1
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Haloi N, Huang S, Nichols AL, Fine EJ, Friesenhahn NJ, Marotta CB, Dougherty DA, Lindahl E, Howard RJ, Mayo SL, Lester HA. Interactive computational and experimental approaches improve the sensitivity of periplasmic binding protein-based nicotine biosensors for measurements in biofluids. Protein Eng Des Sel 2024; 37:gzae003. [PMID: 38302088 PMCID: PMC10896302 DOI: 10.1093/protein/gzae003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 01/17/2024] [Accepted: 01/29/2024] [Indexed: 02/03/2024] Open
Abstract
We developed fluorescent protein sensors for nicotine with improved sensitivity. For iNicSnFR12 at pH 7.4, the proportionality constant for ∆F/F0vs [nicotine] (δ-slope, 2.7 μM-1) is 6.1-fold higher than the previously reported iNicSnFR3a. The activated state of iNicSnFR12 has a fluorescence quantum yield of at least 0.6. We measured similar dose-response relations for the nicotine-induced absorbance increase and fluorescence increase, suggesting that the absorbance increase leads to the fluorescence increase via the previously described nicotine-induced conformational change, the 'candle snuffer' mechanism. Molecular dynamics (MD) simulations identified a binding pose for nicotine, previously indeterminate from experimental data. MD simulations also showed that Helix 4 of the periplasmic binding protein (PBP) domain appears tilted in iNicSnFR12 relative to iNicSnFR3a, likely altering allosteric network(s) that link the ligand binding site to the fluorophore. In thermal melt experiments, nicotine stabilized the PBP of the tested iNicSnFR variants. iNicSnFR12 resolved nicotine in diluted mouse and human serum at 100 nM, the peak [nicotine] that occurs during smoking or vaping, and possibly at the decreasing levels during intervals between sessions. NicSnFR12 was also partially activated by unidentified endogenous ligand(s) in biofluids. Improved iNicSnFR12 variants could become the molecular sensors in continuous nicotine monitors for animal and human biofluids.
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Affiliation(s)
- Nandan Haloi
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm 10044, Sweden
| | - Shan Huang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Eve J Fine
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Nicholas J Friesenhahn
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Christopher B Marotta
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Erik Lindahl
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm 10044, Sweden
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm 10691, Sweden
| | - Rebecca J Howard
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm 10691, Sweden
| | - Stephen L Mayo
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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2
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Haloi N, Huang S, Nichols AL, Fine EJ, Friesenhahn NJ, Marotta CB, Dougherty DA, Lindahl E, Howard RJ, Mayo SL, Lester HA. Interactive computational and experimental approaches improve the sensitivity of periplasmic binding protein-based nicotine biosensors for measurements in biofluids. bioRxiv 2024:2023.01.16.524298. [PMID: 36712031 PMCID: PMC9882114 DOI: 10.1101/2023.01.16.524298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We developed fluorescent protein sensors for nicotine with improved sensitivity. For iNicSnFR12 at pH 7.4, the proportionality constant for Δ F / F 0 vs [nicotine] (δ-slope, 2.7 μM-1) is 6.1-fold higher than the previously reported iNicSnFR3a. The activated state of iNicSnFR12 has a fluorescence quantum yield of at least 0.6. We measured similar dose-response relations for the nicotine-induced absorbance increase and fluorescence increase, suggesting that the absorbance increase leads to the fluorescence increase via the previously described nicotine-induced conformational change, the "candle snuffer" mechanism. Molecular dynamics (MD) simulations identified a binding pose for nicotine, previously indeterminate from experimental data. MD simulations also showed that Helix 4 of the periplasmic binding protein (PBP) domain appears tilted in iNicSnFR12 relative to iNicSnFR3a, likely altering allosteric network(s) that link the ligand binding site to the fluorophore. In thermal melt experiments, nicotine stabilized the PBP of the tested iNicSnFR variants. iNicSnFR12 resolved nicotine in diluted mouse and human serum at 100 nM, the peak [nicotine] that occurs during smoking or vaping, and possibly at the decreasing levels during intervals between sessions. NicSnFR12 was also partially activated by unidentified endogenous ligand(s) in biofluids. Improved iNicSnFR12 variants could become the molecular sensors in continuous nicotine monitors for animal and human biofluids.
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Affiliation(s)
- Nandan Haloi
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, 10044 Stockholm, Sweden
| | - Shan Huang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Eve J Fine
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Nicholas J Friesenhahn
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Christopher B Marotta
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Erik Lindahl
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, 10044 Stockholm, Sweden
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, 10691 Stockholm, Sweden
| | - Rebecca J Howard
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, 10691 Stockholm, Sweden
| | - Stephen L Mayo
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
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3
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Blumenfeld Z, Bera K, Castrén E, Lester HA. Antidepressants enter cells, organelles, and membranes. Neuropsychopharmacology 2024; 49:246-261. [PMID: 37783840 PMCID: PMC10700606 DOI: 10.1038/s41386-023-01725-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/28/2023] [Accepted: 08/28/2023] [Indexed: 10/04/2023]
Abstract
We begin by summarizing several examples of antidepressants whose therapeutic actions begin when they encounter their targets in the cytoplasm or in the lumen of an organelle. These actions contrast with the prevailing view that most neuropharmacological actions begin when drugs engage their therapeutic targets at extracellular binding sites of plasma membrane targets-ion channels, receptors, and transporters. We review the chemical, pharmacokinetic, and pharmacodynamic principles underlying the movements of drugs into subcellular compartments. We note the relationship between protonation-deprotonation events and membrane permeation of antidepressant drugs. The key properties relate to charge and hydrophobicity/lipid solubility, summarized by the parameters LogP, pKa, and LogDpH7.4. The classical metric, volume of distribution (Vd), is unusually large for some antidepressants and has both supracellular and subcellular components. A table gathers structures, LogP, PKa, LogDpH7.4, and Vd data and/or calculations for most antidepressants and antidepressant candidates. The subcellular components, which can now be measured in some cases, are dominated by membrane binding and by trapping in the lumen of acidic organelles. For common antidepressants, such as selective serotonin reuptake inhibitors (SSRIs) and serotonin/norepinephrine reuptake inhibitors (SNRIs), the target is assumed to be the eponymous reuptake transporter(s), although in fact the compartment of target engagement is unknown. We review special aspects of the pharmacokinetics of ketamine, ketamine metabolites, and other rapidly acting antidepressants (RAADs) including methoxetamine and scopolamine, psychedelics, and neurosteroids. Therefore, the reader can assess properties that markedly affect a drug's ability to enter or cross membranes-and therefore, to interact with target sites that face the cytoplasm, the lumen of organelles, or a membrane. In the current literature, mechanisms involving intracellular targets are termed "location-biased actions" or "inside-out pharmacology". Hopefully, these general terms will eventually acquire additional mechanistic details.
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Affiliation(s)
- Zack Blumenfeld
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
- Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Kallol Bera
- Department of Neurosciences and Howard Hughes Medical Institute, University of California at San Diego, La Jolla, CA, USA
| | - Eero Castrén
- Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
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4
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Walker NB, Yan Y, Tapia MA, Tucker BR, Thomas LN, George BE, West AM, Marotta CB, Lester HA, Dougherty DA, Holleran KM, Jones SR, Drenan RM. β2 nAChR Activation on VTA DA Neurons Is Sufficient for Nicotine Reinforcement in Rats. eNeuro 2023; 10:ENEURO.0449-22.2023. [PMID: 37193602 PMCID: PMC10216253 DOI: 10.1523/eneuro.0449-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 05/01/2023] [Accepted: 05/08/2023] [Indexed: 05/18/2023] Open
Abstract
Mesolimbic nicotinic acetylcholine receptor (nAChRs) activation is necessary for nicotine reinforcement behavior, but it is unknown whether selective activation of nAChRs in the dopamine (DA) reward pathway is sufficient to support nicotine reinforcement. In this study, we tested the hypothesis that activation of β2-containing (β2*) nAChRs on VTA neurons is sufficient for intravenous nicotine self-administration (SA). We expressed β2 nAChR subunits with enhanced sensitivity to nicotine (referred to as β2Leu9'Ser) in the VTA of male Sprague Dawley (SD) rats, enabling very low concentrations of nicotine to selectively activate β2* nAChRs on transduced neurons. Rats expressing β2Leu9'Ser subunits acquired nicotine SA at 1.5 μg/kg/infusion, a dose too low to support acquisition in control rats. Saline substitution extinguished responding for 1.5 μg/kg/inf, verifying that this dose was reinforcing. β2Leu9'Ser nAChRs also supported acquisition at the typical training dose in rats (30 μg/kg/inf) and reducing the dose to 1.5 μg/kg/inf caused a significant increase in the rate of nicotine SA. Viral expression of β2Leu9'Ser subunits only in VTA DA neurons (via TH-Cre rats) also enabled acquisition of nicotine SA at 1.5 μg/kg/inf, and saline substitution significantly attenuated responding. Next, we examined electrically-evoked DA release in slices from β2Leu9'Ser rats with a history of nicotine SA. Single-pulse evoked DA release and DA uptake rate were reduced in β2Leu9'Ser NAc slices, but relative increases in DA following a train of stimuli were preserved. These results are the first to report that β2* nAChR activation on VTA neurons is sufficient for nicotine reinforcement in rats.
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Affiliation(s)
- Noah B Walker
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Yijin Yan
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Melissa A Tapia
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Brenton R Tucker
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Leanne N Thomas
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Brianna E George
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Alyssa M West
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Christopher B Marotta
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91106
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91106
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91106
| | - Katherine M Holleran
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Sara R Jones
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Ryan M Drenan
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
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5
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Maldifassi MC, Campello HR, Gallagher T, Lester HA, Dougherty DA. Human α6β4 nicotinic acetylcholine receptor: heterologous expression and agonist behavior provide insights into the immediate binding site. Mol Pharmacol 2023; 103:339-347. [PMID: 37001996 DOI: 10.1124/molpharm.123.000672] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/09/2023] [Accepted: 03/15/2023] [Indexed: 04/03/2023] Open
Abstract
Study of α6β4 nicotinic acetylcholine receptors (nAChRs) as a pharmacological target has recently gained interest because of their involvement in analgesia, control of catecholamine secretion, dopaminergic pathways, and aversive pathways. However, an extensive characterization of the human α6β4 nAChRs has been vitiated by technical difficulties resulting in poor receptor expression. In 2020, Knowland and collaborators identified BARP (β-anchoring and regulatory protein), a previously known voltage-gated calcium channel suppressor, as a novel human α6β4 chaperone. Here, we establish that co-expression of human BARP with human α6β4 in Xenopus oocytes, resulted in the functional expression of human α6β4 receptors with acetylcholine-elicited currents that allow an in-depth characterization of the receptor using two electrode voltage-clamp electrophysiology together with diverse agonists and receptor mutations. We report: 1) an extended pharmacological characterization of the receptor, and 2) key residues for agonist-activity located in or near the first shell of the binding pocket. SIGNIFICANCE STATEMENT: The human α6β4 nicotinic acetylcholine receptor has attained increased interest because of its involvement in diverse physiological processes and diseases. Although recognized as a pharmacological target, development of specific agonists has been hampered by limited knowledge of its structural characteristics and by challenges in expressing the receptor. By including the chaperone β-anchoring and regulatory protein for enhanced expression and employing different ligands, we have studied the pharmacology of α6β4, providing insight into receptor residues and structural requirements for ligands important to consider for agonist-induced activation.
