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Husain MA, Laurent B, Plourde M. APOE and Alzheimer's Disease: From Lipid Transport to Physiopathology and Therapeutics. Front Neurosci 2021; 15:630502. [PMID: 33679311 PMCID: PMC7925634 DOI: 10.3389/fnins.2021.630502] [Citation(s) in RCA: 111] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/20/2021] [Indexed: 12/23/2022] Open
Abstract
Alzheimer’s disease (AD) is a devastating neurodegenerative disorder characterized by extracellular amyloid β (Aβ) and intraneuronal tau protein aggregations. One risk factor for developing AD is the APOE gene coding for the apolipoprotein E protein (apoE). Humans have three versions of APOE gene: ε2, ε3, and ε4 allele. Carrying the ε4 allele is an AD risk factor while carrying the ε2 allele is protective. ApoE is a component of lipoprotein particles in the plasma at the periphery, as well as in the cerebrospinal fluid (CSF) and in the interstitial fluid (ISF) of brain parenchyma in the central nervous system (CNS). ApoE is a major lipid transporter that plays a pivotal role in the development, maintenance, and repair of the CNS, and that regulates multiple important signaling pathways. This review will focus on the critical role of apoE in AD pathogenesis and some of the currently apoE-based therapeutics developed in the treatment of AD.
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Affiliation(s)
- Mohammed Amir Husain
- Centre de Recherche Sur le Vieillissement, Centre Intégré Universitaire de Santé et Services Sociaux de l'Estrie-Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada.,Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Benoit Laurent
- Centre de Recherche Sur le Vieillissement, Centre Intégré Universitaire de Santé et Services Sociaux de l'Estrie-Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada.,Département de Biochimie et Génomique Fonctionnelle, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Mélanie Plourde
- Centre de Recherche Sur le Vieillissement, Centre Intégré Universitaire de Santé et Services Sociaux de l'Estrie-Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada.,Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
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ApoE Lipidation as a Therapeutic Target in Alzheimer's Disease. Int J Mol Sci 2020; 21:ijms21176336. [PMID: 32882843 PMCID: PMC7503657 DOI: 10.3390/ijms21176336] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 08/28/2020] [Accepted: 08/30/2020] [Indexed: 12/19/2022] Open
Abstract
Apolipoprotein E (APOE) is the major cholesterol carrier in the brain, affecting various normal cellular processes including neuronal growth, repair and remodeling of membranes, synaptogenesis, clearance and degradation of amyloid β (Aβ) and neuroinflammation. In humans, the APOE gene has three common allelic variants, termed E2, E3, and E4. APOE4 is considered the strongest genetic risk factor for Alzheimer’s disease (AD), whereas APOE2 is neuroprotective. To perform its normal functions, apoE must be secreted and properly lipidated, a process influenced by the structural differences associated with apoE isoforms. Here we highlight the importance of lipidated apoE as well as the APOE-lipidation targeted therapeutic approaches that have the potential to correct or prevent neurodegeneration. Many of these approaches have been validated using diverse cellular and animal models. Overall, there is great potential to improve the lipidated state of apoE with the goal of ameliorating APOE-associated central nervous system impairments.
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Zorec R, Parpura V, Vardjan N, Verkhratsky A. Astrocytic face of Alzheimer’s disease. Behav Brain Res 2017; 322:250-257. [DOI: 10.1016/j.bbr.2016.05.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 04/16/2016] [Accepted: 05/08/2016] [Indexed: 10/21/2022]
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4
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Rames M, Yu Y, Ren G. Optimized negative staining: a high-throughput protocol for examining small and asymmetric protein structure by electron microscopy. J Vis Exp 2014:e51087. [PMID: 25145703 PMCID: PMC4710468 DOI: 10.3791/51087] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Structural determination of proteins is rather challenging for proteins with molecular masses between 40 - 200 kDa. Considering that more than half of natural proteins have a molecular mass between 40 - 200 kDa1,2, a robust and high-throughput method with a nanometer resolution capability is needed. Negative staining (NS) electron microscopy (EM) is an easy, rapid, and qualitative approach which has frequently been used in research laboratories to examine protein structure and protein-protein interactions. Unfortunately, conventional NS protocols often generate structural artifacts on proteins, especially with lipoproteins that usually form presenting rouleaux artifacts. By using images of lipoproteins from cryo-electron microscopy (cryo-EM) as a standard, the key parameters in NS specimen preparation conditions were recently screened and reported as the optimized NS protocol (OpNS), a modified conventional NS protocol 3 . Artifacts like rouleaux can be greatly limited by OpNS, additionally providing high contrast along with reasonably high‐resolution (near 1 nm) images of small and asymmetric proteins. These high-resolution and high contrast images are even favorable for an individual protein (a single object, no average) 3D reconstruction, such as a 160 kDa antibody, through the method of electron tomography4,5. Moreover, OpNS can be a high‐throughput tool to examine hundreds of samples of small proteins. For example, the previously published mechanism of 53 kDa cholesteryl ester transfer protein (CETP) involved the screening and imaging of hundreds of samples 6. Considering cryo-EM rarely successfully images proteins less than 200 kDa has yet to publish any study involving screening over one hundred sample conditions, it is fair to call OpNS a high-throughput method for studying small proteins. Hopefully the OpNS protocol presented here can be a useful tool to push the boundaries of EM and accelerate EM studies into small protein structure, dynamics and mechanisms.
