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MT1-MMP-dependent neovessel formation within the confines of the three-dimensional extracellular matrix.

Chun TH, Sabeh F, Ota I, Murphy H, McDonagh KT, Holmbeck K, Birkedal-Hansen H, Allen ED, Weiss SJ - J. Cell Biol. (2004)

Bottom Line: Extracellular matrix-degradative enzymes, including the matrix metalloproteinases (MMPs) MMP-2 and MMP-9, are thought to play key roles in angiogenesis by binding to docking sites on the cell surface after activation by plasmin- and/or membrane-type (MT) 1-MMP-dependent processes.Unexpectedly, neither MMP-2, MMP-9, their cognate cell-surface receptors (i.e., beta3 integrin and CD44), nor plasminogen are essential for collagenolytic activity, endothelial cell invasion, or neovessel formation.Instead, the membrane-anchored MMP, MT1-MMP, confers endothelial cells with the ability to express invasive and tubulogenic activity in a collagen-rich milieu, in vitro or in vivo, where it plays an indispensable role in driving neovessel formation.

View Article: PubMed Central - PubMed

Affiliation: Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA.

ABSTRACT
During angiogenesis, endothelial cells initiate a tissue-invasive program within an interstitial matrix comprised largely of type I collagen. Extracellular matrix-degradative enzymes, including the matrix metalloproteinases (MMPs) MMP-2 and MMP-9, are thought to play key roles in angiogenesis by binding to docking sites on the cell surface after activation by plasmin- and/or membrane-type (MT) 1-MMP-dependent processes. To identify proteinases critical to neovessel formation, an ex vivo model of angiogenesis has been established wherein tissue explants from gene-targeted mice are embedded within a three-dimensional, type I collagen matrix. Unexpectedly, neither MMP-2, MMP-9, their cognate cell-surface receptors (i.e., beta3 integrin and CD44), nor plasminogen are essential for collagenolytic activity, endothelial cell invasion, or neovessel formation. Instead, the membrane-anchored MMP, MT1-MMP, confers endothelial cells with the ability to express invasive and tubulogenic activity in a collagen-rich milieu, in vitro or in vivo, where it plays an indispensable role in driving neovessel formation.

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The functional role of the MMP-2–β3 integrin axis in capillary sprout formation. (A) Neovessel outgrowth from control littermate (left column) and MMP-2– (right column) mouse aortic rings suspended in type I collagen gels and stimulated with VEGF–HGF in 5% wild-type or MMP-2−/− serum are shown, respectively, after a 7-d incubation period (top). Cross sections of mature neovessels highlight the nearly identical pattern of tubule formation assessed by either light microscopy (middle; bar, 100 μm) or transmission electron micrograph (TEM) analysis (bottom; bar, 5 μm). (B) Capillary sprouting from wild-type and β3 integrin– mouse aortic rings as assessed by phase-contrast microscopy at day 7 is shown (top). Cross sections of the capillary sprouts from wild-type and β3- aortic rings display similar morphology (bottom).
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fig2: The functional role of the MMP-2–β3 integrin axis in capillary sprout formation. (A) Neovessel outgrowth from control littermate (left column) and MMP-2– (right column) mouse aortic rings suspended in type I collagen gels and stimulated with VEGF–HGF in 5% wild-type or MMP-2−/− serum are shown, respectively, after a 7-d incubation period (top). Cross sections of mature neovessels highlight the nearly identical pattern of tubule formation assessed by either light microscopy (middle; bar, 100 μm) or transmission electron micrograph (TEM) analysis (bottom; bar, 5 μm). (B) Capillary sprouting from wild-type and β3 integrin– mouse aortic rings as assessed by phase-contrast microscopy at day 7 is shown (top). Cross sections of the capillary sprouts from wild-type and β3- aortic rings display similar morphology (bottom).

Mentions: The association of catalytically active MMP-2 with the αvβ3 integrin has been reported to regulate the angiogenic response (Brooks et al., 1996, 1998; Silletti et al., 2001), but the role that this complex plays in directing invasive/tubulogenic programs has not been defined. To determine the relative roles of MMP-2 and αvβ3 in neovessel formation, we monitored vessel outgrowth and morphology in explants isolated from MMP-2– or αvβ3- mice. Although wild-type explants expressed both MMP-2 and β3, as assessed by RT-PCR (not depicted), MMP-2– and wild-type littermate explants mounted an indistinguishable tubulogenic response, without significant differences in mean capillary length or density (Figs. 2 A and 3 C). Furthermore, morphogenesis proceeded in normal fashion, with a ring of endothelial cells circumscribing a patent lumen (Fig. 2 A). Consistent with an MMP-2–independent tubulogenic program, neither vessel outgrowth nor vessel morphology was inhibited in the absence of the β3 integrin (Figs. 2 B and 3 C).


