1
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Nors JW, Endres Z, Goldschen-Ohm MP. GABA A receptor subunit M2-M3 linkers have asymmetric roles in pore gating and diazepam modulation. Biophys J 2024; 123:2085-2096. [PMID: 38400541 PMCID: PMC11309982 DOI: 10.1016/j.bpj.2024.02.016] [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: 10/30/2023] [Revised: 01/19/2024] [Accepted: 02/20/2024] [Indexed: 02/25/2024] Open
Abstract
GABAA receptors (GABAARs) are neurotransmitter-gated ion channels critical for inhibitory synaptic transmission as well as the molecular target for benzodiazepines (BZDs), one of the most widely prescribed class of psychotropic drugs today. Despite structural insight into the conformations underlying functional channel states, the detailed molecular interactions involved in conformational transitions and the physical basis for their modulation by BZDs are not fully understood. We previously identified that alanine substitution at the central residue in the α1 subunit M2-M3 linker (V279A) enhances the efficiency of linkage between the BZD site and the pore gate. Here, we expand on this work by investigating the effect of alanine substitutions at the analogous positions in the M2-M3 linkers of β2 (I275A) and γ2 (V290A) subunits, which together with α1 comprise typical heteromeric α1β2γ2 synaptic GABAARs. We find that these mutations confer subunit-specific effects on the intrinsic pore closed-open equilibrium and its modulation by the BZD diazepam (DZ). The mutations α1(V279A) or γ2(V290A) bias the channel toward a closed conformation, whereas β2(I275A) biases the channel toward an open conformation to the extent that the channel becomes leaky and opens spontaneously in the absence of agonist. In contrast, only α1(V279A) enhances the efficiency of DZ-to-pore linkage, whereas mutations in the other two subunits have no effect. These observations show that the central residue in the M2-M3 linkers of distinct subunits in synaptic α1β2γ2 GABAARs contribute asymmetrically to the intrinsic closed-open equilibrium and its modulation by DZ.
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Affiliation(s)
- Joseph W Nors
- Department of Neuroscience, University of Texas at Austin, Austin, Texas; Department of Molecular and Cellular Physiology, Stanford University, Stanford, California
| | - Zachary Endres
- Department of Neuroscience, University of Texas at Austin, Austin, Texas
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2
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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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3
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Bharambe N, Li Z, Seiferth D, Balakrishna AM, Biggin PC, Basak S. Cryo-EM structures of prokaryotic ligand-gated ion channel GLIC provide insights into gating in a lipid environment. Nat Commun 2024; 15:2967. [PMID: 38580666 PMCID: PMC10997623 DOI: 10.1038/s41467-024-47370-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: 02/22/2023] [Accepted: 03/28/2024] [Indexed: 04/07/2024] Open
Abstract
GLIC, a proton-activated prokaryotic ligand-gated ion channel, served as a model system for understanding the eukaryotic counterparts due to their structural and functional similarities. Despite extensive studies conducted on GLIC, the molecular mechanism of channel gating in the lipid environment requires further investigation. Here, we present the cryo-EM structures of nanodisc-reconstituted GLIC at neutral and acidic pH in the resolution range of 2.6 - 3.4 Å. In our apo state at pH 7.5, the extracellular domain (ECD) displays conformational variations compared to the existing apo structures. At pH 4.0, three distinct conformational states (C1, C2 and O states) are identified. The protonated structures exhibit a compacted and counter-clockwise rotated ECD compared with our apo state. A gradual widening of the pore in the TMD is observed upon reducing the pH, with the widest pore in O state, accompanied by several layers of water pentagons. The pore radius and molecular dynamics (MD) simulations suggest that the O state represents an open conductive state. We also observe state-dependent interactions between several lipids and proteins that may be involved in the regulation of channel gating. Our results provide comprehensive insights into the importance of lipids impact on gating.
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Affiliation(s)
- Nikhil Bharambe
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - Zhuowen Li
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - David Seiferth
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Philip C Biggin
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, UK
| | - Sandip Basak
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore.
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore, 639798, Singapore.
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4
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Felt K, Stauffer M, Salas-Estrada L, Guzzo PR, Xie D, Huang J, Filizola M, Chakrapani S. Structural basis for partial agonism in 5-HT 3A receptors. Nat Struct Mol Biol 2024; 31:598-609. [PMID: 38177669 DOI: 10.1038/s41594-023-01140-2] [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: 02/06/2023] [Accepted: 09/26/2023] [Indexed: 01/06/2024]
Abstract
Hyperactivity of serotonin 3 receptors (5-HT3R) underlies pathologies associated with irritable bowel syndrome and chemotherapy-induced nausea and vomiting. Setrons, a class of high-affinity competitive antagonists, are used in the treatment of these conditions. Although generally effective for chemotherapy-induced nausea and vomiting, the use of setrons for treating irritable bowel syndrome has been impaired by adverse side effects. Partial agonists are now being considered as an alternative strategy, with potentially less severe side effects than full antagonists. However, a structural understanding of how these ligands work is lacking. Here, we present high-resolution cryogenic electron microscopy structures of the mouse 5-HT3AR in complex with partial agonists (SMP-100 and ALB-148471) captured in pre-activated and open-like conformational states. Molecular dynamics simulations were used to assess the stability of drug-binding poses and interactions with the receptor over time. Together, these studies reveal mechanisms for the functional differences between orthosteric partial agonists, full agonists and antagonists of the 5-HT3AR.
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Affiliation(s)
- Kevin Felt
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA
| | - Madeleine Stauffer
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA
| | - Leslie Salas-Estrada
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Peter R Guzzo
- SciMount Therapeutics (Shenzhen) Co. Ltd., Shenzhen, China
| | - Dejian Xie
- SciMount Therapeutics (Shenzhen) Co. Ltd., Shenzhen, China
| | - Jinkun Huang
- SciMount Therapeutics (Shenzhen) Co. Ltd., Shenzhen, China
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sudha Chakrapani
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA.
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, USA.
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5
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Alvarez LD, Carina Alves NR. Structural Basis for Molecular Recognition of Cannabinoids by Inhibitory Cys-Loop Channels. J Med Chem 2024; 67:3274-3286. [PMID: 38428383 DOI: 10.1021/acs.jmedchem.3c02391] [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: 03/03/2024]
Abstract
Cannabis sativa has a long history of medicinal use, dating back to ancient times. This plant produces cannabinoids, which are now known to interact with several human proteins, including Cys-loop receptors for glycine (GlyR) and gamma-aminobutyric acid (GABAAR). As these channels are the primary mediators of inhibitory signals, they contribute to the diverse effects of cannabinoids on the nervous system. Evidence suggests that cannabinoid binding sites are located within the transmembrane domain, although their precise location has remained undetermined for over a decade. The process of identification of the binding site and the computational approaches employed are the main subjects of this Perspective, which includes an analysis of the most recently resolved cryo-EM structures of zebrafish GlyR bound to Δ9-tetrahydrocannabinol and the THC-GlyR complex obtained through molecular dynamics simulations. With this work, we aim to contribute to guiding future studies investigating the molecular basis of cannabinoid action on inhibitory channels.
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Affiliation(s)
- Lautaro D Alvarez
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires C1428EGA, Argentina
- UMYMFOR, CONICET-Universidad de Buenos Aires, Ciudad UniversitariaBuenos Aires C1428EGA, Argentina
| | - N R Carina Alves
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires C1428EGA, Argentina
- UMYMFOR, CONICET-Universidad de Buenos Aires, Ciudad UniversitariaBuenos Aires C1428EGA, Argentina
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6
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Wiessler AL, Talucci I, Piro I, Seefried S, Hörlin V, Baykan BB, Tüzün E, Schaefer N, Maric HM, Sommer C, Villmann C. Glycine Receptor β-Targeting Autoantibodies Contribute to the Pathology of Autoimmune Diseases. NEUROLOGY(R) NEUROIMMUNOLOGY & NEUROINFLAMMATION 2024; 11:e200187. [PMID: 38215349 PMCID: PMC10786602 DOI: 10.1212/nxi.0000000000200187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 10/02/2023] [Indexed: 01/14/2024]
Abstract
BACKGROUND AND OBJECTIVES Stiff-person syndrome (SPS) and progressive encephalomyelitis with rigidity and myoclonus (PERM) are rare neurologic disorders of the CNS. Until now, exclusive GlyRα subunit-binding autoantibodies with subsequent changes in function and surface numbers were reported. GlyR autoantibodies have also been described in patients with focal epilepsy. Autoimmune reactivity against the GlyRβ subunits has not yet been shown. Autoantibodies against GlyRα1 target the large extracellular N-terminal domain. This domain shares a high degree of sequence homology with GlyRβ making it not unlikely that GlyRβ-specific autoantibody (aAb) exist and contribute to the disease pathology. METHODS In this study, we investigated serum samples from 58 patients for aAb specifically detecting GlyRβ. Studies in microarray format, cell-based assays, and primary spinal cord neurons and spinal cord tissue immunohistochemistry were performed to determine specific GlyRβ binding and define aAb binding to distinct protein regions. Preadsorption approaches of aAbs using living cells and the purified extracellular receptor domain were further used. Finally, functional consequences for inhibitory neurotransmission upon GlyRβ aAb binding were resolved by whole-cell patch-clamp recordings. RESULTS Among 58 samples investigated, cell-based assays, tissue analysis, and preadsorption approaches revealed 2 patients with high specificity for GlyRβ aAb. Quantitative protein cluster analysis demonstrated aAb binding to synaptic GlyRβ colocalized with the scaffold protein gephyrin independent of the presence of GlyRα1. At the functional level, binding of GlyRβ aAb from both patients to its target impair glycine efficacy. DISCUSSION Our study establishes GlyRβ as novel target of aAb in patients with SPS/PERM. In contrast to exclusively GlyRα1-positive sera, which alter glycine potency, aAbs against GlyRβ impair receptor efficacy for the neurotransmitter glycine. Imaging and functional analyses showed that GlyRβ aAbs antagonize inhibitory neurotransmission by affecting receptor function rather than localization.
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Affiliation(s)
- Anna-Lena Wiessler
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
| | - Ivan Talucci
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
| | - Inken Piro
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
| | - Sabine Seefried
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
| | - Verena Hörlin
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
| | - Betül B Baykan
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
| | - Erdem Tüzün
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
| | - Natascha Schaefer
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
| | - Hans M Maric
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
| | - Claudia Sommer
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
| | - Carmen Villmann
- From the Institute for Clinical Neurobiology (A.-L.W., V.H., N.S., C.V.), University of Wuerzburg; Department of Neurology (I.T., I.P., S.S., C.S.), University Hospital Wuerzburg; Rudolf Virchow Center for Integrative and Translational Bioimaging (I.T., H.M.M.), University of Wuerzburg, Germany; Department of Neurology (B.B.B.), Istanbul Faculty of Medicine; and Institute of Experimental Medical Research (E.T.), Istanbul University, Turkey
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7
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Burke SM, Avstrikova M, Noviello CM, Mukhtasimova N, Changeux JP, Thakur GA, Sine SM, Cecchini M, Hibbs RE. Structural mechanisms of α7 nicotinic receptor allosteric modulation and activation. Cell 2024; 187:1160-1176.e21. [PMID: 38382524 PMCID: PMC10950261 DOI: 10.1016/j.cell.2024.01.032] [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: 08/31/2023] [Revised: 12/05/2023] [Accepted: 01/22/2024] [Indexed: 02/23/2024]
Abstract
The α7 nicotinic acetylcholine receptor is a pentameric ligand-gated ion channel that plays an important role in cholinergic signaling throughout the nervous system. Its unique physiological characteristics and implications in neurological disorders and inflammation make it a promising but challenging therapeutic target. Positive allosteric modulators overcome limitations of traditional α7 agonists, but their potentiation mechanisms remain unclear. Here, we present high-resolution structures of α7-modulator complexes, revealing partially overlapping binding sites but varying conformational states. Structure-guided functional and computational tests suggest that differences in modulator activity arise from the stable rotation of a channel gating residue out of the pore. We extend the study using a time-resolved cryoelectron microscopy (cryo-EM) approach to reveal asymmetric state transitions for this homomeric channel and also find that a modulator with allosteric agonist activity exploits a distinct channel-gating mechanism. These results define mechanisms of α7 allosteric modulation and activation with implications across the pentameric receptor superfamily.
