The Hand1, Stra13 and Gcm1 transcription factors override FGF signaling to promote terminal differentiation of trophoblast stem cells

Dev Biol. 2004 Jul 1;271(1):26-37. doi: 10.1016/j.ydbio.2004.03.029.


The trophoblast cell lineage is an interesting model system because it is composed of a limited number of cell types that are spatially patterned. Trophoblast stem (TS) cells reside within a layer called the chorion and either remain as stem cells or differentiate into spongiotrophoblast (SpT), trophoblast giant (TG) cells or syncytiotrophoblast cells (SynT) of the labyrinth. Maintenance of the TS phenotype is dependent on stimulation by FGF4, whereas differentiation and/or maintenance of the differentiated derivatives are dependent on key transcription factors: Mash2 for SpT, Hand1 for TG cells and Gcm1 for SynT cells. TS cells proliferate and retain their stem cell phenotype in culture in response to FGF4 and an additional factor(s) that can be provided by conditioned medium from embryonic fibroblast feeder cells (CM). To understand the functions of Hand1, Mash2 and Gcm1 at a cellular level, we tested the effects of their ectopic and over-expression on the ability of TS cells to either continue to proliferate or differentiate into their alternative fates. Expression of Mash2 alone had no effects on TS cell differentiation. However, Mash2-transfected cells continued to divide longer after withdrawal of FGF/CM. Hand1 promoted TGC differentiation, even in the continued presence of FGF4/CM. Stra13, another bHLH factor gene that is expressed in TG cells, also induced TG differentiation. Gcm1 induced a rapid arrest of TS proliferation but, in contrast to Hand1 and Stra13, blocked TG cell differentiation. Although Gcm1 was not sufficient to promote SynT formation, expression of an antisense Gcm1 transcript blocked SynT differentiation. These data suggest that Mash2 functions to promote transient FGF4-independent amplification of trophoblast cells that are progressing towards the SpT and TG cell phenotype. By contrast, Hand1 and Stra13 promote cell cycle exit and restrict cells towards the TG fate, whereas Gcm1 promotes cell cycle exit and restriction towards the SynT fate.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Basic Helix-Loop-Helix Transcription Factors
  • Blotting, Northern
  • Blotting, Western
  • Cell Cycle Proteins / metabolism
  • Cell Differentiation / physiology*
  • Cell Line
  • DNA, Complementary / genetics
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Densitometry
  • Fibroblast Growth Factor 4
  • Fibroblast Growth Factors / metabolism
  • Gene Expression Regulation, Developmental*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Immunohistochemistry
  • In Situ Hybridization
  • Mice
  • Neuropeptides / genetics
  • Neuropeptides / metabolism*
  • Nuclear Proteins
  • Plasmids / genetics
  • Proto-Oncogene Proteins / metabolism
  • Signal Transduction / genetics
  • Signal Transduction / physiology*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transfection
  • Trophoblasts / metabolism
  • Trophoblasts / physiology*


  • Basic Helix-Loop-Helix Transcription Factors
  • Bhlhe40 protein, mouse
  • Cell Cycle Proteins
  • DNA, Complementary
  • DNA-Binding Proteins
  • Fgf4 protein, mouse
  • Fibroblast Growth Factor 4
  • GCM1 protein, human
  • Gcm1 protein, mouse
  • Hand1 protein, mouse
  • Homeodomain Proteins
  • Neuropeptides
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • Transcription Factors
  • helix-loop-helix protein, eHAND
  • Fibroblast Growth Factors