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Existence and distribution of Niemann-Pick type 2C (NPC2) in prawn reproductive tract and its putative role as a cholesterol modulator during sperm transit in the vas deferens. Cell Tissue Res 2020; 382:381-390. [PMID: 32556727 DOI: 10.1007/s00441-020-03225-6] [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: 01/03/2020] [Accepted: 04/27/2020] [Indexed: 10/24/2022]
Abstract
Sequestering of cholesterol (CHO) is a hallmark molecular event that is known to be associated with sperm gaining their fertilizing ability in a broad array of animals. We have shown previously that the level of CHO declines in the Macrobrachium rosenbergii sperm membrane when they are migrating into the vas deferens, prompting us to search for CHO transporters, one of which is Niemann-Pick type 2C (NPC2), within the prawn male reproductive tract. Sequence comparison of MrNPC2 with other NPC2, from crustaceans to mammals, revealed its conserved features in the hydrophobic cavity with 3 amino acids forming a CHO lid that is identical in all species analyzed. Expressions of MrNPC2 transcript and protein were detected in testicular supporting and interstitial cells and along the epithelial cells of the vas deferens. As confirmed by live cell staining, the testicular sperm (Tsp) surface was devoid of MrNPC2 but it first existed on the vas deferens sperm, suggesting its acquisition from the luminal fluid, possibly through trafficking of multi-lamellar vesicles during sperm transit in the vas deferens. We further showed that recombinant MrNPC2 had a high affinity towards CHO in the lipid extracts, either from Tsp or from lipid vesicles in the vas deferens. Together, our results indicated the presence of MrNPC2 in the male reproductive tract, which may play an important role as a CHO modulator between the sperm membrane and vas deferens epithelial communication.
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2
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The characteristics and biological significance of NPC2: Mutation and disease. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2019; 782:108284. [PMID: 31843136 DOI: 10.1016/j.mrrev.2019.108284] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 05/10/2019] [Accepted: 07/05/2019] [Indexed: 12/12/2022]
Abstract
Niemann-Pick C disease (NPC) is a rare autosomal recessive disorder characterized by severe neurodegeneration of central nervous system. Linkage studies in multiplex NPC families and genetic complementation research revealed two disease genes, NPC1 and NPC2, both of which are important transporters for cholesterol trafficking. NPC2 executes cholesterol-transport function through protein-protein interaction with NPC1 as well as through protein-membrane interaction directly with membrane of late endosome and lysosome. In addition, NPC2 may play many other roles as indicated by its widely expressing pattern in different cells and presenting in numerous secretory fluids, although it biological significance is less studied today. About 50 clinical cases have been reported documenting over twenty different mutations of NPC2 in NPC patients so far. In this review, we will mainly summarize the molecular characteristics and biological significance of NPC2, highlighting its vital roles in NPC disease.
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3
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Do GWAS and studies of heterozygotes for NPC1 and/or NPC2 explain why NPC disease cases are so rare? J Appl Genet 2018; 59:441-447. [PMID: 30209687 DOI: 10.1007/s13353-018-0465-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/31/2018] [Accepted: 09/04/2018] [Indexed: 12/15/2022]
Abstract
Early onset Niemann-Pick C diseases are extremely rare, especially Niemann-Pick C2. Perhaps unusually for autosomal recessive diseases, heterozygotes for mutations in NPC1 manifest many biological variations. NPC2 deficiency has large effects on fertility. These features of NPC1 and NPC2 are reviewed in regard to possible negative selection for heterozygotes carrying null and hypomorphic alleles.
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4
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Berzina Z, Solanko LM, Mehadi AS, Jensen MLV, Lund FW, Modzel M, Szomek M, Solanko KA, Dupont A, Nielsen GK, Heegaard CW, Ejsing CS, Wüstner D. Niemann-Pick C2 protein regulates sterol transport between plasma membrane and late endosomes in human fibroblasts. Chem Phys Lipids 2018; 213:48-61. [PMID: 29580834 DOI: 10.1016/j.chemphyslip.2018.03.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/13/2018] [Accepted: 03/15/2018] [Indexed: 11/28/2022]
Abstract
Niemann-Pick disease type C2 is a lipid storage disorder in which mutations in the NPC2 protein cause accumulation of lipoprotein-derived cholesterol in late endosomes and lysosomes (LE/LYSs). Whether cholesterol delivered by other means to NPC2 deficient cells also accumulates in LE/LYSs is currently unknown. We show that the close cholesterol analog dehydroergosterol (DHE), when delivered to the plasma membrane (PM) accumulates in LE/LYSs of human fibroblasts lacking functional NPC2. We measured two different time scales of sterol diffusion; while DHE rich LE/LYSs moved by slow anomalous diffusion in disease cells (D ∼ 4.6∙10-4 μm2/sec; α∼0.76), a small pool of sterol could exchange rapidly with D ∼ 3 μm2/s between LE/LYSs, as shown by fluorescence recovery after photobleaching (FRAP). By quantitative lipid mass spectrometry we found that esterification of 13C-labeled cholesterol but not of DHE is reduced 10-fold in disease fibroblasts compared to control cells. Internalized NPC2 rescued the sterol storage phenotype and strongly expanded the dynamic sterol pool seen in FRAP experiments. Together, our study shows that cholesterol esterification and trafficking of sterols between the PM and LE/LYSs depends on a functional NPC2 protein. NPC2 likely acts inside LE/LYSs from where it increases non-vesicular sterol exchange with other organelles.
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Affiliation(s)
- Zane Berzina
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Lukasz M Solanko
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark; Orphazyme ApS, Ole Maales Vej 3, 2200 Copenhagen N, Denmark
| | - Ahmed S Mehadi
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Maria Louise V Jensen
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Frederik W Lund
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Maciej Modzel
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Maria Szomek
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Katarzyna A Solanko
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Alice Dupont
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Gitte Krogh Nielsen
- Department of Molecular Biology and Genetics, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Christian W Heegaard
- Department of Molecular Biology and Genetics, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Christer S Ejsing
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, DK-5230 Odense M, Denmark.
