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Chomphoo S, Kondo H, Hipkaeo W. Electron-translucency and partial defects of synaptic basal lamina in the electrocyte synapse of an electric ray (Narke japonica) in 3D embedment-free section electron microscopy. Microsc Res Tech 2024; 87:1647-1653. [PMID: 38461470 DOI: 10.1002/jemt.24534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/31/2024] [Accepted: 02/14/2024] [Indexed: 03/12/2024]
Abstract
The synaptic basal lamina of the electrocytes was disclosed to be electron-translucent to some extent when viewed in an en-face direction in embedment-free section transmission electron microscopy (EFS-TEM), and synaptic vesicles located close to the presynaptic membrane were seen through the synaptic basal lamina together with the presynaptic and postsynaptic membranes. This feature of translucency has the potential to analyze possible spatial interrelations in situ between bioactive molecules in the synaptic basal lamina and the synaptic vesicles in further studies. The synaptic basal lamina, appearing as an electron-dense line sandwiched by two parallel lines representing the presynaptic and postsynaptic membranes in ultrathin sections cut right to the synaptic junctional plane in conventional TEM, was not fully continuous but randomly intermittent along its trajectory. Compatible with the intermittent line appearance, the en-face 3D view in embedment-free section TEM revealed for the first time partial irregular defects of the synaptic basal lamina. Considering the known functional significance of several molecules contained in the synaptic basal lamina in the maintenance and exertion of the synapse, its partial defects may not represent its rigid structural features, but its immature structure under remodeling or its dynamic changes in consistency such as the sol/gel transition, whose validity needs further examination. RESEARCH HIGHLIGHTS: In embedment-free section TEM, a 3D en-face view of synaptic basal lamina in situ is reliably possible. The basal lamina en-face is electron-translucent, which makes it possible to analyze spatial interrelation between pre- and post-synaptic components. Partial irregular defects in the basal lamina are revealed in Torpedo electrocytes, suggesting its remodeling or dynamic changes in consistency.
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Affiliation(s)
- Surang Chomphoo
- Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Hisatake Kondo
- Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- Department of Anatomy, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Wiphawi Hipkaeo
- Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
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2
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Kaiser J, Gertzen CGW, Bernauer T, Nitsche V, Höfner G, Niessen KV, Seeger T, Paintner FF, Wanner KT, Steinritz D, Worek F, Gohlke H. Identification of ligands binding to MB327-PAM-1, a binding pocket relevant for resensitization of nAChRs. Toxicol Lett 2024; 398:91-104. [PMID: 38768836 DOI: 10.1016/j.toxlet.2024.05.013] [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: 12/21/2023] [Revised: 04/13/2024] [Accepted: 05/17/2024] [Indexed: 05/22/2024]
Abstract
Desensitization of nicotinic acetylcholine receptors (nAChRs) can be induced by overstimulation with acetylcholine (ACh) caused by an insufficient degradation of ACh after poisoning with organophosphorus compounds (OPCs). Currently, there is no generally applicable treatment for OPC poisoning that directly targets the desensitized nAChR. The bispyridinium compound MB327, an allosteric modulator of nAChR, has been shown to act as a resensitizer of nAChRs, indicating that drugs binding directly to nAChRs can have beneficial effects after OPC poisoning. However, MB327 also acts as an inhibitor of nAChRs at higher concentrations and can thus not be used for OPC poisoning treatment. Consequently, novel, more potent resensitizers are required. To successfully design novel ligands, the knowledge of the binding site is of utmost importance. Recently, we performed in silico studies to identify a new potential binding site of MB327, MB327-PAM-1, for which a more affine ligand, UNC0646, has been described. In this work, we performed ligand-based screening approaches to identify novel analogs of UNC0646 to help further understand the structure-affinity relationship of this compound class. Furthermore, we used structure-based screenings and identified compounds representing four new chemotypes binding to MB327-PAM-1. One of these compounds, cycloguanil, is the active metabolite of the antimalaria drug proguanil and shows a higher affinity towards MB327-PAM-1 than MB327. Furthermore, cycloguanil can reestablish the muscle force in soman-inhibited rat muscles. These results can act as a starting point to develop more potent resensitizers of nAChR and to close the gap in the treatment after OPC poisoning.
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Affiliation(s)
- Jesko Kaiser
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Christoph G W Gertzen
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tamara Bernauer
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Valentin Nitsche
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Georg Höfner
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Karin V Niessen
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Franz F Paintner
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Klaus T Wanner
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Dirk Steinritz
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Bio- and Geosciences (IBG-4: Bioinformatics), Forschungszentrum Jülich, Jülich, Germany.
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3
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Gambardella MD, Wang Y, Pang J. The Cholinergic Selectivity of FDA-Approved and Metabolite Compounds Examined with Molecular-Docking-Based Virtual Screening. Molecules 2024; 29:2333. [PMID: 38792196 PMCID: PMC11124253 DOI: 10.3390/molecules29102333] [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: 04/20/2024] [Revised: 05/07/2024] [Accepted: 05/13/2024] [Indexed: 05/26/2024] Open
Abstract
The search for selective anticholinergic agents stems from varying cholinesterase levels as Alzheimer's Disease progresses from the mid to late stage. In this computational study, we probed the selectivity of FDA-approved and metabolite compounds against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with molecular-docking-based virtual screening. The results were evaluated using locally developed codes for the statistical methods. The docking-predicted selectivity for AChE and BChE was predominantly the consequence of differences in the volume of the active site and the narrower entrance to the bottom of the active site gorge of AChE.
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Affiliation(s)
- Michael D. Gambardella
- Department of Chemistry and Biochemistry, Southern Connecticut State University, New Haven, CT 06515, USA
| | - Yigui Wang
- Department of Chemistry and Biochemistry, Southern Connecticut State University, New Haven, CT 06515, USA
- Department of Chemistry and Chemical & Biochemical Engineering, University of New Haven, West Haven, CT 06516, USA
| | - Jiongdong Pang
- Department of Chemistry and Biochemistry, Southern Connecticut State University, New Haven, CT 06515, USA
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4
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Zhang Y, Ge G, Xu X, Wu J. Ensemble-Based Virtual Screening Led to the Discovery of Novel Lead Molecules as Potential NMBAs. Molecules 2024; 29:1955. [PMID: 38731447 PMCID: PMC11085220 DOI: 10.3390/molecules29091955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/16/2024] [Accepted: 04/22/2024] [Indexed: 05/13/2024] Open
Abstract
Neuromuscular blocking agents (NMBAs) are routinely used during anesthesia to relax skeletal muscle. Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels; NMBAs can induce muscle paralysis by preventing the neurotransmitter acetylcholine (ACh) from binding to nAChRs situated on the postsynaptic membranes. Despite widespread efforts, it is still a great challenge to find new NMBAs since the introduction of cisatracurium in 1995. In this work, an effective ensemble-based virtual screening method, including molecular property filters, 3D pharmacophore model, and molecular docking, was applied to discover potential NMBAs from the ZINC15 database. The results showed that screened hit compounds had better docking scores than the reference compound d-tubocurarine. In order to further investigate the binding modes between the hit compounds and nAChRs at simulated physiological conditions, the molecular dynamics simulation was performed. Deep analysis of the simulation results revealed that ZINC257459695 can stably bind to nAChRs' active sites and interact with the key residue Asp165. The binding free energies were also calculated for the obtained hits using the MM/GBSA method. In silico ADMET calculations were performed to assess the pharmacokinetic properties of hit compounds in the human body. Overall, the identified ZINC257459695 may be a promising lead compound for developing new NMBAs as an adjunct to general anesthesia, necessitating further investigations.
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Affiliation(s)
- Yi Zhang
- School of Medicine, Nanjing University, Nanjing 210093, China
- Jiangsu Key Laboratory of Central Nervous System Drug Research and Development, Jiangsu Nhwa Pharmaceutical Co., Ltd., Xuzhou 221116, China
| | - Gonghui Ge
- School of Pharmacy, China Medical University, Shenyang 110122, China
| | - Xiangyang Xu
- Jiangsu Key Laboratory of Central Nervous System Drug Research and Development, Jiangsu Nhwa Pharmaceutical Co., Ltd., Xuzhou 221116, China
| | - Jinhui Wu
- School of Medicine, Nanjing University, Nanjing 210093, China
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5
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Muller KS, Tibúrcio FC, Ferreira RS, Barraviera B, Matheus SMM. Heterologous fibrin biopolymer as an emerging approach to peripheral nerve repair: a scoping review. J Venom Anim Toxins Incl Trop Dis 2024; 30:e20230060. [PMID: 38628622 PMCID: PMC11019597 DOI: 10.1590/1678-9199-jvatitd-2023-0060] [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: 09/04/2023] [Accepted: 01/29/2024] [Indexed: 04/19/2024] Open
Abstract
Nerve injuries present a substantial challenge within the medical domain due to their prevalent occurrence and significant impact. In nerve injuries, a range of physiopathological and metabolic responses come into play to stabilize and repair the resulting damage. A critical concern arises from the disruption of connections at neuromuscular junctions, leading to profound degeneration and substantial loss of muscle function, thereby hampering motor tasks. While end-to-end neurorrhaphy serves as the established technique for treating peripheral nerve injuries, achieving comprehensive morphofunctional recovery remains a formidable challenge. In pursuit of enhancing the repair process, alternative and supportive methods are being explored. A promising candidate is the utilization of heterologous fibrin biopolymer, a sealant devoid of human blood components. Notably, this biopolymer has showcased its prowess in establishing a stable and protective microenvironment at the site of use in multiple scenarios of regenerative medicine. Hence, this scoping review is directed towards assessing the effects of associating heterologous fibrin biopolymer with neurorrhaphy to treat nerve injuries, drawing upon findings from prior studies disseminated through PubMed/MEDLINE, Scopus, and Web of Science databases. Further discourse delves into the intricacies of the biology of neuromuscular junctions, nerve injury pathophysiology, and the broader utilization of fibrin sealants in conjunction with sutures for nerve reconstruction procedures. The association of the heterologous fibrin biopolymer with neurorrhaphy emerges as a potential avenue for surmounting the limitations associated with traditional sealants while also mitigating degeneration in nerves, muscles, and NMJs post-injury, thereby fostering a more conducive environment for subsequent regeneration. Indeed, queries arise regarding the long-term regenerative potential of this approach and its applicability in reconstructive surgeries for human nerve injuries.
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Affiliation(s)
- Kevin Silva Muller
- Department of Structural and Functional Biology, São Paulo State
University (UNESP), Botucatu Institute of Biosciences, Botucatu, SP, Brazil
- Botucatu Medical School, São Paulo State University (UNESP),
Botucatu, SP, Brazil
| | - Felipe Cantore Tibúrcio
- Department of Structural and Functional Biology, São Paulo State
University (UNESP), Botucatu Institute of Biosciences, Botucatu, SP, Brazil
- Botucatu Medical School, São Paulo State University (UNESP),
Botucatu, SP, Brazil
| | - Rui Seabra Ferreira
- Botucatu Medical School, São Paulo State University (UNESP),
Botucatu, SP, Brazil
- Center for the Study of Venoms and Venomous Animals (CEVAP), São
Paulo State University (UNESP), Botucatu, SP, Brazil
- Center for Translational Sciences and Biopharmaceuticals Development
(CTS), Center for the Study of Venoms and Venomous Animals (CEVAP), Botucatu, SP,
Brazil
| | - Benedito Barraviera
- Botucatu Medical School, São Paulo State University (UNESP),
Botucatu, SP, Brazil
- Center for the Study of Venoms and Venomous Animals (CEVAP), São
Paulo State University (UNESP), Botucatu, SP, Brazil
- Center for Translational Sciences and Biopharmaceuticals Development
(CTS), Center for the Study of Venoms and Venomous Animals (CEVAP), Botucatu, SP,
Brazil
| | - Selma Maria Michelin Matheus
- Department of Structural and Functional Biology, São Paulo State
University (UNESP), Botucatu Institute of Biosciences, Botucatu, SP, Brazil
- Botucatu Medical School, São Paulo State University (UNESP),
Botucatu, SP, Brazil
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6
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Bourne Y, Sulzenbacher G, Chabaud L, Aráoz R, Radić Z, Conrod S, Taylor P, Guillou C, Molgó J, Marchot P. The Cyclic Imine Core Common to the Marine Macrocyclic Toxins Is Sufficient to Dictate Nicotinic Acetylcholine Receptor Antagonism. Mar Drugs 2024; 22:149. [PMID: 38667766 PMCID: PMC11050823 DOI: 10.3390/md22040149] [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: 02/13/2024] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024] Open
Abstract
Macrocyclic imine phycotoxins are an emerging class of chemical compounds associated with harmful algal blooms and shellfish toxicity. Earlier binding and electrophysiology experiments on nAChR subtypes and their soluble AChBP surrogates evidenced common trends for substantial antagonism, binding affinities, and receptor-subtype selectivity. Earlier, complementary crystal structures of AChBP complexes showed that common determinants within the binding nest at each subunit interface confer high-affinity toxin binding, while distinctive determinants from the flexible loop C, and either capping the nest or extending toward peripheral subsites, dictate broad versus narrow receptor subtype selectivity. From these data, small spiroimine enantiomers mimicking the functional core motif of phycotoxins were chemically synthesized and characterized. Voltage-clamp analyses involving three nAChR subtypes revealed preserved antagonism for both enantiomers, despite lower subtype specificity and binding affinities associated with faster reversibility compared with their macrocyclic relatives. Binding and structural analyses involving two AChBPs pointed to modest affinities and positional variability of the spiroimines, along with a range of AChBP loop-C conformations denoting a prevalence of antagonistic properties. These data highlight the major contribution of the spiroimine core to binding within the nAChR nest and confirm the need for an extended interaction network as established by the macrocyclic toxins to define high affinities and marked subtype specificity. This study identifies a minimal set of functional pharmacophores and binding determinants as templates for designing new antagonists targeting disease-associated nAChR subtypes.
