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Cell. 2016 Oct 20;167(3):774-788.e17. doi: 10.1016/j.cell.2016.10.002.

C9orf72 Dipeptide Repeats Impair the Assembly, Dynamics, and Function of Membrane-Less Organelles.

Author information

1
Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
2
Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
3
Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Howard Hughes Medical Institute, Department of Cell and Molecular Biology, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
4
Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
5
Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
6
Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Sciences Center, Memphis, TN 38105, USA.
7
Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Howard Hughes Medical Institute, Department of Cell and Molecular Biology, St Jude Children's Research Hospital, Memphis, TN 38105, USA. Electronic address: jpaul.taylor@stjude.org.

Abstract

Expansion of a hexanucleotide repeat GGGGCC (G4C2) in C9ORF72 is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Transcripts carrying (G4C2) expansions undergo unconventional, non-ATG-dependent translation, generating toxic dipeptide repeat (DPR) proteins thought to contribute to disease. Here, we identify the interactome of all DPRs and find that arginine-containing DPRs, polyGly-Arg (GR) and polyPro-Arg (PR), interact with RNA-binding proteins and proteins with low complexity sequence domains (LCDs) that often mediate the assembly of membrane-less organelles. Indeed, most GR/PR interactors are components of membrane-less organelles such as nucleoli, the nuclear pore complex and stress granules. Genetic analysis in Drosophila demonstrated the functional relevance of these interactions to DPR toxicity. Furthermore, we show that GR and PR altered phase separation of LCD-containing proteins, insinuating into their liquid assemblies and changing their material properties, resulting in perturbed dynamics and/or functions of multiple membrane-less organelles.

KEYWORDS:

C9ORF72; amyotrophic lateral sclerosis; dipeptide repeat; membrane-less organelle; nucleolus; phase separation; stress granule

PMID:
27768896
PMCID:
PMC5079111
DOI:
10.1016/j.cell.2016.10.002
[Indexed for MEDLINE]
Free PMC Article

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