A human iPSC-derived inducible neuronal model of Niemann-Pick disease, type C1.

Anika V Prabhu,Michael E Ward,Pamela Kell,Insung Kang,Juan S Bonifacino,Raffaella De Pace,Daniel S Ory,Forbes D Porter,Christopher A Wassif,Hideji Fujiwara,Xuntian Jiang

doi:10.1186/s12915-021-01133-x

Abstract

BackgroundNiemann-Pick disease, type C (NPC) is a childhood-onset, lethal, neurodegenerative disorder caused by autosomal recessive mutations in the genes NPC1 or NPC2 and characterized by impaired cholesterol homeostasis, a lipid essential for cellular function. Cellular cholesterol levels are tightly regulated, and mutations in either NPC1 or NPC2 lead to deficient transport and accumulation of unesterified cholesterol in the late endosome/lysosome compartment, and progressive neurodegeneration in affected individuals. Previous cell-based studies to understand the NPC cellular pathophysiology and screen for therapeutic agents have mainly used patient fibroblasts. However, these do not allow modeling the neurodegenerative aspect of NPC disease, highlighting the need for an in vitro system that permits understanding the cellular mechanisms underlying neuronal loss and identifying appropriate therapies. This study reports the development of a novel human iPSC-derived, inducible neuronal model of Niemann-Pick disease, type C1 (NPC1).ResultsWe generated a null i3Neuron (inducible × integrated × isogenic) (NPC1−/− i3Neuron) iPSC-derived neuron model of NPC1. The NPC1−/− and the corresponding isogenic NPC1+/+ i3Neuron cell lines were used to efficiently generate homogenous, synchronized neurons that can be used in high-throughput screens. NPC1−/− i3Neurons recapitulate cardinal cellular NPC1 pathological features including perinuclear endolysosomal storage of unesterified cholesterol, accumulation of GM2 and GM3 gangliosides, mitochondrial dysfunction, and impaired axonal lysosomal transport. Cholesterol storage, mitochondrial dysfunction, and axonal trafficking defects can be ameliorated by treatment with 2-hydroxypropyl-β-cyclodextrin, a drug that has shown efficacy in NPC1 preclinical models and in a phase 1/2a trial.ConclusionOur data demonstrate the utility of this new cell line in high-throughput drug/chemical screens to identify potential therapeutic agents. The NPC1−/− i3Neuron line will also be a valuable tool for the NPC1 research community to explore the pathological mechanisms contributing to neuronal degeneration.Graphical abstract

Highlights

Niemann-Pick disease, type C (NPC) is a childhood-onset, lethal, neurodegenerative disorder caused by autosomal recessive mutations in the genes NPC1 or NPC2 and characterized by impaired cholesterol homeostasis, a lipid essential for cellular function
Western blot analysis confirmed undetectable levels of the NPC1 protein (Fig. 1B) in the NPC1−/− i3Neurons, confirming a null genotype. This NPC1−/− cell line had a normal karyotype (Figure S2A), and neuronal differentiation was indistinguishable from the isogenic control line (Figure S2B)
The PFO signal co-localized with lysosomal-associated membrane protein 1 (LAMP1), indicating that cholesterol accumulation is occurring in the endo-lysosomal system (Fig. 1C)

Summary

Introduction

Niemann-Pick disease, type C (NPC) is a childhood-onset, lethal, neurodegenerative disorder caused by autosomal recessive mutations in the genes NPC1 or NPC2 and characterized by impaired cholesterol homeostasis, a lipid essential for cellular function. Cellular cholesterol levels are tightly regulated, and mutations in either NPC1 or NPC2 lead to deficient transport and accumulation of unesterified cholesterol in the late endosome/ lysosome compartment, and progressive neurodegeneration in affected individuals. Previous cell-based studies to understand the NPC cellular pathophysiology and screen for therapeutic agents have mainly used patient fibroblasts These do not allow modeling the neurodegenerative aspect of NPC disease, highlighting the need for an in vitro system that permits understanding the cellular mechanisms underlying neuronal loss and identifying appropriate therapies. Various inborn errors of cholesterol homeostasis result in excessive or insufficient cellular cholesterol, which can lead to severe mental and physical abnormalities One such example is NiemannPick disease, type C (NPC). NPC is an autosomal recessive disease, characterized by the accumulation of unesterified cholesterol in the late endosome/lysosome compartment and progressive neurodegeneration in affected individuals [1]. It is critical to identify and understand the cellular processes that contribute to neuronal loss and to identify therapies that are effective in neurons

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Discussion

Conclusion