Characterization of the role of microtubule-associated protein 1B in metabotropic glutamate receptor-mediated endocytosis of AMPA receptors in hippocampus.
The mGluR-dependent endocytosis of AMPA receptors (AMPARs) in the CA1 region is protein synthesis dependent. However, why this form of trafficking, and not that mediated by NMDA receptor activation, is dependent on protein translation is unclear. Here we have studied the contribution of the cytoskeletal microtubule-associated protein 1B (MAP1B) to the pathway-specific internalization of AMPARs. Treatments of cultured neurons with 3,4-dihydroxyphenylglycol (DHPG) or NMDA, both of which drive AMPAR endocytosis, caused a translation-dependent increase in the dendritic levels of MAP1B protein. Although interfering with protein synthesis using short interfering RNA (siRNA) to eEF2 kinase (eukaryotic elongation factor 2 kinase) blocked the dendritic MAP1B increase by both pathways, it selectively blocked the DHPG- and not the NMDA-induced AMPAR endocytosis. In support of MAP1B synthesis contributing to metabotropic glutamate receptor (mGluR)-mediated AMPAR endocytosis, siRNA against MAP1B in CA1 cultured neurons specifically blocked the DHPG-induced AMPAR internalization. Previous studies suggest a direct interaction between MAP1B and the AMPAR-binding protein GRIP1. Biochemical studies establish that MAP1B associates with GRIP1 and forms a complex with GluR2 in vivo in rat hippocampus. Furthermore, the interaction between MAP1B and GRIP1 increased significantly in acute slices after treatment with DHPG and not NMDA. Together, these findings suggest that MAP1B plays a selective role in the DHPG-induced endocytosis of AMPARs, perhaps through its interaction with GRIP1.
Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA. gdavidko@scripps.edu
Genoveva
G
Davidkova
Reed C
RC
Carroll
D000818:Animals; D000831:Animals, Newborn; D019921:Biotinylation / Q000379:methods; D002478:Cells, Cultured; D004347:Drug Interactions; D054736:Elongation Factor 2 Kinase / Q000235:genetics; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D047468:Immunoprecipitation / Q000379:methods; D066298:In Vitro Techniques; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives / Q000494:pharmacology; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000378:metabolism*; D018094:Receptors, Metabotropic Glutamate / Q000502:physiology*
D018690:Excitatory Amino Acid Agonists; D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; D018091:Receptors, AMPA; D018094:Receptors, Metabotropic Glutamate; C085284:microtubule-associated protein 1B; D008734:Methoxyhydroxyphenylglycol; D016202:N-Methylaspartate; C517689:EEF2K protein, human; D054736:Elongation Factor 2 Kinase; C010117:3,4-dihydroxyphenylglycol