1
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Souf YM, Lokaj G, Kuruva V, Saed Y, Raviglione D, Brik A, Nicke A, Inguimbert N, Dutertre S. Synthesis and Biological Activity of Novel α-Conotoxins Derived from Endemic Polynesian Cone Snails. Mar Drugs 2023; 21:356. [PMID: 37367681 DOI: 10.3390/md21060356] [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: 05/17/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/28/2023] Open
Abstract
α-Conotoxins are well-known probes for the characterization of the various subtypes of nicotinic acetylcholine receptors (nAChRs). Identifying new α-conotoxins with different pharmacological profiles can provide further insights into the physiological or pathological roles of the numerous nAChR isoforms found at the neuromuscular junction, the central and peripheral nervous systems, and other cells such as immune cells. This study focuses on the synthesis and characterization of two novel α-conotoxins obtained from two species endemic to the Marquesas Islands, namely Conus gauguini and Conus adamsonii. Both species prey on fish, and their venom is considered a rich source of bioactive peptides that can target a wide range of pharmacological receptors in vertebrates. Here, we demonstrate the versatile use of a one-pot disulfide bond synthesis to achieve the α-conotoxin fold [Cys 1-3; 2-4] for GaIA and AdIA, using the 2-nitrobenzyl (NBzl) protecting group of cysteines for effective regioselective oxidation. The potency and selectivity of GaIA and AdIA against rat nicotinic acetylcholine receptors were investigated electrophysiologically and revealed potent inhibitory activities. GaIA was most active at the muscle nAChR (IC50 = 38 nM), whereas AdIA was most potent at the neuronal α6/3 β2β3 subtype (IC50 = 177 nM). Overall, this study contributes to a better understanding of the structure-activity relationships of α-conotoxins, which may help in the design of more selective tools.
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Affiliation(s)
- Yazid Mohamed Souf
- CRIOBE, UAR CNRS-EPHE-UPVD 3278, Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860 Perpignan, France
| | - Gonxhe Lokaj
- Faculty of Medicine, Walther Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Nußbaumstraße 26, 80336 Munich, Germany
| | - Veeresh Kuruva
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200008, Israel
| | - Yakop Saed
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200008, Israel
| | - Delphine Raviglione
- CRIOBE, UAR CNRS-EPHE-UPVD 3278, Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860 Perpignan, France
| | - 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 Maximilian University of Munich, Nußbaumstraße 26, 80336 Munich, Germany
| | - Nicolas Inguimbert
- CRIOBE, UAR CNRS-EPHE-UPVD 3278, Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860 Perpignan, France
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2
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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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3
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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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4
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Straub CJ, Rusali LE, Kremiller KM, Riley AP. What We Have Gained from Ibogaine: α3β4 Nicotinic Acetylcholine Receptor Inhibitors as Treatments for Substance Use Disorders. J Med Chem 2023; 66:107-121. [PMID: 36440853 PMCID: PMC10034762 DOI: 10.1021/acs.jmedchem.2c01562] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
For decades, ibogaine─the main psychoactive alkaloid found in Tabernanthe iboga─has been investigated as a possible treatment for substance use disorders (SUDs) due to its purported ability to interrupt the addictive properties of multiple drugs of abuse. Of the numerous pharmacological actions of ibogaine and its derivatives, the inhibition of α3β4 nicotinic acetylcholine receptors (nAChRs), represents a probable mechanism of action for their apparent anti-addictive activity. In this Perspective, we examine several classes of compounds that have been discovered and developed to target α3β4 nAChRs. Specifically, by focusing on compounds that have proven efficacious in pre-clinical models of drug abuse and have been evaluated clinically, we highlight the promising potential of the α3β4 nAChRs as viable targets to treat a wide array of SUDs. Additionally, we discuss the challenges faced by the existing classes of α3β4 nAChR ligands that must be overcome to develop them into therapeutic treatments.
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Affiliation(s)
- Carolyn J Straub
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
| | - Lisa E Rusali
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
| | - Kyle M Kremiller
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
| | - Andrew P Riley
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
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5
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Liang J, Tae HS, Zhao Z, Li X, Zhang J, Chen S, Jiang T, Adams DJ, Yu R. Mechanism of Action and Structure-Activity Relationship of α-Conotoxin Mr1.1 at the Human α9α10 Nicotinic Acetylcholine Receptor. J Med Chem 2022; 65:16204-16217. [PMID: 36137181 DOI: 10.1021/acs.jmedchem.2c00494] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
α-Conotoxins (α-CTxs) can selectively target nicotinic acetylcholine receptors (nAChRs) and are important drug leads for the treatment of cancer, chronic pain, and neuralgia. Here, we chemically synthesized a formerly defined rat α7 nAChR targeting α-CTx Mr1.1 and evaluated its activity at human nAChRs. Mr1.1 was most potent at the human (h) α9α10 nAChR with a half-maximal inhibitory concentration (IC50) of 92.0 nM. Molecular dynamic simulations suggested that Mr1.1 favorably binds at the α10(+)α9(-) and α9(+)α9(-) sites via hydrogen bonds and salt bridges, stabilizing the channel in a closed conformation. Although Mr1.1 and another antagonist, α-CTx Vc1.1 share high sequence similarity and disulfide-bond framework, Mr1.1 has distinct orientations at hα9α10. Based on the Mr1.1-hα9α10 model, analogues were generated, and the more potent Mr1.1[S4Dap], antagonized hα9α10 with an IC50 of 4.0 nM. Furthermore, Mr1.1[S4Dap] displayed analgesic activity in the rat chronic constriction injury (CCI) pain model and therefore presents a promising drug candidate.
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Affiliation(s)
- Jiazhen Liang
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao266003, China.,Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao266003, China
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales2522, Australia
| | - Zitong Zhao
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao266003, China.,Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao266003, China
| | - Xiao Li
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao266003, China.,Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao266003, China
| | - Jinghui Zhang
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao266003, China.,Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao266003, China
| | - Shen Chen
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao266003, China.,Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao266003, China
| | - Tao Jiang
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao266003, China.,Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao266003, China.,Innovation Center for Marine Drug Screening & Evaluation, Qingdao National Laboratory for Marine Science and Technology, Qingdao266003, China
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales2522, Australia
| | - Rilei Yu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao266003, China.,Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao266003, China.,Innovation Center for Marine Drug Screening & Evaluation, Qingdao National Laboratory for Marine Science and Technology, Qingdao266003, China
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6
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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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7
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Wei N, Chu Y, Liu H, Xu Q, Jiang T, Yu R. Antagonistic Mechanism of α-Conotoxin BuIA toward the Human α3β2 Nicotinic Acetylcholine Receptor. ACS Chem Neurosci 2021; 12:4535-4545. [PMID: 34738810 DOI: 10.1021/acschemneuro.1c00568] [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: 12/22/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels that are abundantly expressed in the central and peripheral nervous systems, playing an important role in mediating neurotransmitter release and inter-synaptic signaling. Dysfunctional nAChRs are associated with neurological disorders, and studying the structure and function of nAChRs is essential for development of drugs or strategies for treatment of related diseases. α-Conotoxins are selective antagonists of the nAChR and are an important class of drug leads. So far, the antagonistic mechanism of α-conotoxins toward the nAChRs is still unclear. In this study, we built an α3β2 nAChR homology model and investigated its conformational transition mechanism upon binding with a highly potent inhibitor, α-conotoxin BuIA, through μs molecular dynamic simulations and site-directed mutagenesis studies. The results suggested that the α3β2 nAChR underwent global conformational transitions and was stabilized into a closed state with three hydrophobic gates present in the transmembrane domain by BuIA. Finally, the probable antagonistic mechanism of BuIA was proposed. Overall, the closed-state model of the α3β2 nAChR bound with BuIA is not only essential for understanding the antagonistic mechanism of α-conotoxins but also particularly valuable for development of therapeutic inhibitors in future.
