title: Presynaptic NMDA receptors - dynamics and distribution in developing axons in vitro and in vivo.
abstract: During cortical development, N-methyl-D-aspartate (NMDA) receptors (NMDARs) facilitate presynaptic terminal formation, enhance neurotransmitter release and are required in presynaptic neurons for spike-timing-dependent long-term depression (tLTD). However, the extent to which NMDARs are found within cortical presynaptic terminals has remained controversial, and the sub-synaptic localization and dynamics of axonal NMDARs are unknown. Here, using live confocal imaging and biochemical purification of presynaptic membranes, we provide strong evidence that NMDARs localize to presynaptic terminals in vitro and in vivo in a developmentally regulated manner. The NR1 and NR2B subunits (also known as GRIN1 and GRIN2B, respectively) were found within the active zone membrane, where they could respond to synaptic glutamate release. Surprisingly, NR1 also appeared in glutamatergic and GABAergic synaptic vesicles. During synaptogenesis, NR1 was mobile throughout axons - including growth cones and filopodia, structures that are involved in synaptogenesis. Upon synaptogenic contact, NMDA receptors were quickly recruited to terminals by neuroligin-1 signaling. Unlike dendrites, the trafficking and distribution of axonal NR1 were insensitive to activity changes, including NMDA exposure, local glutamate uncaging or action potential blockade. These results support the idea that presynaptic NMDARs play an early role in presynaptic development.
authors.affiliation: Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
authors.forename: Ishwar
authors.initials: I
authors.lastname: Gill
authors.affiliation: Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
authors.forename: Sammy
authors.initials: S
authors.lastname: Droubi
authors.affiliation: Department of Experimental Medicine, University of Genoa, 16132 Genoa, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Giovedi
authors.affiliation: Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
authors.forename: Karlie N
authors.initials: KN
authors.lastname: Fedder
authors.affiliation: Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
authors.forename: Luke A D
authors.initials: LA
authors.lastname: Bury
authors.affiliation: Department of Experimental Medicine, University of Genoa, 16132 Genoa, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Bosco
authors.affiliation: Department of Neuroscience, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Sceniak
authors.affiliation: Department of Experimental Medicine, University of Genoa, 16132 Genoa, Italy Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, 16163 Genoa, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Benfenati
authors.affiliation: Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA Department of Neuroscience, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA shasta.sabo@case.edu.
authors.forename: Shasta L
authors.initials: SL
authors.lastname: Sabo
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D002478:Cells, Cultured; D003712:Dendrites / Q000378:metabolism; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D057809:HEK293 Cells; D006801:Humans; D007091:Image Processing, Computer-Assisted; D018613:Microscopy, Confocal; D018377:Neurotransmitter Agents / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D017661:Receptors, Presynaptic / Q000378:metabolism; D015398:Signal Transduction; D009435:Synaptic Transmission / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism*; D014793:Visual Cortex / Q000196:embryology*
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; C409466:NR1 NMDA receptor; C121001:NR2B NMDA receptor; D018377:Neurotransmitter Agents; D016194:Receptors, N-Methyl-D-Aspartate; D017661:Receptors, Presynaptic; C093438:neuroligin 1
keywords: NMDA receptor; Presynaptic; Receptor trafficking; Synapse development; Synaptosome