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Xiao J, Dong LW, Liu S, Meng FH, Xie C, Lu XY, Zhang WJ, Luo J, Song BL. Bile acids-mediated intracellular cholesterol transport promotes intestinal cholesterol absorption and NPC1L1 recycling. Nat Commun 2023; 14:6469. [PMID: 37833289 PMCID: PMC10575946 DOI: 10.1038/s41467-023-42179-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 10/03/2023] [Indexed: 10/15/2023] Open
Abstract
Niemann-Pick C1-like 1 (NPC1L1) is essential for intestinal cholesterol absorption. Together with the cholesterol-rich and Flotillin-positive membrane microdomain, NPC1L1 is internalized via clathrin-mediated endocytosis and transported to endocytic recycling compartment (ERC). When ERC cholesterol level decreases, NPC1L1 interacts with LIMA1 and moves back to plasma membrane. However, how cholesterol leaves ERC is unknown. Here, we find that, in male mice, intracellular bile acids facilitate cholesterol transport to other organelles, such as endoplasmic reticulum, in a non-micellar fashion. When cholesterol level in ERC is decreased by bile acids, the NPC1L1 carboxyl terminus that previously interacts with the cholesterol-rich membranes via the A1272LAL residues dissociates from membrane, exposing the Q1277KR motif for LIMA1 recruitment. Then NPC1L1 moves back to plasma membrane. This study demonstrates an intracellular cholesterol transport function of bile acids and explains how the substantial amount of cholesterol in NPC1L1-positive compartments is unloaded in enterocytes during cholesterol absorption.
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Affiliation(s)
- Jian Xiao
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Le-Wei Dong
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Shuai Liu
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
- Heart Center, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, Xinjiang, China
| | - Fan-Hua Meng
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
- Heart Center, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, Xinjiang, China
- Affiliated Hospital of Jining Medical University, Jining, 272007, Shandong, China
| | - Chang Xie
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Xiao-Yi Lu
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Weiping J Zhang
- Department of Pathophysiology, Naval Medical University, Shanghai, China
| | - Jie Luo
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Bao-Liang Song
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China.
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Furse S, Koch H, Wright GA, Stevenson PC. Sterol and lipid metabolism in bees. Metabolomics 2023; 19:78. [PMID: 37644282 PMCID: PMC10465395 DOI: 10.1007/s11306-023-02039-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 07/27/2023] [Indexed: 08/31/2023]
Abstract
BACKGROUND Bees provide essential pollination services for many food crops and are critical in supporting wild plant diversity. However, the dietary landscape of pollen food sources for social and solitary bees has changed because of agricultural intensification and habitat loss. For this reason, understanding the basic nutrient metabolism and meeting the nutritional needs of bees is becoming an urgent requirement for agriculture and conservation. We know that pollen is the principal source of dietary fat and sterols for pollinators, but a precise understanding of what the essential nutrients are and how much is needed is not yet clear. Sterols are key for producing the hormones that control development and may be present in cell membranes, where fatty-acid-containing species are important structural and signalling molecules (phospholipids) or to supply, store and distribute energy (glycerides). AIM OF THE REVIEW In this critical review, we examine the current general understanding of sterol and lipid metabolism of social and solitary bees from a variety of literature sources and discuss implications for bee health. KEY SCIENTIFIC CONCEPTS OF REVIEW We found that while eusocial bees are resilient to some dietary variation in sterol supply the scope for this is limited. The evidence of both de novo lipogenesis and a dietary need for particular fatty acids (FAs) shows that FA metabolism in insects is analogous to mammals but with distinct features. Bees rely on their dietary intake for essential sterols and lipids in a way that is dependent upon pollen availability.
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Affiliation(s)
- Samuel Furse
- Royal Botanic Gardens, Kew Green, Kew, Surrey, TW9 3AB, UK.
| | - Hauke Koch
- Royal Botanic Gardens, Kew Green, Kew, Surrey, TW9 3AB, UK
| | | | - Philip C Stevenson
- Royal Botanic Gardens, Kew Green, Kew, Surrey, TW9 3AB, UK.
- Natural Resources Institute, University of Greenwich, Chatham, Kent, ME4 4TB, UK.
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Bansia H, Mahanta P, Yennawar NH, Ramakumar S. Small Glycols Discover Cryptic Pockets on Proteins for Fragment-Based Approaches. J Chem Inf Model 2021; 61:1322-1333. [PMID: 33570386 DOI: 10.1021/acs.jcim.0c01126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cryptic pockets are visible in ligand-bound protein structures but are occluded in unbound structures. Utilizing these pockets in fragment-based drug-design provides an attractive option for proteins not tractable by classical binding sites. However, owing to their hidden nature, they are difficult to identify. Here, we show that small glycols find cryptic pockets on a diverse set of proteins. Initial crystallography experiments serendipitously revealed the ability of ethylene glycol, a small glycol, to identify a cryptic pocket on the W6A mutant of the RBSX protein (RBSX-W6A). Explicit-solvent molecular dynamics (MD) simulations of RBSX-W6A with the exposed state of the cryptic pocket (ethylene glycol removed) revealed closure of the pocket reiterating that the exposed state of cryptic pockets in general are unstable in the absence of ligands. Also, no change in the pocket was observed for simulations of RBSX-W6A with the occluded state of the cryptic pocket, suggesting that water molecules are not able to open the cryptic pocket. "Cryptic-pocket finding" potential of small glycols was then supported and generalized through additional crystallography experiments, explicit-cosolvent MD simulations, and protein data set construction and analysis. The cryptic pocket on RBSX-W6A was found again upon repeating the crystallography experiments with another small glycol, propylene glycol. Use of ethylene glycol as a probe molecule in cosolvent MD simulations led to the enhanced sampling of the exposed state of experimentally observed cryptic sites on a test set of two proteins (Niemann-Pick C2, Interleukin-2). Further, analyses of protein structures with validated cryptic sites showed that ethylene glycol molecules bind to sites on proteins (Bcl-xL, G-actin, myosin II, and glutamate receptor 2), which become apparent upon binding of biologically relevant ligands. Our study thus suggests potential application of the small glycols in experimental and computational fragment-based approaches to identify cryptic pockets in apparently undruggable and/or difficult targets, making these proteins amenable to drug-design strategies.
