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O’Brien BCV, Thao S, Weber L, Danielson HL, Boldt AD, Hueffer K, Weltzin MM. The human alpha7 nicotinic acetylcholine receptor is a host target for the rabies virus glycoprotein. Front Cell Infect Microbiol 2024; 14:1394713. [PMID: 38836054 PMCID: PMC11148329 DOI: 10.3389/fcimb.2024.1394713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Accepted: 04/29/2024] [Indexed: 06/06/2024] Open
Abstract
The rabies virus enters the nervous system by interacting with several molecular targets on host cells to modify behavior and trigger receptor-mediated endocytosis of the virion by poorly understood mechanisms. The rabies virus glycoprotein (RVG) interacts with the muscle acetylcholine receptor and the neuronal α4β2 subtype of the nicotinic acetylcholine receptor (nAChR) family by the putative neurotoxin-like motif. Given that the neurotoxin-like motif is highly homologous to the α7 nAChR subtype selective snake toxin α-bungarotoxin (αBTX), other nAChR subtypes are likely involved. The purpose of this study is to determine the activity of the RVG neurotoxin-like motif on nAChR subtypes that are expressed in brain regions involved in rabid animal behavior. nAChRs were expressed in Xenopus laevis oocytes, and two-electrode voltage clamp electrophysiology was used to collect concentration-response data to measure the functional effects. The RVG peptide preferentially and completely inhibits α7 nAChR ACh-induced currents by a competitive antagonist mechanism. Tested heteromeric nAChRs are also inhibited, but to a lesser extent than the α7 subtype. Residues of the RVG peptide with high sequence homology to αBTX and other neurotoxins were substituted with alanine. Altered RVG neurotoxin-like peptides showed that residues phenylalanine 192, arginine 196, and arginine 199 are important determinants of RVG peptide apparent potency on α7 nAChRs, while serine 195 is not. The evaluation of the rabies ectodomain reaffirmed the observations made with the RVG peptide, illustrating a significant inhibitory impact on α7 nAChR with potency in the nanomolar range. In a mammalian cell culture model of neurons, we confirm that the RVG peptide binds preferentially to cells expressing the α7 nAChR. Defining the activity of the RVG peptide on nAChRs expands our understanding of basic mechanisms in host-pathogen interactions that result in neurological disorders.
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Affiliation(s)
- Brittany C. V. O’Brien
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Shelly Thao
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Lahra Weber
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Helen L. Danielson
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Agatha D. Boldt
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Karsten Hueffer
- Department of Veterinary Medicine, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Maegan M. Weltzin
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
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2
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George AA, John SJ, Lucero LM, Eaton JB, Jaiswal E, Christensen SB, Gajewiak J, Watkins M, Cao Y, Olivera BM, Im W, McIntosh JM, Whiteaker P. Analogs of α-conotoxin PnIC selectively inhibit α7β2- over α7-only subtype nicotinic acetylcholine receptors via a novel allosteric mechanism. FASEB J 2024; 38:e23374. [PMID: 38161283 PMCID: PMC10782225 DOI: 10.1096/fj.202302079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 12/01/2023] [Indexed: 01/03/2024]
Abstract
This study was undertaken to identify and characterize the first ligands capable of selectively identifying nicotinic acetylcholine receptors containing α7 and β2 subunits (α7β2-nAChR subtype). Basal forebrain cholinergic neurons express α7β2-nAChR. Here, they appear to mediate neuronal dysfunction induced by the elevated levels of oligomeric amyloid-β associated with early Alzheimer's disease. Additional work indicates that α7β2-nAChR are expressed across several further critically important cholinergic and GABAergic neuronal circuits within the central nervous system. Further studies, however, are significantly hindered by the inability of currently available ligands to distinguish heteromeric α7β2-nAChR from the closely related and more widespread homomeric α7-only-nAChR subtype. Functional screening using two-electrode voltage-clamp electrophysiology identified a family of α7β2-nAChR-selective analogs of α-conotoxin PnIC (α-CtxPnIC). A combined electrophysiology, functional kinetics, site-directed mutagenesis, and molecular dynamics approach was used to further characterize the α7β2-nAChR selectivity and site of action of these α-CtxPnIC analogs. We determined that α7β2-nAChR selectivity of α-CtxPnIC analogs arises from interactions at a site distinct from the orthosteric agonist-binding site shared between α7β2- and α7-only-nAChR. As numerous previously identified α-Ctx ligands are competitive antagonists of orthosteric agonist-binding sites, this study profoundly expands the scope of use of α-Ctx ligands (which have already provided important nAChR research and translational breakthroughs). More immediately, analogs of α-CtxPnIC promise to enable, for the first time, both comprehensive mapping of the distribution of α7β2-nAChR and detailed investigations of their physiological roles.
