Endogenous α-crystallin inhibits expression of caspase-3 induced by hypoxia in retinal neurons

To investigate the expression of endogenous, hypoxic stress-induced α-crystallin and caspase-3 in rat retinal neurons in vitro.

Retinal neurons were cultured from Long-Evans rats. The expression of endogenous α-crystallin was analyzed by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR). Furthermore, hypoxic exposure was performed in cultured cells, and the expression of endogenous α-crystallin and caspase-3 was assayed by Western blotting.

Positive α-crystallin staining was observed in cultured retinal neurons, and expression of endogenous α-crystallin mRNA peaked 3-5d after inoculation (P<0.05). Moreover, endogenous, hypoxic stress-induced α-crystallin expression increased gradually, peaking 6h after hypoxia. The expression was more abundant compared to the control (P<0. 01) and was associated with a decrease in caspase-3 expression (P<0. 05).

The present study demonstrates that the expression of endogenous α-crystallin in retinal neurons, especially over-expression induced by hypoxic stress, results in the down regulation of caspase-3. The data suggest that endogenous α-crystallin may act as an endogenous neuroprotective factor in retinal neurons.