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Carreño D, Facundo A, Nguyen MTT, Lotfipour S. Dopamine and Norepinephrine Tissue Levels in the Developing Limbic Brain Are Impacted by the Human CHRNA6 3'-UTR Single-Nucleotide Polymorphism (rs2304297) in Rats. Int J Mol Sci 2024; 25:3676. [PMID: 38612487 PMCID: PMC11011259 DOI: 10.3390/ijms25073676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 03/16/2024] [Accepted: 03/19/2024] [Indexed: 04/14/2024] Open
Abstract
We previously demonstrated that a genetic single-nucleotide polymorphism (SNP, rs2304297) in the 3' untranslated region (UTR) of the human CHRNA6 gene has sex- and genotype-dependent effects on nicotine-induced locomotion, anxiety, and nicotine + cue-induced reinstatement in adolescent rats. This study aims to investigate how the CHRNA6 3'-UTR SNP influences dopaminergic and noradrenergic tissue levels in brain reward regions during baseline and after the reinstatement of drug-seeking behavior. Naïve adolescent and adult rats, along with those undergoing nicotine + cue reinstatement and carrying the CHRNA6 3'-UTR SNP, were assessed for dopamine (DA), norepinephrine (NE), and metabolites in reward pathway regions. The results reveal age-, sex-, and genotype-dependent baseline DA, NE, and DA turnover levels. Post-reinstatement, male α6GG rats show suppressed DA levels in the Nucleus Accumbens (NAc) Shell compared to the baseline, while nicotine+ cue-induced reinstatement behavior correlates with neurotransmitter levels in specific brain regions. This study emphasizes the role of CHRNA6 3'-UTR SNP in the developmental maturation of the dopaminergic and noradrenergic system in the adolescent rat brain, with tissue levels acting as predictors of nicotine + cue-induced reinstatement.
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Affiliation(s)
- Diana Carreño
- Department of Emergency Medicine, University of California, Irvine, CA 92697, USA
| | - Antonella Facundo
- Department of Emergency Medicine, University of California, Irvine, CA 92697, USA
| | - My Trang Thi Nguyen
- Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697, USA
| | - Shahrdad Lotfipour
- Department of Emergency Medicine, University of California, Irvine, CA 92697, USA
- Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697, USA
- Department of Pathology and Laboratory Medicine, University of California, Irvine, CA 92617, USA
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2
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Jiménez-Pompa A, Albillos A. Nicotinic Receptors in Human Chromaffin Cells: Characterization, Functional and Physical Interactions between Subtypes and Regulation. Int J Mol Sci 2024; 25:2304. [PMID: 38396980 PMCID: PMC10888968 DOI: 10.3390/ijms25042304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 02/06/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
This review summarizes our research on nicotinic acetylcholine receptors in human chromaffin cells. Limited research has been conducted in this field on human tissue, primarily due to the difficulties associated with obtaining human cells. Receptor subtypes were characterized here using molecular biology and electrophysiological patch-clamp techniques. However, the most significant aspect of this study refers to the cross-talk between the two main subtypes identified in these cells, the α7- and α3β4* subtypes, aiming to avoid their desensitization. The article also reviews other aspects, including the regulation of their expression, function or physical interaction by choline, Ca2+, and tyrosine and serine/threonine phosphatases. Additionally, the influence of sex on their expression is also discussed.
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Affiliation(s)
| | - Almudena Albillos
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, 4 Arzobispo Morcillo Str., 28029 Madrid, Spain;
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3
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Wu X, Hone AJ, Huang YH, Clark RJ, McIntosh JM, Kaas Q, Craik DJ. Computational Design of α-Conotoxins to Target Specific Nicotinic Acetylcholine Receptor Subtypes. Chemistry 2024; 30:e202302909. [PMID: 37910861 PMCID: PMC10872529 DOI: 10.1002/chem.202302909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 10/25/2023] [Accepted: 10/26/2023] [Indexed: 11/03/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are drug targets for neurological diseases and disorders, but selective targeting of the large number of nAChR subtypes is challenging. Marine cone snail α-conotoxins are potent blockers of nAChRs and some have been engineered to achieve subtype selectivity. This engineering effort would benefit from rapid computational methods able to predict mutational energies, but current approaches typically require high-resolution experimental structures, which are not widely available for α-conotoxin complexes. Herein, five mutational energy prediction methods were benchmarked using crystallographic and mutational data on two acetylcholine binding protein/α-conotoxin systems. Molecular models were developed for six nAChR subtypes in complex with five α-conotoxins that were studied through 150 substitutions. The best method was a combination of FoldX and molecular dynamics simulations, resulting in a predictive Matthews Correlation Coefficient (MCC) of 0.68 (85 % accuracy). Novel α-conotoxin mutants designed using this method were successfully validated by experimental assay with improved pharmaceutical properties. This work paves the way for the rapid design of subtype-specific nAChR ligands and potentially accelerated drug development.
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Affiliation(s)
- Xiaosa Wu
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, 4072, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Arik J Hone
- School of Biological Science, University of Utah, Salt Lake City, Utah, 84112, USA
- MIRECC, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, 84112, USA
| | - Yen-Hua Huang
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Richard J Clark
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - J Michael McIntosh
- School of Biological Science, University of Utah, Salt Lake City, Utah, 84112, USA
- Department of Psychiatry, University of Utah, Salt Lake City, Utah, 84112, USA
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, 84112, USA
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, 4072, Australia
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4
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George AA, John SJ, Lucero LM, Eaton JB, Jaiswal E, Christensen SB, Gajewiak J, Watkins M, Cao Y, Olivera BM, Im W, McIntosh JM, Whiteaker P. Analogs of α-conotoxin PnIC selectively inhibit α7β2- over α7-only subtype nicotinic acetylcholine receptors via a novel allosteric mechanism. FASEB J 2024; 38:e23374. [PMID: 38161283 PMCID: PMC10782225 DOI: 10.1096/fj.202302079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 12/01/2023] [Indexed: 01/03/2024]
Abstract
This study was undertaken to identify and characterize the first ligands capable of selectively identifying nicotinic acetylcholine receptors containing α7 and β2 subunits (α7β2-nAChR subtype). Basal forebrain cholinergic neurons express α7β2-nAChR. Here, they appear to mediate neuronal dysfunction induced by the elevated levels of oligomeric amyloid-β associated with early Alzheimer's disease. Additional work indicates that α7β2-nAChR are expressed across several further critically important cholinergic and GABAergic neuronal circuits within the central nervous system. Further studies, however, are significantly hindered by the inability of currently available ligands to distinguish heteromeric α7β2-nAChR from the closely related and more widespread homomeric α7-only-nAChR subtype. Functional screening using two-electrode voltage-clamp electrophysiology identified a family of α7β2-nAChR-selective analogs of α-conotoxin PnIC (α-CtxPnIC). A combined electrophysiology, functional kinetics, site-directed mutagenesis, and molecular dynamics approach was used to further characterize the α7β2-nAChR selectivity and site of action of these α-CtxPnIC analogs. We determined that α7β2-nAChR selectivity of α-CtxPnIC analogs arises from interactions at a site distinct from the orthosteric agonist-binding site shared between α7β2- and α7-only-nAChR. As numerous previously identified α-Ctx ligands are competitive antagonists of orthosteric agonist-binding sites, this study profoundly expands the scope of use of α-Ctx ligands (which have already provided important nAChR research and translational breakthroughs). More immediately, analogs of α-CtxPnIC promise to enable, for the first time, both comprehensive mapping of the distribution of α7β2-nAChR and detailed investigations of their physiological roles.
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Affiliation(s)
- Andrew A. George
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
| | - Sabin J. John
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
- Department of Life SciencesUniversity of BathBathUK
| | - Linda M. Lucero
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | - J. Brek Eaton
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | - Ekta Jaiswal
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | | | - Joanna Gajewiak
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
| | - Maren Watkins
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
| | - Yiwei Cao
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | | | - Wonpil Im
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | - J. Michael McIntosh
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
- George E. Wahlen Veterans Affairs Medical CenterSalt Lake CityUtahUSA
- Department of PsychiatryUniversity of UtahSalt Lake CityUtahUSA
| | - Paul Whiteaker
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
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5
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Pei S, Xu C, Tan Y, Wang M, Yu J, Zhangsun D, Zhu X, Luo S. Synthesis, Activity, and Application of Fluorescent Analogs of [D1G, Δ14Q]LvIC Targeting α6β4 Nicotinic Acetylcholine Receptor. Bioconjug Chem 2023; 34:2194-2204. [PMID: 37748043 DOI: 10.1021/acs.bioconjchem.3c00283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
α6β4* nicotinic acetylcholine receptor (nAChR) (* represents the possible presence of additional subunits) is mainly distributed in the central and peripheral nervous system and is associated with neurological diseases, such as neuropathic pain; however, the ability to explore its function and distribution is limited due to the lack of pharmacological tools. As one of the analogs of α-conotoxin (α-CTx) LvIC from Conus lividus, [D1G, Δ14Q]LvIC (Lv) selectively and potently blocks α6/α3β4 nAChR (α6/α3 represents a chimera). Here, we synthesized three fluorescent analogs of Lv by connecting fluorescent molecules 6-carboxytetramethylrhodamine succinimidyl ester (6-TAMRA-SE, R), Cy3 NHS ester (Cy3, C) and BODIPY-FL NHS ester (BDP, B) to the N-terminus of the peptide and obtained Lv-R, Lv-C, and Lv-B, respectively. The potency and selectivity of three fluorescent peptides were evaluated using two-electrode voltage-clamp recording on nAChR subtypes expressed in Xenopus laevis oocytes, and the potency and selectivity of Lv-B were almost maintained with the half-maximal inhibition (IC50) of 64 nM. Then, we explored the stability of Lv-B in artificial cerebrospinal fluid and stained rat brain slices with Lv-B. The results indicated that the stability of Lv-B was slightly improved compared to that of native Lv. Additionally, we detected the distribution of the α6β4* nAChR subtype in the cerebral cortex using green fluorescently labeled peptide and fluorescence microscopy. Our findings not only provide a visualized pharmacological tool for exploring the distribution of the α6β4* nAChR subtype in various situ tissues and organs but also extend the application of α-CTx [D1G, Δ14Q]LvIC to demonstrate the involvement of α6β4 nAChR function in pathophysiology and pharmacology.
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Affiliation(s)
- Shengrong Pei
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Chenxing Xu
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Yao Tan
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Meiting Wang
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Jinpeng Yu
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Dongting Zhangsun
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China
| | - Xiaopeng Zhu
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Sulan Luo
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China
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6
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Haufe Y, Kuruva V, Samanani Z, Lokaj G, Kamnesky G, Shadamarshan P, Shahoei R, Katz D, Sampson JM, Pusch M, Brik A, Nicke A, Leffler AE. Basic Residues at Position 11 of α-Conotoxin LvIA Influence Subtype Selectivity between α3β2 and α3β4 Nicotinic Receptors via an Electrostatic Mechanism. ACS Chem Neurosci 2023; 14:4311-4322. [PMID: 38051211 DOI: 10.1021/acschemneuro.3c00506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023] Open
Abstract
Understanding the determinants of α-conotoxin (α-CTX) selectivity for different nicotinic acetylcholine receptor (nAChR) subtypes is a prerequisite for the design of tool compounds to study nAChRs. However, selectivity optimization of these small, disulfide-rich peptides is difficult not only because of an absence of α-CTX/nAChR co-structures but also because it is challenging to predict how a mutation to an α-CTX will alter its potency and selectivity. As a prototypical system to investigate selectivity, we employed the α-CTX LvIA that is 25-fold selective for the α3β2 nAChR over the related α3β4 nAChR subtype, which is a target for nicotine addiction. Using two-electrode voltage clamp electrophysiology, we identified LvIA[D11R] that is 2-fold selective for the α3β4 nAChR, reversing the subtype preference. This effect is specifically due to the change in charge and not shape of LvIA[D11R], as substitution of D11 with citrulline retains selectivity for the α3β2 nAChR. Furthermore, LvIA[D11K] shows a stronger reversal, with 4-fold selectivity for the α3β4 nAChR. Motivated by these findings, using site-directed mutagenesis, we found that β2[K79A] (I79 on β4), but not β2[K78A] (N78 on β4), largely restores the potency of basic mutants at position 11. Finally, to understand the structural basis of this effect, we used AlphaFold2 to generate models of LvIA in complex with both nAChR subtypes. Both models confirm the plausibility of an electrostatic mechanism to explain the data and also reproduce a broad range of potency and selectivity structure-activity relationships for LvIA mutants, as measured using free energy perturbation simulations. Our work highlights how electrostatic interactions can drive α-CTX selectivity and may serve as a strategy for optimizing the selectivity of LvIA and other α-CTXs.
