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Updated: Jun 28, 2026
A High-throughput Calcium-flux Assay to Study NMDA-receptors with Sensitivity to Glycine/D-serine and Glutamate
Published on: July 10, 2018
Specific targeting of pro-death NMDA receptor signals with differing reliance on the NR2B PDZ ligand
Francesc X Soriano1, Marc-Andre Martel, Sofia Papadia
1Centres for Integrative Physiology and Neuroscience Research, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom.
Abstract:
NMDA receptors (NMDARs) mediate ischemic brain damage, for which interactions between the C termini of NR2 subunits and PDZ domain proteins within the NMDAR signaling complex (NSC) are emerging therapeutic targets. However, expression of NMDARs in a non-neuronal context, lacking many NSC components, can still induce cell death. Moreover, it is unclear whether targeting the NSC will impair NMDAR-dependent prosurvival and plasticity signaling. We show that the NMDAR can promote death signaling independently of the NR2 PDZ ligand, when expressed in non-neuronal cells lacking PSD-95 and neuronal nitric oxide synthase (nNOS), key PDZ proteins that mediate neuronal NMDAR excitotoxicity. However, in a non-neuronal context, the NMDAR promotes cell death solely via c-Jun N-terminal protein kinase (JNK), whereas NMDAR-dependent cortical neuronal death is promoted by both JNK and p38. NMDAR-dependent pro-death signaling via p38 relies on neuronal context, although death signaling by JNK, triggered by mitochondrial reactive oxygen species production, does not. NMDAR-dependent p38 activation in neurons is triggered by submembranous Ca(2+), and is disrupted by NOS inhibitors and also a peptide mimicking the NR2B PDZ ligand (TAT-NR2B9c). TAT-NR2B9c reduced excitotoxic neuronal death and p38-mediated ischemic damage, without impairing an NMDAR-dependent plasticity model or prosurvival signaling to CREB or Akt. TAT-NR2B9c did not inhibit JNK activation, and synergized with JNK inhibitors to ameliorate severe excitotoxic neuronal loss in vitro and ischemic cortical damage in vivo. Thus, NMDAR-activated signals comprise pro-death pathways with differing requirements for PDZ protein interactions. These signals are amenable to selective inhibition, while sparing synaptic plasticity and prosurvival signaling.
Insights
Targeting NMDA receptor (NMDAR) signaling pathways offers a novel therapeutic strategy for ischemic brain damage. Selective inhibition of pro-death NMDAR signals spares prosurvival pathways, reducing neuronal loss without impairing plasticity.
Area of Science:
- Neuroscience
- Cell Biology
- Pharmacology
Background:
- NMDA receptors (NMDARs) are critical mediators of ischemic brain damage.
- Interactions between NMDAR C termini and PDZ proteins in the NMDAR signaling complex (NSC) are potential therapeutic targets.
- NMDARs can induce cell death even in non-neuronal cells lacking key NSC components.
Purpose of the Study:
- To investigate whether targeting the NSC impairs NMDAR-dependent prosurvival and plasticity signaling.
- To elucidate the mechanisms of NMDAR-mediated cell death in neuronal and non-neuronal contexts.
- To evaluate the therapeutic potential of selectively inhibiting pro-death NMDAR pathways.
Main Methods:
- Expression of NMDARs in non-neuronal cells lacking PSD-95 and nNOS.
- Analysis of NMDAR-mediated cell death pathways, including JNK and p38 activation.
- Pharmacological inhibition of NMDAR signaling using a peptide mimicking the NR2B PDZ ligand (TAT-NR2B9c).
- Assessment of NMDAR-dependent plasticity, prosurvival signaling (CREB, Akt), and excitotoxic/ischemic damage in vitro and in vivo.
Main Results:
- NMDARs promote cell death independently of the NR2 PDZ ligand in non-neuronal cells, primarily via JNK.
- Neuronal NMDAR-dependent death involves both JNK and p38 pathways; p38 activation relies on neuronal context and Ca(2+).
- TAT-NR2B9c selectively reduced excitotoxic neuronal death and p38-mediated ischemic damage without affecting prosurvival signaling or plasticity.
- TAT-NR2B9c synergized with JNK inhibitors to protect against severe neuronal loss and ischemic damage.
Conclusions:
- NMDAR-activated pro-death signaling pathways have distinct requirements for PDZ protein interactions.
- Selective inhibition of specific NMDAR pro-death pathways is achievable.
- Targeting NMDARs can ameliorate ischemic brain damage while preserving crucial prosurvival and plasticity functions.