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Affiliation(s)
- Andrew A. George
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
| | - Sabin J. John
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
- Department of Life SciencesUniversity of BathBathUK
| | - Linda M. Lucero
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | - J. Brek Eaton
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | - Ekta Jaiswal
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | | | - Joanna Gajewiak
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
| | - Maren Watkins
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
| | - Yiwei Cao
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | | | - Wonpil Im
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | - J. Michael McIntosh
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
- George E. Wahlen Veterans Affairs Medical CenterSalt Lake CityUtahUSA
- Department of PsychiatryUniversity of UtahSalt Lake CityUtahUSA
| | - Paul Whiteaker
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
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3
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Becchetti A, Grandi LC, Cerina M, Amadeo A. Nicotinic acetylcholine receptors and epilepsy. Pharmacol Res 2023; 189:106698. [PMID: 36796465 DOI: 10.1016/j.phrs.2023.106698] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/04/2023] [Accepted: 02/13/2023] [Indexed: 02/16/2023]
Abstract
Despite recent advances in understanding the causes of epilepsy, especially the genetic, comprehending the biological mechanisms that lead to the epileptic phenotype remains difficult. A paradigmatic case is constituted by the epilepsies caused by altered neuronal nicotinic acetylcholine receptors (nAChRs), which exert complex physiological functions in mature as well as developing brain. The ascending cholinergic projections exert potent control of forebrain excitability, and wide evidence implicates nAChR dysregulation as both cause and effect of epileptiform activity. First, tonic-clonic seizures are triggered by administration of high doses of nicotinic agonists, whereas non-convulsive doses have kindling effects. Second, sleep-related epilepsy can be caused by mutations on genes encoding nAChR subunits widely expressed in the forebrain (CHRNA4, CHRNB2, CHRNA2). Third, in animal models of acquired epilepsy, complex time-dependent alterations in cholinergic innervation are observed following repeated seizures. Heteromeric nAChRs are central players in epileptogenesis. Evidence is wide for autosomal dominant sleep-related hypermotor epilepsy (ADSHE). Studies of ADSHE-linked nAChR subunits in expression systems suggest that the epileptogenic process is promoted by overactive receptors. Investigation in animal models of ADSHE indicates that expression of mutant nAChRs can lead to lifelong hyperexcitability by altering i) the function of GABAergic populations in the mature neocortex and thalamus, ii) synaptic architecture during synaptogenesis. Understanding the balance of the epileptogenic effects in adult and developing networks is essential to plan rational therapy at different ages. Combining this knowledge with a deeper understanding of the functional and pharmacological properties of individual mutations will advance precision and personalized medicine in nAChR-dependent epilepsy.
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Affiliation(s)
- Andrea Becchetti
- Department of Biotechnology and Biosciences, and NeuroMI (Milan Center of Neuroscience), University of Milano-Bicocca, Piazza della Scienza 2, Milano 20126, Italy.
| | - Laura Clara Grandi
- Department of Biotechnology and Biosciences, and NeuroMI (Milan Center of Neuroscience), University of Milano-Bicocca, Piazza della Scienza 2, Milano 20126, Italy.
| | - Marta Cerina
- Department of Biotechnology and Biosciences, and NeuroMI (Milan Center of Neuroscience), University of Milano-Bicocca, Piazza della Scienza 2, Milano 20126, Italy.
| | - Alida Amadeo
- Department of Biosciences, University of Milano, Via Celoria 26, Milano 20133, Italy.
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4
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Huang YB, Ma ZG, Zheng C, Ma XKK, Taylor DH, Gao M, Lukas RJ, Wu J. Levo-tetrahydropalmatine inhibits α4β2 nicotinic receptor response to nicotine in cultured SH-EP1 cells. Acta Pharmacol Sin 2022; 43:889-896. [PMID: 34253876 PMCID: PMC8975845 DOI: 10.1038/s41401-021-00709-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 05/30/2021] [Indexed: 02/05/2023] Open
Abstract
Nicotine, a major component of tobacco, is highly addictive and acts on nicotinic acetylcholine receptors (nAChRs) to stimulate reward-associated circuits in the brain. It is well known that nAChRs play critical roles in mediating nicotine reward and addiction. Current FDA-approved medications for smoking cessation are the antidepressant bupropion and the nicotinic partial agonist varenicline, yet both are limited by adverse side effects and moderate efficacy. Thus, development of more efficacious medications with fewer side effects for nicotine addiction and smoking cessation is urgently needed. l-Tetrahydropalmatine (l-THP) is an active ingredient of the Chinese medicinal herb Corydalis ambigua that possesses rich neuropharmacological actions on dopamine (DA) receptors in the mesocorticolimbic dopaminergic reward pathway. L-THP has been explored as anti-addiction treatments for drug abuse including nicotine. However, the targets and mechanisms of l-THP-caused anti-nicotine effects are largely unknown. In this study we address this question by elucidating the effects of l-THP on human neuronal nAChRs using patch-clamp recordings. Human neuronal α4β2-nAChRs were heterologously expressed in SH-EP1 human epithelial cells. Bath application of nicotine (0.1-100 μM) induced inward currents, co-application of l-THP (3 μM) inhibited nicotine-induced currents in the transfected cells. L-THP-caused inhibition was concentration-dependent (the EC50 values for inhibiting the peak and steady-state current were 18 and 2.1 μM, respectively) and non-competitive. Kinetic analysis of the whole-cell currents showed that l-THP slowed rising time and accelerated decay time constants. L-THP specifically modulated α4β2-nAChRs, as it did not affect α7-nAChRs or α1*-nAChRs (muscle type). Interestingly, two putative α4β2-nAChR isoforms, namely sazetidine A-activated, high-sensitive one (α42β23-nAChR) and cytisine-activated, low-sensitive one (α43β22-nAChR) were pharmacologically separated, and the low-sensitive one was more susceptible to l-THP inhibition than the high-sensitive one. In conclusion, we demonstrate that l-THP blocks neuronal α4β2-nAChR function, which may underlie its inhibition on nicotine addiction.
