Smad2 is essential for maintenance of the human and mouse primed pluripotent stem cell state

J Biol Chem. 2013 Jun 21;288(25):18546-60. doi: 10.1074/jbc.M112.446591. Epub 2013 May 6.


Human embryonic stem cells and mouse epiblast stem cells represent a primed pluripotent stem cell state that requires TGF-β/activin signaling. TGF-β and/or activin are commonly thought to regulate transcription through both Smad2 and Smad3. However, the different contributions of these two Smads to primed pluripotency and the downstream events that they may regulate remain poorly understood. We addressed the individual roles of Smad2 and Smad3 in the maintenance of primed pluripotency. We found that Smad2, but not Smad3, is required to maintain the undifferentiated pluripotent state. We defined a Smad2 regulatory circuit in human embryonic stem cells and mouse epiblast stem cells, in which Smad2 acts through binding to regulatory promoter sequences to activate Nanog expression while in parallel repressing autocrine bone morphogenetic protein signaling. Increased autocrine bone morphogenetic protein signaling caused by Smad2 down-regulation leads to cell differentiation toward the trophectoderm, mesoderm, and germ cell lineages. Additionally, induction of Cdx2 expression, as a result of decreased Smad2 expression, leads to repression of Oct4 expression, which, together with the decreased Nanog expression, accelerates the loss of pluripotency. These findings reveal that Smad2 is a unique integrator of transcription and signaling events and is essential for the maintenance of the mouse and human primed pluripotent stem cell state.

Keywords: Bone Morphogenetic Protein (BMP); Cell Differentiation; Nanog; Pluripotency; Smad Transcription Factor; Stem Cells; Transforming Growth Factor β (TGFβ).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Morphogenetic Proteins / genetics
  • Bone Morphogenetic Proteins / metabolism
  • CDX2 Transcription Factor
  • Cell Differentiation / genetics
  • Cells, Cultured
  • Embryonic Stem Cells / cytology
  • Embryonic Stem Cells / metabolism*
  • Germ Layers / cytology
  • Germ Layers / metabolism*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism
  • Humans
  • Immunoblotting
  • Mice
  • Mice, 129 Strain
  • Microscopy, Fluorescence
  • Nanog Homeobox Protein
  • Octamer Transcription Factor-3 / genetics
  • Octamer Transcription Factor-3 / metabolism
  • Pluripotent Stem Cells / cytology
  • Pluripotent Stem Cells / metabolism*
  • RNA Interference
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / genetics
  • Smad2 Protein / genetics
  • Smad2 Protein / metabolism*
  • Smad3 Protein / genetics
  • Smad3 Protein / metabolism
  • Transcription, Genetic
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / metabolism


  • Bone Morphogenetic Proteins
  • CDX2 Transcription Factor
  • CDX2 protein, human
  • Homeodomain Proteins
  • NANOG protein, human
  • Nanog Homeobox Protein
  • Octamer Transcription Factor-3
  • POU5F1 protein, human
  • Smad2 Protein
  • Smad3 Protein
  • Transforming Growth Factor beta