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Joseph TT, Bu W, Haji-Ghassemi O, Chen YS, Woll K, Allen PD, Brannigan G, van Petegem F, Eckenhoff RG. Propofol directly binds and inhibits skeletal muscle ryanodine receptor 1 (RyR1). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.10.575040. [PMID: 38260485 PMCID: PMC10802444 DOI: 10.1101/2024.01.10.575040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
As the primary Ca 2+ release channel in skeletal muscle sarcoplasmic reticulum (SR), mutations in the type 1 ryanodine receptor (RyR1) or its binding partners underlie a constellation of muscle disorders, including malignant hyperthermia (MH). In patients with MH mutations, exposure to triggering drugs such as the halogenated volatile anesthetics biases RyR1 to an open state, resulting in uncontrolled Ca 2+ release, sarcomere tension and heat production. Restoration of Ca 2+ into the SR also consumes ATP, generating a further untenable metabolic load. When anesthetizing patients with known MH mutations, the non-triggering intravenous general anesthetic propofol is commonly substituted for triggering anesthetics. Evidence of direct binding of anesthetic agents to RyR1 or its binding partners is scant, and the atomic-level interactions of propofol with RyR1 are entirely unknown. Here, we show that propofol decreases RyR1 opening in heavy SR vesicles and planar lipid bilayers, and that it inhibits activator-induced Ca 2+ release from SR in human skeletal muscle. In addition to confirming direct binding, photoaffinity labeling using m- azipropofol (AziP m ) revealed several putative propofol binding sites on RyR1. Prediction of binding affinity by molecular dynamics simulation suggests that propofol binds at least one of these sites at clinical concentrations. These findings invite the hypothesis that in addition to propofol not triggering MH, it may also be protective against MH by inhibiting induced Ca 2+ flux through RyR1.
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Yan J, Hang BN, Ma LH, Lin JT, Zhou Y, Jiao XH, Yuan YX, Shao KJ, Zhang LM, Xue Q, Li ZY, Zhang HX, Cao JL, Li S, Zheng H, Wu YQ. GABAergic Neurons in the Nucleus Accumbens are Involved in the General Anesthesia Effect of Propofol. Mol Neurobiol 2023; 60:5789-5804. [PMID: 37349621 DOI: 10.1007/s12035-023-03445-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 06/03/2023] [Indexed: 06/24/2023]
Abstract
The mechanism underlying the hypnosis effect of propofol is still not fully understood. In essence, the nucleus accumbens (NAc) is crucial for regulating wakefulness and may be directly engaged in the principle of general anesthesia. However, the role of NAc in the process of propofol-induced anesthesia is still unknown. We used immunofluorescence, western blotting, and patch-clamp to access the activities of NAc GABAergic neurons during propofol anesthesia, and then we utilized chemogenetic and optogenetic methods to explore the role of NAc GABAergic neurons in regulating propofol-induced general anesthesia states. Moreover, we also conducted behavioral tests to analyze anesthetic induction and emergence. We found out that c-Fos expression was considerably dropped in NAc GABAergic neurons after propofol injection. Meanwhile, patch-clamp recording of brain slices showed that firing frequency induced by step currents in NAc GABAergic neurons significantly decreased after propofol perfusion. Notably, chemically selective stimulation of NAc GABAergic neurons during propofol anesthesia lowered propofol sensitivity, prolonged the induction of propofol anesthesia, and facilitated recovery; the inhibition of NAc GABAergic neurons exerted opposite effects. Furthermore, optogenetic activation of NAc GABAergic neurons promoted emergence whereas the result of optogenetic inhibition was the opposite. Our results demonstrate that NAc GABAergic neurons modulate propofol anesthesia induction and emergence.
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Affiliation(s)
- Jing Yan
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Bei-Ning Hang
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Lin-Hui Ma
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Jia-Tao Lin
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Yue Zhou
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Xin-Hao Jiao
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Ying-Xuan Yuan
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Ke-Jie Shao
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Le-Meng Zhang
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Qi Xue
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Zi-Yi Li
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Hong-Xing Zhang
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Jun-Li Cao
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China
| | - Shuai Li
- Department of Anesthesiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China.
| | - Hui Zheng
- Department of Anesthesiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China.
| | - Yu-Qing Wu
- Jiangsu Province Key Laboratory of Anesthesiology/NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, 221004, China.
