Purchase this article with an account.
N. Piri, Y. Munemasa, J. M. K. Kwong, J. Caprioli; Overexpression of Alpha A and Alpha B Crystallins Promote the Survival of Retinal Ganglion Cells After Optic Nerve Transection. Invest. Ophthalmol. Vis. Sci. 2009;50(13):121.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Stress-induced crystallin expression is commonly viewed as an activation of the cell survival mechanism. We analyzed expression of alpha A and alpha B crystallins in a rat optic nerve transection (ONT) model characterized by specific retinal ganglion cell (RGC) degeneration and determined their role in RGC survival.
ONT was performed on adult male Wistar rats weighing 300-350g. Quantitative and spatial expression were examined with western blot and immunohistochemisty, respectively. Electroporation was used to deliver alpha A and alpha B expression constructs to RGCs. Cell protective effects of alpha A and alpha B overexpression after ONT was determined with RGC density analysis.
Alpha A and alpha B mRNA and protein expression in the retina was observed predominantly in the ganglion cell layer, where the majority of crystallin-positive cells were co-localized with RGCs. Crystallin expression was also present in the inner nuclear and to a lesser degree in the outer nuclear layers. Very few crystallin-positive cells were found 14 days after ONT, which leads to more than 90% of RGCs loss. Quantitative analysis showed that the expression level of the alpha A (control vs ONT, n=8, P = 0.016) and alpha B proteins (control vs ONT, n=8, P = 0.005) was reduced by approximately 1.6 fold after ONT compared to the contralateral untreated retinas. The effect of alpha A and alpha B overexpression on RGC survival was evaluated 14 days after axotomy. The numbers of surviving RGCs after alpha A and alpha B transfection were 389±57 and 353.57±60 cells/mm2, respectively, versus 198±29 cells/mm2 following transfection with the vector alone [ONT + EGFP (n=5) vs ONT + alpha A - EGFP (n=8), P = 0.003; ONT + EGFP (n=5) vs ONT + alpha B - EGFP (n=8), P = 0.003] or 206±60 cells/mm2 in non-transfected retinas [ONT (n=9) vs ONT + alpha A - EGFP (n=8), P = 0.001; ONT (n=9) vs ONT + alpha B - EGFP (n=8), P = 0.001].
The results indicate a significant neuroprotective effect of alpha-crystallins on RGCs with approximately 95% and 75% increase in the RGC survival rate mediated by alpha A and alpha B overexpression, respectively.
This PDF is available to Subscribers Only