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Lam XJ, Maniam S, Cheah PS, Ling KH. REST in the Road Map of Brain Development. Cell Mol Neurobiol 2023; 43:3417-3433. [PMID: 37517069 DOI: 10.1007/s10571-023-01394-w] [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: 04/05/2023] [Accepted: 07/23/2023] [Indexed: 08/01/2023]
Abstract
Repressor element-1 silencing transcription factor (REST) or also known as neuron-restrictive silencing factor (NRSF), is the key initiator of epigenetic neuronal gene-expression modification. Identification of a massive number of REST-targeted genes in the brain signifies its broad involvement in maintaining the functionality of the nervous system. Additionally, REST plays a crucial role in conferring neuroprotection to the neurons against various stressors or insults during injuries. At the cellular level, nuclear localisation of REST is a key determinant for the functional transcriptional regulation of REST towards its target genes. Emerging studies reveal the implication of REST nuclear mislocalisation or dysregulation in several neurological diseases. The expression of REST varies depending on different types of neurological disorders, which has created challenges in the discovery of REST-targeted interventions. Hence, this review presents a comprehensive summary on the physiological roles of REST throughout brain development and its implications in neurodegenerative and neurodevelopmental disorders, brain tumours and cerebrovascular diseases. This review offers valuable insights to the development of potential therapeutic approaches targeting REST to improve pathologies in the brain. The important roles of REST as a key player in the nervous system development, and its implications in several neurological diseases.
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Affiliation(s)
- Xin-Jieh Lam
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - Sandra Maniam
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - Pike-See Cheah
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
- Malaysian Research Institute on Ageing (MyAgeing), Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
| | - King-Hwa Ling
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
- Malaysian Research Institute on Ageing (MyAgeing), Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
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Zhang L, Xia Y, Gui Y. Neuronal ApoE4 in Alzheimer's disease and potential therapeutic targets. Front Aging Neurosci 2023; 15:1199434. [PMID: 37333457 PMCID: PMC10272394 DOI: 10.3389/fnagi.2023.1199434] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 05/16/2023] [Indexed: 06/20/2023] Open
Abstract
The most prevalent genetic risk factor for Alzheimer's disease (AD) is Apolipoprotein E (ApoE), a gene located on chromosome 19 that encodes three alleles (e2, e3, and e4) that give rise to the ApoE subtypes E2, E3, and E4, respectively. E2 and E4 have been linked to increased plasma triglyceride concentrations and are known to play a critical role in lipoprotein metabolism. The prominent pathological features of AD mainly include senile plaques formed by amyloid β (Aβ42) aggregation and neuronal fibrous tangles (NFTs), and the deposited plaques are mainly composed of Aβ hyperphosphorylation and truncated head. In the central nervous system, the ApoE protein is primarily derived from astrocytes, but ApoE is also produced when neurons are stressed or affected by certain stress, injury, and aging conditions. ApoE4 in neurons induces Aβ and tau protein pathologies, leading to neuroinflammation and neuronal damage, impairing learning and memory functions. However, how neuronal ApoE4 mediates AD pathology remains unclear. Recent studies have shown that neuronal ApoE4 may lead to greater neurotoxicity, which increases the risk of AD development. This review focuses on the pathophysiology of neuronal ApoE4 and explains how neuronal ApoE4 mediates Aβ deposition, pathological mechanisms of tau protein hyperphosphorylation, and potential therapeutic targets.
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Lazar AN, Hanbouch L, Boussicaut L, Fourmaux B, Daira P, Millan MJ, Bernoud-Hubac N, Potier MC. Lipid Dys-Homeostasis Contributes to APOE4-Associated AD Pathology. Cells 2022; 11:cells11223616. [PMID: 36429044 PMCID: PMC9688773 DOI: 10.3390/cells11223616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/21/2022] [Accepted: 11/09/2022] [Indexed: 11/18/2022] Open
Abstract
The association of the APOE4 (vs. APOE3) isoform with an increased risk of Alzheimer's disease (AD) is unequivocal, but the underlying mechanisms remain incompletely elucidated. A prevailing hypothesis incriminates the impaired ability of APOE4 to clear neurotoxic amyloid-β peptides (Aβ) from the brain as the main mechanism linking the apolipoprotein isoform to disease etiology. The APOE protein mediates lipid transport both within the brain and from the brain to the periphery, suggesting that lipids may be potential co-factors in APOE4-associated physiopathology. The present study reveals several changes in the pathways of lipid homeostasis in the brains of mice expressing the human APOE4 vs. APOE3 isoform. Carriers of APOE4 had altered cholesterol turnover, an imbalance in the ratio of specific classes of phospholipids, lower levels of phosphatidylethanolamines bearing polyunsaturated fatty acids and an overall elevation in levels of monounsaturated fatty acids. These modifications in lipid homeostasis were related to increased production of Aβ peptides as well as augmented levels of tau and phosphorylated tau in primary neuronal cultures. This suite of APOE4-associated anomalies in lipid homeostasis and neurotoxic protein levels may be related to the accrued risk for AD in APOE4 carriers and provides novel insights into potential strategies for therapeutic intervention.
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Affiliation(s)
- Adina-Nicoleta Lazar
- Univ Lyon, INSA Lyon, CNRS, LaMCoS, UMR5259, 69621 Villeurbanne, France
- Correspondence: (A.-N.L.); (M.-C.P.)
| | - Linda Hanbouch
- ICM Paris Brain Institute, CNRS UMR7225, INSERM U1127, Sorbonne University, Hôpital de la Pitié-Salpêtrière, 47 Bd de l’Hôpital, 75013 Paris, France
| | - Lydie Boussicaut
- ICM Paris Brain Institute, CNRS UMR7225, INSERM U1127, Sorbonne University, Hôpital de la Pitié-Salpêtrière, 47 Bd de l’Hôpital, 75013 Paris, France
| | - Baptiste Fourmaux
- Univ Lyon, INSA Lyon, CNRS, LaMCoS, UMR5259, 69621 Villeurbanne, France
| | - Patricia Daira
- Univ Lyon, INSA Lyon, CNRS, LaMCoS, UMR5259, 69621 Villeurbanne, France
| | - Mark J. Millan
- Institut De Recherche Servier IDRS, Neuroscience Inflammation Thérapeutic Area, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, France
- Institute of Neuroscience and Psychology, College of Medical, Vet and life Sciences, Glasgow University, 68 Hillhead Street, Glasgow G12 8QB, Scotland, UK
| | | | - Marie-Claude Potier
- ICM Paris Brain Institute, CNRS UMR7225, INSERM U1127, Sorbonne University, Hôpital de la Pitié-Salpêtrière, 47 Bd de l’Hôpital, 75013 Paris, France
- Correspondence: (A.-N.L.); (M.-C.P.)
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4
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Wong MY, Lewis M, Doherty JJ, Shi Y, Cashikar AG, Amelianchik A, Tymchuk S, Sullivan PM, Qian M, Covey DF, Petsko GA, Holtzman DM, Paul SM, Luo W. 25-Hydroxycholesterol amplifies microglial IL-1β production in an apoE isoform-dependent manner. J Neuroinflammation 2020; 17:192. [PMID: 32552741 PMCID: PMC7298825 DOI: 10.1186/s12974-020-01869-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 06/08/2020] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Genome-wide association studies of Alzheimer's disease (AD) have implicated pathways related to lipid homeostasis and innate immunity in AD pathophysiology. However, the exact cellular and chemical mediators of neuroinflammation in AD remain poorly understood. The oxysterol 25-hydroxycholesterol (25-HC) is an important immunomodulator produced by peripheral macrophages with wide-ranging effects on cell signaling and innate immunity. Cholesterol 25-hydroxylase (CH25H), the enzyme responsible for 25-HC production, has also been found to be one of the disease-associated microglial (DAM) genes that are upregulated in the brain of AD and AD transgenic mouse models. METHODS We used real-time PCR and immunoblotting to examine CH25H expression in human AD brain tissue and in transgenic mouse brain tissue-bearing amyloid-β plaques or tau pathology. The innate immune response of primary mouse microglia under different treatment conditions or bearing different genetic backgrounds was analyzed using ELISA, western blotting, or immunocytochemistry. RESULTS We found that CH25H expression is upregulated in human AD brain tissue and in transgenic mouse brain tissue-bearing amyloid-β plaques or tau pathology. Treatment with the toll-like receptor 4 (TLR4) agonist lipopolysaccharide (LPS) markedly upregulates CH25H expression in the mouse brain and stimulates CH25H expression and 25-HC secretion in mouse primary microglia. We found that LPS-induced microglial production of the pro-inflammatory cytokine IL-1β is markedly potentiated by 25-HC and attenuated by the deletion of CH25H. Microglia expressing apolipoprotein E4 (apoE4), a genetic risk factor for AD, produce greater amounts of 25-HC than apoE3-expressing microglia following treatment with LPS. Remarkably, 25-HC treatment results in a greater level of IL-1β secretion in LPS-activated apoE4-expressing microglia than in apoE2- or apoE3-expressing microglia. Blocking potassium efflux or inhibiting caspase-1 prevents 25-HC-potentiated IL-1β release in apoE4-expressing microglia, indicating the involvement of caspase-1 inflammasome activity. CONCLUSION 25-HC may function as a microglial-secreted inflammatory mediator in the brain, promoting IL-1β-mediated neuroinflammation in an apoE isoform-dependent manner (E4>>E2/E3) and thus may be an important mediator of neuroinflammation in AD.
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Affiliation(s)
- Man Ying Wong
- grid.5386.8000000041936877XAppel Alzheimer’s Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY USA
| | - Michael Lewis
- grid.476678.c0000 0004 5913 664XSage Therapeutics, Cambridge, Massachusetts USA
| | - James J. Doherty
- grid.476678.c0000 0004 5913 664XSage Therapeutics, Cambridge, Massachusetts USA
| | - Yang Shi
- grid.4367.60000 0001 2355 7002Department of Neurology, Hope Center for Neurological Disorders, Charles F. and Joanne Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO USA
| | - Anil G. Cashikar
- grid.4367.60000 0001 2355 7002Departments of Neurology and Psychiatry, Hope Center for Neurological Disorders, Taylor Family Institute, Washington University School of Medicine, St. Louis, MO USA
| | - Anna Amelianchik
- grid.5386.8000000041936877XAppel Alzheimer’s Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY USA
| | - Svitlana Tymchuk
- grid.5386.8000000041936877XAppel Alzheimer’s Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY USA
| | - Patrick M. Sullivan
- grid.281208.10000 0004 0419 3073Department of Medicine, Duke University Medical Center, Durham Veterans Health Administration Medical Center’s Geriatric Research, Education and Clinical Center, Durham, NC USA
| | - Mingxing Qian
- grid.4367.60000 0001 2355 7002Departments of Developmental Biology, Anesthesiology, Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, 660 South Euclid Avenue, St. Louis, MO 63110 USA
| | - Douglas F. Covey
- grid.4367.60000 0001 2355 7002Departments of Developmental Biology, Anesthesiology, Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, 660 South Euclid Avenue, St. Louis, MO 63110 USA
| | - Gregory A. Petsko
- grid.5386.8000000041936877XAppel Alzheimer’s Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY USA
| | - David M. Holtzman
- grid.4367.60000 0001 2355 7002Department of Neurology, Hope Center for Neurological Disorders, Charles F. and Joanne Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO USA
| | - Steven M. Paul
- grid.476678.c0000 0004 5913 664XSage Therapeutics, Cambridge, Massachusetts USA ,grid.4367.60000 0001 2355 7002Departments of Neurology and Psychiatry, Hope Center for Neurological Disorders, Taylor Family Institute, Washington University School of Medicine, St. Louis, MO USA
| | - Wenjie Luo
- Appel Alzheimer's Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA.
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Iacono D, Feltis GC. Impact of Apolipoprotein E gene polymorphism during normal and pathological conditions of the brain across the lifespan. Aging (Albany NY) 2020; 11:787-816. [PMID: 30677746 PMCID: PMC6366964 DOI: 10.18632/aging.101757] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 01/05/2019] [Indexed: 12/12/2022]
Abstract
The central nervous system (CNS) is the cellular substrate for the integration of complex, dynamic, constant, and simultaneous interactions among endogenous and exogenous stimuli across the entire human lifespan. Numerous studies on aging-related brain diseases show that some genes identified as risk factors for some of the most common neurodegenerative diseases - such as the allele 4 of APOE gene (APOE4) for Alzheimer's disease (AD) - have a much earlier neuro-anatomical and neuro-physiological impact. The impact of APOE polymorphism appears in fact to start as early as youth and early-adult life. Intriguingly, though, those same genes associated with aging-related brain diseases seem to influence different aspects of the brain functioning much earlier actually, that is, even from the neonatal periods and earlier. The APOE4, an allele classically associated with later-life neurodegenerative disorders as AD, seems in fact to exert a series of very early effects on phenomena of neuroplasticity and synaptogenesis that begin from the earliest periods of life such as the fetal ones.We reviewed some of the findings supporting the hypothesis that APOE polymorphism is an early modifier of various neurobiological aspects across the entire human lifespan - from the in-utero to the centenarian life - during both normal and pathological conditions of the brain.