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Zhang B, Zhang P, L T, Cao Y, Chen T, Chen C, Zhang Z, Zhong Q. P2X7 Receptor in microglia contributes to propofol-induced unconsciousness by regulating synaptic plasticity in mice. Neuroscience 2023:S0306-4522(23)00223-3. [PMID: 37211083 DOI: 10.1016/j.neuroscience.2023.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 04/16/2023] [Accepted: 05/14/2023] [Indexed: 05/23/2023]
Abstract
Propofol infusion is processed through the wake-sleep cycle in neural connections, and the ionotropic purine type 2X7 receptor (P2X7R) is a nonspecific cation channel implicated in sleep regulation and synaptic plasticity through its regulation of electric activity in the brain. Here, we explored the potential roles of P2X7R of microglia in propofol-induced unconsciousness. Propofol induced loss of the righting reflex in male C57BL/6 wild-type mice and increased spectral power of the slow wave and delta wave of the medial prefrontal cortex (mPFC), all of which were reversed with P2X7R antagonist A-740003 and strengthened with P2X7R agonist Bz-ATP. Propofol increased the P2X7R expression level and P2X7R immunoreactivity with microglia in the mPFC, induced mild synaptic injury and increased GABA release in the mPFC, and these changes were less severe when treated with A-740003 and were more obvious when treated with Bz-ATP. Electrophysiological approaches showed that propofol induced a decreased frequency of sEPSCs and an increased frequency of sIPSCs, A-740003 decrease frequency of sEPSCs and sIPSCs and Bz-ATP increase frequency of sEPSCs and sIPSCs under propofol anesthesia. These findings indicated that P2X7R in microglia regulates synaptic plasticity and may contribute to propofol-mediated unconsciousness.
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Affiliation(s)
- Bo Zhang
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China, 430022
| | - Panpan Zhang
- Department of Anesthesiology, Zhongnan Hospital, Wuhan University, East Lake Road, Wuhan, Hubei, China, 430071; Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China, 430022
| | - Tingting L
- Department of Anesthesiology, Zhongnan Hospital, Wuhan University, East Lake Road, Wuhan, Hubei, China, 430071
| | - Yue Cao
- Department of Anesthesiology, Zhongnan Hospital, Wuhan University, East Lake Road, Wuhan, Hubei, China, 430071
| | - Ting Chen
- Department of Anesthesiology, Zhongnan Hospital, Wuhan University, East Lake Road, Wuhan, Hubei, China, 430071
| | - Chang Chen
- Department of Anesthesiology, Zhongnan Hospital, Wuhan University, East Lake Road, Wuhan, Hubei, China, 430071
| | - Zongze Zhang
- Department of Anesthesiology, Zhongnan Hospital, Wuhan University, East Lake Road, Wuhan, Hubei, China, 430071.
| | - Qi Zhong
- Department of Anesthesiology, Zhongnan Hospital, Wuhan University, East Lake Road, Wuhan, Hubei, China, 430071.
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Oda R, Shou J, Zhong W, Ozeki Y, Yasui M, Nuriya M. Direct visualization of general anesthetic propofol on neurons by stimulated Raman scattering microscopy. iScience 2022; 25:103936. [PMID: 35252821 PMCID: PMC8894261 DOI: 10.1016/j.isci.2022.103936] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 01/28/2022] [Accepted: 02/14/2022] [Indexed: 11/29/2022] Open
Abstract
The consensus for the precise mechanism of action of general anesthetics is through allosteric interactions with GABA receptors in neurons. However, it has been speculated that these anesthetics may also interact with the plasma membrane on some level. Owing to the small size of anesthetics, direct visualization of these interactions is difficult to achieve. We demonstrate the ability to directly visualize a deuterated analog of propofol in living cells using stimulated Raman scattering (SRS) microscopy. Our findings support the theory that propofol is highly concentrated and interacts primarily through non-specific binding to the plasma membrane of neurons. Additionally, we show that SRS microscopy can be used to monitor the dynamics of propofol binding using real-time, live-cell imaging. The strategy used to visualize propofol can be applied to other small molecule drugs that have been previously invisible to traditional imaging techniques Multi-modal SRS developed for real-time biological imaging of small molecule substances Propofol primarily concentrates at the cell membrane of neurons Anesthesia dynamics can be monitored in real-time with SRS
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Affiliation(s)
- Robert Oda
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
- Department of Electrical Engineering and Information Systems, Graduate School of Engineering, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
- Corresponding author
| | - Jingwen Shou
- Department of Electrical Engineering and Information Systems, Graduate School of Engineering, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Wenying Zhong
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Yasuyuki Ozeki
- Department of Electrical Engineering and Information Systems, Graduate School of Engineering, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Masato Yasui
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Mutsuo Nuriya
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
- Graduate School of Environment and Information Sciences, Yokohama National University, 79-1 Tokiwadai, Hodogaya, Yokohama, Kanagawa 240-8501, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
