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L. Wang, G. Duncan, A. R. Prescott, I. M. Wormstone; EIF-2 Dephosphoryaltion Inhibitor, Salubrinal, Protects Human Lens Cells Against Cell Death Induced by Sigma-1 Receptor Antagonists. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3257. doi: https://doi.org/.
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It has been widely accepted that Endoplasmic Reticulum (ER) stress can induce cell death. We have previously shown that silencing or antagonising Sigma-1 receptor (Sig-1R) can inhibit human lens cell growth and induce apoptosis. The aim of this study was to test whether the inhibitor of Eukaryotic Translation Initiation Factor 2 (EIF-2α) dephosphorylation, Salubrinal is protective against ER-stress induced cell death.
Lens capsular bags were prepared and dissected from human donor eyes and used for this study together with the human lens cell line FHL124. Western blotting was used to assess phosphorylation of EIF-2α. Apoptosis was quantified using the TUNEL assay and western blotting for pro-Caspase-3 and 12. Cell growth within the capsular bags was analysed using image analysis software.
The number of apoptotic FHL 124 cells was significantly increased in the presence of 10µM BD1047, a selective Sig-1R antagonist, using the TUNEL assay. Moreover, the protein level of pro-Caspase-3 and 12 was also significantly decreased by BD1047 exposure. Interestingly, BD1047 enhanced EIF-2α phosphorylation; however the addition of 10 µM Salubrinal significantly increased phosphorylation levels even further. Exposure of FHL124 cells to Salubrinal was protective against BD1047 induced apoptosis; both TUNEL positive cells were reduced and pro-caspase 3 and 12 level remained high. The level of cell death induced on the capsular bag with 10µM BD1047 exposure was significantly reduced by the addition of 10uM Salubrinal.
This study confirms an important role of the Sig-1R in lens cell death and survival. EIF-2α appears to be an important mediator of apoptosis following Sig-1R inhibition; modulation of ER-stress mediated apoptotic pathways could provide protective benefits to lens cells in preventing cataractogenesis.
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