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6
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Nichols AL, Blumenfeld Z, Luebbert L, Knox HJ, Muthusamy AK, Marvin JS, Kim CH, Grant SN, Walton DP, Cohen BN, Hammar R, Looger L, Artursson P, Dougherty DA, Lester HA. Selective Serotonin Reuptake Inhibitors within Cells: Temporal Resolution in Cytoplasm, Endoplasmic Reticulum, and Membrane. J Neurosci 2023; 43:2222-2241. [PMID: 36868853 PMCID: PMC10072302 DOI: 10.1523/jneurosci.1519-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 11/02/2022] [Accepted: 11/27/2022] [Indexed: 03/05/2023] Open
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are the most prescribed treatment for individuals experiencing major depressive disorder. The therapeutic mechanisms that take place before, during, or after SSRIs bind the serotonin transporter (SERT) are poorly understood, partially because no studies exist on the cellular and subcellular pharmacokinetic properties of SSRIs in living cells. We studied escitalopram and fluoxetine using new intensity-based, drug-sensing fluorescent reporters targeted to the plasma membrane, cytoplasm, or endoplasmic reticulum (ER) of cultured neurons and mammalian cell lines. We also used chemical detection of drug within cells and phospholipid membranes. The drugs attain equilibrium in neuronal cytoplasm and ER at approximately the same concentration as the externally applied solution, with time constants of a few s (escitalopram) or 200-300 s (fluoxetine). Simultaneously, the drugs accumulate within lipid membranes by ≥18-fold (escitalopram) or 180-fold (fluoxetine), and possibly by much larger factors. Both drugs leave cytoplasm, lumen, and membranes just as quickly during washout. We synthesized membrane-impermeant quaternary amine derivatives of the two SSRIs. The quaternary derivatives are substantially excluded from membrane, cytoplasm, and ER for >2.4 h. They inhibit SERT transport-associated currents sixfold or 11-fold less potently than the SSRIs (escitalopram or fluoxetine derivative, respectively), providing useful probes for distinguishing compartmentalized SSRI effects. Although our measurements are orders of magnitude faster than the therapeutic lag of SSRIs, these data suggest that SSRI-SERT interactions within organelles or membranes may play roles during either the therapeutic effects or the antidepressant discontinuation syndrome.SIGNIFICANCE STATEMENT Selective serotonin reuptake inhibitors stabilize mood in several disorders. In general, these drugs bind to SERT, which clears serotonin from CNS and peripheral tissues. SERT ligands are effective and relatively safe; primary care practitioners often prescribe them. However, they have several side effects and require 2-6 weeks of continuous administration until they act effectively. How they work remains perplexing, contrasting with earlier assumptions that the therapeutic mechanism involves SERT inhibition followed by increased extracellular serotonin levels. This study establishes that two SERT ligands, fluoxetine and escitalopram, enter neurons within minutes, while simultaneously accumulating in many membranes. Such knowledge will motivate future research, hopefully revealing where and how SERT ligands engage their therapeutic target(s).
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Affiliation(s)
- Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91106
| | - Zack Blumenfeld
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91106
- Keck School of Medicine, University of Southern California, Los Angeles, California 90007
| | - Laura Luebbert
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91106
- Institute of Biology, Leiden University, 2333 BE Leiden, The Netherlands
| | - Hailey J Knox
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91106
| | - Anand K Muthusamy
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91106
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Viginia 20147
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91106
| | - Stephen N Grant
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91106
| | - David P Walton
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91106
| | - Bruce N Cohen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91106
| | - Rebekkah Hammar
- Department of Pharmacy, Uppsala University, SE-751 23 Uppsala, Sweden
| | - Loren Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Viginia 20147
| | - Per Artursson
- Department of Pharmacy, Uppsala University, SE-751 23 Uppsala, Sweden
- Science for Life Laboratory Drug Discovery and Development Platform and Uppsala University Drug Optimization and Pharmaceutical Profiling Platform, Uppsala University, SE-751 23 Uppsala, Sweden
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91106
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91106
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7
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Nichols AL, Blumenfeld Z, Fan C, Luebbert L, Blom AEM, Cohen BN, Marvin JS, Borden PM, Kim CH, Muthusamy AK, Shivange AV, Knox HJ, Campello HR, Wang JH, Dougherty DA, Looger LL, Gallagher T, Rees DC, Lester HA. Correction: Fluorescence activation mechanism and imaging of drug permeation with new sensors for smoking-cessation ligands. eLife 2022; 11:e85479. [PMID: 36520038 PMCID: PMC9754624 DOI: 10.7554/elife.85479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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8
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Beatty ZG, Muthusamy AK, Unger EK, Dougherty DA, Tian L, Looger LL, Shivange AV, Bera K, Lester HA, Nichols AL. Fluorescence Screens for Identifying Central Nervous System-Acting Drug-Biosensor Pairs for Subcellular and Supracellular Pharmacokinetics. Bio Protoc 2022; 12:e4551. [PMID: 36532688 PMCID: PMC9724018 DOI: 10.21769/bioprotoc.4551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/17/2022] [Accepted: 09/12/2022] [Indexed: 11/19/2022] Open
Abstract
Subcellular pharmacokinetic measurements have informed the study of central nervous system (CNS)-acting drug mechanisms. Recent investigations have been enhanced by the use of genetically encoded fluorescent biosensors for drugs of interest at the plasma membrane and in organelles. We describe screening and validation protocols for identifying hit pairs comprising a drug and biosensor, with each screen including 13-18 candidate biosensors and 44-84 candidate drugs. After a favorable hit pair is identified and validated via these protocols, the biosensor is then optimized, as described in other papers, for sensitivity and selectivity to the drug. We also show sample hit pair data that may lead to future intensity-based drug-sensing fluorescent reporters (iDrugSnFRs). These protocols will assist scientists to use fluorescence responses as criteria in identifying favorable fluorescent biosensor variants for CNS-acting drugs that presently have no corresponding biosensor partner. This protocol was validated in: eLife (2022), DOI: 10.7554/eLife.74648 Graphical abstract.
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Affiliation(s)
- Zoe G. Beatty
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, USA
| | - Anand K. Muthusamy
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, USA
| | - Elizabeth K. Unger
- Department of Biochemistry and Molecular Medicine and the Center for Neuroscience, University of California at Davis, Davis, USA
| | - Dennis A. Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, USA
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine and the Center for Neuroscience, University of California at Davis, Davis, USA
| | | | - Amol V. Shivange
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, USA
| | - Kallol Bera
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, USA
| | - Henry A. Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, USA
| | - Aaron L. Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, USA
,
*For correspondence:
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9
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Knox HJ, Rego Campello H, Lester HA, Gallagher T, Dougherty DA. Characterization of Binding Site Interactions and Selectivity Principles in the α3β4 Nicotinic Acetylcholine Receptor. J Am Chem Soc 2022; 144:16101-16117. [PMID: 36006801 DOI: 10.1021/jacs.2c06495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) play an important role in neurotransmission and are also involved in addiction and several disease states. There is significant interest in therapeutic targeting of nAChRs; however, achieving selectivity for one subtype over others has been a longstanding challenge, given the close structural similarities across the family. Here, we characterize binding interactions in the α3β4 nAChR subtype via structure-function studies involving noncanonical amino acid mutagenesis and two-electrode voltage clamp electrophysiology. We establish comprehensive binding models for both the endogenous neurotransmitter ACh and the smoking cessation drug cytisine. We also use a panel of C(10)-substituted cytisine derivatives to probe the effects of subtle changes in the ligand structure on binding. By comparing our results to those obtained for the well-studied α4β2 subtype, we identify several features of both the receptor and agonist structure that can be utilized to enhance selectivity for either α3β4 or α4β2. Finally, we characterize binding interactions of the α3β4-selective partial agonist AT-1001 to determine factors that contribute to its selectivity. These results shed new light on the design of selective nAChR-targeted ligands and can be used to inform the design of improved therapies with minimized off-target effects.
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Affiliation(s)
- Hailey J Knox
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | | | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | | | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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10
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Muthusamy A, Kim CH, Virgil SC, Knox HJ, Marvin JS, Nichols AL, Cohen BN, Dougherty DA, Looger LL, Lester HA. Three Mutations Convert the Selectivity of a Protein Sensor from Nicotinic Agonists to S-Methadone for Use in Cells, Organelles, and Biofluids. J Am Chem Soc 2022; 144:8480-8486. [PMID: 35446570 PMCID: PMC9121368 DOI: 10.1021/jacs.2c02323] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Indexed: 11/28/2022]
Abstract
We report a reagentless, intensity-based S-methadone fluorescent sensor, iS-methadoneSnFR, consisting of a circularly permuted GFP inserted within the sequence of a mutated bacterial periplasmic binding protein (PBP). We evolved a previously reported nicotine-binding PBP to become a selective S-methadone-binding sensor, via three mutations in the PBP's second shell and hinge regions. iS-methadoneSnFR displays the necessary sensitivity, kinetics, and selectivity─notably enantioselectivity against R-methadone─for biological applications. Robust iS-methadoneSnFR responses in human sweat and saliva and mouse serum enable diagnostic uses. Expression and imaging in mammalian cells demonstrate that S-methadone enters at least two organelles and undergoes acid trapping in the Golgi apparatus, where opioid receptors can signal. This work shows a straightforward strategy in adapting existing PBPs to serve real-time applications ranging from subcellular to personal pharmacokinetics.
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Affiliation(s)
- Anand
K. Muthusamy
- Division
of Biology and Biological Engineering, California
Institute of Technology, Pasadena, California 91106, United States
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91106, United States
| | - Charlene H. Kim
- Division
of Biology and Biological Engineering, California
Institute of Technology, Pasadena, California 91106, United States
| | - Scott C. Virgil
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91106, United States
| | - Hailey J. Knox
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91106, United States
| | - Jonathan S. Marvin
- Howard
Hughes Medical Institute, Janelia Research Campus, Ashburn, Virginia 20147, United States
| | - Aaron L. Nichols
- Division
of Biology and Biological Engineering, California
Institute of Technology, Pasadena, California 91106, United States
| | - Bruce N. Cohen
- Division
of Biology and Biological Engineering, California
Institute of Technology, Pasadena, California 91106, United States
| | - Dennis A. Dougherty
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91106, United States
| | - Loren L. Looger
- Howard
Hughes Medical Institute, University of
California, San Diego, San Diego, California 92093, United States
| | - Henry A. Lester
- Division
of Biology and Biological Engineering, California
Institute of Technology, Pasadena, California 91106, United States
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11
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Nichols AL, Blumenfeld Z, Fan C, Luebbert L, Blom AEM, Cohen BN, Marvin JS, Borden PM, Kim CH, Muthusamy AK, Shivange AV, Knox HJ, Campello HR, Wang JH, Dougherty DA, Looger LL, Gallagher T, Rees DC, Lester HA. Fluorescence activation mechanism and imaging of drug permeation with new sensors for smoking-cessation ligands. eLife 2022; 11:e74648. [PMID: 34982029 PMCID: PMC8820738 DOI: 10.7554/elife.74648] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 01/03/2022] [Indexed: 12/16/2022] Open
Abstract
Nicotinic partial agonists provide an accepted aid for smoking cessation and thus contribute to decreasing tobacco-related disease. Improved drugs constitute a continued area of study. However, there remains no reductionist method to examine the cellular and subcellular pharmacokinetic properties of these compounds in living cells. Here, we developed new intensity-based drug-sensing fluorescent reporters (iDrugSnFRs) for the nicotinic partial agonists dianicline, cytisine, and two cytisine derivatives - 10-fluorocytisine and 9-bromo-10-ethylcytisine. We report the first atomic-scale structures of liganded periplasmic binding protein-based biosensors, accelerating development of iDrugSnFRs and also explaining the activation mechanism. The nicotinic iDrugSnFRs detect their drug partners in solution, as well as at the plasma membrane (PM) and in the endoplasmic reticulum (ER) of cell lines and mouse hippocampal neurons. At the PM, the speed of solution changes limits the growth and decay rates of the fluorescence response in almost all cases. In contrast, we found that rates of membrane crossing differ among these nicotinic drugs by >30-fold. The new nicotinic iDrugSnFRs provide insight into the real-time pharmacokinetic properties of nicotinic agonists and provide a methodology whereby iDrugSnFRs can inform both pharmaceutical neuroscience and addiction neuroscience.
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Affiliation(s)
- Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Zack Blumenfeld
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
- Keck School of Medicine, University of Southern CaliforniaLos AngelesUnited States
| | - Chengcheng Fan
- Division of Chemistry and Chemical Engineering, California Institute of TechnologyPasadenaUnited States
| | - Laura Luebbert
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
- Institute of Biology, Leiden UniversityLeidenNetherlands
| | - Annet EM Blom
- Division of Chemistry and Chemical Engineering, California Institute of TechnologyPasadenaUnited States
| | - Bruce N Cohen
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Philip M Borden
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Anand K Muthusamy
- Division of Chemistry and Chemical Engineering, California Institute of TechnologyPasadenaUnited States
| | - Amol V Shivange
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Hailey J Knox
- Division of Chemistry and Chemical Engineering, California Institute of TechnologyPasadenaUnited States
| | | | - Jonathan H Wang
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of TechnologyPasadenaUnited States
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | | | - Douglas C Rees
- Division of Chemistry and Chemical Engineering, California Institute of TechnologyPasadenaUnited States
- Howard Hughes Medical Institute, California Institute of TechnologyPasadenaUnited States
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
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12
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Mulcahy MJ, Huard SM, Paulo JA, Wang JH, McKinney S, Marks MJ, Henderson BJ, Lester HA. Protein profiling in the habenula after chronic (-)-menthol exposure in mice. J Neurochem 2021; 158:1345-1358. [PMID: 34407206 DOI: 10.1111/jnc.15495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 07/10/2021] [Accepted: 08/11/2021] [Indexed: 11/30/2022]
Abstract
The identification of proteins that are altered following nicotine/tobacco exposure can facilitate and positively impact the investigation of related diseases. In this report, we investigated the effects of chronic (-)-menthol exposure in 14 murine brain regions for changes in total β2 subunit protein levels and changes in epibatidine binding levels using immunoblotting and radioligand binding assays. We identified the habenula as a region of interest due to the region's marked decreases in β2 subunit and nAChR levels in response to chronic (-)-menthol alone. Thus, we further examined the habenula, a brain region associated with both the reward and withdrawal components of addiction, for additional protein level alterations using mass spectrometry. A total of 552 proteins with altered levels were identified after chronic (-)-menthol exposure. Enriched in the proteins with altered levels after (-)-menthol exposure were proteins associated with signaling, immune systems, RNA regulation, and protein transport. The continuation and expansion of the brain region-specific protein profiling in response to (-)-menthol will provide a better understanding of how this common flavorant in tobacco and e-liquid products may affect addiction and general health.
