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Liu F, Li T, Gong H, Tian F, Bai Y, Wang H, Yang C, Li Y, Guo F, Liu S, Chen Q. Structural insights into the molecular effects of the anthelmintics monepantel and betaine on the Caenorhabditis elegans acetylcholine receptor ACR-23. EMBO J 2024:10.1038/s44318-024-00165-7. [PMID: 39009676 DOI: 10.1038/s44318-024-00165-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 06/27/2024] [Accepted: 06/28/2024] [Indexed: 07/17/2024] Open
Abstract
Anthelmintics are drugs used for controlling pathogenic helminths in animals and plants. The natural compound betaine and the recently developed synthetic compound monepantel are both anthelmintics that target the acetylcholine receptor ACR-23 and its homologs in nematodes. Here, we present cryo-electron microscopy structures of ACR-23 in apo, betaine-bound, and betaine- and monepantel-bound states. We show that ACR-23 forms a homo-pentameric channel, similar to some other pentameric ligand-gated ion channels (pLGICs). While betaine molecules are bound to the classical neurotransmitter sites in the inter-subunit interfaces in the extracellular domain, monepantel molecules are bound to allosteric sites formed in the inter-subunit interfaces in the transmembrane domain of the receptor. Although the pore remains closed in betaine-bound state, monepantel binding results in an open channel by wedging into the cleft between the transmembrane domains of two neighboring subunits, which causes dilation of the ion conduction pore. By combining structural analyses with site-directed mutagenesis, electrophysiology and in vivo locomotion assays, we provide insights into the mechanism of action of the anthelmintics monepantel and betaine.
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Affiliation(s)
- Fenglian Liu
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Tianyu Li
- Shanghai Key Laboratory of Maternal Fetal Medicine, Shanghai Institute of Maternal-Fetal Medicine and Gynecologic Oncology, Department of Anesthesiology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 201204, China
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Huihui Gong
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Fei Tian
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Yan Bai
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Haowei Wang
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Chonglin Yang
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Yang Li
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - Fei Guo
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, 200040, China.
| | - Sheng Liu
- Institute of Pediatrics, Shenzhen Children's Hospital, Shenzhen, Guangdong Province, 518026, China.
- Department of Infectious Diseases, Shenzhen Children's Hospital, Shenzhen, Guangdong Province, 518038, China.
| | - Qingfeng Chen
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China.
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Wang YJ, Di XJ, Zhang PP, Chen X, Williams MP, Han DY, Nashmi R, Henderson BJ, Moss FJ, Mu TW. Hsp47 promotes biogenesis of multi-subunit neuroreceptors in the endoplasmic reticulum. eLife 2024; 13:e84798. [PMID: 38963323 PMCID: PMC11257679 DOI: 10.7554/elife.84798] [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: 11/18/2022] [Accepted: 05/21/2024] [Indexed: 07/05/2024] Open
Abstract
Protein homeostasis (proteostasis) deficiency is an important contributing factor to neurological and metabolic diseases. However, how the proteostasis network orchestrates the folding and assembly of multi-subunit membrane proteins is poorly understood. Previous proteomics studies identified Hsp47 (Gene: SERPINH1), a heat shock protein in the endoplasmic reticulum lumen, as the most enriched interacting chaperone for gamma-aminobutyric acid type A (GABAA) receptors. Here, we show that Hsp47 enhances the functional surface expression of GABAA receptors in rat neurons and human HEK293T cells. Furthermore, molecular mechanism study demonstrates that Hsp47 acts after BiP (Gene: HSPA5) and preferentially binds the folded conformation of GABAA receptors without inducing the unfolded protein response in HEK293T cells. Therefore, Hsp47 promotes the subunit-subunit interaction, the receptor assembly process, and the anterograde trafficking of GABAA receptors. Overexpressing Hsp47 is sufficient to correct the surface expression and function of epilepsy-associated GABAA receptor variants in HEK293T cells. Hsp47 also promotes the surface trafficking of other Cys-loop receptors, including nicotinic acetylcholine receptors and serotonin type 3 receptors in HEK293T cells. Therefore, in addition to its known function as a collagen chaperone, this work establishes that Hsp47 plays a critical and general role in the maturation of multi-subunit Cys-loop neuroreceptors.
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Affiliation(s)
- Ya-Juan Wang
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
| | - Xiao-Jing Di
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
| | - Pei-Pei Zhang
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
| | - Xi Chen
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
| | - Marnie P Williams
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
| | - Dong-Yun Han
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
| | - Raad Nashmi
- Department of Biology, University of VictoriaVictoriaCanada
| | - Brandon J Henderson
- Department of Biomedical Sciences, Marshall UniversityHuntingtonUnited States
| | - Fraser J Moss
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
| | - Ting-Wei Mu
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
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Krogman WL, Woodard T, McKay RSF. Anesthetic Mechanisms: Synergistic Interactions With Lipid Rafts and Voltage-Gated Sodium Channels. Anesth Analg 2024; 139:92-106. [PMID: 37968836 DOI: 10.1213/ane.0000000000006738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2023]
Abstract
Despite successfully utilizing anesthetics for over 150 years, the mechanism of action remains relatively unknown. Recent studies have shown promising results, but due to the complex interactions between anesthetics and their targets, there remains a clear need for further mechanistic research. We know that lipophilicity is directly connected to anesthetic potency since lipid solubility relates to anesthetic partition into the membrane. However, clinically relevant concentrations of anesthetics do not significantly affect lipid bilayers but continue to influence various molecular targets. Lipid rafts are derived from liquid-ordered phases of the plasma membrane that contain increased concentrations of cholesterol and sphingomyelin and act as staging platforms for membrane proteins, including ion channels. Although anesthetics do not perturb membranes at clinically relevant concentrations, they have recently been shown to target lipid rafts. In this review, we summarize current research on how different types of anesthetics-local, inhalational, and intravenous-bind and affect both lipid rafts and voltage-gated sodium channels, one of their major targets, and how those effects synergize to cause anesthesia and analgesia. Local anesthetics block voltage-gated sodium channel pores while also disrupting lipid packing in ordered membranes. Inhalational anesthetics bind to the channel pore and the voltage-sensing domain while causing an increase in the number, size, and diameter of lipid rafts. Intravenous anesthetics bind to the channel primarily at the voltage-sensing domain and the selectivity filter, while causing lipid raft perturbation. These changes in lipid nanodomain structure possibly give proteins access to substrates that have translocated as a result of these structural alterations, resulting in lipid-driven anesthesia. Overall, anesthetics can impact channel activity either through direct interaction with the channel, indirectly through the lipid raft, or both. Together, these result in decreased sodium ion flux into the cell, disrupting action potentials and producing anesthetic effects. However, more research is needed to elucidate the indirect mechanisms associated with channel disruption through the lipid raft, as not much is known about anionic lipid products and their influence over voltage-gated sodium channels. Anesthetics' effect on S-palmitoylation, a promising mechanism for direct and indirect influence over voltage-gated sodium channels, is another auspicious avenue of research. Understanding the mechanisms of different types of anesthetics will allow anesthesiologists greater flexibility and more specificity when treating patients.
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Affiliation(s)
- William L Krogman
- From the Department of Anesthesiology, University of Kansas School of Medicine - Wichita, Wichita, Kansas
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Parikh A, Krogman W, Walker J. The impact of volatile anesthetics and propofol on phosphatidylinositol 4,5-bisphosphate signaling. Arch Biochem Biophys 2024; 757:110045. [PMID: 38801966 DOI: 10.1016/j.abb.2024.110045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 04/29/2024] [Accepted: 05/24/2024] [Indexed: 05/29/2024]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PIP2), as well as other anionic phospholipids, play a pivotal role in various cellular processes, including ion channel regulation, receptor trafficking, and intracellular signaling pathways. The binding of volatile anesthetics and propofol to PIP2 leads to alterations in PIP2-mediated signaling causing modulation of ion channels such as ɣ-aminobutyric acid type A (GABAA) receptors, voltage-gated calcium channels, and potassium channels through various mechanisms. Additionally, the interaction between anionic phospholipids and G protein-coupled receptors plays a critical role in various anesthetic pathways, with these anesthetic-induced changes impacting PIP2 levels which cause cascading effects on receptor trafficking, including GABAA receptor internalization. This comprehensive review of various mechanisms of interaction provides insights into the intricate interplay between PIP2 signaling and anesthetic-induced changes, shedding light on the molecular mechanisms underlying anesthesia.
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Affiliation(s)
- Ayaan Parikh
- Wichita Collegiate School, Wichita, KS. 9115 E 13th St N, Wichita, KS, 67206, USA.
| | - William Krogman
- University of Kansas School of Medicine-Wichita, Wichita, KS, USA; Department of Anesthesiology, 929 N St Francis, Room 8079, Wichita, KS, 67214, USA
| | - James Walker
- University of Kansas School of Medicine-Wichita, Wichita, KS, USA; Department of Anesthesiology, 929 N St Francis, Room 8079, Wichita, KS, 67214, USA
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5
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Nemecz D, Nowak WA, Nemecz Á. VHH Nanobody Versatility against Pentameric Ligand-Gated Ion Channels. J Med Chem 2024; 67:8502-8518. [PMID: 38829690 PMCID: PMC11181324 DOI: 10.1021/acs.jmedchem.4c00231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/17/2024] [Accepted: 05/20/2024] [Indexed: 06/05/2024]
Abstract
Pentameric ligand-gated ion channels provide rapid chemical-electrical signal transmission between cells in the central and peripheral nervous system. Their dysfunction is associated with many nervous system disorders. They are composed of five identical (homomeric receptors) or homologous (heteromeric receptors) subunits. VHH nanobodies, or single-chain antibodies, are the variable domain, VHH, of antibodies that are composed of the heavy chain only from camelids. Their unique structure results in many specific biochemical and biophysical properties that make them an excellent alternative to conventional antibodies. This Perspective explores the published VHH nanobodies which have been isolated against pentameric ligand-gated ion channel subfamilies. It outlines the genetic and chemical modifications available to alter nanobody function. An assessment of the available functional and structural data indicate that it is feasible to create therapeutic agents and impart, through their modification, a given desired modulatory effect of its target receptor for current stoichiometric-specific VHH nanobodies.
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Affiliation(s)
- Dorota Nemecz
- Biochemistry
Department, Nicolaus Copernicus University
in Torun, 87-100 Torun, Poland
| | - Weronika A. Nowak
- Biochemistry
Department, Nicolaus Copernicus University
in Torun, 87-100 Torun, Poland
| | - Ákos Nemecz
- Biochemistry
Department, Nicolaus Copernicus University
in Torun, 87-100 Torun, Poland
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6
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Cao B, Xu Q, Shi Y, Zhao R, Li H, Zheng J, Liu F, Wan Y, Wei B. Pathology of pain and its implications for therapeutic interventions. Signal Transduct Target Ther 2024; 9:155. [PMID: 38851750 PMCID: PMC11162504 DOI: 10.1038/s41392-024-01845-w] [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: 05/12/2023] [Revised: 04/08/2024] [Accepted: 04/25/2024] [Indexed: 06/10/2024] Open
Abstract
Pain is estimated to affect more than 20% of the global population, imposing incalculable health and economic burdens. Effective pain management is crucial for individuals suffering from pain. However, the current methods for pain assessment and treatment fall short of clinical needs. Benefiting from advances in neuroscience and biotechnology, the neuronal circuits and molecular mechanisms critically involved in pain modulation have been elucidated. These research achievements have incited progress in identifying new diagnostic and therapeutic targets. In this review, we first introduce fundamental knowledge about pain, setting the stage for the subsequent contents. The review next delves into the molecular mechanisms underlying pain disorders, including gene mutation, epigenetic modification, posttranslational modification, inflammasome, signaling pathways and microbiota. To better present a comprehensive view of pain research, two prominent issues, sexual dimorphism and pain comorbidities, are discussed in detail based on current findings. The status quo of pain evaluation and manipulation is summarized. A series of improved and innovative pain management strategies, such as gene therapy, monoclonal antibody, brain-computer interface and microbial intervention, are making strides towards clinical application. We highlight existing limitations and future directions for enhancing the quality of preclinical and clinical research. Efforts to decipher the complexities of pain pathology will be instrumental in translating scientific discoveries into clinical practice, thereby improving pain management from bench to bedside.
