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Novel approach to probe subunit-specific contributions to N-methyl-D-aspartate (NMDA) receptor trafficking reveals a dominant role for NR2B in receptor recycling.

ABSTRACT: N-Methyl-d-aspartate (NMDA) receptors are expressed at excitatory synapses throughout the brain and are essential for neuronal development and synaptic plasticity. Functional NMDA receptors are tetramers, typically composed of NR1 and NR2 subunits (NR2A-D). NR2A and NR2B are expressed in the forebrain and are thought to assemble as diheteromers (NR1/NR2A, NR1/NR2B) and triheteromers (NR1/NR2A/NR2B). NR2A and NR2B contain cytosolic domains that regulate distinct postendocytic sorting events, with NR2A sorting predominantly into the degradation pathway, and NR2B preferentially trafficking through the recycling pathway. However, the interplay between these two subunits remains an open question. We have now developed a novel approach based on the dimeric feature of the alpha- and beta-chains of the human major histocompatibility complex class II molecule. We created chimeras of alpha- and beta-chains with the NR2A and NR2B C termini and evaluated endocytosis of dimers. Like chimeric proteins containing only a single NR2A or NR2B C-terminal domain, major histocompatibility complex class II-NR2A homodimers sort predominantly to late endosomes, whereas NR2B homodimers traffic to recycling endosomes. Interestingly, NR2A/NR2B heterodimers traffic preferentially through the recycling pathway, and NR2B is dominant in regulating dimer trafficking in both heterologous cells and neurons. In addition, the recycling of NR2B-containing NMDARs in wild-type neurons is not significantly different from NR2A(-/-) neurons. These data support a dominant role for NR2B in regulating the trafficking of triheteromeric NMDARs in vivo. Furthermore, our molecular approach allows for the direct and selective evaluation of dimeric assemblies and can be used to define dominant trafficking domains in other multisubunit protein complexes.

SUBMITTER: Tang TT

PROVIDER: S-EPMC2898322 | biostudies-literature | 2010 Jul

REPOSITORIES: biostudies-literature

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Novel approach to probe subunit-specific contributions to N-methyl-D-aspartate (NMDA) receptor trafficking reveals a dominant role for NR2B in receptor recycling.

Tang Tina Tze-Tsang TT Badger John D JD Roche Paul A PA Roche Katherine W KW

The Journal of biological chemistry 20100428 27

N-Methyl-d-aspartate (NMDA) receptors are expressed at excitatory synapses throughout the brain and are essential for neuronal development and synaptic plasticity. Functional NMDA receptors are tetramers, typically composed of NR1 and NR2 subunits (NR2A-D). NR2A and NR2B are expressed in the forebrain and are thought to assemble as diheteromers (NR1/NR2A, NR1/NR2B) and triheteromers (NR1/NR2A/NR2B). NR2A and NR2B contain cytosolic domains that regulate distinct postendocytic sorting events, with ...[more]

PMID: 20427279

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Project description:BackgroundPostherpetic neuralgia is spontaneous pain and allodynia that persist long after the disappearance of the cutaneous lesions caused by herpes zoster. Inoculation of mice with herpes simplex virus-1 causes herpes zoster-like skin lesions and herpetic and postherpetic pain. Although NMDA receptors have been suggested to be involved in postherpetic pain as in other types of neuropathic pain, the neural mechanism remains unclear. NMDA receptor NR2B subunit is the most tyrosine-phosphorylated protein in the brain, and Tyr1472 is the major phosphorylation site of this subunit.ResultsTo elucidate the role of Tyr1472 phosphorylation of the NR2B subunit in herpetic and postherpetic allodynia, we inoculated herpes simplex virus-1 into the unilateral hind paw of knock-in mice with a mutation of Tyr1472 of the NR2B subunit to Phe (Y1472F-KI). On day 7 post-inoculation, acute herpetic allodynia was observed in more than 80% of the inoculated wild-type and Y1472F-KI mice. Y1472F-KI mice showed significantly reduced intensity and incidence of postherpetic allodynia on days 45-50 post-inoculation as compared with wild-type mice. The innervation in the skin at the postherpetic neuralgia phase was retained to a greater extent in the Y1472F-KI mice. The level of activating transcription factor-3 mRNA, a marker of axonal damage, increased much less in the dorsal root ganglia (DRGs) of Y1472F-KI mice than in those of wild-type mice; and the level of nerve growth factor mRNA significantly increased in wild-type mice, but not at all in Y1472F-KI mice on day 7 post-inoculation. Production of nerve growth factor was at the basal level in the skin of both groups of mice on day 50 post-inoculation. Nerve growth factor and glial cell-derived neurotrophic factor stimulated neurite outgrowth of cultured DRG neurons from Y1472F-KI mice, similarly or less so as they did the outgrowth of those from wild-type mice. Wild-type DRG neurons were more susceptible to glutamate neurotoxicity than Y1472F-KI ones.ConclusionsTaken together, the present data suggest that phosphorylation of the NR2B subunit at its Tyr1472 is involved in the development of postherpetic allodynia due to nerve damage and that the nerve damage at the acute herpetic phase is correlated with the incidence of postherpetic pain.

Dataset Information

Novel approach to probe subunit-specific contributions to N-methyl-D-aspartate (NMDA) receptor trafficking reveals a dominant role for NR2B in receptor recycling.

Publications

Novel approach to probe subunit-specific contributions to N-methyl-D-aspartate (NMDA) receptor trafficking reveals a dominant role for NR2B in receptor recycling.

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