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5
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Quantitative Co-Localization and Pattern Analysis of Endo-Lysosomal Cargo in Subcellular Image Cytometry and Validation on Synthetic Image Sets. Methods Mol Biol 2017; 1594:93-128. [PMID: 28456978 DOI: 10.1007/978-1-4939-6934-0_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Late endosomes and lysosomes (LE/LYSs) play a central role in trafficking of endocytic cargo, secretion of exosomes, and hydrolysis of ingested proteins and lipids. Failure in such processes can lead to lysosomal storage disorders in which a particular metabolite accumulates within LE/LYSs. Analysis of endocytic trafficking relies heavily on quantitative fluorescence microscopy, but evaluation of the huge image data sets is challenging and demands computer-assisted statistical tools. Here, we describe how to use SpatTrack ( www.sdu.dk/bmb/spattrack ), an imaging toolbox, which we developed for quantification of the distribution and dynamics of endo-lysosomal cargo from fluorescence images of living cells. First, we explain how to analyze experimental images of endocytic processes in Niemann Pick C2 disease fibroblasts using SpatTrack. We demonstrate how to quantify the location of the sterol-binding protein NPC2 in LE/LYSs relative to cholesterol -rich lysosomal storage organelles (LSOs) stained with filipin. Second, we show how to simulate realistic vesicle patterns in the cell geometry using Markov Chain Monte Carlo and suitable inter-vesicle and cell-vesicle interaction potentials. Finally, we use such synthetic vesicle patterns as "ground truth" for validation of two-channel analysis tools in SpatTrack, revealing their high reliability. An improved version of SpatTrack for microscopy-based quantification of cargo transport through the endo-lysosomal system accompanies this protocol.
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6
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Khurana T, Newman-Lindsay S, Young PR, Slater JE. The NPC2 protein: A novel dog allergen. Ann Allergy Asthma Immunol 2016; 116:440-446.e2. [PMID: 26995145 DOI: 10.1016/j.anai.2016.02.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/05/2016] [Accepted: 02/15/2016] [Indexed: 11/17/2022]
Abstract
BACKGROUND Dogs are an important source of indoor allergens that cause rhinoconjunctivitis, urticaria, and asthma in sensitized individuals. Can f 1 is reported as a major dog allergen, but other allergens have also been identified. Identification of immunologically important allergens is important for both the diagnosis and treatment of dog allergy. OBJECTIVE To identify and characterize the canine NPC2 protein, a novel dog allergen. METHODS We screened commercial and laboratory-generated aqueous dog extracts by 2-dimensional polyacrylamide gel electrophoresis with IgE immunoblotting using human serum samples from 71 dog-allergic individuals. A target of interest was excised from the gel and sequenced. Canine NPC2 sequence was generated, and recombinant proteins expressed in yeast and bacteria were used to determine allergenicity. An IgE enzyme-linked immunosorbent assay was used for screening 71 dog-positive and 30 dog-negative serum samples. RESULTS A 16-kDa protein (pK = 8.5) in dog allergen extracts was recognized by specific IgE. The protein was identified by sequencing as a CE1 protein or NPC2 protein. Human IgE bound to recombinant protein was expressed in both yeast and bacteria. Ten (14%) of 71 individuals had specific IgE to NPC2 protein from bacteria, and 12 (17%) had IgE to NPC2 protein from yeast. Binding of pooled dog-allergic serum IgE to the dust mite protein Der p 2 was partially inhibited by recombinant NPC2 protein. CONCLUSION NPC2 protein, a member of the MD-2-related lipid recognition family, is identified as a dog allergen (Can f 7), with an apparent seroprevalence of 10% to 20%.
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Affiliation(s)
- Taruna Khurana
- Laboratory of Immunobiochemistry, Division of Bacterial, Parasitic and Allergenic Products, US Food and Drug Administration, Silver Spring, Maryland
| | - Shoshana Newman-Lindsay
- Laboratory of Immunobiochemistry, Division of Bacterial, Parasitic and Allergenic Products, US Food and Drug Administration, Silver Spring, Maryland
| | - Philip R Young
- Laboratory of Immunobiochemistry, Division of Bacterial, Parasitic and Allergenic Products, US Food and Drug Administration, Silver Spring, Maryland
| | - Jay E Slater
- Laboratory of Immunobiochemistry, Division of Bacterial, Parasitic and Allergenic Products, US Food and Drug Administration, Silver Spring, Maryland.
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7
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Acuña M, González-Hódar L, Amigo L, Castro J, Morales MG, Cancino GI, Groen AK, Young J, Miquel JF, Zanlungo S. Transgenic overexpression of Niemann-Pick C2 protein promotes cholesterol gallstone formation in mice. J Hepatol 2016; 64:361-369. [PMID: 26453970 DOI: 10.1016/j.jhep.2015.10.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 09/29/2015] [Accepted: 10/01/2015] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS Niemann-Pick C2 (NPC2) is a lysosomal protein involved in the egress of low-density lipoprotein-derived cholesterol from lysosomes to other intracellular compartments. NPC2 has been detected in several tissues and is also secreted from the liver into bile. We have previously shown that NPC2-deficient mice fed a lithogenic diet showed reduced biliary cholesterol secretion as well as cholesterol crystal and gallstone formation. This study aimed to investigate the consequences of NPC2 hepatic overexpression on liver cholesterol metabolism, biliary lipid secretion, gallstone formation and the effect of NPC2 on cholesterol crystallization in model bile. METHODS We generated NPC2 transgenic mice (Npc2.Tg) and fed them either chow or lithogenic diets. We studied liver cholesterol metabolism, biliary lipid secretion, bile acid composition and gallstone formation. We performed cholesterol crystallization studies in model bile using a recombinant NPC2 protein. RESULTS No differences were observed in biliary cholesterol content or secretion between wild-type and Npc2.Tg mice fed the chow or lithogenic diets. Interestingly, Npc2.Tg mice showed an increased susceptibility to the lithogenic diet, developing more cholesterol gallstones at early times, but did not show differences in the bile acid hydrophobicity and gallbladder cholesterol saturation indices compared to wild-type mice. Finally, recombinant NPC2 decreased nucleation time in model bile. CONCLUSIONS These results suggest that NPC2 promotes cholesterol gallstone formation by decreasing the cholesterol nucleation time, indicating a pro-nucleating function of NPC2 in bile.
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Affiliation(s)
- Mariana Acuña
- Department of Gastroenterology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile; FONDAP "Center for Genome Regulation" (CGR), Santiago, Chile
| | - Lila González-Hódar
- Department of Gastroenterology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Ludwig Amigo
- Department of Gastroenterology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Castro
- Department of Gastroenterology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - M Gabriela Morales
- Department of Gastroenterology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Gonzalo I Cancino
- Neuroscience and Mental Health Program, The Hospital for Sick Children, Toronto, Canada
| | - Albert K Groen
- Departments of Pediatrics/Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Juan Young
- Centro de Estudios Científicos (CECs), Valdivia, Chile
| | - Juan Francisco Miquel
- Department of Gastroenterology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile; FONDAP "Center for Genome Regulation" (CGR), Santiago, Chile
| | - Silvana Zanlungo
- Department of Gastroenterology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile; FONDAP "Center for Genome Regulation" (CGR), Santiago, Chile.
