PhD Dissertation: İskalen Cansu OKAN
ELUCIDATING OPA1 DISEASE MODEL MECHANISMS AND
THERAPEUTIC EFFECTS OF CN03, a cGMP ANALOG,
ON RETINAL DEGENERATION
İskalen Cansu OKAN
Molecular Biology, Genetics and Bioengineering, PhD Dissertation, 2025
Thesis Jury
Asst. Prof. Dr. Cavit Ağca (Thesis Advisor)
Assoc. Prof. Dr. Med. Markus Tschopp
Asst.Prof. Dr. Stuart James Lucas
Asst.Prof. Dr. Alex Lyakhovich
Assoc. Prof. Dr. Albert Neutzner
Date & Time: 21st, July 2025 – 05.30 PM
Place: FENS G035
Zoom Link: https://sabanciuniv.zoom.us/j/
Keywords : Dominant optic atrophy, Retinal ganglion cells, Opa1 haploinsufficiency, Axonal transport, Intraocular pressure, Glaucoma, CN03 treatment, cGMP analog
Abstract
Dominant Optic Atrophy (DOA) is a hereditary optic neuropathy characterized by bilateral degeneration of retinal ganglion cells (RGCs) and their axons, most commonly due to OPA1 haploinsufficiency. The mechanisms underlying DOA disease are still not fully understood. Here, we aimed to understand the primary disease mechanism, hypothesizing that axonal transport defects should be one of the early markers of DOA due to the disruptions in mitochondrial energy metabolism and apoptotic stimulus sensitivity. We show that OPA1 haploinsufficiency impairs anterograde and retrograde axonal transport. Intravitreal injection of CTB-488 showed a delay in anterograde transport with a decreased signal in retinorecipient areas of the brain. Intracranial injection of CTB-488 confirmed a retrograde transport defect due to a decreased number of CTB-488 positive RGCs in the retina. To rescue the effects of OPA1 haploinsufficiency, CN03, a cGMP analog, which has previously been shown to delay retinal degeneration and protect photoreceptors in three distinct retinitis pigmentosa (RP) animal models has been tested. Moreover, the neuroprotective effects of LP-CN03 have not been previously tested on Aipl mutations, which will expand the potential usage on patients with AIPL mutations. To further explore this therapeutic approach, we generated an Aipl1 knockout mouse model of Leber Congenital Amaurosis type 4 (LCA4) by using CRISPR-CAS9. Our result showed that LP-CN03 in the Aipl1 knockout model resulted in significant preservation of retinal structure and function. This was supported by scotopic ERG recordings, longitudinal OCT, fundus imaging, and optomotor response testing. Additionally, ddPCR analysis confirmed the preservation of photoreceptors. These critical findings represent an advancement toward developing a treatment for patients with AIPL1-associated retinal disease.