Abstract
Purpose :
The purpose of this research is to determine whether amplification of A-kinase anchoring protein 1 (AKAP1) protects retinal ganglion cells and their axons, and central visual pathway by preserving mitochondrial activity in a mouse model of glaucoma.
Methods :
Five-month-old pre-glaucomatous DBA/2J (D2) mice were intravitreally transduced with recombinant adeno-associated virus serotype 2 (AAV2) constructs, including AAV2-Null or AKAP1 for 5 months. Each of the 10-month-old D2 mice used in this study had a single intraocular (IOP) measurement. RGC survival and its axon preservation were assessed by cell counting using RBPMS immunohistochemistry and electron microscopy analyses. Mitochondrial dynamics and oxidative phosphorylation (OXPHOS) were measured by western blot analysis and immunohistochemistry. Preservation of the central visual pathway was assessed in the superior colliculus (SC) by cholera toxin subunit B (CTB) labeling.
Results :
Elevated IOP triggered a significant loss of AKAP1 expression in 10-month-old glaucomatous D2 retina, along with RGC loss. Based on these data, we overexpressed AKAP1 in the retina by in vivo intravitreal delivery of AAV2-AKAP1. We observed that restoring sustained AKAP1 expression significantly protected RGCs in the middle and peripheral retinas and preserved their axons in the glial lamina of glaucomatous D2 mice compared to glaucomatous Null-D2 mice. Glaucomatous Null-D2 retina showed an increase in calcineurin (CaN) and total dynamin-related protein 1 (DRP1) protein expression and a decrease in DRP1 phosphorylation at serine 637 (pDRP1 S637) and optic atrophy type 1 (OPA1) protein expression. However, administration of AAV2-AKAP1 restored the expression of these mitochondrial dynamics-regulating proteins and mitochondrial OXPHOS protein expression in the retina of glaucomatous D2 mice. In addition, AKAP1 amplification significantly promoted mitochondrial biogenesis by increasing PGC-1α and TFAM protein expression. Lastly, we observed that AKAP1 amplification restored CTB intensity in the SC of glaucomatous D2 mice compared to glaucomatous Null-D2 mice.
Conclusions :
These findings suggest that AKAP1 has a therapeutic potential to protect RGC and its axon, and preserve central visual pathway by maintaining structural and functional integrity of mitochondria against glaucomatous damage.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.