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Affiliation(s)
- Sean M Burke
- Molecular Biophysics Graduate Program, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Mariia Avstrikova
- Institut de Chimie de Strasbourg, UMR7177, CNRS, Université de Strasbourg, 67081 Strasbourg Cedex, France
| | - Colleen M Noviello
- Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Nuriya Mukhtasimova
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55902, USA; Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55902, USA
| | - Jean-Pierre Changeux
- Neuroscience Department, Institut Pasteur, Collège de France, 75015 Paris, France
| | - Ganesh A Thakur
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Steven M Sine
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55902, USA; Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55902, USA; Department of Neurology, Mayo Clinic College of Medicine, Rochester, MN 55902, USA.
| | - Marco Cecchini
- Institut de Chimie de Strasbourg, UMR7177, CNRS, Université de Strasbourg, 67081 Strasbourg Cedex, France.
| | - Ryan E Hibbs
- Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA; Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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8
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Wiessler AL, Hasenmüller AS, Fuhl I, Mille C, Cortes Campo O, Reinhard N, Schenk J, Heinze KG, Schaefer N, Specht CG, Villmann C. Role of the Glycine Receptor β Subunit in Synaptic Localization and Pathogenicity in Severe Startle Disease. J Neurosci 2024; 44:e0837232023. [PMID: 37963764 PMCID: PMC10860499 DOI: 10.1523/jneurosci.0837-23.2023] [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: 05/08/2023] [Revised: 09/20/2023] [Accepted: 10/16/2023] [Indexed: 11/16/2023] Open
Abstract
Startle disease is due to the disruption of recurrent inhibition in the spinal cord. Most common causes are genetic variants in genes (GLRA1, GLRB) encoding inhibitory glycine receptor (GlyR) subunits. The adult GlyR is a heteropentameric complex composed of α1 and β subunits that localizes at postsynaptic sites and replaces embryonically expressed GlyRα2 homomers. The human GlyR variants of GLRA1 and GLRB, dominant and recessive, have been intensively studied in vitro. However, the role of unaffected GlyRβ, essential for synaptic GlyR localization, in the presence of mutated GlyRα1 in vivo is not fully understood. Here, we used knock-in mice expressing endogenous mEos4b-tagged GlyRβ that were crossed with mouse Glra1 startle disease mutants. We explored the role of GlyRβ under disease conditions in mice carrying a missense mutation (shaky) or resulting from the loss of GlyRα1 (oscillator). Interestingly, synaptic targeting of GlyRβ was largely unaffected in both mouse mutants. While synaptic morphology appears unaltered in shaky animals, synapses were notably smaller in homozygous oscillator animals. Hence, GlyRβ enables transport of functionally impaired GlyRα1 missense variants to synaptic sites in shaky animals, which has an impact on the efficacy of possible compensatory mechanisms. The observed enhanced GlyRα2 expression in oscillator animals points to a compensation by other GlyRα subunits. However, trafficking of GlyRα2β complexes to synaptic sites remains functionally insufficient, and homozygous oscillator mice still die at 3 weeks after birth. Thus, both functional and structural deficits can affect glycinergic neurotransmission in severe startle disease, eliciting different compensatory mechanisms in vivo.
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Affiliation(s)
- Anna-Lena Wiessler
- Institute for Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, 97078 Würzburg, Germany
| | - Ann-Sofie Hasenmüller
- Institute for Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, 97078 Würzburg, Germany
| | - Isabell Fuhl
- Institute for Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, 97078 Würzburg, Germany
| | - Clémence Mille
- Institut National de la Santé et de la Recherche Médicale (Inserm U1195), Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Orlando Cortes Campo
- Institute for Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, 97078 Würzburg, Germany
| | - Nicola Reinhard
- Institute for Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, 97078 Würzburg, Germany
| | - Joachim Schenk
- Rudolf Virchow Center for Integrative and Translational Bioimaging, Julius-Maximilians-University of Würzburg, 97080 Würzburg, Germany
| | - Katrin G Heinze
- Rudolf Virchow Center for Integrative and Translational Bioimaging, Julius-Maximilians-University of Würzburg, 97080 Würzburg, Germany
| | - Natascha Schaefer
- Institute for Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, 97078 Würzburg, Germany
| | - Christian G Specht
- Institut National de la Santé et de la Recherche Médicale (Inserm U1195), Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Carmen Villmann
- Institute for Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, 97078 Würzburg, Germany
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9
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Lam AKM, Dutzler R. Mechanistic basis of ligand efficacy in the calcium-activated chloride channel TMEM16A. EMBO J 2023; 42:e115030. [PMID: 37984335 PMCID: PMC10711664 DOI: 10.15252/embj.2023115030] [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: 07/19/2023] [Revised: 10/27/2023] [Accepted: 11/02/2023] [Indexed: 11/22/2023] Open
Abstract
Agonist binding in ligand-gated ion channels is coupled to structural rearrangements around the binding site, followed by the opening of the channel pore. In this process, agonist efficacy describes the equilibrium between open and closed conformations in a fully ligand-bound state. Calcium-activated chloride channels in the TMEM16 family are important sensors of intracellular calcium signals and are targets for pharmacological modulators, yet a mechanistic understanding of agonist efficacy has remained elusive. Using a combination of cryo-electron microscopy, electrophysiology, and autocorrelation analysis, we now show that agonist efficacy in the ligand-gated channel TMEM16A is dictated by the conformation of the pore-lining helix α6 around the Ca2+ -binding site. The closure of the binding site, which involves the formation of a π-helix below a hinge region in α6, appears to be coupled to the opening of the inner pore gate, thereby governing the channel's open probability and conductance. Our results provide a mechanism for agonist binding and efficacy and a structural basis for the design of potentiators and partial agonists in the TMEM16 family.
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Affiliation(s)
- Andy KM Lam
- Department of BiochemistryUniversity of ZurichZurichSwitzerland
| | - Raimund Dutzler
- Department of BiochemistryUniversity of ZurichZurichSwitzerland
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10
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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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11
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Huf F, Gutierres JM, da Silva GN, Zago AM, Koenig LFC, Fernandes MC. Neuroprotection elicited by taurine in sporadic Alzheimer-like disease: benefits on memory and control of neuroinflammation in the hippocampus of rats. Mol Cell Biochem 2023:10.1007/s11010-023-04872-3. [PMID: 37874493 DOI: 10.1007/s11010-023-04872-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 10/05/2023] [Indexed: 10/25/2023]
Abstract
This study aimed to analyze whether taurine has a nootropic effect on short-term and long-term memory in a model of sporadic dementia of the Alzheimer's type (SDAT). Moreover, we evaluated the immunoreactivity and insulin receptor (IR) distribution and markers for neurons and glial cells in the hippocampus of rats with SDAT and treated with taurine. For this, Male Wistar rats received STZ (ICV, 3 mg/kg, bilateral, 5ul per site, aCFS vehicle) and were treated with taurine (100 mg/kg orally, 1 time per day, saline vehicle) for 25 days. The animals were divided into 4 groups: vehicle (VE), taurine (TAU), ICV-STZ (STZ) and ICV-STZ plus taurine (STZ + TAU). At the end of taurine treatment, short- and long-term memory were assessed by performance on object recognition and Y-maze tasks. Insulin receptor (IR) was evaluated by immunoperoxidase while mature neurons (NeuN), astrocytes (GFAP, S100B, SOX9), and microglia (Iba-1) were evaluated by immunofluorescence. STZ induced worse spatial and recognition memory (INDEX) in YM and ORT tasks. Taurine protected against STZ-induced memory impairment. SDAT reduced the population of mature neurons as well as increased astrocytic and microglial reactivity, and taurine protected against these STZ-induced effects, mainly in the CA1 region of the hippocampus. Taurine increases IR expression in the hippocampus, and protects against the reduction in the density of this receptor in CA1 induced by STZ. In conclusion, these findings demonstrate that taurine is able to enhance memory, up-regulates IR in the hippocampus, protects the neuron population, and reduces the astrogliosis found in SDAT.
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Affiliation(s)
- Fernanda Huf
- Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514 - Building 3, Porto Alegre, CEP 90050-170, RS, Brazil
| | - Jessié Martins Gutierres
- Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514 - Building 3, Porto Alegre, CEP 90050-170, RS, Brazil.
| | - Gabrielle N da Silva
- Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514 - Building 3, Porto Alegre, CEP 90050-170, RS, Brazil
| | - Adriana M Zago
- Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514 - Building 3, Porto Alegre, CEP 90050-170, RS, Brazil
| | - Luiz Felipe C Koenig
- Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514 - Building 3, Porto Alegre, CEP 90050-170, RS, Brazil
| | - Marilda C Fernandes
- Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514 - Building 3, Porto Alegre, CEP 90050-170, RS, Brazil.
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12
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Liu X, Wang W. Asymmetric gating of a human hetero-pentameric glycine receptor. Nat Commun 2023; 14:6377. [PMID: 37821459 PMCID: PMC10567788 DOI: 10.1038/s41467-023-42051-6] [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: 12/16/2022] [Accepted: 09/28/2023] [Indexed: 10/13/2023] Open
Abstract
Hetero-pentameric Cys-loop receptors constitute a major type of neurotransmitter receptors that enable signal transmission and processing in the nervous system. Despite intense investigations into their working mechanism and pharmaceutical potentials, how neurotransmitters activate these receptors remains unclear due to the lack of high-resolution structural information in the activated open state. Here we report near-atomic resolution structures resolved in digitonin consistent with all principle functional states of the human α1β GlyR, which is a major Cys-loop receptor that mediates inhibitory neurotransmission in the central nervous system of adults. Glycine binding induces cooperative and symmetric structural rearrangements in the neurotransmitter-binding extracellular domain but asymmetrical pore dilation in the transmembrane domain. Symmetric response in the extracellular domain is consistent with electrophysiological data showing cooperative glycine activation and contribution from both α1 and β subunits. A set of functionally essential but differentially charged amino acid residues in the transmembrane domain of the α1 and β subunits explains asymmetric activation. These findings provide a foundation for understanding how the gating of the Cys-loop receptor family members diverges to accommodate specific physiological environments.
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Affiliation(s)
- Xiaofen Liu
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Weiwei Wang
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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13
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Asad A, Shahidan NO, de la Vega de León A, Wiggin GR, Whitfield TT, Baxendale S. A screen of pharmacologically active compounds to identify modulators of the Adgrg6/Gpr126 signalling pathway in zebrafish embryos. Basic Clin Pharmacol Toxicol 2023; 133:364-377. [PMID: 37394692 PMCID: PMC10952222 DOI: 10.1111/bcpt.13923] [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: 04/06/2023] [Revised: 06/20/2023] [Accepted: 06/27/2023] [Indexed: 07/04/2023]
Abstract
Adhesion G protein-coupled receptors (GPCRs) are an underrepresented class of GPCRs in drug discovery. We previously developed an in vivo drug screening pipeline to identify compounds with agonist activity for Adgrg6 (Gpr126), an adhesion GPCR required for myelination of the peripheral nervous system in vertebrates. The screening assay tests for rescue of an ear defect found in adgrg6tb233c-/- hypomorphic homozygous mutant zebrafish, using the expression of versican b (vcanb) mRNA as an easily identifiable phenotype. In the current study, we used the same assay to screen a commercially available library of 1280 diverse bioactive compounds (Sigma LOPAC). Comparison with published hits from two partially overlapping compound collections (Spectrum, Tocris) confirms that the screening assay is robust and reproducible. Using a modified counter screen for myelin basic protein (mbp) gene expression, we have identified 17 LOPAC compounds that can rescue both inner ear and myelination defects in adgrg6tb233c-/- hypomorphic mutants, three of which (ebastine, S-methylisothiourea hemisulfate, and thapsigargin) are new hits. A further 25 LOPAC hit compounds were effective at rescuing the otic vcanb expression but not mbp. Together, these and previously identified hits provide a wealth of starting material for the development of novel and specific pharmacological modulators of Adgrg6 receptor activity.