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Affiliation(s)
- Ningning Wei
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao 266021, China
| | - Yanyan Chu
- Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266200, China
- Molecular Synthesis Center & Key Laboratory of Marine Drugs, Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
- Innovation Platform of Marine Drug Screening & Evaluation, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, Shandong 266100, China
| | - Huijie Liu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao 266021, China
| | - Qingliang Xu
- Molecular Synthesis Center & Key Laboratory of Marine Drugs, Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Tao Jiang
- Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266200, China
- Molecular Synthesis Center & Key Laboratory of Marine Drugs, Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Rilei Yu
- Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266200, China
- Molecular Synthesis Center & Key Laboratory of Marine Drugs, Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
- Innovation Platform of Marine Drug Screening & Evaluation, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, Shandong 266100, China
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8
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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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9
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Ning H, Huang B, Tae HS, Liu Z, Yu S, Li L, Zhang L, Adams DJ, Guo C, Dai Q. α-Conotoxin Bt1.8 from Conus betulinus selectively inhibits α6/α3β2β3 and α3β2 nicotinic acetylcholine receptor subtypes. J Neurochem 2021; 159:90-100. [PMID: 34008858 DOI: 10.1111/jnc.15434] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 04/16/2021] [Accepted: 04/27/2021] [Indexed: 12/01/2022]
Abstract
α-Conotoxins are small disulfide-rich peptides found in the venom of marine cone snails and are potent antagonists of nicotinic acetylcholine receptors (nAChRs). They are valuable pharmacological tools and have potential therapeutic applications for the treatment of chronic pain or neurological diseases and disorders. In the present study, we synthesized and functionally characterized a novel α-conotoxin Bt1.8, which was cloned from Conus betulinus. Bt1.8 selectively inhibited ACh-evoked currents in Xenopus oocytes expressing rat(r) α6/α3β2β3 and rα3β2 nAChRs with an IC50 of 2.1 nM and 9.4 nM, respectively, and similar potency for human (h) α6/α3β2β3 and hα3β2 nAChRs. Additionally, Bt1.8 had higher binding affinity with a slower dissociation rate for the rα6/α3β2β3 subtype compared to rα3β2. The amino acid sequence of Bt1.8 is significantly different from other reported α-conotoxins targeting the two nAChR subtypes. Further Alanine scanning analyses demonstrated that residues Ile9, Leu10, Asn11, Asn12 and Asn14 are critical for its inhibitory activity at the α6/α3β2β3 and α3β2 subtypes. Moreover, the NMR structure of Bt1.8 indicated the presence of a relatively larger hydrophobic zone than other α4/7-conotoxins which may explain its potent inhibition at α6/α3β2β3 nAChRs.
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Affiliation(s)
- Huying Ning
- Beijing Institute of Biotechnology, Beijing, China
| | - Biling Huang
- Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Zhuguo Liu
- Beijing Institute of Biotechnology, Beijing, China
| | - Shuo Yu
- Beijing Institute of Biotechnology, Beijing, China
| | - Liang Li
- Beijing Institute of Biotechnology, Beijing, China
| | | | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Chenyun Guo
- Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Qiuyun Dai
- Beijing Institute of Biotechnology, Beijing, China
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10
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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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11
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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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12
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An Overview of Nicotinic Cholinergic System Signaling in Neurogenesis. Arch Med Res 2020; 51:287-296. [DOI: 10.1016/j.arcmed.2020.03.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 03/13/2020] [Accepted: 03/30/2020] [Indexed: 12/19/2022]
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13
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αM-Conotoxin MIIIJ Blocks Nicotinic Acetylcholine Receptors at Neuromuscular Junctions of Frog and Fish. Toxins (Basel) 2020; 12:toxins12030197. [PMID: 32245200 PMCID: PMC7150935 DOI: 10.3390/toxins12030197] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 03/17/2020] [Accepted: 03/18/2020] [Indexed: 11/16/2022] Open
Abstract
We report the discovery and functional characterization of αM-Conotoxin MIIIJ, a peptide from the venom of the fish-hunting cone snail Conus magus. Injections of αM-MIIIJ induced paralysis in goldfish (Carassius auratus) but not mice. Intracellular recording from skeletal muscles of fish (C. auratus) and frog (Xenopus laevis) revealed that αM-MIIIJ inhibited postsynaptic nicotinic acetylcholine receptors (nAChRs) with an IC50 of ~0.1 μM. With comparable potency, αM-MIIIJ reversibly blocked ACh-gated currents (IACh) of voltage-clamped X. laevis oocytes exogenously expressing nAChRs cloned from zebrafish (Danio rerio) muscle. αM-MIIIJ also protected against slowly-reversible block of IACh by α-bungarotoxin (α-BgTX, a snake neurotoxin) and α-conotoxin EI (α-EI, from Conus ermineus another fish hunter) that competitively block nAChRs at the ACh binding site. Furthermore, assessment by fluorescence microscopy showed that αM-MIIIJ inhibited the binding of fluorescently-tagged α-BgTX at neuromuscular junctions of X. laevis, C. auratus, and D. rerio. (Note, we observed that αM-MIIIJ can block adult mouse and human muscle nAChRs exogenously expressed in X. laevis oocytes, but with IC50s ~100-times higher than those of zebrafish nAChRs.) Taken together, these results indicate that αM-MIIIJ inhibits muscle nAChRs and furthermore apparently does so by interfering with the binding of ACh to its receptor. Comparative alignments with homologous sequences identified in other fish hunters revealed that αM-MIIIJ defines a new class of muscle nAChR inhibitors from cone snails.
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van Hout M, Klein J, Ahring PK, Brown DT, Thaneshwaran S, Dos Santos AB, Jensen AA, Kohlmeier KA, Christophersen P, Dyhring T. Characterization of AN6001, a positive allosteric modulator of α6β2-containing nicotinic acetylcholine receptors. Biochem Pharmacol 2019; 174:113788. [PMID: 31887290 DOI: 10.1016/j.bcp.2019.113788] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 12/23/2019] [Indexed: 01/23/2023]
Abstract
α6β2-Containing nicotinic acetylcholine receptors (α6β2* nAChRs) are predominantly expressed in midbrain dopaminergic neurons, including substantia nigra pars compacta (SNc) neurons and their projections to striatal regions, where they regulate dopamine release and nigrostriatal activity. It is well established that nAChR agonists exert protection against dopaminergic neurotoxicity in cellular assays and parkinsonian animal models. Historically, drug development in the nAChR field has been mostly focused on development of selective agonists and positive allosteric modulators (PAMs) for the predominant neuronal nAChRs, α7 and α4β2. Here, we report the discovery and characterization of AN6001, a novel selective α6β2* nAChR PAM. AN6001 mediated increases in both nicotine potency and efficacy at the human α6/α3β2β3V9'S nAChR in HEK293 cells, and it positively modulated ACh-evoked currents through both α6/α3β2β3V9'S and a concatenated β3-α6-β2-α6-β2 receptor in Xenopus oocytes, displaying EC50 values of 0.58 µM and 0.40 µM, respectively. In contrast, the compound did not display significant modulatory activity at α4β2, α3β4, α7 and muscle nAChRs. AN6001 also increased agonist-induced dopamine release from striatal synaptosomes and augmented agonist-induced global cellular responses and inward currents in dopaminergic neurons in SNc slices (measured by Ca2+ imaging and patch clamp recordings, respectively). Finally, AN6001 potentiated the neuroprotective effect of nicotine at MPP+-treated primary dopaminergic neurons. Overall, our studies demonstrate the existence of allosteric sites on α6β2* nAChRs and that positive modulation of native α6β2* receptors strengthens DA signaling. Hence, AN6001 represents an important tool for studies of α6β2* nAChRs and furthermore underlines the therapeutic potential in these receptors in Parkinson's disease.