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Affiliation(s)
- Yves Haufe
- Faculty of Medicine, Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich 80539, Germany
| | - Veeresh Kuruva
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200008, Israel
| | - Ziyana Samanani
- Schrödinger, Inc., 1540 Broadway, New York, New York 10036, United States
| | - Gonxhe Lokaj
- Faculty of Medicine, Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich 80539, Germany
| | - Guy Kamnesky
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200008, Israel
| | - PranavKumar Shadamarshan
- Faculty of Medicine, Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich 80539, Germany
| | - Rezvan Shahoei
- Schrödinger, Inc., 1540 Broadway, New York, New York 10036, United States
| | - Dana Katz
- Schrödinger, Inc., 1540 Broadway, New York, New York 10036, United States
| | - Jared M Sampson
- Schrödinger, Inc., 1540 Broadway, New York, New York 10036, United States
| | - Michael Pusch
- Istituto di Biofisica, CNR, Via De Marini 6, Genova 16149, Italy
| | - Ashraf Brik
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200008, Israel
| | - Annette Nicke
- Faculty of Medicine, Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich 80539, Germany
| | - Abba E Leffler
- Schrödinger, Inc., 1540 Broadway, New York, New York 10036, United States
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7
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Dong J, Zhang P, Xie J, Xie T, Zhu X, Zhangsun D, Yu J, Luo S. Loop2 Size Modification Reveals Significant Impacts on the Potency of α-Conotoxin TxID. Mar Drugs 2023; 21:md21050286. [PMID: 37233480 DOI: 10.3390/md21050286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 04/27/2023] [Accepted: 04/29/2023] [Indexed: 05/27/2023] Open
Abstract
α4/6-conotoxin TxID, which was identified from Conus textile, simultaneously blocks rat (r) α3β4 and rα6/α3β4 nicotinic acetylcholine receptors (nAChRs) with IC50 values of 3.6 nM and 33.9 nM, respectively. In order to identify the effects of loop2 size on the potency of TxID, alanine (Ala) insertion and truncation mutants were designed and synthesized in this study. An electrophysiological assay was used to evaluate the activity of TxID and its loop2-modified mutants. The results showed that the inhibition of 4/7-subfamily mutants [+9A]TxID, [+10A]TxID, [+14A]TxID, and all the 4/5-subfamily mutants against rα3β4 and rα6/α3β4 nAChRs decreased. Overall, ala-insertion or truncation of the 9th, 10th, and 11th amino acid results in a loss of inhibition and the truncation of loop2 has more obvious impacts on its functions. Our findings have strengthened the understanding of α-conotoxin, provided guidance for further modifications, and offered a perspective for future studies on the molecular mechanism of the interaction between α-conotoxins and nAChRs.
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Affiliation(s)
- Jianying Dong
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Panpan Zhang
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Junjie Xie
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Ting Xie
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Xiaopeng Zhu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China
| | - Jinpeng Yu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Sulan Luo
- School of Medicine, Guangxi University, Nanning 530004, China
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China
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8
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Zhu X, Wang S, Kaas Q, Yu J, Wu Y, Harvey PJ, Zhangsun D, Craik DJ, Luo S. Discovery, Characterization, and Engineering of LvIC, an α4/4-Conotoxin That Selectively Blocks Rat α6/α3β4 Nicotinic Acetylcholine Receptors. J Med Chem 2023; 66:2020-2031. [PMID: 36682014 DOI: 10.1021/acs.jmedchem.2c01786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
α6β4 nicotinic acetylcholine receptors (nAChRs) are expressed in the central and peripheral nervous systems, but their functions are not fully understood, largely because of a lack of specific ligands. Here, we characterized a novel α-conotoxin, LvIC, and designed a series of analogues to probe structure-activity relationships at the α6β4 nAChR. The potency and selectivity of these conotoxins were tested using two-electrode voltage-clamp recording on nAChR subtypes expressed in Xenopus laevis oocytes. One of the analogues, [D1G,ΔQ14]LvIC, potently blocked α6/α3β4 nAChRs (α6/α3 is a chimera) with an IC50 of 19 nM, with minimal activity at other nAChR subtypes, including the structurally similar α6/α3β2β3 and α3β4 subtypes. Using NMR, molecular docking, and receptor mutation, structure-activity relationships of [D1G,ΔQ14]LvIC at the α6/α3β4 nAChR were defined. It is a potent and specific antagonist of α6β4 nAChRs that could potentially serve as a novel molecular probe to explore α6β4 nAChR-related neurophysiological and pharmacological functions.
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Affiliation(s)
- Xiaopeng Zhu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Shuai Wang
- Center for Novel Target and Therapeutic Intervention, Institute of Life Sciences, Chongqing Medical University, Chongqing 400016, China
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane 4072, Queensland, Australia
| | - Jinpeng Yu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Yong Wu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Peta J Harvey
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane 4072, Queensland, Australia
| | - Dongting Zhangsun
- School of Medicine, Guangxi University, Nanning 530004, China.,Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China
| | - David J Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane 4072, Queensland, Australia
| | - Sulan Luo
- School of Medicine, Guangxi University, Nanning 530004, China.,Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China
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9
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A Novel α4/7-Conotoxin QuIA Selectively Inhibits α3β2 and α6/α3β4 Nicotinic Acetylcholine Receptor Subtypes with High Efficacy. Mar Drugs 2022; 20:md20020146. [PMID: 35200675 PMCID: PMC8878501 DOI: 10.3390/md20020146] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 02/07/2022] [Accepted: 02/14/2022] [Indexed: 12/10/2022] Open
Abstract
α6β4 nAChR is expressed in the peripheral and central nervous systems and is associated with pain, addiction, and movement disorders. Natural α-conotoxins (α-CTxs) can effectively block different nAChR subtypes with higher efficacy and selectivity. However, the research on α6β4 nAChR is relatively poor, partly because of the lack of available target-specific α-CTxs. In this study, we synthesized a novel α-4/7 conotoxin QuIA that was found from Conus quercinus. We investigated the efficacy of this peptide to different nAChR subtypes using a two-electrode voltage-clamp technique. Remarkably, we found α-QuIA inhibited the neuronal α3β2 and α6/α3β4 nAChR subtypes with significantly high affinity (IC50 was 55.7 nM and 90.68 nM, respectively), and did not block other nAChR subtypes even at a high concentration of 10 μM. In contrast, most α-CTxs have been determined so far to effectively block the α6/α3β4 nAChR subtype while also maintaining a similar higher efficacy against the closely related α6β2β3 and/or α3β4 subtypes, which are different from QuIA. In conclusion, α-QuIA is a novel α4/7-CTx, which has the potential to develop as an effective neuropharmacology tool to detect the function of α6β4 nAChR.
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10
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Wills L, Ables JL, Braunscheidel KM, Caligiuri SPB, Elayouby KS, Fillinger C, Ishikawa M, Moen JK, Kenny PJ. Neurobiological Mechanisms of Nicotine Reward and Aversion. Pharmacol Rev 2022; 74:271-310. [PMID: 35017179 PMCID: PMC11060337 DOI: 10.1124/pharmrev.121.000299] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 08/24/2021] [Indexed: 12/27/2022] Open
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) regulate the rewarding actions of nicotine contained in tobacco that establish and maintain the smoking habit. nAChRs also regulate the aversive properties of nicotine, sensitivity to which decreases tobacco use and protects against tobacco use disorder. These opposing behavioral actions of nicotine reflect nAChR expression in brain reward and aversion circuits. nAChRs containing α4 and β2 subunits are responsible for the high-affinity nicotine binding sites in the brain and are densely expressed by reward-relevant neurons, most notably dopaminergic, GABAergic, and glutamatergic neurons in the ventral tegmental area. High-affinity nAChRs can incorporate additional subunits, including β3, α6, or α5 subunits, with the resulting nAChR subtypes playing discrete and dissociable roles in the stimulatory actions of nicotine on brain dopamine transmission. nAChRs in brain dopamine circuits also participate in aversive reactions to nicotine and the negative affective state experienced during nicotine withdrawal. nAChRs containing α3 and β4 subunits are responsible for the low-affinity nicotine binding sites in the brain and are enriched in brain sites involved in aversion, including the medial habenula, interpeduncular nucleus, and nucleus of the solitary tract, brain sites in which α5 nAChR subunits are also expressed. These aversion-related brain sites regulate nicotine avoidance behaviors, and genetic variation that modifies the function of nAChRs in these sites increases vulnerability to tobacco dependence and smoking-related diseases. Here, we review the molecular, cellular, and circuit-level mechanisms through which nicotine elicits reward and aversion and the adaptations in these processes that drive the development of nicotine dependence. SIGNIFICANCE STATEMENT: Tobacco use disorder in the form of habitual cigarette smoking or regular use of other tobacco-related products is a major cause of death and disease worldwide. This article reviews the actions of nicotine in the brain that contribute to tobacco use disorder.
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Affiliation(s)
- Lauren Wills
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Jessica L Ables
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Kevin M Braunscheidel
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Stephanie P B Caligiuri
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Karim S Elayouby
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Clementine Fillinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Masago Ishikawa
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Janna K Moen
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Paul J Kenny
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
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11
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Ho TNT, Abraham N, Lewis RJ. Unique Pharmacological Properties of α-Conotoxin OmIA at α7 nAChRs. Front Pharmacol 2021; 12:803397. [PMID: 34955864 PMCID: PMC8692984 DOI: 10.3389/fphar.2021.803397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/22/2021] [Indexed: 11/13/2022] Open
Abstract
OmIA, isolated from Conus omaria venom, is a potent antagonist at α7 nAChRs. We determined the co-crystal structure of OmIA with Lymnae stagnalis acetylcholine binding protein (Ls-AChBP) that identified His5, Val10 and Asn11 as key determinants for the high potency of OmIA at α7 nAChRs. Remarkably, despite a competitive binding mode observed in the co-crystal structure, OmIA and analogues displayed functional insurmountable antagonism at α7 and α3β4 nAChRs, except OmIA analogues having long side chain at position 10 ([V10Q]OmIA and [V10L]OmIA), which were partial insurmountable antagonist at α7 nAChRs in the presence of type II positive allosteric modulators (PAMs). A “two-state, two-step” model was used to explain these observations, with [V10Q]OmIA and [V10L]OmIA co-existing in a fast reversible/surmountable as well as a tight binding/insurmountable state. OmIA and analogues also showed biphasic-inhibition at α7 nAChRs in the presence of PNU120596, with a preference for the high-affinity binding site following prolonged exposure. The molecular basis of binding and complex pharmacological profile of OmIA at α7 nAChRs presented in here expands on the potential of α-conotoxins to probe the pharmacological properties of nAChRs and may help guide the development novel α7 modulators.
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Affiliation(s)
- Thao N T Ho
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Nikita Abraham
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Richard J Lewis
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
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12
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Stone TW. Relationships and Interactions between Ionotropic Glutamate Receptors and Nicotinic Receptors in the CNS. Neuroscience 2021; 468:321-365. [PMID: 34111447 DOI: 10.1016/j.neuroscience.2021.06.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 02/07/2023]
Abstract
Although ionotropic glutamate receptors and nicotinic receptors for acetylcholine (ACh) have usually been studied separately, they are often co-localized and functionally inter-dependent. The objective of this review is to survey the evidence for interactions between the two receptor families and the mechanisms underlying them. These include the mutual regulation of subunit expression, which change the NMDA:AMPA response balance, and the existence of multi-functional receptor complexes which make it difficult to distinguish between individual receptor sites, especially in vivo. This is followed by analysis of the functional relationships between the receptors from work on transmitter release, cellular electrophysiology and aspects of behavior where these can contribute to understanding receptor interactions. It is clear that nicotinic receptors (nAChRs) on axonal terminals directly regulate the release of glutamate and other neurotransmitters, α7-nAChRs generally promoting release. Hence, α7-nAChR responses will be prevented not only by a nicotinic antagonist, but also by compounds blocking the indirectly activated glutamate receptors. This accounts for the apparent anticholinergic activity of some glutamate antagonists, including the endogenous antagonist kynurenic acid. The activation of presynaptic nAChRs is by the ambient levels of ACh released from pre-terminal synapses, varicosities and glial cells, acting as a 'volume neurotransmitter' on synaptic and extrasynaptic sites. In addition, ACh and glutamate are released as CNS co-transmitters, including 'cholinergic' synapses onto spinal Renshaw cells. It is concluded that ACh should be viewed primarily as a modulator of glutamatergic neurotransmission by regulating the release of glutamate presynaptically, and the location, subunit composition, subtype balance and sensitivity of glutamate receptors, and not primarily as a classical fast neurotransmitter. These conclusions and caveats should aid clarification of the sites of action of glutamate and nicotinic receptor ligands in the search for new centrally-acting drugs.
