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XB-ART-50133
EMBO J 1997 Sep 01;1617:5353-62. doi: 10.1093/emboj/16.17.5353.
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TGF-beta receptor-mediated signalling through Smad2, Smad3 and Smad4.

Nakao A , Imamura T , Souchelnytskyi S , Kawabata M , Ishisaki A , Oeda E , Tamaki K , Hanai J , Heldin CH , Miyazono K , ten Dijke P .


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Smad family members are newly identified essential intracellular signalling components of the transforming growth factor-beta (TGF-beta) superfamily. Smad2 and Smad3 are structurally highly similar and mediate TGF-beta signals. Smad4 is distantly related to Smads 2 and 3, and forms a heteromeric complex with Smad2 after TGF-beta or activin stimulation. Here we show that Smad2 and Smad3 interacted with the kinase-deficient TGF-beta type I receptor (TbetaR)-I after it was phosphorylated by TbetaR-II kinase. TGF-beta1 induced phosphorylation of Smad2 and Smad3 in Mv1Lu mink lung epithelial cells. Smad4 was found to be constitutively phosphorylated in Mv1Lu cells, the phosphorylation level remaining unchanged upon TGF-beta1 stimulation. Similar results were obtained using HSC4 cells, which are also growth-inhibited by TGF-beta. Smads 2 and 3 interacted with Smad4 after TbetaR activation in transfected COS cells. In addition, we observed TbetaR-activation-dependent interaction between Smad2 and Smad3. Smads 2, 3 and 4 accumulated in the nucleus upon TGF-beta1 treatment in Mv1Lu cells, and showed a synergistic effect in a transcriptional reporter assay using the TGF-beta-inducible plasminogen activator inhibitor-1 promoter. Dominant-negative Smad3 inhibited the transcriptional synergistic response by Smad2 and Smad4. These data suggest that TGF-beta induces heteromeric complexes of Smads 2, 3 and 4, and their concomitant translocation to the nucleus, which is required for efficient TGF-beta signal transduction.

???displayArticle.pubmedLink??? 9311995
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Species referenced: Xenopus
Genes referenced: kcne1 plg smad10 smad2 smad3 smad4 tgfb1
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References [+] :
Baker, A novel mesoderm inducer, Madr2, functions in the activin signal transduction pathway. 1996, Pubmed, Xenbase