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Affiliation(s)
- Matthew J Mulcahy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Stephanie M Huard
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Jonathan H Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Sheri McKinney
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Michael J Marks
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Brandon J Henderson
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
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13
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Grant SN, Lester HA. Regulation of epithelial sodium channel activity by SARS-CoV-1 and SARS-CoV-2 proteins. Biophys J 2021; 120:2805-2813. [PMID: 34197807 PMCID: PMC8238646 DOI: 10.1016/j.bpj.2021.06.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 04/21/2021] [Accepted: 06/03/2021] [Indexed: 01/06/2023] Open
Abstract
Severe acute respiratory syndrome (SARS) coronavirus (CoV) 2 (SARS-CoV-2), which causes the coronavirus disease 2019, encodes several proteins whose roles are poorly understood. We tested their ability either to directly form plasma membrane ion channels or to change functions of two mammalian plasma membrane ion channels, the epithelial sodium channel (ENaC) and the α3β4 nicotinic acetylcholine receptor. In mRNA-injected Xenopus oocytes, none of nine SARS-CoV-2 proteins or two SARS-CoV-1 proteins produced conductances, nor did co-injection of several combinations. Immunoblots for ORF8, spike (S), and envelope (E) proteins revealed that the proteins are expressed at appropriate molecular weights. In experiments on coexpression with ENaC, three tested SARS proteins (SARS-CoV-1 E, SARS-CoV-2 E, and SARS-CoV-2 S) markedly decrease ENaC currents. SARS-CoV-1 S protein decreases ENaC currents modestly. Coexpressing the E proteins but not the S proteins with α3β4 nicotinic acetylcholine receptors significantly reduces acetylcholine-induced currents. ENaC inhibition does not occur if the SARS-CoV protein mRNAs are injected 24 h after the ENaC mRNAs, suggesting that SARS-CoV proteins affect early step(s) in functional expression of channel proteins. Consistent with the hypothesis that the SARS-CoV-2 S protein-induced ENaC inhibition involves competition for available protease, mutating the furin cleavage site in SARS-CoV-2 S protein partially relieves inhibition of ENaC currents. Extending previous suggestions that SARS proteins affect ENaC currents via protein kinase C (PKC) activation, PKC activation via phorbol 12-myristate 13-acetate decreases ENaC and α3β4 activity. Phorbol 12-myristate 13-acetate application reduced membrane capacitance ∼5%, presumably via increased endocytosis, but this decrease is much smaller than the SARS proteins' effects on conductances. Also, incubating oocytes in Gö-6976, a PKCα and PKCβ inhibitor, did not alter E or S protein-induced channel inhibition. We conclude that SARS-CoV-1 and SARS-CoV-2 proteins alter the function of human plasma membrane channels, via incompletely understood mechanisms. These interactions may play a role in the coronavirus 2019 pathophysiology.
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Affiliation(s)
- Stephen N Grant
- Division of Chemistry and Chemical Engineering, Pasadena, California
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California.
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14
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Grant S, Lester HA. Proteins for increased surface expression of the α6β4 nicotinic acetylcholine receptor: nothing but good news? J Clin Invest 2021; 130:5685-5687. [PMID: 33074245 DOI: 10.1172/jci143197] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Useful animal models of disease in neuroscience can make accurate predictions about a therapeutic outcome, a feature known as predictive validity. In this issue of the JCI, Knowland et al. provide an improved model to assess nicotinic acetylcholine receptor (nAChR) ligands for treating chronic pain. The authors identify two proteins, the voltage-dependent calcium channel auxiliary subunit BARP and the unfolded protein response sensor IRE1α, that are required for robust heterologous expression of α6β4, an nAChR subtype in dorsal root ganglia (DRG). This nAChR is a candidate for the analgesic effects of nicotine as well as the frog toxin epibatidine. Now researchers can efficiently screen for α6β4 nAChR-selective agonists using heterologous expression systems. Candidates that emerge will enable researchers to test the predictive validity of mouse models for chronic pain in the nAChR context. If all these steps work, one can envision a class of non-opioid nAChR-targeted analgesics for chronic pain.
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Affiliation(s)
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
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15
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Unger EK, Keller JP, Altermatt M, Liang R, Matsui A, Dong C, Hon OJ, Yao Z, Sun J, Banala S, Flanigan ME, Jaffe DA, Hartanto S, Carlen J, Mizuno GO, Borden PM, Shivange AV, Cameron LP, Sinning S, Underhill SM, Olson DE, Amara SG, Temple Lang D, Rudnick G, Marvin JS, Lavis LD, Lester HA, Alvarez VA, Fisher AJ, Prescher JA, Kash TL, Yarov-Yarovoy V, Gradinaru V, Looger LL, Tian L. Directed Evolution of a Selective and Sensitive Serotonin Sensor via Machine Learning. Cell 2020; 183:1986-2002.e26. [PMID: 33333022 PMCID: PMC8025677 DOI: 10.1016/j.cell.2020.11.040] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 06/22/2020] [Accepted: 11/20/2020] [Indexed: 12/28/2022]
Abstract
Serotonin plays a central role in cognition and is the target of most pharmaceuticals for psychiatric disorders. Existing drugs have limited efficacy; creation of improved versions will require better understanding of serotonergic circuitry, which has been hampered by our inability to monitor serotonin release and transport with high spatial and temporal resolution. We developed and applied a binding-pocket redesign strategy, guided by machine learning, to create a high-performance, soluble, fluorescent serotonin sensor (iSeroSnFR), enabling optical detection of millisecond-scale serotonin transients. We demonstrate that iSeroSnFR can be used to detect serotonin release in freely behaving mice during fear conditioning, social interaction, and sleep/wake transitions. We also developed a robust assay of serotonin transporter function and modulation by drugs. We expect that both machine-learning-guided binding-pocket redesign and iSeroSnFR will have broad utility for the development of other sensors and in vitro and in vivo serotonin detection, respectively.
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Affiliation(s)
- Elizabeth K Unger
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Jacob P Keller
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA
| | - Michael Altermatt
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Ruqiang Liang
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Aya Matsui
- Laboratory on Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Chunyang Dong
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Olivia J Hon
- Bowles Center for Alcohol Studies, Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Zi Yao
- Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Junqing Sun
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Samba Banala
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA
| | - Meghan E Flanigan
- Bowles Center for Alcohol Studies, Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - David A Jaffe
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Samantha Hartanto
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Jane Carlen
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Grace O Mizuno
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Phillip M Borden
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA
| | - Amol V Shivange
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Lindsay P Cameron
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Steffen Sinning
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Suzanne M Underhill
- Laboratory of Molecular and Cellular Neurobiology, National Institute on Mental Health, NIH, Bethesda, MD 20892, USA
| | - David E Olson
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Susan G Amara
- Laboratory of Molecular and Cellular Neurobiology, National Institute on Mental Health, NIH, Bethesda, MD 20892, USA
| | - Duncan Temple Lang
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Gary Rudnick
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Veronica A Alvarez
- Laboratory on Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Andrew J Fisher
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Jennifer A Prescher
- Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Thomas L Kash
- Bowles Center for Alcohol Studies, Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Vladimir Yarov-Yarovoy
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Viviana Gradinaru
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA.
| | - Lin Tian
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA.
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16
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Abstract
In this issue of Neuron, Gharpure et al. (2019) nearly complete atomic-level descriptions for binding, permeation, and subunit interactions at the two major heteropentameric nicotinic receptors-those governing nicotine's rewarding and aversive effects. Can we finally design highly selective and useful nicotinic drugs?
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Affiliation(s)
- Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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17
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Bera K, Kamajaya A, Shivange AV, Muthusamy AK, Nichols AL, Borden PM, Grant S, Jeon J, Lin E, Bishara I, Chin TM, Cohen BN, Kim CH, Unger EK, Tian L, Marvin JS, Looger LL, Lester HA. Biosensors Show the Pharmacokinetics of S-Ketamine in the Endoplasmic Reticulum. Front Cell Neurosci 2019; 13:499. [PMID: 31798415 PMCID: PMC6874132 DOI: 10.3389/fncel.2019.00499] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 10/22/2019] [Indexed: 12/20/2022] Open
Abstract
The target for the “rapid” (<24 h) antidepressant effects of S-ketamine is unknown, vitiating programs to rationally develop more effective rapid antidepressants. To describe a drug’s target, one must first understand the compartments entered by the drug, at all levels—the organ, the cell, and the organelle. We have, therefore, developed molecular tools to measure the subcellular, organellar pharmacokinetics of S-ketamine. The tools are genetically encoded intensity-based S-ketamine-sensing fluorescent reporters, iSKetSnFR1 and iSKetSnFR2. In solution, these biosensors respond to S-ketamine with a sensitivity, S-slope = delta(F/F0)/(delta[S-ketamine]) of 0.23 and 1.9/μM, respectively. The iSKetSnFR2 construct allows measurements at <0.3 μM S-ketamine. The iSKetSnFR1 and iSKetSnFR2 biosensors display >100-fold selectivity over other ligands tested, including R-ketamine. We targeted each of the sensors to either the plasma membrane (PM) or the endoplasmic reticulum (ER). Measurements on these biosensors expressed in Neuro2a cells and in human dopaminergic neurons differentiated from induced pluripotent stem cells (iPSCs) show that S-ketamine enters the ER within a few seconds after appearing in the external solution near the PM, then leaves as rapidly after S-ketamine is removed from the extracellular solution. In cells, S-slopes for the ER and PM-targeted sensors differ by <2-fold, indicating that the ER [S-ketamine] is less than 2-fold different from the extracellular [S-ketamine]. Organelles represent potential compartments for the engagement of S-ketamine with its antidepressant target, and potential S-ketamine targets include organellar ion channels, receptors, and transporters.
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Affiliation(s)
- Kallol Bera
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Aron Kamajaya
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Amol V Shivange
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Anand K Muthusamy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States.,Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States.,Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Philip M Borden
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
| | - Stephen Grant
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Janice Jeon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Elaine Lin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Ishak Bishara
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Theodore M Chin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Bruce N Cohen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Elizabeth K Unger
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, United States
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, United States
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
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18
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Mulcahy MJ, Huard SM, Paulo JA, Wang JH, McKinney S, Henderson BJ, Lester HA. Brain Region-Specific nAChR and Associated Protein Abundance Alterations Following Chronic Nicotine and/or Menthol Exposure. J Proteome Res 2019; 19:36-48. [PMID: 31657575 DOI: 10.1021/acs.jproteome.9b00286] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The identification of biomarkers that are altered following nicotine/tobacco exposure can facilitate the investigation of tobacco-related diseases. Nicotinic acetylcholine receptors (nAChRs) are pentameric cation channels expressed in the mammalian central and peripheral nervous systems and the neuromuscular junction. Neuronal nAChR subunits (11) have been identified in mammals (α2-7, α9-10, β2-4). We examined changes in β2 nAChR subunit protein levels after chronic nicotine, (±)-menthol, or nicotine co-administered with (±)-menthol in nine murine brain regions. Our investigation of β2 nAChR subunit level changes identified the hypothalamus as a novel region of interest for menthol exposure that demonstrated increased β2 nAChR levels after (±)-menthol plus nicotine exposure compared to nicotine exposure alone. Using mass spectrometry, we further characterized changes in membrane protein abundance profiles in the hypothalamus to identify potential biomarkers of (±)-menthol plus nicotine exposure and proteins that may contribute to the elevated β2 nAChR subunit levels. In the hypothalamus, 272 membrane proteins were identified with altered abundances after chronic nicotine plus menthol exposure with respect to chronic nicotine exposure without menthol. A comprehensive investigation of changes in nAChR and non-nAChR protein expression resulting from (±)-menthol plus nicotine in the brain may establish biomarkers to better understand the effects of these drugs on addiction and addiction-related diseases.
