The deubiquitinase Otud7b suppresses cone photoreceptor degeneration in mouse models of retinal degenerative diseases
Primary and secondary cone photoreceptor cell death in retinal degenerative diseases, including age-related macular degeneration and retinitis pigmentosa, leads to severe vision impairment and blindness. Regardless of the fact that protection of cone photoreceptor cells under stress conditions, such as retinal degenerative diseases, is crucial for maintaining vision, the underlying molecular mechanisms are unclear. Here, we investigated the function of the deubiquitinase Otud7b/Cezanne in the retina. We identified that Otud7b is predominantly expressed in photoreceptor cells in the mouse retina. While the ablation of Otud7b did not cause a significant defect in development and maturation of the mouse retina, Otud7b?/? mice subjected to light-induced damage, which is one of the dry age-related macular degeneration models, exhibited increased cone photoreceptor degeneration. In addition, Otud7b deficiency in Mak?/? mice, a retinitis pigmentosa mouse model, resulted in further cone photoreceptor degeneration. Moreover, neuronal cells deficient in Otud7b were susceptible to serum starvation, resulting in cell death. We found that NF-?B activity is increased in the Otud7b?/? retinas exposed to light by RNA-sequencing analysis. Luciferase reporter assay also demonstrated increased NF-?B activation in Otud7b-deficient neuronal cells under stress. The neuronal cell death resulting from Otud7b deficiency was suppressed through the inhibition of NF-?B. Furthermore, we observed that inhibition of NF-?B attenuated cone photoreceptor degeneration in the light-exposed Otud7b?/? retina. Together, the current study suggests that Otud7b deubiquitinase protects cone photoreceptor cells under stress conditions by modulating the NF-?B activity. Overall design: We performed RNA-seq analysis using retinal RNAs from Otud7b+/+ and Otud7b?/? mice that underwent light exposure.