UC San Diego

Niemann Pick Type C1 Disease (NPC1D) is a rare lysosomal storage disease that causes severe neurodegeneration. NPC1D has no treatment or cure, and leads to premature death. This disease is caused by mutations in NPC1, which affects the NPC1 lysosomal cholesterol transporter and results in sequestration of lysosomal cholesterol. While the effect of NPC1 mutations on cholesterol distribution is well-established, the mechanism underlying neuronal failure is not. Many groups have investigated the role of autophagy in NPC1D disease pathogenesis, as lysosomes, which are plagued in NPC1D, play an important role in autophagy. However, reported phenotypes of autophagy dysfunction have been inconsistent among models of NPC1D, potentially due to the differences among models and the dynamic nature of autophagy.

To further evaluate the role of autophagy, the CRISPR/Cas9 system was used to engineer a human NPC1 knockout (KO) neuronal line. This new platform overcomes limitations associated with prior models, as it is a human neuronal line free of genetic background biases. This project aims to validate the KO line’s ability to recapitulate NPC1D biology and further investigate the relationship between NPC1 mutations and autophagy dysregulation. KO neurons recapitulate established phenotypes of NPC1D, abnormal distribution of cholesterol and decreased neuronal viability, proving it is a suitable model. Additionally, KO neurons exhibit increased induction of autophagy via Beclin-1 and impaired autophagy flow. These studies suggest that the NPC1 KO neuronal line is a valuable model to study NPC1D and dysregulation of autophagy is directly related to the loss of function of NPC1.