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Zheng H, Yde CC, Clausen MR, Kristensen M, Lorenzen J, Astrup A, Bertram HC. Metabolomics investigation to shed light on cheese as a possible piece in the French paradox puzzle. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:2830-2839. [PMID: 25727903 DOI: 10.1021/jf505878a] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An NMR-based metabolomics approach was used to investigate the differentiation between subjects consuming cheese or milk and to elucidate the potential link to an effect on blood cholesterol level. Fifteen healthy young men participated in a full crossover study during which they consumed three isocaloric diets with similar fat contents that were either (i) high in milk, (ii) high in cheese with equal amounts of dairy calcium, or (iii) a control diet for 14 days. Urine and feces samples were collected and analyzed by NMR-based metabolomics. Cheese and milk consumption decreased urinary choline and TMAO levels and increased fecal excretion of acetate, propionate, and lipid. Compared with milk intake, cheese consumption significantly reduced urinary citrate, creatine, and creatinine levels and significantly increased the microbiota-related metabolites butyrate, hippurate, and malonate. Correlation analyses indicated that microbial and lipid metabolism could be involved in the dairy-induced effects on blood cholesterol level.
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Affiliation(s)
- Hong Zheng
- †Department of Food Science, Aarhus University, Kirstinebjergvej 10, DK-5792 Aarslev, Denmark
| | - Christian C Yde
- †Department of Food Science, Aarhus University, Kirstinebjergvej 10, DK-5792 Aarslev, Denmark
| | - Morten R Clausen
- †Department of Food Science, Aarhus University, Kirstinebjergvej 10, DK-5792 Aarslev, Denmark
| | - Mette Kristensen
- §Department of Nutrition, Exercise and Sports, University of Copenhagen, DK-1958 Frederiksberg C, Denmark
| | - Janne Lorenzen
- §Department of Nutrition, Exercise and Sports, University of Copenhagen, DK-1958 Frederiksberg C, Denmark
| | - Arne Astrup
- §Department of Nutrition, Exercise and Sports, University of Copenhagen, DK-1958 Frederiksberg C, Denmark
| | - Hanne C Bertram
- †Department of Food Science, Aarhus University, Kirstinebjergvej 10, DK-5792 Aarslev, Denmark
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9
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Lund FW, Jensen MLV, Christensen T, Nielsen GK, Heegaard CW, Wüstner D. SpatTrack: An Imaging Toolbox for Analysis of Vesicle Motility and Distribution in Living Cells. Traffic 2014; 15:1406-29. [DOI: 10.1111/tra.12228] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 09/16/2014] [Accepted: 09/17/2014] [Indexed: 01/01/2023]
Affiliation(s)
- Frederik W. Lund
- Department of Biochemistry and Molecular Biology; University of Southern Denmark; DK-5230 Odense M Denmark
- Department of Biochemistry; Weill Medical College of Cornell University; York Ave. 1300 10065 NY USA
| | - Maria Louise V. Jensen
- Department of Biochemistry and Molecular Biology; University of Southern Denmark; DK-5230 Odense M Denmark
| | - Tanja Christensen
- Department of Biochemistry and Molecular Biology; University of Southern Denmark; DK-5230 Odense M Denmark
| | - Gitte K. Nielsen
- Department of Biomedicine; University of Aarhus; DK-8000 Aarhus C. Denmark
| | - Christian W. Heegaard
- Department of Molecular Biology and Genetics; University of Aarhus; DK-8000 Aarhus C. Denmark
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology; University of Southern Denmark; DK-5230 Odense M Denmark
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10
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Abstract
Lactation physiology is a process that is only partly understood. Proteomics techniques have shown to be useful to help advance the knowledge on lactation physiology in human and rodent species but have not been used as major tools for dairy cows, except for mastitis. In this paper, advanced non-targeted proteomics techniques (Filter aided sample preparation and NanoLC-Orbitrap-MS/MS) were applied to study the milk fat globule membrane and milk serum fraction, resulting in the identification of 246 proteins. Of these, 23 transporters and enzymes were related to lipid synthesis and secretion in mammary gland and their functions are discussed in detail. The identification of these intracellular transporters and enzymes in milk provides a possibility of using milk itself to study lipid synthesis and secretion pathways. This full-scale scan of milk proteins by using non-targeted proteomic analysis helps to reveal the important proteins involved in lipid synthesis and secretion for further examination in targeted studies.
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García-Lorenzo A, Rodríguez-Piñeiro AM, Rodríguez-Berrocal FJ, Cadena MPDL, Martínez-Zorzano VS. Changes on the Caco-2 secretome through differentiation analyzed by 2-D differential in-gel electrophoresis (DIGE). Int J Mol Sci 2012. [PMID: 23203071 PMCID: PMC3509587 DOI: 10.3390/ijms131114401] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Colorectal cancer is still a major health burden worldwide, and its diagnosis has not improved in recent years due to a lack of appropriate diagnostic serum markers. Aiming to find new diagnostic proteins, we applied the proteomic DIGE technology to analyze changes in the secretome before/after differentiation of the colon adenocarcinoma Caco-2 cell line, an accepted in vitro model to study colorectal tumorigenesis. When the secretomes from undifferentiated (tumor-like) and differentiated cells (resembling healthy enterocytes) were compared, we found 96 spots differentially expressed. After MS/MS analysis, 22 spots corresponding to 15 different proteins were identified. Principal component analysis demonstrated these 22 spots could serve as a discriminatory panel between the tumor-like and normal-like cells. Among the identified proteins, the translationally-controlled tumor protein (TCTP), the transforming growth factor-beta-induced protein ig-h3 (TGFβIp), and the Niemann-Pick disease type C2 protein (NPC2) are interesting candidates for future studies focused on their utility as serum biomarkers of colorectal cancer.
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Affiliation(s)
- Andrés García-Lorenzo
- Department of Biochemistry, Genetics and Immunology, Faculty of Biology, University of Vigo, 36310 Vigo, Spain.
