TY - JOUR

T1 - Identification and Structure-Function Study of Positive Allosteric Modulators of Kainate Receptors

AU - Larsen, Anja Probst

AU - Fièvre, Sabine

AU - Frydenvang, Karla

AU - Francotte, Pierre

AU - Pirotte, Bernard

AU - Kastrup, Jette Sandholm

AU - Mulle, Christophe

N1 - Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

PY - 2017/6

Y1 - 2017/6

N2 - Kainate receptors (KARs) consist of a class of ionotropic glutamate receptors, which exert diverse pre- and postsynaptic functions through complex signaling regulating the activity of neural circuits. Whereas numerous small-molecule positive allosteric modulators of the ligand-binding domain of (S)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propanoic acid (AMPA) receptors have been reported, no such ligands are available for KARs. In this study, we investigated the ability of three benzothiadiazine-based modulators to potentiate glutamate-evoked currents at recombinantly expressed KARs. 4-cyclopropyl-7-fluoro-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide (BPAM344) potentiated glutamate-evoked currents of GluK2a 21-fold at the highest concentration tested (200 μM), with an EC50 of 79 μM. BPAM344 markedly decreased desensitization kinetics (from 5.5 to 775 ms), whereas it only had a minor effect on deactivation kinetics. 4-cyclopropyl-7-hydroxy-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide (BPAM521) potentiated the recorded peak current amplitude of GluK2a 12-fold at a concentration of 300 μM with an EC50 value of 159 μM, whereas no potentiation of the glutamate-evoked response was observed for 7-chloro-4-(2-fluoroethyl)-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide (BPAM121) at the highest concentration of modulator tested (300 μM). BPAM344 (100 μM) also potentiated the peak current amplitude of KAR subunits GluK3a (59-fold), GluK2a (15-fold), GluK1b (5-fold), as well as the AMPA receptor subunit GluA1i (5-fold). X-ray structures of the three modulators in the GluK1 ligand-binding domain were determined, locating two modulator-binding sites at the GluK1 dimer interface. In conclusion, this study may enable the design of new positive allosteric modulators selective for KARs, which will be of great interest for further investigation of the function of KARs in vivo and may prove useful for pharmacologically controlling the activity of neuronal networks.

AB - Kainate receptors (KARs) consist of a class of ionotropic glutamate receptors, which exert diverse pre- and postsynaptic functions through complex signaling regulating the activity of neural circuits. Whereas numerous small-molecule positive allosteric modulators of the ligand-binding domain of (S)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propanoic acid (AMPA) receptors have been reported, no such ligands are available for KARs. In this study, we investigated the ability of three benzothiadiazine-based modulators to potentiate glutamate-evoked currents at recombinantly expressed KARs. 4-cyclopropyl-7-fluoro-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide (BPAM344) potentiated glutamate-evoked currents of GluK2a 21-fold at the highest concentration tested (200 μM), with an EC50 of 79 μM. BPAM344 markedly decreased desensitization kinetics (from 5.5 to 775 ms), whereas it only had a minor effect on deactivation kinetics. 4-cyclopropyl-7-hydroxy-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide (BPAM521) potentiated the recorded peak current amplitude of GluK2a 12-fold at a concentration of 300 μM with an EC50 value of 159 μM, whereas no potentiation of the glutamate-evoked response was observed for 7-chloro-4-(2-fluoroethyl)-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide (BPAM121) at the highest concentration of modulator tested (300 μM). BPAM344 (100 μM) also potentiated the peak current amplitude of KAR subunits GluK3a (59-fold), GluK2a (15-fold), GluK1b (5-fold), as well as the AMPA receptor subunit GluA1i (5-fold). X-ray structures of the three modulators in the GluK1 ligand-binding domain were determined, locating two modulator-binding sites at the GluK1 dimer interface. In conclusion, this study may enable the design of new positive allosteric modulators selective for KARs, which will be of great interest for further investigation of the function of KARs in vivo and may prove useful for pharmacologically controlling the activity of neuronal networks.

KW - Allosteric Regulation

KW - Animals

KW - Dose-Response Relationship, Drug

KW - Excitatory Amino Acid Agonists

KW - HEK293 Cells

KW - Humans

KW - Protein Structure, Secondary

KW - Rats

KW - Receptors, Kainic Acid

KW - Structure-Activity Relationship

KW - X-Ray Diffraction

KW - Journal Article

U2 - 10.1124/mol.116.107599

DO - 10.1124/mol.116.107599

M3 - Journal article

C2 - 28360094

VL - 91

SP - 576

EP - 585

JO - Molecular Pharmacology

JF - Molecular Pharmacology

SN - 0026-895X

IS - 6

ER -