Gene expression in the murine liver, effect of hepatic expression of Niemann-Pick C1-like 1 protein.
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE110285 | GEO | 2020/03/09
REPOSITORIES: GEO
Similar Datasets
Project description:Niemann-Pick C1 protein (NPC1) is a late-endosomal membrane protein involved in trafficking of LDL-derived cholesterol, Niemann-Pick disease type C, and Ebola virus infection. NPC1 contains 13 transmembrane segments (TMs), five of which are thought to represent a "sterol-sensing domain" (SSD). Although present also in other key regulatory proteins of cholesterol biosynthesis, uptake, and signaling, the structure and mechanism of action of the SSD are unknown. Here we report a crystal structure of a large fragment of human NPC1 at 3.6 Å resolution, which reveals internal twofold pseudosymmetry along TM 2-13 and two structurally homologous domains that protrude 60 Å into the endosomal lumen. Strikingly, NPC1's SSD forms a cavity that is accessible from both the luminal bilayer leaflet and the endosomal lumen; computational modeling suggests that this cavity is large enough to accommodate one cholesterol molecule. We propose a model for NPC1 function in cholesterol sensing and transport.
| S-EPMC4961162 | biostudies-literature
Project description:OBJECTIVES:The 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. DESIGN:Fifty 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. RESULTS:Over 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. CONCLUSIONS:This 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.
| S-EPMC3895917 | biostudies-literature
Project description:ObjectiveControversies have arisen from recent mouse studies about the essential role of biliary sterol secretion in reverse cholesterol transport (RCT). The objective of this study was to examine the role of biliary cholesterol secretion in modulating macrophage RCT in Niemann-Pick C1-Like 1 (NPC1L1) liver only (L1(LivOnly)) mice, an animal model that is defective in both biliary sterol secretion and intestinal sterol absorption, and determine whether NPC1L1 inhibitor ezetimibe facilitates macrophage RCT by inhibiting hepatic NPC1L1.Approach and resultsL1(LivOnly) mice were generated by crossing NPC1L1 knockout (L1-KO) mice with transgenic mice overexpressing human NPC1L1 specifically in liver. Macrophage-to-feces RCT was assayed in L1-KO and L1(LivOnly) mice injected intraperitoneally with [(3)H]-cholesterol-labeled peritoneal macrophages isolated from C57BL/6 mice. Inhibition of biliary sterol secretion by hepatic overexpression of NPC1L1 substantially reduced transport of [(3)H]-cholesterol from primary peritoneal macrophages to the neutral sterol fraction in bile and feces in L1(LivOnly) mice without affecting tracer excretion in the bile acid fraction. Ezetimibe treatment for 2 weeks completely restored both biliary and fecal excretion of [(3)H]-tracer in the neutral sterol fraction in L1(LivOnly) mice. High-density lipoprotein kinetic studies showed that L1(LivOnly) mice compared with L1-KO mice had a significantly reduced fractional catabolic rate without altered hepatic and intestinal uptake of high-density lipoprotein-cholesterol ether.ConclusionsIn mice lacking intestinal cholesterol absorption, macrophage-to-feces RCT depends on efficient biliary sterol secretion, and ezetimibe promotes macrophage RCT by inhibiting hepatic NPC1L1 function.
| S-EPMC3965670 | biostudies-literature
Project description:Niemann-Pick C1-like 1 (NPC1L1) is required for cholesterol absorption. Intestinal NPC1L1 appears to be a target of ezetimibe, a cholesterol absorption inhibitor that effectively lowers plasma LDL-cholesterol in humans. However, human liver also expresses NPC1L1. Hepatic function of NPC1L1 was previously unknown, but we recently discovered that NPC1L1 localizes to the canalicular membrane of primate hepatocytes and that NPC1L1 facilitates cholesterol uptake in hepatoma cells. Based upon these findings, we hypothesized that hepatic NPC1L1 allows the retention of biliary cholesterol by hepatocytes and that ezetimibe disrupts hepatic function of NPC1L1. To test this hypothesis, transgenic mice expressing human NPC1L1 in hepatocytes (L1-Tg mice) were created. Hepatic overexpression of NPC1L1 resulted in a 10- to 20-fold decrease in biliary cholesterol concentration, but not phospholipid and bile acid concentrations. This decrease was associated with a 30%-60% increase in plasma cholesterol, mainly because of the accumulation of apoE-rich HDL. Biliary and plasma cholesterol concentrations in these animals were virtually returned to normal with ezetimibe treatment. These findings suggest that in humans, ezetimibe may reduce plasma cholesterol by inhibiting NPC1L1 function in both intestine and liver, and hepatic NPC1L1 may have evolved to protect the body from excessive biliary loss of cholesterol.