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Affiliation(s)
- Anzar Asad
- School of BiosciencesUniversity of SheffieldSheffieldUK
| | | | | | | | | | - Sarah Baxendale
- School of BiosciencesUniversity of SheffieldSheffieldUK
- Sheffield Zebrafish Screening Facility, School of BiosciencesUniversity of SheffieldSheffieldUK
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14
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Liu X, Wang W. Gating mechanism of the human α1β GlyR by glycine. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.08.552474. [PMID: 37609197 PMCID: PMC10441291 DOI: 10.1101/2023.08.08.552474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Glycine receptors (GlyRs) are members of the Cys-loop receptors that constitute a major portion of neurotransmitter receptors in the human nervous system. GlyRs are found in the spinal cord and brain mediating locomotive, sensory and cognitive functions, and are targets for pharmaceutical development. GlyRs share a general gating scheme with Cys-loop receptor family members, but the underlying mechanism is unclear. Recent resolution of heteromeric GlyRs structures in multiple functional states identified an invariable 4:1 α:β subunit stoichiometry and provided snapshots in the gating cycle, challenging previous beliefs and raising the fundamental questions of how α and β subunit functions in glycine binding and channel activation. In addition, how a single glycine-bound extracellular domain conformation leads to structurally and functionally different open and desensitized states remained enigmatic. In this study, we characterized in detail equilibrium properties as well as the transition kinetics between functional states. We show that while all allosteric sites bind cooperatively to glycine, occupation of 2 sites at the α-α interfaces is necessary and sufficient for GlyR activation. We also demonstrate differential glycine concentration dependence of desensitization rate, extent, and its recovery, which suggests separate but concerted roles of ligand-binding and ionophore reorganization. Based on these observations and available structural information, we developed a comprehensive quantitative gating model that accurately predicts both equilibrium and kinetical properties throughout glycine gating cycle. This model likely applies generally to the Cys-loop receptor family and informs on pharmaceutical endeavors in function modulation of this receptor family.
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15
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Chen GL, Li J, Zhang J, Zeng B. To Be or Not to Be an Ion Channel: Cryo-EM Structures Have a Say. Cells 2023; 12:1870. [PMID: 37508534 PMCID: PMC10378246 DOI: 10.3390/cells12141870] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/13/2023] [Accepted: 07/16/2023] [Indexed: 07/30/2023] Open
Abstract
Ion channels are the second largest class of drug targets after G protein-coupled receptors. In addition to well-recognized ones like voltage-gated Na/K/Ca channels in the heart and neurons, novel ion channels are continuously discovered in both excitable and non-excitable cells and demonstrated to play important roles in many physiological processes and diseases such as developmental disorders, neurodegenerative diseases, and cancer. However, in the field of ion channel discovery, there are an unignorable number of published studies that are unsolid and misleading. Despite being the gold standard of a functional assay for ion channels, electrophysiological recordings are often accompanied by electrical noise, leak conductance, and background currents of the membrane system. These unwanted signals, if not treated properly, lead to the mischaracterization of proteins with seemingly unusual ion-conducting properties. In the recent ten years, the technical revolution of cryo-electron microscopy (cryo-EM) has greatly advanced our understanding of the structures and gating mechanisms of various ion channels and also raised concerns about the pore-forming ability of some previously identified channel proteins. In this review, we summarize cryo-EM findings on ion channels with molecular identities recognized or disputed in recent ten years and discuss current knowledge of proposed channel proteins awaiting cryo-EM analyses. We also present a classification of ion channels according to their architectures and evolutionary relationships and discuss the possibility and strategy of identifying more ion channels by analyzing structures of transmembrane proteins of unknown function. We propose that cross-validation by electrophysiological and structural analyses should be essentially required for determining molecular identities of novel ion channels.
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Affiliation(s)
- Gui-Lan Chen
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
| | - Jian Li
- College of Pharmaceutical Sciences, Gannan Medical University, Ganzhou 341000, China
| | - Jin Zhang
- School of Basic Medical Sciences, Nanchang University, Nanchang 330031, China
| | - Bo Zeng
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
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16
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Breitinger U, Sedky CA, Sticht H, Breitinger HG. Patch-clamp studies and cell viability assays suggest a distinct site for viroporin inhibitors on the E protein of SARS-CoV-2. Virol J 2023; 20:142. [PMID: 37422646 PMCID: PMC10329798 DOI: 10.1186/s12985-023-02095-y] [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: 07/30/2022] [Accepted: 06/08/2023] [Indexed: 07/10/2023] Open
Abstract
BACKGROUND SARS-CoV-2 has caused a worldwide pandemic since December 2019 and the search for pharmaceutical targets against COVID-19 remains an important challenge. Here, we studied the envelope protein E of SARS-CoV and SARS-CoV-2, a highly conserved 75-76 amino acid viroporin that is crucial for virus assembly and release. E protein channels were recombinantly expressed in HEK293 cells, a membrane-directing signal peptide ensured transfer to the plasma membrane. METHODS Viroporin channel activity of both E proteins was investigated using patch-clamp electrophysiology in combination with a cell viability assay. We verified inhibition by classical viroporin inhibitors amantadine, rimantadine and 5-(N,N-hexamethylene)-amiloride, and tested four ivermectin derivatives. RESULTS Classical inhibitors showed potent activity in patch-clamp recordings and viability assays. In contrast, ivermectin and milbemycin inhibited the E channel in patch-clamp recordings but displayed only moderate activity on the E protein in the cell viability assay, which is also sensitive to general cytotoxic activity of the tested compounds. Nemadectin and ivermectin aglycon were inactive. All ivermectin derivatives were cytotoxic at concentrations > 5 µM, i.e. below the level required for E protein inhibition. CONCLUSIONS This study demonstrates direct inhibition of the SARS-CoV-2 E protein by classical viroporin inhibitors. Ivermectin and milbemycin inhibit the E protein channel but their cytotoxicity argues against clinical application.
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Affiliation(s)
- Ulrike Breitinger
- Department of Biochemistry, German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo, 11835, Egypt.
| | - Christine Adel Sedky
- Department of Biochemistry, German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo, 11835, Egypt
| | - Heinrich Sticht
- Division of Bioinformatics, Institute for Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Hans-Georg Breitinger
- Department of Biochemistry, German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo, 11835, Egypt
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17
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Fricke S, Harnau M, Hetsch F, Liu H, Leonhard J, Eylmann A, Knauff P, Sun H, Semtner M, Meier JC. Cesium activates the neurotransmitter receptor for glycine. Front Mol Neurosci 2023; 16:1018530. [PMID: 37284465 PMCID: PMC10239821 DOI: 10.3389/fnmol.2023.1018530] [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] [Received: 08/16/2022] [Accepted: 05/02/2023] [Indexed: 06/08/2023] Open
Abstract
The monovalent cations sodium and potassium are crucial for the proper functioning of excitable cells, but, in addition, other monovalent alkali metal ions such as cesium and lithium can also affect neuronal physiology. For instance, there have been recent reports of adverse effects resulting from self-administered high concentrations of cesium in disease conditions, prompting the Food and Drug Administration (FDA) to issue an alert concerning cesium chloride. As we recently found that the monovalent cation NH4+ activates glycine receptors (GlyRs), we investigated the effects of alkali metal ions on the function of the GlyR, which belongs to one of the most widely distributed neurotransmitter receptors in the peripheral and central nervous systems. Whole-cell voltage clamp electrophysiology was performed with HEK293T cells transiently expressing different splice and RNA-edited variants of GlyR α2 and α3 homopentameric channels. By examining the influence of various milli- and sub-millimolar concentrations of lithium, sodium, potassium, and cesium on these GlyRs in comparison to its natural ligand glycine (0.1 mM), we could show that cesium activates GlyRs in a concentration- and post-transcriptional-dependent way. Additionally, we conducted atomistic molecular dynamic simulations on GlyR α3 embedded in a membrane bilayer with potassium and cesium, respectively. The simulations revealed slightly different GlyR-ion binding profiles for potassium and cesium, identifying interactions near the glycine binding pocket (potassium and cesium) and close to the RNA-edited site (cesium) in the extracellular GlyR domain. Together, these findings show that cesium acts as an agonist of GlyRs.
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Affiliation(s)
- Steffen Fricke
- Division Cell Physiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Magnus Harnau
- Division Cell Physiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Florian Hetsch
- Institute of Pathophysiology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Haoran Liu
- Structural Chemistry and Computational Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
- Institute of Chemistry, Technical University of Berlin, Berlin, Germany
| | - Julia Leonhard
- Division Cell Physiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Anna Eylmann
- Division Cell Physiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Pina Knauff
- Division Cell Physiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Han Sun
- Structural Chemistry and Computational Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
- Institute of Chemistry, Technical University of Berlin, Berlin, Germany
| | - Marcus Semtner
- Psychoneuroimmunology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Jochen C. Meier
- Division Cell Physiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
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18
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Habibi S, Nazareth K, Nichols J, Varley S, Forrester SG. The Haemonchus contortus LGC-39 subunit is a novel subtype of an acetylcholine-gated chloride channel. Int J Parasitol Drugs Drug Resist 2023; 22:20-26. [PMID: 37054482 PMCID: PMC10122009 DOI: 10.1016/j.ijpddr.2023.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 03/27/2023] [Accepted: 04/02/2023] [Indexed: 04/15/2023]
Abstract
The nematode genome exhibits a vast array of Cys-loop receptors that are activated by a diverse set of neurotransmitters and anthelmintic drugs such as ivermectin and levamisole. While many Cys-loop receptors have been functionally and pharmacologically characterized, there remains a large subset of orphan receptors where the agonist remains unknown. We have identified an orphan Cys-loop receptor, LGC-39, from the parasitic nematode Haemonchus contortus that is a novel type of cholinergic-sensitive ligand-gated chloride channel. This receptor groups outside of the acetylcholine-gated chloride channel family, in the previously named GGR-1 (GABA/Glycine Receptor-1) group of Cys-loop receptors. We found that LGC-39 forms a functional homomeric receptor when expressed in Xenopus laevis oocytes and is activated by several cholinergic ligands including acetylcholine, methacholine and surprisingly, atropine with an EC50 for atropine on the low μM range. A homology model was generated which revealed some key features of the LGC-39 ligand-binding pocket that may explain some of the elements important for atropine recognition of the LGC-39 receptor. Overall these results suggest that the GGR-1 family (now called LGC-57) of Cys-loop receptors includes novel acetylcholine-gated chloride channel subtypes and may represent important future drug targets.
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Affiliation(s)
- Sarah Habibi
- Faculty of Science, Ontario Tech University, 2000 Simcoe Street North, Oshawa, ON, L1H 7K4, Canada
| | - Kristen Nazareth
- Faculty of Science, Ontario Tech University, 2000 Simcoe Street North, Oshawa, ON, L1H 7K4, Canada
| | - Jennifer Nichols
- Faculty of Science, Ontario Tech University, 2000 Simcoe Street North, Oshawa, ON, L1H 7K4, Canada
| | - Sierra Varley
- Faculty of Science, Ontario Tech University, 2000 Simcoe Street North, Oshawa, ON, L1H 7K4, Canada
| | - Sean G Forrester
- Faculty of Science, Ontario Tech University, 2000 Simcoe Street North, Oshawa, ON, L1H 7K4, Canada.
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19
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Bondarenko V, Chen Q, Singewald K, Haloi N, Tillman TS, Howard RJ, Lindahl E, Xu Y, Tang P. Structural Elucidation of Ivermectin Binding to α7nAChR and the Induced Channel Desensitization. ACS Chem Neurosci 2023; 14:1156-1165. [PMID: 36821490 PMCID: PMC10020961 DOI: 10.1021/acschemneuro.2c00783] [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] [Indexed: 02/24/2023] Open
Abstract
The α7 nicotinic acetylcholine receptor (α7nAChR) mediates signaling in the central nervous system and cholinergic anti-inflammatory pathways. Ivermectin is a positive allosteric modulator of a full-length α7nAChR and an agonist of the α7nAChR construct containing transmembrane (TMD) and intracellular (ICD) domains, but structural insights of the binding have not previously been determined. Here, combining nuclear magnetic resonance as a primary experimental tool with Rosetta comparative modeling and molecular dynamics simulations, we have revealed details of ivermectin binding to the α7nAChR TMD + ICD and corresponding structural changes in an ivermectin-induced desensitized state. Ivermectin binding was stabilized predominantly by hydrophobic interactions from interfacial residues between adjacent subunits near the extracellular end of the TMD, where the inter-subunit gap was substantially expanded in comparison to the apo structure. The ion-permeation pathway showed a profile distinctly different from the resting-state profile but similar to profiles of desensitized α7nAChR. The ICD also exhibited structural changes, including reorientation of the MX and h3 helices relative to the channel axis. The resulting structures of the α7nAChR TMD + ICD in complex with ivermectin provide opportunities for discovering new modulators of therapeutic potential and exploring the structural basis of cytoplasmic signaling under different α7nAChR functional states.
