title: Functional insight into development of positive allosteric modulators of AMPA receptors.
abstract: Positive allosteric modulators of α-amino-3-hydroxy-5-methyl-isoxazole-propionic acid (AMPA) ionotropic glutamate receptors facilitate synaptic plasticity and contribute essentially to learning and memory, properties which make AMPA receptors targets for drug discovery and development. One region at which several different classes of positive allosteric modulators bind lies at the dimer interface between the ligand-binding core of the second, membrane-proximal, extracellular domain of AMPA receptors. This solvent-accessible binding pocket has been the target of drug discovery efforts, leading to the recent delineation of five "subsites" which differentially allow access to modulator moieties, and for which distinct modulator affinities and apparent efficacies are attributed. Here we use the voltage-clamp technique in conjunction with rapid drug application to study the effects of mutants lining subsites "A" and "B" of the allosteric modulator pocket to assess affinity and efficacy of allosteric modulation by cyclothiazide, CX614, CMPDA and CMPDB. A novel analysis of the decay of current produced by the onset of desensitization has allowed us to estimate both affinity and efficacy from single concentrations of modulator. Such an approach may be useful for effective high throughput screening of new target compounds.
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1617, USA. Electronic address: autumnmweeks@gmail.com.
authors.forename: Autumn M
authors.initials: AM
authors.lastname: Weeks
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1617, USA. Electronic address: Jonathan.Harms@colostate.edu.
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Harms
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1617, USA. Electronic address: Kathy.partin@colostate.edu.
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Partin
authors.affiliation: Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, GA 30310-1495, USA. Electronic address: mbenvensiste@msm.edu.
authors.forename: Morris
authors.initials: M
authors.lastname: Benveniste
mesh_terms: D001581:Benzothiadiazines / Q000737:chemistry / Q000494:pharmacology; D001665:Binding Sites / Q000187:drug effects / Q000235:genetics; D003198:Computer Simulation; D055808:Drug Discovery; D018683:Excitatory Amino Acid Agents / Q000737:chemistry / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008958:Models, Molecular; D009154:Mutation; D010078:Oxazines / Q000737:chemistry / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D018091:Receptors, AMPA / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D001581:Benzothiadiazines; D018683:Excitatory Amino Acid Agents; D010078:Oxazines; D018091:Receptors, AMPA; C414782:2H,3H,6aH-pyrrolidino(2'',1''-3',2')1,3-oxazino(6',5'-5,4)benzo(e)1, 4-dioxan-10-one; C004639:cyclothiazide
keywords: AMPAkine; Allosteric modulation; Deactivation; Desensitization; Electrophysiology; Ion channel gating; Mutagenesis; Neuropharmacology