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Affiliation(s)
- Matthew J Mulcahy
- Division of Biology and Biological Engineering , California Institute of Technology , 1200 East California Boulevard , Pasadena , California 91125-2900 , United States
| | - Stephanie M Huard
- Division of Biology and Biological Engineering , California Institute of Technology , 1200 East California Boulevard , Pasadena , California 91125-2900 , United States
| | - Joao A Paulo
- Department of Cell Biology , Harvard Medical School , 240 Longwood Avenue , Boston , Massachusetts 02115 , United States
| | - Jonathan H Wang
- Division of Biology and Biological Engineering , California Institute of Technology , 1200 East California Boulevard , Pasadena , California 91125-2900 , United States
| | - Sheri McKinney
- Division of Biology and Biological Engineering , California Institute of Technology , 1200 East California Boulevard , Pasadena , California 91125-2900 , United States
| | - Brandon J Henderson
- Division of Biology and Biological Engineering , California Institute of Technology , 1200 East California Boulevard , Pasadena , California 91125-2900 , United States.,Department of Biomedical Sciences , Joan C. Edwards School of Medicine, Marshall University , Huntington , West Virginia 25701 , United States
| | - Henry A Lester
- Division of Biology and Biological Engineering , California Institute of Technology , 1200 East California Boulevard , Pasadena , California 91125-2900 , United States
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19
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Blom AE, Campello HR, Lester HA, Gallagher T, Dougherty DA. Probing Binding Interactions of Cytisine Derivatives to the α4β2 Nicotinic Acetylcholine Receptor. J Am Chem Soc 2019; 141:15840-15849. [DOI: 10.1021/jacs.9b06580] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
| | - Hugo Rego Campello
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | | | - Timothy Gallagher
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
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20
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Shivange AV, Borden PM, Muthusamy AK, Nichols AL, Bera K, Bao H, Bishara I, Jeon J, Mulcahy MJ, Cohen B, O'Riordan SL, Kim C, Dougherty DA, Chapman ER, Marvin JS, Looger LL, Lester HA. Determining the pharmacokinetics of nicotinic drugs in the endoplasmic reticulum using biosensors. J Gen Physiol 2019; 151:738-757. [PMID: 30718376 PMCID: PMC6571994 DOI: 10.1085/jgp.201812201] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/05/2018] [Accepted: 01/09/2019] [Indexed: 12/27/2022] Open
Abstract
Nicotine dependence is thought to arise in part because nicotine permeates into the endoplasmic reticulum (ER), where it binds to nicotinic receptors (nAChRs) and begins an "inside-out" pathway that leads to up-regulation of nAChRs on the plasma membrane. However, the dynamics of nicotine entry into the ER are unquantified. Here, we develop a family of genetically encoded fluorescent biosensors for nicotine, termed iNicSnFRs. The iNicSnFRs are fusions between two proteins: a circularly permutated GFP and a periplasmic choline-/betaine-binding protein engineered to bind nicotine. The biosensors iNicSnFR3a and iNicSnFR3b respond to nicotine by increasing fluorescence at [nicotine] <1 µM, the concentration in the plasma and cerebrospinal fluid of a smoker. We target iNicSnFR3 biosensors either to the plasma membrane or to the ER and measure nicotine kinetics in HeLa, SH-SY5Y, N2a, and HEK293 cell lines, as well as mouse hippocampal neurons and human stem cell-derived dopaminergic neurons. In all cell types, we find that nicotine equilibrates in the ER within 10 s (possibly within 1 s) of extracellular application and leaves as rapidly after removal from the extracellular solution. The [nicotine] in the ER is within twofold of the extracellular value. We use these data to run combined pharmacokinetic and pharmacodynamic simulations of human smoking. In the ER, the inside-out pathway begins when nicotine becomes a stabilizing pharmacological chaperone for some nAChR subtypes, even at concentrations as low as ∼10 nM. Such concentrations would persist during the 12 h of a typical smoker's day, continually activating the inside-out pathway by >75%. Reducing nicotine intake by 10-fold decreases activation to ∼20%. iNicSnFR3a and iNicSnFR3b also sense the smoking cessation drug varenicline, revealing that varenicline also permeates into the ER within seconds. Our iNicSnFRs enable optical subcellular pharmacokinetics for nicotine and varenicline during an early event in the inside-out pathway.
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Affiliation(s)
- Amol V Shivange
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Philip M Borden
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Anand K Muthusamy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA
| | - Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Kallol Bera
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Huan Bao
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin, Madison, WI
| | - Ishak Bishara
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Janice Jeon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Matthew J Mulcahy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Bruce Cohen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Saidhbhe L O'Riordan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Charlene Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA
| | - Edwin R Chapman
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin, Madison, WI
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
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21
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Bavan S, Kim CH, Henderson BJ, Lester HA. Chronic Menthol Does Not Change Stoichiometry or Functional Plasma Membrane Levels of Mouse α3 β4-Containing Nicotinic Acetylcholine Receptors. Mol Pharmacol 2019; 95:398-407. [PMID: 30670481 PMCID: PMC6399576 DOI: 10.1124/mol.118.114769] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/12/2019] [Indexed: 11/22/2022] Open
Abstract
Heteromeric α3β4 nicotinic acetylcholine (ACh) receptors (nAChRs) are pentameric ligand-gated cation channels that include at least two α3 and two β4 subunits. They have functions in peripheral tissue and peripheral and central nervous systems. We examined the effects of chronic treatment with menthol, a major flavor additive in tobacco cigarettes and electronic nicotine delivery systems, on mouse α3β4 nAChRs transiently transfected into neuroblastoma-2a cells. Chronic menthol treatment at 500 nM, near the estimated menthol concentration in the brain following cigarette smoking, altered neither the [ACh]-response relationship nor Zn2+ sensitivity of ACh-evoked currents, suggesting that menthol does not change α3β4 nAChR subunit stoichiometry. Chronic menthol treatment failed to change the current density (peak current amplitude/cell capacitance) of 100 μM ACh-evoked currents. Chronic menthol treatment accelerated desensitization of 100 and 200 μM ACh-evoked currents. Chronic nicotine treatment (250 μM) decreased ACh-induced currents, and we found no additional effect of including chronic menthol. These data contrast with previously reported, marked effects of chronic menthol on β2* nAChRs studied in the same expression system. Mechanistically, the data support the emerging interpretation that both chronic menthol and chronic nicotine act on nAChRs in the early exocytotic pathway, and that this pathway does not present a rate-limiting step to the export of α3β4 nAChRs; these nAChRs include endoplasmic reticulum (ER) export motifs but not ER retention motifs. Previous reports show that smoking mentholated cigarettes enhances tobacco addiction; but our results show that this effect is unlikely to arise via menthol actions on α3β4 nAChRs.
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Affiliation(s)
- Selvan Bavan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
| | - Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
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22
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Zhou C, Gu W, Wu H, Yan X, Deshpande P, Xiao C, Lester HA. Bidirectional dopamine modulation of excitatory and inhibitory synaptic inputs to subthalamic neuron subsets containing α4β2 or α7 nAChRs. Neuropharmacology 2019; 148:220-228. [PMID: 30660626 DOI: 10.1016/j.neuropharm.2019.01.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 01/10/2019] [Accepted: 01/14/2019] [Indexed: 02/05/2023]
Abstract
The subthalamic nucleus (STN) possesses microcircuits distinguished by subtypes of nicotinic acetylcholine receptors (nAChRs). Although dysfunction of the STN is well-known in Parkinson's disease, there is still little information about whether dopamine differentially modulates excitatory and inhibitory synaptic inputs to STN neurons expressing different nAChR subtypes. To address this issue, we performed brain slice patch-clamp recordings on STN neurons, while we pharmacologically manipulated dopaminergic inputs. In STN neuron subsets containing either α4β2 or α7 nAChRs, D1 and D2 receptors respectively enhanced and inhibited spontaneous inhibitory and excitatory postsynaptic currents (sIPSCs and sEPSCs) and firing rates. The elevation of dopamine levels resulted in diverse regulations of synaptic transmission in these two neuron subsets, and interestingly, the dopamine regulation of sIPSCs significantly correlated with that of sEPSCs. Surprisingly, depletion of dopamine either by reserpine treatment or by unilateral 6-OHDA lesion of nigrostriatal dopaminergic neurons did not alter synaptic inputs to STN neurons, but STN neurons in the 6-OHDA-lesioned side exhibited hyperactivity. In summary, dopamine regulated both GABAergic and glutamatergic synaptic inputs to STN neuron subsets containing either α4β2 or α7 nAChRs, forming a balancing machinery to control neuronal activity. In parkinsonian mice, postsynaptic mechanisms may exist and contribute to the hyperactivity of STN neurons.
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Affiliation(s)
- Chunyi Zhou
- Jiangsu Province Key Laboratory in Anesthesiology, School of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China
| | - Weixin Gu
- Jiangsu Province Key Laboratory in Anesthesiology, School of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China
| | - Haichuan Wu
- Jiangsu Province Key Laboratory in Anesthesiology, School of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China
| | - Xiang Yan
- Jiangsu Province Key Laboratory in Anesthesiology, School of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China
| | - Purnima Deshpande
- Division of Biology, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Cheng Xiao
- Jiangsu Province Key Laboratory in Anesthesiology, School of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China; Division of Biology, California Institute of Technology, Pasadena, CA, 91125, USA.
| | - Henry A Lester
- Division of Biology, California Institute of Technology, Pasadena, CA, 91125, USA.
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23
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Henderson BJ, Grant S, Chu BW, Shahoei R, Huard SM, Saladi SSM, Tajkhorshid E, Dougherty DA, Lester HA. Menthol Stereoisomers Exhibit Different Effects on α4β2 nAChR Upregulation and Dopamine Neuron Spontaneous Firing. eNeuro 2018; 5:ENEURO.0465-18.2018. [PMID: 30627659 PMCID: PMC6325563 DOI: 10.1523/eneuro.0465-18.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 12/08/2018] [Indexed: 11/21/2022] Open
Abstract
Menthol contributes to poor cessation rates among smokers, in part because menthol enhances nicotine reward and reinforcement. Mentholated tobacco products contain (-)-menthol and (+)-menthol, in varying proportions. We examined these two menthol stereoisomers for their ability to upregulate α4β2 nAChRs and to alter dopamine neuron firing frequency using long-term, low-dose (≤500 nm) exposure that is pharmacologically relevant to smoking. We found that (-)-menthol upregulates α4β2 nAChRs while (+)-menthol does not. We also found that (-)-menthol decreases dopamine neuron baseline firing and dopamine neuron excitability, while (+)-menthol exhibits no effect. We then examined both stereoisomers for their ability to inhibit α4β2 nAChR function at higher concentrations (>10 µm) using the Xenopus oocyte expression system. To probe for the potential binding site of menthol, we conducted flooding simulations and site-directed mutagenesis. We found that menthol likely binds to the 9´ position on the TM2 (transmembrane M2) helix. We found that menthol inhibition is dependent on the end-to-end distance of the side chain at the 9´ residue. Additionally, we have found that (-)-menthol is only modestly (∼25%) more potent than (+)-menthol at inhibiting wild-type α4β2 nAChRs and a series of L9´ mutant nAChRs. These data reveal that menthol exhibits a stereoselective effect on nAChRs and that the stereochemical effect is much greater for long-term, submicromolar exposure in mice than for acute, higher-level exposure. We hypothesize that of the two menthol stereoisomers, only (-)-menthol plays a role in enhancing nicotine reward through nAChRs on dopamine neurons.
