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Houchat JN, Cartereau A, Taillebois E, Thany SH. Calmidazolium induces a decrease in nicotine-induced currents and intracellular calcium levels after pulse application of nicotine onto insect neurosecretory cells. J Insect Physiol 2022; 139:104385. [PMID: 35315336 DOI: 10.1016/j.jinsphys.2022.104385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 03/01/2022] [Accepted: 03/16/2022] [Indexed: 06/14/2023]
Abstract
Dorsal unpaired median (DUM) neurons, are a class of insect neurosecretory cells, which are involved in the control of several functions, such as excretion and reproduction, or the release of neurohormones. Previous studies demonstrated that they express different nicotinic acetylcholine receptor subtypes, in particular α-bungarotoxin-insensitive receptors, with nAChR1 and nAChR2 subtypes. Here, we demonstrated that pulse application of 1 mM nicotine (300 ms pulse duration) induced inward currents which were reduced under bath application of 15 µM calmidazolium, a calmodulin inhibitor. Bath application of 0.5 µM α-bungarotoxin had no effect on calmidazolium action, suggesting that it could have an indirect effect through α-bungarotoxin-insensitive receptors. Indeed, nicotine-evoked currents were reduced by 10 µM d-tubocurarine, and completely blocked by 5 µM mecamylamine, which affected nAChR1 and nAChR2 subtypes, respectively. Our results demonstrated that nAChR2 subtypes are involved in the indirect effect of calmidazolium. Moreover, we found that this calmidazolium effect was associated to a strong reduction in intracellular calcium levels after pulse application of 1 mM nicotine. Thus, compared to previous studies on mammalian cells, calmidazolium did not cause an increase in intracellular calcium levels in DUM neurons, suggesting that different calcium mechanisms are involved in the calmidazolium effect.
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Affiliation(s)
- Jean-Noël Houchat
- Université d'Orléans, LBLGC USC-INRAE 1328, 1 rue de Chartres, Orléans 45067, France
| | - Alison Cartereau
- Université d'Orléans, LBLGC USC-INRAE 1328, 1 rue de Chartres, Orléans 45067, France
| | - Emiliane Taillebois
- Université d'Orléans, LBLGC USC-INRAE 1328, 1 rue de Chartres, Orléans 45067, France
| | - Steeve H Thany
- Université d'Orléans, LBLGC USC-INRAE 1328, 1 rue de Chartres, Orléans 45067, France.
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Xia J, Yang H, Mu M, Micovic N, Poskanzer KE, Monaghan JR, Clark HA. Imaging in vivo acetylcholine release in the peripheral nervous system with a fluorescent nanosensor. Proc Natl Acad Sci U S A 2021; 118:e2023807118. [PMID: 33795516 PMCID: PMC8040656 DOI: 10.1073/pnas.2023807118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The ability to monitor the release of neurotransmitters during synaptic transmission would significantly impact the diagnosis and treatment of neurological diseases. Here, we present a DNA-based enzymatic nanosensor for quantitative detection of acetylcholine (ACh) in the peripheral nervous system of living mice. ACh nanosensors consist of DNA as a scaffold, acetylcholinesterase as a recognition component, pH-sensitive fluorophores as signal generators, and α-bungarotoxin as a targeting moiety. We demonstrate the utility of the nanosensors in the submandibular ganglia of living mice to sensitively detect ACh ranging from 0.228 to 358 μM. In addition, the sensor response upon electrical stimulation of the efferent nerve is dose dependent, reversible, and we observe a reduction of ∼76% in sensor signal upon pharmacological inhibition of ACh release. Equipped with an advanced imaging processing tool, we further spatially resolve ACh signal propagation on the tissue level. Our platform enables sensitive measurement and mapping of ACh transmission in the peripheral nervous system.
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Affiliation(s)
- Junfei Xia
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Hongrong Yang
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Michelle Mu
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Nicholas Micovic
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Kira E Poskanzer
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
- Kavli Insititute for Fundamental Neuroscience, San Francisco, CA 94143
| | - James R Monaghan
- Department of Biology, College of Science, Northeastern University, Boston, MA 02115
| | - Heather A Clark
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115;
- Department of Chemistry and Chemical Biology, College of Science, Northeastern University, Boston, MA 02115
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Badanavalu MP, Srivatsan M. Nicotine is neuroprotective to neonatal neurons of sympathetic ganglion in rat. Auton Neurosci 2018; 216:25-32. [PMID: 30206032 DOI: 10.1016/j.autneu.2018.08.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 07/13/2018] [Accepted: 08/31/2018] [Indexed: 01/04/2023]
Abstract
Sympathetic neurons of SCG are dependent on availability of nerve growth factor (NGF) for their survival. SCG neurons express nicotinic receptors (nAChR) whose expression levels are modulated by nicotine. Nicotine exerts multiple effects on neurons, including neuroprotection, through nAChR binding. Although sympathetic neurons express robust levels of nAChR, a possible neuroprotective role for nicotine in these neurons is not well-understood. Therefore we determined the effect of nicotine exposure on survival of SCG neurons during NGF withdrawal in a well-established cell culture system. NGF was withdrawn in rat neonatal SCG neuron cultures which were then treated with either 10 μM nicotine alone or with nAChR antagonists 0.1 μM α-bungarotoxin (antagonist for α7 subunit bearing nAChR) and 10 μM mecamylamine (non-specific antagonist for ganglionic nAChR) for 48 h. Apoptotic death was determined by TUNEL staining. Cell survival was also determined by MTS assay. Western blot analysis of ERK1/2 was also performed. Our results showed that exposure to 10 μM nicotine significantly reduced apoptotic cell death in SCG neurons resulting from NGF withdrawal as shown by fewer TUNEL positive cells. The MTS assay results also revealed that 10 μM nicotine concentration significantly increased cell survival thus indicating neuroprotective effect of nicotine against cell death resulting from NGF withdrawal. Nicotinic receptor antagonists (bungarotoxin & mecamylamine) attenuated the effect of nicotine's action of neuroprotection. Western blot analysis showed an increased expression of ERK1/2 in nicotine treated cultures suggesting nicotine provided neuroprotection in SCG neurons by increasing the expression of ERK1/2 through nicotinic receptor dependent mechanisms.
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Affiliation(s)
- Mahadevappa P Badanavalu
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR 72401, United States
| | - Malathi Srivatsan
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR 72401, United States.
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Abstract
The fruit fly, Drosophila melanogaster, is a popular model organism for studying neurological processes and diseases due to the availability of sophisticated genetic tools. While endogenous neurotransmitter release has been characterized in Drosophila larvae, here, we measured endogenous dopamine release in isolated adult Drosophila brains for the first time. Dopamine was measured with fast-scan cyclic voltammetry (FSCV), and acetylcholine or nicotine were used as the stimulus, as both interact with nicotinic acetylcholine receptors (nAChRs) to evoke endogenous dopamine release. Stimulations with 10 pmol of acetylcholine elicited 0.26 ± 0.05 μM dopamine, while 70 fmol nicotine stimulations evoked 0.29 ± 0.03 μM in the central complex. Nicotine-stimulated dopamine release lasted much longer than acetylcholine-stimulated release. Dopamine release is reduced in the presence of nAChR antagonist α-bungarotoxin and the sodium channel blocker tetrodotoxin, indicating release is mediated by nAChRs and exocytosis. The identity of dopamine was confirmed by using 3-iodotyrosine, a dopamine synthesis inhibitor, and by confirming that release was not changed in octopamine synthesis mutant flies, Tdc2 RO54. Additionally, the half-decay time ( t50) in fumin (67 ± 15 s), dopamine transporter mutant flies, was larger than in wild-type flies (16 ± 3.7 s) further proving that acetylcholine stimulation evokes dopamine release. This study demonstrates that stimulation of nAChRs can be used to elicit endogenous dopamine release in adult fly brains, which will be a useful technique for future studies probing dopamine changes during aging or in neurodegenerative diseases.
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Affiliation(s)
- Mimi Shin
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901
| | - B. Jill Venton
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901
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Torrealba D, Balasch JC, Criado M, Tort L, Mackenzie S, Roher N. Functional evidence for the inflammatory reflex in teleosts: A novel α7 nicotinic acetylcholine receptor modulates the macrophage response to dsRNA. Dev Comp Immunol 2018; 84:279-291. [PMID: 29501534 DOI: 10.1016/j.dci.2018.02.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 02/28/2018] [Accepted: 02/28/2018] [Indexed: 06/08/2023]
Abstract
The inflammatory reflex modulates the innate immune system, keeping in check the detrimental consequences of overstimulation. A key player controlling the inflammatory reflex is the alpha 7 acetylcholine receptor (α7nAChR). This receptor is one of the signalling molecules regulating cytokine expression in macrophages. In this study, we characterize a novel teleost α7nAChR. Protein sequence analysis shows a high degree of conservation with mammalian orthologs and trout α7nAChR has all the features and essential amino acids to form a fully functional receptor. We demonstrate that trout macrophages can bind α-bungarotoxin (α-BTX), a competitive antagonist for α7nAChRs. Moreover, nicotine stimulation produces a decrease in pro-inflammatory cytokine expression after stimulation with poly(I:C). These results suggest the presence of a functional α7nAChR in the macrophage plasma membrane. Further, in vivo injection of poly(I:C) induced an increase in serum ACh levels in rainbow trout. Our results manifest for the first time the functional conservation of the inflammatory reflex in teleosts.
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Affiliation(s)
- Débora Torrealba
- Institut de Biotecnologia i de Biomedicina (IBB), Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain; Departament de Biologia Cel·lular, Fisiologia Animal i Immunologia, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain
| | - Joan Carles Balasch
- Departament de Biologia Cel·lular, Fisiologia Animal i Immunologia, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain
| | - Manuel Criado
- Instituto de Neurociencias, Universidad Miguel Hernández-CSIC, 03550 Sant Joan d'Alacant, Spain
| | - Lluís Tort
- Departament de Biologia Cel·lular, Fisiologia Animal i Immunologia, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain
| | - Simon Mackenzie
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, United Kingdom.
| | - Nerea Roher
- Institut de Biotecnologia i de Biomedicina (IBB), Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain; Departament de Biologia Cel·lular, Fisiologia Animal i Immunologia, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain.
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Belhareth R, Mezouar S, Ben Amara A, Chartier C, Azzouz EB, Chabrière E, Amri M, Mege JL. Cigarette smoke extract interferes with placenta macrophage functions: A new mechanism to compromise placenta functions? Reprod Toxicol 2018; 78:120-129. [PMID: 29673796 DOI: 10.1016/j.reprotox.2018.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 04/10/2018] [Accepted: 04/12/2018] [Indexed: 12/25/2022]
Abstract
The success of pregnancy depends on the maternal immune system's ability to promote tolerance and host defense. This equilibrium is compromised in inflammatory and infectious impairment of placenta. Smoking during pregnancy exposes the fetus to severe complications which might result from an alteration in placenta macrophages (pMφ) functions. In this study, we assessed the effect of cigarette smoke extract (CSE) on the functions of third trimester pMφs.CSE inhibited particles uptake and the formation of multinucleated giant cells, a recently reported property of pMφs based on their ability to fuse in vitro. These alterations were associated with a CSE-induced abnormal activation of pMφs, which was characterized by an increased release of TNF, interleukin (IL)-33, and decreased IL-6 and IL-10 release. Furthermore, CSE enhanced the expression of metalloproteinase genes known to be involved in tissue remodeling. This effect of CSE on pMφs was specific because CSE affected circulating monocytes in a different way. Finally, we showed that nicotine affected in part the functional properties of pMφs. Taken together, these results showed that CSE modulated the functional activity of pMφs, which may compromise pregnancy.
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Affiliation(s)
- Rym Belhareth
- Aix-Marseille University, Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes (URMITE), CNRS 7278, IRD 198, INSERM 1095, Marseille, France; Laboratoire de Neurophysiologie Fonctionnelle et Pathologies UR/11ES09, FST Campus Universitaire, 2092, El Manar Tunis, Tunisie
| | - Soraya Mezouar
- Aix-Marseille University, Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes (URMITE), CNRS 7278, IRD 198, INSERM 1095, Marseille, France
| | - Amira Ben Amara
- Aix-Marseille University, Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes (URMITE), CNRS 7278, IRD 198, INSERM 1095, Marseille, France
| | - Céline Chartier
- Aix-Marseille University, Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes (URMITE), CNRS 7278, IRD 198, INSERM 1095, Marseille, France
| | - Eya Ben Azzouz
- Aix-Marseille University, Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes (URMITE), CNRS 7278, IRD 198, INSERM 1095, Marseille, France
| | - Eric Chabrière
- Aix-Marseille University, Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes (URMITE), CNRS 7278, IRD 198, INSERM 1095, Marseille, France
| | - Mohamed Amri
- Laboratoire de Neurophysiologie Fonctionnelle et Pathologies UR/11ES09, FST Campus Universitaire, 2092, El Manar Tunis, Tunisie
| | - Jean-Louis Mege
- Aix-Marseille University, Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes (URMITE), CNRS 7278, IRD 198, INSERM 1095, Marseille, France.
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Vulfius CA, Kasheverov IE, Kryukova EV, Spirova EN, Shelukhina IV, Starkov VG, Andreeva TV, Faure G, Zouridakis M, Tsetlin VI, Utkin YN. Pancreatic and snake venom presynaptically active phospholipases A2 inhibit nicotinic acetylcholine receptors. PLoS One 2017; 12:e0186206. [PMID: 29023569 PMCID: PMC5638340 DOI: 10.1371/journal.pone.0186206] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 09/27/2017] [Indexed: 01/08/2023] Open
Abstract
Phospholipases A2 (PLA2s) are enzymes found throughout the animal kingdom. They hydrolyze phospholipids in the sn-2 position producing lysophospholipids and unsaturated fatty acids, agents that can damage membranes. PLA2s from snake venoms have numerous toxic effects, not all of which can be explained by phospholipid hydrolysis, and each enzyme has a specific effect. We have earlier demonstrated the capability of several snake venom PLA2s with different enzymatic, cytotoxic, anticoagulant and antiproliferative properties, to decrease acetylcholine-induced currents in Lymnaea stagnalis neurons, and to compete with α-bungarotoxin for binding to nicotinic acetylcholine receptors (nAChRs) and acetylcholine binding protein. Since nAChRs are implicated in postsynaptic and presynaptic activities, in this work we probe those PLA2s known to have strong presynaptic effects, namely β-bungarotoxin from Bungarus multicinctus and crotoxin from Crotalus durissus terrificus. We also wished to explore whether mammalian PLA2s interact with nAChRs, and have examined non-toxic PLA2 from porcine pancreas. It was found that porcine pancreatic PLA2 and presynaptic β-bungarotoxin blocked currents mediated by nAChRs in Lymnaea neurons with IC50s of 2.5 and 4.8 μM, respectively. Crotoxin competed with radioactive α-bungarotoxin for binding to Torpedo and human α7 nAChRs and to the acetylcholine binding protein. Pancreatic PLA2 interacted similarly with these targets; moreover, it inhibited radioactive α-bungarotoxin binding to the water-soluble extracellular domain of human α9 nAChR, and blocked acetylcholine induced currents in human α9α10 nAChRs heterologously expressed in Xenopus oocytes. These and our earlier results show that all snake PLA2s, including presynaptically active crotoxin and β-bungarotoxin, as well as mammalian pancreatic PLA2, interact with nAChRs. The data obtained suggest that this interaction may be a general property of all PLA2s, which should be proved by further experiments.
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Affiliation(s)
- Catherine A. Vulfius
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Igor E. Kasheverov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Elena V. Kryukova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Ekaterina N. Spirova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Irina V. Shelukhina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Vladislav G. Starkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Tatyana V. Andreeva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Grazyna Faure
- Unité Récepteurs-Canaux, Institut Pasteur, Paris, France
| | | | - Victor I. Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Yuri N. Utkin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
- * E-mail:
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Groot-Kormelink PJ, Ferrand S, Kelley N, Bill A, Freuler F, Imbert PE, Marelli A, Gerwin N, Sivilotti LG, Miraglia L, Orth AP, Oakeley EJ, Schopfer U, Siehler S. High Throughput Random Mutagenesis and Single Molecule Real Time Sequencing of the Muscle Nicotinic Acetylcholine Receptor. PLoS One 2016; 11:e0163129. [PMID: 27649498 PMCID: PMC5029940 DOI: 10.1371/journal.pone.0163129] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/03/2016] [Indexed: 12/15/2022] Open
Abstract
High throughput random mutagenesis is a powerful tool to identify which residues are important for the function of a protein, and gain insight into its structure-function relation. The human muscle nicotinic acetylcholine receptor was used to test whether this technique previously used for monomeric receptors can be applied to a pentameric ligand-gated ion channel. A mutant library for the α1 subunit of the channel was generated by error-prone PCR, and full length sequences of all 2816 mutants were retrieved using single molecule real time sequencing. Each α1 mutant was co-transfected with wildtype β1, δ, and ε subunits, and the channel function characterized by an ion flux assay. To test whether the strategy could map the structure-function relation of this receptor, we attempted to identify mutations that conferred resistance to competitive antagonists. Mutant hits were defined as receptors that responded to the nicotinic agonist epibatidine, but were not inhibited by either α-bungarotoxin or tubocurarine. Eight α1 subunit mutant hits were identified, six of which contained mutations at position Y233 or V275 in the transmembrane domain. Three single point mutations (Y233N, Y233H, and V275M) were studied further, and found to enhance the potencies of five channel agonists tested. This suggests that the mutations made the channel resistant to the antagonists, not by impairing antagonist binding, but rather by producing a gain-of-function phenotype, e.g. increased agonist sensitivity. Our data show that random high throughput mutagenesis is applicable to multimeric proteins to discover novel functional mutants, and outlines the benefits of using single molecule real time sequencing with regards to quality control of the mutant library as well as downstream mutant data interpretation.
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Affiliation(s)
- Paul J. Groot-Kormelink
- Musculoskeletal Disease Area, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Sandrine Ferrand
- Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Nicholas Kelley
- Analytical Sciences and Imaging, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Anke Bill
- Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States of America
| | - Felix Freuler
- Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Pierre-Eloi Imbert
- Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Anthony Marelli
- Genomics Institute of the Novartis Research Foundation, Novartis Institutes for BioMedical Research, San Diego, California, United States of America
| | - Nicole Gerwin
- Musculoskeletal Disease Area, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Lucia G. Sivilotti
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Loren Miraglia
- Genomics Institute of the Novartis Research Foundation, Novartis Institutes for BioMedical Research, San Diego, California, United States of America
| | - Anthony P. Orth
- Genomics Institute of the Novartis Research Foundation, Novartis Institutes for BioMedical Research, San Diego, California, United States of America
| | - Edward J. Oakeley
- Analytical Sciences and Imaging, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Ulrich Schopfer
- Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Sandra Siehler
- Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland
- * E-mail:
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Taillebois E, Thany SH. CHARACTERIZATION OF NICOTINE ACETYLCHOLINE RECEPTOR SUBUNITS IN THE COCKROACH Periplaneta americana MUSHROOM BODIES REVEALS A STRONG EXPRESSION OF β1 SUBUNIT: INVOLVEMENT IN NICOTINE-INDUCED CURRENTS. Arch Insect Biochem Physiol 2016; 93:40-54. [PMID: 27357353 DOI: 10.1002/arch.21340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Nicotinic acetylcholine receptors are ligand-gated ion channels expressed in many insect structures, such as mushroom bodies, in which they play a central role. We have recently demonstrated using electrophysiological recordings that different native nicotinic receptors are expressed in cockroach mushroom bodies Kenyon cells. In the present study, we demonstrated that eight genes coding for cockroach nicotinic acetylcholine receptor subunits are expressed in the mushroom bodies. Quantitative real-time polymerase chain reaction (PCR) experiments demonstrated that β1 subunit was the most expressed in the mushroom bodies. Moreover, antisense oligonucleotides performed against β1 subunit revealed that inhibition of β1 expression strongly decreases nicotine-induced currents amplitudes. Moreover, co-application with 0.5 μM α-bungarotoxin completely inhibited nicotine currents whereas 10 μM d-tubocurarine had a partial effect demonstrating that β1-containing neuronal nicotinic acetylcholine receptor subtypes could be sensitive to the nicotinic acetylcholine receptor antagonist α-bungarotoxin.
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Affiliation(s)
- Emiliane Taillebois
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), Université d'Angers, Angers, France
| | - Steeve H Thany
- Laboratoire de Biologie des Ligneux et des Grandes Cultures (LBLGC), Université d'Orléans, Orléans, France
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10
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Chen W, Carvalho LPD, Chan MY, Kini RM, Kang TS. Fasxiator, a novel factor XIa inhibitor from snake venom, and its site-specific mutagenesis to improve potency and selectivity. J Thromb Haemost 2015; 13:248-61. [PMID: 25418421 DOI: 10.1111/jth.12797] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 11/11/2014] [Indexed: 02/03/2023]
Abstract
BACKGROUND Bleeding remains a major limitation of standard anticoagulant drugs that target the extrinsic and common coagulation pathways. Recently, intrinsic coagulation factors are increasingly being investigated as alternative targets for developing anticoagulant drugs with lower bleeding risk. OBJECTIVES Goals were to (i) identify novel anticoagulants selectively targeting intrinsic coagulation pathway and (ii) characterize and further improve the properties of the identified anticoagulants. METHODS AND RESULTS We have isolated and sequenced a specific factor XIa (FXIa) inhibitor, henceforth named Fasxiator, from the venom of the banded krait snake, Bungarus fasciatus. It is a Kunitz-type protease inhibitor that prolonged activated partial thromboplastin time without significant effects on prothrombin time. Fasxiator was recombinantly expressed (rFasxiator), purified, and characterized to be a slow-type inhibitor of FXIa that exerts its anticoagulant activities (doubled activated partial thromboplastin time at ~ 3 μmol L(-1) ) by selectively inhibiting human FXIa in in vitro assays. A series of mutants were subsequently generated to improve the potency and selectivity of recombinant rFasxiator. rFasxiatorN17R,L19E showed the best balance between potency (IC50 ~ 1 nmol L(-1) ) and selectivity (> 100 times). rFasxiatorN17R,L19E is a competitive slow-type inhibitor of FXIa (Ki = 0.86 nmol L(-1) ), possesses anticoagulant activity that is ~ 10 times stronger in human plasma than in murine plasma, and prolonged the occlusion time of mice carotid artery in FeCl3 -induced thrombosis models. CONCLUSION We have isolated an exogenous FXIa specific inhibitor, engineered it to improve its potency by ~ 1000 times and demonstrated its in vitro and in vivo efficacy. These proof-of-principle data supported the further development of Fasxiator as a novel anticoagulant candidate.
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Affiliation(s)
- W Chen
- Department of Pharmacy, National University of Singapore, Singapore City, Singapore
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11
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Mahgoub M, Keun-Hang SY, Sydorenko V, Ashoor A, Kabbani N, Al Kury L, Sadek B, Howarth CF, Isaev D, Galadari S, Oz M. Effects of cannabidiol on the function of α7-nicotinic acetylcholine receptors. Eur J Pharmacol 2013; 720:310-9. [PMID: 24140434 DOI: 10.1016/j.ejphar.2013.10.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Revised: 09/16/2013] [Accepted: 10/07/2013] [Indexed: 11/18/2022]
Abstract
The effects of cannabidiol (CBD), a non-psychoactive ingredient of cannabis plant, on the function of the cloned α7 subunit of the human nicotinic acetylcholine (α7 nACh) receptor expressed in Xenopus oocytes were tested using the two-electrode voltage-clamp technique. CBD reversibly inhibited ACh (100 μM)-induced currents with an IC50 value of 11.3 µM. Other phytocannabinoids such as cannabinol and Δ(9)-tetrahydrocannabinol did not affect ACh-induced currents. CBD inhibition was not altered by pertussis toxin treatment. In addition, CBD did not change GTP-γ-S binding to the membranes of oocytes injected with α7 nACh receptor cRNA. The effect of CBD was not dependent on the membrane potential. CBD (10 µM) did not affect the activity of endogenous Ca(2+)-dependent Cl(-) channels, since the extent of inhibition by CBD was unaltered by intracellular injection of the Ca(2+) chelator BAPTA and perfusion with Ca(2+)-free bathing solution containing 2mM Ba(2+). Inhibition by CBD was not reversed by increasing ACh concentrations. Furthermore, specific binding of [(125)I] α-bungarotoxin was not inhibited by CBD (10 µM) in oocytes membranes. Using whole cell patch clamp technique in CA1 stratum radiatum interneurons of rat hippocampal slices, currents induced by choline, a selective-agonist of α7-receptor induced currents were also recoded. Bath application of CBD (10 µM) for 10 min caused a significant inhibition of choline induced currents. Finally, in hippocampal slices, [(3)H] norepinephrine release evoked by nicotine (30 µM) was also inhibited by 10 µM CBD. Our results indicate that CBD inhibits the function of the α7-nACh receptor.
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Affiliation(s)
- Mohamed Mahgoub
- Laboratory of Functional Lipidomics, Department of Pharmacology, College of Medicine and Health Sciences, UAE University, Abu Dhabi, Al Ain, United Arab Emirates
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12
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Du MH, Luo HM, Hu S, Lv Y, Lin ZL, Ma L. Electroacupuncture improves gut barrier dysfunction in prolonged hemorrhagic shock rats through vagus anti-inflammatory mechanism. World J Gastroenterol 2013; 19:5988-5999. [PMID: 24106399 PMCID: PMC3785620 DOI: 10.3748/wjg.v19.i36.5988] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 07/11/2013] [Accepted: 08/17/2013] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate whether electroacupuncture (EA) at Zusanli (ST36) prevents intestinal barrier and remote organ dysfunction following prolonged hemorrhagic shock through a vagus anti-inflammatory mechanism.
METHODS: Sprague-Dawley rats were subjected to about 45% of total blood volume loss followed by delayed fluid replacement (DFR) with Ringer lactate 3h after hemorrhage. In a first study, rats were randomly divided into six groups: (1) EAN: EA at non-channel acupoints followed by DFR; (2) EA: EA at ST36 after hemorrhage followed by DFR; (3) VGX/EA: vagotomy (VGX) before EA at ST36 and DFR; (4) VGX/EAN: VGX before EAN and DFR; (5) α-bungarotoxin (α-BGT)/EA: intraperitoneal injection of α-BGT before hemorrhage, followed by EA at ST36 and DFR; and (6) α-BGT/EAN group: α-BGT injection before hemorrhage followed by EAN and DFR. Survival and mean arterial pressure (MAP) were monitored over the next 12 h. In a second study, with the same grouping and treatment, cytokine levels in plasma and intestine, organ parameters, gut injury score, gut permeability to 4 kDa FITC-dextran, and expression and distribution of tight junction protein ZO-1 were evaluated.
RESULTS: MAP was significantly lowered after blood loss; EA at ST36 improved the blood pressure at corresponding time points 3 and 12 h after hemorrhage. EA at ST36 reduced tumor necrosis factor-α and interleukin (IL)-6 levels in both plasma and intestine homogenates after blood loss and DFR, while vagotomy or intraperitoneal injection of α-BGT before EA at ST36 reversed its anti-inflammatory effects, and EA at ST36 did not influence IL-10 levels in plasma and intestine. EA at ST36 alleviated the injury of intestinal villus, the gut injury score being significantly lower than that of EAN group (1.85 ± 0.33 vs 3.78 ± 0.59, P < 0.05). EA at ST36 decreased intestinal permeability to FITC-dextran compared with EAN group (856.95 ng/mL ± 90.65 ng/mL vs 2305.62 ng/mL ± 278.32 ng/mL, P < 0.05). EA at ST36 significantly preserved ZO-1 protein expression and localization at 12 h after hemorrhage. However, EA at non-channel acupoints had no such effect, and abdominal vagotomy and α-BGT treatment could weaken or eliminate the effects of EA at ST36. Besides, EA at ST36 decreased blood aminotransferase, MB isoenzyme of creatine kinase and creatinine vs EAN group at corresponding time points. At the end of 12-h experiment, the survival rate of the EA group was significantly higher than that of the other groups.
CONCLUSION: EA at ST36 attenuates the systemic inflammatory response, protects intestinal barrier integrity, improves organ function and survival rate after hemorrhagic shock via activating the cholinergic anti-inflammatory mechanism.
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13
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Ali SA, Yang DC, Jackson TNW, Undheim EAB, Koludarov I, Wood K, Jones A, Hodgson WC, McCarthy S, Ruder T, Fry BG. Venom proteomic characterization and relative antivenom neutralization of two medically important Pakistani elapid snakes (Bungarus sindanus and Naja naja). J Proteomics 2013; 89:15-23. [PMID: 23714137 DOI: 10.1016/j.jprot.2013.05.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 05/01/2013] [Accepted: 05/06/2013] [Indexed: 11/17/2022]
Abstract
UNLABELLED Intra- and interspecific variation in venom composition has been shown to have a major effect upon the efficacy of antivenoms. Due to the absence of domestically produced antivenoms, Pakistan is wholly reliant upon antivenoms produced in other countries, such as India. However, the efficacy of these antivenoms in neutralising the venoms of Pakistani snakes has not been ascertained. This is symptomatic of the general state of toxicological research in this country, which has a myriad of highly toxic and medically important venomous animals. Thus, there is a dire need for knowledge regarding the fundamental proteomics of these venoms and applied knowledge of the relative efficacy of foreign antivenoms. Here we present the results of our proteomic research on two medically important snakes of Pakistan: Bungarus sindanus and Naja naja. Indian Polyvalent Antivenom (Bharat Serums and Vaccines Ltd), which is currently marketed for use in Pakistan, was completely ineffective against either Pakistani species. In addition to the expected pre- and post-synaptic neurotoxic activity, the venom of the Pakistan population of N. naja was shown to be quite divergent from other populations of this species in being potently myotoxic. These results highlight the importance of studying divergent species and isolated populations, where the same data not only elucidates clinical problems in need of immediate attention, but also uncovers sources for novel toxins with potentially useful activities. BIOLOGICAL SIGNIFICANCE Pakistan Bungarus sindanus and Naja naja venoms are differentially complex. Naja naja is potently myotoxic. Neither venom is neutralized by Indian antivenom. These results have direct implications for the treatment of envenomed patients in Pakistan. The unusually myotoxic effects of Naja naja demonstrates the value of studying remote populations for biodiscovery.
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Affiliation(s)
- Syed A Ali
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia, Qld 4072, Australia
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14
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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 Mol Biol 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] [What about the content of this article? (0)] [Affiliation(s)] [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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15
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Tanaka H, Tanabe N, Kawato T, Nakai K, Kariya T, Matsumoto S, Zhao N, Motohashi M, Maeno M. Nicotine affects bone resorption and suppresses the expression of cathepsin K, MMP-9 and vacuolar-type H(+)-ATPase d2 and actin organization in osteoclasts. PLoS One 2013; 8:e59402. [PMID: 23555029 PMCID: PMC3598738 DOI: 10.1371/journal.pone.0059402] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 02/16/2013] [Indexed: 11/18/2022] Open
Abstract
Tobacco smoking is an important risk factor for the development of several cancers, osteoporosis, and inflammatory diseases such as periodontitis. Nicotine is one of the major components of tobacco. In previous study, we showed that nicotine inhibits mineralized nodule formation by osteoblasts, and the culture medium from osteoblasts containing nicotine and lipopolysaccharide increases osteoclast differentiation. However, the direct effect of nicotine on the differentiation and function of osteoclasts is poorly understood. Thus, we examined the direct effects of nicotine on the expression of nicotine receptors and bone resorption-related enzymes, mineral resorption, actin organization, and bone resorption using RAW264.7 cells and bone marrow cells as osteoclast precursors. Cells were cultured with 10(-5), 10(-4), or 10(-3) M nicotine and/or 50 µM α-bungarotoxin (btx), an 7 nicotine receptor antagonist, in differentiation medium containing the soluble RANKL for up 7 days. 1-5, 7, 9, and 10 nicotine receptors were expressed on RAW264.7 cells. The expression of 7 nicotine receptor was increased by the addition of nicotine. Nicotine suppressed the number of tartrate-resistant acid phosphatase positive multinuclear osteoclasts with large nuclei(≥10 nuclei), and decreased the planar area of each cell. Nicotine decreased expression of cathepsin K, MMP-9, and V-ATPase d2. Btx inhibited nicotine effects. Nicotine increased CA II expression although decreased the expression of V-ATPase d2 and the distribution of F-actin. Nicotine suppressed the planar area of resorption pit by osteoclasts, but did not affect mineral resorption. These results suggest that nicotine increased the number of osteoclasts with small nuclei, but suppressed the number of osteoclasts with large nuclei. Moreover, nicotine reduced the planar area of resorption pit by suppressing the number of osteoclasts with large nuclei, V-ATPase d2, cathepsin K and MMP-9 expression and actin organization.
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Affiliation(s)
- Hideki Tanaka
- Department of Oral Health Sciences, Nihon University School of Dentistry, Tokyo, Japan
| | - Natsuko Tanabe
- Department of Biochemistry, Nihon University School of Dentistry, Tokyo, Japan
- Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
| | - Takayuki Kawato
- Department of Oral Health Sciences, Nihon University School of Dentistry, Tokyo, Japan
- Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
| | - Kumiko Nakai
- Nihon University Graduate School of Dentistry, Tokyo, Japan
| | - Taro Kariya
- Nihon University Graduate School of Dentistry, Tokyo, Japan
| | | | - Ning Zhao
- Department of Biochemistry, Nihon University School of Dentistry, Tokyo, Japan
- Department of Endodontics, School of Dentistry, Shandong University, Jinan, Shandong Province, People's Republic of China
| | - Masafumi Motohashi
- Department of Oral Health Sciences, Nihon University School of Dentistry, Tokyo, Japan
- Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
| | - Masao Maeno
- Department of Oral Health Sciences, Nihon University School of Dentistry, Tokyo, Japan
- Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
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Raskin K, Marie-Luce C, Picot M, Bernard V, Mailly P, Hardin-Pouzet H, Tronche F, Mhaouty-Kodja S. Characterization of the spinal nucleus of the bulbocavernosus neuromuscular system in male mice lacking androgen receptor in the nervous system. Endocrinology 2012; 153:3376-85. [PMID: 22585832 DOI: 10.1210/en.2012-1001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Motoneurons in the spinal nucleus of the bulbocavernosus (SNB) and their target bulbocavernosus (BC) and levator ani (LA) muscles play a role in male copulation and fertility. Testosterone (T) induces sexual differentiation of this SNB neuromuscular system during development and maintains its activation in adulthood. In the rat, T-induced effects mostly involve the androgen receptor (AR). However, the role of central AR in T-induced effects remains to be studied with pertinent genetic models. We addressed this question by using specific motoneuron immunolabeling and retrograde tracing in mice selectively disrupted for AR in the nervous system. This work reveals that nervous system AR is not required either for T-induced development of BC-LA muscles and perinatal sparing of SNB motoneurons from atrophy or for adult sensitivity of BC-LA muscles to T. By contrast, loss of AR expression in the nervous system resulted in SNB motoneurons having smaller somata and shorter dendrites than controls. We studied the effects of adult castration and T supplementation on SNB cell morphology in control and mutant males; these experiments showed that central AR is involved in the developmental regulation of soma size and dendritic length and in the adult maintenance of soma size of SNB motoneurons. T seemed to act indirectly through BC-LA muscles to maintain dendritic length in adulthood. Our results also suggest that central AR functions may contribute to normal activity of SNB motoneurons and perineal muscles because mutant mice displayed diminished copulatory behavior and fertility.
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Affiliation(s)
- Kalina Raskin
- Centre National de la Recherche Scientifique Unité Mixte de Recherche 7224, and Université Pierre et Marie Curie, 75005 Paris Cedex 05, France
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17
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Kim SY, Kang KL, Lee JC, Heo JS. Nicotinic acetylcholine receptor α7 and β4 subunits contribute nicotine-induced apoptosis in periodontal ligament stem cells. Mol Cells 2012; 33:343-50. [PMID: 22382680 PMCID: PMC3887805 DOI: 10.1007/s10059-012-2172-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 01/06/2012] [Accepted: 01/18/2012] [Indexed: 12/14/2022] Open
Abstract
Nicotine, a major component of cigarette smoking, is the important risk factor for the development of periodontal disease. However, the mechanisms that underlie the cytotoxicity of nicotine in human periodontal ligament stem cells (PDLSCs) are largely unknown. Thus, the purpose of this study was to determine the cytotoxic effect of nicotine by means of nicotinic acetylcholine receptor (nAChR) activation in PDLSCs. We first detected α7 and β4 nAChRs in PDLSCs. The gene expressions of α7 and β4 nAChR were increased by nicotine administration. Nicotine significantly decreased cell viability at a concentration higher than 10(-5) M. DNA fragmentation was also detected at high doses of nicotine treatment. Moreover, the detection of sub G1 phase and TUNEL assay demonstrated that nicotine significantly induced apoptotic cell death at 10(-2) M concentration. Western blot analysis confirmed that p53 proteins were phosphorylated by nicotine. Under various doses of nicotine, a decrease in the anti-apoptotic protein Bcl-2, but an increase in p53 and cleaved caspase-3 protein levels, was detected in a dose-dependent manner. However, the apoptotic effect of nicotine was inhibited by the pretreatment of α-bungarotoxin, a selective α7 nAChR antagonist or mecamylamine, a non-selective nAChR antagonist. Finally, increases in the subG1 phase and DNA fragmentation by nicotine was attenuated by each nAChR antagonist. Collectively, the presence of α7 and β4 nAChRs in PDLSCs supports a key role of nAChRs in the modulation of nicotine-induced apoptosis.
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Affiliation(s)
- So Yeon Kim
- Department of Maxillofacial Biomedical Engineering and Institute of Oral Biology, School of Dentistry, Kyung Hee University, Seoul 130-701,
Korea
| | - Kyung Lhi Kang
- Department of Periodontology, School of Dentistry, Kyung Hee University, Seoul 130-701,
Korea
| | - Jeong-Chae Lee
- Institute of Oral Biosciences, Cluster for CraniofacialDevelopment and Regeneration Research and School of Dentistry (Brain Korea 21 Program), Chonbuk National University, Jeonju 561-756,
Korea
| | - Jung Sun Heo
- Department of Maxillofacial Biomedical Engineering and Institute of Oral Biology, School of Dentistry, Kyung Hee University, Seoul 130-701,
Korea
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18
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Alamanda V, Singh S, Lawrence NJ, Chellappan SP. Nicotine-mediated induction of E-selectin in aortic endothelial cells requires Src kinase and E2F1 transcriptional activity. Biochem Biophys Res Commun 2012; 418:56-61. [PMID: 22240023 DOI: 10.1016/j.bbrc.2011.12.127] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 12/25/2011] [Indexed: 01/19/2023]
Abstract
Smoking is highly correlated with enhanced likelihood of atherosclerosis by inducing endothelial dysfunction. In endothelial cells, various cell-adhesion molecules including E-selectin, are shown to be upregulated upon exposure to nicotine, the addictive component of tobacco smoke; however, the molecular mechanisms underlying this induction are poorly understood. Here we demonstrate that nicotine-induced E-selectin transcription in human aortic endothelial cells (HAECs) could be significantly blocked by α7-nAChR subunit inhibitor, α-BT, Src-kinase inhibitor, PP2, or siRNAs against Src or β-Arrestin-1 (β-Arr1). Further, chromatin immunoprecipitations show that E-selectin is an E2F1 responsive gene and nicotine stimulation results in increased recruitment of E2F1 on E-selectin promoter. Inhibiting E2F1 activity using RRD-251, a disruptor of the Rb-Raf-1 kinase interaction, could significantly inhibit the nicotine-induced recruitment of E2F1 to the E-selectin promoter as well as E-selectin expression. Interestingly, stimulation of HAECs with nicotine results in increased adhesion of U937 monocytic cells to HAECs and could be inhibited by pre-treatment with RRD-251. Similarly, depletion of E2F1 or Src using RNAi blocked the increased adhesion of monocytes to nicotine-stimulated HAECs. These results suggest that nicotine-stimulated adhesion of monocytes to endothelial cells is dependent on the activation of α7-nAChRs, β-Arr1 and cSrc regulated increase in E2F1-mediated transcription of E-selectin gene. Therefore, agents such as RRD-251 that can target activity of E2F1 may have potential therapeutic benefit against cigarette smoke induced atherosclerosis.
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Affiliation(s)
- Vignesh Alamanda
- Department of Tumor Biology, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, USA
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19
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Araud T, Graw S, Berger R, Lee M, Neveu E, Bertrand D, Leonard S. The chimeric gene CHRFAM7A, a partial duplication of the CHRNA7 gene, is a dominant negative regulator of α7*nAChR function. Biochem Pharmacol 2011; 82:904-14. [PMID: 21718690 PMCID: PMC3162115 DOI: 10.1016/j.bcp.2011.06.018] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 06/10/2011] [Accepted: 06/13/2011] [Indexed: 12/11/2022]
Abstract
The human α7 neuronal nicotinic acetylcholine receptor gene (CHRNA7) is a candidate gene for schizophrenia and an important drug target for cognitive deficits in the disorder. Activation of the α7*nAChR, results in opening of the channel and entry of mono- and divalent cations, including Ca(2+), that presynaptically participates to neurotransmitter release and postsynaptically to down-stream changes in gene expression. Schizophrenic patients have low levels of α7*nAChR, as measured by binding of the ligand [(125)I]-α-bungarotoxin (I-BTX). The structure of the gene, CHRNA7, is complex. During evolution, CHRNA7 was partially duplicated as a chimeric gene (CHRFAM7A), which is expressed in the human brain and elsewhere in the body. The association between a 2bp deletion in CHRFAM7A and schizophrenia suggested that this duplicate gene might contribute to cognitive impairment. To examine the putative contribution of CHRFAM7A on receptor function, co-expression of α7 and the duplicate genes was carried out in cell lines and Xenopus oocytes. Expression of the duplicate alone yielded protein expression but no functional receptor and co-expression with α7 caused a significant reduction of the amplitude of the ACh-evoked currents. Reduced current amplitude was not correlated with a reduction of I-BTX binding, suggesting the presence of non-functional (ACh-silent) receptors. This hypothesis is supported by a larger increase of the ACh-evoked current by the allosteric modulator 1-(5-chloro-2,4-dimethoxy-phenyl)-3-(5-methyl-isoxazol-3-yl)-urea (PNU-120596) in cells expressing the duplicate than in the control. These results suggest that CHRFAM7A acts as a dominant negative modulator of CHRNA7 function and is critical for receptor regulation in humans.
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Affiliation(s)
- Tanguy Araud
- Department of Neurosciences Medical Faculty, University of Geneva, Geneva, Switzerland.
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20
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Yu M, Liu Q, Sun J, Yi K, Wu L, Tan X. Nicotine improves the functional activity of late endothelial progenitor cells via nicotinic acetylcholine receptors. Biochem Cell Biol 2011; 89:405-10. [PMID: 21774635 DOI: 10.1139/o11-032] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The aim of this study is to investigate whether nicotinic acetylcholine receptors (nAChRs) are involved in the modulation of functional activity of late endothelial progenitor cells (EPCs) induced by nicotine. Total mononuclear cells (MNCs) were isolated from human umbilical cord blood by Ficoll density gradient centrifugation, and then the cells were plated on fibronectin-coated culture plates. Late EPCs were positive for 1,1-dioctadecyl-3,3,3,3-tetramethylindocarbocyanine-labeled acetylated low-density lipoprotein (DiI-acLDL) uptake and fluorescein-isothiocyanate-conjugated Ulex europaeus agglutinin lectin (UEA-1) binding. Expression of von Willbrand factor (vWF), kinase insert domain receptor (KDR), and α7 nAChR was detected by indirect immunofluorescence staining. Late EPCs of 3-5 passages were treated for 32 h with either vehicle or nicotine with or without pre-incubation of nAChR antagonism, mecamylamine, or α-bungarotoxin. The viability, migration, and in vitro vasculogenesis activity of late EPCs were assayed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, modified Boyden chamber assay, and in vitro angiogenesis assay, respectively. Late EPCs adhesion assay was performed by replating cells on fibronectin-coated plates, and then adherent cells were counted. Incubation with 10 nmol/L nicotine enhanced viable, migratory, adhesive, and in vitro vasculogenesis capacity of late EPCs. The effect of nicotine on late EPCs can be attenuated by mecamylamine or α-bungarotoxin. In conclusion, nicotine improves the functional activity of late EPCs via nAChRs.
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Affiliation(s)
- Min Yu
- Department of Cardiology, the First Affiliated Hospital, Shantou University Medical College, Guangdong, China
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Hannan S, Wilkins ME, Dehghani-Tafti E, Thomas P, Baddeley SM, Smart TG. Gamma-aminobutyric acid type B (GABA(B)) receptor internalization is regulated by the R2 subunit. J Biol Chem 2011; 286:24324-35. [PMID: 21724853 PMCID: PMC3129212 DOI: 10.1074/jbc.m110.220814] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 04/20/2011] [Indexed: 01/04/2023] Open
Abstract
γ-Aminobutyric acid type B (GABA(B)) receptors are important for slow synaptic inhibition in the CNS. The efficacy of inhibition is directly related to the stability of cell surface receptors. For GABA(B) receptors, heterodimerization between R1 and R2 subunits is critical for cell surface expression and signaling, but how this determines the rate and extent of receptor internalization is unknown. Here, we insert a high affinity α-bungarotoxin binding site into the N terminus of the R2 subunit and reveal its dominant role in regulating the internalization of GABA(B) receptors in live cells. To simultaneously study R1a and R2 trafficking, a new α-bungarotoxin binding site-labeling technique was used, allowing α-bungarotoxin conjugated to different fluorophores to selectively label R1a and R2 subunits. This approach demonstrated that R1a and R2 are internalized as dimers. In heterologous expression systems and neurons, the rates and extents of internalization for R1aR2 heteromers and R2 homomers are similar, suggesting a regulatory role for R2 in determining cell surface receptor stability. The fast internalization rate of R1a, which has been engineered to exit the endoplasmic reticulum, was slowed to that of R2 by truncating the R1a C-terminal tail or by removing a dileucine motif in its coiled-coil domain. Slowing the rate of internalization by co-assembly with R2 represents a novel role for GPCR heterodimerization whereby R2 subunits, via their C terminus coiled-coil domain, mask a dileucine motif on R1a subunits to determine the surface stability of the GABA(B) receptor.
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Affiliation(s)
- Saad Hannan
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom and
- GlaxoSmithKline R&D, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom
| | - Megan E. Wilkins
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom and
| | - Ebrahim Dehghani-Tafti
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom and
| | - Philip Thomas
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom and
| | - Stuart M. Baddeley
- GlaxoSmithKline R&D, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom
| | - Trevor G. Smart
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom and
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22
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Rehan VK, Sakurai R, Torday JS. Thirdhand smoke: a new dimension to the effects of cigarette smoke on the developing lung. Am J Physiol Lung Cell Mol Physiol 2011; 301:L1-8. [PMID: 21478255 PMCID: PMC3129897 DOI: 10.1152/ajplung.00393.2010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Accepted: 04/08/2011] [Indexed: 11/22/2022] Open
Abstract
The underlying mechanisms and effector molecules involved in mediating in utero smoke exposure-induced effects on the developing lung are only beginning to be understood. However, the effects of a newly discovered category of smoke, i.e., thirdhand smoke (THS), on the developing lung are completely unknown. We hypothesized that, in addition to nicotine, other components of THS would also affect lung development adversely. Fetal rat lung explants were exposed to nicotine, 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal (NNA), or 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), the two main tobacco-specific N-nitrosamine constituents of THS, for 24 h. We then determined key markers for alveolar paracrine signaling [epithelial differentiation markers surfactant phospholipid and protein synthesis; mesenchymal differentiation markers peroxisome proliferator-activated receptor γ (PPAR-γ), fibronectin and calponin], the BCL-2-to-Bax ratio (BCL-2/Bax), a marker of apoptosis and the involvement of nicotinic acetylcholine receptors (nAChR)-α3 and -α7 in mediating NNA's and NNK's effects on the developing lung. Similar to the effects of nicotine, exposure of the developing lung to either NNK or NNA resulted in disrupted homeostatic signaling, indicated by the downregulation of PPAR-γ, upregulation of fibronectin and calponin protein levels, decreased BCL-2/Bax, and the accompanying compensatory stimulation of surfactant phospholipid and protein synthesis. Furthermore, nAChR-α3 and -α7 had differential complex roles in mediating these effects. NNK and NNA exposure resulted in breakdown of alveolar epithelial-mesenchymal cross-talk, reflecting lipofibroblast-to-myofibroblast transdifferentiation, suggesting THS constituents as possible novel contributors to in utero smoke exposure-induced pulmonary damage. These data are particularly relevant for designing specific therapeutic strategies, and for formulating public health policies to minimize THS exposure.
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Affiliation(s)
- Virender K Rehan
- Departments of Pediatrics, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California 90502, USA.
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23
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Li Q, Zhou XD, Kolosov VP, Perelman JM. Nicotine reduces TNF-α expression through a α7 nAChR/MyD88/NF-ĸB pathway in HBE16 airway epithelial cells. Cell Physiol Biochem 2011; 27:605-12. [PMID: 21691078 DOI: 10.1159/000329982] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2011] [Indexed: 12/26/2022] Open
Abstract
AIMS To explore the signaling mechanism associated with the inhibitory effect of nicotine on tumor necrosis factor (TNF)- α expression in human airway epithelial cells. METHODS HBE16 airway epithelial cells were cultured and incubated with either nicotine or cigarette smoke extract (CE). Cells were then transfected with α1, α5, or α7 nicotinic acetylcholine receptor (nAChR)-specific small interfering RNAs (siRNAs). The effects of nicotine on the production of proinflammatory factors TNF-α, in transfected cells were analyzed. Furthermore, we assayed the expression levels of myeloid differentiation primary response gene 88 (MyD88) protein, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 protein, NF-κB activity and NF-κB inhibitor alpha (I-κBα) expression in cells after treatment with nicotine or α7 nAChR inhibitor, α -bungarotoxin (α-BTX). RESULTS The production of TNF-α was lower in cells pretreated with nicotine before lipopolysaccharide (LPS) stimulation, compared with LPS-only-treated cells. In contrast, in α7 siRNA-transfected cells incubated with nicotine and LPS, TNF-α expression was higher than that in non-transfected cells or in α1 or α5 siRNA-transfected cells. Addition of MyD88 siRNA or the NF-κB inhibitor pyridine-2,6-dithiocarboxylic acid (PDTC) also reduced TNF-α expression. Furthermore, we found that nicotine decreased MyD88 protein, NF-κB p65 protein, NF-κB activity and phospho-I-κBα expression induced by CE or LPS. The inhibitor α-BTX could reverse these effects. CONCLUSION Nicotine reduces TNF-α expression in HBE16 airway epithelial cells, mainly through an α7 nAChR/MyD88/NF-κB pathway.
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Affiliation(s)
- Qi Li
- Department of Respiratory Medicine, Second Affiliated Hospital, Chongqing Medical University, Chongqing, P.R. China
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24
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Lyukmanova EN, Shenkarev ZO, Shulepko MA, Mineev KS, D'Hoedt D, Kasheverov IE, Filkin SY, Krivolapova AP, Janickova H, Dolezal V, Dolgikh DA, Arseniev AS, Bertrand D, Tsetlin VI, Kirpichnikov MP. NMR structure and action on nicotinic acetylcholine receptors of water-soluble domain of human LYNX1. J Biol Chem 2011; 286:10618-27. [PMID: 21252236 PMCID: PMC3060513 DOI: 10.1074/jbc.m110.189100] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 12/20/2010] [Indexed: 12/26/2022] Open
Abstract
Discovery of proteins expressed in the central nervous system sharing the three-finger structure with snake α-neurotoxins provoked much interest to their role in brain functions. Prototoxin LYNX1, having homology both to Ly6 proteins and three-finger neurotoxins, is the first identified member of this family membrane-tethered by a GPI anchor, which considerably complicates in vitro studies. We report for the first time the NMR spatial structure for the water-soluble domain of human LYNX1 lacking a GPI anchor (ws-LYNX1) and its concentration-dependent activity on nicotinic acetylcholine receptors (nAChRs). At 5-30 μM, ws-LYNX1 competed with (125)I-α-bungarotoxin for binding to the acetylcholine-binding proteins (AChBPs) and to Torpedo nAChR. Exposure of Xenopus oocytes expressing α7 nAChRs to 1 μM ws-LYNX1 enhanced the response to acetylcholine, but no effect was detected on α4β2 and α3β2 nAChRs. Increasing ws-LYNX1 concentration to 10 μM caused a modest inhibition of these three nAChR subtypes. A common feature for ws-LYNX1 and LYNX1 is a decrease of nAChR sensitivity to high concentrations of acetylcholine. NMR and functional analysis both demonstrate that ws-LYNX1 is an appropriate model to shed light on the mechanism of LYNX1 action. Computer modeling, based on ws-LYNX1 NMR structure and AChBP x-ray structure, revealed a possible mode of ws-LYNX1 binding.
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Affiliation(s)
- Ekaterina N. Lyukmanova
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Zakhar O. Shenkarev
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Mikhail A. Shulepko
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Konstantin S. Mineev
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Dieter D'Hoedt
- the Department of Neuroscience, Centre Medical Universitaire, 1 Rue Michel Servet, 1211 Geneva 4, Switzerland
| | - Igor E. Kasheverov
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Sergey Yu. Filkin
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Alexandra P. Krivolapova
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Helena Janickova
- the Institute of Physiology, Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic, and
| | - Vladimir Dolezal
- the Institute of Physiology, Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic, and
| | - Dmitry A. Dolgikh
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
- Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Alexander S. Arseniev
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Daniel Bertrand
- the Department of Neuroscience, Centre Medical Universitaire, 1 Rue Michel Servet, 1211 Geneva 4, Switzerland
| | - Victor I. Tsetlin
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
| | - Mikhail P. Kirpichnikov
- From the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia
- Lomonosov Moscow State University, 119991 Moscow, Russia
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25
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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 Biochem Mol Biol 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] [What about the content of this article? (0)] [Affiliation(s)] [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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26
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Osman AA, Schrader AD, Hawkes AJ, Akil O, Bergeron A, Lustig LR, Simmons DD. Muscle-like nicotinic receptor accessory molecules in sensory hair cells of the inner ear. Mol Cell Neurosci 2008; 38:153-69. [PMID: 18420419 PMCID: PMC2480618 DOI: 10.1016/j.mcn.2008.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 01/28/2008] [Accepted: 02/12/2008] [Indexed: 11/30/2022] Open
Abstract
Nothing is known about the regulation of nicotinic acetylcholine receptors (nAChRs) in hair cells of the inner ear. MuSK, rapsyn and RIC-3 are accessory molecules associated with muscle and brain nAChR function. We demonstrate that these accessory molecules are expressed in the inner ear raising the possibility of a muscle-like mechanism for clustering and assembly of nAChRs in hair cells. We focused our investigations on rapsyn and RIC-3. Rapsyn interacts with the cytoplasmic loop of nAChR alpha9 subunits but not nAChR alpha10 subunits. Although rapsyn and RIC-3 increase nAChR alpha9 expression, rapsyn plays a greater role in receptor clustering while RIC-3 is important for acetylcholine-induced calcium responses. Our data suggest that RIC-3 facilitates receptor function, while rapsyn enhances receptor clustering at the cell surface.
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MESH Headings
- Animals
- Bungarotoxins/pharmacology
- Calcium/metabolism
- Female
- Hair Cells, Auditory, Inner/cytology
- Hair Cells, Auditory, Inner/metabolism
- Humans
- Intracellular Signaling Peptides and Proteins/genetics
- Intracellular Signaling Peptides and Proteins/metabolism
- Kidney/cytology
- LLC-PK1 Cells
- Male
- Mice
- Mice, Inbred C57BL
- Muscle Proteins/metabolism
- Pregnancy
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor Protein-Tyrosine Kinases/metabolism
- Receptors, Cholinergic/genetics
- Receptors, Cholinergic/metabolism
- Receptors, Nicotinic/genetics
- Receptors, Nicotinic/metabolism
- Swine
- Synapses/metabolism
- Transfection
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Affiliation(s)
- Abdullah A. Osman
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Ave., St. Louis MO 63110
| | - Angela D. Schrader
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Ave., St. Louis MO 63110
| | - Aubrey J. Hawkes
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Ave., St. Louis MO 63110
- Department of Physiolgical Science, University of California, Los Angeles
| | - Omar Akil
- Department of Otolaryngology-Head & Neck Surgery, University of California San Francisco, 400 Parnassus Avenue, San Francisco CA 94143
| | - Adam Bergeron
- Program in Neuroscience, Washington University School of Medicine, 660 South Euclid Ave., St. Louis MO 63110
| | - Lawrence R. Lustig
- Department of Otolaryngology-Head & Neck Surgery, University of California San Francisco, 400 Parnassus Avenue, San Francisco CA 94143
| | - Dwayne D. Simmons
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Ave., St. Louis MO 63110
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Ave., St. Louis MO 63110
- Program in Neuroscience, Washington University School of Medicine, 660 South Euclid Ave., St. Louis MO 63110
- Department of Physiolgical Science, University of California, Los Angeles
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27
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Lu J, Yang H, Yu H, Gao W, Lai R, Liu J, Liang X. A novel serine protease inhibitor from Bungarus fasciatus venom. Peptides 2008; 29:369-74. [PMID: 18164783 DOI: 10.1016/j.peptides.2007.11.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 11/19/2007] [Accepted: 11/19/2007] [Indexed: 11/15/2022]
Abstract
By Sephadex G-50 gel filtration, cation-exchange CM-Sephadex C-25 chromatography and reversed phase high-performance liquid chromatography (HPLC), a novel serine protease inhibitor named bungaruskunin was purified and characterized from venom of Bungarus fasciatus. Its cDNA was also cloned from the cDNA library of B. fasciatus venomous glands. The predicted precursor is composed of 83 amino acid (aa) residues including a 24-aa signal peptide and a 59-aa mature bungaruskunin. Bungaruskunin showed maximal similarity (64%) with the predicted serine protease inhibitor blackelin deduced from the cDNA sequence of the red-bellied black snake Pseudechis porphyriacus. Bungaruskunin is a Kunitz protease inhibitor with a conserved Kunitz domain and could exert inhibitory activity against trypsin, chymotrypsin, and elastase. By screening the cDNA library, two new B chains of beta-bungarotoxin are also identified. The overall structures of bungaruskunin and beta-bungarotoxin B chains are similar; especially they have highly conserved signal peptide sequences. These findings strongly suggest that snake Kunitz/BPTI protease inhibitors and neurotoxic homologs may have originated from a common ancestor.
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Affiliation(s)
- Jia Lu
- Biotoxin Units of Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
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28
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Abstract
Nicotinic receptors (nAchRs) are responsible for fast excitatory signaling by the neurotransmitter acetylcholine (Ach). They are present on the postsynaptic membrane at neuromuscular junctions (NMJs) and also at brain synapses. Alpha-bungarotoxin (alpha-BTX), a high-affinity nAchR antagonist, inhibits Ach binding and neurotransmission. Here we demonstrate biotinylated alpha-BTX, bound to native mouse diaphragm nAchRs, can be quantified and visualized ex vivo using streptavidin-conjugated quantum dots. This approach provides a novel methodology for the direct assessment of the presence and mobility of neurotransmitter receptors in native tissue.
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Affiliation(s)
- Rebecca L Orndorff
- Department of Chemistry, Vanderbilt University, Vanderbilt School of Medicine, Vanderbilt University, Nashville, Tennessee 37235-1822, USA
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29
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Razani-Boroujerdi S, Boyd RT, Dávila-García MI, Nandi JS, Mishra NC, Singh SP, Pena-Philippides JC, Langley R, Sopori ML. T cells express alpha7-nicotinic acetylcholine receptor subunits that require a functional TCR and leukocyte-specific protein tyrosine kinase for nicotine-induced Ca2+ response. J Immunol 2007; 179:2889-98. [PMID: 17709503 DOI: 10.4049/jimmunol.179.5.2889] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Acute and chronic effects of nicotine on the immune system are usually opposite; acute treatment stimulates while chronic nicotine suppresses immune and inflammatory responses. Nicotine acutely raises intracellular calcium ([Ca(2+)](i)) in T cells, but the mechanism of this response is unclear. Nicotinic acetylcholine receptors (nAChRs) are present on neuronal and non-neuronal cells, but while in neurons, nAChRs are cation channels that participate in neurotransmission; their structure and function in nonexcitable cells are not well-defined. In this communication, we present evidence that T cells express alpha7-nAChRs that are critical in increasing [Ca(2+)](i) in response to nicotine. Cloning and sequencing of the receptor from human T cells showed a full-length transcript essentially identical to the neuronal alpha7-nAChR subunit (>99.6% homology). These receptors are up-regulated and tyrosine phosphorylated by treatment with nicotine, anti-TCR Abs, or Con A. Furthermore, knockdown of the alpha7-nAChR subunit mRNA by RNA interference reduced the nicotine-induced Ca(2+) response, but unlike the neuronal receptor, alpha-bungarotoxin and methyllycaconitine not only failed to block, but also actually raised [Ca(2+)](i) in T cells. The nicotine-induced release of Ca(2+) from intracellular stores in T cells did not require extracellular Ca(2+), but, similar to the TCR-mediated Ca(2+) response, required activation of protein tyrosine kinases, a functional TCR/CD3 complex, and leukocyte-specific tyrosine kinase. Moreover, CD3zeta and alpha7-nAChR co-immunoprecipitated with anti-CD3zeta or anti-alpha7-nAChR Abs. These results suggest that in T cells, alpha7-nAChR, despite its close sequence homology with neuronal alpha7-nAChR, fails to form a ligand-gated Ca(2+) channel, and that the nicotine-induced rise in [Ca(2+)](i) in T cells requires functional TCR/CD3 and leukocyte-specific tyrosine kinase.
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MESH Headings
- Aconitine/analogs & derivatives
- Aconitine/pharmacology
- Animals
- Bridged Bicyclo Compounds, Heterocyclic/metabolism
- Bridged Bicyclo Compounds, Heterocyclic/pharmacology
- Bungarotoxins/pharmacology
- CD3 Complex/metabolism
- Calcium/metabolism
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Humans
- Immunoprecipitation
- Jurkat Cells
- Leukocytes/enzymology
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/genetics
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/metabolism
- Neurons/metabolism
- Nicotine/pharmacology
- Phosphorylation
- Protein-Tyrosine Kinases/metabolism
- Proto-Oncogene Proteins c-fyn/metabolism
- Pyridines/metabolism
- Pyridines/pharmacology
- RNA, Small Interfering/pharmacology
- Rats
- Receptors, Antigen, T-Cell/antagonists & inhibitors
- Receptors, Antigen, T-Cell/metabolism
- Receptors, Nicotinic/drug effects
- Receptors, Nicotinic/genetics
- Receptors, Nicotinic/metabolism
- T-Lymphocytes/drug effects
- T-Lymphocytes/immunology
- alpha7 Nicotinic Acetylcholine Receptor
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Affiliation(s)
- Seddigheh Razani-Boroujerdi
- Immunology Division, Lovelace Respiratory Research Institute, 2425 Ridgecrest Drive SE, Albuquerque, NM 87108, USA
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30
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Renna JM, Strang CE, Amthor FR, Keyser KT. Strychnine, but not PMBA, inhibits neuronal nicotinic acetylcholine receptors expressed by rabbit retinal ganglion cells. Vis Neurosci 2007; 24:503-11. [PMID: 17900376 DOI: 10.1017/s0952523807070241] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2006] [Accepted: 03/02/2007] [Indexed: 02/07/2023]
Abstract
Strychnine is considered a selective competitive antagonist of glycine gated Cl- channels (Saitoh et al., 1994) and studies have used strychnine at low micromolar concentrations to study the role of glycine in rabbit retina (Linn, 1998; Protti et al., 2005). However, other studies have shown that strychnine, in the concentrations commonly used, is also a potent competitive antagonist of alpha7 nicotinic acetylcholine receptors (nAChRs; Matsubayashi et al., 1998). We tested the effects of low micromolar concentrations of strychnine and 3-[2'-phosphonomethyl[1,1'-biphenyl]-3-yl] alanine (PMBA), a specific glycine receptor blocker (Saitoh et al., 1994; Hosie et al., 1999) on the activation of both alpha7 nAChRs on retinal ganglion cells and on ganglion cell responses to a light flash. Extracellular recordings were obtained from ganglion cells in an isolated retina/choroid preparation and 500 microM choline was used as an alpha7 agonist (Alkondon et al., 1997). We recorded from brisk sustained and brisk transient OFF cells, many of which have been previously shown to have alpha7 receptors (Strang et al., 2005). Further, we tested the effect of strychnine, PMBA and alpha-bungarotoxin on the binding of tetramethylrhodamine alpha-bungarotoxin in the inner plexiform layer. Our data indicates that strychnine, at doses as low as 1.0 microM, can inhibit the alpha7 nAChR-mediated response to choline, but PMBA at concentrations as high as 0.4 microM does not. Binding studies show strychnine and alpha-bungarotoxin inhibit binding of labeled alpha-bungarotoxin in the IPL. Thus, the effects of strychnine application may be to inhibit glycine receptors expressed by ganglion cell or to inhibit amacrine cell alpha7 nAChRs, both of which would result in an increase in the ganglion cell responses. Further research will be required to disentangle the effects of strychnine previously believed to be caused by a single mechanism of glycine receptor inhibition.
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Affiliation(s)
- J M Renna
- Department of Vision Sciences, University Alabama-Birmingham, Birmingham, Alabama 35294, USA
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31
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Zouridakis M, Kostelidou K, Sotiriadis A, Stergiou C, Eliopoulos E, Poulas K, Tzartos SJ. Circular dichroism studies of extracellular domains of human nicotinic acetylcholine receptors provide an insight into their structure. Int J Biol Macromol 2007; 41:423-9. [PMID: 17659334 DOI: 10.1016/j.ijbiomac.2007.05.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 05/31/2007] [Accepted: 05/31/2007] [Indexed: 11/26/2022]
Abstract
The extracellular domains (ECDs) of human nicotinic acetylcholine receptors (nAChRs) are of major pharmacological interest as drug targets in the autoimmune disease myasthenia gravis and in various neurological disorders. We have previously expressed and purified the human muscle alpha1-, beta1-, gamma- and epsilon-nAChR-ECDs, as well as the wild type and a mutant of neuronal alpha7-ECD, in yeast Pichia pastoris. The far-UV circular dichroism (CD) studies of these ECDs, presented here, revealed a major prevalence of beta-sheet ( approximately 40%) and a small proportion of alpha-helical ( approximately 5%) structure for all ECDs, in good agreement with the secondary structure composition of the Torpedo muscle-type nAChR-ECDs and in less, but considerable, agreement with that of the homologous invertebrate acetylcholine-binding proteins (AChBPs). The near-UV CD studies of these nAChR-ECDs indicated well-defined tertiary structures, as was previously suggested by biochemical and immunochemical studies. Furthermore, the binding of cholinergic ligands to the mutant of alpha7-ECD resulted in no changes in its secondary structure, but revealed significant local conformational changes. Our present studies probe the structure of human nAChR-ECDs for the first time and further suggest that our expressed proteins fold to a near-native conformation, thus being suitable for further structural studies.
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Affiliation(s)
- Marios Zouridakis
- Department of Biochemistry, Hellenic Pasteur Institute, 127, Vas. Sofias Ave., GR11521 Athens, Greece
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Patti L, Raiteri L, Grilli M, Zappettini S, Bonanno G, Marchi M. Evidence that α7 nicotinic receptor modulates glutamate release from mouse neocortical gliosomes. Neurochem Int 2007; 51:1-7. [PMID: 17462791 DOI: 10.1016/j.neuint.2007.03.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 03/05/2007] [Accepted: 03/07/2007] [Indexed: 11/23/2022]
Abstract
The presence of nicotinic receptors on astrocytes in human and rat brain has been previously demonstrated however their possible functional role is still poorly understood. In this study we investigated on the presence of nicotinic receptors on gliosomes, purified from mouse cortex, and on their role in eliciting glutamate release. Epibatidine significantly increased basal release of [3H]D-aspartate and of endogenous glutamate from mouse gliosomes but not from synaptosomes. This effect was prevented by methyllycaconitine, alpha-bungarotoxin and mecamylamine but not by dihydro-beta-erythroidine. Epibatidine provoked also a significant increase of calcium concentration in gliosomes but not in synaptosomes; the increase in [Ca2+]i induced by epibatidine and KCl in gliosomes was very similar to each other. The present results indicate that alpha7 nicotinic receptors exist on mouse cortical glial particles and stimulate glutamate release.
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Affiliation(s)
- Laura Patti
- Sezione di Farmacologia e Tossicologia, Dipartimento di Medicina Sperimentale, Università degli Studi di Genova, Viale Cembrano 4, 16148 Genoa, Italy
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Abstract
Epidemiological studies have reported that smoking is associated with a lower incidence of Parkinson's disease (PD), leading to theories that smoking in general and nicotine in particular might be neuroprotective. Recent studies suggested cholinergic anti-inflammatory pathway-regulating microglial activation through alpha7 nicotinic receptors. In the present study, we used lipopolysaccharide (LPS)-induced in vitro and in vivo inflammation models to investigate whether nicotine has a protective effect on the dopaminergic system through an anti-inflammatory mechanism. Nicotine pretreatment considerably decreased microglial activation with significant reduction of tumour necrosis factor (TNF)-alpha mRNA expression and TNF-alpha release induced by LPS stimulation. In co-cultures of microglia and mesencephalic neurons, nicotine pretreatment significantly decreased the loss of tyrosine hydroxylase-immunopositive (TH-ip) cells, approximately twice more than the LPS-only treatment. alpha-Bungarotoxin, an alpha7 nicotinic acetylcholine receptor subunit-selective blocker, considerably blocked the inhibitory effects of nicotine on microglial activation and TH-ip neuronal loss. Chronic nicotine pretreatment in rats showed that TH-ip neuronal loss induced by LPS stimulation in the substantia nigra was dramatically decreased, which was clearly accompanied by a reduction in the formation of TNF-alpha. The present study demonstrated that nicotine has a neuroprotective effect on dopaminergic neurons via an anti-inflammatory mechanism mediated by the modulation of microglial activation. Along with various neuroprotective effects of nicotine, the anti-inflammatory mechanism of nicotine could have a major therapeutic implication in the preventive treatment of PD.
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Affiliation(s)
- Hyun Jung Park
- Department of Neurology, Ajou University School of Medicine, Suwon, Korea
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Marks MJ, Meinerz NM, Drago J, Collins AC. Gene targeting demonstrates that alpha4 nicotinic acetylcholine receptor subunits contribute to expression of diverse [3H]epibatidine binding sites and components of biphasic 86Rb+ efflux with high and low sensitivity to stimulation by acetylcholine. Neuropharmacology 2007; 53:390-405. [PMID: 17631923 PMCID: PMC2577786 DOI: 10.1016/j.neuropharm.2007.05.021] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 04/21/2007] [Accepted: 05/28/2007] [Indexed: 11/20/2022]
Abstract
[3H]Epibatidine binds to nAChR subtypes in mouse brain with higher (KD approximately 0.02 nM) and lower affinity (KD approximately 7 nM), which can be further subdivided through inhibition by selected agonists and antagonists. These subsets are differentially affected by targeted deletion of alpha7, beta2 or beta4 subunits. Most, but not all, higher and lower affinity binding sites require beta2 (Marks, M.J., Whiteaker, P., Collins, A.C., 2006. Deletion of the alpha7, beta2 or beta4 nicotinic receptor subunit genes identifies highly expressed subtypes with relatively low affinity for [3H]epibatidine. Mol. Pharmacol. 70, 947-959). Effects of functional alpha4 gene deletion are reported here. Deletion of alpha4 virtually eliminated cytisine-sensitive, higher-affinity [3H]epibatidine binding as did beta2 deletion, confirming that these sites are alpha4beta2*-nAChR. Cytisine-resistant, higher-affinity [3H]epibatidine binding sites are diverse and some of these sites require alpha4 expression. Lower affinity [3H]epibatidine binding sites are also heterogeneous and can be subdivided into alpha-bungarotoxin-sensitive and -resistant components. Deleting alpha4 did not affect the alpha-bungarotoxin-sensitive component, but markedly reduced the alpha-bungarotoxin-resistant component. This effect was similar, but not quite identical, to the effect of beta2 deletion. This provides the first evidence that lower-affinity epibatidine binding sites in the brain require expression of alpha4 subunits. The effects of alpha4 gene targeting on receptor function were measured using a 86Rb+ efflux assay. Concentration-effect curves for ACh-stimulated 86Rb+ efflux are biphasic (EC50 values=3.3 microM and 300 microM). Targeting alpha4 produced substantial gene-dose dependent reductions in both phases in whole brain and in most of the 14 brain regions assayed. These effects are very similar to those following deletion of beta2. Thus, alpha4beta2*-nAChRs mediate a significant fraction of both phases of ACh stimulated 86Rb+ efflux.
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Affiliation(s)
- Michael J Marks
- Institute for Behavioral Genetics, 447 UCB, University of Colorado, Boulder, CO 80309, USA.
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35
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Arredondo J, Chernyavsky AI, Jolkovsky DL, Pinkerton KE, Grando SA. Receptor-mediated tobacco toxicity: alterations of the NF-kappaB expression and activity downstream of alpha7 nicotinic receptor in oral keratinocytes. Life Sci 2007; 80:2191-4. [PMID: 17291542 PMCID: PMC1973165 DOI: 10.1016/j.lfs.2007.01.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2006] [Revised: 11/26/2006] [Accepted: 01/04/2007] [Indexed: 12/01/2022]
Abstract
To gain a mechanistic insight into nicotinic receptor-dependent morbidity of tobacco products in the oral cavity, we studied effects of exposures of normal human oral keratinocytes (KCs) for 24 h to environmental tobacco smoke (ETS) vs. equivalent concentration of pure nicotine. The exposed KCs showed a multifold increase of nuclear factor-kappaB (NF-kappaB) at the mRNA and protein levels, which could be significantly (p<0.05) diminished by alpha-bungarotoxin or transfection with anti-alpha7 small interfering RNA. An increased protein-binding activity of NF-kappaB also could be prevented by blocking alpha7 signaling. The use of pathway inhibitors demonstrated that the Ras/Raf-1/MEK1/ERK steps mediated alpha7-dependent upregulation of NF-kappaB. Thus, exposure of KCs to tobacco may lead to the pathobiologic effects via an intracellular signaling pathway downstream of alpha7 that proceeds through the Ras/Raf-1/MEK1/ERK steps leading to upregulated expression and transactivation of NF-kappaB.
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Affiliation(s)
- Juan Arredondo
- Department of Dermatology, University of California, Davis
| | | | - David L. Jolkovsky
- Section of Periodontics, School of Dentistry, University of California, Los Angeles, CA, USA
| | - Kent E. Pinkerton
- Center for Health and the Environment, University of California, Davis
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36
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Guzmán GR, Ortiz-Acevedo A, Ricardo A, Rojas LV, Lasalde-Dominicci JA. The Polarity of Lipid-Exposed Residues Contributes to the Functional Differences between Torpedo and Muscle-Type Nicotinic Receptors. J Membr Biol 2007; 214:131-8. [PMID: 17530159 DOI: 10.1007/s00232-006-0051-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 11/27/2006] [Indexed: 10/23/2022]
Abstract
A comparison between the Torpedo and muscle-type acetylcholine receptors (AChRs) reveals differences in several lipid-exposed amino acids, particularly in the polarity of those residues. The goal of this study was to characterize the role of eight lipid-exposed residues in the functional differences between the Torpedo and muscle-type AChRs. To this end, residues alphaS287, alphaC412, betaY441, gammaM299, gammaS460, deltaM293, deltaS297 and deltaN305 in the Torpedo AChR were replaced with those found in the muscle-type receptor. Mutant receptor expression was measured in Xenopus oocytes using [(125)I]-alpha-bungarotoxin, and AChR ion channel function was evaluated using the two-electrode voltage clamp. Eight mutant combinations resulted in an increase (1.5- to 5.2-fold) in AChR expression. Four mutant combinations produced a significant 46% decrease in the ACh 50% inhibitory concentration (EC(50)), while three mutant combinations resulted in 1.7- to 2-fold increases in ACh EC(50). Finally, seven mutant combinations resulted in a decrease in normalized, ACh-induced currents. Our results suggest that these residues, although remote from the ion channel pore, (1) contribute to ion channel gating, (2) may affect trafficking of AChR into specialized membrane domains and (3) account for the functional differences between Torpedo and muscle-type AChR. These findings emphasize the importance of the lipid-protein interface in the functional differences between the Torpedo and muscle-type AChRs.
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Affiliation(s)
- Gisila R Guzmán
- Department of Biology, University of Puerto Rico, San Juan, Puerto Rico 00931-3360.
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37
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Yalcin M, Erturk M. The involvement of the central cholinergic system in the pressor and bradycardic effects of centrally administrated melittin in normotensive conscious rats. Neuropeptides 2007; 41:103-10. [PMID: 17222905 DOI: 10.1016/j.npep.2006.11.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 11/11/2006] [Accepted: 11/18/2006] [Indexed: 10/23/2022]
Abstract
Recently we demonstrated that centrally administrated melittin, a phospholipase A(2) (PLA(2)) activator, caused pressor and bradycardic effect in the normotensive conscious rats. In the current study we aimed to determine the mediation of central cholinergic system in the pressor and bradycardic effect of centrally administrated melittin. Studies were performed in normotensive male Sprague-Dawley rats. 1.5, 3.0 or 6.0microg/5.0microl doses of melittin were injected intracerebroventricularly (i.c.v.). Melittin caused dose- and time-dependent increases in mean arterial pressure (MAP) and decrease in heart rate (HR). In order to test the mediation of central cholinergic system on the pressor and bradycardic effect of melittin, the rats were pretreated with mecamylamine (50microg; i.c.v.), cholinergic nonselective nicotinic receptor antagonist, atropine sulfate (10microg; i.c.v.), a cholinergic nonselective muscarinic receptor antagonist, hemicholinium-3 (20microg; i.c.v.), a high affinity neuronal choline uptake inhibitor, methyllycaconitine (10 and 25microg; i.c.v.) or alpha-bungarotoxin (10 and 25microg; i.c.v.), selective antagonists of alpha-7 subtype nicotinic acetylcholine receptors (alpha7nAChRs), 15min prior to melittin (3.0microg) injection. Pretreatment with mecamylamine, hemicholinium-3, methyllycaconitine or alpha-bungarotoxin partially attenuated the pressor and bradicardia effect of elicited by melittin in the normotensive conscious rats whereas pretreatment with atropine had no effect. In conclusion, i.c.v. administration of melittin increases MAP and decreases HR in conscious rats. The activation of central nicotinic cholinergic receptors, predominantly alpha7nAChRs, partially acts as a mediator in the pressor responses to i.c.v. injection of melittin in the normotensive conscious rats. Moreover, decreased uptake of choline to the cholinergic terminals may consider that melittin activates central choline and acetylcholine release, as well.
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Affiliation(s)
- Murat Yalcin
- Department of Physiology, Faculty of Veterinary Medicine, Uludag University, 16059 Bursa, Turkey.
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38
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Mexal S, Jenkins PM, Lautner MA, Iacob E, Crouch EL, Stitzel JA. alpha7 nicotinic receptor gene promoter polymorphisms in inbred mice affect expression in a cell type-specific fashion. J Biol Chem 2007; 282:13220-7. [PMID: 17360707 DOI: 10.1074/jbc.m610694200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inbred mouse strains display significant differences in their levels of brain alpha7 nicotinic acetylcholine receptor (alpha7 nAChR) expression, as measured by binding of the alpha7-selective antagonist alpha-bungarotoxin. Variations in alpha-bungarotoxin binding have been shown to correlate with an animal's sensitivity to nicotine-induced seizures and sensory gating. In two inbred mouse strains, C3H/2Ibg (C3H) and DBA/2Ibg (DBA/2), the inter-strain binding differences are linked to a restriction length polymorphism in the alpha7 nAChR gene, Chrna7. Despite this finding, the molecular mechanism(s) through which genetic variability in Chrna7 may contribute to alpha7 nAChR expression differences remains unknown. However, studies of the human alpha7 nAChR gene (CHRNA7) previously have demonstrated that CHRNA7 promoter polymorphisms are associated with differences in promoter activity as well as differences in sensory processing. In the present study, a 947-base pair region of the Chrna7 promoter was cloned from both the C3H and DBA/2 inbred mouse strains in an attempt to identify polymorphisms that may underlie alpha7 nAChR differential expression. Sequence analysis of these fragments identified 14 single nucleotide polymorphisms (SNPs). A combination of two of these SNPs affects promoter activity in an in vitro luciferase reporter assay. These results suggest a mechanism through which the Chrna7 promoter genotype may influence interstrain variations in alpha7 nAChR expression.
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Affiliation(s)
- Sharon Mexal
- Institute for Behavioral Genetics and Department of Integrative Physiology, University of Colorado, Boulder, Colorado 80309, USA
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39
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Shin EJ, Chae JS, Jung ME, Bing G, Ko KH, Kim WK, Wie MB, Cheon MA, Nah SY, Kim HC. Repeated intracerebroventricular infusion of nicotine prevents kainate-induced neurotoxicity by activating the α7 nicotinic acetylcholine receptor. Epilepsy Res 2007; 73:292-8. [PMID: 17174071 DOI: 10.1016/j.eplepsyres.2006.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 11/10/2006] [Accepted: 11/16/2006] [Indexed: 10/23/2022]
Abstract
We examined whether (-)-nicotine infusion can affect kainic acid (KA)-induced neurotoxicity in rats. Although treatment with a single nicotine infusion (0.5 or 1.0 microg/side, i.c.v.) failed to attenuate KA-induced neurotoxicity, repeated nicotine infusions (1.0 microg/side/day for 10 days) attenuated the seizures, the severe loss of cells in hippocampal regions CA1 and CA3, the increase in activator protein (AP)-1 DNA binding activity, and mortality after KA administration. alpha-Bungarotoxin and mecamylamine blocked the neuroprotective effects of nicotine. These results suggest that repeated nicotine treatment provides alpha7 nicotinic acetylcholine receptor-mediated neuroprotection against KA toxicity.
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Affiliation(s)
- Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 200-701, South Korea
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40
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Feuerbach D, Nozulak J, Lingenhoehl K, McAllister K, Hoyer D. JN403, in vitro characterization of a novel nicotinic acetylcholine receptor alpha7 selective agonist. Neurosci Lett 2007; 416:61-5. [PMID: 17314009 DOI: 10.1016/j.neulet.2007.01.045] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Revised: 01/15/2007] [Accepted: 01/21/2007] [Indexed: 11/30/2022]
Abstract
This report describes the in vitro features of a novel selective nicotinic acetylcholine receptor (nAChR) alpha7 agonist, JN403, (S)-(1-Aza-bicyclo[2.2.2]oct-3-yl)-carbamic acid (S)-1-(2-fluoro-phenyl)-ethyl ester. JN403 was evaluated in a number of in vitro systems of different species, at recombinant receptors using radioligand binding, signal transduction and electrophysiological studies. When using [(125)I] alpha-bungarotoxin (alpha-BTX) as a radioligand, JN403 has high affinity for human recombinant nAChR alpha7 (pK(D)=6.7). Functionally, JN403 is a partial and potent agonist at human nAChR alpha7. The compound stimulates calcium influx in GH3 cells recombinantly expressing the human nAChR with an pEC(50) of 7.0 and an E(max) of 85% (compared to the full agonist epibatidine). In Xenopus oocytes expressing human nAChR alpha7 JN403 induces inward currents with an pEC(50) of 5.7 and an E(max) of 55%. In both recombinant systems JN403 is a partial agonist and the agonistic effects are blocked after pre-administration of methyllycaconitine (MLA, 100nM), a nAChR alpha7 antagonist. In functional calcium influx assays, JN403 displays a significantly lower potency for other subtypes of human nAChRs like alpha4beta2, alpha3beta4, alpha1beta1gammadelta as well as 5HT(3) receptors when tested functionally as an antagonist (pIC(50)<4.8) and is devoid of agonistic activity (pEC(50)<4). Similarly, JN403 shows low binding activity at a wide panel of neurotransmitter receptors. Thus, JN403 is a potent and selective nAChR alpha7 agonist and will be a useful tool for the characterization of nAChR alpha7 mediated effects both in vitro and in vivo.
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Affiliation(s)
- Dominik Feuerbach
- Neuroscience Research, Novartis Institutes for BioMedical Research, Basel, Switzerland.
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41
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Wang ZF, Tang XC. Huperzine A protects C6 rat glioma cells against oxygen-glucose deprivation-induced injury. FEBS Lett 2007; 581:596-602. [PMID: 17257593 DOI: 10.1016/j.febslet.2007.01.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 12/28/2006] [Accepted: 01/10/2007] [Indexed: 10/23/2022]
Abstract
The protective effects of huperzine A against oxygen-glucose deprivation (OGD)-induced injury in C6 cells were investigated. OGD for 6h and reoxygenation for 6h enhanced phosphorylation and degradation of IkappaBalpha and nuclear translocation of nuclear factor-kappa B (NF-kappaB), triggered overexpression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and nitric oxide (NO) in C6 cells. Along with inhibiting acetylcholinesterase activity, treatment with 1 microM huperzine A inhibited activation of NF-kappaB, attenuated iNOS, COX-2 and NO overexpression, and promoted survival in C6 cells subjected to OGD insult. The protective effects of huperzine A were partly mediated by "cholinergic anti-inflammatory pathway" through alpha7 nicotinic acetylcholine receptor.
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Affiliation(s)
- Zhi Fei Wang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, People's Republic of China
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Neumann S, Razen M, Habermehl P, Meyer CU, Zepp F, Kirkpatrick CJ, Wessler I. The non-neuronal cholinergic system in peripheral blood cells: effects of nicotinic and muscarinic receptor antagonists on phagocytosis, respiratory burst and migration. Life Sci 2007; 80:2361-4. [PMID: 17286990 DOI: 10.1016/j.lfs.2007.01.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Revised: 12/08/2006] [Accepted: 01/10/2007] [Indexed: 11/22/2022]
Abstract
Peripheral blood cells express the complete non-neuronal cholinergic system. For example synthesis of acetylcholine and nicotinic as well muscarinic receptors have been demonstrated in leucocytes isolated from human peripheral blood. In the present experiments mononuclear cells and granulocytes were isolated from the peripheral blood to investigate content and synthesis of acetylcholine as well as phenotypic functions like respiratory burst, phagocytosis and migration. Mononuclear cells (T-cells and monocytes) contained 0.36 pmol/10(6) cells acetylcholine, whereas acetylcholine content in granulocytes was 100-fold lower. Acetylcholine synthesis amounted to 23.2+/-4.7 nmol/mg protein/h and 2.90+/-0.84 in CD15+ (granulocytes) and CD3+ cells (T-lymphocytes), respectively. Neither atropine (blockade of muscarinic receptors) nor tubocurarine (blockade of nicotinic receptors) exerted an effect on the respiratory burst. Tubocurarine (30 muM), alone or in combination with atropine (1 microM), reduced phagocytosis in granulocytes by 13% and 19%, respectively (p<0.05). Spontaneous transwell migration of granulocytes was doubled by tubocurarine combined with atropine (p>0.05). Also alpha-bungarotoxin (10 microg/ml) enhanced spontaneous granulocyte migration, but hexamethonium (300 microM) was without effect. The present experiments demonstrate a cholinergic modulation of immune functions in peripheral leucocytes under in vitro conditions, i.e. in the absence of a neuronal innervation. Blockade of nicotine receptors (alpha1 muscular subtype) facilitates spontaneous migration of granulocytes.
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Affiliation(s)
- Stefanie Neumann
- Institute of Pathology, University Hospital, Johannes Gutenberg University, D-55101 Mainz, Germany
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43
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Cheikh A, Cognard C, Potreau D, Bescond J, Raymond G, El Ayeb M, Benkhalifa R. [Modulation of skeletal muscle contraction by the non-toxic fraction of Buthus occitanus tunetanus venom via the cholinergic receptors]. Arch Inst Pasteur Tunis 2007; 84:39-47. [PMID: 19388582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cholinergic receptors have an essential physiological role in the central nervous system because of their implication in higher functions in the neuromuscular junction within the brain and also in the peripheral nervous system by activating nicotinic (nAChRs) or muscarinic (mAChRs) receptors. Moreover, cholinergic receptors could be recognized by animal toxins isolated from snake venoms or alkaloids having animal or vegetal origin. In this context, we aim to find such molecules in a non toxic venom fraction of Buthus occitanus tunetanus scorpion, M1, which could therefore constitute promising medical tool. We present here a physiological study in skeletal muscle cells that regroups data that have been recently published and some new results reinforcing the last ones. The global effect of M1, was firstly studied on isolated nerve-muscle preparation. In cultured myotubes, we have found that the intracellular calcium increase, induced by M1 was blocked when ryanodine or inositol 1,4,5-triphosphate receptors are inhibited. Moreover, we have shown that M1 application on myotubes, induced a membrane depolarization as seen with acetylcholine. The treatment of myotubes with alpha-bungarotoxin blocked in most parts the depolarization amplitude. Thus, these results confirm the presence of at least one component in M1 active in nAChRs.
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Affiliation(s)
- A Cheikh
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, BP 74-1002 Tunis, Tunisie
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Abstract
In Drosophila, nicotinic acetylcholine receptors (nAChRs) mediate fast excitatory synaptic transmission in mushroom body Kenyon cells, a neuronal population involved in generation of complex behaviors, including responses to drugs of abuse. To determine whether activation of nAChRs can induce cellular changes that contribute to functional plasticity in these neurons, we examined nicotine-evoked responses in cells cultured from brains of late stage OK107-GAL4 pupae. Kenyon cells can be identified by expression of green fluorescent protein (GFP+). Nicotine activates alpha-bungarotoxin-sensitive nAChRs, causing a rapid increase in intracellular calcium levels in over 95% of the Kenyon cells. The nicotine-evoked calcium increase has a voltage-gated calcium channel (VGCC) dependent component and a VGCC-independent component that involves calcium influx directly through nAChRs. Thapsigargin treatment reduces the nicotine response consistent with amplification by calcium release from intracellular stores. The response to nicotine is experience-dependent: a short conditioning pulse of nicotine causes a transient 50% reduction in the magnitude of the response to a test pulse of nicotine when the interpulse interval is 4 h. This cellular plasticity is dependent on activation of the VGCC-component of the nicotine response and on cAMP-signaling, but not on protein synthesis. These data demonstrate that activation of nAChRs induces a calcium-dependent plasticity in Kenyon cells that could contribute to adult behaviors involving information processing in the mushroom bodies including responses to nicotine.
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Affiliation(s)
- Jorge M Campusano
- Department of Anatomy and Neurobiology, University of California-Irvine, Irvine, CA 92697-1280, USA
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45
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Ribera J, Ayala V, Casas C. Involvement of c-Jun-JNK pathways in the regulation of programmed cell death of developing chick embryo spinal cord motoneurons. Dev Neurosci 2006; 29:438-51. [PMID: 17119319 DOI: 10.1159/000097318] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Accepted: 08/03/2006] [Indexed: 01/24/2023] Open
Abstract
Key features of developmentally regulated programmed cell death (PCD) have been described for the first time in the chick nervous system. JNK/c-Jun pathway was involved in early events determining normal and pathological neuronal death as shown in experimental models. In the chick embryo, PCD of motoneurons (MNs) in ovo occurs within a well-defined temporal window and can be subjected to experimental manipulation. Taking advantage of this in vivo system, we explored the role of c-Jun and JNK pathway in the regulation of PCD in MNs. By using specific antibodies against phospho-c-Jun (Ser 63, 73) and JNK we demonstrated that before MNs acquire apoptotic phenotype there is an increase in c-Jun. Blockage of neuromuscular activity by the GABA agonist muscimol reduces PCD and diminishes c-Jun immunoreactivity in MNs. Extensive induction of PCD, either due to injection of beta-bungarotoxin or limb bud removal, is also preceded by an increase in c-Jun immunoreactivity that is also associated with upregulation of phospho-c-Jun and JNK. Translocation of JNK from cytoplasm to MN nuclei was also detected. After acute application of beta-bungarotoxin, which is a strong apoptotic stimulus for MNs, c-Jun phosphorylation occurs on serine 73, whereas serine 63 is the main site for c-Jun phosphorylation after limb bud removal. These results demonstrated that the JNK/c-Jun pathway is involved in the decision phase of normal and induced apoptosis in MNs. Pharmacological interventions involving this pathway should be explored as a potential therapeutic target for promoting MN survival.
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Affiliation(s)
- Joan Ribera
- Universitat de Lleida, Facultat de Medicina, Departament de Ciències Mèdiques Bàsiques, Lleida, Spain.
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46
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Sola E, Capsoni S, Rosato-Siri M, Cattaneo A, Cherubini E. Failure of nicotine-dependent enhancement of synaptic efficacy at Schaffer-collateral CA1 synapses of AD11 anti-nerve growth factor transgenic mice. Eur J Neurosci 2006; 24:1252-64. [PMID: 16987213 DOI: 10.1111/j.1460-9568.2006.04996.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Alzheimer's disease is a neurodegenerative disorder characterized by neuronal loss associated with a progressive impairment of cognitive functions. Early consequences of Alzheimer's disease include deficit of cholinergic signalling in particular regions controlling memory processes, such as the cortex and hippocampus, and accumulation of beta-amyloid (Abeta) peptide in neuritic plaques. The cholinergic system depends for its integrity and function on nerve growth factor. Chronic nerve growth factor deprivation in transgenic mice (AD11) engineered to produce recombinant neutralizing anti-nerve growth factor antibodies leads to progressive age-dependent Alzheimer's-like neurodegenerative pathology similar to that found in patients with Alzheimer's disease, associated with a selective loss of cholinergic neurones in the basal forebrain. Here we show that in the hippocampus of 6-month-old AD11 mice, Abeta aggregates started appearing in the CA1 region. The accumulation of Abeta was associated with a loss of cholinergic function at CA3-CA1 synapses. Whereas in wild-type mice nicotine induced a persistent increase of synaptic efficacy via alpha7 nicotine acetylcholine receptors, in AD11 mice this alkaloid failed to modify synaptic strength. Moreover, nicotine failed to transiently enhance the frequency of spontaneous miniature glutamatergic currents (miniature excitatory postsynaptic currents) recorded from CA1 but not from CA3 pyramidal neurones of AD11 mice. However, in CA3 principal cells of AD11 mice, the potentiating effect of nicotine on miniature excitatory postsynaptic currents was prevented when Abeta peptide 1-42 was added to the extracellular solution. These data suggest that in AD11 mice, Abeta interferes with nicotine acetylcholine receptors at the level of presynaptic glutamatergic terminals, inhibiting their function possibly through calcium signalling via presynaptic alpha7 nicotine acetylcholine receptors.
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Affiliation(s)
- Elisabetta Sola
- Neuroscience Programme, International School for Advanced Studies, Via Beirut 2-4, 34014 Trieste, Italy
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Riganti L, Matteoni C, Di Angelantonio S, Nistri A, Gaimarri A, Sparatore F, Canu-Boido C, Clementi F, Gotti C. Long-term exposure to the new nicotinic antagonist 1,2-bisN-cytisinylethane upregulates nicotinic receptor subtypes of SH-SY5Y human neuroblastoma cells. Br J Pharmacol 2006; 146:1096-109. [PMID: 16273122 PMCID: PMC1751242 DOI: 10.1038/sj.bjp.0706434] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Nicotinic drug treatment can affect the expression of neuronal nicotinic acetylcholine receptors (nAChR) both in vivo and in vitro through molecular mechanisms not fully understood. The present study investigated the effect of the novel cytisine dimer 1,2-bisN-cytisinylethane (CC4) on nAChR natively expressed by SH-SY5Y neuroblastoma cells in culture. CC4 lacked the agonist properties of cytisine and was a potent antagonist (IC50=220 nM) on nAChRs. Chronic treatment of SH-SY5Y cells with 1 mM CC4 for 48 h increased the expression of 3H-epibatidine (3H-Epi; 3-4-fold) or 125I-alpha-bungarotoxin (125I-alphaBgtx; 1.2-fold) sensitive receptors present on the cell membrane and in the intracellular pool. Comparable data were obtained with nicotine or cytisine, but not with carbamylcholine, d-tubocurarine, di-hydro-beta-erythroidine or hexametonium. Immunoprecipitation and immunopurification studies showed that the increase in 3H-Epi-binding receptors was due to the enhanced expression of alpha3beta2 and alpha3beta2beta4 subtypes without changes in subunit mRNA transcription or receptor half-life. The upregulation was not dependent on agonist/antagonist properties of the drugs, and did not concern muscarinic or serotonin receptors. Whole-cell patch clamp analysis of CC4-treated cells demonstrated larger nicotine-evoked inward currents with augmented sensitivity to the blockers alpha-conotoxin MII or methyllycaconitine. In conclusion, chronic treatment with CC4 increased the number of nAChRs containing beta2 and alpha7 subunits on the plasma membrane, where they were functionally active. In the case of beta2-containing receptors, we propose that CC4, by binding to intracellular receptors, triggered a conformational reorganisation of intracellular subunits that stimulated preferential assembly and membrane-directed trafficking of beta2-containing receptor subtypes..
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Affiliation(s)
- Loredana Riganti
- CNR, Institute of Neuroscience, Cellular and Molecular Pharmacology, Department of Medical Pharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milan, Via Vanvitelli 32, 20129 Milan, Italy
| | - Cosetta Matteoni
- Neurobiology Sector, International School for Advanced Studies (SISSA), Trieste, Italy
| | | | - Andrea Nistri
- Neurobiology Sector, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Annalisa Gaimarri
- CNR, Institute of Neuroscience, Cellular and Molecular Pharmacology, Department of Medical Pharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milan, Via Vanvitelli 32, 20129 Milan, Italy
| | - Fabio Sparatore
- Department of Pharmaceutical Science, University of Genoa, Genoa, Italy
| | | | - Francesco Clementi
- CNR, Institute of Neuroscience, Cellular and Molecular Pharmacology, Department of Medical Pharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milan, Via Vanvitelli 32, 20129 Milan, Italy
| | - Cecilia Gotti
- CNR, Institute of Neuroscience, Cellular and Molecular Pharmacology, Department of Medical Pharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milan, Via Vanvitelli 32, 20129 Milan, Italy
- Author for correspondence:
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Takahashi HK, Iwagaki H, Hamano R, Yoshino T, Tanaka N, Nishibori M. alpha7 Nicotinic acetylcholine receptor stimulation inhibits lipopolysaccharide-induced interleukin-18 and -12 production in monocytes. J Pharmacol Sci 2006; 102:143-6. [PMID: 16960420 DOI: 10.1254/jphs.sc0060074] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Nicotine inhibited interleukin (IL)-18 and -12 production in lipopolysaccharide (LPS)-stimulated monocytes, and the action of nicotine was antagonized by a non-selective and a selective alpha7 nicotinic acetylcholine receptor (alpha7-nAChR) antagonist, suggesting that the stimulation of alpha7-nAChR may be involved in the action of nicotine. Nicotine is reported to induce prostaglandin E(2) (PGE(2)) production in monocytes through the up-regulation of cyclooxygenase (COX)-2 expression. PGE(2) is known to increase cAMP levels and to activate protein kinase A (PKA). COX-2 and PKA inhibitors prevented the action of nicotine, indicating that the mechanism of action of nicotine may be via endogenous PGE(2) production.
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Affiliation(s)
- Hideo Kohka Takahashi
- Department of Pharmacology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science, Japan
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Gauthier M, Dacher M, Thany SH, Niggebrügge C, Déglise P, Kljucevic P, Armengaud C, Grünewald B. Involvement of α-bungarotoxin-sensitive nicotinic receptors in long-term memory formation in the honeybee (Apis mellifera). Neurobiol Learn Mem 2006; 86:164-74. [PMID: 16616529 DOI: 10.1016/j.nlm.2006.02.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Revised: 02/16/2006] [Accepted: 02/22/2006] [Indexed: 11/18/2022]
Abstract
In the honeybee Apis mellifera, multiple-trial olfactory conditioning of the proboscis extension response specifically leads to long-term memory (LTM) which can be retrieved more than 24 h after learning. We studied the involvement of nicotinic acetylcholine receptors in the establishment of LTM by injecting the nicotinic antagonists mecamylamine (1 mM), alpha-bungarotoxin (alpha-BGT, 0.1 mM) or methyllycaconitine (MLA, 0.1 mM) into the brain through the median ocellus 20 min before or 20 min after multiple-trial learning. The retention tests were performed 1, 3, and 24 h after learning. Pre-training injections of mecamylamine induced a lower performance during conditioning but had no effect on LTM formation. Post-training injections of mecamylamine did not affect honeybees' performances. Pre-training injections of MLA or post-training injection of alpha-BGT specifically induced LTM impairment whereas acquisition as well as memory retrieval tested 1 or 3 h after learning was normal. This indicates that brain injections of alpha-BGT and MLA did not interfere with learning or medium-term memory. Rather, these blockers affect the LTM. To explain these results, we advance the hypothesis that honeybee alpha-BGT-sensitive acetylcholine receptors are also sensitive to MLA. These receptors could be essential for triggering intracellular mechanisms involved in LTM. By contrast, medium-term memory is not dependent upon these receptors but is affected by mecamylamine.
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Affiliation(s)
- Monique Gauthier
- Centre de Recherches sur la Cognition Animale, CNRS/Université Paul Sabatier Toulouse III, 4R3, 118 route de Narbonne, 31062 Toulouse Cedex 09, France.
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Zhu W, Mantione KJ, Casares FM, Sheehan MH, Kream RM, Stefano GB. Cholinergic regulation of endogenous morphine release from lobster nerve cord. Med Sci Monit 2006; 12:BR295-301. [PMID: 16940924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Accepted: 07/15/2006] [Indexed: 05/11/2023] Open
Abstract
BACKGROUND Invertebrate nervous systems are regulated by G-coupled protein receptors, chemical transporters, and ion channels responsive to established drugs of abuse including opiates, alcohol, psychostinulants, and nicotine. Thus, invertebrate nervous tissue preparations can be used as predictive model systems by which to evaluate underlying pharmacological mechanisms of addictive processes. MATERIAL/METHODS Ex vivo pharmacological trials were used to determine the comparative effects of the nicotinic agonists and antagonists on the evoked release of labeled morphine from H. americanus nerve cord. The intrinsically low basal levels of endogenous morphine required that we utilize an ex vivo model system involving pre-labeling of intracellutlar opiate alkaloid pools with high specific activity 125I labeled morphine. RESULTS Both nicotine and epibatidine promoted evoked release of 125I labeled morphine that is selectively linked to activation of invertebrate nicotinic receptors based on pharmacological inhibition by alpha bungarotoxin (alpha-BuTx). Epibatidine promoted release at concentrations 2-3 orders of magnitude higher than nicotine. Co-administration of nicotine (60 nM) and the pre-junctional ganglionic nicotinic antagonist hexamethonium (1 microM) produced a marked potentiation of 125I labeled morphine release; a pharmacological effect also observed for epibatidine (35 microM) co-administered with the competitive nicotinic antagonist chlorisondaminie at 1 microM. The stimulatory effects of ethanol to promote enhanced release of endogenous morphine were not affected by co-admninistration of alpha-BuTx at 1 microM. CONCLUSIONS The stirmulatory effects of nicotine on cellular expression and release of endogenous morphine occurs via specific alpha-BuTx sensitive receptors, suggesting a novel mechanism underling the reinforcing and addictive properties of nicotine via endogenous morphine.
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Affiliation(s)
- Wei Zhu
- Neuroscience Research Institute, State University of New York-College at Old Westbury, P.O. Box 210, Old Westbury, NY 11568, USA.
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