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Chow CY, King GF. Shining a Light on Venom-Peptide Receptors: Venom Peptides as Targeted Agents for In Vivo Molecular Imaging. Toxins (Basel) 2024; 16:307. [PMID: 39057947 DOI: 10.3390/toxins16070307] [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: 05/13/2024] [Revised: 06/27/2024] [Accepted: 07/02/2024] [Indexed: 07/28/2024] Open
Abstract
Molecular imaging has revolutionised the field of biomedical research by providing a non-invasive means to visualise and understand biochemical processes within living organisms. Optical fluorescent imaging in particular allows researchers to gain valuable insights into the dynamic behaviour of a target of interest in real time. Ion channels play a fundamental role in cellular signalling, and they are implicated in diverse pathological conditions, making them an attractive target in the field of molecular imaging. Many venom peptides exhibit exquisite selectivity and potency towards ion channels, rendering them ideal agents for molecular imaging applications. In this review, we illustrate the use of fluorescently-labelled venom peptides for disease diagnostics and intraoperative imaging of brain tumours and peripheral nerves. Finally, we address challenges for the development and clinical translation of venom peptides as nerve-targeted imaging agents.
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Affiliation(s)
- Chun Yuen Chow
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
- Australia Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
- Australia Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St. Lucia, QLD 4072, Australia
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2
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Fluorescently Labeled α-Conotoxin TxID, a New Probe for α3β4 Neuronal Nicotinic Acetylcholine Receptors. Mar Drugs 2022; 20:md20080511. [PMID: 36005514 PMCID: PMC9410468 DOI: 10.3390/md20080511] [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: 06/29/2022] [Revised: 08/07/2022] [Accepted: 08/09/2022] [Indexed: 11/16/2022] Open
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) are important ion channel membrane proteins that are widely distributed in the central nervous system (CNS) and peripheral nervous system (PNS). As an important member, α3β4 nAChRs are related to pain sensation in PNS and nicotine addiction in CNS. However, research related to the α3β4 nAChRs is greatly limited by the lack of subtype-selective pharmacological tools. The α-conotoxin (α-CTx) TxID from the marine cone snail, Conus textile, is a selective α3β4 nAChR antagonist with relatively high potency. In this study, a fluorescent dye (5-TAMRA SE) was used to label TxID on the N-terminus of α-CTx TxID, and pure TxID-F (fluorescent analogue of TxID) was obtained by HPLC. At the same time, the potency and selectivity of TxID-F were detected by high-performance liquid chromatography (HPLC). Additionally, the potency and selectivity of TxID-F were determined by using a two-electrode voltage-clamp technique on various nAChRs expressed in the Xenopus oocyte expression system. The results obtained by electrophysiology showed that TxID-F maintained the same order of potency (IC50 73 nM) as the native toxin (IC50 25 nM) for the α3β4 nAChR subtype. In addition, the results of fluorescent spectroscopy and circular dichroism showed TxID-F has the same fluorescence as 5-TAMRA SE, as well as similar profiles as TxID. The results of flow cytometry showed that the histogram shifted significantly to the right for the RAW264.7 cells expressing α3β4-containing nAChRs stained with TxID-F and confirmed by live cell imaging. The study of fluorescent-labeled α-CTx TxID provides a rich pharmacological tool to explore the structure-function relationship, distribution, and ligand-binding domain of α3β4 nAChR subtype in the future.
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3
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Bavo F, Pallavicini M, Pucci S, Appiani R, Giraudo A, Eaton B, Lucero L, Gotti C, Moretti M, Whiteaker P, Bolchi C. From 2-Triethylammonium Ethyl Ether of 4-Stilbenol (MG624) to Selective Small-Molecule Antagonists of Human α9α10 Nicotinic Receptor by Modifications at the Ammonium Ethyl Residue. J Med Chem 2022; 65:10079-10097. [PMID: 35834819 PMCID: PMC9339509 DOI: 10.1021/acs.jmedchem.2c00746] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nicotinic acetylcholine receptors containing α9 subunits (α9*-nAChRs) are potential druggable targets arousing great interest for pain treatment alternative to opioids. Nonpeptidic small molecules selectively acting as α9*-nAChRs antagonists still remain an unattained goal. Here, through modifications of the cationic head and the ethylene linker, we have converted the 2-triethylammonium ethyl ether of 4-stilbenol (MG624), a well-known α7- and α9*-nAChRs antagonist, into some selective antagonists of human α9*-nAChR. Among these, the compound with cyclohexyldimethylammonium head (7) stands out for having no α7-nAChR agonist or antagonist effect along with very low affinity at both α7- and α3β4-nAChRs. At supra-micromolar concentrations, 7 and the other selective α9* antagonists behaved as partial agonists at α9*-nAChRs with a very brief response, followed by rebound current once the application is stopped and the channel is disengaged. The small or null postapplication activity of ACh seems to be related to the slow recovery of the rebound current.
