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Zheng Q, Li X, Huang N, Li F, Ge J, Wang D, Sun R, Liu R. Saikosaponins ameliorate hyperlipidemia in rats by enhancing hepatic lipid and cholesterol metabolism. JOURNAL OF ETHNOPHARMACOLOGY 2023; 305:116110. [PMID: 36581162 DOI: 10.1016/j.jep.2022.116110] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/22/2022] [Accepted: 12/24/2022] [Indexed: 06/17/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Hyperlipidemia is the systemic manifestation of abnormal lipid metabolism, characterized by elevated circulating levels of cholesterol and triglyceride and a high risk of cardiovascular events. Radix Bupleuri (RB) is a traditional Chinese herbal product used to treat liver diseases. Our previous study demonstrated that Saikosaponins (SSs), the most potent bioactive ingredients in RB, ameliorate hepatic steatosis. However, whether SSs have anti-hyperlipidemia effects and plausible underlying mechanisms remain elusive. AIM OF THE STUDY To comprehensively evaluate the lipid-lowering potential of SSs against hyperlipidemia in rats. MATERIALS AND METHODS RNA sequencing and untargeted metabolomics approaches were applied to analyze the changes in the liver transcriptome and serum lipid profile in long-term high-fat diet feeding-induced hyperlipidemia rats in response to SSs or positive drug simvastatin (SIM) intervention. RESULTS Our data revealed that SSs significantly alleviated HFD-induced hypertriglyceridemia and hypercholesterolemia. Combined with the analysis of gene ontology enrichment analysis and gene set enrichment analysis, we found that SSs remarkably repaired the unbalanced blood lipid metabolic spectrum in a dose-dependent manner by increasing the hepatic uptake of circulating fatty acids and facilitating mitochondrial respiration in fatty acid oxidation, comparable to SIM group. In addition, SSs markedly modulated cholesterol clearance by promoting intracellular cholesterol efflux, HDL remodeling, LDL particle clearance, and bile acid synthesis. SSs also efficiently protected the liver from lipid overload-related oxidative stress and lipid peroxidation, as well as substantially exaggerated inflammatory response. CONCLUSION Our research not only unraveled the intricate mechanisms underlying the lipid-lowering functions of SSs but also provided novel perspectives on developing an SSs-based therapeutic strategy for the treatment of hyperlipidemia. CLASSIFICATION Metabolism.
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Affiliation(s)
- Qi Zheng
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, 11 Bei San Huan Dong Lu, Beijing, 100029, China
| | - Xiaojiaoyang Li
- School of Life Sciences, Beijing University of Chinese Medicine, 11 Bei San Huan Dong Lu, Beijing, 100029, China
| | - Nana Huang
- The Second Hospital of Shandong University, Shan Dong University, 247 Bei Yuan Da Jie, Jinan, 250033, China
| | - Fanghong Li
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, 11 Bei San Huan Dong Lu, Beijing, 100029, China
| | - Junde Ge
- The Second Hospital of Shandong University, Shan Dong University, 247 Bei Yuan Da Jie, Jinan, 250033, China
| | - Daijie Wang
- Biological Engineering Technology Innovation Center of Shandong Province, Heze Branch of Qilu University of Technology (Shandong Academy of Sciences), Heze, 274000, China
| | - Rong Sun
- The Second Hospital of Shandong University, Shan Dong University, 247 Bei Yuan Da Jie, Jinan, 250033, China.
| | - Runping Liu
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, 11 Bei San Huan Dong Lu, Beijing, 100029, China.
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Wang X, Han X, Wang S, Wang Y, Wang P, Zhao Z, Qin H, Jing C, Liang C. Extraction of honokiol from Artemisia argyi and in vitro and in vivo investigation of its antifungal activity. Nat Prod Res 2023; 37:651-656. [PMID: 35506313 DOI: 10.1080/14786419.2022.2071887] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Extracts from plants used in Chinese medicine can be good sources of fungicides for agricultural applications. In this study, we separated and identified antifungal compounds from four traditional Chinese medicine extracts and evaluated their antifungal activities in vitro and in vivo. In vitro, honokiol extracted from Artemisia argyi showed broad-spectrum antimicrobial and mycelial inhibitory activity with EC50 in the range 3.56 - 33.85 μg/mL against eight plant pathogens. q-PCR indicated that honokiol might induce cell cancerisation and inhibit cellular respiration, which provided significant insights into honokiol function in tobacco resistance to molecular mechanisms of the phytopathogenic fungus Phytophthora nicotianae. In vivo, honokiol significantly decreased the rate of fungal infection in eggplants, potatoes, grapes, cherry tomatoes, and cucumbers, and enhanced disease resistance in tobacco. Overall, our results indicate that honokiol has the potential to control a variety of fungal and oomycete diseases, and A. argyi could be a source of honokiol.
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Affiliation(s)
- Xianxian Wang
- Shandong Engineering Research Center for Environment-Friendly Agricultural Pest Management, College of Plant Health and Medicine, Qingdao Agricultural University, Qingdao, China
| | - Xiaobin Han
- Zunyi Branch, Guizhou Tobacco Company, Zunyi, China
| | - Shu Wang
- Technology Center of Qingdao Customs, Qingdao, China
| | - Yaobin Wang
- Qingdao Branch, Shandong Qingdao Tobacco Co., Ltd, Qingdao, China
| | - Peng Wang
- Qingdao Branch, Shandong Qingdao Tobacco Co., Ltd, Qingdao, China
| | - Zhongli Zhao
- Qingdao Branch, Shandong Qingdao Tobacco Co., Ltd, Qingdao, China
| | - Huimin Qin
- Shandong Engineering Research Center for Environment-Friendly Agricultural Pest Management, College of Plant Health and Medicine, Qingdao Agricultural University, Qingdao, China
| | - Changliang Jing
- Ocean Agricultural Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Chen Liang
- Shandong Engineering Research Center for Environment-Friendly Agricultural Pest Management, College of Plant Health and Medicine, Qingdao Agricultural University, Qingdao, China
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Dietary oxidized frying oil activates hepatic stellate cells and accelerates the severity of carbon tetrachloride- and thioacetamide-induced liver fibrosis in mice. J Nutr Biochem 2023; 115:109267. [PMID: 36641072 DOI: 10.1016/j.jnutbio.2023.109267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 11/18/2022] [Accepted: 01/05/2023] [Indexed: 01/13/2023]
Abstract
Deep-frying is a common cooking practice worldwide, and after repeated heating's, the oil undergoes various chemical reactions, including hydrolysis, polymerization, lipid oxidation, and the Maillard reaction. Studies have pointed out that oxidized dietary frying oil may cause teratogenesis in mice and increase cancer and cardiovascular risks. The liver is the main organ involved in dietary nutrient catabolism, detoxification, bile production, and lipid metabolism. Nevertheless, the effects of oxidized frying oil exposure on the activation of hepatic stellate cells (HSCs) and liver fibrosis are still unclear. In this study, we showed that exposure to oxidized frying oil enhanced the sensitivity of HSCs to transforming growth factor (TGF)-β1-induced α-smooth muscle actin (α-SMA), collagen 1a2, collagen 1a1, metalloproteinase-2, and phosphorylated smad2/3 activation. In both carbon tetrachloride (CCl4)- and thioacetamide (TAA)-induced liver fibrosis mouse models, we showed that long-term administration of a 10% fried oil-containing diet significantly upregulated fibrogenesis genes expression and deposition of hepatic collagen. Furthermore, long-term fried oil exposure not only promoted macrophage infiltration and increased inflammatory-related gene expression, but also accumulated excess cholesterol and lipid peroxidation in the liver tissues. In conclusion, our study demonstrated that feeding a fried oil-containing diet may trigger TGF-β1-induced HSCs activation and thereby promote liver damage and fibrosis progression through enhancing the inflammatory response and lipid peroxidation.
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Paten AM, Colin T, Coppin CW, Court LN, Barron AB, Oakeshott JG, Morgan MJ. Non-additive gene interactions underpin molecular and phenotypic responses in honey bee larvae exposed to imidacloprid and thymol. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 814:152614. [PMID: 34963587 DOI: 10.1016/j.scitotenv.2021.152614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 06/14/2023]
Abstract
Understanding the cumulative risk of chemical mixtures at environmentally realistic concentrations is a key challenge in honey bee ecotoxicology. Ecotoxicogenomics, including transcriptomics, measures responses in individual organisms at the molecular level which can provide insights into the mechanisms underlying phenotypic responses induced by one or more stressors and link impacts on individuals to populations. Here, fifth instar honey bee larvae were sampled from a previously reported field experiment exploring the phenotypic impacts of environmentally realistic chronic exposures of the pesticide imidacloprid (5 μg.kg-1 for six weeks) and the acaricide thymol (250 g.kg-1 applied via Apiguard gel in-hive for four weeks), both separately and in combination. RNA-seq was used to discover individual and interactive chemical effects on larval gene expression and to uncover molecular mechanisms linked to reported adult and colony phenotypes. The separate and combined treatments had distinct gene expression profiles which represented differentially affected signaling and metabolic pathways. The molecular signature of the mixture was characterised by additive interactions in canonical stress responses associated with oxidative stress and detoxification, and non-additive interactions in secondary responses including developmental, neurological, and immune pathways. Novel emergent impacts on eye development genes correlated with long-term defects in visual learning performance as adults. This is consistent with these chemicals working through independent modes of action that combine to impact common downstream pathways, and highlights the importance of establishing mechanistic links between molecular and phenotypic responses when predicting effects of chemical mixtures on ecologically relevant population outcomes.