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Affiliation(s)
- Bo Cao
- Department of General Surgery, First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
| | - Qixuan Xu
- Department of General Surgery, First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
- Medical School of Chinese PLA, Beijing, 100853, China
| | - Yajiao Shi
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, 100191, China
| | - Ruiyang Zhao
- Department of General Surgery, First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
- Medical School of Chinese PLA, Beijing, 100853, China
| | - Hanghang Li
- Department of General Surgery, First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
- Medical School of Chinese PLA, Beijing, 100853, China
| | - Jie Zheng
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, 100191, China
| | - Fengyu Liu
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, 100191, China.
| | - You Wan
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, 100191, China.
| | - Bo Wei
- Department of General Surgery, First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China.
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7
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Mortensen M, Bright DP, Fagotti J, Dorovykh V, Cerna B, Smart TG. Forty Years Searching for Neurosteroid Binding Sites on GABA A Receptors. Neuroscience 2024:S0306-4522(24)00257-4. [PMID: 38852898 DOI: 10.1016/j.neuroscience.2024.06.002] [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: 04/04/2024] [Revised: 05/31/2024] [Accepted: 06/03/2024] [Indexed: 06/11/2024]
Abstract
Brain inhibition is a vital process for controlling and sculpting the excitability of the central nervous system in healthy individuals. This level of control is provided over several timescales and involves the neurotransmitter GABA acting at inhibitory synapses to: rapidly inhibit neurons by activating the GABAA receptor; over a slower timescale, to tonically activate extrasynaptic GABAA receptors to provide a low level of background inhibition; and finally, to activate G-protein coupled GABAB receptors to control transmitter release by inhibiting presynaptic Ca2+ channels whilst providing postsynaptic inhibition via K+ channel activation. From this plethora of roles for GABA and its receptors, the GABAA receptor isoform is of major interest due to its dynamic functional plasticity, which in part, is due to being targeted by modulatory brain neurosteroids derived from sex and stress hormones. This family of neurosteroids can, depending on their structure, potentiate, activate and also inhibit the activity of GABAA receptors to affect brain inhibition. This review tracks the methods that have been deployed in probing GABAA receptors, and charts the sterling efforts made by several groups to locate the key neurosteroid binding sites that affect these important receptors. Increasing our knowledge of these binding sites will greatly facilitate our understanding of the physiological roles of neurosteroids and will help to advance their use as novel therapeutics to combat debilitating brain diseases.
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Affiliation(s)
- Martin Mortensen
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom
| | - Damian P Bright
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom
| | - Juliane Fagotti
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom
| | - Valentina Dorovykh
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom
| | - Barbora Cerna
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom
| | - Trevor G Smart
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom.
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López-Sánchez U, Munro LJ, Ladefoged LK, Pedersen AJ, Brun CC, Lyngby SM, Baud D, Juillan-Binard C, Pedersen MG, Lummis SCR, Bang-Andersen B, Schiøtt B, Chipot C, Schoehn G, Neyton J, Dehez F, Nury H, Kristensen AS. Structural determinants for activity of the antidepressant vortioxetine at human and rodent 5-HT 3 receptors. Nat Struct Mol Biol 2024:10.1038/s41594-024-01282-x. [PMID: 38698207 DOI: 10.1038/s41594-024-01282-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 03/19/2024] [Indexed: 05/05/2024]
Abstract
Vortioxetine (VTX) is a recently approved antidepressant that targets a variety of serotonin receptors. Here, we investigate the drug's molecular mechanism of operation at the serotonin 5-HT3 receptor (5-HT3R), which features two properties: VTX acts differently on rodent and human 5-HT3R, and VTX appears to suppress any subsequent response to agonists. Using a combination of cryo-EM, electrophysiology, voltage-clamp fluorometry and molecular dynamics, we show that VTX stabilizes a resting inhibited state of the mouse 5-HT3R and an agonist-bound-like state of human 5-HT3R, in line with the functional profile of the drug. We report four human 5-HT3R structures and show that the human receptor transmembrane domain is intrinsically fragile. We also explain the lack of recovery after VTX administration via a membrane partition mechanism.
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Affiliation(s)
- Uriel López-Sánchez
- University Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Lachlan Jake Munro
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | | | - Anders Juel Pedersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Christian Colding Brun
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Signe Meisner Lyngby
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Delphine Baud
- University Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | | | | | - Sarah C R Lummis
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | | | - Birgit Schiøtt
- Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - Christophe Chipot
- Université de Lorraine, CNRS, LPCT, Nancy, France
- Laboratoire International Associé CNRS and University of Illinois at Urbana-Champaign, Vandoeuvre-les-Nancy, France
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Guy Schoehn
- University Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Jacques Neyton
- University Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Francois Dehez
- Université de Lorraine, CNRS, LPCT, Nancy, France
- Laboratoire International Associé CNRS and University of Illinois at Urbana-Champaign, Vandoeuvre-les-Nancy, France
| | - Hugues Nury
- University Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France.
| | - Anders S Kristensen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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9
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Yuan Z, Pavel MA, Hansen SB. GABA and astrocytic cholesterol determine the lipid environment of GABA AR in cultured cortical neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.26.591395. [PMID: 38746110 PMCID: PMC11092523 DOI: 10.1101/2024.04.26.591395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The γ-aminobutyric acid (GABA) type A receptor (GABAAR), a GABA activated pentameric chloride channel, mediates fast inhibitory neurotransmission in the brain. The lipid environment is critical for GABAAR function. How lipids regulate the channel in the cell membrane is not fully understood. Here we employed super resolution imaging of lipids to demonstrate that the agonist GABA induces a rapid and reversible membrane translocation of GABAAR to phosphatidylinositol 4,5-bisphosphate (PIP2) clusters in mouse primary cortical neurons. This translocation relies on nanoscopic separation of PIP2 clusters and lipid rafts (cholesterol-dependent ganglioside clusters). In a resting state, the GABAAR associates with lipid rafts and this colocalization is enhanced by uptake of astrocytic secretions. These astrocytic secretions enhance endocytosis and delay desensitization. Our findings suggest intercellular signaling from astrocytes regulates GABAAR location based on lipid uptake in neurons. The findings have implications for treating mood disorders associated with altered neural excitability.
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Affiliation(s)
- Zixuan Yuan
- Department of Molecular Medicine, Department of Neuroscience, The Scripps Research Institute, Scripps, Jupiter, Florida 33458, USA
- Scripps Research Skaggs Graduate School of Chemical and Biological Science, The Scripps Research Institute, Scripps, Jupiter, Florida 33458, USA
| | - Mahmud Arif Pavel
- Department of Molecular Medicine, Department of Neuroscience, The Scripps Research Institute, Scripps, Jupiter, Florida 33458, USA
| | - Scott B. Hansen
- Department of Molecular Medicine, Department of Neuroscience, The Scripps Research Institute, Scripps, Jupiter, Florida 33458, USA
- Scripps Research Skaggs Graduate School of Chemical and Biological Science, The Scripps Research Institute, Scripps, Jupiter, Florida 33458, USA
- Department of Molecular Medicine, Department of Neuroscience, UF Scripps, Jupiter, Florida 33458, USA
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10
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Ananchenko A, Gao RY, Dehez F, Baenziger JE. State-dependent binding of cholesterol and an anionic lipid to the muscle-type Torpedo nicotinic acetylcholine receptor. Commun Biol 2024; 7:437. [PMID: 38600247 PMCID: PMC11006840 DOI: 10.1038/s42003-024-06106-8] [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: 08/28/2023] [Accepted: 03/25/2024] [Indexed: 04/12/2024] Open
Abstract
The ability of the Torpedo nicotinic acetylcholine receptor (nAChR) to undergo agonist-induced conformational transitions requires the presence of cholesterol and/or anionic lipids. Here we use recently solved structures along with multiscale molecular dynamics simulations to examine lipid binding to the nAChR in bilayers that have defined effects on nAChR function. We examine how phosphatidic acid and cholesterol, lipids that support conformational transitions, individually compete for binding with phosphatidylcholine, a lipid that does not. We also examine how the two lipids work synergistically to stabilize an agonist-responsive nAChR. We identify rapidly exchanging lipid binding sites, including both phospholipid sites with a high affinity for phosphatidic acid and promiscuous cholesterol binding sites in the grooves between adjacent transmembrane α-helices. A high affinity cholesterol site is confirmed in the inner leaflet framed by a key tryptophan residue on the MX α-helix. Our data provide insight into the dynamic nature of lipid-nAChR interactions and set the stage for a detailed understanding of the mechanisms by which lipids facilitate nAChR function at the neuromuscular junction.
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Affiliation(s)
- Anna Ananchenko
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Rui Yan Gao
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - François Dehez
- CNRS, LPCT, Université de Lorraine, F-54000 Nancy, France.
| | - John E Baenziger
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada.
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11
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Premageetha GT, Vinothkumar KR, Bose S. Exploring advances in single particle CryoEM with apoferritin: From blobs to true atomic resolution. Int J Biochem Cell Biol 2024; 169:106536. [PMID: 38307321 DOI: 10.1016/j.biocel.2024.106536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/21/2024] [Accepted: 01/23/2024] [Indexed: 02/04/2024]
Abstract
Deciphering the three-dimensional structures of macromolecules is of paramount importance for gaining insights into their functions and roles in human health and disease. Single particle cryoEM has emerged as a powerful technique that enables direct visualization of macromolecules and their complexes, and through subsequent averaging, achieve near atomic-level resolution. A major breakthrough was recently achieved with the determination of the apoferritin structure at true atomic resolution. In this review, we discuss the latest technological innovations across the entire single-particle workflow, which have been instrumental in driving the resolution revolution and in transforming cryoEM as a mainstream technique in structural biology. We illustrate these advancements using apoferritin as an example that has served as an excellent benchmark sample for assessing emerging technologies. We further explore whether the existing technology can routinely generate atomic structures of dynamic macromolecules that more accurately represent real-world samples, the limitations in the workflow, and the current approaches employed to overcome them.
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Affiliation(s)
- Gowtham ThambraRajan Premageetha
- Institute for Stem Cell Science and Regenerative Medicine, GKVK Post, Bangalore 560065, India; Manipal Academy of Higher Education, Tiger Circle Road, Manipal, Karnataka 576104, India.
| | - Kutti R Vinothkumar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Post, Bangalore 560065, India
| | - Sucharita Bose
- Institute for Stem Cell Science and Regenerative Medicine, GKVK Post, Bangalore 560065, India.
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12
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Witkin JM, Shafique H, Cerne R, Smith JL, Marini AM, Lipsky RH, Delery E. Mechanistic and therapeutic relationships of traumatic brain injury and γ-amino-butyric acid (GABA). Pharmacol Ther 2024; 256:108609. [PMID: 38369062 DOI: 10.1016/j.pharmthera.2024.108609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 01/18/2024] [Accepted: 02/01/2024] [Indexed: 02/20/2024]
Abstract
Traumatic brain injury (TBI) is a highly prevalent medical condition for which no medications specific for the prophylaxis or treatment of the condition as a whole exist. The spectrum of symptoms includes coma, headache, seizures, cognitive impairment, depression, and anxiety. Although it has been known for years that the inhibitory neurotransmitter γ-amino-butyric acid (GABA) is involved in TBI, no novel therapeutics based upon this mechanism have been introduced into clinical practice. We review the neuroanatomical, neurophysiological, neurochemical, and neuropharmacological relationships of GABA neurotransmission to TBI with a view toward new potential GABA-based medicines. The long-standing idea that excitatory and inhibitory (GABA and others) balances are disrupted by TBI is supported by the experimental data but has failed to invent novel methods of restoring this balance. The slow progress in advancing new treatments is due to the complexity of the disorder that encompasses multiple dynamically interacting biological processes including hemodynamic and metabolic systems, neurodegeneration and neurogenesis, major disruptions in neural networks and axons, frank brain lesions, and a multitude of symptoms that have differential neuronal and neurohormonal regulatory mechanisms. Although the current and ongoing clinical studies include GABAergic drugs, no novel GABA compounds are being explored. It is suggested that filling the gap in understanding the roles played by specific GABAA receptor configurations within specific neuronal circuits could help define new therapeutic approaches. Further research into the temporal and spatial delivery of GABA modulators should also be useful. Along with GABA modulation, research into the sequencing of GABA and non-GABA treatments will be needed.