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Affiliation(s)
- Trevor W Stone
- The Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, UK; Institute of Neuroscience, University of Glasgow, G12 8QQ, UK.
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13
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Wills L, Kenny PJ. Addiction-related neuroadaptations following chronic nicotine exposure. J Neurochem 2021; 157:1652-1673. [PMID: 33742685 DOI: 10.1111/jnc.15356] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/14/2021] [Accepted: 03/15/2021] [Indexed: 12/16/2022]
Abstract
The addiction-relevant molecular, cellular, and behavioral actions of nicotine are derived from its stimulatory effects on neuronal nicotinic acetylcholine receptors (nAChRs) in the central nervous system. nAChRs expressed by dopamine-containing neurons in the ventral midbrain, most notably in the ventral tegmental area (VTA), contribute to the reward-enhancing properties of nicotine that motivate the use of tobacco products. nAChRs are also expressed by neurons in brain circuits that regulate aversion. In particular, nAChRs expressed by neurons in the medial habenula (mHb) and the interpeduncular nucleus (IPn) to which the mHb almost exclusively projects regulate the "set-point" for nicotine aversion and control nicotine intake. Different nAChR subtypes are expressed in brain reward and aversion circuits and nicotine intake is titrated to maximally engage reward-enhancing nAChRs while minimizing the recruitment of aversion-promoting nAChRs. With repeated exposure to nicotine, reward- and aversion-related nAChRs and the brain circuits in which they are expressed undergo adaptations that influence whether tobacco use will transition from occasional to habitual. Genetic variation that influences the sensitivity of addiction-relevant brain circuits to the actions of nicotine also influence the propensity to develop habitual tobacco use. Here, we review some of the key advances in our understanding of the mechanisms by which nicotine acts on brain reward and aversion circuits and the adaptations that occur in these circuits that may drive addiction to nicotine-containing tobacco products.
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Affiliation(s)
- Lauren Wills
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, USA
| | - Paul J Kenny
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, USA
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14
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Bekbossynova A, Zharylgap A, Filchakova O. Venom-Derived Neurotoxins Targeting Nicotinic Acetylcholine Receptors. Molecules 2021; 26:molecules26113373. [PMID: 34204855 PMCID: PMC8199771 DOI: 10.3390/molecules26113373] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/05/2021] [Accepted: 05/07/2021] [Indexed: 01/02/2023] Open
Abstract
Acetylcholine was the first neurotransmitter described. The receptors targeted by acetylcholine are found within organisms spanning different phyla and position themselves as very attractive targets for predation, as well as for defense. Venoms of snakes within the Elapidae family, as well as those of marine snails within the Conus genus, are particularly rich in proteins and peptides that target nicotinic acetylcholine receptors (nAChRs). Such compounds are invaluable tools for research seeking to understand the structure and function of the cholinergic system. Proteins and peptides of venomous origin targeting nAChR demonstrate high affinity and good selectivity. This review aims at providing an overview of the toxins targeting nAChRs found within venoms of different animals, as well as their activities and the structural determinants important for receptor binding.
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15
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Wang S, Zhu X, Zhangsun M, Wu Y, Yu J, Harvey PJ, Kaas Q, Zhangsun D, Craik DJ, Luo S. Engineered Conotoxin Differentially Blocks and Discriminates Rat and Human α7 Nicotinic Acetylcholine Receptors. J Med Chem 2021; 64:5620-5631. [PMID: 33902275 DOI: 10.1021/acs.jmedchem.0c02079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The α7 nicotinic acetylcholine receptor (nAChR) is present in the central nervous system and plays an important role in cognitive function and memory. α-Conotoxin LvIB, identified from genomic DNA of Conus lividus, its three isomers and four globular isomer analogues were synthesized and screened at a wide range of nAChR subtypes. One of the analogues, amidated [Q1G,ΔR14]LvIB, was found to be a potent blocker of rat α7 nAChRs. Importantly, it differentiates between α7 nAChRs of human (IC50: 1570 nM) and rat (IC50: 97 nM). Substitutions between rat and human α7 nAChRs at three key mutation sites revealed that no single mutant could completely change the activity profile of amidated [Q1G,ΔR14]LvIB. Rather, we found that the combined influence of Gln141, Asn184, and Lys186 determines the α7 nAChR species specificity of this peptide. This engineered α4/4 conotoxin has potential applications as a template for designing ligands to selectively block human α7 nAChRs.
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Affiliation(s)
- Shuai Wang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.,Medical School, Guangxi University, Nanning 530004, China
| | - Manqi Zhangsun
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Yong Wu
- Medical School, Guangxi University, Nanning 530004, China
| | - Jinpeng Yu
- Medical School, Guangxi University, Nanning 530004, China
| | - Peta J Harvey
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.,Medical School, Guangxi University, Nanning 530004, China
| | - David J Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.,Medical School, Guangxi University, Nanning 530004, China
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16
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Hone AJ, Kaas Q, Kearns I, Hararah F, Gajewiak J, Christensen S, Craik DJ, McIntosh JM. Computational and Functional Mapping of Human and Rat α6β4 Nicotinic Acetylcholine Receptors Reveals Species-Specific Ligand-Binding Motifs. J Med Chem 2021; 64:1685-1700. [PMID: 33523678 PMCID: PMC8382285 DOI: 10.1021/acs.jmedchem.0c01973] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pharmacological targets for the treatment of neuropathic pain, and the α6β4 subtype has been identified as particularly promising. Rat α6β4 nAChRs are less sensitive to some ligands than the human homologue potentially complicating the use of rodent α6β4 receptors for screening therapeutic compounds. We used molecular dynamics simulations coupled with functional assays to study the interaction between α-conotoxin PeIA and α6β4 nAChRs and to identify key ligand-receptor interactions that contribute to species differences in α-conotoxin potency. Our results show that human and rat α6β4 nAChRs have distinct ligand-binding motifs and show markedly different sensitivities to α-conotoxins. These studies facilitated the creation of PeIA-5667, a peptide that shows 270-fold higher potency for rat α6β4 nAChRs over native PeIA and similar potency for the human homologue. Our results may inform the design of therapeutic ligands that target α6β4 nAChRs for the treatment of neuropathic pain.
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Affiliation(s)
- Arik J Hone
- MIRECC, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah 84148 United States
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072 Australia
| | | | | | | | | | - David J Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072 Australia
| | - J Michael McIntosh
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah 84148 United States
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17
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Kennedy AC, Belgi A, Husselbee BW, Spanswick D, Norton RS, Robinson AJ. α-Conotoxin Peptidomimetics: Probing the Minimal Binding Motif for Effective Analgesia. Toxins (Basel) 2020; 12:E505. [PMID: 32781580 PMCID: PMC7472027 DOI: 10.3390/toxins12080505] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/29/2020] [Accepted: 08/03/2020] [Indexed: 12/18/2022] Open
Abstract
Several analgesic α-conotoxins have been isolated from marine cone snails. Structural modification of native peptides has provided potent and selective analogues for two of its known biological targets-nicotinic acetylcholine and γ-aminobutyric acid (GABA) G protein-coupled (GABAB) receptors. Both of these molecular targets are implicated in pain pathways. Despite their small size, an incomplete understanding of the structure-activity relationship of α-conotoxins at each of these targets has hampered the development of therapeutic leads. This review scrutinises the N-terminal domain of the α-conotoxin family of peptides, a region defined by an invariant disulfide bridge, a turn-inducing proline residue and multiple polar sidechain residues, and focusses on structural features that provide analgesia through inhibition of high-voltage-activated Ca2+ channels. Elucidating the bioactive conformation of this region of these peptides may hold the key to discovering potent drugs for the unmet management of debilitating chronic pain associated with a wide range of medical conditions.
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Affiliation(s)
- Adam C. Kennedy
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia; (A.C.K.); (A.B.); (B.W.H.)
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia; (A.C.K.); (A.B.); (B.W.H.)
| | - Benjamin W. Husselbee
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia; (A.C.K.); (A.B.); (B.W.H.)
| | - David Spanswick
- Biomedicine Discovery Institute and the Department of Physiology, Monash University, Victoria 3800, Australia;
- Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
- NeuroSolutions Ltd., Coventry CV4 7AL, UK
| | - Raymond S. Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Science, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia;
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria 3052, Australia
| | - Andrea J. Robinson
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia; (A.C.K.); (A.B.); (B.W.H.)
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18
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Donvito G, Muldoon PP, Jackson KJ, Ahmad U, Zaveri NT, McIntosh JM, Chen X, Lichtman AH, Damaj MI. Neuronal nicotinic acetylcholine receptors mediate ∆ 9 -THC dependence: Mouse and human studies. Addict Biol 2020; 25:e12691. [PMID: 30378732 PMCID: PMC6509006 DOI: 10.1111/adb.12691] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 09/27/2018] [Accepted: 10/09/2018] [Indexed: 11/29/2022]
Abstract
Cessation from prolonged use of ∆9 -tetrahydrocannabinol (THC), the primary active compound responsible for the cannabimimetic effects of cannabis, results in a mild to moderate withdrawal syndrome in humans and laboratory animals. Whereas manipulations of the endogenous cannabinoid system (eg, cannabinoid receptors and endocannabinoid regulating enzymes) alter nicotine withdrawal, in this study we asked the reciprocal question. Do nicotinic acetylcholine receptors (nAChRs) modulate THC withdrawal? To assess the role of different nAChR subtypes in THC withdrawal, we used transgenic mouse, preclinical pharmacological, and human genetic correlation approaches. Our findings show that selective α3β4* nAChR antagonist, AuIB, and α3β4* nAChR partial agonist, AT-1001, dose-dependently attenuated somatic withdrawal signs in THC-dependent mice that were challenged with the cannabinoid-1 receptor antagonist rimonabant. Additionally, THC-dependent α5 and α6 nAChR knockout (KO) mice displayed decreased rimonabant precipitated somatic withdrawal signs compared with their wild-type counterparts. In contrast, β2 and α7 nAChR KO mice showed no alterations in THC withdrawal signs. Moreover, deletion of β2 nAChR did not alter the reduced expression of somatic signs by the preferred α6β4* antagonist, BulA [T5A;P60]. Finally, the human genetic association studies indicated that variations in the genes that code for the α5, α3, β4, and α6 nAChRs were associated with cannabis disorder phenotypes. Overall, these findings suggest that α3β4* and α6β4* nAChR subtypes represent viable targets for the development of medications to counteract THC dependence.
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Affiliation(s)
- Giulia Donvito
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad St., Molecular Medicine Research Building, Box 980613, Richmond, VA, 23298, USA
| | - Pretal P. Muldoon
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad St., Molecular Medicine Research Building, Box 980613, Richmond, VA, 23298, USA
| | - Kia J. Jackson
- Department of Psychiatry, Virginia Commonwealth University, 800 E. Leigh St, Biotech I, Suite 390A, Richmond, VA, 23219, USA
| | - Urslan Ahmad
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad St., Molecular Medicine Research Building, Box 980613, Richmond, VA, 23298, USA
| | - Nur T. Zaveri
- Astraea Therapeutics, LLC. 320 Logue Avenue, Mountain View, CA 94043
| | - J. Michael McIntosh
- Departments of Biology and Psychiatry, University of Utah, Salt Lake City, UT 84112, USA
| | - Xiangning Chen
- Nevada Institute of Personalized Medicine, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy. Las Vegas, NV 89154-4004
| | - Aron H. Lichtman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad St., Molecular Medicine Research Building, Box 980613, Richmond, VA, 23298, USA
| | - M. Imad Damaj
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad St., Molecular Medicine Research Building, Box 980613, Richmond, VA, 23298, USA
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19
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van Hout M, Valdes A, Christensen SB, Tran PT, Watkins M, Gajewiak J, Jensen AA, Olivera BM, McIntosh JM. α-Conotoxin VnIB from Conus ventricosus is a potent and selective antagonist of α6β4* nicotinic acetylcholine receptors. Neuropharmacology 2019; 157:107691. [PMID: 31255696 DOI: 10.1016/j.neuropharm.2019.107691] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/05/2019] [Accepted: 06/26/2019] [Indexed: 01/20/2023]
Abstract
α6-containing (α6*) nicotinic acetylcholine receptors (nAChRs) are expressed throughout the periphery and the central nervous system and constitute putative therapeutic targets in pain, addiction and movement disorders. The α6β2* nAChRs are relatively well studied, in part due to the availability of target specific α-conotoxins (α-Ctxs). In contrast, all native α-Ctxs identified that potently block α6β4 nAChRs exhibit higher potencies for the closely related α6β2β3 and/or α3β4 subtypes. In this study, we have identified a novel peptide from Conus ventricosus with pronounced selectivity for the α6β4 nAChR. The peptide-encoding gene was cloned from genomic DNA and the predicted mature peptide, α-Ctx VnIB, was synthesized. The functional properties of VnIB were characterized at rat and human nAChRs expressed in Xenopus oocytes by two-electrode voltage clamp electrophysiology. VnIB potently inhibited ACh-evoked currents at rα6β4 and rα6/α3β4 nAChRs, displayed ∼20-fold and ∼250-fold lower potencies at rα3β4 and rα6/α3β2β3 receptors, respectively, and exhibited negligible effects at eight other nAChR subtypes. Interestingly, even higher degrees of selectivity were observed for hα6/α3β4 over hα6/α3β2β3 and hα3β4 receptors. Finally, VnIB displayed fast binding kinetics at rα6/α3β4 (on-rate t½ = 0.87 min-1, off-rate t½ = 2.7 min-1). The overall preference of VnIB for β4* over β2* nAChRs is similar to the selectivity profiles of other 4/6 α-Ctxs. However, in contrast to previously identified native α-Ctxs targeting α6* nAChRs, VnIB displays pronounced selectivity for α6β4 nAChRs over both α3β4 and α6β2β3 receptors. VnIB thus represents a novel molecular probe for elucidating the physiological role and therapeutic properties of α6β4* nAChRs.