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Affiliation(s)
- Yves Bourne
- Lab “Architecture et Fonction des Macromolécules Biologiques” (AFMB), Aix-Marseille Univ, CNRS, Faculté des Sciences Campus Luminy, 13288 Marseille cedex 09, France; (Y.B.); (G.S.)
| | - Gerlind Sulzenbacher
- Lab “Architecture et Fonction des Macromolécules Biologiques” (AFMB), Aix-Marseille Univ, CNRS, Faculté des Sciences Campus Luminy, 13288 Marseille cedex 09, France; (Y.B.); (G.S.)
| | - Laurent Chabaud
- Institut de Chimie des Substances Naturelles (ICSN), Univ Paris-Saclay, CNRS, 91198 Gif-sur-Yvette, France; (L.C.); (C.G.)
| | - Rómulo Aráoz
- Service d’Ingénierie Moléculaire pour la Santé (SIMoS) EMR CNRS 9004, Département Médicaments et Technologies pour la Santé, Institut des Sciences du Vivant Frédéric Joliot, CEA, INRAE, Université Paris-Saclay, 91191 Gif-sur-Yvette, France; (R.A.); (J.M.)
| | - Zoran Radić
- Skaggs School of Pharmacy and Pharmaceutical Sciences (SSPPS), University of California San Diego, La Jolla, CA 92093-0751, USA; (Z.R.); (P.T.)
| | - Sandrine Conrod
- Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille (CRN2M), Aix Marseille Univ, CNRS, 13344 Marseille, France;
| | - Palmer Taylor
- Skaggs School of Pharmacy and Pharmaceutical Sciences (SSPPS), University of California San Diego, La Jolla, CA 92093-0751, USA; (Z.R.); (P.T.)
| | - Catherine Guillou
- Institut de Chimie des Substances Naturelles (ICSN), Univ Paris-Saclay, CNRS, 91198 Gif-sur-Yvette, France; (L.C.); (C.G.)
| | - Jordi Molgó
- Service d’Ingénierie Moléculaire pour la Santé (SIMoS) EMR CNRS 9004, Département Médicaments et Technologies pour la Santé, Institut des Sciences du Vivant Frédéric Joliot, CEA, INRAE, Université Paris-Saclay, 91191 Gif-sur-Yvette, France; (R.A.); (J.M.)
| | - Pascale Marchot
- Lab “Architecture et Fonction des Macromolécules Biologiques” (AFMB), Aix-Marseille Univ, CNRS, Faculté des Sciences Campus Luminy, 13288 Marseille cedex 09, France; (Y.B.); (G.S.)
- Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille (CRN2M), Aix Marseille Univ, CNRS, 13344 Marseille, France;
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7
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Kumari M, Khatoon N, Sharma R, Adusumilli S, Auerbach A, Kashyap HK, Nayak TK. Mechanism of hydrophobic gating in the acetylcholine receptor channel pore. J Gen Physiol 2024; 156:e202213189. [PMID: 38153395 PMCID: PMC10757554 DOI: 10.1085/jgp.202213189] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/16/2023] [Accepted: 12/06/2023] [Indexed: 12/29/2023] Open
Abstract
Neuromuscular acetylcholine receptors (AChRs) are hetero-pentameric, ligand-gated ion channels. The binding of the neurotransmitter acetylcholine (ACh) to two target sites promotes a global conformational change of the receptor that opens the channel and allows ion conduction through the channel pore. Here, by measuring free-energy changes from single-channel current recordings and using molecular dynamics simulations, we elucidate how a constricted hydrophobic region acts as a "gate" to regulate the channel opening in the pore of AChRs. Mutations of gate residues, including those implicated in congenital myasthenia syndrome, lower the permeation barrier of the channel substantially and increase the unliganded gating equilibrium constant (constitutive channel openings). Correlations between hydrophobicity and the observed free-energy changes, supported by calculations of water densities in the wild-type versus mutant channel pores, provide evidence for hydrophobic wetting-dewetting transition at the gate. The analysis of a coupled interaction network provides insight into the molecular mechanism of closed- versus open-state conformational changes at the gate. Studies of the transition state by "phi"(φ)-value analysis indicate that agonist binding serves to stabilize both the transition and the open state. Intersubunit interaction energy measurements and molecular dynamics simulations suggest that channel opening involves tilting of the pore-lining M2 helices, asymmetric outward rotation of amino acid side chains, and wetting transition of the gate region that lowers the barrier to ion permeation and stabilizes the channel open conformation. Our work provides new insight into the hydrophobic gate opening and shows why the gate mutations result in constitutive AChR channel activity.
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Affiliation(s)
- Monika Kumari
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Nadira Khatoon
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Rachita Sharma
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Sushanth Adusumilli
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Anthony Auerbach
- Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Hemant K. Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Tapan K. Nayak
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
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8
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Crestini A, Carbone E, Rivabene R, Ancidoni A, Rosa P, Tata AM, Fabrizi E, Locuratolo N, Vanacore N, Lacorte E, Piscopo P. A Systematic Review on Drugs Acting as Nicotinic Acetylcholine Receptor Agonists in the Treatment of Dementia. Cells 2024; 13:237. [PMID: 38334629 PMCID: PMC10854606 DOI: 10.3390/cells13030237] [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: 12/11/2023] [Revised: 01/10/2024] [Accepted: 01/17/2024] [Indexed: 02/10/2024] Open
Abstract
Acetylcholine signaling is attenuated in early Alzheimer's disease (AD) and other dementias. A significant reduction in the expression of nicotinic acetylcholine receptors (nAChRs) in the brain of AD patients has also been reported in several molecular biological and in situ labeling studies. The modulation of the functional deficit of the cholinergic system as a pharmacological target could therefore have a clinical benefit, which is not to be neglected. This systematic review was conducted to identify clinical trials, which evaluated the safety and efficacy of nicotinic acetylcholine receptor agonists using Clinicaltrial (CT) and EudraCT databases. Structured searches identified 39 trials, which used 15 different drugs designed to increase the function of the nAChRs. Most of the identified clinical trials were phase II trials, with some of them classified as ongoing for several years. The systematic screening of the literature led to the selection of 14 studies out of the 8261 bibliographic records retrieved. Six trials reported detailed data on adverse events associated with the intervention, while twelve trials reported data on efficacy measures, such as attention, behavior and cognition. Overall, smost of the physical side effects of cholinergic agonists were reported to be well tolerated. Some trials also reported improvements in attention. However, the efficacy of these drugs in other cognitive and behavioral outcomes remains highly controversial.
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Affiliation(s)
- Alessio Crestini
- Department of Neuroscience, Italian National Institute of Health, 00161 Rome, Italy; (E.C.); (R.R.); (P.P.)
| | - Elena Carbone
- Department of Neuroscience, Italian National Institute of Health, 00161 Rome, Italy; (E.C.); (R.R.); (P.P.)
| | - Roberto Rivabene
- Department of Neuroscience, Italian National Institute of Health, 00161 Rome, Italy; (E.C.); (R.R.); (P.P.)
| | - Antonio Ancidoni
- National Center for Disease Prevention and Health Promotion, Italian National Institute of Health, 00161 Rome, Italy; (A.A.); (N.L.); (N.V.); (E.L.)
| | - Paolo Rosa
- Department of Medical-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Polo Pontino, 04100 Latina, Italy;
- ICOT (Institute of Traumatology and Orthopaedic Surgery), 04100 Latina, Italy
| | - Ada Maria Tata
- Department of Biology and Biotechnologies Charles Darwin, Sapienza University of Rome, 00185 Rome, Italy;
- Research Center in Neurobiology Daniel Bovet, Sapienza University of Rome, 00185 Rome, Italy
| | - Elisa Fabrizi
- National Center for Disease Prevention and Health Promotion, Italian National Institute of Health, 00161 Rome, Italy; (A.A.); (N.L.); (N.V.); (E.L.)
- Doctoral School, The Catholic University of Valencia San Vicente Mártir, 46001 Valencia, Spain
| | - Nicoletta Locuratolo
- National Center for Disease Prevention and Health Promotion, Italian National Institute of Health, 00161 Rome, Italy; (A.A.); (N.L.); (N.V.); (E.L.)
| | - Nicola Vanacore
- National Center for Disease Prevention and Health Promotion, Italian National Institute of Health, 00161 Rome, Italy; (A.A.); (N.L.); (N.V.); (E.L.)
| | - Eleonora Lacorte
- National Center for Disease Prevention and Health Promotion, Italian National Institute of Health, 00161 Rome, Italy; (A.A.); (N.L.); (N.V.); (E.L.)
| | - Paola Piscopo
- Department of Neuroscience, Italian National Institute of Health, 00161 Rome, Italy; (E.C.); (R.R.); (P.P.)
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9
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Silva A, Mourão J, Vale N. A Review of the Lidocaine in the Perioperative Period. J Pers Med 2023; 13:1699. [PMID: 38138926 PMCID: PMC10744742 DOI: 10.3390/jpm13121699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/06/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
This review analyzes the controversies surrounding lidocaine (LIDO), a widely recognized local anesthetic, by exploring its multifaceted effects on pain control in the perioperative setting. The article critically analyzes debates about lidocaine's efficacy, safety, and optimal administration methods. While acknowledging its well-documented analgesic attributes, the text highlights the ongoing controversies in its application. The goal is to provide clinicians with a comprehensive understanding of the current discourse, enabling informed decisions about incorporating lidocaine into perioperative protocols. On the other hand, emphasizes the common uses of lidocaine and its potential role in personalized medicine. It discusses the medication's versatility, including its application in anesthesia, chronic pain, and cardiovascular diseases. The text recognizes lidocaine's widespread use in medical practice and its ability to be combined with other drugs, showcasing its adaptability for individualized treatments. Additionally, it explores the incorporation of lidocaine into hyaluronic acid injections and its impact on pharmacokinetics, signaling innovative approaches. The discussion centers on how lidocaine, within the realm of personalized medicine, can offer safer and more comfortable experiences for patients through tailored treatments.