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Affiliation(s)
- Jeffrey M Witkin
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent Hospital, Indianapolis, IN, USA; Departments of Neuroscience and Trauma Research, Ascension St. Vincent Hospital, Indianapolis, IN, USA; RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA.
| | | | - Rok Cerne
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent Hospital, Indianapolis, IN, USA; RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA; Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, IN, USA
| | - Jodi L Smith
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent Hospital, Indianapolis, IN, USA
| | - Ann M Marini
- Department of Neurology, Program in Neuroscience, and Molecular and Cellular Biology Program, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Robert H Lipsky
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Elizabeth Delery
- College of Osteopathic Medicine, Marian University, Indianapolis, IN, USA.
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13
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Tateiwa H, Evers AS. Neurosteroids and their potential as a safer class of general anesthetics. J Anesth 2024; 38:261-274. [PMID: 38252143 PMCID: PMC10954990 DOI: 10.1007/s00540-023-03291-4] [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: 10/31/2023] [Accepted: 11/25/2023] [Indexed: 01/23/2024]
Abstract
Neurosteroids (NS) are a class of steroids that are synthesized within the central nervous system (CNS). Various NS can either enhance or inhibit CNS excitability and they play important biological roles in brain development, brain function and as mediators of mood. One class of NS, 3α-hydroxy-pregnane steroids such as allopregnanolone (AlloP) or pregnanolone (Preg), inhibits neuronal excitability; these endogenous NS and their analogues have been therapeutically applied as anti-depressants, anti-epileptics and general anesthetics. While NS have many favorable properties as anesthetics (e.g. rapid onset, rapid recovery, minimal cardiorespiratory depression, neuroprotection), they are not currently in clinical use, largely due to problems with formulation. Recent advances in understanding NS mechanisms of action and improved formulations have rekindled interest in development of NS as sedatives and anesthetics. In this review, the synthesis of NS, and their mechanism of action will be reviewed with specific emphasis on their binding sites and actions on γ-aminobutyric acid type A (GABAA) receptors. The potential advantages of NS analogues as sedative and anesthetic agents will be discussed.
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Affiliation(s)
- Hiroki Tateiwa
- Department of Anesthesiology and Intensive Care Medicine, Kochi Medical School, Kochi, Japan
| | - Alex S Evers
- Department of Anesthesiology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA.
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14
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Cebi E, Lee J, Subramani VK, Bak N, Oh C, Kim KK. Cryo-electron microscopy-based drug design. Front Mol Biosci 2024; 11:1342179. [PMID: 38501110 PMCID: PMC10945328 DOI: 10.3389/fmolb.2024.1342179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/31/2024] [Indexed: 03/20/2024] Open
Abstract
Structure-based drug design (SBDD) has gained popularity owing to its ability to develop more potent drugs compared to conventional drug-discovery methods. The success of SBDD relies heavily on obtaining the three-dimensional structures of drug targets. X-ray crystallography is the primary method used for solving structures and aiding the SBDD workflow; however, it is not suitable for all targets. With the resolution revolution, enabling routine high-resolution reconstruction of structures, cryogenic electron microscopy (cryo-EM) has emerged as a promising alternative and has attracted increasing attention in SBDD. Cryo-EM offers various advantages over X-ray crystallography and can potentially replace X-ray crystallography in SBDD. To fully utilize cryo-EM in drug discovery, understanding the strengths and weaknesses of this technique and noting the key advancements in the field are crucial. This review provides an overview of the general workflow of cryo-EM in SBDD and highlights technical innovations that enable its application in drug design. Furthermore, the most recent achievements in the cryo-EM methodology for drug discovery are discussed, demonstrating the potential of this technique for advancing drug development. By understanding the capabilities and advancements of cryo-EM, researchers can leverage the benefits of designing more effective drugs. This review concludes with a discussion of the future perspectives of cryo-EM-based SBDD, emphasizing the role of this technique in driving innovations in drug discovery and development. The integration of cryo-EM into the drug design process holds great promise for accelerating the discovery of new and improved therapeutic agents to combat various diseases.
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Affiliation(s)
| | | | | | | | - Changsuk Oh
- Department of Precision Medicine, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Kyeong Kyu Kim
- Department of Precision Medicine, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
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15
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Burgess SG, Paul NR, Richards MW, Ault JR, Askenatzis L, Claydon SG, Corbyn R, Machesky LM, Bayliss R. A nanobody inhibitor of Fascin-1 actin-bundling activity and filopodia formation. Open Biol 2024; 14:230376. [PMID: 38503329 PMCID: PMC10960945 DOI: 10.1098/rsob.230376] [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: 10/13/2023] [Accepted: 01/16/2024] [Indexed: 03/21/2024] Open
Abstract
Fascin-1-mediated actin-bundling activity is central to the generation of plasma membrane protrusions required for cell migration. Dysregulated formation of cellular protrusions is observed in metastatic cancers, where they are required for increased invasiveness, and is often correlated with increased Fascin-1 abundance. Therefore, there is interest in generating therapeutic Fascin-1 inhibitors. We present the identification of Nb 3E11, a nanobody inhibitor of Fascin-1 actin-bundling activity and filopodia formation. The crystal structure of the Fascin-1/Nb 3E11 complex reveals the structural mechanism of inhibition. Nb 3E11 occludes an actin-binding site on the third β-trefoil domain of Fascin-1 that is currently not targeted by chemical inhibitors. Binding of Nb 3E11 to Fascin-1 induces a conformational change in the adjacent domains to stabilize Fascin-1 in an inhibitory state similar to that adopted in the presence of small-molecule inhibitors. Nb 3E11 could be used as a tool inhibitor molecule to aid in the development of Fascin-1 targeted therapeutics.
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Affiliation(s)
- Selena G. Burgess
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Nikki R. Paul
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Mark W. Richards
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - James R. Ault
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Laurie Askenatzis
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Sophie G. Claydon
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Ryan Corbyn
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Laura M. Machesky
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1QH, UK
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Richard Bayliss
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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16
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Sharmin D, Divović B, Ping X, Cerne R, Smith JL, Rezvanian S, Mondal P, Meyer MJ, Kiley ME, Arnold LA, Mian MY, Pandey KP, Jin X, Mitrović JR, Djorović D, Lippa A, Cook JM, Golani LK, Scholze P, Savić MM, Witkin JM. New Imidazodiazepine Analogue, 5-(8-Bromo-6-(pyridin-2-yl)-4 H-benzo[ f]imidazo[1,5- a][1,4]diazepin-3-yl)oxazole, Provides a Simplified Synthetic Scheme, High Oral Plasma and Brain Exposures, and Produces Antiseizure Efficacy in Mice, and Antiepileptogenic Activity in Neural Networks in Brain Slices from a Patient with Mesial Temporal Lobe Epilepsy. ACS Chem Neurosci 2024; 15:517-526. [PMID: 38175916 DOI: 10.1021/acschemneuro.3c00555] [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] [Indexed: 01/06/2024] Open
Abstract
KRM-II-81 (1) is an imidazodiazepine GABAA receptor (GABAAR) potentiator with broad antiseizure efficacy and a low sedative burden. A brominated analogue, DS-II-73 (5), was synthesized and pharmacologically characterized as a potential backup compound as KRM-II-81 moves forward into development. The synthesis from 2-amino-5-bromophenyl)(pyridin-2yl)methanone (6) was processed in five steps with an overall yield of 38% and without the need for a palladium catalyst. GABAAR binding occurred with a Ki of 150 nM, and only 3 of 41 screened binding sites produced inhibition ≥50% at 10 μM, and the potency to induce cytotoxicity was ≥240 mM. DS-II-73 was selective for α2/3/5- over that of α1-containing GABAARs. Oral exposure of plasma and brain of rats was more than sufficient to functionally impact GABAARs. Tonic convulsions in mice and lethality induced by pentylenetetrazol were suppressed by DS-II-73 after oral administration and latencies to clonic and tonic seizures were prolonged. Cortical slice preparations from a patient with pharmacoresistant epilepsy (mesial temporal lobe) showed decreases in the frequency of local field potentials by DS-II-73. As with KRM-II-81, the motor-impairing effects of DS-II-73 were low compared to diazepam. Molecular docking studies of DS-II-73 with the α1β3γ2L-configured GABAAR showed low interaction with α1His102 that is suggested as a potential molecular mechanism for its low sedative side effects. These findings support the viability of DS-II-73 as a backup molecule for its ethynyl analogue, KRM-II-81, with the human tissue data providing translational credibility.
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Affiliation(s)
- Dishary Sharmin
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Branka Divović
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade 11221, Serbia
| | - Xingjie Ping
- Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, Indiana 46202, United States
| | - Rok Cerne
- Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, Indiana 46202, United States
- Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana 46260, United States
- RespireRx Pharmaceuticals Inc, Glen Rock, New Jersey 07452, United States
- Faculty of Medicine, University of Ljubljana, Zaloška cesta 4, Ljubljana 1000, Slovenia
| | - Jodi L Smith
- Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana 46260, United States
| | - Sepideh Rezvanian
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Prithu Mondal
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Michelle Jean Meyer
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Molly E Kiley
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Leggy A Arnold
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Md Yeunus Mian
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Kamal P Pandey
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Xiaoming Jin
- Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, Indiana 46202, United States
| | - Jelena R Mitrović
- Department of Pharmaceutical Technology and Cosmetology, Faculty of Pharmacy, University of Belgrade, Belgrade 11221, Serbia
| | - Djordje Djorović
- Institute of Anatomy, School of Medicine, University of Belgrade, Belgrade 11221, Serbia
| | - Arnold Lippa
- RespireRx Pharmaceuticals Inc, Glen Rock, New Jersey 07452, United States
| | - James M Cook
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
- RespireRx Pharmaceuticals Inc, Glen Rock, New Jersey 07452, United States
| | - Lalit K Golani
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna 1090, Austria
| | - Miroslav M Savić
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade 11221, Serbia
| | - Jeffrey M Witkin
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
- Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana 46260, United States
- RespireRx Pharmaceuticals Inc, Glen Rock, New Jersey 07452, United States
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17
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Condeminas M, Macias MJ. Overcoming challenges in structural biology with integrative approaches and nanobody-derived technologies. Curr Opin Struct Biol 2024; 84:102764. [PMID: 38215529 DOI: 10.1016/j.sbi.2023.102764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/24/2023] [Accepted: 12/11/2023] [Indexed: 01/14/2024]
Abstract
A full understanding of protein structure is key to unraveling how these systems work, how mutations affect their function, and discovering new hotspots for drug discovery. Research tackling this field began with the analysis of globular proteins. In recent years, as technology has improved, research efforts have broadened their focus to include the study of multidomain proteins and the analysis of conformational variability, flexibility, and dynamic systems. Here, we have selected five recent examples that integrate complementary structural methods to provide insight into the behavior of modular, flexible, and transient contacts. We also describe the structural application of domains derived from single-chain antibodies, which are instrumental in overcoming the size limitation of cryogenic electron microscopy (cryoEM) studies. As these methods are continuously developed, they will lead to the interrogation of more complex systems, revealing how large signaling and transcriptional machines are assembled in the context of health and disease.
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Affiliation(s)
- Miriam Condeminas
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Carrer de Baldiri Reixac 10, Barcelona 08028, Spain; Department of Medicine and Life Sciences, Universitat Pompeu Fabra (MELIS-UPF), Carrer del Doctor Aiguader 88, Barcelona 08003, Spain
| | - Maria J Macias
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Carrer de Baldiri Reixac 10, Barcelona 08028, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, Barcelona 08010, Spain.
