TGF-β signaling is required for maintenance of retinal ganglion cell differentiation and survival

Neuroscience. 2011 Aug 25;189:123-31. doi: 10.1016/j.neuroscience.2011.05.020. Epub 2011 May 27.

Abstract

Purpose: To determine the role of TGF-β1 in the maintenance of retinal ganglion cell line (RGC-5) differentiation and integrity.

Methods: RGC-5 cells were differentiated in media conditioned by human non-pigmented ciliary epithelial cells (HNPE) for 4 days before treatment with TGF-β1 for 24 h. Cells were examined for morphological changes and harvested for western blot and real-time PCR analysis. For study of apoptosis, differentiated RGC-5 cells were grown in serum-free medium for 24 h in the presence or absence of TGF-β1 and collected for Annexin V/Propidium iodide FACs analysis. The role of MAPK pathways in TGF-β1-dependent signaling was determined by treatment with specific inhibitors of ERK, JNK and p38.

Results: Differentiation of RGC-5 cells in HNPE-conditioned media (CM) increased the neural cell markers, Brn-3c, NF-160, Thy1.2, Tau and PGP9.5. Treatment with TGF-β1 significantly increased the length of neurites extended by differentiated RGC-5s, concomitant with increased expression of NF-160 and PGP9.5, but not Brn-3c, Thy1.2 or Tau. TGF-β1 also decreased RGC-5 cell apoptosis in serum-free medium. p38 phosphorylation, but not smad2/3, JNK or ERK phosphorylation, was increased in TGF-β1 treated cells. Specific inhibition of p38 signaling reversed TGF-β1 induced neurite growth.

Conclusions: These findings demonstrate the induction of RGC-5 cell differentiation by HNPE-derived CM and illustrate a role for TGF-β1 in maintaining RGC-5 cell survival and promoting neurite outgrowth through p38 MAPK.

Publication types

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

MeSH terms

  • Animals
  • Apoptosis
  • Biomarkers / metabolism
  • Cell Differentiation
  • Cell Line
  • Cell Survival
  • Cilia / metabolism
  • Culture Media, Conditioned
  • Epithelial Cells / metabolism
  • Humans
  • Intracellular Space / metabolism
  • MAP Kinase Signaling System
  • Neurites / physiology
  • Rats
  • Retinal Ganglion Cells / cytology
  • Retinal Ganglion Cells / metabolism*
  • Signal Transduction
  • Smad Proteins / physiology
  • Transforming Growth Factor beta1 / pharmacology
  • Transforming Growth Factor beta1 / physiology*

Substances

  • Biomarkers
  • Culture Media, Conditioned
  • Smad Proteins
  • Transforming Growth Factor beta1