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Affiliation(s)
- Marloes van Hout
- Saniona A/S, Ballerup, Denmark; Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | | | - Philip K Ahring
- Saniona A/S, Ballerup, Denmark; School of Pharmacy, Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | | | - Siganya Thaneshwaran
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Altair B Dos Santos
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Kristi A Kohlmeier
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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15
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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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16
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Morales Duque H, Campos Dias S, Franco OL. Structural and Functional Analyses of Cone Snail Toxins. Mar Drugs 2019; 17:md17060370. [PMID: 31234371 PMCID: PMC6628382 DOI: 10.3390/md17060370] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 06/16/2019] [Accepted: 06/17/2019] [Indexed: 12/12/2022] Open
Abstract
Cone snails are marine gastropod mollusks with one of the most powerful venoms in nature. The toxins, named conotoxins, must act quickly on the cone snails´ prey due to the fact that snails are extremely slow, reducing their hunting capability. Therefore, the characteristics of conotoxins have become the object of investigation, and as a result medicines have been developed or are in the trialing process. Conotoxins interact with transmembrane proteins, showing specificity and potency. They target ion channels and ionotropic receptors with greater regularity, and when interaction occurs, there is immediate physiological decompensation. In this review we aimed to evaluate the structural features of conotoxins and the relationship with their target types.
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Affiliation(s)
- Harry Morales Duque
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
| | - Simoni Campos Dias
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
| | - Octávio Luiz Franco
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
- S-inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande-MS 79.117-900, Brazil.
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17
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Mutagenesis of α-Conotoxins for Enhancing Activity and Selectivity for Nicotinic Acetylcholine Receptors. Toxins (Basel) 2019; 11:toxins11020113. [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] [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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18
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Rationally Designed α-Conotoxin Analogues Maintained Analgesia Activity and Weakened Side Effects. Molecules 2019; 24:molecules24020337. [PMID: 30669328 PMCID: PMC6358911 DOI: 10.3390/molecules24020337] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/05/2019] [Accepted: 01/17/2019] [Indexed: 11/16/2022] Open
Abstract
A lack of specificity is restricting the further application of conotoxin from Conus bullatus (BuIA). In this study, an analogue library of BuIA was established and virtual screening was used, which identified high α7 nicotinic acetylcholine receptor (nAChR)-selectivity analogues. The analogues were synthesized and tested for their affinity to functional human α7 nAChR and for the regulation of intracellular calcium ion capacity in neurons. Immunofluorescence, flow cytometry, and patch clamp results showed that the analogues maintained their capacity for calcium regulation. The results of the hot-plate model and paclitaxel-induced peripheral neuropathy model indicated that, when compared with natural BuIA, the analgesia activities of the analogues in different models were maintained. To analyze the adverse effects and toxicity of BuIA and its analogues, the tail suspension test, forced swimming test, and open field test were used. The results showed that the safety and toxicity of the analogues were significantly better than BuIA. The analogues of BuIA with an appropriate and rational mutation showed high selectivity and maintained the regulation of Ca2+ capacity in neurons and activities of analgesia, whereas the analogues demonstrated that the adverse effects of natural α-conotoxins could be reduced.
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19
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Toxins as tools: Fingerprinting neuronal pharmacology. Neurosci Lett 2018; 679:4-14. [DOI: 10.1016/j.neulet.2018.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 01/09/2018] [Accepted: 02/02/2018] [Indexed: 12/30/2022]
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20
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Ren J, Li R, Ning J, Zhu X, Zhangsun D, Wu Y, Luo S. Effect of Methionine Oxidation and Substitution of α-Conotoxin TxID on α3β4 Nicotinic Acetylcholine Receptor. Mar Drugs 2018; 16:md16060215. [PMID: 29925760 PMCID: PMC6025358 DOI: 10.3390/md16060215] [Citation(s) in RCA: 6] [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: 05/21/2018] [Revised: 06/05/2018] [Accepted: 06/15/2018] [Indexed: 12/24/2022] Open
Abstract
α-Conotoxin TxID was discovered from Conus textile by gene cloning, which has 4/6 inter-cysteine loop spacing and selectively inhibits α3β4 nicotinic acetylcholine receptor (nAChR) subtype. However, TxID is susceptible to modification due to it containing a methionine (Met) residue that easily forms methionine sulfoxide (MetO) in oxidative environment. In this study, we investigated how Met-11 and its derivatives affect the activity of TxID using a combination of electrophysiological recordings and molecular modelling. The results showed most TxID analogues had substantially decreased activities on α3β4 nAChR with more than 10-fold potency loss and 5 of them demonstrated no inhibition on α3β4 nAChR. However, one mutant, [M11I]TxID, displayed potent inhibition at α3β4 nAChR with an IC50 of 69 nM, which only exhibited 3.8-fold less compared with TxID. Molecular dynamics simulations were performed to expound the decrease in the affinity for α3β4 nAChR. The results indicate replacement of Met with a hydrophobic moderate-sized Ile in TxID is an alternative strategy to reduce the impact of Met oxidation, which may help to redesign conotoxins containing methionine residue.
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Affiliation(s)
- Jie Ren
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
- Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Rui Li
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Jiong Ning
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Yong Wu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Sulan Luo
- 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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21
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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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22
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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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23
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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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Cuny H, Yu R, Tae HS, Kompella SN, Adams DJ. α-Conotoxins active at α3-containing nicotinic acetylcholine receptors and their molecular determinants for selective inhibition. Br J Pharmacol 2017; 175:1855-1868. [PMID: 28477355 DOI: 10.1111/bph.13852] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 04/13/2017] [Accepted: 04/24/2017] [Indexed: 01/22/2023] Open
Abstract
Neuronal α3-containing nicotinic acetylcholine receptors (nAChRs) in the peripheral nervous system (PNS) and non-neuronal tissues are implicated in a number of severe disease conditions ranging from cancer to cardiovascular diseases and chronic pain. However, despite the physiological characterization of mouse models and cell lines, the precise pathophysiology of nAChRs outside the CNS remains not well understood, in part because there is a lack of subtype-selective antagonists. α-Conotoxins isolated from cone snail venom exhibit characteristic individual selectivity profiles for nAChRs and, therefore, are excellent tools to study the determinants for nAChR-antagonist interactions. Given that human α3β4 subtype selective α-conotoxins are scarce and this is a major nAChR subtype in the PNS, the design of new peptides targeting this nAChR subtype is desirable. Recent studies using α-conotoxins RegIIA and AuIB, in combination with nAChR site-directed mutagenesis and computational modelling, have shed light onto specific nAChR residues, which determine the selectivity of the α-conotoxins for the human α3β2 and α3β4 subtypes. Publications describing the selectivity profile and binding sites of other α-conotoxins confirm that subtype-selective nAChR antagonists often work through common mechanisms by interacting with the same structural components and sites on the receptor. 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)
- Hartmut Cuny
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia.,Victor Chang Cardiac Research Institute, Developmental and Stem Cell Biology Division, Sydney, NSW, Australia
| | - Rilei Yu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China.,Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Shiva N Kompella
- Faculty of Pharmacy, University of Sydney, Sydney, NSW, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
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25
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Abraham N, Healy M, Ragnarsson L, Brust A, Alewood PF, Lewis RJ. Structural mechanisms for α-conotoxin activity at the human α3β4 nicotinic acetylcholine receptor. Sci Rep 2017; 7:45466. [PMID: 28361878 PMCID: PMC5374441 DOI: 10.1038/srep45466] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 03/01/2017] [Indexed: 01/22/2023] Open
Abstract
Nicotinic acetylcholine receptors (nAChR) are therapeutic targets for a range of human diseases. α-Conotoxins are naturally occurring peptide antagonists of nAChRs that have been used as pharmacological probes and investigated as drug leads for nAChR related disorders. However, α-conotoxin interactions have been mostly characterised at the α7 and α3β2 nAChRs, with interactions at other subtypes poorly understood. This study provides novel structural insights into the molecular basis for α-conotoxin activity at α3β4 nAChR, a therapeutic target where subtype specific antagonists have potential to treat nicotine addiction and lung cancer. A co-crystal structure of α-conotoxin LsIA with Lymnaea stagnalis acetylcholine binding protein guided the design and functional characterisations of LsIA analogues that identified the minimum pharmacophore regulating α3β4 antagonism. Interactions of the LsIA R10F with β4 K57 and the conserved -NN- α-conotoxin motif with β4 I77 and I109 conferred α3β4 activity to the otherwise inactive LsIA. Using these structural insights, we designed LsIA analogues with α3β4 activity. This new understanding of the structural basis of protein-protein interactions between α-conotoxins and α3β4 may help rationally guide the development of α3β4 selective antagonists with therapeutic potential.