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18
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Bergh C, Rovšnik U, Howard R, Lindahl E. Discovery of lipid binding sites in a ligand-gated ion channel by integrating simulations and cryo-EM. eLife 2024; 12:RP86016. [PMID: 38289224 PMCID: PMC10945520 DOI: 10.7554/elife.86016] [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] [Indexed: 02/01/2024] Open
Abstract
Ligand-gated ion channels transduce electrochemical signals in neurons and other excitable cells. Aside from canonical ligands, phospholipids are thought to bind specifically to the transmembrane domain of several ion channels. However, structural details of such lipid contacts remain elusive, partly due to limited resolution of these regions in experimental structures. Here, we discovered multiple lipid interactions in the channel GLIC by integrating cryo-electron microscopy and large-scale molecular simulations. We identified 25 bound lipids in the GLIC closed state, a conformation where none, to our knowledge, were previously known. Three lipids were associated with each subunit in the inner leaflet, including a buried interaction disrupted in mutant simulations. In the outer leaflet, two intrasubunit sites were evident in both closed and open states, while a putative intersubunit site was preferred in open-state simulations. This work offers molecular details of GLIC-lipid contacts particularly in the ill-characterized closed state, testable hypotheses for state-dependent binding, and a multidisciplinary strategy for modeling protein-lipid interactions.
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Affiliation(s)
- Cathrine Bergh
- Science for Life Laboratory & Swedish e-Science Research Center, Department of Applied Physics, KTH Royal Institute of TechnologyStockholmSweden
| | - Urška Rovšnik
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm UniversityStockholmSweden
| | - Rebecca Howard
- Science for Life Laboratory & Swedish e-Science Research Center, Department of Applied Physics, KTH Royal Institute of TechnologyStockholmSweden
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm UniversityStockholmSweden
| | - Erik Lindahl
- Science for Life Laboratory & Swedish e-Science Research Center, Department of Applied Physics, KTH Royal Institute of TechnologyStockholmSweden
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm UniversityStockholmSweden
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19
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Dalal V, Arcario MJ, Petroff JT, Tan BK, Dietzen NM, Rau MJ, Fitzpatrick JAJ, Brannigan G, Cheng WWL. Lipid nanodisc scaffold and size alter the structure of a pentameric ligand-gated ion channel. Nat Commun 2024; 15:25. [PMID: 38167383 PMCID: PMC10762164 DOI: 10.1038/s41467-023-44366-w] [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: 11/20/2022] [Accepted: 12/11/2023] [Indexed: 01/05/2024] Open
Abstract
Lipid nanodiscs have become a standard tool for studying membrane proteins, including using single particle cryo-electron microscopy (cryo-EM). We find that reconstituting the pentameric ligand-gated ion channel (pLGIC), Erwinia ligand-gated ion channel (ELIC), in different nanodiscs produces distinct structures by cryo-EM. The effect of the nanodisc on ELIC structure extends to the extracellular domain and agonist binding site. Additionally, molecular dynamic simulations indicate that nanodiscs of different size impact ELIC structure and that the nanodisc scaffold directly interacts with ELIC. These findings suggest that the nanodisc plays a crucial role in determining the structure of pLGICs, and that reconstitution of ion channels in larger nanodiscs may better approximate a lipid membrane environment.
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Affiliation(s)
- Vikram Dalal
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Mark J Arcario
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - John T Petroff
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Brandon K Tan
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Noah M Dietzen
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Michael J Rau
- Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO, USA
| | - James A J Fitzpatrick
- Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO, USA
| | - Grace Brannigan
- Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, USA
- Department of Physics, Rutgers University, Camden, NJ, USA
| | - Wayland W L Cheng
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA.
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20
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Wu H, Smalinskaitė L, Hegde RS. EMC rectifies the topology of multipass membrane proteins. Nat Struct Mol Biol 2024; 31:32-41. [PMID: 37957425 PMCID: PMC10803268 DOI: 10.1038/s41594-023-01120-6] [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: 04/25/2023] [Accepted: 09/08/2023] [Indexed: 11/15/2023]
Abstract
Most eukaryotic multipass membrane proteins are inserted into the membrane of the endoplasmic reticulum. Their transmembrane domains (TMDs) are thought to be inserted co-translationally as they emerge from a membrane-bound ribosome. Here we find that TMDs near the carboxyl terminus of mammalian multipass proteins are inserted post-translationally by the endoplasmic reticulum membrane protein complex (EMC). Site-specific crosslinking shows that the EMC's cytosol-facing hydrophilic vestibule is adjacent to a pre-translocated C-terminal tail. EMC-mediated insertion is mostly agnostic to TMD hydrophobicity, favored for short uncharged C-tails and stimulated by a preceding unassembled TMD bundle. Thus, multipass membrane proteins can be released by the ribosome-translocon complex in an incompletely inserted state, requiring a separate EMC-mediated post-translational insertion step to rectify their topology, complete biogenesis and evade quality control. This sequential co-translational and post-translational mechanism may apply to ~250 diverse multipass proteins, including subunits of the pentameric ion channel family that are crucial for neurotransmission.
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Affiliation(s)
- Haoxi Wu
- MRC Laboratory of Molecular Biology, Cambridge, UK
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21
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Hernandez CC, Hu N, Shen W, Macdonald RL. Epileptic Encephalopathy GABRB Structural Variants Share Common Gating and Trafficking Defects. Biomolecules 2023; 13:1790. [PMID: 38136660 PMCID: PMC10741827 DOI: 10.3390/biom13121790] [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: 11/20/2023] [Revised: 12/08/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Variants in the GABRB gene, which encodes the β subunit of the GABAA receptor, have been implicated in various epileptic encephalopathies and related neurodevelopmental disorders such as Dravet syndrome and Angelman syndrome. These conditions are often associated with early-onset seizures, developmental regression, and cognitive impairments. The severity and specific features of these encephalopathies can differ based on the nature of the genetic variant and its impact on GABAA receptor function. These variants can lead to dysfunction in GABAA receptor-mediated inhibition, resulting in an imbalance between neuronal excitation and inhibition that contributes to the development of seizures. Here, 13 de novo EE-associated GABRB variants, occurring as missense mutations, were analyzed to determine their impact on protein stability and flexibility, channel function, and receptor biogenesis. Our results showed that all mutations studied significantly impact the protein structure, altering protein stability, flexibility, and function to varying degrees. Variants mapped to the GABA-binding domain, coupling zone, and pore domain significantly impact the protein structure, modifying the β+/α- interface of the receptor and altering channel activation and receptor trafficking. Our study proposes that the extent of loss or gain of GABAA receptor function can be elucidated by identifying the specific structural domain impacted by mutation and assessing the variability in receptor structural dynamics. This paves the way for future studies to explore and uncover links between the incidence of a variant in the receptor topology and the severity of the related disease.
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Affiliation(s)
- Ciria C. Hernandez
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ningning Hu
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (N.H.); (W.S.); (R.L.M.)
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (N.H.); (W.S.); (R.L.M.)
| | - Robert L. Macdonald
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (N.H.); (W.S.); (R.L.M.)
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22
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Schaefer N, Harvey RJ, Villmann C. Startle Disease: New Molecular Insights into an Old Neurological Disorder. Neuroscientist 2023; 29:767-781. [PMID: 35754344 PMCID: PMC10623600 DOI: 10.1177/10738584221104724] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Startle disease (SD) is characterized by enhanced startle responses, generalized muscle stiffness, unexpected falling, and fatal apnea episodes due to disturbed feedback inhibition in the spinal cord and brainstem of affected individuals. Mutations within the glycine receptor (GlyR) subunit and glycine transporter 2 (GlyT2) genes have been identified in individuals with SD. Impaired inhibitory neurotransmission in SD is due to pre- and/or postsynaptic GlyR or presynaptic GlyT2 dysfunctions. Previous research has focused on mutated GlyRs and GlyT2 that impair ion channel/transporter function or trafficking. With insights provided by recently solved cryo-electron microscopy and X-ray structures of GlyRs, a detailed picture of structural transitions important for receptor gating has emerged, allowing a deeper understanding of SD at the molecular level. Moreover, studies on novel SD mutations have demonstrated a higher complexity of SD, with identification of additional clinical signs and symptoms and interaction partners representing key players for fine-tuning synaptic processes. Although our knowledge has steadily improved during the last years, changes in synaptic localization and GlyR or GlyT2 homeostasis under disease conditions are not yet completely understood. Combined proteomics, interactomics, and high-resolution microscopy techniques are required to reveal alterations in receptor dynamics at the synaptic level under disease conditions.
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Affiliation(s)
- Natascha Schaefer
- Institute of Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Robert J. Harvey
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Maroochydore DC, Australia
- Sunshine Coast Health Institute, Birtinya, Australia
| | - Carmen Villmann
- Institute of Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, Würzburg, Germany
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23
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Wang YJ, Vu GH, Mu TW. Pathogenicity Prediction of GABA A Receptor Missense Variants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.14.567135. [PMID: 38014242 PMCID: PMC10680766 DOI: 10.1101/2023.11.14.567135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Variants in the genes encoding the subunits of gamma-aminobutyric acid type A (GABA A ) receptors are associated with epilepsy. To date, over 1000 clinical variants have been identified in these genes. However, the majority of these variants lack functional studies and their clinical significance is uncertain although accumulating evidence indicates that proteostasis deficiency is the major disease-causing mechanism for GABA A receptor variants. Here, we apply two state-of-the-art modeling tools, namely AlphaMissense, which uses an artificial intelligence-based approach based on AlphaFold structures, and Rhapsody, which integrates sequence evolution and known structure-based data, to predict the pathogenicity of saturating missense variants in genes that encode the major subunits of GABA A receptors in the central nervous system, including GABRA1 , GABRB2 , GABRB3 , and GABRG2 . Our results demonstrate that the predicted pathogenicity correlates well between AlphaMissense and Rhapsody although AlphaMissense tends to generate higher pathogenic probability. Furthermore, almost all annotated pathogenic variants in the ClinVar clinical database are successfully identified from the prediction, whereas uncertain variants from ClinVar partially due to the lack of experimental data are differentiated into different pathogenicity groups. The pathogenicity prediction of GABA A receptor missense variants provides a resource to the community as well as guidance for future experimental and clinical investigations.
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24
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Cowgill J, Fan C, Haloi N, Tobiasson V, Zhuang Y, Howard RJ, Lindahl E. Structure and dynamics of differential ligand binding in the human ρ-type GABA A receptor. Neuron 2023; 111:3450-3464.e5. [PMID: 37659407 DOI: 10.1016/j.neuron.2023.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 08/01/2023] [Accepted: 08/07/2023] [Indexed: 09/04/2023]
Abstract
The neurotransmitter γ-aminobutyric acid (GABA) drives critical inhibitory processes in and beyond the nervous system, partly via ionotropic type-A receptors (GABAARs). Pharmacological properties of ρ-type GABAARs are particularly distinctive, yet the structural basis for their specialization remains unclear. Here, we present cryo-EM structures of a lipid-embedded human ρ1 GABAAR, including a partial intracellular domain, under apo, inhibited, and desensitized conditions. An apparent resting state, determined first in the absence of modulators, was recapitulated with the specific inhibitor (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid and blocker picrotoxin and provided a rationale for bicuculline insensitivity. Comparative structures, mutant recordings, and molecular simulations with and without GABA further explained the sensitized but slower activation of ρ1 relative to canonical subtypes. Combining GABA with picrotoxin also captured an apparent uncoupled intermediate state. This work reveals structural mechanisms of gating and modulation with applications to ρ-specific pharmaceutical design and to our biophysical understanding of ligand-gated ion channels.
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Affiliation(s)
- John Cowgill
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden
| | - Chen Fan
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden
| | - Nandan Haloi
- Department of Applied Physics, SciLifeLab, KTH Royal Institute of Technology, 17121 Solna, Sweden
| | - Victor Tobiasson
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden
| | - Yuxuan Zhuang
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden
| | - Rebecca J Howard
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden.
| | - Erik Lindahl
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden; Department of Applied Physics, SciLifeLab, KTH Royal Institute of Technology, 17121 Solna, Sweden.
