Ecel1 knockdown with an AAV2-mediated CRISPR/Cas9 system promotes optic nerve damage-induced RGC death in the mouse retina

PURPOSE. To assess the therapeutic potential of endothelin-converting enzyme-like 1 (Ecel1) in a mouse model of optic nerve crush. METHODS. Ecel1 expression was evaluated with real time quantitative (qRT)-PCR, Western blotting, and immunohistochemistry in mouse retinas after optic nerve crush. Vinblastine administration to the optic nerve and the intravitreal injection of N-methyl-d-aspartate (NMDA) were used to assess Ecel1 gene expression. Ecel1 was deleted with an adeno-associated viral (AAV) clustered regulatory interspaced short palindromic repeat (CRISPR)/ Cas9 system, and retinal ganglion cell (RGC) survival was investigated with retrograde labeling, qRT-PCR, and visual evoked potential. RESULTS. Optic nerve crush induced Ecel1 expression specifically in the RGCs, peaking on day 4 after optic nerve crush. Ecel1 gene expression was induced by the vinblastine-induced inhibition of axonal flow, but not by NMDA-induced excitotoxicity, even though both are triggers of RGC death. Knockdown of Ecel1 promoted the loss of RGCs after optic nerve crush. CONCLUSIONS. Our data suggest that Ecel1 induction is part of the retinal neuroprotective response to axonal injury in mice. These findings might provide insight into novel therapeutic targets for the attenuation of RGC damage, such as occurs in traumatic optic neuropathy.