title: A 3' untranslated region variant in FMR1 eliminates neuronal activity-dependent translation of FMRP by disrupting binding of the RNA-binding protein HuR.
abstract: Fragile X syndrome is a common cause of intellectual disability and autism spectrum disorder. The gene underlying the disorder, fragile X mental retardation 1 (FMR1), is silenced in most cases by a CGG-repeat expansion mutation in the 5' untranslated region (UTR). Recently, we identified a variant located in the 3'UTR of FMR1 enriched among developmentally delayed males with normal repeat lengths. A patient-derived cell line revealed reduced levels of endogenous fragile X mental retardation protein (FMRP), and a reporter containing a patient 3'UTR caused a decrease in expression. A control reporter expressed in cultured mouse cortical neurons showed an expected increase following synaptic stimulation that was absent when expressing the patient reporter, suggesting an impaired response to neuronal activity. Mobility-shift assays using a control RNA detected an RNA-protein interaction that is lost with the patient RNA, and HuR was subsequently identified as an associated protein. Cross-linking immunoprecipitation experiments identified the locus as an in vivo target of HuR, supporting our in vitro findings. These data suggest that the disrupted interaction of HuR impairs activity-dependent translation of FMRP, which may hinder synaptic plasticity in a clinically significant fashion.
authors.affiliation: Department of Human Genetics, Emory University, Atlanta, GA 30322;
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Suhl
authors.affiliation: Department of Cell Biology, Emory University, Atlanta, GA 30322;
authors.forename: Ravi S
authors.initials: RS
authors.lastname: Muddashetty
authors.affiliation: Department of Human Genetics, Emory University, Atlanta, GA 30322; Department of Cell Biology, Emory University, Atlanta, GA 30322;
authors.forename: Bart R
authors.initials: BR
authors.lastname: Anderson
authors.affiliation: Department of Cell Biology, Emory University, Atlanta, GA 30322;
authors.forename: Marius F
authors.initials: MF
authors.lastname: Ifrim
authors.affiliation: Department of Human Genetics, Emory University, Atlanta, GA 30322;
authors.forename: Jeannie
authors.initials: J
authors.lastname: Visootsak
authors.affiliation: Department of Cell Biology, Emory University, Atlanta, GA 30322;
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Bassell
authors.affiliation: Department of Human Genetics, Emory University, Atlanta, GA 30322; Department of Biochemistry, Emory University, Atlanta, GA 30322; Department of Pediatrics, Emory University, Atlanta, GA 30322 swarren@emory.edu.
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Warren
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics*; D000483:Alleles; D000818:Animals; D001483:Base Sequence; D019921:Biotinylation; D002478:Cells, Cultured; D003712:Dendrites / Q000378:metabolism; D000067780:ELAV-Like Protein 1 / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics* / Q000378:metabolism; D017930:Genes, Reporter; D056426:Genetic Loci; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction / Q000235:genetics; D013569:Synapses / Q000378:metabolism; D053719:Tandem Mass Spectrometry
chemical_list: D020413:3' Untranslated Regions; D000067780:ELAV-Like Protein 1; D051860:Fragile X Messenger Ribonucleoprotein 1; D008156:Luciferases; D012333:RNA, Messenger; D017470:Receptors, Glutamate
keywords: FMR1; FMRP; HuR; autism; fragile X syndrome