Nucleocytoplasmic Proteomic Analysis Uncovers eRF1 and Nonsense-Mediated Decay as Modifiers of ALS/FTD C9orf72 Toxicity

Neuron. 2020 Apr 8;106(1):90-107.e13. doi: 10.1016/j.neuron.2020.01.020. Epub 2020 Feb 13.


The most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is a hexanucleotide repeat expansion in C9orf72 (C9-HRE). While RNA and dipeptide repeats produced by C9-HRE disrupt nucleocytoplasmic transport, the proteins that become redistributed remain unknown. Here, we utilized subcellular fractionation coupled with tandem mass spectrometry and identified 126 proteins, enriched for protein translation and RNA metabolism pathways, which collectively drive a shift toward a more cytosolic proteome in C9-HRE cells. Among these was eRF1, which regulates translation termination and nonsense-mediated decay (NMD). eRF1 accumulates within elaborate nuclear envelope invaginations in patient induced pluripotent stem cell (iPSC) neurons and postmortem tissue and mediates a protective shift from protein translation to NMD-dependent mRNA degradation. Overexpression of eRF1 and the NMD driver UPF1 ameliorate C9-HRE toxicity in vivo. Our findings provide a resource for proteome-wide nucleocytoplasmic alterations across neurodegeneration-associated repeat expansion mutations and highlight eRF1 and NMD as therapeutic targets in C9orf72-associated ALS and/or FTD.

Keywords: C9orf72; ETF1/eRF1; UPF1; amyotrophic lateral sclerosis; frontotemporal dementia; motor neurons; neurodegeneration; nonsense-mediated decay; nuclear invaginations; nucleocytoplasmic proteome.

Publication types

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

MeSH terms

  • Amyotrophic Lateral Sclerosis / genetics*
  • Amyotrophic Lateral Sclerosis / metabolism
  • Animals
  • C9orf72 Protein / genetics*
  • C9orf72 Protein / metabolism
  • Cell Fractionation
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster
  • Frontotemporal Dementia / genetics*
  • Frontotemporal Dementia / metabolism
  • HEK293 Cells
  • Humans
  • Induced Pluripotent Stem Cells
  • Neurons / metabolism*
  • Nonsense Mediated mRNA Decay / genetics*
  • Nuclear Envelope
  • Peptide Chain Termination, Translational / genetics
  • Peptide Termination Factors / genetics*
  • Peptide Termination Factors / metabolism
  • Protein Biosynthesis
  • Proteome
  • RNA, Messenger / metabolism*
  • Subcellular Fractions
  • Tandem Mass Spectrometry


  • C9orf72 Protein
  • Drosophila Proteins
  • ETF1 protein, human
  • Peptide Termination Factors
  • Proteome
  • RNA, Messenger
  • Upf1 protein, Drosophila
  • eRF1 protein, Drosophila

Supplementary concepts

  • Frontotemporal Dementia With Motor Neuron Disease