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Affiliation(s)
- Vasyl Bondarenko
- Department
of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Qiang Chen
- Department
of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Kevin Singewald
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Nandan Haloi
- Department
of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, PO Box 1031, SE-17121 Solna, Sweden
- Department
of Applied Physics, Swedish e-Science Research Center, KTH Royal Institute of Technology, PO Box 1031, SE-17121 Solna, Sweden
| | - Tommy S. Tillman
- Department
of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Rebecca J. Howard
- Department
of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, PO Box 1031, SE-17121 Solna, Sweden
- Department
of Applied Physics, Swedish e-Science Research Center, KTH Royal Institute of Technology, PO Box 1031, SE-17121 Solna, Sweden
| | - Erik Lindahl
- Department
of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, PO Box 1031, SE-17121 Solna, Sweden
- Department
of Applied Physics, Swedish e-Science Research Center, KTH Royal Institute of Technology, PO Box 1031, SE-17121 Solna, Sweden
| | - Yan Xu
- Department
of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Pharmacology and Chemical Biology, University
of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Structural Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Physics and Astronomy, University of
Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Pei Tang
- Department
of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Pharmacology and Chemical Biology, University
of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Computational and Systems Biology, University
of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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20
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Gibbs E, Klemm E, Seiferth D, Kumar A, Ilca SL, Biggin PC, Chakrapani S. Conformational transitions and allosteric modulation in a heteromeric glycine receptor. Nat Commun 2023; 14:1363. [PMID: 36914669 PMCID: PMC10011588 DOI: 10.1038/s41467-023-37106-7] [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: 07/22/2022] [Accepted: 03/02/2023] [Indexed: 03/16/2023] Open
Abstract
Glycine Receptors (GlyRs) provide inhibitory neuronal input in the spinal cord and brainstem, which is critical for muscle coordination and sensory perception. Synaptic GlyRs are a heteromeric assembly of α and β subunits. Here we present cryo-EM structures of full-length zebrafish α1βBGlyR in the presence of an antagonist (strychnine), agonist (glycine), or agonist with a positive allosteric modulator (glycine/ivermectin). Each structure shows a distinct pore conformation with varying degrees of asymmetry. Molecular dynamic simulations found the structures were in a closed (strychnine) and desensitized states (glycine and glycine/ivermectin). Ivermectin binds at all five interfaces, but in a distinct binding pose at the β-α interface. Subunit-specific features were sufficient to solve structures without a fiduciary marker and to confirm the 4α:1β stoichiometry recently observed. We also report features of the extracellular and intracellular domains. Together, our results show distinct compositional and conformational properties of α1βGlyR and provide a framework for further study of this physiologically important channel.
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Affiliation(s)
- Eric Gibbs
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA
| | - Emily Klemm
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA
| | - David Seiferth
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Arvind Kumar
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA
| | - Serban L Ilca
- New York Structural Biology Center, New York, NY, 10027, USA
- Simons Electron Microscopy Center, New York, NY, 10027, USA
| | - Philip C Biggin
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Sudha Chakrapani
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA.
- Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106-4970, USA.
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21
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Alvarez LD, Alves NRC. Molecular determinants of tetrahydrocannabinol binding to the glycine receptor. Proteins 2023; 91:400-411. [PMID: 36271319 DOI: 10.1002/prot.26438] [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: 08/02/2022] [Revised: 10/04/2022] [Accepted: 10/18/2022] [Indexed: 02/03/2023]
Abstract
The recognition of Cannabis as a source of new compounds suitable for medical use has attracted strong interest from the scientific community in its research, and substantial progress has accumulated regarding cannabinoids' activity; however, a thorough description of their molecular mechanisms of action remains a task to complete. Highlighting their complex pharmacology, the list of cannabinoids' interactors has vastly expanded beyond the canonical cannabinoid receptors. Among those, we have focused our study on the glycine receptor (GlyR), an ion channel involved in the modulation of nervous system responses, including, to our interest, sensitivity to peripheral pain. Here, we report the use of computational methods to investigate possible binding modes between the GlyR and Δ9 -tetrahydrocannabinol (THC). After obtaining a first pose for the THC binding from a biased molecular docking simulation and subsequently evaluating it by molecular dynamic simulations, we found a dynamic system with an identifiable representative binding mode characterized by the specific interaction with two transmembrane residues (Phe293 and Ser296). Complementarily, we assessed the role of membrane cholesterol in this interaction and positively established its relevance for THC binding to GlyR. Lastly, the use of restrained molecular dynamics simulations allowed us to refine the description of the binding mode and of the cholesterol effect. Altogether, our findings contribute to the current knowledge about the GlyR-THC mode of binding and propose a new starting point for future research on how cannabinoids in general, and THC in particular, modulate pain perception in view of its possible clinical applications.
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Affiliation(s)
- Lautaro D Alvarez
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Universidad de Buenos Aires, Buenos Aires, Argentina.,CONICET-Universidad de Buenos Aires, UMYMFOR, Buenos Aires, Argentina
| | - N R Carina Alves
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Universidad de Buenos Aires, Buenos Aires, Argentina.,CONICET-Universidad de Buenos Aires, IFIBYNE, Buenos Aires, Argentina
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22
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Li Z, Chan KC, Nickels JD, Cheng X. Molecular Dynamics Refinement of Open State Serotonin 5-HT 3A Receptor Structures. J Chem Inf Model 2023; 63:1196-1207. [PMID: 36757760 DOI: 10.1021/acs.jcim.2c01441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Pentameric ligand-gated ion channels play an important role in mediating fast neurotransmissions. As a member of this receptor family, cation-selective 5-HT3 receptors are a clinical target for treating nausea and vomiting associated with chemotherapy and radiation therapy (Thompson and Lummis, 2006). Multiple cryo-electron microscopy (cryo-EM) structures of 5-HT3 receptors have been determined in distinct functional states (e.g., open, closed, etc.) (Basak et al., 2018; Basak et al., 2018; Polovinkin et al., 2018; Zhang et al., 2015). However, recent work has shown that the transmembrane pores of the open 5-HT3 receptor structures rapidly collapse and become artificially asymmetric in molecular dynamics (MD) simulations. To avoid this hydrophobic collapse, Dämgen and Biggin developed an equilibration protocol that led to a stable open state structure of the glycine receptor in MD simulations (Dämgen and Biggin, 2020). However, the protocol failed to yield open-like structures of the 5-HT3 receptor in our simulations. Here, we present a refined equilibration protocol that involves the rearrangement of the transmembrane helices to achieve stable open state structures of the 5-HT3 receptor that allow both water and ion permeation through the channel. Notably, channel gating is mediated through collective movement of the transmembrane helices, involving not only pore lining M2 helices but also their cross-talk with the adjacent M1 and M3 helices. Thus, the successful application of our refined equilibration protocol underscores the importance of the conformational coupling between the transmembrane helices in stabilizing open-like structures of the 5-HT3 receptor.
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Affiliation(s)
- Zoe Li
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy at The Ohio State University, Columbus, Ohio 43210, United States
| | - Kevin C Chan
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy at The Ohio State University, Columbus, Ohio 43210, United States
| | - Jonathan D Nickels
- Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Xiaolin Cheng
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy at The Ohio State University, Columbus, Ohio 43210, United States.,Translational Data Analytics Institute (TDAI) at The Ohio State University, Columbus, Ohio 43210, United States
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23
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Rauschenberger V, Piro I, Kasaragod VB, Hörlin V, Eckes AL, Kluck CJ, Schindelin H, Meinck HM, Wickel J, Geis C, Tüzün E, Doppler K, Sommer C, Villmann C. Glycine receptor autoantibody binding to the extracellular domain is independent from receptor glycosylation. Front Mol Neurosci 2023; 16:1089101. [PMID: 36860666 PMCID: PMC9969106 DOI: 10.3389/fnmol.2023.1089101] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 01/19/2023] [Indexed: 02/17/2023] Open
Abstract
Glycine receptor (GlyR) autoantibodies are associated with stiff-person syndrome and the life-threatening progressive encephalomyelitis with rigidity and myoclonus in children and adults. Patient histories show variability in symptoms and responses to therapeutic treatments. A better understanding of the autoantibody pathology is required to develop improved therapeutic strategies. So far, the underlying molecular pathomechanisms include enhanced receptor internalization and direct receptor blocking altering GlyR function. A common epitope of autoantibodies against the GlyRα1 has been previously defined to residues 1A-33G at the N-terminus of the mature GlyR extracellular domain. However, if other autoantibody binding sites exist or additional GlyR residues are involved in autoantibody binding is yet unknown. The present study investigates the importance of receptor glycosylation for binding of anti-GlyR autoantibodies. The glycine receptor α1 harbors only one glycosylation site at the amino acid residue asparagine 38 localized in close vicinity to the identified common autoantibody epitope. First, non-glycosylated GlyRs were characterized using protein biochemical approaches as well as electrophysiological recordings and molecular modeling. Molecular modeling of non-glycosylated GlyRα1 did not show major structural alterations. Moreover, non-glycosylation of the GlyRα1N38Q did not prevent the receptor from surface expression. At the functional level, the non-glycosylated GlyR demonstrated reduced glycine potency, but patient GlyR autoantibodies still bound to the surface-expressed non-glycosylated receptor protein in living cells. Efficient adsorption of GlyR autoantibodies from patient samples was possible by binding to native glycosylated and non-glycosylated GlyRα1 expressed in living not fixed transfected HEK293 cells. Binding of patient-derived GlyR autoantibodies to the non-glycosylated GlyRα1 offered the possibility to use purified non-glycosylated GlyR extracellular domain constructs coated on ELISA plates and use them as a fast screening readout for the presence of GlyR autoantibodies in patient serum samples. Following successful adsorption of patient autoantibodies by GlyR ECDs, binding to primary motoneurons and transfected cells was absent. Our results indicate that the glycine receptor autoantibody binding is independent of the receptor's glycosylation state. Purified non-glycosylated receptor domains harbouring the autoantibody epitope thus provide, an additional reliable experimental tool besides binding to native receptors in cell-based assays for detection of autoantibody presence in patient sera.
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Affiliation(s)
- Vera Rauschenberger
- Institute of Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Inken Piro
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Vikram Babu Kasaragod
- Rudolf Virchow Centre for Integrative and Translational Bioimaging, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Verena Hörlin
- Institute of Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Anna-Lena Eckes
- Institute of Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Christoph J. Kluck
- Institute of Biochemistry, Emil-Fischer-Center, FAU Erlangen-Nürnberg, Erlangen, Germany
| | - Hermann Schindelin
- Rudolf Virchow Centre for Integrative and Translational Bioimaging, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Hans-Michael Meinck
- Department of Neurology, University Hospital Heidelberg, Heidelberg, Germany
| | - Jonathan Wickel
- Section Translational Neuroimmunology, Department of Neurology, Jena University Hospital, Jena, Germany
| | - Christian Geis
- Section Translational Neuroimmunology, Department of Neurology, Jena University Hospital, Jena, Germany
| | - Erdem Tüzün
- Institute of Experimental Medicine, Istanbul University, Istanbul, Türkiye
| | - Kathrin Doppler
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Claudia Sommer
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Carmen Villmann
- Institute of Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, Würzburg, Germany,*Correspondence: Carmen Villmann, ✉
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24
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Illumination of a progressive allosteric mechanism mediating the glycine receptor activation. Nat Commun 2023; 14:795. [PMID: 36781912 PMCID: PMC9925812 DOI: 10.1038/s41467-023-36471-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 02/02/2023] [Indexed: 02/15/2023] Open
Abstract
Pentameric ligand-gated ion channel mediate signal transduction at chemical synapses by transiting between resting and open states upon neurotransmitter binding. Here, we investigate the gating mechanism of the glycine receptor fluorescently labeled at the extracellular-transmembrane interface by voltage-clamp fluorometry (VCF). Fluorescence reports a glycine-elicited conformational change that precedes pore opening. Low concentrations of glycine, partial agonists or specific mixtures of glycine and strychnine trigger the full fluorescence signal while weakly activating the channel. Molecular dynamic simulations of a partial agonist bound-closed Cryo-EM structure show a highly dynamic nature: a marked structural flexibility at both the extracellular-transmembrane interface and the orthosteric site, generating docking properties that recapitulate VCF data. This work illuminates a progressive propagating transition towards channel opening, highlighting structural plasticity within the mechanism of action of allosteric effectors.
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25
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Liu X, Wang W. Asymmetric gating of a human hetero-pentameric glycine receptor. RESEARCH SQUARE 2023:rs.3.rs-2386831. [PMID: 36711971 PMCID: PMC9882600 DOI: 10.21203/rs.3.rs-2386831/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Hetero-pentameric Cys-loop receptors constitute a major type of neurotransmitter receptors that enable signal transmission and processing in the nervous system. Despite intense investigations in their working mechanism and pharmaceutical potentials, how neurotransmitters activate these receptors remain unclear due to the lack of high-resolution structural information in the activated open state. Here we report near-atomic resolution structures in all principle functional states of the human α1β GlyR, which is a major Cys-loop receptor that mediates inhibitory neurotransmission in the central nervous system of adults. Glycine binding induced cooperative and symmetric structural rearrangements in the neurotransmitter-binding extracellular domain, but asymmetrical pore dilation in the transmembrane domain. Symmetric response in the extracellular domain is consistent with electrophysiological data showing similar contribution to activation from all the α1 and β subunits. A set of functionally essential but differentially charged amino-acid residues in the transmembrane domain of the α1 and β subunits explains asymmetric activation. These findings point to a gating mechanism that is distinct from homomeric receptors but more compatible with heteromeric GlyRs being clustered at synapses through β subunit-scaffolding protein interactions. Such mechanism provides foundation for understanding how gating of the Cys-loop receptor members diverge to accommodate specific physiological environment.
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Affiliation(s)
- Xiaofen Liu
- University of Texas Southwestern Medical Center
| | - Weiwei Wang
- University of Texas Southwestern Medical Center
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26
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Duong SL, Prüss H. Molecular disease mechanisms of human antineuronal monoclonal autoantibodies. Trends Mol Med 2023; 29:20-34. [PMID: 36280535 DOI: 10.1016/j.molmed.2022.09.011] [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: 08/05/2022] [Revised: 09/28/2022] [Accepted: 09/30/2022] [Indexed: 11/22/2022]
Abstract
Autoantibodies targeting brain antigens can mediate a wide range of neurological symptoms ranging from epileptic seizures to psychosis to dementia. Although earlier experimental work indicated that autoantibodies can be directly pathogenic, detailed studies on disease mechanisms, biophysical autoantibody properties, and target interactions were hampered by the availability of human material and the paucity of monospecific disease-related autoantibodies. The emerging generation of patient-derived monoclonal autoantibodies (mAbs) provides a novel platform for the detailed characterization of immunobiology and autoantibody pathogenicity in vitro and in animal models. This Feature Review focuses on recent advances in mAb generation and discusses their potential as powerful scientific tools for high-resolution imaging, antigenic target identification, atomic-level structural analyses, and the development of antibody-selective immunotherapies.
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Affiliation(s)
- Sophie L Duong
- Department of Neurology and Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany; German Center for Neurodegenerative Diseases (DZNE) Berlin, 10117 Berlin, Germany; Berlin Institute of Health at Charité - Universitätsmedizin Berlin, BIH Biomedical Innovation Academy, BIH Charité Junior Clinician Scientist Program, Charitéplatz 1, 10117 Berlin, Germany
| | - Harald Prüss
- Department of Neurology and Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany; German Center for Neurodegenerative Diseases (DZNE) Berlin, 10117 Berlin, Germany.
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27
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The mechanisms of chromogranin B-regulated Cl- homeostasis. Biochem Soc Trans 2022; 50:1659-1672. [PMID: 36511243 DOI: 10.1042/bst20220435] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/25/2022] [Accepted: 12/01/2022] [Indexed: 12/15/2022]
Abstract
Chloride is the most abundant inorganic anions in almost all cells and in human circulation systems. Its homeostasis is therefore important for systems physiology and normal cellular activities. This topic has been extensively studied with chloride loaders and extruders expressed in both cell surfaces and intracellular membranes. With the newly discovered, large-conductance, highly selective Cl- channel formed by membrane-bound chromogranin B (CHGB), which differs from all other known anion channels of conventional transmembrane topology, and is distributed in plasma membranes, endomembrane systems, endosomal, and endolysosomal compartments in cells expressing it, we will discuss the potential physiological importance of the CHGB channels to Cl- homeostasis, cellular excitability and volume control, and cation uptake or release at the cellular and subcellular levels. These considerations and CHGB's association with human diseases make the CHGB channel a possible druggable target for future molecular therapeutics.
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28
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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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29
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Gallagher CI, Ha DA, Harvey RJ, Vandenberg RJ. Positive Allosteric Modulators of Glycine Receptors and Their Potential Use in Pain Therapies. Pharmacol Rev 2022; 74:933-961. [PMID: 36779343 PMCID: PMC9553105 DOI: 10.1124/pharmrev.122.000583] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 04/26/2022] [Accepted: 05/13/2022] [Indexed: 11/22/2022] Open
Abstract
Glycine receptors are ligand-gated ion channels that mediate synaptic inhibition throughout the mammalian spinal cord, brainstem, and higher brain regions. They have recently emerged as promising targets for novel pain therapies due to their ability to produce antinociception by inhibiting nociceptive signals within the dorsal horn of the spinal cord. This has greatly enhanced the interest in developing positive allosteric modulators of glycine receptors. Several pharmaceutical companies and research facilities have attempted to identify new therapeutic leads by conducting large-scale screens of compound libraries, screening new derivatives from natural sources, or synthesizing novel compounds that mimic endogenous compounds with antinociceptive activity. Advances in structural techniques have also led to the publication of multiple high-resolution structures of the receptor, highlighting novel allosteric binding sites and providing additional information for previously identified binding sites. This has greatly enhanced our understanding of the functional properties of glycine receptors and expanded the structure activity relationships of novel pharmacophores. Despite this, glycine receptors are yet to be used as drug targets due to the difficulties in obtaining potent, selective modulators with favorable pharmacokinetic profiles that are devoid of side effects. This review presents a summary of the structural basis for how current compounds cause positive allosteric modulation of glycine receptors and discusses their therapeutic potential as analgesics. SIGNIFICANCE STATEMENT: Chronic pain is a major cause of disability, and in Western societies, this will only increase as the population ages. Despite the high level of prevalence and enormous socioeconomic burden incurred, treatment of chronic pain remains limited as it is often refractory to current analgesics, such as opioids. The National Institute for Drug Abuse has set finding effective, safe, nonaddictive strategies to manage chronic pain as their top priority. Positive allosteric modulators of glycine receptors may provide a therapeutic option.
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Affiliation(s)
- Casey I Gallagher
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
| | - Damien A Ha
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
| | - Robert J Harvey
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
| | - Robert J Vandenberg
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
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30
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Xu W, Wu L, Liu S, Liu X, Cao X, Zhou C, Zhang J, Fu Y, Guo Y, Wu Y, Tan Q, Wang L, Liu J, Jiang L, Fan Z, Pei Y, Yu J, Cheng J, Zhao S, Hao X, Liu ZJ, Hua T. Structural basis for strychnine activation of human bitter taste receptor TAS2R46. Science 2022; 377:1298-1304. [DOI: 10.1126/science.abo1633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Taste sensing is a sophisticated chemosensory process, and bitter taste perception is mediated by type 2 taste receptors (TAS2Rs), or class T G protein–coupled receptors. Understanding the detailed molecular mechanisms behind taste sensation is hindered by a lack of experimental receptor structures. Here, we report the cryo–electron microscopy structures of human TAS2R46 complexed with chimeric mini–G protein gustducin, in both strychnine-bound and apo forms. Several features of TAS2R46 are disclosed, including distinct receptor structures that compare with known GPCRs, a new “toggle switch,” activation-related motifs, and precoupling with mini–G protein gustducin. Furthermore, the dynamic extracellular and more-static intracellular parts of TAS2R46 suggest possible diverse ligand-recognition and activation processes. This study provides a basis for further exploration of other bitter taste receptors and their therapeutic applications.
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Affiliation(s)
- Weixiu Xu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Lijie Wu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Shenhui Liu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiao Liu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiaoling Cao
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Cui Zhou
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jinyi Zhang
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - You Fu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yu Guo
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Yiran Wu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Qiwen Tan
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Ling Wang
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Junlin Liu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Longquan Jiang
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Zhongbo Fan
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yuan Pei
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Jingyi Yu
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jianjun Cheng
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Suwen Zhao
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiaojiang Hao
- State Key Laboratory of Phytochemistry and Plant Resource in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650210, China
| | - Zhi-Jie Liu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Tian Hua
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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31
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GABA A receptor proline 273 at the interdomain interface of the β 2 subunit regulates entry into desensitization and opening/closing transitions. Life Sci 2022; 308:120943. [PMID: 36096246 DOI: 10.1016/j.lfs.2022.120943] [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: 05/31/2022] [Revised: 08/29/2022] [Accepted: 09/06/2022] [Indexed: 11/23/2022]
Abstract
AIMS GABAA receptors belong to Cys-loop ion channel family and mediate inhibition in the brain. Despite the abundance of structural data on receptor structure, the molecular scenarios of activation are unknown. In this study we investigated the role of a β2P273 residue in channel gating transitions. This residue is located in a central position of the M2-M3 linker of the interdomain interface, expected to be predisposed to interact with another interfacial element, the β1-β2 loop of the extracellular side. The interactions occurring on this interface have been reported to couple agonist binding to channel gating. MAIN METHODS We recorded micro- and macroscopic current responses of recombinant GABAA receptors mutated at the β2P273 residue (to A, K, E) to saturating GABA. Electrophysiological data served as basis to kinetic modeling, used to decipher which gating transition were affected by mutations. KEY FINDINGS Mutations of this residue impaired macroscopic desensitization and accelerated current deactivation with P273E mutant showing greatest deviation from wild-type. Single-channel analysis revealed alterations mainly in short-lived shut times and shortening of openings, resulting in dramatic changes in intraburst open probability. Kinetic modeling indicated that β2P273 mutants show diminished entry into desensitized and open states as well as faster channel closing transitions. SIGNIFICANCE In conclusion, we demonstrate that β2P273 of the M2-M3 linker is a crucial element of the ECD-TMD interface regulating the receptor's ability to undergo late gating transitions. Henceforth, this region could be an important target for new pharmacological tools affecting GABAAR-mediated inhibition.
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Kumar A, Kindig K, Rao S, Zaki AM, Basak S, Sansom MSP, Biggin PC, Chakrapani S. Structural basis for cannabinoid-induced potentiation of alpha1-glycine receptors in lipid nanodiscs. Nat Commun 2022; 13:4862. [PMID: 35982060 PMCID: PMC9388682 DOI: 10.1038/s41467-022-32594-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 08/08/2022] [Indexed: 11/23/2022] Open
Abstract
Nociception and motor coordination are critically governed by glycine receptor (GlyR) function at inhibitory synapses. Consequentially, GlyRs are attractive targets in the management of chronic pain and in the treatment of several neurological disorders. High-resolution mechanistic details of GlyR function and its modulation are just emerging. While it has been known that cannabinoids such as Δ9-tetrahydrocannabinol (THC), the principal psychoactive constituent in marijuana, potentiate GlyR in the therapeutically relevant concentration range, the molecular mechanism underlying this effect is still not understood. Here, we present Cryo-EM structures of full-length GlyR reconstituted into lipid nanodisc in complex with THC under varying concentrations of glycine. The GlyR-THC complexes are captured in multiple conformational states that reveal the basis for THC-mediated potentiation, manifested as different extents of opening at the level of the channel pore. Taken together, these structural findings, combined with molecular dynamics simulations and functional analysis, provide insights into the potential THC binding site and the allosteric coupling to the channel pore.
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Affiliation(s)
- Arvind Kumar
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Kayla Kindig
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Shanlin Rao
- Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Sandip Basak
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Philip C Biggin
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Sudha Chakrapani
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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Ivica J, Zhu H, Lape R, Gouaux E, Sivilotti LG. Aminomethanesulfonic acid illuminates the boundary between full and partial agonists of the pentameric glycine receptor. eLife 2022; 11:79148. [PMID: 35975975 PMCID: PMC9462852 DOI: 10.7554/elife.79148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 08/16/2022] [Indexed: 11/26/2022] Open
Abstract
To clarify the determinants of agonist efficacy in pentameric ligand-gated ion channels, we examined a new compound, aminomethanesulfonic acid (AMS), a molecule intermediate in structure between glycine and taurine. Despite wide availability, to date there are no reports of AMS action on glycine receptors, perhaps because AMS is unstable at physiological pH. Here, we show that at pH 5, AMS is an efficacious agonist, eliciting in zebrafish α1 glycine receptors a maximum single-channel open probability of 0.85, much greater than that of β-alanine (0.54) or taurine (0.12), and second only to that of glycine itself (0.96). Thermodynamic cycle analysis of the efficacy of these closely related agonists shows supra-additive interaction between changes in the length of the agonist molecule and the size of the anionic moiety. Single particle cryo-electron microscopy structures of AMS-bound glycine receptors show that the AMS-bound agonist pocket is as compact as with glycine, and three-dimensional classification demonstrates that the channel populates the open and the desensitized states, like glycine, but not the closed intermediate state associated with the weaker partial agonists, β-alanine and taurine. Because AMS is on the cusp between full and partial agonists, it provides a new tool to help us understand agonist action in the pentameric superfamily of ligand-gated ion channels.
