title: Reduced cortical synaptic plasticity and GluR1 expression associated with fragile X mental retardation protein deficiency.
abstract: Lack of expression of the fragile X mental retardation protein (FMRP), due to silencing of the FMR1 gene, causes the Fragile X syndrome. Although FMRP was characterized previously to be an RNA binding protein, little is known about its function or the mechanisms underlying the Fragile X syndrome. Here we report that the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor subunit, GluR1, was decreased in the cortical synapses, but not in the hippocampus or cerebellum, of FMR1 gene knockout mice. Reduced long-term potentiation (LTP) was also found in the cortex but not in the hippocampus. Another RNA binding protein, FXR; the N-methyl-D-aspartate receptor subunit, NR2; and other learning-related proteins including c-fos, synapsin, myelin proteolipid protein, and cAMP response element binding protein were not different between FMR1 gene knockout and wild-type mice. These findings suggest that the depressed cortical GluR1 expression and LTP associated with FMRP deficiency could contribute to the Fragile X phenotype.
authors.affiliation: Division of Cellular and Molecular Biology, Toronto Western Research Institute, University of Toronto, Toronto, Ontario M5T 2S8, Canada.
authors.forename: Jianxue
authors.initials: J
authors.lastname: Li
authors.forename: Marc R
authors.initials: MR
authors.lastname: Pelletier
authors.forename: Jose-Luis
authors.initials: JL
authors.lastname: Perez Velazquez
authors.forename: Peter L
authors.initials: PL
authors.lastname: Carlen
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000235:genetics; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005786:Gene Expression Regulation / Q000235:genetics; D007859:Learning Disabilities / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D008099:Liver / Q000378:metabolism; D017774:Long-Term Potentiation / Q000187:drug effects / Q000235:genetics*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018991:Myelin Proteolipid Protein / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000172:deficiency* / Q000235:genetics; D016601:RNA-Binding Proteins / Q000378:metabolism; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000378:metabolism*; D016704:Synapsins / Q000378:metabolism; D013570:Synaptic Membranes / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000235:genetics*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D018691:Excitatory Amino Acid Antagonists; D051860:Fragile X Messenger Ribonucleoprotein 1; D018991:Myelin Proteolipid Protein; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D016704:Synapsins; D013779:Tetrodotoxin; C096916:FXR1 protein, human; C497684:Fmr1 protein, mouse; C120997:NR2A NMDA receptor