- Corresponding author
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5
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Yang E, Bu W, Suma A, Carnevale V, Grasty KC, Loll PJ, Woll K, Bhanu N, Garcia BA, Eckenhoff RG, Covarrubias M. Binding Sites and the Mechanism of Action of Propofol and a Photoreactive Analogue in Prokaryotic Voltage-Gated Sodium Channels. ACS Chem Neurosci 2021; 12:3898-3914. [PMID: 34607428 DOI: 10.1021/acschemneuro.1c00495] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Propofol, one of the most commonly used intravenous general anesthetics, modulates neuronal function by interacting with ion channels. The mechanisms that link propofol binding to the modulation of distinct ion channel states, however, are not understood. To tackle this problem, we investigated the prokaryotic ancestors of eukaryotic voltage-gated Na+ channels (Navs) using unbiased photoaffinity labeling (PAL) with a diazirine derivative of propofol (AziPm), electrophysiological methods, and mutagenesis. AziPm inhibits Nav function in a manner that is indistinguishable from that of the parent compound by promoting activation-coupled inactivation. In several replicates (8/9) involving NaChBac and NavMs, we found adducts at residues located at the C-terminal end of the S4 voltage sensor, the S4-S5 linker, and the N-terminal end of the S5 segment. However, the non-inactivating mutant NaChBac-T220A yielded adducts that were different from those found in the wild-type counterpart, which suggested state-dependent changes at the binding site. Then, using molecular dynamics simulations to further elucidate the structural basis of Nav modulation by propofol, we show that the S4 voltage sensors and the S4-S5 linkers shape two distinct propofol binding sites in a conformation-dependent manner. Supporting the PAL and MD simulation results, we also found that Ala mutations of a subset of adducted residues have distinct effects on gating modulation of NaChBac and NavMs by propofol. The results of this study provide direct insights into the structural basis of the mechanism through which propofol binding promotes activation-coupled inactivation to inhibit Nav channel function.
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Affiliation(s)
- Elaine Yang
- Department of Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, United States
| | - Weiming Bu
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Antonio Suma
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, United States
- Dipartimento di Fisica, Universit̀a di Bari, and Sezione INFN di Bari, via Amendola 173, Bari 70126, Italy
| | - Vincenzo Carnevale
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Kimberly C. Grasty
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, Pennsylvania 19102, United States
| | - Patrick J. Loll
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, Pennsylvania 19102, United States
| | - Kellie Woll
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Natarajan Bhanu
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Benjamin A. Garcia
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Roderic G. Eckenhoff
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Manuel Covarrubias
- Department of Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, United States
- Bluemle Life Sciences Building, 233 S 10th Street, Room 231, Philadelphia, Pennsylvania 19107, United States
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Angsutararux P, Kang PW, Zhu W, Silva JR. Conformations of voltage-sensing domain III differentially define NaV channel closed- and open-state inactivation. J Gen Physiol 2021; 153:212533. [PMID: 34347027 PMCID: PMC8348240 DOI: 10.1085/jgp.202112891] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 07/14/2021] [Indexed: 11/21/2022] Open
Abstract
Voltage-gated Na+ (NaV) channels underlie the initiation and propagation of action potentials (APs). Rapid inactivation after NaV channel opening, known as open-state inactivation, plays a critical role in limiting the AP duration. However, NaV channel inactivation can also occur before opening, namely closed-state inactivation, to tune the cellular excitability. The voltage-sensing domain (VSD) within repeat IV (VSD-IV) of the pseudotetrameric NaV channel α-subunit is known to be a critical regulator of NaV channel inactivation. Yet, the two processes of open- and closed-state inactivation predominate at different voltage ranges and feature distinct kinetics. How inactivation occurs over these different ranges to give rise to the complexity of NaV channel dynamics is unclear. Past functional studies and recent cryo-electron microscopy structures, however, reveal significant inactivation regulation from other NaV channel components. In this Hypothesis paper, we propose that the VSD of NaV repeat III (VSD-III), together with VSD-IV, orchestrates the inactivation-state occupancy of NaV channels by modulating the affinity of the intracellular binding site of the IFMT motif on the III-IV linker. We review and outline substantial evidence that VSD-III activates in two distinct steps, with the intermediate and fully activated conformation regulating closed- and open-state inactivation state occupancy by altering the formation and affinity of the IFMT crevice. A role of VSD-III in determining inactivation-state occupancy and recovery from inactivation suggests a regulatory mechanism for the state-dependent block by small-molecule anti-arrhythmic and anesthetic therapies.
