title: The NG2 Protein Is Not Required for Glutamatergic Neuron-NG2 Cell Synaptic Signaling.
abstract: NG2 glial cells (as from now NG2 cells) are unique in receiving synaptic input from neurons. However, the components regulating formation and maintenance of these neuron-glia synapses remain elusive. The transmembrane protein NG2 has been considered a potential mediator of synapse formation and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) clustering, because it contains 2 extracellular Laminin G/Neurexin/Sex Hormone-Binding Globulin domains, which in neurons are crucial for formation of transsynaptic neuroligin-neurexin complexes. NG2 is connected via Glutamate Receptor-Interacting Protein with GluA2/3-containing AMPARs, thereby possibly mediating receptor clustering in glial postsynaptic density. To elucidate the role of NG2 in neuron-glia communication, we investigated glutamatergic synaptic transmission in juvenile and aged hippocampal NG2 cells of heterozygous and homozygous NG2 knockout mice. Neuron-NG2 cell synapses readily formed in the absence of NG2. Short-term plasticity, synaptic connectivity, postsynaptic AMPAR current kinetics, and density were not affected by NG2 deletion. During development, an NG2-independent acceleration of AMPAR current kinetics and decreased synaptic connectivity were observed. Our results indicate that the lack of NG2 does not interfere with genesis and basic properties of neuron-glia synapses. In addition, we demonstrate frequent expression of neuroligins 1-3 in juvenile and aged NG2 cells, suggesting a role of these molecules in synapse formation between NG2 glia and neurons.
authors.affiliation: Institute of Cellular Neurosciences, University of Bonn, Bonn 53105, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Passlick
authors.affiliation: Molecular Cell Biology, University of Mainz, Mainz 55099, Germany.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Trotter
authors.affiliation: Institute of Cellular Neurosciences, University of Bonn, Bonn 53105, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Seifert
authors.affiliation: Institute of Cellular Neurosciences, University of Bonn, Bonn 53105, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Steinhäuser
authors.affiliation: Institute of Cellular Neurosciences, University of Bonn, Bonn 53105, Germany.
authors.forename: Ronald
authors.initials: R
authors.lastname: Jabs
mesh_terms: D000818:Animals; D000941:Antigens / Q000235:genetics*; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008822:Mice, Transgenic; D009457:Neuroglia / Q000166:cytology*; D009474:Neurons / Q000166:cytology*; D011509:Proteoglycans / Q000235:genetics*; D018091:Receptors, AMPA / Q000378:metabolism; D013569:Synapses / Q000378:metabolism*; D009435:Synaptic Transmission / Q000235:genetics*; D000099216:Chondroitin Sulfate Proteoglycan 4
chemical_list: D000941:Antigens; D018698:Glutamic Acid; D008565:Membrane Proteins; D011509:Proteoglycans; D018091:Receptors, AMPA; D000099216:Chondroitin Sulfate Proteoglycan 4
keywords: AMPA receptor; NG2; NG2 knockout; neuroligin; neuron–glia synapse