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Affiliation(s)
- Francesco Bavo
- Dipartimento
di Scienze Farmaceutiche, Università
degli Studi di Milano, via Mangiagalli 25, I-20133 Milano, Italy,Department
of Drug Design and Pharmacology, University
of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Marco Pallavicini
- Dipartimento
di Scienze Farmaceutiche, Università
degli Studi di Milano, via Mangiagalli 25, I-20133 Milano, Italy
| | - Susanna Pucci
- Institute
of Neuroscience, CNR, via Vanvitelli 32, I-20129 Milano, Italy,NeuroMi
Milan Center for Neuroscience, University
of Milano Bicocca, piazza
Ateneo Nuovo 1, I-20126 Milano, Italy
| | - Rebecca Appiani
- Dipartimento
di Scienze Farmaceutiche, Università
degli Studi di Milano, via Mangiagalli 25, I-20133 Milano, Italy
| | - Alessandro Giraudo
- Dipartimento
di Scienze Farmaceutiche, Università
degli Studi di Milano, via Mangiagalli 25, I-20133 Milano, Italy
| | - Brek Eaton
- Division
of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013, United States
| | - Linda Lucero
- Division
of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013, United States
| | - Cecilia Gotti
- Institute
of Neuroscience, CNR, via Vanvitelli 32, I-20129 Milano, Italy
| | - Milena Moretti
- Institute
of Neuroscience, CNR, via Vanvitelli 32, I-20129 Milano, Italy,Department
of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, via Vanvitelli 32, I-20129 Milano, Italy
| | - Paul Whiteaker
- Department
of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Cristiano Bolchi
- Dipartimento
di Scienze Farmaceutiche, Università
degli Studi di Milano, via Mangiagalli 25, I-20133 Milano, Italy,. Phone: +390250319347
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4
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Richter K, Papke RL, Stokes C, Roy DC, Espinosa ES, Wolf PMK, Hecker A, Liese J, Singh VK, Padberg W, Schlüter KD, Rohde M, McIntosh JM, Morley BJ, Horenstein NA, Grau V, Simard AR. Comparison of the Anti-inflammatory Properties of Two Nicotinic Acetylcholine Receptor Ligands, Phosphocholine and pCF3-diEPP. Front Cell Neurosci 2022; 16:779081. [PMID: 35431807 PMCID: PMC9008208 DOI: 10.3389/fncel.2022.779081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 03/10/2022] [Indexed: 12/14/2022] Open
Abstract
Activation of nicotinic acetylcholine receptors (nAChRs) expressed by innate immune cells can attenuate pro-inflammatory responses. Silent nAChR agonists, which down-modulate inflammation but have little or no ionotropic activity, are of outstanding clinical interest for the prevention and therapy of numerous inflammatory diseases. Here, we compare two silent nAChR agonists, phosphocholine, which is known to interact with nAChR subunits α7, α9, and α10, and pCF3-N,N-diethyl-N′-phenyl-piperazine (pCF3-diEPP), a previously identified α7 nAChR silent agonist, regarding their anti-inflammatory properties and their effects on ionotropic nAChR functions. The lipopolysaccharide (LPS)-induced release of interleukin (IL)-6 by primary murine macrophages was inhibited by pCF3-diEPP, while phosphocholine was ineffective presumably because of instability. In human whole blood cultures pCF3-diEPP inhibited the LPS-induced secretion of IL-6, TNF-α and IL-1β. The ATP-mediated release of IL-1β by LPS-primed human peripheral blood mononuclear leukocytes, monocytic THP-1 cells and THP-1-derived M1-like macrophages was reduced by both phosphocholine and femtomolar concentrations of pCF3-diEPP. These effects were sensitive to mecamylamine and to conopeptides RgIA4 and [V11L; V16D]ArIB, suggesting the involvement of nAChR subunits α7, α9 and/or α10. In two-electrode voltage-clamp measurements pCF3-diEPP functioned as a partial agonist and a strong desensitizer of classical human α9 and α9α10 nAChRs. Interestingly, pCF3-diEPP was more effective as an ionotropic agonist at these nAChRs than at α7 nAChR. In conclusion, phosphocholine and pCF3-diEPP are potent agonists at unconventional nAChRs expressed by monocytic and macrophage-like cells. pCF3-diEPP inhibits the LPS-induced release of pro-inflammatory cytokines, while phosphocholine is ineffective. However, both agonists signal via nAChR subunits α7, α9 and/or α10 to efficiently down-modulate the ATP-induced release of IL-1β. Compared to phosphocholine, pCF3-diEPP is expected to have better pharmacological properties. Thus, low concentrations of pCF3-diEPP may be a therapeutic option for the treatment of inflammatory diseases including trauma-induced sterile inflammation.
