Unique players in the BMP pathway: small C-terminal domain phosphatases dephosphorylate Smad1 to attenuate BMP signaling

Marie Knockaert, Gopal Sapkota, Claudio Alarcón, Joan Massagué, Ali H. Brivanlou

    Research output: Contribution to journalArticle

    98 Citations (Scopus)

    Abstract

    Smad transcription factors are key signal transducers for the TGF-ß/bone morphogenetic protein (BMP) family of cytokines and morphogens. C-terminal serine phosphorylation by TGF-ß and BMP membrane receptors drives Smads into the nucleus as transcriptional regulators. Dephosphorylation and recycling of activated Smads is an integral part of this process, which is critical for agonist sensing by the cell. However, the nuclear phosphatases involved have remained unknown. Here we provide functional, biochemical, and embryological evidence identifying the SCP (small C-terminal domain phosphatase) family of nuclear phosphatases as mediators of Smad1 dephosphorylation in the BMP signaling pathway in vertebrates. Xenopus SCP2/Os4 inhibits BMP activity in the presumptive ectoderm and leads to neuralization. In Xenopus embryos, SCP2/Os4 and human SCP1, 2, and 3 cause selective dephosphorylation of Smad1 compared with Smad2, inhibiting BMP- and Smad1-dependent transcription and leading to the induction of the secondary dorsal axis. In human cells, RNAi-mediated depletion of SCP1 and SCP2 increases the extent and duration of Smad1 phosphorylation in response to BMP, the transcriptional action of Smad1, and the strength of endogenous BMP gene responses. The present identification of the SCP family as Smad C-terminal phosphatases sheds light on the events that attenuate Smad signaling and reveals unexpected links to the essential phosphatases that control RNA polymerase II in eukaryotes.

    Original languageEnglish
    Pages (from-to)11940-11945
    Number of pages6
    JournalProceedings of the National Academy of Sciences of the United States of America
    Volume103
    Issue number32
    DOIs
    Publication statusPublished - 2006

    Fingerprint

    Bone Morphogenetic Proteins
    Phosphoric Monoester Hydrolases
    Xenopus
    Phosphorylation
    Bone Morphogenetic Protein Receptors
    Ectoderm
    RNA Polymerase II
    Recycling
    RNA Interference
    Eukaryota
    Transducers
    Nuclear Family
    Serine
    Vertebrates
    Transcription Factors
    Embryonic Structures
    Cytokines
    Membranes
    Genes

    Cite this

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    title = "Unique players in the BMP pathway: small C-terminal domain phosphatases dephosphorylate Smad1 to attenuate BMP signaling",
    abstract = "Smad transcription factors are key signal transducers for the TGF-{\ss}/bone morphogenetic protein (BMP) family of cytokines and morphogens. C-terminal serine phosphorylation by TGF-{\ss} and BMP membrane receptors drives Smads into the nucleus as transcriptional regulators. Dephosphorylation and recycling of activated Smads is an integral part of this process, which is critical for agonist sensing by the cell. However, the nuclear phosphatases involved have remained unknown. Here we provide functional, biochemical, and embryological evidence identifying the SCP (small C-terminal domain phosphatase) family of nuclear phosphatases as mediators of Smad1 dephosphorylation in the BMP signaling pathway in vertebrates. Xenopus SCP2/Os4 inhibits BMP activity in the presumptive ectoderm and leads to neuralization. In Xenopus embryos, SCP2/Os4 and human SCP1, 2, and 3 cause selective dephosphorylation of Smad1 compared with Smad2, inhibiting BMP- and Smad1-dependent transcription and leading to the induction of the secondary dorsal axis. In human cells, RNAi-mediated depletion of SCP1 and SCP2 increases the extent and duration of Smad1 phosphorylation in response to BMP, the transcriptional action of Smad1, and the strength of endogenous BMP gene responses. The present identification of the SCP family as Smad C-terminal phosphatases sheds light on the events that attenuate Smad signaling and reveals unexpected links to the essential phosphatases that control RNA polymerase II in eukaryotes.",
    author = "Marie Knockaert and Gopal Sapkota and Claudio Alarc{\'o}n and Joan Massagu{\'e} and Brivanlou, {Ali H.}",
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    Unique players in the BMP pathway : small C-terminal domain phosphatases dephosphorylate Smad1 to attenuate BMP signaling. / Knockaert, Marie; Sapkota, Gopal; Alarcón, Claudio; Massagué, Joan; Brivanlou, Ali H.

    In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 103, No. 32, 2006, p. 11940-11945.

    Research output: Contribution to journalArticle

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    AU - Knockaert, Marie

    AU - Sapkota, Gopal

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    AU - Massagué, Joan

    AU - Brivanlou, Ali H.

    PY - 2006

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    AB - Smad transcription factors are key signal transducers for the TGF-ß/bone morphogenetic protein (BMP) family of cytokines and morphogens. C-terminal serine phosphorylation by TGF-ß and BMP membrane receptors drives Smads into the nucleus as transcriptional regulators. Dephosphorylation and recycling of activated Smads is an integral part of this process, which is critical for agonist sensing by the cell. However, the nuclear phosphatases involved have remained unknown. Here we provide functional, biochemical, and embryological evidence identifying the SCP (small C-terminal domain phosphatase) family of nuclear phosphatases as mediators of Smad1 dephosphorylation in the BMP signaling pathway in vertebrates. Xenopus SCP2/Os4 inhibits BMP activity in the presumptive ectoderm and leads to neuralization. In Xenopus embryos, SCP2/Os4 and human SCP1, 2, and 3 cause selective dephosphorylation of Smad1 compared with Smad2, inhibiting BMP- and Smad1-dependent transcription and leading to the induction of the secondary dorsal axis. In human cells, RNAi-mediated depletion of SCP1 and SCP2 increases the extent and duration of Smad1 phosphorylation in response to BMP, the transcriptional action of Smad1, and the strength of endogenous BMP gene responses. The present identification of the SCP family as Smad C-terminal phosphatases sheds light on the events that attenuate Smad signaling and reveals unexpected links to the essential phosphatases that control RNA polymerase II in eukaryotes.

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