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Affiliation(s)
- Abigail Silva
- PerMed Research Group, Center for Health Technology and Services Research (CINTESIS), Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal;
- CINTESIS@RISE, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal;
| | - Joana Mourão
- CINTESIS@RISE, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal;
- Department of Anesthesiology, Centro Hospitalar Universitário de São João, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal
- Surgery and Physiology Department, Faculty of Medicine, University of Porto, Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal
| | - Nuno Vale
- PerMed Research Group, Center for Health Technology and Services Research (CINTESIS), Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal;
- CINTESIS@RISE, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal;
- Department of Community Medicine, Health Information and Decision (MEDCIDS), Faculty of Medicine, University of Porto, Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal
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10
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Lukenge M, Ignell R, Hill SR. Adenosine triphosphate overrides the aversive effect of antifeedants and toxicants: a model alternative phagostimulant for sugar-based vector control tools. Parasit Vectors 2023; 16:416. [PMID: 37964326 PMCID: PMC10647091 DOI: 10.1186/s13071-023-06039-x] [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: 09/14/2023] [Accepted: 10/30/2023] [Indexed: 11/16/2023] Open
Abstract
BACKGROUND Sugar, when used as the phagostimulant in attractive toxic bait control tools, limits the efficacy and selectivity of this technology. Thus, more potent and selective phagostimulants than sugar are required to improve this technology. The potency of adenosine triphosphate (ATP) as an alternative model phagostimulant was assessed to determine its capacity to override the aversive effects of select antifeedants and toxicants. How ATP and sucrose modulate the rate of toxicity in the yellow fever mosquito Aedes aegypti was also examined. METHODS A no-choice feeding assay was used to investigate the phagostimulatory ability of ATP to override the aversive effects of structurally divergent antifeedant and toxicant compounds, and to modulate the rate of toxicity over 24 h. Binary combinations of antifeedant and toxicant compounds, at various concentrations, were similarly assessed for enhanced lethal potency. In comparison, no-choice open access and cotton wick feeding assays were used to determine the phagostimulatory role of sucrose in the ingestion of boric acid-laced diets. Dissections of the guts were performed to determine the diet destination as dependant on the phagostimulant. RESULTS ATP is a potent phagostimulant that dose dependently overrides aversion to antifeedant and toxicant tastants. Feeding on antifeedant- or toxicant-laced diets that was induced by ATP selectively resulted in rapid knockdown (nicotine, lobeline and caffeine) or death (boric acid and propylene glycol), with a combination of the two lethal compounds inducing a synergistic effect at lower concentrations. ATP- and sucrose-induced feeding predominantly directed the antifeedant- or toxicant-laced meals to the midgut and the crop, respectively. CONCLUSIONS ATP is an efficacious alternative model phagostimulant to sucrose that overrides the aversive effects of antifeedants and toxicants, resulting in rapid toxic effects. Furthermore, this study demonstrates that variation in the rate of toxicity between ATP- and sugar-induced feeding is at least partly regulated by the differential feeding response, volume imbibed and the destination of the meals. Additional research is needed to identify structurally related, stable analogues of ATP due to the ephemeral nature of this molecule. For future applications, the workflow presented in this study may be used to evaluate such analogues for their suitability for use in attractive bait stations designed to target a broad range of haematophagous arthropods and prevent off-target species' feeding.
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Affiliation(s)
- Matthew Lukenge
- Disease Vector Group, Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Rickard Ignell
- Disease Vector Group, Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Sharon Rose Hill
- Disease Vector Group, Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.
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11
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Sinclair P, Kabbani N. Ionotropic and metabotropic responses by alpha 7 nicotinic acetylcholine receptors. Pharmacol Res 2023; 197:106975. [PMID: 38032294 DOI: 10.1016/j.phrs.2023.106975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/12/2023] [Accepted: 10/26/2023] [Indexed: 12/01/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) belong to a superfamily of cys-loop receptors characterized by the assembly of five subunits into a multi-protein channel complex. Ligand binding to nAChRs activates rapid allosteric transitions of the receptor leading to channel opening and ion flux in neuronal and non-neuronal cell. Thus, while ionotropic properties of nAChRs are well recognized, less is known about ligand-mediated intracellular metabotropic signaling responses. Studies in neural and non-neural cells confirm ionotropic and metabotropic channel responses following ligand binding. In this review we summarize evidence on the existence of ionotropic and metabotropic signaling responses by homopentameric α7 nAChRs in various cell types. We explore how coordinated calcium entry through the ion channel and calcium release from nearby stores gives rise to signaling important for the modulation of cytoskeletal motility and cell growth. Amino acid residues for intracellular protein binding within the α7 nAChR support engagement in metabotropic responses including signaling through heterotrimeric G proteins in neural and immune cells. Understanding the dual properties of ionotropic and metabotropic nAChR responses is essential in advancing drug development for the treatment of various human disease.
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Affiliation(s)
| | - Nadine Kabbani
- Interdisciplinary Program in Neuroscience, Fairfax, VA, USA; School of Systems Biology, George Mason University, Fairfax, VA, USA.
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12
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Singh N, Wanjari A, Sinha AH. Effects of Nicotine on the Central Nervous System and Sleep Quality in Relation to Other Stimulants: A Narrative Review. Cureus 2023; 15:e49162. [PMID: 38130519 PMCID: PMC10733894 DOI: 10.7759/cureus.49162] [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: 10/02/2023] [Accepted: 11/20/2023] [Indexed: 12/23/2023] Open
Abstract
Nicotine is used extensively across the globe despite the common awareness of the fact that it might stimulate the neurological system in those who indulge in its consumption. Nicotine can be consumed in a wide number of various forms and can also be delivered in a wide variety of different ways. After it has been heated, it can be smoked, consumed sublingually, or brought into touch with mucosal surfaces, with the buccal mucosa being the most popular one. These three methods of consumption account for the vast majority of its use. It has been demonstrated without a reasonable doubt that people who partake in nicotine do, in fact, experience an increase in their levels of alertness, wakefulness, attention, and focus. The half-life of the substance, in addition to its effects, is highly variable depending on the forms in which it is consumed, viz. cigarettes, tobacco, gums, lozenges, and the manner in which it is administered. This is the case regardless of whether the chemical is administered orally or intravenously. It is common for a person to require multiple "hits" of the chemical throughout the course of the day, though the frequency of these needs and the intervals between them can vary greatly. The time interval between each of these "hits" can range anywhere from a few hours to a few minutes. The user has the potential to develop a tolerance to the neurostimulatory and systemic effects of nicotine, as well as a heightened sensitivity to those effects, and even hereditary predispositions to specific adverse consequences. There is also a possibility that the user will develop an addiction to nicotine. This literature review aims to explore the relationship between nicotine consumption and its effects on the central nervous system, especially on sleep.
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Affiliation(s)
- Nihaal Singh
- Medicine, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
| | - Anil Wanjari
- Medicine, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
| | - Arya Harshyt Sinha
- Medicine, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
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13
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Zhang Y, Chen H, Li R, Sterling K, Song W. Amyloid β-based therapy for Alzheimer's disease: challenges, successes and future. Signal Transduct Target Ther 2023; 8:248. [PMID: 37386015 PMCID: PMC10310781 DOI: 10.1038/s41392-023-01484-7] [Citation(s) in RCA: 73] [Impact Index Per Article: 73.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 05/05/2023] [Accepted: 05/09/2023] [Indexed: 07/01/2023] Open
Abstract
Amyloid β protein (Aβ) is the main component of neuritic plaques in Alzheimer's disease (AD), and its accumulation has been considered as the molecular driver of Alzheimer's pathogenesis and progression. Aβ has been the prime target for the development of AD therapy. However, the repeated failures of Aβ-targeted clinical trials have cast considerable doubt on the amyloid cascade hypothesis and whether the development of Alzheimer's drug has followed the correct course. However, the recent successes of Aβ targeted trials have assuaged those doubts. In this review, we discussed the evolution of the amyloid cascade hypothesis over the last 30 years and summarized its application in Alzheimer's diagnosis and modification. In particular, we extensively discussed the pitfalls, promises and important unanswered questions regarding the current anti-Aβ therapy, as well as strategies for further study and development of more feasible Aβ-targeted approaches in the optimization of AD prevention and treatment.
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Affiliation(s)
- Yun Zhang
- National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital, Capital Medical University, Beijing, China.
| | - Huaqiu Chen
- National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Ran Li
- The Second Affiliated Hospital and Yuying Children's Hospital, Institute of Aging, Key Laboratory of Alzheimer's Disease of Zhejiang Province, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Keenan Sterling
- Townsend Family Laboratories, Department of Psychiatry, The University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
| | - Weihong Song
- National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital, Capital Medical University, Beijing, China.
- The Second Affiliated Hospital and Yuying Children's Hospital, Institute of Aging, Key Laboratory of Alzheimer's Disease of Zhejiang Province, Wenzhou Medical University, Wenzhou, Zhejiang, China.
- Townsend Family Laboratories, Department of Psychiatry, The University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Wenzhou, Zhejiang, China.
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14
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Choi Y, Nam YH, Jeong S, Lee HY, Choi SY, Park S, Jung SC. Biochemical and functional characterization of skeletal muscle cells differentiated from tonsil-derived mesenchymal stem cells. Muscle Nerve 2023. [PMID: 37243484 DOI: 10.1002/mus.27847] [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: 11/08/2022] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/28/2023]
Abstract
INTRODUCTION/AIMS Human tonsils are a readily accessible source of stem cells for the potential treatment of skeletal muscle disorders. We reported previously that tonsil-derived mesenchymal stem cells (TMSCs) can differentiate into skeletal muscle cells (SKMCs), which renders TMSCs promising candidates for cell therapy for skeletal muscle disorders. However, the functional properties of the myocytes differentiated from mesenchymal stem cells have not been clearly evaluated. In this study we investigated whether myocytes differentiated from TMSCs (skeletal muscle cells derived from tonsil mesenchymal stem cells [TMSC-SKMCs]) exhibit the functional characteristics of SKMCs. METHODS To test the insulin reactivity of TMSC-SKMCs, the expression of glucose transporter 4 (GLUT4) and phosphatidylinositol 3-kinase/Akt was analyzed after the cells were treated for 30 minutes with 100 nmol/L insulin in normal or high-glucose medium. We also examined whether these cells formed a neuromuscular junction (NMJ) when cocultured with motor neurons, and whether they were stimulated by electrical signals using whole-cell patch clamping. RESULTS Skeletal muscle cells derived from tonsil mesenchymal stem cells expressed SKMC markers, such as MYOD, MYH3, MYH8, TNNI1, and TTN, at high levels, and exhibited a multinucleated cell morphology and a myotube-like shape. The expression of the acetylcholine receptor and GLUT4 was confirmed in TMSC-SKMCs. In addition, these cells exhibited insulin-mediated glucose uptake, NMJ formation, and transient changes in cell membrane action potential, all of which are representative functions of human SKMCs. DISCUSSION Tonsil-derived mesenchymal stem cells can be functionally differentiated into SKMCs and may have potential for clinical application for the treatment of skeletal muscle disorders.
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Affiliation(s)
- Yeonzi Choi
- Department of Biochemistry, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
- Graduate Program in System Health Science and Engineering, Ewha Womans University, Seoul, Republic of Korea
| | - Yu Hwa Nam
- Department of Biochemistry, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
- Graduate Program in System Health Science and Engineering, Ewha Womans University, Seoul, Republic of Korea
| | - Soyeon Jeong
- Department of Biochemistry, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Hee-Yoon Lee
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Se-Young Choi
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Saeyoung Park
- Department of Biochemistry, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Sung-Chul Jung
- Department of Biochemistry, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
- Graduate Program in System Health Science and Engineering, Ewha Womans University, Seoul, Republic of Korea
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15
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Bkaily G, Jacques D. Calcium Homeostasis, Transporters, and Blockers in Health and Diseases of the Cardiovascular System. Int J Mol Sci 2023; 24:ijms24108803. [PMID: 37240147 DOI: 10.3390/ijms24108803] [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: 02/21/2023] [Revised: 05/06/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
Calcium is a highly positively charged ionic species. It regulates all cell types' functions and is an important second messenger that controls and triggers several mechanisms, including membrane stabilization, permeability, contraction, secretion, mitosis, intercellular communications, and in the activation of kinases and gene expression. Therefore, controlling calcium transport and its intracellular homeostasis in physiology leads to the healthy functioning of the biological system. However, abnormal extracellular and intracellular calcium homeostasis leads to cardiovascular, skeletal, immune, secretory diseases, and cancer. Therefore, the pharmacological control of calcium influx directly via calcium channels and exchangers and its outflow via calcium pumps and uptake by the ER/SR are crucial in treating calcium transport remodeling in pathology. Here, we mainly focused on selective calcium transporters and blockers in the cardiovascular system.