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Affiliation(s)
- Paweorn Angsutararux
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
| | - Po Wei Kang
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
| | - Wandi Zhu
- Department of Medicine, Brigham and Women's Hospital, Boston, MA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
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Regulation and drug modulation of a voltage-gated sodium channel: Pivotal role of the S4-S5 linker in activation and slow inactivation. Proc Natl Acad Sci U S A 2021; 118:2102285118. [PMID: 34260401 PMCID: PMC8285963 DOI: 10.1073/pnas.2102285118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Voltage-gated sodium channels initiate electric signals in cell communications. The S4–S5 linker between the voltage-sensing and pore modules transmits depolarization signals to trigger channel activation. The mechanisms of this action, however, remain elusive. By combining biophysical and computational approaches, we identify a critical residue, T140, in the S4–S5 linker of the bacterial sodium channel NaChBac, which plays a pivotal role in channel activation and drug modulation of slow inactivation. Specifically, we discovered conformation-dependent drug binding at this site and unveiled a toggling mode of action by T140, which switches interaction partners with different S6 residues to regulate channel activation and slow inactivation. These observations suggest the possibility of conformation-specific drugs targeting the gating machinery of voltage-gated ion channels. Voltage-gated sodium (NaV) channels control excitable cell functions. While structural investigations have revealed conformation details of different functional states, the mechanisms of both activation and slow inactivation remain unclear. Here, we identify residue T140 in the S4–S5 linker of the bacterial voltage-gated sodium channel NaChBac as critical for channel activation and drug effects on inactivation. Mutations at T140 either attenuate activation or render the channel nonfunctional. Propofol, a clinical anesthetic known to inhibit NaChBac by promoting slow inactivation, binds to a pocket between the S4–S5 linker and S6 helix in a conformation-dependent manner. Using 19F-NMR to quantify site-specific binding by saturation transfer differences (STDs), we found strong STDs in inactivated, but not activated, NaChBac. Molecular dynamics simulations show a highly dynamic pocket in the activated conformation, limiting STD buildup. In contrast, drug binding to this pocket promotes and stabilizes the inactivated states. Our results provide direct experimental evidence showing distinctly different associations between the S4–S5 linker and S6 helix in activated and inactivated states. Specifically, an exchange occurs between interaction partners T140 and N234 of the same subunit in activation, and T140 and N225 of the domain-swapped subunit in slow inactivation. The drug action on slow inactivation of prokaryotic NaV channels seems to have a mechanism similar to the recently proposed “door-wedge” action of the isoleucine-phenylalanine-methionine (IFM) motif on the fast inactivation of eukaryotic NaV channels. Elucidating this gating mechanism points to a possible direction for conformation-dependent drug development.
