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Species-specific differences in NPC1 protein trafficking govern therapeutic response in Niemann-Pick type C disease
Journal article   Open access   Peer reviewed

Species-specific differences in NPC1 protein trafficking govern therapeutic response in Niemann-Pick type C disease

Mark L. Schultz, Kylie J. Schache, Ruth D. Azaria, Esmee Q. Kuiper, Steven Erwood, Evgueni A. Ivakine, Nicole Y. Farhat, Forbes D. Porter, Koralege C. Pathmasiri, Stephanie M. Cologna, …
JCI insight, Vol.7(23), e160308
12/06/2022
DOI: 10.1172/jci.insight.160308
PMCID: PMC9746915
PMID: 36301667
url
https://doi.org/10.1172/jci.insight.160308View
Published (Version of record) Open Access

Abstract

The folding and trafficking of transmembrane glycoproteins are essential for cellular homeostasis and are compromised in many diseases. In Niemann-Pick type C disease, a lysosomal disorder characterized by impaired intracellular cholesterol trafficking, the transmembrane glycoprotein NPC1 misfolds due to disease-causing missense mutations. While mutant NPC1 has emerged as a robust target for proteostasis modulators, drug development efforts have been unsuccessful in mouse models. Here, we demonstrated unexpected differences in trafficking through the medial Golgi between mouse and human I1061T-NPC1, a common disease-causing mutant. We established that these distinctions are governed by differences in the NPC1 protein sequence rather than by variations in the endoplasmic reticulum-folding environment. Moreover, we demonstrated direct effects of mutant protein trafficking on the response to small molecules that modulate the endoplasmic reticulum-folding environment by affecting Ca++ concentration. Finally, we developed a panel of isogenic human NPC1 iNeurons expressing WT, I1061T-, and R934L-NPC1 and demonstrated their utility in testing these candidate therapeutics. Our findings identify important rules governing mutant NPC1's response to proteostatic modulators and highlight the importance of species-and mutation-specific responses for therapy development.
Life Sciences & Biomedicine Medicine, Research & Experimental Research & Experimental Medicine Science & Technology

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