Detection of Soluble and Insoluble Protein Species in Patient-Derived iPSCs.

Protein aggregation is one of the hallmarks of many neurodegenerative diseases. While protein aggregation is a heavily studied aspect of neurodegenerative disease, methods of detection vary from one model system to another. Induced pluripotent stem cells (iPSCs) present an opportunity to model disease using patient-specific cells. However, iPSC-derived neurons are fetal-like in maturity, making it a challenge to detect key features such as protein aggregation that are often exacerbated with age. Nevertheless, we have previously found abnormal soluble and insoluble protein burden in motor neurons generated from amyotrophic lateral sclerosis (ALS) iPSCs, though protein aggregation has not been readily detected in iPSC-derived neurons from other neurodegenerative diseases. Therefore, here we present an ultracentrifugation method that detects insoluble protein species in various models of neurodegenerative disease, including Huntington's disease, Alzheimer's disease, and ALS. This method is able to detect soluble, insoluble, and SDS-resistant species in iPSC-derived neurons and is designed to be flexible for optimal detection of various aggregation-prone proteins.