Regulation of membrane type-1 matrix metalloproteinase activity and intracellular localization in clinical thoracic aortic aneurysms

• Published in: The Journal of thoracic and cardiovascular surgery Vol. 153; no. 3; pp. 537 - 546
• Main Authors: Ikonomidis, John S., Nadeau, Elizabeth K., Akerman, Adam W., Stroud, Robert E., Mukherjee, Rupak, Jones, Jeffrey A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2017
• Subjects: Aged; aneurysm; Animals; Aorta, Thoracic - enzymology; Aorta, Thoracic - pathology; Aortic Aneurysm, Thoracic - enzymology; Aortic Aneurysm, Thoracic - pathology; Cardiothoracic Surgery; Cell Line; Disease Models, Animal; Enzyme Activation - physiology; Fibroblasts - metabolism; Fibroblasts - pathology; Humans; Immunoblotting; Intracellular Space - enzymology; Matrix Metalloproteinase 14 - metabolism; Mice; Microscopy, Confocal; Middle Aged; MT1-MMP; protein kinase C; remodeling; thoracic aorta; Vascular Remodeling; PBS; aneurysm; remodeling; PMA; thoracic aorta; PKC; ECM; GFP; MMP; MT1-MMP; TGF; TAA; protein kinase C; phorbol 12-myristate 13-acetate; phosphate-buffered saline; green fluorescent protein; thoracic aortic aneurysm; membrane type-1 matrix metalloproteinase; matrix metalloproteinase; transforming growth factor; extracellular matrix
• ISSN: 0022-5223; 1097-685X; 1097-685X
• DOI: 10.1016/j.jtcvs.2016.10.065

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.