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Affiliation(s)
- Marloes van Hout
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Amanda Valdes
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Sean B Christensen
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Phuong T Tran
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Maren Watkins
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA; Department of Pathology, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Joanna Gajewiak
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | | | - J Michael McIntosh
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA; Department of Psychiatry, University of Utah, Salt Lake City, UT, 84108, USA; George E. Wahlen Veterans Affair Medical Center, Salt Lake City, UT, 84148, USA.
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20
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Hone AJ, Fisher F, Christensen S, Gajewiak J, Larkin D, Whiteaker P, McIntosh JM. PeIA-5466: A Novel Peptide Antagonist Containing Non-natural Amino Acids That Selectively Targets α3β2 Nicotinic Acetylcholine Receptors. J Med Chem 2019; 62:6262-6275. [PMID: 31194549 DOI: 10.1021/acs.jmedchem.9b00566] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Pharmacologically distinguishing α3β2 nicotinic acetylcholine receptors (nAChRs) from closely related subtypes, particularly α6β2, has been challenging due to the lack of subtype-selective ligands. We created analogs of α-conotoxin (α-Ctx) PeIA to identify ligand-receptor interactions that could be exploited to selectively increase potency and selectivity for α3β2 nAChRs. A series of PeIA analogs were synthesized by replacing amino acid residues in the second disulfide loop with standard or nonstandard residues and assessing their activity on α3β2 and α6/α3β2β3 nAChRs heterologously expressed in Xenopus laevis oocytes. Asparagine11 was found to occupy a pivotal position, and when replaced with negatively charged amino acids, selectivity for α3β2 over α6/α3β2β3 nAChRs was substantially increased. Second generation peptides were then designed to further improve both potency and selectivity. One peptide, PeIA-5466, was ∼300-fold more potent on α3β2 than α6/α3β2β3 and is the most α3β2-selective antagonist heretofore reported.
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Affiliation(s)
| | | | | | | | | | | | - J Michael McIntosh
- George E. Whalen Veterans Affairs Medical Center , Salt Lake City , Utah 84148 , United States
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21
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Turner MW, Marquart LA, Phillips PD, McDougal OM. Mutagenesis of α-Conotoxins for Enhancing Activity and Selectivity for Nicotinic Acetylcholine Receptors. Toxins (Basel) 2019; 11:E113. [PMID: 30781866 PMCID: PMC6409848 DOI: 10.3390/toxins11020113] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 02/10/2019] [Accepted: 02/11/2019] [Indexed: 02/04/2023] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are found throughout the mammalian body and have been studied extensively because of their implication in a myriad of diseases. α-Conotoxins (α-CTxs) are peptide neurotoxins found in the venom of marine snails of genus Conus. α-CTxs are potent and selective antagonists for a variety of nAChR isoforms. Over the past 40 years, α-CTxs have proven to be valuable molecular probes capable of differentiating between closely related nAChR subtypes and have contributed greatly to understanding the physiological role of nAChRs in the mammalian nervous system. Here, we review the amino acid composition and structure of several α-CTxs that selectively target nAChR isoforms and explore strategies and outcomes for introducing mutations in native α-CTxs to direct selectivity and enhance binding affinity for specific nAChRs. This review will focus on structure-activity relationship studies involving native α-CTxs that have been rationally mutated and molecular interactions that underlie binding between ligand and nAChR isoform.
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Affiliation(s)
- Matthew W Turner
- Biomolecular Sciences Graduate Programs, Boise State University; Boise, ID 83725, USA.
| | - Leanna A Marquart
- Department of Chemistry and Biochemistry, Boise State University; Boise, ID 83725, USA.
| | - Paul D Phillips
- Department of Chemistry and Biochemistry, Boise State University; Boise, ID 83725, USA.
| | - Owen M McDougal
- Department of Chemistry and Biochemistry, Boise State University; Boise, ID 83725, USA.
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22
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Liu W, Li MD. Insights Into Nicotinic Receptor Signaling in Nicotine Addiction: Implications for Prevention and Treatment. Curr Neuropharmacol 2018; 16:350-370. [PMID: 28762314 PMCID: PMC6018190 DOI: 10.2174/1570159x15666170801103009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 06/18/2017] [Accepted: 07/28/2017] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Nicotinic acetylcholine receptors (nAChRs) belong to the Cys-loop ligandgated ion-channel (LGIC) superfamily, which also includes the GABA, glycine, and serotonin receptors. Many nAChR subunits have been identified and shown to be involved in signal transduction on binding to them of either the neurotransmitter acetylcholine or exogenous ligands such as nicotine. The nAChRs are pentameric assemblies of homologous subunits surrounding a central pore that gates cation flux, and they are expressed at neuromuscular junctions throughout the nervous system. METHODS AND RESULTS Because different nAChR subunits assemble into a variety of pharmacologically distinct receptor subtypes, and different nAChRs are implicated in various physiological functions and pathophysiological conditions, nAChRs represent potential molecular targets for drug addiction and medical therapeutic research. This review intends to provide insights into recent advances in nAChR signaling, considering the subtypes and subunits of nAChRs and their roles in nicotinic cholinergic systems, including structure, diversity, functional allosteric modulation, targeted knockout mutations, and rare variations of specific subunits, and the potency and functional effects of mutations by focusing on their effects on nicotine addiction (NA) and smoking cessation (SC). Furthermore, we review the possible mechanisms of action of nAChRs in NA and SC based on our current knowledge. CONCLUSION Understanding these cellular and molecular mechanisms will lead to better translational and therapeutic operations and outcomes for the prevention and treatment of NA and other drug addictions, as well as chronic diseases, such as Alzheimer's and Parkinson's. Finally, we put forward some suggestions and recommendations for therapy and treatment of NA and other chronic diseases.
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Affiliation(s)
- Wuyi Liu
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China.,School of Biological Sciences and Food Engineering, Fuyang Normal University, Fuyang, Anuhi 236041, China
| | - Ming D Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China.,Research Center for Air Pollution and Health, Zhejiang University, Hangzhou, China.,Institute of NeuroImmune Pharmacology, Seton Hall University, South Orange, NJ, United States
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23
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Peng C, Yan Y, Kim VJ, Engle SE, Berry JN, McIntosh JM, Neve RL, Drenan RM. Gene editing vectors for studying nicotinic acetylcholine receptors in cholinergic transmission. Eur J Neurosci 2018; 50:2224-2238. [PMID: 29779223 DOI: 10.1111/ejn.13957] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/19/2018] [Accepted: 04/16/2018] [Indexed: 01/28/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs), prototype members of the cys-loop ligand-gated ion channel family, are key mediators of cholinergic transmission in the central nervous system. Despite their importance, technical gaps exist in our ability to dissect the function of individual subunits in the brain. To overcome these barriers, we designed CRISPR/Cas9 small guide RNA sequences (sgRNAs) for the production of loss-of-function alleles in mouse nAChR genes. These sgRNAs were validated in vitro via deep sequencing. We subsequently targeted candidate nAChR genes in vivo by creating herpes simplex virus (HSV) vectors delivering sgRNAs and Cas9 expression to mouse brain. The production of loss-of-function insertions or deletions (indels) by these 'all-in-one' HSV vectors was confirmed using brain slice patch clamp electrophysiology coupled with pharmacological analysis. Next, we developed a scheme for cell type-specific gene editing in mouse brain. Knockin mice expressing Cas9 in a Cre-dependent manner were validated using viral microinjections and genetic crosses to common Cre-driver mouse lines. We subsequently confirmed functional Cas9 activity by targeting the ubiquitous neuronal protein, NeuN, using adeno-associated virus (AAV) delivery of sgRNAs. Finally, the mouse β2 nAChR gene was successfully targeted in dopamine transporter (DAT)-positive neurons via CRISPR/Cas9. The sgRNA sequences and viral vectors, including our scheme for Cre-dependent gene editing, should be generally useful to the scientific research community. These tools could lead to new discoveries related to the function of nAChRs in neurotransmission and behavioral processes.
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Affiliation(s)
- Can Peng
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, 320 East Superior Street, Searle 5-450, Chicago, IL, 60611, USA
| | - Yijin Yan
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, 320 East Superior Street, Searle 5-450, Chicago, IL, 60611, USA
| | - Veronica J Kim
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, 320 East Superior Street, Searle 5-450, Chicago, IL, 60611, USA
| | - Staci E Engle
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Jennifer N Berry
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - J Michael McIntosh
- George E. Wahlen Veterans Affairs Medical Center and Departments of Psychiatry and Biology, University of Utah, Salt Lake City, UT, USA
| | - Rachael L Neve
- Gene Delivery Technology Core, Massachusetts General Hospital, Cambridge, MA, USA
| | - Ryan M Drenan
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, 320 East Superior Street, Searle 5-450, Chicago, IL, 60611, USA
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24
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Wu X, Tae HS, Huang YH, Adams DJ, Craik DJ, Kaas Q. Stoichiometry dependent inhibition of rat α3β4 nicotinic acetylcholine receptor by the ribbon isomer of α-conotoxin AuIB. Biochem Pharmacol 2018; 155:288-297. [PMID: 30009767 DOI: 10.1016/j.bcp.2018.07.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 07/11/2018] [Indexed: 11/17/2022]
Abstract
The ribbon isomer of α-conotoxin AuIB has 10-fold greater potency than the wild-type globular isomer at inhibiting nicotinic acetylcholine receptors (nAChRs) in rat parasympathetic neurons, and unlike its globular isoform, ribbon AuIB only targets a specific stoichiometry of the α3β4 nAChR subtype. Previous electrophysiological recordings of AuIB indicated that ribbon AuIB binds to the α3(+)α3(-) interface within the nAChR extracellular domain, which is displayed by the (α3)3(β4)2 stoichiometry but not by (α3)2(β4)3. This specificity for a particular stoichiometry is remarkable and suggests that ribbon isoforms of α-conotoxins might have great potential in drug design. In this study, we investigated the binding mode and structure-activity relationships of ribbon AuIB using a combination of molecular modeling and electrophysiology recording to determine the features that underpin its selectivity. An alanine scan showed that positions 4 and 9 of ribbon AuIB are the main determinants of the interaction with (α3)3(β4)2 nAChR. Our computational models indicate that the first loop of ribbon AuIB binds in the "aromatic box" of the acetylcholine orthosteric binding site, similar to that of globular AuIB. In contrast, the second loop and the termini of the ribbon isomer have different orientations and interactions in the binding sites to those of the globular isomer. The structure-activity relationships reported herein should be useful to design peptides displaying a ribbon α-conotoxin scaffold for inhibition of nAChR subtypes that have hitherto been difficult to selectively target.
