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D. R. Daudt, III, T. Yorio; FK506 Binding Protein 51 (FKBP51) Mediated Neuroprotection Against Glutamate Excitotoxicity in 661w and HT22 Cell Culture. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3699.
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© ARVO (1962-2015); The Authors (2016-present)
Glaucoma is a progressive optic neuropathy characterized by loss of retinal ganglion cells (RGC) and optic nerve degradation. Existing treatments focus on lowering intraocular pressure (IOP); however, vision loss may still progress. Neuroprotectant drugs are useful as an adjunct approach in preventing further loss of RGCs; though, candidate genes are lacking. FK506, a widely used immunosuppressant drug, has profound neuroprotective and neuroregenerative properties throughout the central nervous system, including the eye. FK506 achieves these properties through interaction with FK506 Binding Proteins (FKBP), including FKBP51. Currently, we investigated FKBP51’s neuroprotective properties in two neuronal cell lines.
661w cells were treated with various concentrations of FK506 and analyzed through western blot analysis to determine changes in protein levels of FKBP51, NFΚB, and activated NFΚB. Additionally, 661w and HT22 cell cultures were either stably transfected with FKBP51 overexpression vectors or treated with FKBP51 targeted siRNA and then challenged with glutamate-induced neurotoxicity. Cell death and apoptosis were measured through calcein-AM/propidium iodide cell-surivival assay, caspase 3 dectection kit, and activated BAX protein levels. Furthermore, NFΚB and activated NFΚB were analyzed as a factor of FKBP51 protein levels for each condition.
FK506 increased FKBP51 protein levels in a stepwise manner. FK506 also increased NFΚB protein levels; however, it was difficult to determine activated NFΚB protein levels. The 661w and HT22 cell cultures, stably transfected cells overexpressing FKBP51 and FKBP51 targeted siRNA caused changes to protein levels and cell viability.
This data provides strong evidence that FKBP51 promotes anti-apoptotic action in neuronal cell cultures when challenged with glutamate-induced neurotoxicity. Additionally, it suggests a possible neuroprotective mechanism of FKBP51 through NFΚB.
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