MT1-MMP-dependent neovessel formation within the confines of the three-dimensional extracellular matrix.

Chun TH, Sabeh F, Ota I, Murphy H, McDonagh KT, Holmbeck K, Birkedal-Hansen H, Allen ED, Weiss SJ - J. Cell Biol. (2004)

The functional role of the MMP-2–β3 integrin axis in capillary sprout formation. (A) Neovessel outgrowth from control littermate (left column) and MMP-2– (right column) mouse aortic rings suspended in type I collagen gels and stimulated with VEGF–HGF in 5% wild-type or MMP-2−/− serum are shown, respectively, after a 7-d incubation period (top). Cross sections of mature neovessels highlight the nearly identical pattern of tubule formation assessed by either light microscopy (middle; bar, 100 μm) or transmission electron micrograph (TEM) analysis (bottom; bar, 5 μm). (B) Capillary sprouting from wild-type and β3 integrin– mouse aortic rings as assessed by phase-contrast microscopy at day 7 is shown (top). Cross sections of the capillary sprouts from wild-type and β3- aortic rings display similar morphology (bottom).
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172577&req=5

fig2: The functional role of the MMP-2–β3 integrin axis in capillary sprout formation. (A) Neovessel outgrowth from control littermate (left column) and MMP-2– (right column) mouse aortic rings suspended in type I collagen gels and stimulated with VEGF–HGF in 5% wild-type or MMP-2−/− serum are shown, respectively, after a 7-d incubation period (top). Cross sections of mature neovessels highlight the nearly identical pattern of tubule formation assessed by either light microscopy (middle; bar, 100 μm) or transmission electron micrograph (TEM) analysis (bottom; bar, 5 μm). (B) Capillary sprouting from wild-type and β3 integrin– mouse aortic rings as assessed by phase-contrast microscopy at day 7 is shown (top). Cross sections of the capillary sprouts from wild-type and β3- aortic rings display similar morphology (bottom).
Mentions: The association of catalytically active MMP-2 with the αvβ3 integrin has been reported to regulate the angiogenic response (Brooks et al., 1996, 1998; Silletti et al., 2001), but the role that this complex plays in directing invasive/tubulogenic programs has not been defined. To determine the relative roles of MMP-2 and αvβ3 in neovessel formation, we monitored vessel outgrowth and morphology in explants isolated from MMP-2– or αvβ3- mice. Although wild-type explants expressed both MMP-2 and β3, as assessed by RT-PCR (not depicted), MMP-2– and wild-type littermate explants mounted an indistinguishable tubulogenic response, without significant differences in mean capillary length or density (Figs. 2 A and 3 C). Furthermore, morphogenesis proceeded in normal fashion, with a ring of endothelial cells circumscribing a patent lumen (Fig. 2 A). Consistent with an MMP-2–independent tubulogenic program, neither vessel outgrowth nor vessel morphology was inhibited in the absence of the β3 integrin (Figs. 2 B and 3 C).

Bottom Line: Extracellular matrix-degradative enzymes, including the matrix metalloproteinases (MMPs) MMP-2 and MMP-9, are thought to play key roles in angiogenesis by binding to docking sites on the cell surface after activation by plasmin- and/or membrane-type (MT) 1-MMP-dependent processes.Unexpectedly, neither MMP-2, MMP-9, their cognate cell-surface receptors (i.e., beta3 integrin and CD44), nor plasminogen are essential for collagenolytic activity, endothelial cell invasion, or neovessel formation.Instead, the membrane-anchored MMP, MT1-MMP, confers endothelial cells with the ability to express invasive and tubulogenic activity in a collagen-rich milieu, in vitro or in vivo, where it plays an indispensable role in driving neovessel formation.

View Article: PubMed Central - PubMed

Affiliation: Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA.

ABSTRACT
During angiogenesis, endothelial cells initiate a tissue-invasive program within an interstitial matrix comprised largely of type I collagen. Extracellular matrix-degradative enzymes, including the matrix metalloproteinases (MMPs) MMP-2 and MMP-9, are thought to play key roles in angiogenesis by binding to docking sites on the cell surface after activation by plasmin- and/or membrane-type (MT) 1-MMP-dependent processes. To identify proteinases critical to neovessel formation, an ex vivo model of angiogenesis has been established wherein tissue explants from gene-targeted mice are embedded within a three-dimensional, type I collagen matrix. Unexpectedly, neither MMP-2, MMP-9, their cognate cell-surface receptors (i.e., beta3 integrin and CD44), nor plasminogen are essential for collagenolytic activity, endothelial cell invasion, or neovessel formation. Instead, the membrane-anchored MMP, MT1-MMP, confers endothelial cells with the ability to express invasive and tubulogenic activity in a collagen-rich milieu, in vitro or in vivo, where it plays an indispensable role in driving neovessel formation.

Show MeSH
Related in: MedlinePlus