Cyclic nucleotide-gated (CNG) channels are important mediators in the transduction pathways of rod and cone photoreceptors. Native CNG channels are heterotetramers composed of homologous A and B subunits. Biallelic mutations in CNGA1 or CNGB1 genes result in autosomal recessive retinitis pigmentosa (RP). To investigate the pathogenic mechanism of CNG channel-associated retinal degeneration, we developed a mouse model of CNGA1 knock-out using CRISPR/Cas9 technology. We observed progressive retinal thinning and a concomitant functional deficit in vivo as typical phenotypes for RP. Immunofluorescence and TUNEL staining showed progressive degeneration in rods and cones. Moreover, microglial activation and oxidative stress damage occurred in parallel. RNA-sequencing analysis of the retinae suggested down-regulated synaptic transmission and phototransduction as early as 9 days postnatal, possibly inducing later photoreceptor degeneration. In addition, the down-regulated PI3K-AKT-mTOR pathway indicated upregulation of autophagic process, and chaperone-mediated autophagy was further shown to coincide with the time course of photoreceptor death. Taken together, our studies add to a growing body of research exploring the mechanisms of photoreceptor death during RP progression and provide a novel CNGA1 knockout mouse model for potential development of therapies.

中文翻译：

---

缺乏环核苷酸门控通道亚基 CNGA1 小鼠的视网膜变性

环核苷酸门控 (CNG) 通道是杆状和锥状光感受器转导通路中的重要介质。天然 CNG 通道是由同源 A 和 B 亚基组成的异源四聚体。CNGA1或CNGB1基因中的双等位基因突变导致常染色体隐性色素性视网膜炎 (RP)。为了研究 CNG 通道相关性视网膜变性的发病机制，我们开发了CNGA1小鼠模型使用 CRISPR/Cas9 技术敲除。我们观察到渐进性视网膜变薄和伴随的体内功能缺陷是 RP 的典型表型。免疫荧光和 TUNEL 染色显示视杆细胞和视锥细胞逐渐退化。此外，小胶质细胞激活和氧化应激损伤同时发生。视网膜的 RNA 测序分析表明，早在出生后 9 天，突触传递和光转导就下调，可能导致后期光感受器退化。此外，下调的 PI3K-AKT-mTOR 通路表明自噬过程上调，并且伴侣蛋白介导的自噬进一步显示与光感受器死亡的时间过程一致。综合起来，CNGA1基因敲除小鼠模型的潜在疗法开发。