title: Quantitative Proteomics of Human Fibroblasts with I1061T Mutation in Niemann-Pick C1 (NPC1) Protein Provides Insights into the Disease Pathogenesis.
abstract: Niemann-Pick type C (NPC) disease is a fatal neurodegenerative disorder characterized by the accumulation of unesterified cholesterol in the late endosomal/lysosomal compartments. Mutations in the NPC1 protein are implicated in 95% of patients with NPC disease. The most prevalent mutation is the missense mutation I1061T that occurs in ∼ 15-20% of the disease alleles. In our study, an isobaric labeling-based quantitative analysis of proteome of NPC1(I1061T) primary fibroblasts when compared with wild-type cells identified 281 differentially expressed proteins based on stringent data analysis criteria. Gene ontology enrichment analysis revealed that these proteins play important roles in diverse cellular processes such as protein maturation, energy metabolism, metabolism of reactive oxygen species, antioxidant activity, steroid metabolism, lipid localization, and apoptosis. The relative expression level of a subset of differentially expressed proteins (TOR4A, DHCR24, CLGN, SOD2, CHORDC1, HSPB7, and GAA) was independently and successfully substantiated by Western blotting. We observed that treating NPC1(I1061T) cells with four classes of seven different compounds that are potential NPC drugs increased the expression level of SOD2 and DHCR24. We have also shown an abnormal accumulation of glycogen in NPC1(I1061T) fibroblasts possibly triggered by defective processing of lysosomal alpha-glucosidase. Our study provides a starting point for future more focused investigations to better understand the mechanisms by which the reported dysregulated proteins triggers the pathological cascade in NPC, and furthermore, their effect upon therapeutic interventions.
authors: From the ‡Department of Chemical Physiology.
authors: Navin
authors: N
authors: Rauniyar
authors: §Department of Cell and Molecular Biology, The Scripps Research Institute, 10550, North Torrey Pines Road, La Jolla, California-92037.
authors: Kanagaraj
authors: K
authors: Subramanian
authors: From the ‡Department of Chemical Physiology.
authors: Mathieu
authors: M
authors: Lavallée-Adam
authors: From the ‡Department of Chemical Physiology.
authors: Salvador
authors: S
authors: Martínez-Bartolomé
authors: §Department of Cell and Molecular Biology, The Scripps Research Institute, 10550, North Torrey Pines Road, La Jolla, California-92037. webalch@scripps.edu jyates@scripps.edu.
authors: William E
authors: WE
authors: Balch
authors: From the ‡Department of Chemical Physiology, webalch@scripps.edu jyates@scripps.edu.
authors: John R
authors: JR
authors: Yates
mesh_terms: D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics*; D030562:Databases, Protein; D015536:Down-Regulation; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D063990:Gene Ontology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007553:Isotope Labeling; D008562:Membrane Glycoproteins / Q000235:genetics*; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics*; D000077296:Niemann-Pick C1 Protein; D052556:Niemann-Pick Disease, Type C / Q000235:genetics*; D020543:Proteome / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D015203:Reproducibility of Results; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; C106881:NPC1 protein, human; D000077296:Niemann-Pick C1 Protein; D020543:Proteome; D013482:Superoxide Dismutase