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Affiliation(s)
- Harsh Bansia
- Department of Physics, Indian Institute of Science, Bengaluru 560012, India
| | - Pranjal Mahanta
- Department of Physics, Indian Institute of Science, Bengaluru 560012, India
| | - Neela H Yennawar
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, United States
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Lopez AM, Ramirez CM, Taylor AM, Jones RD, Repa JJ, Turley SD. Ontogenesis and Modulation of Intestinal Unesterified Cholesterol Sequestration in a Mouse Model of Niemann-Pick C1 Disease. Dig Dis Sci 2020; 65:158-167. [PMID: 31312996 DOI: 10.1007/s10620-019-05736-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 07/11/2019] [Indexed: 01/24/2023]
Abstract
BACKGROUND Mutations in the NPC1 gene result in sequestration of unesterified cholesterol (UC) and glycosphingolipids in most tissues leading to multi-organ disease, especially in the brain, liver, lungs, and spleen. Various data from NPC1-deficient mice suggest the small intestine (SI) is comparatively less affected, even in late stage disease. METHODS Using the Npc1nih mouse model, we measured SI weights and total cholesterol (TC) levels in Npc1-/- versus Npc1+/+ mice as a function of age, and then after prolonged ezetimibe-induced inhibition of cholesterol absorption. Next, we determined intestinal levels of UC and esterified cholesterol (EC), and cholesterol synthesis rates in Npc1-/- and Npc1+/+ mice, with and without the cholesterol-esterifying enzyme SOAT2, following a once-only subcutaneous injection with 2-hydroxypropyl-β-cyclodextrin (2HPβCD). RESULTS By ~ 42 days of age, intestinal TC levels averaged ~ 2.1-fold more (mostly UC) in the Npc1-/- versus Npc1+/+ mice with no further increase thereafter. Chronic ezetimibe treatment lowered intestinal TC levels in the Npc1-/- mice by only ~ 16%. In Npc1-/- mice given 2HPβCD 24 h earlier, UC levels fell, EC levels increased (although less so in mice lacking SOAT2), and cholesterol synthesis was suppressed equally in the Npc1-/-:Soat2+/+ and Npc1-/-:Soat2-/- mice. CONCLUSIONS The low and static levels of intestinal UC sequestration in Npc1-/- mice likely reflect the continual sloughing of cells from the mucosa. This sequestration is blunted by about the same extent following a single acute treatment with 2HPβCD as it is by a prolonged ezetimibe-induced block of cholesterol absorption.
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MESH Headings
- 2-Hydroxypropyl-beta-cyclodextrin/pharmacology
- Animals
- Cholesterol/metabolism
- Disease Models, Animal
- Ezetimibe/pharmacology
- Female
- Intestinal Absorption/drug effects
- Intestinal Mucosa/drug effects
- Intestinal Mucosa/metabolism
- Intestine, Small/drug effects
- Intestine, Small/metabolism
- Intracellular Signaling Peptides and Proteins/deficiency
- Intracellular Signaling Peptides and Proteins/genetics
- Male
- Mice, 129 Strain
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Niemann-Pick C1 Protein
- Niemann-Pick Disease, Type C/drug therapy
- Niemann-Pick Disease, Type C/genetics
- Niemann-Pick Disease, Type C/metabolism
- Sterol O-Acyltransferase/genetics
- Sterol O-Acyltransferase/metabolism
- Sterol O-Acyltransferase 2
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Affiliation(s)
- Adam M Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Charina M Ramirez
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Anna M Taylor
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Ryan D Jones
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- Department of Pathology, Northwestern University, Chicago, IL, 60611, USA
| | - Joyce J Repa
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Stephen D Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.
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Holtof M, Lenaerts C, Cullen D, Vanden Broeck J. Extracellular nutrient digestion and absorption in the insect gut. Cell Tissue Res 2019; 377:397-414. [DOI: 10.1007/s00441-019-03031-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 04/04/2019] [Indexed: 02/07/2023]
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Vélez AM, Fishilevich E. The mysteries of insect RNAi: A focus on dsRNA uptake and transport. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2018; 151:25-31. [PMID: 30704709 DOI: 10.1016/j.pestbp.2018.08.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 07/11/2018] [Accepted: 08/08/2018] [Indexed: 05/25/2023]
Abstract
RNA interference (RNAi) is becoming a practical tool to control insect pests. Many mysteries of how double-stranded RNA (dsRNA) is transported into, within, and between cells to generate an efficient RNAi response in insects are still to be unraveled. This review provides an overview of the evidence that supports a key role of endocytosis in the uptake of dsRNA on both cellular and tissue levels. Additionally, other components of cellular membrane transport and their impact on the efficiency of RNAi in insects are explored. It is now evident that the membrane transport and potentially dsRNA release from the endosome may comprise some of the limiting factors in insects that are recalcitrant to dsRNA. This review concludes with the apparent connection between gene products that are necessary for cellular trafficking of dsRNA and highly lethal RNAi targets.
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Affiliation(s)
- Ana M Vélez
- University of Nebraska-Lincoln, Department of Entomology, 103 Entomology Hall, Lincoln, NE 68583-0816, United States.
| | - Elane Fishilevich
- University of Nebraska-Lincoln, Department of Entomology, 103 Entomology Hall, Lincoln, NE 68583-0816, United States; Corteva Agriscience™, Agriculture Division of DowDuPont™, 9330 Zionsville Road, Indianapolis, IN 46268, United States.
