title: Abnormal vessel formation in the choroid of mice lacking tissue inhibitor of metalloprotease-3.
abstract: OBJECTIVE
  Tissue inhibitor of metalloprotease (TIMP)-3 is an inhibitor of matrix metalloprotease (MMP) and regulates angiogenesis. In the eye, TIMP3 is tightly associated with Bruch's membrane. In this study, the authors analyzed mice lacking TIMP3 for retinal abnormalities.
  
  
  METHODS
  Mice with targeted disruption of the Timp3 gene were generated (Timp3(-/-)) and bred into C57/Bl6 and CD1 backgrounds. Eyes were analyzed by light and electron microscopy. Vasculature was examined by scanning laser ophthalmoscopy, corrosion casts, and whole mount preparations. MMP activity was assessed by in situ zymography, angiogenic potential was evaluated by tube formation, and aortic ring assays and signaling pathways were studied by immunoblotting.
  
  
  RESULTS
  TIMP3-deficient mice develop abnormal vessels with dilated capillaries throughout the choroid. Enhanced MMP activity in the choroid region of Timp3(-/-) eyes was detected when compared with controls. Timp3(-/-)-derived tissue showed an increased angiogenic activity over wild-type, an effect that could specifically be inhibited by recombinant TIMP3. Moreover, the antiangiogenic property of TIMP3 was demonstrated to reside within the C-terminal domain. When VEGFR2 inhibitor was added to Timp3(-/-) aortic explants, endothelial sprout formation was markedly reduced, which provided evidence for an unbalanced VEGF-mediated angiogenesis in Timp3(-/-) animals. Finally, angiogenic signaling pathways are activated in Timp3(-/-)-derived cells.
  
  
  CONCLUSIONS
  These findings suggest that the distinct choroidal phenotype in mice lacking TIMP3 may be the result of a local disruption of extracellular matrix and angiogenic homeostasis, and they support an important role of TIMP3 in the regulation of choroidal vascularization.
authors.affiliation: Institute of Human Genetics, University of Regensburg, Regensburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Janssen
authors.forename: Julia
authors.initials: J
authors.lastname: Hoellenriegel
authors.forename: Marton
authors.initials: M
authors.lastname: Fogarasi
authors.forename: Heinrich
authors.initials: H
authors.lastname: Schrewe
authors.forename: Mathias
authors.initials: M
authors.lastname: Seeliger
authors.forename: Ernst
authors.initials: E
authors.lastname: Tamm
authors.forename: Andreas
authors.initials: A
authors.lastname: Ohlmann
authors.forename: Christian Albrecht
authors.initials: CA
authors.lastname: May
authors.forename: Bernhard H F
authors.initials: BH
authors.lastname: Weber
authors.forename: Heidi
authors.initials: H
authors.lastname: Stöhr
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000503:physiopathology; D001808:Blood Vessels / Q000002:abnormalities / Q000473:pathology; D016570:Bruch Membrane / Q000473:pathology; D002196:Capillaries / Q000254:growth & development; D002829:Choroid / Q000098:blood supply* / Q000201:enzymology; D005123:Eye / Q000378:metabolism; D066298:In Vitro Techniques; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009389:Neovascularization, Pathologic / Q000209:etiology; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000502:physiology*; D010641:Phenotype; D010857:Pigment Epithelium of Eye / Q000473:pathology; D017434:Protein Structure, Tertiary / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology; D012160:Retina / Q000473:pathology; D015398:Signal Transduction; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000172:deficiency / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors
chemical_list: D011994:Recombinant Proteins; D019717:Tissue Inhibitor of Metalloproteinase-3; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9