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Affiliation(s)
- Matthew Rames
- Lawrence Berkeley National Laboratory, The Molecular Foundry
| | - Yadong Yu
- Lawrence Berkeley National Laboratory, The Molecular Foundry
| | - Gang Ren
- Lawrence Berkeley National Laboratory, The Molecular Foundry;
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Garewal M, Zhang L, Ren G. Optimized negative-staining protocol for examining lipid-protein interactions by electron microscopy. Methods Mol Biol 2013; 974:111-8. [PMID: 23404274 PMCID: PMC10546916 DOI: 10.1007/978-1-62703-275-9_6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A large number of proteins are capable of inserting themselves into lipids, and interacting with membranes, such as transmembrane proteins and apolipoproteins. Protein-lipid interactions have been identified as one of the keys in understanding biological processes, while the structure of proteins at the lipid-binding stage can provide evidence to help identify their roles and critical functions. However, structure determination of proteins at the lipid-binding stage is rather difficult, because conformational and compositional heterogeneities of the protein-lipid complexes are major barriers to unravel their structures using traditional methods, such as X-ray crystallography. Electron microscopy (EM) is an alternative approach to determine protein structure and has demonstrated a capability in visualizing lipid-protein interactions directly. Among various EM techniques, negative-staining (NS) is an easy, rapid, qualitative approach that is a well-established technique, frequently used in research laboratories. Conventional NS protocols, unfortunately, often generate artifacts with lipid-related proteins, such as the rouleau formation of lipoproteins. To overcome this artifact formation, Ren and his colleagues recently developed an optimized NS protocol that was validated by comparing images of lipoproteins from cryo-electron microscopy (cryo-EM). The optimized NS protocol could produce "near native-state" particle images and high contrast images of the protein in its lipid-binding state that is favorable for three-dimensional (3D) reconstruction by single-particle analysis and individual-particle electron tomography (IPET), suggesting this optimized protocol can be used widely to examine the structure of proteins at lipid-binding stage.
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Affiliation(s)
- Mark Garewal
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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Zhang L, Tong H, Garewal M, Ren G. Optimized negative-staining electron microscopy for lipoprotein studies. Biochim Biophys Acta Gen Subj 2012; 1830:2150-9. [PMID: 23032862 DOI: 10.1016/j.bbagen.2012.09.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Revised: 09/20/2012] [Accepted: 09/23/2012] [Indexed: 12/16/2022]
Abstract
BACKGROUND Negative-staining (NS), a rapid, simple and conventional technique of electron microscopy (EM), has been commonly used to initially study the morphology and structure of proteins for half a century. Certain NS protocols however can cause artifacts, especially for structurally flexible or lipid-related proteins, such as lipoproteins. Lipoproteins were often observed in the form of rouleau as lipoprotein particles appeared to be stacked together by conventional NS protocols. The flexible components of lipoproteins, i.e. lipids and amphipathic apolipoproteins, resulted in the lipoprotein structure being sensitive to the NS sample preparation parameters, such as operational procedures, salt concentrations, and the staining reagents. SCOPE OF REVIEW The most popular NS protocols that have been used to examine lipoprotein morphology and structure were reviewed. MAJOR CONCLUSIONS The comparisons show that an optimized NS (OpNS) protocol can eliminate the rouleau artifacts of lipoproteins, and that the lipoproteins are similar in size and shape as statistically measured from two EM methods, OpNS and cryo-electron microscopy (cryo-EM). OpNS is a high-throughput, high-contrast and high-resolution (near 1nm, but rarely better than 1nm) method which has been used to discover the mechanics of a small protein, 53kDa cholesterol ester transfer protein (CETP), and the structure of an individual particle of a single protein by individual-particle electron tomography (IPET), i.e. a 14Å-resolution IgG antibody three-dimensional map. GENERAL SIGNIFICANCE It is suggested that OpNS can be used as a general protocol to study the structure of proteins, especially highly dynamic proteins with equilibrium-fluctuating structures.
