Altered angiogenesis in caveolin-1 gene-deficient mice is restored by ablation of endothelial nitric oxide synthase.
Caveolin-1 is an essential structural protein of caveolae, specialized plasma membrane organelles highly abundant in endothelial cells, where they regulate multiple functions including angiogenesis. Caveolin-1 exerts a tonic inhibition of endothelial nitric oxide synthase (eNOS) activity. Accordingly, caveolin-1 gene-disrupted mice have enhanced eNOS activity as well as increased systemic nitric oxide (NO) levels. We hypothesized that excess eNOS activity, secondary to caveolin deficiency, would mediate the decreased angiogenesis observed in caveolin-1 gene-disrupted mice. We tested tumor angiogenesis in mice lacking either one or both proteins, using in vitro, ex vivo, and in vivo assays. We show that endothelial cell migration, tube formation, cell sprouting from aortic rings, tumor growth, and angiogenesis are all significantly impaired in both caveolin-1-null and eNOS-null mice. We further show that these parameters were either partially or fully restored in double knockout mice that lack both caveolin-1 and eNOS. Furthermore, the effects of genetic ablation of eNOS are mimicked by the administration of the NOS inhibitor N-nitro-L-arginine methyl ester hydrochloride (L-NAME), including the reversal of the caveolin-1-null mouse angiogenic phenotype. This study is the first to demonstrate the detrimental effects of unregulated eNOS activity on angiogenesis, and shows that impaired tumor angiogenesis in caveolin-1-null mice is, at least in part, the result of enhanced eNOS activity.
University of Queensland School of Pharmacy, Woolloongabba, Australia.
Christudas
C
Morais
Quteba
Q
Ebrahem
Bela
B
Anand-Apte
Marie-Odile
MO
Parat
D000818:Animals; D051242:Caveolin 1 / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D002633:Chemotaxis / Q000502:physiology; D016510:Corneal Neovascularization / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008168:Lung / Q000166:cytology / Q000187:drug effects; D008546:Melanoma, Experimental / Q000098:blood supply / Q000473:pathology / Q000517:prevention & control; D051379:Mice; D018345:Mice, Knockout; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology / Q000627:therapeutic use; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000378:metabolism* / Q000517:prevention & control; D018919:Neovascularization, Physiologic / Q000187:drug effects; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052250:Nitric Oxide Synthase Type III / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology
D051242:Caveolin 1; D004791:Enzyme Inhibitors; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D019331:NG-Nitroarginine Methyl Ester