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Affiliation(s)
- Ghassan Bkaily
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Danielle Jacques
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
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16
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Barrantes FJ. Structure and function meet at the nicotinic acetylcholine receptor-lipid interface. Pharmacol Res 2023; 190:106729. [PMID: 36931540 DOI: 10.1016/j.phrs.2023.106729] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023]
Abstract
The nicotinic acetylcholine receptor (nAChR) is a transmembrane protein that mediates fast intercellular communication in response to the endogenous neurotransmitter acetylcholine. It is the best characterized and archetypal molecule in the superfamily of pentameric ligand-gated ion channels (pLGICs). As a typical transmembrane macromolecule, it interacts extensively with its vicinal lipid microenvironment. Experimental evidence provides a wealth of information on receptor-lipid crosstalk: the nAChR exerts influence on its immediate membrane environment and conversely, the lipid moiety modulates ligand binding, affinity state transitions and gating of ion translocation functions of the receptor protein. Recent cryogenic electron microscopy (cryo-EM) studies have unveiled the occurrence of sites for phospholipids and cholesterol on the lipid-exposed regions of neuronal and electroplax nAChRs, confirming early spectroscopic and affinity labeling studies demonstrating the close contact of lipid molecules with the receptor transmembrane segments. This new data provides structural support to the postulated "lipid sensor" ability displayed by the outer ring of M4 transmembrane domains and their modulatory role on nAChR function, as we postulated a decade ago. Borrowing from the best characterized nAChR, the electroplax (muscle-type) receptor, and exploiting new structural information on the neuronal nAChR, it is now possible to achieve an improved depiction of these sites. In combination with site-directed mutagenesis, single-channel electrophysiology, and molecular dynamics studies, the new structural information delivers a more comprehensive portrayal of these lipid-sensitive loci, providing mechanistic explanations for their ability to modulate nAChR properties and raising the possibility of targetting them in disease.
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Affiliation(s)
- Francisco J Barrantes
- Laboratory of Molecular Neurobiology, Biomedical Research Institute, Faculty of Medical Sciences, Pontifical Catholic University of Argentina (UCA) - Argentine Scientific & Technol. Research Council (CONICET), Av. Alicia Moreau de Justo 1600, C1107AAZ Buenos Aires, Argentina.
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17
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Chrestia JF, Turani O, Araujo NR, Hernando G, Esandi MDC, Bouzat C. Regulation of nicotinic acetylcholine receptors by post-translational modifications. Pharmacol Res 2023; 190:106712. [PMID: 36863428 DOI: 10.1016/j.phrs.2023.106712] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/21/2023] [Accepted: 02/24/2023] [Indexed: 03/04/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) comprise a family of pentameric ligand-gated ion channels widely distributed in the central and peripheric nervous system and in non-neuronal cells. nAChRs are involved in chemical synapses and are key actors in vital physiological processes throughout the animal kingdom. They mediate skeletal muscle contraction, autonomic responses, contribute to cognitive processes, and regulate behaviors. Dysregulation of nAChRs is associated with neurological, neurodegenerative, inflammatory and motor disorders. In spite of the great advances in the elucidation of nAChR structure and function, our knowledge about the impact of post-translational modifications (PTMs) on nAChR functional activity and cholinergic signaling has lagged behind. PTMs occur at different steps of protein life cycle, modulating in time and space protein folding, localization, function, and protein-protein interactions, and allow fine-tuned responses to changes in the environment. A large body of evidence demonstrates that PTMs regulate all levels of nAChR life cycle, with key roles in receptor expression, membrane stability and function. However, our knowledge is still limited, restricted to a few PTMs, and many important aspects remain largely unknown. There is thus a long way to go to decipher the association of aberrant PTMs with disorders of cholinergic signaling and to target PTM regulation for novel therapeutic interventions. In this review we provide a comprehensive overview of what is known about how different PTMs regulate nAChR.
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Affiliation(s)
- Juan Facundo Chrestia
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Ornella Turani
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Noelia Rodriguez Araujo
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Guillermina Hernando
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - María Del Carmen Esandi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina.
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18
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Abstract
While it has long been established that cell membranes are complex assemblies of proteins and bilayer-forming lipids, the inherent mobility and wide-ranging heterogeneity of the lipids have limited our ability to understand cell-membrane structure at a molecular level. Consequently, little is yet known about the protein-lipid and lipid-lipid interplay that exists in situ. The present study exploits the regular architecture of a cholinergic cell membrane to determine how the phospholipid and cholesterol organization is influenced by the protein surfaces and by differences in cholesterol concentration between the two leaflets. Lipids in the leaflet containing the most cholesterol form an ordered sterol-hydrocarbon “skin.” This hitherto unobserved hydrophobic-core structure has far-reaching implications in terms of how cholesterol-rich membranes are constructed and function. Cell membranes are complex assemblies of proteins and lipids making transient or long-term associations that have yet to be characterized at a molecular level. Here, cryo-electron microscopy is applied to determine how phospholipids and cholesterol arrange between neighboring proteins (nicotinic acetylcholine receptors) of Torpedo cholinergic membrane. The lipids exhibit distinct properties in the two leaflets of the bilayer, influenced by the protein surfaces and by differences in cholesterol concentration. In the outer leaflet, the lipids show no consistent motif away from the protein surfaces, in keeping with their assumed fluidity. In the inner leaflet, where the cholesterol concentration is higher, the lipids organize into extensive close-packed linear arrays. These arrays are built from the sterol groups of cholesterol and the initial saturated portions of the phospholipid hydrocarbon chains. Together, they create an ordered ∼7 Å-thick “skin” within the hydrophobic core of the bilayer. The packing of lipids in the arrays appears to bear a close relationship to the linear cholesterol arrays that form crystalline monolayers at the air-water interface.
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19
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Chandrasekara U, Harris RJ, Fry BG. The Target Selects the Toxin: Specific Amino Acids in Snake-Prey Nicotinic Acetylcholine Receptors That Are Selectively Bound by King Cobra Venoms. Toxins (Basel) 2022; 14:toxins14080528. [PMID: 36006190 PMCID: PMC9416539 DOI: 10.3390/toxins14080528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 07/25/2022] [Accepted: 07/28/2022] [Indexed: 11/16/2022] Open
Abstract
Snake venom is an adaptive ecological trait that has evolved primarily as a form of prey subjugation. Thus, the selection pressure for toxin diversification is exerted by the prey’s physiological targets, with this pressure being particularly acute for specialist feeders, such as the King Cobra species, all of which are snake-prey specialists. However, while extensive research has been undertaken to elucidate key amino acids that guide toxin structure–activity relationships, reciprocal investigations into the specific sites guiding prey-lineage selective effects have been lacking. This has largely been due to the lack of assay systems amenable to systematic amino acid replacements of targeted proteins in the prey’s physiological pathways. To fill this knowledge gap, we used a recently described approach based upon mimotope peptides corresponding to the orthosteric site of nicotinic acetylcholine receptor alpha-1 subunits, a major binding site for snake venom neurotoxins that cause flaccid paralysis. We investigated the venoms of four different types of King Cobra (Cambodian, Javan, Malaysian, and Thai). This approach allowed for the determination of the key amino acid positions in King Cobra snake prey that are selectively bound by the toxins, whereby replacing these amino acids in the snake-prey orthosteric site with those from lizards or rats resulted in a significantly lower level of binding by the venoms, while conversely replacing the lizard or rat amino acids with those from the snake at that position increased the binding. By doing such, we identified three negatively charged amino acids in the snake orthosteric site that are strongly bound by the positively charged neurotoxic three-finger toxins found in King Cobra venom. This study, thus, sheds light on the selection pressures exerted by a specialist prey item for the evolution of lineage-selective toxins.
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20
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Speculation on How RIC-3 and Other Chaperones Facilitate α7 Nicotinic Receptor Folding and Assembly. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27144527. [PMID: 35889400 PMCID: PMC9318448 DOI: 10.3390/molecules27144527] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/07/2022] [Accepted: 07/09/2022] [Indexed: 11/17/2022]
Abstract
The process of how multimeric transmembrane proteins fold and assemble in the endoplasmic reticulum is not well understood. The alpha7 nicotinic receptor (α7 nAChR) is a good model for multimeric protein assembly since it has at least two independent and specialized chaperones: Resistance to Inhibitors of Cholinesterase 3 (RIC-3) and Nicotinic Acetylcholine Receptor Regulator (NACHO). Recent cryo-EM and NMR data revealed structural features of α7 nAChRs. A ser-ala-pro (SAP) motif precedes a structurally important but unique "latch" helix in α7 nAChRs. A sampling of α7 sequences suggests the SAP motif is conserved from C. elegans to humans, but the latch sequence is only conserved in vertebrates. How RIC-3 and NACHO facilitate receptor subunits folding into their final pentameric configuration is not known. The artificial intelligence program AlphaFold2 recently predicted structures for NACHO and RIC-3. NACHO is highly conserved in sequence and structure across species, but RIC-3 is not. This review ponders how different intrinsically disordered RIC-3 isoforms from C. elegans to humans interact with α7 nAChR subunits despite having little sequence homology across RIC-3 species. Two models from the literature about how RIC-3 assists α7 nAChR assembly are evaluated considering recent structural information about the receptor and its chaperones.
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21
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Fan H, Sun F. Developing Graphene Grids for Cryoelectron Microscopy. Front Mol Biosci 2022; 9:937253. [PMID: 35911962 PMCID: PMC9326159 DOI: 10.3389/fmolb.2022.937253] [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: 05/06/2022] [Accepted: 05/31/2022] [Indexed: 11/13/2022] Open
Abstract
Cryogenic electron microscopy (cryo-EM) single particle analysis has become one of the major techniques used to study high-resolution 3D structures of biological macromolecules. Specimens are generally prepared in a thin layer of vitrified ice using a holey carbon grid. However, the sample quality using this type of grid is not always ideal for high-resolution imaging even when the specimens in the test tube behave ideally. Various problems occur during a vitrification procedure, including poor/nonuniform distribution of particles, preferred orientation of particles, specimen denaturation/degradation, high background from thick ice, and beam-induced motion, which have become important bottlenecks in high-resolution structural studies using cryo-EM in many projects. In recent years, grids with support films made of graphene and its derivatives have been developed to efficiently solve these problems. Here, the various advantages of graphene grids over conventional holey carbon film grids, functionalization of graphene support films, production methods of graphene grids, and origins of pristine graphene contamination are reviewed and discussed.
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Affiliation(s)
- Hongcheng Fan
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Fei Sun
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- Bioland Laboratory, Guangzhou, China
- *Correspondence: Fei Sun,
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22
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Zhang L, Wang X, Chen J, Kleyman TR, Sheng S. Accessibility of ENaC extracellular domain central core residues. J Biol Chem 2022; 298:101860. [PMID: 35339489 PMCID: PMC9052164 DOI: 10.1016/j.jbc.2022.101860] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 03/16/2022] [Accepted: 03/21/2022] [Indexed: 11/20/2022] Open
Abstract
The epithelial Na+ channel (ENaC)/degenerin family has a similar extracellular architecture, where specific regulatory factors interact and alter channel gating behavior. The extracellular palm domain serves as a key link to the channel pore. In this study, we used cysteine-scanning mutagenesis to assess the functional effects of Cys-modifying reagents on palm domain β10 strand residues in mouse ENaC. Of the 13 ENaC α subunit mutants with Cys substitutions examined, only mutants at sites in the proximal region of β10 exhibited changes in channel activity in response to methanethiosulfonate reagents. Additionally, Cys substitutions at three proximal sites of β and γ subunit β10 strands also rendered mutant channels methanethiosulfonate-responsive. Moreover, multiple Cys mutants were activated by low concentrations of thiophilic Cd2+. Using the Na+ self-inhibition response to assess ENaC gating behavior, we identified four α, two β, and two γ subunit β10 strand mutations that changed the Na+ self-inhibition response. Our results suggest that the proximal regions of β10 strands in all three subunits are accessible to small aqueous compounds and Cd2+ and have a role in modulating ENaC gating. These results are consistent with a structural model of mouse ENaC that predicts the presence of aqueous tunnels adjacent to the proximal part of β10 and with previously resolved structures of a related family member where palm domain structural transitions were observed with channels in an open or closed state.
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Affiliation(s)
- Lei Zhang
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Nephrology, Hunan Key Laboratory of Kidney Disease and Blood Purification, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; The Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Xueqi Wang
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Nephrology, Hunan Key Laboratory of Kidney Disease and Blood Purification, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; The Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Jingxin Chen
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Thomas R Kleyman
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
| | - Shaohu Sheng
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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23
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Conformational transitions and ligand-binding to a muscle-type nicotinic acetylcholine receptor. Neuron 2022; 110:1358-1370.e5. [PMID: 35139364 DOI: 10.1016/j.neuron.2022.01.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 11/02/2021] [Accepted: 01/10/2022] [Indexed: 12/15/2022]
Abstract
Fast synaptic communication requires receptors that respond to the presence of neurotransmitter by opening an ion channel across the post-synaptic membrane. The muscle-type nicotinic acetylcholine receptor from the electric fish, Torpedo, is the prototypic ligand-gated ion channel, yet the structural changes underlying channel activation remain undefined. Here we use cryo-EM to solve apo and agonist-bound structures of the Torpedo nicotinic receptor embedded in a lipid nanodisc. Using both a direct biochemical assay to define the conformational landscape and molecular dynamics simulations to assay flux through the pore, we correlate structures with functional states and elucidate the motions that lead to pore activation of a heteromeric nicotinic receptor. We highlight an underappreciated role for the complementary subunit in channel gating, establish the structural basis for the differential agonist affinities of α/δ versus α /γ sites, and explain why nicotine is less potent at muscle nicotinic receptors compared to neuronal ones.
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24
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Khatoon N, Adusumilli S, Dey P, Sharma R, Kampani P, Shandilya J, Nayak TK. Protein engineering and design in ion channels and receptors. Methods Cell Biol 2022; 169:143-168. [DOI: 10.1016/bs.mcb.2021.12.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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25
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Shen SY, Ren LQ, Chen HD, Zhu HF, Zhou DF, Zhang B, Tan XQ, Xie YH. Geniposide protects pulmonary arterial smooth muscle cells from lipopolysaccharide-induced injury via α7nAchR-mediated TLR-4/MyD88 signaling. Exp Ther Med 2021; 22:1234. [PMID: 34539830 PMCID: PMC8438699 DOI: 10.3892/etm.2021.10668] [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: 04/12/2020] [Accepted: 02/10/2021] [Indexed: 12/18/2022] Open
Abstract
Geniposide is a bioactive iridoid glucoside derived from Gardenia jasminoides that has proven anti-inflammatory effects against acute lung injury. The aim of this study was to determine whether geniposide could protect pulmonary arterial smooth muscle cells (PASMCs) from lipopolysaccharide (LPS)-induced injury and to explore the participation of α7 nicotinic acetylcholine receptor (α7nAChR), which was previously reported to suppress pro-inflammatory cytokine production in LPS-stimulated macrophages. In the present study, rat PASMCs were isolated and stimulated using LPS. The effect of geniposide on LPS-induced PASMC injury was then explored. Geniposide exerted anti-apoptotic and anti-inflammatory effects on LPS-treated PASMCs, as demonstrated by the downregulation of pro-apoptotic proteins and pro-inflammatory cytokines, respectively. Furthermore, the α7nAChR agonist PNU282987 accentuated the protective effect of geniposide against LPS-induced injury in PASMCs by inhibiting toll-like receptor-4/myeloid differentiation primary response 88 (TLR-4/MyD88) signaling and downregulating nuclear factor (NF)-κB expression. Conversely, methyllycaconitine, an inhibitor of α7nAChR, attenuated the effects of geniposide. These findings collectively suggested that in conjunction with geniposide, the activation of α7nAChR may contribute to further mitigating LPS-induced PASMC apoptosis and inflammation. In addition, the underlying mechanisms critically involve the NF-κB/MyD88 signaling axis. These results may provide novel insights into the treatment and management of lung diseases via geniposide administration.
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Affiliation(s)
- San-Ying Shen
- Department of Respiratory Medicine, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430033, P.R. China
| | - Li-Quan Ren
- Department of Medical Services, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430033, P.R. China
| | - Hui-Dong Chen
- Department of Respiratory Medicine, Wuhan Jinyintan Hospital, Wuhan, Hubei 430023, P.R. China
| | - Hong-Fei Zhu
- Hubei Research Institute of Traditional Chinese Medicine, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, Hubei 430072, P.R. China
| | - Deng-Feng Zhou
- Department of Respiratory Medicine, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430033, P.R. China
| | - Bo Zhang
- Department of Respiratory Medicine, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430033, P.R. China
| | - Xiao-Qin Tan
- Department of Respiratory Medicine, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430033, P.R. China
| | - Yong-Hua Xie
- Department of Traditional Chinese Medicine, Wuhan Fourth Hospital, Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430033, P.R. China
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26
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Borroni V, Barrantes FJ. Homomeric and Heteromeric α7 Nicotinic Acetylcholine Receptors in Health and Some Central Nervous System Diseases. MEMBRANES 2021; 11:membranes11090664. [PMID: 34564481 PMCID: PMC8465519 DOI: 10.3390/membranes11090664] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/24/2021] [Accepted: 08/24/2021] [Indexed: 11/22/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels involved in the modulation of essential brain functions such as memory, learning, and attention. Homomeric α7 nAChR, formed exclusively by five identical α7 subunits, is involved in rapid synaptic transmission, whereas the heteromeric oligomers composed of α7 in combination with β subunits display metabotropic properties and operate in slower time frames. At the cellular level, the activation of nAChRs allows the entry of Na+ and Ca2+; the two cations depolarize the membrane and trigger diverse cellular signals, depending on the type of nAChR pentamer and neurons involved, the location of the intervening cells, and the networks of which these neuronal cells form part. These features make the α7 nAChR a central player in neurotransmission, metabolically associated Ca2+-mediated signaling, and modulation of diverse fundamental processes operated by other neurotransmitters in the brain. Due to its ubiquitous distribution and the multiple functions it displays in the brain, the α7 nAChR is associated with a variety of neurological and neuropsychiatric disorders whose exact etiopathogenic mechanisms are still elusive.
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Affiliation(s)
- Virginia Borroni
- Instituto de Tecnología en Polímeros y Nanotecnología (ITPN-UBA-CONICET), Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires C1127AAR, Argentina;
| | - Francisco J. Barrantes
- Laboratory of Molecular Neurobiology, Institute for Biomedical Research, UCA–CONICET, Faculty of Medical Sciences, Catholic University of Argentina, Av. Alicia Moreau de Justo 1600, Buenos Aires C1107AAZ, Argentina
- Correspondence:
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27
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Elephants in the Dark: Insights and Incongruities in Pentameric Ligand-gated Ion Channel Models. J Mol Biol 2021; 433:167128. [PMID: 34224751 DOI: 10.1016/j.jmb.2021.167128] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/25/2021] [Accepted: 06/25/2021] [Indexed: 02/06/2023]
Abstract
The superfamily of pentameric ligand-gated ion channels (pLGICs) comprises key players in electrochemical signal transduction across evolution, including historic model systems for receptor allostery and targets for drug development. Accordingly, structural studies of these channels have steadily increased, and now approach 250 depositions in the protein data bank. This review contextualizes currently available structures in the pLGIC family, focusing on morphology, ligand binding, and gating in three model subfamilies: the prokaryotic channel GLIC, the cation-selective nicotinic acetylcholine receptor, and the anion-selective glycine receptor. Common themes include the challenging process of capturing and annotating channels in distinct functional states; partially conserved gating mechanisms, including remodeling at the extracellular/transmembrane-domain interface; and diversity beyond the protein level, arising from posttranslational modifications, ligands, lipids, and signaling partners. Interpreting pLGIC structures can be compared to describing an elephant in the dark, relying on touch alone to comprehend the many parts of a monumental beast: each structure represents a snapshot in time under specific experimental conditions, which must be integrated with further structure, function, and simulations data to build a comprehensive model, and understand how one channel may fundamentally differ from another.
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28
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Alhowail A. Molecular insights into the benefits of nicotine on memory and cognition (Review). Mol Med Rep 2021; 23:398. [PMID: 33786606 PMCID: PMC8025477 DOI: 10.3892/mmr.2021.12037] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 10/13/2020] [Indexed: 01/19/2023] Open
Abstract
The health risks of nicotine are well known, but there is some evidence of its beneficial effects on cognitive function. The present review focused on the reported benefits of nicotine in the brain and summarizes the associated underlying mechanisms. Nicotine administration can improve cognitive impairment in Alzheimer's disease (AD), and dyskinesia and memory impairment in Parkinson's disease (PD). In terms of its mechanism of action, nicotine slows the progression of PD by inhibiting Sirtuin 6, a stress‑responsive protein deacetylase, thereby decreasing neuronal apoptosis and improving neuronal survival. In AD, nicotine improves cognitive impairment by enhancing protein kinase B (also referred to as Akt) activity and stimulating phosphoinositide 3‑kinase/Akt signaling, which regulates learning and memory processes. Nicotine may also activate thyroid receptor signaling pathways to improve memory impairment caused by hypothyroidism. In healthy individuals, nicotine improves memory impairment caused by sleep deprivation by enhancing the phosphorylation of calmodulin‑dependent protein kinase II, an essential regulator of cell proliferation and synaptic plasticity. Furthermore, nicotine may improve memory function through its effect on chromatin modification via the inhibition of histone deacetylases, which causes transcriptional changes in memory‑related genes. Finally, nicotine administration has been demonstrated to rescue long‑term potentiation in individuals with sleep deprivation, AD, chronic stress and hypothyroidism, primarily by desensitizing α7 nicotinic acetylcholine receptors. To conclude, nicotine has several cognitive benefits in healthy individuals, as well as in those with cognitive dysfunction associated with various diseases. However, further research is required to shed light on the effect of acute and chronic nicotine treatment on memory function.
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Affiliation(s)
- Ahmad Alhowail
- Department of Pharmacology and Toxicology, College of Pharmacy, Qassim University, Buraydah 52571, Qassim, Kingdom of Saudi Arabia
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29
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An Inside Job: Molecular Determinants for Postsynaptic Localization of Nicotinic Acetylcholine Receptors. Molecules 2021; 26:molecules26113065. [PMID: 34063759 PMCID: PMC8196675 DOI: 10.3390/molecules26113065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/13/2021] [Accepted: 05/15/2021] [Indexed: 11/29/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic transmission at neuromuscular and autonomic ganglionic synapses in the peripheral nervous system. The postsynaptic localization of muscle ((α1)2β1γδ) and neuronal ((α3β4)2β4) nicotinic receptors at these synapses is mediated by interactions between the nAChR intracellular domains and cytoplasmic scaffolding proteins. Recent high resolution structures and functional studies provide new insights into the molecular determinants that mediate these interactions. Surprisingly, they reveal that the muscle nAChR binds 1–3 rapsyn scaffolding molecules, which dimerize and thereby form an interconnected lattice between receptors. Moreover, rapsyn binds two distinct sites on the nAChR subunit cytoplasmic loops; the MA-helix on one or more subunits and a motif specific to the β subunit. Binding at the latter site is regulated by agrin-induced phosphorylation of βY390, and increases the stoichiometry of rapsyn/AChR complexes. Similarly, the neuronal nAChR may be localized at ganglionic synapses by phosphorylation-dependent interactions with 14-3-3 adaptor proteins which bind specific motifs in each of the α3 subunit cytoplasmic loops. Thus, postsynaptic localization of nAChRs is mediated by regulated interactions with multiple scaffolding molecules, and the stoichiometry of these complexes likely helps regulate the number, density, and stability of receptors at the synapse.
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30
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Oliveira ASF, Ibarra AA, Bermudez I, Casalino L, Gaieb Z, Shoemark DK, Gallagher T, Sessions RB, Amaro RE, Mulholland AJ. A potential interaction between the SARS-CoV-2 spike protein and nicotinic acetylcholine receptors. Biophys J 2021; 120:983-993. [PMID: 33609494 PMCID: PMC7889469 DOI: 10.1016/j.bpj.2021.01.037] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 01/11/2021] [Accepted: 01/13/2021] [Indexed: 01/08/2023] Open
Abstract
Changeux et al. (Changeux et al. C. R. Biol. 343:33-39.) recently suggested that the SARS-CoV-2 spike protein may interact with nicotinic acetylcholine receptors (nAChRs) and that such interactions may be involved in pathology and infectivity. This hypothesis is based on the fact that the SARS-CoV-2 spike protein contains a sequence motif similar to known nAChR antagonists. Here, we use molecular simulations of validated atomically detailed structures of nAChRs and of the spike to investigate the possible binding of the Y674-R685 region of the spike to nAChRs. We examine the binding of the Y674-R685 loop to three nAChRs, namely the human α4β2 and α7 subtypes and the muscle-like αβγδ receptor from Tetronarce californica. Our results predict that Y674-R685 has affinity for nAChRs. The region of the spike responsible for binding contains a PRRA motif, a four-residue insertion not found in other SARS-like coronaviruses. The conformational behavior of the bound Y674-R685 is highly dependent on the receptor subtype; it adopts extended conformations in the α4β2 and α7 complexes but is more compact when bound to the muscle-like receptor. In the α4β2 and αβγδ complexes, the interaction of Y674-R685 with the receptors forces the loop C region to adopt an open conformation, similar to other known nAChR antagonists. In contrast, in the α7 complex, Y674-R685 penetrates deeply into the binding pocket in which it forms interactions with the residues lining the aromatic box, namely with TrpB, TyrC1, and TyrC2. Estimates of binding energy suggest that Y674-R685 forms stable complexes with all three nAChR subtypes. Analyses of simulations of the glycosylated spike show that the Y674-R685 region is accessible for binding. We suggest a potential binding orientation of the spike protein with nAChRs, in which they are in a nonparallel arrangement to one another.
