The Key Laboratory for Human Disease Gene Study of Sichuan Province and Institute of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.
Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Henan Provincial Ophthalmic Hospital, Zhengzhou, China.
Curr Med Chem. 2022;29(40):6115-6124. doi: 10.2174/0929867329666220216111952.
Catalytic hydrolysis of cyclic guanosine monophosphate (cGMP) by phosphodiesterase 6 (PDE6) is critical in phototransduction signalling in photoreceptors. Mutations in the genes encoding any of the three PDE6 subunits are associated with retinitis pigmentosa, the most common form of inherited retinal diseases. The RD1 mouse carries a naturally occurring nonsense mutation in the Pde6b gene. The RD1 mouse retina rapidly degenerates and fails to form rod photoreceptor outer segments due to the elevated cGMP level and subsequent excessive Ca2+ influx. In this study, we aim to test whether the PDE5 expression, a non-photoreceptor-specific member of the PDE superfamily, rescues photoreceptors in the RD1 retina.
Electroporation used the PDE5 expression plasmid to transfect neonatal RD1 mice. The mouse retina degeneration was assessed by retinal sections' stains with DAPI. The expression and localization of phototransduction proteins in photoreceptors were analysed by immunostaining. The expression of proteins in cultured cells was analysed by immunoblotting.
The exogenous PDE5 expression, a non-photoreceptor-specific member of the PDE superfamily, prevents photoreceptor degeneration in RD1 mice. Unlike endogenous photoreceptor-specific PDE6 localised in the outer segments of photoreceptors, ectopically- expressed PDE5 was distributed in inner segments and synaptic terminals. PDE5 also promoted the development of the outer segments in RD1 mice. PDE5 co-expression with rhodopsin in cultured cells showed enhanced rhodopsin expression.
Lowering the cGMP level in photoreceptors by PDE5 is sufficient to rescue photoreceptors in RD1 retinas. cGMP may also play a role in rhodopsin expression regulation in photoreceptors.
环鸟苷酸单磷酸（cGMP）的磷酸二酯酶 6（PDE6）催化水解在光感受器的光转导信号中至关重要。编码 PDE6 三个亚基之一的基因突变与视网膜色素变性有关，这是最常见的遗传性视网膜疾病。RD1 小鼠携带 Pde6b 基因的自然发生的无义突变。由于 cGMP 水平升高和随后的 Ca2+ 内流过多，RD1 小鼠的视网膜迅速退化，无法形成杆状光感受器外节。在这项研究中，我们旨在测试 PDE5 表达（PDE 超家族的非光感受器特异性成员）是否可以挽救 RD1 视网膜中的光感受器。
电穿孔使用 PDE5 表达质粒转染新生 RD1 小鼠。用 DAPI 染色视网膜切片评估小鼠视网膜变性。通过免疫染色分析光感受器中光转导蛋白的表达和定位。通过免疫印迹分析培养细胞中的蛋白表达。
外源性 PDE5 表达（PDE 超家族的非光感受器特异性成员）可防止 RD1 小鼠中的光感受器变性。与定位于光感受器外节的内源性光感受器特异性 PDE6 不同，异位表达的 PDE5 分布在内节和突触末端。PDE5 还促进了 RD1 小鼠中外节的发育。在培养的细胞中，PDE5 与视蛋白共表达显示出增强的视蛋白表达。
通过 PDE5 降低光感受器中的 cGMP 水平足以挽救 RD1 视网膜中的光感受器。cGMP 也可能在光感受器中的视蛋白表达调控中发挥作用。