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Xiao J, Chen Z, Yu B. A Potential Mechanism of Sodium Channel Mediating the General Anesthesia Induced by Propofol. Front Cell Neurosci 2020; 14:593050. [PMID: 33343303 PMCID: PMC7746837 DOI: 10.3389/fncel.2020.593050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 11/10/2020] [Indexed: 12/19/2022] Open
Abstract
General anesthesia has revolutionized healthcare over the past 200 years and continues to show advancements. However, many phenomena induced by general anesthetics including paradoxical excitation are still poorly understood. Voltage-gated sodium channels (NaV) were believed to be one of the proteins targeted during general anesthesia. Based on electrophysiological measurements before and after propofol treatments of different concentrations, we mathematically modified the Hodgkin–Huxley sodium channel formulations and constructed a thalamocortical model to investigate the potential roles of NaV. The ion channels of individual neurons were modeled using the Hodgkin–Huxley type equations. The enhancement of propofol-induced GABAa current was simulated by increasing the maximal conductance and the time-constant of decay. Electroencephalogram (EEG) was evaluated as the post-synaptic potential from pyramidal (PY) cells. We found that a left shift in activation of NaV was induced primarily by a low concentration of propofol (0.3–10 μM), while a left shift in inactivation of NaV was induced by an increasing concentration (0.3–30 μM). Mathematical simulation indicated that a left shift of NaV activation produced a Hopf bifurcation, leading to cell oscillations. Left shift of NaV activation around a value of 5.5 mV in the thalamocortical models suppressed normal bursting of thalamocortical (TC) cells by triggering its chaotic oscillations. This led to irregular spiking of PY cells and an increased frequency in EEG readings. This observation suggests a mechanism leading to paradoxical excitation during general anesthesia. While a left shift in inactivation led to light hyperpolarization in individual cells, it inhibited the activity of the thalamocortical model after a certain depth of anesthesia. This finding implies that high doses of propofol inhibit the network partly by accelerating NaV toward inactivation. Additionally, this result explains why the application of sodium channel blockers decreases the requirement for general anesthetics. Our study provides an insight into the roles that NaV plays in the mechanism of general anesthesia. Since the activation and inactivation of NaV are structurally independent, it should be possible to avoid side effects by state-dependent binding to the NaV to achieve precision medicine in the future.
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Affiliation(s)
- Jinglei Xiao
- Department of Anesthesiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhengguo Chen
- College of Computer, National University of Defence Technology, Changsha, China
| | - Buwei Yu
- Department of Anesthesiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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9
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Denomme N, Hull JM, Mashour GA. Role of Voltage-Gated Sodium Channels in the Mechanism of Ether-Induced Unconsciousness. Pharmacol Rev 2019; 71:450-466. [PMID: 31471460 DOI: 10.1124/pr.118.016592] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Despite continuous clinical use for more than 170 years, the mechanism of general anesthetics has not been completely characterized. In this review, we focus on the role of voltage-gated sodium channels in the sedative-hypnotic actions of halogenated ethers, describing the history of anesthetic mechanisms research, the basic neurobiology and pharmacology of voltage-gated sodium channels, and the evidence for a mechanistic interaction between halogenated ethers and sodium channels in the induction of unconsciousness. We conclude with a more integrative perspective of how voltage-gated sodium channels might provide a critical link between molecular actions of the halogenated ethers and the more distributed network-level effects associated with the anesthetized state across species.
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Affiliation(s)
- Nicholas Denomme
- Departments of Pharmacology (N.D.) and Anesthesiology (G.A.M.), Center for Consciousness Science (N.D., G.A.M.), and Neuroscience Graduate Program (J.M.H., G.A.M.), University of Michigan, Ann Arbor, Michigan
| | - Jacob M Hull
- Departments of Pharmacology (N.D.) and Anesthesiology (G.A.M.), Center for Consciousness Science (N.D., G.A.M.), and Neuroscience Graduate Program (J.M.H., G.A.M.), University of Michigan, Ann Arbor, Michigan
| | - George A Mashour
- Departments of Pharmacology (N.D.) and Anesthesiology (G.A.M.), Center for Consciousness Science (N.D., G.A.M.), and Neuroscience Graduate Program (J.M.H., G.A.M.), University of Michigan, Ann Arbor, Michigan
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10
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Finol-Urdaneta RK, McArthur JR, Korkosh VS, Huang S, McMaster D, Glavica R, Tikhonov DB, Zhorov BS, French RJ. Extremely Potent Block of Bacterial Voltage-Gated Sodium Channels by µ-Conotoxin PIIIA. Mar Drugs 2019; 17:md17090510. [PMID: 31470595 PMCID: PMC6780087 DOI: 10.3390/md17090510] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 08/13/2019] [Accepted: 08/24/2019] [Indexed: 12/15/2022] Open
Abstract
µ-Conotoxin PIIIA, in the sub-picomolar, range inhibits the archetypal bacterial sodium channel NaChBac (NavBh) in a voltage- and use-dependent manner. Peptide µ-conotoxins were first recognized as potent components of the venoms of fish-hunting cone snails that selectively inhibit voltage-gated skeletal muscle sodium channels, thus preventing muscle contraction. Intriguingly, computer simulations predicted that PIIIA binds to prokaryotic channel NavAb with much higher affinity than to fish (and other vertebrates) skeletal muscle sodium channel (Nav 1.4). Here, using whole-cell voltage clamp, we demonstrate that PIIIA inhibits NavBac mediated currents even more potently than predicted. From concentration-response data, with [PIIIA] varying more than 6 orders of magnitude (10−12 to 10−5 M), we estimated an IC50 = ~5 pM, maximal block of 0.95 and a Hill coefficient of 0.81 for the inhibition of peak currents. Inhibition was stronger at depolarized holding potentials and was modulated by the frequency and duration of the stimulation pulses. An important feature of the PIIIA action was acceleration of macroscopic inactivation. Docking of PIIIA in a NaChBac (NavBh) model revealed two interconvertible binding modes. In one mode, PIIIA sterically and electrostatically blocks the permeation pathway. In a second mode, apparent stabilization of the inactivated state was achieved by PIIIA binding between P2 helices and trans-membrane S5s from adjacent channel subunits, partially occluding the outer pore. Together, our experimental and computational results suggest that, besides blocking the channel-mediated currents by directly occluding the conducting pathway, PIIIA may also change the relative populations of conducting (activated) and non-conducting (inactivated) states.
