CDR1as Deficiency Prevents Photoreceptor Degeneration by Regulating miR-7a-5p/α-syn/Parthanatos Pathway in Retinal Detachment.

Retinal detachment (RD) is the separation of the neural retina from the retinal pigment epithelium, with photoreceptor degeneration being a major cause of irreversible vision loss. Ischemia and hypoxia after RD decreased the level of miR-7a-5p (miR-7) and promoted the expression of its main target, α-synuclein (α-syn), which activated the parthanatos pathway and led to photoreceptor damage. Circular RNA CDR1as, which is an antisense transcript of cerebellar degeneration-related protein 1, functions as a "sponge" for miR-7, thereby regulating its abundance and activity. In this study, we first reported that CDR1as expression is elevated after RD. Adeno-associated virus serotype 9 vector containing the shRNA-CDR1as sequence was used to inhibit CDR1as expression via subretinal injection. Hematoxylin and eosin staining and transmission electron microscopy revealed that the morphology and outer nuclear layer thickness of the retina were preserved and photoreceptor cell death was decreased after experimental RD in mice. Mechanistically, CDR1as deficiency significantly increased the expression of miR-7, then decreased the expression of α-syn, poly (ADP-ribose) polymerase 1, apoptosis-inducing factor, and migration inhibitory factor. Furthermore, visual function was improved as shown by Morris water maze experiments in the mouse model of RD. Our findings suggest a surprisingly neuroprotective role for CDR1as deficiency, which is probably mediated by enhancing miR-7 activity and inhibiting α-syn/poly (ADP-ribose) polymerase 1/apoptosis-inducing factor pathway, thereby preventing photoreceptor degeneration.