| S-EPMC1888567 | biostudies-literature
Project description:BACKGROUND: Niemann-Pick type C disease (NPC) is a rare autosomal recessive lipid storage disease characterized by progressive neurodegeneration. As only a few studies have been conducted on the impact of NPC on sensory systems, we used a mutant mouse model (NPC1(-/-)) to examine the effects of this disorder to morphologically distinct regions of the olfactory system, namely the olfactory epithelium (OE) and olfactory bulb (OB). METHODOLOGY/PRINCIPAL FINDINGS: For structural and functional analysis immunohistochemistry, electron microscopy, western blotting, and electrophysiology have been applied. For histochemistry and western blotting, we used antibodies against a series of neuronal and glia marker proteins, as well as macrophage markers. NPC1(-/-) animals present myelin-like lysosomal deposits in virtually all types of cells of the peripheral and central olfactory system. Especially supporting cells of the OE and central glia cells are affected, resulting in pronounced astrocytosis and microgliosis in the OB and other olfactory cortices. Up-regulation of Galectin-3, Cathepsin D and GFAP in the cortical layers of the OB underlines the critical role and location of the OB as a possible entrance gate for noxious substances. Unmyelinated olfactory afferents of the lamina propria seem less affected than ensheathing cells. Supporting the structural findings, electro-olfactometry of the olfactory mucosa suggests that NPC1(-/-) animals exhibit olfactory and trigeminal deficits. CONCLUSIONS/SIGNIFICANCE: Our data demonstrate a pronounced neurodegeneration and glia activation in the olfactory system of NPC1(-/-), which is accompanied by sensory deficits.
| S-EPMC3877006 | biostudies-literature
Project description:Mutations in the late endosomal/lysosomal membrane protein Niemann-Pick C1 (NPC1) are known to cause a generalized block in retrograde vesicle-mediated transport, resulting in the hyper-accumulation of multiple lysosomal cargos. An important, yet often overlooked, category of lysosomal cargo includes the vast array of small molecular weight amine-containing molecules that are substrates for ion trapping in the highly acidic organelle lumen. We show here that the introduction of amine-containing molecules in lysosomes can significantly stimulate NPC1-mediated late endosome/lysosome fusion, and subsequently the secretion of lysosomal cargo. To illustrate the physiological importance of this NPC1-mediated transport pathway, we show that NPC1-deficient cells are more susceptible to the toxic effects of a lysosomotropic polyamine metabolite 3-aminopropanal. Moreover, NPC fibroblasts are shown to have higher levels of polyamine oxidase, an enzyme involved in the formation of 3-aminopropanal. Collectively, these findings provide strong support for a novel functional role for NPC1 and may also provide clues toward understanding NPC disease progression.
| S-EPMC2528997 | biostudies-literature
Project description:Niemann-Pick type C1 (NPC1) disease is caused by a deleterious mutation in the Npc1 gene, causing lysosomal accumulation of unesterified cholesterol and sphingolipids. Consequently, NPC1 disease patients suffer from severe neurovisceral symptoms which, in the absence of effective treatments, result in premature death. NPC1 disease patients display increased plasma levels of cholesterol oxidation products such as those enriched in oxidized low-density lipoprotein (oxLDL), a pro-inflammatory mediator. While it has been shown that inflammation precedes and exacerbates symptom severity in NPC1 disease, it is unclear whether oxLDL contributes to NPC1 disease progression. In this study, we investigated the effects of increasing anti-oxLDL IgM autoantibodies on systemic and neurological symptoms in an NPC1 disease mouse model. For this purpose, Npc1 nih mice were immunized with heat-inactivated S. pneumoniae, an immunogen which elicits an IgM autoantibody-mediated immune response against oxLDL. Npc1 nih mice injected with heat-inactivated pneumococci displayed an improved hepatic phenotype, including liver lipid accumulation and inflammation. In addition, regression of motor skills was delayed in immunized Npc1 nih . In line with these results, brain analyses showed an improved cerebellar phenotype and neuroinflammation in comparison with control-treated subjects. This study highlights the potential of the pneumococcal immunization as a novel therapeutical approach in NPC1 disease. Future research should investigate whether implementation of this therapy can improve life span and quality of life of NPC1 disease patients.