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Affiliation(s)
- Katrin Richter
- Department of General and Thoracic Surgery, Laboratory of Experimental Surgery, Justus-Liebig-University, German Center for Lung Research, Giessen, Germany
- *Correspondence: Katrin Richter,
| | - Roger L. Papke
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States
| | - Clare Stokes
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States
| | - Danika C. Roy
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON, Canada
| | | | - Philipp M. K. Wolf
- Department of General and Thoracic Surgery, Laboratory of Experimental Surgery, Justus-Liebig-University, German Center for Lung Research, Giessen, Germany
| | - Andreas Hecker
- Department of General and Thoracic Surgery, Laboratory of Experimental Surgery, Justus-Liebig-University, German Center for Lung Research, Giessen, Germany
| | - Juliane Liese
- Department of General and Thoracic Surgery, Laboratory of Experimental Surgery, Justus-Liebig-University, German Center for Lung Research, Giessen, Germany
| | - Vijay K. Singh
- Department of Pediatric Hematology and Oncology, Justus-Liebig-University, Giessen, Germany
| | - Winfried Padberg
- Department of General and Thoracic Surgery, Laboratory of Experimental Surgery, Justus-Liebig-University, German Center for Lung Research, Giessen, Germany
| | | | - Marius Rohde
- Department of Pediatric Hematology and Oncology, Justus-Liebig-University, Giessen, Germany
| | - J. Michael McIntosh
- Department of Biology, University of Utah, Salt Lake City, UT, United States
- George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, UT, United States
- Department of Psychiatry, University of Utah, Salt Lake City, UT, United States
| | - Barbara J. Morley
- Center for Sensory Neuroscience, Boys Town National Research Hospital, Omaha, NE, United States
| | | | - Veronika Grau
- Department of General and Thoracic Surgery, Laboratory of Experimental Surgery, Justus-Liebig-University, German Center for Lung Research, Giessen, Germany
| | - Alain R. Simard
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON, Canada
- Department of Biology, Laurentian University, Sudbury, ON, Canada
- Northern Ontario School of Medicine, Sudbury, ON, Canada
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5
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Yang Y, Tan Y, Zhangsun D, Zhu X, Luo S. Design, Synthesis, and Activity of an α-Conotoxin LtIA Fluorescent Analogue. ACS Chem Neurosci 2021; 12:3662-3671. [PMID: 34523332 DOI: 10.1021/acschemneuro.1c00392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are essential pentameric ligand-gated ion channels that are distributed throughout the central and peripheral nervous systems and non-neuronal tissues in mammalian species that play critical roles in a variety of neural and mental activities. The α3β2 nAChR subtype participates in pain, addiction to nicotine, and other neurophysiological and pathological activities. Owing to the lack of highly selective pharmacological tools targeting α3β2, related research on its tissue distribution and function has been hindered. α-Conotoxin (α-CTx) LtIA, discovered from Conus literatus in our lab, potently and selectively blocks α3β2 nAChR, providing an important molecular probe to study the α3β2 nAChR structure and function. We used the fluorescent molecule 5-carboxytetramethylrhodamine succinimidyl ester, which can react with the N-terminus of LtIA, to obtain a novel fluorescent analogue of LtIA (LtIA-F). The potency and selectivity of LtIA-F were tested using a two-electrode voltage clamp recording on various nAChRs expressed in Xenopus laevis oocytes. LtIA-F potently inhibited ACh-evoked currents at the α3β2 nAChR, with an IC50 value of 90.66 nM, displaying a ∼4-fold decrease in potency compared with native LtIA without a change in selectivity. The serum stability results indicated that LtIA-F exhibited stability similar to that of native LtIA. This study on an α-CTx LtIA fluorescent analogue provides a wealth of pharmacological tools to explore the structure-function relationship, distribution, and ligand binding domain of the α3β2 nAChR subtype.
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Affiliation(s)
- Yishuai Yang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Yao Tan
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Xiaopeng Zhu
- Medical School, Guangxi University, Nanning 530004, China
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
- Medical School, Guangxi University, Nanning 530004, China
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6
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Terpinskaya TI, Osipov AV, Kryukova EV, Kudryavtsev DS, Kopylova NV, Yanchanka TL, Palukoshka AF, Gondarenko EA, Zhmak MN, Tsetlin VI, Utkin YN. α-Conotoxins and α-Cobratoxin Promote, while Lipoxygenase and Cyclooxygenase Inhibitors Suppress the Proliferation of Glioma C6 Cells. Mar Drugs 2021; 19:md19020118. [PMID: 33669933 PMCID: PMC7956437 DOI: 10.3390/md19020118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/01/2021] [Accepted: 02/18/2021] [Indexed: 12/11/2022] Open
Abstract
Among the brain tumors, glioma is the most common. In general, different biochemical mechanisms, involving nicotinic acetylcholine receptors (nAChRs) and the arachidonic acid cascade are involved in oncogenesis. Although the engagement of the latter in survival and proliferation of rat C6 glioma has been shown, there are practically no data about the presence and the role of nAChRs in C6 cells. In this work we studied the effects of nAChR antagonists, marine snail α-conotoxins and snake α-cobratoxin, on the survival and proliferation of C6 glioma cells. The effects of the lipoxygenase and cyclooxygenase inhibitors either alone or together with α-conotoxins and α-cobratoxin were studied in parallel. It was found that α-conotoxins and α-cobratoxin promoted the proliferation of C6 glioma cells, while nicotine had practically no effect at concentrations below 1 µL/mL. Nordihydroguaiaretic acid, a nonspecific lipoxygenase inhibitor, and baicalein, a 12-lipoxygenase inhibitor, exerted antiproliferative and cytotoxic effects on C6 cells. nAChR inhibitors weaken this effect after 24 h cultivation but produced no effects at longer times. Quantitative real-time polymerase chain reaction showed that mRNA for α4, α7, β2 and β4 subunits of nAChR were expressed in C6 glioma cells. This is the first indication for involvement of nAChRs in mechanisms of glioma cell proliferation.
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Affiliation(s)
- Tatiana I. Terpinskaya
- Institute of Physiology, National Academy of Sciences of Belarus, ul. Akademicheskaya, 28, 220072 Minsk, Belarus; (T.I.T.); (T.L.Y.); (A.F.P.)
| | - Alexey V. Osipov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.V.O.); (E.V.K.); (D.S.K.); (N.V.K.); (E.A.G.); (M.N.Z.); (V.I.T.)
| | - Elena V. Kryukova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.V.O.); (E.V.K.); (D.S.K.); (N.V.K.); (E.A.G.); (M.N.Z.); (V.I.T.)
| | - Denis S. Kudryavtsev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.V.O.); (E.V.K.); (D.S.K.); (N.V.K.); (E.A.G.); (M.N.Z.); (V.I.T.)
| | - Nina V. Kopylova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.V.O.); (E.V.K.); (D.S.K.); (N.V.K.); (E.A.G.); (M.N.Z.); (V.I.T.)
| | - Tatsiana L. Yanchanka
- Institute of Physiology, National Academy of Sciences of Belarus, ul. Akademicheskaya, 28, 220072 Minsk, Belarus; (T.I.T.); (T.L.Y.); (A.F.P.)
