Integrated transcriptome landscape of ALS identifies genome instability linked to TDP-43 pathology

Amyotrophic Lateral Sclerosis (ALS) causes motor neuron degeneration, with 97% of cases exhibiting TDP-43 proteinopathy. Elucidating pathomechanisms has been hampered by disease heterogeneity and difficulties accessing motor neurons. Human induced pluripotent stem cell-derived motor neurons (iPSMNs) offer a solution; however, studies have typically been limited to underpowered cohorts. Here, we present a comprehensive compendium of 429 iPSMNs from 15 datasets, and 271 post-mortem spinal cord samples. Using reproducible bioinformatic workflows, we identify robust upregulation of p53 signalling in ALS in both iPSMNs and post-mortem spinal cord. p53 activation is greatest with C9orf72 repeat expansions but is weakest with SOD1 and FUS mutations. TDP-43 depletion potentiates p53 activation in both post-mortem neuronal nuclei and cell culture, thereby functionally linking p53 activation with TDP-43 depletion. ALS iPSMNs and post-mortem tissue display enrichment of splicing alterations, somatic mutations, and gene fusions, possibly contributing to the DNA damage response. The causes of ALS remain unclear with many proposed pathomechanisms. Here, the authors integrate iPSC-derived motor neuron and post-mortem datasets and identify a heightened DNA damage response accompanied by accumulation of somatic mutations in ALS.

Automated summary

Amyotrophic Lateral Sclerosis (ALS) is characterized by motor neuron degeneration, predominantly associated with TDP-43 proteinopathy. This study integrates datasets of iPSC-derived motor neurons and post-mortem tissues to identify a heightened DNA damage response and accumulation of somatic mutations in ALS. The activation of p53 signaling is robust in ALS, with stronger activation in C9orf72 repeat expansions and weaker activation in SOD1 and FUS mutations. TDP-43 depletion enhances p53 activation, linking it functionally to ALS pathogenesis.