Integrated profiling of iPSC-derived motor neurons carrying C9orf72, FUS, TARDBP, or SOD1 mutations

We conducted temporal RNA-seq profiling of human induced pluripotent stem cells (hiPSCs) and iPSC-derived motor neurons (iMNs) carrying C9orf72, FUS, TARDBP, or SOD1 mutations in both patients with ALS and healthy individuals. We discovered dysregulated gene expression and alternative splicing (AS) throughout iMN development and maturation, and iMNs with mutations in ALS-associated genes displayed enrichment of cytoskeletal defects and synaptic alterations from the premature stage to mature iMNs. Our findings indicate that synaptic gene dysfunction is a common molecular hallmark of familial ALS, which may result in neuronal susceptibility and progressive motor neuron degeneration. Analysis of upstream splicing factors revealed that differentially expressed RNA-binding proteins (RBPs) in iMNs from patients with ALS may cause abnormal AS events, highlighting the importance of studying RBP defects in ALS research. Overall, our research provides a comprehensive and valuable resource for gaining insights into the shared mechanisms of familial ALS pathogenesis during motor neuron development and maturation in iMN models.