| | - Alena F. Palukoshka
- Institute of Physiology, National Academy of Sciences of Belarus, ul. Akademicheskaya, 28, 220072 Minsk, Belarus; (T.I.T.); (T.L.Y.); (A.F.P.)
| | - Elena A. Gondarenko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.V.O.); (E.V.K.); (D.S.K.); (N.V.K.); (E.A.G.); (M.N.Z.); (V.I.T.)
| | - Maxim N. Zhmak
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.V.O.); (E.V.K.); (D.S.K.); (N.V.K.); (E.A.G.); (M.N.Z.); (V.I.T.)
| | - Victor I. Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.V.O.); (E.V.K.); (D.S.K.); (N.V.K.); (E.A.G.); (M.N.Z.); (V.I.T.)
| | - Yuri N. Utkin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.V.O.); (E.V.K.); (D.S.K.); (N.V.K.); (E.A.G.); (M.N.Z.); (V.I.T.)
- Correspondence: or ; Tel.: +7-495-3366522
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7
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Muttenthaler M, Nevin ST, Inserra M, Lewis RJ, Adams DJ, Alewood P. On-resin strategy to label α-conotoxins: Cy5-RgIA, a potent α9α10 nicotinic acetylcholine receptor imaging probe. Aust J Chem 2019; 73:327-333. [PMID: 32394983 PMCID: PMC7212043 DOI: 10.1071/ch19456] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In-solution conjugation is the most commonly used strategy to label peptides and proteins with fluorophores. However, lack of site-specific control and high costs of fluorophores are recognised limitations of this approach. Here, we established facile access to grams of Cy5-COOH via a two-step synthetic route, demonstrated that Cy5 is stable to HF treatment and therefore compatible with Boc-SPPS, and coupled Cy5 to the N-terminus of α-conotoxin RgIA while still attached to the resin. Folding of the two-disulfide containing Cy5-RgIA benefitted from the hydrophobic nature of Cy5 resulting in only the globular disulfide bond isomer. In contrast, wild-type α-RgIA folded into the inactive ribbon and bioactive globular isomer under the same conditions. Labelled α-RgIA retained its ability to inhibit acetylcholine(100 μM)-evoked current reversibly with an IC50 of 5.0 nM (Hill coefficient = 1.7) for α-RgIA and an IC50 of 1.6 (Hill coefficient = 1.2) for Cy5-RgIA at the α9α10 nicotinic acetylcholine receptors (nAChRs) heterologeously expressed in Xenopus oocytes. Cy5-RgIA was then used to successfully visualise nAChRs in RAW264.7 mouse macrophage cell line. This work introduced not only a new and valuable nAChR probe, but also a new versatile synthetic strategy that facilitates production of milligram to gram quantities of fluorophore-labelled peptides at low cost, which is often required for in vivo experiments. The strategy is compatible with Boc- and Fmoc-chemistry, allows for site-specific labelling of free amines anywhere in the peptide sequence, and can also be used for the introduction of Cy3/Cy5 FRET pairs.
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Affiliation(s)
- Markus Muttenthaler
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
- Institute of Biological Chemistry, Faculty of Chemistry, University of Vienna, Vienna, Austria
| | - Simon T Nevin
- Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | - Marco Inserra
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Paul Alewood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
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8
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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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9
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Grau V, Richter K, Hone AJ, McIntosh JM. Conopeptides [V11L;V16D]ArIB and RgIA4: Powerful Tools for the Identification of Novel Nicotinic Acetylcholine Receptors in Monocytes. Front Pharmacol 2019; 9:1499. [PMID: 30687084 PMCID: PMC6338043 DOI: 10.3389/fphar.2018.01499] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 12/07/2018] [Indexed: 12/27/2022] Open
Abstract
Venomous marine snails of the genus Conus employ small peptides to capture prey, mainly osteichthyes, mollusks, and worms. A subset of these peptides known as α-conotoxins, are antagonists of nicotinic acetylcholine receptors (nAChRs). These disulfide-rich peptides provide a large number of evolutionarily refined templates that can be used to develop conopeptides that are highly selective for the various nAChR subtypes. Two such conopeptides, namely [V11L;V16D]ArIB and RgIA4, have been engineered to selectively target mammalian α7∗ and α9∗ nAChRs, respectively, and have been used to study the functional roles of these subtypes in immune cells. Unlike in neurons and cochlear hair cells, where α7∗ and α9∗ nAChRs, respectively, function as ligand-gated ion channels, in immune cells ligand-evoked ion currents have not been demonstrated. Instead, different metabotropic functions of α7∗ and α9∗ nAChRs have been described in monocytic cells including the inhibition of ATP-induced ion currents, inflammasome activation, and interleukin-1β (IL-1β) release. In addition to conventional nAChR agonists, diverse compounds containing a phosphocholine group inhibit monocytic IL-1β release and include dipalmitoyl phosphatidylcholine, palmitoyl lysophosphatidylcholine, glycerophosphocholine, phosphocholine, phosphocholine-decorated lipooligosaccharides from Haemophilus influenzae, synthetic phosphocholine-modified bovine serum albumin, and the phosphocholine-binding C-reactive protein. In monocytic cells, the effects of [V11L;V16D]ArIB and RgIA4 suggested that activation of nAChRs containing α9, α7, and/or α10 subunits inhibits ATP-induced IL-1β release. These results have been corroborated utilizing gene-deficient mice and small interfering RNA. Targeted re-engineering of native α-conotoxins has resulted in excellent tools for nAChR research as well as potential therapeutics. ∗indicates possible presence of additional subunits.
