A Frameshift Variant of GluN2A Identified in an Epilepsy Patient Results in NMDA Receptor Mistargeting

• DOI: 10.1523/jneurosci.0557-23.2023
• Publication Date: 2023-11-30T18:50:11Z
• Authors: M. M. Vieira; S. Peng; S. Won; E. Hong; S. K. Inati; A. Thurm; A. H. Thiam; S. Kim; S. J. Myers; J. D. Badger; S. F. Traynelis; W. Lu; K. W. Roche
• Keywords: Postsynaptic density

N -methyl- D -aspartate receptors (NMDARs) are crucial for neuronal development and synaptic plasticity. Dysfunction of NMDARs is associated with multiple neurodevelopmental disorders, including epilepsy, autism spectrum disorder, intellectual disability. Understanding the impact genetic variants NMDAR subunits can shed light on mechanisms disease. Here, we characterized functional implications a de novo mutation GluN2A subunit (P1199Rfs*32) resulting in truncation C-terminal domain. The variant was identified male patient epileptic encephalopathy, seizure types, severe aphasia, neurobehavioral changes. Given known role CTD trafficking, examined changes receptor localization abundance at postsynaptic membrane using combination molecular assays heterologous cells rat primary cultures. We observed that P1199Rfs*32-containing traffic efficiently to but have increased extra-synaptic expression relative WT GluN2A-containing NMDARs. Using silico predictions, hypothesized mutant would lose all PDZ interactions, except recycling protein Scribble1. Indeed, impaired binding scaffolding protein-95 (PSD-95); however, found interacts Scribble1, which facilitates both GluN2A. Finally, neurons expressing P1199Rfs*32 fewer synapses decreased spine density, indicating compromised transmission these neurons. Overall, our data show loss-of-function altered provide mechanistic insight into disease etiology.