The ADMA/DDAH pathway regulates VEGF-mediated angiogenesis.
OBJECTIVE
Asymmetrical dimethylarginine (ADMA) is a nitric oxide synthase (NOS) inhibitor and cardiovascular risk factor associated with angiogenic disorders. Enzymes metabolising ADMA, dimethylarginine dimethylaminohydrolases (DDAH) promote angiogenesis, but the mechanisms are not clear. We hypothesized that ADMA/DDAH modifies endothelial responses to vascular endothelial growth factor (VEGF) by affecting activity of Rho GTPases, regulators of actin polymerization, and focal adhesion dynamics.


RESULTS
The effects of ADMA on VEGF-induced endothelial cell motility, focal adhesion turnover, and angiogenesis were studied in human umbilical vein endothelial cells (HUVECs) and DDAH I heterozygous knockout mice. ADMA inhibited VEGF-induced chemotaxis in vitro and angiogenesis in vitro and in vivo in an NO-dependent way. ADMA effects were prevented by overexpression of DDAH but were not associated with decreased proliferation, increased apoptosis, or changes in VEGFR-2 activity or expression. ADMA inhibited endothelial cell polarization, protrusion formation, and decreased focal adhesion dynamics, resulting from Rac1 inhibition after decrease in phosphorylation of vasodilator stimulated phosphoprotein (VASP). Constitutively active Rac1, and to a lesser extent dominant negative RhoA, abrogated ADMA effects in vitro and in vivo.


CONCLUSIONS
The ADMA/DDAH pathway regulates VEGF-induced angiogenesis in an NO- and Rac1-dependent manner.
National Heart and Lung Institute, Faculty of Medicine, Imperial College London, UK.
Lorna R
LR
Fiedler
Tiziana
T
Bachetti
James
J
Leiper
Ian
I
Zachary
Lihua
L
Chen
Thomas
T
Renné
Beata
B
Wojciak-Stothard
D000581:Amidohydrolases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D016764:Cell Polarity / Q000187:drug effects; D049109:Cell Proliferation; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D022001:Focal Adhesions / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D009479:Neuropeptides / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D000098662:Vasodilator-Stimulated Phosphoprotein
D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D009479:Neuropeptides; D010750:Phosphoproteins; C107953:RAC1 protein, human; C484602:Rac1 protein, mouse; D042461:Vascular Endothelial Growth Factor A; D000098662:Vasodilator-Stimulated Phosphoprotein; D009569:Nitric Oxide; C018524:N,N-dimethylarginine; D001120:Arginine; D000581:Amidohydrolases; C059999:dimethylargininase; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein