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Yang LG, March ZM, Stephenson RA, Narayan PS. Apolipoprotein E in lipid metabolism and neurodegenerative disease. Trends Endocrinol Metab 2023:S1043-2760(23)00092-9. [PMID: 37357100 PMCID: PMC10365028 DOI: 10.1016/j.tem.2023.05.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/05/2023] [Accepted: 05/09/2023] [Indexed: 06/27/2023]
Abstract
Dysregulation of lipid metabolism has emerged as a central component of many neurodegenerative diseases. Variants of the lipid transport protein, apolipoprotein E (APOE), modulate risk and resilience in several neurodegenerative diseases including late-onset Alzheimer's disease (LOAD). Allelic variants of the gene, APOE, alter the lipid metabolism of cells and tissues and have been broadly associated with several other cellular and systemic phenotypes. Targeting APOE-associated metabolic pathways may offer opportunities to alter disease-related phenotypes and consequently, attenuate disease risk and impart resilience to multiple neurodegenerative diseases. We review the molecular, cellular, and tissue-level alterations to lipid metabolism that arise from different APOE isoforms. These changes in lipid metabolism could help to elucidate disease mechanisms and tune neurodegenerative disease risk and resilience.
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Affiliation(s)
- Linda G Yang
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, MD, USA
| | - Zachary M March
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, MD, USA
| | - Roxan A Stephenson
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, MD, USA
| | - Priyanka S Narayan
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, MD, USA.; National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Bethesda, MD, USA; Center for Alzheimer's and Related Dementias (CARD), National Institutes of Health, Bethesda, MD, USA.
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2
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Kacher R, Mounier C, Caboche J, Betuing S. Altered Cholesterol Homeostasis in Huntington’s Disease. Front Aging Neurosci 2022; 14:797220. [PMID: 35517051 PMCID: PMC9063567 DOI: 10.3389/fnagi.2022.797220] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 03/18/2022] [Indexed: 12/25/2022] Open
Abstract
Huntington’s disease (HD) is an autosomal dominant genetic disorder caused by an expansion of the CAG repeat in the first exon of Huntingtin’s gene. The associated neurodegeneration mainly affects the striatum and the cortex at early stages and progressively spreads to other brain structures. Targeting HD at its earlier stages is under intense investigation. Numerous drugs were tested, with a rate of success of only 3.5% approved molecules used as symptomatic treatment. The restoration of cholesterol metabolism, which is central to the brain homeostasis and strongly altered in HD, could be an interesting disease-modifying strategy. Cholesterol is an essential membrane component in the central nervous system (CNS); alterations of its homeostasis have deleterious consequences on neuronal functions. The levels of several sterols, upstream of cholesterol, are markedly decreased within the striatum of HD mouse model. Transcription of cholesterol biosynthetic genes is reduced in HD cell and mouse models as well as post-mortem striatal and cortical tissues from HD patients. Since the dynamic of brain cholesterol metabolism is complex, it is essential to establish the best method to target it in HD. Cholesterol, which does not cross the blood-brain-barrier, is locally synthesized and renewed within the brain. All cell types in the CNS synthesize cholesterol during development but as they progress through adulthood, neurons down-regulate their cholesterol synthesis and turn to astrocytes for their full supply. Cellular levels of cholesterol reflect the dynamic balance between synthesis, uptake and export, all integrated into the context of the cross talk between neurons and glial cells. In this review, we describe the latest advances regarding the role of cholesterol deregulation in neuronal functions and how this could be a determinant factor in neuronal degeneration and HD progression. The pathways and major mechanisms by which cholesterol and sterols are regulated in the CNS will be described. From this overview, we discuss the main clinical strategies for manipulating cholesterol metabolism in the CNS, and how to reinstate a proper balance in HD.
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Affiliation(s)
- Radhia Kacher
- Institut du Cerveau - Paris Brain Institute (ICM), AP-HP, INSERM, CNRS, University Hospital Pitié-Salpêtrière, Sorbonne Université, Paris, France
- INSERM, U1216, Grenoble Institut Neurosciences, Université Grenoble Alpes, Grenoble, France
| | - Coline Mounier
- Neuroscience Paris Seine, Institut de Biologie Paris-Seine, Faculté des Sciences et Ingénierie, Sorbonne Université, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Paris, France
- U1130, Institut National de la Santé et de la Recherche Médicale, Paris, France
| | - Jocelyne Caboche
- Neuroscience Paris Seine, Institut de Biologie Paris-Seine, Faculté des Sciences et Ingénierie, Sorbonne Université, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Paris, France
- U1130, Institut National de la Santé et de la Recherche Médicale, Paris, France
| | - Sandrine Betuing
- Neuroscience Paris Seine, Institut de Biologie Paris-Seine, Faculté des Sciences et Ingénierie, Sorbonne Université, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Paris, France
- U1130, Institut National de la Santé et de la Recherche Médicale, Paris, France
- *Correspondence: Sandrine Betuing,
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3
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Navas Guimaraes M, Lopez-Blanco R, Correa J, Fernandez-Villamarin M, Bistué MB, Martino-Adami P, Morelli L, Kumar V, Wempe MF, Cuello AC, Fernandez-Megia E, Bruno MA. Liver X Receptor Activation with an Intranasal Polymer Therapeutic Prevents Cognitive Decline without Altering Lipid Levels. ACS NANO 2021; 15:4678-4687. [PMID: 33666411 PMCID: PMC8488954 DOI: 10.1021/acsnano.0c09159] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The progressive accumulation of amyloid-beta (Aβ) in specific areas of the brain is a common prelude to late-onset of Alzheimer's disease (AD). Although activation of liver X receptors (LXR) with agonists decreases Aβ levels and ameliorates contextual memory deficit, concomitant hypercholesterolemia/hypertriglyceridemia limits their clinical application. DMHCA (N,N-dimethyl-3β-hydroxycholenamide) is an LXR partial agonist that, despite inducing the expression of apolipoprotein E (main responsible of Aβ drainage from the brain) without increasing cholesterol/triglyceride levels, shows nil activity in vivo because of a low solubility and inability to cross the blood brain barrier. Herein, we describe a polymer therapeutic for the delivery of DMHCA. The covalent incorporation of DMHCA into a PEG-dendritic scaffold via carboxylate esters produces an amphiphilic copolymer that efficiently self-assembles into nanometric micelles that exert a biological effect in primary cultures of the central nervous system (CNS) and experimental animals using the intranasal route. After CNS biodistribution and effective doses of DMHCA micelles were determined in nontransgenic mice, a transgenic AD-like mouse model of cerebral amyloidosis was treated with the micelles for 21 days. The benefits of the treatment included prevention of memory deterioration and a significant reduction of hippocampal Aβ oligomers without affecting plasma lipid levels. These results represent a proof of principle for further clinical developments of DMHCA delivery systems.
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Affiliation(s)
- María
Eugenia Navas Guimaraes
- Instituto
de Ciencias Biomédicas, Facultad de Ciencias Médicas, Universidad Católica de Cuyo, Av. José Ignacio de la Roza
1516, Rivadavia, 5400, San Juan, Argentina
- National
Council of Scientific and Technical Research (CONICET), Godoy Cruz 2290, C1425FQB Ciudad Autónoma de Buenos Aires Argentina
| | - Roi Lopez-Blanco
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CIQUS) and Departamento de Química
Orgánica, Universidade de Santiago
de Compostela, Jenaro de la Fuente s/n, 15782 Santiago de Compostela, Spain
| | - Juan Correa
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CIQUS) and Departamento de Química
Orgánica, Universidade de Santiago
de Compostela, Jenaro de la Fuente s/n, 15782 Santiago de Compostela, Spain
| | - Marcos Fernandez-Villamarin
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CIQUS) and Departamento de Química
Orgánica, Universidade de Santiago
de Compostela, Jenaro de la Fuente s/n, 15782 Santiago de Compostela, Spain
| | - María Beatriz Bistué
- Instituto
de Ciencias Biomédicas, Facultad de Ciencias Médicas, Universidad Católica de Cuyo, Av. José Ignacio de la Roza
1516, Rivadavia, 5400, San Juan, Argentina
| | - Pamela Martino-Adami
- Laboratory
of Brain Aging and Neurodegeneration, Fundación
Instituto Leloir, IIBBA-CONICET, Av. Patricias Argentinas 435 C1405BWE, Ciudad Autónoma de Buenos Aires, Argentina
| | - Laura Morelli
- Laboratory
of Brain Aging and Neurodegeneration, Fundación
Instituto Leloir, IIBBA-CONICET, Av. Patricias Argentinas 435 C1405BWE, Ciudad Autónoma de Buenos Aires, Argentina
| | - Vijay Kumar
- School
of Pharmacy, Department of Pharmaceutical Sciences, University of Colorado, Aurora, Colorado 80045 United States
| | - Michael F. Wempe
- School
of Pharmacy, Department of Pharmaceutical Sciences, University of Colorado, Aurora, Colorado 80045 United States
| | - A. C. Cuello
- Department
of Pharmacology and Therapeutics, McGill
University, McIntyre
Medical Building 3655 Prom. Sir-William-Osler, Montreal, Quebec H3G 1Y6, Canada
| | - Eduardo Fernandez-Megia
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CIQUS) and Departamento de Química
Orgánica, Universidade de Santiago
de Compostela, Jenaro de la Fuente s/n, 15782 Santiago de Compostela, Spain
- Eduardo Fernandez-Megia,
| | - Martin A. Bruno
- Instituto
de Ciencias Biomédicas, Facultad de Ciencias Médicas, Universidad Católica de Cuyo, Av. José Ignacio de la Roza
1516, Rivadavia, 5400, San Juan, Argentina
- National
Council of Scientific and Technical Research (CONICET), Godoy Cruz 2290, C1425FQB Ciudad Autónoma de Buenos Aires Argentina
- Martin A. Bruno,
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Li Z, Shue F, Zhao N, Shinohara M, Bu G. APOE2: protective mechanism and therapeutic implications for Alzheimer's disease. Mol Neurodegener 2020; 15:63. [PMID: 33148290 PMCID: PMC7640652 DOI: 10.1186/s13024-020-00413-4] [Citation(s) in RCA: 103] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 10/17/2020] [Indexed: 02/06/2023] Open
Abstract
Investigations of apolipoprotein E (APOE) gene, the major genetic risk modifier for Alzheimer's disease (AD), have yielded significant insights into the pathogenic mechanism. Among the three common coding variants, APOE*ε4 increases, whereas APOE*ε2 decreases the risk of late-onset AD compared with APOE*ε3. Despite increased understanding of the detrimental effect of APOE*ε4, it remains unclear how APOE*ε2 confers protection against AD. Accumulating evidence suggests that APOE*ε2 protects against AD through both amyloid-β (Aβ)-dependent and independent mechanisms. In addition, APOE*ε2 has been identified as a longevity gene, suggesting a systemic effect of APOE*ε2 on the aging process. However, APOE*ε2 is not entirely benign; APOE*ε2 carriers exhibit increased risk of certain cerebrovascular diseases and neurological disorders. Here, we review evidence from both human and animal studies demonstrating the protective effect of APOE*ε2 against AD and propose a working model depicting potential underlying mechanisms. Finally, we discuss potential therapeutic strategies designed to leverage the protective effect of APOE2 to treat AD.
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Affiliation(s)
- Zonghua Li
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | - Francis Shue
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
- Neuroscience Graduate Program, Mayo Clinic, Jacksonville, FL, USA
| | - Na Zhao
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | - Mitsuru Shinohara
- Department of Aging Neurobiology, National Center for Geriatrics and Gerontology, 7-430 Morioka, Obu, Aichi, 474-8511, Japan.
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA.
- Neuroscience Graduate Program, Mayo Clinic, Jacksonville, FL, USA.
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Shinohara M, Shinohara M, Zhao J, Fu Y, Liu CC, Kanekiyo T, Bu G. 5-HT3 Antagonist Ondansetron Increases apoE Secretion by Modulating the LXR-ABCA1 Pathway. Int J Mol Sci 2019; 20:ijms20061488. [PMID: 30934555 PMCID: PMC6471172 DOI: 10.3390/ijms20061488] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/10/2019] [Accepted: 03/21/2019] [Indexed: 12/20/2022] Open
Abstract
Apolipoprotein E (apoE) is linked to the risk for Alzheimer’s disease (AD) and thus has been suggested to be an important therapeutic target. In our drug screening effort, we identified Ondansetron (OS), an FDA-approved 5-HT3 antagonist, as an apoE-modulating drug. OS at low micromolar concentrations significantly increased apoE secretion from immortalized astrocytes and primary astrocytes derived from apoE3 and apoE4-targeted replacement mice without generating cellular toxicity. Other 5-HT3 antagonists also had similar effects as OS, though their effects were milder and required higher concentrations. Antagonists for other 5-HT receptors did not increase apoE secretion. OS also increased mRNA and protein levels of the ATB-binding cassette protein A1 (ABCA1), which is involved in lipidation and secretion of apoE. Accordingly, OS increased high molecular weight apoE. Moreover, the liver X receptor (LXR) and ABCA1 antagonists blocked the OS-induced increase of apoE secretion, indicating that the LXR-ABCA1 pathway is involved in the OS-mediated facilitation of apoE secretion from astrocytes. The effects of OS on apoE and ABCA1 were also observed in human astrocytes derived from induced pluripotent stem cells (iPSC) carrying the APOE ε3/ε3 and APOE ε4/ε4 genotypes. Oral administration of OS at clinically-relevant doses affected apoE levels in the liver, though the effects in the brain were not observed. Collectively, though further studies are needed to probe its effects in vivo, OS could be a potential therapeutic drug for AD by modulating poE metabolism through the LXR-ABCA1 pathway.
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Affiliation(s)
- Motoko Shinohara
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.
- Department of Aging Neurobiology, National Center for Geriatrics and Gerontology, Aichi 474-8511, Japan.
| | - Mitsuru Shinohara
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.
- Department of Aging Neurobiology, National Center for Geriatrics and Gerontology, Aichi 474-8511, Japan.
| | - Jing Zhao
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.
| | - Yuan Fu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.
| | - Chia-Chen Liu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.
| | - Takahisa Kanekiyo
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.
- Neuroscience Graduate Program, Mayo Clinic, Jacksonville, FL 32224, USA.
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.
- Neuroscience Graduate Program, Mayo Clinic, Jacksonville, FL 32224, USA.
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6
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Komati R, Spadoni D, Zheng S, Sridhar J, Riley KE, Wang G. Ligands of Therapeutic Utility for the Liver X Receptors. Molecules 2017; 22:molecules22010088. [PMID: 28067791 PMCID: PMC5373669 DOI: 10.3390/molecules22010088] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/29/2016] [Accepted: 12/30/2016] [Indexed: 12/21/2022] Open
Abstract
Liver X receptors (LXRs) have been increasingly recognized as a potential therapeutic target to treat pathological conditions ranging from vascular and metabolic diseases, neurological degeneration, to cancers that are driven by lipid metabolism. Amidst intensifying efforts to discover ligands that act through LXRs to achieve the sought-after pharmacological outcomes, several lead compounds are already being tested in clinical trials for a variety of disease interventions. While more potent and selective LXR ligands continue to emerge from screening of small molecule libraries, rational design, and empirical medicinal chemistry approaches, challenges remain in minimizing undesirable effects of LXR activation on lipid metabolism. This review provides a summary of known endogenous, naturally occurring, and synthetic ligands. The review also offers considerations from a molecular modeling perspective with which to design more specific LXRβ ligands based on the interaction energies of ligands and the important amino acid residues in the LXRβ ligand binding domain.
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Affiliation(s)
- Rajesh Komati
- Department of Chemistry and RCMI Cancer Research Center, Xavier University of Louisiana, New Orleans, LA 70125, USA.
| | - Dominick Spadoni
- Department of Chemistry and RCMI Cancer Research Center, Xavier University of Louisiana, New Orleans, LA 70125, USA.
| | - Shilong Zheng
- Department of Chemistry and RCMI Cancer Research Center, Xavier University of Louisiana, New Orleans, LA 70125, USA.
| | - Jayalakshmi Sridhar
- Department of Chemistry and RCMI Cancer Research Center, Xavier University of Louisiana, New Orleans, LA 70125, USA.
| | - Kevin E Riley
- Department of Chemistry and RCMI Cancer Research Center, Xavier University of Louisiana, New Orleans, LA 70125, USA.
| | - Guangdi Wang
- Department of Chemistry and RCMI Cancer Research Center, Xavier University of Louisiana, New Orleans, LA 70125, USA.
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7
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Achariyar TM, Li B, Peng W, Verghese PB, Shi Y, McConnell E, Benraiss A, Kasper T, Song W, Takano T, Holtzman DM, Nedergaard M, Deane R. Glymphatic distribution of CSF-derived apoE into brain is isoform specific and suppressed during sleep deprivation. Mol Neurodegener 2016; 11:74. [PMID: 27931262 PMCID: PMC5146863 DOI: 10.1186/s13024-016-0138-8] [Citation(s) in RCA: 141] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 12/01/2016] [Indexed: 12/21/2022] Open
Abstract
Background Apolipoprotein E (apoE) is a major carrier of cholesterol and essential for synaptic plasticity. In brain, it’s expressed by many cells but highly expressed by the choroid plexus and the predominant apolipoprotein in cerebrospinal fluid (CSF). The role of apoE in the CSF is unclear. Recently, the glymphatic system was described as a clearance system whereby CSF and ISF (interstitial fluid) is exchanged via the peri-arterial space and convective flow of ISF clearance is mediated by aquaporin 4 (AQP4), a water channel. We reasoned that this system also serves to distribute essential molecules in CSF into brain. The aim was to establish whether apoE in CSF, secreted by the choroid plexus, is distributed into brain, and whether this distribution pattern was altered by sleep deprivation. Methods We used fluorescently labeled lipidated apoE isoforms, lenti-apoE3 delivered to the choroid plexus, immunohistochemistry to map apoE brain distribution, immunolabeled cells and proteins in brain, Western blot analysis and ELISA to determine apoE levels and radiolabeled molecules to quantify CSF inflow into brain and brain clearance in mice. Data were statistically analyzed using ANOVA or Student’s t- test. Results We show that the glymphatic fluid transporting system contributes to the delivery of choroid plexus/CSF-derived human apoE to neurons. CSF-delivered human apoE entered brain via the perivascular space of penetrating arteries and flows radially around arteries, but not veins, in an isoform specific manner (apoE2 > apoE3 > apoE4). Flow of apoE around arteries was facilitated by AQP4, a characteristic feature of the glymphatic system. ApoE3, delivered by lentivirus to the choroid plexus and ependymal layer but not to the parenchymal cells, was present in the CSF, penetrating arteries and neurons. The inflow of CSF, which contains apoE, into brain and its clearance from the interstitium were severely suppressed by sleep deprivation compared to the sleep state. Conclusions Thus, choroid plexus/CSF provides an additional source of apoE and the glymphatic fluid transporting system delivers it to brain via the periarterial space. By implication, failure in this essential physiological role of the glymphatic fluid flow and ISF clearance may also contribute to apoE isoform-specific disorders in the long term. Electronic supplementary material The online version of this article (doi:10.1186/s13024-016-0138-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Thiyagaragan M Achariyar
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, University of Rochester, Rochester, NY, 14642, USA
| | - Baoman Li
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, University of Rochester, Rochester, NY, 14642, USA.,Laboratory of Brain Metabolic Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, China
| | - Weiguo Peng
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, University of Rochester, Rochester, NY, 14642, USA
| | - Philip B Verghese
- Department of Neurology, Hope Center for Neurological Disorders, and the Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Yang Shi
- Department of Neurology, Hope Center for Neurological Disorders, and the Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Evan McConnell
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, University of Rochester, Rochester, NY, 14642, USA
| | - Abdellatif Benraiss
- Center for Translational Neuromedicine, Division of Cell and Gene Therapy, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Tristan Kasper
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, University of Rochester, Rochester, NY, 14642, USA
| | - Wei Song
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, University of Rochester, Rochester, NY, 14642, USA
| | - Takahiro Takano
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, University of Rochester, Rochester, NY, 14642, USA
| | - David M Holtzman
- Department of Neurology, Hope Center for Neurological Disorders, and the Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, University of Rochester, Rochester, NY, 14642, USA
| | - Rashid Deane
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, University of Rochester, Rochester, NY, 14642, USA.