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Affiliation(s)
- Amy M Paten
- Land and Water, CSIRO, Black Mountain, Canberra, ACT 2601, Australia.
| | - Théotime Colin
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Chris W Coppin
- Land and Water, CSIRO, Black Mountain, Canberra, ACT 2601, Australia.
| | - Leon N Court
- Land and Water, CSIRO, Black Mountain, Canberra, ACT 2601, Australia.
| | - Andrew B Barron
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
| | - John G Oakeshott
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia; Applied Biosciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Matthew J Morgan
- Land and Water, CSIRO, Black Mountain, Canberra, ACT 2601, Australia.
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Different Trafficking Phenotypes of Niemann-Pick C1 Gene Mutations Correlate with Various Alterations in Lipid Storage, Membrane Composition and Miglustat Amenability. Int J Mol Sci 2020; 21:ijms21062101. [PMID: 32204338 PMCID: PMC7139583 DOI: 10.3390/ijms21062101] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 03/15/2020] [Accepted: 03/16/2020] [Indexed: 12/24/2022] Open
Abstract
Niemann-Pick Type C (NPC) is an autosomal recessive lysosomal storage disease leading to progressive neurodegeneration. Mutations in the NPC1 gene, which accounts for 95% of the cases, lead to a defect in intra-lysosomal trafficking of cholesterol and an accumulation of storage material including cholesterol and sphingolipids in the endo-lysosomal system. Symptoms are progressive neurological and visceral deterioration, with variable onset and severity of the disease. This study investigates the influence of two different NPC1 mutations on the biochemical phenotype in fibroblasts isolated from NPC patients in comparison to healthy, wild type (WT) cells. Skin derived fibroblasts were cultured from one patient compound-heterozygous for D874V/D948Y mutations, which presented wild-type like intracellular trafficking of NPC1, and a second patient compound- heterozygous for I1061T/P887L mutations, which exhibited a more severe biochemical phenotype as revealed in the delayed trafficking of NPC1. Biochemical analysis using HPLC and TLC indicated that lipid accumulations were mutation-dependent and correlated with the trafficking pattern of NPC1: higher levels of cholesterol and glycolipids were associated with the mutations that exhibited delayed intracellular trafficking, as compared to their WT-like trafficked or wild type (WT) counterparts. Furthermore, variations in membrane structure was confirmed in these cell lines based on alteration in lipid rafts composition as revealed by the shift in flotillin-2 (FLOT2) distribution, a typical lipid rafts marker, which again showed marked alterations only in the NPC1 mutant showing major trafficking delay. Finally, treatment with N-butyldeoxynojirimycin (NB-DNJ, Miglustat) led to a reduction of stored lipids in cells from both patients to various extents, however, no normalisation in lipid raft structure was achieved. The data presented in this study help in understanding the varying biochemical phenotypes observed in patients harbouring different mutations, which explain why the effectiveness of NB-DNJ treatment is patient specific.
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Schultz ML, Fawaz MV, Azaria RD, Hollon TC, Liu EA, Kunkel TJ, Halseth TA, Krus KL, Ming R, Morin EE, McLoughlin HS, Bushart DD, Paulson HL, Shakkottai VG, Orringer DA, Schwendeman AS, Lieberman AP. Synthetic high-density lipoprotein nanoparticles for the treatment of Niemann-Pick diseases. BMC Med 2019; 17:200. [PMID: 31711490 PMCID: PMC6849328 DOI: 10.1186/s12916-019-1423-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 09/10/2019] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Niemann-Pick disease type C is a fatal and progressive neurodegenerative disorder characterized by the accumulation of unesterified cholesterol in late endosomes and lysosomes. We sought to develop new therapeutics for this disorder by harnessing the body's endogenous cholesterol scavenging particle, high-density lipoprotein (HDL). METHODS Here we design, optimize, and define the mechanism of action of synthetic HDL (sHDL) nanoparticles. RESULTS We demonstrate a dose-dependent rescue of cholesterol storage that is sensitive to sHDL lipid and peptide composition, enabling the identification of compounds with a range of therapeutic potency. Peripheral administration of sHDL to Npc1 I1061T homozygous mice mobilizes cholesterol, reduces serum bilirubin, reduces liver macrophage size, and corrects body weight deficits. Additionally, a single intraventricular injection into adult Npc1 I1061T brains significantly reduces cholesterol storage in Purkinje neurons. Since endogenous HDL is also a carrier of sphingomyelin, we tested the same sHDL formulation in the sphingomyelin storage disease Niemann-Pick type A. Utilizing stimulated Raman scattering microscopy to detect endogenous unlabeled lipids, we show significant rescue of Niemann-Pick type A lipid storage. CONCLUSIONS Together, our data establish that sHDL nanoparticles are a potential new therapeutic avenue for Niemann-Pick diseases.
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Affiliation(s)
- Mark L Schultz
- Department of Pathology, University of Michigan Medical School, 3510 MSRB1, 1150 W. Medical Center Dr., Ann Arbor, MI, 48109, USA
| | - Maria V Fawaz
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Ruth D Azaria
- Department of Pathology, University of Michigan Medical School, 3510 MSRB1, 1150 W. Medical Center Dr., Ann Arbor, MI, 48109, USA
| | - Todd C Hollon
- Department of Neurosurgery, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Elaine A Liu
- Department of Pathology, University of Michigan Medical School, 3510 MSRB1, 1150 W. Medical Center Dr., Ann Arbor, MI, 48109, USA
- Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Medical Scientist Training Program, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Thaddeus J Kunkel
- Department of Pathology, University of Michigan Medical School, 3510 MSRB1, 1150 W. Medical Center Dr., Ann Arbor, MI, 48109, USA
| | - Troy A Halseth
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Kelsey L Krus
- Department of Pathology, University of Michigan Medical School, 3510 MSRB1, 1150 W. Medical Center Dr., Ann Arbor, MI, 48109, USA
| | - Ran Ming
- Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, B20-102W NCRC, 2800 Plymouth Road, Ann Arbor, MI, 48109, USA
| | - Emily E Morin
- Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, B20-102W NCRC, 2800 Plymouth Road, Ann Arbor, MI, 48109, USA
| | - Hayley S McLoughlin
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - David D Bushart
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Henry L Paulson
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Vikram G Shakkottai
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Daniel A Orringer
- Department of Neurosurgery, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Anna S Schwendeman
- Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, B20-102W NCRC, 2800 Plymouth Road, Ann Arbor, MI, 48109, USA.
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, 48109, USA.
| | - Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, 3510 MSRB1, 1150 W. Medical Center Dr., Ann Arbor, MI, 48109, USA.
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Insights into the Molecular Mechanisms of Cholesterol Binding to the NPC1 and NPC2 Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1135:139-160. [PMID: 31098815 DOI: 10.1007/978-3-030-14265-0_8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In recent years, a growing number of studies have implicated the coordinated action of NPC1 and NPC2 in intralysosomal transport and efflux of cholesterol. Our current understanding of this process developed with just over two decades of research. Since the cloning of the genes encoding the NPC1 and NPC2 proteins, studies of the biochemical defects observed when either gene is mutated along with computational and structural studies have unraveled key steps in the underlying mechanism. Here, we summarize the major contributions to our understanding of the proposed cholesterol transport controlled by NPC1 and NPC2, and briefly discuss recent findings of cholesterol binding and transport proteins beyond NPC1 and NPC2. We conclude with key questions and major challenges for future research on cholesterol transport by the NPC1 and NPC2 proteins.
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Abstract
Lysosomal storage diseases (LSDs) are a group of over 70 diseases that are characterized by lysosomal dysfunction, most of which are inherited as autosomal recessive traits. These disorders are individually rare but collectively affect 1 in 5,000 live births. LSDs typically present in infancy and childhood, although adult-onset forms also occur. Most LSDs have a progressive neurodegenerative clinical course, although symptoms in other organ systems are frequent. LSD-associated genes encode different lysosomal proteins, including lysosomal enzymes and lysosomal membrane proteins. The lysosome is the key cellular hub for macromolecule catabolism, recycling and signalling, and defects that impair any of these functions cause the accumulation of undigested or partially digested macromolecules in lysosomes (that is, 'storage') or impair the transport of molecules, which can result in cellular damage. Consequently, the cellular pathogenesis of these diseases is complex and is currently incompletely understood. Several LSDs can be treated with approved, disease-specific therapies that are mostly based on enzyme replacement. However, small-molecule therapies, including substrate reduction and chaperone therapies, have also been developed and are approved for some LSDs, whereas gene therapy and genome editing are at advanced preclinical stages and, for a few disorders, have already progressed to the clinic.
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Coordinate regulation of mutant NPC1 degradation by selective ER autophagy and MARCH6-dependent ERAD. Nat Commun 2018; 9:3671. [PMID: 30202070 PMCID: PMC6131187 DOI: 10.1038/s41467-018-06115-2] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 07/26/2018] [Indexed: 12/30/2022] Open
Abstract
Niemann–Pick type C disease is a fatal, progressive neurodegenerative disorder caused by loss-of-function mutations in NPC1, a multipass transmembrane glycoprotein essential for intracellular lipid trafficking. We sought to define the cellular machinery controlling degradation of the most common disease-causing mutant, I1061T NPC1. We show that this mutant is degraded, in part, by the proteasome following MARCH6-dependent ERAD. Unexpectedly, we demonstrate that I1061T NPC1 is also degraded by a recently described autophagic pathway called selective ER autophagy (ER-phagy). We establish the importance of ER-phagy both in vitro and in vivo, and identify I1061T as a misfolded endogenous substrate for this FAM134B-dependent process. Subcellular fractionation of I1061T Npc1 mouse tissues and analysis of human samples show alterations of key components of ER-phagy, including FAM134B. Our data establish that I1061T NPC1 is recognized in the ER and degraded by two different pathways that function in a complementary fashion to regulate protein turnover. Niemann-Pick type C1 disease is most commonly caused by the allele NPC1 I1061T, which is misfolded in the ER and rapidly degraded by the ubiquitin proteasome system. Here the authors show that the I1061T mutant is also degraded by ER-phagy.
