ABSTRACT
The nicotinic acetylcholine receptors (nAChR) are ligand-gated ion channels involved in cognitive processes and are associated with brain disorders which makes them interesting drug targets. This article presents a general overview of the receptor to introduce the α7 nAChR as a drug target. The advances in understanding of the structure/function properties of the nAChR produced during the last decade are detailed as they are crucial for rational drug design. The allosteric properties of the nAChR will also be described because they also have important consequences for drug design.
Subject(s)
Brain Diseases/drug therapy , Drug Delivery Systems , Receptors, Nicotinic/metabolism , Allosteric Regulation/physiology , Animals , Brain Diseases/physiopathology , Cognition/physiology , Drug Design , Humans , alpha7 Nicotinic Acetylcholine ReceptorABSTRACT
Different photoremovable protecting groups in the o-nitrobenzyl, phenacyl, and 2-(o-nitrophenyl)propyl series with a donor-acceptor biphenyl backbone, known to display excellent two-photon absorption cross-sections, were investigated in order to develop efficient two-photon sensitive photoremovable protecting groups. The 2-(o-nitrophenyl)propyl series was a more versatile platform to increase the two-photon sensitivity of photoremovable protecting groups, leading to the p-alkoxy and p-bisalkylamino-4-nitro-[1,1'-biphenyl]-3-yl)propyl derivatives: PENB and EANBP respectively. Those two photoremovable protecting groups are to date the best caging groups for two-photon excitation at 800 and 740 nm respectively, offering attracting perspectives in chemical biology.
Subject(s)
Biphenyl Compounds/chemistry , Nitrobenzenes/chemistry , Photons , Molecular Structure , PhotolysisABSTRACT
The binding modes of noncompetitive GABA(A)-channel blockers were re-examined taking into account the recent description of the 3D structure of prokaryotic pentameric ligand-gated ion channels, which provided access to new mammalian or insect GABA receptor models, emphasizing their transmembrane portion. Two putative binding modes were deciphered for this class of compounds, including the insecticide fipronil, located nearby either the intra- or the extracellular part of the membrane, respectively. These results are in full agreement with previously described affinity-labeling reactions performed with GABA(A) noncompetitive blockers (Perret et al. J. Biol. Chem.1999, 274, 25350-25354).
Subject(s)
Affinity Labels , GABA-A Receptor Antagonists/metabolism , Insecticides/metabolism , Receptors, GABA-A/metabolism , Amino Acid Sequence , Animals , Binding Sites , GABA-A Receptor Antagonists/chemistry , Insecticides/chemistry , Models, Molecular , Molecular Sequence Data , Mutagenesis, Site-Directed , Protein Binding , Protein Engineering , Pyrazoles/metabolism , Rats , Receptors, GABA-A/chemistry , Receptors, GABA-A/geneticsABSTRACT
GABA(A) receptors are the major inhibitory neurotransmitter receptors in the brain. Some of them are targets of benzodiazepines that are widely used in clinical practice for their sedative/hypnotic, anxiolytic, muscle relaxant and anticonvulsant effects. In order to rationally separate these different drug actions, we need to understand the interaction of such compounds with the benzodiazepine-binding pocket. With this aim, we mutated residues located in the benzodiazepine-binding site individually to cysteine. These mutated receptors were combined with benzodiazepine site ligands carrying a cysteine reactive group in a defined position. Proximal apposition of reaction partners will lead to a covalent reaction. We describe here such proximity-accelerated chemical coupling reactions of alpha(1)S205C and alpha(1)T206C with a diazepam derivative modified at the C-3 position with a reactive isothiocyanate group (-NCS). We also provide new data that identify alpha(1)H101C and alpha(1)N102C as exclusive sites of the reaction of a diazepam derivative where the -Cl atom is replaced by a -NCS group. Based on these observations we propose a relative positioning of diazepam within the benzodiazepine-binding site of alpha(1)beta(2)gamma(2) receptors.
Subject(s)
Anti-Anxiety Agents/pharmacology , Benzodiazepines/metabolism , Diazepam/pharmacology , Receptors, GABA-A/drug effects , Receptors, GABA-A/metabolism , Allosteric Regulation/genetics , Animals , Benzodiazepines/chemistry , Binding Sites/drug effects , Binding Sites/genetics , Biophysics , Cell Line, Transformed , Cysteine/metabolism , Dizocilpine Maleate/analogs & derivatives , Dizocilpine Maleate/pharmacology , Dose-Response Relationship, Drug , Electric Stimulation/methods , Flumazenil/pharmacology , GABA Modulators/pharmacology , Humans , Membrane Potentials/drug effects , Oocytes , Point Mutation/genetics , Protein Binding/drug effects , Receptors, GABA-A/genetics , Structure-Activity Relationship , Transfection/methods , Xenopus , gamma-Aminobutyric Acid/pharmacologyABSTRACT
A pi-extended [2-(2-nitrophenyl)propoxy]carbonyl (NPPOC) derivative has been prepared as an efficient UV and near-IR photolabile protecting group for glutamate. This glutamate cage compound exhibits efficient photorelease upon one-photon excitation (epsilonPhi=990 M(-1) cm(-1) at 315 nm). In addition, it also shows efficient photorelease in activation of glutamate receptors in electrophysiological recordings. Combined with a high two-photon uncaging cross-section (deltaPhi=0.45 GM at 800 nm), its overall properties make this new cage-3-(2-propyl)-4'-methoxy-4-nitrobiphenyl (PMNB)-for glutamate a very promising tool for two-photon neuronal studies.
