title: Endothelial Dimethylarginine Dimethylaminohydrolase 1 Is an Important Regulator of Angiogenesis but Does Not Regulate Vascular Reactivity or Hemodynamic Homeostasis.
abstract: BACKGROUND
  Asymmetrical dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthesis and a risk factor for cardiovascular disease. Dimethylarginine dimethylaminohydrolase (DDAH) enzymes are responsible for ADMA breakdown. It has been reported that endothelial DDAH1 accounts for the majority of ADMA metabolism. However, we and others have shown strong DDAH1 expression in a range of nonendothelial cell types, suggesting that the endothelium is not the only site of metabolism. We have developed a new endothelium-specific DDAH1 knockout mouse (DDAH1(En-/-)) to investigate the significance of endothelial ADMA in cardiovascular homeostasis.
  
  
  RESULTS
  DDAH1 deletion in the DDAH1(En-/-) mouse was mediated by Tie-2 driven Cre expression. DDAH1 deletion was confirmed through immunocytochemistry, whereas Western blotting showed that DDAH1 remained in the kidney and liver, confirming expression in nonendothelial cells. Plasma ADMA was unchanged in DDAH1(En-/-) mice, and cultured aortas released amounts of ADMA to similar to controls. Consistent with these observations, vasoreactivity ex vivo and hemodynamics in vivo were unaltered in DDAH1(En-/-) mice. In contrast, we observed significantly impaired angiogenic responses both ex vivo and in vivo.
  
  
  CONCLUSIONS
  We demonstrate that endothelial DDAH1 is not a critical determinant of plasma ADMA, vascular reactivity, or hemodynamic homeostasis. DDAH1 is widely expressed in a range of vascular and nonvascular cell types; therefore, the additive effect of DDAH1 expression in multiple organ systems determines plasma ADMA concentrations. Endothelial deletion of DDAH1 profoundly impairs the angiogenic capacity of endothelial cells, indicating that intracellular ADMA is a critical determinant of endothelial cell response.
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Laura
authors.initials: L
authors.lastname: Dowsett
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Sophie
authors.initials: S
authors.lastname: Piper
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Slaviero
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Dufton
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Olga
authors.initials: O
authors.lastname: Boruc
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Delahaye
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Lucy
authors.initials: L
authors.lastname: Colman
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Eliza
authors.initials: E
authors.lastname: Kalk
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: James
authors.initials: J
authors.lastname: Tomlinson
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Graeme
authors.initials: G
authors.lastname: Birdsey
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Randi
authors.affiliation: From MRC Clinical Sciences Centre (L.D., S.P., A.S., Z.W., O.B., M.D., L.C., E.K., J.T., J.L.) and National Heart and Lung Institute Vascular Science Unit (N.D., G.B., A.M.R.), Faculty of Medicine, Imperial College London, UK. james.leiper@csc.mrc.ac.uk.
authors.forename: James
authors.initials: J
authors.lastname: Leiper
mesh_terms: D000581:Amidohydrolases / Q000172:deficiency / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000201:enzymology*; D004730:Endothelium, Vascular / Q000201:enzymology*; D006439:Hemodynamics / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic / Q000502:physiology*
chemical_list: D000581:Amidohydrolases; C059999:dimethylargininase
keywords: angiogenesis; endothelium; neovascularization, physiologic; nitric oxide