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25
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Hannan SB, Penzinger R, Mickute G, Smart TG. CGP7930 - An allosteric modulator of GABA BRs, GABA ARs and inwardly-rectifying potassium channels. Neuropharmacology 2023; 238:109644. [PMID: 37422181 PMCID: PMC10951960 DOI: 10.1016/j.neuropharm.2023.109644] [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: 03/22/2022] [Revised: 06/01/2023] [Accepted: 06/22/2023] [Indexed: 07/10/2023]
Abstract
Type-A and -B GABA receptors (GABAARs/GABABRs) control brain function and behaviour by fine tuning neurotransmission. Over-time these receptors have become important therapeutic targets for treating neurodevelopmental and neuropsychiatric disorders. Several positive allosteric modulators (PAMs) of GABARs have reached the clinic and selective targeting of receptor subtypes is crucial. For GABABRs, CGP7930 is a widely used PAM for in vivo studies, but its full pharmacological profile has not yet been established. Here, we reveal that CGP7930 has multiple effects not only on GABABRs but also GABAARs, which for the latter involves potentiation of GABA currents, direct receptor activation, and also inhibition. Furthermore, at higher concentrations, CGP7930 also blocks G protein-coupled inwardly-rectifying K+ (GIRK) channels diminishing GABABR signalling in HEK 293 cells. In male and female rat hippocampal neuron cultures, CGP7930 allosteric effects on GABAARs caused prolonged rise and decay times and reduced the frequency of inhibitory postsynaptic currents and potentiated GABAAR-mediated tonic inhibition. Additional comparison between predominant synaptic- and extrasynaptic-isoforms of GABAAR indicated no evident subtype selectivity for CGP7930. In conclusion, our study of CGP7930 modulation of GABAARs, GABABRs and GIRK channels, indicates this compound is unsuitable for use as a specific GABABR PAM.
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Affiliation(s)
- Saad B Hannan
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
| | - Reka Penzinger
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Ginte Mickute
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Trevor G Smart
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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26
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Mortensen M, Xu Y, Shehata MA, Krall J, Ernst M, Frølund B, Smart TG. Pregnenolone sulfate analogues differentially modulate GABA A receptor closed/desensitised states. Br J Pharmacol 2023; 180:2482-2499. [PMID: 37194503 PMCID: PMC10952582 DOI: 10.1111/bph.16143] [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: 06/07/2021] [Revised: 02/07/2023] [Accepted: 05/05/2023] [Indexed: 05/18/2023] Open
Abstract
BACKGROUND AND PURPOSE GABAA receptors are regulated by numerous classes of allosteric modulators. However, regulation of receptor macroscopic desensitisation remains largely unexplored and may offer new therapeutic opportunities. Here, we report the emerging potential for modulating desensitisation with analogues of the endogenous inhibitory neurosteroid, pregnenolone sulfate. EXPERIMENTAL APPROACH New pregnenolone sulfate analogues were synthesised incorporating various heterocyclic substitutions located at the C-21 position on ring D. The pharmacological profiles of these compounds were assessed using electrophysiology and recombinant GABAA receptors together with mutagenesis, molecular dynamics simulations, structural modelling and kinetic simulations. KEY RESULTS All seven analogues retained a negative allosteric modulatory capability whilst exhibiting diverse potencies. Interestingly, we observed differential effects on GABA current decay by compounds incorporating either a six- (compound 5) or five-membered heterocyclic ring (compound 6) on C-21, which was independent of their potencies as inhibitors. We propose that differences in molecular charges, and the targeted binding of analogues to specific states of the GABAA receptor, are the most likely cause of the distinctive functional profiles. CONCLUSIONS AND IMPLICATIONS Our findings reveal that heterocyclic addition to inhibitory neurosteroids not only affected their potency and macroscopic efficacy but also affected innate receptor mechanisms that underlie desensitisation. Acute modulation of macroscopic desensitisation will determine the degree and duration of GABA inhibition, which are vital for the integration of neural circuit activity. Discovery of this form of modulation could present an opportunity for next-generation GABAA receptor drug design and development.
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Affiliation(s)
- Martin Mortensen
- Department of Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUK
| | - Yue Xu
- Department of Drug Design and Pharmacology, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Mohamed A. Shehata
- Department of Drug Design and Pharmacology, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Jacob Krall
- Department of Drug Design and Pharmacology, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
- Present address:
Xellia Pharmaceuticals ApSCopenhagenDenmark
| | - Margot Ernst
- Department of Pathology of the Nervous System, Center for Brain ResearchMedical University of ViennaViennaAustria
| | - Bente Frølund
- Department of Drug Design and Pharmacology, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Trevor G. Smart
- Department of Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUK
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27
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Mohamad FH, Mohamad Jamali MA, Che Has AT. Structure-function Studies of GABA (A) Receptors and Related computer-aided Studies. J Mol Neurosci 2023; 73:804-817. [PMID: 37750966 DOI: 10.1007/s12031-023-02158-3] [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: 08/03/2023] [Accepted: 09/12/2023] [Indexed: 09/27/2023]
Abstract
The γ-aminobutyric acid type A receptor (GABA (A) receptor) is a membrane protein activated by the neurotransmitter GABA. Structurally, this major inhibitory neurotransmitter receptor in the human central nervous system is a pentamer that can be built from a selection of 19 subunits consisting of α(1,2,3,4,5 or 6), β (1,2 or 3), γ (1,2 or 3), ρ (1,2 or 3), and δ, π, θ, and ε. This creates several possible pentameric arrangements, which also influence the pharmacological and physiological properties of the receptor. The complexity and heterogeneity of the receptors are further increased by the addition of short and long splice variants in several subunits and the existence of multiple allosteric binding sites and expansive ligands that can bind to the receptors. Therefore, a comprehensive understanding of the structure and function of the receptors is required to gain novel insights into the consequences of receptor dysfunction and subsequent drug development studies. Notably, advancements in computational-aided studies have facilitated the elucidation of residual interactions and exploring energy binding, which may otherwise be challenging to investigate. In this review, we aim to summarize the current understanding of the structure and function of GABA (A) receptors obtained from advancements in computational-aided applications.
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Affiliation(s)
- Fatin H Mohamad
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, 16150 Kota Bharu, Kelantan, Malaysia
| | - Muhamad Arif Mohamad Jamali
- Faculty of Science and Technology, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800, Nilai, Negeri Sembilan, Malaysia
| | - Ahmad Tarmizi Che Has
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, 16150 Kota Bharu, Kelantan, Malaysia.
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28
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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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29
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Sun C, Zhu H, Clark S, Gouaux E. Cryo-EM structures reveal native GABA A receptor assemblies and pharmacology. Nature 2023; 622:195-201. [PMID: 37730991 PMCID: PMC10550821 DOI: 10.1038/s41586-023-06556-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 08/21/2023] [Indexed: 09/22/2023]
Abstract
Type A γ-aminobutyric acid receptors (GABAARs) are the principal inhibitory receptors in the brain and the target of a wide range of clinical agents, including anaesthetics, sedatives, hypnotics and antidepressants1-3. However, our understanding of GABAAR pharmacology has been hindered by the vast number of pentameric assemblies that can be derived from 19 different subunits4 and the lack of structural knowledge of clinically relevant receptors. Here, we isolate native murine GABAAR assemblies containing the widely expressed α1 subunit and elucidate their structures in complex with drugs used to treat insomnia (zolpidem (ZOL) and flurazepam) and postpartum depression (the neurosteroid allopregnanolone (APG)). Using cryo-electron microscopy (cryo-EM) analysis and single-molecule photobleaching experiments, we uncover three major structural populations in the brain: the canonical α1β2γ2 receptor containing two α1 subunits, and two assemblies containing one α1 and either an α2 or α3 subunit, in which the single α1-containing receptors feature a more compact arrangement between the transmembrane and extracellular domains. Interestingly, APG is bound at the transmembrane α/β subunit interface, even when not added to the sample, revealing an important role for endogenous neurosteroids in modulating native GABAARs. Together with structurally engaged lipids, neurosteroids produce global conformational changes throughout the receptor that modify the ion channel pore and the binding sites for GABA and insomnia medications. Our data reveal the major α1-containing GABAAR assemblies, bound with endogenous neurosteroid, thus defining a structural landscape from which subtype-specific drugs can be developed.
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Affiliation(s)
- Chang Sun
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Hongtao Zhu
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Sarah Clark
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, USA
| | - Eric Gouaux
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA.
- Howard Hughes Medical Institute, Oregon Health and Science University, Portland, OR, USA.
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30
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Gu S, Huang M, Handel TM. On-bead purification and nanodisc reconstitution of human chemokine receptor complexes for structural and biophysical studies. STAR Protoc 2023; 4:102460. [PMID: 37516969 PMCID: PMC10407235 DOI: 10.1016/j.xpro.2023.102460] [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: 04/12/2023] [Revised: 06/02/2023] [Accepted: 06/23/2023] [Indexed: 08/01/2023] Open
Abstract
Chemokine receptors, a subfamily of G-protein-coupled receptors (GPCRs), are responsible for cell migration during physiological processes as well as in diseases like inflammation and cancers. Here, we present a protocol for solubilizing, purifying, and reconstituting complexes of chemokine receptors with their ligands in "nanodiscs," soluble lipid bilayers that mimic the native environment of membrane receptors. The protocol yields chemokine receptor complexes with sufficient purity and yield for structural and biophysical studies and should be applicable to other GPCRs.
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Affiliation(s)
- Siyi Gu
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, San Diego, CA 92093, USA.
| | - Mian Huang
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, San Diego, CA 92093, USA
| | - Tracy M Handel
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, San Diego, CA 92093, USA.
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31
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Legesse DH, Fan C, Teng J, Zhuang Y, Howard RJ, Noviello CM, Lindahl E, Hibbs RE. Structural insights into opposing actions of neurosteroids on GABA A receptors. Nat Commun 2023; 14:5091. [PMID: 37607940 PMCID: PMC10444788 DOI: 10.1038/s41467-023-40800-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/10/2023] [Indexed: 08/24/2023] Open
Abstract
γ-Aminobutyric acid type A (GABAA) receptors mediate fast inhibitory signaling in the brain and are targets of numerous drugs and endogenous neurosteroids. A subset of neurosteroids are GABAA receptor positive allosteric modulators; one of these, allopregnanolone, is the only drug approved specifically for treating postpartum depression. There is a consensus emerging from structural, physiological and photolabeling studies as to where positive modulators bind, but how they potentiate GABA activation remains unclear. Other neurosteroids are negative modulators of GABAA receptors, but their binding sites remain debated. Here we present structures of a synaptic GABAA receptor bound to allopregnanolone and two inhibitory sulfated neurosteroids. Allopregnanolone binds at the receptor-bilayer interface, in the consensus potentiator site. In contrast, inhibitory neurosteroids bind in the pore. MD simulations and electrophysiology support a mechanism by which allopregnanolone potentiates channel activity and suggest the dominant mechanism for sulfated neurosteroid inhibition is through pore block.
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Affiliation(s)
| | - Chen Fan
- Dept. of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Jinfeng Teng
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
| | - Yuxuan Zhuang
- Dept. of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Rebecca J Howard
- Dept. of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Colleen M Noviello
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
| | - Erik Lindahl
- Dept. of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden.
- Dept. of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden.
| | - Ryan E Hibbs
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, USA.
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA.
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32
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Zupancic JM, Smith MD, Trzeciakiewicz H, Skinner ME, Ferris SP, Makowski EK, Lucas MJ, McArthur N, Kane RS, Paulson HL, Tessier PM. Quantitative flow cytometric selection of tau conformational nanobodies specific for pathological aggregates. Front Immunol 2023; 14:1164080. [PMID: 37622125 PMCID: PMC10445546 DOI: 10.3389/fimmu.2023.1164080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 05/15/2023] [Indexed: 08/26/2023] Open
Abstract
Single-domain antibodies, also known as nanobodies, are broadly important for studying the structure and conformational states of several classes of proteins, including membrane proteins, enzymes, and amyloidogenic proteins. Conformational nanobodies specific for aggregated conformations of amyloidogenic proteins are particularly needed to better target and study aggregates associated with a growing class of associated diseases, especially neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. However, there are few reported nanobodies with both conformational and sequence specificity for amyloid aggregates, especially for large and complex proteins such as the tau protein associated with Alzheimer's disease, due to difficulties in selecting nanobodies that bind to complex aggregated proteins. Here, we report the selection of conformational nanobodies that selectively recognize aggregated (fibrillar) tau relative to soluble (monomeric) tau. Notably, we demonstrate that these nanobodies can be directly isolated from immune libraries using quantitative flow cytometric sorting of yeast-displayed libraries against tau aggregates conjugated to quantum dots, and this process eliminates the need for secondary nanobody screening. The isolated nanobodies demonstrate conformational specificity for tau aggregates in brain samples from both a transgenic mouse model and human tauopathies. We expect that our facile approach will be broadly useful for isolating conformational nanobodies against diverse amyloid aggregates and other complex antigens.
