title: Glutamate receptor-mediated phosphorylation of ezrin/radixin/moesin proteins is implicated in filopodial protrusion of primary cultured hippocampal neuronal cells.
abstract: Previously, we reported the phosphorylation of moesin induced by electroconvulsive shock in rat brain and by glutamate in immortalized rat hippocampal cells. However, the function of phosphorylated moesin in differentiated neurons is not well understood. In this study, we observed that glutamate induces phosphorylation of ezrin/radixin/moesin proteins (ERM) in cultured hippocampal cells and that phosphorylated ERM localizes at the newly formed filopodia of neurites. The glutamate-induced phosphorylation of ERM is calcium-dependent, and inhibition of protein kinase C abolishes ERM phosphorylation as well as RhoA activation. The inhibitions of RhoA and RhoA kinase also diminishes the glutamate-induced ERM phosphorylation in cultured hippocampal cells. The knock-down of moesin or the inhibition of ERM phosphorylation results in the reduction of glutamate-induced filopodia protrusion and diminishes the increase in active synaptic boutons induced by glutamate treatment. These results indicate that glutamate-induced phosphorylation of ERM proteins in primary cultured differentiated hippocampal neurons is mediated by calcium-dependent protein kinase C, RhoA and RhoA kinase, and the phosphorylated ERM protein is necessary for the formation of filopodial protrusion and may be involved in pre-synaptic trafficking.
authors.affiliation: Department of Molecular Cell Biology and Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Korea.
authors.forename: Han-Seop
authors.initials: HS
authors.lastname: Kim
authors.forename: Chang-Dae
authors.initials: CD
authors.lastname: Bae
authors.forename: Joobae
authors.initials: J
authors.lastname: Park
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D000076122:Disks Large Homolog 4 Protein; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics; D006624:Hippocampus / Q000166:cytology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009474:Neurons / Q000648:ultrastructure*; D010766:Phosphorylation / Q000187:drug effects; D011554:Pseudopodia / Q000187:drug effects / Q000502:physiology*; D011726:Pyridinium Compounds / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017470:Receptors, Glutamate / Q000502:physiology*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014162:Transfection / Q000379:methods; D020742:rhoA GTP-Binding Protein / Q000378:metabolism; D000099149:Ezrin
chemical_list: D002614:Chelating Agents; D003598:Cytoskeletal Proteins; D000076122:Disks Large Homolog 4 Protein; D004533:Egtazic Acid; D004791:Enzyme Inhibitors; D018683:Excitatory Amino Acid Agents; D018698:Glutamic Acid; D049452:Green Fluorescent Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D034741:RNA, Small Interfering; D017470:Receptors, Glutamate; D020742:rhoA GTP-Binding Protein; D000099149:Ezrin; C501449:Dlg4 protein, rat; C092350:FM 4-64; C489787:MAP2 protein, rat; C485184:enhanced green fluorescent protein; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; C071058:moesin; C071776:radixin