title: Dominant-negative SMAD-3 interferes with transcriptional activation by multiple agonists.
abstract: Smad proteins have recently been identified as mediators of transcriptional activation by members of the transforming growth factor-beta superfamily. To determine if Smads might also be involved in inducing gene transcription in response to other agonists, expression vectors for dominant-negative Smad proteins were constructed. These plasmids were transiently cotransfected with luciferase reporter genes and the effects of various agonists on reporter gene activity evaluated in NIH 3T3 cells. Dominant-negative Smad3, but not other dominant-negative Smads, reduced stimulation of the plasminogen activator inhibitor-1 (PAI-1) and other gene promoters by phorbol ester, cAMP, and platelet-derived growth factor. Activation of the PAI-1 promoter by TGF-beta or prostaglandin F2 alpha, and transactivation by c-Jun or JunB were not inhibited by dominant-negative Smad3, supporting the specificity of this mutant. These results suggest that Smad3, like CREB-binding protein (CBP), may participate in transcriptional activation by multiple agonists.
authors.affiliation: Department of Pediatrics, Hospital for Sick Children, University of Toronto, Ontario, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Mucsi
authors.forename: H J
authors.initials: HJ
authors.lastname: Goldberg
mesh_terms: D016475:3T3 Cells; D000818:Animals; D003094:Collagen / Q000235:genetics; D017364:Collagenases / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D016762:Genes, fos; D005822:Genetic Vectors; D006801:Humans; D051379:Mice; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D051900:Smad3 Protein; D015534:Trans-Activators; D015533:Transcriptional Activation / Q000187:drug effects*; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; C497790:SMAD3 protein, human; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D015534:Trans-Activators; D003094:Collagen; D017364:Collagenases