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Affiliation(s)
- Xiaosa Wu
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), The University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Yen-Hua Huang
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), The University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
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25
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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: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [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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26
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Albillos A, McIntosh JM. Human nicotinic receptors in chromaffin cells: characterization and pharmacology. Pflugers Arch 2017; 470:21-27. [PMID: 29058146 DOI: 10.1007/s00424-017-2073-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/14/2017] [Accepted: 09/19/2017] [Indexed: 02/03/2023]
Abstract
During the last 10 years, we have been working on human chromaffin cells obtained from the adrenal gland of organ donors that suffered encephalic or cardiac death. We first electrophysiologically characterized the nicotinic acetylcholine receptors (nAChRs) activated by acetylcholine, and their contribution to the exocytosis of chromaffin vesicles and release of catecholamines. We have shown that these cells possess an adrenergic phenotype. This phenotype may contribute to an increased expression of α7 nAChRs in these cells, allowing for recording of α7 nAChR currents, something that had previously not been achieved in non-human species. The use of α-conotoxins allowed us to characterize non-α7 nAChR subtypes and, together with molecular biology experiments, conclude that the predominant nAChR subtype in human chromaffin cells is α3β4* (asterisk indicates the posible presence of additional subunits). In addition, there is a minor population of αxβ2 nAChRs. Both α7 and non-α7 nAChR subtypes contribute to the exocytotic process. Exocytosis mediated by nAChRs could be as large in magnitude as that elicited by calcium entry through voltage-dependent calcium channels. Finally, we have also investigated the effect of nAChR-targeted tobacco cessation drugs on catecholamine release in chromaffin cells. We have concluded that at therapeutic concentrations, varenicline alone does not increase the frequency of action potentials evoked by ACh. However, varenicline in the presence of nicotine does increase this frequency, and thus, in the presence of both drugs, the probability of increased catecholamine release in human chromaffin cells is high.
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Affiliation(s)
- Almudena Albillos
- Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, Calle Arzobispo Morcillo 4, 28029, Madrid, Spain.
| | - J Michael McIntosh
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Department of Biology, University of Utah, Salt Lake City, UT, USA.,Department of Psychiatry, University of Utah, Salt Lake City, UT, USA
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27
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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] [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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28
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Yu J, Zhu X, Yang Y, Luo S, Zhangsun D. Expression in Escherichia coli of fusion protein comprising α-conotoxin TxIB and preservation of selectivity to nicotinic acetylcholine receptors in the purified product. Chem Biol Drug Des 2017; 91:349-358. [PMID: 28891599 DOI: 10.1111/cbdd.13104] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 06/04/2017] [Accepted: 08/21/2017] [Indexed: 12/19/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels, which are widely distributed in the central and peripheral nervous system. The α6β2* nAChR is an important subtype, which is closely associated with nicotine addiction and movement disorders etc. α-conotoxin TxIB with 16-amino acid residues specifically targets α6β2* nAChR with no obvious effect on other nAChR subtypes. However, chemical synthesis of TxIB is expensive, and the quantity of native TxIB extracted from cone snail is limited. In the present study, we attempted to obtain TxIB using biological method based on the recombinant expression in Escherichia coli (E. coli). The synthetic gene encoding mature peptide of TxIB was inserted in pET-31b(+) vector and transformed into E. coli strain BLR(DE3)pLysS for expression. The recombinant fusion protein KSI-TxIB-His6 (KSI, ketosteroid isomerase) was expressed successfully as inclusion body in E. coli, which was purified by Ni-NTA affinity chromatography column and cleaved by cyanogen bromide (CNBr) to release recombinant α-conotoxin TxIB (rTxIB). Then, rTxIB was purified by reverse-phase high-performance liquid chromatography (RP-HPLC) and was identified by electrospray ionization mass spectrometry (ESI-MS). Pharmacological activity of rTxIB was assessed by electrophysiological approaches. The results indicated that it preserved about 50% of potency, but, was even more important, had the same selectivity as the natural conotoxin which may provide an alternative method for quantity production of small peptides with low cost on the premise of not changing their potency.
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Affiliation(s)
- Jinpeng Yu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China.,College of Agriculture, Hainan University, Haikou, China
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China
| | - Yang Yang
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China.,College of Agriculture, Hainan University, Haikou, China
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China
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29
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Peng C, Engle SE, Yan Y, Weera MM, Berry JN, Arvin MC, Zhao G, McIntosh JM, Chester JA, Drenan RM. Altered nicotine reward-associated behavior following α4 nAChR subunit deletion in ventral midbrain. PLoS One 2017; 12:e0182142. [PMID: 28759616 PMCID: PMC5536316 DOI: 10.1371/journal.pone.0182142] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 07/12/2017] [Indexed: 11/19/2022] Open
Abstract
Nicotinic acetylcholine receptors containing α4 subunits (α4β2* nAChRs) are critical for nicotinic cholinergic transmission and the addictive action of nicotine. To identify specific activities of these receptors in the adult mouse brain, we coupled targeted deletion of α4 nAChR subunits with behavioral and and electrophysiological measures of nicotine sensitivity. A viral-mediated Cre/lox approach allowed us to delete α4 from ventral midbrain (vMB) neurons. We used two behavioral assays commonly used to assess the motivational effects of drugs of abuse: home-cage oral self-administration, and place conditioning. Mice lacking α4 subunits in vMB consumed significantly more nicotine at the highest offered nicotine concentration (200 μg/mL) compared to control mice. Deletion of α4 subunits in vMB blocked nicotine-induced conditioned place preference (CPP) without affecting locomotor activity. Acetylcholine-evoked currents as well as nicotine-mediated increases in synaptic potentiation were reduced in mice lacking α4 in vMB. Immunostaining verified that α4 subunits were deleted from both dopamine and non-dopamine neurons in the ventral tegmental area (VTA). These results reveal that attenuation of α4* nAChR function in reward-related brain circuitry of adult animals may increase nicotine intake by enhancing the rewarding effects and/or reducing the aversive effects of nicotine.
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Affiliation(s)
- Can Peng
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Staci E. Engle
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
| | - Yijin Yan
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Marcus M. Weera
- Department of Psychological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Jennifer N. Berry
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
| | - Matthew C. Arvin
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
| | - Guiqing Zhao
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - J. Michael McIntosh
- George E. Wahlen Veterans Affairs Medical Center and Departments of Psychiatry and Biology, University of Utah, Salt Lake City, Utah, United States of America
| | - Julia A. Chester
- Department of Psychological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Ryan M. Drenan
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
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30
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Wu Y, Zhangsun D, Zhu X, Kaas Q, Zhangsun M, Harvey PJ, Craik DJ, McIntosh JM, Luo S. α-Conotoxin [S9A]TxID Potently Discriminates between α3β4 and α6/α3β4 Nicotinic Acetylcholine Receptors. J Med Chem 2017; 60:5826-5833. [PMID: 28603989 DOI: 10.1021/acs.jmedchem.7b00546] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
α3β4 nAChRs have been implicated in various pathophysiological conditions. However, the expression profile of α3β4 nAChRs and α6/α3β4 nAChRs overlap in a variety of tissues. To distinguish between these two subtypes, we redesigned peptide 1 (α-conotoxin TxID), which inhibits α3β4 and α6/α3β4 nAChR subtypes. We systematically mutated 1 to evaluate analogue selectivity for α3β4 vs α6/α3β4 nAChRs expressed in Xenopus laevis oocytes. One analogue, peptide 7 ([S9A]TxID), had 46-fold greater potency for α3β4 versus α6/α3β4 nAChRs. Peptide 7 had IC50s > 10 μM for other nAChR subtypes. Molecular dynamics simulations suggested that Ser-9 of TxID was involved in a weak hydrogen bond with β4 Lys-81 in the α6β4 binding site but not in the α3β4 binding site. When Ser-9 was substituted by an Ala, this hydrogen bond interaction was disrupted. These results provide further molecular insights into the selectivity of 7 and provide a guide for designing ligands that block α3β4 nAChRs.
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Affiliation(s)
- Yong Wu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University , Haikou, Hainan 570228 China
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University , Haikou, Hainan 570228 China
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University , Haikou, Hainan 570228 China
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - Manqi Zhangsun
- Departments of Biology and Psychiatry, University of Utah , Salt Lake City, Utah 84112, United States
| | - Peta J Harvey
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - J Michael McIntosh
- Departments of Biology and Psychiatry, University of Utah , Salt Lake City, Utah 84112, United States.,George E. Wahlen Veterans Affairs Medical Center , Salt Lake City, Utah 84108, United States
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University , Haikou, Hainan 570228 China
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31
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Dutertre S, Nicke A, Tsetlin VI. Nicotinic acetylcholine receptor inhibitors derived from snake and snail venoms. Neuropharmacology 2017. [PMID: 28623170 DOI: 10.1016/j.neuropharm.2017.06.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The nicotinic acetylcholine receptor (nAChR) represents the prototype of ligand-gated ion channels. It is vital for neuromuscular transmission and an important regulator of neurotransmission. A variety of toxic compounds derived from diverse species target this receptor and have been of elemental importance in basic and applied research. They enabled milestone discoveries in pharmacology and biochemistry ranging from the original formulation of the receptor concept, the first isolation and structural analysis of a receptor protein (the nAChR) to the identification, localization, and differentiation of its diverse subtypes and their validation as a target for therapeutic intervention. Among the venom-derived compounds, α-neurotoxins and α-conotoxins provide the largest families and still represent indispensable pharmacological tools. Application of modified α-neurotoxins provided substantial structural and functional details of the nAChR long before high resolution structures were available. α-bungarotoxin represents not only a standard pharmacological tool and label in nAChR research but also for unrelated proteins tagged with a minimal α-bungarotoxin binding motif. A major advantage of α-conotoxins is their smaller size, as well as superior selectivity for diverse nAChR subtypes that allows their development into ligands with optimized pharmacological and chemical properties and potentially novel drugs. In the following, these two groups of nAChR antagonists will be described focusing on their respective roles in the structural and functional characterization of nAChRs and their development into research tools. In addition, we provide a comparative overview of the diverse α-conotoxin selectivities that can serve as a practical guide for both structure activity studies and subtype classification. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Sébastien Dutertre
- Institut des Biomolécules Max Mousseron, UMR 5247, Université Montpellier - CNRS, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
| | - Annette Nicke
- Walther Straub Institute for Pharmacology and Toxicology, Ludwig-Maximilians-Universität, Nußbaumstr. 26, 80336 Munich, Germany.
| | - Victor I Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str.16/10, Moscow 117999, Russian Federation
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Jareczek FJ, White SR, Hammond DL. Plasticity in Brainstem Mechanisms of Pain Modulation by Nicotinic Acetylcholine Receptors in the Rat. eNeuro 2017; 4:ENEURO.0364-16.2017. [PMID: 28197544 PMCID: PMC5286660 DOI: 10.1523/eneuro.0364-16.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 01/03/2023] Open
Abstract
Individuals with chronic pain may be driven to smoke more because the analgesic efficacy of nicotine diminishes. To determine whether persistent pain diminishes the actions of a nicotinic acetylcholine receptor (nAChR) agonist in pain modulatory pathways, we examined the effects of epibatidine in the rostral ventromedial medulla (RVM) of rats with and without inflammatory injury induced by intraplantar injection of complete Freund's adjuvant (CFA). In uninjured rats, epibatidine produced a dose-dependent antinociception that was completely blocked by dihydro-β-erythroidine (DHβE; α4β2 antagonist) and partially blocked by methyllycaconitine (MLA; α7 antagonist). Epibatidine reversed heat hyperalgesia when microinjected in the RVM 4 h, 4 d, or 2 weeks after CFA treatment. Although DHβE completely blocked epibatidine's antihyperalgesic effect at 4 h, at 2 weeks it elicited only partial antagonism. Methyllycaconitine was ineffective at both time points. Epibatidine's antinociceptive efficacy in the uninjured hind paw progressively declined, and it was without effect 2 weeks after CFA. Moreover, as early as 4 h after CFA, the antinociceptive effect of epibatidine was no longer antagonized by DHβE. Neither antagonist alone altered paw withdrawal latency in uninjured or CFA-treated rats, suggesting that neither α4β2 nor α7 nAChRs are tonically active in the RVM. The Bmax and Kd of α4β2 nAChRs in the RVM were unchanged after CFA treatment. These observations provide the first evidence of pharmacological plasticity of the actions of α4β2 nAChR agonists in a critical brainstem pain modulatory pathway and may in part explain why people with chronic pain smoke more than the general population.