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Affiliation(s)
- Lei Zhang
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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Sato K, Malchinkhuu E, Horiuchi Y, Mogi C, Tomura H, Tosaka M, Yoshimoto Y, Kuwabara A, Okajima F. Critical role of ABCA1 transporter in sphingosine 1-phosphate release from astrocytes. J Neurochem 2011; 103:2610-9. [PMID: 17931360 DOI: 10.1111/j.1471-4159.2007.04958.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sphingosine 1-phosphate (S1P) is accumulated in lipoproteins, especially high-density lipoprotein (HDL), in plasma. However, it remains uncharacterized how extracellular S1P is produced in the CNS. The treatment of rat astrocytes with retinoic acid and dibutyryl cAMP, which induce apolipoprotein E (apoE) synthesis and HDL-like lipoprotein formation, stimulated extracellular S1P accumulation in the presence of its precursor sphingosine. The released S1P was present together with apoE particles in the HDL fraction. S1P release from astrocytes was inhibited by the treatment of the cells with glybenclamide or small interfering RNAs specific to ATP-binding cassette transporter A1 (ABCA1). Astrocytes from Abca1-/- mice also showed impairment of retinoic acid/dibutyryl cAMP-induced S1P release in association with the blockage of HDL-like lipoprotein formation. However, the formation of either apoE or lipoprotein itself was not sufficient, and additional up-regulation of ABCA1 was requisite to stimulate S1P release. We conclude that the S1P release from astrocytes is coupled with lipoprotein formation through ABCA1.
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Affiliation(s)
- Koichi Sato
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan.
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Pfrieger FW, Ungerer N. Cholesterol metabolism in neurons and astrocytes. Prog Lipid Res 2011; 50:357-71. [PMID: 21741992 DOI: 10.1016/j.plipres.2011.06.002] [Citation(s) in RCA: 316] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 06/11/2011] [Accepted: 06/22/2011] [Indexed: 12/20/2022]
Abstract
Cells in the mammalian body must accurately maintain their content of cholesterol, which is an essential membrane component and precursor for vital signalling molecules. Outside the brain, cholesterol homeostasis is guaranteed by a lipoprotein shuttle between the liver, intestine and other organs via the blood circulation. Cells inside the brain are cut off from this circuit by the blood-brain barrier and must regulate their cholesterol content in a different manner. Here, we review how this is accomplished by neurons and astrocytes, two cell types of the central nervous system, whose cooperation is essential for normal brain development and function. The key observation is a remarkable cell-specific distribution of proteins that mediate different steps of cholesterol metabolism. This form of metabolic compartmentalization identifies astrocytes as net producers of cholesterol and neurons as consumers with unique means to prevent cholesterol overload. The idea that cholesterol turnover in neurons depends on close cooperation with astrocytes raises new questions that need to be addressed by new experimental approaches to monitor and manipulate cholesterol homeostasis in a cell-specific manner. We conclude that an understanding of cholesterol metabolism in the brain and its role in disease requires a close look at individual cell types.
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Affiliation(s)
- Frank W Pfrieger
- CNRS UPR 3212, University of Strasbourg, Institute of Cellular and Integrative Neurosciences (INCI), 67084 Strasbourg Cedex, France.
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9
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Astrocytic Responses to DNA Delivery Using Nucleofection. Neurochem Res 2010; 35:1771-9. [DOI: 10.1007/s11064-010-0243-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/03/2010] [Indexed: 01/10/2023]
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10
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Zhang L, Song J, Newhouse Y, Zhang S, Weisgraber KH, Ren G. An optimized negative-staining protocol of electron microscopy for apoE4 POPC lipoprotein. J Lipid Res 2009; 51:1228-36. [PMID: 19965615 PMCID: PMC2853450 DOI: 10.1194/jlr.d002493] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Apolipoprotein E (apoE), one of the major protein components of lipoproteins in the peripheral and central nervous systems, regulates cholesterol metabolism through its interaction with members of the low density lipoprotein receptor family. One key to understanding apoE function is determining the structure of lipid-bound forms of apoE. Negative-staining (NS) electron microscopy (EM) is an easy and rapid approach for studying the structure and morphology of lipid-bound forms of apoE. However, an artifact of using the conventional NS protocol is that the apoE•phospholipid particles form rouleaux. In this study, we used cryo-electron microscopy (cryo-EM) to examine apoE4•palmitoyl-oleoylphosphatidylcholine (POPC) particles in a frozen-hydrated native state. By comparing the particle sizes and shapes produced by different NS protocols to those produced by cryo-EM, we propose an optimized protocol to examine apoE4•POPC particles. Statistical analysis demonstrated that the particle sizes differ by less than 5% between the optimized protocol and the cryo-EM method, with similar shapes. The high contrast and fine detail of particle images produced using this optimized protocol lend themselves to the structural study of lipid-bound forms of apoE.
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Affiliation(s)
- Lei Zhang
- Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China
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11
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Teter B. Life-span influences of apoE4 on CNS function. Neurobiol Aging 2007; 28:693-703; discussion 704-6. [PMID: 17045362 DOI: 10.1016/j.neurobiolaging.2006.06.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 06/22/2006] [Indexed: 11/20/2022]
Affiliation(s)
- Bruce Teter
- Department of Medicine SFVP, University of California, Los Angeles and Veteran's Administration-GLAHS, Sepulveda VA Medical Center, mc 151, 16111 Plummer St., Sepulveda, CA 91343, United States.
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12
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Chuu CP, Kokontis JM, Hiipakka RA, Liao S. Modulation of liver X receptor signaling as novel therapy for prostate cancer. J Biomed Sci 2007; 14:543-53. [PMID: 17372849 DOI: 10.1007/s11373-007-9160-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Accepted: 02/26/2007] [Indexed: 10/23/2022] Open
Abstract
Liver X receptors (LXRs) are important regulators of cholesterol, fatty acid, and glucose homeostasis. LXR agonists are effective for treatment of murine models of atherosclerosis, diabetes, and Alzheimer's disease. Recently we observed that LXR agonists suppressed proliferation of prostate and breast cancer cells in vitro and treatment of mice with the LXR agonist T0901317 suppressed the growth of prostate tumor xenografts. LXR agonists appear to cause G1 cell cycle arrest in cells by reducing expression of Skp2 and inducing the accumulation of p27(Kip). T0901317 induced expression of ATP-binding cassette transporter A1 (ABCA1) and delayed the progression of androgen-dependent human prostate tumor xenografts towards androgen-independency in mice. Phytosterols, the plant equivalent of mammalian cholesterol, have recently been shown to be agonists for LXRs. beta-Sitosterol and campesterol, the two most common phytosterols, suppressed proliferation of prostate and breast cancer cells. The anticancer activity of phytosterols may be due to LXR signaling. This review examines the potential use of LXR signaling as a therapeutic target in prostate and other cancers.
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Affiliation(s)
- Chih-Pin Chuu
- The Ben May Department for Cancer Research, The University of Chicago, 929 East 57th Street, CIS W325F, Chicago, IL 60637, USA
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LaDu MJ, Stine WB, Narita M, Getz GS, Reardon CA, Bu G. Self-assembly of HEK cell-secreted ApoE particles resembles ApoE enrichment of lipoproteins as a ligand for the LDL receptor-related protein. Biochemistry 2006; 45:381-90. [PMID: 16401069 PMCID: PMC2564845 DOI: 10.1021/bi051765s] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent studies have shown that the lipidation and assembly state of apolipoprotein E (apoE) determine receptor recognition and amyloid-beta peptide (Abeta) binding. We previously demonstrated that apoE secreted by HEK cells stably expressing apoE3 or apoE4 (HEK-apoE) binds Abeta and inhibits Abeta-induced neurotoxicity by an isoform-specific process that requires apoE receptors. Here we characterized the structure of HEK-apoE assemblies and determined their receptor binding specificity. By chromatography, HEK-apoE elutes in high molecular mass fractions and is the size of plasma HDL, consistent with a multiprotein assembly. No lipid was associated with these apoE assemblies. Several methods for analyzing receptor binding indicate that HEK-apoE is a ligand for low-density lipoprotein (LDL) receptor-related protein (LRP) but not the LDL receptor. This suggests that self-assembly of apoE may induce a functional conformation necessary for binding to LRP. Our results indicate that, in addition to lipid content, the assembly state of apoE influences Abeta binding and receptor recognition.
