: E
authors.lastname: Calvo
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: López
authors.forename: Carlos
authors.initials: C
authors.lastname: Zaragoza
mesh_terms: D000821:Animal Feed; D000818:Animals; D001013:Aorta, Thoracic / Q000473:pathology*; D001057:Apolipoproteins E / Q000172:deficiency*; D050197:Atherosclerosis / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology*; D002791:Cholesterol, Dietary; D004032:Diet; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000201:enzymology* / Q000473:pathology; D005109:Extracellular Matrix / Q000473:pathology; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics*; D008264:Macrophages / Q000502:physiology; D053509:Matrix Metalloproteinase 13 / Q000235:genetics / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D052250:Nitric Oxide Synthase Type III / Q000172:deficiency*
chemical_list: D001057:Apolipoproteins E; D002791:Cholesterol, Dietary; D061965:Matrix Metalloproteinase Inhibitors; D018799:Intercellular Adhesion Molecule-1; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D053509:Matrix Metalloproteinase 13