Nucleocytoplasmic mRNA redistribution in ALS motor neurons and is reversed by VCP ATPase inhibition

Although the pathological hallmark of amyotrophic lateral sclerosis (ALS) is the nucleocytoplasmic mislocalisation of RNA binding proteins (RBPs), such as TDP-43 and FUS, the nucleocytoplasmic distribution of mRNA remains uncharacterised. Here, we used subcellular fractionation with RNA sequencing to assess nucleocytoplasmic mRNA localisation in human induced pluripotent stem cell-derived motor neurons (iPSNs) from ALS patients with TARDBP mutations, VCP mutations, and controls with VCP mutations isogenically knocked in with CRISPR/Cas9. In each mutant group, we found substantial nucleocytoplasmic mRNA redistribution, particularly in transcripts involved in protein binding. Redistributed transcripts in ALS iPSNs were enriched in protein-coding biotypes, exhibited longer lengths, and had enhanced interactions with RBPs, including TDP-43 and FUS. Treatment with the VCP D2 ATPase domain inhibitor ML240 partially restored nucleocytoplasmic mRNA redistribution not only in VCP mutants but also in TARDBP mutant iPSNs. Overall design: Induced pluripotent stem cell derived motor neurons from controls, TARDBP mutant, VCP mutant and VCP knock ins underwent subcellular fractionation into nuclear and cytoplasmic fractions. Cultures were treated with VCP D2 ATPase inhibitor ML240.