RGC Neuroprotection by Manipulating ER Stress Signaling Molecules

Abstract

Purpose: To explore the therapeutic potential of ER stress modulation in optic nerve (ON) injury mouse model.

Methods: Adeno-associated virus (AAV)-mediated RNA interference was employed to suppress pro-apoptotic ER stress molecule CCAAT/enhancer binding protein homologous protein (CHOP) in RGCs of C57BL/6 mice. The phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) induces CHOP expression downstream of ER stress. By overexpression of un-phosphorylated eIF2α S51A mutant in transgenic mice, we blocked the eIF2α-CHOP branch of ER stress. Intraorbital ON crush (ONC) was performed in the left eyes of testing animals and the right eyes served as internal naïve controls. The survival RGCs were counted by immunostaining with Tuj1 antibody in whole-mount retinas 14 days post crush (14dpc).

Results: There was about 21.9% RGC survival in wild type (WT) control mice at 14dpc. AAV-CHOP-shRNA efficiently knocked down CHOP expression in RGCs after ONC and RGC survival was increased significantly to 31.9%. Moreover, eIF2α S51A overexpression increases RGC survival to about 57.2%.

Conclusions: Modulation of the eIF2α-CHOP branch of ER stress significantly increases RGC survival after ON injury, suggesting targeting ER stress may have considerable therapeutic neuroprotective potential in optic neuropathies including glaucoma.

Keywords: 615 neuroprotection • 629 optic nerve • 531 ganglion cells