Functional characterization of Tet-AMPA [tetrazolyl-2-amino-3-(3-hydroxy-5-methyl- 4-isoxazolyl)propionic acid] analogues at ionotropic glutamate receptors GluR1-GluR4. The molecular basis for the functional selectivity profile of 2-Bn-Tet-AMPA.
Four 2-substituted Tet-AMPA [Tet = tetrazolyl, AMPA = 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid] analogues were characterized functionally at the homomeric AMPA receptors GluR1i, GluR2Qi, GluR3i, and GluR4i in a Fluo-4/Ca2+ assay. Whereas 2-Et-Tet-AMPA, 2-Pr-Tet-AMPA, and 2-iPr-Tet-AMPA were nonselective GluR agonists, 2-Bn-Tet-AMPA exhibited a 40-fold higher potency at GluR4i than at GluR1i. Examination of homology models of the S1-S2 domains of GluR1 and GluR4 containing 2-Bn-Tet-AMPA suggested four nonconserved residues in a region adjacent to the orthosteric site as possible determinants of the GluR4i/GluR1i selectivity. In a mutagenesis study, doubly mutating M686V/I687A in GluR1i in combination with either D399S or E683A increased both the potency and the maximal response of 2-Bn-Tet-AMPA at this receptor to levels similar to those elicited by the agonist at GluR4i. The dependence of the novel selectivity profile of 2-Bn-Tet-AMPA upon residues located outside of the orthosteric site underlines the potential for developing GluR subtype selective ligands by designing compounds with substituents that protrude beyond the (S)-Glu binding pocket.
Jensen
Anders A
AA
Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark. aaj@farma.ku.dk
Christesen
Thomas
T
Bølcho
Ulrik
U
Greenwood
Jeremy R
JR
Postorino
Giovanna
G
Vogensen
Stine B
SB
Johansen
Tommy N
TN
Egebjerg
Jan
J
Bräuner-Osborne
Hans
H
Clausen
Rasmus P
RP
D000814:Aniline Compounds; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D005260:Female; D005456:Fluorescent Dyes; D006801:Humans; D066298:In Vitro Techniques; D007555:Isoxazoles / Q000737:chemistry* / Q000494:pharmacology; D008958:Models, Molecular; D009154:Mutation; D009865:Oocytes / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D011422:Propionates / Q000737:chemistry* / Q000494:pharmacology; D051381:Rats; D018091:Receptors, AMPA / Q000819:agonists* / Q000235:genetics / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013777:Tetrazoles / Q000737:chemistry* / Q000494:pharmacology; D013816:Thermodynamics; D014966:Xanthenes; D014981:Xenopus; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology
D000814:Aniline Compounds; D005456:Fluorescent Dyes; D007555:Isoxazoles; D011422:Propionates; D018091:Receptors, AMPA; D013777:Tetrazoles; D014966:Xanthenes; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; C520859:2-amino-3-(3-hydroxy-5-(2-benzyl-2H-5-tetrazolyl)-4-isoxazolyl)propionic acid; C409648:Fluo 4; C104723:glutamate receptor ionotropic, AMPA 3; C104724:glutamate receptor ionotropic, AMPA 4; C104722:glutamate receptor ionotropic, AMPA 2