PDF(Pubmed)
Abstract：
In treating retinitis pigmentosa, a genetic disorder causing progressive vision loss, selective inhibition of rod cyclic nucleotide-gated (CNG) channels holds promise. Blocking the increased Ca2+-influx in rod photoreceptors through CNG channels can potentially delay disease progression and improve the quality of life for patients. To find inhibitors for rod CNG channels, we investigated the impact of 16 cGMP analogues on both rod and cone CNG channels using the patch-clamp technique. Although modifications at the C8 position of the guanine ring did not change the ligand efficacy, modifications at the N1 and N2 positions rendered cGMP largely ineffective in activating retinal CNG channels. Notably, PET-cGMP displayed selective potential, favoring rod over cone, whereas Rp-cGMPS showed greater efficiency in activating cone over rod CNG channels. Ligand docking and molecular dynamics simulations on cyclic nucleotide-binding domains showed comparable binding energies and binding modes for cGMP and its analogues in both rod and cone CNG channels (CNGA1 vs CNGA3 subunits). Computational experiments on CNGB1a vs CNGB3 subunits showed similar binding modes albeit with fewer amino acid interactions with cGMP due to an inactivated conformation of their C-helix. In addition, no clear correlation could be observed between the computational scores and the CNG channel efficacy values, suggesting additional factors beyond binding strength determining ligand selectivity and potency. This study highlights the importance of looking beyond the cyclic nucleotide-binding domain and toward the gating mechanism when searching for selective modulators. Future efforts in developing selective modulators for CNG channels should prioritize targeting alternative channel domains.
摘要：
在治疗视网膜色素变性时，导致进行性视力丧失的遗传性疾病，选择性抑制杆状环核苷酸门控（CNG）通道有望实现。通过CNG通道阻断杆状光感受器中增加的Ca2+流入可以潜在地延迟疾病进展并改善患者的生活质量。为了寻找棒CNG通道的抑制剂，我们使用膜片钳技术研究了16种cGMP类似物对棒形和锥形CNG通道的影响.虽然鸟嘌呤环C8位的修饰并没有改变配体的功效，在N1和N2位置的修饰使cGMP在激活视网膜CNG通道方面基本上无效。值得注意的是,PET-cGMP显示选择性潜能,喜欢棒而不是锥，而Rp-cGMPS在激活杆状CNG通道上显示出更高的效率。环核苷酸结合域上的配体对接和分子动力学模拟显示，在杆状和锥形CNG通道（CNGA1vsCNGA3亚基）中，cGMP及其类似物的结合能和结合模式相当。CNGB1a对CNGB3亚基的计算实验显示出相似的结合模式，尽管由于其C-螺旋的失活构象，氨基酸与cGMP的相互作用较少。此外,计算分数和CNG通道功效值之间没有明显的相关性，表明除了结合强度之外的其他因素决定了配体的选择性和效力。这项研究强调了在寻找选择性调节剂时，超越环核苷酸结合域和门控机制的重要性。开发用于CNG通道的选择性调节剂的未来努力应优先考虑靶向替代通道域。