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Affiliation(s)
- Veronika Grau
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, German Centre for Lung Research (DZL), Giessen University, Giessen, Germany
| | - Katrin Richter
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, German Centre for Lung Research (DZL), Giessen University, Giessen, Germany
| | - Arik J Hone
- Department of Biology, University of Utah, Salt Lake City, UT, United States
| | - J Michael McIntosh
- Department of Biology, University of Utah, Salt Lake City, UT, United States.,George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, UT, United States.,Department of Psychiatry, University of Utah, Salt Lake City, UT, United States
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10
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Samra GK, Intskirveli I, Govind AP, Liang C, Lazar R, Green WN, Metherate R, Mukherjee J. Development of fluorescence imaging probes for nicotinic acetylcholine α4β2 ∗ receptors. Bioorg Med Chem Lett 2018; 28:371-377. [PMID: 29277457 DOI: 10.1016/j.bmcl.2017.12.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 12/13/2017] [Accepted: 12/16/2017] [Indexed: 11/29/2022]
Abstract
Nicotinic acetylcholine α4β2∗ receptors (nAChRs) are implicated in various neurodegenerative diseases and smoking addiction. Imaging of brain high-affinity α4β2∗ nAChRs at the cellular and subcellular levels would greatly enhance our understanding of their functional role. Since better resolution could be achieved with fluorescent probes, using our previously developed positron emission tomography (PET) imaging agent [18F]nifrolidine, we report here design, synthesis and evaluation of two fluorescent probes, nifrodansyl and nifrofam for imaging α4β2∗ nAChRs. The nifrodansyl and nifrofam exhibited nanomolar affinities for the α4β2∗ nAChRs in [3H]cytisine-radiolabeled rat brain slices. Nifrofam labeling was observed in α4β2∗ nAChR-expressing HEK cells and was upregulated by nicotine exposure. Nifrofam co-labeled cell-surface α4β2∗ nAChRs, labeled with antibodies specific for a β2 subunit extracellular epitope indicating that nifrofam labels α4β2∗ nAChR high-affinity binding sites. Mouse brain slices exhibited discrete binding of nifrofam in the auditory cortex showing promise for examining cellular distribution of α4β2∗ nAChRs in brain regions.
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Affiliation(s)
- Gurleen K Samra
- Preclinical Imaging, Department of Radiological Sciences, University of California-Irvine, Irvine, CA 92697, United States
| | - Irakli Intskirveli
- Department of Neurobiology and Behavior, University of California-Irvine, Irvine, CA 92697, United States
| | - Anitha P Govind
- Department of Neurobiology, University of Chicago, IL 60637, United States
| | - Christopher Liang
- Preclinical Imaging, Department of Radiological Sciences, University of California-Irvine, Irvine, CA 92697, United States
| | - Ronit Lazar
- Department of Neurobiology and Behavior, University of California-Irvine, Irvine, CA 92697, United States
| | - William N Green
- Department of Neurobiology, University of Chicago, IL 60637, United States
| | - Raju Metherate
- Department of Neurobiology and Behavior, University of California-Irvine, Irvine, CA 92697, United States
| | - Jogeshwar Mukherjee
- Preclinical Imaging, Department of Radiological Sciences, University of California-Irvine, Irvine, CA 92697, United States; Department of Biomedical Engineering, University of California-Irvine, Irvine, CA 92697, United States.
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11
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Mucchietto V, Fasoli F, Pucci S, Moretti M, Benfante R, Maroli A, Di Lascio S, Bolchi C, Pallavicini M, Dowell C, McIntosh M, Clementi F, Gotti C. α9- and α7-containing receptors mediate the pro-proliferative effects of nicotine in the A549 adenocarcinoma cell line. Br J Pharmacol 2017; 175:1957-1972. [PMID: 28726253 DOI: 10.1111/bph.13954] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 06/14/2017] [Accepted: 07/07/2017] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Tobacco smoke contains many classes of carcinogens and although nicotine is unable to initiate tumourigenesis in humans and rodents, it promotes tumour growth and metastasis in lung tumours by acting on neuronal nicotinic ACh receptors (nAChRs). The aim of this study was to identify molecularly, biochemically and pharmacologically which nAChR subtypes are expressed and functionally activated by nicotine in lung cancer cell lines. EXPERIMENTAL APPROACH We used A549 and H1975 adenocarcinoma cell lines derived from lung tumours to test the in vitro effects of nicotine, and nAChR subtype-specific peptides and compounds. KEY RESULTS The two adenocarcinoma cell lines express distinctive nAChR subtypes, and this affects their nicotine-induced proliferation. In A549 cells, nAChRs containing the α7 or α9 subunits not only regulate nicotine-induced cell proliferation but also the activation of the Akt and ERK pathways. Blocking these nAChRs by means of subtype-specific peptides, or silencing their expression by means of subunit-specific siRNAs, abolishes nicotine-induced proliferation and signalling. Moreover, we found that the α7 antagonist MG624 also acts on α9-α10 nAChRs, blocks the effects of nicotine on A549 cells and has dose-dependent cytotoxic activity. CONCLUSIONS AND IMPLICATIONS These results highlight the pathophysiological role of α7- and α9-containing receptors in promoting non-small cell lung carcinoma cell growth and intracellular signalling and provide a framework for the development of new drugs that specifically target the receptors expressed in lung tumours. LINKED ARTICLES This article is part of a themed section on Nicotinic Acetylcholine Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.11/issuetoc.
