22. 04. 2025
How ligand binding affects the surface expression of NMDA receptors
Lecturer: Jakub Netolický, M.Sc. / Department of Neurochemistry
Annotation: N-Methyl-D-aspartate receptors (NMDARs) play a key role in neuronal excitation. Pathological variants of GluN subunits, particularly within the ligand-binding domains (LBDs), can affect both receptor function and trafficking to the cell surface. Using microscopy, electrophysiology, and molecular simulations (including RMSD, SASA, and binding energy calculations), we investigated the impact of mutations in the GluN1 and GluN2A subunits on NMDAR surface trafficking. Among other findings, we observed that in GluN1-LBD mutants, the number of receptors on the cell surface correlated with glycine sensitivity, while GluN2A-LBD mutations showed no correlation with glutamate sensitivity. Moreover, using the ARIAD system, we confirmed that we specifically studied early trafficking of NMDARs to the cell surface.
Our study provides new insights into how agonist binding in the LBD influences early surface trafficking of NMDARs and further characterises several pathogenic variants. The results were recently published in the Journal of Neuroscience under the title Distinct Regulation of Early Trafficking of the NMDA Receptors by the Ligand-Binding Domains of the GluN1 and GluN2A Subunits (open in a new window).
Using the Mg²-deficient GluN2A-N615S mutation to study the effects of classical and novel open channel blockers
Lecturer: Marek Ladislav, Ph.D. / Department of Neurochemistry
Annotation: Open-channel blockers of NMDA receptors (NMDARs), such as memantine or ketamine, are used in the treatment of neuropsychiatric disorders; however, their efficacy and safety are limited by their pharmacological properties. In our recent study, we described a novel compound, K2060, a dizocilpine derivative, which exhibits reversible and selective inhibition of NMDARs through a distinct mechanism compared to classical channel blockers.
In this talk, we will present not only the published findings but also new data obtained in a knock-in mouse model carrying a mutation in the M2 loop of the GluN2A subunit (GluN2A-N615S), which abolishes the physiological Mg²⁺ block of the channel. This model allows us to investigate how the absence of the Mg²⁺ block influences the action of open-channel blockers. We compared the effects of memantine, ketamine, and K2060 in vitro and in vivo in this context.
Our results demonstrate that disruption of Mg²⁺ block fundamentally alters the pharmacological profile of these drugs and provides new mechanistic insights into NMDAR inhibition. K2060 emerges as a promising candidate with unique properties compared to clinically used open-channel blockers.