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Affiliation(s)
- Jennifer M. Zupancic
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
| | - Matthew D. Smith
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
| | - Hanna Trzeciakiewicz
- Department of Translational Neuroscience, Michigan State University, Grand Rapids, MI, United States
| | - Mary E. Skinner
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Sean P. Ferris
- Department of Pathology, University of Michigan, Ann Arbor, MI, United States
| | - Emily K. Makowski
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
- Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Michael J. Lucas
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
- Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Nikki McArthur
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | - Ravi S. Kane
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | - Henry L. Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
- Protein Folding Disease Initiative, University of Michigan, Ann Arbor, MI, United States
- Michigan Alzheimer’s Disease Center, University of Michigan, Ann Arbor, MI, United States
| | - Peter M. Tessier
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
- Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI, United States
- Protein Folding Disease Initiative, University of Michigan, Ann Arbor, MI, United States
- Michigan Alzheimer’s Disease Center, University of Michigan, Ann Arbor, MI, United States
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
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33
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Do HQ, Jansen M. Binding motif for RIC-3 chaperon protein in serotonin type 3A receptors. J Gen Physiol 2023; 155:e202213305. [PMID: 37026993 PMCID: PMC10083716 DOI: 10.1085/jgp.202213305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 03/09/2023] [Accepted: 03/21/2023] [Indexed: 04/08/2023] Open
Abstract
Serotonin or 5-hydroxytryptamine type 3 (5-HT3) receptors belong to the family of pentameric ligand-gated ion channels (pLGICs) that are therapeutic targets for psychiatric disorders and neurological diseases. Due to structural conservation and significant sequence similarities of pLGICs' extracellular and transmembrane domains, clinical trials for drug candidates targeting these two domains have been hampered by off-subunit modulation. With the present study, we explore the interaction interface of the 5-HT3A subunit intracellular domain (ICD) with the resistance to inhibitors of choline esterase (RIC-3) protein. Previously, we have shown that RIC-3 interacts with the L1-MX segment of the ICD fused to maltose-binding protein. In the present study, synthetic L1-MX-based peptides and Ala-scanning identify positions W347, R349, and L353 as critical for binding to RIC-3. Complementary studies using full-length 5-HT3A subunits confirm that the identified Ala substitutions reduce the RIC-3-mediated modulation of functional surface expression. Additionally, we find and characterize a duplication of the binding motif, DWLR…VLDR, present in both the MX-helix and the transition between the ICD MA-helix and transmembrane segment M4. Analogous Ala substitutions at W447, R449, and L454 disrupt MAM4-peptide RIC-3 interactions and reduce modulation of functional surface expression. In summary, we identify the binding motif for RIC-3 in 5-HT3A subunits at two locations in the ICD, one in the MX-helix and one at the MAM4-helix transition.
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Affiliation(s)
- Hoa Quynh Do
- Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Michaela Jansen
- Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
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Li Q, Nemecz Á, Aymé G, Dejean de la Bâtie G, Prevost MS, Pons S, Barilone N, Baachaoui R, Maskos U, Lafaye P, Corringer PJ. Generation of nanobodies acting as silent and positive allosteric modulators of the α7 nicotinic acetylcholine receptor. Cell Mol Life Sci 2023; 80:164. [PMID: 37231269 DOI: 10.1007/s00018-023-04779-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 03/28/2023] [Accepted: 04/07/2023] [Indexed: 05/27/2023]
Abstract
The α7 nicotinic acetylcholine receptor (nAChR), a potential drug target for treating cognitive disorders, mediates communication between neuronal and non-neuronal cells. Although many competitive antagonists, agonists, and partial-agonists have been found and synthesized, they have not led to effective therapeutic treatments. In this context, small molecules acting as positive allosteric modulators binding outside the orthosteric, acetylcholine, site have attracted considerable interest. Two single-domain antibody fragments, C4 and E3, against the extracellular domain of the human α7-nAChR were generated through alpaca immunization with cells expressing a human α7-nAChR/mouse 5-HT3A chimera, and are herein described. They bind to the α7-nAChR but not to the other major nAChR subtypes, α4β2 and α3β4. E3 acts as a slowly associating positive allosteric modulator, strongly potentiating the acetylcholine-elicited currents, while not precluding the desensitization of the receptor. An E3-E3 bivalent construct shows similar potentiating properties but displays very slow dissociation kinetics conferring quasi-irreversible properties. Whereas, C4 does not alter the receptor function, but fully inhibits the E3-evoked potentiation, showing it is a silent allosteric modulator competing with E3 binding. Both nanobodies do not compete with α-bungarotoxin, localizing at an allosteric extracellular binding site away from the orthosteric site. The functional differences of each nanobody, as well as the alteration of functional properties through nanobody modifications indicate the importance of this extracellular site. The nanobodies will be useful for pharmacological and structural investigations; moreover, they, along with the extracellular site, have a direct potential for clinical applications.
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Affiliation(s)
- Qimeng Li
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Antibody Engineering Platform, Paris, France
- Lanzhou Institute of Biological Product Co., Lanzhou, China
- Sorbonne Université, Collège Doctoral, Paris, France
| | - Ákos Nemecz
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France.
| | - Gabriel Aymé
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Antibody Engineering Platform, Paris, France.
| | | | - Marie S Prevost
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
| | - Stéphanie Pons
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Integrative Neurobiology of Cholinergic Systems Unit, Paris, France
| | - Nathalie Barilone
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
| | - Rayen Baachaoui
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Antibody Engineering Platform, Paris, France
| | - Uwe Maskos
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Integrative Neurobiology of Cholinergic Systems Unit, Paris, France
| | - Pierre Lafaye
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Antibody Engineering Platform, Paris, France
| | - Pierre-Jean Corringer
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France.
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35
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Lu C, Zhu X, Feng Y, Ao W, Li J, Gao Z, Luo H, Chen M, Cai F, Zhan S, Li H, Sun W, Hu J. Atypical antipsychotics antagonize GABA A receptors in the ventral tegmental area GABA neurons to relieve psychotic behaviors. Mol Psychiatry 2023; 28:2107-2121. [PMID: 36754983 DOI: 10.1038/s41380-023-01982-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/19/2023] [Accepted: 01/24/2023] [Indexed: 02/10/2023]
Abstract
Psychosis is an abnormal mental condition that can cause patients to lose contact with reality. It is a common symptom of schizophrenia, bipolar disorder, sleep deprivation, and other mental disorders. Clinically, antipsychotic medications, such as olanzapine and clozapine, are very effective in treatment for psychosis. To investigate the neural circuit mechanism that is affected by antipsychotics and identify more selective therapeutic targets, we employed a strategy by using these effective antipsychotics to identify antipsychotic neural substrates. We observed that local injection of antipsychotics into the ventral tegmental area (VTA) could reverse the sensorimotor gating defects induced by MK-801 injection in mice. Using in vivo fiber photometry, electrophysiological techniques, and chemogenetics, we found that antipsychotics could activate VTA gamma-aminobutyric acid (GABA) neurons by blocking GABAA receptors. Moreover, we found that the VTAGABA nucleus accumbens (NAc) projection was crucially involved in such antipsychotic effects. In summary, our study identifies a novel therapeutic target for the treatment of psychosis and underscores the utility of a 'bedside-to-bench' approach for identifying neural circuits that influence psychotic disorders.
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Affiliation(s)
- Chen Lu
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Xiaona Zhu
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China.
| | - Yifan Feng
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Weizhen Ao
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Jie Li
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 200030, Shanghai, China
| | - Zilong Gao
- School of Life Sciences, Westlake University, 310024, Hangzhou, China
| | - Huoqing Luo
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Ming Chen
- Institutes of Brain Science, Fudan University, 200032, Shanghai, China
| | - Fang Cai
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Shulu Zhan
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Hongxia Li
- Department of Neurology and Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China
| | - Wenzhi Sun
- Chinese Institute for Brain Research, 102206, Beijing, China.
- School of Basic Medical Sciences, Capital Medical University, 100069, Beijing, China.
| | - Ji Hu
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China.
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36
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Käshammer L, van den Ent F, Jeffery M, Jean NL, Hale VL, Löwe J. Cryo-EM structure of the bacterial divisome core complex and antibiotic target FtsWIQBL. Nat Microbiol 2023:10.1038/s41564-023-01368-0. [PMID: 37127704 DOI: 10.1038/s41564-023-01368-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 03/23/2023] [Indexed: 05/03/2023]
Abstract
In most bacteria, cell division relies on the synthesis of new cell wall material by the multiprotein divisome complex. Thus, at the core of the divisome are the transglycosylase FtsW, which synthesises peptidoglycan strands from its substrate Lipid II, and the transpeptidase FtsI that cross-links these strands to form a mesh, shaping and protecting the bacterial cell. The FtsQ-FtsB-FtsL trimeric complex interacts with the FtsWI complex and is involved in regulating its enzymatic activities; however, the structure of this pentameric complex is unknown. Here, we present the cryogenic electron microscopy structure of the FtsWIQBL complex from Pseudomonas aeruginosa at 3.7 Å resolution. Our work reveals intricate structural details, including an extended coiled coil formed by FtsL and FtsB and the periplasmic interaction site between FtsL and FtsI. Our structure explains the consequences of previously reported mutations and we postulate a possible activation mechanism involving a large conformational change in the periplasmic domain. As FtsWIQBL is central to the divisome, our structure is foundational for the design of future experiments elucidating the precise mechanism of bacterial cell division, an important antibiotic target.
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Affiliation(s)
- Lisa Käshammer
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | | | - Magnus Jeffery
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Nicolas L Jean
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Victoria L Hale
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Jan Löwe
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
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37
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Kłopotowski K, Michałowski MA, Gos M, Mosiądz D, Czyżewska MM, Mozrzymas JW. Mutation of valine 53 at the interface between extracellular and transmembrane domains of the β 2 principal subunit affects the GABA A receptor gating. Eur J Pharmacol 2023; 947:175664. [PMID: 36934960 DOI: 10.1016/j.ejphar.2023.175664] [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: 11/17/2022] [Revised: 02/09/2023] [Accepted: 03/16/2023] [Indexed: 03/21/2023]
Abstract
GABAA receptors (gamma-aminobutyric acid type A receptors) are pentameric ligand-gated ion channels mediating inhibition in adult mammalian brains. Their static structure has been intensely studied in the past years but the underlying molecular activatory mechanisms remain obscure. The interface between extracellular and transmembrane domains has been recognized as a key player in the receptor gating. However, the role of the valine 53 in the β1-β2 loop of the principal subunit (β2) remains controversial showing differences compared to homologous residues in some cys-loop counterparts such as nAChR. To address the role of the β2V53 residue in the α1β2γ2L receptor gating, we performed high resolution macroscopic and single-channel recordings. To explore underlying molecular mechanisms a variety of substituting amino acids were investigated: Glutamate and Lysine (different electric charge), Alanine (aliphatic, larger than Valine) and Histidine (same residue as in homologous α1H55). We report that mutation of the β2V53 residue results in alterations of nearly all gating transitions including opening/closing, preactivation and desensitization. A dramatic gating impairment was observed for glutamate substitution (β2V53E) but β2V53K mutation had a weak effect. The impact of histidine substitution was also small while β2V53A markedly affected the receptor but to a smaller extent than β2V53E. Considering available structures in desensitized and bicuculline blocked shut states we propose that strongly detrimental effect of β2V53E mutation on receptor activation results from electrostatic interaction between the glutamate and β2K274 on the loop M2-M3 which stabilizes the receptor in the shut state. We conclude that β2V53 is strongly involved in mechanisms underlying the receptor gating.