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Zheng JC, Sun SL, Yue XR, Liu TX, Jing X. Phylogeny and evolution of the cholesterol transporter NPC1 in insects. JOURNAL OF INSECT PHYSIOLOGY 2018; 107:157-166. [PMID: 29649482 DOI: 10.1016/j.jinsphys.2018.04.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 04/08/2018] [Accepted: 04/08/2018] [Indexed: 06/08/2023]
Abstract
Sterols are essential nutrients for eukaryotes. Insects are obligate sterol auxotrophs and must acquire this key nutrient from their diets. The digestive tract is the organ for absorbing nutrients as well as sterols from food. In mice, the Niemann-Pick type C1 Like 1 (NPC1L1) gene is highly expressed in the intestine and is critical for cholesterol absorption. In contrast, the molecular mechanisms for the absorption of dietary sterols in insects have not been well studied. We annotated NPC1 genes in 39 insects from 10 orders using available genomic and transcriptomic information and inferred phylogenetic relationships. Insect NPC1 genes were grouped into two sister-clades, NPC1a and NPC1b, suggesting a likely duplication in the ancestor of insects. The former exhibited weaker gut-biased expression or a complete lack of tissue-biased expression, depending on the species, while the latter was highly enriched in the gut of three lepidopteran species. This result is similar to previous findings in Drosophila melanogaster. In insects, NPC1a accumulated non-synonymous substitutions at a lower rate than NPC1b. This pattern was consistent across orders, indicating that NPC1a evolved under stronger molecular constraint than NPC1b.
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Affiliation(s)
- Jin-Cheng Zheng
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China; Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Shao-Lei Sun
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China; Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xiao-Rong Yue
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China; Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Tong-Xian Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China; Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
| | - Xiangfeng Jing
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China; Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
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RND transporters in the living world. Res Microbiol 2018; 169:363-371. [PMID: 29577985 DOI: 10.1016/j.resmic.2018.03.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 02/27/2018] [Accepted: 03/01/2018] [Indexed: 12/22/2022]
Abstract
Transporters of the RND superfamily are well-known as the major drug efflux pumps of Gram-negative bacteria. However, they are widespread in organisms ranging from Archaea to Eukaryotes, and perform diverse functions. This review gives a brief overview of these diverse members of the superfamily with emphasis on their structure and functions.
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12
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Sobajima T, Yoshimura SI, Maeda T, Miyata H, Miyoshi E, Harada A. The Rab11-binding protein RELCH/KIAA1468 controls intracellular cholesterol distribution. J Cell Biol 2018. [PMID: 29514919 PMCID: PMC5940305 DOI: 10.1083/jcb.201709123] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Sobajima et al. identify the novel protein RELCH/KIAA1468 as a Rab11-binding protein and show that RELCH/KIAA1468 and Rab11 regulate OSBP-dependent nonvesicular cholesterol transport from recycling endosomes to the trans-Golgi network. Cholesterol, which is endocytosed to the late endosome (LE)/lysosome, is delivered to other organelles through vesicular and nonvesicular transport mechanisms. In this study, we discuss a novel mechanism of cholesterol transport from recycling endosomes (REs) to the trans-Golgi network (TGN) through RELCH/KIAA1468, which is newly identified in this study as a Rab11-GTP– and OSBP-binding protein. After treating cells with 25-hydroxycholesterol to induce OSBP relocation from the cytoplasm to the TGN, REs accumulated around the TGN area, but this accumulation was diminished in RELCH- or OSBP-depleted cells. Cholesterol content in the TGN was decreased in Rab11-, RELCH-, and OSBP-depleted cells and increased in the LE/lysosome. According to in vitro reconstitution experiments, RELCH tethers Rab11-bound RE-like and OSBP-bound TGN-like liposomes and promotes OSBP-dependent cholesterol transfer from RE-like to TGN-like liposomes. These data suggest that RELCH promotes nonvesicular cholesterol transport from REs to the TGN through membrane tethering.
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Affiliation(s)
- Tomoaki Sobajima
- Department of Cell Biology, Graduate School of Medicine, Osaka University, Osaka, Japan.,Department of Molecular Biochemistry and Clinical Investigation, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Shin-Ichiro Yoshimura
- Department of Cell Biology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Tomomi Maeda
- Department of Cell Biology, Graduate School of Medicine, Osaka University, Osaka, Japan.,Department of Molecular Biochemistry and Clinical Investigation, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Haruhiko Miyata
- Department of Experimental Genome Research, Research Institute for Microbial Diseases, Osaka, Japan
| | - Eiji Miyoshi
- Department of Molecular Biochemistry and Clinical Investigation, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Akihiro Harada
- Department of Cell Biology, Graduate School of Medicine, Osaka University, Osaka, Japan
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Wang D, Zhou Y, Li X, Qu X, Deng Y, Wang Z, He C, Zou Y, Jin Y, Liu Y. Mechanisms of pH-Sensitivity and Cellular Internalization of PEOz-b-PLA Micelles with Varied Hydrophilic/Hydrophobic Ratios and Intracellular Trafficking Routes and Fate of the Copolymer. ACS APPLIED MATERIALS & INTERFACES 2017; 9:6916-6930. [PMID: 28186394 DOI: 10.1021/acsami.6b16376] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
pH-responsive polymeric micelles have shown promise for the targeted and intracellular delivery of antitumor agents. The present study aimed to elucidate the possible mechanisms of pH-sensitivity and cellular internalization of PEOz-b-PLA micelles in detail, further unravel the effect of hydrophilic/hydrophobic ratio of the micelles on their cellular internalization, and examine the intracellular trafficking routes and fate of PEOz-b-PLA after internalization of the micelles. The results of variations in the size and Zeta potential of PEOz-b-PLA micelles and cross-sectional area of PEOz-b-PLA molecules with pH values suggested that electrostatic repulsion between PEOz chains resulting from ionization of the tertiary amide groups along PEOz chain at pH lower than its pKa was responsible for pH-sensitivity of PEOz-b-PLA micelles. Furthermore, the studies on internalization of PEOz-b-PLA micelles by MCF-7 cells revealed that the uptake of PEOz-b-PLA micelles was strongly influenced by their structural features, and showed that PEOz-b-PLA micelles with hydrophilic/hydrophobic ratio of 1.7-2.0 exhibited optimal cellular uptake. No evident alteration in cellular uptake of PEOz-b-PLA micelles was detected by flow cytometry upon the existence of EIPA and chlorpromazine. However, the intracellular uptake of the micelles in the presence of MβCD and genistein was effectively inhibited. Hence, the internalization of such micelles by MCF-7 cells appeared to proceed mainly through caveolae/lipid raft-mediated endocytosis without being influenced by their hydrophilic/hydrophobic ratio. Confocal micrographs revealed that late endosomes, mitochondria and endoplasmic reticulum were all involved in the intracellular trafficking of PEOz-b-PLA copolymers following their internalization via endocytosis, and then part of them was excreted from tumor cells to extracellular medium. These findings provided valuable information for developing desired PEOz-b-PLA micelles to improve their therapeutic efficacy and reducing the potential safety risks associated with their intracellular accumulation.
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Affiliation(s)
- Dishi Wang
- Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University , Beijing 100191, China
| | - Yanxia Zhou
- Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University , Beijing 100191, China
| | - Xinru Li
- Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University , Beijing 100191, China
| | - Xiaoyou Qu
- Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University , Beijing 100191, China
| | - Yunqiang Deng
- Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University , Beijing 100191, China
| | - Ziqi Wang
- Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University , Beijing 100191, China
| | - Chuyu He
- Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University , Beijing 100191, China
| | - Yang Zou
- Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University , Beijing 100191, China
| | - Yiguang Jin
- Department of Pharmaceutical Sciences, Beijing Institute of Radiation Medicine , 27 Taiping Road, Beijing 100850, China
| | - Yan Liu
- Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University , Beijing 100191, China
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Niemann-Pick Type C2 Protein Mediates Hepatic Stellate Cells Activation by Regulating Free Cholesterol Accumulation. Int J Mol Sci 2016; 17:ijms17071122. [PMID: 27420058 PMCID: PMC4964497 DOI: 10.3390/ijms17071122] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 06/26/2016] [Accepted: 07/07/2016] [Indexed: 01/18/2023] Open
Abstract
In chronic liver diseases, regardless of their etiology, the development of fibrosis is the first step toward the progression to cirrhosis, portal hypertension, and hepatocellular carcinoma. Hepatic stellate cells (HSCs) are the main profibrogenic cells that promote the pathogenesis of liver fibrosis, and so it is important to identify the molecules that regulate HSCs activation and liver fibrosis. Niemann-Pick type C2 (NPC2) protein plays an important role in the regulation of intracellular cholesterol homeostasis by directly binding with free cholesterol. However, the roles of NPC2 in HSCs activation and liver fibrosis have not been explored in detail. Since a high-cholesterol diet exacerbates liver fibrosis progression in both rodents and humans, we propose that the expression of NPC2 affects free cholesterol metabolism and regulates HSCs activation. In this study, we found that NPC2 is decreased in both thioacetamide- and carbon tetrachloride-induced liver fibrosis tissues. In addition, NPC2 is expressed in quiescent HSCs, but its activation status is down-regulated. Knockdown of NPC2 in HSC-T6 cells resulted in marked increases in transforming growth factor-β1 (TGF-β1)-induced collagen type 1 α1 (Col1a1), α-smooth muscle actin (α-SMA) expression, and Smad2 phosphorylation. In contrast, NPC2 overexpression decreased TGF-β1-induced HSCs activation. We further demonstrated that NPC2 deficiency significantly increased the accumulation of free cholesterol in HSCs, increasing Col1a1 and α-SMA expression and activating Smad2, and leading to sensitization of HSCs to TGF-β1 activation. In contrast, overexpression of NPC2 decreased U18666A-induced free cholesterol accumulation and inhibited the subsequent HSCs activation. In conclusion, our study has demonstrated that NPC2 plays an important role in HSCs activation by regulating the accumulation of free cholesterol. NPC2 overexpression may thus represent a new treatment strategy for liver fibrosis.
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Mazzacuva F, Mills P, Mills K, Camuzeaux S, Gissen P, Nicoli ER, Wassif C, Te Vruchte D, Porter FD, Maekawa M, Mano N, Iida T, Platt F, Clayton PT. Identification of novel bile acids as biomarkers for the early diagnosis of Niemann-Pick C disease. FEBS Lett 2016; 590:1651-62. [PMID: 27139891 PMCID: PMC5089630 DOI: 10.1002/1873-3468.12196] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 04/18/2016] [Indexed: 11/12/2022]
Abstract
This article describes a rapid UPLC-MS/MS method to quantitate novel bile acids in biological fluids and the evaluation of their diagnostic potential in Niemann-Pick C (NPC). Two new compounds, NPCBA1 (3β-hydroxy,7β-N-acetylglucosaminyl-5-cholenoic acid) and NPCBA2 (probably 3β,5α,6β-trihydroxycholanoyl-glycine), were observed to accumulate preferentially in NPC patients: median plasma concentrations of NPCBA1 and NPCBA2 were 40- and 10-fold higher in patients than in controls. However, NPCBA1 concentrations were normal in some patients because they carried a common mutation inactivating the GlcNAc transferase required for the synthesis of this bile acid. NPCBA2, not containing a GlcNAc moiety, is thus a better NPC biomarker.
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Affiliation(s)
- Francesca Mazzacuva
- Centre for Translational Omics, Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Philippa Mills
- Centre for Translational Omics, Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Kevin Mills
- Centre for Translational Omics, Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Stephane Camuzeaux
- Centre for Translational Omics, Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Paul Gissen
- Centre for Translational Omics, Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
- Metabolic Medicine, Great Ormond Street Children's Hospital, London, UK
| | | | - Christopher Wassif
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | - Forbes D Porter
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Masamitsu Maekawa
- Department of Pharmaceutical Sciences, Tohoku University Hospital, Japan
| | - Nariyasu Mano
- Department of Pharmaceutical Sciences, Tohoku University Hospital, Japan
| | - Takashi Iida
- College of Humanities and Sciences, Nihon University, Tokyo, Japan
| | - Frances Platt
- Department of Pharmacology, University of Oxford, UK
| | - Peter T Clayton
- Centre for Translational Omics, Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
- Metabolic Medicine, Great Ormond Street Children's Hospital, London, UK
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16
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Maintenance of Membrane Integrity and Permeability Depends on a Patched-Related Protein in Caenorhabditis elegans. Genetics 2016; 202:1411-20. [PMID: 26857627 DOI: 10.1534/genetics.115.179705] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 02/02/2016] [Indexed: 11/18/2022] Open
Abstract
Membrane integrity is critical for cell survival, defects of which cause pathological symptoms such as metabolic diseases. In this study, we used ethanol sensitivity of the nematode Caenorhabditis elegans to identify genetic factors involved in membrane integrity. InC. elegans, acute exposure to a high concentration (7% v/v) of ethanol changes membrane permeability, as measured by propidium iodide staining, and causes paralysis. We used the timing of complete paralysis as an indicator for alteration of membrane integrity in our genetic screen, and identified ptr-6 as a gene that confers ethanol resistance when mutated. PTR-6 is a patched-related protein and contains a sterol sensing domain. Inhibition of two PTR-encoding genes,ptr-15 and ptr-23, and mboa-1, encoding an Acyl Co-A: cholesterol acyltransferase homolog, restored ethanol sensitivity of the ptr-6 mutant, suggesting that these ptr genes and mboa-1 are involved in the maintenance of membrane integrity and permeability. Our results suggest that C. elegans can be used as a model system to identify factors involved in metabolic diseases and to screen for therapeutic drugs.
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17
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Saher G, Stumpf SK. Cholesterol in myelin biogenesis and hypomyelinating disorders. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1083-94. [PMID: 25724171 DOI: 10.1016/j.bbalip.2015.02.010] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 02/05/2015] [Accepted: 02/12/2015] [Indexed: 02/05/2023]
Abstract
The largest pool of free cholesterol in mammals resides in myelin membranes. Myelin facilitates rapid saltatory impulse propagation by electrical insulation of axons. This function is achieved by ensheathing axons with a tightly compacted stack of membranes. Cholesterol influences myelination at many steps, from the differentiation of myelinating glial cells, over the process of myelin membrane biogenesis, to the functionality of mature myelin. Cholesterol emerged as the only integral myelin component that is essential and rate-limiting for the development of myelin in the central and peripheral nervous system. Moreover, disorders that interfere with sterol synthesis or intracellular trafficking of cholesterol and other lipids cause hypomyelination and neurodegeneration. This review summarizes recent results on the roles of cholesterol in CNS myelin biogenesis in normal development and under different pathological conditions. This article is part of a Special Issue entitled Brain Lipids.
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Affiliation(s)
- Gesine Saher
- Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.
| | - Sina Kristin Stumpf
- Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.
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18
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Platt FM. Sphingolipid lysosomal storage disorders. Nature 2014; 510:68-75. [PMID: 24899306 DOI: 10.1038/nature13476] [Citation(s) in RCA: 226] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/14/2014] [Indexed: 12/18/2022]
Abstract
Lysosomal storage diseases are inborn errors of metabolism, the hallmark of which is the accumulation, or storage, of macromolecules in the late endocytic system. They are monogenic disorders that occur at a collective frequency of 1 in 5,000 live births and are caused by inherited defects in genes that mainly encode lysosomal proteins, most commonly lysosomal enzymes. A subgroup of these diseases involves the lysosomal storage of glycosphingolipids. Through our understanding of the genetics, biochemistry and, more recently, cellular aspects of sphingolipid storage disorders, we have gained insights into fundamental aspects of cell biology that would otherwise have remained opaque. In addition, study of these disorders has led to significant progress in the development of therapies, several of which are now in routine clinical use. Emerging mechanistic links with more common diseases suggest we need to rethink our current concept of disease boundaries.
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Affiliation(s)
- Frances M Platt
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
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19
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Amini-Bavil-Olyaee S, Choi YJ, Lee JH, Shi M, Huang IC, Farzan M, Jung JU. The antiviral effector IFITM3 disrupts intracellular cholesterol homeostasis to block viral entry. Cell Host Microbe 2014; 13:452-64. [PMID: 23601107 PMCID: PMC3646482 DOI: 10.1016/j.chom.2013.03.006] [Citation(s) in RCA: 267] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 12/04/2012] [Accepted: 03/19/2013] [Indexed: 12/21/2022]
Abstract
Vesicle-membrane-protein-associated protein A (VAPA) and oxysterol-binding protein (OSBP) regulate intracellular cholesterol homeostasis, which is required for many virus infections. During entry, viruses or virus-containing vesicles can fuse with endosomal membranes to mediate the cytosolic release of virions, and alterations in endosomal cholesterol can inhibit this invasion step. We show that the antiviral effector protein interferon-inducible transmembrane protein 3 (IFITM3) interacts with VAPA and prevents its association with OSBP, thereby disrupting intracellular cholesterol homeostasis and inhibiting viral entry. By altering VAPA-OSBP function, IFITM3 induces a marked accumulation of cholesterol in multivesicular bodies and late endosomes, which inhibits the fusion of intraluminal virion-containing vesicles with endosomal membranes and thereby blocks virus release into the cytosol. Consequently, ectopic expression or depletion of the VAPA gene profoundly affects IFITM3-mediated inhibition of viral entry. Thus, IFITM3 disrupts intracellular cholesterol homeostasis to block viral entry, further underscoring the importance of cholesterol in virus infection.
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Affiliation(s)
- Samad Amini-Bavil-Olyaee
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Harlyne J. Norris Cancer Research Tower, 1450 Biggy Street, Los Angeles, CA 90033, USA
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20
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Sakai-Kato K, Un K, Nanjo K, Nishiyama N, Kusuhara H, Kataoka K, Kawanishi T, Goda Y, Okuda H. Elucidating the molecular mechanism for the intracellular trafficking and fate of block copolymer micelles and their components. Biomaterials 2014; 35:1347-58. [DOI: 10.1016/j.biomaterials.2013.11.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 11/08/2013] [Indexed: 01/14/2023]
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21
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Swierczynska MM, Lamounier-Zepter V, Bornstein SR, Eaton S. Lipoproteins and Hedgehog signalling--possible implications for the adrenal gland function. Eur J Clin Invest 2013; 43:1178-83. [PMID: 23992253 DOI: 10.1111/eci.12145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 07/27/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND Metabolic syndrome is a common metabolic disorder that is associated with an increased risk of type 2 diabetes and cardiovascular diseases. Disturbances in adrenal steroid hormone production significantly contribute to the development of this disorder. Therefore, it is extremely important to fully understand the mechanisms governing adrenal gland function, both in physiological and pathological conditions. RESULTS Recently, Sonic hedgehog has emerged as an important regulator of adrenal development, with a possible role in adult gland homeostasis. Recent work of our group shows that lipoproteins are important regulators of Hedgehog signaling; they act as carriers for the spread of Hedgehog proteins, but also contain lipid(s) that inhibit the pathway. CONCLUSIONS We propose that lipoproteins may affect Sonic hedgehog signaling in the adult adrenal gland at multiple levels. Understanding the interplay between lipoprotein metabolism and adrenal Hedgehog signaling may improve our understanding of how adrenal gland disorders contribute to the metabolic syndrome.
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Affiliation(s)
- Marta M Swierczynska
- Department of Internal Medicine III, University Hospital Carl Gustav Carus, Dresden, Germany; Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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22
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Discovery of Oxysterol-Derived Pharmacological Chaperones for NPC1: Implication for the Existence of Second Sterol-Binding Site. ACTA ACUST UNITED AC 2013; 20:391-402. [DOI: 10.1016/j.chembiol.2013.02.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 01/12/2013] [Accepted: 02/07/2013] [Indexed: 11/24/2022]
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23
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HDL drug carriers for targeted therapy. Clin Chim Acta 2012; 415:94-100. [PMID: 23063777 DOI: 10.1016/j.cca.2012.10.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Revised: 10/06/2012] [Accepted: 10/07/2012] [Indexed: 01/08/2023]
Abstract
Plasma concentrations of high-density lipoprotein cholesterol (HDL-C) are strongly and inversely associated with cardiovascular risk. HDL is not a simple lipid transporter, but possesses multiple anti-atherosclerosis activities because it contains special proteins, signaling lipid, and microRNAs. Natural or recombinant HDLs have emerged as potential carriers for delivering a drug to a specified target. However, HDL function also depends on enzymes that alter its structure and composition, as well as cellular receptors and membrane micro-domains that facilitate interactions with the microenvironment. In this review, four mechanisms predicted to enhance functions or targeted therapy of HDL in vivo are discussed. The first involves caveolae-mediated recruitment of HDL signal to bind their receptors. The second involves scavenger receptor class B type I (SR-BI) mediating anchoring and fluidity for signal-lipid of HDL. The third involves lecithin-cholesterol acyltransferase (LCAT) concentrating the signaling lipid at the surface of the HDL particle. The fourth involves microRNAs (miRNAs) being delivered in the blood to special targets by HDL. Exploitation of these four mechanisms will promote HDL to carry targeted drugs and increase HDL's clinical value.
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24
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Lieberman AP, Puertollano R, Raben N, Slaugenhaupt S, Walkley SU, Ballabio A. Autophagy in lysosomal storage disorders. Autophagy 2012; 8:719-30. [PMID: 22647656 PMCID: PMC3378416 DOI: 10.4161/auto.19469] [Citation(s) in RCA: 296] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Lysosomes are ubiquitous intracellular organelles that have an acidic internal pH, and play crucial roles in cellular clearance. Numerous functions depend on normal lysosomes, including the turnover of cellular constituents, cholesterol homeostasis, downregulation of surface receptors, inactivation of pathogenic organisms, repair of the plasma membrane and bone remodeling. Lysosomal storage disorders (LSDs) are characterized by progressive accumulation of undigested macromolecules within the cell due to lysosomal dysfunction. As a consequence, many tissues and organ systems are affected, including brain, viscera, bone and cartilage. The progressive nature of phenotype development is one of the hallmarks of LSDs. In recent years biochemical and cell biology studies of LSDs have revealed an ample spectrum of abnormalities in a variety of cellular functions. These include defects in signaling pathways, calcium homeostasis, lipid biosynthesis and degradation and intracellular trafficking. Lysosomes also play a fundamental role in the autophagic pathway by fusing with autophagosomes and digesting their content. Considering the highly integrated function of lysosomes and autophagosomes it was reasonable to expect that lysosomal storage in LSDs would have an impact upon autophagy. The goal of this review is to provide readers with an overview of recent findings that have been obtained through analysis of the autophagic pathway in several types of LSDs, supporting the idea that LSDs could be seen primarily as "autophagy disorders."
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Affiliation(s)
- Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI USA
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25
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Sakai-Kato K, Ishikura K, Oshima Y, Tada M, Suzuki T, Ishii-Watabe A, Yamaguchi T, Nishiyama N, Kataoka K, Kawanishi T, Okuda H. Evaluation of intracellular trafficking and clearance from HeLa cells of doxorubicin-bound block copolymers. Int J Pharm 2011; 423:401-9. [PMID: 22207161 DOI: 10.1016/j.ijpharm.2011.12.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 11/16/2011] [Accepted: 12/15/2011] [Indexed: 11/25/2022]
Abstract
New technologies are needed to deliver medicines safely and effectively. Polymeric nanoparticulate carriers are one such technology under investigation. We examined the intracellular trafficking of doxorubicin-bound block copolymers quantitatively and by imaging doxorubicin-derived fluorescence using confocal microscopy. The polymers were internalized by endocytosis and distributed in endosomal/lysosomal compartments and the endoplasmic reticulum; unlike free doxorubicin, the polymers were not found in the nucleus. Moreover, the ATP-binding cassette protein B1 (ABCB1) transporter may be involved in the efflux of the polymer from cells. This drug delivery system is attractive because the endogenous transport system is used for the uptake and delivery of the artificial drug carrier to the target as well as for its efflux from cells to medium. Our results show that a drug delivery system strategy targeting this endogenous transport pathway may be useful for affecting specific molecular targets.
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Affiliation(s)
- Kumiko Sakai-Kato
- Division of Drugs, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
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26
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Deficiency of a Niemann-Pick, type C1-related protein in toxoplasma is associated with multiple lipidoses and increased pathogenicity. PLoS Pathog 2011; 7:e1002410. [PMID: 22174676 PMCID: PMC3234224 DOI: 10.1371/journal.ppat.1002410] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 10/16/2011] [Indexed: 02/07/2023] Open
Abstract
Several proteins that play key roles in cholesterol synthesis, regulation, trafficking and signaling are united by sharing the phylogenetically conserved 'sterol-sensing domain' (SSD). The intracellular parasite Toxoplasma possesses at least one gene coding for a protein containing the canonical SSD. We investigated the role of this protein to provide information on lipid regulatory mechanisms in the parasite. The protein sequence predicts an uncharacterized Niemann-Pick, type C1-related protein (NPC1) with significant identity to human NPC1, and it contains many residues implicated in human NPC disease. We named this NPC1-related protein, TgNCR1. Mammalian NPC1 localizes to endo-lysosomes and promotes the movement of sterols and sphingolipids across the membranes of these organelles. Miscoding patient mutations in NPC1 cause overloading of these lipids in endo-lysosomes. TgNCR1, however, lacks endosomal targeting signals, and localizes to flattened vesicles beneath the plasma membrane of Toxoplasma. When expressed in mammalian NPC1 mutant cells and properly addressed to endo-lysosomes, TgNCR1 restores cholesterol and GM1 clearance from these organelles. To clarify the role of TgNCR1 in the parasite, we genetically disrupted NCR1; mutant parasites were viable. Quantitative lipidomic analyses on the ΔNCR1 strain reveal normal cholesterol levels but an overaccumulation of several species of cholesteryl esters, sphingomyelins and ceramides. ΔNCR1 parasites are also characterized by abundant storage lipid bodies and long membranous tubules derived from their parasitophorous vacuoles. Interestingly, these mutants can generate multiple daughters per single mother cell at high frequencies, allowing fast replication in vitro, and they are slightly more virulent in mice than the parental strain. These data suggest that the ΔNCR1 strain has lost the ability to control the intracellular levels of several lipids, which subsequently results in the stimulation of lipid storage, membrane biosynthesis and parasite division. Based on these observations, we ascribe a role for TgNCR1 in lipid homeostasis in Toxoplasma.
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27
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Molecular mechanisms of endolysosomal Ca2+ signalling in health and disease. Biochem J 2011; 439:349-74. [PMID: 21992097 DOI: 10.1042/bj20110949] [Citation(s) in RCA: 295] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Endosomes, lysosomes and lysosome-related organelles are emerging as important Ca2+ storage cellular compartments with a central role in intracellular Ca2+ signalling. Endocytosis at the plasma membrane forms endosomal vesicles which mature to late endosomes and culminate in lysosomal biogenesis. During this process, acquisition of different ion channels and transporters progressively changes the endolysosomal luminal ionic environment (e.g. pH and Ca2+) to regulate enzyme activities, membrane fusion/fission and organellar ion fluxes, and defects in these can result in disease. In the present review we focus on the physiology of the inter-related transport mechanisms of Ca2+ and H+ across endolysosomal membranes. In particular, we discuss the role of the Ca2+-mobilizing messenger NAADP (nicotinic acid adenine dinucleotide phosphate) as a major regulator of Ca2+ release from endolysosomes, and the recent discovery of an endolysosomal channel family, the TPCs (two-pore channels), as its principal intracellular targets. Recent molecular studies of endolysosomal Ca2+ physiology and its regulation by NAADP-gated TPCs are providing exciting new insights into the mechanisms of Ca2+-signal initiation that control a wide range of cellular processes and play a role in disease. These developments underscore a new central role for the endolysosomal system in cellular Ca2+ regulation and signalling.
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28
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Mani O, Körner M, Ontsouka CE, Sorensen MT, Sejrsen K, Bruckmaier RM, Albrecht C. Identification of ABCA1 and ABCG1 in milk fat globules and mammary cells--implications for milk cholesterol secretion. J Dairy Sci 2011; 94:1265-76. [PMID: 21338792 DOI: 10.3168/jds.2010-3521] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 11/01/2010] [Indexed: 11/19/2022]
Abstract
The ATP-binding cassette (ABC) transporters ABCA1 and ABCG1 play an important role in cellular cholesterol homeostasis, but their function in mammary gland (MG) tissue remains elusive. A bovine MG model that allows repeated MG sampling in identical animals at different functional stages was used to test whether 1) ABCA1 and ABCG1 protein expression and subcellular localization in mammary epithelial cells (MEC) change during the pregnancy-lactation cycle, and 2) these 2 proteins were present in milk fat globules (MFG). Expression and localization in MEC were investigated in bovine MG tissues at the end of lactation, during the dry period (DP), and early lactation using immunohistochemical and immunofluorescence approaches. The presence of ABCA1 and ABCG1 in MFG isolated from fresh milk was determined by immunofluorescence. The ABCA1 protein expression in MEC, expressed as arbitrary units, was higher during the end of lactation (12.2±0.24) and the DP (12.5±0.22) as compared with during early lactation (10.2±0.65). In contrast, no significant change in ABCG1 expression existed between the stages. Throughout the cycle, ABCA1 and ABCG1 were detected in the apical (41.9±24.8 and 49.0±4.96% of cows, respectively), basal (56.2±28.1 and 54.6±7.78% of cows, respectively), or entire cytoplasm (56.8±13.4 and 61.6±14.4% of cows, respectively) of MEC, or showed combined localization. Unlike ABCG1, ABCA1 was absent at the apical aspect of MEC during early lactation. Immunolabeling experiments revealed the presence of ABCA1 and ABCG1 in MFG membranes. Findings suggest a differential, functional stage-dependent role of ABCA1 and ABCG1 in cholesterol homeostasis of the MG epithelium. The presence of ABCA1 and ABCG1 in MFG membranes suggests that these proteins are involved in cholesterol exchange between MEC and alveolar milk.
