Regulation of SMAD2 Signaling by SMP1 Phosphatase

Summary

Principal Investigator: X Lin
Abstract: Loss of TGF-beta growth factor-induced cell cycle arrest is a hallmark in cancers. Our long-term objective of this application is to understand the fundamental processes controlling cell cycle progression and cell differentiation in normal cells and to elucidate the functions of dysregulated TGF-beta signal transduction as a causal factor in tumor pathogenesis. One of the most critical events in activation of TGF-beta signal transduction pathway is the phosphorylation of transcription factor SMADs by cell surface TGF-beta receptors. While phosphorylated SMADs directly activate the gene responses in the nucleus, hypothetical protein phosphatases are anticipated to dephosphorylate phospho-SMADs and consequently shut down TGF-beta signaling. Despite supporting data for the existence of SMAD phosphatases (SMP), the identity of SMPC(s) remains vague. Therefore, our short-term strategy for this proposal is to identify such phosphatases and investigate the regulation of SMADs by (de)phosphorylation. Our preliminary studies have identified a phosphatase designated SMP1 that can interact with and dephosphorylate SMAD2. These data lead us to hypothesize that SMP1 acts as a bonafide phosphatase for tumor suppressor SMAD2 and shuts down TGF-beta signaling. Thus, it is significantly important to investigate the physiological roles of SMP1 in the regulation of tumor suppressing functions of TGF-beta signaling. We propose three specific aims to test the hypothesis. Aim 1: The molecular mechanisms for SMP1-mediated SMAD2 dephosphorylation will be investigated by further characterizing the phosphatase activity of SMP1, examining the SMP1-SMAD2 complex interaction and determining the structural features required for SMP1- mediated SMAD2 dephosphorylation. Aim 2: We will determine the physiological roles of SMP1 in TGF-beta responses such as TGF-beta-induced cell cycle arrest in mammalian cells and tissue differentiation during Xenopus development. Aim 3: We will examine the regulation of SMP1-mediated SMAD2 dephosphorylation in breast cells and cancers. The experimental design to carry out the proposed research will take on a wide range of approaches that cross the multiple disciplines of biology to address fundamental questions in normal cell functions and cancer development. It is expected that the results obtained from this project will help to establish a working theory for how SMAD2 is regulated and provide insights into the mechanisms of TGF-beta resistance and of SMAD actions in malignant transformation and progression of human cancers. Lay description: We propose a research plan to understand how TGF-beta and related growth factors regulate cell functions in normal versus cancer cells. The results will be pertinent towards development for a foundation for the rational design of novel therapeutic approaches for prevention and treatment of human cancers and other diseases.
Funding Period: 2005-09-30 - 2010-07-31
more information: NIH RePORT

Top Publications

  1. ncbi Smad7-induced beta-catenin degradation alters epidermal appendage development
    Gangwen Han
    Department of Otolaryngology, Oregon Health and Science University, Portland, 97239, USA
    Dev Cell 11:301-12. 2006
  2. ncbi Protein phosphatase 4 cooperates with Smads to promote BMP signaling in dorsoventral patterning of zebrafish embryos
    Shunji Jia
    State Key Laboratory of Biomembrane and Membrane Engineering, Tsinghua Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
    Dev Cell 22:1065-78. 2012
  3. pmc Coupling of dephosphorylation and nuclear export of Smads in TGF-beta signaling
    Fangyan Dai
    Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
    Methods Mol Biol 647:125-37. 2010
  4. pmc Phospho-control of TGF-beta superfamily signaling
    Katharine H Wrighton
    Michael E DeBakey Department of Surgery, Department of Molecular and Cellular Biology and Dan L Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
    Cell Res 19:8-20. 2009
  5. pmc Transforming Growth Factor {beta} Can Stimulate Smad1 Phosphorylation Independently of Bone Morphogenic Protein Receptors
    Katharine H Wrighton
    Michael E DeBakey Department of Surgery and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
    J Biol Chem 284:9755-63. 2009
  6. pmc Smad3 differentially regulates the induction of regulatory and inflammatory T cell differentiation
    Gustavo J Martinez
    Department of Immunology, M D Anderson Cancer Center, Houston, Texas 77054, USA
    J Biol Chem 284:35283-6. 2009
  7. ncbi Smad3 mediates immediate early induction of Id1 by TGF-beta
    Yao Yun Liang
    Michael E DeBakey Department of Surgery, Baylor College of Medicine, BCM 390, Research Tower, Room R711, One Baylor Plaza, Houston, TX 77030, USA
    Cell Res 19:140-8. 2009
  8. pmc Nuclear export of Smad2 and Smad3 by RanBP3 facilitates termination of TGF-beta signaling
    Fangyan Dai
    Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
    Dev Cell 16:345-57. 2009
  9. ncbi BCL6 represses Smad signaling in transforming growth factor-beta resistance
    Degang Wang
    Michael E DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas 77030, USA
    Cancer Res 68:783-9. 2008
  10. pmc To (TGF)beta or not to (TGF)beta: fine-tuning of Smad signaling via post-translational modifications
    Katharine H Wrighton
    Michael E DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
    Cell Signal 20:1579-91. 2008