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Affiliation(s)
- Yuan-Bing Huang
- Department of Neurology, Yunfu People's Hospital, Yunfu, 527300, China
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Ze-Gang Ma
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
- Electrophysiology Laboratory, Wannan Medical College, Wuhu, 695011, China
| | - Chao Zheng
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
- Institution of Brain Sciences and Diseases, Qingdao University, Qingdao, 266071, China
| | - Xiao-Kuang K Ma
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
- Department of Pharmacology, Shantou University Medical College, Shantou, 515041, China
| | - Devin H Taylor
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
- Department of Biology, Utah Valley University, Orem, UT, 84058, USA
| | - Ming Gao
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Ronald J Lukas
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Jie Wu
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA.
- Institution of Brain Sciences and Diseases, Qingdao University, Qingdao, 266071, China.
- Department of Pharmacology, Shantou University Medical College, Shantou, 515041, China.
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5
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Nielsen TØ, Herlin MK, Linnet KM, Beniczky S, Sommerlund M, Granild-Jensen JB, Gregersen PA. Autosomal dominant sleep-related hypermotor epilepsy caused by a previously unreported CHRNA4 variant. Eur J Med Genet 2022; 65:104444. [DOI: 10.1016/j.ejmg.2022.104444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 01/09/2022] [Accepted: 01/22/2022] [Indexed: 11/03/2022]
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6
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Pisapati AV, Cao W, Anderson KR, Jones G, Holick KH, Whiteaker P, Im W, Zhang XF, Miwa JM. Biophysical characterization of lynx-nicotinic receptor interactions using atomic force microscopy. FASEB Bioadv 2021; 3:1034-1042. [PMID: 34938964 PMCID: PMC8664008 DOI: 10.1096/fba.2021-00012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 08/03/2021] [Accepted: 08/30/2021] [Indexed: 11/11/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are broadly expressed in the central and peripheral nervous systems, playing essential roles in cholinergic neurotransmission. The lynx family proteins, a subset of the Ly6/uPAR superfamily expressed in multiple brain regions, have been shown to bind to nAChRs and modulate their function via allosteric regulation. The binding interactions between lynx and nAChRs, however, have not been systematically quantified and compared. In this work, we characterized the interactions between lynx1 or lynx2 and α3β4- or α7-nAChRs using single-molecule atomic force microscopy (AFM). The AFM technique allows the quantification of the off-rate of lynx-nAChR binding and of the energetic barrier width between the bound state and transition state, providing a biophysical means to compare the selectivity of lynx proteins for nAChR subtypes. Results indicate that lynx1 has a marginal preference for α7- over α3β4-nAChRs. Strikingly, lynx2 exhibits a two order of magnitude stronger affinity for α3β4- compared to α7-nAChRs. Together, the AFM assay serves as a valuable tool for the biophysical characterization of lynx-nAChR binding affinities. Revealing the differential affinities of lynx proteins for nAChR subtypes will help elucidate how lynx regulates nAChR-dependent functions in the brain, including nicotine addiction and other critical pathways.
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Affiliation(s)
- Avani V. Pisapati
- Department of BioengineeringLehigh UniversityBethlehemPennsylvaniaUSA
| | - Wenpeng Cao
- Department of BioengineeringLehigh UniversityBethlehemPennsylvaniaUSA
| | | | - Griffin Jones
- Department of Biological SciencesLehigh UniversityBethlehemPennsylvaniaUSA
| | | | - Paul Whiteaker
- Division of NeurobiologyBarrow Neurological Institute, St. Joseph's Hospital and Medical CenterLehigh UniversityPhoenixArizonaUSA
| | - Wonpil Im
- Department of BioengineeringLehigh UniversityBethlehemPennsylvaniaUSA
- Department of Biological SciencesLehigh UniversityBethlehemPennsylvaniaUSA
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | - X. Frank Zhang
- Department of BioengineeringLehigh UniversityBethlehemPennsylvaniaUSA
- Department of Mechanical Engineering and MechanicsLehigh UniversityBethlehemPennsylvaniaUSA
| | - Julie M. Miwa
- Department of Biological SciencesLehigh UniversityBethlehemPennsylvaniaUSA
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7
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Borroni V, Barrantes FJ. Homomeric and Heteromeric α7 Nicotinic Acetylcholine Receptors in Health and Some Central Nervous System Diseases. MEMBRANES 2021; 11:membranes11090664. [PMID: 34564481 PMCID: PMC8465519 DOI: 10.3390/membranes11090664] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/24/2021] [Accepted: 08/24/2021] [Indexed: 11/22/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels involved in the modulation of essential brain functions such as memory, learning, and attention. Homomeric α7 nAChR, formed exclusively by five identical α7 subunits, is involved in rapid synaptic transmission, whereas the heteromeric oligomers composed of α7 in combination with β subunits display metabotropic properties and operate in slower time frames. At the cellular level, the activation of nAChRs allows the entry of Na+ and Ca2+; the two cations depolarize the membrane and trigger diverse cellular signals, depending on the type of nAChR pentamer and neurons involved, the location of the intervening cells, and the networks of which these neuronal cells form part. These features make the α7 nAChR a central player in neurotransmission, metabolically associated Ca2+-mediated signaling, and modulation of diverse fundamental processes operated by other neurotransmitters in the brain. Due to its ubiquitous distribution and the multiple functions it displays in the brain, the α7 nAChR is associated with a variety of neurological and neuropsychiatric disorders whose exact etiopathogenic mechanisms are still elusive.
