title: Neto1 is an auxiliary subunit of native synaptic kainate receptors.
abstract: Ionotropic glutamate receptors of AMPA, NMDA, and kainate receptor (KAR) subtypes mediate fast excitatory synaptic transmission in the vertebrate CNS. Auxiliary proteins have been identified for AMPA and NMDA receptor complexes, but little is known about KAR complex proteins. We previously identified the CUB (complement C1r/C1s, Uegf, Bmpl) domain protein, Neto1, as an NMDA receptor-associated polypeptide. Here, we show that Neto1 is also an auxiliary subunit for endogenous synaptic KARs. We found that Neto1 and KARs coimmunoprecipitated from brain lysates, from postsynaptic densities (PSDs) and, in a manner dependent on Neto1 CUB domains, when coexpressed in heterologous cells. In Neto1-null mice, there was an ∼50% reduction in the abundance of GluK2-KARs in hippocampal PSDs. Neto1 strongly localized to CA3 stratum lucidum, and loss of Neto1 resulted in a selective deficit in KAR-mediated neurotransmission at mossy fiber-CA3 pyramidal cell (MF-CA3) synapses: KAR-mediated EPSCs in Neto1-null mice were reduced in amplitude and decayed more rapidly than did those in wild-type mice. In contrast, the loss of Neto2, which also localizes to stratum lucidum and interacts with KARs, had no effect on KAR synaptic abundance or MF-CA3 transmission. Indeed, MF-CA3 KAR deficits in Neto1/Neto2-double-null mutant mice were indistinguishable from Neto1 single-null mice. Thus, our findings establish Neto1 as an auxiliary protein required for synaptic function of KARs. The ability of Neto1 to regulate both NMDARs and KARs reveals a unique dual role in controlling synaptic transmission by serving as an auxiliary protein for these two classes of ionotropic glutamate receptors in a synapse-specific fashion.
authors: Program in Developmental and Stem Cell Biology, The Research Institute, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.
authors: Man
authors: M
authors: Tang
authors: Kenneth A
authors: KA
authors: Pelkey
authors: David
authors: D
authors: Ng
authors: Evgueni
authors: E
authors: Ivakine
authors: Chris J
authors: CJ
authors: McBain
authors: Michael W
authors: MW
authors: Salter
authors: Roderick R
authors: RR
authors: McInnes
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000378:metabolism; D015815:Cell Adhesion Molecules; D002461:Cell Line, Transformed; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D006624:Hippocampus / Q000166:cytology; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D066298:In Vitro Techniques; D026502:LDL-Receptor Related Proteins; D008077:Lipoproteins, LDL / Q000172:deficiency / Q000378:metabolism*; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000172:deficiency / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques / Q000379:methods; D057907:Post-Synaptic Density / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate; D013574:Synaptosomes / Q000378:metabolism*; D014162:Transfection / Q000379:methods
chemical_list: D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D026502:LDL-Receptor Related Proteins; D008077:Lipoproteins, LDL; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; C529673:CDCP1 protein, mouse; C539204:NETO2 protein, mouse; C486748:Neto1 protein, mouse