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Choudhary S, Kashyap SS, Martin RJ, Robertson AP. Advances in our understanding of nematode ion channels as potential anthelmintic targets. Int J Parasitol Drugs Drug Resist 2022; 18:52-86. [PMID: 35149380 PMCID: PMC8841521 DOI: 10.1016/j.ijpddr.2021.12.001] [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: 06/18/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 12/15/2022]
Abstract
Ion channels are specialized multimeric proteins that underlie cell excitability. These channels integrate with a variety of neuromuscular and biological functions. In nematodes, the physiological behaviors including locomotion, navigation, feeding and reproduction, are regulated by these protein entities. Majority of the antinematodal chemotherapeutics target the ion channels to disrupt essential biological functions. Here, we have summarized current advances in our understanding of nematode ion channel pharmacology. We review cys-loop ligand gated ion channels (LGICs), including nicotinic acetylcholine receptors (nAChRs), acetylcholine-chloride gated ion channels (ACCs), glutamate-gated chloride channels (GluCls), and GABA (γ-aminobutyric acid) receptors, and other ionotropic receptors (transient receptor potential (TRP) channels and potassium ion channels). We have provided an update on the pharmacological properties of these channels from various nematodes. This article catalogs the differences in ion channel composition and resulting pharmacology in the phylum Nematoda. This diversity in ion channel subunit repertoire and pharmacology emphasizes the importance of pursuing species-specific drug target research. In this review, we have provided an overview of recent advances in techniques and functional assays available for screening ion channel properties and their application.
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Affiliation(s)
- Shivani Choudhary
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA
| | - Sudhanva S Kashyap
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA
| | - Richard J Martin
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA
| | - Alan P Robertson
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
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2
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Becerra-Amezcua MP, Hernández-Sámano AC, Puch-Hau C, Aguilar MB, Collí-Dulá RC. Effect of pterois volitans (lionfish) venom on cholinergic and dopaminergic systems. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2020; 77:103359. [PMID: 32146351 DOI: 10.1016/j.etap.2020.103359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 02/27/2020] [Accepted: 02/29/2020] [Indexed: 06/10/2023]
Abstract
Pterois volitans venom induces muscular fibrillation, which results from nerve transmission caused by the presence of acetylcholine (ACh). It also has cardiovascular effects that are due to its actions on muscarinic and nicotinic cholinergic receptors. In this study, we characterized the effects of P. volitans venom on nicotinic acetylcholine receptors (nAChRs) and dopaminergic neurons. After exposure to P. volitans venom, acetylcholinesterase (AChE) mRNA levels and the expression of the α2 subunit of nAChR increased in zebrafish embryos (15-20 somites). In addition, the lionfish venom blocked zebrafish α2 nAChR subunit functional expression and the ACh-induced response of human neuronal α3β2 receptors. The latter receptor was blocked by a protein fraction named F2, which was isolated from P. volitans venom using reversed phase high performance liquid chromatography (RP-HPLC). This venom causes death in dopaminergic neurons, and affects the cholinergic system. The effect of these two systems may result in retarded embryonic development of zebrafish, since the two systems function in a related manner to control growth hormone secretion.
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Affiliation(s)
- Mayra P Becerra-Amezcua
- Laboratorio de Biotecnología y Toxicología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Mérida, Departamento de Recursos del Mar, Km. 6 Antigua Carretera a Progreso, Cordemex, 97310 Mérida, Yucatán, Mexico.
| | - Arisaí C Hernández-Sámano
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, 76230, Mexico
| | - Carlos Puch-Hau
- Laboratorio de Biotecnología y Toxicología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Mérida, Departamento de Recursos del Mar, Km. 6 Antigua Carretera a Progreso, Cordemex, 97310 Mérida, Yucatán, Mexico
| | - Manuel B Aguilar
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, 76230, Mexico
| | - Reyna C Collí-Dulá
- Laboratorio de Biotecnología y Toxicología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Mérida, Departamento de Recursos del Mar, Km. 6 Antigua Carretera a Progreso, Cordemex, 97310 Mérida, Yucatán, Mexico; Consejo Nacional de Ciencia y Tecnología (CONACyT), Mexico
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3
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Gao H, Wang S, Qi Y, He G, Qiang B, Wang S, Zhang H. Synthesis and biological evaluation of 9-fluorenone derivatives for SPECT imaging of α7-nicotinic acetylcholine receptor. Bioorg Med Chem Lett 2019; 29:126724. [PMID: 31624040 DOI: 10.1016/j.bmcl.2019.126724] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 09/22/2019] [Accepted: 09/28/2019] [Indexed: 11/29/2022]
Abstract
The α7-nicotinic acetylcholine receptor (α7-nAChR) subtype, is found to have a connection with the pathogenesis of a variety of psychiatric and neurological disorders. Herein, we report the development of radioiodinated 9-fluorenone derivatives as single-photon emission computed tomography (SPECT) imaging tracers for α7-nAChRs. Among the derivatives, the best member of the series 10 (Ki = 2.23 nM) were radiolabeled with 125I for in vitro and in vivo studies. The radiotracer [125I]10 exhibited robust brain uptake and specifically labeled α7-nAChRs with a peak uptake value of 9.49 ± 0.87%ID/g in brain. Blocking studies demonstrated that the tracer was highly specific toward α7-nAChR. Furthermore, ex vivo autoradiography and micro-SPECT/CT dynamic imaging in mice confirmed the excellent imaging properties. In addition, molecular docking was also performed to rationalize the potency of the chosen compounds towards α7-nAChRs. To conclude, compound 10 could serve as a promising radiotracer for the α7-nAChRs.
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Affiliation(s)
- Hang Gao
- Key Laboratory of Radiopharmaceuticals of Ministry of Education, College of Chemistry, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China.
| | - Shuxia Wang
- Key Laboratory of Radiopharmaceuticals of Ministry of Education, College of Chemistry, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China
| | - Yueheng Qi
- Key Laboratory of Radiopharmaceuticals of Ministry of Education, College of Chemistry, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China
| | - Guoxue He
- Key Laboratory of Radiopharmaceuticals of Ministry of Education, College of Chemistry, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China
| | - Bingchao Qiang
- Key Laboratory of Radiopharmaceuticals of Ministry of Education, College of Chemistry, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China
| | - Sixuan Wang
- Key Laboratory of Radiopharmaceuticals of Ministry of Education, College of Chemistry, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China
| | - Huabei Zhang
- Key Laboratory of Radiopharmaceuticals of Ministry of Education, College of Chemistry, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China.
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Liu W, Su K. A Review on the Receptor-ligand Molecular Interactions in the Nicotinic Receptor Signaling Systems. Pak J Biol Sci 2019; 21:51-66. [PMID: 30221881 DOI: 10.3923/pjbs.2018.51.66] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Nicotine is regarded as the main active addictive ingredient in tobacco products driving continued tobacco abuse behavior (smoking) to the addiction behavior, whereas nicotinic acetylcholine receptors (nAChR) is the crucial effective apparatus or molecular effector of nicotine and acetylcholine and other similar ligands. Many nAChR subunits have been revealed to bind to either neurotransmitters or exogenous ligands, such as nicotine and acetylcholine, being involved in the nicotinic receptor signal transduction. Therefore, the nicotinic receptor signalling molecules and the receptor-ligand molecular interactions between nAChRs and their ligands are universally regarded as crucial mediators of cellular functions and drug targets in medical treatment and clinical diagnosis. Given numerous endeavours have been made in defining the roles of nAChRs in response to nicotine and other addictive drugs, this review focuses on studies and reports in recent years on the receptor-ligand interactions between nAChR receptors and ligands, including lipid-nAChR and protein-nAChR molecular interactions, relevant signal transduction pathways and their molecular mechanisms in the nicotinic receptor signalling systems. All the references were carefully retrieved from the PubMed database by searching key words "nicotine", "acetylcholine", "nicotinic acetylcholine receptor(s)", "nAChR*", "protein and nAChR", "lipid and nAChR", "smok*" and "tobacco". All the relevant referred papers and reports retrieved were fully reviewed for manual inspection. This effort intend to get a quick insight and understanding of the nicotinic receptor signalling and their molecular interactions mechanisms. Understanding the cellular receptor-ligand interactions and molecular mechanisms between nAChRs and ligands will lead to a better translational and therapeutic operations and outcomes for the prevention and treatment of nicotine addiction and other chronic drug addictions in the brain's reward circuitry.
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Patočka J, Kuča K, Jun D. Acetylcholinesterase and Butyrylcholinesterase – Important Enzymes of Human Body. ACTA MEDICA (HRADEC KRÁLOVÉ) 2018. [DOI: 10.14712/18059694.2018.95] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The serine hydrolases and proteases are a ubiquitous group of enzymes that is fundamental to many critical lifefunctions. Human tissues have two distinct cholinesterase activities: acetylcholinesterase and butyrylcholinesterase. Acetylcholinesterase functions in the transmission of nerve impulses, whereas the physiological function of butyrylcholinesterase remains unknown. Acetylcholinesterase is one of the crucial enzymes in the central and peripheral nerve system. Organophosphates and carbamates are potent inhibitors of serine hydrolases and well suited probes for investigating the chemical reaction mechanism of the inhibition. Understanding the enzyme’s chemistry is essential in preventing and/or treating organophosphate and carbamate poisoning as well as designing new medicaments for cholinergic-related diseases like as Alzheimer’s disease.
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Kaur J, Rauti R, Nistri A. Nicotine‐mediated neuroprotection of rat spinal networks against excitotoxicity. Eur J Neurosci 2018; 47:1353-1374. [DOI: 10.1111/ejn.13950] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 03/19/2018] [Accepted: 04/10/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Jaspreet Kaur
- Department of NeuroscienceInternational School for Advanced Studies (SISSA) Trieste Italy
- Jaspreet Kaur, Institute of Neurosciences of Timone (IMAPATH Team) ‐ CERIMEDUMR 7289Aix‐Marseille University 27, boulevard Jean Moulin Marseille Cedex 05 13385 France
| | - Rossana Rauti
- Department of NeuroscienceInternational School for Advanced Studies (SISSA) Trieste Italy
| | - Andrea Nistri
- Department of NeuroscienceInternational School for Advanced Studies (SISSA) Trieste Italy
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de la Rosa G, Corrales-García LL, Rodriguez-Ruiz X, López-Vera E, Corzo G. Short-chain consensus alpha-neurotoxin: a synthetic 60-mer peptide with generic traits and enhanced immunogenic properties. Amino Acids 2018; 50:885-895. [PMID: 29626299 DOI: 10.1007/s00726-018-2556-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 03/13/2018] [Indexed: 10/17/2022]
Abstract
The three-fingered toxin family and more precisely short-chain α-neurotoxins (also known as Type I α-neurotoxins) are crucial in defining the elapid envenomation process, but paradoxically, they are barely neutralized by current elapid snake antivenoms. This work has been focused on the primary structural identity among Type I neurotoxins in order to create a consensus short-chain α-neurotoxin with conserved characteristics. A multiple sequence alignment considering the twelve most toxic short-chain α-neurotoxins reported from the venoms of the elapid genera Acanthophis, Oxyuranus, Walterinnesia, Naja, Dendroaspis and Micrurus led us to propose a short-chain consensus α-neurotoxin, here named ScNtx. The synthetic ScNtx gene was de novo constructed and cloned into the expression vector pQE30 containing a 6His-Tag and an FXa proteolytic cleavage region. Escherichia coli Origami cells transfected with the pQE30/ScNtx vector expressed the recombinant consensus neurotoxin in a soluble form with a yield of 1.5 mg/L of culture medium. The 60-amino acid residue ScNtx contains canonical structural motifs similar to α-neurotoxins from African elapids and its LD50 of 3.8 µg/mice is similar to the most toxic short-chain α-neurotoxins reported from elapid venoms. Furthermore, ScNtx was also able to antagonize muscular, but not neuronal, nicotinic acetylcholine receptors (nAChR). Rabbits immunized with ScNtx were able to immune-recognize short-chain α-neurotoxins within whole elapid venoms. Type I neurotoxins are difficult to isolate and purify from natural sources; therefore, the heterologous expression of molecules such ScNtx, bearing crucial motifs and key amino acids, is a step forward to create common immunogens for developing cost-effective antivenoms with a wider spectrum of efficacy, quality and strong therapeutic value.
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Affiliation(s)
- Guillermo de la Rosa
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, UNAM, Apartado Postal 510-3, 61500, Cuernavaca, Morelos, Mexico
| | - Ligia L Corrales-García
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, UNAM, Apartado Postal 510-3, 61500, Cuernavaca, Morelos, Mexico.,Departamento de Alimentos, Facultad de Ciencias Farmacéuticas y Alimentarias, Universidad de Antioquia, AA 1226, Medellín, Colombia
| | - Ximena Rodriguez-Ruiz
- Instituto de Ciencias del Mar y Limnología/Posgrado en Ciencias del Mar y Limnologia, Universidad Nacional Autónoma de México, UNAM, Circuito exterior s/n, Ciudad Universitaria, 04510, Mexico City, Mexico
| | - Estuardo López-Vera
- Instituto de Ciencias del Mar y Limnología/Posgrado en Ciencias del Mar y Limnologia, Universidad Nacional Autónoma de México, UNAM, Circuito exterior s/n, Ciudad Universitaria, 04510, Mexico City, Mexico
| | - Gerardo Corzo
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, UNAM, Apartado Postal 510-3, 61500, Cuernavaca, Morelos, Mexico. .,Institute of Biotechnology-UNAM, Av. Universidad 2001, 62210, Cuernavaca, Morelos, Mexico.
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8
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Boffi JC, Marcovich I, Gill-Thind JK, Corradi J, Collins T, Lipovsek MM, Moglie M, Plazas PV, Craig PO, Millar NS, Bouzat C, Elgoyhen AB. Differential Contribution of Subunit Interfaces to α9α10 Nicotinic Acetylcholine Receptor Function. Mol Pharmacol 2017; 91:250-262. [PMID: 28069778 PMCID: PMC5325082 DOI: 10.1124/mol.116.107482] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 01/04/2017] [Indexed: 12/31/2022] Open
Abstract
Nicotinic acetylcholine receptors can be assembled from either homomeric or heteromeric pentameric subunit combinations. At the interface of the extracellular domains of adjacent subunits lies the acetylcholine binding site, composed of a principal component provided by one subunit and a complementary component of the adjacent subunit. Compared with neuronal nicotinic acetylcholine cholinergic receptors (nAChRs) assembled from α and β subunits, the α9α10 receptor is an atypical member of the family. It is a heteromeric receptor composed only of α subunits. Whereas mammalian α9 subunits can form functional homomeric α9 receptors, α10 subunits do not generate functional channels when expressed heterologously. Hence, it has been proposed that α10 might serve as a structural subunit, much like a β subunit of heteromeric nAChRs, providing only complementary components to the agonist binding site. Here, we have made use of site-directed mutagenesis to examine the contribution of subunit interface domains to α9α10 receptors by a combination of electrophysiological and radioligand binding studies. Characterization of receptors containing Y190T mutations revealed unexpectedly that both α9 and α10 subunits equally contribute to the principal components of the α9α10 nAChR. In addition, we have shown that the introduction of a W55T mutation impairs receptor binding and function in the rat α9 subunit but not in the α10 subunit, indicating that the contribution of α9 and α10 subunits to complementary components of the ligand-binding site is nonequivalent. We conclude that this asymmetry, which is supported by molecular docking studies, results from adaptive amino acid changes acquired only during the evolution of mammalian α10 subunits.
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Affiliation(s)
- Juan Carlos Boffi
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Irina Marcovich
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - JasKiran K Gill-Thind
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Jeremías Corradi
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Toby Collins
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - María Marcela Lipovsek
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Marcelo Moglie
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Paola V Plazas
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Patricio O Craig
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Neil S Millar
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Cecilia Bouzat
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Ana Belén Elgoyhen
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B).
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9
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Suresh A, Hung A. Molecular simulation study of the unbinding of α-conotoxin [ϒ4E]GID at the α7 and α4β2 neuronal nicotinic acetylcholine receptors. J Mol Graph Model 2016; 70:109-121. [PMID: 27721068 DOI: 10.1016/j.jmgm.2016.09.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 08/11/2016] [Accepted: 09/05/2016] [Indexed: 12/27/2022]
Abstract
The α7 and α4β2 neuronal nicotinic receptors belonging to the family of ligand-gated ion channels are most prevalent in the brain, and are implicated in various neurodegenerative disorders. α-conotoxin GID (and its analogue [ϒ4E]GID) specifically inhibits these subtypes, with more affinity towards the human α7 (hα7) subtype, and is valuable in understanding the physiological roles of these receptors. In this study, we use umbrella-sampling molecular dynamics simulations to understand the mechanism of interaction between [ϒ4E]GID and the agonist binding pockets of the α4β2 and the hα7 receptors, and to estimate their relative binding affinities (ΔGbind). The obtained ΔGbind values indicate stronger interaction with the hα7 receptor, in agreement with previous experimental studies. Simulations also revealed different unbinding pathways between the two receptor subtypes, enabling identification of a number of interactions at locations far from the orthosteric binding site which may explain the difference in [ϒ4E]GID potency. The pathways identified will help in the design of novel conotoxins with increased potency at α4β2, for which there is currently no known highly potent conotoxin inhibitor. Computational mutational free energy analyses also revealed a number of possible single-site mutations to GID which might enhance its selective binding to α4β2 over α7.
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Affiliation(s)
- Abishek Suresh
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia
| | - Andrew Hung
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia.
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10
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Attwood MM, Krishnan A, Pivotti V, Yazdi S, Almén MS, Schiöth HB. Topology based identification and comprehensive classification of four-transmembrane helix containing proteins (4TMs) in the human genome. BMC Genomics 2016; 17:268. [PMID: 27030248 PMCID: PMC4815072 DOI: 10.1186/s12864-016-2592-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 03/16/2016] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Membrane proteins are key components in a large spectrum of diverse functions and thus account for the major proportion of the drug-targeted portion of the genome. From a structural perspective, the α-helical transmembrane proteins can be categorized into major groups based on the number of transmembrane helices and these groups are often associated with specific functions. When compared to the well-characterized seven-transmembrane containing proteins (7TM), other TM groups are less explored and in particular the 4TM group. In this study, we identify the complete 4TM complement from the latest release of the human genome and assess the 4TM structure group as a whole. We functionally characterize this dataset and evaluate the resulting groups and ubiquitous functions, and furthermore describe disease and drug target involvement. RESULTS We classified 373 proteins, which represents ~7 % of the human membrane proteome, and includes 69 more proteins than our previous estimate. We have characterized the 4TM dataset based on functional, structural, and/or evolutionary similarities. Proteins that are involved in transport activity constitute 37 % of the dataset, 23 % are receptor-related, and 13 % have enzymatic functions. Intriguingly, proteins involved in transport are more than double the 15 % of transporters in the entire human membrane proteome, which might suggest that the 4TM topological architecture is more favored for transporting molecules over other functions. Moreover, we found an interesting exception to the ubiquitous intracellular N- and C-termini localization that is found throughout the entire membrane proteome and 4TM dataset in the neurotransmitter gated ion channel families. Overall, we estimate that 58 % of the dataset has a known association to disease conditions with 19 % of the genes possibly involved in different types of cancer. CONCLUSIONS We provide here the most robust and updated classification of the 4TM complement of the human genome as a platform to further understand the characteristics of 4TM functions and to explore pharmacological opportunities.
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Affiliation(s)
- Misty M. Attwood
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Arunkumar Krishnan
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Valentina Pivotti
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Samira Yazdi
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Markus Sällman Almén
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Helgi B. Schiöth
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
- />Institutionen för neurovetenskap, BMC, Box 593, 751 24 Uppsala, Sweden
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11
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Ihara M, Sattelle DB, Matsuda K. Probing new components (loop G and the α-α interface) of neonicotinoid binding sites on nicotinic acetylcholine receptors. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2015; 121:47-52. [PMID: 26047111 DOI: 10.1016/j.pestbp.2015.02.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 02/25/2015] [Accepted: 02/25/2015] [Indexed: 06/04/2023]
Abstract
Neonicotinoid insecticides interact with the orthosteric site on the extracellular ligand binding domain (LBD) of nicotinic acetylcholine receptors (nAChRs), typically activating the cation permeable ion channels. In nAChRs consisting of two α and three non-α subunits, LBDs contain six loops (loops A, B and C on the α subunit and loops D, E and F on the non-α subunit) which make up the orthosteric binding site at the α/non-α subunit interfaces. Recently, an additional site (loop G) on the β1 strand has been identified. Also, when the α/non-α subunit ratio is 3/2, another binding site is generated at the interface of two adjacent α subunits. Roles for loop G and the α-α interface in the interactions with neonicotinoids are discussed with reference to recent structural and physiological data.
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Affiliation(s)
- Makoto Ihara
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan.
| | - David B Sattelle
- The Wolfson Institute for Biomedical Research, Department of Medicine, University College London, Cruciform Building, Gower Street, London, WC1E 6BT, UK
| | - Kazuhiko Matsuda
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan.
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12
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Biomolecular recognition of antagonists by α7 nicotinic acetylcholine receptor: Antagonistic mechanism and structure-activity relationships studies. Eur J Pharm Sci 2015; 76:119-32. [PMID: 25963024 DOI: 10.1016/j.ejps.2015.05.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 04/24/2015] [Accepted: 05/06/2015] [Indexed: 12/20/2022]
Abstract
As the key constituent of ligand-gated ion channels in the central nervous system, nicotinic acetylcholine receptors (nAChRs) and neurodegenerative diseases are strongly coupled in the human species. In recently years the developments of selective agonists by using nAChRs as the drug target have made a large progress, but the studies of selective antagonists are severely lacked. Currently these antagonists rest mainly on the extraction of partly natural products from some animals and plants; however, the production of these crude substances is quite restricted, and artificial synthesis of nAChR antagonists is still one of the completely new research fields. In the context of this manuscript, our primary objective was to comprehensively analyze the recognition patterns and the critical interaction descriptors between target α7 nAChR and a series of the novel compounds with potentially antagonistic activity by means of virtual screening, molecular docking and molecular dynamics simulation, and meanwhile these recognition reactions were also compared with the biointeraction of α7 nAChR with a commercially natural antagonist - methyllycaconitine. The results suggested clearly that there are relatively obvious differences of molecular structures between synthetic antagonists and methyllycaconitine, while the two systems have similar recognition modes on the whole. The interaction energy and the crucially noncovalent forces of the α7 nAChR-antagonists are ascertained according to the method of Molecular Mechanics/Generalized Born Surface Area. Several amino acid residues, such as B/Tyr-93, B/Lys-143, B/Trp-147, B/Tyr-188, B/Tyr-195, A/Trp-55 and A/Leu-118 played a major role in the α7 nAChR-antagonist recognition processes, in particular, residues B/Tyr-93, B/Trp-147 and B/Tyr-188 are the most important. These outcomes tally satisfactorily with the discussions of amino acid mutations. Based on the explorations of three-dimensional quantitative structure-activity relationships, the structure-antagonistic activity relationships of antagonists and the characteristics of α7 nAChR-ligand recognitions were received a reasonable summary as well. These attempts emerged herein would not only provide helpful guidance for the design of α7 nAChR antagonists, but shed new light on the subsequent researches in antagonistic mechanism.
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13
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Jozwiak K, Targowska-Duda KM, Kaczor AA, Kozak J, Ligeza A, Szacon E, Wrobel TM, Budzynska B, Biala G, Fornal E, Poso A, Wainer IW, Matosiuk D. Synthesis, in vitro and in vivo studies, and molecular modeling of N-alkylated dextromethorphan derivatives as non-competitive inhibitors of α3β4 nicotinic acetylcholine receptor. Bioorg Med Chem 2014; 22:6846-56. [PMID: 25464883 DOI: 10.1016/j.bmc.2014.10.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 10/03/2014] [Accepted: 10/24/2014] [Indexed: 11/26/2022]
Abstract
9 N-alkylated derivatives of dextromethorphan are synthesized and studied as non-competitive inhibitors of α3β4 nicotinic acetylcholine receptors (nAChRs). In vitro activity towards α3β4 nicotinic acetylcholine receptor is determined using a patch-clamp technique and is in the micromolar range. Homology modeling, molecular docking and molecular dynamics of ligand-receptor complexes in POPC membrane are used to find the mode of interactions of N-alkylated dextromethorphan derivatives with α3β4 nAChR. The compounds, similarly as dextromethorphan, interact with the middle portion of α3β4 nAChR ion channel. Finally, behavioral tests confirmed potential application of the studied compounds for the treatment of addiction.
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Affiliation(s)
- Krzysztof Jozwiak
- Department of Chemistry, Laboratory of Medicinal Chemistry and Neuroengineering, Medical University of Lublin, 4a Chodzki St., PL-20093 Lublin, Poland
| | - Katarzyna M Targowska-Duda
- Department of Chemistry, Laboratory of Medicinal Chemistry and Neuroengineering, Medical University of Lublin, 4a Chodzki St., PL-20093 Lublin, Poland
| | - Agnieszka A Kaczor
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modeling Lab, Faculty of Pharmacy with Division of Medical Analytics, 4a Chodzki St., PL-20093 Lublin, Poland; School of Pharmacy, University of Eastern Finland, Yliopistonranta 1, PO Box 1627, FI-70211 Kuopio, Finland
| | - Joanna Kozak
- Department of Chemistry, Laboratory of Medicinal Chemistry and Neuroengineering, Medical University of Lublin, 4a Chodzki St., PL-20093 Lublin, Poland; Department of Anatomy, Medical University of Lublin, 4 Jaczewskiego St., PL-20090 Lublin, Poland
| | - Agnieszka Ligeza
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modeling Lab, Faculty of Pharmacy with Division of Medical Analytics, 4a Chodzki St., PL-20093 Lublin, Poland
| | - Elzbieta Szacon
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modeling Lab, Faculty of Pharmacy with Division of Medical Analytics, 4a Chodzki St., PL-20093 Lublin, Poland
| | - Tomasz M Wrobel
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modeling Lab, Faculty of Pharmacy with Division of Medical Analytics, 4a Chodzki St., PL-20093 Lublin, Poland
| | - Barbara Budzynska
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, 4a Chodzki St., PL-20093 Lublin, Poland
| | - Grazyna Biala
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, 4a Chodzki St., PL-20093 Lublin, Poland
| | - Emilia Fornal
- Department of Chemistry, Catholic University of Lublin, al. Krasnicka 102, PL-20718 Lublin, Poland
| | - Antti Poso
- School of Pharmacy, University of Eastern Finland, Yliopistonranta 1, PO Box 1627, FI-70211 Kuopio, Finland
| | - Irving W Wainer
- Laboratory of Clinical Investigation, Division of Intramural Research Programs, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Dariusz Matosiuk
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modeling Lab, Faculty of Pharmacy with Division of Medical Analytics, 4a Chodzki St., PL-20093 Lublin, Poland.
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14
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Paramo T, East A, Garzón D, Ulmschneider MB, Bond PJ. Efficient Characterization of Protein Cavities within Molecular Simulation Trajectories: trj_cavity. J Chem Theory Comput 2014; 10:2151-64. [DOI: 10.1021/ct401098b] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Teresa Paramo
- Unilever
Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Alexandra East
- Unilever
Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Diana Garzón
- Unilever
Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Martin B. Ulmschneider
- Department
of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Peter J. Bond
- Unilever
Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
- Bioinformatics Institute (A*STAR), 30
Biopolis Str, #07-01 Matrix, Singapore 138671
- Department
of Biological Sciences, National University of Singapore, 14 Science
Drive 4, 117543 Singapore
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15
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Sambasivarao SV, Roberts J, Bharadwaj VS, Slingsby JG, Rohleder C, Mallory C, Groome JR, McDougal OM, Maupin CM. Acetylcholine promotes binding of α-conotoxin MII at α3 β2 nicotinic acetylcholine receptors. Chembiochem 2014; 15:413-24. [PMID: 24420650 DOI: 10.1002/cbic.201300577] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Indexed: 11/09/2022]
Abstract
α-Conotoxin MII (α-CTxMII) is a 16-residue peptide with the sequence GCCSNPVCHLEHSNLC, containing Cys2-Cys8 and Cys3-Cys16 disulfide bonds. This peptide, isolated from the venom of the marine cone snail Conus magus, is a potent and selective antagonist of neuronal nicotinic acetylcholine receptors (nAChRs). To evaluate the impact of channel-ligand interactions on ligand-binding affinity, homology models of the heteropentameric α3β2-nAChR were constructed. The models were created in MODELLER with the aid of experimentally characterized structures of the Torpedo marmorata-nAChR (Tm-nAChR, PDB ID: 2BG9) and the Aplysia californica-acetylcholine binding protein (Ac-AChBP, PDB ID: 2BR8) as templates for the α3- and β2-subunit isoforms derived from rat neuronal nAChR primary amino acid sequences. Molecular docking calculations were performed with AutoDock to evaluate interactions of the heteropentameric nAChR homology models with the ligands acetylcholine (ACh) and α-CTxMII. The nAChR homology models described here bind ACh with binding energies commensurate with those of previously reported systems, and identify critical interactions that facilitate both ACh and α-CTxMII ligand binding. The docking calculations revealed an increased binding affinity of the α3β2-nAChR for α-CTxMII with ACh bound to the receptor, and this was confirmed through two-electrode voltage clamp experiments on oocytes from Xenopus laevis. These findings provide insights into the inhibition and mechanism of electrostatically driven antagonist properties of the α-CTxMIIs on nAChRs.
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Affiliation(s)
- Somisetti V Sambasivarao
- Chemical and Biological Engineering Department, Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401 (USA)
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16
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Kichko TI, Lennerz J, Eberhardt M, Babes RM, Neuhuber W, Kobal G, Reeh PW. Bimodal concentration-response of nicotine involves the nicotinic acetylcholine receptor, transient receptor potential vanilloid type 1, and transient receptor potential ankyrin 1 channels in mouse trachea and sensory neurons. J Pharmacol Exp Ther 2013; 347:529-39. [PMID: 23926288 DOI: 10.1124/jpet.113.205971] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
High concentrations of nicotine, as in the saliva of oral tobacco consumers or in smoking cessation aids, have been shown to sensitize/activate recombinant transient receptor potential vanilloid type 1 (rTRPV1) and mouse TRPA1 (mTRPA1) channels. By measuring stimulated calcitonin gene-related peptide (CGRP) release from the isolated mouse trachea, we established a bimodal concentration-response relationship with a threshold below 10 µM (-)-nicotine, a maximum at 100 µM, an apparent nadir between 0.5 and 10 mM, and a renewed increase at 20 mM. The first peak was unchanged in TRPV1/A1 double-null mutants as compared with wild-types and was abolished by specific nicotinic acetylcholine receptor (nAChR) inhibitors and by camphor, discovered to act as nicotinic antagonist. The nicotine response at 20 mM was strongly pHe-dependent, - five times greater at pH 9.0 than 7.4, indicating that intracellular permeation of the (uncharged) alkaloid was required to reach the TRPV1/A1 binding sites. The response was strongly reduced in both null mutants, and more so in double-null mutants. Upon measuring calcium transients in nodose/jugular and dorsal root ganglion neurons in response to 100 µM nicotine, 48% of the vagal (but only 14% of the somatic) sensory neurons were activated, the latter very weakly. However, nicotine 20 mM at pH 9.0 repeatedly activated almost every single cultured neuron, partly by releasing intracellular calcium and independent of TRPV1/A1 and nAChRs. In conclusion, in mouse tracheal sensory nerves nAChRs are 200-fold more sensitive to nicotine than TRPV1/A1; they are widely coexpressed with the capsaicin receptor among vagal sensory neurons and twice as abundant as TRPA1. Nicotine is the major stimulant in tobacco, and its sensory impact through nAChRs should not be disregarded.
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Affiliation(s)
- Tatjana I Kichko
- Institute of Physiology and Pathophysiology (T.I.K., J.L., M.E., R.M.B., P.W.R.) and Institute of Anatomy I (W.N.), Friedrich-Alexander-University, Erlangen, Germany; Institute of Pathology, University of Ulm, Ulm, Germany (J.L.); Department of Biophysics, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania (R.M.B.); Department of Anesthesiology and Intensive Care, Hannover Medical School, Hannover, Germany (M.E.); and Altria Client Services, Inc., Richmond, Virginia (G.K.)
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17
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Dederer H, Berger M, Meyer T, Werr M, Ilg T. Structure-activity relationships of acetylcholine derivatives with Lucilia cuprina nicotinic acetylcholine receptor α1 and α2 subunits in chicken β2 subunit hybrid receptors in comparison with chicken nicotinic acetylcholine receptor α4/β2. INSECT MOLECULAR BIOLOGY 2013; 22:183-198. [PMID: 23331538 DOI: 10.1111/imb.12014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Insect nicotinic acetylcholine (ACh) receptors (nAChRs) are the targets of several insecticide classes. In the present study, we report the gene identification and cloning of nAChR α1 and α2 subunits (Lcα1 and Lcα2) from the sheep blowfly Lucilia cuprina. Xenopus oocytes voltage clamp experiments as hybrids with the chicken β2 nAChR (Ggβ2) subunit resulted in ACh-gated ion channels with distinct dose-response curves for Lcα1/Ggβ2 (effective concentration 50% [EC50 ] = 80 nM; nH = 1.05), and Lcα2/Ggβ2 (EC50 = 5.37 μM, nH = 1.46). The neonicotinoid imidacloprid was a potent agonist for the α-bungarotoxin-sensitive Lcα1/Ggβ2 (EC50 ∼ 20 nM), while the α-bungarotoxin-resistant Lcα2/Ggβ2 showed a 30-fold lower sensitivity to this insecticide (EC50 = 0.62 μM). Thirteen close derivatives of ACh were analysed in EC50 , Hill coefficient and maximum current (relative to ACh) determinations for Lcα1/Ggβ2 and Lcα2/Ggβ2 and the chicken Ggα4/Ggβ2 nAChRs, and comparisons relative to ACh allowed the definition of novel structure-activity and structure-selectivity relationships. In the case of N-ethyl-acetylcholine, the EC50 of the chicken Ggα4/Ggβ2 rose by a factor of 1000, while for both Lcα1/Ggβ2 and Lcα2/Ggβ2, potency remained unchanged. Further derivatives with insect nAChR selectivity potential were acetyl-α-methylcholine and trimethyl-(3-methoxy-3-oxopropyl)ammonium, followed by acetylhomocholine and trimethyl-(4-oxopentyl) ammonium. Our results may provide guidance for the identification or design of insect-specific nAChR agonists using structure-based or in silico methods.
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Affiliation(s)
- H Dederer
- MSD Animal Health Innovation GmbH, Schwabenheim, Germany
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18
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Barber CM, Isbister GK, Hodgson WC. Alpha neurotoxins. Toxicon 2013; 66:47-58. [PMID: 23416229 DOI: 10.1016/j.toxicon.2013.01.019] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 01/29/2013] [Indexed: 10/27/2022]
Abstract
α-Neurotoxins have been isolated from hydrophid, elapid and, more recently, colubrid snake venoms. Also referred to as postsynaptic neurotoxins or 'curare mimetic' neurotoxins, they play an important role in the capture and/or killing of prey by binding to the nicotinic acetylcholine receptor on the skeletal muscle disrupting neurotransmission. They are also thought to cause respiratory paralysis in envenomed humans. This review will discuss the historical background into the discovery, isolation, structure and mechanism of action of the α-neurotoxins, including targets and cellular outcomes, and then will examine the potential uses of α-neurotoxins as pharmacological tools and/or as drug leads.
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Affiliation(s)
- Carmel M Barber
- Monash Venom Group, Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia
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19
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Postnatal changes in vagal control of esophageal muscle contractions in rats. Life Sci 2012; 90:495-501. [PMID: 22285836 DOI: 10.1016/j.lfs.2012.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Revised: 12/21/2011] [Accepted: 01/09/2012] [Indexed: 12/23/2022]
Abstract
AIMS Replacement of smooth muscles by striated muscles occurs in the esophagus during the early postnatal period. The aim of this study was to clarify postnatal changes in vagal control of esophageal muscle contractions in rats. MAIN METHODS An isolated segment of the neonatal rat esophagus was placed in an organ bath and the contractile responses were recorded using a force transducer. KEY FINDINGS Electrical stimulation of the vagus trunk evoked a biphasic contractile response in the neonatal esophageal segment. The first and second components of the contractions were inhibited by α-bungarotoxin and atropine, respectively. Ganglion blockers, hexamethonium and mecamylamine, did not affect vagally mediated contractions. The first component gradually enlarged with age in days, whereas the second component declined during the first week after birth. Application of d-tubocurarine or acetylcholine caused an apparent contraction in the esophageal striated muscle at postnatal day 0, but responses to these drugs were not observed at 1 week after birth. The neonatal esophagus expressed the γ-subunit of nicotinic acetylcholine receptors. In contrast, the ε-subunit was dominantly expressed in the adult esophagus. SIGNIFICANCE The vagus nerves directly innervate both the esophageal striated muscles and smooth muscles in the early neonatal period. During the process of muscle rearrangement, the property of the striated muscles is altered substantially. The specific features of striated muscles in the neonatal rat esophagus might compensate for immature formation of neuromuscular junctions. Unsuccessful conversion of the striated muscle property during postnatal muscle rearrangement would be related to disorders of esophageal motility.
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20
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Green BT, Welch KD, Cook D, Gardner DR. Potentiation of the actions of acetylcholine, epibatidine, and nicotine by methyllycaconitine at fetal muscle-type nicotinic acetylcholine receptors. Eur J Pharmacol 2011; 662:15-21. [DOI: 10.1016/j.ejphar.2011.04.053] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 04/15/2011] [Accepted: 04/18/2011] [Indexed: 10/18/2022]
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21
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Hung A, Yarovsky I. Gap Junction Hemichannel Interactions with Zwitterionic Lipid, Anionic Lipid, and Cholesterol: Molecular Simulation Studies. Biochemistry 2011; 50:1492-504. [DOI: 10.1021/bi1004156] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrew Hung
- Health Innovations Research Institute and School of Applied Sciences, RMIT University, GPO Box 2476, Victoria 3001, Australia
| | - Irene Yarovsky
- Health Innovations Research Institute and School of Applied Sciences, RMIT University, GPO Box 2476, Victoria 3001, Australia
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22
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Bernareggi A, Reyes-Ruiz JM, Lorenzon P, Ruzzier F, Miledi R. Microtransplantation of acetylcholine receptors from normal or denervated rat skeletal muscles to frog oocytes. J Physiol 2011; 589:1133-42. [PMID: 21224230 DOI: 10.1113/jphysiol.2010.202994] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Cell membranes, carrying neurotransmitter receptors and ion channels, can be 'microtransplanted' into frog oocytes. This technique allows a direct functional characterization of the original membrane proteins, together with any associated molecules they may have, still embedded in their natural lipid environment. This approach has been previously demonstrated to be very useful to study neurotransmitter receptors and ion channels contained in cell membranes isolated from human brains. Here, we examined the possibility of using the microtransplantation method to study acetylcholine receptors from normal and denervated rat skeletal muscles. We found that the muscle membranes, carrying their fetal or adult acetylcholine receptor isoforms, could be efficiently microtransplanted to the oocyte membrane, making the oocytes become sensitive to acetylcholine. These results show that oocytes injected with skeletal muscle membranes efficiently incorporate functional acetylcholine receptors, thus making the microtransplantation approach a valuable tool to further investigate receptors and ion channels of human muscle diseases.
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Affiliation(s)
- Annalisa Bernareggi
- Department of Life Sciences, University of Trieste, Via A. Fleming 22, I-34127 Trieste, Italy.
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Dederer H, Werr M, Ilg T. Differential sensitivity of Ctenocephalides felis and Drosophila melanogaster nicotinic acetylcholine receptor α1 and α2 subunits in recombinant hybrid receptors to nicotinoids and neonicotinoid insecticides. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2011; 41:51-61. [PMID: 20933086 DOI: 10.1016/j.ibmb.2010.09.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 09/22/2010] [Accepted: 09/29/2010] [Indexed: 05/30/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are the binding sites for nicotinoid drugs, such as nicotine and epibatidine, and are the molecular targets of the selectively insecticidal neonicotinoids. In this study we report the full length cDNA cloning of the three Ctenocephalides (C.) felis (cat flea) nAChR α subunits Cfα1, Cfα2, and Cfα3. When expressed in Xenopus oocytes as hybrid receptors with the Gallus gallus (chicken) β2 (Ggβ2) subunit, these cat flea α subunits formed acetylcholine-responsive ion channels. Acetylcholine-evoked currents of Cfα2/Ggβ2 were resistant to α-bungarotoxin, while those of Cfα1/Ggβ2 were sensitive to this snake toxin. The pharmacological profiles of Cfα1/Ggβ2, Cfα2/Ggβ2 and the chicken neuronal receptor Ggα4/Ggβ2 for acetylcholine, two nicotinoids and 6 insecticidal neonicotinoids were determined and compared. Particularly remarkable was the finding that Cfα1/Ggβ2 was far more sensitive to acetylcholine, nicotine and neonicotinoid agonists than either Cfα2/Ggβ2 or Ggα4/Ggβ2: for the anti flea neonicotinoid market compound imidacloprid the respective EC₅₀s were 0.02 μM, 1.31 μM and 10 μM. These results were confirmed for another insect species, Drosophila melanogaster, where the pharmacological profile of the Dmα1 and Dmα2 subunits as hybrid receptors with Ggβ2 in Xenopus oocyte expressions resulted in a similar sensitivity pattern as those identified for the C. felis orthologs. Our results show that at least in a Ggβ2 hybrid receptor setting, insect α1 subunits confer higher sensitivity to neonicotinoids than α2 subunits, which may contribute in vivo to the insect-selective action of this pesticide class.
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Affiliation(s)
- Helene Dederer
- Intervet Innovation GmbH, Zur Propstei, 55270 Schwabenheim, Germany
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Arias HR, Gu RX, Feuerbach D, Wei DQ. Different interaction between the agonist JN403 and the competitive antagonist methyllycaconitine with the human alpha7 nicotinic acetylcholine receptor. Biochemistry 2010; 49:4169-80. [PMID: 20377277 DOI: 10.1021/bi901999v] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interaction of the agonist JN403 with the human (h) alpha7 nicotinic acetylcholine receptor (AChR) was compared to that for the competitive antagonist methyllycaconitine (MLA). The receptor selectivity of JN403 was studied on the halpha7, halpha3beta4, and halpha4beta2 AChRs. The results established that the cationic center and the hydrophobic group found in JN430 and MLA are important for the interaction with the AChRs. MLA preincubation inhibits JN403-induced Ca(2+) influx in GH3-halpha7 cells with a potency 160-fold higher than that when MLA is co-injected with JN403. The most probable explanation, based on our dynamics results, is that MLA (more specifically the 3-methyl-2,5-dioxopyrrole ring and the B-D rings) stabilizes the resting conformational state. The order of receptor specificity for JN403 is as follows: halpha7 > halpha3beta4 ( approximately 40-fold) > halpha4beta2 ( approximately 500-fold). This specificity is based on a larger number of hydrogen bonds between the carbamate group (another pharmacophore) of JN403 and the halpha7 sites, the electrostatic repulsion between the positively charged residues around the halpha3beta4 sites and the cationic center of JN403, fewer hydrogen bonds for the interaction of JN403 with the halpha3beta4 AChR, and an unfavorable van der Waals interaction between JN403 and the alpha4-beta2 interface. The higher receptor specificity for JN403 could be important for the treatment of alpha7-related disorders, including dementias, pain-related ailments, depression, anxiety, and wound healing.
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Affiliation(s)
- Hugo R Arias
- Department of Pharmaceutical Sciences, College of Pharmacy, Midwestern University, Glendale, Arizona 85308, USA.
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25
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Tang PA, Jiang HB, Xu YQ, An FM, Wang JJ. Molecular characterization of two nicotinic acetylcholine receptor subunits from Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae). ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2009; 72:34-47. [PMID: 19533628 DOI: 10.1002/arch.20321] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Two nicotinic acetylcholine receptor (nAChR) subunit genes, Lbalpha1 and Lbalpha8, were isolated and characterized from psocid, Liposcelis bostrychophila Badonnel, using the rapid amplification of cDNA ends (RACE) technique. They are the first two nAChR family members isolated from the insect order of Psocoptera. The full-length cDNAs of Lbalpha1 (GenBank accession number: EU871527) and Lbalpha8 (EU871526) consist of 2,025 and 1,763 nucleotides, respectively, and an open reading frame of 1,644 and 1,608 bp encoding 547 and 535 amino acid proteins, respectively. Both genes have typical features of nAChR family members, though they share only 56% identity in amino acid sequence. The dendrogram generated by the MEGA 3.1 program shows that the protein deduced by Lbalpha1 had the closest phylogenetic relationship to Agamalpha1 from Anopheles gambiae and Amelalpha1 from Apis mellifera, and Lbalpha8 shares the highest identity with Agamalpha8 from An. gambiae and Amelalpha8 from A. mellifera. Quantitative real-time PCR analysis showed that Lbalpha1 was expressed 2.03-6.54-fold higher than Lbalpha8 at the different developmental stages of L. bostrychophila. The highest expression levels of Lbalpha1 and Lbalpha8 were both detected at adult stage and the lowest were at the third and fourth nymphal stages, respectively. There was a stable and relatively low expression level for Lbalpha1, whereas there was a descending expression pattern for Lbalpha8 in the 1st through the 4th nymphal stadia.
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Affiliation(s)
- Pei-An Tang
- Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, P. R. China
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26
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Bunnelle WH, Tietje KR, Frost JM, Peters D, Ji J, Li T, Scanio MJC, Shi L, Anderson DJ, Dyhring T, Grønlien JH, Ween H, Thorin-Hagene K, Meyer MD. Octahydropyrrolo[3,4-c]pyrrole: A Diamine Scaffold for Construction of Either α4β2 or α7-Selective Nicotinic Acetylcholine Receptor (nAChR) Ligands. Substitutions that Switch Subtype Selectivity. J Med Chem 2009; 52:4126-41. [DOI: 10.1021/jm900249k] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- William H. Bunnelle
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Karin R. Tietje
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Jennifer M. Frost
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Dan Peters
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Jianguo Ji
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Tao Li
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Marc J. C. Scanio
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Lei Shi
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - David J. Anderson
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Tino Dyhring
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Jens H. Grønlien
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Hilde Ween
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Kirsten Thorin-Hagene
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
| | - Michael D. Meyer
- Neuroscience Research, Abbott Laboratories, Department R47W, Building AP9A, Abbott Park, Illinois 60064-6117
- NeuroSearch A/S, 93 Pederstrupvej, DK-2750 Ballerup, Denmark
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27
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Zhang Y, Liu S, Gu J, Song F, Yao X, Liu Z. Imidacloprid acts as an antagonist on insect nicotinic acetylcholine receptor containing the Y151M mutation. Neurosci Lett 2009; 446:97-100. [PMID: 18824080 DOI: 10.1016/j.neulet.2008.09.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 08/29/2008] [Accepted: 09/15/2008] [Indexed: 10/21/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels which mediate fast cholinergic synaptic transmission in insect and vertebrate nervous systems. A point mutation Y151S had been identified in Nilaparvata lugens (brown planthopper) that is associated with target-site resistance to neonicotinoid insecticides. Methionine (M151) is found in the Caenorhabditis elegans alpha subunit acr18 at the corresponding site to Y151 in Nlalpha1. Here, the Y151M mutation was introduced into Nlalpha1 and co-expressed with rat beta2 in Xenopus oocytes. The influence of the Y151M mutation on the affinity and efficacy of acetylcholine and imidacloprid on hybrid nAChRs Nla1/beta2 was examined by radioligand binding and electrophysiology methods. Imidacloprid bound with Nlalpha1(Y151M)/beta2 with high affinity, although this was lower than that of Nlalpha1/beta2. However, imidacloprid did not show agonist actions on Nlalpha1(Y151M)/beta2, although the quite small responses to imidacloprid at high concentrations (0.5-1.0 mM) were detected in some (but not all) oocytes expressing Nlalpha1(Y151M/beta2. Further study demonstrated that imidacloprid acted as an antagonist on Nlalpha1(Y151M)/beta2, which blocked responses to acetylcholine on Nlalpha1(Y151M)/beta2 with a pIC50 of 5.14 +/- 0.06. Nlalpha1(Y151M)/beta2 nAChRs block by imidacloprid was slowly reversible. This is the first time a point mutation in loop B of insect nAChR alpha subunits has been identified that changes the mode of interaction between neonicotinoid insecticides and insect nAChRs.
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Affiliation(s)
- Yixi Zhang
- Key Laboratory of Monitoring and Management of Plant Disease and Insect, Ministry of Agriculture, Nanjing Agricultural University, Tongwei Road 6, Nanjing 210095, China
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Nasiripourdori A, Ranjbar B, Naderi-Manesh H. Binding of long-chain alpha-neurotoxin would stabilize the resting state of nAChR: a comparative study with alpha-conotoxin. Theor Biol Med Model 2009; 6:3. [PMID: 19210780 PMCID: PMC2649906 DOI: 10.1186/1742-4682-6-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Accepted: 02/11/2009] [Indexed: 11/27/2022] Open
Abstract
Background The details of interaction in a complex between potent antagonists such as long chain α-neurotoxins and α-conotoxins with nicotinic acetylcholine receptor (nAChR), and conformational changes induced by these antagonists, are not yet clear. Modeling In order to uncover some of these critical structural features, we conducted a docking simulation and a molecular dynamics simulation (MD) of a model of the ligand binding domain of nAChR in complex with a long-chain α-neurotoxin and an α-conotoxin. Results Our docking results confirm the claim that T.nAChR is in the basal or resting state, which favors binding to the alpha-neurotoxins. Moreover, more correct "hits" for the α/γ interface upon docking for conotoxin-nAChR confirm the preference of conotoxin GI for the α/γ interface. More importantly, upon binding of α-neurotoxin, ligand-bonded nAChR is less dynamic in certain domains than the apo form of the conotoxin-AChR complex. Some critical interactions in the binding site such as the salt bridge formed between K145/D200 in the neurotoxin-nAChR complex is further stabilized during the MD simulation, while it is obviously more labile in the apo form. Conclusion These observations could support the claim that alpha neurotoxins stabilize the nAChR resting state.
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Affiliation(s)
- Adak Nasiripourdori
- Department of Biophysics, Faculty of Science, Tarbiat Modares University, P,O, Box 14115-175, Tehran, Iran.
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29
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Jeschke P, Nauen R. Neonicotinoids-from zero to hero in insecticide chemistry. PEST MANAGEMENT SCIENCE 2008; 64:1084-98. [PMID: 18712805 DOI: 10.1002/ps.1631] [Citation(s) in RCA: 492] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In recent years, neonicotinoids have been the fastest-growing class of insecticides in modern crop protection, with widespread use against a broad spectrum of sucking and certain chewing pests. As potent agonists, they act selectively on insect nicotinic acetylcholine receptors, their molecular target site. The discovery of neonicotinoids can be considered as a milestone in insecticide research and facilitates greatly the understanding of the functional properties of insect nicotinic acetylcholine receptors. Because of the relatively low risk for non-target organisms and environment, the high target specificity of neonicotinoid insecticides and their versatility in application methods, this important class has to be maintained globally for integrated pest management strategies and insect resistance management programmes. This review comprehensively describes particularly the origin, structure and bonding as well as associated properties of neonicotinoid insecticides.
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Affiliation(s)
- Peter Jeschke
- Bayer CropScience AG, Research Insecticides Chemistry Insecticides, Building 6240, Alfred-Nobel Str. 50, D-40789 Monheim am Rhein, Germany.
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30
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Millar NS, Gotti C. Diversity of vertebrate nicotinic acetylcholine receptors. Neuropharmacology 2008; 56:237-46. [PMID: 18723036 DOI: 10.1016/j.neuropharm.2008.07.041] [Citation(s) in RCA: 274] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 07/14/2008] [Accepted: 07/15/2008] [Indexed: 10/21/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric neurotransmitter receptors. They are members of the Cys-loop family of ligand-gated ion channels which also include ionotropic receptors for 5-hydroxytryptamine (5-HT), gamma-aminobutyric acid (GABA) and glycine. Nicotinic receptors are expressed in both the nervous system and at the neuromuscular junction and have been implicated in several neurological and neuromuscular disorders. In vertebrates, seventeen nAChR subunits have been identified (alpha1-alpha10, beta1-beta4, gamma, delta and epsilon) which can co-assemble to generate a diverse family of nAChR subtypes. This review will focus on vertebrate nAChRs and will provide an overview of the extent of nAChR diversity based on studies of both native and recombinant nAChRs.
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Affiliation(s)
- Neil S Millar
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK.
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Lindovský J, Kaniaková M, Svobodová L, Vyskocil F, Krůsek J. Role of negatively charged amino acids in beta 4 F-loop in activation and desensitization of alpha 3 beta 4 rat neuronal nicotinic receptors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:864-71. [PMID: 18249185 DOI: 10.1016/j.bbamem.2008.01.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Revised: 01/04/2008] [Accepted: 01/10/2008] [Indexed: 10/22/2022]
Abstract
The role of negatively charged amino acids in the F-loop of the beta 4 subunit in channel activation and desensitization was studied using the patch-clamp technique. The selected amino acids were changed to their neutral analogs via point mutations. Whole-cell currents were recorded in COS cells transiently transfected with the alpha 3 beta 4 nicotinic acetylcholine receptor. The application of acetylcholine (ACh), nicotine (Nic), cytisine (Cyt), carbamylcholine (CCh) and epibatidine (Epi) to cells clamped at -40 mV produced inward currents which displayed biphasic desensitization. The EC50 of Epi and Nic were increased by a factor of 3-6 due to mutations D191N or D192N. Only Epi remained an agonist in the double-mutated receptors with EC50 increased 17-fold. The interaction of the receptors with the competitive antagonist (+)tubocurarine (TC) was weakened almost 3-fold in the double-mutated receptors. The mutations increased the proportion of the slower desensitization component and increased the response plateau, resulting in decreased receptor desensitization. The double mutation substantially accelerated the return from long-term desensitization induced by Epi.
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Affiliation(s)
- Jirí Lindovský
- Institute of Physiology, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague 4, Czech Republic
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The conformation of acetylcholine at its target site in the membrane-embedded nicotinic acetylcholine receptor. Proc Natl Acad Sci U S A 2007; 104:18031-6. [PMID: 17989232 DOI: 10.1073/pnas.0704785104] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The conformation of the neurotransmitter acetylcholine bound to the fully functional nicotinic acetylcholine receptor embedded in its native membrane environment has been characterized by using frequency-selective recoupling solid-state NMR. Six dipolar couplings among five resolved (13)C-labeled atoms of acetylcholine were measured. Bound acetylcholine adopts a bent conformation characterized with a quaternary ammonium-to-carbonyl distance of 5.1 A. In this conformation, and with its orientation constrained to that previously determined by us, the acetylcholine could be docked satisfactorily in the agonist pocket of the agonist-bound, but not the agonist-free, crystal structure of a soluble acetylcholine-binding protein from Lymnaea stagnali. The quaternary ammonium group of the acetylcholine was determined to be within 3.9 A of five aromatic residues and its acetyl group close to residues C187/188 of the principle and residue L112 of the complementary subunit. The observed >C O chemical shift is consistent with H bonding to the nicotinic acetylcholine receptor residues gammaY116 and deltaT119 that are homologous to L112 in the soluble acetylcholine-binding protein.
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33
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Moaddel R, Jozwiak K, Wainer IW. Allosteric modifiers of neuronal nicotinic acetylcholine receptors: new methods, new opportunities. Med Res Rev 2007; 27:723-53. [PMID: 17238157 DOI: 10.1002/med.20091] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Allosteric, non-competitive inhibitors (NCIs) of neuronal nicotinic acetylcholine receptors (nAChRs) have been shown to produce a wide variety of clinically relevant responses. Many of the observed effects are desired as the nAChR is the therapeutic target, while others are undesired consequences due to off-target binding at the nAChR. Thus, the determination of whether or not a lead drug candidate is an NCI should play an important role in drug discovery programs. However, the current experimental techniques used to identify NCIs are challenging, expensive, and time consuming. This review focuses on an alternative approach to the investigation of interactions between test compounds and nAChRs based upon liquid chromatographic stationary phases containing cellular fragments from cell lines expressing nAChRs. The development and validation of these phases as well as their use in drug discovery and pharmacophore modeling are discussed.
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Affiliation(s)
- Ruin Moaddel
- Gerontology Research Center, Laboratory of Clinical Investigations, National Institute on Aging/NIH, Baltimore, Maryland, USA
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Moaddel R, Wainer IW. Conformational mobility of immobilized proteins. J Pharm Biomed Anal 2006; 43:399-406. [PMID: 17095178 DOI: 10.1016/j.jpba.2006.08.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Accepted: 08/20/2006] [Indexed: 11/15/2022]
Abstract
Cellular membrane fragments have been immobilized on the surface of a silica-based liquid chromatographic support and on the surface of glass capillaries to create immobilized receptor and drug transporter columns. These columns have included phases containing one subtype of the nicotinic receptor (alpha3beta2, alpha3beta4, alpha4beta2, alpha4beta4) and the P-glycoprotein transporter. A key question in the application of these columns to drug discovery and development is the ability of the immobilized receptor or transporter to undergo ligand and/or co-factor induced conformational changes. Using frontal affinity chromatographic techniques and non-linear chromatographic techniques it has been demonstrated that the immobilized nicotinic receptors undergo agonist-induced conformational shifts from the resting to desensitized states with corresponding changes in binding affinities and enantioselectivities. Ligand-induced allosteric interactions and ATP-driven conformational changes have also been demonstrated with the immobilized Pgp stationary phase. The results demonstrate that the immobilized proteins retained their ability to undergo conformational mobility and that this is an attractive alternative to allow for the full characterization of multiple protein conformations.
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Affiliation(s)
- Ruin Moaddel
- Gerontology Research Center, National Institutes in Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825, USA.
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35
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Xu Y, Barrantes FJ, Shen J, Luo X, Zhu W, Chen K, Jiang H. Blocking of the Nicotinic Acetylcholine Receptor Ion Channel by Chlorpromazine, a Noncompetitive Inhibitor: A Molecular Dynamics Simulation Study. J Phys Chem B 2006; 110:20640-8. [PMID: 17034254 DOI: 10.1021/jp0604591] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A large series of pharmacological agents, distinct from the typical competitive antagonists, block in a noncompetitive manner the permeability response of the nicotinic acetylcholine receptor (nAChR) to the neurotransmitter acetylcholine. Taking the neuroleptic chlorpromazine (CPZ) as an example of such agents, the blocking mechanism of noncompetitive inhibitors to the ion channel pore of the nAChR has been explored at the atomic level using both conventional and steered molecular dynamics (MD) simulations. Repeated steered MD simulations have permitted calculation of the free energy (approximately 36 kJ/mol) of CPZ binding and identification of the optimal site in the region of the serine and leucine rings, at approximately 4 A from the pore entrance. Coulomb and the Lennard-Jones interactions between CPZ and the ion channel as well as the conformational fluctuations of CPZ were examined to assess the contribution of each to the binding of CPZ to the nAChR. The MD simulations disclose a dynamic interaction of CPZ binding to the nAChR ionic channel. The cationic ammonium head of CPZ forms strong hydrogen bonds with Glu262 (alpha), Asp268 (beta), Glu272 (beta), Ser276 (beta), Glu280 (delta), Gln271 (gamma), Glu275 (gamma), and Asn279 (gamma) nAChR residues. Finally, the conventional MD simulation of CPZ at its identified binding site demonstrates that the binding of CPZ not only blocks ion transport through the channel but also markedly inhibits the conformational transitions of the channel, necessary for nAChR to carry out its biological function.
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Affiliation(s)
- Yechun Xu
- Drug Discovery and Design Centre, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, and Graduate School, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
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36
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Dutertre S, Lewis RJ. Toxin insights into nicotinic acetylcholine receptors. Biochem Pharmacol 2006; 72:661-70. [PMID: 16716265 DOI: 10.1016/j.bcp.2006.03.027] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 03/17/2006] [Accepted: 03/20/2006] [Indexed: 11/28/2022]
Abstract
Venomous species have evolved cocktails of bioactive peptides to facilitate prey capture. Given their often exquisite potency and target selectivity, venom peptides provide unique biochemical tools for probing the function of membrane proteins at the molecular level. In the field of the nicotinic acetylcholine receptors (nAChRs), the subtype specific snake alpha-neurotoxins and cone snail alpha-conotoxins have been widely used to probe receptor structure and function in native tissues and recombinant systems. However, only recently has it been possible to generate an accurate molecular view of these nAChR-toxin interactions. Crystal structures of AChBP, a homologue of the nAChR ligand binding domain, have now been solved in complex with alpha-cobratoxin, alpha-conotoxin PnIA and alpha-conotoxin ImI. The orientation of all three toxins in the ACh binding site confirms many of the predictions obtained from mutagenesis and docking simulations on homology models of mammalian nAChR. The precise understanding of the molecular determinants of these complexes is expected to contribute to the development of more selective nAChR modulators. In this commentary, we review the structural data on nAChR-toxin interactions and discuss their implications for the design of novel ligands acting at the nAChR.
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Affiliation(s)
- Sébastien Dutertre
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld 4072, Australia
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37
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Zhang D, Gullingsrud J, McCammon JA. Potentials of mean force for acetylcholine unbinding from the alpha7 nicotinic acetylcholine receptor ligand-binding domain. J Am Chem Soc 2006; 128:3019-26. [PMID: 16506783 PMCID: PMC2546508 DOI: 10.1021/ja057292u] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nicotinic acetylcholine receptor is a prototype ligand-gated ion channel that mediates signal transduction in the neuromuscular junctions and other cholinergic synapses. The molecular basis for the energetics of ligand binding and unbinding is critical to our understanding of the pharmacology of this class of receptors. Here, we used steered molecular dynamics to investigate the unbinding of acetylcholine from the ligand-binding domain of human alpha7 nicotinic acetylcholine receptor along four different predetermined pathways. Pulling forces were found to correlate well with interactions between acetylcholine and residues in the binding site during the unbinding process. From multiple trajectories along these unbinding pathways, we calculated the potentials of mean force for acetylcholine unbinding. Four available methods based on Jarzynski's equality were used and compared for their efficiencies. The most probable pathway was identified to be along a direction approximately parallel to the membrane. The derived binding energy for acetylcholine was in good agreement with that derived from the experimental binding constant for acetylcholine binding protein, but significantly higher than that for the complete human alpha7 nicotinic acetylcholine receptor. In addition, it is likely that several intermediate states exist along the unbinding pathways.
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Affiliation(s)
- Deqiang Zhang
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA 92093-0365, USA.
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38
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Svobodová L, Krůsek J, Hendrych T, Vyskocil F. Physostigmine modulation of acetylcholine currents in COS cells transfected with mouse muscle nicotinic receptor. Neurosci Lett 2006; 401:20-4. [PMID: 16530961 DOI: 10.1016/j.neulet.2006.02.065] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Revised: 02/13/2006] [Accepted: 02/22/2006] [Indexed: 11/30/2022]
Abstract
Physostigmine (Phy), a reversible inhibitor of acetylcholine (ACh) esterase (AChE), may also act as a low potency agonist and a modulator of the nicotinic receptor. The actions of Phy on mouse muscle nicotinic receptors in the COS-7 cell line were studied by the patch-clamp technique. Currents were recorded in the whole-cell mode 3-7 days after cell transfection by plasmids coding alphabetagammadelta combination of receptor subunits. The application of ACh to cells clamped at -10 mV produced inward currents which displayed desensitization. The application of Phy in concentrations up to 1 x 10(-3) M did not give reliable specific whole-cell membrane responses. The application of Phy in concentrations of 10(-6)-10(-4) M together with ACh modulated the amplitude; accelerated desensitization of currents induced by ACh and increased the final extent of desensitization in a concentration-dependent manner. This finding is in contrast to the suppression and slowing down of desensitization by Phy and 1-methyl-galanthamine observed in Torpedo receptors.
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Affiliation(s)
- Lucie Svobodová
- Institute of Physiology, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague, Czech Republic
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39
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Svobodová L, Krusek J, Hendrych T, Vyskocil F. Allosteric Modulation of the Nicotinic Acetylcholine Receptor by Physostigmine. Ann N Y Acad Sci 2006; 1048:355-8. [PMID: 16154951 DOI: 10.1196/annals.1342.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The action of physostigmine on mouse muscle nicotinic acetylcholine receptor expressed in the COS-7 cell line was studied by the patch-clamp technique. Physostigmine accelerated, by allosteric modulation, the rate of desensitization of whole cell currents induced by acetylcholine and decreased the maximal amplitude in concentration-dependent manner.
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Affiliation(s)
- Lucie Svobodová
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague
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40
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Bass C, Lansdell SJ, Millar NS, Schroeder I, Turberg A, Field LM, Williamson MS. Molecular characterisation of nicotinic acetylcholine receptor subunits from the cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2006; 36:86-96. [PMID: 16360954 DOI: 10.1016/j.ibmb.2005.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 11/04/2005] [Accepted: 11/08/2005] [Indexed: 05/05/2023]
Abstract
As part of a program to monitor the susceptibility of cat flea populations to the insecticide imidacloprid we have examined the cat flea nicotinic acetylcholine receptor, the target site protein of the neonicotinoid group of insecticides. Seven nAChR subunits (six alpha-type and one beta-type) were identified in cat flea using a degenerate PCR-based strategy. Five of these were expressed in vitro by creating chimeras containing the N-terminal ligand-binding domain of the cat flea subunits and the C-terminal region of the Drosophila Dalpha2 (SAD) subunit. Two of the five chimeric subunits, Cfalpha1/Dalpha2 and Cfalpha3/Dalpha2, when co-expressed with rat beta2 in Drosophila S2 cells, showed high-affinity binding of both epibatidine (Kd=1.6+/-0.6 and 0.13+/-0.06nM, respectively), and imidacloprid (Ki=142+/-34 and 28.7+/-2.4nM, respectively). It is likely therefore that Cfalpha1 and Cfalpha3 contribute to nAChR populations in vivo that are sensitive to imidacloprid. The identification of cat flea nAChR subunits that have a high affinity for imidacloprid presents candidate genes in which to look for resistance-associated mutations if target-site resistance to imidacloprid arises in domestic pet flea populations.
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Affiliation(s)
- Chris Bass
- Department of Biological and Ecological Chemistry, Rothamsted Research, Harpenden, AL5 2JQ, UK.
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41
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Szegedi V, Bárdos G, Détári L, Tóth A, Banczerowski-Pelyhe I, Világi I. Transient alterations in neuronal and behavioral activity following bensultap and fipronil treatment in rats. Toxicology 2005; 214:67-76. [PMID: 16009481 DOI: 10.1016/j.tox.2005.05.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Revised: 05/27/2005] [Accepted: 05/31/2005] [Indexed: 10/25/2022]
Abstract
In the present multilevel study, neuromodulatory effect of two insecticides, bensultap and fipronil were investigated in rats. Although the new generation of insecticides shows greater affinity to invertebrate as compared to mammalian receptors, toxic effect of these compounds in vertebrates cannot be excluded. The aim of the study was to follow the course of neuronal changes in rats for 1 week after a high-dose insecticide exposure. Alterations in synaptic excitability, in sleep-wake pattern and in behavior were analyzed using conventional in vitro brain slice method, long-lasting EEG recordings, and open-field tests. The two chemicals examined in this study induced only weak and transient effects. Bensultap, acting on nicotinic acetylcholine receptors, caused a transient decrease in neuronal excitability. Sleep and behavioral changes demonstrated a similar time course. Fipronil, on the other hand, increased excitability and its effect lasted slightly longer. All effects were greatest on the first day following 'poisoning', and measured variables usually returned to normal within a week. These results suggest that the studied compounds do have some effects on the mammalian nervous system, but this effect is usually mild and temporary.
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Affiliation(s)
- Viktor Szegedi
- Eötvös Loránd University, Department of Physiology and Neurobiology, 1117 Budapest, Hungary
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42
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Moaddel R, Jozwiak K, Whittington K, Wainer IW. Conformational Mobility of Immobilized α3β2, α3β4, α4β2, and α4β4 Nicotinic Acetylcholine Receptors. Anal Chem 2004; 77:895-901. [PMID: 15679359 DOI: 10.1021/ac048826x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Four affinity chromatography stationary phases have been developed based upon immobilized nicotinic acetylcholine receptor (nAChR) subtypes, the alpha3beta2, alpha3beta4, alpha4beta2, and alpha4beta4 nAChRs. The stationary phases were created using membranes from cell lines expressing the subtypes and an immobilized artificial membrane stationary phase. The immobilized nAChRs were characterized using frontal chromatography with the agonist epibatidine as the marker. The observed binding affinities for the agonists epibatidine, nicotine, and cytisine were consistent with reported values, indicating that the nAChRs retained their ability to bind agonists. The noncompetitive inhibitors (NCIs) of the nAChR (R)- and (S)-mecamylamine, phencylcidine, dextromethoprphan, and levomethorphan were also chromatographed on the columns using nonlinear chromatography techniques. The studies were carried out before and after exposure of the columns to epibatidine. The NCI retention times increased after exposure to epibtatidine as did the enantioselective separation of mecamylamine and methorphan. The results indicate that the immobilized nAChRs retained their ability to undergo agonist-induced conformational change from the resting to the desensitized states. The columns provide a unique ability to study the interactions of NCIs with both of these conformational states.
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Affiliation(s)
- Ruin Moaddel
- Gerontology Research Center, National Institutes in Aging, National Institutes of Health, Baltimore, MD 21224-6825, USA
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43
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Yoon KJP, Hyatt JL, Morton CL, Lee RE, Potter PM, Danks MK. Characterization of inhibitors of specific carboxylesterases: Development of carboxylesterase inhibitors for translational application. Mol Cancer Ther 2004. [DOI: 10.1158/1535-7163.903.3.8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Carboxylesterases, expressed at high levels in human liver and intestine, are thought to detoxify xenobiotics. The anticancer prodrug 7-ethyl-10-[4-1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) is also metabolized by carboxylesterases to produce the active drug 7-ethyl-10-hydroxycamptothecin. Activation of CPT-11 by human intestinal carboxylesterase (hiCE) in the human intestine may contribute to delayed onset diarrhea, a dose-limiting side effect of this drug. The goal of this study was to develop small molecule inhibitors selective for hiCE to circumvent or treat the toxic side effects of CPT-11. A secondary goal was to develop molecules that specifically inhibit activation of CPT-11 by a rabbit liver carboxylesterase (rCE). rCE is the most efficient CPT-11–activating enzyme thus far identified, and this enzyme is being developed for viral-directed enzyme prodrug therapy applications. Based on in vitro assays with partially purified hiCE and rCE proteins and on growth inhibition assays using U373MG human glioma cells transfected to express hiCE or rCE (U373pIREShiCE or U373pIRESrCE), we identified specific inhibitors of each enzyme. Lead compounds are derivatives of nitrophenol having 4-(furan-2-carbonyl)-piperazine-1-carboxylic acid or 4-[(4-chlorophenyl)-phenylmethyl]-piperazine-1-carboxylic acid substitutions in the p position. Kinetic analysis of each compound for hiCE compared with rCE showed that the Ki values of the most selective of these inhibitors differed by 6- to 10-fold. In growth inhibition assays, nontoxic, low micromolar concentrations of these inhibitors increased the EC50 of CPT-11 for U373pIREShiCE or U373pIRESrCE cells by 13- to >1,500-fold. The four compounds characterized in this study will serve as lead compounds for a series of inhibitors to be constructed using a combinatorial approach.
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Affiliation(s)
- Kyoung Jin P. Yoon
- 1Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee and
| | - Janice L. Hyatt
- 1Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee and
| | - Christopher L. Morton
- 1Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee and
| | - Richard E. Lee
- 2Department of Pharmaceutical Science, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Philip M. Potter
- 1Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee and
| | - Mary K. Danks
- 1Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee and
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44
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Henchman RH, Wang HL, Sine SM, Taylor P, McCammon JA. Asymmetric structural motions of the homomeric alpha7 nicotinic receptor ligand binding domain revealed by molecular dynamics simulation. Biophys J 2004; 85:3007-18. [PMID: 14581202 PMCID: PMC1303578 DOI: 10.1016/s0006-3495(03)74720-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
A homology model of the ligand binding domain of the alpha7 nicotinic receptor is constructed based on the acetylcholine-binding protein crystal structure. This structure is refined in a 10 ns molecular dynamics simulation. The modeled structure proves fairly resilient, with no significant changes at the secondary or tertiary structural levels. The hypothesis that the acetylcholine-binding protein template is in the activated or desensitized state, and the absence of a bound agonist in the simulation suggests that the structure may also be relaxing from this state to the activatable state. Candidate motions that take place involve not only the side chains of residues lining the binding sites, but also the subunit positions that determine the overall shape of the receptor. In particular, two nonadjacent subunits move outward, whereas their partners counterclockwise to them move inward, leading to a marginally wider interface between themselves and an overall asymmetric structure. This in turn affects the binding sites, producing two that are more open and characterized by distinct side-chain conformations of W54 and L118, although motions of the side chains of all residues in every binding site still contribute to a reduction in binding site size, especially the outward motion of W148, which hinders acetylcholine binding. The Cys loop at the membrane interface also displays some flexibility. Although the short simulation timescale is unlikely to sample adequately all the conformational states, the pattern of observed motions suggests how ligand binding may correlate with larger-scale subunit motions that would connect with the transmembrane region that controls the passage of ions. Furthermore, the shape of the asymmetry with binding sites of differing affinity for acetylcholine, characteristic of other nicotinic receptors, may be a natural property of the relaxed, activatable state of alpha7.
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Affiliation(s)
- Richard H Henchman
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA.
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45
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Jozwiak K, Ravichandran S, Collins JR, Wainer IW. Interaction of Noncompetitive Inhibitors with an Immobilized α3β4 Nicotinic Acetylcholine Receptor Investigated by Affinity Chromatography, Quantitative−Structure Activity Relationship Analysis, and Molecular Docking. J Med Chem 2004; 47:4008-21. [PMID: 15267239 DOI: 10.1021/jm0400707] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A large number of drug substances act as noncompetitive inhibitors (NCIs) of the nicotinic acetylcholine receptor (nAChR) by blocking the ion flux through the channel. An affinity chromatography technique has been developed for investigating the interactions between NCIs and the alpha3beta4 subtype of neuronal nAChR. The data obtained from the chromatographic study were used to construct QSAR models of the NCI-nAChR binding with both electronic and steric parameters observed as important descriptors. A molecular model of the transmembrane domain of the alpha3beta4 subtype of nAChR was constructed and used to simulate the docking of a series of NCIs. A key aspect of the model was the discovery of the cleft produced by the incorporation of the bulky phenylalanine moiety into the nonpolar section of the lumen by the beta4 subunit. Quantitatively, the results of docking simulations modeled the experimental affinity data better than QSAR results. The computational approach, combined with the modeling of NCI-nAChR interaction by affinity chromatography, can be used to predict possible toxicities and adverse interactions.
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Affiliation(s)
- Krzysztof Jozwiak
- Gerontology Research Center, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, Maryland 21224, USA
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46
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Avramopoulou V, Mamalaki A, Tzartos SJ. Soluble, oligomeric, and ligand-binding extracellular domain of the human alpha7 acetylcholine receptor expressed in yeast: replacement of the hydrophobic cysteine loop by the hydrophilic loop of the ACh-binding protein enhances protein solubility. J Biol Chem 2004; 279:38287-93. [PMID: 15226316 DOI: 10.1074/jbc.m402533200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The N-terminal extracellular domain (ECD; amino acids 1-208) of the neuronal nicotinic acetylcholine receptor (AChR) alpha7 subunit, the only human AChR subunit known to assemble as a homopentamer, was expressed as a glycosylated form in the yeast Pichia pastoris in order to obtain a native-like model of the extracellular part of an intact pentameric nicotinic AChR. This molecule, alpha7-ECD, although able to bind the specific ligand alpha-bungarotoxin, existed mainly in the form of microaggregates. Substitution of Cys-116 in the alpha7-ECD with serine led to a decrease in microaggregate size. A second mutant form, alpha7-ECD(C116S,Cys-loop), was generated in which, in addition to the C116S mutation, the hydrophobic Cys-loop (Cys(128)-Cys(142)) was replaced by the corresponding hydrophilic Cys-loop from the snail glial cell acetylcholine-binding protein. This second mutant protein was water-soluble, expressed at a moderate level (0.5 +/- 0.1 mg/liter), and had a size corresponding approximately to a pentamer as judged by gel filtration and electron microscopy studies. It also bound (125)I-alpha-bungarotoxin with relatively high affinity (K(d) = 57 nm), the binding being inhibited by unlabeled alpha-bungarotoxin, d-tubocurarine, or nicotine (K(i) = 0.8 x 10(-7) m, K(i) = 1 x 10(-5) m, and K(i) = 0.9 x 10(-2) m, respectively). All three constructs were expressed as glycosylated forms, but in vitro deglycosylation reduced the heterogeneity without affecting their ligand binding properties. These results show that alpha7-ECD(C116S,Cys-loop) was expressed in P. pastoris as an oligomer (probably a pentamer) with a near native conformation and that its deglycosylated form seems to be suitable starting material for structural studies on the ligand-binding domain of a neurotransmitter receptor.
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Affiliation(s)
- Vassiliki Avramopoulou
- Department of Biochemistry, Hellenic Pasteur Institute, 127 Vassilissis Sofias Avenue, GR11521 Athens, Greece
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47
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Woods AS. The Mighty Arginine, the Stable Quaternary Amines, the Powerful Aromatics, and the Aggressive Phosphate: Their Role in the Noncovalent Minuet. J Proteome Res 2004; 3:478-84. [PMID: 15253429 DOI: 10.1021/pr034091l] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the age of proteomics, the role of certain amino acid residues and some post-translational modifications in noncovalent complex formation are gaining in importance, as the understanding of interactions between biological molecules, is at the heart of the structure function relationship puzzle. In this work, mass spectrometry is used to highlight ammonium- or guanidinium-aromatic interactions through Cation-pi bonds and ammonium- or guanidinium-phosphate interactions through salt bridge formation. Such interactions are crucial factors in certain ligand-receptor interactions and receptor-receptor interactions. In addition, the ability of phosphorylated residues and phosphorylated lipids to form noncovalent complexes with guanidinium and quaternary ammonium (mostly through Coulombic interactions) is demonstrated, and could explain the stability of certain membrane embedded protein, or a possible role for phosphorylation in protein-protein interactions. Dougherty's work demonstrates cation-pi interactions in intra-protein interactions and folding, the present work explores inter-peptide interactions, i.e., the formation of noncovalent complexes between peptides' epitopes containing adjacent aromatic residues and ones containing adjacent Arg as a model to better understand the role of cation-pi complexes in protein-protein interaction. Complexes of peptides containing aromatic residues with quaternary amines as well as the interaction of aromatic compounds, with the guanidinium group of Arg are also investigated. Considering that an inordinate number of therapeutic compounds contain aromatic rings and quaternary amines, the above-described interactions could possibly be of great importance in better understanding their mechanism of action.
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Affiliation(s)
- Amina S Woods
- The National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 5500 Nathan Shock Drive, Baltimore, Maryland 21224, USA.
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48
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Göõz M, Tóth M, Vakkuri O, Göõz P, Smolka AJ, de Châtel R, Szalay KS. Endogenous ouabain-like factor (OLF) secretion is modulated by nicotinic mechanisms in rat adrenocortical cells. Life Sci 2004; 74:2111-28. [PMID: 14969716 DOI: 10.1016/j.lfs.2003.07.058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2003] [Accepted: 07/15/2003] [Indexed: 11/17/2022]
Abstract
This study tested the hypothesis that rat adrenocortical secretion of endogenous ouabain-like factor (OLF) is regulated by nicotinic mechanisms. OLF secreted by dispersed cell suspensions of zona glomerulosa (ZG) and fasciculata/reticularis (ZFR) cells was found to co-elute with authentic ouabain by reverse phase HPLC; OLF concentrations in cell supernatants were measured by radioimmunoassay. Nicotine (10(-6) - 10(-3) M) stimulated significant OLF secretion in rat adrenocortical cells. Acetylcholine (10(-7) - 10(-4) M) and eserine (10(-7) - 10(-3) M) stimulated OLF secretion in ZG cells at lower concentrations and stimulated at higher concentrations. Acetylcholine had no effect on ZFR secretion of OLF, but eserine stimulated OLF secretion. ACTH (10(-8) M) strongly potentiated the OLF stimulatory effect of nicotine in ZG cells; however significant interactions between nicotine and ACTH or angiotensin II on OLF secretion in ZFR cells were not apparent. The ganglionic blockers hexamethonium and mecamylamine further potentiated the effect of nicotine, implicating nicotinic acetylcholine receptors (nAChRs) in regulation of OLF secretion. The alpha7-receptor antagonist methyllycaconitine (MLA) dose-dependently inhibited the effect of nicotine in the ZG cells, and in ZFR cells MLA potentiated nicotine-induced OLF secretion. These data suggest that nicotinic regulation may underlie OLF secretion by rat adrenocortical cells, and strongly suggest presence of functional nicotinic acetylcholine receptors on these cells.
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Affiliation(s)
- Monika Göõz
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43, 1083 Budapest, Hungary.
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49
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Bentley GN, Jones AK, Oliveros Parra WG, Agnew A. ShAR1α and ShAR1β: novel putative nicotinic acetylcholine receptor subunits from the platyhelminth blood fluke Schistosoma. Gene 2004; 329:27-38. [PMID: 15033526 DOI: 10.1016/j.gene.2003.12.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2003] [Revised: 11/21/2003] [Accepted: 12/12/2003] [Indexed: 10/26/2022]
Abstract
The cDNAs for two novel neuronal-type nicotinic acetylcholine receptor (nAChR) subunits have been cloned and characterised from the parasitic trematode blood fluke Schistosoma haematobium. One of these encodes a putative nAChR alpha-subunit named ShAR1alpha, whilst the second encodes a potential non-alpha subunit, ShAR1beta. These ShARs possess the key structural features common to all nAChRs, but they are unusual in that they have very large cytoplasmic domains spanning M3 and M4. Overall, the ShAR1alpha and ShAR1beta proteins share 37% identity and 53% similarity, but excluding the residues of the M3-M4 domain this rises to 52% identity and 71% similarity. Sequence comparisons with other nAChR polypeptides indicate that both ShARs are most similar to the invertebrate alpha7-like subunits identified in insects and nematodes, and to the vertebrate subunits alpha7 and alpha8. Outside of the M3-M4 domain, 45% and 40%, respectively, of the ShAR1alpha and ShAR1beta residues are conserved in the ACR-16 subunit from Caenorhabditis elegans. Phylogenetic analysis suggests that the ShARs share a common lineage with members of the ACR-16 group as well as alpha7 and alpha8. Immunolocalisation studies revealed distinct and non-overlapping patterns of distribution for ShAR1alpha and ShAR1beta within the parasite. ShAR1beta was localised within the musculature and on discrete cell bodies within the connective parenchyma. In contrast, ShAR1alpha was localised exclusively to the surface membranes, suggesting it may contribute to the regulatory nAChR we have characterised previously. In Xenopus oocyte expression studies, ShAR1alpha did not form functional channels on its own or in combination with ShAR1beta or the chick beta2 subunit. Furthermore, a chimera in which the M3-M4 domain of ShAR1alpha was replaced with that of chick alpha7 was also non-functional. We discuss our findings in the context of the proposed role for surface nAChRs in the regulation of glucose uptake in the parasite, and the potential exploitation of these receptors as targets for cholinergic schistosomicides.
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Affiliation(s)
- Geoffrey N Bentley
- The School of Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, UK
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50
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Drescher DG, Ramakrishnan NA, Drescher MJ, Chun W, Wang X, Myers SF, Green GE, Sadrazodi K, Karadaghy AA, Poopat N, Karpenko AN, Khan KM, Hatfield JS. Cloning and characterization of α9 subunits of the nicotinic acetylcholine receptor expressed by saccular hair cells of the rainbow trout (Oncorhynchus mykiss). Neuroscience 2004; 127:737-52. [PMID: 15283971 DOI: 10.1016/j.neuroscience.2004.05.037] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Revised: 04/27/2004] [Accepted: 05/11/2004] [Indexed: 11/19/2022]
Abstract
alpha9/alpha10 Subunits are thought to constitute the nicotinic acetylcholine receptors mediating cholinergic efferent modulation of vertebrate hair cells. The present report describes the cloning and sequence analysis of subunits of the alpha9-containing receptor of a hair-cell layer from the saccule of the rainbow trout (Oncorhynchus mykiss). A major alpha9 subunit, termed alpha9-I, displayed typical features of a nicotinic alpha subunit, with total coding sequence of 572 amino acids including a 16 amino-acid signal peptide. It possessed an extended cytoplasmic loop between membrane-spanning regions M3 and M4, compared with mammalian homologs. Transcript for alpha9-I was robustly expressed in the saccular hair cell layer and less prominently in trout olfactory mucosa, spleen, pituitary gland, and liver, as determined by reverse transcription-polymerase chain reaction. alpha9-I cDNA was not detected in trout brain, skeletal muscle, retina, and kidney. The alpha9-I nicotinic receptor protein was immunolocalized, with an affinity-purified antibody directed against a trout alpha9-I epitope, to hair-cell and neural sites in the saccular hair-cell layer. Foci were found at basal and basolateral membrane sites on hair cells as well as on afferent nerve. Receptor clustering was observed in hair cells bordering non-sensory epithelium. Since in higher vertebrates the alpha9 is reported to associate with another nicotinic subunit, alpha10, we examined the possibility of expression of additional nicotinic subunits in trout saccular hair cells. Message for another nicotinic subunit, termed alpha9-II, was found to be expressed in the hair cells, although more difficult to amplify than alpha9-I. In contrast to alpha9-I, alpha9-II was expressed in brain, as well as in olfactory mucosa, less prominently in pituitary gland and liver, but not in spleen, skeletal muscle, retina, or kidney. The cloned alpha9-II had a total coding sequence of 550 amino acids, which included a 17-amino-acid signal peptide, and an extended M3-M4 loop. A third nicotinic subunit message, termed alpha9-III, was PCR-amplified from trout olfactory mucosa where it was strongly expressed. However, message for alpha9-III was not detected in hair cells. Message for alpha9-III was moderately expressed in trout brain, retina, and pituitary gland but not in trout spleen, skeletal muscle, liver, and kidney. Thus, alpha9-I and alpha9-II may together contribute to the formation of the hair-cell nicotinic receptor of teleosts, where no ortholog of alpha10 appears to exist. The current work is, to our knowledge, the first description of alpha9 coding sequences directly from a vertebrate hair cell source. Further, the generality of hair cell expression of subunits for the alpha9-containing nicotinic cholinergic receptor has been extended to fishes, suggesting a similar efferent mechanism across all vertebrate octavolateralis sensory systems.
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Affiliation(s)
- D G Drescher
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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