title: Dimethylarginine dimethylaminohydrolase 1 modulates endothelial cell growth through nitric oxide and Akt.
abstract: OBJECTIVE
  Dimethylarginine dimethylaminohydrolase 1 (DDAH1) modulates NO production by degrading the endogenous nitric oxide (NO) synthase (NOS) inhibitors asymmetrical dimethylarginine (ADMA) and L-NG-monomethyl arginine (L-NMMA). This study examined whether, in addition to degrading ADMA, DDAH1 exerts ADMA-independent effects that influence endothelial function.
  
  
  RESULTS
  Using selective gene silencing of DDAH1 with small interfering RNA and overexpression of DDAH1 in human umbilical vein endothelial cells, we found that DDAH1 acts to promote endothelial cell proliferation, migration, and tube formation by Akt phosphorylation, as well as through the traditional role of degrading ADMA. Incubation of human umbilical vein endothelial cells with the NOS inhibitors l-NG-nitro-arginine methyl ester (L-NAME) or ADMA, the soluble guanylyl cyclase inhibitor 1H-(1,2,4)oxadiazolo-(4,3-2)quinoxalin-1-one, or the cGMP analog 8-(4-Chlorophenylthio)-cGMP had no effect on phosphorylated (p)-Akt(Ser473), indicating that the increase in p-Akt(Ser473) produced by DDAH1 was independent of the NO-cGMP signaling pathway. DDAH1 formed a protein complex with Ras, and DDAH1 overexpression increased Ras activity. The Ras inhibitor manumycin-A or dominant-negative Ras significantly attenuated the DDAH1-induced increase in p-Akt(Ser473). Furthermore, DDAH1 knockout impaired endothelial sprouting from cultured aortic rings, and overexpression of constitutively active Akt or DDAH1 rescued endothelial sprouting in the aortic rings from these mice.
  
  
  CONCLUSIONS
  DDAH1 exerts a unique role in activating Akt that affects endothelial function independently of degrading endogenous NOS inhibitors.
authors.affiliation: Division of Cardiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.forename: Xinli
authors.initials: X
authors.lastname: Hu
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Chen
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Bache
mesh_terms: D000581:Amidohydrolases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034622:RNA Interference; D015398:Signal Transduction; D013997:Time Factors; D046509:Tissue Culture Techniques; D014162:Transfection; D018631:ras Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: D000581:Amidohydrolases; D001120:Arginine; D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D018631:ras Proteins; C018524:N,N-dimethylarginine; C496314:NOS3 protein, human; C496315:Nos3 protein, mouse; C059999:dimethylargininase