Propofol rescues voltage-dependent gating of HCN1 channel epilepsy mutants.

1. Nature. 2024 Aug;632(8024):451-459. doi: 10.1038/s41586-024-07743-z. Epub 2024 Jul 31. Propofol rescues voltage-dependent gating of HCN1 channel epilepsy mutants. Kim ED(#)(1), Wu X(#)(2), Lee S(1), Tibbs GR(1), Cunningham KP(2)(3), Di Zanni E(1), Perez ME(2), Goldstein PA(1), Accardi A(1)(4), Larsson HP(5)(6), Nimigean CM(7)(8). Author information: (1)Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA. (2)Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA. (3)School of Life Sciences, University of Westminster, London, UK. (4)Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA. (5)Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA. peter.larsson@liu.se. (6)Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden. peter.larsson@liu.se. (7)Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA. crn2002@med.cornell.edu. (8)Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA. crn2002@med.cornell.edu. (#)Contributed equally Comment in Epilepsy Curr. 2025 Feb 28;25(3):192-194. doi: 10.1177/15357597251318573. 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. © 2024. The Author(s), under exclusive licence to Springer Nature Limited. DOI: 10.1038/s41586-024-07743-z PMCID: PMC11634041 PMID: 39085604 [Indexed for MEDLINE] Conflict of interest statement: Competing interest declaration GT and PG are co-inventors on patents related to the development of novel alkylphenols for the treatment of neuropathic pain. GT and PG serve on the Scientific Advisory Board for Akelos Inc. (New York, NY), a research-based biotechnology company that has a licensing agreement for the use of those patents.