A single missense mutant of Smad3 inhibits activation of both Smad2 and Smad3, and has a dominant negative effect on TGF-beta signals.
A missense mutation of Smad2 identified in cancer cells was reconstructed on the corresponding residue of Smad3. This mutant, Smad3D407E, was not phosphorylated by the constitutively active form of type I receptor for transforming growth factor-beta (TGF-beta), and inhibited the phosphorylation of co-expressed wild-type Smad2 and Smad3. This mutant also had a dominant negative effect on the growth inhibition of HaCaT cells and on the expression of p3TP-lux reporter gene induced by TGF-beta. However, it did not alter the phosphorylation of Smad1 induced by the constitutively active form of the bone morphogenetic protein type IA receptor. These findings showed that a single missense mutation in Smad3 could specifically block TGF-beta signals by preventing activation of both Smad2 and Smad3.
Goto
D
D
Department of Biochemistry, The Cancer Institute, Japanese Foundation for Cancer Research, Tokyo.
Yagi
K
K
Inoue
H
H
Iwamoto
I
I
Kawabata
M
M
Miyazono
K
K
Kato
M
M
D000595:Amino Acid Sequence; D000818:Animals; D052005:Bone Morphogenetic Protein Receptors, Type I; D019556:COS Cells; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015603:Keratinocytes; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry; D017978:Receptors, Growth Factor / Q000737:chemistry; D011993:Recombinant Fusion Proteins; D015398:Signal Transduction / Q000502:physiology*; D051899:Smad2 Protein; D051900:Smad3 Protein; D015534:Trans-Activators; D015533:Transcriptional Activation; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D004268:DNA-Binding Proteins; D017978:Receptors, Growth Factor; D011993:Recombinant Fusion Proteins; D051899:Smad2 Protein; D051900:Smad3 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D052005:Bone Morphogenetic Protein Receptors, Type I