Detail Information

Publications18

  1. ncbi Smad7-induced beta-catenin degradation alters epidermal appendage development
    Gangwen Han
    Department of Otolaryngology, Oregon Health and Science University, Portland, 97239, USA
    Dev Cell 11:301-12. 2006
    ..Our data reveal a mechanism for Smad7 in antagonizing Wnt/beta-catenin signaling, thereby shifting the skin differentiation program from forming hair follicles to sebaceous glands...
  2. ncbi Protein phosphatase 4 cooperates with Smads to promote BMP signaling in dorsoventral patterning of zebrafish embryos
    Shunji Jia
    State Key Laboratory of Biomembrane and Membrane Engineering, Tsinghua Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
    Dev Cell 22:1065-78. 2012
    ..We conclude that Ppp4c is a critical positive regulator of BMP/Smad signaling during embryonic dorsoventral pattern formation in zebrafish...
  3. pmc Coupling of dephosphorylation and nuclear export of Smads in TGF-beta signaling
    Fangyan Dai
    Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
    Methods Mol Biol 647:125-37. 2010
    ..The second step involves nuclear export of dephosphorylated Smad2/3 with the aid of nuclear protein RanBP3 to terminate Smad signaling. This chapter introduces methods for examining nuclear export of Smad2/3 in TGF-beta signaling...
  4. pmc Phospho-control of TGF-beta superfamily signaling
    Katharine H Wrighton
    Michael E DeBakey Department of Surgery, Department of Molecular and Cellular Biology and Dan L Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
    Cell Res 19:8-20. 2009
    ..This article illustrates the essential roles of reversible phosphorylation in controlling the strength and duration of TGF-beta signaling and the ensuing physiological responses...
  5. pmc Transforming Growth Factor {beta} Can Stimulate Smad1 Phosphorylation Independently of Bone Morphogenic Protein Receptors
    Katharine H Wrighton
    Michael E DeBakey Department of Surgery and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
    J Biol Chem 284:9755-63. 2009
    ..Thus, TGFbeta-mediated Smad1 phosphorylation appears to occur via different receptor complexes in a cell type-specific manner...
  6. pmc Smad3 differentially regulates the induction of regulatory and inflammatory T cell differentiation
    Gustavo J Martinez
    Department of Immunology, M D Anderson Cancer Center, Houston, Texas 77054, USA
    J Biol Chem 284:35283-6. 2009
    ..These results demonstrate that Smad3 is differentially involved in the reciprocal regulatory and inflammatory T cell generation...
  7. ncbi Smad3 mediates immediate early induction of Id1 by TGF-beta
    Yao Yun Liang
    Michael E DeBakey Department of Surgery, Baylor College of Medicine, BCM 390, Research Tower, Room R711, One Baylor Plaza, Houston, TX 77030, USA
    Cell Res 19:140-8. 2009
    ..Chromatin immunoprecipitation assay confirms that Smad3 and Smad4 bind to the upstream region of the Id1 gene. Our results demonstrate that Smad3, but not Smad2, mediates TGF-beta1-dependent early transcriptional induction of Id1...
  8. pmc Nuclear export of Smad2 and Smad3 by RanBP3 facilitates termination of TGF-beta signaling
    Fangyan Dai
    Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
    Dev Cell 16:345-57. 2009
    ..In conclusion, our study supports a definitive role for RanBP3 in mediating Smad2/3 nuclear export and terminating TGF-beta signaling...
  9. ncbi BCL6 represses Smad signaling in transforming growth factor-beta resistance
    Degang Wang
    Michael E DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas 77030, USA
    Cancer Res 68:783-9. 2008
    ..This study provides strong evidence that overexpression of BCL6 contributes to TGF-beta resistance in B-cell lymphoma...