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12
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Nielsen GK, Dagnaes-Hansen F, Holm IE, Meaney S, Symula D, Andersen NT, Heegaard CW. Protein replacement therapy partially corrects the cholesterol-storage phenotype in a mouse model of Niemann-Pick type C2 disease. PLoS One 2011; 6:e27287. [PMID: 22073306 PMCID: PMC3207855 DOI: 10.1371/journal.pone.0027287] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 10/13/2011] [Indexed: 01/02/2023] Open
Abstract
Niemann-Pick type C2 (NPC2) disease is a fatal autosomal recessive neurovisceral degenerative disorder characterized by late endosomal-lysosomal sequestration of low-density lipoprotein derived cholesterol. The breach in intracellular cholesterol homeostasis is caused by deficiency of functional NPC2, a soluble sterol binding protein targeted to the lysosomes by binding the mannose-6-phosphate receptor. As currently there is no effective treatment for the disorder, we have investigated the efficacy of NPC2 replacement therapy in a murine gene-trap model of NPC2-disease generated on the 129P2/OlaHsd genetic background. NPC2 was purified from bovine milk and its functional competence assured in NPC2-deficient fibroblasts using the specific cholesterol fluorescent probe filipin. For evaluation of phenotype correction in vivo, three-week-old NPC2−/− mice received two weekly intravenous injections of 5 mg/kg NPC2 until trial termination 66 days later. Whereas the saline treated NPC2−/− mice exhibited massive visceral cholesterol storage as compared to their wild-type littermates, administration of NPC2 caused a marked reduction in cholesterol build up. The histological findings, indicating an amelioration of the disease pathology in liver, spleen, and lungs, corroborated the biochemical results. Little or no difference in the overall cholesterol levels was observed in the kidneys, blood, cerebral cortex and hippocampus when comparing NPC2−/− and wild type mice. However, cerebellum cholesterol was increased about two fold in NPC2−/− mice compared with wild-type littermates. Weight gain performance was slightly improved as a result of the NPC2 treatment but significant motor coordination deficits were still observed. Accordingly, ultrastructural cerebellar abnormalities were detected in both saline treated and NPC2 treated NPC2−/− animals 87 days post partum. Our data indicate that protein replacement may be a beneficial therapeutic approach in the treatment of the visceral manifestations in NPC2 disease and further suggest that neurodegeneration is not secondary to visceral dysfunction.
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Affiliation(s)
- Gitte Krogh Nielsen
- Department of Molecular Biology, Aarhus University, Aarhus, Denmark
- * E-mail: (GKN); (CWH)
| | | | - Ida Elisabeth Holm
- Experimental Neuropathology Laboratory, Department of Pathology, Randers Hospital and Clinical Institute, Aarhus University, Aarhus, Denmark
| | - Steve Meaney
- School of Biological Sciences, Dublin Institute of Technology, Dublin, Ireland
| | - Derek Symula
- Wadsworth Center, Albany, New York, United States of America
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Dixit SS, Jadot M, Sohar I, Sleat DE, Stock AM, Lobel P. Loss of Niemann-Pick C1 or C2 protein results in similar biochemical changes suggesting that these proteins function in a common lysosomal pathway. PLoS One 2011; 6:e23677. [PMID: 21887293 PMCID: PMC3161064 DOI: 10.1371/journal.pone.0023677] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 07/22/2011] [Indexed: 11/19/2022] Open
Abstract
Niemann-Pick Type C (NPC) disease is a lysosomal storage disorder characterized by accumulation of unesterified cholesterol and other lipids in the endolysosomal system. NPC disease results from a defect in either of two distinct cholesterol-binding proteins: a transmembrane protein, NPC1, and a small soluble protein, NPC2. NPC1 and NPC2 are thought to function closely in the export of lysosomal cholesterol with both proteins binding cholesterol in vitro but they may have unrelated lysosomal roles. To investigate this possibility, we compared biochemical consequences of the loss of either protein. Analyses of lysosome-enriched subcellular fractions from brain and liver revealed similar decreases in buoyant densities of lysosomes from NPC1 or NPC2 deficient mice compared to controls. The subcellular distribution of both proteins was similar and paralleled a lysosomal marker. In liver, absence of either NPC1 or NPC2 resulted in similar alterations in the carbohydrate processing of the lysosomal protease, tripeptidyl peptidase I. These results highlight biochemical alterations in the lysosomal system of the NPC-mutant mice that appear secondary to lipid storage. In addition, the similarity in biochemical phenotypes resulting from either NPC1 or NPC2 deficiency supports models in which the function of these two proteins within lysosomes are linked closely.
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Affiliation(s)
- Sayali S. Dixit
- Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey, United States of America
- Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical School (UMDNJ–RWJMS), Piscataway, New Jersey, United States of America
- Department of Biochemistry, UMDNJ–RWJMS, Piscataway, New Jersey, United States of America
| | - Michel Jadot
- Laboratoire de Chimie Physiologique, Namur Research Institute for Life Sciences and Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium
| | - Istvan Sohar
- Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey, United States of America
| | - David E. Sleat
- Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey, United States of America
- Department of Pharmacology, UMDNJ–RWJMS, Piscataway, New Jersey, United States of America
| | - Ann M. Stock
- Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey, United States of America
- Department of Biochemistry, UMDNJ–RWJMS, Piscataway, New Jersey, United States of America
| | - Peter Lobel
- Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey, United States of America
- Department of Pharmacology, UMDNJ–RWJMS, Piscataway, New Jersey, United States of America
- * E-mail:
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14
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Björkhem I, Leoni V, Meaney S. Genetic connections between neurological disorders and cholesterol metabolism. J Lipid Res 2010; 51:2489-503. [PMID: 20466796 PMCID: PMC2918434 DOI: 10.1194/jlr.r006338] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 05/13/2010] [Indexed: 12/25/2022] Open
Abstract
Cholesterol is an essential component of both the peripheral and central nervous systems of mammals. Over the last decade, evidence has accumulated that disturbances in cholesterol metabolism are associated with the development of various neurological conditions. In addition to genetically defined defects in cholesterol synthesis, which will be covered in another review in this Thematic Series, defects in cholesterol metabolism (cerebrotendinous xanthomatosis) and intracellular transport (Niemann Pick Syndrome) lead to neurological disease. A subform of hereditary spastic paresis (type SPG5) and Huntington's disease are neurological diseases with mutations in genes that are of importance for cholesterol metabolism. Neurodegeneration is generally associated with disturbances in cholesterol metabolism, and presence of the E4 isoform of the cholesterol transporter apolipoprotein E as well as hypercholesterolemia are important risk factors for development of Alzheimer's disease. In the present review, we discuss the links between genetic disturbances in cholesterol metabolism and the above neurological disorders.
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Affiliation(s)
- Ingemar Björkhem
- Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden.
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15
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Abdul-Hammed M, Breiden B, Adebayo MA, Babalola JO, Schwarzmann G, Sandhoff K. Role of endosomal membrane lipids and NPC2 in cholesterol transfer and membrane fusion. J Lipid Res 2010; 51:1747-60. [PMID: 20179319 PMCID: PMC2882726 DOI: 10.1194/jlr.m003822] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We examined the effect of Niemann-Pick disease type 2 (NPC2) protein and some late endosomal lipids [sphingomyelin, ceramide and bis(monoacylglycero)phosphate (BMP)] on cholesterol transfer and membrane fusion. Of all lipid-binding proteins tested, only NPC2 transferred cholesterol at a substantial rate, with no transfer of ceramide, GM3, galactosylceramide, sulfatide, phosphatidylethanolamine, or phosphatidylserine. Cholesterol transfer was greatly stimulated by BMP, little by ceramide, and strongly inhibited by sphingomyelin. Cholesterol and ceramide were also significantly transferred in the absence of protein. This spontaneous transfer of cholesterol was greatly enhanced by ceramide, slightly by BMP, and strongly inhibited by sphingomyelin. In our transfer assay, biotinylated donor liposomes were separated from fluorescent acceptor liposomes by streptavidin-coated magnetic beads. Thus, the loss of fluorescence indicated membrane fusion. Ceramide induced spontaneous fusion of lipid vesicles even at very low concentrations, while BMP and sphingomyelin did so at about 20 mol% and 10 mol% concentrations, respectively. In addition to transfer of cholesterol, NPC2 induced membrane fusion, although less than saposin-C. In this process, BMP and ceramide had a strong and mild stimulating effect, and sphingomyelin an inhibiting effect, respectively. Note that the effects of the lipids on cholesterol transfer mediated by NPC2 were similar to their effect on membrane fusion induced by NPC2 and saposin-C.
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Affiliation(s)
- Misbaudeen Abdul-Hammed
- Membrane Biology and Biochemistry Unit, Life and Medical Sciences Institute (LIMES), Bonn, Germany
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16
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Storch J, Xu Z. Niemann-Pick C2 (NPC2) and intracellular cholesterol trafficking. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:671-8. [PMID: 19232397 DOI: 10.1016/j.bbalip.2009.02.001] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 02/03/2009] [Accepted: 02/03/2009] [Indexed: 12/01/2022]
Abstract
Cholesterol is an important precursor for numerous biologically active molecules, and it plays a major role in membrane structure and function. Cholesterol can be endogenously synthesized or exogenously taken up via the endocytic vesicle system and subsequently delivered to post-endo/lysosomal sites including the plasma membrane and the endoplasmic reticulum. Niemann-Pick C (NPC) disease results in the accumulation of exogenously-derived cholesterol, as well as other lipids, in late endosomes and lysosomes (LE/LY). Identification of the two genes that underlie NPC disease, NPC1 and NPC2, has focused attention on the mechanisms by which lipids, in particular cholesterol, are transported out of the LE/LY compartment. This review discusses the role of the NPC2 protein in cholesterol transport, and the potential for concerted action of NPC1 and NPC2 in regulating normal intracellular cholesterol homeostasis.
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Affiliation(s)
- Judith Storch
- Department of Nutritional Sciences and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA.
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17
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Dixit S, Sleat D, Stock A, Lobel P. Do mammalian NPC1 and NPC2 play a role in intestinal cholesterol absorption? Biochem J 2007; 408:1-5. [PMID: 17880278 PMCID: PMC2049080 DOI: 10.1042/bj20071167] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
NPC1L1 (Niemann-Pick C1-like 1), the pharmacological target of the cholesterol-uptake inhibitor ezetimibe, is a transporter localized on the brush border of enterocytes. Although this protein plays a key role in intestinal uptake of sterols, multiple molecular events that underlie intestinal cholesterol absorption have not been fully characterized. Two proteins that might be involved in this process are NPC1 and NPC2 (Niemann-Pick disease type C proteins 1 and 2), which function in the endosomal/lysosomal cholesterol egress pathway and whose deficiency results in NPC (Niemann-Pick type C) disease. The involvement of these proteins in intestinal cholesterol absorption was examined in mutant mice lacking either NPC1 or NPC2. Our data indicate that deficiencies in either protein do not have an effect on cholesterol uptake or absorption. This contrasts with recent results obtained for the fruitfly Drosophila melanogaster, which indicate that a deficiency of NPC1 (dNPC1a being its Drosophila homologue) leads to activation of an NPC1L1 (Drosophila homologue dNPC1b)-independent cholesterol uptake pathway, underscoring fundamental differences in mammalian and non-mammalian cholesterol metabolism.
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Affiliation(s)
- Sayali S. Dixit
- *Center for Advanced Biotechnology and Medicine, 679 Hoes Lane, Piscataway, NJ 08854, U.S.A
- †675 Hoes Lane, Piscataway, NJ 08854, U.S.A
- ‡Department of Biochemistry, University of Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical School (UMDNJ–RWJMS), Piscataway, NJ 08854, U.S.A
| | - David E. Sleat
- *Center for Advanced Biotechnology and Medicine, 679 Hoes Lane, Piscataway, NJ 08854, U.S.A
- §Department of Pharmacology, UMDNJ–RWJMS, Piscataway, NJ 08854, U.S.A
| | - Ann M. Stock
- *Center for Advanced Biotechnology and Medicine, 679 Hoes Lane, Piscataway, NJ 08854, U.S.A
- ‡Department of Biochemistry, University of Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical School (UMDNJ–RWJMS), Piscataway, NJ 08854, U.S.A
- ¶Howard Hughes Medical Institute, Piscataway, NJ 08854, U.S.A
- To whom correspondence should be addressed (email or )
| | - Peter Lobel
- *Center for Advanced Biotechnology and Medicine, 679 Hoes Lane, Piscataway, NJ 08854, U.S.A
- §Department of Pharmacology, UMDNJ–RWJMS, Piscataway, NJ 08854, U.S.A
- To whom correspondence should be addressed (email or )
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18
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Xu S, Benoff B, Liou HL, Lobel P, Stock AM. Structural basis of sterol binding by NPC2, a lysosomal protein deficient in Niemann-Pick type C2 disease. J Biol Chem 2007; 282:23525-31. [PMID: 17573352 PMCID: PMC3645284 DOI: 10.1074/jbc.m703848200] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NPC2 is a small lysosomal glycoprotein that binds cholesterol with submicromolar affinity. Deficiency in NPC2 is the cause of Niemann-Pick type C2 disease, a fatal neurovisceral disorder characterized by accumulation of cholesterol in lysosomes. Here we report the crystal structure of bovine NPC2 bound to cholesterol-3-O-sulfate, an analog that binds with greater apparent affinity than cholesterol. Structures of both apo-bound and sterol-bound NPC2 were observed within the same crystal lattice, with an asymmetric unit containing one molecule of apoNPC2 and two molecules of sterol-bound NPC2. As predicted from a previously determined structure of apoNPC2, the sterol binds in a deep hydrophobic pocket sandwiched between the two beta-sheets of NPC2, with only the sulfate substituent of the ligand exposed to solvent. In the two available structures of apoNPC2, the incipient ligand-binding pocket, which ranges from a loosely packed hydrophobic core to a small tunnel, is too small to accommodate cholesterol. In the presence of sterol, the pocket expands, facilitated by a slight separation of the beta-strands and substantial reorientation of some side chains, resulting in a perfect molding of the pocket around the hydrocarbon portion of cholesterol. A notable feature is the repositioning of two aromatic residues at the tunnel entrance that are essential for NPC2 function. The NPC2 structures provide evidence of a malleable binding site, consistent with the previously documented broad range of sterol ligand specificity.