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Affiliation(s)
- Virginia Borroni
- Instituto de Tecnología en Polímeros y Nanotecnología (ITPN-UBA-CONICET), Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires C1127AAR, Argentina;
| | - Francisco J. Barrantes
- Laboratory of Molecular Neurobiology, Institute for Biomedical Research, UCA–CONICET, Faculty of Medical Sciences, Catholic University of Argentina, Av. Alicia Moreau de Justo 1600, Buenos Aires C1107AAZ, Argentina
- Correspondence:
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8
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Wu X, Craik DJ, Kaas Q. Interactions of Globular and Ribbon [γ4E]GID with α4β2 Neuronal Nicotinic Acetylcholine Receptor. Mar Drugs 2021; 19:md19090482. [PMID: 34564144 PMCID: PMC8469569 DOI: 10.3390/md19090482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 08/24/2021] [Accepted: 08/24/2021] [Indexed: 02/05/2023] Open
Abstract
The α4β2 nAChR is implicated in a range of diseases and disorders including nicotine addiction, epilepsy and Parkinson's and Alzheimer's diseases. Designing α4β2 nAChR selective inhibitors could help define the role of the α4β2 nAChR in such disease states. In this study, we aimed to modify globular and ribbon α-conotoxin GID to selectively target the α4β2 nAChR through competitive inhibition of the α4(+)β2(-) or α4(+)α4(-) interfaces. The binding modes of the globular α-conotoxin [γ4E]GID with rat α3β2, α4β2 and α7 nAChRs were deduced using computational methods and were validated using published experimental data. The binding mode of globular [γ4E]GID at α4β2 nAChR can explain the experimental mutagenesis data, suggesting that it could be used to design GID variants. The predicted mutational energy results showed that globular [γ4E]GID is optimal for binding to α4β2 nAChR and its activity could not likely be further improved through amino-acid substitutions. The binding mode of ribbon GID with the (α4)3(β2)2 nAChR was deduced using the information from the cryo-electron structure of (α4)3(β2)2 nAChR and the binding mode of ribbon AuIB. The program FoldX predicted the mutational energies of ribbon [γ4E]GID at the α4(+)α4(-) interface, and several ribbon[γ4E]GID mutants were suggested to have desirable properties to inhibit (α4)3(β2)2 nAChR.
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Affiliation(s)
- Xiaosa Wu
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia;
- National Institutes of Health, Building 35A, Room 3D-953B, 35 Convent Drive, Bethesda, MD 20892-3701, USA
| | - 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, QLD 4072, Australia;
- Correspondence: (D.J.C.); (Q.K.)
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia;
- Correspondence: (D.J.C.); (Q.K.)
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9
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Zheng JJ, Zhang TY, Liu HT, Huang ZX, Teng JM, Deng JX, Zhong JG, Qian X, Sheng XW, Ding JQ, He SQ, Zhao X, Ji WD, Qi DF, Li W, Zhang M. Cytisine Exerts an Anti-Epileptic Effect via α7nAChRs in a Rat Model of Temporal Lobe Epilepsy. Front Pharmacol 2021; 12:706225. [PMID: 34248648 PMCID: PMC8263902 DOI: 10.3389/fphar.2021.706225] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 06/09/2021] [Indexed: 11/13/2022] Open
Abstract
Background and Purpose: Temporal lobe epilepsy (TLE) is a common chronic neurological disease that is often invulnerable to anti-epileptic drugs. Increasing data have demonstrated that acetylcholine (ACh) and cholinergic neurotransmission are involved in the pathophysiology of epilepsy. Cytisine, a full agonist of α7 nicotinic acetylcholine receptors (α7nAChRs) and a partial agonist of α4β2nAChRs, has been widely applied for smoking cessation and has shown neuroprotection in neurological diseases. However, whether cytisine plays a role in treating TLE has not yet been determined. Experimental Approach: In this study, cytisine was injected intraperitoneally into pilocarpine-induced epileptic rats for three weeks. Alpha-bungarotoxin (α-bgt), a specific α7nAChR antagonist, was used to evaluate the mechanism of action of cytisine. Rats were assayed for the occurrence of seizures and cognitive function by video surveillance and Morris water maze. Hippocampal injuries and synaptic structure were assessed by Nissl staining and Golgi staining. Furthermore, levels of glutamate, γ-aminobutyric acid (GABA), ACh, and α7nAChRs were measured. Results: Cytisine significantly reduced seizures and hippocampal damage while improving cognition and inhibiting synaptic remodeling in TLE rats. Additionally, cytisine decreased glutamate levels without altering GABA levels, and increased ACh levels and α7nAChR expression in the hippocampi of TLE rats. α-bgt antagonized the above-mentioned effects of cytisine treatment. Conclusion and Implications: Taken together, these findings indicate that cytisine exerted an anti-epileptic and neuroprotective effect in TLE rats via activation of α7nAChRs, which was associated with a decrease in glutamate levels, inhibition of synaptic remodeling, and improvement of cholinergic transmission in the hippocampus. Hence, our findings not only suggest that cytisine represents a promising anti-epileptic drug, but provides evidence of α7nAChRs as a novel therapeutic target for TLE.
