Department of Small Animal Clinical Sciences, Veterinary Medical Center, Michigan State University, East Lansing, MI, USA.
Center for Integrated Protein Science Munich (CIPSM) at the Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany.
Adv Exp Med Biol. 2019;1185:103-107. doi: 10.1007/978-3-030-27378-1_17.
Mutations in the gene encoding the phosphodiesterase 6 alpha subunit (PDE6A) account for 3-4% of autosomal recessive retinitis pigmentosa (RP), and currently no treatment is available. There are four animal models for PDE6A-RP: a dog with a frameshift truncating mutation (p.Asn616ThrfsTer39) and three mouse models with missense mutations (Val685Met, Asp562Trp, and Asp670Gly) showing a range of phenotype severities. Initial proof-of-concept gene augmentation studies in the Asp670Gly mouse model and dog model used a subretinally delivered adeno-associated virus serotype 8 with a 733 tyrosine capsid mutation delivering species-specific Pde6a cDNAs. These restored some rod-mediated function and preserved retinal structure. Subsequently, a translatable vector (AAV8 with a human rhodopsin promoter and human PDE6A cDNA) was tested in the dog and the Asp670Gly mouse model. In the dog, there was restoration of rod function, a robust rod-mediated ERG, and introduction of dim-light vision. Treatment improved morphology of the photoreceptor layer, and the retina was preserved in the treated region. In the Asp670Gly mouse, therapy also preserved photoreceptors with cone survival being reflected by maintenance of cone-mediated ERG responses. These studies are an important step toward a translatable therapy for PDE6A-RP.
PDE6A 基因编码突变（phosphodiesterase 6 alpha subunit）占常染色体隐性遗传视网膜色素变性（RP）的 3-4%，目前尚无治疗方法。目前有四种 PDE6A-RP 的动物模型：一种狗带有移码截断突变（p.Asn616ThrfsTer39），三种小鼠模型带有错义突变（Val685Met、Asp562Trp 和 Asp670Gly），表现出不同程度的表型严重程度。在 Asp670Gly 小鼠模型和狗模型中的最初概念验证基因增强研究中，使用了带有 733 个酪氨酸衣壳突变的亚视网膜递送达的腺相关病毒血清型 8 载体，传递种特异性的 Pde6a cDNA。这些方法恢复了一些杆状介导的功能并保留了视网膜结构。随后，在狗和 Asp670Gly 小鼠模型中测试了一种可转化的载体（带有人类视紫红质启动子和人类 PDE6A cDNA 的 AAV8）。在狗中，恢复了杆状功能，产生了强大的杆状介导的 ERG，并引入了暗光视觉。治疗改善了光感受器层的形态，并且在治疗区域保留了视网膜。在 Asp670Gly 小鼠中，治疗也保留了光感受器，这反映在维持锥状介导的 ERG 反应中。这些研究是开发可转化的 PDE6A-RP 治疗方法的重要一步。