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Affiliation(s)
- Sujuan Xu
- Center for Advanced Biotechnology and Medicine, Department of Biochemistry, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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19
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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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20
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Berger AC, Vanderford TH, Gernert KM, Nichols JW, Faundez V, Corbett AH. Saccharomyces cerevisiae Npc2p is a functionally conserved homologue of the human Niemann-Pick disease type C 2 protein, hNPC2. EUKARYOTIC CELL 2006; 4:1851-62. [PMID: 16278452 PMCID: PMC1287848 DOI: 10.1128/ec.4.11.1851-1862.2005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Niemann-Pick Disease Type C (NP-C) is a fatal neurodegenerative disease, which is biochemically distinguished by the lysosomal accumulation of exogenously derived cholesterol. Mutation of either the hNPC1 or hNPC2 gene is causative for NP-C. We report the identification of the yeast homologue of human NPC2, Saccharomyces cerevisiae Npc2p. We demonstrate that scNpc2p is evolutionarily related to the mammalian NPC2 family of proteins. We also show, through colocalization, subcellular fractionation, and secretion analyses, that yeast Npc2p is treated similarly to human NPC2 when expressed in mammalian cells. Importantly, we show that yeast Npc2p can efficiently revert the unesterified cholesterol and GM1 accumulation seen in hNPC2-/- patient fibroblasts demonstrating that it is a functional homologue of human NPC2. The present study reveals that the fundamental process of NPC2-mediated lipid transport has been maintained throughout evolution.
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Affiliation(s)
- Adam C Berger
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Rd., NE, Atlanta, GA 30322, USA
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21
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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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22
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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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23
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Chikh K, Vey S, Simonot C, Vanier MT, Millat G. Niemann-Pick type C disease: importance of N-glycosylation sites for function and cellular location of the NPC2 protein. Mol Genet Metab 2004; 83:220-30. [PMID: 15542393 DOI: 10.1016/j.ymgme.2004.06.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Revised: 06/15/2004] [Accepted: 06/16/2004] [Indexed: 10/26/2022]
Abstract
Niemann-Pick disease type C (NPC), a neurovisceral disorder characterized by accumulation of cholesterol and glycolipids in the lysosomal/late endosomal system, is due to mutations on either the NPC1 or the NPC2 genes. Although NPC1 and NPC2 proteins appear essential for proper cellular cholesterol trafficking, their precise functions and relationship have remained elusive. Mutation identification in NPC2 patients did not provide insights into structure-function relationships, but recent studies brought important information on the cholesterol-binding site of the NPC2 protein. The present work was focused on localization and N-glycosylation of NPC2, considering that glycosylation is often essential for targeting, stability and biological function of proteins. Using immunocytofluorescence in cultured human fibroblasts, we found that the native NPC2 protein is essentially lysosomal, at variance with the late endosomal location of NPC1. Expression of cDNA mutants affecting each of the three potential NPC2 N-glycosylation sites in NPC2-/- fibroblasts showed that only two sites are used. The intracellular human NPC2 protein occurred as two N-glycosylated forms, with either one single oligosaccharide chain attached to Asn 58 or two oligosaccharides attached to Asn 58 and 135. The oligosaccharidic chains were of the hybrid and/or high mannose type, with no complex chains. Further studies on the cellular location of Asn 58 and Asn 135 mutant proteins and their respective effect on restoration of normal cholesterol traficking in NPC2-/- cells led to the conclusion that only the oligosaccharide chain carried by Asn 58 is responsible for proper targeting of NPC2 to lysosomes, and is crucial for NPC2 function.
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Affiliation(s)
- Karim Chikh
- Inserm Unit 189, Lyon Sud Medical School, 69921 Oullins, France and Fondation Gillet-Mérieux, Lyon-Sud Hospital, 69495 Pierre Bénite Cedex, France
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24
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Chatterton D, Rasmussen J, Heegaard C, Sørensen E, Petersen T. In vitro digestion of novel milk protein ingredients for use in infant formulas: Research on biological functions. Trends Food Sci Technol 2004. [DOI: 10.1016/j.tifs.2003.12.004] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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25
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Jobim MIM, Oberst ER, Salbego CG, Souza DO, Wald VB, Tramontina F, Mattos RC. Two-dimensional polyacrylamide gel electrophoresis of bovine seminal plasma proteins and their relation with semen freezability. Theriogenology 2004; 61:255-66. [PMID: 14662126 DOI: 10.1016/s0093-691x(03)00230-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The objective of this study was to evaluate the low weight (10-30 kDa) protein profile of bovine seminal plasma using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and to determine if any of these proteins was associated with semen freezability. Seminal plasma was collected from 16 bulls of high or low semen freezability. Twelve protein spots were identified from the 2D gel (15%); six of these were present in all samples. Of the 12 proteins found, three spots, present in all samples, 3 (15-16 kDa), 5 (16-17 kDa), and 7 (10-12 kDa) had nonsignificant variation among bulls, regardless of their freezability classification. Four proteins were more abundant (P<0.05) in seminal plasma samples collected from bulls with high semen freezability than in samples of bulls with low semen freezability: the spots 3 (15-16 kDa, pI 4.7-5.2), 7 (11-12 kDa, pI 4.8-4.9), 11 (13-14 kDa, pI 4.0-4.5), and 23 (20-22 kDa, pI 4.8-5.2). On the other hand, spot 25 (25-26 kDa, pI 6.0-6.5) was more abundant (P<0.05) on seminal plasma samples from bulls with low semen freezability. The N-terminus sequence of protein 7 was identical to the acidic seminal fluid protein (aSFP). Protein 23 (after trypsin digestion) had structural similarity to bovine clusterin. We concluded that there were differences in the seminal plasma protein profile from bulls with low and high semen freezability; aSFP, clusterin, proteins 3 and 11 may be used as semen freezability markers; and protein 25 was related to low semen freezability.
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Affiliation(s)
- M I M Jobim
- Department of Veterinary Clinical Pathology, Veterinary Faculty, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
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26
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Schäfer B, von Horsten HH, Dacheux JL, Holtz W, Kirchhoff C. Cloning and characterization of boar epididymal secretory proteins by homology to the human. Reprod Domest Anim 2003; 38:111-8. [PMID: 12654021 DOI: 10.1046/j.1439-0531.2003.00403.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Northern blot analysis suggested that the boar epididymis produces closely related counterparts to human epididymal proteins HE1, HE3, HE4, HE5 and HE12. 'Full-length' cloning by nucleic acid and amino acid sequence similarity was achieved by RT-PCR methods in the case of the porcine counterparts of HE3 and HE4, while the homologues of HE5 and HE12, despite their cross-hybridization during Northern blot analysis, have not yet been cloned. The two novel porcine cDNAs were derived from moderately abundant epididymal mRNAs that were 75 and 83% identical to HE3 and HE4 cDNAs, respectively. To emphasize their relationship to the corresponding HEs, they were named Se3 and Se4 cDNAs. Their open reading frames predicted small secretory proteins with 55% (Se3) and 76% (Se4) conserved amino acids. Monospecific antipeptide antibodies to HE secretory proteins identified He3- and HE12-related proteins on Western blots of porcine epididymal fluid and semen. Both Northern and Western analyses indicated that the Se proteins were produced in a regionalized pattern and accumulated in the cauda fluid.