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Affiliation(s)
- Karol Kłopotowski
- Wroclaw Medical University, Department of Biophysics and Neuroscience, Chałubińskiego 3a, Wrocław, Dolnośląskie, PL 50-368, Poland.
| | - Michał A Michałowski
- Wroclaw Medical University, Department of Biophysics and Neuroscience, Chałubińskiego 3a, Wrocław, Dolnośląskie, PL 50-368, Poland
| | - Michalina Gos
- Wroclaw Medical University, Department of Biophysics and Neuroscience, Chałubińskiego 3a, Wrocław, Dolnośląskie, PL 50-368, Poland; University of Wroclaw, Department of Molecular Physiology and Neurobiology, Sienkiewicza 21, Wrocław, Dolnośląskie, Pl 50-335, Poland
| | - Daniela Mosiądz
- Wroclaw Medical University, Department of Biophysics and Neuroscience, Chałubińskiego 3a, Wrocław, Dolnośląskie, PL 50-368, Poland
| | - Marta M Czyżewska
- Wroclaw Medical University, Department of Biophysics and Neuroscience, Chałubińskiego 3a, Wrocław, Dolnośląskie, PL 50-368, Poland
| | - Jerzy W Mozrzymas
- Wroclaw Medical University, Department of Biophysics and Neuroscience, Chałubińskiego 3a, Wrocław, Dolnośląskie, PL 50-368, Poland; University of Wroclaw, Department of Molecular Physiology and Neurobiology, Sienkiewicza 21, Wrocław, Dolnośląskie, Pl 50-335, Poland.
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38
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Gc JB, Szlenk CT, Diyaolu A, Obi P, Wei H, Shi X, Gibson KM, Natesan S, Roullet JB. Allosteric modulation of α1β3γ2 GABA A receptors by farnesol through the neurosteroid sites. Biophys J 2023; 122:849-867. [PMID: 36721367 PMCID: PMC10027449 DOI: 10.1016/j.bpj.2023.01.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 12/13/2022] [Accepted: 01/23/2023] [Indexed: 02/02/2023] Open
Abstract
In mammalian cells, all-trans farnesol, a 15-carbon isoprenol, is a product of the mevalonate pathway. It is the natural substrate of alcohol dehydrogenase and a substrate for CYP2E1, two enzymes implicated in ethanol metabolism. Studies have shown that farnesol is present in the human brain and inhibits voltage-gated Ca2+ channels at much lower concentrations than ethanol. Here we show that farnesol modulates the activity of γ-aminobutyric acid type A receptors (GABAARs), some of which also mediate the sedative activity of ethanol. Electrophysiology experiments performed in HEK cells expressing human α1β3γ2 or α6β3γ2 GABAARs revealed that farnesol increased chloride currents through positive allosteric modulation of these receptors and showed dependence on both the alcoholic functional group of farnesol and the length of the alkyl chain for activity. In silico studies using long-timescale unbiased all-atom molecular dynamics (MD) simulations of the human α1β3γ2 GABAA receptors revealed that farnesol modulates the channel by directly binding to the transmembrane neurosteroid-binding site, after partitioning into the surrounding membrane and reaching the receptor by lateral diffusion. Channel activation by farnesol was further characterized by several structural and dynamic variables, such as global twisting of the receptor's extracellular domain, tilting of the transmembrane M2 helices, radius, cross-sectional area, hydration status, and electrostatic potential of the channel pore. Our results expand the pharmacological activities of farnesol to yet another class of ion channels implicated in neurotransmission, thus providing a novel path for understanding and treatment of diseases involving GABAA receptor dysfunction.
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Affiliation(s)
- Jeevan B Gc
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Christopher T Szlenk
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Ayobami Diyaolu
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Peter Obi
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Haiyang Wei
- Eurofins Panlabs, Inc., St. Charles, Missouri
| | - Xutong Shi
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - K Michael Gibson
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Senthil Natesan
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington.
| | - Jean-Baptiste Roullet
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington.
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39
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Zhu KF, Yuan C, Du YM, Sun KL, Zhang XK, Vogel H, Jia XD, Gao YZ, Zhang QF, Wang DP, Zhang HW. Applications and prospects of cryo-EM in drug discovery. Mil Med Res 2023; 10:10. [PMID: 36872349 PMCID: PMC9986049 DOI: 10.1186/s40779-023-00446-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 02/14/2023] [Indexed: 03/07/2023] Open
Abstract
Drug discovery is a crucial part of human healthcare and has dramatically benefited human lifespan and life quality in recent centuries, however, it is usually time- and effort-consuming. Structural biology has been demonstrated as a powerful tool to accelerate drug development. Among different techniques, cryo-electron microscopy (cryo-EM) is emerging as the mainstream of structure determination of biomacromolecules in the past decade and has received increasing attention from the pharmaceutical industry. Although cryo-EM still has limitations in resolution, speed and throughput, a growing number of innovative drugs are being developed with the help of cryo-EM. Here, we aim to provide an overview of how cryo-EM techniques are applied to facilitate drug discovery. The development and typical workflow of cryo-EM technique will be briefly introduced, followed by its specific applications in structure-based drug design, fragment-based drug discovery, proteolysis targeting chimeras, antibody drug development and drug repurposing. Besides cryo-EM, drug discovery innovation usually involves other state-of-the-art techniques such as artificial intelligence (AI), which is increasingly active in diverse areas. The combination of cryo-EM and AI provides an opportunity to minimize limitations of cryo-EM such as automation, throughput and interpretation of medium-resolution maps, and tends to be the new direction of future development of cryo-EM. The rapid development of cryo-EM will make it as an indispensable part of modern drug discovery.
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Affiliation(s)
- Kong-Fu Zhu
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, 518055 Guangdong China
| | - Chuang Yuan
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, 100191 China
| | - Yong-Ming Du
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105 USA
| | - Kai-Lei Sun
- Center for Protein Science and Crystallography, School of Life Sciences, Faculty of Science, Chinese University of Hong Kong, Hong Kong, 999077 China
| | - Xiao-Kang Zhang
- Interdisciplinary Center for Brain Information, the Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055 Guangdong China
- Faculty of Life and Health Sciences, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055 Guangdong China
- Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, 518055 Guangdong China
| | - Horst Vogel
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055 Guangdong China
| | - Xu-Dong Jia
- State Key Lab for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275 China
| | - Yuan-Zhu Gao
- Cryo-EM Facility Center, Southern University of Science and Technology, Shenzhen, 518055 Guangdong China
| | - Qin-Fen Zhang
- State Key Lab for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275 China
| | - Da-Ping Wang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, 518055 Guangdong China
- Department of Orthopedics, Shenzhen Intelligent Orthopaedics and Biomedical Innovation Platform, Guangdong Provincial Research Center for Artificial Intelligence and Digital Orthopedic Technology, Shenzhen Second People’s Hospital, The First Affiliated Hospital of Shenzhen University, Shenzhen, 518000 Guangdong China
| | - Hua-Wei Zhang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, 518055 Guangdong China
- Guangdong Provincial Key Laboratory of Advanced Biomaterials, Southern University of Science and Technology, Shenzhen, 518055 Guangdong China
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40
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Hernandez CC, Shen Y, Hu N, Shen W, Narayanan V, Ramsey K, He W, Zou L, Macdonald RL. GABRG2 Variants Associated with Febrile Seizures. Biomolecules 2023; 13:414. [PMID: 36979350 PMCID: PMC10046037 DOI: 10.3390/biom13030414] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 02/13/2023] [Accepted: 02/17/2023] [Indexed: 02/24/2023] Open
Abstract
Febrile seizures (FS) are the most common form of epilepsy in children between six months and five years of age. FS is a self-limited type of fever-related seizure. However, complicated prolonged FS can lead to complex partial epilepsy. We found that among the GABAA receptor subunit (GABR) genes, most variants associated with FS are harbored in the γ2 subunit (GABRG2). Here, we characterized the effects of eight variants in the GABAA receptor γ2 subunit on receptor biogenesis and channel function. Two-thirds of the GABRG2 variants followed the expected autosomal dominant inheritance in FS and occurred as missense and nonsense variants. The remaining one-third appeared as de novo in the affected probands and occurred only as missense variants. The loss of GABAA receptor function and dominant negative effect on GABAA receptor biogenesis likely caused the FS phenotype. In general, variants in the GABRG2 result in a broad spectrum of phenotypic severity, ranging from asymptomatic, FS, genetic epilepsy with febrile seizures plus (GEFS+), and Dravet syndrome individuals. The data presented here support the link between FS, epilepsy, and GABRG2 variants, shedding light on the relationship between the variant topological occurrence and disease severity.
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Affiliation(s)
- Ciria C. Hernandez
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yanwen Shen
- Department of Pediatrics, Seventh Medical Center of Chinese PLA General Hospital, Beijing 100010, China
| | - Ningning Hu
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Vinodh Narayanan
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ 85004, USA
| | - Keri Ramsey
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ 85004, USA
| | - Wen He
- Department of Pediatrics, Seventh Medical Center of Chinese PLA General Hospital, Beijing 100010, China
| | - Liping Zou
- Department of Pediatrics, Seventh Medical Center of Chinese PLA General Hospital, Beijing 100010, China
| | - Robert L. Macdonald
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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41
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Yuan Z, Hansen SB. Cholesterol Regulation of Membrane Proteins Revealed by Two-Color Super-Resolution Imaging. MEMBRANES 2023; 13:membranes13020250. [PMID: 36837753 PMCID: PMC9966874 DOI: 10.3390/membranes13020250] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 02/05/2023] [Accepted: 02/07/2023] [Indexed: 05/15/2023]
Abstract
Cholesterol and phosphatidyl inositol 4,5-bisphosphate (PIP2) are hydrophobic molecules that regulate protein function in the plasma membrane of all cells. In this review, we discuss how changes in cholesterol concentration cause nanoscopic (<200 nm) movements of membrane proteins to regulate their function. Cholesterol is known to cluster many membrane proteins (often palmitoylated proteins) with long-chain saturated lipids. Although PIP2 is better known for gating ion channels, in this review, we will discuss a second independent function as a regulator of nanoscopic protein movement that opposes cholesterol clustering. The understanding of the movement of proteins between nanoscopic lipid domains emerged largely through the recent advent of super-resolution imaging and the establishment of two-color techniques to label lipids separate from proteins. We discuss the labeling techniques for imaging, their strengths and weakness, and how they are used to reveal novel mechanisms for an ion channel, transporter, and enzyme function. Among the mechanisms, we describe substrate and ligand presentation and their ability to activate enzymes, gate channels, and transporters rapidly and potently. Finally, we define cholesterol-regulated proteins (CRP) and discuss the role of PIP2 in opposing the regulation of cholesterol, as seen through super-resolution imaging.
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Affiliation(s)
- Zixuan Yuan
- Department of Molecular Medicine, Department of Neuroscience, UF Scripps, Jupiter, FL 33458, USA
- Department of Neuroscience UF Scripps, Jupiter, FL 33458, USA
- Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Scott B. Hansen
- Department of Molecular Medicine, Department of Neuroscience, UF Scripps, Jupiter, FL 33458, USA
- Department of Neuroscience UF Scripps, Jupiter, FL 33458, USA
- Correspondence:
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42
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Sun C, Zhu H, Clark S, Gouaux E. Regulated assembly and neurosteroid modulation constrain GABA A receptor pharmacology in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.16.528867. [PMID: 36824901 PMCID: PMC9949137 DOI: 10.1101/2023.02.16.528867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Type A GABA receptors (GABA A Rs) are the principal inhibitory receptors in the brain and the target of a wide range of clinical agents, including anesthetics, sedatives, hypnotics, and antidepressants. However, our understanding of GABA A R pharmacology has been hindered by the vast number of pentameric assemblies that can be derived from a total 19 different subunits and the lack of structural knowledge of clinically relevant receptors. Here, we isolate native murine GABA A R assemblies containing the widely expressed α 1 subunit, and elucidate their structures in complex with drugs used to treat insomnia (zolpidem and flurazepam) and postpartum depression (the neurosteroid allopregnanolone). Using cryo-EM analysis and single-molecule photobleaching experiments, we uncover only three structural populations in the brain: the canonical α 1 β2γ 2 receptor containing two α 1 subunits and two unanticipated assemblies containing one α 1 and either an α 2 , α 3 or α 5 subunit. Both of the noncanonical assemblies feature a more compact arrangement between the transmembrane and extracellular domains. Interestingly, allopregnanolone is bound at the transmembrane α/β subunit interface, even when not added to the sample, revealing an important role for endogenous neurosteroids in modulating native GABA A Rs. Together with structurally engaged lipids, neurosteroids produce global conformational changes throughout the receptor that modify both the pore diameter and binding environments for GABA and insomnia medications. Together, our data reveal that GABA A R assembly is a strictly regulated process that yields a small number of structurally distinct complexes, defining a structural landscape from which subtype-specific drugs can be developed.