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Affiliation(s)
- A Sofia F Oliveira
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, United Kingdom; Bristol Synthetic Biology Centre, BrisSynBio, Bristol, United Kingdom
| | - Amaurys Avila Ibarra
- Research Software Engineering, Advanced Computing Research Centre, University of Bristol, Bristol, United Kingdom
| | - Isabel Bermudez
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
| | - Lorenzo Casalino
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California
| | - Zied Gaieb
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California
| | - Deborah K Shoemark
- School of Biochemistry, University of Bristol, Bristol, United Kingdom; Bristol Synthetic Biology Centre, BrisSynBio, Bristol, United Kingdom
| | - Timothy Gallagher
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, United Kingdom
| | | | - Rommie E Amaro
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California
| | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, United Kingdom.
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31
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Rahman MM, Worrell BT, Stowell MHB, Hibbs RE. Purification of a native nicotinic receptor. Methods Enzymol 2021; 653:189-206. [PMID: 34099171 DOI: 10.1016/bs.mie.2020.12.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Nicotinic acetylcholine receptors are members of the Cys-loop superfamily of pentameric ligand-gated ion channels. The electric organ of the Torpedo ray is extraordinarily rich in an acetylcholine receptor that is homologous to the human nicotinic receptor found at the neuromuscular junction. Due to this abundant natural source in the fish and the relatively accessible preparation of the neuromuscular junction (compared to a central synapse), this muscle-type receptor and specifically the fish receptors have long been used as the prototype for study of nicotinic receptors. However, an absence of structural detail at high resolution has limited the chemical interpretation of this archetypal nicotinic receptor. One of the main concerns in preparing receptor for high resolution structural analysis was its documented sensitivity to particular detergents and requirements for specific lipids in order to maintain function after reconstitution in a membrane. Here, we present methods for purifying native nicotinic receptor from Torpedo electric tissue that maintains functionality after reconstitution and that is amenable to high resolution structural analysis. The specific developments we describe include detergent exchange during purification, inclusion of specific lipids during purification and for nanodisc reconstitution, and synthesis of a new affinity reagent for rapid isolation of receptors.
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Affiliation(s)
- Md Mahfuzur Rahman
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Brady T Worrell
- Department of Molecular, Cellular & Developmental Biology, University of Colorado, Boulder, CO, United States
| | - Michael H B Stowell
- Department of Molecular, Cellular & Developmental Biology, University of Colorado, Boulder, CO, United States.
| | - Ryan E Hibbs
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, United States.
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32
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Ivica J, Lape R, Jazbec V, Yu J, Zhu H, Gouaux E, Gold MG, Sivilotti LG. The intracellular domain of homomeric glycine receptors modulates agonist efficacy. J Biol Chem 2021; 296:100387. [PMID: 33617876 PMCID: PMC7995613 DOI: 10.1074/jbc.ra119.012358] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/19/2020] [Indexed: 11/20/2022] Open
Abstract
Like other pentameric ligand-gated channels, glycine receptors (GlyRs) contain long intracellular domains (ICDs) between transmembrane helices 3 and 4. Structurally characterized GlyRs are generally engineered to have a very short ICD. We show here that for one such construct, zebrafish GlyREM, the agonists glycine, β-alanine, taurine, and GABA have high efficacy and produce maximum single-channel open probabilities greater than 0.9. In contrast, for full-length human α1 GlyR, taurine and GABA were clearly partial agonists, with maximum open probabilities of 0.46 and 0.09, respectively. We found that the elevated open probabilities in GlyREM are not due to the limited sequence differences between the human and zebrafish orthologs, but rather to replacement of the native ICD with a short tripeptide ICD. Consistent with this interpretation, shortening the ICD in the human GlyR increased the maximum open probability produced by taurine and GABA to 0.90 and 0.70, respectively, but further engineering it to resemble GlyREM (by introducing the zebrafish transmembrane helix 4 and C terminus) had no effect. Furthermore, reinstating the native ICD to GlyREM converted taurine and GABA to partial agonists, with maximum open probabilities of 0.66 and 0.40, respectively. Structural comparison of transmembrane helices 3 and 4 in short- and long-ICD GlyR subunits revealed that ICD shortening does not distort the orientation of these helices within each subunit. This suggests that the effects of shortening the ICD stem from removing a modulatory effect of the native ICD on GlyR gating, revealing a new role for the ICD in pentameric ligand-gated channels.
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Key Words
- 5-ht3, 5-hydroxytryptamine type 3
- dmem, dulbecco’s modified eagle’s medium
- ecd, extracellular domain
- glyr, glycine receptor
- icd, intracellular domain
- popen, open probability
- pdb, protein data bank
- plgic, pentameric ligand-gated ion channels
- tm, transmembrane
- zf, zebrafish
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Affiliation(s)
- Josip Ivica
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, United Kingdom
| | - Remigijus Lape
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, United Kingdom
| | - Vid Jazbec
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Jie Yu
- Vollum Institute, Oregon Health & Science University, Portland, Oregon 97239
| | - Hongtao Zhu
- Vollum Institute, Oregon Health & Science University, Portland, Oregon 97239
| | - Eric Gouaux
- Howard Hughes Medical Institute, Oregon Health & Science University, Portland, Oregon 97239
| | - Matthew G Gold
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, United Kingdom
| | - Lucia G Sivilotti
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, United Kingdom.
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33
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Li F, Egea PF, Vecchio AJ, Asial I, Gupta M, Paulino J, Bajaj R, Dickinson MS, Ferguson-Miller S, Monk BC, Stroud RM. Highlighting membrane protein structure and function: A celebration of the Protein Data Bank. J Biol Chem 2021; 296:100557. [PMID: 33744283 PMCID: PMC8102919 DOI: 10.1016/j.jbc.2021.100557] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 02/10/2021] [Accepted: 03/16/2021] [Indexed: 12/13/2022] Open
Abstract
Biological membranes define the boundaries of cells and compartmentalize the chemical and physical processes required for life. Many biological processes are carried out by proteins embedded in or associated with such membranes. Determination of membrane protein (MP) structures at atomic or near-atomic resolution plays a vital role in elucidating their structural and functional impact in biology. This endeavor has determined 1198 unique MP structures as of early 2021. The value of these structures is expanded greatly by deposition of their three-dimensional (3D) coordinates into the Protein Data Bank (PDB) after the first atomic MP structure was elucidated in 1985. Since then, free access to MP structures facilitates broader and deeper understanding of MPs, which provides crucial new insights into their biological functions. Here we highlight the structural and functional biology of representative MPs and landmarks in the evolution of new technologies, with insights into key developments influenced by the PDB in magnifying their impact.
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Affiliation(s)
- Fei Li
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA; Department of Neurology, University of California San Francisco, San Francisco, California, USA
| | - Pascal F Egea
- Department of Biological Chemistry, School of Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - Alex J Vecchio
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | | | - Meghna Gupta
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA
| | - Joana Paulino
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA
| | - Ruchika Bajaj
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, USA
| | - Miles Sasha Dickinson
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA
| | - Shelagh Ferguson-Miller
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - Brian C Monk
- Sir John Walsh Research Institute and Department of Oral Sciences, University of Otago, North Dunedin, Dunedin, New Zealand
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA.
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34
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Li X, Tae HS, Chu Y, Jiang T, Adams DJ, Yu R. Medicinal chemistry, pharmacology, and therapeutic potential of α-conotoxins antagonizing the α9α10 nicotinic acetylcholine receptor. Pharmacol Ther 2020; 222:107792. [PMID: 33309557 DOI: 10.1016/j.pharmthera.2020.107792] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/07/2020] [Indexed: 12/20/2022]
Abstract
α-Conotoxins are disulfide-rich and well-structured peptides, most of which can block nicotinic acetylcholine receptors (nAChRs) with exquisite selectivity and potency. There are various nAChR subtypes, of which the α9α10 nAChR functions as a heteromeric ionotropic receptor in the mammalian cochlea and mediates postsynaptic transmission from the medial olivocochlear. The α9α10 nAChR subtype has also been proposed as a target for the treatment of neuropathic pain and the suppression of breast cancer cell proliferation. Therefore, α-conotoxins targeting the α9α10 nAChR are potentially useful in the development of specific therapeutic drugs and pharmacological tools. Despite dissimilarities in their amino acid sequence and structures, these conopeptides are potent antagonists of the α9α10 nAChR subtype. Consequently, the activity and stability of these peptides have been subjected to chemical modifications. The resulting synthetic analogues have not only functioned as molecular probes to explore ligand binding sites of the α9α10 nAChR, but also have the potential to become candidates for drug development. From the perspectives of medicinal chemistry and pharmacology, we highlight the structure and function of the α9α10 nAChR and review studies of α-conotoxins targeting it, including their three-dimensional structures, structure optimization strategies, and binding modes at the α9α10 nAChR, as well as their therapeutic potential.
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Affiliation(s)
- Xiao Li
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China; Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Yanyan Chu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China; Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China; Innovation Platform of Marine Drug Screening & Evaluation, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266100, China
| | - Tao Jiang
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China; Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia.
| | - Rilei Yu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China; Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China; Innovation Platform of Marine Drug Screening & Evaluation, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266100, China.
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35
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Matsuda K, Ihara M, Sattelle DB. Neonicotinoid Insecticides: Molecular Targets, Resistance, and Toxicity. Annu Rev Pharmacol Toxicol 2020; 60:241-255. [PMID: 31914891 DOI: 10.1146/annurev-pharmtox-010818-021747] [Citation(s) in RCA: 135] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neonicotinoids have been used to protect crops and animals from insect pests since the 1990s, but there are concerns regarding their adverse effects on nontarget organisms, notably on bees. Enhanced resistance to neonicotinoids in pests is becoming well documented. We address the current understanding of neonicotinoid target site interactions, selectivity, and metabolism not only in pests but also in beneficial insects such as bees. The findings are relevant to the management of both neonicotinoids and the new generation of pesticides targeting insect nicotinic acetylcholine receptors.
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Affiliation(s)
- Kazuhiko Matsuda
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, Nara 631-8505, Japan; .,Agricultural Technology and Innovation Research Institute, Kindai University, Nara 631-8505, Japan
| | - Makoto Ihara
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, Nara 631-8505, Japan;
| | - David B Sattelle
- Centre for Respiratory Biology, UCL Respiratory, University College London, London WC1E 6JF, United Kingdom;
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36
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Oliveira ASF, Ibarra AA, Bermudez I, Casalino L, Gaieb Z, Shoemark DK, Gallagher T, Sessions RB, Amaro RE, Mulholland AJ. Simulations support the interaction of the SARS-CoV-2 spike protein with nicotinic acetylcholine receptors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020:2020.07.16.206680. [PMID: 32743575 PMCID: PMC7386492 DOI: 10.1101/2020.07.16.206680] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Changeux et al. recently suggested that the SARS-CoV-2 spike (S) protein may interact with nicotinic acetylcholine receptors (nAChRs). Such interactions may be involved in pathology and infectivity. Here, we use molecular simulations of validated atomically detailed structures of nAChRs, and of the S protein, to investigate this 'nicotinic hypothesis'. We examine the binding of the Y674-R685 loop of the S protein to three nAChRs, namely the human α4β2 and α7 subtypes and the muscle-like αβγδ receptor from Tetronarce californica. Our results indicate that Y674-R685 has affinity for nAChRs and the region responsible for binding contains the PRRA motif, a four-residue insertion not found in other SARS-like coronaviruses. In particular, R682 has a key role in the stabilisation of the complexes as it forms interactions with loops A, B and C in the receptor's binding pocket. The conformational behaviour of the bound Y674-R685 region is highly dependent on the receptor subtype, adopting extended conformations in the α4β2 and α7 complexes and more compact ones when bound to the muscle-like receptor. In the α4β2 and αβγδ complexes, the interaction of Y674-R685 with the receptors forces the loop C region to adopt an open conformation similar to other known nAChR antagonists. In contrast, in the α7 complex, Y674-R685 penetrates deeply into the binding pocket where it forms interactions with the residues lining the aromatic box, namely with TrpB, TyrC1 and TyrC2. Estimates of binding energy suggest that Y674-R685 forms stable complexes with all three nAChR subtypes. Analyses of the simulations of the full-length S protein show that the Y674-R685 region is accessible for binding, and suggest a potential binding orientation of the S protein with nAChRs.