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Affiliation(s)
- O Mani
- Institute of Biochemistry and Molecular Medicine, University of Bern, CH-3012 Bern, Switzerland
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Jelinek D, Millward V, Birdi A, Trouard TP, Heidenreich RA, Garver WS. Npc1 haploinsufficiency promotes weight gain and metabolic features associated with insulin resistance. Hum Mol Genet 2010; 20:312-21. [PMID: 21036943 DOI: 10.1093/hmg/ddq466] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A recent population-based genome-wide association study has revealed that the Niemann-Pick C1 (NPC1) gene is associated with early-onset and morbid adult obesity. Concurrently, our candidate gene-based mouse growth study performed using the BALB/cJ NPC1 mouse model (Npc1) with decreased Npc1 gene dosage independently supported these results by suggesting an Npc1 gene-diet interaction in relation to early-onset weight gain. To further investigate the Npc1 gene in relation to weight gain and metabolic features associated with insulin resistance, we interbred BALB/cJ Npc1(+/-) mice with wild-type C57BL/6J mice, the latter mouse strain commonly used to study aspects of diet-induced obesity and insulin resistance. This breeding produced a hybrid (BALB/cJ-C57BL/6J) Npc1(+/-) mouse model with increased susceptibility to weight gain and insulin resistance. The results from our study indicated that these Npc1(+/-) mice were susceptible to increased weight gain characterized by increased whole body and abdominal adiposity, adipocyte hypertrophy and hepatic steatosis in the absence of hyperphagia. Moreover, these Npc1(+/-) mice developed abnormal metabolic features characterized by impaired fasting glucose, glucose intolerance, hyperinsulinemia, hyperleptinemia and dyslipidemia marked by an increased concentration of cholesterol and triacylglycerol associated with low-density lipoprotein and high-density lipoprotein. The overall results are consistent with a unique Npc1 gene-diet interaction that promotes both weight gain and metabolic features associated with insulin resistance. Therefore, the NPC1 gene now represents a previously unrecognized gene involved in maintaining energy and metabolic homeostasis that will contribute to our understanding concerning the current global epidemic of obesity and type 2 diabetes mellitus.
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Affiliation(s)
- David Jelinek
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, 1 University of New Mexico, Albuquerque, NM, USA
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Spiroimidazolidinone NPC1L1 inhibitors. Part 2: structure-activity studies and in vivo efficacy. Bioorg Med Chem Lett 2010; 20:6929-32. [PMID: 21030254 DOI: 10.1016/j.bmcl.2010.09.138] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 09/27/2010] [Accepted: 09/28/2010] [Indexed: 11/23/2022]
Abstract
Ezetimibe (Zetia®), a cholesterol-absorption inhibitor (CAI) approved by the FDA for the treatment of hypercholesterolemia, is believed to target the intestine protein Niemann-Pick C1-Like 1 (NPC1L1) or its pathway. A spiroimidazolidinone NPC1L1 inhibitor identified by virtual screening showed moderate binding activity but was not efficacious in an in vivo rodent model of cholesterol absorption. Synthesis of analogs established the structure-activity relationships for binding activity, and resulted in compounds with in vivo efficacy, including 24, which inhibited plasma cholesterol absorption by 67% in the mouse, thereby providing proof-of-concept that non-β-lactams can be effective CAIs.
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Liao PL, Cheng YW, Li CH, Wang YT, Kang JJ. 7-Ketocholesterol and cholesterol-5α,6α-epoxide induce smooth muscle cell migration and proliferation through the epidermal growth factor receptor/phosphoinositide 3-kinase/Akt signaling pathways. Toxicol Lett 2010; 197:88-96. [DOI: 10.1016/j.toxlet.2010.05.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 04/10/2010] [Accepted: 05/04/2010] [Indexed: 12/28/2022]
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Abstract
Gemfibrozil is long known for its ability to reduce the level of triglycerides in the blood circulation and to decrease the risk of hyperlipidemia. However, a number of recent studies reveal that apart from its lipid-lowering effects, gemfibrozil can also regulate many other signaling pathways responsible for inflammation, switching of T-helper cells, cell-to-cell contact, migration, and oxidative stress. In this review, we have made an honest attempt to analyze various biological activities of gemfibrozil and associated mechanisms that may help to consider this drug for different human disorders as primary or adjunct therapy.
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Affiliation(s)
- Avik Roy
- Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois 60612, USA
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33
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Adibhatla RM, Hatcher JF. Lipid oxidation and peroxidation in CNS health and disease: from molecular mechanisms to therapeutic opportunities. Antioxid Redox Signal 2010; 12:125-69. [PMID: 19624272 DOI: 10.1089/ars.2009.2668] [Citation(s) in RCA: 317] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Reactive oxygen species (ROS) are produced at low levels in mammalian cells by various metabolic processes, such as oxidative phosphorylation by the mitochondrial respiratory chain, NAD(P)H oxidases, and arachidonic acid oxidative metabolism. To maintain physiological redox balance, cells have endogenous antioxidant defenses regulated at the transcriptional level by Nrf2/ARE. Oxidative stress results when ROS production exceeds the cell's ability to detoxify ROS. Overproduction of ROS damages cellular components, including lipids, leading to decline in physiological function and cell death. Reaction of ROS with lipids produces oxidized phospholipids, which give rise to 4-hydroxynonenal, 4-oxo-2-nonenal, and acrolein. The brain is susceptible to oxidative damage due to its high lipid content and oxygen consumption. Neurodegenerative diseases (AD, ALS, bipolar disorder, epilepsy, Friedreich's ataxia, HD, MS, NBIA, NPC, PD, peroxisomal disorders, schizophrenia, Wallerian degeneration, Zellweger syndrome) and CNS traumas (stroke, TBI, SCI) are problems of vast clinical importance. Free iron can react with H(2)O(2) via the Fenton reaction, a primary cause of lipid peroxidation, and may be of particular importance for these CNS injuries and disorders. Cholesterol is an important regulator of lipid organization and the precursor for neurosteroid biosynthesis. Atherosclerosis, the major risk factor for ischemic stroke, involves accumulation of oxidized LDL in the arteries, leading to foam cell formation and plaque development. This review will discuss the role of lipid oxidation/peroxidation in various CNS injuries/disorders.
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Affiliation(s)
- Rao Muralikrishna Adibhatla
- Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792-3232, USA.
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34
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Abstract
Abstract
The tripartite efflux system AcrA/AcrB/TolC is the main pump in Escherichia coli for the efflux of multiple antibiotics, dyes, bile salts and detergents. The inner membrane component AcrB is central to substrate recognition and energy transduction and acts as a proton/drug antiporter. Recent structural studies show that homotrimeric AcrB can adopt different monomer conformations representing consecutive states in an allosteric functional rotation transport cycle. The conformational changes create an alternate access drug transport tunnel including a hydrophobic substrate binding pocket in one of the cycle intermediates.
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35
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Pacheco CD, Elrick MJ, Lieberman AP. Tau deletion exacerbates the phenotype of Niemann-Pick type C mice and implicates autophagy in pathogenesis. Hum Mol Genet 2008; 18:956-65. [PMID: 19074461 DOI: 10.1093/hmg/ddn423] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Hyperphosphorylation and aggregation of the microtubule-binding protein tau characterize a diverse array of neurodegenerative disorders. Most of these lack mutations in the encoding MAPT gene, and the role of tau in disease pathogenesis remains controversial. Among these tauopathies is Niemann-Pick type C disease (NPC), a lysosomal storage disorder characterized by progressive neurodegeneration and premature death, most often caused by an inherited deficiency in the intracellular lipid trafficking protein NPC1. To determine the extent to which tau affects NPC pathogenesis, we generated Npc1-/- mice deficient in tau. Unexpectedly, NPC1/tau double null mutants are generated in markedly smaller litters, exhibit an enhanced systemic phenotype and die significantly earlier than NPC1 single null mutants. As autophagy is up-regulated in NPC and protein degradation through this pathway depends on movement along microtubules, we knocked down MAPT expression in NPC1-deficient human fibroblasts and examined effects on this pathway. We show that an acute reduction of tau expression in a cellular model of NPC decreases induction and flux through the autophagic pathway. Our data establish that MAPT deletion exacerbates the NPC phenotype through a mechanism independent of tau protein aggregation and identifies a critical role for tau in the regulation of autophagy in NPC1-deficient cells.