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Affiliation(s)
- Brandon J. Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia 25703
| | - Stephen Grant
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| | - Betty W. Chu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Rezvan Shahoei
- Department of Physics, National Institutes of Health Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Stephanie M. Huard
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Shyam S. M. Saladi
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| | - Emad Tajkhorshid
- Department of Biochemistry, National Institutes of Health Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Dennis A. Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| | - Henry A. Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
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24
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Nichols AL, Noridomi K, Hughes CR, Jalali-Yazdi F, Eaton JB, Lai LH, Advani G, Lukas RJ, Lester HA, Chen L, Roberts RW. α1-FANGs: Protein Ligands Selective for the α-Bungarotoxin Site of the α1-Nicotinic Acetylcholine Receptor. ACS Chem Biol 2018; 13:2568-2576. [PMID: 30059207 DOI: 10.1021/acschembio.8b00513] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels that play a central role in neuronal and neuromuscular signal transduction. Here, we have developed FANG ligands, fibronectin antibody-mimetic nicotinic acetylcholine receptor-generated ligands, using mRNA display. We generated a 1 trillion-member primary e10FnIII library to target a stabilized α1 nicotinic subunit (α211). This library yielded 270000 independent potential protein binding ligands. The lead sequence, α1-FANG1, represented 25% of all library sequences, showed the highest-affinity binding, and competed with α-bungarotoxin (α-Btx). To improve this clone, a new library based on α1-FANG1 was subjected to heat, protease, binding, off-rate selective pressures, and point mutations. This resulted in α1-FANG2 and α1-FANG3. These proteins bind α211 with KD values of 3.5 nM and 670 pM, respectively, compete with α-Btx, and show improved subunit specificity. α1-FANG3 is thermostable ( Tm = 62 °C) with a 6 kcal/mol improvement in folding free energy compared with that of the parent α1-FANG1. α1-FANG3 competes directly with the α-Btx binding site of intact neuromuscular heteropentamers [(α1)2β1γδ] in mammalian culture-derived cellular membranes and in Xenopus laevis oocytes expressing these nAChRs. This work demonstrates that mRNA display against a monomeric ecto-domain of a pentamer has the capability to select ligands that bind that subunit in both a monomeric and a pentameric context. Overall, our work provides a route to creating a new family of stable, well-behaved proteins that specifically target this important receptor family.
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Affiliation(s)
- Aaron L. Nichols
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United States
| | - Kaori Noridomi
- Molecular and Computational Biology, Department of Biology, University of Southern California, Los Angeles, California 90089-0371, United States
| | - Christopher R. Hughes
- Mork Family Department of Chemical Engineering and Material Sciences, University of Southern California, Los Angeles, California 90089-1211, United States
| | - Farzad Jalali-Yazdi
- Mork Family Department of Chemical Engineering and Material Sciences, University of Southern California, Los Angeles, California 90089-1211, United States
| | - J. Brek Eaton
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, University of Arizona, Phoenix, Arizona 85013-4409, United States
| | - Lan Huong Lai
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United States
| | - Gaurav Advani
- Mork Family Department of Chemical Engineering and Material Sciences, University of Southern California, Los Angeles, California 90089-1211, United States
| | - Ronald J. Lukas
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, University of Arizona, Phoenix, Arizona 85013-4409, United States
| | - Henry A. Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125-0001, United States
| | - Lin Chen
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United States
- Molecular and Computational Biology, Department of Biology, University of Southern California, Los Angeles, California 90089-0371, United States
- Norris Cancer Center, University of Southern California, Los Angeles, California 90033, United States
| | - Richard W. Roberts
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United States
- Molecular and Computational Biology, Department of Biology, University of Southern California, Los Angeles, California 90089-0371, United States
- Mork Family Department of Chemical Engineering and Material Sciences, University of Southern California, Los Angeles, California 90089-1211, United States
- Norris Cancer Center, University of Southern California, Los Angeles, California 90033, United States
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California 90089-1111, United States
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25
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Subramaniam SR, Magen I, Bove N, Zhu C, Lemesre V, Dutta G, Elias CJ, Lester HA, Chesselet MF. Chronic nicotine improves cognitive and social impairment in mice overexpressing wild type α-synuclein. Neurobiol Dis 2018; 117:170-180. [PMID: 29859873 PMCID: PMC6051902 DOI: 10.1016/j.nbd.2018.05.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/07/2018] [Accepted: 05/29/2018] [Indexed: 11/23/2022] Open
Abstract
In addition to dopaminergic and motor deficits, patients with Parkinson's disease (PD) suffer from non-motor symptoms, including early cognitive and social impairment, that do not respond well to dopaminergic therapy. Cholinergic deficits may contribute to these problems, but cholinesterase inhibitors have limited efficacy. Mice over-expressing α-synuclein, a protein critically associated with PD, show deficits in cognitive and social interaction tests, as well as a decrease in cortical acetylcholine. We have evaluated the effects of chronic administration of nicotine in mice over-expressing wild type human α-synuclein under the Thy1-promoter (Thy1-aSyn mice). Nicotine was administered subcutaneously by osmotic minipump for 6 months from 2 to 8 months of age at 0.4 mg/kg/h and 2.0 mg/kg/h. The higher dose was toxic in the Thy1-aSyn mice, but the low dose was well tolerated and both doses ameliorated cognitive impairment in Y-maze performance after 5 months of treatment. In a separate cohort of Thy1-aSyn mice, nicotine was administered at the lower dose for one month beginning at 5 months of age. This treatment partially eliminated the cognitive deficit in novel object recognition and social impairment. In contrast, chronic nicotine did not improve motor deficits after 2, 4 or 6 months of treatment, nor modified α-synuclein aggregation, tyrosine hydroxylase immunostaining, synaptic and dendritic markers, or microglial activation in Thy1-aSyn mice. These results suggest that cognitive and social impairment in synucleinopathies like PD may result from deficits in cholinergic neurotransmission and may benefit from chronic administration of nicotinic agonists.
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Affiliation(s)
- Sudhakar R Subramaniam
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
| | - Iddo Magen
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Nicholas Bove
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Chunni Zhu
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Vincent Lemesre
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Garima Dutta
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Chris Jean Elias
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Marie-Francoise Chesselet
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
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26
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Banala S, Arvin MC, Bannon NM, Jin XT, Macklin JJ, Wang Y, Peng C, Zhao G, Marshall JJ, Gee KR, Wokosin DL, Kim VJ, McIntosh JM, Contractor A, Lester HA, Kozorovitskiy Y, Drenan RM, Lavis LD. Photoactivatable drugs for nicotinic optopharmacology. Nat Methods 2018; 15:347-350. [PMID: 29578537 PMCID: PMC5923430 DOI: 10.1038/nmeth.4637] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 02/26/2018] [Indexed: 11/10/2022]
Abstract
Photoactivatable pharmacological agents have revolutionized neuroscience, but the palette of available compounds is limited. We describe a general method for caging tertiary amines by using a stable quaternary ammonium linkage that elicits a red shift in the activation wavelength. We prepared a photoactivatable nicotine (PA-Nic), uncageable via one- or two-photon excitation, that is useful to study nicotinic acetylcholine receptors (nAChRs) in different experimental preparations and spatiotemporal scales.
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Affiliation(s)
- Sambashiva Banala
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn,
Virginia, USA
| | - Matthew C. Arvin
- Department of Pharmacology, Northwestern University Feinberg School
of Medicine, Chicago, Illinois, USA
| | - Nicolas M. Bannon
- Department of Neurobiology, Weinberg School of Arts and Sciences,
Northwestern University, Evanston, Illinois, USA
| | - Xiao-Tao Jin
- Department of Pharmacology, Northwestern University Feinberg School
of Medicine, Chicago, Illinois, USA
| | - John J. Macklin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn,
Virginia, USA
| | - Yong Wang
- Department of Pharmacology, Northwestern University Feinberg School
of Medicine, Chicago, Illinois, USA
| | - Can Peng
- Department of Pharmacology, Northwestern University Feinberg School
of Medicine, Chicago, Illinois, USA
| | - Guiqing Zhao
- Department of Pharmacology, Northwestern University Feinberg School
of Medicine, Chicago, Illinois, USA
| | - John J. Marshall
- Department of Physiology, Northwestern University Feinberg School of
Medicine, Chicago, Illinois, USA
| | - Kyle R. Gee
- Molecular Probes, ThermoFisher, Eugene, Oregon, USA
| | - David L. Wokosin
- Department of Physiology, Northwestern University Feinberg School of
Medicine, Chicago, Illinois, USA
| | - Veronica J. Kim
- Department of Pharmacology, Northwestern University Feinberg School
of Medicine, Chicago, Illinois, USA
| | - J. Michael McIntosh
- George E. Wahlen Veterans Affairs Medical Center and Departments of
Psychiatry and Biology, University of Utah, Salt Lake City, Utah, USA
| | - Anis Contractor
- Department of Physiology, Northwestern University Feinberg School of
Medicine, Chicago, Illinois, USA
- Department of Neurobiology, Weinberg School of Arts and Sciences,
Northwestern University, Evanston, Illinois, USA
| | - Henry A. Lester
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn,
Virginia, USA
- Division of Biology and Biological Engineering, California Institute
of Technology, Pasadena, California, USA
| | - Yevgenia Kozorovitskiy
- Department of Neurobiology, Weinberg School of Arts and Sciences,
Northwestern University, Evanston, Illinois, USA
| | - Ryan M. Drenan
- Department of Pharmacology, Northwestern University Feinberg School
of Medicine, Chicago, Illinois, USA
| | - Luke D. Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn,
Virginia, USA
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27
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Bavan S, Patowary S, Kim CH, Henderson BJ, Lester HA. Effects of Chronic Menthol at Alpha3Beta4 (α3β4)-Containing Nicotinic Acetylcholine Receptors. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.1691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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28
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Muthusamy AK, Shivange AV, Nichols AL, Kamajaya A, Jeon J, Borden PM, Marvin JS, Unger EK, Bao H, Chapman ER, Tian L, Looger LL, Lester HA. Microscopy Using Fluorescent Drug Biosensors for “Inside-Out Pharmacology”. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.1990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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29
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Henderson BJ, Wall TR, Henley BM, Kim CH, McKinney S, Lester HA. Menthol Enhances Nicotine Reward-Related Behavior by Potentiating Nicotine-Induced Changes in nAChR Function, nAChR Upregulation, and DA Neuron Excitability. Neuropsychopharmacology 2017; 42:2285-2291. [PMID: 28401925 PMCID: PMC5645749 DOI: 10.1038/npp.2017.72] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/28/2017] [Accepted: 04/01/2017] [Indexed: 12/17/2022]
Abstract
Understanding why the quit rate among smokers of menthol cigarettes is lower than non-menthol smokers requires identifying the neurons that are altered by nicotine, menthol, and acetylcholine. Dopaminergic (DA) neurons in the ventral tegmental area (VTA) mediate the positive reinforcing effects of nicotine. Using mouse models, we show that menthol enhances nicotine-induced changes in nicotinic acetylcholine receptors (nAChRs) expressed on midbrain DA neurons. Menthol plus nicotine upregulates nAChR number and function on midbrain DA neurons more than nicotine alone. Menthol also enhances nicotine-induced changes in DA neuron excitability. In a conditioned place preference (CPP) assay, we observed that menthol plus nicotine produces greater reward-related behavior than nicotine alone. Our results connect changes in midbrain DA neurons to menthol-induced enhancements of nicotine reward-related behavior and may help explain how smokers of menthol cigarettes exhibit reduced cessation rates.
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Affiliation(s)
- Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA,Department of Biomedical Sciences, Marshall University, Joan C Edwards School of Medicine, Huntington, WV, USA
| | - Teagan R Wall
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Beverley M Henley
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Sheri McKinney
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA,Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard MC 156-29, Pasadena, CA 91125-2900, USA, Tel: +626 395 4946, Fax: +626 564 8709, E-mail:
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Tarren JR, Lester HA, Belmer A, Bartlett SE. Acute Ethanol Administration Upregulates Synaptic α4-Subunit of Neuronal Nicotinic Acetylcholine Receptors within the Nucleus Accumbens and Amygdala. Front Mol Neurosci 2017; 10:338. [PMID: 29114204 PMCID: PMC5660714 DOI: 10.3389/fnmol.2017.00338] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/05/2017] [Indexed: 12/26/2022] Open
Abstract
Alcohol and nicotine are two of the most frequently abused drugs, with their comorbidity well described. Previous data show that chronic exposure to nicotine upregulates high-affinity nicotinic acetylcholine receptors (nAChRs) in several brain areas. Effects of ethanol on specific brain nAChR subtypes within the mesolimbic dopaminergic (DA) pathway may be a key element in the comorbidity of ethanol and nicotine. However, it is unknown how alcohol affects the abundance of these receptor proteins. In the present study, we measured the effect of acute binge ethanol on nAChR α4 subunit levels in the prefrontal cortex (PFC), nucleus accumbens (NAc), ventral tegmental area (VTA), and amygdala (Amg) by western blot analysis using a knock-in mouse line, generated with a normally functioning α4 nAChR subunit tagged with yellow fluorescent protein (YFP). We observed a robust increase in α4-YFP subunit levels in the NAc and the Amg following acute ethanol, with no changes in the PFC and VTA. To further investigate whether this upregulation was mediated by increased local mRNA transcription, we quantified mRNA levels of the Chrna4 gene using qRT-PCR. We found no effect of ethanol on α4 mRNA expression, suggesting that the upregulation of α4 protein rather occurs post-translationally. The quantitative counting of YFP immunoreactive puncta further revealed that α4-YFP protein is upregulated in presynaptic boutons of the dopaminergic axons projecting to the shell and the core regions of the NAc as well as to the basolateral amygdala (BLA), but not to the central or lateral Amg. Together, our results demonstrate that a single exposure to binge ethanol upregulates level of synaptic α4∗ nAChRs in dopaminergic inputs to the NAc and BLA. This upregulation could be linked to the functional dysregulation of dopaminergic signalling observed during the development of alcohol dependence.
