The Establishment of Patient Fibroblast-derived Induced Neurons for Understanding the Pathogenic Mechanisms of Neurodegenerative Diseases

Abstract

The identification of novel susceptibility genes for neurodegenerative diseases is essential for understanding mechanisms of progressive neuronal cell death. Taking advantage of sequencing based approaches, a large number of disease-related genes have been discovered and the importance of disease-cell models that recapitulate specific pathological features to identify genotype-phenotype relationships and its role in pathogenic mechanisms could not be overemphasized enough. In Part I, applying multi-gene panel testing and direct sequencing in patients with amyotrophic lateral sclerosis (ALS), a neurological disorder that leads to motor neuron degeneration, mutations in the fused in sarcoma (FUS) gene in three ALS patients are identified in this study. Since current cell modeling systems for understanding ALS-associated FUS (ALS-FUS) pathology do not sufficiently present pathological neuronal signatures found in patient autopsies, a disease-specific induced neurons (iNeurons) directly converted from ALS patients’ fibroblasts harboring FUS mutations was generated. In Part II, Sanger sequencing was used to find a novel compound heterozygous mutations (p.K563* + p.L634S) in the β-galactosylceramidase (galc) gene in a Krabbe disease (KD) patient, lysosomal storage disease with predominant neurological manifestations. This study reports that the directly converted KD iNeurons showed neurite degeneration and aberrant branching, thus, suggesting autonomous neuronal toxicity in KD. Development of more disease-relevant experimental models of alive patient with neurodegenerative diseases that recapitulate the characteristics of neuronal dysfunction found in human post-mortem tissue will make important contributions to both understanding pathophysiologic mechanisms and developing therapeutic strategies. Therefore, simple, reliable, and reproducible iNeuron model of patients will be a representative tool that mirrors the disease pathology of the alive patients with neurodegenerative disorders.