美国威尔康奈尔医学院Crina M. Nimigean等研究人员合作发现丙泊酚可恢复HCN1通道癫痫突变体的电压依赖性门控。2024年7月31日，《自然》杂志在线发表了这一最新研究成果。

通过单粒子冷冻电子显微镜和电生理学，研究人员展示了丙泊酚通过与S5和S6跨膜螺旋之间的一个机制热点结合来抑制超极化激活的环核苷酸门控（HCN）1。研究人员发现丙泊酚恢复了两种HCN1癫痫相关多态性（M305L和D401H）中的电压依赖性闭合，其中M305L位于S5中的丙泊酚结合位点，D401H位于S6。这些多态性通过破坏通道的闭合状态而起作用。

为了理解丙泊酚抑制和恢复电压门控的机制，研究人员追踪了spHCN通道中的电压传感器运动，并发现丙泊酚的抑制作用与电压传感器的构象变化无关。spHCN中的同源甲硫氨酸及S6中的相邻保守苯丙氨酸的突变类似地使闭合状态不稳定，但不干扰电压传感器运动，表明电压依赖的闭合需要这个界面保持完整。

研究人员提出了一种电压依赖性门控的模型，其中丙泊酚通过稳定电压传感器与孔道之间的耦合来作用于HCN通道中的保守甲硫氨酸-苯丙氨酸界面。这些发现揭示了该位点的潜在利用价值，以设计针对HCN通道病的特异性药物。

研究人员表示，HCN通道对于起搏活动和神经信号传导至关重要。抑制HCN1的药物是治疗神经性疼痛和癫痫发作的有前景的候选药物。全身麻醉药物丙泊酚（2,6-二异丙基苯酚）是一种已知的HCN1别构抑制剂，但其结构基础尚不明确。

附：英文原文

Title: Propofol rescues voltage-dependent gating of HCN1 channel epilepsy mutants

Author: Kim, Elizabeth D., Wu, Xiaoan, Lee, Sangyun, Tibbs, Gareth R., Cunningham, Kevin P., Di Zanni, Eleonora, Perez, Marta E., Goldstein, Peter A., Accardi, Alessio, Larsson, H. Peter, Nimigean, Crina M.

Issue&Volume: 2024-07-31

Abstract: Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels1 are essential for pacemaking activity and neural signalling2,3. Drugs inhibiting HCN1 are promising candidates for management of neuropathic pain4 and epileptic seizures5. The general anaesthetic propofol (2,6-di-iso-propylphenol) is a known HCN1 allosteric inhibitor6 with unknown structural basis. Here, using single-particle cryo-electron microscopy and electrophysiology, we show that propofol inhibits HCN1 by binding to a mechanistic hotspot in a groove between the S5 and S6 transmembrane helices. We found that propofol restored voltage-dependent closing in two HCN1 epilepsy-associated polymorphisms that act by destabilizing the channel closed state: M305L, located in the propofol-binding site in S5, and D401H in S6 (refs.7,8). To understand the mechanism of propofol inhibition and restoration of voltage-gating, we tracked voltage-sensor movement in spHCN channels and found that propofol inhibition is independent of voltage-sensor conformational changes. Mutations at the homologous methionine in spHCN and an adjacent conserved phenylalanine in S6 similarly destabilize closing without disrupting voltage-sensor movements, indicating that voltage-dependent closure requires this interface intact. We propose a model for voltage-dependent gating in which propofol stabilizes coupling between the voltage sensor and pore at this conserved methionine–phenylalanine interface in HCN channels. These findings unlock potential exploitation of this site to design specific drugs targeting HCN channelopathies.

DOI: 10.1038/s41586-024-07743-z

Source: https://www.nature.com/articles/s41586-024-07743-z