on September 24, 2009
Published online before print September 24, 2009, doi: 10.1161/ATVBAHA.109.194035
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Submitted on July 6, 2009
Accepted on September 11, 2009
The ADMA/DDAH Pathway Regulates VEGF-Mediated Angiogenesis
Lorna R Fiedler ;
From the National Heart and Lung Institute, Faculty of Medicine (L.R.F.), Imperial College London, UK; Molecular Cardiology (T.B.), Fondazione Salvatore Maugeri, Pavia, Italy; MRC Clinical Sciences Centre (J.L.), Imperial College London, UK; the Department of Cardiovascular Science (I.Z.), BHF Laboratories, Rayne Institute, University College London, UK; the Center for Cardiovascular Biology (L.C.), University of Washington, Seattle; the Department of Molecular Medicine and Surgery (T.R.), Karolinska Institutet, Stockholm, Sweden; and the Department of Experimental Medicine and Toxicology, Division of Investigative Science (B.W.-S.), Imperial College London, UK.
* To whom correspondence should be addressed. E-mail: b.wojciak-stothard{at}imperial.ac.uk.
Objectives—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.
Methods and 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.
Conclusion—The DDAH/ADMA pathway regulates VEGF-induced angiogenesis in an NO- and Rac1-dependent manner.
Key words: Rho GTPase • ADMA • DDAH I • VEGF • angiogenesis