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Affiliation(s)
- Vanessa Mucchietto
- CNR, Institute of Neuroscience, Milan, Italy.,Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
| | | | | | - Milena Moretti
- CNR, Institute of Neuroscience, Milan, Italy.,Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
| | - Roberta Benfante
- CNR, Institute of Neuroscience, Milan, Italy.,Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
| | - Annalisa Maroli
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
| | - Simona Di Lascio
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
| | - Cristiano Bolchi
- Department of Pharmaceutical Science, Università degli Studi di Milano, Milan, Italy
| | - Marco Pallavicini
- Department of Pharmaceutical Science, Università degli Studi di Milano, Milan, Italy
| | - Cheryl Dowell
- Department of Biology, University of Utah, Salt Lake City, UT, USA
| | - Michael McIntosh
- Department of Biology, University of Utah, Salt Lake City, UT, USA.,George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Department of Psychiatry, University of Utah, Salt Lake City, UT, USA
| | - Francesco Clementi
- CNR, Institute of Neuroscience, Milan, Italy.,Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
| | - Cecilia Gotti
- CNR, Institute of Neuroscience, Milan, Italy.,Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
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12
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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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13
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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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14
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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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15
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Hellyer SD, Selwood AI, van Ginkel R, Munday R, Sheard P, Miles CO, Rhodes L, Kerr DS. In vitro labelling of muscle type nicotinic receptors using a fluorophore-conjugated pinnatoxin F derivative. Toxicon 2014; 87:17-25. [DOI: 10.1016/j.toxicon.2014.05.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 05/02/2014] [Accepted: 05/07/2014] [Indexed: 11/30/2022]
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16
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Hopping G, Wang CIA, Hogg RC, Nevin ST, Lewis RJ, Adams DJ, Alewood PF. Hydrophobic residues at position 10 of α-conotoxin PnIA influence subtype selectivity between α7 and α3β2 neuronal nicotinic acetylcholine receptors. Biochem Pharmacol 2014; 91:534-42. [PMID: 25101833 DOI: 10.1016/j.bcp.2014.07.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 07/25/2014] [Accepted: 07/28/2014] [Indexed: 11/25/2022]
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) are a diverse class of ligand-gated ion channels involved in neurological conditions such as neuropathic pain and Alzheimer's disease. α-Conotoxin [A10L]PnIA is a potent and selective antagonist of the mammalian α7 nAChR with a key binding interaction at position 10. We now describe a molecular analysis of the receptor-ligand interactions that determine the role of position 10 in determining potency and selectivity for the α7 and α3β2 nAChR subtypes. Using electrophysiological and radioligand binding methods on a suite of [A10L]PnIA analogs we observed that hydrophobic residues in position 10 maintained potency at both subtypes whereas charged or polar residues abolished α7 binding. Molecular docking revealed dominant hydrophobic interactions with several α7 and α3β2 receptor residues via a hydrophobic funnel. Incorporation of norleucine (Nle) caused the largest (8-fold) increase in affinity for the α7 subtype (Ki=44nM) though selectivity reverted to α3β2 (IC50=0.7nM). It appears that the placement of a single methyl group determines selectivity between α7 and α3β2 nAChRs via different molecular determinants.
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Affiliation(s)
- Gene Hopping
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - C-I Anderson Wang
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Ron C Hogg
- Department of Neuroscience, Centre Medical Universitaire, Medical Faculty, 1 rue Michel Servet, CH-1211 Geneva 4, Switzerland
| | - Simon T Nevin
- Queensland Brain Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - David J Adams
- Queensland Brain Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia; Health Innovations Research Institute, RMIT University, Bundoora, Victoria 3083, Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia.
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17
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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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18
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Hone AJ, Ruiz M, Scadden M, Christensen S, Gajewiak J, Azam L, McIntosh JM. Positional scanning mutagenesis of α-conotoxin PeIA identifies critical residues that confer potency and selectivity for α6/α3β2β3 and α3β2 nicotinic acetylcholine receptors. J Biol Chem 2013; 288:25428-25439. [PMID: 23846688 DOI: 10.1074/jbc.m113.482059] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The nicotinic acetylcholine receptor (nAChR) subtype α6β2* (the asterisk denotes the possible presence of additional subunits) has been identified as an important molecular target for the pharmacotherapy of Parkinson disease and nicotine dependence. The α6 subunit is closely related to the α3 subunit, and this presents a problem in designing ligands that discriminate between α6β2* and α3β2* nAChRs. We used positional scanning mutagenesis of α-conotoxin PeIA, which targets both α6β2* and α3β2*, in combination with mutagenesis of the α6 and α3 subunits, to gain molecular insights into the interaction of PeIA with heterologously expressed α6/α3β2β3 and α3β2 receptors. Mutagenesis of PeIA revealed that Asn(11) was located in an important position that interacts with the α6 and α3 subunits. Substitution of Asn(11) with a positively charged amino acid essentially abolished the activity of PeIA for α3β2 but not for α6/α3β2β3 receptors. These results were used to synthesize a PeIA analog that was >15,000-fold more potent on α6/α3β2β3 than α3β2 receptors. Analogs with an N11R substitution were then used to show a critical interaction between the 11th position of PeIA and Glu(152) of the α6 subunit and Lys(152) of the α3 subunit. The results of these studies provide molecular insights into designing ligands that selectively target α6β2* nAChRs.
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Affiliation(s)
| | | | | | | | | | | | - J Michael McIntosh
- the Departments of Biology and; From the Interdepartmental Program in Neuroscience and; Psychiatry, University of Utah, Salt Lake City, Utah 84132 and; the George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah 84148.
