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J Mol Signal. 2007 Sep 25;2:9.

PI3 K/Akt/mTOR-mediated translational control regulates proliferation and differentiation of lineage-restricted RoSH stem cell lines.

Author information

  • 1Institute of Medical Biology, 11 Biopolis Street, Helios #02-02, Singapore 13866. saikiang.lim@imb.a-star.edu.sg.

Abstract

BACKGROUND:

We have previously derived highly similar lineage-restricted stem cell lines, RoSH and E-RoSH cell lines from mouse embryos and CD9hi SSEA-1- differentiated mouse embryonic stem cells, respectively. These cell lines are not pluripotent and differentiate readily into endothelial cells in vitro and in vivo.

RESULTS:

We investigated the signaling pathway that maintains proliferation of these cells in an undifferentiated state, and demonstrate that PI3 K/Akt/mTOR, but not Raf/MEK/Erk, signaling in these cells was active during proliferation and was downregulated during endothelial differentiation. Inhibition of PI3 K/Akt/mTOR signaling, but not Raf/MEK/Erk, reduced proliferation and induced expression of endothelial specific proteins. During differentiation or inhibition of PI3 K/Akt/mTOR signaling, cyclinD2 transcript abundance in ribosome-enriched RNA but not in total RNA was reduced with a corresponding reduction in protein level. In contrast, transcript abundance of endothelial-specific genes e.g. Kdr, Tek and Pdgfralpha in ribosome-enriched RNA fraction was not reduced and their protein levels were increased. Together these observations suggested that translational control mediated by PI3K/Akt/mTOR signaling was critical in regulating proliferation and endothelial differentiation of lineage-restricted RoSH-like stem cell lines.

CONCLUSION:

This study highlights translation regulation as a critical regulatory mechanism during proliferation and differentiation in stem cells.

PMID:
17892597
[PubMed]
PMCID:
PMC2045085
Free PMC Article
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