title: Regulation of membrane type-1 matrix metalloproteinase activity and intracellular localization in clinical thoracic aortic aneurysms.
abstract: Membrane type-1 matrix metalloproteinase (MT1-MMP) is elevated during thoracic aortic aneurysm (TAA) development in mouse models, and plays an important role in the activation of matrix metalloproteinase (MMP)-2 and the release of matrix- bound transforming growth factor-β. In this study, we tested the hypothesis that MT1-MMP is subject to protein kinase C (PKC)-mediated regulation, which alters intracellular trafficking and activity with TAAs.
  
  
  
  Levels of MMP-2, native and phosphorylated MT1-MMP, and PKC-δ were measured in aortic tissue from patients with small TAAs (<5 cm; n = 8) and large TAAs (>6.5 cm; n = 8), and compared with values measured in normal controls (n = 8). Cellular localization of green fluorescent protein (GFP)-tagged MT1-MMP was assessed in aortic fibroblasts isolated from control and 4-week TAA mice. The effects of PKC-mediated phosphorylation on MT1-MMP cellular localization and function (active MMP-2 vs phospo-Smad2 abundance) were assessed after treatment with a PKC activator (phorbol-12-myristate-13-acetate [PMA], 100 nM) with and without a PKC-δ-specific inhibitor (röttlerin, 3 μM).
  
  
  
  Compared with controls, MT1-MMP abundance was increased in aortas from both TAA groups. Active MMP-2 was increased only in the large TAA group. The abundances of phosphorylated MT1-MMP and activated PKC-δ were enhanced in the small TAA group compared with the large TAA group. MT1-MMP was localized on the plasma membrane in aortic fibroblasts from control mice and in endosomes from TAA mice. Treatment with PMA induced MT1-MMP-GFP internalization, enhanced phospho-Smad2, and reduced MMP-2 activation, whereas röttlerin pretreatment inhibited these effects.
  
  
  
  Phosphorylation of MT1-MMP mediates its activity through directing cellular localization, shifting its role from MMP-2 activation to intracellular signaling. Thus, targeted inhibition of MT1-MMP may have therapeutic relevance as an approach to attenuating TAA development.
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC.
authors.forename: John S
authors.initials: JS
authors.lastname: Ikonomidis
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC.
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Nadeau
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC.
authors.forename: Adam W
authors.initials: AW
authors.lastname: Akerman
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Stroud
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC; Research Service, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC.
authors.forename: Rupak
authors.initials: R
authors.lastname: Mukherjee
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC; Research Service, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC. Electronic address: jonesja@musc.edu.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Jones
mesh_terms: D000368:Aged; D000818:Animals; D001013:Aorta, Thoracic / Q000201:enzymology* / Q000473:pathology; D017545:Aortic Aneurysm, Thoracic / Q000201:enzymology* / Q000473:pathology; D002460:Cell Line; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000502:physiology*; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D006801:Humans; D015151:Immunoblotting; D042541:Intracellular Space / Q000201:enzymology; D053511:Matrix Metalloproteinase 14 / Q000378:metabolism*; D051379:Mice; D018613:Microscopy, Confocal; D008875:Middle Aged; D066253:Vascular Remodeling
chemical_list: D053511:Matrix Metalloproteinase 14
keywords: MT1-MMP; aneurysm; protein kinase C; remodeling; thoracic aorta