TY - JOUR
T1 - Pharmacological characterization of a novel negative allosteric modulator of NMDA receptors, UBP792
AU - Sapkota, Kiran
AU - Burnell, Erica S.
AU - Irvine, Mark W.
AU - Fang, Guangyu
AU - Gawande, Dinesh Y.
AU - Dravid, Shashank M.
AU - Jane, David E.
AU - Monaghan, Daniel T.
N1 - Funding Information:
We would like to thank the laboratories of Drs. Shigetada Nakanishi, Peter Seeburg, Dolan Pritchett and Gabriela Popescu for generously providing cDNA constructs as indicated in the Methods. We would also like to thank Dr. Wally Thoreson for assistance with capacitance measurements. Research reported in this publication was supported by the National Institute of Mental Health of the National Institutes of Health (grant R01MH060252 ), the Medical Research Council (grant G0601812 ) and the Biotechnology and Biological Sciences Research Council (grant BB/L001977/1 ).
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2021/12/15
Y1 - 2021/12/15
N2 - N-methyl-D-aspartate (NMDA) receptors (NMDARs) are a subtype of ionotropic glutamate receptor with important roles in CNS function. Since excessive NMDAR activity can lead to neuronal cell death and epilepsy, there is interest in developing NMDAR negative allosteric modulators (NAMs) as neuroprotective agents. In this study, we characterize the inhibitory properties of a novel NMDAR antagonist, UBP792. This compound displays partial subtype-selectivity by having a varied maximal inhibition of GluN2A-, GluN2B-, GluN2C-, and GluN2D-containing receptors (52%, 70%, 87%, 89%, respectively) with IC50s 4–10 μM. UBP792 inhibited NMDAR responses by reducing L-glutamate and glycine potencies and efficacies. Consistent with non-competitive inhibition, increasing agonist concentrations 30-fold did not reduce UBP792 potency. UBP792 inhibition was also not competitive with the structurally-related positive allosteric modulator (PAM) UBP684. UBP792 activity was voltage-independent, unaffected by GluN1's exon-5, and reduced at low pH (except for GluN1/GluN2A receptors which were more sensitive at acidic pH). UBP792 binding appeared independent of agonist binding and may be entering the plasma membrane to gain access to its binding site. Inhibition by UBP792 is reduced when the ligand-binding domain (LBD) of the GluN2 subunit, but not that of the GluN1 subunit, is cross-linked in the closed-cleft, activated conformation. Thus, UBP792 may be inhibiting by stabilizing an open GluN2-LBD cleft associated with channel inactivation or by stabilizing downstream closed channel conformations allosterically-coupled to the GluN2-LBD. These findings further expand the repertoire displayed by NMDAR NAMs thus expanding the opportunities for developing NMDAR modulators with the most appropriate selectivity and physiological actions for specific therapeutic indications.
AB - N-methyl-D-aspartate (NMDA) receptors (NMDARs) are a subtype of ionotropic glutamate receptor with important roles in CNS function. Since excessive NMDAR activity can lead to neuronal cell death and epilepsy, there is interest in developing NMDAR negative allosteric modulators (NAMs) as neuroprotective agents. In this study, we characterize the inhibitory properties of a novel NMDAR antagonist, UBP792. This compound displays partial subtype-selectivity by having a varied maximal inhibition of GluN2A-, GluN2B-, GluN2C-, and GluN2D-containing receptors (52%, 70%, 87%, 89%, respectively) with IC50s 4–10 μM. UBP792 inhibited NMDAR responses by reducing L-glutamate and glycine potencies and efficacies. Consistent with non-competitive inhibition, increasing agonist concentrations 30-fold did not reduce UBP792 potency. UBP792 inhibition was also not competitive with the structurally-related positive allosteric modulator (PAM) UBP684. UBP792 activity was voltage-independent, unaffected by GluN1's exon-5, and reduced at low pH (except for GluN1/GluN2A receptors which were more sensitive at acidic pH). UBP792 binding appeared independent of agonist binding and may be entering the plasma membrane to gain access to its binding site. Inhibition by UBP792 is reduced when the ligand-binding domain (LBD) of the GluN2 subunit, but not that of the GluN1 subunit, is cross-linked in the closed-cleft, activated conformation. Thus, UBP792 may be inhibiting by stabilizing an open GluN2-LBD cleft associated with channel inactivation or by stabilizing downstream closed channel conformations allosterically-coupled to the GluN2-LBD. These findings further expand the repertoire displayed by NMDAR NAMs thus expanding the opportunities for developing NMDAR modulators with the most appropriate selectivity and physiological actions for specific therapeutic indications.
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U2 - 10.1016/j.neuropharm.2021.108818
DO - 10.1016/j.neuropharm.2021.108818
M3 - Article
C2 - 34610288
AN - SCOPUS:85116687730
VL - 201
JO - Neuropharmacology
JF - Neuropharmacology
SN - 0028-3908
M1 - 108818
ER -