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Affiliation(s)
- Jing-Jun Zheng
- Key Laboratory of Molecular Target and Clinical Pharmacology, Department of Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.,Department of Pharmacy, Shenzhen Kangning Hospital, Shenzhen Mental Health Center, Shenzhen, China
| | - Teng-Yue Zhang
- Key Laboratory of Molecular Target and Clinical Pharmacology, Department of Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Hong-Tao Liu
- Key Laboratory of Molecular Target and Clinical Pharmacology, Department of Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Ze-Xin Huang
- Key Laboratory of Molecular Target and Clinical Pharmacology, Department of Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Jing-Mei Teng
- Key Laboratory of Molecular Target and Clinical Pharmacology, Department of Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Jing-Xian Deng
- Key Laboratory of Molecular Target and Clinical Pharmacology, Department of Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Jia-Gui Zhong
- Department of Neurosurgery, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Xu Qian
- Key Laboratory of Molecular Target and Clinical Pharmacology, Department of Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Xin-Wen Sheng
- Key Laboratory of Molecular Target and Clinical Pharmacology, Department of Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Ji-Qiang Ding
- Department of Neurosurgery, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Shu-Qiao He
- Department of Pharmacy, Maoming People's Hospital, Maoming, China
| | - Xin Zhao
- Key Laboratory of Molecular Target and Clinical Pharmacology, Department of Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Wei-Dong Ji
- Center for Translational Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - De-Feng Qi
- Department of Urology, Minimally Invasive Surgery Center, The First Affiliated Hop-ital of Guangzhou Medical University, Guangdong Key Laboratory of Urology, Guangzhou, China
| | - Wei Li
- Department of Neurosurgery, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Mei Zhang
- Key Laboratory of Molecular Target and Clinical Pharmacology, Department of Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
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10
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Sleep-related hypermotor epilepsy associated mutations uncover important kinetic roles of α4β2- nicotinic acetylcholine receptor intracellular structures. PLoS One 2021; 16:e0247825. [PMID: 33657187 PMCID: PMC7928491 DOI: 10.1371/journal.pone.0247825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 02/12/2021] [Indexed: 12/13/2022] Open
Abstract
Sleep-related hypermotor epilepsy (SHE) is a group of seizure disorders prominently associated with mutations in nicotinic acetylcholine receptors (nAChR). The most prevalent central nervous system nAChR subtype contains α4 and β2 subunits, in two ratios. (α4β2)2β2-nAChR have high agonist sensitivity (HS-isoform), whereas (α4β2)2α4-nAChR agonist responses exhibit a small high-sensitivity, and a predominant low-sensitivity, phase of function (LS-isoform). Multiple non-synonymous mutations in the second and third transmembrane domains of α4 and β2 subunits are associated with SHE. We recently demonstrated that two additional, SHE-associated, missense mutations in the major cytoplasmic loops of these subunits [α4(R336H) and β2(V337G)] cause increased macroscopic function-per receptor. Here, we use single-channel patch-clamp electrophysiology to show that these mutations influence single-channel amplitudes and open- and closed-state kinetics. Pure populations of HS- or LS-isoform α4β2-nAChR were expressed by injecting either 1:10 or 30:1 α4:β2 cRNA ratios, respectively, into Xenopus laevis oocytes. Functional properties of the resulting mutant α4β2-nAChR isoforms were compared to their wildtype counterparts. α4(R336H) subunit incorporation minimally affected single-channel amplitudes, whereas β2(V337G) subunit incorporation reduced them significantly in both isoforms. However, for both mutant subunits, increased function-per-receptor was predominantly caused by altered single channel kinetics. The α4(R336H) mutation primarily destabilizes desensitized states between openings. By contrast, the β2(V337G) mutation principally stabilizes receptor open states. The use of naturally-occurring and physiologically-impactful mutations has allowed us to define valuable new insights regarding the functional roles of nAChR intracellular domains. Further mechanistic context is provided by intracellular-domain structures recently published for other members of the Cys-loop receptor superfamily (α3β4-nAChR and 5-HT3AR).
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Abstract
Abstract:Purpose:Our purpose was to determine the role of CHRNA4 and CHRNB2 in insular epilepsy.Method:We identified two patients with drug-resistant predominantly sleep-related hypermotor seizures, one harboring a heterozygous missense variant (c.77C>T; p. Thr26Met) in the CHRNB2 gene and the other a heterozygous missense variant (c.1079G>A; p. Arg360Gln) in the CHRNA4 gene. The patients underwent electrophysiological and neuroimaging studies, and we performed functional characterization of the p. Thr26Met (c.77C>T) in the CHRNB2 gene.Results:We localized the epileptic foci to the left insula in the first case (now seizure-free following epilepsy surgery) and to both insulae in the second case. Based on tools predicting the possible impact of amino acid substitutions on the structure and function of proteins (sorting intolerant from tolerant and PolyPhen-2), variants identified in this report could be deleterious. Functional expression in human cell lines of α4β2 (wild-type), α4β2-Thr26Met (homozygote), and α4β2/β2-Thr26Met (heterozygote) nicotinic acetylcholine receptors revealed that the mutant subunit led to significantly higher whole-cell nicotinic currents. This feature was observed in both homo- and heterozygous conditions and was not accompanied by major alterations of the current reversal potential or the shape of the concentration-response relation.Conclusions:This study suggests that variants in CHRNB2 and CHRNA4, initially linked to autosomal dominant nocturnal frontal lobe epilepsy, are also found in patients with predominantly sleep-related insular epilepsy. Although the reported variants should be considered of unknown clinical significance for the moment, identification of additional similar cases and further functional studies could eventually strengthen this association.