  10. pmc To (TGF)beta or not to (TGF)beta: fine-tuning of Smad signaling via post-translational modifications
    Katharine H Wrighton
    Michael E DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
    Cell Signal 20:1579-91. 2008
    ..Recent progress, discussed herein, illustrates the critical roles of Smad post-translational modifications in the cellular outcome to TGF-beta signaling...
  11. pmc Critical regulation of TGFbeta signaling by Hsp90
    Katharine H Wrighton
    Michael E DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
    Proc Natl Acad Sci U S A 105:9244-9. 2008
    ..Our data reveal an essential level of TGFbeta signaling regulation mediated by Hsp90 by its ability to chaperone TbetaRs and also implicate the use of Hsp90 inhibitors in blocking undesired activation of TGFbeta signaling in diseases...
  12. pmc Phosphatase PPM1A regulates phosphorylation of Thr-186 in the Cdk9 T-loop
    Yan Wang
    Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA
    J Biol Chem 283:33578-84. 2008
    ..PPM1B only efficiently dephosphorylated Cdk9 Thr-186 in vitro when 7SK RNA was depleted from P-TEFb. Taken together, our data indicate that PPM1A and to some extent PPM1B are important negative regulators of P-TEFb function...
  13. pmc TGFbeta1 regulation of vimentin gene expression during differentiation of the C2C12 skeletal myogenic cell line requires Smads, AP-1 and Sp1 family members
    Yongzhong Wu
    Department of Biochemistry and the Massey Cancer Center, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298 0614, USA
    Biochim Biophys Acta 1773:427-39. 2007
    ..DNA precipitation and ChIP assays suggest that c-Jun, c-Fos, Smad3 and Sp1/Sp3 interact over this region, but this interaction changes during myogenesis with TGFbeta1 induction...
  14. pmc Erbin inhibits transforming growth factor beta signaling through a novel Smad-interacting domain
    Fangyan Dai
    Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Room 137D, Houston, TX 77030, USA
    Mol Cell Biol 27:6183-94. 2007
    ..Therefore, these results define Erbin as a novel negative modulator of Smad2/Smad3 functions and expand the physiological role of Erbin to the regulation of TGFbeta signaling...
  15. ncbi Protein serine/threonine phosphatase PPM1A dephosphorylates Smad1 in the bone morphogenetic protein signaling pathway
    Xueyan Duan
    Department of Molecular and Cellular Biology, Michael E DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas 77030, USA
    J Biol Chem 281:36526-32. 2006
    ..Collectively, our study suggests that PPM1A plays an important role in controlling BMP signaling through catalyzing Smad dephosphorylation...
  16. ncbi PPM1A functions as a Smad phosphatase to terminate TGFbeta signaling
    Xia Lin
    Michael E DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
    Cell 125:915-28. 2006
    ..This work demonstrates that PPM1A/PP2Calpha, through dephosphorylation of Smad2/3, plays a critical role in terminating TGFbeta signaling...
  17. ncbi Small C-terminal domain phosphatases dephosphorylate the regulatory linker regions of Smad2 and Smad3 to enhance transforming growth factor-beta signaling
    Katharine H Wrighton
    Michael E DeBakey Department of Surgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
    J Biol Chem 281:38365-75. 2006
    ..Taken together, this work identifies the first example of a Smad2/3 linker phosphatase(s) and reveals an important new substrate for SCPs...
  18. pmc Zinc finger protein 451 is a novel Smad corepressor in transforming growth factor-β signaling
    Yili Feng
    From the Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China and
    J Biol Chem 289:2072-83. 2014
    ..Taken together, ZNF451 acts as a transcriptional corepressor for Smad3/4 and negatively regulates TGF-β signaling. ..