Argonaute-2-dependent rescue of a Drosophila model of FXTAS by FRAXE premutation repeat

Hum Mol Genet. 2007 Oct 1;16(19):2326-32. doi: 10.1093/hmg/ddm186. Epub 2007 Jul 17.


Fragile X Syndrome is the most common form of hereditary mental retardation. It is caused by a large expansion of the CGG trinucleotide repeat (>200 repeats) in the 5'-untranslated region (UTR) of the FMR1 gene that leads to silencing of its transcript. Individuals with CGG repeat expansions approximately between 60 and 200 are referred to as premutation carriers. Fragile X-associated tremor and ataxia syndrome (FXTAS), an RNA-mediated neurodegenerative disease has been described in up to 50% of males carrying premutation alleles. FRAXE, the most common form of non-syndromic X-linked mental retardation, is caused by expansion of a CCG trinucleotide repeat (>200) in the 5'-UTR of the FMR2 gene. While the FRAXE premutation length repeat is observed in the general population, there has not yet been a report of a neurodegenerative phenotype associated with these alleles. In this study, we show that the CCG premutation length repeat leads to an RNA-mediated neurodegenerative phenotype in a Drosophila model. Furthermore, we show that co-expression of both the CCG and CGG-containing RNAs suppresses their independent toxicity and is dependent on the RNAi pathway. These data support the concept that RNA toxicity is the mechanism of neuronal toxicity and suggests potential reversal of RNA-mediated phenotypes with complementary RNA molecules.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Argonaute Proteins
  • Ataxia / genetics*
  • Ataxia / pathology
  • Ataxia / physiopathology
  • Behavior, Animal
  • Blotting, Western
  • Disease Models, Animal
  • Drosophila / genetics
  • Drosophila / physiology
  • Drosophila / ultrastructure
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / physiology
  • Eye / metabolism
  • Eye / pathology
  • Eye / ultrastructure
  • Female
  • Fragile X Mental Retardation Protein / genetics*
  • Fragile X Mental Retardation Protein / physiology
  • Fragile X Syndrome / genetics*
  • Fragile X Syndrome / pathology
  • Fragile X Syndrome / physiopathology
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Humans
  • Male
  • Microscopy, Electron, Scanning
  • RNA-Induced Silencing Complex / genetics*
  • RNA-Induced Silencing Complex / physiology
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tremor / genetics*
  • Tremor / pathology
  • Tremor / physiopathology
  • Trinucleotide Repeat Expansion*


  • AGO2 protein, Drosophila
  • Argonaute Proteins
  • Drosophila Proteins
  • RNA-Induced Silencing Complex
  • Recombinant Fusion Proteins
  • Fragile X Mental Retardation Protein
  • Green Fluorescent Proteins