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Affiliation(s)
- B Schäfer
- IHF Institut für Hormon- und Fortpflanzungsforschung an der Universität Hamburg, Hamburg, Germany
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27
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Friedland N, Liou HL, Lobel P, Stock AM. Structure of a cholesterol-binding protein deficient in Niemann-Pick type C2 disease. Proc Natl Acad Sci U S A 2003; 100:2512-7. [PMID: 12591954 PMCID: PMC151372 DOI: 10.1073/pnas.0437840100] [Citation(s) in RCA: 238] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2002] [Accepted: 12/23/2002] [Indexed: 11/18/2022] Open
Abstract
Niemann-Pick disease type C2 (NP-C2) is a fatal hereditary disease characterized by accumulation of low-density lipoprotein-derived cholesterol in lysosomes. Here we report the 1.7-A resolution crystal structure of the cholesterol-binding protein deficient in this disease, NPC2, and the characterization of its ligand binding properties. Human NPC2 binds the cholesterol analog dehydroergosterol with submicromolar affinity at both acidic and neutral pH. NPC2 has an Ig-like fold stabilized by three disulfide bonds. The structure of the bovine protein reveals a loosely packed region penetrating from the surface into the hydrophobic core that forms adjacent small cavities with a total volume of approximately 160 A(3). We propose that this region represents the incipient cholesterol-binding site that dilates to accommodate an approximately 740-A(3) cholesterol molecule.
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Affiliation(s)
- Natalia Friedland
- Center for Advanced Biotechnology and Medicine, Howard Hughes Medical Institute, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, 679 Hoes Lane, Piscataway, NJ 08854, USA
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28
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Expression Patterns of the Differentially Expressed Genes During Growth Stages of Hanwoo(Korean Cattle). JOURNAL OF ANIMAL SCIENCE AND TECHNOLOGY 2002. [DOI: 10.5187/jast.2002.44.6.677] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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29
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Nixon B, Jones RC, Hansen LA, Holland MK. Rabbit epididymal secretory proteins. I. Characterization and hormonal regulation. Biol Reprod 2002; 67:133-9. [PMID: 12080009 DOI: 10.1095/biolreprod67.1.133] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Analyses of samples of luminal fluid from the rete testis, distal efferent ducts, and epididymal regions 2-5 and 8 revealed that 91% of the fluid leaving the testis is reabsorbed by the efferent ducts, 79% of the remainder is reabsorbed proximal to epididymal regions 4 and 5, and there is a net secretion of fluid into the duct caudally. There is a net reabsorption by the efferent ducts of 73% of the protein leaving the testis and then a net secretion along the epididymis. SDS-PAGE of the luminal fluids indicated that four new protein bands that were not present in blood appeared in the efferent ducts, 5 in epididymal regions 1-5, 6 in regions 6 and 7, and one in region 8. Two bands in samples from the efferent ducts were absent caudally, and one band present in region 7 was absent in region 8. The rates of incorporation of (35)S-methionine into minced duct in vitro varied among regions when expressed per milligram of wet weight of tissue (region 2-5 > region 7 > region 6 > region 1 > region 8 > ductuli efferentes), and orchidectomy had little effect on the rates. Incorporation into four proteins that were secreted in vitro (M(r) 38 000, 20 000, 15 000, and 13 000) was reduced or abolished by orchidectomy and restored by testosterone therapy. The secretion of three proteins (M(r) 52 000, 23 000, and 22 000) was reduced or abolished by orchidectomy and not restored by testosterone therapy. SDS-PAGE of detergent extracts of sperm indicated that five proteins were lost and nine were gained during epididymal transit. Seven of the proteins gained were about the same molecular weight as proteins secreted by the epididymis (M(r) 94 000, 52 000, 38 000, 36 000, 22 000, 20 000, and 13 000) and were analyzed using N-terminal amino acid microsequencing.
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Affiliation(s)
- Brett Nixon
- Department of Biological Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
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30
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Naureckiene S, Sleat DE, Lackland H, Fensom A, Vanier MT, Wattiaux R, Jadot M, Lobel P. Identification of HE1 as the second gene of Niemann-Pick C disease. Science 2000; 290:2298-301. [PMID: 11125141 DOI: 10.1126/science.290.5500.2298] [Citation(s) in RCA: 627] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Niemann-Pick type C2 disease (NP-C2) is a fatal hereditary disorder of unknown etiology characterized by defective egress of cholesterol from lysosomes. Here we show that the disease is caused by a deficiency in HE1, a ubiquitously expressed lysosomal protein identified previously as a cholesterol-binding protein. HE1 was undetectable in fibroblasts from NP-C2 patients but present in fibroblasts from unaffected controls and NP-C1 patients. Mutations in the HE1 gene, which maps to chromosome 14q24.3, were found in NP-C2 patients but not in controls. Treatment of NP-C2 fibroblasts with exogenous recombinant HE1 protein ameliorated lysosomal accumulation of low density lipoprotein-derived cholesterol.
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Affiliation(s)
- S Naureckiene
- Center for Advanced Biotechnology and Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
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31
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Takai T, Ichikawa S, Hatanaka H, Inagaki F, Okumura Y. Effects of proline mutations in the major house dust mite allergen Der f 2 on IgE-binding and histamine-releasing activity. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:6650-6. [PMID: 11054118 DOI: 10.1046/j.1432-1327.2000.01760.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Der f 2 is the major group 2 allergen from house dust mite Dermatophagoides farinae and is composed of 129 amino-acid residues. Wild-type and six proline mutants of Der f 2 (P26A, P34A, P66A, P79A, P95A, and P99A) expressed in Escherichia coli were refolded and purified. Formations of intramolecular disulfide bonds in the purified proteins were confirmed correct. The apparent molecular masses analyzed by gel-filtration were 14-15 kDa. The IgE-binding capacity in the sera of seven mite-allergic patients, inhibitory activity for IgE-binding to immobilized wild-type Der f 2, and activity to stimulate peripheral blood basophils to release histamine in two volunteers were analyzed. P95A and P99A, which slightly differed from the wild-type Der f 2 in their CD spectrum, showed reduced IgE-binding, reduced inhibitory activity, and less histamine-releasing activity than the wild-type. P34A also showed reduced allergenicity. Considering that Pro95, Pro99 and Pro34 are closely located in loops at one end of the tertiary structure of Der f 2, we concluded that these loop regions included an IgE-binding site common to all tested patients. P66A showed reduced IgE-binding in two sera out of seven. P26A and P79A showed no reduced allergenicity. However, in immunoblot analysis after SDS/PAGE under reduced conditions, P79A showed no or markedly reduced IgE-binding while the other mutants showed IgE-binding corresponding to that in the assay using correctly refolded proteins. This suggests that Pro79 is involved in refolding of Der f 2. The findings in this study are important for the understanding of the antigenic structure of mite group 2 allergens and for manipulation of the allergens for specific immunotherapy.