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19
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Bingham JP, Andrews EA, Kiyabu SM, Cabalteja CC. Drugs from slugs. Part II--conopeptide bioengineering. Chem Biol Interact 2012; 200:92-113. [PMID: 23063744 DOI: 10.1016/j.cbi.2012.09.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Revised: 08/27/2012] [Accepted: 09/17/2012] [Indexed: 11/27/2022]
Abstract
The biological transformation of toxins as research probes, or as pharmaceutical drug leads, is an onerous and drawn out process. Issues regarding changes to pharmacological specificity, desired potency, and bioavailability are compounded naturally by their inherent toxicity. These often scuttle their progress as they move up the narrowing drug development pipeline. Yet one class of peptide toxins, from the genus Conus, has in many ways spearheaded the expansion of new peptide bioengineering techniques to aid peptide toxin pharmaceutical development. What has now emerged is the sequential bioengineering of new research probes and drug leads that owe their lineage to these highly potent and isoform specific peptides. Here we discuss the progressive bioengineering steps that many conopeptides have transitioned through, and specifically illustrate some of the biochemical approaches that have been established to maximize their biological research potential and pharmaceutical worth.
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Affiliation(s)
- Jon-Paul Bingham
- Department of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI 96822, USA.
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Hone AJ, Scadden M, Gajewiak J, Christensen S, Lindstrom J, McIntosh JM. α-Conotoxin PeIA[S9H,V10A,E14N] potently and selectively blocks α6β2β3 versus α6β4 nicotinic acetylcholine receptors. Mol Pharmacol 2012; 82:972-82. [PMID: 22914547 DOI: 10.1124/mol.112.080853] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) containing α6 and β2 subunits modulate dopamine release in the basal ganglia and are therapeutically relevant targets for treatment of neurological and psychiatric disorders including Parkinson's disease and nicotine dependence. However, the expression profile of β2 and β4 subunits overlap in a variety of tissues including locus ceruleus, retina, hippocampus, dorsal root ganglia, and adrenal chromaffin cells. Ligands that bind α6β2 nAChRs also potently bind the closely related α6β4 subtype. To distinguish between these two subtypes, we synthesized novel analogs of a recently described α-conotoxin, PeIA. PeIA is a peptide antagonist that blocks several nAChR subtypes, including α6/α3β2β3 and α6/α3β4 nAChRs, with low nanomolar potency. We systematically mutated PeIA and evaluated the resulting analogs for enhanced potency and/or selectivity for α6/α3β2β3 nAChRs expressed in Xenopus oocytes (α6/α3 is a subunit chimera that contains the N-terminal ligand-binding domain of the α6 subunit). On the basis of these results, second-generation analogs were then synthesized. The final analog, PeIA[S9H,V10A,E14N], potently blocked acetylcholine-gated currents mediated by α6/α3β2β3 and α6/α3β4 nAChRs with IC(50) values of 223 pM and 65 nM, respectively, yielding a >290-fold separation between the two subtypes. Kinetic studies of ligand binding to α6/α3β2β3 nAChRs yielded a k(off) of 0.096 ± 0.001 min(-1) and a k(on) of 0.23 ± 0.019 min(-1) M(-9). The synthesis of PeIA[S9H,V10A,E14N] demonstrates that ligands can be developed to discriminate between α6β2 and α6β4 nAChRs.
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Affiliation(s)
- Arik J Hone
- Department of Biology, University of Utah, Salt Lake City, Utah, USA
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21
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Onset of cholinergic efferent synaptic function in sensory hair cells of the rat cochlea. J Neurosci 2011; 31:15092-101. [PMID: 22016543 DOI: 10.1523/jneurosci.2743-11.2011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In the developing mammalian cochlea, the sensory hair cells receive efferent innervation originating in the superior olivary complex. This input is mediated by α9/α10 nicotinic acetylcholine receptors (nAChRs) and is inhibitory due to the subsequent activation of calcium-dependent SK2 potassium channels. We examined the acquisition of this cholinergic efferent input using whole-cell voltage-clamp recordings from inner hair cells (IHCs) in acutely excised apical turns of the rat cochlea from embryonic day 21 to postnatal day 8 (P8). Responses to 1 mm acetylcholine (ACh) were detected from P0 on in almost every IHC. The ACh-activated current amplitude increased with age and demonstrated the same pharmacology as α9-containing nAChRs. Interestingly, at P0, the ACh response was not coupled to SK2 channels, so that the initial cholinergic response was excitatory and could trigger action potentials in IHCs. Coupling to SK current was detected earliest at P1 in a subset of IHCs and by P3 in every IHC studied. Clustered nAChRs and SK2 channels were found on IHCs from P1 on using Alexa Fluor 488 conjugated α-bungarotoxin and SK2 immunohistochemistry. The number of nAChRs clusters increased with age to 16 per IHC at P8. Cholinergic efferent synaptic currents first appeared in a subset of IHCs at P1 and by P3 in every IHC studied, contemporaneously with ACh-evoked SK currents, suggesting that SK2 channels may be necessary at onset of synaptic function. An analogous pattern of development was observed for the efferent synapses that form later (P6-P8) on outer hair cells in the basal cochlea.