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Affiliation(s)
- Francis J. Jareczek
- Medical Scientist Training Program, University of Iowa, Iowa City, IA 52242
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242
| | | | - Donna L. Hammond
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242
- Department of Anesthesia, University of Iowa, Iowa City, IA 52242
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242
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Hone AJ, Michael McIntosh J, Rueda-Ruzafa L, Passas J, de Castro-Guerín C, Blázquez J, González-Enguita C, Albillos A. Therapeutic concentrations of varenicline in the presence of nicotine increase action potential firing in human adrenal chromaffin cells. J Neurochem 2016; 140:37-52. [PMID: 27805736 DOI: 10.1111/jnc.13883] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 10/20/2016] [Accepted: 10/27/2016] [Indexed: 01/13/2023]
Abstract
Varenicline is a nicotinic acetylcholine receptor (nAChR) agonist used to treat nicotine addiction, but a live debate persists concerning its mechanism of action in reducing nicotine consumption. Although initially reported as α4β2 selective, varenicline was subsequently shown to activate other nAChR subtypes implicated in nicotine addiction including α3β4. However, it remains unclear whether activation of α3β4 nAChRs by therapeutically relevant concentrations of varenicline is sufficient to affect the behavior of cells that express this subtype. We used patch-clamp electrophysiology to assess the effects of varenicline on native α3β4* nAChRs (asterisk denotes the possible presence of other subunits) expressed in human adrenal chromaffin cells and compared its effects to those of nicotine. Varenicline and nicotine activated α3β4* nAChRs with EC50 values of 1.8 (1.2-2.7) μM and 19.4 (11.1-33.9) μM, respectively. Stimulation of adrenal chromaffin cells with 10 ms pulses of 300 μM acetylcholine (ACh) in current-clamp mode evoked sodium channel-dependent action potentials (APs). Under these conditions, perfusion of 50 or 100 nM varenicline showed very little effect on AP firing compared to control conditions (ACh stimulation alone), but at higher concentrations (250 nM) varenicline increased the number of APs fired up to 436 ± 150%. These results demonstrate that therapeutic concentrations of varenicline are unlikely to alter AP firing in chromaffin cells. In contrast, nicotine showed no effect on AP firing at any of the concentrations tested (50, 100, 250, and 500 nM). However, perfusion of 50 nM nicotine simultaneously with 100 nM varenicline increased AP firing by 290 ± 104% indicating that exposure to varenicline and nicotine concurrently may alter cellular behavior such as excitability and neurotransmitter release.
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Affiliation(s)
- Arik J Hone
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain.,Departments of Biology, University of Utah, Salt Lake City, Utah, USA
| | - J Michael McIntosh
- Departments of Biology, University of Utah, Salt Lake City, Utah, USA.,Psychiatry, University of Utah, Salt Lake City, Utah, USA.,The George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, USA
| | - Lola Rueda-Ruzafa
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain
| | | | | | | | | | - Almudena Albillos
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain
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Barloscio D, Cerri E, Domenici L, Longhi R, Dallanoce C, Moretti M, Vilella A, Zoli M, Gotti C, Origlia N. In vivo study of the role of α6-containing nicotinic acetylcholine receptor in retinal function using subtype-specific RDP-MII(E11R) toxin. FASEB J 2016; 31:192-202. [PMID: 27682206 DOI: 10.1096/fj.201600855r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/16/2016] [Indexed: 02/05/2023]
Abstract
Although α6-contaning (α6*) nicotinic acetylcholine receptors (nAChRs) are densely expressed in the visual system, their role is not well known. We have characterized a family of toxins that are antagonists for α6β2* receptors and used one of these [RDP-MII(E11R)] to localize α6* nAChRs and investigate their impact on retinal function in adult Long-Evans rats. The α6*nAChRs in retinal tissue were localized using either a fluorescently tagged [RDP-MII(E11R)] or anti-α6-specific antibodies and found to be predominantly at the level of the ganglion cell layer. After intraocular injection of RDP-MII(E11R) in one eye and vehicle or inactive MII in contralateral eyes as controls, we recorded flash electroretinograms (F-ERGs), pattern ERGs (P-ERGs), and cortical visual-evoked potential (VEPs). There was no significant difference in F-ERG between the RDP-MII(E11R)-treated and control eyes. In contrast, P-ERG response amplitude was significantly reduced in the RDP-MII(E11R)-injected eye. Blocking α6* nAChRs at retinal level also decreased the VEP amplitude recorded in the visual cortex contralateral to the injected eye. Because both the cortical and inner retina output were affected by RDP-MII(E11R), whereas photoreceptor output was preserved, we conclude that the reduced visual response was due to an alteration in the function of α6* nAChRs present in the ganglion cell layer.-Barloscio, D., Cerri, E., Domenici, L., Longhi, R., Dallanoce, C., Moretti, M., Vilella, A., Zoli, M., Gotti, C., and Origlia, N. In vivo study of the role of α6-containing nicotinic acetylcholine receptor in retinal function using subtype-specific RDP-MII(E11R) toxin.
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Affiliation(s)
- Davide Barloscio
- National Research Council (CNR) Neuroscience Institute-Pisa, Pisa, Italy
| | - Elisa Cerri
- National Research Council (CNR) Neuroscience Institute-Pisa, Pisa, Italy
| | - Luciano Domenici
- National Research Council (CNR) Neuroscience Institute-Pisa, Pisa, Italy
| | - Renato Longhi
- CNR Institute of Chemistry of Molecular Recognition, Milan, Italy
| | - Clelia Dallanoce
- Department of Pharmaceutical Sciences, Section of Medicinal Chemistry "Pietro Pratesi," University of Milan, Milan, Italy
| | - Milena Moretti
- CNR Neuroscience Institute-Milano, Biometra University of Milan, Milan, Italy; and
| | - Antonietta Vilella
- Center for Neuroscience and Neurotechnology, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Michele Zoli
- Center for Neuroscience and Neurotechnology, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Cecilia Gotti
- CNR Neuroscience Institute-Milano, Biometra University of Milan, Milan, Italy; and
| | - Nicola Origlia
- National Research Council (CNR) Neuroscience Institute-Pisa, Pisa, Italy;
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Rodrigues RJ, Almeida T, Díaz-Hernández M, Marques JM, Franco R, Solsona C, Miras-Portugal MT, Ciruela F, Cunha RA. Presynaptic P2X1-3 and α3-containing nicotinic receptors assemble into functionally interacting ion channels in the rat hippocampus. Neuropharmacology 2016; 105:241-257. [PMID: 26801076 DOI: 10.1016/j.neuropharm.2016.01.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 12/20/2015] [Accepted: 01/18/2016] [Indexed: 01/10/2023]
Abstract
Previous studies documented a cross-talk between purinergic P2X (P2XR) and nicotinic acetylcholine receptors (nAChR) in heterologous expression systems and peripheral preparations. We now investigated if this occurred in native brain preparations and probed its physiological function. We found that P2XR and nAChR were enriched in hippocampal terminals, where both P2X1-3R and α3, but not α4, nAChR subunits were located in the active zone and in dopamine-β-hydroxylase-positive hippocampal terminals. Notably, P2XR ligands displaced nAChR binding and nAChR ligands displaced P2XR binding to hippocampal synaptosomes. In addition, a negative P2XR/nAChR cross-talk was observed in the control of the evoked release of noradrenaline from rat hippocampal synaptosomes, characterized by a less-than-additive facilitatory effect upon co-activation of both receptors. This activity-dependent cross-inhibition was confirmed in Xenopus oocytes transfected with P2X1-3Rs and α3β2 (but not α4β2) nAChR. Besides, P2X2 co-immunoprecipitated α3β2 (but not α4β2) nAChR, both in HEK cells and rat hippocampal membranes indicating that this functional interaction is supported by a physical association between P2XR and nAChR. Moreover, eliminating extracellular ATP with apyrase in hippocampal slices promoted the inhibitory effect of the nAChR antagonist tubocurarine on noradrenaline release induced by high- but not low-frequency stimulation. Overall, these results provide integrated biochemical, pharmacological and functional evidence showing that P2X1-3R and α3β2 nAChR are physically and functionally interconnected at the presynaptic level to control excessive noradrenergic terminal activation upon intense synaptic firing in the hippocampus.
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Affiliation(s)
- Ricardo J Rodrigues
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Portugal.
| | - Teresa Almeida
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Portugal; Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, 08028, Spain; Department of Pathology and Experimental Therapeutics, Faculty of Medicine, IDIBELL, University of Barcelona, 08907, Spain
| | - Miguel Díaz-Hernández
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary, Complutense University of Madrid, 28040, Spain
| | - Joana M Marques
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Portugal
| | - Rafael Franco
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, 08028, Spain; CIBERNED, Centro de Investigación en Red, Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, Madrid, Spain
| | - Carles Solsona
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine, IDIBELL, University of Barcelona, 08907, Spain
| | - María Teresa Miras-Portugal
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary, Complutense University of Madrid, 28040, Spain
| | - Francisco Ciruela
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine, IDIBELL, University of Barcelona, 08907, Spain; Department of Physiology, Faculty of Sciences, University of Ghent, B-9000, Belgium
| | - Rodrigo A Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Portugal; Faculty of Medicine, University of Coimbra, 3004-504, Portugal
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Shih PY, McIntosh JM, Drenan RM. Nicotine Dependence Reveals Distinct Responses from Neurons and Their Resident Nicotinic Receptors in Medial Habenula. Mol Pharmacol 2015; 88:1035-44. [PMID: 26429939 DOI: 10.1124/mol.115.101444] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 09/30/2015] [Indexed: 01/22/2023] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are the molecular target of nicotine. nAChRs in the medial habenula (MHb) have recently been shown to play a role in nicotine dependence, but it is not clear which nAChR subtypes or MHb neuron types are most important. To identify MHb nAChRs and/or cell types that play a role in nicotine dependence, we studied these receptors and cells with brain slice electrophysiology using both acute and chronic nicotine application. Cells in the ventroinferior (MHbVI) and ventrolateral MHb (MHbVL) subregions expressed functional nAChRs with different pharmacology. Further, application of nicotine to cells in these subregions led to different action potential firing patterns. The latter result was correlated with a differing ability of nicotine to induce nAChR desensitization. Chronic nicotine caused functional upregulation of nAChRs selectively in MHbVI cells, but did not change nAChR function in MHbVL. Importantly, firing responses were also differentially altered in these subregions following chronic nicotine. MHbVI neurons treated chronically with nicotine exhibited enhanced basal pacemaker firing but a blunted nicotine-induced firing response. MHbVL neurons did not change their firing properties in response to chronic nicotine. Together, these results suggest that acute and chronic nicotine differentially affect nAChR function and output of cells in MHb subregions. Because the MHb extensively innervates the interpeduncular nucleus, an area critical for both affective and somatic signs of withdrawal, these results could reflect some of the neurophysiological changes thought to occur in the MHb to the interpeduncular nucleus circuit in human smokers.
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Affiliation(s)
- Pei-Yu Shih
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (P.-Y.S., R.M.D.) and George E. Wahlen Veterans Affairs Medical Center and Departments of Psychiatry and Biology, University of Utah, Salt Lake City, Utah (J.M.M.)
| | - J Michael McIntosh
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (P.-Y.S., R.M.D.) and George E. Wahlen Veterans Affairs Medical Center and Departments of Psychiatry and Biology, University of Utah, Salt Lake City, Utah (J.M.M.)
| | - Ryan M Drenan
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (P.-Y.S., R.M.D.) and George E. Wahlen Veterans Affairs Medical Center and Departments of Psychiatry and Biology, University of Utah, Salt Lake City, Utah (J.M.M.)
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37
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Hone AJ, McIntosh JM, Azam L, Lindstrom J, Lucero L, Whiteaker P, Passas J, Blázquez J, Albillos A. α-Conotoxins Identify the α3β4* Subtype as the Predominant Nicotinic Acetylcholine Receptor Expressed in Human Adrenal Chromaffin Cells. Mol Pharmacol 2015; 88:881-93. [PMID: 26330550 DOI: 10.1124/mol.115.100982] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 08/31/2015] [Indexed: 01/17/2023] Open
Abstract
Ligands that selectively inhibit human α3β2 and α6β2 nicotinic acetylcholine receptor (nAChRs) and not the closely related α3β4 and α6β4 subtypes are lacking. Current α-conotoxins (α-Ctxs) that discriminate among these nAChR subtypes in rat fail to discriminate among the human receptor homologs. In this study, we describe the development of α-Ctx LvIA(N9R,V10A) that is 3000-fold more potent on oocyte-expressed human α3β2 than α3β4 and 165-fold more potent on human α6/α3β2β3 than α6/α3β4 nAChRs. This analog was used in conjuction with three other α-Ctx analogs and patch-clamp electrophysiology to characterize the nAChR subtypes expressed by human adrenal chromaffin cells. LvIA(N9R,V10A) showed little effect on the acetylcholine-evoked currents in these cells at concentrations expected to inhibit nAChRs with β2 ligand-binding sites. In contrast, the β4-selective α-Ctx BuIA(T5A,P6O) inhibited >98% of the acetylcholine-evoked current, indicating that most of the heteromeric receptors contained β4 ligand-binding sites. Additional studies using the α6-selective α-Ctx PeIA(A7V,S9H,V10A,N11R,E14A) indicated that the predominant heteromeric nAChR expressed by human adrenal chromaffin cells is the α3β4* subtype (asterisk indicates the possible presence of additional subunits). This conclusion was supported by polymerase chain reaction experiments of human adrenal medulla gland and of cultured human adrenal chromaffin cells that demonstrated prominent expression of RNAs for α3, α5, α7, β2, and β4 subunits and a low abundance of RNAs for α2, α4, α6, and α10 subunits.