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Blom AE, Campello HR, Lester HA, Gallagher T, Dougherty DA. Probing Binding Interactions of Cytisine Derivatives to the α4β2 Nicotinic Acetylcholine Receptor. J Am Chem Soc 2019; 141:15840-15849. [DOI: 10.1021/jacs.9b06580] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
| | - Hugo Rego Campello
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | | | - Timothy Gallagher
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
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Weltzin MM, George AA, Lukas RJ, Whiteaker P. Distinctive single-channel properties of α4β2-nicotinic acetylcholine receptor isoforms. PLoS One 2019; 14:e0213143. [PMID: 30845161 PMCID: PMC6405073 DOI: 10.1371/journal.pone.0213143] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 02/17/2019] [Indexed: 11/19/2022] Open
Abstract
Central nervous system nicotinic acetylcholine receptors (nAChR) are predominantly of the α4β2 subtype. Two isoforms exist, with high or low agonist sensitivity (HS-(α4β2)2β2- and LS-(α4β2)2α4-nAChR). Both isoforms exhibit similar macroscopic potency and efficacy values at low acetylcholine (ACh) concentrations, mediated by a common pair of high-affinity α4(+)/(-)β2 subunit binding interfaces. However LS-(α4β2)2α4-nAChR also respond to higher concentrations of ACh, acting at a third α4(+)/(-)α4 subunit interface. To probe isoform functional differences further, HS- and LS-α4β2-nAChR were expressed in Xenopus laevis oocytes and single-channel responses were assessed using cell-attached patch-clamp. In the presence of a low ACh concentration, both isoforms produce low-bursting function. HS-(α4β2)2β2-nAChR exhibit a single conductance state, whereas LS-(α4β2)2α4-nAChR display two distinctive conductance states. A higher ACh concentration did not preferentially recruit either conductance state, but did result in increased LS-(α4β2)2α4-nAChR bursting and reduced closed times. Introduction of an α4(+)/(-)α4-interface loss-of-function α4W182A mutation abolished these changes, confirming this site's role in mediating LS-(α4β2)2α4-nAChR responses. Small or large amplitude openings are highly-correlated within individual LS-(α4β2)2α4-nAChR bursts, suggesting that they arise from distinct intermediate states, each of which is stabilized by α4(+)/(-)α4 site ACh binding. These findings are consistent with α4(+)/(-)α4 subunit interface occupation resulting in allosteric potentiation of agonist actions at α4(+)/(-)β2 subunit interfaces, rather than independent induction of high conductance channel openings.
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Affiliation(s)
- Maegan M. Weltzin
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, United States of America
- * E-mail:
| | - Andrew A. George
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, United States of America
| | - Ronald J. Lukas
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, United States of America
| | - Paul Whiteaker
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, United States of America
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Indurthi DC, Qudah T, Liao VW, Ahring PK, Lewis TM, Balle T, Chebib M, Absalom NL. Revisiting autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) mutations in the nicotinic acetylcholine receptor reveal an increase in efficacy regardless of stochiometry. Pharmacol Res 2019; 139:215-227. [DOI: 10.1016/j.phrs.2018.11.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 11/21/2018] [Accepted: 11/21/2018] [Indexed: 12/22/2022]
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15
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Liu W, Li MD. Insights Into Nicotinic Receptor Signaling in Nicotine Addiction: Implications for Prevention and Treatment. Curr Neuropharmacol 2018; 16:350-370. [PMID: 28762314 PMCID: PMC6018190 DOI: 10.2174/1570159x15666170801103009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 06/18/2017] [Accepted: 07/28/2017] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Nicotinic acetylcholine receptors (nAChRs) belong to the Cys-loop ligandgated ion-channel (LGIC) superfamily, which also includes the GABA, glycine, and serotonin receptors. Many nAChR subunits have been identified and shown to be involved in signal transduction on binding to them of either the neurotransmitter acetylcholine or exogenous ligands such as nicotine. The nAChRs are pentameric assemblies of homologous subunits surrounding a central pore that gates cation flux, and they are expressed at neuromuscular junctions throughout the nervous system. METHODS AND RESULTS Because different nAChR subunits assemble into a variety of pharmacologically distinct receptor subtypes, and different nAChRs are implicated in various physiological functions and pathophysiological conditions, nAChRs represent potential molecular targets for drug addiction and medical therapeutic research. This review intends to provide insights into recent advances in nAChR signaling, considering the subtypes and subunits of nAChRs and their roles in nicotinic cholinergic systems, including structure, diversity, functional allosteric modulation, targeted knockout mutations, and rare variations of specific subunits, and the potency and functional effects of mutations by focusing on their effects on nicotine addiction (NA) and smoking cessation (SC). Furthermore, we review the possible mechanisms of action of nAChRs in NA and SC based on our current knowledge. CONCLUSION Understanding these cellular and molecular mechanisms will lead to better translational and therapeutic operations and outcomes for the prevention and treatment of NA and other drug addictions, as well as chronic diseases, such as Alzheimer's and Parkinson's. Finally, we put forward some suggestions and recommendations for therapy and treatment of NA and other chronic diseases.