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Affiliation(s)
- Chris D Pacheco
- Neuroscience Program, The University of Michigan Medical School, 3510 MSRB1, 1150 W. Medical Center Dr, Ann Arbor, MI 48109, USA
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Lipid homeostasis in macrophages – Implications for atherosclerosis. REVIEWS OF PHYSIOLOGY BIOCHEMISTRY AND PHARMACOLOGY 2008; 160:93-125. [DOI: 10.1007/112_2008_802] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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37
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Pacheco CD, Kunkel R, Lieberman AP. Autophagy in Niemann-Pick C disease is dependent upon Beclin-1 and responsive to lipid trafficking defects. Hum Mol Genet 2007; 16:1495-503. [PMID: 17468177 DOI: 10.1093/hmg/ddm100] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Niemann-Pick C (NPC) disease is an autosomal recessive lipid storage disorder characterized by a disruption of sphingolipid and cholesterol trafficking that produces cognitive impairment, ataxia and death, often in childhood. Most cases are caused by loss of function mutations in the Npc1 gene, which encodes a protein that localizes to late endosomes and functions in lipid sorting and vesicle trafficking. Here, we demonstrate that NPC1-deficient primary human fibroblasts, like npc1(-/-) mice fibroblasts, showed increased autophagy as evidenced by elevated LC3-II levels, numerous autophagic vacuoles and enhanced degradation of long-lived proteins. Autophagy because of NPC1 deficiency was associated with increased expression of Beclin-1 rather than activation of the Akt-mTOR-p70 S6K signaling pathway, and siRNA knockdown of Beclin-1 decreased long-lived protein degradation. Induction of cholesterol trafficking defects in wild-type fibroblasts by treatment with U18666A increased Beclin-1 and LC3-II expression, whereas treatment of NPC1-deficient fibroblasts with sphingolipid-lowering compound NB-DGJ failed to alter the expression of either Beclin-1 or LC3-II. Primary fibroblasts from patients with two other sphingolipid storage diseases, NPC2 deficiency and Sandhoff disease, characterized by sphingolipid trafficking defects also showed elevation in Beclin-1 and LC3-II levels. In contrast, Gaucher disease fibroblasts, which traffic sphingolipids normally, showed wild-type levels of Beclin-1 and LC3-II. Our data define a critical role for Beclin-1 in the activation of autophagy because of NPC1 deficiency, and reveal an unexpected role for lipid trafficking in the regulation of this pathway in patients with several sphingolipid storage diseases.
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Affiliation(s)
- Chris D Pacheco
- Neuroscience Program, The University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Sillence DJ. New insights into glycosphingolipid functions--storage, lipid rafts, and translocators. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 262:151-89. [PMID: 17631188 DOI: 10.1016/s0074-7696(07)62003-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glycosphingolipids are key components of eukaryotic cellular membranes. Through their propensity to form lipid rafts, they are important in membrane transport and signaling. At the cell surface, they are required for caveolar-mediated endocytosis, a process required for the action of many glycosphingolipid-binding toxins. Glycosphingolipids also exist intracellularly, on both leaflets of organelle membranes. It is expected that dissecting the mechanisms of cell pathology seen in the glycosphingolipid storage diseases, where lysosomal glycosphingolipid degradation is defective, will reveal their functions. Disrupted cation gradients in Mucolipidosis type IV disease are interlinked with glycosphingolipid storage, defective rab 7 function, and the activation of autophagy. Relationships between drug translocators and glycosphingolipid synthesis are also discussed. Mass spectrometry of cell lines defective in drug transporters reveal clear differences in glycosphingolipid mass and fatty acid composition. The potential roles of glycosphingolipids in lipid raft formation, endocytosis, and cationic gradients are discussed.
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Affiliation(s)
- Dan J Sillence
- Leicester School of Pharmacy, Hawthorne Building, De Montfort University, Leicester, LE1 9BH, United Kingdom
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39
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Walkley SU. Lysosomal Disorders of the Nervous System. Neurobiol Dis 2007. [DOI: 10.1016/b978-012088592-3/50003-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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40
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Liou HL, Dixit SS, Xu S, Tint GS, Stock AM, Lobel P. NPC2, the Protein Deficient in Niemann-Pick C2 Disease, Consists of Multiple Glycoforms That Bind a Variety of Sterols. J Biol Chem 2006; 281:36710-23. [PMID: 17018531 DOI: 10.1074/jbc.m608743200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Niemann-Pick C disease is a fatal neurodegenerative disorder characterized by an endolysosomal accumulation of cholesterol and other lipids. One form of the disease is caused by a deficiency in NPC2, a soluble lysosomal glycoprotein that binds cholesterol. To better understand the biological function of NPC2 and how its deficiency results in disease, we have characterized the structural and functional properties of recombinant human protein. Highly purified NPC2 consists of a complex mixture of glycosylated isoforms, similar to that observed in human brain autopsy specimens. Mass spectrometric analysis revealed that of the three potential N-linked glycosylation sites present in the mature protein, Asn-19 is not utilized; Asn-39 is linked to an endoglycosidase H (Endo H)-sensitive oligosaccharide, and Asn-116 is variably utilized, either being unmodified or linked to Endo H-sensitive or Endo H-resistant oligosaccharides. All glycoforms are endocytosed and ameliorate the cholesterol storage phenotype of NPC2-deficient fibroblasts. In addition, the purified preparation contains a mixture of both free and lipid-bound protein. All glycoforms bind cholesterol, and sterol binding to NPC2 significantly alters its behavior upon cation-exchange chromatography. Based on this observation, we developed chromatography-based binding assays and determined that NPC2 forms an equimolar complex with the fluorescent cholesterol analog dehydroergosterol. In addition, we find that NPC2 binds a range of cholesterol-related molecules (cholesterol precursors, plant sterols, some oxysterols, cholesterol sulfate, cholesterol acetate, and 5-alpha-cholestan-3-one) and that 27-hydroxysterol accumulates in NPC2-deficient mouse liver. Binding was not detected for various glycolipids, phospholipids, or fatty acids. These biochemical properties support a direct and specialized function of NPC2 in lysosomal sterol transport.
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Affiliation(s)
- Heng-Ling Liou
- Center for Advanced Biotechnology and Medicine, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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41
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Rottiers V, Motola DL, Gerisch B, Cummins CL, Nishiwaki K, Mangelsdorf DJ, Antebi A. Hormonal Control of C. elegans Dauer Formation and Life Span by a Rieske-like Oxygenase. Dev Cell 2006; 10:473-82. [PMID: 16563875 DOI: 10.1016/j.devcel.2006.02.008] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Revised: 01/30/2006] [Accepted: 02/02/2006] [Indexed: 10/24/2022]
Abstract
C. elegans diapause, gonadal outgrowth, and life span are regulated by a lipophilic hormone, which serves as a ligand to the nuclear hormone receptor DAF-12. A key step in hormone production is catalyzed by the CYP450 DAF-9, but the extent of the biosynthetic pathway is unknown. Here, we identify a conserved Rieske-like oxygenase, DAF-36, as a component in hormone metabolism. Mutants display larval developmental and adult aging phenotypes, as well as patterns of epistasis similar to that of daf-9. Larval phenotypes are potently reversed by crude lipid extracts, 7-dehydrocholesterol, and a recently identified DAF-12 sterol ligand, suggesting that DAF-36 works early in the hormone biosynthetic pathway. DAF-36 is expressed primarily within the intestine, a major organ of metabolic and endocrine control, distinct from DAF-9. These results imply that C. elegans hormone production has multiple steps and is distributed, and that it may provide one way that tissues register their current physiological state during organismal commitments.
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Affiliation(s)
- Veerle Rottiers
- Huffington Center on Aging, Department of Molecular and Cellular Biology, Baylor College of Medicine, Room M320, One Baylor Plaza, Houston, Texas 77030, USA
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42
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Klein A, Amigo L, Retamal MJ, Morales MG, Miquel JF, Rigotti A, Zanlungo S. NPC2 is expressed in human and murine liver and secreted into bile: potential implications for body cholesterol homeostasis. Hepatology 2006; 43:126-33. [PMID: 16374838 DOI: 10.1002/hep.20985] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
The liver plays a critical role in the metabolism of lipoprotein cholesterol and in controlling its elimination through the bile. Niemann-Pick type C 2 (NPC2), a cholesterol-binding protein, is key for normal intracellular trafficking of lipoprotein cholesterol, allowing its exit from the endolysosomal pathway into the metabolically active pool of the cell. In addition, NPC2 is a secretory protein from astrocytes and epididymal cells. Although NPC2 mRNA is detected in the liver, plasma and biliary NPC2 protein levels and function have not been reported. This study demonstrates that NPC2 is present in murine and human plasma and bile. In addition, hepatic NPC2 protein expression was dramatically increased in NPC1-deficient mice but not regulated by cholesterol feeding or pharmacological modulation of various nuclear receptors involved in cholesterol and bile acid metabolism. Interestingly, biliary NPC2 levels were 3-fold increased in gallstone-susceptible C57BL6/J versus gallstone-resistant BALB/c mice. Furthermore, NPC2 was exclusively found in the cholesterol pro-nucleating ConA-binding fraction of human bile. In conclusion, NPC2 is secreted from the liver into bile and plasma, where it may have a functional role in cholesterol transport in normal and disease conditions.
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Affiliation(s)
- Andrés Klein
- Departamento de Gastroenterología, Facultad de Medicina, Pontificia Universidad Católica, Santiago, Chile
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43
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Saccharomyces cerevisiae, a model to study sterol uptake and transport in eukaryotes. Biochem Soc Trans 2005. [DOI: 10.1042/bst0331186] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The molecular mechanisms that govern intracellular transport of sterols in eukaryotic cells are only poorly understood. Saccharomyces cerevisiae is a facultative anaerobic organism that requires supplementation with unsaturated fatty acids and sterols to grow in the absence of oxygen, as the synthesis of these lipids requires molecular oxygen. The fact that yeast grows well under anaerobic conditions indicates that lipid uptake is rapid and efficient. To identify components in this lipid uptake and transport pathway, we screened the yeast mutant collection for genes that are essential under anaerobic conditions. Out of the approx. 4800 non-essential genes represented in the mutant collection, 37 were required for growth under anaerobic conditions. Uptake assays using radiolabelled cholesterol revealed that 16 of these genes are required for cholesterol uptake/transport and esterification. Further characterization of the precise role of these genes is likely to advance our understanding of this elusive pathway in yeast and may prove to be relevant to understand sterol homoeostasis in higher eukaryotic cells.