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Affiliation(s)
- Josip Ivica
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Hongtao Zhu
- Vollum Institute, Oregon Health and Science University Hospital, Portland, United States
| | - Remigijus Lape
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Eric Gouaux
- Vollum Institute, Oregon Health and Science University Hospital, Portland, United States
| | - Lucia G Sivilotti
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
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Zhu H. Structure and Mechanism of Glycine Receptor Elucidated by Cryo-Electron Microscopy. Front Pharmacol 2022; 13:925116. [PMID: 36016557 PMCID: PMC9395720 DOI: 10.3389/fphar.2022.925116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 06/14/2022] [Indexed: 11/17/2022] Open
Abstract
Glycine receptors (GlyRs) are pentameric ion channels that mediate fast inhibitory neurotransmission. GlyRs are found in the central nervous system including the spinal cord, brain stem, and cerebellum, as well as in the retina, sperm, macrophages, hippocampus, cochlea, and liver. Due to their crucial roles in counter-balancing excitatory signals and pain signal transmission, GlyR dysfunction can lead to severe diseases, and as a result, compounds that modify GlyR activity may have tremendous therapeutic potential. Despite this potential, the development of GlyR-specific small-molecule ligands is lacking. Over the past few years, high-resolution structures of both homomeric and heteromeric GlyRs structures in various conformations have provided unprecedented details defining the pharmacology of ligand binding, subunit composition, and mechanisms of channel gating. These high-quality structures will undoubtedly help with the development of GlyR-targeted therapies.
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Computational methods for ultrastructural analysis of synaptic complexes. Curr Opin Neurobiol 2022; 76:102611. [PMID: 35952541 DOI: 10.1016/j.conb.2022.102611] [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: 02/28/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 11/21/2022]
Abstract
Electron microscopy (EM) provided fundamental insights about the ultrastructure of neuronal synapses. The large amount of information present in the contemporary EM datasets precludes a thorough assessment by visual inspection alone, thus requiring computational methods for the analysis of the data. Here, I review image processing software methods ranging from membrane tracing in large volume datasets to high resolution structures of synaptic complexes. Particular attention is payed to molecular level analysis provided by recent cryo-electron microscopy and tomography methods.
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36
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Mhashal AR, Yoluk O, Orellana L. Exploring the Conformational Impact of Glycine Receptor TM1-2 Mutations Through Coarse-Grained Analysis and Atomistic Simulations. Front Mol Biosci 2022; 9:890851. [PMID: 35836931 PMCID: PMC9275627 DOI: 10.3389/fmolb.2022.890851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 05/05/2022] [Indexed: 11/13/2022] Open
Abstract
Pentameric ligand-gated ion channels (PLGICs) are a family of proteins that convert chemical signals into ion fluxes through cellular membranes. Their structures are highly conserved across all kingdoms from bacteria to eukaryotes. Beyond their classical roles in neurotransmission and neurological disorders, PLGICs have been recently related to cell proliferation and cancer. Here, we focus on the best characterized eukaryotic channel, the glycine receptor (GlyR), to investigate its mutational patterns in genomic-wide tumor screens and compare them with mutations linked to hyperekplexia (HPX), a Mendelian neuromotor disease that disrupts glycinergic currents. Our analysis highlights that cancer mutations significantly accumulate across TM1 and TM2, partially overlapping with HPX changes. Based on 3D-clustering, conservation, and phenotypic data, we select three mutations near the pore, expected to impact GlyR conformation, for further study by molecular dynamics (MD). Using principal components from experimental GlyR ensembles as framework, we explore the motions involved in transitions from the human closed and desensitized structures and how they are perturbed by mutations. Our MD simulations show that WT GlyR spontaneously explores opening and re-sensitization transitions that are significantly impaired by mutations, resulting in receptors with altered permeability and desensitization properties in agreement with HPX functional data.
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Recent Insight into Lipid Binding and Lipid Modulation of Pentameric Ligand-Gated Ion Channels. Biomolecules 2022; 12:biom12060814. [PMID: 35740939 PMCID: PMC9221113 DOI: 10.3390/biom12060814] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/03/2022] [Accepted: 06/08/2022] [Indexed: 02/04/2023] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) play a leading role in synaptic communication, are implicated in a variety of neurological processes, and are important targets for the treatment of neurological and neuromuscular disorders. Endogenous lipids and lipophilic compounds are potent modulators of pLGIC function and may help shape synaptic communication. Increasing structural and biophysical data reveal sites for lipid binding to pLGICs. Here, we update our evolving understanding of pLGIC–lipid interactions highlighting newly identified modes of lipid binding along with the mechanistic understanding derived from the new structural data.
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Chen X, Wilson KA, Schaefer N, De Hayr L, Windsor M, Scalais E, van Rijckevorsel G, Stouffs K, Villmann C, O’Mara ML, Lynch JW, Harvey RJ. Loss, Gain and Altered Function of GlyR α2 Subunit Mutations in Neurodevelopmental Disorders. Front Mol Neurosci 2022; 15:886729. [PMID: 35571374 PMCID: PMC9103196 DOI: 10.3389/fnmol.2022.886729] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/07/2022] [Indexed: 12/11/2022] Open
Abstract
Glycine receptors (GlyRs) containing the α2 subunit govern cell fate, neuronal migration and synaptogenesis in the developing cortex and spinal cord. Rare missense variants and microdeletions in the X-linked GlyR α2 subunit gene (GLRA2) have been associated with human autism spectrum disorder (ASD), where they typically cause a loss-of-function via protein truncation, reduced cell-surface trafficking and/or reduced glycine sensitivity (e.g., GLRA2Δex8-9 and extracellular domain variants p.N109S and p.R126Q). However, the GlyR α2 missense variant p.R323L in the intracellular M3-M4 domain results in a gain-of-function characterized by slower synaptic decay times, longer duration active periods and increases in channel conductance. This study reports the functional characterization of four missense variants in GLRA2 associated with ASD or developmental disorders (p.V-22L, p.N38K, p.K213E, p.T269M) using a combination of bioinformatics, molecular dynamics simulations, cellular models of GlyR trafficking and electrophysiology in artificial synapses. The GlyR α2V–22L variant resulted in altered predicted signal peptide cleavage and a reduction in cell-surface expression, suggestive of a partial loss-of-function. Similarly, GlyR α2N38K homomers showed reduced cell-surface expression, a reduced affinity for glycine and a reduced magnitude of IPSCs in artificial synapses. By contrast, GlyR α2K213E homomers showed a slight reduction in cell-surface expression, but IPSCs were larger, with faster rise/decay times, suggesting a gain-of-function. Lastly, GlyR α2T269M homomers exhibited a high glycine sensitivity accompanied by a substantial leak current, suggestive of an altered function that could dramatically enhance glycinergic signaling. These results may explain the heterogeneity of clinical phenotypes associated with GLRA2 mutations and reveal that missense variants can result in a loss, gain or alteration of GlyR α2 function. In turn, these GlyR α2 missense variants are likely to either negatively or positively deregulate cortical progenitor homeostasis and neuronal migration in the developing brain, leading to changes in cognition, learning, and memory.
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Affiliation(s)
- Xiumin Chen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Katie A. Wilson
- Research School of Chemistry, The Australian National University, Canberra, ACT, Australia
| | - Natascha Schaefer
- Institute of Clinical Neurobiology, University Hospital, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Lachlan De Hayr
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Maroochydore, QLD, Australia
- Sunshine Coast Health Institute, Birtinya, QLD, Australia
| | - Mark Windsor
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Maroochydore, QLD, Australia
- Sunshine Coast Health Institute, Birtinya, QLD, Australia
| | - Emmanuel Scalais
- Neurologie Pédiatrique, Centre Hospitalier de Luxembourg, Luxembourg, Luxembourg
| | | | - Katrien Stouffs
- Center for Medical Genetics, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium
| | - Carmen Villmann
- Institute of Clinical Neurobiology, University Hospital, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Megan L. O’Mara
- Research School of Chemistry, The Australian National University, Canberra, ACT, Australia
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, QLD, Australia
| | - Joseph W. Lynch
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Robert J. Harvey
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Maroochydore, QLD, Australia
- Sunshine Coast Health Institute, Birtinya, QLD, Australia
- *Correspondence: Robert J. Harvey,
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Zlotos DP, Mandour YM, Jensen AA. Strychnine and its mono- and dimeric analogues: a pharmaco-chemical perspective. Nat Prod Rep 2022; 39:1910-1937. [PMID: 35380133 DOI: 10.1039/d1np00079a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covering: up to November 2021Since its isolation in 1818, strychnine has attracted the attention of a plethora of chemists and pharmacologists who have established its structure, developed total syntheses, and examined its complex pharmacology. While numerous reviews on structure elucidation and total synthesis of strychnine are available, reports on structure-activity relationships (SARs) of this fascinating alkaloid are rare. In this review, we present and discuss structures, synthetic approaches, metabolic transformations, and the diverse pharmacological actions of strychnine and its mono- and dimeric analogues. Particular attention is given to its SARs at glycine receptors (GlyRs) in light of recently published high-resolution structures of strychnine-GlyR complexes. Other pharmacological actions of strychnine and its derivatives, such as their antagonistic properties at nicotinic acetylcholine receptors (nAChRs), allosteric modulation of muscarinic acetylcholine receptors as well as anti-cancer and anti-plasmodial effects are also critically reviewed, and possible future developments in the field are discussed.
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Affiliation(s)
- Darius P Zlotos
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, The German University in Cairo, New Cairo City, 11835 Cairo, Egypt.
| | - Yasmine M Mandour
- School of Life and Medical Sciences, University of Hertfordshire hosted by Global Academic Foundation, New Administrative Capital, Cairo, Egypt
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
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40
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Rotational Dynamics of The Transmembrane Domains Play an Important Role in Peptide Dynamics of Viral Fusion and Ion Channel Forming Proteins—A Molecular Dynamics Simulation Study. Viruses 2022; 14:v14040699. [PMID: 35458429 PMCID: PMC9024552 DOI: 10.3390/v14040699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/02/2022] [Accepted: 03/20/2022] [Indexed: 02/04/2023] Open
Abstract
Focusing on the transmembrane domains (TMDs) of viral fusion and channel-forming proteins (VCPs), experimentally available and newly generated peptides in an ideal conformation of the S and E proteins of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) and SARS-CoV, gp41 and Vpu, both of human immunodeficiency virus type 1 (HIV-1), haemagglutinin and M2 of influenza A, as well as gB of herpes simplex virus (HSV), are embedded in a fully hydrated lipid bilayer and used in multi-nanosecond molecular dynamics simulations. It is aimed to identify differences in the dynamics of the individual TMDs of the two types of viral membrane proteins. The assumption is made that the dynamics of the individual TMDs are decoupled from their extra-membrane domains, and that the mechanics of the TMDs are distinct from each other due to the different mechanism of function of the two types of proteins. The diffusivity coefficient (DC) of the translational and rotational diffusion is decreased in the oligomeric state of the TMDs compared to those values when calculated from simulations in their monomeric state. When comparing the calculations for two different lengths of the TMD, a longer full peptide and a shorter purely TMD stretch, (i) the difference of the calculated DCs begins to level out when the difference exceeds approximately 15 amino acids per peptide chain, and (ii) the channel protein rotational DC is the most affected diffusion parameter. The rotational dynamics of the individual amino acids within the middle section of the TMDs of the fusion peptides remain high upon oligomerization, but decrease for the channel peptides, with an increasing number of monomers forming the oligomeric state, suggesting an entropic penalty on oligomerization for the latter.