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Affiliation(s)
- Nikita Abraham
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Michael Healy
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Lotten Ragnarsson
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Andreas Brust
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Paul F Alewood
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Richard J Lewis
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
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Gorson J, Holford M. Small Packages, Big Returns: Uncovering the Venom Diversity of Small Invertebrate Conoidean Snails. Integr Comp Biol 2016; 56:962-972. [PMID: 27371389 PMCID: PMC6058754 DOI: 10.1093/icb/icw063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Venomous organisms used in research were historically chosen based on size and availability. This opportunity-driven strategy created a species bias in which snakes, scorpions, and spiders became the primary subjects of venom research. Increasing technological advancements have enabled interdisciplinary studies using genomics, transcriptomics, and proteomics to expand venom investigation to animals that produce small amounts of venom or lack traditional venom producing organs. One group of non-traditional venomous organisms that have benefitted from the rise of -omic technologies is the Conoideans. The Conoidean superfamily of venomous marine snails includes, the Terebridae, Turridae (s.l), and Conidae. Conoidea venom is used for both predation and defense, and therefore under strong selection pressures. The need for conoidean venom peptides to be potent and specific to their molecular targets has made them important tools for investigating cellular physiology and bioactive compounds that are beneficial to improving human health. A convincing case for the potential of Conoidean venom is made with the first commercially available conoidean venom peptide drug Ziconotide (Prialt®), an analgesic derived from Conus magus venom that is used to treat chronic pain in HIV and cancer patients. Investigation of conoidean venom using -omics technology provides significant insights into predator-driven diversification in biodiversity and identifies novel compounds for manipulating cellular communication, especially as it pertains to disease and disorders.
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Affiliation(s)
- J Gorson
- *Department of Chemistry, Hunter College, The City University of New York, Belfer Research Building, NY, 10021 USA
- Departments of Biology, Chemistry, and Biochemistry, The Graduate City, The City University of New York, NY, 10016 USA
- Invertebrate Zoology, Sackler Institute of Comparative Genomics, American Museum of Natural History, NY, 10024 USA
| | - M Holford
- *Department of Chemistry, Hunter College, The City University of New York, Belfer Research Building, NY, 10021 USA
- Departments of Biology, Chemistry, and Biochemistry, The Graduate City, The City University of New York, NY, 10016 USA
- Invertebrate Zoology, Sackler Institute of Comparative Genomics, American Museum of Natural History, NY, 10024 USA
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Cuny H, Kompella SN, Tae HS, Yu R, Adams DJ. Key Structural Determinants in the Agonist Binding Loops of Human β2 and β4 Nicotinic Acetylcholine Receptor Subunits Contribute to α3β4 Subtype Selectivity of α-Conotoxins. J Biol Chem 2016; 291:23779-23792. [PMID: 27646000 DOI: 10.1074/jbc.m116.730804] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Indexed: 12/16/2022] Open
Abstract
α-Conotoxins represent a large group of pharmacologically active peptides that antagonize nicotinic acetylcholine receptors (nAChRs). The α3β4 nAChR, a predominant subtype in the peripheral nervous system, has been implicated in various pathophysiological conditions. As many α-conotoxins have multiple pharmacological targets, compounds specifically targeting individual nAChR subtypes are needed. In this study, we performed mutational analyses to evaluate the key structural components of human β2 and β4 nAChR subunits that determine α-conotoxin selectivity for α3β4 nAChR. α-Conotoxin RegIIA was used to evaluate the impact of non-conserved human β2 and β4 residues on peptide affinity. Two mutations, α3β2[T59K] and α3β2[S113R], strongly enhanced RegIIA affinity compared with wild-type α3β2, as seen by substantially increased inhibitory potency and slower off-rate kinetics. Opposite point mutations in α3β4 had the contrary effect, emphasizing the importance of loop D residue 59 and loop E residue 113 as determinants for RegIIA affinity. Molecular dynamics simulation revealed the side chains of β4 Lys59 and β4 Arg113 formed hydrogen bonds with RegIIA loop 2 atoms, whereas the β2 Thr59 and β2 Ser113 side chains were not long enough to form such interactions. Residue β4 Arg113 has been identified for the first time as a crucial component facilitating antagonist binding. Another α-conotoxin, AuIB, exhibited low activity at human α3β2 and α3β4 nAChRs. Molecular dynamics simulation indicated the key interactions with the β subunit are different to RegIIA. Taken together, these data elucidate the interactions with specific individual β subunit residues that critically determine affinity and pharmacological activity of α-conotoxins RegIIA and AuIB at human nAChRs.