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Lopez AM, Jones RD, Repa JJ, Turley SD. Niemann-Pick C1-deficient mice lacking sterol O-acyltransferase 2 have less hepatic cholesterol entrapment and improved liver function. Am J Physiol Gastrointest Liver Physiol 2018; 315:G454-G463. [PMID: 29878847 PMCID: PMC6230690 DOI: 10.1152/ajpgi.00124.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 05/31/2018] [Accepted: 06/01/2018] [Indexed: 01/31/2023]
Abstract
Cholesteryl esters are generated at multiple sites in the body by sterol O-acyltransferase (SOAT) 1 or SOAT2 in various cell types and lecithin cholesterol acyltransferase in plasma. Esterified cholesterol and triacylglycerol contained in lipoproteins cleared from the circulation via receptor-mediated or bulk-phase endocytosis are hydrolyzed by lysosomal acid lipase within the late endosomal/lysosomal (E/L) compartment. Then, through the successive actions of Niemann-Pick C (NPC) 2 and NPC 1, unesterified cholesterol (UC) is exported from the E/L compartment to the cytosol. Mutations in either NPC1 or NPC2 lead to continuing entrapment of UC in all organs, resulting in multisystem disease, which includes hepatic dysfunction and in some cases liver failure. These studies investigated primarily whether elimination of SOAT2 in NPC1-deficient mice impacted hepatic UC sequestration, inflammation, and transaminase activities. Measurements were made in 7-wk-old mice fed a low-cholesterol chow diet or one enriched with cholesterol starting 2 wk before study. In the chow-fed mice, NPC1:SOAT2 double knockouts, compared with their littermates lacking only NPC1, had 20% less liver mass, 28% lower hepatic UC concentrations, and plasma alanine aminotransferase and aspartate aminotransferase activities that were decreased by 48% and 36%, respectively. mRNA expression levels for several markers of inflammation were all significantly lower in the NPC1 mutants lacking SOAT2. The existence of a new class of potent and selective SOAT2 inhibitors provides an opportunity for exploring if suppression of this enzyme could potentially become an adjunctive therapy for liver disease in NPC1 deficiency. NEW & NOTEWORTHY In Niemann-Pick type C1 (NPC1) disease, the entrapment of unesterified cholesterol (UC) in the endosomal/lysosomal compartment of all cells causes multiorgan disease, including neurodegeneration, pulmonary dysfunction, and liver failure. Some of this sequestered UC entered cells initially in the esterified form. When sterol O-acyltransferase 2, a cholesterol esterifying enzyme present in enterocytes and hepatocytes, is eliminated in NPC1-deficient mice, there is a reduction in their hepatomegaly, hepatic UC content, and cellular injury.
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Affiliation(s)
- Adam M Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Ryan D Jones
- Department of Physiology, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Joyce J Repa
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
- Department of Physiology, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Stephen D Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
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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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Kimura SR, Hu HP, Ruvinsky AM, Sherman W, Favia AD. Deciphering Cryptic Binding Sites on Proteins by Mixed-Solvent Molecular Dynamics. J Chem Inf Model 2017; 57:1388-1401. [PMID: 28537745 DOI: 10.1021/acs.jcim.6b00623] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In recent years, molecular dynamics simulations of proteins in explicit mixed solvents have been applied to various problems in protein biophysics and drug discovery, including protein folding, protein surface characterization, fragment screening, allostery, and druggability assessment. In this study, we perform a systematic study on how mixtures of organic solvent probes in water can reveal cryptic ligand binding pockets that are not evident in crystal structures of apo proteins. We examine a diverse set of eight PDB proteins that show pocket opening induced by ligand binding and investigate whether solvent MD simulations on the apo structures can induce the binding site observed in the holo structures. The cosolvent simulations were found to induce conformational changes on the protein surface, which were characterized and compared with the holo structures. Analyses of the biological systems, choice of probes and concentrations, druggability of the resulting induced pockets, and application to drug discovery are discussed here.
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Affiliation(s)
- S Roy Kimura
- Schrödinger KK , 17th Fl, Marunouchi Trust Tower North, 1-8-1 Marunouchi, Chiyoda-ku, Tokyo, Japan
| | - Hai Peng Hu
- Lilly China Research and Development Center (LCRDC), Eli Lilly and Company , Building 8, 338 Jia Li Lue Road, Shanghai 201203, PR China
| | - Anatoly M Ruvinsky
- Schrödinger LLC , 222 Third Street, Suite 2230, Cambridge, Massachusetts 02142, United States
| | - Woody Sherman
- Schrödinger LLC , 222 Third Street, Suite 2230, Cambridge, Massachusetts 02142, United States
| | - Angelo D Favia
- Lilly China Research and Development Center (LCRDC), Eli Lilly and Company , Building 8, 338 Jia Li Lue Road, Shanghai 201203, PR China
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Bolaños J, Betanzos A, Javier-Reyna R, García- Rivera G, Huerta M, Pais-Morales J, González-Robles A, Rodríguez MA, Schnoor M, Orozco E. EhNPC1 and EhNPC2 Proteins Participate in Trafficking of Exogenous Cholesterol in Entamoeba histolytica Trophozoites: Relevance for Phagocytosis. PLoS Pathog 2016; 12:e1006089. [PMID: 28002502 PMCID: PMC5176366 DOI: 10.1371/journal.ppat.1006089] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 11/25/2016] [Indexed: 12/31/2022] Open
Abstract
Entamoeba histolytica, the highly phagocytic protozoan causative of human amoebiasis lacks the machinery to synthesize cholesterol. Here, we investigated the presence of NPC1 and NPC2 proteins in this parasite, which are involved in cholesterol trafficking in mammals. Bioinformatics analysis revealed one Ehnpc1 and two Ehnpc2 genes. EhNPC1 appeared as a transmembrane protein and both EhNPC2 as peripheral membrane proteins. Molecular docking predicted that EhNPC1 and EhNPC2 bind cholesterol and interact with each other. Genes and proteins were identified in trophozoites. Serum pulse-chase and confocal microscopy assays unveiled that after trophozoites sensed the cholesterol source, EhNPC1 and EhNPC2 were organized around the plasma membrane in a punctuated pattern. Vesicles emerged and increased in number and size and some appeared full of cholesterol with EhNPC1 or EhNPC2 facing the extracellular space. Both proteins, but mostly EhNPC2, were found out of the cell associated with cholesterol. EhNPC1 and cholesterol formed networks from the plasma membrane to the nucleus. EhNPC2 appeared in erythrocytes that were being ingested by trophozoites, co-localizing with cholesterol of erythrocytes, whereas EhNPC1 surrounded the phagocytic cup. EhNPC1 and EhNPC2 co-localized with EhSERCA in the endoplasmic reticulum and with lysobisphosphatidic acid and EhADH (an Alix protein) in phagolysosomes. Immunoprecipitation assays confirmed the EhNPC1 and EhNPC2 association with cholesterol, EhRab7A and EhADH. Serum starved and blockage of cholesterol trafficking caused a low rate of phagocytosis and incapability of trophozoites to produce damage in the mouse colon. Ehnpc1 and Ehnpc2 knockdown provoked in trophozoites a lower intracellular cholesterol concentration and a diminished rate of phagocytosis; and Ehnpc1 silencing also produced a decrease of