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41
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San Martín VP, Sazo A, Utreras E, Moraga-Cid G, Yévenes GE. Glycine Receptor Subtypes and Their Roles in Nociception and Chronic Pain. Front Mol Neurosci 2022; 15:848642. [PMID: 35401105 PMCID: PMC8984470 DOI: 10.3389/fnmol.2022.848642] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 01/28/2022] [Indexed: 01/23/2023] Open
Abstract
Disruption of the inhibitory control provided by the glycinergic system is one of the major mechanisms underlying chronic pain. In line with this concept, recent studies have provided robust proof that pharmacological intervention of glycine receptors (GlyRs) restores the inhibitory function and exerts anti-nociceptive effects on preclinical models of chronic pain. A targeted regulation of the glycinergic system requires the identification of the GlyR subtypes involved in chronic pain states. Nevertheless, the roles of individual GlyR subunits in nociception and in chronic pain are yet not well defined. This review aims to provide a systematic outline on the contribution of GlyR subtypes in chronic pain mechanisms, with a particular focus on molecular pathways of spinal glycinergic dis-inhibition mediated by post-translational modifications at the receptor level. The current experimental evidence has shown that phosphorylation of synaptic α1β and α3β GlyRs are involved in processes of spinal glycinergic dis-inhibition triggered by chronic inflammatory pain. On the other hand, the participation of α2-containing GlyRs and of β subunits in pain signaling have been less studied and remain undefined. Although many questions in the field are still unresolved, future progress in GlyR research may soon open new exciting avenues into understanding and controlling chronic pain.
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Affiliation(s)
- Victoria P. San Martín
- Department of Physiology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
- Millennium Nucleus for the Study of Pain (MiNuSPain), Santiago, Chile
| | - Anggelo Sazo
- Department of Physiology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
- Millennium Nucleus for the Study of Pain (MiNuSPain), Santiago, Chile
| | - Elías Utreras
- Millennium Nucleus for the Study of Pain (MiNuSPain), Santiago, Chile
- Department of Biology, Faculty of Science, Universidad de Chile, Santiago, Chile
| | - Gustavo Moraga-Cid
- Department of Physiology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
- Millennium Nucleus for the Study of Pain (MiNuSPain), Santiago, Chile
| | - Gonzalo E. Yévenes
- Department of Physiology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
- Millennium Nucleus for the Study of Pain (MiNuSPain), Santiago, Chile
- *Correspondence: Gonzalo E. Yévenes,
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Marcogliese PC, Deal SL, Andrews J, Harnish JM, Bhavana VH, Graves HK, Jangam S, Luo X, Liu N, Bei D, Chao YH, Hull B, Lee PT, Pan H, Bhadane P, Huang MC, Longley CM, Chao HT, Chung HL, Haelterman NA, Kanca O, Manivannan SN, Rossetti LZ, German RJ, Gerard A, Schwaibold EMC, Fehr S, Guerrini R, Vetro A, England E, Murali CN, Barakat TS, van Dooren MF, Wilke M, van Slegtenhorst M, Lesca G, Sabatier I, Chatron N, Brownstein CA, Madden JA, Agrawal PB, Keren B, Courtin T, Perrin L, Brugger M, Roser T, Leiz S, Mau-Them FT, Delanne J, Sukarova-Angelovska E, Trajkova S, Rosenhahn E, Strehlow V, Platzer K, Keller R, Pavinato L, Brusco A, Rosenfeld JA, Marom R, Wangler MF, Yamamoto S. Drosophila functional screening of de novo variants in autism uncovers damaging variants and facilitates discovery of rare neurodevelopmental diseases. Cell Rep 2022; 38:110517. [PMID: 35294868 PMCID: PMC8983390 DOI: 10.1016/j.celrep.2022.110517] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 09/23/2021] [Accepted: 02/18/2022] [Indexed: 12/30/2022] Open
Abstract
Individuals with autism spectrum disorder (ASD) exhibit an increased burden of de novo mutations (DNMs) in a broadening range of genes. While these studies have implicated hundreds of genes in ASD pathogenesis, which DNMs cause functional consequences in vivo remains unclear. We functionally test the effects of ASD missense DNMs using Drosophila through "humanization" rescue and overexpression-based strategies. We examine 79 ASD variants in 74 genes identified in the Simons Simplex Collection and find 38% of them to cause functional alterations. Moreover, we identify GLRA2 as the cause of a spectrum of neurodevelopmental phenotypes beyond ASD in 13 previously undiagnosed subjects. Functional characterization of variants in ASD candidate genes points to conserved neurobiological mechanisms and facilitates gene discovery for rare neurodevelopmental diseases.
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Affiliation(s)
- Paul C Marcogliese
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Samantha L Deal
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA; Program in Developmental Biology, BCM, Houston, TX 77030, USA
| | - Jonathan Andrews
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - J Michael Harnish
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - V Hemanjani Bhavana
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Hillary K Graves
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Sharayu Jangam
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Xi Luo
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA; Department of Pediatrics, Division of Hematology/Oncology, BCM, Houston, TX 77030, USA
| | - Ning Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA; Baylor Genetics Laboratories, Houston, TX 77021, USA
| | - Danqing Bei
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Yu-Hsin Chao
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Brooke Hull
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Hongling Pan
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Pradnya Bhadane
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Mei-Chu Huang
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Colleen M Longley
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA; Program in Developmental Biology, BCM, Houston, TX 77030, USA
| | - Hsiao-Tuan Chao
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA; Department of Pediatrics, Division of Neurology and Developmental Neuroscience, BCM, Houston, TX 77030, USA; Department of Neuroscience, BCM, Houston, TX 77030, USA; McNair Medical Institute, The Robert and Janice McNair Foundation, Houston, TX 77030, USA; TCH, Houston, TX 77030, USA; Development, Disease Models & Therapeutics Graduate Program, BCM, Houston, TX 77030, USA
| | - Hyung-Lok Chung
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA; Howard Hughes Medical Institute, Houston, TX 77030, USA
| | - Nele A Haelterman
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Sathiya N Manivannan
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Linda Z Rossetti
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA
| | - Ryan J German
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA
| | - Amanda Gerard
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; TCH, Houston, TX 77030, USA
| | | | - Sarah Fehr
- Praxis für Humangenetik Tübingen, Tübingen, Germany
| | - Renzo Guerrini
- Neuroscience Department, Children's Hospital Meyer-University of Florence, Florence, Italy
| | - Annalisa Vetro
- Neuroscience Department, Children's Hospital Meyer-University of Florence, Florence, Italy
| | - Eleina England
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Chaya N Murali
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; TCH, Houston, TX 77030, USA
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, the Netherlands
| | - Marieke F van Dooren
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, the Netherlands
| | - Martina Wilke
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, the Netherlands
| | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, the Netherlands
| | - Gaetan Lesca
- Department of Medical Genetics, Lyon University Hospital, Université Claude Bernard Lyon 1, Lyon, France; Institut NeuroMyoGène, CNRS UMR 5310 - INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Isabelle Sabatier
- Department of Pediatric Neurology, Lyon University Hospitals, Lyon, France
| | - Nicolas Chatron
- Department of Medical Genetics, Lyon University Hospital, Université Claude Bernard Lyon 1, Lyon, France; Institut NeuroMyoGène, CNRS UMR 5310 - INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Catherine A Brownstein
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Jill A Madden
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA
| | - Pankaj B Agrawal
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA; Division of Newborn Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Boris Keren
- Genetic Department, Pitié-Salpêtrière Hospital, APHP.Sorbonne Université, Paris 75013, France
| | - Thomas Courtin
- Genetic Department, Pitié-Salpêtrière Hospital, APHP.Sorbonne Université, Paris 75013, France
| | - Laurence Perrin
- Genetic Department, Robert Debré Hospital, APHP.Nord-Université de Paris, Paris 75019, France
| | - Melanie Brugger
- Institute of Human Genetics, Technical University Munich, Munich, Germany
| | - Timo Roser
- Division of Pediatric Neurology, Developmental Medicine and Social Pediatrics, Department of Pediatrics, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Lindwurmstraße 4, 80337 Munich, Germany
| | - Steffen Leiz
- Department of Pediatrics and Adolescent Medicine, Hospital Dritter Orden, Munich, Germany
| | - Frederic Tran Mau-Them
- INSERM U1231, LNC UMR1231 GAD, Burgundy University, 21000 Dijon, France; Laboratoire de Génétique, Innovation en Diagnostic Génomique des Maladies Rares UF6254, Plateau Technique de Biologie, CHU Dijon, 14 Rue Paul Gaffarel, BP 77908, 21079 Dijon, France
| | - Julian Delanne
- INSERM U1231, LNC UMR1231 GAD, Burgundy University, 21000 Dijon, France
| | - Elena Sukarova-Angelovska
- Department of Endocrinology and Genetics, University Clinic for Children's Diseases, Medical Faculty, University Sv. Kiril i Metodij, Skopje, Republic of Macedonia
| | - Slavica Trajkova
- Department of Medical Sciences, University of Torino, Turin, Italy
| | - Erik Rosenhahn
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Vincent Strehlow
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Konrad Platzer
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Roberto Keller
- Adult Autism Center, Mental Health Department, Health Unit ASL Città di Torino, Turin, Italy
| | - Lisa Pavinato
- Department of Medical Sciences, University of Torino, Turin, Italy; Institute of Human Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Alfredo Brusco
- Department of Medical Sciences, University of Torino, Turin, Italy; Medical Genetics Unit, Città della Salute e della Scienza, University Hospital, Turin, Italy
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Baylor Genetics Laboratories, Houston, TX 77021, USA
| | - Ronit Marom
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; TCH, Houston, TX 77030, USA
| | - Michael F Wangler
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA; TCH, Houston, TX 77030, USA; Development, Disease Models & Therapeutics Graduate Program, BCM, Houston, TX 77030, USA.
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA; Program in Developmental Biology, BCM, Houston, TX 77030, USA; Department of Neuroscience, BCM, Houston, TX 77030, USA; Development, Disease Models & Therapeutics Graduate Program, BCM, Houston, TX 77030, USA.
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43
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Gumerov VM, Andrianova EP, Matilla MA, Page KM, Monteagudo-Cascales E, Dolphin AC, Krell T, Zhulin IB. Amino acid sensor conserved from bacteria to humans. Proc Natl Acad Sci U S A 2022; 119:e2110415119. [PMID: 35238638 PMCID: PMC8915833 DOI: 10.1073/pnas.2110415119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 01/10/2022] [Indexed: 11/18/2022] Open
Abstract
SignificanceAmino acids are the building blocks of life and important signaling molecules. Despite their common structure, no universal mechanism for amino acid recognition by cellular receptors is currently known. We discovered a simple motif, which binds amino acids in various receptor proteins from all major life-forms. In humans, this motif is found in subunits of calcium channels that are implicated in pain and neurodevelopmental disorders. Our findings suggest that γ-aminobutyric acid-derived drugs bind to the same motif in human proteins that binds natural ligands in bacterial receptors, thus enabling future improvement of important drugs.
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Affiliation(s)
- Vadim M. Gumerov
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH 43210
| | - Ekaterina P. Andrianova
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH 43210
| | - Miguel A. Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, E-18008 Granada, Spain
| | - Karen M. Page
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Elizabet Monteagudo-Cascales
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, E-18008 Granada, Spain
| | - Annette C. Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, E-18008 Granada, Spain
| | - Igor B. Zhulin
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH 43210
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44
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Aslan HG, Kuşçulu NG. Investigation of chemical activity, SCHIFF base reactions and staining effects of some amino acids by spectrophotometric and theorical methods. J INDIAN CHEM SOC 2022. [DOI: 10.1016/j.jics.2021.100315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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45
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Felsztyna I, Villarreal MA, García DA, Miguel V. Insect RDL Receptor Models for Virtual Screening: Impact of the Template Conformational State in Pentameric Ligand-Gated Ion Channels. ACS OMEGA 2022; 7:1988-2001. [PMID: 35071887 PMCID: PMC8771969 DOI: 10.1021/acsomega.1c05465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
The RDL receptor is one of the most relevant protein targets for insecticide molecules. It belongs to the pentameric ligand-gated ion channel (pLGIC) family. Given that the experimental structures of pLGICs are difficult to obtain, homology modeling has been extensively used for these proteins, particularly for the RDL receptor. However, no detailed assessments of the usefulness of homology models for virtual screening (VS) have been carried out for pLGICs. The aim of this study was to evaluate which are the determinant factors for a good VS performance using RDL homology models, specially analyzing the impact of the template conformational state. Fifteen RDL homology models were obtained based on different pLGIC templates representing the closed, open, and desensitized states. A retrospective VS process was performed on each model, and their performance in the prioritization of active ligands was assessed. In addition, the three best-performing models among each of the conformations were subjected to molecular dynamics simulations (MDS) in complex with a representative active ligand. The models showed variations in their VS performance parameters that were related to the structural properties of the binding site. VS performance tended to improve in more constricted binding cavities. The best performance was obtained with a model based on a template in the closed conformation. MDS confirmed that the closed model was the one that best represented the interactions with an active ligand. These results imply that different templates should be evaluated and the structural variations between their channel conformational states should be specially examined, providing guidelines for the application of homology modeling for VS in other proteins of the pLGIC family.
