Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisbon, 1749-016, Lisbon, Portugal.
Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisbon, 1749-016, Lisbon, Portugal.
Eur J Pharmacol. 2024 Mar 15;967:176390. doi: 10.1016/j.ejphar.2024.176390. Epub 2024 Feb 8.
The deletion of a phenylalanine at position 508 (p.Phe508del) in the CFTR anion channel is the most prevalent variant in people with Cystic Fibrosis (CF). This variant impairs folding and stability of the CF transmembrane conductance regulator (CFTR) protein, resulting in its defective trafficking and premature degradation. Over the last years, therapeutic accomplishments have been attained in developing small molecules that partially correct p.Phe508del-CFTR defects; however, the mechanism of action (MoA) of these compounds has only started to be uncovered. In this study, we employed biochemical, fluorescence microscopy, and functional assays to examine the efficacy and properties of PTI-801, a newly developed p.Phe508del-CFTR corrector. To exploit its MoA, we assessed PTI-801 effects in combination with low temperature, genetic revertants of p.Phe508del-CFTR (the in cis p.Val510Asp, p.Gly550Glu, p.Arg1070Trp, and 4RK) and other correctors. Our results demonstrated that PTI-801 rescues p.Phe508del-CFTR processing, PM trafficking, and channel function (upon agonist stimulation) with greater correction effects in combination with ABBV-2222, FDL-169, VX-661, or VX-809, but not with VX-445. Although PTI-801 exhibited no potentiator activity on low temperature- and corrector-rescued p.Phe508del-CFTR, this compound displayed similar behavior to that of VX-445 on genetic revertants. Such evidence associated with the lack of additivity when PTI-801 and VX-445 were combined indicates that they share a common binding site to correct p.Phe508del-CFTR defects. Despite the high efficacy of PTI-801 in combination with ABBV-2222, FDL-169, VX-661, or VX-809, these dual corrector combinations only partially restored p.Phe508del-CFTR conformational stability, as shown by the lower half-life of the mutant protein compared to that of WT-CFTR. In summary, PTI-801 likely shares a common MoA with VX-445 in rescuing p.Phe508del-CFTR, thus being a feasible alternative for the development of novel corrector combinations with greater capacity to rescue mutant CFTR folding and stability.
CFTR 阴离子通道中第 508 位苯丙氨酸的缺失（p.Phe508del）是囊性纤维化（CF）患者中最常见的变体。这种变体损害 CF 跨膜电导调节剂（CFTR）蛋白的折叠和稳定性，导致其运输缺陷和过早降解。在过去的几年中，在开发能够部分纠正 p.Phe508del-CFTR 缺陷的小分子方面取得了治疗成就；然而，这些化合物的作用机制（MoA）才刚刚开始被揭示。在这项研究中，我们采用生化、荧光显微镜和功能测定来研究新开发的 p.Phe508del-CFTR 校正剂 PTI-801 的功效和特性。为了利用其 MoA，我们评估了 PTI-801 与低温、p.Phe508del-CFTR 的遗传回复突变体（顺式 p.Val510Asp、p.Gly550Glu、p.Arg1070Trp 和 4RK）和其他校正剂联合使用的效果。我们的结果表明，PTI-801 可恢复 p.Phe508del-CFTR 的加工、PM 运输和通道功能（在激动剂刺激下），与 ABBV-2222、FDL-169、VX-661 或 VX-809 联合使用时具有更好的校正效果，但与 VX-445 联合使用时则不然。尽管 PTI-801 对低温和校正剂挽救的 p.Phe508del-CFTR 没有增效作用，但该化合物在遗传回复突变体上的行为与 VX-445 相似。当 PTI-801 和 VX-445 联合使用时缺乏加性的这种证据表明，它们具有纠正 p.Phe508del-CFTR 缺陷的共同结合位点。尽管 PTI-801 与 ABBV-2222、FDL-169、VX-661 或 VX-809 联合使用的疗效很高，但这些双重校正剂组合仅部分恢复了 p.Phe508del-CFTR 的构象稳定性，与 WT-CFTR 相比，突变蛋白的半衰期更短。总之，PTI-801 可能与 VX-445 具有共同的 MoA，可挽救 p.Phe508del-CFTR，因此是开发具有更大潜力挽救突变 CFTR 折叠和稳定性的新型校正剂组合的可行选择。
