A complex role for FGF-2 in self-renewal, survival, and adhesion of human embryonic stem cells

Stem Cells. 2009 Aug;27(8):1847-57. doi: 10.1002/stem.128.

Abstract

The transcription program that is responsible for the pluripotency of human ESCs (hESCs) is believed to be comaintained by exogenous fibroblast growth factor-2 (FGF-2), which activates FGF receptors (FGFRs) and stimulates the mitogen-activated protein kinase (MAPK) pathway. However, the same pathway is stimulated by insulin receptors, insulin-like growth factor 1 receptors, and epidermal growth factor receptors. This mechanism is further complicated by intracrine FGF signals. Thus, the molecular mechanisms by which FGF-2 promotes the undifferentiated growth of hESCs are unclear. Here we show that, in undifferentiated hESCs, exogenous FGF-2 stimulated the expression of stem cell genes while suppressing cell death and apoptosis genes. Inhibition of autocrine FGF signaling caused upregulation of differentiation-related genes and downregulation of stem cell genes. Thus, exogenous FGF-2 reinforced the pluripotency maintenance program of intracrine FGF-2 signaling. Consistent with this hypothesis, expression of endogenous FGF-2 decreased during hESC differentiation and FGF-2 knockdown-induced hESC differentiation. In addition, FGF-2 signaling via FGFR2 activated MAPK kinase/extracellular signal-regulated kinase and AKT kinases, protected hESC from stress-induced cell death, and increased hESC adhesion and cloning efficiency. This stimulation of self-renewal, cell survival, and adhesion by exogenous and endogenous FGF-2 may synergize to maintain the undifferentiated growth of hESCs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Adhesion / drug effects
  • Cell Adhesion / physiology
  • Cell Differentiation / drug effects
  • Cell Differentiation / physiology
  • Cell Growth Processes / drug effects
  • Cell Growth Processes / physiology
  • Cell Line
  • Cell Survival / drug effects
  • Cell Survival / physiology
  • Down-Regulation
  • Embryonic Stem Cells / cytology*
  • Embryonic Stem Cells / drug effects
  • Embryonic Stem Cells / metabolism
  • Enzyme Activation
  • Fibroblast Growth Factor 2 / genetics
  • Fibroblast Growth Factor 2 / metabolism*
  • Fibroblast Growth Factor 2 / pharmacology*
  • Gene Expression
  • Humans
  • Immunoblotting
  • Mitogen-Activated Protein Kinases / metabolism
  • Oncogene Protein v-akt / metabolism
  • Phosphorylation
  • Receptor, Fibroblast Growth Factor, Type 2 / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction

Substances

  • Fibroblast Growth Factor 2
  • Receptor, Fibroblast Growth Factor, Type 2
  • Oncogene Protein v-akt
  • Mitogen-Activated Protein Kinases