An ALS-linked mutation in TDP-43 disrupts normal protein interactions in the motor neuron response to oxidative stress

Neurobiol Dis. 2020 Oct;144:105050. doi: 10.1016/j.nbd.2020.105050. Epub 2020 Aug 13.

Abstract

TDP-43 pathology is a key feature of amyotrophic lateral sclerosis (ALS), but the mechanisms linking TDP-43 to altered cellular function and neurodegeneration remain unclear. We have recently described a mouse model in which human wild-type or mutant TDP-43 are expressed at low levels and where altered stress granule formation is a robust phenotype of TDP-43M337V/- expressing cells. In the present study we use this model to investigate the functional connectivity of human TDP-43 in primary motor neurons under resting conditions and in response to oxidative stress. The interactome of human TDP-43WT or TDP-43M337V was compared by mass spectrometry, and gene ontology enrichment analysis identified pathways dysregulated by the M337V mutation. We found that under normal conditions the interactome of human TDP-43WT was enriched for proteins involved in transcription, translation and poly(A)-RNA binding. In response to oxidative stress, TDP-43WT recruits proteins of the endoplasmic reticulum and endosomal-extracellular transport pathways, interactions which are reduced in the presence of the M337V mutation. Specifically, TDP-43M337V impaired protein-protein interactions involved in stress granule formation including reduced binding to the translation initiation factors Poly(A)-binding protein and Eif4a1 and the endoplasmic reticulum chaperone Grp78. The M337V mutation also affected interactions involved in endosomal-extracellular transport and this this was associated with reduced extracellular vesicle secretion in primary motor neurons from TDP-43M337V/- mice and in human iPSCs-derived motor neurons. Taken together, our analysis highlights a TDP-43 interaction network in motor neurons and demonstrates that an ALS associated mutation may alter the interactome to drive aberrant pathways involved in the pathogenesis of ALS.

Keywords: Amyotrophic lateral sclerosis; Biomarker; Interactome; Motor neuron; Neurodegeneration; Oxidative stress; TDP-43.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyotrophic Lateral Sclerosis / genetics
  • Amyotrophic Lateral Sclerosis / metabolism*
  • Animals
  • Cells, Cultured
  • DNA-Binding Proteins / genetics*
  • Embryonic Stem Cells
  • Endoplasmic Reticulum Chaperone BiP
  • Gene Regulatory Networks*
  • Humans
  • Mice
  • Mice, Transgenic
  • Motor Neurons / metabolism*
  • Mutation
  • Oxidative Stress*
  • Protein Biosynthesis / genetics
  • Protein Interaction Maps*
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / metabolism
  • Transcription, Genetic / genetics

Substances

  • DNA-Binding Proteins
  • Endoplasmic Reticulum Chaperone BiP
  • HSPA5 protein, human
  • Hspa5 protein, mouse
  • RNA, Messenger
  • RNA-Binding Proteins
  • TARDBP protein, human