title: Ephrin-B3 regulates glutamate receptor signaling at hippocampal synapses.
abstract: B-ephrin-EphB receptor signaling modulates NMDA receptors by inducing tyrosine phosphorylation of NR2 subunits. Ephrins and EphB RTKs are localized to postsynaptic compartments in the CA1, and therefore potentially interact in a non-canonical cis- configuration. However, it is not known whether cis- configured receptor-ligand signaling is utilized by this class of RTKs, and whether this might influence excitatory synapses. We found that ablation of ephrin-B3 results in an enhancement of the NMDA receptor component of synaptic transmission relative to the AMPA receptor component in CA1 synapses. Synaptic AMPA receptor expression is reduced in ephrin-B3 knockout mice, and there is a marked enhancement of tyrosine phosphorylation of the NR2B receptor subunit. In a reduced system co-expression of ephrin-B3 attenuated EphB2-mediated NR2B tyrosine phosphorylation. Moreover, phosphorylation of EphB2 was elevated in the hippocampus of ephrin-B3 knockout mice, suggesting that regulation of EphB2 activity is lost in these mice. Direct activation of EphB RTKs resulted in phosphorylation of NR2B and a potential signaling partner, the non-receptor tyrosine kinase Pyk2. Our data suggests that ephrin-B3 limits EphB RTK-mediated phosphorylation of the NR2B subunit through an inhibitory cis- interaction which is required for the correct function of glutamatergic CA1 synapses.
authors.affiliation: Department of Physiology, Northwestern University Feinberg School of Medicine, 303 E Chicago Ave, Chicago, Il 60611, USA.
authors.forename: Marcia D
authors.initials: MD
authors.lastname: Antion
authors.forename: Louisa A
authors.initials: LA
authors.lastname: Christie
authors.forename: Allison M
authors.initials: AM
authors.lastname: Bond
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Dalva
authors.forename: Anis
authors.initials: A
authors.lastname: Contractor
mesh_terms: D000818:Animals; D036389:Ephrin-B3 / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials; D057809:HEK293 Cells; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D051379:Mice; D018345:Mice, Knockout; D018408:Patch-Clamp Techniques; D018091:Receptors, AMPA / Q000378:metabolism; D036081:Receptors, Eph Family / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013569:Synapses / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology; D014162:Transfection
chemical_list: D036389:Ephrin-B3; C121001:NR2B NMDA receptor; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D036081:Receptors, Eph Family