Antiapoptotic role of the cellular repressor of E1A-stimulated genes (CREG) in retinal photoreceptor cells in a rat model of light-induced retinal injury

Abstract Objective Light injury-induced apoptosis of retinal photoreceptor cells can lead to vision loss. The mechanism underlying such injury remains unclear, and there are no effective therapies at present. The aim of this study was to examine the potential antiapoptotic role of the cellular repressor of E1A-stimulated genes (CREG) in retinal cells in a rat model of light-induced retinal damage. Methods CREG proteins were injected into the vitreous space of rats in which light retinal injury was induced. An equal volume of PBS was injected into the vitreous space of a control group. Retinas were collected for H&E staining and Western blotting analysis 1, 3, and 7 days later. Inhibitors or agonist for P38, JNK, and AKT were injected into the vitreous space to verify CREG function. Results In rats with light-induced retinal injury, the CREG treatment inhibited the expression of apoptosis-related proteins caspase-3, caspase-8, and caspase-9 and signaling proteins phosphorylated ERK (P-ERK), phosphorylated JNK (P-JNK), phosphorylated P38 (P-P38), and phosphorylated AKT (P-AKT). An inhibitor of PI3K-AKT and an agonists of P38 and JNK abrogated the inhibitory effect of CREG on caspase-3 expression. Conclusion CREG protected retinal cells against apoptosis by inhibiting P38/MAPK and JNK/MAPK signaling pathways and activating the PI3K-AKT signaling pathway.