Fibroblast growth factor 2 applied to the optic nerve after axotomy up-regulates BDNF and TrkB in ganglion cells by activating the ERK and PKA signaling pathways

J Neurochem. 2006 Jan;96(1):82-96. doi: 10.1111/j.1471-4159.2005.03510.x. Epub 2005 Nov 3.

Abstract

Application of basic fibroblast growth factor (FGF-2) to the optic nerve after axotomy promotes the survival of retinal ganglion cells (RGCs) in the frog, Rana pipiens. Here we investigate the effects of FGF-2 treatment upon the synthesis of brain-derived neurotrophic factor (BDNF) and its receptor, tyrosine receptor kinase B (TrkB). Axotomy alone increased the amounts of BDNF and TrkB mRNA in RGCs after 1 week and 48 h, respectively; FGF-2 treatment to the nerve accelerated and increased this up-regulation of both. FGF-2 also increased the amounts of phosphorylated cAMP response element binding protein (pCREB) in the retina. Blocking extracellular-regulated kinase (ERK) activation with PD98059 or U0126 prevented the FGF-2-induced up-regulation of BDNF transcription but had no effect on TrkB. However, blocking protein kinase A (PKA) with H89 or Rp-8-Cl-cAMPS reduced the up-regulation of both BDNF and TrkB, and reduced pCREB. In addition, H89 inhibited ERK activation, indicating cross-talk between the pathways. Finally, axonal application of blocking antibody against the FGF receptor 1 (FGFR1) prevented the FGF-2-induced up-regulation of BDNF and TrkB. Our results suggest that FGF-2 acts on RGCs via FGFR1, activating the ERK pathway and CREB to increase BDNF synthesis, and PKA and CREB to increase TrkB synthesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Axotomy
  • Blotting, Western
  • Brain-Derived Neurotrophic Factor / biosynthesis*
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
  • Cyclic AMP-Dependent Protein Kinases / physiology*
  • DNA, Complementary / biosynthesis
  • DNA, Complementary / genetics
  • Enzyme Activation / drug effects
  • Exons / genetics
  • Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors
  • Extracellular Signal-Regulated MAP Kinases / physiology*
  • Fibroblast Growth Factor 2 / pharmacology*
  • Immunohistochemistry
  • In Situ Hybridization
  • Mitogen-Activated Protein Kinases / physiology
  • Optic Nerve / drug effects*
  • Rana pipiens
  • Receptor, trkB / biosynthesis*
  • Retinal Ganglion Cells / drug effects
  • Retinal Ganglion Cells / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / drug effects*
  • Signal Transduction / physiology
  • Up-Regulation / drug effects

Substances

  • Brain-Derived Neurotrophic Factor
  • Cyclic AMP Response Element-Binding Protein
  • DNA, Complementary
  • Fibroblast Growth Factor 2
  • Receptor, trkB
  • Cyclic AMP-Dependent Protein Kinases
  • Extracellular Signal-Regulated MAP Kinases
  • Mitogen-Activated Protein Kinases