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8
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Brain penetrant liver X receptor (LXR) modulators based on a 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazole core. Bioorg Med Chem Lett 2016; 26:5044-5050. [PMID: 27599745 DOI: 10.1016/j.bmcl.2016.08.089] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 07/25/2016] [Accepted: 08/27/2016] [Indexed: 11/22/2022]
Abstract
Liver X receptor (LXR) agonists have been reported to lower brain amyloid beta (Aβ) and thus to have potential for the treatment of Alzheimer's disease. Structure and property based design led to the discovery of a series of orally bioavailable, brain penetrant LXR agonists. Oral administration of compound 18 to rats resulted in significant upregulation of the expression of the LXR target gene ABCA1 in brain tissue, but no significant effect on Aβ levels was detected.
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A randomized controlled study to evaluate the effect of bexarotene on amyloid-β and apolipoprotein E metabolism in healthy subjects. ALZHEIMERS & DEMENTIA-TRANSLATIONAL RESEARCH & CLINICAL INTERVENTIONS 2016; 2:110-120. [PMID: 29067298 PMCID: PMC5644280 DOI: 10.1016/j.trci.2016.06.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION We conducted a phase Ib proof of mechanism trial to determine whether bexarotene (Targretin) increases central nervous system (CNS) apolipoprotein E (apoE) levels and alters Aβ metabolism in normal healthy individuals with the APOE ε3/ε3 genotype. METHODS We used stable isotope labeling kinetics (SILK-ApoE and SILK-Aβ) to measure the effect of bexarotene on the turnover rate of apoE and Aβ peptides and stable isotope spike absolute quantitation (SISAQ) to quantitate their concentrations in the cerebrospinal fluid (CSF). Normal subjects were treated for 3 days with bexarotene (n = 3 women, 3 men, average 32 years old) or placebo (n = 6 women, average 30.2 years old) before administration of C13-leucine and collection of plasma and CSF over the next 48 hours. Bexarotene concentrations in plasma and CSF were also measured. RESULTS Oral administration of bexarotene resulted in plasma levels of 1 to 2 μM; however, only low nM levels were found in CSF. Bexarotene increased CSF apoE by 25% but had no effect on metabolism of Aβ peptides. DISCUSSION Bexarotene has poor CNS penetration in normal human subjects. Drug treatment resulted in a modest increase in CSF apoE levels. The absence of an effect on Aβ metabolism is likely reflective of the low CNS levels of bexarotene achieved. This study documents the utility of SILK-ApoE technology in measuring apoE kinetics in humans. TRIAL REGISTRATION This trial is registered at clinicaltrials.gov (NCT02061878).
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Stachel SJ, Zerbinatti C, Rudd MT, Cosden M, Suon S, Nanda KK, Wessner K, DiMuzio J, Maxwell J, Wu Z, Uslaner JM, Michener MS, Szczerba P, Brnardic E, Rada V, Kim Y, Meissner R, Wuelfing P, Yuan Y, Ballard J, Holahan M, Klein DJ, Lu J, Fradera X, Parthasarathy G, Uebele VN, Chen Z, Li Y, Li J, Cooke AJ, Bennett DJ, Bilodeau MT, Renger J. Identification and in Vivo Evaluation of Liver X Receptor β-Selective Agonists for the Potential Treatment of Alzheimer’s Disease. J Med Chem 2016; 59:3489-98. [DOI: 10.1021/acs.jmedchem.6b00176] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Zhongguo Chen
- WuXi AppTec Company, Ltd., Shanghai 200131, P. R. China
| | - Yingjie Li
- WuXi AppTec Company, Ltd., Shanghai 200131, P. R. China
| | - Jian Li
- WuXi AppTec Company, Ltd., Shanghai 200131, P. R. China
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Abstract
Alzheimer's disease (AD) is characterized pathologically by the presence of amyloid plaques and neurofibrillary tangles. The amyloid hypothesis contends that the abnormal accumulation of Aβ, the principal component of amyloid plaques, plays an essential role in initiating the disease. Impaired clearance of soluble Aβ from the brain, a process facilitated by apolipoprotein E (APOE), is believed to be a contributing factor in plaque formation. APOE expression is transcriptionally regulated through the action of a family of nuclear receptors including the peroxisome proliferator-activated receptor gamma and liver X receptors (LXRs) in coordination with retinoid X receptors (RXRs). It has been previously reported that various agonists of this receptor family can influence brain Aβ levels in rodents. In this study we investigated the effects of LXR/RXR agonism on brain and cerebrospinal fluid (CSF) levels of Aβ40 in naïve rats. Treatment of rats for 3 days or 7 days with the LXR agonist, T0901317 or the RXR agonist, bexarotene did not result in significant changes in brain or CSF Aβ40 levels.
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Affiliation(s)
- Songli Wang
- Genome Analysis Unit, Amgen Inc., San Francisco, CA, USA
| | - Paul Wen
- Department of Neuroscience, Amgen Inc., Thousand Oaks, CA, USA
| | - Stephen Wood
- Department of Neuroscience, Amgen Inc., Thousand Oaks, CA, USA
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Collins MA, An J, Peller D, Bowser R. Total protein is an effective loading control for cerebrospinal fluid western blots. J Neurosci Methods 2015; 251:72-82. [PMID: 26004848 DOI: 10.1016/j.jneumeth.2015.05.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 05/13/2015] [Accepted: 05/14/2015] [Indexed: 12/13/2022]
Abstract
BACKGROUND Cerebrospinal fluid (CSF) has been used to identify biomarkers of neurological disease. CSF protein biomarkers identified by high-throughput methods, however, require further validation. While Western blotting (WB) is well-suited to this task, the lack of a validated loading control for CSF WB limits the method's accuracy. NEW METHOD We investigated the use of total protein (TP) as a CSF WB loading control. Using iodine-based reversible membrane staining, we determined the linear range and consistency of the CSF TP signal. We then spiked green fluorescent protein (GFP) into CSF to create defined sample-to-sample differences in GFP levels that were measured by WB before and after TP loading correction. Levels of CSF complement C3 and cystatin C measured by WB with TP loading correction and ELISA in amyotrophic lateral sclerosis and healthy control CSF samples were then compared. RESULTS CSF WB with the TP loading control accurately detected defined differences in GFP levels and corrected for simulated loading errors. Individual CSF sample Western blot and ELISA measurements of complement C3 and cystatin C were significantly correlated and the methods showed a comparable ability to detect between-groups differences. COMPARISON WITH EXISTING METHOD CSF TP staining has a greater linear dynamic range and sample-to-sample consistency than albumin, a commonly used CSF loading control. The method accurately corrects for simulated errors in loading and improves the sensitivity of CSF WB compared to using no loading control. CONCLUSIONS The TP staining loading control improves the sensitivity and accuracy of CSF WB results.
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Affiliation(s)
- Mahlon A Collins
- Department of Neurobiology, University of Pittsburgh, 200 South Lothrop Street, Pittsburgh, PA 15213, USA; Departments of Neurobiology and Neurology, St. Joseph's Hospital and Medical Center and Barrow Neurological Institute, 350 West Thomas Road, Phoenix, AZ 85013, USA.
| | - Jiyan An
- Departments of Neurobiology and Neurology, St. Joseph's Hospital and Medical Center and Barrow Neurological Institute, 350 West Thomas Road, Phoenix, AZ 85013, USA.
| | - Danielle Peller
- Departments of Neurobiology and Neurology, St. Joseph's Hospital and Medical Center and Barrow Neurological Institute, 350 West Thomas Road, Phoenix, AZ 85013, USA.
| | - Robert Bowser
- Departments of Neurobiology and Neurology, St. Joseph's Hospital and Medical Center and Barrow Neurological Institute, 350 West Thomas Road, Phoenix, AZ 85013, USA.
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Fitz NF, Castranio EL, Carter AY, Kodali R, Lefterov I, Koldamova R. Improvement of memory deficits and amyloid-β clearance in aged APP23 mice treated with a combination of anti-amyloid-β antibody and LXR agonist. J Alzheimers Dis 2015; 41:535-49. [PMID: 24643138 DOI: 10.3233/jad-132789] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Passive amyloid-β (Aβ) vaccination has shown significant effects on amyloid pathology in pre-depositing amyloid-β protein precursor (AβPP) mice but the results in older mice are inconsistent. A therapeutic effect of LXR and RXR agonists consisting of improved memory deficits and Aβ pathology has been demonstrated in different Alzheimer's disease (AD) mouse models. Here, we report the effect of a combination of N-terminal Aβ antibody and synthetic LXR agonist T0901317 (T0) on AD-like phenotype of APP23 mice. To examine the therapeutic potential of this combination, the treatment of mice started at 11 months of age, when amyloid phenotype in this model is fully developed, and continued for 50 days. We show that Aβ immunization with or without LXR agonist restored the performance of APP23 transgenic mice in two behavior paradigms without affecting the existing amyloid plaques. Importantly, we did not observe an increase of brain microhemorrhage which is considered a significant side effect of Aβ vaccination. Target engagement was confirmed by increased Abca1 and ApoE protein level as well as increased ApoE lipidation in soluble brain extract. In interstitial fluid obtained by microdialysis, we demonstrate that immunization and T0 significantly reduced Aβ levels, indicating an increased Aβ clearance. We found no interaction between the immunotherapy and T0, suggesting no synergism, at least with these doses. The results of our study demonstrate that anti-Aβ treatments can ameliorate cognitive deficits in AβPP mice with advanced AD-like phenotype in conjunction with a decrease of Aβ in brain interstitium and increase of ApoE lipidation without affecting the existing amyloid plaques.
