CNTF induces photoreceptor neuroprotection and Müller glial cell proliferation through two different signaling pathways in the adult zebrafish retina

Kassen, S.C., Thummel, R., Campochiaro, L.A., Harding, M.J., Bennett, N.A., and Hyde, D.R.
Experimental Eye Research   88(6): 1051-1064 (Journal)
Registered Authors
Harding, Molly, Kassen, Sean, Thummel, Ryan
CNTF, Stat3, light-induced retinal damage, retinal regeneration, Müller glia, neuroprotection, zebrafish, SB 203580, MAP kinase inhibitor
MeSH Terms
  • Animals
  • Apoptosis/drug effects
  • Cell Proliferation/drug effects
  • Cell Proliferation/radiation effects
  • Ciliary Neurotrophic Factor/pharmacology*
  • In Situ Nick-End Labeling
  • MAP Kinase Signaling System/physiology
  • Nerve Regeneration/drug effects
  • Nerve Regeneration/physiology
  • Neuroglia/drug effects*
  • Neuroglia/radiation effects
  • Neuroprotective Agents/pharmacology*
  • Opsins/metabolism
  • Photic Stimulation/methods
  • Photoreceptor Cells, Vertebrate/drug effects*
  • Photoreceptor Cells, Vertebrate/metabolism
  • Radiation Injuries/metabolism
  • Radiation Injuries/pathology
  • Radiation Injuries/prevention & control*
  • Retina/cytology
  • Retina/drug effects
  • Retina/radiation effects
  • Retinal Diseases/metabolism
  • Retinal Diseases/pathology
  • Retinal Diseases/prevention & control*
  • STAT3 Transcription Factor/metabolism
  • STAT3 Transcription Factor/physiology
  • Signal Transduction/drug effects
  • Stem Cells/cytology
  • Stem Cells/drug effects
  • Zebrafish
19450453 Full text @ Exp. Eye. Res.
Ciliary neurotrophic factor (CNTF) acts in several processes in the vertebrate retina, including neuroprotection of photoreceptors in the stressed adult retina and regulation of neuronal progenitor cell proliferation during retinal development. However, the signaling pathway it utilizes (Jak/Stat, MAPK, or Akt) in these processes is ambiguous. Because dark-adapted albino zebrafish exhibit light-induced rod and cone cell death and subsequently regenerate the lost photoreceptor cells, zebrafish should be a useful model to study the role of CNTF in both neuroprotection and neuronal progenitor cell proliferation. We therefore investigated the potential roles of CNTF in both the undamaged and light-damaged adult zebrafish retinas. Intraocular injection of CNTF suppressed light-induced photoreceptor cell death, which then failed to exhibit the regeneration response that is marked by proliferating Müller glia and neuronal progenitor cells. Inhibiting the MAPK signaling pathway, but neither the Stat3 nor Akt pathways, significantly reduced the CNTF-mediated neuroprotection of light-induced photoreceptor cell death. Intraocular injection of CNTF into non-light-treated (undamaged) eyes mimicked constant intense light treatment by increasing Stat3 expression in Müller glia followed by increasing the number of proliferating Müller glia and neuronal progenitors. Knockdown of Stat3 expression in the CNTF-injected non-light-treated retinas significantly reduced the number of proliferating Müller glia, while coinjection of CNTF with either MAPK or Akt inhibitors did not inhibit the CNTF-induced Müller glia proliferation. Thus, CNTF utilizes a MAPK-dependant signaling pathway in neuroprotection of light-induced photoreceptor cell death and a Stat3-dependant signaling pathway to stimulate Müller glia proliferation.
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