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Seto T. General anesthetic binding mode via hydration with weak affinity and molecular discrimination: General anesthetic dissolution in interfacial water of the common binding site of GABA A receptor. Biophys Physicobiol 2023; 20:e200005. [PMID: 38496235 PMCID: PMC10941959 DOI: 10.2142/biophysico.bppb-v20.0005] [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: 07/04/2022] [Accepted: 01/23/2023] [Indexed: 01/25/2023] Open
Abstract
The GABAA receptor (GABAAR) is a target channel for the loss of awareness of general anesthesia. General anesthetic (GA) spans a wide range of chemical structures, such as monatomic molecules, barbital acids, phenols, ethers, and alkanes. GA has a weak binding affinity, and the affinity has a characteristic that correlates with the solubility in olive oil rather than the molecular shape. The GA binding site of GABAAR is common to GAs and exists in the transmembrane domain of the GABAAR intersubunit. In this study, the mechanism of GA binding, which allows binding of various GAs with intersubunit selectivity, was elucidated from the hydration analysis of the binding site. Regardless of the diverse GA chemical structures, a strong correlation was observed between the binding free energy and total dehydration number of the binding process. The GA binding free energy was more involved in the binding dehydration and showed molecular recognition that allowed for the binding of various GA structures via binding site hydration. We regarded the GA substitution for the interfacial water molecule of the binding site as a dissolution into the interfacial hydration layer. The elucidation of the GA binding mechanism mediated by hydration at the GABAAR common binding site provides a rationale for the combined use of anesthetics in medical practice and its combination adjustments via drug interactions.
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Affiliation(s)
- Tomoyoshi Seto
- Department of Anesthesiology, School of Medicine, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
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Dallo S, Shin J, Zhang S, Ren Q, Bao H. Designer Nanodiscs to Probe and Reprogram Membrane Biology in Synapses. J Mol Biol 2023; 435:167757. [PMID: 35872069 PMCID: PMC9805492 DOI: 10.1016/j.jmb.2022.167757] [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: 06/01/2022] [Revised: 07/17/2022] [Accepted: 07/18/2022] [Indexed: 02/04/2023]
Abstract
Signal transduction at the synapse is mediated by a variety of protein-lipid interactions, which are vital for the spatial and temporal regulation of synaptic vesicle biogenesis, neurotransmitter release, and postsynaptic receptor activation. Therefore, our understanding of synaptic transmission cannot be completed until the elucidation of these critical protein-lipid interactions. On this front, recent advances in nanodiscs have vastly expanded our ability to probe and reprogram membrane biology in synapses. Here, we summarize the progress of the nanodisc toolbox and discuss future directions in this exciting field.
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Affiliation(s)
- Sarah Dallo
- Department of Molecular Medicine, UF Scripps Biomedical Research, 130 Scripps Way, Jupiter 33458, FL, USA
| | - Jeehae Shin
- Department of Molecular Medicine, UF Scripps Biomedical Research, 130 Scripps Way, Jupiter 33458, FL, USA
| | - Shanwen Zhang
- Department of Molecular Medicine, UF Scripps Biomedical Research, 130 Scripps Way, Jupiter 33458, FL, USA
| | - Qian Ren
- Department of Molecular Medicine, UF Scripps Biomedical Research, 130 Scripps Way, Jupiter 33458, FL, USA
| | - Huan Bao
- Department of Molecular Medicine, UF Scripps Biomedical Research, 130 Scripps Way, Jupiter 33458, FL, USA.
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Abstract
Membrane transporter proteins are divided into channels/pores and carriers and constitute protein families of physiological and pharmacological importance. Several presently used therapeutic compounds elucidate their effects by targeting membrane transporter proteins, including anti-arrhythmic, anesthetic, antidepressant, anxiolytic and diuretic drugs. The lack of three-dimensional structures of human transporters hampers experimental studies and drug discovery. In this chapter, the use of homology modeling for generating structural models of membrane transporter proteins is reviewed. The increasing number of atomic resolution structures available as templates, together with improvements in methods and algorithms for sequence alignments, secondary structure predictions, and model generation, in addition to the increase in computational power have increased the applicability of homology modeling for generating structural models of transporter proteins. Different pitfalls and hints for template selection, multiple-sequence alignments, generation and optimization, validation of the models, and the use of transporter homology models for structure-based virtual ligand screening are discussed.
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Affiliation(s)
- Ingebrigt Sylte
- Molecular Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway.
| | - Mari Gabrielsen
- Molecular Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - Kurt Kristiansen
- Molecular Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
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Biophysical characterization of calcium-binding and modulatory-domain dynamics in a pentameric ligand-gated ion channel. Proc Natl Acad Sci U S A 2022; 119:e2210669119. [PMID: 36480474 PMCID: PMC9897478 DOI: 10.1073/pnas.2210669119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) perform electrochemical signal transduction in organisms ranging from bacteria to humans. Among the prokaryotic pLGICs, there is architectural diversity involving N-terminal domains (NTDs) not found in eukaryotic relatives, exemplified by the calcium-sensitive channel (DeCLIC) from a Desulfofustis deltaproteobacterium, which has an NTD in addition to the canonical pLGIC structure. Here, we have characterized the structure and dynamics of DeCLIC through cryoelectron microscopy (cryo-EM), small-angle neutron scattering (SANS), and molecular dynamics (MD) simulations. In the presence and absence of calcium, cryo-EM yielded structures with alternative conformations of the calcium-binding site. SANS profiles further revealed conformational diversity at room temperature beyond that observed in static structures, shown through MD to be largely attributable to rigid-body motions of the NTD relative to the protein core, with expanded and asymmetric conformations improving the fit of the SANS data. This work reveals the range of motion available to the DeCLIC NTD and calcium-binding site, expanding the conformational landscape of the pLGIC family. Further, these findings demonstrate the power of combining low-resolution scattering, high-resolution structural, and MD simulation data to elucidate interfacial interactions that are highly conserved in the pLGIC family.
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Goldschen-Ohm MP. Benzodiazepine Modulation of GABA A Receptors: A Mechanistic Perspective. Biomolecules 2022; 12:biom12121784. [PMID: 36551212 PMCID: PMC9775625 DOI: 10.3390/biom12121784] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/23/2022] [Accepted: 11/26/2022] [Indexed: 12/05/2022] Open
Abstract
Benzodiazepines (BZDs) are a class of widely prescribed psychotropic drugs that target GABAA receptors (GABAARs) to tune inhibitory synaptic signaling throughout the central nervous system. Despite knowing their molecular target for over 40 years, we still do not fully understand the mechanism of modulation at the level of the channel protein. Nonetheless, functional studies, together with recent cryo-EM structures of GABAA(α1)2(βX)2(γ2)1 receptors in complex with BZDs, provide a wealth of information to aid in addressing this gap in knowledge. Here, mechanistic interpretations of functional and structural evidence for the action of BZDs at GABAA(α1)2(βX)2(γ2)1 receptors are reviewed. The goal is not to describe each of the many studies that are relevant to this discussion nor to dissect in detail all the effects of individual mutations or perturbations but rather to highlight general mechanistic principles in the context of recent structural information.
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Open-channel structure of a pentameric ligand-gated ion channel reveals a mechanism of leaflet-specific phospholipid modulation. Nat Commun 2022; 13:7017. [PMID: 36385237 PMCID: PMC9668969 DOI: 10.1038/s41467-022-34813-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 11/08/2022] [Indexed: 11/18/2022] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) mediate synaptic transmission and are sensitive to their lipid environment. The mechanism of phospholipid modulation of any pLGIC is not well understood. We demonstrate that the model pLGIC, ELIC (Erwinia ligand-gated ion channel), is positively modulated by the anionic phospholipid, phosphatidylglycerol, from the outer leaflet of the membrane. To explore the mechanism of phosphatidylglycerol modulation, we determine a structure of ELIC in an open-channel conformation. The structure shows a bound phospholipid in an outer leaflet site, and structural changes in the phospholipid binding site unique to the open-channel. In combination with streamlined alchemical free energy perturbation calculations and functional measurements in asymmetric liposomes, the data support a mechanism by which an anionic phospholipid stabilizes the activated, open-channel state of a pLGIC by specific, state-dependent binding to this site.
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Lovatt M, Leistner C, Frank RAW. Bridging length scales from molecules to the whole organism by cryoCLEM and cryoET. Faraday Discuss 2022; 240:114-126. [PMID: 35959706 PMCID: PMC9642002 DOI: 10.1039/d2fd00081d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Resolving atomic structures of isolated proteins has uncovered mechanisms and fundamental processes in biology. However, many functions can only be tested in the context of intact cells and tissues that are many orders of magnitude larger than the macromolecules on which they depend. Therefore, methods that interrogate macromolecular structure in situ provide a means of directly relating structure to function across length scales. Here, we developed several workflows using cryogenic correlated light and electron microscopy (cryoCLEM) and electron tomography (cryoET) that can bridge this gap to reveal the molecular infrastructure that underlies higher order functions within cells and tissues. We also describe experimental design considerations, including cryoCLEM labelling, sample preparation, and quality control, for determining the in situ molecular architectures within native, hydrated cells and tissues.
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Affiliation(s)
- Megan Lovatt
- Astbury Centre of Structural Molecular Biology, School of Biomedical Sciences, Faculty of Biological Sciences, University of LeedsLS2 9JTUK
| | - Conny Leistner
- Astbury Centre of Structural Molecular Biology, School of Biomedical Sciences, Faculty of Biological Sciences, University of LeedsLS2 9JTUK
| | - René A. W. Frank
- Astbury Centre of Structural Molecular Biology, School of Biomedical Sciences, Faculty of Biological Sciences, University of LeedsLS2 9JTUK
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Cerdan AH, Peverini L, Changeux JP, Corringer PJ, Cecchini M. Lateral fenestrations in the extracellular domain of the glycine receptor contribute to the main chloride permeation pathway. SCIENCE ADVANCES 2022; 8:eadc9340. [PMID: 36240268 PMCID: PMC9565810 DOI: 10.1126/sciadv.adc9340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 08/29/2022] [Indexed: 06/16/2023]
Abstract
Glycine receptors (GlyRs) are ligand-gated ion channels mediating signal transduction at chemical synapses. Since the early patch-clamp electrophysiology studies, the details of the ion permeation mechanism have remained elusive. Here, we combine molecular dynamics simulations of a zebrafish GlyR-α1 model devoid of the intracellular domain with mutagenesis and single-channel electrophysiology of the full-length human GlyR-α1. We show that lateral fenestrations between subunits in the extracellular domain provide the main translocation pathway for chloride ions to enter/exit a central water-filled vestibule at the entrance of the transmembrane channel. In addition, we provide evidence that these fenestrations are at the origin of current rectification in known anomalous mutants and design de novo two inward-rectifying channels by introducing mutations within them. These results demonstrate the central role of lateral fenestrations on synaptic neurotransmission.
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Affiliation(s)
- Adrien H. Cerdan
- Institut de Chimie de Strasbourg, UMR7177, CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
| | - Laurie Peverini
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
| | - Jean-Pierre Changeux
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
- Kavli Institute for Brain and Mind, University of California, San Diego, La Jolla, CA, USA
- Collège de France, Paris, France
| | - Pierre-Jean Corringer
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
| | - Marco Cecchini
- Institut de Chimie de Strasbourg, UMR7177, CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France
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