| S-EPMC6330339 | biostudies-literature
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.
| S-EPMC5820923 | biostudies-literature
Project description:The loss of NPC1 protein function is the predominant cause of Niemann-Pick type C1 disease (NP-C1), a systemic and neurodegenerative disorder characterized by late-endosomal/lysosomal accumulation of cholesterol and other lipids. Limited evidence from post-mortem human tissues, an Npc1(-/-) mouse model, and cell culture studies also suggest failure of metal homeostasis in NP-C1. To investigate these findings, we performed a comprehensive transition metal analysis of cerebrospinal fluid (CSF), plasma and tissue samples from human NP-C1 patients and an Npc1(-/-) mouse model. NPC1 deficiency in the Npc1(-/-) mouse model resulted in a perturbation of transition metal homeostasis in the plasma and key organs (brain, liver, spleen, heart, lungs, and kidneys). Analysis of human patient CSF, plasma and post-mortem brain tissues also indicated disrupted metal homeostasis. There was a disparity in the direction of metal changes between the human and the Npc1(-/-) mouse samples, which may reflect species-specific metal metabolism. Nevertheless, common to both species is brain zinc accumulation. Furthermore, treatment with the glucosylceramide synthase inhibitor miglustat, the only drug shown in a controlled clinical trial to have some efficacy for NP-C1, did not correct the alterations in CSF and plasma transition metal and ceruloplasmin (CP) metabolism in NP-C1 patients. These findings highlight the importance of NPC1 function in metal homeostasis, and indicate that metal-targeting therapy may be of value as a treatment for NP-C.
| S-EPMC4178950 | biostudies-literature
Project description:Lysosomal function is impaired in Niemann-Pick disease type C1 (NPC1), a rare and inherited neurodegenerative disorder, resulting in late endosomal/lysosomal accumulation of unesterified cholesterol. The precise pathogenic mechanism of NPC1 remains incompletely understood. In this study, we employed metabolomics to uncover secondary accumulated substances in NPC1. Our findings unveiled a substantial elevation in the levels of three alkyl-lysophosphatidylcholine [alkyl-LPC, also known as lyso-platelet activating factor (PAF)] species in NPC1 compared to controls across various tissues, including brain tissue from individuals with NPC1, liver, spleen, cerebrum, cerebellum, and brain stem from NPC1 mice, as well as in both brain and liver tissue from NPC1 cats. The three elevated alkyl-LPC species were as follows: LPC O-16:0, LPC O-18:1, and LPC O-18:0. However, the levels of PAF 16:0, PAF 18:1, and PAF 18:0 were not altered in NPC1. In the NPC1 feline model, the brain and liver alkyl-LPC levels were reduced following 2-hydroxypropyl-β-cyclodextrin (HPβCD) treatment, suggesting that alkyl-LPCs are secondary storage metabolites in NPC1 disease. Unexpectedly, cerebrospinal fluid (CSF) levels of LPC O-16:0 and LPC O-18:1 were decreased in individuals with NPC1 compared to age-appropriate comparison samples, and their levels were increased in 80% of participants 2 years after intrathecal HPβCD treatment. The fold increases in CSF LPC O-16:0 and LPC O-18:1 levels were more pronounced in responders compared to nonresponders. This study identified alkyl-LPC species as secondary storage metabolites in NPC1 and indicates that LPC O-16:0 and LPC O-18:1, in particular, could serve as potential biomarkers for tracking treatment response in NPC1 patients.
| S-EPMC11367646 | biostudies-literature