RT Journal Article
SR Electronic
T1 Structural Determinants and Mechanism of Action of a GluN2C-selective NMDA Receptor Positive Allosteric Modulator
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP mol.114.094516
DO 10.1124/mol.114.094516
A1 Alpa Khatri
A1 Pieter B Burger
A1 Sharon A. Swanger
A1 Kasper B. Hansen
A1 Sommer Zimmerman
A1 Erkan Karakas
A1 Dennis C. Liotta
A1 Hiro Furukawa
A1 James P. Snyder
A1 Stephen F. Traynelis
YR 2014
UL http://molpharm.aspetjournals.org/content/early/2014/09/09/mol.114.094516.abstract
AB NMDA receptors are tetrameric complexes of GluN1, GluN2A-D, and GluN3A-B subunits and are involved in normal brain function and neurological disorders. We have identified a novel class of stereo-selective pyrrolidinone (PYD) positive allosteric modulators for GluN2C-containing NMDA receptors, exemplified by methyl 4-(3-acetyl-4-hydroxy-1-(2-(2-methyl-1H-indol-3-yl)ethyl)-5-oxo-2,5-dihydro-1H-pyrrol-2-yl)benzoate. Here we explore the site and mechanism of action of a prototypical analogue PYD-106, which at 30 μM does not alter responses of NMDA receptors containing GluN2A, GluN2B, and GluN2D, and has no effect on AMPA and kainate receptors. Co-application of 50 μM PYD-106 with a maximally effective concentration of glutamate and glycine increases the response of GluN1/GluN2C NMDA receptors in HEK-293 cells to 221% of that obtained in the absence of PYD (taken as 100%). Evaluation of the concentration-dependence of this enhancement revealed an EC50 value for PYD of 13 μM. PYD-106 increased opening frequency and open time of single channel currents activated by maximally effective concentrations of agonist, but only had modest effects on glutamate and glycine EC50. PYD-106 selectively enhanced the responses of diheteromeric GluN1/GluN2C receptors, but not triheteromeric GluN1/GluN2A/GluN2C receptors. Inclusion of residues encoded by GluN1-exon5 attenuated the effects of PYD. Three GluN2C residues (Arg194, Ser470, Lys470), at which mutagenesis virtually eliminated PYD function, line a cavity at the interface of the ligand binding and the amino terminal domains in a homology model of GluN1/GluN2C built from crystallographic data on GluN1/GluN2B. We propose that this domain interface constitutes a new allosteric modulatory site on the NMDA receptor.