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Affiliation(s)
- Wuyi Liu
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China.,School of Biological Sciences and Food Engineering, Fuyang Normal University, Fuyang, Anuhi 236041, China
| | - Ming D Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China.,Research Center for Air Pollution and Health, Zhejiang University, Hangzhou, China.,Institute of NeuroImmune Pharmacology, Seton Hall University, South Orange, NJ, United States
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Walsh RM, Roh SH, Gharpure A, Morales-Perez CL, Teng J, Hibbs RE. Structural principles of distinct assemblies of the human α4β2 nicotinic receptor. Nature 2018; 557:261-265. [PMID: 29720657 PMCID: PMC6132059 DOI: 10.1038/s41586-018-0081-7] [Citation(s) in RCA: 149] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 03/23/2018] [Indexed: 11/08/2022]
Abstract
Fast chemical communication in the nervous system is mediated by neurotransmitter-gated ion channels. The prototypical member of this class of cell surface receptors is the cation-selective nicotinic acetylcholine receptor. As with most ligand-gated ion channels, nicotinic receptors assemble as oligomers of subunits, usually as hetero-oligomers and often with variable stoichiometries 1 . This intrinsic heterogeneity in protein composition provides fine tunability in channel properties, which is essential to brain function, but frustrates structural and biophysical characterization. The α4β2 subtype of the nicotinic acetylcholine receptor is the most abundant isoform in the human brain and is the principal target in nicotine addiction. This pentameric ligand-gated ion channel assembles in two stoichiometries of α- and β-subunits (2α:3β and 3α:2β). Both assemblies are functional and have distinct biophysical properties, and an imbalance in the ratio of assemblies is linked to both nicotine addiction2,3 and congenital epilepsy4,5. Here we leverage cryo-electron microscopy to obtain structures of both receptor assemblies from a single sample. Antibody fragments specific to β2 were used to 'break' symmetry during particle alignment and to obtain high-resolution reconstructions of receptors of both stoichiometries in complex with nicotine. The results reveal principles of subunit assembly and the structural basis of the distinctive biophysical and pharmacological properties of the two different stoichiometries of this receptor.
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Affiliation(s)
- Richard M Walsh
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Soung-Hun Roh
- Department of Bioengineering and BioX Program, Stanford University, Stanford, CA, USA
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Anant Gharpure
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Claudio L Morales-Perez
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jinfeng Teng
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ryan E Hibbs
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Tarvin RD, Borghese CM, Sachs W, Santos JC, Lu Y, O'Connell LA, Cannatella DC, Harris RA, Zakon HH. Interacting amino acid replacements allow poison frogs to evolve epibatidine resistance. Science 2018; 357:1261-1266. [PMID: 28935799 DOI: 10.1126/science.aan5061] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 08/24/2017] [Indexed: 12/18/2022]
Abstract
Animals that wield toxins face self-intoxication. Poison frogs have a diverse arsenal of defensive alkaloids that target the nervous system. Among them is epibatidine, a nicotinic acetylcholine receptor (nAChR) agonist that is lethal at microgram doses. Epibatidine shares a highly conserved binding site with acetylcholine, making it difficult to evolve resistance yet maintain nAChR function. Electrophysiological assays of human and frog nAChR revealed that one amino acid replacement, which evolved three times in poison frogs, decreased epibatidine sensitivity but at a cost of acetylcholine sensitivity. However, receptor functionality was rescued by additional amino acid replacements that differed among poison frog lineages. Our results demonstrate how resistance to agonist toxins can evolve and that such genetic changes propel organisms toward an adaptive peak of chemical defense.
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Affiliation(s)
- Rebecca D Tarvin
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA.
| | - Cecilia M Borghese
- Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, USA
| | - Wiebke Sachs
- Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, USA.,Department of Biology, University of Konstanz, Konstanz, Germany 78457
| | - Juan C Santos
- Department of Biological Sciences, St. John's University, Queens, NY 11439, USA
| | - Ying Lu
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Lauren A O'Connell
- Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - David C Cannatella
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA.,Biodiversity Center, University of Texas at Austin, Austin, TX 78712, USA
| | - R Adron Harris
- Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, USA
| | - Harold H Zakon
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
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Lyu G, Han YL. [Research advances in hereditary epilepsy and precision drug therapy]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2017; 19:1118-1123. [PMID: 29046212 PMCID: PMC7389281 DOI: 10.7499/j.issn.1008-8830.2017.10.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 05/27/2017] [Indexed: 06/07/2023]
Abstract
Epilepsy is a common nervous system disease. It has been found that the pathogenesis of epilepsy is associated mutations in various genes, including genes encoding voltage-dependent ion channel, genes encoding ligand-gated ion channel, and solute carrier family genes. Different types of epilepsy caused by different mutations have different responses to drugs, and therefore, diagnosis and medication guidance based on genes are new thoughts for developing therapies. With the application of next-generation sequencing technology, more and more genes will be determined, which helps to further study the pathogenic mechanism of mutant genes and provides a basis for precision drug therapy for epilepsy.
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Affiliation(s)
- Ge Lyu
- Department of Pediatrics, First Affiliated Hospital of Guangxi Medical University, Nanning 530000, China.
