NMDA receptors (NRs) mediate fast excitatory transmission in the brain. Their activation is critical for the normal development, maintenance and continual remodeling of excitatory synapses. Excessive NR activity is a disease mechanism in stroke, chronic pain, epilepsy, and neurodegenerative disease, whereas insufficient NR signaling has been involved with schizophrenia and cognitive disorders. Numerous endogenous and pharmacologic agents modulate NR activities and are potential candidates for therapeutic intervention. The mechanisms governing the allosteric control of NR activity are poorly understood and empirical attempts to control NR function have so far yielded disappointing results. The OBJECTIVE is to understand how allosteric modulators control NR physiologic functions in terms of molecular mechanisms, integration and consequences on synaptic physiology.
The AIMS addressed in this proposal are to: i) characterize individual NR allosteric modulators in terms of their effects on NR gating dynamics and on non-stationary macroscopic behaviors;ii) establish how multiple allosteric signals are integrated to result in responses with distinct signaling profiles;and iii) investigate how allosteric modulation of NR responses impacts on synaptic physiology. First, using kinetic analysis of single-channel currents and statistical modeling we will identify and quantify the actions of individual modulators on NR elementary kinetic transitions during gating. These measured rate constants are intrinsically rich with mechanistic information;in addition they can predict modulator effects on NR macroscopic behaviors and on NR- mediated synaptic function. These predictions will be verified by measuring ensemble NR responses to patterned stimulation in excised membrane patches and by measuring evoked NR synaptic responses in brain slices. For NRs whose activation reaction is complex, this approach is entirely novel and may identify effective means to modulate specific receptor functions in separation of each other. Taken together the results will help to compile an integrated mechanistic view of how allosteric control of NR activity impacts synaptic physiology. This view should suggest new, combinatorial approaches to specifically target harmful receptor behaviors while preserving the critical functions played by NRs .

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS052669-04
Application #
7586622
Study Section
Biophysics of Synapses, Channels, and Transporters Study Section (BSCT)
Program Officer
Silberberg, Shai D
Project Start
2006-07-01
Project End
2011-03-31
Budget Start
2009-04-01
Budget End
2010-03-31
Support Year
4
Fiscal Year
2009
Total Cost
$331,327
Indirect Cost
Name
State University of New York at Buffalo
Department
Physiology
Type
Schools of Medicine
DUNS #
038633251
City
Buffalo
State
NY
Country
United States
Zip Code
14260
Iacobucci, Gary J; Popescu, Gabriela K (2018) Kinetic models for activation and modulation of NMDA receptor subtypes. Curr Opin Physiol 2:114-122
Iacobucci, Gary J; Popescu, Gabriela K (2017) Resident Calmodulin Primes NMDA Receptors for Ca2+-Dependent Inactivation. Biophys J 113:2236-2248
Iacobucci, Gary J; Popescu, Gabriela K (2017) NMDA receptors: linking physiological output to biophysical operation. Nat Rev Neurosci 18:236-249
Cummings, Kirstie A; Belin, Sophie; Popescu, Gabriela K (2017) Residues in the GluN1 C-terminal domain control kinetics and pharmacology of GluN1/GluN3A N-methyl-d-aspartate receptors. Neuropharmacology 119:40-47
Cummings, Kirstie A; Popescu, Gabriela K (2016) Protons Potentiate GluN1/GluN3A Currents by Attenuating Their Desensitisation. Sci Rep 6:23344
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
Cummings, Kirstie A; Popescu, Gabriela K (2015) Glycine-dependent activation of NMDA receptors. J Gen Physiol 145:513-27
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
Popescu, Gabriela K (2015) Accessories assist AMPA receptors to close pockets. J Gen Physiol 145:17-21

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