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Affiliation(s)
- Arik J Hone
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain (A.J.H., A.A.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M., L.A.); George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.); Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania (J.L.); Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona (L.L., P.W.); Hospital Doce de Octubre, Madrid, Spain (J.P.); and Hospital Clínico San Carlos Madrid, Spain (J.B.)
| | - J Michael McIntosh
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain (A.J.H., A.A.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M., L.A.); George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.); Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania (J.L.); Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona (L.L., P.W.); Hospital Doce de Octubre, Madrid, Spain (J.P.); and Hospital Clínico San Carlos Madrid, Spain (J.B.)
| | - Layla Azam
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain (A.J.H., A.A.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M., L.A.); George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.); Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania (J.L.); Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona (L.L., P.W.); Hospital Doce de Octubre, Madrid, Spain (J.P.); and Hospital Clínico San Carlos Madrid, Spain (J.B.)
| | - Jon Lindstrom
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain (A.J.H., A.A.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M., L.A.); George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.); Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania (J.L.); Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona (L.L., P.W.); Hospital Doce de Octubre, Madrid, Spain (J.P.); and Hospital Clínico San Carlos Madrid, Spain (J.B.)
| | - Linda Lucero
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain (A.J.H., A.A.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M., L.A.); George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.); Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania (J.L.); Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona (L.L., P.W.); Hospital Doce de Octubre, Madrid, Spain (J.P.); and Hospital Clínico San Carlos Madrid, Spain (J.B.)
| | - Paul Whiteaker
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain (A.J.H., A.A.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M., L.A.); George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.); Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania (J.L.); Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona (L.L., P.W.); Hospital Doce de Octubre, Madrid, Spain (J.P.); and Hospital Clínico San Carlos Madrid, Spain (J.B.)
| | - Juan Passas
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain (A.J.H., A.A.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M., L.A.); George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.); Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania (J.L.); Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona (L.L., P.W.); Hospital Doce de Octubre, Madrid, Spain (J.P.); and Hospital Clínico San Carlos Madrid, Spain (J.B.)
| | - Jesús Blázquez
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain (A.J.H., A.A.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M., L.A.); George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.); Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania (J.L.); Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona (L.L., P.W.); Hospital Doce de Octubre, Madrid, Spain (J.P.); and Hospital Clínico San Carlos Madrid, Spain (J.B.)
| | - Almudena Albillos
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain (A.J.H., A.A.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M., L.A.); George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.); Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania (J.L.); Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona (L.L., P.W.); Hospital Doce de Octubre, Madrid, Spain (J.P.); and Hospital Clínico San Carlos Madrid, Spain (J.B.)
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Berry JN, Engle SE, McIntosh JM, Drenan RM. α6-Containing nicotinic acetylcholine receptors in midbrain dopamine neurons are poised to govern dopamine-mediated behaviors and synaptic plasticity. Neuroscience 2015. [PMID: 26210579 DOI: 10.1016/j.neuroscience.2015.07.052] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Acetylcholine (ACh) acts through nicotinic and muscarinic ACh receptors in the ventral midbrain and striatal areas to influence dopamine (DA) transmission. This cholinergic control of DA transmission is important for processes such as attention and motivated behavior, and is manipulated by nicotine in tobacco products. Identifying and characterizing the key ACh receptors involved in cholinergic control of DA transmission could lead to small molecule therapeutics for treating disorders involving attention, addiction, Parkinson's disease, and schizophrenia. α6-Containing nicotinic acetylcholine receptors (nAChRs) are highly and specifically expressed in midbrain DA neurons, making them an attractive drug target. Here, we used genetic, pharmacological, behavioral, and biophysical approaches to study this nAChR subtype. For many experiments, we used mice expressing mutant α6 nAChRs ("α6L9S" mice) that increase the sensitivity of these receptors to agonists such as ACh and nicotine. Taking advantage of a simple behavioral phenotype exhibited by α6L9S mice, we compared the ability of full versus partial α6(∗) nAChR agonists to activate α6(∗) nAChRs in vivo. Using local infusions of both agonists and antagonists into the brain, we demonstrate that neurons and nAChRs in the midbrain are sufficient to account for this behavioral response. To complement these behavioral studies, we studied the ability of in vivo α6(∗) nAChR activation to support plasticity changes in midbrain DA neurons that are relevant to behavioral sensitization and addiction. By coupling local infusion of drugs and brain slice patch-clamp electrophysiology, we show that activating α6(∗) nAChRs in midbrain DA areas is sufficient to enhance glutamatergic transmission in ventral tegmental area (VTA) DA neurons. Together, these results from in vivo studies strongly suggest that α6(∗) nAChRs expressed by VTA DA neurons are positioned to strongly influence both DA-mediated behaviors and the induction of synaptic plasticity by nicotine.
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Affiliation(s)
- J N Berry
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - S E Engle
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - J M McIntosh
- George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, UT 84148, USA; Departments of Biology and Psychiatry, University of Utah, Salt Lake City, UT 84148, USA
| | - R M Drenan
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA.
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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] [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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40
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Cadmium increases the sensitivity of adolescent female mice to nicotine-related behavioral deficits. Behav Neurol 2014; 2014:360978. [PMID: 25477708 PMCID: PMC4247978 DOI: 10.1155/2014/360978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 10/22/2014] [Indexed: 11/29/2022] Open
Abstract
This study investigates spatial and nonspatial working memory, anxiety related behavior, and motor activities in cadmium and/or nicotine exposed female adolescent mice. P28 female adolescent mice (albino strain) were divided into four groups of five (n = 5) mice each. A set of mice (Nic) received subcutaneous nicotine (2.0 mg/kg) while a separate set (Cd) was treated with 2.0 mg/kg cadmium (subcutaneous). For the combined treatments of cadmium and nicotine, we administered 2.0 mg/kg Nicotine and 2.0 mg/kg of Cd. Subsequently, a separate group of animals (n = 5; control) received normal saline. The total duration of treatment for all groups was 28 days (P28–P56). At P56, the treatment was discontinued, after which the animals were examined in behavioural tests. Nicotine and cadmium increased the metabolism and food intake in the female adolescent mice. This also corresponded to an increase in weight when compared with the control. However, a combined nicotine-cadmium treatment induced a decline in weight of the animals versus the control. Also, nicotine administration increased the motor function, while cadmium and nicotine-cadmium treatment caused a decline in motor activity. Both nicotine and cadmium induced a reduction in memory index; however, nicotine-cadmium treatment induced the most significant decrease in nonspatial working memory.
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41
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Engle SE, McIntosh JM, Drenan RM. Nicotine and ethanol cooperate to enhance ventral tegmental area AMPA receptor function via α6-containing nicotinic receptors. Neuropharmacology 2014; 91:13-22. [PMID: 25484253 DOI: 10.1016/j.neuropharm.2014.11.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 11/11/2014] [Accepted: 11/22/2014] [Indexed: 01/16/2023]
Abstract
Nicotine + ethanol co-exposure results in additive and/or synergistic effects in the ventral tegmental area (VTA) to nucleus accumbens (NAc) dopamine (DA) pathway, but the mechanisms supporting this are unclear. We tested the hypothesis that nAChRs containing α6 subunits (α6* nAChRs) are involved in the response to nicotine + ethanol co-exposure. Exposing VTA slices from C57BL/6 WT animals to drinking-relevant concentrations of ethanol causes a marked enhancement of α-amino-3-hydroxy-5-methyl-isoxazolepropionic acid (AMPA) receptor (AMPAR) function in VTA neurons. This effect was sensitive to α-conotoxin MII (an α6β2* nAChR antagonist), suggesting that α6* nAChR function is required. In mice expressing hypersensitive α6* nAChRs (α6L9S mice), we found that lower concentrations (relative to C57BL/6 WT) of ethanol were sufficient to enhance AMPAR function in VTA neurons. Exposure of live C57BL/6 WT mice to ethanol also produced AMPAR functional enhancement in VTA neurons, and studies in α6L9S mice strongly suggest a role for α6* nAChRs in this response. We then asked whether nicotine and ethanol cooperate to enhance VTA AMPAR function. We identified low concentrations of nicotine and ethanol that were capable of strongly enhancing VTA AMPAR function when co-applied to slices, but that did not enhance AMPAR function when applied alone. This effect was sensitive to both varenicline (an α4β2* and α6β2* nAChR partial agonist) and α-conotoxin MII. Finally, nicotine + ethanol co-exposure also enhanced AMPAR function in VTA neurons from α6L9S mice. Together, these data identify α6* nAChRs as important players in the response to nicotine + ethanol co-exposure in VTA neurons.
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Affiliation(s)
- Staci E Engle
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - J Michael McIntosh
- George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, UT 84148, USA; Departments of Psychiatry and Biology, University of Utah, Salt Lake City, UT 84148, USA
| | - Ryan M Drenan
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA.
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42
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Heghinian MD, Mejia M, Adams DJ, Godenschwege TA, Marí F. Inhibition of cholinergic pathways in Drosophila melanogaster by α-conotoxins. FASEB J 2014; 29:1011-8. [PMID: 25466886 DOI: 10.1096/fj.14-262733] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) play a pivotal role in synaptic transmission of neuronal signaling pathways and are fundamentally involved in neuronal disorders, including Alzheimer's disease, Parkinson's disease, and schizophrenia. In vertebrates, cholinergic pathways can be selectively inhibited by α-conotoxins; we show that in the model organism Drosophila, the cholinergic component of the giant fiber system is inhibited by α-conotoxins MII, AuIB, BuIA, EI, PeIA, and ImI. The injection of 45 pmol/fly of each toxin dramatically decreases the response of the giant fiber to dorsal longitudinal muscle (GF-DLM) connection to 20 ± 13.9% for MII; 26 ± 13.7% for AuIB, 12 ± 9.9% for BuIA, 30 ± 11.3% for EI, 1 ± 1% for PeIA, and 34 ± 15.4% for ImI. Through bioassay-guided fractionation of the venom of Conus brunneus, we found BruIB, an α-conotoxin that inhibits Drosophila nicotinic receptors but not its vertebrate counterparts. GF-DLM responses decreased to 43.7 ± 8.02% on injection of 45 pmol/fly of BruIB. We manipulated the Dα7 nAChR to mimic the selectivity of its vertebrate counterpart by placing structurally guided point mutations in the conotoxin-binding site. This manipulation rendered vertebrate-like behavior in the Drosophila system, enhancing the suitability of Drosophila as an in vivo tool to carry out studies related to human neuronal diseases. .
