title: Nitric oxide regulates transforming growth factor-beta signaling in endothelial cells.
abstract: Many forms of vascular disease are characterized by increased transforming growth factor (TGF)-beta1 expression and endothelial dysfunction. Smad proteins are a key step in TGF-beta-initiated signal transduction. We hypothesized that NO may regulate endothelial TGF-beta-dependent gene expression. We show that NO inhibits TGF-beta/Smad-regulated gene transactivation in a cGMP-dependent manner. NO effects were mimicked by a soluble analogue of cGMP. Inhibition of cGMP-dependent protein kinase 1 (PKG-1) or overexpression of dominant-negative PKG-1alpha suppressed NO/cGMP inhibition of TGF-beta-induced gene expression. Inversely, overexpression of PKG-1alpha catalytic subunit blocked TGF-beta-induced gene transactivation. Furthermore NO delayed and reduced phosphorylated Smad2/3 nuclear translocation, an effect mediated by PKG-1, whereas NG-nitro-L-arginine methyl ester augmented Smad phosphorylation and gene expression in response to TGF-beta. Aortas from endothelial NO synthase-deficient mice showed enhanced basal TGF-beta1 and collagen type I expression; endothelial cells from these animals showed increased Smad phosphorylation and transcriptional activity. Proteasome inhibitors prevented the inhibitory effect of NO on TGF-beta signaling. NO reduced the metabolic life of ectopically expressed Smad2 and enhanced its ubiquitination. Taken together, these results suggest that the endothelial NO/cGMP/PKG pathway interferes with TGF-beta/Smad2 signaling by directing the proteasomal degradation of activated Smad.
authors.affiliation: Departmento Fisiología, Universidad de Alcalá, Alcalá de Henares, Spain. marta.saura@uah.es
authors.forename: Marta
authors.initials: M
authors.lastname: Saura
authors.forename: Carlos
authors.initials: C
authors.lastname: Zaragoza
authors.forename: Beatrice
authors.initials: B
authors.lastname: Herranz
authors.forename: Mercedes
authors.initials: M
authors.lastname: Griera
authors.forename: Luisa
authors.initials: L
authors.lastname: Diez-Marqués
authors.forename: Diego
authors.initials: D
authors.lastname: Rodriguez-Puyol
authors.forename: Manuel
authors.initials: M
authors.lastname: Rodriguez-Puyol
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000502:physiology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000502:physiology; D042783:Endothelial Cells / Q000502:physiology*; D006801:Humans; D051379:Mice; D009569:Nitric Oxide / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D051899:Smad2 Protein / Q000502:physiology*; D051900:Smad3 Protein / Q000502:physiology; D015533:Transcriptional Activation; D016212:Transforming Growth Factor beta / Q000502:physiology*
chemical_list: D051899:Smad2 Protein; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta; D009569:Nitric Oxide; D017869:Cyclic GMP-Dependent Protein Kinases; D046988:Proteasome Endopeptidase Complex; D006152:Cyclic GMP