title: Proteomic identification of matrix metalloproteinase substrates in the human vasculature.
abstract: BACKGROUND
  Matrix metalloproteinases (MMPs) play a key role in cardiovascular disease, in particular aneurysm formation and plaque rupture. Surprisingly, little is known about MMP substrates in the vasculature.
  
  
  RESULTS
  We used a proteomics approach to identify vascular substrates for 3 MMPs, 1 of each of the 3 major classes of MMPs: Human arteries were incubated with MMP-3 (a member of stromelysins), MMP-9 (considered a gelatinase), and MMP-14 (considered a member of the collagenases and of the membrane-bound MMPs). Candidate substrates were identified by mass spectrometry based on increased release from the arterial tissue on digestion, spectral evidence for proteolytic degradation after gel separation, and identification of nontryptic cleavage sites. Using this approach, novel candidates were identified, including extracellular matrix proteins associated with the basement membrane, elastic fibers (emilin-1), and other extracellular proteins (periostin, tenascin-X). Seventy-four nontryptic cleavage sites were detected, many of which were shared among different MMPs. The proteomics findings were validated by immunoblotting and by digesting recombinant/purified proteins with exogenous MMPs. As proof-of-principle, results were related to in vivo pathology by searching for corresponding degradation products in human aortic tissue with different levels of endogenous MMP-9.
  
  
  CONCLUSIONS
  The application of proteomics to identify MMP targets is a new frontier in cardiovascular research. Our current classification of MMPs based on few substrates is an oversimplification of a complex area of biology. This study provides a more comprehensive assessment of potential MMP substrates in the vasculature and represents a valuable resource for future investigations.
authors.affiliation: King's British Heart Foundation Centre, King's College London, London, United Kingdom.
authors.forename: Christin
authors.initials: C
authors.lastname: Stegemann
authors.forename: Athanasios
authors.initials: A
authors.lastname: Didangelos
authors.forename: Javier
authors.initials: J
authors.lastname: Barallobre-Barreiro
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Langley
authors.forename: Kaushik
authors.initials: K
authors.lastname: Mandal
authors.forename: Marjan
authors.initials: M
authors.lastname: Jahangiri
authors.forename: Manuel
authors.initials: M
authors.lastname: Mayr
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D053511:Matrix Metalloproteinase 14 / Q000235:genetics / Q000378:metabolism*; D019278:Matrix Metalloproteinase 3 / Q000235:genetics / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D040901:Proteomics; D017534:Radial Artery / Q000737:chemistry* / Q000201:enzymology / Q000378:metabolism*; D055815:Young Adult
chemical_list: D019278:Matrix Metalloproteinase 3; D020780:Matrix Metalloproteinase 9; D053511:Matrix Metalloproteinase 14