Neurofibromatosis type I tumor suppressor neurofibromin regulates neuronal differentiation via its GTPase-activating protein function toward Ras

J Biol Chem. 2003 Jul 18;278(29):26958-69. doi: 10.1074/jbc.M209413200. Epub 2003 May 2.

Abstract

Neurofibromin, the neurofibromatosis type 1 (NF1) gene product, contains a central domain homologous to a family of proteins known as Ras-GTPase-activating proteins (Ras-GAPs), which function as negative regulators of Ras. The loss of neurofibromin function has been thought to be implicated in the abnormal regulation of Ras in NF1-related pathogenesis. In this study, we found a novel role of neurofibromin in neuronal differentiation in conjunction with the regulation of Ras activity via its GAP-related domain (GRD) in neuronal cells. In PC12 cells, time-dependent increases in the GAP activity of cellular neurofibromin (NF1-GAP) were detected after NGF stimulation, which were correlated with the down-regulation of Ras activity during neurite elongation. Interestingly, the NF1-GAP increase was due to the induction of alternative splicing of NF1-GRD type I triggered by the NGF-induced Ras activation. Dominant-negative (DN) forms of NF1-GRD type I significantly inhibited the neurite extension of PC12 cells via regulation of the Ras state. NF1-GRD-DN also reduced axonal and dendritic branching/extension of rat embryonic hippocampal neurons. These results demonstrate that the mutual regulation of Ras and NF1-GAP is essential for normal neuronal differentiation and that abnormal regulation in neuronal cells may be implicated in NF1-related learning and memory disturbance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing / drug effects
  • Animals
  • Base Sequence
  • Binding Sites
  • Cell Differentiation
  • DNA, Complementary / genetics
  • Epidermal Growth Factor / pharmacology
  • Humans
  • In Vitro Techniques
  • Kinetics
  • Mutagenesis, Site-Directed
  • Nerve Growth Factor / pharmacology
  • Neurofibromin 1 / genetics
  • Neurofibromin 1 / metabolism*
  • Neurons / cytology*
  • Neurons / drug effects
  • Neurons / metabolism*
  • PC12 Cells
  • Protein Structure, Tertiary
  • Rats
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • ras GTPase-Activating Proteins / chemistry
  • ras GTPase-Activating Proteins / genetics
  • ras GTPase-Activating Proteins / metabolism*

Substances

  • DNA, Complementary
  • Neurofibromin 1
  • Recombinant Proteins
  • ras GTPase-Activating Proteins
  • Epidermal Growth Factor
  • Nerve Growth Factor