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Affiliation(s)
- A. Sofia F. Oliveira
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | - Amaurys Avila Ibarra
- Research Software Engineering, Advanced Computing Research Centre, University of Bristol, Bristol BS1 5QD, UK
| | - Isabel Bermudez
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX30BP, UK
| | - Lorenzo Casalino
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, 92093 USA
| | - Zied Gaieb
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, 92093 USA
| | | | - Timothy Gallagher
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | | | - Rommie E. Amaro
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, 92093 USA
| | - Adrian J. Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
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37
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Cottone G, Chiodo L, Maragliano L. Thermodynamics and Kinetics of Ion Permeation in Wild-Type and Mutated Open Active Conformation of the Human α7 Nicotinic Receptor. J Chem Inf Model 2020; 60:5045-5056. [PMID: 32803965 PMCID: PMC8011927 DOI: 10.1021/acs.jcim.0c00549] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
Molecular
studies of human pentameric ligand-gated ion channels
(LGICs) expressed in neurons and at neuromuscular junctions are of
utmost importance in the development of therapeutic strategies for
neurological disorders. We focus here on the nicotinic acetylcholine
receptor nAChR-α7, a homopentameric channel widely expressed
in the human brain, with a proven role in a wide spectrum of disorders
including schizophrenia and Alzheimer’s disease. By exploiting
an all-atom structural model of the full (transmembrane and extracellular)
protein in the open, agonist-bound conformation we recently developed,
we evaluate the free energy and the mean first passage time of single-ion
permeation using molecular dynamics simulations and the milestoning
method with Voronoi tessellation. The results for the wild-type channel
provide the first available mapping of the potential of mean force
in the full-length α7 nAChR, reveal its expected cationic nature,
and are in good agreement with simulation data for other channels
of the LGIC family and with experimental data on nAChRs. We then investigate
the role of a specific mutation directly related to ion selectivity
in LGICs, the E-1′ → A-1′ substitution at the
cytoplasmatic selectivity filter. We find that the mutation strongly
affects sodium and chloride permeation in opposite directions, leading
to a complete inversion of selectivity, at variance with the limited
experimental results available that classify this mutant as cationic.
We thus provide structural determinants for the observed cationic-to-anionic
inversion, revealing a key role of the protonation state of residue
rings far from the mutation, in the proximity of the hydrophobic channel
gate.
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Affiliation(s)
- Grazia Cottone
- Department of Physics and Chemistry-Emilio Segrè, University of Palermo, Viale delle Scienze Ed. 17, 90128 Palermo, Italy
| | - Letizia Chiodo
- Department of Engineering, Campus Bio-Medico University of Rome, Via Á. del Portillo 21, 00128 Rome, Italy
| | - Luca Maragliano
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi, 10, 16132 Genova, Italy.,IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi, 10, 16132 Genova, Italy
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38
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Optical control of muscular nicotinic channels with azocuroniums, photoswitchable azobenzenes bearing two N-methyl-N-carbocyclic quaternary ammonium groups. Eur J Med Chem 2020; 200:112403. [DOI: 10.1016/j.ejmech.2020.112403] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 04/17/2020] [Accepted: 04/27/2020] [Indexed: 12/19/2022]
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39
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Nirthanan S. Snake three-finger α-neurotoxins and nicotinic acetylcholine receptors: molecules, mechanisms and medicine. Biochem Pharmacol 2020; 181:114168. [PMID: 32710970 DOI: 10.1016/j.bcp.2020.114168] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/20/2020] [Accepted: 07/20/2020] [Indexed: 12/13/2022]
Abstract
Snake venom three-finger α-neurotoxins (α-3FNTx) act on postsynaptic nicotinic acetylcholine receptors (nAChRs) at the neuromuscular junction (NMJ) to produce skeletal muscle paralysis. The discovery of the archetypal α-bungarotoxin (α-BgTx), almost six decades ago, exponentially expanded our knowledge of membrane receptors and ion channels. This included the localisation, isolation and characterization of the first receptor (nAChR); and by extension, the pathophysiology and pharmacology of neuromuscular transmission and associated pathologies such as myasthenia gravis, as well as our understanding of the role of α-3FNTxs in snakebite envenomation leading to novel concepts of targeted treatment. Subsequent studies on a variety of animal venoms have yielded a plethora of novel toxins that have revolutionized molecular biomedicine and advanced drug discovery from bench to bedside. This review provides an overview of nAChRs and their subtypes, classification of α-3FNTxs and the challenges of typifying an increasing arsenal of structurally and functionally unique toxins, and the three-finger protein (3FP) fold in the context of the uPAR/Ly6/CD59/snake toxin superfamily. The pharmacology of snake α-3FNTxs including their mechanisms of neuromuscular blockade, variations in reversibility of nAChR interactions, specificity for nAChR subtypes or for distinct ligand-binding interfaces within a subtype and the role of α-3FNTxs in neurotoxic envenomation are also detailed. Lastly, a reconciliation of structure-function relationships between α-3FNTx and nAChRs, derived from historical mutational and biochemical studies and emerging atomic level structures of nAChR models in complex with α-3FNTxs is discussed.
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Affiliation(s)
- Selvanayagam Nirthanan
- School of Medical Science, Griffith Health Group, Griffith University, Gold Coast, Queensland, Australia.
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40
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Shigetou S, Shimada S, Makoto I, Matsuda K. Modulation by neonicotinoids of honeybee α1/chicken β2 hybrid nicotinic acetylcholine receptors expressed in Xenopus laevis oocytes. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2020; 166:104545. [PMID: 32448414 DOI: 10.1016/j.pestbp.2020.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 02/05/2020] [Accepted: 02/14/2020] [Indexed: 06/11/2023]
Abstract
Neonicotinoids targeting insect nicotinic acetylcholine (ACh) receptors (insect nAChRs) are used for crop protection, but there is a concern about adverse effects on pollinators such as honeybees (Apis mellifera). Thus, we investigated the agonist actions of neonicotinoids (imidacloprid, thiacloprid and clothianidin) on A. mellifera α1 (Amα1)/chicken β2 hybrid nAChRs in Xenopus laevis oocytes according to the subunit stoichiometry of (Amα1)3(β2)2 and (Amα1)2(β2)3 using voltage-clamp electrophysiology. ACh activated (Amα1)3(β2)2 and (Amα1)2(β2)3 nAChRs with similar current amplitude. We investigated the agonist activity of imidacloprid, thiacloprid and clothianidin for the two hybrid nAChRs and found that: 1) imidacloprid showed higher affinity than clothianidin, whereas clothianidin showed higher efficacy than imidacloprid for the nAChRs; 2) Thiacloprid showed the highest agonist affinity and the lowest efficacy for the nAChRs. The Amα1/β2 subunit ratio influenced the efficacy of imidacloprid and thiacloprid, but hardly affected that of clothianidin. Hydrogen bond formation by the NH group in clothianidin with the main chain carbonyl of the loop B may account, at least in part, for the unique agonist actions of clothianidin on the hybrid nAChRs tested.
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Affiliation(s)
- Sho Shigetou
- Graduate School of Agriculture, Kindai University, Nakamachi, Nara 631-8505, Japan
| | - Shota Shimada
- Graduate School of Agriculture, Kindai University, Nakamachi, Nara 631-8505, Japan
| | - Ihara Makoto
- Graduate School of Agriculture, Kindai University, Nakamachi, Nara 631-8505, Japan
| | - Kazuhiko Matsuda
- Graduate School of Agriculture, Kindai University, Nakamachi, Nara 631-8505, Japan; Agricultural Technology and Innovation Research Institute, Kindai University, Nakamachi, Nara 631-8505, Japan.
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41
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Rahman MM, Teng J, Worrell BT, Noviello CM, Lee M, Karlin A, Stowell MHB, Hibbs RE. Structure of the Native Muscle-type Nicotinic Receptor and Inhibition by Snake Venom Toxins. Neuron 2020; 106:952-962.e5. [PMID: 32275860 DOI: 10.1016/j.neuron.2020.03.012] [Citation(s) in RCA: 121] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/13/2020] [Accepted: 03/15/2020] [Indexed: 12/28/2022]
Abstract
The nicotinic acetylcholine receptor, a pentameric ligand-gated ion channel, converts the free energy of binding of the neurotransmitter acetylcholine into opening of its central pore. Here we present the first high-resolution structure of the receptor type found in muscle-endplate membrane and in the muscle-derived electric tissues of fish. The native receptor was purified from Torpedo electric tissue and functionally reconstituted in lipids optimal for cryo-electron microscopy. The receptor was stabilized in a closed state by the binding of α-bungarotoxin. The structure reveals the binding of a toxin molecule at each of two subunit interfaces in a manner that would block the binding of acetylcholine. It also reveals a closed gate in the ion-conducting pore, formed by hydrophobic amino acid side chains, located ∼60 Å from the toxin binding sites. The structure provides a framework for understanding gating in ligand-gated channels and how mutations in the acetylcholine receptor cause congenital myasthenic syndromes.
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Affiliation(s)
- Md Mahfuzur Rahman
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jinfeng Teng
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Brady T Worrell
- Department of Molecular, Cellular & Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Colleen M Noviello
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Myeongseon Lee
- Department of Molecular, Cellular & Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Arthur Karlin
- Center for Molecular Recognition & Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Michael H B Stowell
- Department of Molecular, Cellular & Developmental Biology, University of Colorado, Boulder, CO 80309, USA.
| | - Ryan E Hibbs
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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42
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Progress in nicotinic receptor structural biology. Neuropharmacology 2020; 171:108086. [PMID: 32272141 DOI: 10.1016/j.neuropharm.2020.108086] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 03/31/2020] [Indexed: 02/07/2023]
Abstract
Here we begin by briefly reviewing landmark structural studies on the nicotinic acetylcholine receptor. We highlight challenges that had to be overcome to push through resolution barriers, then focus on what has been gleaned in the past few years from crystallographic and single particle cryo-EM studies of different nicotinic receptor subunit assemblies and ligand complexes. We discuss insights into ligand recognition, ion permeation, and allosteric gating. We then highlight some foundational aspects of nicotinic receptor structural biology that remain unresolved and are areas ripe for future exploration. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.
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43
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Amend N, Niessen KV, Seeger T, Wille T, Worek F, Thiermann H. Diagnostics and treatment of nerve agent poisoning—current status and future developments. Ann N Y Acad Sci 2020; 1479:13-28. [DOI: 10.1111/nyas.14336] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/25/2020] [Accepted: 03/05/2020] [Indexed: 12/20/2022]
Affiliation(s)
- Niko Amend
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
| | - Karin V. Niessen
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
| | - Timo Wille
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
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44
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Yokoyama Y, Terada T, Shimizu K, Nishikawa K, Kozai D, Shimada A, Mizoguchi A, Fujiyoshi Y, Tani K. Development of a deep learning-based method to identify "good" regions of a cryo-electron microscopy grid. Biophys Rev 2020; 12:349-354. [PMID: 32162215 DOI: 10.1007/s12551-020-00669-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 02/26/2020] [Indexed: 02/05/2023] Open
Abstract
Recent advances in cryo-electron microscopy (cryo-EM) have enabled protein structure determination at atomic resolutions. Cryo-EM specimens are prepared by rapidly freezing a protein solution on a metal grid coated with a holey carbon film; this results in the formation of an ice film on each hole. The thickness of the ice film is a critical factor for high-resolution structure determination; ice that is too thick degrades the contrast of the protein image while ice that is too thin excludes the protein from the hole or denatures the protein. Therefore, trained researchers need to manually select "good" regions with appropriate ice thicknesses for imaging. To reduce the time spent on such tasks, we developed a deep learning program consisting of a "detector" and a "classifier" to identify good regions from low-magnification EM images. In our method, the holes in a low-magnification EM image are detected via a detector, and the ice image on each hole is classified as either good or bad via a classifier. The detector detected more than 95% of the holes regardless of the type of samples. The classifier was trained for different types of samples because the appropriate ice thickness varies between sample types. The accuracies of the classifiers were 93.8% for a soluble protein sample (β-galactosidase) and 95.3% for a membrane protein sample (bovine heart cytochrome c oxidase). In addition, we found that a training data set containing ~ 2100 hole images from 300 low-magnification EM images was sufficient to obtain good accuracy, such as higher than 90%. We expect that the throughput of the cryo-EM data collection step will be greatly improved by using our method.
