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Calcium/calmodulin-dependent protein kinase II regulates the phosphorylation of CREB in NMDA-induced retinal

Hiroyuki Takeda1, Yasushi Kitaoka, Yasuhiro Hayashi

  • 1Department of Ophthalmology, St Marianna University School of Medicine, Kawasaki-Shi, Kanagawa, Japan.

Brain Research
|October 27, 2007
PubMed

Insights

The phosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII) and cyclic AMP-response element binding protein (CREB) may protect retinal ganglion cells from NMDA-induced neurotoxicity. Blocking these pathways worsened cell loss, suggesting a neuroprotective role.

Area of Science:

  • Neuroscience
  • Ophthalmology
  • Molecular Biology

Background:

  • N-methyl-d-aspartate (NMDA) receptor activation can lead to excitotoxicity in retinal ganglion cells (RGCs).
  • The roles of calcium/calmodulin-dependent protein kinase II (CaMKII) and cyclic AMP-response element binding protein (CREB) phosphorylation in NMDA-induced RGCs neurotoxicity are not fully understood.

Purpose of the Study:

  • To investigate the involvement of CaMKII and CREB phosphorylation in NMDA-induced retinal neurotoxicity.
  • To determine if CaMKII activation regulates CREB phosphorylation in this context.
  • To elucidate the neuroprotective potential of CaMKII and CREB phosphorylation against NMDA excitotoxicity.

Main Methods:

  • Western blot analysis to quantify protein levels of phosphorylated CaMKII (p-CaMKII) and phosphorylated CREB (p-CREB).
  • Immunohistochemistry to assess the localization of p-CaMKII in retinal tissue.
  • Small interfering RNA (siRNA) targeting CaMKII and CRE decoy oligonucleotides were used to inhibit specific pathways.
  • Morphometric analysis of neurotracer retrograde labeling and Thy-1-positive cells to quantify RGC loss.

Main Results:

  • NMDA injection led to early elevation of p-CaMKII followed by p-CREB.
  • p-CaMKII was found in Thy-1-positive RGCs after NMDA exposure.
  • CaMKII siRNA significantly inhibited both p-CaMKII and p-CREB increases and accelerated RGC loss.
  • Inhibition of CREB binding exacerbated NMDA-induced RGC loss.

Conclusions:

  • CaMKII activation appears to regulate CREB phosphorylation in the context of NMDA-induced retinal neurotoxicity.
  • Transient phosphorylation of CaMKII and CREB may represent a neuroprotective mechanism against NMDA excitotoxicity.
  • Targeting CaMKII and CREB pathways could offer therapeutic strategies for retinal neurodegenerative diseases.

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