trophozoites movement. Trafficking of EhNPC1 and EhNPC2 during cholesterol uptake and phagocytosis as well as their association with molecules involved in endocytosis strongly suggest that these proteins play a key role in cholesterol uptake. NPC1 and NPC2 proteins are involved in cholesterol trafficking in mammals. Using different approaches, we have detected the orthologues EhNPC1 and EhNPC2 proteins in Entamoeba histolytica. Trophozoites are particularly rich in membranes and vacuoles, but they do not possess the machinery to synthetize cholesterol. Thus, they are completely dependent on molecules able to “fish” cholesterol from the medium. The relevance of our findings lies in the fact that cholesterol is fundamental for endocytosis and motility; and, phagocytosis is an important nutritional and virulence factor for E. histolytica. In silico and experimental strategies, using U18666A to arrest cholesterol trafficking, as well as, knockdown mutants, showed that EhNPC1 and EhNPC2 participate in cholesterol uptake and trafficking in this parasite. They are secreted by trophozoites and directly involved in erythrophagocytosis and motility. Our findings revealed E. histolytica as one of the first protozoa in which these proteins are being characterized. Moreover, E. histolytica provides an excellent and less complicated model to elucidate the intricate event of cholesterol trafficking in eukaryotic cells. The relevance of cholesterol transport for the parasite virulence and the involvement of EhNPC1 and EhNPC2 in this process, make these proteins promising targets for therapy strategies development against the parasite.
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Affiliation(s)
- Jeni Bolaños
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., México
| | - Abigail Betanzos
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., México
- Cátedras, Consejo Nacional de Ciencia y Tecnología, D.F., México
| | - Rosario Javier-Reyna
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., México
| | - Guillermina García- Rivera
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., México
| | - Miriam Huerta
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., México
| | - Jonnatan Pais-Morales
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., México
| | - Arturo González-Robles
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., México
| | - Mario A. Rodríguez
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., México
| | - Michael Schnoor
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., México
| | - Esther Orozco
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., México
- * E-mail:
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Poongavanam V, Kongsted J, Wüstner D. Computational Analysis of Sterol Ligand Specificity of the Niemann Pick C2 Protein. Biochemistry 2016; 55:5165-79. [DOI: 10.1021/acs.biochem.6b00217] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Vasanthanathan Poongavanam
- Department of Physics, Chemistry
and Pharmacy and †Department of Biochemistry and
Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Jacob Kongsted
- Department of Physics, Chemistry
and Pharmacy and †Department of Biochemistry and
Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Daniel Wüstner
- Department of Physics, Chemistry
and Pharmacy and †Department of Biochemistry and
Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
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12
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Nawaratna SSK, Gobert GN, Willis C, Mulvenna J, Hofmann A, McManus DP, Jones MK. Lysosome-associated membrane glycoprotein (LAMP)--preliminary study on a hidden antigen target for vaccination against schistosomiasis. Sci Rep 2015; 5:15069. [PMID: 26472258 PMCID: PMC4607944 DOI: 10.1038/srep15069] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 08/13/2015] [Indexed: 12/12/2022] Open
Abstract
Our previously reported gene atlasing of schistosome tissues revealed transcripts that were highly enriched in the digestive tract of Schistosoma mansoni. From these, we selected two candidates, Sm-LAMP and Sm-NPC2 for testing as vaccine targets. The two molecules were selected on the basis of relatively high expression in the gastrodermis, their potentially important biological function, divergence from homologous molecules of the host and possible apical membrane expression in the gastrodermis. Bacterially expressed recombinant peptides corresponding to regions excluding trans-membrane domains of the selected vaccine targets were used in blinded vaccine trials in CBA mice using alum-CpG as adjuvant. Vaccine trials using the recombinant insoluble Sm-LAMP protein showed 16-25% significant reduction in total worm burden. Faecal egg count reduction was 52% and 60% in two trials, respectively, with similar results for the solubly expressed protein. Liver egg burden was reduced significantly (20% and 38%) with an insoluble recombinant Sm-LAMP in two trials, but not with the soluble recombinant form. Parasite fecundity was not affected by either Sm-LAMP protein preparations in the trials. It is concluded that Sm-LAMP may provide limited protection towards S. mansoni infections but could be used in combination with other vaccine candidates, to provide more comprehensive protection.
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Affiliation(s)
- Sujeevi S. K. Nawaratna
- School of Veterinary Sciences, The University of Queensland, Gatton Campus, Gatton Qld, 4343, Australia
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Qld, 4006, Australia
| | - Geoffrey N. Gobert
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Qld, 4006, Australia
| | - Charlene Willis
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Qld, 4006, Australia
| | - Jason Mulvenna
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Qld, 4006, Australia
| | - Andreas Hofmann
- Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Qld 4111, Australia
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Donald P. McManus
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Qld, 4006, Australia
| | - Malcolm K. Jones
- School of Veterinary Sciences, The University of Queensland, Gatton Campus, Gatton Qld, 4343, Australia
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Qld, 4006, Australia
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Abstract
PURPOSE OF REVIEW The process of reverse cholesterol transport (RCT) is critical for disposal of excess cholesterol from the body. Although it is generally accepted that RCT requires biliary secretion, recent studies show that RCT persists in genetic or surgical models of biliary insufficiency. Discovery of this nonbiliary pathway has opened new possibilities of targeting the intestine as an inducible cholesterol excretory organ. In this review we highlight the relative contribution and therapeutic potential for both biliary and nonbiliary components of RCT. RECENT FINDINGS Recently, the proximal small intestine has gained attention for its underappreciated ability to secrete cholesterol in a process called transintestinal cholesterol efflux (TICE). Although this intestinal pathway for RCT is quantitatively less important than the biliary route under normal physiological conditions, TICE is highly inducible, providing a novel therapeutic opportunity for treatment of atherosclerotic cardiovascular disease (ASCVD). In fact, recent studies show that intestine-specific activation of RCT protects against ASCVD in mice. SUMMARY It is well known that the small intestine plays a gatekeeper role in the maintenance of cholesterol balance. Through integrated regulation of cholesterol absorption and TICE, the small intestine is a key target for new therapies against ASCVD.
