CRISPR-Cas9 screens in human cells and primary neurons identify modifiers of C9ORF72 dipeptide-repeat-protein toxicity

Nat Genet. 2018 Apr;50(4):603-612. doi: 10.1038/s41588-018-0070-7. Epub 2018 Mar 5.

Abstract

Hexanucleotide-repeat expansions in the C9ORF72 gene are the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia (c9ALS/FTD). The nucleotide-repeat expansions are translated into dipeptide-repeat (DPR) proteins, which are aggregation prone and may contribute to neurodegeneration. We used the CRISPR-Cas9 system to perform genome-wide gene-knockout screens for suppressors and enhancers of C9ORF72 DPR toxicity in human cells. We validated hits by performing secondary CRISPR-Cas9 screens in primary mouse neurons. We uncovered potent modifiers of DPR toxicity whose gene products function in nucleocytoplasmic transport, the endoplasmic reticulum (ER), proteasome, RNA-processing pathways, and chromatin modification. One modifier, TMX2, modulated the ER-stress signature elicited by C9ORF72 DPRs in neurons and improved survival of human induced motor neurons from patients with C9ORF72 ALS. Together, our results demonstrate the promise of CRISPR-Cas9 screens in defining mechanisms of neurodegenerative diseases.

Publication types

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

MeSH terms

  • Active Transport, Cell Nucleus / genetics
  • Amyotrophic Lateral Sclerosis / etiology
  • Amyotrophic Lateral Sclerosis / genetics
  • Amyotrophic Lateral Sclerosis / metabolism
  • Animals
  • C9orf72 Protein / genetics*
  • C9orf72 Protein / metabolism
  • C9orf72 Protein / toxicity
  • CRISPR-Cas Systems
  • DNA Repeat Expansion
  • Endoplasmic Reticulum Stress / genetics
  • Frontotemporal Dementia / etiology
  • Frontotemporal Dementia / genetics
  • Frontotemporal Dementia / metabolism
  • Gene Knockout Techniques
  • HeLa Cells
  • Humans
  • K562 Cells
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mice
  • Microsatellite Repeats
  • Motor Neurons / metabolism
  • Thioredoxins / genetics
  • Thioredoxins / metabolism
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / metabolism

Substances

  • C9orf72 Protein
  • C9orf72 protein, human
  • C9orf72 protein, mouse
  • Membrane Proteins
  • TMX2 protein, human
  • rab7 protein
  • Thioredoxins
  • rab GTP-Binding Proteins