Numerous endogenous and synthetic ligands modulate NMDA receptor activities and are potential candidates for therapeutic intervention in a number of neurologic disorders. To date, empirical attempts to control en masse NMDA receptor-mediated fluxes have had only modest success in the clinic, mainly due to inadequate understanding of the mechanisms governing the allosteric control of NMDA receptor activities and of the specific roles played by these activities in brain physiology and pathology. Over the previous funding period the objective has been to delineate the mechanisms by which endogenous modulators (protons, zinc/ifenprodil, glycine) affect NMDA receptor gating dynamics and thus control the macroscopic response relevant to synaptic signaling. Over the next funding period the objective is to delineate the intracellular protein motions that constitute the NMDA receptor activation. The general approach is to capitalize on the recently solved atomic-resolution structure for a GluA2 tetrameric receptor, a NMDA receptor homologue and our growing expertise on NMDA receptor gating modulation. We will introduce mutations to perturb (increase and decrease) the relative mobility of NMDA receptor structural modules and will delineate the accompanying changes in reaction mechanism by kinetic analyses of single-molecule signals. Further, we will explore the time course of macroscopic responses obtained from receptors with restricted or enhanced internal motions to better understand how specific structural features support the unique biological functions played by NMDA receptors in brain physiology and pathology. Overall this work will provide critical information about structural correlates of NMDA receptor activation and will integrate the currently isolated structural and kinetic models of gating. Given that glutamate receptors mediate more than 90% of excitatory transmission in brain and NMDA receptors are critical to many fundamental brain functions, knowledge generated by the proposed experiments is likely to have wide impact on the fields of neurotransmission and neuromodulation.
NMDA receptors mediate fundamental brain processes and are therapeutic target for a number of neuropathologies including stroke, chronic neurodegeneration, addiction and pain. Results from this application will provide needed information about structural correlates of NMDA receptor activation and by integrating structural and kinetic models of gating will assist in the rational design of pharmacologic approaches to address acute and chronic neuropathies.
|Cummings, Kirstie A; Popescu, Gabriela K (2016) Protons Potentiate GluN1/GluN3A Currents by Attenuating Their Desensitisation. Sci Rep 6:23344|
|Cummings, Kirstie A; Popescu, Gabriela K (2015) Glycine-dependent activation of NMDA receptors. J Gen Physiol 145:513-27|
|Popescu, Gabriela K (2015) Accessories assist AMPA receptors to close pockets. J Gen Physiol 145:17-21|
|Paganelli, Meaghan A; Popescu, Gabriela K (2015) Actions of bupivacaine, a widely used local anesthetic, on NMDA receptor responses. J Neurosci 35:831-42|
|Popescu, Gabriela K (2015) Zinc transporter found attached to N-methyl-D-aspartate receptors. J Neurochem 132:155-8|
|Borschel, William F; Cummings, Kirstie A; Tindell, LeeAnn K et al. (2015) Kinetic contributions to gating by interactions unique to N-methyl-D-aspartate (NMDA) receptors. J Biol Chem 290:26846-55|
|Popescu, Gabriela K (2014) Dynamic plasticity of NMDA receptor-mediated calcium entry in neurons exposed to HIV-tat. J Neurochem 130:609-11|
|Maki, Bruce A; Popescu, Gabriela K (2014) Extracellular Ca(2+) ions reduce NMDA receptor conductance and gating. J Gen Physiol 144:379-92|
|Murphy, Jessica A; Stein, Ivar S; Lau, C Geoffrey et al. (2014) Phosphorylation of Ser1166 on GluN2B by PKA is critical to synaptic NMDA receptor function and Ca2+ signaling in spines. J Neurosci 34:869-79|
|Maki, Bruce A; Cummings, Kirstie A; Paganelli, Meaghan A et al. (2014) One-channel cell-attached patch-clamp recording. J Vis Exp :|
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