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Affiliation(s)
- Nicholas F Fitz
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Emilie L Castranio
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Alexis Y Carter
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ravindra Kodali
- Department of Structural Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
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Tice CM, Noto PB, Fan KY, Zhuang L, Lala DS, Singh SB. The Medicinal Chemistry of Liver X Receptor (LXR) Modulators. J Med Chem 2014; 57:7182-205. [PMID: 24832115 DOI: 10.1021/jm500442z] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Colin M. Tice
- Vitae Pharmaceuticals Inc., 502 West Office Center Drive, Fort Washington, Pennsylvania 19034, United States
| | - Paul B. Noto
- Vitae Pharmaceuticals Inc., 502 West Office Center Drive, Fort Washington, Pennsylvania 19034, United States
| | - Kristi Yi Fan
- Vitae Pharmaceuticals Inc., 502 West Office Center Drive, Fort Washington, Pennsylvania 19034, United States
| | - Linghang Zhuang
- Vitae Pharmaceuticals Inc., 502 West Office Center Drive, Fort Washington, Pennsylvania 19034, United States
| | - Deepak S. Lala
- Vitae Pharmaceuticals Inc., 502 West Office Center Drive, Fort Washington, Pennsylvania 19034, United States
| | - Suresh B. Singh
- Vitae Pharmaceuticals Inc., 502 West Office Center Drive, Fort Washington, Pennsylvania 19034, United States
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15
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Searcy JL, Le Bihan T, Salvadores N, McCulloch J, Horsburgh K. Impact of age on the cerebrovascular proteomes of wild-type and Tg-SwDI mice. PLoS One 2014; 9:e89970. [PMID: 24587158 PMCID: PMC3935958 DOI: 10.1371/journal.pone.0089970] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 01/23/2014] [Indexed: 12/13/2022] Open
Abstract
The structural integrity of cerebral vessels is compromised during ageing. Abnormal amyloid (Aβ) deposition in the vasculature can accelerate age-related pathologies. The cerebrovascular response associated with ageing and microvascular Aβ deposition was defined using quantitative label-free shotgun proteomic analysis. Over 650 proteins were quantified in vessel-enriched fractions from the brains of 3 and 9 month-old wild-type (WT) and Tg-SwDI mice. Sixty-five proteins were significantly increased in older WT animals and included several basement membrane proteins (nidogen-1, basement membrane-specific heparan sulfate proteoglycan core protein, laminin subunit gamma-1 precursor and collagen alpha-2(IV) chain preproprotein). Twenty-four proteins were increased and twenty-one decreased in older Tg-SwDI mice. Of these, increases in Apolipoprotein E (APOE) and high temperature requirement serine protease-1 (HTRA1) and decreases in spliceosome and RNA-binding proteins were the most prominent. Only six shared proteins were altered in both 9-month old WT and Tg-SwDI animals. The age-related proteomic response in the cerebrovasculature was distinctly different in the presence of microvascular Aβ deposition. Proteins found differentially expressed within the WT and Tg-SwDI animals give greater insight to the mechanisms behind age-related cerebrovascular dysfunction and pathologies and may provide novel therapeutic targets.
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Affiliation(s)
- James L Searcy
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom
| | - Thierry Le Bihan
- SynthSys - Synthetic & Systems Biology, University of Edinburgh, Edinburgh, United Kingdom ; Institute of Structural and Molecular Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Natalia Salvadores
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom
| | - James McCulloch
- Centre for Cognitive and Neural Systems, University of Edinburgh, Edinburgh, United Kingdom ; Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Karen Horsburgh
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom ; Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom
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16
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Pathogenesis, modulation, and therapy of Alzheimer’s disease: A perspective on roles of liver-X receptors. Transl Neurosci 2013. [DOI: 10.2478/s13380-013-0136-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
AbstractThe pathogenesis of Alzheimer’s disease (AD) has been mostly linked to aberrant amyloid beta (Aβ) and tau proteins metabolism, disturbed lipid/cholesterol homeostasis, and progressive neuroinflammation. Liver X receptors (LXR) are ligand-activated transcription factors, best known as the key regulators of cholesterol metabolism and transport. In addition, LXR signaling has been shown to have significant anti-inflammatory properties. In this brief review, we focus on the outcome of studies implicating LXR in the pathogenesis, modulation, and therapy of AD.
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18
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Bachmeier C, Beaulieu-Abdelahad D, Crawford F, Mullan M, Paris D. Stimulation of the Retinoid X Receptor Facilitates Beta-Amyloid Clearance Across the Blood–Brain Barrier. J Mol Neurosci 2012; 49:270-6. [DOI: 10.1007/s12031-012-9866-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 07/24/2012] [Indexed: 12/12/2022]
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Abstract
Although the precise cause of Alzheimer's disease is not known, the β-amyloid peptide chains of 40-42 amino acids are suspected to contribute to the disease. The β-amyloid precursor protein is found on many types of cell membranes, and the action of secretases (β and γ) on this precursor protein normally releases the β-amyloids at a high rate into the plasma and the cerebrospinal fluid. However, the concentrations of the β-amyloids in the plasma and the spinal fluid vary considerably between laboratories. The β-amyloids adsorb in the nanomolar concentration range to receptors on neuronal and glial cells. The β-amyloids are internalized, become folded in the β-folded or β-pleated shape, and then stack on each other to form long fibrils and aggregates known as plaques. The β-amyloids likely act as monomers, dimers, or multimers on cell membranes to interfere with neurotransmission and memory before the plaques build up. Treatment strategies include inhibitors of β- and γ-secretase, as well as drugs and physiological compounds to prevent aggregation of the amyloids. Several immune approaches and a cholesterol-lowering strategy are also being tested to remove the β-amyloids.
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Affiliation(s)
- Philip Seeman
- Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada.
