Increased OPA1 Expression Blocks RGC Loss and Apoptotic Cell Death in Glaucomatous Retina

Abstract

Purpose: : To determine whether OPA1 expression changes in the retina of a mouse model of glaucoma and whether increased OPA1 expression can block the RGC loss and retinal apoptosis that would otherwise occur in these glaucomatous DBA/2J mice.

Methods: : IOP in the eye of DBA/2J mice was measured and OPA1 mRNA in the retina was measured by Taqman qPCR. The cellular distribution of OPA1 protein was assessed by immunocytochemistry and Western blot. Following intravitreal injection of recombinant AAV2-OPA1 construct, RGC survival was counted by retrograde labeling of RGCs by FluoroGold. Apoptotic cell death was assessed by TUNEL staining.

Results: : OPA1 mRNA was significantly decreased in the retinas of 9 month-old glaucomatous DBA/2J mice. The OPA1 antibody recognized at least five major OPA1 isoforms in the retinas of DBA/2J mice. The relative expression of the 75 kDa OPA1 isoform was increased but other OPA1 isoforms were not altered in the retinas of 9 month-old glaucomatous DBA/2J mice compared with 3 month-old DBA/2J mice. The distribution of OPA1 immunoreactivity was not changed in the retina of 9 month-old glaucomatous DBA/2J mice compared with 3 month-old DBA/2J mice. Quantitative analysis showed a significant increase of RGC survival in 9 month-old glaucomatous DBA/2J mice that received AAV2-OPA1 transfectant. Further, the AAV2-OPA1 transfectant blocked apoptotic cell death in the GCL.

Conclusions: : Our findings indicate that increased OPA1 expression protects against RGC death in a mouse model of glaucoma. Based on this observation, we propose that reduction of OPA1 expression is key in a distinct mitochondria-mediated cell death pathway in glaucomatous retina.

Keywords: mitochondria • adenovirus • retinal degenerations: cell biology