Caveolin-1 expression is critical for vascular endothelial growth factor-induced ischemic hindlimb collateralization and nitric oxide-mediated angiogenesis.
Nitric oxide (NO) is a powerful angiogenic mediator acting downstream of vascular endothelial growth factor (VEGF). Both the endothelial NO synthase (eNOS) and the VEGFR-2 receptor colocalize in caveolae. Because the structural protein of these signaling platforms, caveolin, also represses eNOS activity, changes in its abundance are likely to influence the angiogenic process in various ways. In this study, we used mice deficient for the caveolin-1 gene (Cav-/-) to examine the impact of caveolae suppression in a model of adaptive angiogenesis obtained after femoral artery resection. Evaluation of the ischemic tissue perfusion and histochemical analyses revealed that contrary to Cav+/+ mice, Cav-/- mice failed to recover a functional vasculature and actually lost part of the ligated limbs, thereby recapitulating the effects of the NOS inhibitor L-NAME administered to operated Cav+/+ mice. We also isolated endothelial cells (ECs) from Cav-/- aorta and showed that on VEGF stimulation, NO production and endothelial tube formation were dramatically abrogated when compared with Cav+/+ ECs. The Ser1177 eNOS phosphorylation and Thr495 dephosphorylation but also the ERK phosphorylation were similarly altered in VEGF-treated Cav-/- ECs. Interestingly, caveolin transfection in Cav-/- ECs redirected the VEGFR-2 in caveolar membranes and restored the VEGF-induced ERK and eNOS activation. However, when high levels of recombinant caveolin were reached, VEGF exposure failed to activate ERK and eNOS. These results emphasize the critical role of caveolae in ensuring the coupling between VEGFR-2 stimulation and downstream mediators of angiogenesis. This study also provides new insights to understand the paradoxical roles of caveolin (eg, repressing basal enzyme activity but facilitating activation on agonist stimulation) in cardiovascular pathophysiology.
Sonveaux
Pierre
P
University of Louvain Medical School, Unit of Pharmacology and Therapeutics, Brussels, Belgium.
Martinive
Philippe
P
DeWever
Julie
J
Batova
Zuzana
Z
Daneau
Géraldine
G
Pelat
Michel
M
Ghisdal
Philippe
P
Grégoire
Vincent
V
Dessy
Chantal
C
Balligand
Jean-Luc
JL
Feron
Olivier
O
D000818:Animals; D001011:Aorta; D021941:Caveolae / Q000502:physiology*; D051242:Caveolin 1; D022461:Caveolins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D002451:Cell Compartmentation; D002478:Cells, Cultured / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D006614:Hindlimb / Q000098:blood supply; D007511:Ischemia / Q000503:physiopathology / Q000628:therapy; D051379:Mice; D018345:Mice, Knockout; D019331:NG-Nitroarginine Methyl Ester / Q000633:toxicity; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000502:physiology; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D011993:Recombinant Fusion Proteins / Q000502:physiology; D015398:Signal Transduction; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000502:physiology
C495541:Cav1 protein, mouse; D051242:Caveolin 1; D022461:Caveolins; D011993:Recombinant Fusion Proteins; D042461:Vascular Endothelial Growth Factor A; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D040301:Vascular Endothelial Growth Factor Receptor-2; D048049:Extracellular Signal-Regulated MAP Kinases; D019331:NG-Nitroarginine Methyl Ester