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44
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Ioannou YA. Guilty until proven innocent: the case of NPC1 and cholesterol. Trends Biochem Sci 2005; 30:498-505. [PMID: 16054367 DOI: 10.1016/j.tibs.2005.07.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Revised: 06/30/2005] [Accepted: 07/20/2005] [Indexed: 11/16/2022]
Abstract
Cholesterol accumulation in the endosomes and lysosomes of Niemann-Pick C (NPC) cells is considered to be the hallmark of this disorder, so the main focus of NPC research has revolved around cholesterol and its role in disease pathogenesis. However, recent data indicate that cholesterol is not the primary culprit in this human lipidosis. I propose a new hypothesis for the potential action or function of the NPC1 protein in the endosome. In this context, the relationship of NPC2 and NPC1 is also discussed.
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Affiliation(s)
- Yiannis A Ioannou
- Department of Human Genetics, The Mount Sinai School of Medicine, New York, NY 10029, USA.
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45
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Chao WT, Tsai SH, Lin YC, Lin WW, Yang VC. Cellular localization and interaction of ABCA1 and caveolin-1 in aortic endothelial cells after HDL incubation. Biochem Biophys Res Commun 2005; 332:743-9. [PMID: 15907796 DOI: 10.1016/j.bbrc.2005.05.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Accepted: 05/02/2005] [Indexed: 01/27/2023]
Abstract
The goal of this study was to investigate the cellular localization and the interaction between caveolin-1 and ABCA1 in cholesterol-loaded aortic endothelial cells after HDL incubation. Immunofluorescence confocal microscopy showed that ABCA1 was found primarily on the cell surface, whereas caveolin-1 was revealed on the cell surface and in the cytoplasm. The HDL appeared to colocalize with ABCA1 and caveolin-1 on the cell surface. No free HDL was revealed in the cytoplasm. The HDL was colocalized neither with early endosome marker (CD71) nor with late endosome marker (LAMP2). The chemical cross-linking and immunoprecipitation analysis revealed that ABCA1 binds directly to both HDL and caveolin-1, whereas HDL does not bind directly to caveolin-1. The studies provide evidence for a direct interaction between ABCA1 and HDL, ABCA1 and caveolin-1, but not HDL and caveolin-1, indicating that ABCA1 may act as a structural platform between HDL and caveolin-1 on the cell surface during cellular cholesterol efflux.
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MESH Headings
- ATP Binding Cassette Transporter 1
- ATP-Binding Cassette Transporters/metabolism
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Biological Transport, Active
- Caveolin 1
- Caveolins/metabolism
- Cell Membrane/metabolism
- Cells, Cultured
- Cholesterol/metabolism
- Endosomes/metabolism
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Lipoproteins, HDL/metabolism
- Lipoproteins, HDL/pharmacology
- Models, Biological
- Protein Binding
- Rats
- Subcellular Fractions/metabolism
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Affiliation(s)
- Wei-Ting Chao
- Department of Life Science, Life Science Research Center, Tunghai University, Taichung, Taiwan, ROC
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46
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Garcia-Calvo M, Lisnock J, Bull HG, Hawes BE, Burnett DA, Braun MP, Crona JH, Davis HR, Dean DC, Detmers PA, Graziano MP, Hughes M, Macintyre DE, Ogawa A, O'neill KA, Iyer SPN, Shevell DE, Smith MM, Tang YS, Makarewicz AM, Ujjainwalla F, Altmann SW, Chapman KT, Thornberry NA. The target of ezetimibe is Niemann-Pick C1-Like 1 (NPC1L1). Proc Natl Acad Sci U S A 2005; 102:8132-7. [PMID: 15928087 PMCID: PMC1149415 DOI: 10.1073/pnas.0500269102] [Citation(s) in RCA: 557] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Ezetimibe is a potent inhibitor of cholesterol absorption that has been approved for the treatment of hypercholesterolemia, but its molecular target has been elusive. Using a genetic approach, we recently identified Niemann-Pick C1-Like 1 (NPC1L1) as a critical mediator of cholesterol absorption and an essential component of the ezetimibe-sensitive pathway. To determine whether NPC1L1 is the direct molecular target of ezetimibe, we have developed a binding assay and shown that labeled ezetimibe glucuronide binds specifically to a single site in brush border membranes and to human embryonic kidney 293 cells expressing NPC1L1. Moreover, the binding affinities of ezetimibe and several key analogs to recombinant NPC1L1 are virtually identical to those observed for native enterocyte membranes. KD values of ezetimibe glucuronide for mouse, rat, rhesus monkey, and human NPC1L1 are 12,000, 540, 40, and 220 nM, respectively. Last, ezetimibe no longer binds to membranes from NPC1L1 knockout mice. These results unequivocally establish NPC1L1 as the direct target of ezetimibe and should facilitate efforts to identify the molecular mechanism of cholesterol transport.
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Abstract
Signalling by secreted Hedgehog (Hh) proteins is important for the development of many tissues and organs. Damage to components of the Hh signal-transduction pathway can lead to birth defects and cancer. The Hh proteins are distributed in tissues in a gradient, and cells respond to different thresholds of Hh with distinct responses. The cellular machinery that is responsible for the unique molecular mechanisms of Hh signal transduction has been largely conserved during metazoan evolution.
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Affiliation(s)
- Joan E Hooper
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, 12801 East 17th Avenue, Box 8018, Aurora, Colorado 80045, USA.
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48
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Higaki K, Almanzar-Paramio D, Sturley SL. Metazoan and microbial models of Niemann-Pick Type C disease. Biochim Biophys Acta Mol Cell Biol Lipids 2004; 1685:38-47. [PMID: 15465425 DOI: 10.1016/j.bbalip.2004.08.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Niemann-Pick Type C (NP-C) disease compellingly provides insight into lipid transport and the association of this process with severe neuronal dysfunction. The two genes that define this syndrome, NPC1 and NPC2, are conserved throughout much of eukaryotic evolution, to the extent that the yeast and mammalian NPC1 genes are functionally interchangeable. We present here an evolutionary perspective of the genes defective in NP-C disease. We will describe how conservation of sequences and their biological roles in a variety of microbial and metazoan model systems may act as roadmaps to understanding this syndrome in humans.
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Affiliation(s)
- Katsumi Higaki
- The Institute of Human Nutrition, Columbia University College of Physicians and Surgeons, 630 W168th St. New York, NY 10032, USA
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49
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Abstract
Somatic cell hydridization and linkage studies indicated the implication of a second gene as a cause of Niemann-Pick C disease in a minority (5%) of patients. A study of the lysosomal proteome led to the identification of a previously known gene, HE1, as the NPC2 gene. The mature NPC2/HE1 protein is a ubiquitous soluble small 132-amino-acid glycoprotein, first characterized as a major secretory protein in the human epididymis, but also detected in most tissues. Seventeen families with mutations in the NPC2 gene are known. Good genotype-phenotype correlations were observed. No distinction can be made between the biochemical phenotypes of NPC1 or NPC2 mutants. The NPC2 protein binds cholesterol with submicromolar affinity at neutral and acidic pH. The bovine protein has been crystallized, and the cholesterol-binding site assigned to a hydrophobic loosely packed region. There is strong evidence that the NPC1 and NPC2 proteins must function in a closely related fashion. Current data have led to the hypothesis that NPC2 would bind cholesterol from internal lysosomal membranes, enabling a physical interaction with NPC1 (or another protein) and allowing postlysosomal export of cholesterol. In this model, the activity of NPC1 would depend on that of NPC2. The precise function of the NPC2 protein has, however, not been fully elucidated.
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Affiliation(s)
- Marie T Vanier
- INSERM Unit 189, Lyon-Sud Medical School and Fondation Gillet-Mérieux, Lyon-Sud University Hospital, 69495- Pierre-Bénite Cedex, France.
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Rong JX, Kusunoki J, Oelkers P, Sturley SL, Fisher EA. Acyl-coenzymeA (CoA):cholesterol acyltransferase inhibition in rat and human aortic smooth muscle cells is nontoxic and retards foam cell formation. Arterioscler Thromb Vasc Biol 2004; 25:122-7. [PMID: 15499046 DOI: 10.1161/01.atv.0000148202.49842.3b] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Studies in vitro and in vivo of macrophage foam cells have shown evidence of cytotoxicity after acyl-CoA:cholesterol acyltransferase (ACAT) inhibition. Foam cells of smooth muscle origin are also found in human and animal atherosclerotic lesions. METHODS AND RESULTS To study whether cytotoxicity from ACAT inhibition is independent of cell type, we first established a protocol to conveniently induce aortic smooth muscle foam cell formation using cholesterol-cyclodextrin complexes (CCC). Rat aortic smooth muscle cells (ASMCs) treated for 48 hours with CCC (20 microg/mL) became foam cells by morphological (oil-red-O staining) and biochemical (approximately 1200% and approximately 180% increase in cellular esterified and free cholesterol, respectively) criteria. ACAT activity increased 500% (P<0.01 versus untreated). Similar results were obtained in human ASMC, but ACAT activity increased to an even greater extent (3200%; P<0.01 versus untreated). Western blots indicated that CCC treatment increased human (to 380+/-20% of untreated, P<0.001), but not rat, ACAT protein expression. ACAT inhibition by Fujirebio compound F1394 suppressed CCC-induced foam cell formation in rat and human ASMC, but, notably, did not induce significant cytotoxicity. CONCLUSIONS ASMC might be more resistant to FC-induced adverse effects than are macrophages.
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Affiliation(s)
- James X Rong
- Marc and Ruti Bell Vascular Biology Research Program of the Leon H. Charney Division of Cardiology, Department of Medicine, New York, NY 10016, USA
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