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19
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Lyu G, Han YL. [Research advances in hereditary epilepsy and precision drug therapy]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2017; 19:1118-1123. [PMID: 29046212 PMCID: PMC7389281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 05/27/2017] [Indexed: 11/12/2023]
Abstract
Epilepsy is a common nervous system disease. It has been found that the pathogenesis of epilepsy is associated mutations in various genes, including genes encoding voltage-dependent ion channel, genes encoding ligand-gated ion channel, and solute carrier family genes. Different types of epilepsy caused by different mutations have different responses to drugs, and therefore, diagnosis and medication guidance based on genes are new thoughts for developing therapies. With the application of next-generation sequencing technology, more and more genes will be determined, which helps to further study the pathogenic mechanism of mutant genes and provides a basis for precision drug therapy for epilepsy.
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Affiliation(s)
- Ge Lyu
- Department of Pediatrics, First Affiliated Hospital of Guangxi Medical University, Nanning 530000, China.
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Puligheddu M, Melis M, Pillolla G, Milioli G, Parrino L, Terzano GM, Aroni S, Sagheddu C, Marrosu F, Pistis M, Muntoni AL. Rationale for an adjunctive therapy with fenofibrate in pharmacoresistant nocturnal frontal lobe epilepsy. Epilepsia 2017; 58:1762-1770. [DOI: 10.1111/epi.13863] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Monica Puligheddu
- Sleep Disorder Research Center; Department of Medical Sciences and Public Health; University of Cagliari; Cagliari Italy
| | - Miriam Melis
- Department of Biomedical Sciences; University of Cagliari; Monserrato Italy
| | - Giuliano Pillolla
- Department of Biomedical Sciences; University of Cagliari; Monserrato Italy
| | - Giulia Milioli
- Department of Neurosciences; Sleep Disorder Center; University of Parma; Parma Italy
| | - Liborio Parrino
- Department of Neurosciences; Sleep Disorder Center; University of Parma; Parma Italy
| | | | - Sonia Aroni
- Department of Biomedical Sciences; University of Cagliari; Monserrato Italy
| | - Claudia Sagheddu
- Department of Biomedical Sciences; University of Cagliari; Monserrato Italy
| | - Francesco Marrosu
- Sleep Disorder Research Center; Department of Medical Sciences and Public Health; University of Cagliari; Cagliari Italy
- Department of Medical Sciences and Public Health; University of Cagliari; Cagliari Italy
| | - Marco Pistis
- Department of Biomedical Sciences; University of Cagliari; Monserrato Italy
- Neuroscience Institute; National Research Council of Italy; Cagliari Italy
| | - Anna Lisa Muntoni
- Neuroscience Institute; National Research Council of Italy; Cagliari Italy
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Lucero LM, Weltzin MM, Eaton JB, Cooper JF, Lindstrom JM, Lukas RJ, Whiteaker P. Differential α4(+)/(-)β2 Agonist-binding Site Contributions to α4β2 Nicotinic Acetylcholine Receptor Function within and between Isoforms. J Biol Chem 2015; 291:2444-59. [PMID: 26644472 DOI: 10.1074/jbc.m115.684373] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Indexed: 11/06/2022] Open
Abstract
Two α4β2 nicotinic acetylcholine receptor (α4β2-nAChR) isoforms exist with (α4)2(β2)3 and (α4)3(β2)2 subunit stoichiometries and high versus low agonist sensitivities (HS and LS), respectively. Both isoforms contain a pair of α4(+)/(-)β2 agonist-binding sites. The LS isoform also contains a unique α4(+)/(-)α4 site with lower agonist affinity than the α4(+)/(-)β2 sites. However, the relative roles of the conserved α4(+)/(-)β2 agonist-binding sites in and between the isoforms have not been studied. We used a fully linked subunit concatemeric nAChR approach to express pure populations of HS or LS isoform α4β2*-nAChR. This approach also allowed us to mutate individual subunit interfaces, or combinations thereof, on each isoform background. We used this approach to systematically mutate a triplet of β2 subunit (-)-face E-loop residues to their non-conserved α4 subunit counterparts or vice versa (β2HQT and α4VFL, respectively). Mutant-nAChR constructs (and unmodified controls) were expressed in Xenopus oocytes. Acetylcholine concentration-response curves and maximum function were measured using two-electrode voltage clamp electrophysiology. Surface expression was measured with (125)I-mAb 295 binding and was used to define function/nAChR. If the α4(+)/(-)β2 sites contribute equally to function, making identical β2HQT substitutions at either site should produce similar functional outcomes. Instead, highly differential outcomes within the HS isoform, and between the two isoforms, were observed. In contrast, α4VFL mutation effects were very similar in all positions of both isoforms. Our results indicate that the identity of subunits neighboring the otherwise equivalent α4(+)/(-)β2 agonist sites modifies their contributions to nAChR activation and that E-loop residues are an important contributor to this neighbor effect.
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Affiliation(s)
- Linda M Lucero
- From the Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013 and
| | - Maegan M Weltzin
- From the Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013 and
| | - J Brek Eaton
- From the Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013 and
| | - John F Cooper
- the Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania 19104
| | - Jon M Lindstrom
- the Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, Pennsylvania 19104
| | - Ronald J Lukas
- From the Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013 and
| | - Paul Whiteaker
- From the Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013 and
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