title: Development of potent fluorescent polyamine toxins and application in labeling of ionotropic glutamate receptors in hippocampal neurons.
abstract: The natural product argiotoxin-636 (ArgTX-636) found in the venom of the Argiope lobata spider is a potent open-channel blocker of ionotropic glutamate (iGlu) receptors, and recently, two analogues, ArgTX-75 and ArgTX-48, were identified with increased potency and selectivity for iGlu receptor subtypes. Here, we have exploited these analogues as templates in the development of fluorescent iGlu receptor ligands to be employed as unique tools for dynamic studies. Eighteen fluorescent analogues were designed and synthesized, and subsequently pharmacologically evaluated at three iGlu receptor subtypes, which resulted in the discovery of highly potent fluorescent iGlu receptor antagonists with IC50 values as low as 11 nM. The most promising ligands were further characterized showing retention of their mechanism of action, as open-channel blockers of iGlu receptors, as well as preservation of the photophysical properties of the incorporated fluorophores. Finally, we demonstrate the applicability of the developed probes for imaging of iGlu receptors in hippocampal neurons.
authors.affiliation: Department of Drug Design and Pharmacology, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Niels G
authors.initials: NG
authors.lastname: Nørager
authors.forename: Christel B
authors.initials: CB
authors.lastname: Jensen
authors.forename: Mette
authors.initials: M
authors.lastname: Rathje
authors.forename: Jacob
authors.initials: J
authors.lastname: Andersen
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Madsen
authors.forename: Anders S
authors.initials: AS
authors.lastname: Kristensen
authors.forename: Kristian
authors.initials: K
authors.lastname: Strømgaard
mesh_terms: D000818:Animals; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology*; D007210:Indoleacetic Acids / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D008024:Ligands; D008958:Models, Molecular; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D011073:Polyamines / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D058468:Receptors, Ionotropic Glutamate / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D013194:Staining and Labeling
chemical_list: D005456:Fluorescent Dyes; D007210:Indoleacetic Acids; D008024:Ligands; D011073:Polyamines; D058468:Receptors, Ionotropic Glutamate; C558368:argiotoxin-636