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Affiliation(s)
- Ryan E. Temel
- Department of Pathology-Section on Lipid Sciences, Wake Forest University School of Medicine, Winston-Salem, North Carolina, 27157, USA
| | - J. Mark Brown
- Department of Pathology-Section on Lipid Sciences, Wake Forest University School of Medicine, Winston-Salem, North Carolina, 27157, USA
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Niemann-Pick C1-Like 1 and cholesterol uptake. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:964-72. [PMID: 22480541 DOI: 10.1016/j.bbalip.2012.03.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Revised: 03/09/2012] [Accepted: 03/12/2012] [Indexed: 01/27/2023]
Abstract
Niemann-Pick C1-Like 1 (NPC1L1) is a polytopic transmembrane protein responsible for dietary cholesterol and biliary cholesterol absorption. Consistent with its functions, NPC1L1 distributes on the brush border membrane of enterocytes and the canalicular membrane of hepatocytes in humans. As the molecular target of ezetimibe, a hypocholesterolemic drug, its physiological and pathological significance has been recognized and intensively studied for years. Recently, plenty of new findings reveal the molecular mechanism of NPC1L1's role in cholesterol uptake, which may provide new insights on our understanding of cholesterol absorption. In this review, we summarized recent progress in these studies and proposed a working model, hoping to provide new perspectives on the regulation of cholesterol transport and metabolism.
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Yamanashi Y, Takada T, Shoda JI, Suzuki H. Novel function of Niemann-Pick C1-like 1 as a negative regulator of Niemann-Pick C2 protein. Hepatology 2012; 55:953-64. [PMID: 22095670 DOI: 10.1002/hep.24772] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 10/08/2011] [Indexed: 12/07/2022]
Abstract
UNLABELLED The hepatic expression of Niemann-Pick C1-like 1 (NPC1L1), which is a key molecule in intestinal cholesterol absorption, is high in humans. In addition to NPC1L1, Niemann-Pick C2 (NPC2), a secretory cholesterol-binding protein involved in intracellular cholesterol trafficking and the stimulation of biliary cholesterol secretion, is also expressed in the liver. In this study, we examined the molecular interaction and functional association between NPC1L1 and NPC2. In vitro studies with adenovirus-based or plasmid-mediated gene transfer systems revealed that NPC1L1 negatively regulated the protein expression and secretion of NPC2 without affecting the level of NPC2 messenger RNA. Experiments with small interfering RNA against NPC1L1 confirmed the endogenous association of these proteins. In addition, endocytosed NPC2 could compensate for the reduction of NPC2 in NPC1L1-overexpressing cells, and this demonstrated that the posttranscriptional regulation of NPC2 was dependent on a novel ability of NPC1L1 to inhibit the maturation of NPC2 and accelerate the degradation of NPC2 during its maturation. Furthermore, to confirm the physiological relevance of NPC1L1-mediated regulation, we analyzed human liver specimens and found a negative correlation between the protein levels of hepatic NPC1L1 and hepatic NPC2. CONCLUSION NPC1L1 down-regulates the expression and secretion of NPC2 by inhibiting its maturation and accelerating its degradation. NPC2 functions as a regulator of intracellular cholesterol trafficking and biliary cholesterol secretion; therefore, in addition to its role in cholesterol re-uptake from the bile by hepatocytes, hepatic NPC1L1 may control cholesterol homeostasis via the down-regulation of NPC2.
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Affiliation(s)
- Yoshihide Yamanashi
- Department of Pharmacy, University of Tokyo Hospital, Faculty of Medicine, University of Tokyo, Tokyo, Japan
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16
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Balboa E, Morales G, Aylwin P, Carrasco G, Amigo L, Castro J, Rigotti A, Zanlungo S. Niemann-Pick C2 protein expression regulates lithogenic diet-induced gallstone formation and dietary cholesterol metabolism in mice. Lipids 2011; 47:13-25. [PMID: 22038687 DOI: 10.1007/s11745-011-3625-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 10/11/2011] [Indexed: 12/21/2022]
Abstract
Niemann-Pick C2 protein (NPC2) is a lysosomal soluble protein that is highly expressed in the liver; it binds to cholesterol and is involved in intracellular cholesterol trafficking, allowing the exit of lysosomal cholesterol obtained via the lipoprotein endocytic pathway. Thus, this protein may play an important role in controlling hepatic cholesterol transport and metabolism. The aim of this work was to study the relevance of NPC2 protein expression in hepatic cholesterol metabolism, biliary lipid secretion and gallstone formation by comparing NPC2 hypomorph [NPC2 (h/h)] and wild-type mice fed control, 2% cholesterol, and lithogenic diets. NPC2 (h/h) mice exhibited resistance to a diet-induced increase in plasma cholesterol levels. When consuming the chow diet, we observed increased biliary cholesterol and phospholipid secretions in NPC2 (h/h) mice. When fed the 2% cholesterol diet, NPC2 (h/h) mice exhibited low and high gallbladder bile cholesterol and phospholipid concentrations, respectively. NPC2 (h/h) mice fed with the lithogenic diet showed reduced biliary cholesterol secretion, gallbladder bile cholesterol saturation, and cholesterol crystal and gallstone formation. This work indicates that hepatic NPC2 expression is an important factor in the regulation of diet-derived cholesterol metabolism and disposal as well as in diet-induced cholesterol gallstone formation in mice.
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Affiliation(s)
- Elisa Balboa
- Departmento de Gastroenterología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 367, Casilla 114-D, Santiago, Chile
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17
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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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18
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Kwon HJ, Palnitkar M, Deisenhofer J. The structure of the NPC1L1 N-terminal domain in a closed conformation. PLoS One 2011; 6:e18722. [PMID: 21525977 PMCID: PMC3078110 DOI: 10.1371/journal.pone.0018722] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 03/09/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND NPC1L1 is the molecular target of the cholesterol lowering drug Ezetimibe and mediates the intestinal absorption of cholesterol. Inhibition or deletion of NPC1L1 reduces intestinal cholesterol absorption, resulting in reduction of plasma cholesterol levels. PRINCIPAL FINDINGS Here we present the 2.8 Å crystal structure of the N-terminal domain (NTD) of NPC1L1 in the absence of cholesterol. The structure, combined with biochemical data, reveals the mechanism of cholesterol selectivity of NPC1L1. Comparison to the cholesterol free and bound structures of NPC1(NTD) reveals that NPC1L1(NTD) is in a closed conformation and the sterol binding pocket is occluded from solvent. CONCLUSION The structure of NPC1L1(NTD) reveals a degree of flexibility surrounding the entrance to the sterol binding pocket, suggesting a gating mechanism that relies on multiple movements around the entrance to the sterol binding pocket.
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Affiliation(s)
- Hyock Joo Kwon
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Maya Palnitkar
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Johann Deisenhofer
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
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19
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Pramfalk C, Jiang ZY, Cai Q, Hu H, Zhang SD, Han TQ, Eriksson M, Parini P. HNF1alpha and SREBP2 are important regulators of NPC1L1 in human liver. J Lipid Res 2010; 51:1354-62. [PMID: 20460578 DOI: 10.1194/jlr.m900274] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Niemann-Pick C1-like 1 (NPC1L1), a key regulator of intestinal cholesterol absorption, is highly expressed in human liver. Here, we aimed to gain more insight into mechanisms participating in its hepatic regulation in humans. Correlation analysis in livers from Chinese patients with and without gallstone disease revealed strong positive correlations between NPC1L1 and sterol regulatory element binding protein 2 (SREBP2) (r = 0.74, P < 0.05) and between NPC1L1 and hepatic nuclear factor alpha (HNF4alpha) (r = 0.53, P < 0.05) mRNA expression. HNF4alpha is an upstream regulator of HNF1alpha; thus, we also tested whether HNF1alpha participates in the regulation of NPC1L1. We showed a dose-dependent regulation by SREBP2 on the NPC1L1 promoter activity and mRNA expression in HuH7 cells. Chromatin immunoprecipitation assay confirmed the binding of SREBP2 to the promoter in vivo. Surprisingly, HNF4alpha slightly decreased the NPC1L1 promoter activity but had no effect on its gene expression. By contrast, HNF1alpha increased the promoter activity and the gene expression, and an important HNF1 binding site was identified within the human NPC1L1 promoter. ChIP assays confirmed that HNF1alpha can bind to the NPC1L1 promoter in vivo.
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Affiliation(s)
- Camilla Pramfalk
- Division of Clinical Chemistry, Department of Endocrinology, Karolinska Institutet, Karolinska University Hospital, Huddinge, S-141 86 Stockholm, Sweden
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20
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Morales MG, Amigo L, Balboa E, Acuña M, Castro J, Molina H, Miquel JF, Nervi F, Rigotti A, Zanlungo S. Deficiency of Niemann-Pick C1 protein protects against diet-induced gallstone formation in mice. Liver Int 2010; 30:887-97. [PMID: 20408952 DOI: 10.1111/j.1478-3231.2010.02230.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND/AIMS Receptor-mediated endocytosis is a critical cellular mechanism for the uptake of lipoprotein cholesterol in the liver. Because Niemann-Pick C1 (NPC1) protein is a key component for the intracellular distribution of cholesterol originating from lipoprotein endocytosis, it may play an important role in controlling biliary cholesterol secretion and gallstone formation induced by a lithogenic diet. METHODS We studied biliary cholesterol secretion, gallbladder lipid composition and gallstone formation in NPC1-deficient mice fed a low-fat lithogenic diet (1.5% cholesterol and 0.5% cholic acid) compared with control animals under the same diet. RESULTS The lipid secretion response to the lithogenic diet was impaired in NPC1 (-/-) mice, leading to a decreased cholesterol output and an increased hepatic cholesterol concentration compared with the lithogenic diet-fed wild-type mice. A decreased cholesterol saturation index was found in the gallbladder bile of NPC1 (+/-) and (-/-) mice after lithogenic diet feeding. Consequently, mice with a partial or a total deficiency of NPC1 had a drastically lower frequency of gallbladder cholesterol crystals and a reduced prevalence of gallstones. CONCLUSION Hepatic NPC1 expression is an important factor for regulating the biliary secretion of diet-derived cholesterol as well as for diet-induced cholesterol gallstone formation in mice.
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Affiliation(s)
- María Gabriela Morales
- Departamento de Gastroenterología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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21
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Pramfalk C, Jiang ZY, Cai Q, Hu H, Zhang SD, Han TQ, Eriksson M, Parini P. HNF1α and SREBP2 are important regulators of NPC1L1 in human liver. J Lipid Res 2010. [DOI: 10.1194/jlr.m900274-jlr200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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22
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Uronen RL, Lundmark P, Orho-Melander M, Jauhiainen M, Larsson K, Siegbahn A, Wallentin L, Zethelius B, Melander O, Syvänen AC, Ikonen E. Niemann-Pick C1 modulates hepatic triglyceride metabolism and its genetic variation contributes to serum triglyceride levels. Arterioscler Thromb Vasc Biol 2010; 30:1614-20. [PMID: 20489167 DOI: 10.1161/atvbaha.110.207191] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To study how Niemann-Pick disease type C1 (NPC1) influences hepatic triacylglycerol (TG) metabolism and to determine whether this is reflected in circulating lipid levels. METHODS AND RESULTS In Npc1(-/-) mice, the hepatic cholesterol content is increased but the TG content is decreased. We investigated lipid metabolism in Npc1(-/-) mouse hepatocytes and the association of NPC1 single-nucleotide polymorphisms with circulating TGs in humans. TGs were reduced in Npc1(-/-) mouse serum and hepatocytes. In Npc1(-/-) hepatocytes, the incorporation of [3H]oleic acid and [3H]acetate into TG was decreased, but shunting of oleic acid- or acetate-derived [3H]carbons into cholesterol was increased. Inhibition of cholesterol synthesis normalized TG synthesis, content, and secretion in Npc1(-/-) hepatocytes, suggesting increased hepatic cholesterol neogenesis as a cause for the reduced TG content and secretion. We found a significant association between serum TG levels and 5 common NPC1 single-nucleotide polymorphisms in a cohort of 1053 men, with the lowest P=8.7 x 10(-4) for the single-nucleotide polymorphism rs1429934. The association between the rs1429934 A allele and higher TG levels was replicated in 2 additional cohorts, which included 8041 individuals. CONCLUSIONS This study provides evidence of the following: (1) in mice, loss of NPC1 function reduces hepatocyte TG content and secretion by increasing the metabolic flux of carbons into cholesterol synthesis; and (2) common variation in NPC1 contributes to serum TG levels in humans.