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Affiliation(s)
- Josephine R Tarren
- Translational Research Institute, Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Arnauld Belmer
- Translational Research Institute, Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Selena E Bartlett
- Translational Research Institute, Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
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Wall TR, Henderson BJ, Voren G, Wageman CR, Deshpande P, Cohen BN, Grady SR, Marks MJ, Yohannes D, Kenny PJ, Bencherif M, Lester HA. TC299423, a Novel Agonist for Nicotinic Acetylcholine Receptors. Front Pharmacol 2017; 8:641. [PMID: 29033834 PMCID: PMC5626944 DOI: 10.3389/fphar.2017.00641] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Accepted: 08/29/2017] [Indexed: 01/11/2023] Open
Abstract
(E)-5-(Pyrimidin-5-yl)-1,2,3,4,7,8-hexahydroazocine (TC299423) is a novel agonist for nicotinic acetylcholine receptors (nAChRs). We examined its efficacy, affinity, and potency for α6β2∗ (α6β2-containing), α4β2∗, and α3β4∗ nAChRs, using [125I]-epibatidine binding, whole-cell patch-clamp recordings, synaptosomal 86Rb+ efflux, [3H]-dopamine release, and [3H]-acetylcholine release. TC299423 displayed an EC50 of 30–60 nM for α6β2∗ nAChRs in patch-clamp recordings and [3H]-dopamine release assays. Its potency for α6β2∗ in these assays was 2.5-fold greater than that for α4β2∗, and much greater than that for α3β4∗-mediated [3H]-acetylcholine release. We observed no major off-target binding on 70 diverse molecular targets. TC299423 was bioavailable after intraperitoneal or oral administration. Locomotor assays, measured with gain-of-function, mutant α6 (α6L9′S) nAChR mice, show that TC299423 elicits α6β2∗ nAChR-mediated responses at low doses. Conditioned place preference assays show that low-dose TC299423 also produces significant reward in α6L9′S mice, and modest reward in WT mice, through a mechanism that probably involves α6(non-α4)β2∗ nAChRs. However, TC299423 did not suppress nicotine self-administration in rats, indicating that it did not block nicotine reinforcement in the dosage range that was tested. In a hot-plate test, TC299423 evoked antinociceptive responses in mice similar to those of nicotine. TC299423 and nicotine similarly inhibited mouse marble burying as a measure of anxiolytic effects. Taken together, our data suggest that TC299423 will be a useful small-molecule agonist for future in vitro and in vivo studies of nAChR function and physiology.
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Affiliation(s)
- Teagan R Wall
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Brandon J Henderson
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, United States
| | - George Voren
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Charles R Wageman
- Institute of Behavioral Genetics, University of Colorado, Boulder, Boulder, CO, United States
| | - Purnima Deshpande
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Bruce N Cohen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Sharon R Grady
- Institute of Behavioral Genetics, University of Colorado, Boulder, Boulder, CO, United States
| | - Michael J Marks
- Institute of Behavioral Genetics, University of Colorado, Boulder, Boulder, CO, United States.,Department of Psychology and Neuroscience, University of Colorado, Boulder, Boulder, CO, United States
| | | | - Paul J Kenny
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | | | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
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Mulcahy MJ, Lester HA. Granulocytes as models for human protein marker identification following nicotine exposure. J Neurochem 2017; 142 Suppl 2:151-161. [PMID: 28791704 PMCID: PMC6057152 DOI: 10.1111/jnc.14010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 12/23/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric cation channels expressed in the mammalian CNS, in the peripheral nervous system, and in skeletal muscle. Neuronal-type nAChRs are also found in several non-neuronal cell types, including leukocytes. Granulocytes are a subtype of leukocytes that include basophils, eosinophils, and neutrophils. Granulocytes, also known as polymorphonuclear leukocytes, are characterized by their ability to produce, store, and release compounds from intracellular granules. Granulocytes are the most abundant type of leukocyte circulating in the peripheral blood. Granulocyte abundance, nAChR expression, and nAChR upregulation following chronic nicotine administration makes granulocytes interesting models for identifying protein markers of nicotine exposure. Nicotinic receptor subunits and several non-nAChR proteins have been identified as protein markers of granulocyte nicotine exposure. We review methods to isolate granulocytes from human tissue, summarize present data about the expression of nAChRs in the three granulocyte cell types (basophils, eosinophils, and neutrophils), describe current knowledge of the effects of nicotine exposure on human granulocyte protein expression, and highlight areas of interest for future investigation. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.
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Affiliation(s)
- Matthew J Mulcahy
- Department of Biology, California Institute of Technology, Pasadena, California, USA
| | - Henry A Lester
- Department of Biology, California Institute of Technology, Pasadena, California, USA
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Abstract
Designing subtype-selective agonists for neuronal nicotinic acetylcholine receptors is a challenging and significant goal aided by intricate knowledge of each subtype's binding patterns. We previously reported that in α6β2 receptors, acetylcholine makes a functional cation-π interaction with Trp149, but nicotine and TC299423 do not, suggesting a distinctive binding site. This work explores hydrogen binding at the backbone carbonyl associated with α6β2 Trp149. Substituting residue i + 1, Thr150, with its α-hydroxy analogue (Tah) attenuates the carbonyl's hydrogen bond accepting ability. At α6(T150Tah)β2, nicotine shows a 24-fold loss of function, TC299423 shows a modest loss, and acetylcholine shows no effect. Nicotine was further analyzed via a double-mutant cycle analysis utilizing N'-methylnicotinium, which indicated a hydrogen bond in α6β2 with a ΔΔG of 2.6 kcal/mol. Thus, even though nicotine does not make the conserved cation-π interaction with Trp149, it still makes a functional hydrogen bond to its associated backbone carbonyl.
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Affiliation(s)
- Michael R Post
- Division of Chemistry and Chemical Engineering and ‡Division of Biology and Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
| | - Henry A Lester
- Division of Chemistry and Chemical Engineering and ‡Division of Biology and Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering and ‡Division of Biology and Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
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Henley BM, Cohen BN, Kim CH, Gold HD, Srinivasan R, McKinney S, Deshpande P, Lester HA. Reliable Identification of Living Dopaminergic Neurons in Midbrain Cultures Using RNA Sequencing and TH-promoter-driven eGFP Expression. J Vis Exp 2017. [PMID: 28287593 DOI: 10.3791/54981] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In Parkinson's Disease (PD) there is widespread neuronal loss throughout the brain with pronounced degeneration of dopaminergic neurons in the SNc, leading to bradykinesia, rigidity, and tremor. The identification of living dopaminergic neurons in primary Ventral Mesencephalic (VM) cultures using a fluorescent marker provides an alternative way to study the selective vulnerability of these neurons without relying on the immunostaining of fixed cells. Here, we isolate, dissociate, and culture mouse VM neurons for 3 weeks. We then identify dopaminergic neurons in the cultures using eGFP fluorescence (driven by a Tyrosine Hydroxylase (TH) promoter). Individual neurons are harvested into microcentrifuge tubes using glass micropipettes. Next, we lyse the harvested cells, and conduct cDNA synthesis and transposon-mediated "tagmentation" to produce single cell RNA-Seq libraries1,2,3,4,5. After passing a quality-control check, single-cell libraries are sequenced and subsequent analysis is carried out to measure gene expression. We report transcriptome results for individual dopaminergic and GABAergic neurons isolated from midbrain cultures. We report that 100% of the live TH-eGFP cells that were harvested and sequenced were dopaminergic neurons. These techniques will have widespread applications in neuroscience and molecular biology.
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Affiliation(s)
- Beverley M Henley
- Division of Biology and Biological Engineering, California Institute of Technology (Caltech);
| | - Bruce N Cohen
- Division of Biology and Biological Engineering, California Institute of Technology (Caltech)
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of Technology (Caltech)
| | - Heather D Gold
- Division of Biology and Biological Engineering, California Institute of Technology (Caltech)
| | - Rahul Srinivasan
- Division of Biology and Biological Engineering, California Institute of Technology (Caltech)
| | - Sheri McKinney
- Division of Biology and Biological Engineering, California Institute of Technology (Caltech)
| | - Purnima Deshpande
- Division of Biology and Biological Engineering, California Institute of Technology (Caltech)
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology (Caltech)
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Kim J, Henley BM, Kim CH, Lester HA, Yang C. Incubator embedded cell culture imaging system (EmSight) based on Fourier ptychographic microscopy. Biomed Opt Express 2016; 7:3097-110. [PMID: 27570701 PMCID: PMC4986817 DOI: 10.1364/boe.7.003097] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Revised: 07/07/2016] [Accepted: 07/17/2016] [Indexed: 05/20/2023]
Abstract
Multi-day tracking of cells in culture systems can provide valuable information in bioscience experiments. We report the development of a cell culture imaging system, named EmSight, which incorporates multiple compact Fourier ptychographic microscopes with a standard multiwell imaging plate. The system is housed in an incubator and presently incorporates six microscopes. By using the same low magnification objective lenses as the objective and the tube lens, the EmSight is configured as a 1:1 imaging system that, providing large field-of-view (FOV) imaging onto a low-cost CMOS imaging sensor. The EmSight improves the image resolution by capturing a series of images of the sample at varying illumination angles; the instrument reconstructs a higher-resolution image by using the iterative Fourier ptychographic algorithm. In addition to providing high-resolution brightfield and phase imaging, the EmSight is also capable of fluorescence imaging at the native resolution of the objectives. We characterized the system using a phase Siemens star target, and show four-fold improved coherent resolution (synthetic NA of 0.42) and a depth of field of 0.2 mm. To conduct live, long-term dopaminergic neuron imaging, we cultured ventral midbrain from mice driving eGFP from the tyrosine hydroxylase promoter. The EmSight system tracks movements of dopaminergic neurons over a 21 day period.
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Affiliation(s)
- Jinho Kim
- Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Beverley M. Henley
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Charlene H. Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Henry A. Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Changhuei Yang
- Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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Nichols WA, Henderson BJ, Marotta CB, Yu CY, Richards C, Dougherty DA, Lester HA, Cohen BN. Mutation Linked to Autosomal Dominant Nocturnal Frontal Lobe Epilepsy Reduces Low-Sensitivity α4β2, and Increases α5α4β2, Nicotinic Receptor Surface Expression. PLoS One 2016; 11:e0158032. [PMID: 27336596 PMCID: PMC4918917 DOI: 10.1371/journal.pone.0158032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 06/09/2016] [Indexed: 11/24/2022] Open
Abstract
A number of mutations in α4β2-containing (α4β2*) nicotinic acetylcholine (ACh) receptors (nAChRs) are linked to autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), including one in the β2 subunit called β2V287L. Two α4β2* subtypes with different subunit stoichiometries and ACh sensitivities co-exist in the brain, a high-sensitivity subtype with (α4)2(β2)3 subunit stoichiometry and a low-sensitivity subtype with (α4)3(β2)2 stoichiometry. The α5 nicotinic subunit also co-assembles with α4β2 to form a high-sensitivity α5α4β2 nAChR. Previous studies suggest that the β2V287L mutation suppresses low-sensitivity α4β2* nAChR expression in a knock-in mouse model and also that α5 co-expression improves the surface expression of ADNFLE mutant nAChRs in a cell line. To test these hypotheses further, we expressed mutant and wild-type (WT) nAChRs in oocytes and mammalian cell lines, and measured the effects of the β2V287L mutation on surface receptor expression and the ACh response using electrophysiology, a voltage-sensitive fluorescent dye, and superecliptic pHluorin (SEP). The β2V287L mutation reduced the EC50 values of high- and low-sensitivity α4β2 nAChRs expressed in Xenopus oocytes for ACh by a similar factor and suppressed low-sensitivity α4β2 expression. In contrast, it did not affect the EC50 of α5α4β2 nAChRs for ACh. Measurements of the ACh responses of WT and mutant nAChRs expressed in mammalian cell lines using a voltage-sensitive fluorescent dye and whole-cell patch-clamping confirm the oocyte data. They also show that, despite reducing the maximum response, β2V287L increased the α4β2 response to a sub-saturating ACh concentration (1 μM). Finally, imaging SEP-tagged α5, α4, β2, and β2V287L subunits showed that β2V287L reduced total α4β2 nAChR surface expression, increased the number of β2 subunits per α4β2 receptor, and increased surface α5α4β2 nAChR expression. Thus, the β2V287L mutation alters the subunit composition and sensitivity of α4β2 nAChRs, and increases α5α4β2 surface expression.
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Affiliation(s)
- Weston A Nichols
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Brandon J Henderson
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Christopher B Marotta
- Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Caroline Y Yu
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Chris Richards
- Department of Chemistry, University of Kentucky, Lexington, KY, United States of America
| | - Dennis A Dougherty
- Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Henry A Lester
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Bruce N Cohen
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
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Patowary S, Mackey ED, McKinney SL, Deshpande P, Henderson BJ, Biener G, Raicu V, Lester HA. Effects of Menthol on α3β4∗ Nicotinic Receptors. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.3221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Srinivasan R, Henley BM, Henderson BJ, Indersmitten T, Cohen BN, Kim CH, McKinney S, Deshpande P, Xiao C, Lester HA. Smoking-Relevant Nicotine Concentration Attenuates the Unfolded Protein Response in Dopaminergic Neurons. J Neurosci 2016; 36:65-79. [PMID: 26740650 PMCID: PMC4701966 DOI: 10.1523/jneurosci.2126-15.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 11/09/2015] [Accepted: 11/13/2015] [Indexed: 01/01/2023] Open
Abstract
Retrospective epidemiological studies show an inverse correlation between susceptibility to Parkinson's disease and a person's history of tobacco use. Animal model studies suggest nicotine as a neuroprotective agent and nicotinic acetylcholine (ACh) receptors (nAChRs) as targets for neuroprotection, but the underlying neuroprotective mechanism(s) are unknown. We cultured mouse ventral midbrain neurons for 3 weeks. Ten to 20% of neurons were dopaminergic (DA), revealed by tyrosine hydroxylase (TH) immunoreactivity. We evoked mild endoplasmic reticulum (ER) stress with tunicamycin (Tu), producing modest increases in the level of nuclear ATF6, phosphorylated eukaryotic initiation factor 2α, nuclear XBP1, and the downstream proapoptotic effector nuclear C/EBP homologous protein. We incubated cultures for 2 weeks with 200 nm nicotine, the approximate steady-state concentration between cigarette smoking or vaping, or during nicotine patch use. Nicotine incubation suppressed Tu-induced ER stress and the unfolded protein response (UPR). Study of mice with fluorescent nAChR subunits showed that the cultured TH+ neurons displayed α4, α6, and β3 nAChR subunit expression and ACh-evoked currents. Gene expression profile in cultures from TH-eGFP mice showed that the TH+ neurons also express several other genes associated with DA release. Nicotine also upregulated ACh-induced currents in DA neurons by ∼2.5-fold. Thus, nicotine, at a concentration too low to activate an appreciable fraction of plasma membrane nAChRs, induces two sequelae of pharmacological chaperoning in the ER: UPR suppression and nAChR upregulation. Therefore, one mechanism of neuroprotection by nicotine is pharmacological chaperoning, leading to UPR suppression. Measuring this pathway may help in assessing neuroprotection. SIGNIFICANCE STATEMENT Parkinson's disease (PD) cannot yet be cured or prevented. However, many retrospective epidemiological studies reveal that PD is diagnosed less frequently in tobacco users. Existing programs attempting to develop nicotinic drugs that might exert this apparent neuroprotective effect are asking whether agonists, antagonists, partial agonists, or channel blockers show the most promise. The underlying logic resembles the previous development of varenicline for smoking cessation. We studied whether, and how, nicotine produces neuroprotective effects in cultured dopaminergic neurons, an experimentally tractable, mechanistically revealing neuronal system. We show that nicotine, operating via nicotinic receptors, does protect these neurons against endoplasmic reticulum stress. However, the mechanism is probably "inside-out": pharmacological chaperoning in the endoplasmic reticulum. This cellular-level insight could help to guide neuroprotective strategies.
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Affiliation(s)
- Rahul Srinivasan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Beverley M Henley
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Tim Indersmitten
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Bruce N Cohen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Sheri McKinney
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Purnima Deshpande
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Cheng Xiao
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
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Sinkus ML, Graw S, Freedman R, Ross RG, Lester HA, Leonard S. The human CHRNA7 and CHRFAM7A genes: A review of the genetics, regulation, and function. Neuropharmacology 2015; 96:274-88. [PMID: 25701707 PMCID: PMC4486515 DOI: 10.1016/j.neuropharm.2015.02.006] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 02/04/2015] [Accepted: 02/06/2015] [Indexed: 01/16/2023]
Abstract
The human α7 neuronal nicotinic acetylcholine receptor gene (CHRNA7) is ubiquitously expressed in both the central nervous system and in the periphery. CHRNA7 is genetically linked to multiple disorders with cognitive deficits, including schizophrenia, bipolar disorder, ADHD, epilepsy, Alzheimer's disease, and Rett syndrome. The regulation of CHRNA7 is complex; more than a dozen mechanisms are known, one of which is a partial duplication of the parent gene. Exons 5-10 of CHRNA7 on chromosome 15 were duplicated and inserted 1.6 Mb upstream of CHRNA7, interrupting an earlier partial duplication of two other genes. The chimeric CHRFAM7A gene product, dupα7, assembles with α7 subunits, resulting in a dominant negative regulation of function. The duplication is human specific, occurring neither in primates nor in rodents. The duplicated α7 sequence in exons 5-10 of CHRFAM7A is almost identical to CHRNA7, and thus is not completely queried in high throughput genetic studies (GWAS). Further, pre-clinical animal models of the α7nAChR utilized in drug development research do not have CHRFAM7A (dupα7) and cannot fully model human drug responses. The wide expression of CHRNA7, its multiple functions and modes of regulation present challenges for study of this gene in disease. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Affiliation(s)
- Melissa L Sinkus
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
| | - Sharon Graw
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
| | - Robert Freedman
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA; Veterans Affairs Medical Research Center, Denver, CO 80262, USA.
| | - Randal G Ross
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
| | - Henry A Lester
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Sherry Leonard
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA; Veterans Affairs Medical Research Center, Denver, CO 80262, USA.
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Marotta CB, Lester HA, Dougherty DA. An Unaltered Orthosteric Site and a Network of Long-Range Allosteric Interactions for PNU-120596 in α7 Nicotinic Acetylcholine Receptors. ACTA ACUST UNITED AC 2015. [PMID: 26211363 DOI: 10.1016/j.chembiol.2015.06.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are vital to neuronal signaling, are implicated in important processes such as learning and memory, and are therapeutic targets for neural diseases. The α7 nAChR has been implicated in Alzheimer's disease and schizophrenia, and allosteric modulators have become one focus of drug development efforts. We investigate the mode of action of the α7-selective positive allosteric modulator, PNU-120596, and show that the higher potency of acetylcholine in the presence of PNU-120596 is not due to an altered agonist binding site. In addition, we propose several residues in the gating interface and transmembrane region that are functionally important to transduction of allosteric properties, and link PNU-120596, the acetylcholine binding region, and the receptor gate. These results suggest global protein stabilization from a communication network through several key residues that alter the gating equilibrium of the receptor while leaving the agonist binding properties unperturbed.
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Affiliation(s)
- Christopher B Marotta
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
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Wieskopf JS, Mathur J, Limapichat W, Post MR, Al-Qazzaz M, Sorge RE, Martin LJ, Zaykin DV, Smith SB, Freitas K, Austin JS, Dai F, Zhang J, Marcovitz J, Tuttle AH, Slepian PM, Clarke S, Drenan RM, Janes J, Al Sharari S, Segall SK, Aasvang EK, Lai W, Bittner R, Richards CI, Slade GD, Kehlet H, Walker J, Maskos U, Changeux JP, Devor M, Maixner W, Diatchenko L, Belfer I, Dougherty DA, Su AI, Lummis SCR, Imad Damaj M, Lester HA, Patapoutian A, Mogil JS. The nicotinic α6 subunit gene determines variability in chronic pain sensitivity via cross-inhibition of P2X2/3 receptors. Sci Transl Med 2015; 7:287ra72. [PMID: 25972004 PMCID: PMC5018401 DOI: 10.1126/scitranslmed.3009986] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Chronic pain is a highly prevalent and poorly managed human health problem. We used microarray-based expression genomics in 25 inbred mouse strains to identify dorsal root ganglion (DRG)-expressed genetic contributors to mechanical allodynia, a prominent symptom of chronic pain. We identified expression levels of Chrna6, which encodes the α6 subunit of the nicotinic acetylcholine receptor (nAChR), as highly associated with allodynia. We confirmed the importance of α6* (α6-containing) nAChRs by analyzing both gain- and loss-of-function mutants. We find that mechanical allodynia associated with neuropathic and inflammatory injuries is significantly altered in α6* mutants, and that α6* but not α4* nicotinic receptors are absolutely required for peripheral and/or spinal nicotine analgesia. Furthermore, we show that Chrna6's role in analgesia is at least partially due to direct interaction and cross-inhibition of α6* nAChRs with P2X2/3 receptors in DRG nociceptors. Finally, we establish the relevance of our results to humans by the observation of genetic association in patients suffering from chronic postsurgical and temporomandibular pain.
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Affiliation(s)
- Jeffrey S Wieskopf
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Jayanti Mathur
- Genomic Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Walrati Limapichat
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Michael R Post
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Mona Al-Qazzaz
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - Robert E Sorge
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Loren J Martin
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Dmitri V Zaykin
- National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Shad B Smith
- Center for Neurosensory Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Kelen Freitas
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23219, USA
| | - Jean-Sebastien Austin
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Feng Dai
- Departments of Anesthesiology and Human Genetics, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jie Zhang
- Genomic Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Jaclyn Marcovitz
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Alexander H Tuttle
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Peter M Slepian
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Sarah Clarke
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Ryan M Drenan
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - Jeff Janes
- Genomic Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Shakir Al Sharari
- Department of Pharmacology, King Saud University, P. O. Box 2457, Riyadh 11451, Saudi Arabia
| | - Samantha K Segall
- Center for Neurosensory Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Eske K Aasvang
- Section for Surgical Pathophysiology, Rigshospitalet, Copenhagen University, 2100 Copenhagen, Denmark
| | - Weike Lai
- Departments of Anesthesiology and Human Genetics, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Reinhard Bittner
- Department of Surgery, Marienhospital Stuttgart, 70199 Stuttgart, Germany
| | | | - Gary D Slade
- Department of Dental Ecology, School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Henrik Kehlet
- Section for Surgical Pathophysiology, Rigshospitalet, Copenhagen University, 2100 Copenhagen, Denmark
| | - John Walker
- Genomic Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Uwe Maskos
- Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571, Département de Neuroscience, Institute Pasteur, 75724 Paris, France
| | - Jean-Pierre Changeux
- Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571, Département de Neuroscience, Institute Pasteur, 75724 Paris, France
| | - Marshall Devor
- Department of Cell and Developmental Biology, Institute of Life Sciences and Center for Research on Pain, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - William Maixner
- Center for Neurosensory Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Luda Diatchenko
- Center for Neurosensory Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Faculty of Dentistry, Department of Anesthesia, and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1G1, Canada
| | - Inna Belfer
- Departments of Anesthesiology and Human Genetics, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Andrew I Su
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Sarah C R Lummis
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23219, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Ardem Patapoutian
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, and Howard Hughes Medical Institute, La Jolla, CA 92037, USA
| | - Jeffrey S Mogil
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada.
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43
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Post MR, Limapichat W, Lester HA, Dougherty DA. Heterologous expression and nonsense suppression provide insights into agonist behavior at α6β2 nicotinic acetylcholine receptors. Neuropharmacology 2015; 97:376-82. [PMID: 25908401 DOI: 10.1016/j.neuropharm.2015.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/27/2015] [Accepted: 04/10/2015] [Indexed: 10/23/2022]
Abstract
The α6-containing subtypes of the nicotinic acetylcholine receptor (nAChR) are localized to presynaptic terminals of the dopaminergic pathways of the central nervous system. Selective ligands for these nAChRs are potentially useful in both Parkinson's disease and addiction. For these and other goals, it is important to distinguish the binding behavior of agonists at the α6-β2 binding site versus other subtypes. To study this problem, we apply nonsense suppression-based non-canonical amino acid mutagenesis. We report a combination of four mutations in α6β2 that yield high-level heterologous expression in Xenopus oocytes. By varying mRNA injection ratios, two populations were observed with unique characteristics, likely due to differing stoichiometries. Responses to nine known nAChR agonists were analyzed at the receptor, and their corresponding EC50 values and efficacies are reported. The system is compatible with nonsense suppression, allowing structure-function studies between Trp149 - a conserved residue on loop B found to make a cation-π interaction at several nAChR subtypes - and several agonists. These studies reveal that acetylcholine forms a strong cation-π interaction with the conserved tryptophan, while nicotine and TC299423 do not, suggesting a unique pharmacology for the α6β2 nAChR.