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Affiliation(s)
- Yuichi Yokoyama
- Graduate School of Interdisciplinary Information Studies, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tohru Terada
- Interfaculty Initiative in Information Studies, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. .,Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Kentaro Shimizu
- Interfaculty Initiative in Information Studies, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Kouki Nishikawa
- TMDU Advanced Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.,CeSPIA Inc., 2-1-1, Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan
| | - Daisuke Kozai
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Atsuhiro Shimada
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
| | - Akira Mizoguchi
- Graduate School of Medicine, Mie University, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
| | - Yoshinori Fujiyoshi
- TMDU Advanced Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.,CeSPIA Inc., 2-1-1, Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan
| | - Kazutoshi Tani
- Graduate School of Medicine, Mie University, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
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45
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Reese HR, Shanahan CC, Proulx C, Menegatti S. Peptide science: A "rule model" for new generations of peptidomimetics. Acta Biomater 2020; 102:35-74. [PMID: 31698048 DOI: 10.1016/j.actbio.2019.10.045] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 10/17/2019] [Accepted: 10/30/2019] [Indexed: 02/07/2023]
Abstract
Peptides have been heavily investigated for their biocompatible and bioactive properties. Though a wide array of functionalities can be introduced by varying the amino acid sequence or by structural constraints, properties such as proteolytic stability, catalytic activity, and phase behavior in solution are difficult or impossible to impart upon naturally occurring α-L-peptides. To this end, sequence-controlled peptidomimetics exhibit new folds, morphologies, and chemical modifications that create new structures and functions. The study of these new classes of polymers, especially α-peptoids, has been highly influenced by the analysis, computational, and design techniques developed for peptides. This review examines techniques to determine primary, secondary, and tertiary structure of peptides, and how they have been adapted to investigate peptoid structure. Computational models developed for peptides have been modified to predict the morphologies of peptoids and have increased in accuracy in recent years. The combination of in vitro and in silico techniques have led to secondary and tertiary structure design principles that mirror those for peptides. We then examine several important developments in peptoid applications inspired by peptides such as pharmaceuticals, catalysis, and protein-binding. A brief survey of alternative backbone structures and research investigating these peptidomimetics shows how the advancement of peptide and peptoid science has influenced the growth of numerous fields of study. As peptide, peptoid, and other peptidomimetic studies continue to advance, we will expect to see higher throughput structural analyses, greater computational accuracy and functionality, and wider application space that can improve human health, solve environmental challenges, and meet industrial needs. STATEMENT OF SIGNIFICANCE: Many historical, chemical, and functional relations draw a thread connecting peptides to their recent cognates, the "peptidomimetics". This review presents a comprehensive survey of this field by highlighting the width and relevance of these familial connections. In the first section, we examine the experimental and computational techniques originally developed for peptides and their morphing into a broader analytical and predictive toolbox. The second section presents an excursus of the structures and properties of prominent peptidomimetics, and how the expansion of the chemical and structural diversity has returned new exciting properties. The third section presents an overview of technological applications and new families of peptidomimetics. As the field grows, new compounds emerge with clear potential in medicine and advanced manufacturing.
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46
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Gulsevin A, Papke RL, Horenstein N. In Silico Modeling of the α7 Nicotinic Acetylcholine Receptor: New Pharmacological Challenges Associated with Multiple Modes of Signaling. Mini Rev Med Chem 2020; 20:841-864. [PMID: 32000651 PMCID: PMC8719523 DOI: 10.2174/1389557520666200130105256] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 11/06/2019] [Accepted: 11/07/2019] [Indexed: 12/13/2022]
Abstract
The α7 nicotinic acetylcholine receptor is a homopentameric ion-channel of the Cys-loop superfamily characterized by its low probability of opening, high calcium permeability, and rapid desensitization. The α7 receptor has been targeted for the treatment of the cognitive symptoms of schizophrenia, depression, and Alzheimer's disease, but it is also involved in inflammatory modulation as a part of the cholinergic anti-inflammatory pathway. Despite its functional importance, in silico studies of the α7 receptor cannot produce a general model explaining the structural features of receptor activation, nor predict the mode of action for various ligand classes. Two particular problems in modeling the α7 nAChR are the absence of a high-resolution structure and the presence of five potentially nonequivalent orthosteric ligand binding sites. There is wide variability regarding the templates used for homology modeling, types of ligands investigated, simulation methods, and simulation times. However, a systematic survey focusing on the methodological similarities and differences in modeling α7 has not been done. In this work, we make a critical analysis of the modeling literature of α7 nAChR by comparing the findings of computational studies with each other and with experimental studies under the main topics of structural studies, ligand binding studies, and comparisons with other nAChR. In light of our findings, we also summarize current problems in the field and make suggestions for future studies concerning modeling of the α7 receptor.
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Affiliation(s)
- Alican Gulsevin
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, United States
| | - Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, P.O. Box 100267, Gainesville, FL 32610, United States
| | - Nicole Horenstein
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, United States
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47
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Oliveira ASF, Edsall CJ, Woods CJ, Bates P, Nunez GV, Wonnacott S, Bermudez I, Ciccotti G, Gallagher T, Sessions RB, Mulholland AJ. A General Mechanism for Signal Propagation in the Nicotinic Acetylcholine Receptor Family. J Am Chem Soc 2019; 141:19953-19958. [PMID: 31805762 DOI: 10.1021/jacs.9b09055] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) modulate synaptic activity in the central nervous system. The α7 subtype, in particular, has attracted considerable interest in drug discovery as a target for several conditions, including Alzheimer's disease and schizophrenia. Identifying agonist-induced structural changes underlying nAChR activation is fundamentally important for understanding biological function and rational drug design. Here, extensive equilibrium and nonequilibrium molecular dynamics simulations, enabled by cloud-based high-performance computing, reveal the molecular mechanism by which structural changes induced by agonist unbinding are transmitted within the human α7 nAChR. The simulations reveal the sequence of coupled structural changes involved in driving conformational change responsible for biological function. Comparison with simulations of the α4β2 nAChR subtype identifies features of the dynamical architecture common to both receptors, suggesting a general structural mechanism for signal propagation in this important family of receptors.
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Affiliation(s)
- Ana Sofia F Oliveira
- School of Biochemistry , University of Bristol , Bristol BS8 1DT , United Kingdom
- Centre for Computational Chemistry, School of Chemistry , University of Bristol , Bristol BS8 1TS , United Kingdom
| | - Christopher J Edsall
- Research Software Engineering, Advanced Computing Research Centre , University of Bristol , Bristol BS1 5QD , United Kingdom
| | - Christopher J Woods
- Centre for Computational Chemistry, School of Chemistry , University of Bristol , Bristol BS8 1TS , United Kingdom
- Research Software Engineering, Advanced Computing Research Centre , University of Bristol , Bristol BS1 5QD , United Kingdom
| | - Phil Bates
- Department of Computer Science, Faculty of Engineering , University of Bristol , Bristol BS8 1TR , United Kingdom
- Oracle Corporation, Oracle Cloud Development Centre , Bristol BS2 2JJ , United Kingdom
| | - Gerardo Viedma Nunez
- Oracle Corporation, Oracle Cloud Development Centre , Bristol BS2 2JJ , United Kingdom
| | - Susan Wonnacott
- Department of Biology and Biochemistry , University of Bath , Bath BA2 7AY , United Kingdom
| | - Isabel Bermudez
- Department of Biological and Medical Sciences , Oxford Brookes University , Oxford OX30BP , United Kingdom
| | - Giovanni Ciccotti
- Institute for Applied Computing "Mauro Picone" (IAC), CNR , Via dei Taurini 19 , 00185 Rome , Italy
- School of Physics , University College of Dublin UCD-Belfield , Dublin 4, Ireland
- Università di Roma La Sapienza , Ple. A. Moro 5 , 00185 Roma , Italy
| | - Timothy Gallagher
- Centre for Computational Chemistry, School of Chemistry , University of Bristol , Bristol BS8 1TS , United Kingdom
| | - Richard B Sessions
- School of Biochemistry , University of Bristol , Bristol BS8 1DT , United Kingdom
| | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry , University of Bristol , Bristol BS8 1TS , United Kingdom
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48
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Hoskin JL, Al-Hasan Y, Sabbagh MN. Nicotinic Acetylcholine Receptor Agonists for the Treatment of Alzheimer's Dementia: An Update. Nicotine Tob Res 2019; 21:370-376. [PMID: 30137524 DOI: 10.1093/ntr/nty116] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Accepted: 08/18/2018] [Indexed: 01/08/2023]
Abstract
A significant portion of the clinical phenotype observed in Alzheimer's disease (AD) occurs through nicotinic acetylcholine receptors (nAChRs). Degeneration of cholinergic neurons, combined with aberrant nAChR expression and activation partially through amyloid-beta peptide (Aβ)-nAChR leads to upregulation of pro-inflammatory pathways and subsequently the progressive cognitive decline of AD. Interestingly, the cholinergic anti-inflammatory pathway is also mediated through nAChR particularly α7 nAChR. Thus, agonists of these receptors will likely exert pro-cognitive benefits through multiple mechanisms including stimulating the cholinergic pathway, modulating inflammation, and buffering the effects of amyloid. Despite this promising theoretical use, trials thus far have been complicated by adverse effects or minimal improvement. This review will provide an update on several pharmacological nAChR agonists tested in clinical trials and reasons that further investigation of nAChR agonists is merited. IMPLICATIONS nAChRs have consistently presented a promising theoretical use in the treatment of AD; however, trials thus far have been complicated by adverse effects or minimal improvement. This review will provide an update on several pharmacological nAChR agonists trialed and reasons that further investigation of nAChR agonists is merited.
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Affiliation(s)
| | | | - Marwan Noel Sabbagh
- Barrow Neurological Institute, Phoenix, AZ.,Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV
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Minimal Structural Changes Determine Full and Partial Nicotinic Receptor Agonist Activity for Nicotine Analogues. Molecules 2019; 24:molecules24152684. [PMID: 31344816 PMCID: PMC6695845 DOI: 10.3390/molecules24152684] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/16/2019] [Accepted: 07/22/2019] [Indexed: 11/17/2022] Open
Abstract
Neuronal α4β2 nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels (LGIC) that have been implicated in nicotine addiction, reward, cognition, pain disorders, anxiety, and depression. Nicotine has been widely used as a template for the synthesis of ligands that prefer α4β2 nAChRs subtypes. The most important therapeutic use for α4β2 nAChRs is as replacement therapy for smoking cessation and withdrawal and the most successful therapeutic ligands are partial agonists. In this case, we use the N-methylpyrrolidine moiety of nicotine to design and synthesize new α4β2 nicotinic derivatives, coupling the pyrrolidine moiety to an aromatic group by introducing an ether-bonded functionality. Meta-substituted phenolic derivatives were used for these goals. Radioligand binding assays were performed on clonal cell lines of hα4β2 nAChR and two electrode voltage-clamp experiments were used for functional assays. Molecular docking was performed in the open state of the nAChR in order to rationalize the agonist activity shown by our compounds.
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50
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Oliveira ASF, Shoemark DK, Campello HR, Wonnacott S, Gallagher T, Sessions RB, Mulholland AJ. Identification of the Initial Steps in Signal Transduction in the α4β2 Nicotinic Receptor: Insights from Equilibrium and Nonequilibrium Simulations. Structure 2019; 27:1171-1183.e3. [PMID: 31130483 DOI: 10.1016/j.str.2019.04.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/28/2019] [Accepted: 04/10/2019] [Indexed: 02/02/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) modulate synaptic transmission in the nervous system. These receptors have emerged as therapeutic targets in drug discovery for treating several conditions, including Alzheimer's disease, pain, and nicotine addiction. In this in silico study, we use a combination of equilibrium and nonequilibrium molecular dynamics simulations to map dynamic and structural changes induced by nicotine in the human α4β2 nAChR. They reveal a striking pattern of communication between the extracellular binding pockets and the transmembrane domains (TMDs) and show the sequence of conformational changes associated with the initial steps in this process. We propose a general mechanism for signal transduction for Cys-loop receptors: the mechanistic steps for communication proceed firstly through loop C in the principal subunit, and are subsequently transmitted, gradually and cumulatively, to loop F of the complementary subunit, and then to the TMDs through the M2-M3 linker.
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Affiliation(s)
- A Sofia F Oliveira
- School of Biochemistry, University of Bristol, Bristol BS8 1DT, UK; Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | | | - Hugo Rego Campello
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | - Susan Wonnacott
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Timothy Gallagher
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | | | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
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