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Affiliation(s)
- Hartmut Cuny
- From the Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia.,the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia, and
| | - Shiva N Kompella
- the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia, and
| | - Han-Shen Tae
- From the Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Rilei Yu
- the Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - David J Adams
- From the Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia, .,the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia, and
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28
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Peng C, Yao G, Gao BM, Fan CX, Bian C, Wang J, Cao Y, Wen B, Zhu Y, Ruan Z, Zhao X, You X, Bai J, Li J, Lin Z, Zou S, Zhang X, Qiu Y, Chen J, Coon SL, Yang J, Chen JS, Shi Q. High-throughput identification of novel conotoxins from the Chinese tubular cone snail (Conus betulinus) by multi-transcriptome sequencing. Gigascience 2016; 5:17. [PMID: 27087938 PMCID: PMC4832519 DOI: 10.1186/s13742-016-0122-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 04/07/2016] [Indexed: 01/06/2023] Open
Abstract
Background The venom of predatory marine cone snails mainly contains a diverse array of unique bioactive peptides commonly referred to as conopeptides or conotoxins. These peptides have proven to be valuable pharmacological probes and potential drugs because of their high specificity and affinity to important ion channels, receptors and transporters of the nervous system. Most previous studies have focused specifically on the conopeptides from piscivorous and molluscivorous cone snails, but little attention has been devoted to the dominant vermivorous species. Results The vermivorous Chinese tubular cone snail, Conus betulinus, is the dominant Conus species inhabiting the South China Sea. The transcriptomes of venom ducts and venom bulbs from a variety of specimens of this species were sequenced using both next-generation sequencing and traditional Sanger sequencing technologies, resulting in the identification of a total of 215 distinct conopeptides. Among these, 183 were novel conopeptides, including nine new superfamilies. It appeared that most of the identified conopeptides were synthesized in the venom duct, while a handful of conopeptides were identified only in the venom bulb and at very low levels. Conclusions We identified 215 unique putative conopeptide transcripts from the combination of five transcriptomes and one EST sequencing dataset. Variation in conopeptides from different specimens of C. betulinus was observed, which suggested the presence of intraspecific variability in toxin production at the genetic level. These novel conopeptides provide a potentially fertile resource for the development of new pharmaceuticals, and a pathway for the discovery of new conotoxins. Electronic supplementary material The online version of this article (doi:10.1186/s13742-016-0122-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chao Peng
- BGI-Shenzhen, Shenzhen, 518083 China
| | - Ge Yao
- Research Institute of Pharmaceutical Chemistry, Beijing, 102205 China
| | - Bing-Miao Gao
- School of Pharmaceutical Sciences, Hainan Medical University, Haikou, 571199 China
| | - Chong-Xu Fan
- Research Institute of Pharmaceutical Chemistry, Beijing, 102205 China
| | - Chao Bian
- BGI-Shenzhen, Shenzhen, 518083 China ; Shenzhen Key Laboratory of Marine Genomics, Guangdong Provincial Key Laboratory of Molecular Breeding in Marine Economic Animals, State Key Laboratory of Agricultural Genomics, Shenzhen, 518083 China
| | | | - Ying Cao
- Research Institute of Pharmaceutical Chemistry, Beijing, 102205 China
| | - Bo Wen
- BGI-Shenzhen, Shenzhen, 518083 China
| | | | - Zhiqiang Ruan
- BGI-Shenzhen, Shenzhen, 518083 China ; Shenzhen Key Laboratory of Marine Genomics, Guangdong Provincial Key Laboratory of Molecular Breeding in Marine Economic Animals, State Key Laboratory of Agricultural Genomics, Shenzhen, 518083 China
| | | | - Xinxin You
- BGI-Shenzhen, Shenzhen, 518083 China ; Shenzhen Key Laboratory of Marine Genomics, Guangdong Provincial Key Laboratory of Molecular Breeding in Marine Economic Animals, State Key Laboratory of Agricultural Genomics, Shenzhen, 518083 China
| | - Jie Bai
- BGI-Shenzhen, Shenzhen, 518083 China ; Shenzhen Key Laboratory of Marine Genomics, Guangdong Provincial Key Laboratory of Molecular Breeding in Marine Economic Animals, State Key Laboratory of Agricultural Genomics, Shenzhen, 518083 China
| | - Jia Li
- BGI-Shenzhen, Shenzhen, 518083 China ; Shenzhen Key Laboratory of Marine Genomics, Guangdong Provincial Key Laboratory of Molecular Breeding in Marine Economic Animals, State Key Laboratory of Agricultural Genomics, Shenzhen, 518083 China
| | | | | | - Xinhui Zhang
- BGI-Shenzhen, Shenzhen, 518083 China ; Shenzhen Key Laboratory of Marine Genomics, Guangdong Provincial Key Laboratory of Molecular Breeding in Marine Economic Animals, State Key Laboratory of Agricultural Genomics, Shenzhen, 518083 China
| | - Ying Qiu
- BGI-Shenzhen, Shenzhen, 518083 China ; Shenzhen Key Laboratory of Marine Genomics, Guangdong Provincial Key Laboratory of Molecular Breeding in Marine Economic Animals, State Key Laboratory of Agricultural Genomics, Shenzhen, 518083 China
| | - Jieming Chen
- BGI-Shenzhen, Shenzhen, 518083 China ; Shenzhen Key Laboratory of Marine Genomics, Guangdong Provincial Key Laboratory of Molecular Breeding in Marine Economic Animals, State Key Laboratory of Agricultural Genomics, Shenzhen, 518083 China
| | - Steven L Coon
- Molecular Genomics Laboratory, National Institutes of Health, Bethesda, MD 20892 USA
| | - Jiaan Yang
- Micro Pharmatech Ltd, Wuhan, 430075 China
| | - Ji-Sheng Chen
- Research Institute of Pharmaceutical Chemistry, Beijing, 102205 China
| | - Qiong Shi
- BGI-Shenzhen, Shenzhen, 518083 China ; Shenzhen Key Laboratory of Marine Genomics, Guangdong Provincial Key Laboratory of Molecular Breeding in Marine Economic Animals, State Key Laboratory of Agricultural Genomics, Shenzhen, 518083 China ; BGI-Zhenjiang Institute of Hydrobiology, Zhenjiang, 212000 China
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Zhu X, Bi J, Yu J, Li X, Zhang Y, Zhangsun D, Luo S. Recombinant Expression and Characterization of α-Conotoxin LvIA in Escherichia coli. Mar Drugs 2016; 14:11. [PMID: 26742048 PMCID: PMC4728508 DOI: 10.3390/md14010011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 12/11/2015] [Accepted: 12/28/2015] [Indexed: 01/17/2023] Open
Abstract
α-Conotoxin LvIA is derived from Conus lividus, native to Hainan, and is the most selective inhibitor of α3β2 nicotinic acetylcholine receptors (nAChRs) known to date. In this study, an efficient approach for the production of recombinant α-Conotoxin LvIA is described. Tandem repeats of a LvIA gene fragment were constructed and fused with a KSI gene and a His6 tag in a Escherichia coli (E. coli) expression vector pET-31b(+). The recombinant plasmids were transformed into E. coli and were found to express well. The KSI-(LvIA)n-His6 fusion protein was purified by metal affinity chromatography and then cleaved with CNBr to release recombinant LvIA (rLvIA). High yields of fusion protein ranging from 100 to 500 mg/L culture were obtained. The pharmacological profile of rLvIA was determined by two-electrode voltage-clamp electrophysiology in Xenopus laevis oocytes expressing rat nAChR subtypes. The rLvIA antagonized the α3β2 nAChR subtype selectively with a nano-molar IC50. The rLvIA was analgesic in a mouse hot-plate test model of pain. Overall, this study provides an effective method to synthesize α-conotoxin LvIA in an E. coli recombinant expression system, and this approach could be useful to obtain active conopeptides in large quantity and at low cost.
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Affiliation(s)
- Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
- College of Horticulture and Landscapes, Hainan University, Haikou 570228, China.
- College of Marine Science, Hainan University, Haikou 570228, China.
| | - Jianpeng Bi
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Jinpeng Yu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Xiaodan Li
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Yaning Zhang
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
- College of Marine Science, Hainan University, Haikou 570228, China.
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China.
- College of Marine Science, Hainan University, Haikou 570228, China.
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Cloning, synthesis, and characterization of αO-conotoxin GeXIVA, a potent α9α10 nicotinic acetylcholine receptor antagonist. Proc Natl Acad Sci U S A 2015; 112:E4026-35. [PMID: 26170295 DOI: 10.1073/pnas.1503617112] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We identified a previously unidentified conotoxin gene from Conus generalis whose precursor signal sequence has high similarity to the O1-gene conotoxin superfamily. The predicted mature peptide, αO-conotoxin GeXIVA (GeXIVA), has four Cys residues, and its three disulfide isomers were synthesized. Previously pharmacologically characterized O1-superfamily peptides, exemplified by the US Food and Drug Administration-approved pain medication, ziconotide, contain six Cys residues and are calcium, sodium, or potassium channel antagonists. However, GeXIVA did not inhibit calcium channels but antagonized nicotinic AChRs (nAChRs), most potently on the α9α10 nAChR subtype (IC50 = 4.6 nM). Toxin blockade was voltage-dependent, and kinetic analysis of toxin dissociation indicated that the binding site of GeXIVA does not overlap with the binding site of the competitive antagonist α-conotoxin RgIA. Surprisingly, the most active disulfide isomer of GeXIVA is the bead isomer, comprising, according to NMR analysis, two well-resolved but uncoupled disulfide-restrained loops. The ribbon isomer is almost as potent but has a more rigid structure built around a short 310-helix. In contrast to most α-conotoxins, the globular isomer is the least potent and has a flexible, multiconformational nature. GeXIVA reduced mechanical hyperalgesia in the rat chronic constriction injury model of neuropathic pain but had no effect on motor performance, warranting its further investigation as a possible therapeutic agent.
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Wang S, Zhao C, Liu Z, Wang X, Liu N, Du W, Dai Q. Structural and Functional Characterization of a Novel α-Conotoxin Mr1.7 from Conus marmoreus Targeting Neuronal nAChR α3β2, α9α10 and α6/α3β2β3 Subtypes. Mar Drugs 2015; 13:3259-75. [PMID: 26023835 PMCID: PMC4483627 DOI: 10.3390/md13063259] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 05/11/2015] [Indexed: 12/26/2022] Open
Abstract
In the present study, we synthesized and, structurally and functionally characterized a novel α4/7-conotoxin Mr1.7 (PECCTHPACHVSHPELC-NH2), which was previously identified by cDNA libraries from Conus marmoreus in our lab. The NMR solution structure showed that Mr1.7 contained a 310-helix from residues Pro7 to His10 and a type I β-turn from residues Pro14 to Cys17. Electrophysiological results showed that Mr1.7 selectively inhibited the α3β2, α9α10 and α6/α3β2β3 neuronal nicotinic acetylcholine receptors (nAChRs) with an IC50 of 53.1 nM, 185.7 nM and 284.2 nM, respectively, but showed no inhibitory activity on other nAChR subtypes. Further structure-activity studies of Mr1.7 demonstrated that the PE residues at the N-terminal sequence of Mr1.7 were important for modulating its selectivity, and the replacement of Glu2 by Ala resulted in a significant increase in potency and selectivity to the α3β2 nAChR. Furthermore, the substitution of Ser12 with Asn in the loop2 significantly increased the binding of Mr1.7 to α3β2, α3β4, α2β4 and α7 nAChR subtypes. Taken together, this work expanded our knowledge of selectivity and provided a new way to improve the potency and selectivity of inhibitors for nAChR subtypes.
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Affiliation(s)
- Shuo Wang
- Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Cong Zhao
- Department of Chemistry, Renmin University of China, Beijing 100872, China.
| | - Zhuguo Liu
- Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Xuesong Wang
- Department of Chemistry, Renmin University of China, Beijing 100872, China.
| | - Na Liu
- Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Weihong Du
- Department of Chemistry, Renmin University of China, Beijing 100872, China.
| | - Qiuyun Dai
- Beijing Institute of Biotechnology, Beijing 100071, China.
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Zhangsun D, Zhu X, Wu Y, Hu Y, Kaas Q, Craik DJ, McIntosh JM, Luo S. Key residues in the nicotinic acetylcholine receptor β2 subunit contribute to α-conotoxin LvIA binding. J Biol Chem 2015; 290:9855-62. [PMID: 25713061 DOI: 10.1074/jbc.m114.632646] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Indexed: 12/15/2022] Open
Abstract
α-Conotoxin LvIA (α-CTx LvIA) is a small peptide from the venom of the carnivorous marine gastropod Conus lividus and is the most selective inhibitor of α3β2 nicotinic acetylcholine receptors (nAChRs) known to date. It can distinguish the α3β2 nAChR subtype from the α6β2* (* indicates the other subunit) and α3β4 nAChR subtypes. In this study, we performed mutational studies to assess the influence of residues of the β2 subunit versus those of the β4 subunit on the binding of α-CTx LvIA. Although two β2 mutations, α3β2[F119Q] and α3β2[T59K], strongly enhanced the affinity of LvIA, the β2 mutation α3β2[V111I] substantially reduced the binding of LvIA. Increased activity of LvIA was also observed when the β2-T59L mutant was combined with the α3 subunit. There were no significant difference in inhibition of α3β2[T59I], α3β2[Q34A], and α3β2[K79A] nAChRs when compared with wild-type α3β2 nAChR. α-CTx LvIA displayed slower off-rate kinetics at α3β2[F119Q] and α3β2[T59K] than at the wild-type receptor, with the latter mutant having the most pronounced effect. Taken together, these data provide evidence that the β2 subunit contributes to α-CTx LvIA binding and selectivity. The results demonstrate that Val(111) is critical and facilitates LvIA binding; this position has not previously been identified as important to binding of other 4/7 framework α-conotoxins. Thr(59) and Phe(119) of the β2 subunit appear to interfere with LvIA binding, and their replacement by the corresponding residues of the β4 subunit leads to increased affinity.
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Affiliation(s)
- Dongting Zhangsun
- From the Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Xiaopeng Zhu
- From the Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Yong Wu
- From the Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Yuanyan Hu
- From the Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Quentin Kaas
- the Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072 Australia, and
| | - David J Craik
- the Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072 Australia, and
| | - J Michael McIntosh
- the George E. Wahlen Veterans Affairs Medical Center and Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah 84112
| | - Sulan Luo
- From the 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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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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Kompella SN, Hung A, Clark RJ, Marí F, Adams DJ. Alanine scan of α-conotoxin RegIIA reveals a selective α3β4 nicotinic acetylcholine receptor antagonist. J Biol Chem 2014; 290:1039-48. [PMID: 25411242 DOI: 10.1074/jbc.m114.605592] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of the α3β4 nicotinic acetylcholine receptor (nAChR) subtype has recently been implicated in the pathophysiology of various conditions, including development and progression of lung cancer and in nicotine addiction. As selective α3β4 nAChR antagonists, α-conotoxins are valuable tools to evaluate the functional roles of this receptor subtype. We previously reported the discovery of a new α4/7-conotoxin, RegIIA. RegIIA was isolated from Conus regius and inhibits acetylcholine (ACh)-evoked currents mediated by α3β4, α3β2, and α7 nAChR subtypes. The current study used alanine scanning mutagenesis to understand the selectivity profile of RegIIA at the α3β4 nAChR subtype. [N11A] and [N12A] RegIIA analogs exhibited 3-fold more selectivity for the α3β4 than the α3β2 nAChR subtype. We also report synthesis of [N11A,N12A]RegIIA, a selective α3β4 nAChR antagonist (IC50 of 370 nM) that could potentially be used in the treatment of lung cancer and nicotine addiction. Molecular dynamics simulations of RegIIA and [N11A,N12A]RegIIA bound to α3β4 and α3β2 suggest that destabilization of toxin contacts with residues at the principal and complementary faces of α3β2 (α3-Tyr(92), Ser(149), Tyr(189), Cys(192), and Tyr(196); β2-Trp(57), Arg(81), and Phe(119)) may form the molecular basis for the selectivity shift.
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Affiliation(s)
- Shiva N Kompella
- From the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia
| | - Andrew Hung
- From the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia
| | - Richard J Clark
- the School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia, and
| | - Frank Marí
- the Department of Chemistry & Biochemistry, Florida Atlantic University, Boca Raton, Florida 33431
| | - David J Adams
- From the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia,
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Natural products from marine organisms with neuroprotective activity in the experimental models of Alzheimer's disease, Parkinson's disease and ischemic brain stroke: their molecular targets and action mechanisms. Arch Pharm Res 2014; 38:139-70. [PMID: 25348867 DOI: 10.1007/s12272-014-0503-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/14/2014] [Indexed: 12/20/2022]
Abstract
Continuous increases in the incidence of neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and brain stroke demand the urgent development of therapeutics. Marine organisms are well-known producers of natural products with diverse structures and pharmacological activities. Therefore, researchers have endeavored to identify marine natural products with neuroprotective effects. In this regard, this review summarizes therapeutic targets for AD, PD, and ischemic brain stroke and marine natural products with pharmacological activities on the targets according to taxonomies of marine organisms. Furthermore, several marine natural products on the clinical trials for the treatment of neurological disorders are discussed.
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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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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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38
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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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39
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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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40
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Luo S, Zhangsun D, Zhu X, Wu Y, Hu Y, Christensen S, Harvey PJ, Akcan M, Craik DJ, McIntosh JM. Characterization of a novel α-conotoxin TxID from Conus textile that potently blocks rat α3β4 nicotinic acetylcholine receptors. J Med Chem 2013; 56:9655-63. [PMID: 24200193 DOI: 10.1021/jm401254c] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The α3β4 nAChRs are implicated in pain sensation in the PNS and addiction to nicotine in the CNS. We identified an α-4/6-conotoxin (CTx) TxID from Conus textile. The new toxin consists of 15 amino acid residues with two disulfide bonds. TxID was synthesized using solid phase methods, and the synthetic peptide was functionally tested on nAChRs heterologously expressed in Xenopus laevis oocytes. TxID blocked rat α3β4 nAChRs with a 12.5 nM IC50, which places it among the most potent α3β4 nAChR antagonists. TxID also blocked the closely related α6/α3β4 with a 94 nM IC50 but showed little activity on other nAChR subtypes. NMR analysis showed that two major structural isomers exist in solution, one of which adopts a regular α-CTx fold but with different surface charge distribution to other 4/6 family members. α-CTx TxID is a novel tool with which to probe the structure and function of α3β4 nAChRs.
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Affiliation(s)
- Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drug of Haikou, Hainan University , Haikou Hainan, 570228, China
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41
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Grishin AA, Cuny H, Hung A, Clark RJ, Brust A, Akondi K, Alewood PF, Craik DJ, Adams DJ. Identifying key amino acid residues that affect α-conotoxin AuIB inhibition of α3β4 nicotinic acetylcholine receptors. J Biol Chem 2013; 288:34428-42. [PMID: 24100032 DOI: 10.1074/jbc.m113.512582] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
α-Conotoxin AuIB is a selective α3β4 nicotinic acetylcholine receptor (nAChR) subtype inhibitor. Its analgesic properties are believed to result from it activating GABAB receptors and subsequently inhibiting CaV2.2 voltage-gated calcium channels. The structural determinants that mediate diverging AuIB activity at these targets are unknown. We performed alanine scanning mutagenesis of AuIB and α3β4 nAChR, homology modeling, and molecular dynamics simulations to identify the structural determinants of the AuIB·α3β4 nAChR interaction. Two alanine-substituted AuIB analogues, [P6A]AuIB and [F9A]AuIB, did not inhibit the α3β4 nAChR. NMR and CD spectroscopy studies demonstrated that [F9A]AuIB retains its native globular structure, so its activity loss is probably due to loss of specific toxin-receptor residue pairwise contacts. Compared with AuIB, the concentration-response curve for inhibition of α3β4 by [F9A]AuIB shifted rightward more than 10-fold, and its subtype selectivity profile changed. Homology modeling and molecular dynamics simulations suggest that Phe-9 of AuIB interacts with a two-residue binding pocket on the β4 nAChR subunit. This hypothesis was confirmed by site-directed mutagenesis of the β4-Trp-59 and β4-Lys-61 residues of loop D, which form a putative binding pocket. AuIB analogues with Phe-9 substitutions corroborated the finding of a binding pocket on the β4 subunit and gave further insight into how AuIB Phe-9 interacts with the β4 subunit. In summary, we identified critical residues that mediate interactions between AuIB and its cognate nAChR subtype. These findings might help improve the design of analgesic conopeptides that selectively "avoid" nAChR receptors while targeting receptors involved with nociception.
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Affiliation(s)
- Anton A Grishin
- From the Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia and
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42
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Quinton L, Servent D, Girard E, Molgó J, Le Caer JP, Malosse C, Haidar EA, Lecoq A, Gilles N, Chamot-Rooke J. Identification and functional characterization of a novel α-conotoxin (EIIA) from Conus ermineus. Anal Bioanal Chem 2013; 405:5341-51. [PMID: 23584713 DOI: 10.1007/s00216-013-6926-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/14/2013] [Accepted: 03/18/2013] [Indexed: 01/22/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are one of the most important families in the ligand-gated ion channel superfamily due to their involvement in primordial brain functions and in several neurodegenerative pathologies. The discovery of new ligands which can bind with high affinity and selectivity to nAChR subtypes is of prime interest in order to study these receptors and to potentially discover new drugs for treating various pathologies. Predatory cone snails of the genus Conus hunt their prey using venoms containing a large number of small, highly structured peptides called conotoxins. Conotoxins are classified in different structural families and target a large panel of receptors and ion channels. Interestingly, nAChRs represent the only subgroup for which Conus has developed seven distinct families of conotoxins. Conus venoms have thus received much attention as they could represent a potential source of selective ligands of nAChR subtypes. We describe the mass spectrometric-based approaches which led to the discovery of a novel α-conotoxin targeting muscular nAChR from the venom of Conus ermineus. The presence of several posttranslational modifications complicated the N-terminal sequencing. To discriminate between the different possible sequences, analogs with variable N-terminus were synthesized and fragmented by MS/MS. Understanding the fragmentation pathways in the low m/z range appeared crucial to determine the right sequence. The biological activity of this novel α-conotoxin (α-EIIA) that belongs to the unusual α4/4 subfamily was determined by binding experiments. The results revealed not only its selectivity for the muscular nAChR, but also a clear discrimination between the two binding sites described for this receptor.
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Affiliation(s)
- Loïc Quinton
- Laboratoire des Mécanismes Réactionnels, Département de Chimie, Ecole Polytechnique, CNRS UMR7651, 91128 Palaiseau Cedex, France
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43
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Luo S, Zhangsun D, Wu Y, Zhu X, Hu Y, McIntyre M, Christensen S, Akcan M, Craik DJ, McIntosh JM. Characterization of a novel α-conotoxin from conus textile that selectively targets α6/α3β2β3 nicotinic acetylcholine receptors. J Biol Chem 2012. [PMID: 23184959 DOI: 10.1074/jbc.m112.427898] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
α6β2 Nicotinic acetylcholine receptors (nAChRs) expressed by dopaminergic neurons in the CNS are potential therapeutic targets for the treatment of several neuropsychiatric diseases, including nicotine addiction and Parkinson disease. However, recent studies indicate that the α6 subunit can also associate with the β4 subunit to form α6β4 nAChRs that are difficult to pharmacologically distinguish from α6β2, α3β4, and α3β2 subtypes. The current study characterized a novel 16-amino acid α-conotoxin (α-CTx) TxIB from Conus textile whose sequence is GCCSDPPCRNKHPDLC-amide as deduced from gene cloning. The peptide and an analog with an additional C-terminal glycine were chemically synthesized and tested on rat nAChRs heterologously expressed in Xenopus laevis oocytes. α-CTx TxIB blocked α6/α3β2β3 nAChR with an IC(50) of 28 nm. In contrast, the peptide showed little or no block of other tested subtypes at concentrations up to 10 μm. The three-dimensional solution structure of α-CTx TxIB was determined using NMR spectroscopy. α-CTx TxIB represents a uniquely selective ligand for probing the structure and function of α6β2 nAChRs.
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Affiliation(s)
- Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drug of Haikou, Hainan University, Haikou Hainan, 570228 China.
