TAM receptors support neural stem cell survival, proliferation and neuronal differentiation

PLoS One. 2014 Dec 16;9(12):e115140. doi: 10.1371/journal.pone.0115140. eCollection 2014.

Abstract

Tyro3, Axl and Mertk (TAM) receptor tyrosine kinases play multiple functional roles by either providing intrinsic trophic support for cell growth or regulating the expression of target genes that are important in the homeostatic regulation of immune responses. TAM receptors have been shown to regulate adult hippocampal neurogenesis by negatively regulation of glial cell activation in central nervous system (CNS). In the present study, we further demonstrated that all three TAM receptors were expressed by cultured primary neural stem cells (NSCs) and played a direct growth trophic role in NSCs proliferation, neuronal differentiation and survival. The cultured primary NSCs lacking TAM receptors exhibited slower growth, reduced proliferation and increased apoptosis as shown by decreased BrdU incorporation and increased TUNEL labeling, than those from the WT NSCs. In addition, the neuronal differentiation and maturation of the mutant NSCs were impeded, as characterized by less neuronal differentiation (β-tubulin III+) and neurite outgrowth than their WT counterparts. To elucidate the underlying mechanism that the TAM receptors play on the differentiating NSCs, we examined the expression profile of neurotrophins and their receptors by real-time qPCR on the total RNAs from hippocampus and primary NSCs; and found that the TKO NSC showed a significant reduction in the expression of both nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), but accompanied by compensational increases in the expression of the TrkA, TrkB, TrkC and p75 receptors. These results suggest that TAM receptors support NSCs survival, proliferation and differentiation by regulating expression of neurotrophins, especially the NGF.

Publication types

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

MeSH terms

  • Animals
  • Apoptosis / genetics
  • Axl Receptor Tyrosine Kinase
  • Brain-Derived Neurotrophic Factor / biosynthesis
  • Cell Proliferation
  • Cell Survival
  • Cells, Cultured
  • Hippocampus / cytology
  • Hippocampus / metabolism
  • Mice
  • Mice, Knockout
  • Nerve Growth Factors / biosynthesis
  • Neural Stem Cells / metabolism*
  • Neurogenesis / genetics*
  • Proto-Oncogene Proteins / biosynthesis
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Receptor Protein-Tyrosine Kinases / biosynthesis
  • Receptor Protein-Tyrosine Kinases / genetics
  • Receptor Protein-Tyrosine Kinases / metabolism*
  • Receptor, trkA / biosynthesis
  • Receptor, trkB / biosynthesis
  • Receptor, trkC / biosynthesis
  • Receptors, Nerve Growth Factor / biosynthesis
  • Recombinant Proteins
  • c-Mer Tyrosine Kinase

Substances

  • Brain-Derived Neurotrophic Factor
  • Nerve Growth Factors
  • Proto-Oncogene Proteins
  • Receptors, Nerve Growth Factor
  • Recombinant Proteins
  • Ngfr protein, mouse
  • tyrosine receptor kinase A Ig2
  • Mertk protein, mouse
  • Receptor Protein-Tyrosine Kinases
  • Receptor, trkA
  • Receptor, trkB
  • Receptor, trkC
  • Tyro3 protein, mouse
  • c-Mer Tyrosine Kinase
  • Axl Receptor Tyrosine Kinase
  • AXL receptor tyrosine kinase, mouse