The N-terminal domain of GluD2 (GluRdelta2) recruits presynaptic terminals and regulates synaptogenesis in the cerebellum in vivo.
The delta2 glutamate receptor (GluRdelta2; GluD2), which is predominantly expressed on postsynaptic sites at parallel fiber (PF)-Purkinje cell synapses in the cerebellum, plays two crucial roles in the cerebellum: the formation of PF synapses and the regulation of long-term depression (LTD), a form of synaptic plasticity underlying motor learning. Although the induction of LTD and motor learning absolutely require signaling via the cytoplasmic C-terminal domain of GluD2, the mechanisms by which GluD2 regulates PF synaptogenesis have remained unclear. Here, we examined the role of the extracellular N-terminal domain (NTD) of GluD2 on PF synaptogenesis by injecting Sindbis virus carrying wild-type (GluD2(wt)) or mutant GluD2 into the subarachnoid supracerebellar space of GluD2-null mice. Remarkably, the expression of GluD2(wt), but not of a mutant GluD2 lacking the NTD (GluD2(DeltaNTD)), rapidly induced PF synapse formation and rescued gross motor dyscoordination in adult GluD2-null mice just 1 d after injection. In addition, although the kainate receptor GluR6 (GluK2) did not induce PF synaptogenesis, a chimeric GluK2 that contained the NTD of GluD2 (GluD2(NTD)-GluK2) did. Similarly, GluD2(wt) and GluD2(NTD)-GluK2, but not GluD2(DeltaNTD), induced synaptogenesis in heterologous cells in vitro. In contrast, LTD was restored in GluD2-null Purkinje cells expressing a mutant GluD2 lacking the NTD. These results indicate that the NTD of GluD2 is necessary and sufficient for the function of GluD2 in the regulation of PF-Purkinje cell synaptogenesis. Furthermore, our results suggest that GluD2 differently regulates PF synaptogenesis and cerebellar LTD through the extracellular NTD and the cytoplasmic C-terminal end, respectively.
Kakegawa
Wataru
W
Department of Physiology, Keio University School of Medicine, Tokyo 160-8582, Japan.
Miyazaki
Taisuke
T
Kohda
Kazuhisa
K
Matsuda
Keiko
K
Emi
Kyoichi
K
Motohashi
Junko
J
Watanabe
Masahiko
M
Yuzaki
Michisuke
M
D000595:Amino Acid Sequence / Q000235:genetics; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D002461:Cell Line, Transformed; D002531:Cerebellum / Q000166:cytology* / Q000502:physiology; D004195:Disease Models, Animal; D004558:Electric Stimulation / Q000379:methods; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000235:genetics; D015870:Gene Expression / Q000235:genetics; D018014:Gene Transfer Techniques; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D036881:Long-Term Synaptic Depression / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D009043:Motor Activity / Q000235:genetics; D019957:Motor Skills Disorders / Q000235:genetics / Q000628:therapy; D009154:Mutation / Q000235:genetics; D009412:Nerve Fibers / Q000502:physiology; D009473:Neuronal Plasticity; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000502:physiology* / Q000648:ultrastructure; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology*; D021381:Protein Transport / Q000235:genetics; D011689:Purkinje Cells / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D017470:Receptors, Glutamate / Q000737:chemistry* / Q000172:deficiency / Q000235:genetics; D011999:Recruitment, Neurophysiological; D012845:Sindbis Virus / Q000502:physiology; D013569:Synapses / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D014162:Transfection / Q000379:methods; D050598:Vesicular Glutamate Transport Protein 1 / Q000378:metabolism
D017470:Receptors, Glutamate; C493465:Slc17a7 protein, mouse; D050598:Vesicular Glutamate Transport Protein 1; C107913:glutamate receptor delta 2; D049452:Green Fluorescent Proteins