Purification and structure of luminal domain C of human Niemann-Pick C1 protein.
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ABSTRACT:
SUBMITTER: Odongo L
PROVIDER: S-EPMC9903137 | biostudies-literature | 2023 Feb
REPOSITORIES: biostudies-literature
Publications
Purification and structure of luminal domain C of human Niemann-Pick C1 protein.
Odongo Laura L Zadrozny Kaneil K KK Diehl William E WE Luban Jeremy J White Judith M JM Ganser-Pornillos Barbie K BK Tamm Lukas K LK Pornillos Owen O
Acta crystallographica. Section F, Structural biology communications 20230202 Pt 2
Niemann-Pick C1 protein (NPC1) is a membrane protein that primarily resides in late endosomes and lysosomes, and plays an important role in cholesterol homeostasis in the cell. The second luminal domain of NPC1 (NPC1-C) serves as the intracellular receptor for Ebola and Marburg viruses. Here, the recombinant production of nonglycosylated and glycosylated NPC1-C and a new crystal form of the nonglycosylated protein are reported. The crystals belonged to space group P2<sub>1</sub> and diffracted t ...[more]
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Project description:Niemann-Pick C1-like 1 (NPC1L1) and Niemann-Pick C2 (NPC2) is a critical mediator of cholesterol absorption. The aim of the present study was to investigate the prognostic value of NPC1L1 and NPC2 in human primary hepatocellular carcinoma (HCC). The expression level of NPC1L1 and NPC2 were evaluated by Immunohistochemistry, Westen blot and Real-time Quantitative PCR. Protein expression level in tissue was represented by integral optic density (IOD). For prognosis analyses, outcome-based cut-point was calculated by X-tile software. Kaplan-Meier analysis, Cox regression analysis were used evaluate prognostic value of NPC1L1 and NPC2 and NPC1L1/NPC2 combination. Both of NPC1L1 and NPC2 were significantly decreased in HCC tissues than peritumoral liver tissues (61 pairs of tissue for Immunohistochemistry and 10 pairs of tissues for Western blot and Real-time Quantitative PCR), respectively. (n=61: p=0.0005 for NPC1L1 and p=0.0001 for NPC2; n=10: p=0.0002 for NPC1L1 and p=0.0489 for NPC2). Kaplan-Meier analyses in 265 HCC cases were showed that the low expression level of NPC1L1 and NPC2 and NPC1L1/NPC2 combination were significantly correlated with poor overall survival (OS) and shorter time to recurrence (TTR). In addition, univariate and multivariate Cox analyses showed that the expression level of NPC1L1/NPC2 combination in HCC was an independent prognostic factor for OS and TTR. Conclusion: NPC1L1 and NPC2 were lowly expressed in HCC compared with peritumoral liver tissues, and low expression of NPC1L1 and NPC2 in HCC tissues may indicate poor outcome of HCC patients after surgery. NPC1L1/NPC2 combination is an independent prognostic factor for OS and TTR in postoperative HCC patients.
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Project description:ObjectivesThe aim of this study was to comprehensively evaluate the auditory phenotype in Niemann-Pick disease, type C1 (NPC1), to understand better the natural history of this complex, heterogeneous disorder, and to define further the baseline auditory deficits associated with NPC1 so that use of potentially ototoxic interventions (e.g., 2-hydroxypropyl-ß-cyclodextrin) may be more appropriately monitored and understood.DesignFifty patients with NPC1 ranging in age from 4 months to 21 years (mean = 9.3 years) enrolled in a natural history/observational study at the National Institutes of Health. The auditory test battery included, when possible, immittance audiometry, pure-tone and speech audiometry, otoacoustic emission testing, and a neurotologic auditory brainstem response study. Longitudinal data were collected on a subset of patients.ResultsOver half of the cohort exhibited hearing loss involving the high frequencies ranging from a slight to moderate degree, and 74% of patients presented with clinically significant hearing loss involving the frequencies most important to speech understanding (0.5, 1, 2, 4 kHz). Despite the heterogeneity of the sample, results among patients were sufficiently consistent to implicate retrocochlear dysfunction in the majority (66%) of individuals, with (22%) or without (44%) accompanying cochlear involvement. Some patients (10%) presented with a profile for auditory neuropathy spectrum disorder. The combination of cross-sectional and longitudinal data indicates these patients are at risk for a progressive decline in auditory function.ConclusionsThis is the largest cohort of patients with NPC1 evaluated comprehensively for auditory dysfunction, and results implicate the pathological processes of NPC1 in the manifestation of hearing loss. Patients with NPC1 should be monitored audiologically throughout their lives, beginning at the time of diagnosis. Clinicians and researchers should be aware of this historically overlooked aspect of the phenotype.
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Project description:The membrane protein Niemann-Pick type C1 (NPC1, named NCR1 in yeast) is central to sterol homeostasis in eukaryotes. Saccharomyces cerevisiae NCR1 is localized to the vacuolar membrane, where it is suggested to carry sterols across the protective glycocalyx and deposit them into the vacuolar membrane. However, documentation of a vacuolar glycocalyx in fungi is lacking, and the mechanism for sterol translocation has remained unclear. Here, we provide evidence supporting the presence of a glycocalyx in isolated S. cerevisiae vacuoles and report four cryo-EM structures of NCR1 in two distinct conformations, named tense and relaxed. These two conformations illustrate the movement of sterols through a tunnel formed by the luminal domains, thus bypassing the barrier presented by the glycocalyx. Based on these structures and on comparison with other members of the Resistance-Nodulation-Division (RND) superfamily, we propose a transport model that links changes in the luminal domains with a cycle of protonation and deprotonation within the transmembrane region of the protein. Our model suggests that NPC proteins work by a generalized RND mechanism where the proton motive force drives conformational changes in the transmembrane domains that are allosterically coupled to luminal/extracellular domains to promote sterol transport.
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Project description: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.
| S-EPMC8485536 | biostudies-literature