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44
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Azam L, McIntosh JM. Molecular basis for the differential sensitivity of rat and human α9α10 nAChRs to α-conotoxin RgIA. J Neurochem 2012; 122:1137-44. [PMID: 22774872 DOI: 10.1111/j.1471-4159.2012.07867.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The α9α10 nicotinic acetylcholine receptor (nAChR) may be a potential target in pathophysiology of the auditory system, chronic pain, and breast and lung cancers. Alpha-conotoxins, from the predatory marine snail Conus, are potent nicotinic antagonists, some of which are selective for the α9α10 nAChR. Here, we report a two order of magnitude species difference in the potency of α-conotoxin RgIA for the rat versus human α9α10 nAChR. We investigated the molecular mechanism of this difference. Heterologous expression of the rat α9 with the human α10 subunit in Xenopus oocytes resulted in a receptor that was blocked by RgIA with potency similar to that of the rat α9α10 nAChR. Conversely, expression of the human α9 with that of the rat α10 subunit resulted in a receptor that was blocked by RgIA with potency approaching that of the human α9α10 receptor. Systematic substitution of residues found in the human α9 subunit into the homologous position in the rat α9 subunit revealed that a single point mutation, Thr56 to Ile56, primarily accounts for this species difference. Remarkably, although the α9 nAChR subunit has previously been reported to provide the principal (+) binding face for binding of RgIA, Thr56 is located in the (-) complementary binding face.
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Affiliation(s)
- Layla Azam
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
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45
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Kim HW, McIntosh JM. α6 nAChR subunit residues that confer α-conotoxin BuIA selectivity. FASEB J 2012; 26:4102-10. [PMID: 22751014 DOI: 10.1096/fj.12-204487] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) containing α6 and/or α4 subunits modulate the release of dopamine. However, few compounds can effectively discriminate between ligand-binding sites that contain α6 vs. α4 nAChR subunits. Using a chimeric (α6/α4) subunit, we showed that α-conotoxin BuIA binds the extracellular rat α6β2 vs. α4β2 interface with ∼60,000-fold selectivity. Chimeras containing residues from the α6 subunit were inserted into the homologous position of the α4 subunit to identify critical sequence segments. The region between residues 184 and 207 in the α6 subunit accounted for the potency difference. Chimeras within this region followed by point mutations were constructed for further definition. α6 Lys185, Thr187, and Ile188 form a triad of key residues that influence BuIA binding; when these 3 α6 residues were inserted into the α4 subunit, there was an ∼2000-fold increase in toxin potency. We used a crystal structure of BuIA bound to the acetylcholine-binding protein together with the structure of the Torepedo marmorata nAChR to build a homology model of BuIA bound to the interface between α6 and β2 subunits. The results indicate that the triad of α6 residues lies outside the C loop and is distantly located from bound BuIA (>10 Å). This suggests that alterations in potency are not caused by the direct interaction between the triad and BuIA. Instead, alterations in C-loop 3-dimensional structure and/or flexibility may account for differential potency. Thr198 and Tyr205 also contributed to BuIA potency. In addition, Thr198 caused BuIA potency differences between the closely related α6 and α3 subunits. Together, the findings provide insight into differences between the α6 and other α subunits that may be exploited by α-conotoxins to achieve binding selectivity.
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Affiliation(s)
- Hyun-Woo Kim
- Department of Marine Biology, Pukyong National University, Busan, South Korea.
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46
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McClure-Begley TD, Wageman CR, Grady SR, Marks MJ, McIntosh JM, Collins AC, Whiteaker P. A novel α-conotoxin MII-sensitive nicotinic acetylcholine receptor modulates [(3) H]-GABA release in the superficial layers of the mouse superior colliculus. J Neurochem 2012; 122:48-57. [PMID: 22506481 DOI: 10.1111/j.1471-4159.2012.07759.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mouse superficial superior colliculus (SuSC) contains dense GABAergic innervation and diverse nicotinic acetylcholine receptor subtypes. Pharmacological and genetic approaches were used to investigate the subunit compositions of nicotinic acetylcholine receptors (nAChR) expressed on mouse SuSC GABAergic terminals. [(125) I]-Epibatidine competition-binding studies revealed that the α3β2* and α6β2* nicotinic subtype-selective peptide α-conotoxin MII-blocked binding to 40 ± 5% of SuSC nAChRs. Acetylcholine-evoked [(3) H]-GABA release from SuSC crude synaptosomal preparations is calcium dependent, blocked by the voltage-sensitive calcium channel blocker, cadmium, and the nAChR antagonist mecamylamine, but is unaffected by muscarinic, glutamatergic, P2X and 5-HT3 receptor antagonists. Approximately 50% of nAChR-mediated SuSC [(3) H]-GABA release is inhibited by α-conotoxin MII. However, the highly α6β2*-subtype-selective α-conotoxin PIA did not affect [(3) H]-GABA release. Nicotinic subunit-null mutant mouse experiments revealed that ACh-stimulated SuSC [(3) H]-GABA release is entirely β2 subunit-dependent. α4 subunit deletion decreased total function by >90%, and eliminated α-conotoxin MII-resistant release. ACh-stimulated SuSC [(3) H]-GABA release was unaffected by β3, α5 or α6 nicotinic subunit deletions. Together, these data suggest that a significant proportion of mouse SuSC nicotinic agonist-evoked GABA-release is mediated by a novel, α-conotoxin MII-sensitive α3α4β2 nAChR. The remaining α-conotoxin MII-resistant, nAChR agonist-evoked SuSC GABA release appears to be mediated via α4β2* subtype nAChRs.
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Lewis RJ, Dutertre S, Vetter I, Christie MJ. Conus Venom Peptide Pharmacology. Pharmacol Rev 2012; 64:259-98. [DOI: 10.1124/pr.111.005322] [Citation(s) in RCA: 323] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Franco A, Kompella SN, Akondi KB, Melaun C, Daly NL, Luetje CW, Alewood PF, Craik DJ, Adams DJ, Marí F. RegIIA: An α4/7-conotoxin from the venom of Conus regius that potently blocks α3β4 nAChRs. Biochem Pharmacol 2012; 83:419-26. [DOI: 10.1016/j.bcp.2011.11.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Revised: 11/04/2011] [Accepted: 11/07/2011] [Indexed: 11/26/2022]
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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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Pérez-Alvarez A, Hernández-Vivanco A, McIntosh JM, Albillos A. Native α6β4* nicotinic receptors control exocytosis in human chromaffin cells of the adrenal gland. FASEB J 2011; 26:346-54. [PMID: 21917987 DOI: 10.1096/fj.11-190223] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In the present study, we have electrophysiologically characterized native nicotinic acetylcholine receptors (nAChRs) in human chromaffin cells of the adrenal gland as well as their contribution to the exocytotic process. α-Conotoxin AuIB blocked by 14 ± 1% the acetylcholine (ACh)-induced nicotinic current. α-Conotoxin MII (α-Ctx MII) exhibited an almost full blockade of the nicotinic current at nanomolar concentrations (IC(50)=21.6 nM). The α6*-preferring α-Ctx MII mutant analogs, α-Ctx MII[H9A,L15A] and α-Ctx MII[S4A,E11A,L15A], blocked nAChR currents with an IC(50) of 217.8 and 33 nM, respectively. These data reveal that nAChRs in these cells include the α6* subtype. The washout of the blockade exerted by α-conotoxin BuIA (α-Ctx BuIA; 1 μM) on ACh-evoked currents was slight and slow, arguing in favor of the presence of a β4 subunit in the nAChR composition. Exocytosis was almost fully blocked by 1 μM α-Ctx MII, its mutant analogs, or α-Ctx BuIA. Finally, the fluorescent analog Alexa Fluor 546-BuIA showed distinct staining in these cells. Our results reveal that α6β4* nAChRs are expressed and contribute to exocytosis in human chromaffin cells of the adrenal gland, the main source of adrenaline under stressful situations.
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Affiliation(s)
- Alberto Pérez-Alvarez
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain.
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