Increased optic atrophy type 1 expression protects retinal ganglion cells in a mouse model of glaucoma

PURPOSE The goal of this study is to determine whether increased optic atrophy type 1 (OPA1) expression protects against retinal ganglion cell (RGC) death in glaucomatous DBA/2J mice. METHODS Intraocular pressure in DBA/2J mice was measured, and pre-glaucomatous DBA/2J mice eyes were transfected with recombinant adeno-associated virus serotype 2 (AAV2) constructs including AAV2-wild type (WT) mOPA1 for two months. Increased OPA1 expression was confirmed by western blotting and RGC survival was assessed by retrograde labeling with FluoroGold. In addition, apoptotic cell death and mitochondrial structure were determined in AAV2-WT mOPA1-transfected differentiated RGC-5 cells exposed to elevated hydrostatic pressure (30 mmHg) for three days. RESULTS WT AAV2-mOPA1 transfection significantly increased 90 kDa and 80 kDa OPA1 isoforms in the retina of glaucomatous DBA/2J mice. OPA1 immunoreactivity was increased in the inner nuclear layer, inner plexiform layer, and ganglion cell layer in nine month-old glaucomatous DBA/2J mice transfected with AAV2-WT mOPA1. Overexpression of OPA1 significantly increased RGC survival at two months after AAV2-WT mOPA1 transfection, and decreased activation of both astroglia and microglia in the retina of glaucomatous DBA/2J mice. Also, overexpression of OPA1 in differentiated RGC-5 cells resulted in less apoptotic cell death and blocked mitochondrial fission following elevated hydrostatic pressure. CONCLUSIONS OPA1 can directly modulate RGC survival, and increasing OPA1 expression may protect against RGC death in glaucomatous optic neuropathy.