# Structural and functional investigation of negative allosteric NMDA receptor modulation

> **NIH NIH R01** · UNIVERSITY OF MONTANA · 2020 · $317,188

## Abstract

NMDA receptors (NMDARs) are glutamate receptor ion channels that mediate excitatory neurotransmission.
The majority of NMDARs are composed of two GluN1 and two GluN2 subunits. One GluN1 subunit has been
cloned, but there are four GluN2 subunits (GluN2A-D) that endow NMDARs with distinct functional properties
and different developmental and regional expression. Mutations in the gene encoding the GluN2A subunit have
been associated with childhood epilepsy/aphasia syndromes, and a subset of these mutations cause gain-of-
function in GluN2A-containing receptors that lead to severe neurologic complications. The high frequency of
GluN2A mutations linked to neurologic conditions provides a compelling rationale for the development of
GluN2A-selective therapeutic agents. GluN2A-selective modulators can also be useful and much needed
pharmacological tools for neurophysiological studies. We have identified novel GluN2A-selective negative
allosteric modulators (NAMs) that inhibit NMDARs by reducing glycine binding to the GluN1 subunit. These
NAMs can transform our ability to evaluate the contribution of GluN2A to normal brain function and disease. In
addition, we have determined crystal structures of the heterodimer formed by GluN1 and GluN2A agonist
binding domains (ABDs) with NAMs bound at the subunit interface. These crystal structures represent the
discovery of a novel, unexplored modulatory site and provide new opportunities for the development of subunit-
selective ligands. We will uncover structural and mechanistic features of this modulatory site and provide
important understanding required for the use of GluN2A-selective NAMs as pharmacological tools. Aim 1)
What are the structural bases for selectivity, potency, and efficacy of GluN2A-selective NAMs? We will use
crystallography, mutagenesis, and electrophysiological recordings of NMDA receptor function to define the
structural determinants for NAM inhibition. Aim 2) What is the mechanistic basis for allosteric interaction
between NAM and glycine binding sites? Crystallographic, pharmacological, and mutational analyses will
dissect the conformational changes and mechanism that causes the allosteric interaction between NAM and
glycine binding sites. Aim 3) Can GluN2A-selective NAMs inhibit triheteromeric and neuronal NMDA
receptors? We will define NAM inhibition of NMDARs in conditions relevant to synaptic transmission as well as
NAM inhibition of NMDARs that contain gain-of-function GluN2A mutations identified in epilepsy patients.
Neuronal NMDARs are heterogeneous populations of diheteromeric receptors comprised of two GluN1 and
two identical GluN2 subunits (e.g. GluN1/GluN2A) as well as triheteromeric receptors containing two GluN1
and two different GluN2 subunits (e.g. GluN1/GluN2A/GluN2B). Evaluation of GluN2A-selective modulators on
both diheteromeric and triheteromeric receptors is required for their use as pharmacological tools. In addition,
we will inhibit NMDAR-mediated synaptic currents in...

## Key facts

- **NIH application ID:** 9925846
- **Project number:** 5R01NS097536-05
- **Recipient organization:** UNIVERSITY OF MONTANA
- **Principal Investigator:** Kasper Boe Hansen
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $317,188
- **Award type:** 5
- **Project period:** 2016-08-01 → 2021-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9925846

## Citation

> US National Institutes of Health, RePORTER application 9925846, Structural and functional investigation of negative allosteric NMDA receptor modulation (5R01NS097536-05). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9925846. Licensed CC0.

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