title: Interaction with Smad4 is indispensable for suppression of BMP signaling by c-Ski.
abstract: c-Ski is a transcriptional corepressor that interacts strongly with Smad2, Smad3, and Smad4 but only weakly with Smad1 and Smad5. Through binding to Smad proteins, c-Ski suppresses signaling of transforming growth factor-beta (TGF-beta) as well as bone morphogenetic proteins (BMPs). In the present study, we found that a mutant of c-Ski, termed c-Ski (ARPG) inhibited TGF-beta/activin signaling but not BMP signaling. Selectivity was confirmed in luciferase reporter assays and by determination of cellular responses in mammalian cells (BMP-induced osteoblastic differentiation of C2C12 cells and TGF-beta-induced epithelial-to-mesenchymal transdifferentiation of NMuMG cells) and Xenopus embryos. The ARPG mutant recruited histone deacetylases 1 (HDAC1) to the Smad3-Smad4 complex but not to the Smad1/5-Smad4 complex. c-Ski (ARPG) was unable to interact with Smad4, and the selective loss of suppression of BMP signaling by c-Ski (ARPG) was attributed to the lack of Smad4 binding. We also found that c-Ski interacted with Smad3 or Smad4 without disrupting Smad3-Smad4 heteromer formation. c-Ski (ARPG) would be useful for selectively suppressing TGF-beta/activin signaling.
authors.affiliation: Department of Molecular Pathology, Graduate School of Medicine, University of Tokyo, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Takeda
authors.forename: Masafumi
authors.initials: M
authors.lastname: Mizuide
authors.forename: Masako
authors.initials: M
authors.lastname: Oka
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Watabe
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Inoue
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Toshiro
authors.initials: T
authors.lastname: Fujita
authors.forename: Takeshi
authors.initials: T
authors.lastname: Imamura
authors.forename: Kohei
authors.initials: K
authors.lastname: Miyazono
authors.forename: Keiji
authors.initials: K
authors.lastname: Miyazawa
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D019556:COS Cells; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D009154:Mutation / Q000235:genetics; D009414:Nerve Growth Factors; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D051785:Smad Proteins; D051898:Smad1 Protein; D051901:Smad4 Protein; D015534:Trans-Activators / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D014981:Xenopus / Q000196:embryology / Q000378:metabolism; D029867:Xenopus Proteins
chemical_list: D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; C497402:MXD1 protein, Xenopus; D009414:Nerve Growth Factors; D011518:Proto-Oncogene Proteins; C497399:SMAD1 protein, human; C497796:SMAD4 protein, human; D051785:Smad Proteins; D051898:Smad1 Protein; D051901:Smad4 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; C490808:smad4.1 protein, Xenopus; C117263:smad4.2 protein, Xenopus; C060614:SKI protein, human; D006655:Histone Deacetylases