Phase Separation of C9orf72 Dipeptide Repeats Perturbs Stress Granule Dynamics

Mol Cell. 2017 Mar 16;65(6):1044-1055.e5. doi: 10.1016/j.molcel.2017.02.013.


Liquid-liquid phase separation (LLPS) of RNA-binding proteins plays an important role in the formation of multiple membrane-less organelles involved in RNA metabolism, including stress granules. Defects in stress granule homeostasis constitute a cornerstone of ALS/FTLD pathogenesis. Polar residues (tyrosine and glutamine) have been previously demonstrated to be critical for phase separation of ALS-linked stress granule proteins. We now identify an active role for arginine-rich domains in these phase separations. Moreover, arginine-rich dipeptide repeats (DPRs) derived from C9orf72 hexanucleotide repeat expansions similarly undergo LLPS and induce phase separation of a large set of proteins involved in RNA and stress granule metabolism. Expression of arginine-rich DPRs in cells induced spontaneous stress granule assembly that required both eIF2α phosphorylation and G3BP. Together with recent reports showing that DPRs affect nucleocytoplasmic transport, our results point to an important role for arginine-rich DPRs in the pathogenesis of C9orf72 ALS/FTLD.

Keywords: FUS; LLPS; amyotrophic lateral sclerosis; frontotemporal lobar degeneration; hnRNP; intrinsically disordered protein; low complexity domain; phase transition; prion-like domain; protein aggregation.

MeSH terms

  • Amyotrophic Lateral Sclerosis / genetics
  • Amyotrophic Lateral Sclerosis / metabolism*
  • Amyotrophic Lateral Sclerosis / pathology
  • Arginine / chemistry
  • Arginine / metabolism*
  • C9orf72 Protein
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cytoplasmic Granules / metabolism*
  • Cytoplasmic Granules / pathology
  • DNA Helicases
  • Dipeptides / chemistry
  • Dipeptides / metabolism*
  • Eukaryotic Initiation Factor-2 / genetics
  • Eukaryotic Initiation Factor-2 / metabolism
  • HeLa Cells
  • Humans
  • Intrinsically Disordered Proteins / chemistry
  • Intrinsically Disordered Proteins / metabolism*
  • Lipid Droplets / metabolism
  • Phosphorylation
  • Poly-ADP-Ribose Binding Proteins
  • Protein Domains
  • Proteins / chemistry
  • Proteins / metabolism*
  • RNA / metabolism
  • RNA Helicases
  • RNA Recognition Motif Proteins
  • Time Factors
  • Transfection


  • C9orf72 Protein
  • C9orf72 protein, human
  • Carrier Proteins
  • Dipeptides
  • Eukaryotic Initiation Factor-2
  • Intrinsically Disordered Proteins
  • Poly-ADP-Ribose Binding Proteins
  • Proteins
  • RNA Recognition Motif Proteins
  • RNA
  • Arginine
  • DNA Helicases
  • G3BP1 protein, human
  • RNA Helicases