title: Astrocytic activation of A1 receptors regulates the surface expression of NMDA receptors through a Src kinase dependent pathway.
abstract: Chemical transmitters released from astrocytes, termed gliotransmitters, modulate synaptic transmission and neuronal function. Using astrocyte-specific inducible transgenicmice (dnSNARE mice), we have demonstrated that inhibiting gliotransmission leads to reduced activation of adenosine A1 receptors (A1R) and impaired sleep homeostasis (Halassa et al. (2009) Neuron 61:213-219); Pascual et al. (2005) Science 310:113-116). Additionally, synaptic N-methyl-D-aspartate receptor (NMDAR) currents are reduced in these astrocyte-specific transgenic animals (Fellin et al. (2009) Proc Natl Acad Sci USA 106:15037-15042). Because of the importance of adenosine and NMDA receptors to sleep processes we asked whether there is a causal linkage between changes in A1R activation and synaptic NMDA receptors. We show that astrocytic dnSNARE expression leads to reduced tyrosine phosphorylation of Srckinase and NR2 subunits concomitant with the decreased surface expression of the NR2 subunits. To test the role of A1R signaling in mediating these actions, we show that incubation of wildtype (WT) slices with an A1R antagonist reduces tyrosine phosphorylation of Src kinase and NR2B, decreases the surface expression of the NR2B subunits and leads to smaller NMDA component of miniature EPSCs. In dnSNARE mice we could rescue WT phenotype by incubation in an A1R agonist:activation of A1 receptor led to increased tyrosine phosphorylation of Src kinase and NR2B subunits as well as increased the surface expression of the NR2B subunit and increased NMDA component of the synaptic mEPSC. These results provide the first demonstration that astrocytes can affect neuronal excitability on a long time scale by regulating the surface expression of NMDA receptors through the activation of specific intracellular signaling pathways.
authors.affiliation: Department of Neuroscience, Tufts University, Boston, Massachusetts 02111, USA.
authors.forename: Qiudong
authors.initials: Q
authors.lastname: Deng
authors.forename: Miho
authors.initials: M
authors.lastname: Terunuma
authors.forename: Tommaso
authors.initials: T
authors.lastname: Fellin
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Moss
authors.forename: Philip G
authors.initials: PG
authors.lastname: Haydon
mesh_terms: D058916:Adenosine A1 Receptor Antagonists / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D019921:Biotinylation / Q000379:methods; D004791:Enzyme Inhibitors / Q000494:pharmacology; 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; D047468:Immunoprecipitation / Q000379:methods; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques / Q000379:methods; D010766:Phosphorylation / Q000187:drug effects; D043682:Receptor, Adenosine A1 / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D050600:SNARE Proteins / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D013003:Somatosensory Cortex / Q000166:cytology; D014443:Tyrosine / Q000378:metabolism; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D058916:Adenosine A1 Receptor Antagonists; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; C121001:NR2B NMDA receptor; D043682:Receptor, Adenosine A1; D016194:Receptors, N-Methyl-D-Aspartate; D050600:SNARE Proteins; D014443:Tyrosine; D016202:N-Methylaspartate; C056639:2-amino-5-phosphopentanoic acid; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D019061:src-Family Kinases; D014633:Valine