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Sztolsztener ME, Strzelecka-Kiliszek A, Pikula S, Tylki-Szymanska A, Bandorowicz-Pikula J. Cholesterol as a factor regulating intracellular localization of annexin A6 in Niemann–Pick type C human skin fibroblasts. Arch Biochem Biophys 2010; 493:221-33. [DOI: 10.1016/j.abb.2009.11.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Revised: 10/27/2009] [Accepted: 11/02/2009] [Indexed: 11/25/2022]
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Dierks T, Schlotawa L, Frese MA, Radhakrishnan K, von Figura K, Schmidt B. Molecular basis of multiple sulfatase deficiency, mucolipidosis II/III and Niemann–Pick C1 disease — Lysosomal storage disorders caused by defects of non-lysosomal proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:710-25. [DOI: 10.1016/j.bbamcr.2008.11.015] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 11/11/2008] [Accepted: 11/24/2008] [Indexed: 12/11/2022]
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25
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Karten B, Peake KB, Vance JE. Mechanisms and consequences of impaired lipid trafficking in Niemann-Pick type C1-deficient mammalian cells. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:659-70. [PMID: 19416638 DOI: 10.1016/j.bbalip.2009.01.025] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Accepted: 01/20/2009] [Indexed: 11/18/2022]
Abstract
Niemann-Pick C disease is a fatal progressive neurodegenerative disorder caused in 95% of cases by mutations in the NPC1 gene; the remaining 5% of cases result from mutations in the NPC2 gene. The major biochemical manifestation of NPC1 deficiency is an abnormal sequestration of lipids, including cholesterol and glycosphingolipids, in late endosomes/lysosomes (LE/L) of all cells. In this review, we summarize the current knowledge of the NPC1 protein in mammalian cells with particular focus on how defects in NPC1 alter lipid trafficking and neuronal functions. NPC1 is a protein of LE/L and is predicted to contain thirteen transmembrane domains, five of which constitute a sterol-sensing domain. The precise function of NPC1, and the mechanism by which NPC1 and NPC2 (both cholesterol binding proteins) act together to promote the movement of cholesterol and other lipids out of the LE/L, have not yet been established. Recent evidence suggests that the sequestration of cholesterol in LE/L of cells of the brain (neurons and glial cells) contributes to the widespread death and dysfunction of neurons in the brain. Potential therapies include treatments that promote the removal of cholesterol and glycosphingolipids from LE/L. Currently, the most promising approach for extending life-span and improving the quality of life for NPC patients is a combination of several treatments each of which individually modestly slows disease progression.
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Affiliation(s)
- Barbara Karten
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
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26
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Davis HR, Altmann SW. Niemann-Pick C1 Like 1 (NPC1L1) an intestinal sterol transporter. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:679-83. [PMID: 19272334 DOI: 10.1016/j.bbalip.2009.01.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Revised: 01/06/2009] [Accepted: 01/06/2009] [Indexed: 01/02/2023]
Abstract
Niemann-Pick C1 Like 1 (NPC1L1) has been identified and characterized as an essential protein in the intestinal cholesterol absorption process. NPC1L1 localizes to the brush border membrane of absorptive enterocytes in the small intestine. Intestinal expression of NPC1L1 is down regulated by diets containing high levels of cholesterol. While otherwise phenotypically normal, Npc1l1 null mice exhibit a significant reduction in the intestinal uptake and absorption of cholesterol and phytosterols. Characterization of the NPC1L1 pathway revealed that cholesterol absorption inhibitor ezetimibe specifically binds to an extracellular loop of NPC1L1 and inhibits its sterol transport function. Npc1l1 null mice are resistant to diet-induced hypercholesterolemia, and when crossed with apo E null mice, are completely resistant to the development of atherosclerosis. Intestinal gene expression studies in Npc1l1 null mice indicated that no exogenous cholesterol was entering enterocytes lacking NPC1L1, which resulted in an upregulation of intestinal and hepatic LDL receptor and cholesterol biosynthetic gene expression. Polymorphisms in the human NPC1L1 gene have been found to influence cholesterol absorption and plasma low density lipoprotein levels. Therefore, NPC1L1 is a critical intestinal sterol uptake transporter which influences whole body cholesterol homeostasis.
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Affiliation(s)
- Harry R Davis
- Department of Cardiovascular/Metabolic Disease, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA.
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27
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Liu R, Lu P, Chu JWK, Sharom FJ. Characterization of fluorescent sterol binding to purified human NPC1. J Biol Chem 2008; 284:1840-52. [PMID: 19029290 DOI: 10.1074/jbc.m803741200] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in the NPC1 gene cause Niemann-Pick type C disease, which appears to result from a defect in intracellular cholesterol trafficking. NPC1 is a member of the resistance-nodulation-cell division (RND) permease superfamily and contains a sterol-sensing domain, yet its cellular function and the identity of its substrates remain unknown. FLAG-tagged human NPC1 was purified from NPC1-expressing Chinese hamster ovary cells by solubilization in 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS), followed by affinity chromatography. Purified NPC1 in detergent solution appeared to be oligomeric as determined by gel filtration fast protein liquid chromatography and was photolabeled by an azido-cholesterol derivative. Fluorescent cholesterol analogs, including dehydroergosterol, cholestatrienol, and 22-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-23,24-bisnor-5-cholen-3beta-ol (NBD-cholesterol), displayed enhanced fluorescence upon binding to NPC1 and also resulted in saturable, concentration-dependent quenching of NPC1 intrinsic Trp fluorescence. The apparent binding affinity for these three sterols was in the 0.5-6 microm range. Binding of NBD-cholesterol to NPC1 at low detergent concentration (2 mm CHAPS) was of high apparent affinity (0.5-0.6 microm) and occurred rapidly (<1 min). However, binding of a BODIPY-labeled cholesterol derivative was very slow, requiring approximately 3 h to reach equilibrium. The apparent NBD-cholesterol binding affinity was greatly reduced at higher detergent concentration. The stoichiometry of NBD-cholesterol binding to NPC1 was approximately 1. Various sterols, including native cholesterol and 25-hydroxycholesterol, inhibited NBD-cholesterol binding, suggesting that they compete for binding to the protein. Dynamic quenching studies showed that bound NBD-cholesterol was almost completely shielded from the aqueous medium, suggesting that it is buried in a deep hydrophobic pocket in NPC1. The use of fluorescent cholesterol analogs provides novel information on the molecular properties of the sterol-binding site in the full-length NPC1 protein.
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Affiliation(s)
- Ronghua Liu
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Davis HR, Basso F, Hoos LM, Tetzloff G, Lally SM, Altmann SW. Cholesterol homeostasis by the intestine: lessons from Niemann-Pick C1 Like 1 [NPC1L1). ATHEROSCLEROSIS SUPP 2008; 9:77-81. [PMID: 18585981 DOI: 10.1016/j.atherosclerosissup.2008.05.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 02/14/2008] [Accepted: 05/13/2008] [Indexed: 01/07/2023]
Abstract
Ezetimibe is a selective cholesterol absorption inhibitor, which potently inhibits the uptake and absorption of biliary and dietary cholesterol from the small intestine without affecting the absorption of fat-soluble vitamins, triglycerides or bile acids. Identification and characterization of Niemann-Pick C1 Like 1 (NPC1L1) has established NPC1L1 as an essential protein in the intestinal cholesterol absorption process. While otherwise phenotypically normal, Npc1l1 null mice exhibit a significant reduction in the intestinal uptake and absorption of cholesterol and phytosterols. Characterization of the NPC1L1 pathway revealed that ezetimibe specifically binds to NPC1L1 and inhibits its sterol transport function. Npc1l1 null mice were resistant to diet-induced hypercholesterolemia, and when crossed with apoE null mice, were completely resistant to the development of atherosclerosis. In Npc1l1/apoE null mice or apoE null mice treated with ezetimibe plasma cholesterol levels were reduced primarily in the apoB48 containing chylomicron remnant lipoproteins relative to untreated apoE null mice. SR-B1 has been proposed to play a role in intestinal cholesterol uptake, but in Npc1l1/SR-B1 double null mice intestinal cholesterol absorption was not different than Npc1l1 null alone mice. Therefore, NPC1L1 is the critical intestinal sterol transporter which influences whole body cholesterol homeostasis, and is the molecular target of ezetimibe.
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Affiliation(s)
- Harry R Davis
- Department of Cardiovascular/Metabolic Disease, Schering-Plough Research Institute, K15-2-2600, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA.
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Abstract
Cholesterol is an essential structural component in the cell membranes of most vertebrates. The biophysical properties of cholesterol and the enzymology of cholesterol metabolism provide the basis for how cells handle cholesterol and exchange it with one another. A tightly controlled--but only partially characterized--network of cellular signalling and lipid transfer systems orchestrates the functional compartmentalization of this lipid within and between organellar membranes. This largely dictates the exchange of cholesterol between tissues at the whole body level. Increased understanding of these processes and their integration at the organ systems level provides fundamental insights into the physiology of cholesterol trafficking.
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Affiliation(s)
- Elina Ikonen
- Institute of Biomedicine/Anatomy, University of Helsinki, Haartmaninkatu 8, University of Helsinki, Helsinki FI-00014, Finland.
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Abstract
Niemann-Pick C1-like 1 (NPC1L1) has recently been identified and has been shown to have features of a plasma membrane transporter, including a secretion signal, 13 predicted transmembrane domains, extensive N-linked glycosylation sites and a sterol-sensing domain. It is highly expressed on the surface of absorptive jejunal enterocytes. NPC1L1 has been shown to be a direct target of ezetimibe, and an ezetimibe-sensitive pathway plays a role in intestinal cholesterol absorption. Ezetimibe-based therapy represents an exciting new area in the treatment of dyslipidemia.
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Affiliation(s)
- Shin-ichiro Miura
- Department of Cardiology, Fukuoka University School of Medicine, Fukuoka, Japan
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31
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A role for NPC1 and NPC2 in intestinal cholesterol absorption--the hypothesis gutted. Biochem J 2007; 408:e1-3. [PMID: 17956226 DOI: 10.1042/bj20071340] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Dietary and biliary cholesterol are taken up by intestinal epithelial cells and transported to the endoplasmic reticulum. At the endoplasmic reticulum, cholesterol is esterified, packaged into chylomicrons and secreted into the lymph for delivery to the bloodstream. NPC1L1 (Niemann-Pick C1-like 1) is a protein on the enterocyte brush-border membrane that facilitates cholesterol absorption. Cholesterol's itinerary as it moves to the endoplasmic reticulum is unknown, as is the identity of any cellular proteins that facilitate the movement. Two proteins that play an important role in intracellular cholesterol transport and could potentially influence NPC1L1-mediated cholesterol uptake are NPC1 and NPC2 (Niemann-Pick type C disease proteins 1 and 2). In this issue of the Biochemical Journal, Dixit and colleagues show that the absence or presence of NPC1 and NPC2 has no effect on intestinal cholesterol absorption in the mouse. Thus neither protein fills the gap in our knowledge of intra-enterocyte cholesterol transport. Furthermore, the NPC1/NPC2 pathway would not be a good target for limiting the uptake of dietary cholesterol.
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