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Affiliation(s)
- Mary Jo LaDu
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois 60612, USA
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Karten B, Hayashi H, Francis G, Campenot R, Vance D, Vance J. Generation and function of astroglial lipoproteins from Niemann-Pick type C1-deficient mice. Biochem J 2005; 387:779-88. [PMID: 15544574 PMCID: PMC1135009 DOI: 10.1042/bj20041694] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2004] [Revised: 11/01/2004] [Accepted: 11/15/2004] [Indexed: 11/17/2022]
Abstract
NPC (Niemann-Pick type C) disease is a progressive neurological disorder characterized by defects in intracellular cholesterol trafficking, accumulation of cholesterol in the endosomal system and impaired cholesterol homoeostasis. Although these alterations appear to occur in all NPC1-deficient cell types, the consequences are most profound in the nervous system. Since glial cells are important mediators of brain cholesterol homoeostasis, we proposed that defective generation and/or function of lipoproteins released by glia might contribute to the neurological abnormalities associated with NPC disease. We found that, as in other cell types, Npc1-/- glia accumulate cholesterol intracellularly. We hypothesized that this sequestration of cholesterol in glia might restrict the availability of cholesterol for lipoprotein production. Cerebellar astroglia were cultured from a murine model of NPC disease to compare the lipoproteins generated by these cells and wild-type glia. The experiments demonstrate that the amount of cholesterol in glia-conditioned medium is not reduced by NPC1 deficiency. Similarly, cholesterol efflux to apo (apolipoprotein) A1 or glial expression of the transporter ATP-binding-cassette transporter A1 was not decreased by NPC1 deficiency. In addition, the ratio of apo E:cholesterol and the density distribution of lipoproteins in Npc1-/- and Npc1+/+ glia-conditioned medium are indistinguishable. Importantly, in a functional assay, apo E-containing lipoproteins generated by Npc1-/- and Npc1+/+ glia each stimulate axonal elongation of neurons by approx. 35%. On the basis of these observations, we speculate that the neuropathology characteristic of NPC disease can quite probably be ascribed to impaired processes within neurons in the brain rather than defective lipoprotein production by astroglia.
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Key Words
- apo a1
- apo e
- astroglia
- cholesterol secretion
- glial lipoprotein
- niemann–pick type c disease
- abc transporter, atp-binding-cassette transporter
- apo, apolipoprotein
- cns, central nervous system
- csf, cerebrospinal fluid
- dmem, dulbecco's modified eagle's medium
- fbs, fetal bovine serum
- gfap, glial fibrillary acidic protein
- hdl, high-density lipoproteins
- ldl, low-density lipoprotein
- vldl, very low density lipoprotein
- npc, niemann–pick type c
- rgc, retinal ganglion cells
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Affiliation(s)
- Barbara Karten
- *Canadian Institutes of Health Research Group on the Molecular and Cell Biology of Lipids, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
- †Department of Medicine, University of Alberta, Edmonton, AB, Canada T6G 2S2
| | - Hideki Hayashi
- *Canadian Institutes of Health Research Group on the Molecular and Cell Biology of Lipids, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
- †Department of Medicine, University of Alberta, Edmonton, AB, Canada T6G 2S2
| | - Gordon A. Francis
- *Canadian Institutes of Health Research Group on the Molecular and Cell Biology of Lipids, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
- †Department of Medicine, University of Alberta, Edmonton, AB, Canada T6G 2S2
- ‡Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
| | - Robert B. Campenot
- §Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
| | - Dennis E. Vance
- *Canadian Institutes of Health Research Group on the Molecular and Cell Biology of Lipids, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
- ‡Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
| | - Jean E. Vance
- *Canadian Institutes of Health Research Group on the Molecular and Cell Biology of Lipids, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
- †Department of Medicine, University of Alberta, Edmonton, AB, Canada T6G 2S2
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Liu Y, Yang L, Conde-Knape K, Beher D, Shearman MS, Shachter NS. Fatty acids increase presenilin-1 levels and γ-secretase activity in PSwt-1 cells. J Lipid Res 2004; 45:2368-76. [PMID: 15375184 DOI: 10.1194/jlr.m400317-jlr200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Presenilin-1 (PS1) is an important determinant of the gamma-secretase activity necessary for the generation of beta-amyloid (Abeta), likely the central pathogenic molecule in Alzheimer's disease. Most presenilin is rapidly degraded, and determinants of the level of the active cleaved form are unknown. We examined the influence of fatty acids on PS1 levels and gamma-secretase activity using stably transfected CHO cells that express human PS1 and the human amyloid precursor protein. Cells cultured with 0.4 mM oleic acid (OA), with 0.1 mM linoleic acid, or with a triglyceride emulsion expressed increased PS1 and Abeta. This effect was independent of any secondary increase in cellular cholesterol. Cells cultured in 0.4 mM OA also exhibited significantly increased gamma-secretase activity. PS1 mRNA levels were unchanged, and pulse-chase experiments indicated that OA slowed presenilin holoprotein degradation. Nontransfected human neuroblastoma cells also showed increased presenilin when cultured in 0.4 mM OA. Lipids may be important biological determinants of PS1 level and gamma-secretase activity.
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Affiliation(s)
- Yanzhu Liu
- Department of Medicine, Columbia University, New York, NY, USA
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