title: Splice variant-specific interaction of the NMDA receptor subunit NR1 with neuronal intermediate filaments.
abstract: NMDA receptors are excitatory neurotransmitter receptors critical for synaptic plasticity and neuronal development in the mammalian brain. These receptors are found highly concentrated in the postsynaptic membrane of glutamatergic synapses. To investigate the molecular mechanisms underlying NMDA receptor localization, we used the yeast two-hybrid system to identify proteins expressed in the brain that interact with the NMDA receptor subunit NR1. Here we report that the 68 kDa neurofilament subunit NF-L directly interacts with the NR1 subunit. This interaction occurs between the cytoplasmic C-terminal domain of NR1 and the rod domain of NF-L. However, NR1 splice variants lacking the first C-terminal exon cassette (C1) failed to associate with NF-L. Immunogold electron microscopy revealed a preferential localization of NR1 at the ends of in vitro-assembled neurofilaments. Overexpression of C1 cassette-containing NR1 constructs in fibroblast cells disrupted the assembly of recombinant neurofilaments. In addition, NR1 and NF-L cofractionated in detergent-treated rat brain synaptic plasma membranes. Furthermore, NR1 and NF-L colocalize in the dendrites and growth cones of cultured hippocampal neurons. These results demonstrate the splice variant-specific association of NR1 with neurofilaments and suggest a possible mechanism for anchoring or localizing NMDA receptors in the neuronal plasma membrane.
authors.affiliation: Department of Neuroscience, Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Ehlers
authors.forename: E T
authors.initials: ET
authors.lastname: Fung
authors.forename: R J
authors.initials: RJ
authors.lastname: O'Brien
authors.forename: R L
authors.initials: RL
authors.lastname: Huganir
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism; D007382:Intermediate Filaments / Q000378:metabolism* / Q000648:ultrastructure; D016900:Neurofilament Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics*
chemical_list: D016900:Neurofilament Proteins; D016194:Receptors, N-Methyl-D-Aspartate; C044882:neurofilament protein L