title: Single-channel and structural foundations of neuronal α7 acetylcholine receptor potentiation.
abstract: Potentiation of neuronal nicotinic acetylcholine receptors by exogenous ligands is a promising strategy for treatment of neurological disorders including Alzheimer's disease and schizophrenia. To gain insight into molecular mechanisms underlying potentiation, we examined ACh-induced single-channel currents through the human neuronal α7 acetylcholine receptor in the presence of the α7-specific potentiator PNU-120596 (PNU). Compared to the unusually brief single-channel opening episodes elicited by agonist alone, channel opening episodes in the presence of agonist and PNU are dramatically prolonged. Dwell time analysis reveals that PNU introduces two novel components into open time histograms, indicating at least two degrees of PNU-induced potentiation. Openings of the longest potentiated class coalesce into clusters whose frequency and duration change over a narrow range of PNU concentration. At PNU concentrations approaching saturation, these clusters last up to several minutes, prolonging the submillisecond α7 opening episodes by several orders of magnitude. Mutations known to reduce PNU potentiation at the whole-cell level still give rise to multisecond-long single-channel clusters. However mutation of five residues lining a cavity within each subunit's transmembrane domain abolishes PNU potentiation, defining minimal structural determinants of PNU potentiation.
authors.affiliation: Receptor Biology Laboratory, Departments of Physiology and Biomedical Engineering and Neurology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
authors.forename: Corrie J B
authors.initials: CJ
authors.lastname: daCosta
authors.forename: Chris R
authors.initials: CR
authors.lastname: Free
authors.forename: Jeremías
authors.initials: J
authors.lastname: Corradi
authors.forename: Cecilia
authors.initials: C
authors.lastname: Bouzat
authors.forename: Steven M
authors.initials: SM
authors.lastname: Sine
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D057809:HEK293 Cells; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology; D009154:Mutation / Q000502:physiology*; D009474:Neurons; D010671:Phenylurea Compounds / Q000494:pharmacology; D017433:Protein Structure, Secondary / Q000235:genetics; D011978:Receptors, Nicotinic / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D064569:alpha7 Nicotinic Acetylcholine Receptor
chemical_list: C508388:1-(5-chloro-2,4-dimethoxyphenyl)-3-(5-methylisoxazol-3-yl)urea; C579167:Chrna7 protein, human; D007555:Isoxazoles; D010671:Phenylurea Compounds; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor