Trophoblast stem cell maintenance by fibroblast growth factor 4 requires MEKK4 activation of Jun N-terminal kinase

Mol Cell Biol. 2009 May;29(10):2748-61. doi: 10.1128/MCB.01391-08. Epub 2009 Mar 16.

Abstract

Trophoblast differentiation during placentation involves an epithelial-mesenchymal transition (EMT) with loss of E-cadherin and gain of trophoblast invasiveness. Mice harboring a point mutation that renders inactive the mitogen-activated protein kinase kinase kinase MEKK4 exhibit dysregulated placental development with increased trophoblast invasion. Isolated MEKK4 kinase-inactive trophoblast stem (TS) cells cultured under undifferentiating, self-renewing conditions in the presence of fibroblast growth factor 4 (FGF4) display increased expression of Slug, Twist, and matrix metalloproteinase 2 (MMP2), loss of E-cadherin, and hyperinvasion of extracellular matrix, each a hallmark of EMT. MEKK4 kinase-inactive TS cells show a preferential differentiation to Tpbp alpha- and Gcm1-positive trophoblasts, which are indicative of spongiotrophoblast and syncytiotrophoblast differentiation, respectively. FGF4-stimulated Jun N-terminal kinase (JNK) and p38 activity is markedly reduced in MEKK4 kinase-inactive TS cells. Chemical inhibition of JNK in wild-type TS cells induced a similar EMT response as loss of MEKK4 kinase activity, including inhibition of E-cadherin expression and increased expression of Slug, MMP2, Tpbp alpha, and Gcm1. Chromatin immunoprecipitation analyses revealed changes in AP-1 composition with increased Fra-2 and decreased Fra-1 and JunB binding to the regulatory regions of Gcm1 and MMP2 genes in MEKK4 kinase-inactive TS cells. Our results define MEKK4 as a signaling hub for FGF4 activation of JNK that is required for maintenance of TS cells in an undifferentiated state.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Activins / genetics
  • Activins / metabolism
  • Animals
  • Cadherins / metabolism
  • Cathepsins / genetics
  • Cathepsins / metabolism
  • Cell Differentiation / physiology
  • Cells, Cultured
  • DNA-Binding Proteins
  • Embryo, Mammalian* / cytology
  • Embryo, Mammalian* / physiology
  • Enzyme Activation
  • Extracellular Matrix
  • Female
  • Fibroblast Growth Factor 4 / genetics
  • Fibroblast Growth Factor 4 / metabolism*
  • JNK Mitogen-Activated Protein Kinases / genetics
  • JNK Mitogen-Activated Protein Kinases / metabolism*
  • MAP Kinase Kinase Kinase 4 / genetics
  • MAP Kinase Kinase Kinase 4 / metabolism*
  • Matrix Metalloproteinase 2 / genetics
  • Matrix Metalloproteinase 2 / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neuropeptides / genetics
  • Neuropeptides / metabolism
  • Placenta / cytology
  • Pregnancy
  • Signal Transduction / physiology
  • Snail Family Transcription Factors
  • Stem Cells / cytology
  • Stem Cells / physiology*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / metabolism
  • Trophoblasts / cytology*
  • Trophoblasts / physiology
  • Twist-Related Protein 1 / genetics
  • Twist-Related Protein 1 / metabolism
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Cadherins
  • DNA-Binding Proteins
  • Fibroblast Growth Factor 4
  • Gcm1 protein, mouse
  • Neuropeptides
  • Snai2 protein, mouse
  • Snail Family Transcription Factors
  • Transcription Factors
  • Transforming Growth Factor beta
  • Twist-Related Protein 1
  • Activins
  • JNK Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase Kinase 4
  • Cathepsins
  • cathepsin S
  • Matrix Metalloproteinase 2