title: Trafficking of the membrane type-1 matrix metalloproteinase in ischemia and reperfusion: relation to interstitial membrane type-1 matrix metalloproteinase activity.
abstract: BACKGROUND
  The matrix metalloproteinases (MMPs) contribute to regional remodeling after prolonged periods of ischemia and reperfusion (I/R), but specific MMP types activated during this process remain poorly understood. A novel class, the membrane-type MMPs (MT-MMPs), has been identified in the myocardium, but activity of these MMP types has not been assessed in vivo, particularly during I/R.
  
  
  RESULTS
  Pigs (30 kg, n=8) were instrumented with microdialysis catheters to measure MT1-MMP activity in both ischemic and nonischemic (remote) myocardium. A validated MT1-MMP fluorogenic substrate was infused through the microdialysis system, and changes in fluorescence were reflective of MT1-MMP activity at steady state, during ischemia (90 minutes), and during reperfusion (120 minutes). At peak ischemia, MT1-MMP activity was increased by >40% in the ischemic region, with no change in the remote region, which persisted with reperfusion (P<0.05). After I/R, MT1-MMP abundance was increased by >50% (P<0.05). Differential centrifugation revealed that the endosomal fraction (which contains subcellular organelles) within the ischemic myocardium was associated with a >135% increase in MT1-MMP (P<0.05). Furthermore, in an isolated left ventricular myocyte model of I/R, hypoxia (simulated ischemia) induced a >70% increase in MT1-MMP abundance in myocytes, and confocal microscopy revealed MT1-MMP internalization during this time period and reemergence to the membrane with reperfusion.
  
  
  CONCLUSIONS
  These unique results demonstrate that a specific MMP type, MT1-MMP, is increased in abundance and activity with I/R and is likely attributed, at least in part, to changes in intracellular trafficking.
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, and the Ralph H. Johnson Veteran's Affairs Medical Center, Charleston, SC 29403, USA.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Deschamps
authors.forename: William M
authors.initials: WM
authors.lastname: Yarbrough
authors.forename: Christina E
authors.initials: CE
authors.lastname: Squires
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Allen
authors.forename: David M
authors.initials: DM
authors.lastname: McClister
authors.forename: Kathryn B
authors.initials: KB
authors.lastname: Dowdy
authors.forename: Julie E
authors.initials: JE
authors.lastname: McLean
authors.forename: Joseph T
authors.initials: JT
authors.lastname: Mingoia
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Sample
authors.forename: Rupak
authors.initials: R
authors.lastname: Mukherjee
authors.forename: Francis G
authors.initials: FG
authors.lastname: Spinale
mesh_terms: D000818:Animals; D015687:Cell Hypoxia; D011992:Endosomes / Q000201:enzymology; D006352:Heart Ventricles; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000032:analysis / Q000378:metabolism*; D017551:Microdialysis; D018613:Microscopy, Confocal; D017202:Myocardial Ischemia / Q000201:enzymology* / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000201:enzymology* / Q000473:pathology; D009206:Myocardium / Q000201:enzymology; D032383:Myocytes, Cardiac / Q000201:enzymology* / Q000648:ultrastructure; D021381:Protein Transport; D013347:Subcellular Fractions / Q000201:enzymology; D034421:Sus scrofa; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000032:analysis; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000032:analysis; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000032:analysis; D019714:Tissue Inhibitor of Metalloproteinases / Q000032:analysis; D000097792:Tissue Inhibitor of Metalloproteinase-4
chemical_list: D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D019715:Tissue Inhibitor of Metalloproteinase-1; D019716:Tissue Inhibitor of Metalloproteinase-2; D019717:Tissue Inhibitor of Metalloproteinase-3; D019714:Tissue Inhibitor of Metalloproteinases; D000097792:Tissue Inhibitor of Metalloproteinase-4