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Affiliation(s)
- Rocio K Finol-Urdaneta
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia.
- Department of Biochemistry, Brandeis University, Waltham, MA 0254-9110, USA.
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Vyacheslav S Korkosh
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg 194223, Russia
| | - Sun Huang
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Denis McMaster
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Robert Glavica
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Denis B Tikhonov
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg 194223, Russia
| | - Boris S Zhorov
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg 194223, Russia
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8N 4K1, Canada
| | - Robert J French
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
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11
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Sedwick C. Propofol’s paradox, explained. J Gen Physiol 2018; 150:1231-1232. [PMID: 30115662 PMCID: PMC6122930 DOI: 10.1085/jgp.201812197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Tandem JGP studies investigate how propofol affects voltage-gated sodium channels. Tandem JGP studies investigate how propofol affects voltage-gated sodium channels.
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12
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Wang Y, Yang E, Wells MM, Bondarenko V, Woll K, Carnevale V, Granata D, Klein ML, Eckenhoff RG, Dailey WP, Covarrubias M, Tang P, Xu Y. Propofol inhibits the voltage-gated sodium channel NaChBac at multiple sites. J Gen Physiol 2018; 150:1317-1331. [PMID: 30018039 PMCID: PMC6122922 DOI: 10.1085/jgp.201811993] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 05/02/2018] [Accepted: 06/15/2018] [Indexed: 12/24/2022] Open
Abstract
Voltage-gated sodium (NaV) channels are important targets of general anesthetics, including the intravenous anesthetic propofol. Electrophysiology studies on the prokaryotic NaV channel NaChBac have demonstrated that propofol promotes channel activation and accelerates activation-coupled inactivation, but the molecular mechanisms of these effects are unclear. Here, guided by computational docking and molecular dynamics simulations, we predict several propofol-binding sites in NaChBac. We then strategically place small fluorinated probes at these putative binding sites and experimentally quantify the interaction strengths with a fluorinated propofol analogue, 4-fluoropropofol. In vitro and in vivo measurements show that 4-fluoropropofol and propofol have similar effects on NaChBac function and nearly identical anesthetizing effects on tadpole mobility. Using quantitative analysis by 19F-NMR saturation transfer difference spectroscopy, we reveal strong intermolecular cross-relaxation rate constants between 4-fluoropropofol and four different regions of NaChBac, including the activation gate and selectivity filter in the pore, the voltage sensing domain, and the S4-S5 linker. Unlike volatile anesthetics, 4-fluoropropofol does not bind to the extracellular interface of the pore domain. Collectively, our results show that propofol inhibits NaChBac at multiple sites, likely with distinct modes of action. This study provides a molecular basis for understanding the net inhibitory action of propofol on NaV channels.
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Affiliation(s)
- Yali Wang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Elaine Yang
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College and Jefferson College of Biomedical Sciences, Thomas Jefferson University, Philadelphia, PA
| | - Marta M Wells
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Vasyl Bondarenko
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Kellie Woll
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA
| | - Vincenzo Carnevale
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA
| | - Daniele Granata
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA
| | - Michael L Klein
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA
| | - William P Dailey
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA
| | - Manuel Covarrubias
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College and Jefferson College of Biomedical Sciences, Thomas Jefferson University, Philadelphia, PA
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Yan Xu
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA
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