title: The novel α7β2-nicotinic acetylcholine receptor subtype is expressed in mouse and human basal forebrain: biochemical and pharmacological characterization.
abstract: We examined α7β2-nicotinic acetylcholine receptor (α7β2-nAChR) expression in mammalian brain and compared pharmacological profiles of homomeric α7-nAChRs and α7β2-nAChRs. α-Bungarotoxin affinity purification or immunoprecipitation with anti-α7 subunit antibodies (Abs) was used to isolate nAChRs containing α7 subunits from mouse or human brain samples. α7β2-nAChRs were detected in forebrain, but not other tested regions, from both species, based on Western blot analysis of isolates using β2 subunit-specific Abs. Ab specificity was confirmed in control studies using subunit-null mutant mice or cell lines heterologously expressing specific human nAChR subtypes and subunits. Functional expression in Xenopus oocytes of concatenated pentameric (α7)5-, (α7)4(β2)1-, and (α7)3(β2)2-nAChRs was confirmed using two-electrode voltage clamp recording of responses to nicotinic ligands. Importantly, pharmacological profiles were indistinguishable for concatenated (α7)5-nAChRs or for homomeric α7-nAChRs constituted from unlinked α7 subunits. Pharmacological profiles were similar for (α7)5-, (α7)4(β2)1-, and (α7)3(β2)2-nAChRs except for diminished efficacy of nicotine (normalized to acetylcholine efficacy) at α7β2- versus α7-nAChRs. This study represents the first direct confirmation of α7β2-nAChR expression in human and mouse forebrain, supporting previous mouse studies that suggested relevance of α7β2-nAChRs in Alzheimer disease etiopathogenesis. These data also indicate that α7β2-nAChR subunit isoforms with different α7/β2 subunit ratios have similar pharmacological profiles to each other and to α7 homopentameric nAChRs. This supports the hypothesis that α7β2-nAChR agonist activation predominantly or entirely reflects binding to α7/α7 subunit interface sites.
authors.affiliation: CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.).
authors.forename: Milena
authors.initials: M
authors.lastname: Moretti
authors.affiliation: CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.).
authors.forename: Michele
authors.initials: M
authors.lastname: Zoli
authors.affiliation: CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.).
authors.forename: Andrew A
authors.initials: AA
authors.lastname: George
authors.affiliation: CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.).
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Lukas
authors.affiliation: CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.).
authors.forename: Francesco
authors.initials: F
authors.lastname: Pistillo
authors.affiliation: CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.).
authors.forename: Uwe
authors.initials: U
authors.lastname: Maskos
authors.affiliation: CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.) c.gotti@in.cnr paul.whiteaker@dignityhealth.org.
authors.forename: Paul
authors.initials: P
authors.lastname: Whiteaker
authors.affiliation: CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.) c.gotti@in.cnr paul.whiteaker@dignityhealth.org.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Gotti
mesh_terms: D000818:Animals; D001665:Binding Sites; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002038:Bungarotoxins / Q000494:pharmacology; D002531:Cerebellum / Q000378:metabolism; D005260:Female; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018722:Nicotinic Agonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D009865:Oocytes / Q000378:metabolism; D016548:Prosencephalon / Q000378:metabolism*; D055503:Protein Multimerization; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D011869:Radioligand Assay; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis; D064569:alpha7 Nicotinic Acetylcholine Receptor / Q000235:genetics / Q000378:metabolism*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D002038:Bungarotoxins; D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D021122:Protein Subunits; D011725:Pyridines; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; C082748:epibatidine