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20
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Noto PB, Bukhtiyarov Y, Shi M, McKeever BM, McGeehan GM, Lala DS. Regulation of sphingomyelin phosphodiesterase acid-like 3A gene (SMPDL3A) by liver X receptors. Mol Pharmacol 2012; 82:719-27. [PMID: 22810003 DOI: 10.1124/mol.112.078865] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Liver X receptor (LXR) α and LXRβ function as physiological sensors of cholesterol metabolites (oxysterols), regulating key genes involved in cholesterol and lipid metabolism. LXRs have been extensively studied in both human and rodent cell systems, revealing their potential therapeutic value in the contexts of atherosclerosis and inflammatory diseases. The LXR genome landscape has been investigated in murine macrophages but not in human THP-1 cells, which represent one of the frequently used monocyte/macrophage cell systems to study immune responses. We used a whole-genome screen to detect direct LXR target genes in THP-1 cells treated with two widely used LXR ligands [N-(2,2,2-trifluoroethyl)-N-[4-[2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)-ethyl]phenyl]-benzenesulfonamide (T0901317) and 3-[3-[N-(2-chloro-3-trifluoromethylbenzyl)-(2,2-diphenylethyl)amino]propyloxy] phenylacetic acid hydrochloride (GW3965)]. This screen identified the sphingomyelin phosphodiesterase acid-like 3A (SMPDL3A) gene as a novel LXR-regulated gene, with an LXR response element within its promoter. We investigated the regulation of SMPDL3A gene expression by LXRs across several human and mouse cell types. These studies indicate that the induction of SMPDL3A is LXR-dependent and is restricted to human blood cells with no induction observed in mouse cellular systems.
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Affiliation(s)
- Paul B Noto
- Discovery Biology, Vitae Pharmaceuticals, Inc., Fort Washington, Pennsylvania, USA.
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21
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Sorrentino V, Zelcer N. Post-transcriptional regulation of lipoprotein receptors by the E3-ubiquitin ligase inducible degrader of the low-density lipoprotein receptor. Curr Opin Lipidol 2012; 23:213-219. [PMID: 22510808 DOI: 10.1097/mol.0b013e3283532947] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE OF REVIEW The hepatic low-density lipoprotein receptor (LDLR) pathway is essential for clearing circulating LDL and is an important therapeutic target for treating cardiovascular disease. Abundance of the LDLR is subject to both transcriptional and nontranscriptional control. Here, we highlight a new post-transcriptional mechanism for controlling LDLR function via ubiquitination of the receptor by the E3-ubiquitin ligase inducible degrader of the LDLR (IDOL). RECENT FINDINGS IDOL is a recently identified transcriptional target of the liver X receptors. Acting as an E3-ubiquitin ligase IDOL promotes ubiquitination of the LDLR, thereby marking it for lysosomal degradation. The determinants required for degradation of the LDLR by IDOL have been largely identified. IDOL also targets two related lipoprotein receptors, the very low-density lipoprotein receptor and apolipoprotein E receptor 2. Despite several similarities, the IDOL, and PCSK9 pathways for controlling LDLR abundance seem independent of each other. Genome-wide association studies have recently identified IDOL as a locus influencing variability in circulating levels of LDL, thereby highlighting the possible role of IDOL in human lipoprotein metabolism. SUMMARY Transcriptional induction of IDOL by liver X receptor defines a new post-transcriptional pathway for controlling LDLR abundance and LDL uptake independent of sterol regulatory element binding proteins. Targeting IDOL activity may offer a novel therapeutic approach complementary to statins for treating cardiovascular disease.
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Affiliation(s)
- Vincenzo Sorrentino
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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22
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Stukas S, May S, Wilkinson A, Chan J, Donkin J, Wellington CL. The LXR agonist GW3965 increases apoA-I protein levels in the central nervous system independent of ABCA1. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:536-46. [PMID: 21889608 DOI: 10.1016/j.bbalip.2011.08.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 07/29/2011] [Accepted: 08/05/2011] [Indexed: 01/09/2023]
Abstract
Lipoprotein metabolism in the central nervous system (CNS) is based on high-density lipoprotein-like particles that use apoE as their predominant apolipoprotein rather than apoA-I. Although apoA-I is not expressed in astrocytes and microglia, which produce CNS apoE, apoA-I is reported to be expressed in porcine brain capillary endothelial cells and also crosses the blood-brain barrier (BBB). These mechanisms allow apoA-I to reach concentrations in cerebrospinal fluid (CSF) that are approximately 0.5% of its plasma levels. Recently, apoA-I has been shown to enhance cognitive function and reduce cerebrovascular amyloid deposition in Alzheimer's Disease (AD) mice, raising questions about the regulation and function of apoA-I in the CNS. Peripheral apoA-I metabolism is highly influenced by ABCA1, but less is known about how ABCA1 regulates CNS apoA-I. We report that ABCA1 deficiency leads to greater retention of apoA-I in the CNS than in the periphery. Additionally, treatment of symptomatic AD mice with GW3965, an LXR agonist that stimulates ABCA1 expression, increases apoA-I more dramatically in the CNS compared to the periphery. Furthermore, GW3965-mediated up-regulation of CNS apoA-I is independent of ABCA1. Our results suggest that apoA-I may be regulated by distinct mechanisms on either side of the BBB and that apoA-I may serve to integrate peripheral and CNS lipid metabolism. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).
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Affiliation(s)
- Sophie Stukas
- Department of Pathology and Laboratory Medicine, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4
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