title: Development of spontaneous neuropathy in NF-κBp50-deficient mice by calcineurin-signal involving impaired NF-κB activation.
abstract: OBJECTIVE
  The transcriptional regulator, nuclear factor-kappa B (NF-κB)/Rel family are involved in neuronal cell death and survival. Previously, we reported that NF-κBp50-deficient (p50-deficient) mice exhibit many features resembling human normal tension glaucoma (NTG). The developmental mechanism of human NTG is not clearly understood, and a radical curative treatment has yet to be established. Our aim is to elucidate the signal cascade which mediates the spontaneous optic neuropathy in p50-deficient mice as a model of NTG.
  
  
  METHODS
  To demonstrate the expression and activation of pro-apoptotic factors, which mediate the death of retinal ganglion cells (RGCs) in p50-deficient mice, western blot (WB) and luciferase reporter assays with retinas from p50-deficient and wild type mice, and cultured RGC-5 cells were performed. Furthermore, we tested the neuroprotective effects of chemical reagents (memantine, lomerizine, and tacrolimus) against N-methyl-D-aspartate (NMDA)-susceptible RGC damage according to in vitro experiments with RGC-5 cells. To elucidate the NF-κB-mediated death signaling, the effects of chemical reagents on spontaneous optic neuropathy were examined by histopathological studies.
  
  
  RESULTS
  WB experiments and luciferase reporter assays showed that NF-κB-inducible BCL2-associated X protein (Bax) and a pro-apoptotic factor, activated caspase 3 were expressed in the retina of p50-deficient mice as well as NMDA-treated RGC-5 cells. Further, the constitutively active cleaved forms of calcineurin (CaN), which have been reported to lead to apoptosis, were detected in the retina of p50-deficient mice as well as NMDA-treated RGC-5 cells. Pre-treatment with tacrolimus markedly protected RGC-5 cells from NMDA-induced neurotoxicity, and then both spontaneous RGC death and degenerative changes to the optic nerve in p50-deficient mice were significantly reduced by the chronic administration of tacrolimus. The experiments with cultured RGC-5 cells supported the results of histological examinations with p50-deficient mice, suggesting that CaN activation leads to NF-κB-induced Bax activation and caspase 3 activation, and mediates spontaneous optic neuropathy in p50-deficient mice.
  
  
  CONCLUSIONS
  Research findings show that the chronic administration of tacrolimus significantly reduces spontaneous optic neuropathy in p50-deficient mice. We demonstrated a potential CaN signal cascade, which spontaneously induces age-dependent RGC death and degenerative optic nerve changes in p50-deficient mice.
authors.affiliation: Department of Ophthalmology, Shinshu University Graduate School of Medicine, Nagano, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nakamura-Yanagidaira
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Kenji
authors.initials: K
authors.lastname: Sano
authors.forename: Toshinori
authors.initials: T
authors.lastname: Murata
authors.forename: Takuma
authors.initials: T
authors.lastname: Hayashi
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D019703:Calcineurin / Q000235:genetics / Q000378:metabolism*; D017930:Genes, Reporter; D006801:Humans; D058449:Intravitreal Injections; D008156:Luciferases / Q000032:analysis; D008559:Memantine / Q000494:pharmacology / Q000627:therapeutic use; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016202:N-Methylaspartate / Q000008:administration & dosage / Q000009:adverse effects; D052002:NF-kappa B p50 Subunit / Q000172:deficiency* / Q000235:genetics; D018696:Neuroprotective Agents / Q000494:pharmacology / Q000627:therapeutic use; D009900:Optic Nerve / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009901:Optic Nerve Diseases / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D010879:Piperazines / Q000494:pharmacology / Q000627:therapeutic use; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics*; D016559:Tacrolimus / Q000494:pharmacology / Q000627:therapeutic use; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D052002:NF-kappa B p50 Subunit; D018696:Neuroprotective Agents; D010879:Piperazines; D051028:bcl-2-Associated X Protein; D016202:N-Methylaspartate; C052424:lomerizine; D008156:Luciferases; D019703:Calcineurin; D008559:Memantine; D016559:Tacrolimus