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Affiliation(s)
- Iván Felsztyna
- Facultad
de Ciencias Exactas, Físicas y Naturales, Departamento de Química.
Cátedra de Química Biológica, Universidad Nacional de Córdoba, Córdoba 5016, Argentina
- Instituto
de Investigaciones Biológicas y Tecnológicas (IIByT), CONICET-Universidad Nacional de Córdoba, Córdoba 5016, Argentina
| | - Marcos A. Villarreal
- Facultad
de Ciencias Químicas, Departamento de Química Teórica
y Computacional, Universidad Nacional de
Córdoba, Córdoba 5016, Argentina
- Instituto
de Investigaciones en Físico-Química de Córdoba
(INFIQC), CONICET-Universidad Nacional de
Córdoba, Córdoba 5016, Argentina
| | - Daniel A. García
- Facultad
de Ciencias Exactas, Físicas y Naturales, Departamento de Química.
Cátedra de Química Biológica, Universidad Nacional de Córdoba, Córdoba 5016, Argentina
- Instituto
de Investigaciones Biológicas y Tecnológicas (IIByT), CONICET-Universidad Nacional de Córdoba, Córdoba 5016, Argentina
| | - Virginia Miguel
- Facultad
de Ciencias Exactas, Físicas y Naturales, Departamento de Química.
Cátedra de Química Biológica, Universidad Nacional de Córdoba, Córdoba 5016, Argentina
- Instituto
de Investigaciones Biológicas y Tecnológicas (IIByT), CONICET-Universidad Nacional de Córdoba, Córdoba 5016, Argentina
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46
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Montgomery M, Rendine S, Zimmer CT, Elias J, Schaetzer J, Pitterna T, Benfatti F, Skaljac M, Bigot A. Structural Biology-Guided Design, Synthesis, and Biological Evaluation of Novel Insect Nicotinic Acetylcholine Receptor Orthosteric Modulators. J Med Chem 2022; 65:2297-2312. [PMID: 34986308 DOI: 10.1021/acs.jmedchem.1c01767] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The development of novel and safe insecticides remains an important need for a growing world population to protect crops and animal and human health. New chemotypes modulating the insect nicotinic acetylcholine receptors have been recently brought to the agricultural market, yet with limited understanding of their molecular interactions at their target receptor. Herein, we disclose the first crystal structures of these insecticides, namely, sulfoxaflor, flupyradifurone, triflumezopyrim, flupyrimin, and the experimental compound, dicloromezotiaz, in a double-mutated acetylcholine-binding protein which mimics the insect-ion-channel orthosteric site. Enabled by these findings, we discovered novel pharmacophores with a related mode of action, and we describe herein their design, synthesis, and biological evaluation.
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Affiliation(s)
- Mark Montgomery
- Syngenta Crop Protection, Jealott's Hill International Research Centre, RG42 6EY Bracknell, Berkshire, U.K
| | - Stefano Rendine
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - Christoph T Zimmer
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - Jan Elias
- Syngenta Crop Protection AG, Rosentalstrasse 67, 4002 Basel, Switzerland
| | - Jürgen Schaetzer
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - Thomas Pitterna
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - Fides Benfatti
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - Marisa Skaljac
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - Aurélien Bigot
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
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47
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Kuhlemann A, Beliu G, Janzen D, Petrini EM, Taban D, Helmerich DA, Doose S, Bruno M, Barberis A, Villmann C, Sauer M, Werner C. Genetic Code Expansion and Click-Chemistry Labeling to Visualize GABA-A Receptors by Super-Resolution Microscopy. Front Synaptic Neurosci 2021; 13:727406. [PMID: 34899260 PMCID: PMC8664562 DOI: 10.3389/fnsyn.2021.727406] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 11/02/2021] [Indexed: 01/15/2023] Open
Abstract
Fluorescence labeling of difficult to access protein sites, e.g., in confined compartments, requires small fluorescent labels that can be covalently tethered at well-defined positions with high efficiency. Here, we report site-specific labeling of the extracellular domain of γ-aminobutyric acid type A (GABA-A) receptor subunits by genetic code expansion (GCE) with unnatural amino acids (ncAA) combined with bioorthogonal click-chemistry labeling with tetrazine dyes in HEK-293-T cells and primary cultured neurons. After optimization of GABA-A receptor expression and labeling efficiency, most effective variants were selected for super-resolution microscopy and functionality testing by whole-cell patch clamp. Our results show that GCE with ncAA and bioorthogonal click labeling with small tetrazine dyes represents a versatile method for highly efficient site-specific fluorescence labeling of proteins in a crowded environment, e.g., extracellular protein domains in confined compartments such as the synaptic cleft.
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Affiliation(s)
- Alexander Kuhlemann
- Department of Biotechnology and Biophysics, University of Würzburg, Biocenter, Würzburg, Germany
| | - Gerti Beliu
- Department of Biotechnology and Biophysics, University of Würzburg, Biocenter, Würzburg, Germany.,Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Wuerzburg, Würzburg, Germany
| | - Dieter Janzen
- Institute of Clinical Neurobiology, University of Würzburg, Würzburg, Germany
| | - Enrica Maria Petrini
- Neuroscience and Brain Technologies Department, Istituto Italiano Di Tecnologia, Genova, Italy
| | - Danush Taban
- Department of Biotechnology and Biophysics, University of Würzburg, Biocenter, Würzburg, Germany
| | - Dominic A Helmerich
- Department of Biotechnology and Biophysics, University of Würzburg, Biocenter, Würzburg, Germany
| | - Sören Doose
- Department of Biotechnology and Biophysics, University of Würzburg, Biocenter, Würzburg, Germany
| | - Martina Bruno
- Neuroscience and Brain Technologies Department, Istituto Italiano Di Tecnologia, Genova, Italy
| | - Andrea Barberis
- Neuroscience and Brain Technologies Department, Istituto Italiano Di Tecnologia, Genova, Italy
| | - Carmen Villmann
- Institute of Clinical Neurobiology, University of Würzburg, Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, University of Würzburg, Biocenter, Würzburg, Germany
| | - Christian Werner
- Department of Biotechnology and Biophysics, University of Würzburg, Biocenter, Würzburg, Germany
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48
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Lipovsek M, Marcovich I, Elgoyhen AB. The Hair Cell α9α10 Nicotinic Acetylcholine Receptor: Odd Cousin in an Old Family. Front Cell Neurosci 2021; 15:785265. [PMID: 34867208 PMCID: PMC8634148 DOI: 10.3389/fncel.2021.785265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are a subfamily of pentameric ligand-gated ion channels with members identified in most eumetazoan clades. In vertebrates, they are divided into three subgroups, according to their main tissue of expression: neuronal, muscle and hair cell nAChRs. Each receptor subtype is composed of different subunits, encoded by paralogous genes. The latest to be identified are the α9 and α10 subunits, expressed in the mechanosensory hair cells of the inner ear and the lateral line, where they mediate efferent modulation. α9α10 nAChRs are the most divergent amongst all nicotinic receptors, showing marked differences in their degree of sequence conservation, their expression pattern, their subunit co-assembly rules and, most importantly, their functional properties. Here, we review recent advances in the understanding of the structure and evolution of nAChRs. We discuss the functional consequences of sequence divergence and conservation, with special emphasis on the hair cell α9α10 receptor, a seemingly distant cousin of neuronal and muscle nicotinic receptors. Finally, we highlight potential links between the evolution of the octavolateral system and the extreme divergence of vertebrate α9α10 receptors.
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Affiliation(s)
- Marcela Lipovsek
- Ear Institute, Faculty of Brain Sciences, University College London, London, United Kingdom
| | - Irina Marcovich
- Departments of Otolaryngology & Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
| | - Ana Belén Elgoyhen
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
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49
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Nin-Hill A, Mueller NPF, Molteni C, Rovira C, Alfonso-Prieto M. Photopharmacology of Ion Channels through the Light of the Computational Microscope. Int J Mol Sci 2021; 22:12072. [PMID: 34769504 PMCID: PMC8584574 DOI: 10.3390/ijms222112072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 10/31/2021] [Accepted: 11/02/2021] [Indexed: 12/13/2022] Open
Abstract
The optical control and investigation of neuronal activity can be achieved and carried out with photoswitchable ligands. Such compounds are designed in a modular fashion, combining a known ligand of the target protein and a photochromic group, as well as an additional electrophilic group for tethered ligands. Such a design strategy can be optimized by including structural data. In addition to experimental structures, computational methods (such as homology modeling, molecular docking, molecular dynamics and enhanced sampling techniques) can provide structural insights to guide photoswitch design and to understand the observed light-regulated effects. This review discusses the application of such structure-based computational methods to photoswitchable ligands targeting voltage- and ligand-gated ion channels. Structural mapping may help identify residues near the ligand binding pocket amenable for mutagenesis and covalent attachment. Modeling of the target protein in a complex with the photoswitchable ligand can shed light on the different activities of the two photoswitch isomers and the effect of site-directed mutations on photoswitch binding, as well as ion channel subtype selectivity. The examples presented here show how the integration of computational modeling with experimental data can greatly facilitate photoswitchable ligand design and optimization. Recent advances in structural biology, both experimental and computational, are expected to further strengthen this rational photopharmacology approach.
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Affiliation(s)
- Alba Nin-Hill
- Departament de Química Inorgànica i Orgànica (Secció de Química Orgànica) and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08028 Barcelona, Spain; (A.N.-H.); (C.R.)
| | - Nicolas Pierre Friedrich Mueller
- Institute for Advanced Simulations IAS-5 and Institute of Neuroscience and Medicine INM-9, Computational Biomedicine, Forschungszentrum Jülich, 52425 Jülich, Germany;
- Faculty of Mathematics and Natural Sciences, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Carla Molteni
- Physics Department, King’s College London, London WC2R 2LS, UK;
| | - Carme Rovira
- Departament de Química Inorgànica i Orgànica (Secció de Química Orgànica) and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08028 Barcelona, Spain; (A.N.-H.); (C.R.)
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08020 Barcelona, Spain
| | - Mercedes Alfonso-Prieto
- Institute for Advanced Simulations IAS-5 and Institute of Neuroscience and Medicine INM-9, Computational Biomedicine, Forschungszentrum Jülich, 52425 Jülich, Germany;
- Cécile and Oskar Vogt Institute for Brain Research, University Hospital Düsseldorf, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
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50
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Zhu H, Gouaux E. Architecture and assembly mechanism of native glycine receptors. Nature 2021; 599:513-517. [PMID: 34555840 PMCID: PMC8647860 DOI: 10.1038/s41586-021-04022-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 09/15/2021] [Indexed: 02/08/2023]
Abstract
Glycine receptors (GlyRs) are pentameric, 'Cys-loop' receptors that form chloride-permeable channels and mediate fast inhibitory signalling throughout the central nervous system1,2. In the spinal cord and brainstem, GlyRs regulate locomotion and cause movement disorders when mutated2,3. However, the stoichiometry of native GlyRs and the mechanism by which they are assembled remain unclear, despite extensive investigation4-8. Here we report cryo-electron microscopy structures of native GlyRs from pig spinal cord and brainstem, revealing structural insights into heteromeric receptors and their predominant subunit stoichiometry of 4α:1β. Within the heteromeric pentamer, the β(+)-α(-) interface adopts a structure that is distinct from the α(+)-α(-) and α(+)-β(-) interfaces. Furthermore, the β-subunit contains a unique phenylalanine residue that resides within the pore and disrupts the canonical picrotoxin site. These results explain why inclusion of the β-subunit breaks receptor symmetry and alters ion channel pharmacology. We also find incomplete receptor complexes and, by elucidating their structures, reveal the architectures of partially assembled α-trimers and α-tetramers.
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Affiliation(s)
- Hongtao Zhu
- Vollum Institute, Oregon Health and Science University, Portland, 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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