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Affiliation(s)
- Michael R Post
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125, USA
| | - Walrati Limapichat
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125, USA.
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44
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Abstract
Upregulation of neuronal nicotinic acetylcholine receptors (AChRs) is a venerable result of chronic exposure to nicotine; but it is one of several consequences of pharmacological chaperoning by nicotine and by some other nicotinic ligands, especially agonists. Nicotinic ligands permeate through cell membranes, bind to immature AChR oligomers, elicit incompletely understood conformational reorganizations, increase the interaction between adjacent AChR subunits, and enhance the maturation process toward stable AChR pentamers. These changes and stabilizations in turn lead to increases in both anterograde and retrograde traffic within the early secretory pathway. In addition to the eventual upregulation of AChRs at the plasma membrane, other effects of pharmacological chaperoning include modifications to endoplasmic reticulum stress and to the unfolded protein response. Because these processes depend on pharmacological chaperoning within intracellular organelles, we group them as "inside-out pharmacology". This term contrasts with the better-known, acute, "outside-in" effects of activating and desensitizing plasma membrane AChRs. We review current knowledge concerning the mechanisms and consequences of inside-out pharmacology. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Affiliation(s)
- Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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45
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Miles TF, Lester HA, Dougherty DA. Allosteric activation of the 5-HT3AB receptor by mCPBG. Neuropharmacology 2014; 91:103-8. [PMID: 25541413 DOI: 10.1016/j.neuropharm.2014.12.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 10/16/2014] [Accepted: 12/10/2014] [Indexed: 10/25/2022]
Abstract
The 5-HT3AB receptor contains three A and two B subunits in an A-A-B-A-B order. However, serotonin function at the 5-HT3AB receptor has been shown to depend solely on the A-A interface present in the homomeric receptor. Using mutations at sites on both the primary (E122) and complementary (Y146) faces of the B subunit, we demonstrate that meta-chlorophenyl biguanide (mCPBG), a 5-HT3 selective agonist, is capable of binding to and activating the 5-HT3AB receptor at all five subunit interfaces of the heteromer. Further, mCPBG is capable of allosterically modulating the activity of serotonin from these sites. While these five binding sites are similar enough that they conform to a monophasic dose - response relationship, we uncover subtle differences in the heteromeric binding sites. We also find that the A-A interface appears to contribute disproportionately to the efficacy of 5-HT3AB receptor activation.
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Affiliation(s)
- Timothy F Miles
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA.
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46
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Nichols WA, Henderson BJ, Yu C, Parker RL, Richards CI, Lester HA, Miwa JM. Lynx1 shifts α4β2 nicotinic receptor subunit stoichiometry by affecting assembly in the endoplasmic reticulum. J Biol Chem 2014; 289:31423-32. [PMID: 25193667 PMCID: PMC4223341 DOI: 10.1074/jbc.m114.573667] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/30/2014] [Indexed: 01/11/2023] Open
Abstract
Glycosylphosphatidylinositol-anchored neurotoxin-like receptor binding proteins, such as lynx modulators, are topologically positioned to exert pharmacological effects by binding to the extracellular portion of nAChRs. These actions are generally thought to proceed when both lynx and the nAChRs are on the plasma membrane. Here, we demonstrate that lynx1 also exerts effects on α4β2 nAChRs within the endoplasmic reticulum. Lynx1 affects assembly of nascent α4 and β2 subunits and alters the stoichiometry of the receptor population that reaches the plasma membrane. Additionally, these data suggest that lynx1 shifts nAChR stoichiometry to low sensitivity (α4)3(β2)2 pentamers primarily through this interaction in the endoplasmic reticulum, rather than solely via direct modulation of activity on the plasma membrane. To our knowledge, these data represent the first test of the hypothesis that a lynx family member, or indeed any glycosylphosphatidylinositol-anchored protein, could act within the cell to alter assembly of a multisubunit protein.
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Affiliation(s)
- Weston A Nichols
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Brandon J Henderson
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Caroline Yu
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Rell L Parker
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | | | - Henry A Lester
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Julie M Miwa
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, the Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
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47
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Daeffler KNM, Lester HA, Dougherty DA. Functional evaluation of key interactions evident in the structure of the eukaryotic Cys-loop receptor GluCl. ACS Chem Biol 2014; 9:2283-90. [PMID: 25051140 PMCID: PMC4201344 DOI: 10.1021/cb500323d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
![]()
The
publication of the first high-resolution crystal structure
of a eukaryotic Cys-loop receptor, GluClα, has provided valuable
structural information on this important class of ligand-gated ion
channels (LGIC). However, limited functional data exist for the GluCl
receptors. Before applying the structural insights from GluCl to mammalian
Cys-loop receptors such as nicotinic acetylcholine and GABA receptors,
it is important to ensure that established functional features of mammalian Cys-loop receptors are present in the more
distantly related GluCl receptors. Here, we seek to identify ligand-binding
interactions that are generally associated with Cys-loop receptors,
including the frequently observed cation−π interaction.
Our studies were performed on the highly homologous GluClβ receptor,
because GluClα is not activated by glutamate in Xenopus
laevis oocytes. Mutagenesis of the signal peptide and pore
lining helix was performed to enhance functional expression and sensitivity
to applied ligand, respectively. Conventional and unnatural amino
acid mutagenesis indicate a strong cation−π interaction
between Y206 and the protonated amine of glutamate, as well as other
important ionic and hydrogen bond interactions between the ligand
and the binding site, consistent with the crystal structure.
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Affiliation(s)
- Kristina N.-M. Daeffler
- Division of Chemistry & Chemical Engineering and ‡Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Henry A. Lester
- Division of Chemistry & Chemical Engineering and ‡Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Dennis A. Dougherty
- Division of Chemistry & Chemical Engineering and ‡Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
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48
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Limapichat W, Dougherty DA, Lester HA. Subtype-specific mechanisms for functional interaction between α6β4* nicotinic acetylcholine receptors and P2X receptors. Mol Pharmacol 2014; 86:263-74. [PMID: 24966348 PMCID: PMC4152909 DOI: 10.1124/mol.114.093179] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 06/24/2014] [Indexed: 11/22/2022] Open
Abstract
P2X receptors and nicotinic acetylcholine receptors (nAChRs) display functional and physical interactions in many cell types and heterologous expression systems, but interactions between α6β4-containing (α6β4*) nAChRs and P2X2 receptors and/or P2X3 receptors have not been fully characterized. We measured several types of crosstalk in oocytes coexpressing α6β4 nAChRs and P2X2, P2X3, or P2X2/3 receptors. A novel form of crosstalk occurs between α6β4 nAChRs and P2X2 receptors. P2X2 receptors were forced into a prolonged desensitized state upon activation by ATP through a mechanism that does not depend on the intracellular C terminus of the P2X2 receptors. Coexpression of α6β4 nAChRs with P2X3 receptors shifts the ATP dose-response relation to the right, even in the absence of acetylcholine (ACh). Moreover, currents become nonadditive when ACh and ATP are coapplied, as previously reported for other Cys-loop receptors interacting with P2X receptors, and this crosstalk is dependent on the presence of the P2X3 C-terminal domain. P2X2 receptors also functionally interact with α6β4β3 but through a different mechanism from α6β4. The interaction with P2X3 receptors is less pronounced for the α6β4β3 nAChR than the α6β4 nAChR. We also measured a functional interaction between the α6β4 nAChRs and the heteromeric P2X2/3 receptor. Experiments with the nAChR channel blocker mecamylamine on P2X2-α6β4 oocytes point to the loss of P2X2 channel activity during the crosstalk, whereas the ion channel pores of the P2X receptors were fully functional and unaltered by the receptor interaction for P2X2-α6β4β3, P2X2/3-α6β4, and P2X2/3-α6β4β3. These results may be relevant to dorsal root ganglion cells and to other neurons that coexpress these receptor subunits.
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Affiliation(s)
- Walrati Limapichat
- Divisions of Chemistry and Chemical Engineering (W.L., D.A.D.) and Biology and Biological Engineering (H.A.L.), California Institute of Technology, Pasadena, California
| | - Dennis A Dougherty
- Divisions of Chemistry and Chemical Engineering (W.L., D.A.D.) and Biology and Biological Engineering (H.A.L.), California Institute of Technology, Pasadena, California
| | - Henry A Lester
- Divisions of Chemistry and Chemical Engineering (W.L., D.A.D.) and Biology and Biological Engineering (H.A.L.), California Institute of Technology, Pasadena, California
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49
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Henderson BJ, Srinivasan R, Nichols WA, Dilworth CN, Gutierrez DF, Mackey EDW, McKinney S, Drenan RM, Richards CI, Lester HA. Nicotine exploits a COPI-mediated process for chaperone-mediated up-regulation of its receptors. ACTA ACUST UNITED AC 2014; 143:51-66. [PMID: 24378908 PMCID: PMC3874574 DOI: 10.1085/jgp.201311102] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Chronic exposure to nicotine up-regulates high sensitivity nicotinic acetylcholine receptors (nAChRs) in the brain. This up-regulation partially underlies addiction and may also contribute to protection against Parkinson's disease. nAChRs containing the α6 subunit (α6* nAChRs) are expressed in neurons in several brain regions, but comparatively little is known about the effect of chronic nicotine on these nAChRs. We report here that nicotine up-regulates α6* nAChRs in several mouse brain regions (substantia nigra pars compacta, ventral tegmental area, medial habenula, and superior colliculus) and in neuroblastoma 2a cells. We present evidence that a coat protein complex I (COPI)-mediated process mediates this up-regulation of α6* or α4* nAChRs but does not participate in basal trafficking. We show that α6β2β3 nAChR up-regulation is prevented by mutating a putative COPI-binding motif in the β3 subunit or by inhibiting COPI. Similarly, a COPI-dependent process is required for up-regulation of α4β2 nAChRs by chronic nicotine but not for basal trafficking. Mutation of the putative COPI-binding motif or inhibition of COPI also results in reduced normalized Förster resonance energy transfer between α6β2β3 nAChRs and εCOP subunits. The discovery that nicotine exploits a COPI-dependent process to chaperone high sensitivity nAChRs is novel and suggests that this may be a common mechanism in the up-regulation of nAChRs in response to chronic nicotine.
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Affiliation(s)
- Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
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50
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Wang Y, Xiao C, Indersmitten T, Freedman R, Leonard S, Lester HA. The duplicated α7 subunits assemble and form functional nicotinic receptors with the full-length α7. J Biol Chem 2014; 289:26451-26463. [PMID: 25056953 DOI: 10.1074/jbc.m114.582858] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor gene (CHRNA7) is linked to schizophrenia. A partial duplication of CHRNA7 (CHRFAM7A) is found in humans on 15q13-14. Exon 6 of CHRFAM7A harbors a 2-bp deletion polymorphism, CHRFAM7AΔ2bp, which is also associated with schizophrenia. To understand the effects of the duplicated subunits on α7 receptors, we fused α7, dupα7, and dupΔα7 subunits with various fluorescent proteins. The duplicated subunits co-localized with full-length α7 subunits in mouse neuroblastoma cells (Neuro2a) as well as rat hippocampal neurons. We investigated the interaction between the duplicated subunits and full-length α7 by measuring Förster resonance energy transfer using donor recovery after photobleaching and fluorescence lifetime imaging microscopy. The results revealed that the duplicated proteins co-assemble with α7. In electrophysiological studies, Leu at the 9'-position in the M2 membrane-spanning segment was replaced with Cys in dupα7 or dupΔα7, and constructs were co-transfected with full-length α7 in Neuro2a cells. Exposure to ethylammonium methanethiosulfonate inhibited acetylcholine-induced currents, showing that the assembled functional nicotinic acetylcholine receptors (nAChRs) included the duplicated subunit. Incorporation of dupα7 and dupΔα7 subunits modestly changes the sensitivity of receptors to choline and varenicline. Thus, the duplicated proteins are assembled and transported to the cell membrane together with full-length α7 subunits and alter the function of the nAChRs. The characterization of dupα7 and dupΔα7 as well as their influence on α7 nAChRs may help explain the pathophysiology of schizophrenia and may suggest therapeutic strategies.
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Affiliation(s)
- Ying Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and
| | - Cheng Xiao
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and
| | - Tim Indersmitten
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and
| | - Robert Freedman
- Department of Psychiatry, University of Colorado at Denver, Denver, Colorado 80045
| | - Sherry Leonard
- Department of Psychiatry, University of Colorado at Denver, Denver, Colorado 80045
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and.
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