Regulation of Beta-Amyloid Precursor Protein Expression by Brain-Derived Neurotrophic Factor Involves Activation of Both the Ras and Phosphatidylinositide 3-kinase Signalling Pathways

J Neurochem. 2004 Feb;88(4):1010-8. doi: 10.1046/j.1471-4159.2003.02226.x.

Abstract

Brain-derived neurotrophic factor (BDNF) stimulates beta-amyloid precursor protein (APP) promoter activity by a Ras-dependent mechanism in TrkB-expressing SH-SY5Y cells. To determine the signalling pathways involved in the BDNF-induced response, we have analysed the ability of TrkB mutated forms to mediate promoter stimulation. Brain-derived neurotrophic factor causes a significant induction of promoter activity and mutation K540R in the active site of TrkB completely abolishes the neurotrophin-induced response. A substitution of the Y484 residue by phenylalanine, which blocks binding of Shc, reduces the activation of APP promoter by BDNF by approximately 50% whereas mutation Y785P, which blocks binding of phospholipase C gamma, does not affect the response. In addition, the phosphatidylinositide 3-kinase (PI3K)-specific inhibitors wortmannin and LY294002 reduced BDNF-induced activation. In agreement with a participation of both Ras/MAPK- and PI3K/Akt-mediated mechanisms, transient expression of constitutive active forms of Ras, PI3K and other components of both signalling pathways led to a significant increase of APP promoter activity. Furthermore, the stimulation of the APP promoter by BDNF was completely precluded by expression of dominant-negative forms of Ras and PI3K effectors. Taken together, our results suggest that simultaneous activation of at least two signalling pathways, Ras/MAPK and PI3K/Akt, is necessary to mediate a full activation of the APP promoter by BDNF.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid beta-Protein Precursor / metabolism*
  • Blotting, Western / methods
  • Brain-Derived Neurotrophic Factor / physiology*
  • Cell Line, Tumor
  • Chloramphenicol O-Acetyltransferase / metabolism
  • Drug Interactions
  • Enzyme Inhibitors / pharmacology
  • Gene Expression Regulation / drug effects
  • Humans
  • Mutation / genetics
  • Neuroblastoma
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Precipitin Tests / methods
  • Promoter Regions, Genetic
  • Receptor, trkB / genetics
  • Receptor, trkB / metabolism
  • Signal Transduction / physiology*
  • Transfection
  • ras Proteins / metabolism*

Substances

  • Amyloid beta-Protein Precursor
  • Brain-Derived Neurotrophic Factor
  • Enzyme Inhibitors
  • Chloramphenicol O-Acetyltransferase
  • Phosphatidylinositol 3-Kinases
  • Receptor, trkB
  • ras Proteins