title: Reduced Smad3 protein expression and altered transforming growth factor-beta1-mediated signaling in cystic fibrosis epithelial cells.
abstract: Cystic fibrosis (CF) is a disease characterized by an aggressive inflammatory response in the airways. Given the antiinflammatory properties of transforming growth factor (TGF)-beta1, it was our goal to examine components of TGF-beta1-mediated signaling in both a cultured cell model and a mouse model of CF. A CF-related reduction of protein levels of the TGF-beta1 signaling molecule Smad3 was found in both of these model systems, whereas Smad4 levels were unchanged. Functional effects of reduced Smad3 expression are manifest in our cultured cell model, as reduced basal and TGF-beta1-stimulated levels of luciferase expression using the TGF-beta1-responsive reporter construct 3TP-Lux in the CF-phenotype cells compared with control cells. However, TGF-beta1-stimulated responses using the A3-Luc reporter construct were normal in both cell lines. These results suggest that select TGF-beta1-mediated signaling pathways are impaired in CF epithelial cells. This selective loss of Smad3 protein expression in CF epithelium may also influence inflammatory responses. Our data demonstrate that both CF-phenotype cells lacking Smad3 expression, and A549 cells expressing a dominant-negative Smad3, are unable to support TGF-beta1-mediated inhibition of either the interleukin (IL)-8 or the NOS2 promoter. We conclude that a CF-related reduction in Smad3 protein expression selectively alters TGF- beta1-mediated signaling in CF epithelium, potentially contributing to aggressive inflammatory responses.
authors.affiliation: Department of Pediatrics, Case Western Reserve University, Cleveland, Ohio 44106-4948, USA. tjk12@po.cwru.edu
authors.forename: T J
authors.initials: TJ
authors.lastname: Kelley
authors.forename: H L
authors.initials: HL
authors.lastname: Elmer
authors.forename: D A
authors.initials: DA
authors.lastname: Corey
mesh_terms: D000818:Animals; D002478:Cells, Cultured / Q000378:metabolism; D003550:Cystic Fibrosis / Q000378:metabolism* / Q000473:pathology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000172:deficiency / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D004790:Enzyme Induction; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D007249:Inflammation; D016209:Interleukin-8 / Q000096:biosynthesis / Q000235:genetics; D008099:Liver / Q000378:metabolism; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism; D009297:Nasal Mucosa / Q000166:cytology; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D009928:Organ Specificity; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D051899:Smad2 Protein; D051900:Smad3 Protein; D051901:Smad4 Protein; D015534:Trans-Activators / Q000096:biosynthesis* / Q000235:genetics; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000502:physiology*
chemical_list: C505032:CFTR protein, human; D004268:DNA-Binding Proteins; D016209:Interleukin-8; D016328:NF-kappa B; D011993:Recombinant Fusion Proteins; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; C497796:SMAD4 protein, human; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D008156:Luciferases; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse