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Oishi K, Nagamori M, Kashino Y, Sekiguchi H, Sasaki YC, Miyazawa A, Nishino Y. Ligand-Dependent Intramolecular Motion of Native Nicotinic Acetylcholine Receptors Determined in Living Myotube Cells via Diffracted X-ray Tracking. Int J Mol Sci 2023; 24:12069. [PMID: 37569445 PMCID: PMC10418694 DOI: 10.3390/ijms241512069] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/20/2023] [Accepted: 07/26/2023] [Indexed: 08/13/2023] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that play an important role in signal transduction at the neuromuscular junction (NMJ). Movement of the nAChR extracellular domain following agonist binding induces conformational changes in the extracellular domain, which in turn affects the transmembrane domain and opens the ion channel. It is known that the surrounding environment, such as the presence of specific lipids and proteins, affects nAChR function. Diffracted X-ray tracking (DXT) facilitates measurement of the intermolecular motions of receptors on the cell membranes of living cells, including all the components involved in receptor function. In this study, the intramolecular motion of the extracellular domain of native nAChR proteins in living myotube cells was analyzed using DXT for the first time. We revealed that the motion of the extracellular domain in the presence of an agonist (e.g., carbamylcholine, CCh) was restricted by an antagonist (i.e., alpha-bungarotoxin, BGT).
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Affiliation(s)
- Koichiro Oishi
- Graduate School of Sciences, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Kobe 678-1297, Hyogo, Japan; (K.O.); (Y.K.)
| | - Mayu Nagamori
- Graduate School of Sciences, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Kobe 678-1297, Hyogo, Japan; (K.O.); (Y.K.)
| | - Yasuhiro Kashino
- Graduate School of Sciences, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Kobe 678-1297, Hyogo, Japan; (K.O.); (Y.K.)
| | - Hiroshi Sekiguchi
- Center for Synchrotron Radiation Research, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Sayo 679-5198, Hyogo, Japan; (H.S.); (Y.C.S.)
| | - Yuji C. Sasaki
- Center for Synchrotron Radiation Research, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Sayo 679-5198, Hyogo, Japan; (H.S.); (Y.C.S.)
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8561, Chiba, Japan
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory, National Institute of Advanced Industrial Science and Technology, 6-2-3 Kashiwanoha, Kashiwa 277-0882, Chiba, Japan
| | - Atsuo Miyazawa
- Graduate School of Sciences, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Kobe 678-1297, Hyogo, Japan; (K.O.); (Y.K.)
| | - Yuri Nishino
- Graduate School of Sciences, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Kobe 678-1297, Hyogo, Japan; (K.O.); (Y.K.)
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Shelukhina I, Siniavin A, Kasheverov I, Ojomoko L, Tsetlin V, Utkin Y. α7- and α9-Containing Nicotinic Acetylcholine Receptors in the Functioning of Immune System and in Pain. Int J Mol Sci 2023; 24:ijms24076524. [PMID: 37047495 PMCID: PMC10095066 DOI: 10.3390/ijms24076524] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/26/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) present as many different subtypes in the nervous and immune systems, muscles and on the cells of other organs. In the immune system, inflammation is regulated via the vagus nerve through the activation of the non-neuronal α7 nAChR subtype, affecting the production of cytokines. The analgesic properties of α7 nAChR-selective compounds are mostly based on the activation of the cholinergic anti-inflammatory pathway. The molecular mechanism of neuropathic pain relief mediated by the inhibition of α9-containing nAChRs is not fully understood yet, but the role of immune factors in this process is becoming evident. To obtain appropriate drugs, a search of selective agonists, antagonists and modulators of α7- and α9-containing nAChRs is underway. The naturally occurring three-finger snake α-neurotoxins and mammalian Ly6/uPAR proteins, as well as neurotoxic peptides α-conotoxins, are not only sophisticated tools in research on nAChRs but are also considered as potential medicines. In particular, the inhibition of the α9-containing nAChRs by α-conotoxins may be a pathway to alleviate neuropathic pain. nAChRs are involved in the inflammation processes during AIDS and other viral infections; thus they can also be means used in drug design. In this review, we discuss the role of α7- and α9-containing nAChRs in the immune processes and in pain.
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Affiliation(s)
| | | | | | | | | | - Yuri Utkin
- Correspondence: or ; Tel.: +7-495-3366522
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3
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Speculation on How RIC-3 and Other Chaperones Facilitate α7 Nicotinic Receptor Folding and Assembly. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27144527. [PMID: 35889400 PMCID: PMC9318448 DOI: 10.3390/molecules27144527] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/07/2022] [Accepted: 07/09/2022] [Indexed: 11/17/2022]
Abstract
The process of how multimeric transmembrane proteins fold and assemble in the endoplasmic reticulum is not well understood. The alpha7 nicotinic receptor (α7 nAChR) is a good model for multimeric protein assembly since it has at least two independent and specialized chaperones: Resistance to Inhibitors of Cholinesterase 3 (RIC-3) and Nicotinic Acetylcholine Receptor Regulator (NACHO). Recent cryo-EM and NMR data revealed structural features of α7 nAChRs. A ser-ala-pro (SAP) motif precedes a structurally important but unique "latch" helix in α7 nAChRs. A sampling of α7 sequences suggests the SAP motif is conserved from C. elegans to humans, but the latch sequence is only conserved in vertebrates. How RIC-3 and NACHO facilitate receptor subunits folding into their final pentameric configuration is not known. The artificial intelligence program AlphaFold2 recently predicted structures for NACHO and RIC-3. NACHO is highly conserved in sequence and structure across species, but RIC-3 is not. This review ponders how different intrinsically disordered RIC-3 isoforms from C. elegans to humans interact with α7 nAChR subunits despite having little sequence homology across RIC-3 species. Two models from the literature about how RIC-3 assists α7 nAChR assembly are evaluated considering recent structural information about the receptor and its chaperones.
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Lovejoy PC, Foley KE, Conti MM, Meadows SM, Bishop C, Fiumera AC. Genetic basis of susceptibility to low-dose paraquat and variation between the sexes in Drosophila melanogaster. Mol Ecol 2021; 30:2040-2053. [PMID: 33710693 DOI: 10.1111/mec.15878] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 02/23/2021] [Indexed: 12/18/2022]
Abstract
Toxicant resistance is a complex trait, affected both by genetics and the environment. Like most complex traits, it can exhibit sexual dimorphism, yet sex is often overlooked as a factor in studies of toxicant resistance. Paraquat, one such toxicant, is a commonly used herbicide and is known to produce mitochondrial oxidative stress, decrease dopaminergic neurons and dopamine (DA) levels, and decrease motor ability. While the main effects of paraquat are well-characterized, less is known about the naturally occurring variation in paraquat susceptibility. The purpose of this study was to map the genes contributing to low-dose paraquat susceptibility in Drosophila melanogaster, and to determine if susceptibility differs between the sexes. One hundred of the Drosophila Genetic Reference Panel (DGRP) lines were scored for susceptibility via climbing ability and used in a genome-wide association study (GWAS). Variation in seventeen genes in females and thirty-five genes in males associated with paraquat susceptibility. Only two candidate genes overlapped between the sexes despite a significant positive correlation between male and female susceptibilities. Many associated polymorphisms had significant interactions with sex, with most having conditionally neutral effects. Conditional neutrality between the sexes probably stems from sex-biased expression which may result from partial resolution of sexual conflict. Candidate genes were verified with RNAi knockdowns, gene expression analyses, and DA quantification. Several of these genes are novel associations with paraquat susceptibility. This research highlights the importance of assessing both sexes when studying toxicant susceptibility.
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Affiliation(s)
- Pamela C Lovejoy
- Department of Biological Sciences, Binghamton University, Binghamton, NY, USA.,Department of Biology, St. Joseph's College, Brooklyn, NY, USA
| | - Kate E Foley
- Department of Biological Sciences, Binghamton University, Binghamton, NY, USA
| | - Melissa M Conti
- Department of Psychology, Binghamton University, Binghamton, NY, USA
| | | | | | - Anthony C Fiumera
- Department of Biological Sciences, Binghamton University, Binghamton, NY, USA
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Meng X, Miao L, Ge H, Yang X, Dong F, Xu X, Wu Z, Qian K, Wang J. Molecular characterization of glutamate-gated chloride channel and its possible roles in development and abamectin susceptibility in the rice stem borer, Chilo suppressalis. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2019; 155:72-80. [PMID: 30857629 DOI: 10.1016/j.pestbp.2019.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/15/2019] [Accepted: 01/20/2019] [Indexed: 06/09/2023]
Abstract
Glutamate-gated chloride channels (GluCls) mediate fast inhibitory neurotransmission in invertebrate nervous systems, and are of considerable interest in insecticide discovery. The full length cDNA encoding CsGluCl was cloned from the rice stem borer Chilo suppressalis (Walker). Multiple cDNA sequence alignment revealed three variants of CsGluCl generated by alternative splicing of exon 3 and exon 9. While all the transcripts were predominantly expressed in both nerve cord and brain, the expression patterns of these three variants differed among other tissues and developmental stages. Specifically, the expression level of CsGluCl C in cuticle was similar to that in nerve cord and brain, and was the predominant variant in late pupae and early adult stages. Both injection and oral delivery of dsGluCl significantly reduced the mRNA level of CsGluCl. Increased susceptibility to abamectin and reduced larvae growth and pupation rate were observed in dsGluCl-treated larvae. Thus, our results provide the evidence that in addition to act as the target of abamectin, GluCls also play important physiological roles in the development of insects.
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Affiliation(s)
- Xiangkun Meng
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Lijun Miao
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Huichen Ge
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Xuemei Yang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Fan Dong
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Xin Xu
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Zhaolu Wu
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Kun Qian
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Jianjun Wang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China.
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Wang X, O Reilly AO, Williamson MS, Puinean AM, Yang Y, Wu S, Wu Y. Function and pharmacology of glutamate-gated chloride channel exon 9 splice variants from the diamondback moth Plutella xylostella. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 104:58-64. [PMID: 30550974 DOI: 10.1016/j.ibmb.2018.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 10/24/2018] [Accepted: 12/11/2018] [Indexed: 06/09/2023]
Abstract
Glutamate-gated chloride channels (GluCls) are found only in invertebrates and mediate fast inhibitory neurotransmission. The structural and functional diversity of GluCls are produced through assembly of multiple subunits and via posttranscriptional alternations. Alternative splicing is the most common way to achieve this in insect GluCls and splicing occurs primarily at exons 3 and 9. As expression pattern and pharmacological properties of exon 9 alternative splices in invertebrate GluCls remain poorly understood, the cDNAs encoding three alternative splice variants (9a, 9b and 9c) of the PxGluCl gene from the diamondback moth Plutella xylostella were constructed and their pharmacological characterizations were examined using electrophysiological studies. Alternative splicing of exon 9 had little to no impact on PxGluCl sensitivity towards the agonist glutamate when subunits were singly or co-expressed in Xenopus oocytes. In contrast, the allosteric modulator abamectin and the chloride channel blocker fipronil had differing effects on PxGluCl splice variants. PxGluCl9c channels were more resistant to abamectin and PxGluCl9b channels were more sensitive to fipronil than other homomeric channels. In addition, heteromeric channels containing different splice variants showed similar sensitivity to abamectin (except for 9c) and reduced sensitivity to fipronil than homomeric channels. These findings suggest that functionally indistinguishable but pharmacologically distinct GluCls could be formed in P. xylostella and that the upregulated constitutive expression of the specific variants may contribute to the evolution of insecticide resistance in P. xylostella and other arthropods.
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Affiliation(s)
- Xingliang Wang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
| | - Andrias O O Reilly
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK.
| | - Martin S Williamson
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, UK.
| | - Alin M Puinean
- Oxitec Limited, 71 Innovation Drive, Abingdon, Oxfordshire, UK.
| | - Yihua Yang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
| | - Shuwen Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
| | - Yidong Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
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Yu W, Hu B, Shi X, Cao Z, Ren M, He Z, Lin J, Deng H, Hu R. Nicotine inhibits osteogenic differentiation of human periodontal ligament cells under cyclic tensile stress through canonical Wnt pathway and α7 nicotinic acetylcholine receptor. J Periodontal Res 2018; 53:555-564. [PMID: 29603740 DOI: 10.1111/jre.12545] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2018] [Indexed: 12/29/2022]
Abstract
BACKGROUND AND OBJECTIVES Nicotine, the main psychoactive component of tobacco, affects cell metabolism, proliferation, adhesion and, importantly, the osteogenic differentiation of fibroblasts. Approximately 15% of all orthodontic patients are adults among who one-fifth are smokers. Hence, it is necessary to have insight into the effects of nicotine on the osteogenic differentiation of hPDLCs during orthodontic tooth movement. This study aimed to investigate the effects and mechanisms of nicotine on the osteogenic differentiation of human periodontal ligament cells (hPDLCs) under the application of cyclic tensile stress. MATERIAL AND METHODS hPDLCs were obtained from donor third molars. The hPDLCs were treated with nicotine and/or cyclic tensile stress that was applied with a cell stress plus unit. The effect of nicotine on cell viability was analyzed using the MTT assay. The osteogenic differentiation of hPDLCs was detected by alkaline phosphatase staining, Alizarin Red S staining, quantitative real-time polymerase chain reaction and western blotting. RESULTS In combination with cyclic tensile stress, nicotine prevented the tensile stress-induced increase in alkaline phosphatase activity, formation of mineralization nodules and the upregulation of mRNA and protein expression of Runt-related transcription factor 2, transcription factor Sp7 and collagen type I; however, canonical Wnt pathway was activated. Furthermore, the addition of Dickkopf-related protein 1 and α-bungarotoxin counteracted the negative effect of nicotine and rescued the osteogenic differentiation of hPDLCs, respectively. CONCLUSION These results indicate that nicotine prevents the increased osteogenic potential of hPDLCs induced by cyclic tensile stress by binding to an α7 nicotinic acetylcholine receptor and activating the canonical Wnt pathway.
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Affiliation(s)
- W Yu
- Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, China
| | - B Hu
- Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, China
| | - X Shi
- Department of Periodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, China
| | - Z Cao
- Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, China
| | - M Ren
- Department of Periodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, China
| | - Z He
- Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, China
| | - J Lin
- Department of Periodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, China
| | - H Deng
- Department of Periodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, China
| | - R Hu
- Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, China
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Ferraro NA, Cascio M. Cross-Linking-Mass Spectrometry Studies of Cholesterol Interactions with Human α1 Glycine Receptor. Anal Chem 2018; 90:2508-2516. [DOI: 10.1021/acs.analchem.7b03639] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Nicholas A. Ferraro
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
| | - Michael Cascio
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
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Lazaridis K, Dalianoudis I, Baltatzidi V, Tzartos SJ. Specific removal of autoantibodies by extracorporeal immunoadsorption ameliorates experimental autoimmune myasthenia gravis. J Neuroimmunol 2017; 312:24-30. [DOI: 10.1016/j.jneuroim.2017.09.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/03/2017] [Accepted: 09/05/2017] [Indexed: 11/29/2022]
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Nemecz Á, Prevost MS, Menny A, Corringer PJ. Emerging Molecular Mechanisms of Signal Transduction in Pentameric Ligand-Gated Ion Channels. Neuron 2017; 90:452-70. [PMID: 27151638 DOI: 10.1016/j.neuron.2016.03.032] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 01/07/2016] [Accepted: 03/24/2016] [Indexed: 10/21/2022]
Abstract
Nicotinic acetylcholine, serotonin type 3, γ-amminobutyric acid type A, and glycine receptors are major players of human neuronal communication. They belong to the family of pentameric ligand-gated ion channels, sharing a highly conserved modular 3D structure. Recently, high-resolution structures of both open- and closed-pore conformations have been solved for a bacterial, an invertebrate, and a vertebrate receptor in this family. These data suggest that a common gating mechanism occurs, coupling neurotransmitter binding to pore opening, but they also pinpoint significant differences among subtypes. In this Review, we summarize the structural and functional data in light of these gating models and speculate about their mechanistic consequences on ion permeation, pathological mutations, as well as functional regulation by orthosteric and allosteric effectors.
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Affiliation(s)
- Ákos Nemecz
- Channel-Receptors Unit, Institut Pasteur, 75015 Paris, France; CNRS UMR 3571, 75015 Paris, France
| | - Marie S Prevost
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK
| | - Anaïs Menny
- Channel-Receptors Unit, Institut Pasteur, 75015 Paris, France; CNRS UMR 3571, 75015 Paris, France; Université Pierre et Marie Curie (UPMC), Cellule Pasteur, 75005 Paris, France
| | - Pierre-Jean Corringer
- Channel-Receptors Unit, Institut Pasteur, 75015 Paris, France; CNRS UMR 3571, 75015 Paris, France.
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Kryukova EV, Lebedev DS, Ivanov IA, Ivanov DA, Starkov VG, Tsetlin VI, Utkin YN. N-methyl serotonin analogues from the Bufo bufo toad venom interact efficiently with the α7 nicotinic acetylcholine receptors. DOKL BIOCHEM BIOPHYS 2017; 472:52-55. [PMID: 28421441 DOI: 10.1134/s1607672917010136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Indexed: 11/23/2022]
Abstract
Two low-molecular-weight compounds were isolated from the parotid gland secret of the toad Bufo bufo, which by absorption spectra and HPLC-MS/MS chromatography data correspond to di- and trimethyl derivatives of serotonin (5-hydorxytryptamine): bufotenine (confirmed by counter synthesis) and bufotenidine (5-HTQ). In experiments on competitive radioligand binding, these compounds showed a higher affinity and selectivity for neuronal α7 nicotinic acetylcholine receptors compared with the muscular cholinergic receptors. The most efficient compound in terms of binding value was bufotenine, the efficiency of 5-HTQ was an order of magnitude lower, and the minimal activity was exhibited by serotonin.
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Affiliation(s)
- E V Kryukova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
| | - D S Lebedev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - I A Ivanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - D A Ivanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - V G Starkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - V I Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Yu N Utkin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
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Molgó J, Marchot P, Aráoz R, Benoit E, Iorga BI, Zakarian A, Taylor P, Bourne Y, Servent D. Cyclic imine toxins from dinoflagellates: a growing family of potent antagonists of the nicotinic acetylcholine receptors. J Neurochem 2017; 142 Suppl 2:41-51. [PMID: 28326551 DOI: 10.1111/jnc.13995] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/13/2017] [Accepted: 02/15/2017] [Indexed: 12/24/2022]
Abstract
We present an overview of the toxicological profile of the fast-acting, lipophilic macrocyclic imine toxins, an emerging family of organic compounds associated with algal blooms, shellfish contamination and neurotoxicity. Worldwide, shellfish contamination incidents are expanding; therefore, the significance of these toxins for the shellfish food industry deserves further study. Emphasis is directed to the dinoflagellate species involved in their production, their chemical structures, and their specific mode of interaction with their principal natural molecular targets, the nicotinic acetylcholine receptors, or with the soluble acetylcholine-binding protein, used as a surrogate receptor model. The dinoflagellates Karenia selliformis and Alexandrium ostenfeldii / A. peruvianum have been implicated in the biosynthesis of gymnodimines and spirolides, while Vulcanodinium rugosum is the producer of pinnatoxins and portimine. The cyclic imine toxins are characterized by a macrocyclic skeleton comprising 14-27 carbon atoms, flanked by two conserved moieties, the cyclic imine and the spiroketal ring system. These phycotoxins generally display high affinity and broad specificity for the muscle type and neuronal nicotinic acetylcholine receptors, a feature consistent with their binding site at the receptor subunit interfaces, composed of residues highly conserved among all nAChRs, and explaining the diverse toxicity among animal species. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.
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Affiliation(s)
- Jordi Molgó
- Commissariat à l'Energie Atomique et aux énergies alternatives (CEA), Institut de Biologie et Technologies de Saclay (IBITECS), Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, Gif-sur-Yvette, France.,Institut des Neurosciences Paris-Saclay, UMR 9197, Centre National de la Recherche Scientifique (CNRS)/Université Paris-Sud, Gif-sur-Yvette Cedex, France
| | - Pascale Marchot
- Aix-Marseille Université / Centre National de la Recherche Scientifique, Architecture et Fonction des Macromolécules Biologiques laboratory, Marseille, France
| | - Rómulo Aráoz
- Commissariat à l'Energie Atomique et aux énergies alternatives (CEA), Institut de Biologie et Technologies de Saclay (IBITECS), Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, Gif-sur-Yvette, France.,Institut des Neurosciences Paris-Saclay, UMR 9197, Centre National de la Recherche Scientifique (CNRS)/Université Paris-Sud, Gif-sur-Yvette Cedex, France
| | - Evelyne Benoit
- Commissariat à l'Energie Atomique et aux énergies alternatives (CEA), Institut de Biologie et Technologies de Saclay (IBITECS), Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, Gif-sur-Yvette, France.,Institut des Neurosciences Paris-Saclay, UMR 9197, Centre National de la Recherche Scientifique (CNRS)/Université Paris-Sud, Gif-sur-Yvette Cedex, France
| | - Bogdan I Iorga
- Centre National de la Recherche Scientifique (CNRS), Institut de Chimie des Substances Naturelles, UPR 2301, Labex LERMIT, Gif-sur-Yvette, France
| | - Armen Zakarian
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, USA
| | - Palmer Taylor
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, USA
| | - Yves Bourne
- Aix-Marseille Université / Centre National de la Recherche Scientifique, Architecture et Fonction des Macromolécules Biologiques laboratory, Marseille, France
| | - Denis Servent
- Commissariat à l'Energie Atomique et aux énergies alternatives (CEA), Institut de Biologie et Technologies de Saclay (IBITECS), Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, Gif-sur-Yvette, France
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13
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Wu SF, Mu XC, Dong YX, Wang LX, Wei Q, Gao CF. Expression pattern and pharmacological characterisation of two novel alternative splice variants of the glutamate-gated chloride channel in the small brown planthopper Laodelphax striatellus. PEST MANAGEMENT SCIENCE 2017; 73:590-597. [PMID: 27302648 DOI: 10.1002/ps.4340] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 06/09/2016] [Accepted: 06/10/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND Glutamate-gated chloride channels (GluCl) mediate fast inhibitory neurotransmission in invertebrate nervous systems. Although only one GluCl gene was presented in insects, it showed diverse alternative splicing that was speculated could affect channel function and pharmacology. RESULTS In this study, we isolated GluCl cDNAs from adults of the small brown planthopper (SBPH) Laodelphax striatellus and showed that six L. striatellus GluCl variants (LsGluCl-AS, LsGluCl-BS, LsGluCl-CS, LsGluCl-AL, LsGluCl-BL, LsGluCl-CL) were present in the SBPH. The expression patterns of six variants differed among developmental stages (egg, first- to fifth-instar nymphs, male and female adults) and among the body parts (head, thorax, abdomen, leg) of the female adult SBPH. All the transcripts were abundant in the head of the adult. When expressed in African clawed frog, Xenopus laevis, oocytes, the two functional variants (LsGluCl-AS, LsGluCl-AL) had similar EC50 and IC50 values for L-glutamate and channel blockers picrotoxinin and fipronil. CONCLUSION This study represents a comprehensive molecular, expression and pharmacological characterisation of GluCl in the SBPH. These findings should be useful in providing more opportunities to discover novel insect control chemicals. © 2016 Society of Chemical Industry.
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Affiliation(s)
- Shun-Fan Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Jiangsu, China
| | - Xi-Chao Mu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Jiangsu, China
| | - Yao-Xue Dong
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Jiangsu, China
| | - Li-Xiang Wang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Jiangsu, China
| | - Qi Wei
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Jiangsu, China
| | - Cong-Fen Gao
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Jiangsu, China
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14
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Baenziger JE, Domville JA, Therien JD. The Role of Cholesterol in the Activation of Nicotinic Acetylcholine Receptors. CURRENT TOPICS IN MEMBRANES 2017; 80:95-137. [DOI: 10.1016/bs.ctm.2017.05.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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15
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Meyers JI, Gray M, Kuklinski W, Johnson LB, Snow CD, Black WC, Partin KM, Foy BD. Characterization of the target of ivermectin, the glutamate-gated chloride channel, from Anopheles gambiae. ACTA ACUST UNITED AC 2016; 218:1478-86. [PMID: 25994631 DOI: 10.1242/jeb.118570] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The use of insecticide-treated nets and indoor residual insecticides targeting adult mosquito vectors is a key element in malaria control programs. However, mosquito resistance to the insecticides used in these applications threatens malaria control efforts. Recently, the mass drug administration of ivermectin (IVM) has been shown to kill Anopheles gambiae mosquitoes and disrupt Plasmodium falciparum transmission in the field. We cloned the molecular target of IVM from A. gambiae, the glutamate-gated chloride channel (AgGluCl), and characterized its transcriptional patterns, protein expression and functional responses to glutamate and IVM. AgGluCl cloning revealed an unpredicted fourth splice isoform as well as a novel exon and splice site. The predicted gene products contained heterogeneity in the N-terminal extracellular domain and the intracellular loop region. Responses to glutamate and IVM were measured using two-electrode voltage clamp on Xenopus laevis oocytes expressing AgGluCl. IVM induced non-persistent currents in AgGluCl-a1 and did not potentiate glutamate responses. In contrast, AgGluCl-b was insensitive to IVM, suggesting that the AgGluCl gene could produce IVM-sensitive and -insensitive homomultimers from alternative splicing. AgGluCl isoform-specific transcripts were measured across tissues, ages, blood feeding status and sex, and were found to be differentially transcribed across these physiological variables. Lastly, we stained adult, female A. gambiae for GluCl expression. The channel was expressed in the antenna, Johnston's organ, supraesophageal ganglion and thoracic ganglia. In summary, we have characterized the first GluCl from a mosquito, A. gambiae, and described its unique activity and expression with respect to it as the target of the insecticide IVM.
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Affiliation(s)
- Jacob I Meyers
- Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, CO 80523-1617, USA
| | - Meg Gray
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, 1692 Campus Delivery, Fort Collins, CO 80523-1692, USA
| | - Wojtek Kuklinski
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, 1692 Campus Delivery, Fort Collins, CO 80523-1692, USA
| | - Lucas B Johnson
- Department of Chemical and Biological Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, CO 80523-1370, USA
| | - Christopher D Snow
- Department of Chemical and Biological Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, CO 80523-1370, USA
| | - William C Black
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, 1692 Campus Delivery, Fort Collins, CO 80523-1692, USA
| | - Kathryn M Partin
- Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, CO 80523-1617, USA
| | - Brian D Foy
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, 1692 Campus Delivery, Fort Collins, CO 80523-1692, USA
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16
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Bracamontes JR, Akk G, Steinbach JH. Introduced Amino Terminal Epitopes Can Reduce Surface Expression of Neuronal Nicotinic Receptors. PLoS One 2016; 11:e0151071. [PMID: 26963253 PMCID: PMC4786271 DOI: 10.1371/journal.pone.0151071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 02/23/2016] [Indexed: 12/05/2022] Open
Abstract
Epitopes accessible on the surface of intact cells are extremely valuable in studies of membrane proteins, allowing quantification and determination of the distribution of proteins as well as identification of cells expressing large numbers of proteins. However for many membrane proteins there are no suitable antibodies to native sequences, due to lack of availability, low affinity or lack of specificity. In these cases the use of an introduced epitope at specific sites in the protein of interest can often provide a suitable tool for studies. However, the introduction of the epitope sequence has the potential to affect protein expression, the assembly of multisubunit proteins or transport to the surface membrane. We find that surface expression of heteromeric neuronal nicotinic receptors containing the α4 and β4 subunits can be affected by introduced epitopes when inserted near the amino terminus of a subunit. The FLAG epitope greatly reduces surface expression when introduced into either α4 or β4 subunits, the V5 epitope has little effect when placed in either, while the Myc epitope reduces expression more when inserted into β4 than α4. These results indicate that the extreme amino terminal region is important for assembly of these receptors, and demonstrate that some widely used introduced epitopes may severely reduce surface expression.
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Affiliation(s)
- John R. Bracamontes
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, United States of America
| | - Gustav Akk
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, United States of America
- Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, Saint Louis, MO, United States of America
| | - Joe Henry Steinbach
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, United States of America
- Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, Saint Louis, MO, United States of America
- * E-mail:
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17
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Fu YL, Wang YJ, Mu TW. Proteostasis Maintenance of Cys-Loop Receptors. ION CHANNELS AS THERAPEUTIC TARGETS, PART A 2016; 103:1-23. [DOI: 10.1016/bs.apcsb.2015.11.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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18
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Distinctive effects of nicotinic receptor intracellular-loop mutations associated with nocturnal frontal lobe epilepsy. Neuropharmacology 2015; 102:158-73. [PMID: 26561946 DOI: 10.1016/j.neuropharm.2015.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/02/2015] [Accepted: 11/05/2015] [Indexed: 11/21/2022]
Abstract
Previously characterized nicotinic acetylcholine receptor (nAChR) autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE)-associated mutations are found in α2, α4 and β2 subunit transmembrane (TM) domains. They predominantly increase ACh potency and, for β2-subunit mutants, increase macroscopic currents. Two recently-identified mutations, α4(R336H) and β2(V337G), located in the intracellular cytoplasmic loop (C2) have been associated with non-familial NFLE. Effects of these mutations on α4β2-nAChR function and expression were studied for the first time, using two-electrode voltage clamp recordings in Xenopus laevis oocytes. Biased-ratio preparations elucidated the mutations' effects at alternate isoforms: high-sensitivity [HS; (α4)2(β2)3] or low-sensitivity [LS; (α4)3(β2)2] via 1:10 or 30:1 [α4:β2] cRNA injection ratios, respectively. An unbiased (1:1 [α4:β2] cRNA) injection ratio was also used to study potential shifts in isoform expression. α4(R336H)-containing receptors showed significant increases in maximal ACh-induced currents (Imax) in all preparations (140% increase compared to wild type control). β2(V337G)-containing receptors significantly increased Imax in the LS-favoring preparation (20% increase compared to control). Expression of either mutation consistently produced enrichment of HS-isoform expression in all preparations. α4β2-nAChR harboring either NFLE mutant subunit showed unchanged ACh, sazetidine-A, nicotine, cytisine and mecamylamine potency. However, both mutant subunits enhanced partial agonist efficacies in the LS-biased preparation. Using β2-subunit-specific [(125)I]mAb 295 immunolabeling, nAChR cell-surface expression was determined. Antibody binding studies revealed that the β2(V337G) mutation tended to reduce cell-surface expression, and function per receptor was significantly increased by either NFLE mutant subunit in HS-favoring preparations. These findings identify both common and differing features between TM- and C2-domain AD/NFLE-associated mutations. As we discuss, the shared features may be particularly salient to AD/NFLE etiology.
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19
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Stokes C, Treinin M, Papke RL. Looking below the surface of nicotinic acetylcholine receptors. Trends Pharmacol Sci 2015; 36:514-23. [PMID: 26067101 DOI: 10.1016/j.tips.2015.05.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 05/13/2015] [Accepted: 05/14/2015] [Indexed: 01/10/2023]
Abstract
The amino acid sequences of nicotinic acetylcholine receptors (nAChRs) from diverse species can be compared across extracellular, transmembrane, and intracellular domains. The intracellular domains are most divergent among subtypes, yet relatively consistent among species. The diversity indicates that each nAChR subtype has a unique language for communication with its host cell. The conservation across species also suggests that the intracellular domains have defining functional roles for each subtype. Secondary structure prediction indicates two relatively conserved alpha helices within the intracellular domains of all nAChRs. Among all subtypes, the intracellular domain of α7 nAChR is one of the most well conserved, and α7 nAChRs have effects in non-neuronal cells independent of generating ion currents, making it likely that the α7 intracellular domain directly mediates signal transduction. There are potential phosphorylation and protein-binding sites in the α7 intracellular domain, which are conserved and may be the basis for α7-mediated signal transduction.
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Affiliation(s)
- Clare Stokes
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA
| | - Millet Treinin
- Department of Medical Neurobiology, Hadassah Medical School, Hebrew University, Jerusalem 91120, Israel
| | - Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA.
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20
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Linck L, Binder J, Haynl C, Enz R. Endocytosis of GABAC
receptors depends on subunit composition and is regulated by protein kinase C-ζ and protein phosphatase 1. J Neurochem 2015; 134:233-46. [DOI: 10.1111/jnc.13126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/01/2015] [Accepted: 04/09/2015] [Indexed: 12/01/2022]
Affiliation(s)
- Lisa Linck
- Institut für Biochemie (Emil-Fischer-Zentrum); Friedrich-Alexander-Universität Erlangen-Nürnberg; Erlangen Germany
| | - Jasmin Binder
- Institut für Biochemie (Emil-Fischer-Zentrum); Friedrich-Alexander-Universität Erlangen-Nürnberg; Erlangen Germany
| | - Christian Haynl
- Institut für Biochemie (Emil-Fischer-Zentrum); Friedrich-Alexander-Universität Erlangen-Nürnberg; Erlangen Germany
| | - Ralf Enz
- Institut für Biochemie (Emil-Fischer-Zentrum); Friedrich-Alexander-Universität Erlangen-Nürnberg; Erlangen Germany
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21
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Targeted killing of rhabdomyosarcoma cells by a MAP-based human cytolytic fusion protein. Cancer Lett 2015; 365:149-55. [PMID: 25888452 DOI: 10.1016/j.canlet.2015.04.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 04/02/2015] [Accepted: 04/04/2015] [Indexed: 12/26/2022]
Abstract
The treatment of rhabdomyosarcoma (RMS) is challenging, and the prognosis remains especially poor for high-grade RMS with metastasis. The conventional treatment of RMS is based on multi-agent chemotherapy combined with resection and radiotherapy, which are often marked by low success rate. Alternative therapeutic options include the combination of standard treatments with immunotherapy. We generated a microtubule-associated protein (MAP)-based fully human cytolytic fusion protein (hCFP) targeting the fetal acetylcholine receptor, which is expressed on RMS cells. We were able to express and purify functional scFv35-MAP from Escherichia coli cells. Moreover, we found that scFv35-MAP is rapidly internalized by target cells after binding its receptor, and exhibits specific cytotoxicity toward FL-OH1 and RD cells in vitro. We also confirmed that scFv35-MAP induces apoptosis in FL-OH1 and RD cells. The in vivo potential of scFv35-MAP will need to be considered in further studies.
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22
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Talwar S, Lynch JW. Investigating ion channel conformational changes using voltage clamp fluorometry. Neuropharmacology 2015; 98:3-12. [PMID: 25839896 DOI: 10.1016/j.neuropharm.2015.03.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/12/2015] [Accepted: 03/17/2015] [Indexed: 11/26/2022]
Abstract
Ion channels are membrane proteins whose functions are governed by conformational changes. The widespread distribution of ion channels, coupled with their involvement in most physiological and pathological processes and their importance as therapeutic targets, renders the elucidation of these conformational mechanisms highly compelling from a drug discovery perspective. Thanks to recent advances in structural biology techniques, we now have high-resolution static molecular structures for members of the major ion channel families. However, major questions remain to be resolved about the conformational states that ion channels adopt during activation, drug modulation and desensitization. Patch-clamp electrophysiology has long been used to define ion channel conformational states based on functional criteria. It achieves this by monitoring conformational changes at the channel gate and cannot detect conformational changes occurring in regions distant from the gate. Voltage clamp fluorometry involves labelling cysteines introduced into domains of interest with environmentally sensitive fluorophores and inferring structural rearrangements from voltage or ligand-induced fluorescence changes. Ion channel currents are monitored simultaneously to verify the conformational status. By defining real time conformational changes in domains distant from the gate, this technique provides unexpected new insights into ion channel structure and function. This review aims to summarise the methodology and highlight recent innovative applications of this powerful technique. This article is part of the Special Issue entitled 'Fluorescent Tools in Neuropharmacology'.
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Affiliation(s)
- Sahil Talwar
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Joseph W Lynch
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia.
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23
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Nicotinic acetylcholine receptor-lipid interactions: Mechanistic insight and biological function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1806-17. [PMID: 25791350 DOI: 10.1016/j.bbamem.2015.03.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 02/15/2015] [Accepted: 03/09/2015] [Indexed: 01/14/2023]
Abstract
Membrane lipids are potent modulators of the nicotinic acetylcholine receptor (nAChR) from Torpedo. Lipids influence nAChR function by both conformational selection and kinetic mechanisms, stabilizing varying proportions of activatable versus non-activatable conformations, as well as influencing the transitions between these conformational states. Of note, some membranes stabilize an electrically silent uncoupled conformation that binds agonist but does not undergo agonist-induced conformational transitions. The uncoupled nAChR, however, does transition to activatable conformations in relatively thick lipid bilayers, such as those found in lipid rafts. In this review, we discuss current understanding of lipid-nAChR interactions in the context of increasingly available high resolution structural and functional data. These data highlight different sites of lipid action, including the lipid-exposed M4 transmembrane α-helix. Current evidence suggests that lipids alter nAChR function by modulating interactions between M4 and the adjacent transmembrane α-helices, M1 and M3. These interactions have also been implicated in both the folding and trafficking of nAChRs to the cell surface. We review current mechanistic understanding of lipid-nAChR interactions, and highlight potential biological roles for lipid-nAChR interactions in modulating the synaptic response. This article is part of a Special Issue entitled: Lipid-protein interactions.
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24
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Kasheverov IE, Shelukhina IV, Kudryavtsev DS, Makarieva TN, Spirova EN, Guzii AG, Stonik VA, Tsetlin VI. 6-bromohypaphorine from marine nudibranch mollusk Hermissenda crassicornis is an agonist of human α7 nicotinic acetylcholine receptor. Mar Drugs 2015; 13:1255-66. [PMID: 25775422 PMCID: PMC4377982 DOI: 10.3390/md13031255] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 02/11/2015] [Accepted: 02/15/2015] [Indexed: 01/07/2023] Open
Abstract
6-Bromohypaphorine (6-BHP) has been isolated from the marine sponges Pachymatisma johnstoni, Aplysina sp., and the tunicate Aplidium conicum, but data on its biological activity were not available. For the nudibranch mollusk Hermissenda crassicornis no endogenous compounds were known, and here we describe the isolation of 6-BHP from this mollusk and its effects on different nicotinic acetylcholine receptors (nAChR). Two-electrode voltage-clamp experiments on the chimeric α7 nAChR (built of chicken α7 ligand-binding and glycine receptor transmembrane domains) or on rat α4β2 nAChR expressed in Xenopus oocytes revealed no action of 6-BHP. However, in radioligand analysis, 6-BHP competed with radioiodinated α-bungarotoxin for binding to human α7 nAChR expressed in GH4C1 cells (IC50 23 ± 1 μM), but showed no competition on muscle-type nAChR from Torpedo californica. In Ca2+-imaging experiments on the human α7 nAChR expressed in the Neuro2a cells, 6-BHP in the presence of PNU120596 behaved as an agonist (EC50 ~80 μM). To the best of our knowledge, 6-BHP is the first low-molecular weight compound from marine source which is an agonist of the nAChR subtype. This may have physiological importance because H. crassicornis, with its simple and tractable nervous system, is a convenient model system for studying the learning and memory processes.
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Affiliation(s)
- Igor E Kasheverov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, Moscow 117997, Russia.
| | - Irina V Shelukhina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, Moscow 117997, Russia.
| | - Denis S Kudryavtsev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, Moscow 117997, Russia.
| | - Tatyana N Makarieva
- Elyakov Pacific Institute of Bioorganic Chemistry (PIBOC), Russian Academy of Sciences, Prospect 100 let Vladivostoku, 159, Vladivostok 690022, Russia.
| | - Ekaterina N Spirova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, Moscow 117997, Russia.
| | - Alla G Guzii
- Elyakov Pacific Institute of Bioorganic Chemistry (PIBOC), Russian Academy of Sciences, Prospect 100 let Vladivostoku, 159, Vladivostok 690022, Russia.
| | - Valentin A Stonik
- Elyakov Pacific Institute of Bioorganic Chemistry (PIBOC), Russian Academy of Sciences, Prospect 100 let Vladivostoku, 159, Vladivostok 690022, Russia.
| | - Victor I Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, Moscow 117997, Russia.
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Specific adsorbents for myasthenia gravis autoantibodies using mutants of the muscle nicotinic acetylcholine receptor extracellular domains. J Neuroimmunol 2015; 278:19-25. [DOI: 10.1016/j.jneuroim.2014.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 11/27/2014] [Accepted: 12/01/2014] [Indexed: 11/20/2022]
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26
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The role of the M4 lipid-sensor in the folding, trafficking, and allosteric modulation of nicotinic acetylcholine receptors. Neuropharmacology 2014; 96:157-68. [PMID: 25433148 DOI: 10.1016/j.neuropharm.2014.11.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/31/2014] [Accepted: 11/18/2014] [Indexed: 11/24/2022]
Abstract
With the availability of high resolution structural data, increasing attention has focused on the mechanisms by which drugs and endogenous compounds allosterically modulate nicotinic acetylcholine receptor (nAChR) function. Lipids are potent modulators of the nAChR from Torpedo. Membrane lipids influence nAChR function by both conformational selection and kinetic mechanisms, stabilizing varying proportions of pre-existing resting, open, desensitized, and uncoupled conformations, as well as influencing the transitions between these conformational states. Structural and functional data highlight a role for the lipid-exposed M4 transmembrane α-helix of each subunit in lipid sensing, and suggest that lipids influence gating by altering the binding of M4 to the adjacent transmembrane α-helices, M1 and M3. M4 has also been implicated in both the folding and trafficking of nAChRs to the cell surface, as well as in the potentiation of nAChR gating by neurosteroids. Here, we discuss the roles of M4 in the folding, trafficking, and allosteric modulation of nAChRs. We also consider the hypothesis that variable chemistry at the M4-M1/M3 transmembrane α-helical interface in different nAChR subunits governs the capacity for potentiation by activating lipids. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: ligand-gated ion channels. Br J Pharmacol 2014; 170:1582-606. [PMID: 24528238 PMCID: PMC3892288 DOI: 10.1111/bph.12446] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Ligand-gated ion channels are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen P H Alexander
- School of Life Sciences, University of Nottingham Medical School, Nottingham, NG7 2UH, UK
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Lazaridis K, Zisimopoulou P, Giastas P, Bitzopoulou K, Evangelakou P, Sideri A, Tzartos SJ. Expression of human AChR extracellular domain mutants with improved characteristics. Int J Biol Macromol 2014; 63:210-7. [DOI: 10.1016/j.ijbiomac.2013.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/07/2013] [Accepted: 11/10/2013] [Indexed: 10/26/2022]
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29
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McClure-Begley TD, Papke RL, Stone KL, Stokes C, Levy AD, Gelernter J, Xie P, Lindstrom J, Picciotto MR. Rare human nicotinic acetylcholine receptor α4 subunit (CHRNA4) variants affect expression and function of high-affinity nicotinic acetylcholine receptors. J Pharmacol Exp Ther 2014; 348:410-20. [PMID: 24385388 DOI: 10.1124/jpet.113.209767] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Nicotine, the primary psychoactive component in tobacco smoke, produces its behavioral effects through interactions with neuronal nicotinic acetylcholine receptors (nAChRs). α4β2 nAChRs are the most abundant in mammalian brain, and converging evidence shows that this subtype mediates the rewarding and reinforcing effects of nicotine. A number of rare variants in the CHRNA4 gene that encode the α4 nAChR subunit have been identified in human subjects and appear to be underrepresented in a cohort of smokers. We compared three of these variants (α4R336C, α4P451L, and α4R487Q) to the common variant to determine their effects on α4β2 nAChR pharmacology. We examined [(3)H]epibatidine binding, interacting proteins, and phosphorylation of the α4 nAChR subunit with liquid chromatography and tandem mass spectrometry (LC-MS/MS) in HEK 293 cells and voltage-clamp electrophysiology in Xenopus laevis oocytes. We observed significant effects of the α4 variants on nAChR expression, subcellular distribution, and sensitivity to nicotine-induced receptor upregulation. Proteomic analysis of immunopurified α4β2 nAChRs incorporating the rare variants identified considerable differences in the intracellular interactomes due to these single amino acid substitutions. Electrophysiological characterization in X. laevis oocytes revealed alterations in the functional parameters of activation by nAChR agonists conferred by these α4 rare variants, as well as shifts in receptor function after incubation with nicotine. Taken together, these experiments suggest that genetic variation at CHRNA4 alters the assembly and expression of human α4β2 nAChRs, resulting in receptors that are more sensitive to nicotine exposure than those assembled with the common α4 variant. The changes in nAChR pharmacology could contribute to differences in responses to smoked nicotine in individuals harboring these rare variants.
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Affiliation(s)
- T D McClure-Begley
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut (T.D.M.-B., A.D.L., J.G., M.R.P.); Institute for Behavioral Genetics, University of Colorado, Boulder, Boulder, Colorado (T.D.M.-B.); Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida (R.L.P., C.S.); W.M. Keck Biotechnology Research Laboratory (K.S.), Interdepartmental Neuroscience Program (A.D.L., M.R.P.), Department of Genetics (J.G., P.X.), and Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut (M.R.P.); Department of Psychiatry, Veterans Affairs Connecticut Healthcare Center, West Haven, Connecticut (J.G.); Center for Human Genome Variation, Duke University, Durham, North Carolina (P.X.); and Department of Neuroscience, Medical School of the University of Pennsylvania, Philadelphia, Pennsylvania (J.L.)
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Isacoff EY, Jan LY, Minor DL. Conduits of life's spark: a perspective on ion channel research since the birth of neuron. Neuron 2013; 80:658-74. [PMID: 24183018 DOI: 10.1016/j.neuron.2013.10.040] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Heartbeats, muscle twitches, and lightning-fast thoughts are all manifestations of bioelectricity and rely on the activity of a class of membrane proteins known as ion channels. The basic function of an ion channel can be distilled into, "The hole opens. Ions go through. The hole closes." Studies of the fundamental mechanisms by which this process happens and the consequences of such activity in the setting of excitable cells remains the central focus of much of the field. One might wonder after so many years of detailed poking at such a seemingly simple process, is there anything left to learn?
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Affiliation(s)
- Ehud Y Isacoff
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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31
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Jensen AB, Hoestgaard-Jensen K, Jensen AA. Elucidation of molecular impediments in the α6 subunit for in vitro expression of functional α6β4* nicotinic acetylcholine receptors. J Biol Chem 2013; 288:33708-33721. [PMID: 24085295 DOI: 10.1074/jbc.m113.509356] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Explorations into the α6-containing nicotinic acetylcholine receptors (α6* nAChRs) as putative drug targets have been severely hampered by the inefficient functional expression of the receptors in heterologous expression systems. In this study, the molecular basis for the problem was investigated through the construction of chimeric α6/α3 and mutant α3 and α6 subunits and functional characterization of these co-expressed with β4 or β4β3 subunits in tsA201 cells in a fluorescence-based assay and in Xenopus oocytes using two-electrode voltage clamp electrophysiology. Substitution of a small C-terminal segment in the second intracellular loop or the Phe(223) residue in transmembrane helix 1 of α6 with the corresponding α3 segment or residue was found to enhance α6β4 functionality in tsA201 cells significantly, in part due to increased cell surface expression of the receptors. The gain-of-function effects of these substitutions appeared to be additive since incorporation of both α3 elements into α6 resulted in assembly of α6β4* receptors exhibiting robust functional responses to acetylcholine. The pharmacological properties exhibited by α6β4β3 receptors comprising one of these novel α6/α3 chimeras in oocytes were found to be in good agreement with those from previous studies of α6* nAChRs formed from other surrogate α6 subunits or concatenated subunits and studies of other heteromeric nAChRs. In contrast, co-expression of this α6/α3 chimera with β2 or β2β3 subunits in oocytes did not result in efficient formation of functional receptors, indicating that the identified molecular elements in α6 could be specific impediments for the expression of functional α6β4* nAChRs.
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Affiliation(s)
- Anne B Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Kirsten Hoestgaard-Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
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Chaumont S, André C, Perrais D, Boué-Grabot E, Taly A, Garret M. Agonist-dependent endocytosis of γ-aminobutyric acid type A (GABAA) receptors revealed by a γ2(R43Q) epilepsy mutation. J Biol Chem 2013; 288:28254-65. [PMID: 23935098 DOI: 10.1074/jbc.m113.470807] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
GABA-gated chloride channels (GABAARs) trafficking is involved in the regulation of fast inhibitory transmission. Here, we took advantage of a γ2(R43Q) subunit mutation linked to epilepsy in humans that considerably reduces the number of GABAARs on the cell surface to better understand the trafficking of GABAARs. Using recombinant expression in cultured rat hippocampal neurons and COS-7 cells, we showed that receptors containing γ2(R43Q) were addressed to the cell membrane but underwent clathrin-mediated dynamin-dependent endocytosis. The γ2(R43Q)-dependent endocytosis was reduced by GABAAR antagonists. These data, in addition to a new homology model, suggested that a conformational change in the extracellular domain of γ2(R43Q)-containing GABAARs increased their internalization. This led us to show that endogenous and recombinant wild-type GABAAR endocytosis in both cultured neurons and COS-7 cells can be amplified by their agonists. These findings revealed not only a direct relationship between endocytosis of GABAARs and a genetic neurological disorder but also that trafficking of these receptors can be modulated by their agonist.
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Affiliation(s)
- Severine Chaumont
- From the Université Bordeaux, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), UMR 5287, F-33000 Bordeaux, France
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33
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Planamente S, Moréra S, Faure D. In planta fitness-cost of the Atu4232-regulon encoding for a selective GABA-binding sensor in Agrobacterium. Commun Integr Biol 2013; 6:e23692. [PMID: 23710277 PMCID: PMC3656012 DOI: 10.4161/cib.23692] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 01/21/2013] [Accepted: 01/21/2013] [Indexed: 12/01/2022] Open
Abstract
GABA (gamma-aminobutyric acid) mediates cell-to-cell communication in eukaryotes and interspecies communication in host-microbe interactions. Agrobacterium tumefaciens induces the development of plant tumor in which GABA accumulates. Two periplasmic binding proteins Atu2422 and Atu4243 and their appropriate ABC-transporter are involved in the binding and importation of GABA. The structure of the selective GABA-binding Atu4243 reveals a GABA conformation similar to a proposed model of GABA bound to the mammalian GABAC receptor. The A. tumefaciens atu4243 mutant is affected for GABA uptake, aggressiveness on plant host and GABA-induced degradation of the quorum-sensing signal, hence for horizontal transfer of the tumor-inducing plasmid. Here, we report that a de-repression of atu4243 and its co-regulated neighbor genes affect the fitness of A. tumefaciens during tumor colonization. Atu4243-orthologs are present in several species of the Agrobacterium genus. This addendum highlights the recent data on the GABA transport in the A. tumefaciens plant-pathogen.
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Affiliation(s)
- Sara Planamente
- Institut des Sciences du Végétal (ISV); CNRS; Gif-sur-Yvette, France ; Laboratoire d'Enzymologie et Biochimie Structurales (LEBS); CNRS; Gif-sur-Yvette, France
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34
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Kryukova EV, Shelukhina IV, Kozina EA, Ugryumov MV, Tsetlin VI. Expression of acetylcholine receptors in the brain of mice at the presymptomatic stage of Parkinson’s disease. DOKL BIOCHEM BIOPHYS 2013; 449:69-71. [DOI: 10.1134/s1607672913020038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Indexed: 11/23/2022]
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Herguedas B, Krieger J, Greger IH. Receptor Heteromeric Assembly—How It Works and Why It Matters. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 117:361-86. [DOI: 10.1016/b978-0-12-386931-9.00013-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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36
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Tol MB, Deluz C, Hassaine G, Graff A, Stahlberg H, Vogel H. Thermal unfolding of a mammalian pentameric ligand-gated ion channel proceeds at consecutive, distinct steps. J Biol Chem 2012; 288:5756-69. [PMID: 23275379 DOI: 10.1074/jbc.m112.422287] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Pentameric ligand-gated ion channels (LGICs) play an important role in fast synaptic signal transduction. Binding of agonists to the β-sheet-structured extracellular domain opens an ion channel in the transmembrane α-helical region of the LGIC. How the structurally distinct and distant domains are functionally coupled for such central transmembrane signaling processes remains an open question. To obtain detailed information about the stability of and the coupling between these different functional domains, we analyzed the thermal unfolding of a homopentameric LGIC, the 5-hydroxytryptamine receptor (ligand binding, secondary structure, accessibility of Trp and Cys residues, and aggregation), in plasma membranes as well as during detergent extraction, purification, and reconstitution into artificial lipid bilayers. We found a large loss in thermostability correlating with the loss of the lipid bilayer during membrane solubilization and purification. Thermal unfolding of the 5-hydroxytryptamine receptor occurred in consecutive steps at distinct protein locations. A loss of ligand binding was detected first, followed by formation of different transient low oligomeric states of receptor pentamers, followed by partial unfolding of helical parts of the protein, which finally lead to the formation receptor aggregates. Structural destabilization of the receptor in detergents could be partially reversed by reconstituting the receptor into lipid bilayers. Our results are important because they quantify the stability of LGICs during detergent extraction and purification and can be used to create stabilized receptor proteins for structural and functional studies.
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Affiliation(s)
- Menno B Tol
- Laboratory of Physical Chemistry of Polymers and Membranes, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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37
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Becchetti A. Neuronal nicotinic receptors in sleep-related epilepsy: studies in integrative biology. ISRN BIOCHEMISTRY 2012; 2012:262941. [PMID: 25969754 PMCID: PMC4392997 DOI: 10.5402/2012/262941] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 10/21/2012] [Indexed: 11/23/2022]
Abstract
Although Mendelian diseases are rare, when considered one by one, overall they constitute a significant social burden. Besides the medical aspects, they propose us one of the most general biological problems. Given the simplest physiological perturbation of an organism, that is, a single gene mutation, how do its effects percolate through the hierarchical biological levels to determine the pathogenesis? And how robust is the physiological system to this perturbation? To solve these problems, the study of genetic epilepsies caused by mutant ion channels presents special advantages, as it can exploit the full range of modern experimental methods. These allow to extend the functional analysis from single channels to whole brains. An instructive example is autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), which can be caused by mutations in neuronal nicotinic acetylcholine receptors. In vitro, such mutations often produce hyperfunctional receptors, at least in heterozygous condition. However, understanding how this leads to sleep-related frontal epilepsy is all but straightforward. Several available animal models are helping us to determine the effects of ADNFLE mutations on the mammalian brain. Because of the complexity of the cholinergic regulation in both developing and mature brains, several pathogenic mechanisms are possible, which also present different therapeutic implications.
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Affiliation(s)
- Andrea Becchetti
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
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38
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Planamente S, Mondy S, Hommais F, Vigouroux A, Moréra S, Faure D. Structural basis for selective GABA binding in bacterial pathogens. Mol Microbiol 2012; 86:1085-99. [PMID: 23043322 DOI: 10.1111/mmi.12043] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2012] [Indexed: 11/27/2022]
Abstract
GABA acts as an intercellular signal in eukaryotes and as an interspecies signal in host-microbe interactions. Structural characteristics of selective eukaryotic GABA receptors and bacterial GABA sensors are unknown. Here, we identified the selective GABA-binding protein, called Atu4243, in the plant pathogen Agrobacterium tumefaciens. A constructed atu4243 mutant was affected in GABA transport and in expression of the GABA-regulated functions, including aggressiveness on two plant hosts and degradation of the quorum-sensing signal. The GABA-bound Atu4243 structure at 1.28 Å reveals that GABA adopts a conformation never observed so far and interacts with two key residues, Arg(203) and Asp(226) of which the role in GABA binding and GABA signalling in Agrobacterium has been validated using appropriate mutants. The conformational GABA-analogue trans-4-aminocrotonic acid (TACA) antagonizes GABA activity, suggesting structural similarities between the binding sites of the bacterial sensor Atu4243 and mammalian GABA(C) receptors. Exploration of genomic databases reveals Atu4243 orthologues in several pathogenic and symbiotic proteobacteria, such as Rhizobium, Azospirillum, Burkholderia and Pseudomonas. Thus, this study establishes a structural basis for selective GABA sensors and offers opportunities for deciphering the role of the GABA-mediated communication in several host-pathogen interactions.
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Affiliation(s)
- Sara Planamente
- Institut des Sciences du Végétal, CNRS, avenue de la terrasse, 91198, Gif-sur-Yvette, France
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39
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Surin AM, Kriukova EV, Strukov AS, Zhmak MN, Talka R, Tuominen R, Salminen O, Khiroug L, Kasheverov IE, Tsetlin VI. [Effect of alpha-conotoxin MII and its N-terminal derivatives on Ca2+ and Na+ signals induced by nicotine in neuroblastoma cell line SH-SY5Y]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2012; 38:214-22. [PMID: 22792725 DOI: 10.1134/s1068162012020112] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are implicated in the regulation ofintracellular Ca2+-dependent processes in cells both in normal and pathological states, alpha-Conotoxins isolated from Conus snails venom are a valuable tool for the study of pharmacological properties and functional role of nAChRs. In the present study the alpha-conotoxin MII analogue with the additional tyrosine attached to the N terminus (Y0-MII) was prepared. Also we synthesized analogs with the N-terminal glycine residue labeled with the Bolton- Hunter reagent (BH-MII) or fluorestsein isothiocyanate (FITC-MII). Fluorescence microscopy studies of the neuroblastoma SH-SY5Y cells loaded with Ca2+ indicator Fura-2 or with Ca2+ and Na+ indicators Fluo-4 and SBFI were performed to examine effect of MII modification on its ability to inhibit nicotin-induced increases in intracellular free Ca2+ and Na+ concentrations ([Ca2+] and [Na+]i respectively). Monitoring of individual cell [Ca2+]i and [Na+]i signals revealed different kinetics of [Ca2+]i and [Na+]i rise and decay in responses to brief nicotine (Nic) applications (10-30 microM, 3-5 min), which indicates to different mechanisms of Ca2+ and Na+ homeostasis control in SH-SY5Y cells. MII inhibited in concentration-dependent manner the both [Ca2+]i and [Na+]i increase induced by Nic. Additional tyrosine in the Y0-MII or, especially, more sizeable label in FITC-MII significantly reduced the inhibitory effect of MII. Whereas the efficiency of the Ca2+ response inhibition by BH-MII was found to be close to the efficiency of its inhibition by natural alpha-conotoxin MII, radioiodinated derivatives BH-MII can be used in radioligand assay.
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40
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Saur M, Moeller V, Kapetanopoulos K, Braukmann S, Gebauer W, Tenzer S, Markl J. Acetylcholine-binding protein in the hemolymph of the planorbid snail Biomphalaria glabrata is a pentagonal dodecahedron (60 subunits). PLoS One 2012; 7:e43685. [PMID: 22916297 PMCID: PMC3423370 DOI: 10.1371/journal.pone.0043685] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 07/24/2012] [Indexed: 11/20/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChR) play important neurophysiological roles and are of considerable medical relevance. They have been studied extensively, greatly facilitated by the gastropod acetylcholine-binding proteins (AChBP) which represent soluble structural and functional homologues of the ligand-binding domain of nAChR. All these proteins are ring-like pentamers. Here we report that AChBP exists in the hemolymph of the planorbid snail Biomphalaria glabrata (vector of the schistosomiasis parasite) as a regular pentagonal dodecahedron, 22 nm in diameter (12 pentamers, 60 active sites). We sequenced and recombinantly expressed two ∼25 kDa polypeptides (BgAChBP1 and BgAChBP2) with a specific active site, N-glycan site and disulfide bridge variation. We also provide the exon/intron structures. Recombinant BgAChBP1 formed pentamers and dodecahedra, recombinant BgAChBP2 formed pentamers and probably disulfide-bridged di-pentamers, but not dodecahedra. Three-dimensional electron cryo-microscopy (3D-EM) yielded a 3D reconstruction of the dodecahedron with a resolution of 6 Å. Homology models of the pentamers docked to the 6 Å structure revealed opportunities for chemical bonding at the inter-pentamer interfaces. Definition of the ligand-binding pocket and the gating C-loop in the 6 Å structure suggests that 3D-EM might lead to the identification of functional states in the BgAChBP dodecahedron.
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Affiliation(s)
- Michael Saur
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
| | - Vanessa Moeller
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
| | | | - Sandra Braukmann
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
| | - Wolfgang Gebauer
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
| | - Stefan Tenzer
- Institute of Immunology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Jürgen Markl
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
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Jara O, Acuña R, García IE, Maripillán J, Figueroa V, Sáez JC, Araya-Secchi R, Lagos CF, Pérez-Acle T, Berthoud VM, Beyer EC, Martínez AD. Critical role of the first transmembrane domain of Cx26 in regulating oligomerization and function. Mol Biol Cell 2012; 23:3299-311. [PMID: 22787277 PMCID: PMC3431943 DOI: 10.1091/mbc.e11-12-1058] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
This study identifies a motif within the first transmembrane domain of Cx26, from amino acids Val-37 through Ala-40, that is critical for oligomerization and function. The impacts of deafness-associated mutations within this motif upon gap junction channel and hemichannel functions correlate with the severity of disease that they cause. To identify motifs involved in oligomerization of the gap junction protein Cx26, we studied individual transmembrane (TM) domains and the full-length protein. Using the TOXCAT assay for interactions of isolated TM α-helices, we found that TM1, a Cx26 pore domain, had a strong propensity to homodimerize. We identified amino acids Val-37–Ala-40 (VVAA) as the TM1 motif required for homodimerization. Two deafness-associated Cx26 mutations localized in this region, Cx26V37I and Cx26A40G, differentially affected dimerization. TM1-V37I dimerized only weakly, whereas TM1-A40G did not dimerize. When the full-length mutants were expressed in HeLa cells, both Cx26V37I and Cx26A40G formed oligomers less efficiently than wild-type Cx26. A Cx26 cysteine substitution mutant, Cx26V37C formed dithiothreitol-sensitive dimers. Substitution mutants of Val-37 formed intercellular channels with reduced function, while mutants of Ala-40 did not form functional gap junction channels. Unlike wild-type Cx26, neither Cx26V37I nor Cx26A40G formed functional hemichannels in low extracellular calcium. Thus the VVAA motif of Cx26 is critical for TM1 dimerization, hexamer formation, and channel function. The differential effects of VVAA mutants on hemichannels and gap junction channels imply that inter-TM interactions can differ in unapposed and docked hemichannels. Moreover, Cx26 oligomerization appears dependent on transient TM1 dimerization as an intermediate step.
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Affiliation(s)
- Oscar Jara
- Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
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De Rienzo F, Moura Barbosa AJ, Perez MA, Fernandes PA, Ramos MJ, Menziani MC. The extracellular subunit interface of the 5-HT3receptors: a computational alanine scanning mutagenesis study. J Biomol Struct Dyn 2012; 30:280-98. [DOI: 10.1080/07391102.2012.680029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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43
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Yu R, Kaas Q, Craik DJ. Delineation of the unbinding pathway of α-conotoxin ImI from the α7 nicotinic acetylcholine receptor. J Phys Chem B 2012; 116:6097-105. [PMID: 22571488 DOI: 10.1021/jp301352d] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
α-Conotoxins potently and specifically inhibit isoforms of nicotinic acetylcholine receptors (nAChRs) and are used as molecular probes and as drugs or drug leads. Interactions occurring during binding and unbinding events are linked to binding kinetics, and knowledge of these interactions could help in the development of α-conotoxins as drugs. Here, the unbinding process for the prototypical α-conotoxin ImI/α7-nAChR system was investigated theoretically, and three exit routes were identified using random accelerated molecular dynamics simulations. The route involving the smallest conformation perturbation was further divided into three subpathways, which were studied using steered molecular dynamics simulations. Of the three subpathways, two had better experimental support and lower potential of mean force, indicating that they might be sampled more frequently. Additionally, these subpathways were supported by previous experimental studies. Several pairwise interactions, including a cation-π interaction and charge and hydrogen bond interactions, were identified as potentially playing important roles in the unbinding event.
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Affiliation(s)
- Rilei Yu
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
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44
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Dallanoce C, Matera C, De Amici M, Rizzi L, Pucci L, Gotti C, Clementi F, De Micheli C. The enantiomers of epiboxidine and of two related analogs: synthesis and estimation of their binding affinity at α4β2 and α7 neuronal nicotinic acetylcholine receptors. Chirality 2012; 24:543-51. [PMID: 22566097 DOI: 10.1002/chir.22052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 03/19/2012] [Indexed: 11/07/2022]
Abstract
Epiboxidine hydrochlorides (+)-2 and (-)-2, which are the structural analogs of the antipodes of epibatidine (±)-1, as well as the enantiomeric pairs (+)-3/(-)-3 and (+)-4/(-)-4 were synthesized and tested for binding affinity at α4β2 and α7 nicotinic acetylcholine receptor (nAChR) subtypes. Final derivatives were prepared through the condensation of racemic N-Boc-7-azabicyclo[2.2.1]heptane-2-one (±)-5 with the resolving agent (R)-(+)-2-methyl-2-propanesulfinamide. The pharmacological analysis carried out on the three new enantiomeric pairs evidenced an overall negligible degree of enantioselectivity at both nAChRs subtypes, a result similar to that reported for both natural and unnatural epibatidine enantiomers at the same investigated receptor subtypes.
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Affiliation(s)
- Clelia Dallanoce
- Dipartimento di Scienze Farmaceutiche Pietro Pratesi, Università degli Studi di Milano, Milano, Italy.
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45
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Gündisch D, Eibl C. Nicotinic acetylcholine receptor ligands, a patent review (2006-2011). Expert Opin Ther Pat 2012; 21:1867-96. [PMID: 22098319 DOI: 10.1517/13543776.2011.637919] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Nicotinic acetylcholine receptors (nAChRs), pentameric ligand-gated cation channels, are potential targets for the development of therapeutics for a variety of disease states. AREAS COVERED This article is reviewing recent advances in the development of small-molecule ligands for diverse nAChR subtypes and is a continuation of an earlier review in this journal. EXPERT OPINION The development of nAChR ligands with preference for α4β2 or α7 subtypes for the treatment of central nervous system disorders are in the most advanced developmental stage. In addition, there is a fast growing interest to generate so-called PAMs, positive allosteric modulators, to influence the channels' functionalities.
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Affiliation(s)
- Daniela Gündisch
- University of Hawai'i at Hilo, College of Pharmacy, Department of Pharmaceutical Sciences, 34 Rainbow Drive, Hilo, HI 96720, USA.
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Intracellular localization of nicotinic acetylcholine receptors in human cell lines. Life Sci 2012; 91:1033-7. [PMID: 22365965 DOI: 10.1016/j.lfs.2012.02.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 01/25/2012] [Accepted: 02/04/2012] [Indexed: 12/31/2022]
Abstract
AIMS Previously we demonstrated that mouse liver mitochondria express functional α7 nicotinic acetylcholine receptors (nAChRs). The aim of this study was to investigate whether the nAChRs are found in mitochondria of non-neuronal human cell lines. MAIN METHODS Three cell lines: U373 (astrocytes), U937 (monocytes) and Daudi (B lymphocytes) were examined by flow cytometry, Cell ELISA and fluorescent confocal microscopy using the antibodies against extracellular epitopes of α3, α4, α7, α9, β2 and β4 nAChR subunits. KEY FINDINGS It is shown that the studied cells expressed different sets of nAChR subunits on the plasma membrane suggesting the presence of α7 nAChRs on all cells, of α3β4 nAChRs on U373 cells and of α4β2/α4β4 nAChRs on U937 cells. In addition to nAChRs exposed on the surface, all cells contained a considerable intracellular pool of α3- and α7-containing nAChRs. The binding of α3-, α7- and β4-specific antibodies partially overlapped with that of mitochondrial outer membrane translocase-specific antibody. Binding of α7-specific antibody also overlapped with that of MitoTracker Green, which binds to active mitochondria. SIGNIFICANCE The data obtained suggest that a part of intracellular α3β4 and α7 nAChRs in U373, U937 and Daudi cells is located on mitochondria. This finding complements our previous observation of α7 nAChRs in mouse liver mitochondria and reveals new intracellular targets for cholinergic regulation.
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Chirumbolo S. Plant-derived extracts in the neuroscience of anxiety on animal models: biases and comments. Int J Neurosci 2011; 122:177-88. [PMID: 22050267 DOI: 10.3109/00207454.2011.635829] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Generalized anxiety disorders probably represent one of the world's biggest mental health problems. A large number of studies have also shown that anxiety disorders and depression are often associated with quality of life impairments. As anxiety represents a big concern in public health, a substantial literature supports clinically important associations between psychiatric illness and chronic medical conditions. Actually, most research focuses on depression, finding that depression can adversely affect self-care and increase the risk of incident medical illness, complications, and mortality. Anxiety disorders are less well studied, but robust epidemiological and clinical evidences show that they play an equally important role. Recent reported articles have raised a debate about the effectiveness of some plant-derived extracts in anxiety-like models in mice. Biases about several aspects related with experimental setting, animal selection, environments, operators and investigators, selection and performance of behavioral tests, controls, results managing, and statistics are here discussed.
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Chaperoning α7 neuronal nicotinic acetylcholine receptors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:718-29. [PMID: 22040696 DOI: 10.1016/j.bbamem.2011.10.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Revised: 09/25/2011] [Accepted: 10/17/2011] [Indexed: 11/22/2022]
Abstract
The α7 subtype of nicotinic acetylcholine receptors (AChRs) is one of the most abundant members of the Cys-loop family of receptors present in the central nervous system. It participates in various physiological processes and has received much attention as a potential therapeutic target for a variety of pathologies. The importance of understanding the mechanisms controlling AChR assembly and cell-surface delivery lies in the fact that these two processes are key to determining the functional pool of receptors actively engaged in synaptic transmission. Here we review recent studies showing that RIC-3, a protein originally identified in the worm Caenorhabditis elegans, modulates the expression of α7 AChRs in a subtype-specific manner. Potentiation of AChR expression by post-transcriptional events is also critically assessed.
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Criado M, Mulet J, Gerber S, Sala S, Sala F. A small cytoplasmic region adjacent to the fourth transmembrane segment of the α7 nicotinic receptor is essential for its biogenesis. FEBS Lett 2011; 585:2477-80. [DOI: 10.1016/j.febslet.2011.06.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 06/21/2011] [Accepted: 06/22/2011] [Indexed: 10/18/2022]
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