Dendritic and axonal targeting of type 5 metabotropic glutamate receptor is regulated by homer1 proteins and neuronal excitation.
The physiological actions of neurotransmitter receptors are intimately linked to their proper neuronal compartment localization. Here we studied the effect of the metabotropic glutamate receptor (mGluR)-interacting proteins, Homer1a, b, and c, in the targeting of mGluR5 in neurons. We found that mGluR5 was exclusively localized in cell bodies when transfected alone in cultured cerebellar granule cells. In contrast, mGluR5 was found also in dendrites when coexpressed with Homer1b or Homer1c, and in both dendrites and axons when cotransfected with Homer1a. In dendrites, cotransfected mGluR5 and Homer1b/c formed clusters that colocalized with the synaptic marker synaptophysin. Interestingly when transfected alone, the Homer proteins were also translocated to neurites but did not form such clusters. Depolarization of the neurons with a mixture of ionotropic glutamate receptor agonists, NMDA and kainate, or potassium channel blockers, tetraethylammonium and 4-aminopyridine, induced transient expression of endogenous Homer1a and persistent neuritic localization of transfected mGluR5 even long after degradation of Homer1a. These results suggest that Homer1a/b/c proteins are involved in the targeting of mGluR5 to dendritic synaptic sites and/or axons and that this effect can be regulated by neuronal activity. Because the activity-dependent effect of endogenous Homer1a was also long-lasting, the axonal targeting of mGluR5 by this protein is likely to play an important role in synaptic plasticity.
Ango
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Centre National de la Recherche Scientifique UPR9023, Mécanisme Moléculaires des Communications cellulaires, 34094 Montpellier Cedex 5, France. fagni@ccipe.montp.inserm.r
Pin
J P
JP
Tu
J C
JC
Xiao
B
B
Worley
P F
PF
Bockaert
J
J
Fagni
L
L
D000818:Animals; D001369:Axons / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism; D003342:Corpus Striatum / Q000166:cytology / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D000072233:Homer Scaffolding Proteins; D006801:Humans; D007608:Kainic Acid / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D016202:N-Methylaspartate / Q000378:metabolism / Q000494:pharmacology; D016501:Neurites / Q000378:metabolism; D009473:Neuronal Plasticity / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D026902:Potassium Channel Blockers; D011485:Protein Binding / Q000235:genetics; D020033:Protein Isoforms / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016708:Synaptophysin / Q000378:metabolism; D014162:Transfection
D002352:Carrier Proteins; D018690:Excitatory Amino Acid Agonists; C578935:GRM5 protein, human; C578936:Grm5 protein, mouse; C000606614:HOMER1 protein, human; D000072233:Homer Scaffolding Proteins; C000606623:Homer1 protein, mouse; D009479:Neuropeptides; D026902:Potassium Channel Blockers; D020033:Protein Isoforms; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D011994:Recombinant Proteins; D016708:Synaptophysin; D016202:N-Methylaspartate; D007608:Kainic Acid