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The ALS/FTD-related C9orf72 hexanucleotide repeat expansion forms RNA condensates through multimolecular G-quadruplexes

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Raguseo, Federica 
Wang, Yiran 
Li, Jessica 
Petrić Howe, Marija 
Balendra, Rubika 


jats:titleAbstract</jats:title>jats:pAmyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases that exist on a clinico-pathogenetic spectrum, designated ALS/FTD. The most common genetic cause of ALS/FTD is expansion of the intronic hexanucleotide repeat (GGGGCC)jats:subjats:italicn</jats:italic></jats:sub> in jats:italicC9orf72</jats:italic>. Here, we investigate the formation of nucleic acid secondary structures in these expansion repeats, and their role in generating condensates characteristic of ALS/FTD. We observe significant aggregation of the hexanucleotide sequence (GGGGCC)jats:subjats:italicn</jats:italic></jats:sub>, which we associate to the formation of multimolecular G-quadruplexes (mG4s) by using a range of biophysical techniques. Exposing the condensates to G4-unfolding conditions leads to prompt disassembly, highlighting the key role of mG4-formation in the condensation process. We further validate the biological relevance of our findings by detecting an increased prevalence of G4-structures in jats:italicC9orf72</jats:italic> mutant human motor neurons when compared to healthy motor neurons by staining with a G4-selective fluorescent probe, revealing signal in putative condensates. Our findings strongly suggest that RNA G-rich repetitive sequences can form protein-free condensates sustained by multimolecular G-quadruplexes, highlighting their potential relevance as therapeutic targets for jats:italicC9orf72</jats:italic> mutation-related ALS/FTD.</jats:p>


Funder: Lister Institute of Preventive Medicine; doi:


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Nature Communications

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Springer Science and Business Media LLC
RCUK | Biotechnology and Biological Sciences Research Council (BBSRC) (BB/R011605/1)
Leverhulme Trust (EP/S023518/1)
Francis Crick Institute (Francis Crick Institute Limited) (P2022-0007)
RCUK | MRC | Medical Research Foundation (MR/S006591/1)
Academy of Medical Sciences (SGL027\1022)
EC | EU Framework Programme for Research and Innovation H2020 | H2020 Priority Excellent Science | H2020 European Research Council (H2020 Excellent Science - European Research Council) (851667, 851667, 851667)
RCUK | Engineering and Physical Sciences Research Council (EPSRC) (G98210, MR/S033947/1, MR/S031537/1)
Alzheimer’s Research UK (ARUK) (PG2019B-020)
RCUK | Medical Research Council (MRC) (MR/S006591/1)
Royal Society (URF\R\221009)