Nuclear orphan receptor TLX induces Oct-3/4 for the survival and maintenance of adult hippocampal progenitors upon hypoxia

J Biol Chem. 2011 Mar 18;286(11):9393-404. doi: 10.1074/jbc.M110.167445. Epub 2010 Dec 6.

Abstract

Hypoxia promotes neural stem cell proliferation, the mechanism of which is poorly understood. Here, we have identified the nuclear orphan receptor TLX as a mediator for proliferation and pluripotency of neural progenitors upon hypoxia. We found an enhanced early protein expression of TLX under hypoxia potentiating sustained proliferation of neural progenitors. Moreover, TLX induction upon hypoxia in differentiating conditions leads to proliferation and a stem cell-like phenotype, along with coexpression of neural stem cell markers. Following hypoxia, TLX is recruited to the Oct-3/4 proximal promoter, augmenting the gene transcription and promoting progenitor proliferation and pluripotency. Knockdown of Oct-3/4 significantly reduced TLX-mediated proliferation, highlighting their interdependence in regulating the progenitor pool. Additionally, TLX synergizes with basic FGF to sustain cell viability upon hypoxia, since the knockdown of TLX along with the withdrawal of growth factor results in cell death. This can be attributed to the activation of Akt signaling pathway by TLX, the depletion of which results in reduced proliferation of progenitor cells. Cumulatively, the data presented here demonstrate a new role for TLX in neural stem cell proliferation and pluripotency upon hypoxia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult Stem Cells / cytology
  • Adult Stem Cells / metabolism*
  • Animals
  • Cell Hypoxia / physiology
  • Cell Proliferation
  • Cell Survival / physiology
  • Gene Expression Regulation / physiology
  • Gene Knockdown Techniques
  • Hippocampus / cytology
  • Hippocampus / metabolism*
  • Humans
  • Mice
  • Octamer Transcription Factor-3 / genetics
  • Octamer Transcription Factor-3 / metabolism*
  • Orphan Nuclear Receptors
  • Pluripotent Stem Cells / cytology
  • Pluripotent Stem Cells / metabolism*
  • Promoter Regions, Genetic / physiology
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Signal Transduction / physiology

Substances

  • NR2E1 protein, human
  • Nr2e1 protein, mouse
  • Octamer Transcription Factor-3
  • Orphan Nuclear Receptors
  • POU5F1 protein, human
  • Receptors, Cytoplasmic and Nuclear
  • Proto-Oncogene Proteins c-akt