RNA-mediated neurodegeneration caused by the fragile X premutation rCGG repeats in Drosophila.
Fragile X syndrome carriers have FMR1 alleles, called premutations, with an intermediate number of 5' untranslated CGG repeats between patients (>200 repeats) and normal individuals (<60 repeats). A novel neurodegenerative disease has recently been appreciated in some premutation carriers. As no neurodegeneration is seen in fragile X patients, who do not express FMR1, we hypothesize that lengthened rCGG repeats of the premutation transcript may lead to neurodegeneration. Here, using Drosophila melanogaster, we show that 90 rCGG repeats alone are sufficient to cause neurodegeneration. This phenotype is neuron specific and rCGG repeat dosage sensitive. Although devoid of mutant protein, this neurodegeneration exhibits neuronal inclusion bodies that are Hsp70 and ubiquitin positive. Overexpression of Hsp70 could suppress the neurodegeneration. These results demonstrate that neurodegenerative phenotype associated with fragile X premutation is indeed caused by the lengthened rCGG repeats and provide the first in vivo experimental demonstration of RNA-mediated neurodegeneration.
Jin
Peng
P
Department of Human Genetics, Emory University, Atlanta, GA 30322, USA.
Zarnescu
Daniela C
DC
Zhang
Fuping
F
Pearson
Christopher E
CE
Lucchesi
John C
JC
Moses
Kevin
K
Warren
Stephen T
ST
D000818:Animals; D015153:Blotting, Western; D004195:Disease Models, Animal; D004330:Drosophila; D005123:Eye / Q000473:pathology; D005260:Female; D005455:Fluorescent Antibody Technique; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000235:genetics; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D002479:Inclusion Bodies / Q000378:metabolism / Q000473:pathology; D008297:Male; D008854:Microscopy, Electron; D009154:Mutation; D009410:Nerve Degeneration / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009474:Neurons / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics*; D016601:RNA-Binding Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019076:Transgenes; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*; D025801:Ubiquitin / Q000378:metabolism
D051860:Fragile X Messenger Ribonucleoprotein 1; D018840:HSP70 Heat-Shock Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D025801:Ubiquitin; C497683:FMR1 protein, human