title: N-methyl-D-aspartate receptor subunit- and neuronal-type dependence of excitotoxic signaling through post-synaptic density 95.
abstract: NMDA receptors (NMDARs) mediate excitatory synaptic transmission during repetitive or prolonged glutamate release, playing a critical role in synaptic plasticity or cell death, respectively. Evidence indicates that a major pathway of NMDAR signaling to cell death in cortical and hippocampal neurons requires the scaffolding protein post-synaptic density 95 (PSD-95) and activation of neuronal nitric oxide synthase. However, it is not known if this PSD-95-dependent pathway contributes to excitotoxicity in other brain regions. It is also unclear whether the neuroprotective effects of Tat-NR2B9c, a membrane-permeant peptide that disrupts PSD-95/NMDAR binding, correlate with uncoupling NR2B- and/or NR2A-type NMDARs from PSD-95. In this study, we used cultured hippocampal and striatal neurons to test the potency of Tat-NR2B9c on uncoupling NR2 subunits from PSD-95 and protecting against NMDA-induced excitotoxicity. We found that the concentration of Tat-NR2B9c required to dissociate 50% of PSD-95 was fourfold lower for NR2B than NR2A in cultured hippocampal and striatal neurons, and that this concentration correlated tightly with protection against NMDA-induced toxicity in hippocampal neurons without altering NMDAR current. In contrast, NMDAR signaling to cell death in cultured striatal neurons occurred independently of the NR2B/PSD-95 interaction or neuronal nitric oxide synthase activation. These results will facilitate development of neuronal type-specific protective therapies.
authors.affiliation: Graduate Program in Neuroscience, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Jing
authors.initials: J
authors.lastname: Fan
authors.forename: Oana Cristina
authors.initials: OC
authors.lastname: Vasuta
authors.forename: Lily Y J
authors.initials: LY
authors.lastname: Zhang
authors.forename: Liang
authors.initials: L
authors.lastname: Wang
authors.forename: Ashley
authors.initials: A
authors.lastname: George
authors.forename: Lynn A
authors.initials: LA
authors.lastname: Raymond
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016923:Cell Death / Q000502:physiology; D002478:Cells, Cultured; D018920:Coculture Techniques; D000076122:Disks Large Homolog 4 Protein; D051528:Guanylate Kinases; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism / Q000502:physiology* / Q000633:toxicity; D008565:Membrane Proteins / Q000378:metabolism / Q000502:physiology* / Q000633:toxicity; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism / Q000502:physiology; D010455:Peptides / Q000633:toxicity; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D021122:Protein Subunits / Q000378:metabolism / Q000502:physiology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C120997:NR2A NMDA receptor; C121001:NR2B NMDA receptor; D010455:Peptides; D021122:Protein Subunits; D016194:Receptors, N-Methyl-D-Aspartate; C542597:Tat-NR2B9c; D052248:Nitric Oxide Synthase Type I; D051528:Guanylate Kinases