title: CGG repeats in RNA modulate expression of TDP-43 in mouse and fly models of fragile X tremor ataxia syndrome.
abstract: Determining the molecular mechanism(s) leading to Purkinje neuron loss in the neurodegenerative disorder fragile X-associated tremor/ataxia syndrome (FXTAS) is limited by the complex morphology of this cell type. Purkinje neurons are notoriously difficult to isolate and maintain in culture presenting considerable difficultly to identify molecular changes in response to expanded CGG repeat (rCGG)-containing mRNA that induces neurotoxicity in FXTAS. Several studies have uncovered a number of RNA-binding proteins involved in translation that aberrantly interact with the CGG-containing RNA; however, whether these interactions alter the translational profile of cells has not been investigated. Here we employ bacTRAP translational profiling to demonstrate that Purkinje neurons ectopically expressing 90 CGG repeats exhibit a dramatic change in their translational profile even prior to the onset of rCGG-induced phenotypes. This approach identified ∼500 transcripts that are differentially associated with ribosomes in r(CGG)₉₀-expressing mice. Functional annotation cluster analysis revealed broad ontologies enriched in the r(CGG)₉₀ list, including RNA binding and response to stress. Intriguingly, a transcript for the Tardbp gene, implicated in a number of other neurodegenerative disorders, exhibits altered association with ribosomes in the presence of r(CGG)₉₀ repeats. We therefore tested and showed that reduced association of Tardbp mRNA with the ribosomes results in a loss of TDP-43 protein expression in r(CGG)₉₀-expressing Purkinje neurons. Furthermore, we showed that TDP-43 could modulate the rCGG repeat-mediated toxicity in a Drosophila model that we developed previously. These findings together suggest that translational dysregulation may be an underlying mechanism of rCGG-induced neurotoxicity in FXTAS.
authors.affiliation: Interdepartmental Program in Cell and Molecular Biology.
authors.forename: Jocelyn N
authors.initials: JN
authors.lastname: Galloway
authors.affiliation: Department of Human and Molecular Genetics and.
authors.forename: Chad
authors.initials: C
authors.lastname: Shaw
authors.affiliation: Department of Human and Molecular Genetics and.
authors.forename: Peng
authors.initials: P
authors.lastname: Yu
authors.affiliation: Department of Pathology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA and.
authors.forename: Deena
authors.initials: D
authors.lastname: Parghi
authors.affiliation: Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Mickael
authors.initials: M
authors.lastname: Poidevin
authors.affiliation: Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Jin
authors.affiliation: Interdepartmental Program in Cell and Molecular Biology, Department of Human and Molecular Genetics and nelson@bcm.edu.
authors.forename: David L
authors.initials: DL
authors.lastname: Nelson
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001259:Ataxia / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D005600:Fragile X Syndrome / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D011689:Purkinje Cells / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D014202:Tremor / Q000235:genetics* / Q000378:metabolism; D019680:Trinucleotide Repeat Expansion
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D012333:RNA, Messenger; C000589036:TBPH protein, Drosophila; C578077:Tardbp protein, mouse