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Affiliation(s)
- T Takai
- Bioscience Research and Development Laboratory, Asahi Breweries, Ltd, Ibaraki, Japan.
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Nakamura Y, Takayama N, Minamitani T, Ikuta T, Ariga H, Matsumoto K. Primary structure, genomic organization and expression of the major secretory protein of murine epididymis, ME1. Gene 2000; 251:55-62. [PMID: 10863096 DOI: 10.1016/s0378-1119(00)00189-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The mouse cDNA and its genomic clones encoding the epididymal secretory glycoprotein ME1 were identified. The Me1 gene spans 15kb with four exons and three introns. The deduced amino-acid sequence of the ME1 cDNA revealed that it consists of 149 amino acid residues, which contain a signal peptide characteristic of secretory proteins, six cysteine residues and a proline-rich region conserved in the orthologous proteins. Northern blot analysis revealed that 1.3kb ME1 mRNA is highly expressed in the mouse epididymis. The polyclonal antibodies generated against human HE1 (ME1 orthologous protein) expressed in bacteria reacted with approximately 17 to 25kDa components in mouse epididymis crude extract. The reduction of the molecular mass of the recombinant ME1 protein with the digestion of glycopeptidase A indicated that it is modified by Asn-linked glycosylation.
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Affiliation(s)
- Y Nakamura
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
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Okamura N, Kiuchi S, Tamba M, Kashima T, Hiramoto S, Baba T, Dacheux F, Dacheux JL, Sugita Y, Jin YZ. A porcine homolog of the major secretory protein of human epididymis, HE1, specifically binds cholesterol. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1438:377-87. [PMID: 10366780 DOI: 10.1016/s1388-1981(99)00070-0] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A porcine homolog of the major secretory protein of human epididymis, HE1, was for the first time purified from the porcine cauda epididymal fluid. The HE1 homolog was secreted into the epididymal fluid as a 19-kDa glycoprotein, whose sugar moiety was gradually processed to form a 16-kDa protein during transit through the epididymis. The HE1 homolog mRNA was detected only in the caput and corpus epididymis among the porcine tissues examined. The purified HE1 homolog specifically bound cholesterol with high affinity (Kd=2. 3 microM). The binding stoichiometry was determined to be 0.94 mol/mol, suggesting that 1 mol of cholesterol binds to 1 mol of the protein. It was also found that the HE1 homolog is a major cholesterol-binding protein in the porcine epididymal fluid. The possibility that the HE1 homolog is involved in the regulation of the lipid composition of the sperm membranes during the maturation in epididymis is discussed.
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Affiliation(s)
- N Okamura
- Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki 305, Japan.
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Abstract
The epididymis is a tubular organ exhibiting vectorial functions of sperm concentration, maturation, transport, and storage. The molecular basis for these functions is poorly understood. However, it has become increasingly clear that regional differences along the length of the duct play a role in epididymal physiology and that region-specific gene expression is involved in the formation of these differences. Although not an overtly segmented organ, the epididymis consists of a series of highly coiled "zones," separated by connective tissue septulae and distinct by cell morphology and their pattern of gene expression. Thus, it constitutes an interesting mammalian model to study how pattern formation is achieved by differential gene activity. A large number of epididymis-expressed genes have been cloned and analyzed at the molecular level, most of them have been characterized by a distinct temporal and spatial expression pattern within the organ. Only recently have theories been developed about how and when during ontogenesis this pattern formation takes place and what its significance might be. This review summarizes the current knowledge on regionalized gene expression in the epididymis and presents hypotheses concerning its ontogenetic origin and regulation in the adult.
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Affiliation(s)
- C Kirchhoff
- IHF Institute for Hormone and Fertility Research, Hamburg, Germany
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Affiliation(s)
- W R Thomas
- TVW Telethon Institute for Child Health Research (affiliated with the University of Western Australia), West Perth, Australia
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Mortarino M, Tedeschi G, Negri A, Ceciliani F, Gottardi L, Maffeo G, Ronchi S. Two-dimensional polyacrylamide gel electrophoresis map of bull seminal plasma proteins. Electrophoresis 1998; 19:797-801. [PMID: 9629917 DOI: 10.1002/elps.1150190532] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A two-dimensional polyacrylamide gel electrophoresis map of bull seminal plasma proteins has been established. About 250 spots were detected after silver staining and polypeptides from 24 spots have been N-terminally sequenced. Major proteins already described in bull seminal plasma, like PDC-109 and aSFP, have been located on the map; proteins not yet reported in male reproductive tracts have been evidenced; for some polypeptides showing a previously unknown N-terminal sequence, structural similarities with proteins described in other organisms have been found. A reference map of seminal plasma proteins could be useful in relating protein pattern changes to physiopathological events influencing the reproductive sphere.
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Affiliation(s)
- M Mortarino
- Istituto di Fisiologia Veterinaria e Biochimica, Università degli Studi di Milano, Italy
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Ichikawa S, Hatanaka H, Yuuki T, Iwamoto N, Kojima S, Nishiyama C, Ogura K, Okumura Y, Inagaki F. Solution structure of Der f 2, the major mite allergen for atopic diseases. J Biol Chem 1998; 273:356-60. [PMID: 9417088 DOI: 10.1074/jbc.273.1.356] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
House dust mites cause heavy atopic diseases such as asthma and dermatitis. Among allergens from Dermatophagoides farinae, Der f 2 shows the highest positive rate for atopic patients, but its biological function in mites has been perfectly unknown, as well as the functions of its homologs in human and other animals. We have determined the tertiary structure of Der f 2 by multidimensional nuclear magnetic resonance spectroscopy. Der f 2 was found to be a single-domain protein of immunoglobulin fold, and its structure was the most similar to those of the two regulatory domains of transglutaminase. This fact, binding to the bacterial surface, and other small pieces of information hinted that Der f 2 is related to the innate antibacterial defense system in mites. The immunoglobulin E epitopes are also discussed on the basis of the tertiary structure.
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Affiliation(s)
- S Ichikawa
- Department of Molecular Physiology, Tokyo Metropolitan Institute of Medical Science, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113, Japan
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