Akt-signal integration is involved in the differentiation of embryonal carcinoma cells

PLoS One. 2013 Jun 6;8(6):e64877. doi: 10.1371/journal.pone.0064877. Print 2013.

Abstract

The mechanism by which Akt modulates stem cell homeostasis is still incompletely defined. Here we demonstrate that Akt phosphorylates special AT-rich sequences binding protein 1 (SATB1) at serine 47 and protects SATB1 from apoptotic cleavage. Meanwhile, Akt phosphorylates Oct4 at threonine 228 and Klf4 at threonine 399, and accelerates their degradation. Moreover, PI3K/Akt signaling enhances the binding of SATB1 to Sox2, thereby probably impairing the formation of Oct4/Sox2 regulatory complexes. During retinoic acid (RA)-induced differentiation of mouse F9 embryonal carcinoma cells (ECCs), the Akt activation profile as well as its substrate spectrum is strikingly correlated with the down-regulation of Oct4, Klf4 and Nanog, which suggests Akt activation is coupled to the onset of differentiation. Accordingly, Akt-mediated phosphorylation is crucial for the capability of SATB1 to repress Nanog expression and to activate transcription of Bcl2 and Nestin genes. Taken together, we conclude that Akt is involved in the differentiation of ECCs through coordinated phosphorylations of pluripotency/differentiation factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation
  • Embryonal Carcinoma Stem Cells / drug effects
  • Embryonal Carcinoma Stem Cells / metabolism*
  • Embryonal Carcinoma Stem Cells / pathology
  • Gene Expression Regulation, Neoplastic / drug effects*
  • HEK293 Cells
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism
  • Humans
  • Kruppel-Like Factor 4
  • Kruppel-Like Transcription Factors / genetics
  • Kruppel-Like Transcription Factors / metabolism
  • Matrix Attachment Region Binding Proteins / genetics
  • Matrix Attachment Region Binding Proteins / metabolism
  • Mice
  • Nanog Homeobox Protein
  • Nestin / genetics
  • Nestin / metabolism
  • Octamer Transcription Factor-3 / genetics
  • Octamer Transcription Factor-3 / metabolism
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • SOXB1 Transcription Factors / genetics
  • SOXB1 Transcription Factors / metabolism
  • Signal Transduction / drug effects*
  • Tretinoin / pharmacology

Substances

  • Homeodomain Proteins
  • KLF4 protein, human
  • Klf4 protein, mouse
  • Kruppel-Like Factor 4
  • Kruppel-Like Transcription Factors
  • Matrix Attachment Region Binding Proteins
  • Nanog Homeobox Protein
  • Nanog protein, mouse
  • Nes protein, mouse
  • Nestin
  • Octamer Transcription Factor-3
  • POU5F1 protein, human
  • Proto-Oncogene Proteins c-bcl-2
  • Recombinant Fusion Proteins
  • SATB1 protein, human
  • SOX2 protein, human
  • SOXB1 Transcription Factors
  • Tretinoin
  • Proto-Oncogene Proteins c-akt

Grants and funding

This work was supported by the National Basic Research Program of China (2011CB965203 to WD and YH); the National High Technology Research and Development Program of China (2011AA020118 to WD); and the intra-institutional funding program (2010PY05 to WD). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.