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Affiliation(s)
- Mari D Heghinian
- *Department of Chemistry and Biochemistry and Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, USA; and Health Innovations Research Institute, RMIT University, Melbourne, Victoria, Australia
| | - Monica Mejia
- *Department of Chemistry and Biochemistry and Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, USA; and Health Innovations Research Institute, RMIT University, Melbourne, Victoria, Australia
| | - David J Adams
- *Department of Chemistry and Biochemistry and Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, USA; and Health Innovations Research Institute, RMIT University, Melbourne, Victoria, Australia
| | - Tanja A Godenschwege
- *Department of Chemistry and Biochemistry and Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, USA; and Health Innovations Research Institute, RMIT University, Melbourne, Victoria, Australia
| | - Frank Marí
- *Department of Chemistry and Biochemistry and Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, USA; and Health Innovations Research Institute, RMIT University, Melbourne, Victoria, Australia
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43
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Wang J, Kuryatov A, Lindstrom J. Expression of cloned α6* nicotinic acetylcholine receptors. Neuropharmacology 2014; 96:194-204. [PMID: 25446669 DOI: 10.1016/j.neuropharm.2014.10.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 09/19/2014] [Accepted: 10/07/2014] [Indexed: 10/24/2022]
Abstract
Nicotinic acetylcholine receptors (AChRs) are ACh-gated ion channels formed from five homologous subunits in subtypes defined by their subunit composition and stoichiometry. Some subtypes readily produce functional AChRs in Xenopus oocytes and transfected cell lines. α6β2β3* AChRs (subtypes formed from these subunits and perhaps others) are not easily expressed. This may be because the types of neurons in which they are expressed (typically dopaminergic neurons) have unique chaperones for assembling α6β2β3* AChRs, especially in the presence of the other AChR subtypes. Because these relatively minor brain AChR subtypes are of major importance in addiction to nicotine, it is important for drug development as well as investigation of their functional properties to be able to efficiently express human α6β2β3* AChRs. We review the issues and progress in expressing α6* AChRs. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Affiliation(s)
- Jingyi Wang
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Alexander Kuryatov
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Jon Lindstrom
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
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44
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Jensen AB, Hoestgaard-Jensen K, Jensen AA. Pharmacological characterisation of α6β4⁎ nicotinic acetylcholine receptors assembled from three chimeric α6/α3 subunits in tsA201 cells. Eur J Pharmacol 2014; 740:703-13. [DOI: 10.1016/j.ejphar.2014.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 05/19/2014] [Accepted: 06/01/2014] [Indexed: 02/05/2023]
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45
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Brunzell DH, McIntosh JM, Papke RL. Diverse strategies targeting α7 homomeric and α6β2* heteromeric nicotinic acetylcholine receptors for smoking cessation. Ann N Y Acad Sci 2014; 1327:27-45. [PMID: 24730978 DOI: 10.1111/nyas.12421] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Preclinical studies suggest that a diversity of nicotinic acetylcholine receptors (nAChRs) with different sensitivities to nicotine may contribute to tobacco addiction. Using rodent intravenous nicotine self-administration as a preclinical model with good predictive validity for therapeutic efficacy for tobacco cessation, investigators have identified heteromeric α6β2* and homomeric α7 nAChRs as promising novel therapeutic targets to promote smoking abstinence (*denotes possible assembly with other subunits). The data suggest that diverse strategies that target these subclasses of nAChRs, namely inhibition of α6β2* nAChRs and stimulation of α7 nAChRs, will support tobacco cessation. α6β2* nAChRs, members of the high-affinity family of β2* nAChRs, function similarly to α4β2* nAChRs, the primary target of the FDA-approved drug varenicline, but have a much more selective neuroanatomical pattern of expression in catecholaminergic nuclei. Although activation of β2* nAChRs facilitates nicotine self-administration, stimulation of α7 nAChRs appears to negatively modulate both nicotine reinforcement and β2* nAChR function in the mesolimbic dopamine system. Although challenges and caveats must be considered in the development of therapeutics that target these nAChR subpopulations, an accumulation of data suggests that α7 nAChR agonists, partial agonists, or positive allosteric modulators and α6β2* nAChR antagonists, partial agonists, or negative allosteric modulators may prove to be effective therapeutics for tobacco cessation.
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Affiliation(s)
- Darlene H Brunzell
- Department of Pharmacology and Toxicology, Interdisciplinary Neuroscience Program and Institute for Drug and Alcohol Studies, Virginia Commonwealth University School of Medicine, Richmond, Virginia
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46
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Monkey adrenal chromaffin cells express α6β4* nicotinic acetylcholine receptors. PLoS One 2014; 9:e94142. [PMID: 24727685 PMCID: PMC3984115 DOI: 10.1371/journal.pone.0094142] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 03/14/2014] [Indexed: 01/02/2023] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) that contain α6 and β4 subunits have been demonstrated functionally in human adrenal chromaffin cells, rat dorsal root ganglion neurons, and on noradrenergic terminals in the hippocampus of adolescent mice. In human adrenal chromaffin cells, α6β4* nAChRs (the asterisk denotes the possible presence of additional subunits) are the predominant subtype whereas in rodents, the predominant nAChR is the α3β4* subtype. Here we present molecular and pharmacological evidence that chromaffin cells from monkey (Macaca mulatta) also express α6β4* receptors. PCR was used to show the presence of transcripts for α6 and β4 subunits and pharmacological characterization was performed using patch-clamp electrophysiology in combination with α-conotoxins that target the α6β4* subtype. Acetylcholine-evoked currents were sensitive to inhibition by BuIA[T5A,P6O] and MII[H9A,L15A]; α-conotoxins that inhibit α6-containing nAChRs. Two additional agonists were used to probe for the expression of α7 and β2-containing nAChRs. Cells with currents evoked by acetylcholine were relatively unresponsive to the α7-selctive agonist choline but responded to the agonist 5-I-A-85380. These studies provide further insights into the properties of natively expressed α6β4* nAChRs.
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47
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Chang YP, Banerjee J, Dowell C, Wu J, Gyanda R, Houghten RA, Toll L, McIntosh JM, Armishaw CJ. Discovery of a potent and selective α3β4 nicotinic acetylcholine receptor antagonist from an α-conotoxin synthetic combinatorial library. J Med Chem 2014; 57:3511-21. [PMID: 24649848 PMCID: PMC4358631 DOI: 10.1021/jm500183r] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
α-Conotoxins are disulfide-rich peptide neurotoxins that selectively inhibit neuronal nicotinic acetylcholine receptors (nAChRs). The α3β4 nAChR subtype has been identified as a novel target for managing nicotine addiction. Using a mixture-based positional-scanning synthetic combinatorial library (PS-SCL) with the α4/4-conotoxin BuIA framework, we discovered a highly potent and selective α3β4 nAChR antagonist. The initial PS-SCL consisted of a total of 113 379 904 sequences that were screened for α3β4 nAChR inhibition, which facilitated the design and synthesis of a second generation library of 64 individual α-conotoxin derivatives. Eleven analogues were identified as α3β4 nAChR antagonists, with TP-2212-59 exhibiting the most potent antagonistic activity and selectivity over the α3β2 and α4β2 nAChR subtypes. Final electrophysiological characterization demonstrated that TP-2212-59 inhibited acetylcholine evoked currents in α3β4 nAChRs heterogeneously expressed in Xenopus laevis oocytes with a calculated IC50 of 2.3 nM and exhibited more than 1000-fold selectivity over the α3β2 and α7 nAChR subtypes. As such, TP-2212-59 is among the most potent α3β4 nAChRs antagonists identified to date and further demonstrates the utility of mixture-based combinatorial libraries in the discovery of novel α-conotoxin derivatives with refined pharmacological activity.
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Affiliation(s)
- Yi-Pin Chang
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
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48
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Wang Y, Lee JW, Oh G, Grady SR, McIntosh JM, Brunzell DH, Cannon JR, Drenan RM. Enhanced synthesis and release of dopamine in transgenic mice with gain-of-function α6* nAChRs. J Neurochem 2013; 129:315-27. [PMID: 24266758 DOI: 10.1111/jnc.12616] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 11/19/2013] [Accepted: 11/19/2013] [Indexed: 12/21/2022]
Abstract
α6β2* nicotinic acetylcholine receptors (nAChRs)s in the ventral tegmental area to nucleus accumbens (NAc) pathway are implicated in the response to nicotine, and recent work suggests these receptors play a role in the rewarding action of ethanol. Here, we studied mice expressing gain-of-function α6β2* nAChRs (α6L9'S mice) that are hypersensitive to nicotine and endogenous acetylcholine. Evoked extracellular dopamine (DA) levels were enhanced in α6L9'S NAc slices compared to control, non-transgenic (non-Tg) slices. Extracellular DA levels in both non-Tg and α6L9'S slices were further enhanced in the presence of GBR12909, suggesting intact DA transporter function in both mouse strains. Ongoing α6β2* nAChR activation by acetylcholine plays a role in enhancing DA levels, as α-conotoxin MII completely abolished evoked DA release in α6L9'S slices and decreased spontaneous DA release from striatal synaptosomes. In HPLC experiments, α6L9'S NAc tissue contained significantly more DA, 3,4-dihydroxyphenylacetic acid, and homovanillic acid compared to non-Tg NAc tissue. Serotonin (5-HT), 5-hydroxyindoleacetic acid, and norepinephrine (NE) were unchanged in α6L9'S compared to non-Tg tissue. Western blot analysis revealed increased tyrosine hydroxylase expression in α6L9'S NAc. Overall, these results show that enhanced α6β2* nAChR activity in NAc can stimulate DA production and lead to increased extracellular DA levels.
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Affiliation(s)
- Yuexiang Wang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
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49
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Smith NJ, Hone AJ, Memon T, Bossi S, Smith TE, McIntosh JM, Olivera BM, Teichert RW. Comparative functional expression of nAChR subtypes in rodent DRG neurons. Front Cell Neurosci 2013; 7:225. [PMID: 24348328 PMCID: PMC3842599 DOI: 10.3389/fncel.2013.00225] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 11/03/2013] [Indexed: 11/13/2022] Open
Abstract
We investigated the functional expression of nicotinic acetylcholine receptors (nAChRs) in heterogeneous populations of dissociated rat and mouse lumbar dorsal root ganglion (DRG) neurons by calcium imaging. By this experimental approach, it is possible to investigate the functional expression of multiple receptor and ion-channel subtypes across more than 100 neuronal and glial cells simultaneously. Based on nAChR expression, DRG neurons could be divided into four subclasses: (1) neurons that express predominantly α3β4 and α6β4 nAChRs; (2) neurons that express predominantly α7 nAChRs; (3) neurons that express a combination of α3β4/α6β4 and α7 nAChRs; and (4) neurons that do not express nAChRs. In this comparative study, the same four neuronal subclasses were observed in mouse and rat DRG. However, the expression frequency differed between species: substantially more rat DRG neurons were in the first three subclasses than mouse DRG neurons, at all developmental time points tested in our study. Approximately 70-80% of rat DRG neurons expressed functional nAChRs, in contrast to only ~15-30% of mouse DRG neurons. Our study also demonstrated functional coupling between nAChRs, voltage-gated calcium channels, and mitochondrial Ca(2) (+) transport in discrete subsets of DRG neurons. In contrast to the expression of nAChRs in DRG neurons, we demonstrated that a subset of non-neuronal DRG cells expressed muscarinic acetylcholine receptors and not nAChRs. The general approach to comparative cellular neurobiology outlined in this paper has the potential to better integrate molecular and systems neuroscience by uncovering the spectrum of neuronal subclasses present in a given cell population and the functionally integrated signaling components expressed in each subclass.
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Affiliation(s)
- Nathan J Smith
- Department of Biology, University of Utah Salt Lake City, UT, USA
| | - Arik J Hone
- Department of Biology, University of Utah Salt Lake City, UT, USA ; Interdepartmental Neuroscience Program, University of Utah Salt Lake City, UT, USA
| | - Tosifa Memon
- Department of Biology, University of Utah Salt Lake City, UT, USA
| | - Simon Bossi
- Department of Biology, University of Utah Salt Lake City, UT, USA
| | - Thomas E Smith
- Department of Biology, University of Utah Salt Lake City, UT, USA
| | - J Michael McIntosh
- Department of Biology, University of Utah Salt Lake City, UT, USA ; Department of Psychiatry, University of Utah Salt Lake City, UT, USA ; George E. Wahlen Veterans Affairs Medical Center Salt Lake City, UT, USA
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50
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Jensen AB, Hoestgaard-Jensen K, Jensen AA. Elucidation of molecular impediments in the α6 subunit for in vitro expression of functional α6β4* nicotinic acetylcholine receptors. J Biol Chem 2013; 288:33708-33721. [PMID: 24085295 DOI: 10.1074/jbc.m113.509356] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Explorations into the α6-containing nicotinic acetylcholine receptors (α6* nAChRs) as putative drug targets have been severely hampered by the inefficient functional expression of the receptors in heterologous expression systems. In this study, the molecular basis for the problem was investigated through the construction of chimeric α6/α3 and mutant α3 and α6 subunits and functional characterization of these co-expressed with β4 or β4β3 subunits in tsA201 cells in a fluorescence-based assay and in Xenopus oocytes using two-electrode voltage clamp electrophysiology. Substitution of a small C-terminal segment in the second intracellular loop or the Phe(223) residue in transmembrane helix 1 of α6 with the corresponding α3 segment or residue was found to enhance α6β4 functionality in tsA201 cells significantly, in part due to increased cell surface expression of the receptors. The gain-of-function effects of these substitutions appeared to be additive since incorporation of both α3 elements into α6 resulted in assembly of α6β4* receptors exhibiting robust functional responses to acetylcholine. The pharmacological properties exhibited by α6β4β3 receptors comprising one of these novel α6/α3 chimeras in oocytes were found to be in good agreement with those from previous studies of α6* nAChRs formed from other surrogate α6 subunits or concatenated subunits and studies of other heteromeric nAChRs. In contrast, co-expression of this α6/α3 chimera with β2 or β2β3 subunits in oocytes did not result in efficient formation of functional receptors, indicating that the identified molecular elements in α6 could be specific impediments for the expression of functional α6β4* nAChRs.
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Affiliation(s)
- Anne B Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Kirsten Hoestgaard-Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
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