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Hone AJ, Meyer EL, McIntyre M, McIntosh JM. Nicotinic acetylcholine receptors in dorsal root ganglion neurons include the α6β4* subtype. FASEB J 2011; 26:917-26. [PMID: 22024738 DOI: 10.1096/fj.11-195883] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The α6-containing nicotinic acetylcholine receptors (nAChRs) have recently been implicated in diseases of the central nervous system (CNS), including Parkinson's disease and substance abuse. In contrast, little is known about the role of α6* nAChRs in the peripheral nervous system (where the asterisk denotes the possible presence of additional subunits). Dorsal root ganglia (DRG) neurons are known to express nAChRs with a pharmacology consistent with an α7, α3β4*, and α4β2* composition. Here we present evidence that DRG neurons also express α6* nAChRs. We used RT-PCR to show the presence of α6 subunit transcripts and patch-clamp electrophysiology together with subtype-selective α-conotoxins to pharmacologically characterize the nAChRs in rat DRG neurons. α-Conotoxin BuIA (500 nM) blocked acetylcholine-gated currents (I(ACh)) by 90.3 ± 3.0%; the recovery from blockade was very slow, indicating a predominance of α(x)β4* nAChRs. Perfusion with either 300 nM BuIA[T5A;P6O] or 200 nM MII[E11A], α-conotoxins that target the α6β4* subtype, blocked I(ACh) by 49.3 ± 5 and 46.7 ± 8%, respectively. In these neurons, I(ACh) was relatively insensitive to 200 nM ArIB[V11L;V16D] (9.4±2.0% blockade) or 500 nM PnIA (23.0±4% blockade), α-conotoxins that target α7 and α3β2*/α6β2* nAChRs, respectively. We conclude that α6β4* nAChRs are among the subtypes expressed by DRG, and to our knowledge, this is the first demonstration of α6β4* in neurons outside the CNS.
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Affiliation(s)
- Arik J Hone
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah, USA
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Safavi-Hemami H, Siero WA, Kuang Z, Williamson NA, Karas JA, Page LR, MacMillan D, Callaghan B, Kompella SN, Adams DJ, Norton RS, Purcell AW. Embryonic toxin expression in the cone snail Conus victoriae: primed to kill or divergent function? J Biol Chem 2011; 286:22546-57. [PMID: 21504902 DOI: 10.1074/jbc.m110.217703] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Predatory marine cone snails (genus Conus) utilize complex venoms mainly composed of small peptide toxins that target voltage- and ligand-gated ion channels in their prey. Although the venoms of a number of cone snail species have been intensively profiled and functionally characterized, nothing is known about the initiation of venom expression at an early developmental stage. Here, we report on the expression of venom mRNA in embryos of Conus victoriae and the identification of novel α- and O-conotoxin sequences. Embryonic toxin mRNA expression is initiated well before differentiation of the venom gland, the organ of venom biosynthesis. Structural and functional studies revealed that the embryonic α-conotoxins exhibit the same basic three-dimensional structure as the most abundant adult toxin but significantly differ in their neurological targets. Based on these findings, we postulate that the venom repertoire of cone snails undergoes ontogenetic changes most likely reflecting differences in the biotic interactions of these animals with their prey, predators, or competitors. To our knowledge, this is the first study to show toxin mRNA transcripts in embryos, a finding that extends our understanding of the early onset of venom expression in animals and may suggest alternative functions of peptide toxins during development.
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Affiliation(s)
- Helena Safavi-Hemami
- Department of Biochemistry and Molecular Biology, University of Melbourne, 3010 Victoria, Australia
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Blunt JW, Copp BR, Munro MHG, Northcote PT, Prinsep MR. Marine natural products. Nat Prod Rep 2010; 28:196-268. [PMID: 21152619 DOI: 10.1039/c005001f] [Citation(s) in RCA: 343] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- John W Blunt
- Department of Chemistry, University of Canterbury, Christchurch, New Zealand.
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Hone AJ, Whiteaker P, Mohn JL, Jacob MH, McIntosh JM. Alexa Fluor 546-ArIB[V11L;V16A] is a potent ligand for selectively labeling alpha 7 nicotinic acetylcholine receptors. J Neurochem 2010; 114:994-1006. [PMID: 20492354 DOI: 10.1111/j.1471-4159.2010.06819.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The alpha7* (*denotes the possible presence of additional subunits) nicotinic acetylcholine receptor (nAChR) subtype is widely expressed in the vertebrate nervous system and implicated in neuropsychiatric disorders that compromise thought and cognition. In this report, we demonstrate that the recently developed fluorescent ligand Cy3-ArIB[V11L;V16A] labels alpha7 nAChRs in cultured hippocampal neurons. However, photobleaching of this ligand during long image acquisition times prompted us to develop a new derivative. In photostability studies, this new ligand, Alexa Fluor 546-ArIB[V11L;V16A], was significantly more resistant to bleaching than the Cy3 derivative. The classic alpha7 ligand alpha-bungarotoxin binds to alpha1* and alpha9* nAChRs. In contrast, Alexa Fluor 546-ArIB[V11L;V16A] potently (IC(50) 1.8 nM) and selectively blocked alpha7 nAChRs but not alpha1* or alpha9* nAChRs expressed in Xenopus oocytes. Selectivity was further confirmed by competition binding studies of native nAChRs in rat brain membranes. The fluorescence properties of Alexa Fluor 546-ArIB[V11L;V16A] were assessed using human embryonic kidney-293 cells stably transfected with nAChRs; labeling was observed on cells expressing alpha7 but not cells expressing alpha3beta2, alpha3beta4, or alpha4beta2 nAChRs. Further imaging studies demonstrate that Alexa Fluor 546-ArIB[V11L;V16A] labels hippocampal neurons from wild-type mice but not from nAChR alpha7 subunit-null mice. Thus, Alexa Fluor 546-ArIB[V11L;V16A] represents a potent and selective ligand for imaging alpha7 nAChRs.
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Affiliation(s)
- Arik J Hone
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah 84112, USA
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