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Affiliation(s)
- Diego Iacono
- Neuropathology Research, Biomedical Research Institute of New Jersey (BRInj), Cedar Knolls, NJ 07927, USA.,MidAtlantic Neonatology Associates (MANA), Morristown, NJ 07960, USA.,Atlantic Neuroscience Institute, Atlantic Health System (AHS), Overlook Medical Center, Summit, NJ 07901, USA
| | - Gloria C Feltis
- Neuropathology Research, Biomedical Research Institute of New Jersey (BRInj), Cedar Knolls, NJ 07927, USA
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Meyer K, Feldman HM, Lu T, Drake D, Lim ET, Ling KH, Bishop NA, Pan Y, Seo J, Lin YT, Su SC, Church GM, Tsai LH, Yankner BA. REST and Neural Gene Network Dysregulation in iPSC Models of Alzheimer's Disease. Cell Rep 2020; 26:1112-1127.e9. [PMID: 30699343 PMCID: PMC6386196 DOI: 10.1016/j.celrep.2019.01.023] [Citation(s) in RCA: 123] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 12/04/2018] [Accepted: 01/07/2019] [Indexed: 12/11/2022] Open
Abstract
The molecular basis of the earliest neuronal changes that lead to Alzheimer’s disease (AD) is unclear. Here, we analyze neural cells derived from sporadic AD (SAD), APOE4 gene-edited and control induced pluripotent stem cells (iPSCs). We observe major differences in iPSC-derived neural progenitor (NP) cells and neurons in gene networks related to neuronal differentiation, neurogenesis, and synaptic transmission. The iPSC-derived neural cells from SAD patients exhibit accelerated neural differentiation and reduced progenitor cell renewal. Moreover, a similar phenotype appears in NP cells and cerebral organoids derived from APOE4 iPSCs. Impaired function of the transcriptional repressor REST is strongly implicated in the altered transcriptome and differentiation state. SAD and APOE4 expression result in reduced REST nuclear translocation and chromatin binding, and disruption of the nuclear lamina. Thus, dysregulation of neural gene networks may set in motion the pathologic cascade that leads to AD. Meyer et al. derive neural progenitors, neurons, and cerebral organoids from sporadic Alzheimer’s disease (SAD) and APOE4 gene-edited iPSCs. SAD and APOE4 expression alter the neural transcriptome and differentiation in part through loss of function of the transcriptional repressor REST. Thus, neural gene network dysregulation may lead to Alzheimer’s disease.
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Affiliation(s)
- Katharina Meyer
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Heather M Feldman
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Tao Lu
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Derek Drake
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Elaine T Lim
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - King-Hwa Ling
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Nicholas A Bishop
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Ying Pan
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Jinsoo Seo
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yuan-Ta Lin
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Susan C Su
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - George M Church
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Li-Huei Tsai
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Bruce A Yankner
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
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Qi G, Mi Y, Yin F. Cellular Specificity and Inter-cellular Coordination in the Brain Bioenergetic System: Implications for Aging and Neurodegeneration. Front Physiol 2020; 10:1531. [PMID: 31969828 PMCID: PMC6960098 DOI: 10.3389/fphys.2019.01531] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 12/05/2019] [Indexed: 12/21/2022] Open
Abstract
As an organ with a highly heterogenous cellular composition, the brain has a bioenergetic system that is more complex than peripheral tissues. Such complexities are not only due to the diverse bioenergetic phenotypes of a variety of cell types that differentially contribute to the metabolic profile of the brain, but also originate from the bidirectional metabolic communications and coupling across cell types. While brain energy metabolism and mitochondrial function have been extensively investigated in aging and age-associated neurodegenerative disorders, the role of various cell types and their inter-cellular communications in regulating brain metabolic and synaptic functions remains elusive. In this review, we summarize recent advances in differentiating bioenergetic phenotypes of neurons, astrocytes, and microglia in the context of their functional specificity, and their metabolic shifts upon aging and pathological conditions. Moreover, the metabolic coordination between the two most abundant cell populations in brain, neurons and astrocytes, is discussed regarding how they jointly establish a dynamic and responsive system to maintain brain bioenergetic homeostasis and to combat against threats such as oxidative stress, lipid toxicity, and neuroinflammation. Elucidating the mechanisms by which brain cells with distinctive bioenergetic phenotypes individually and collectively shape the bioenergetic system of the brain will provide rationale for spatiotemporally precise interventions to sustain a metabolic equilibrium that is resilient against synaptic dysfunction in aging and neurodegeneration.
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Affiliation(s)
- Guoyuan Qi
- Center for Innovation in Brain Science, University of Arizona Health Sciences, Tucson, AZ, United States
| | - Yashi Mi
- Center for Innovation in Brain Science, University of Arizona Health Sciences, Tucson, AZ, United States
| | - Fei Yin
- Center for Innovation in Brain Science, University of Arizona Health Sciences, Tucson, AZ, United States
- Department of Pharmacology, College of Medicine Tucson, Tucson, AZ, United States
- Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Tucson, AZ, United States
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8
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Czuba E, Steliga A, Lietzau G, Kowiański P. Cholesterol as a modifying agent of the neurovascular unit structure and function under physiological and pathological conditions. Metab Brain Dis 2017; 32:935-948. [PMID: 28432486 PMCID: PMC5504126 DOI: 10.1007/s11011-017-0015-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 04/17/2017] [Indexed: 02/08/2023]
Abstract
The brain, demanding constant level of cholesterol, precisely controls its synthesis and homeostasis. The brain cholesterol pool is almost completely separated from the rest of the body by the functional blood-brain barrier (BBB). Only a part of cholesterol pool can be exchanged with the blood circulation in the form of the oxysterol metabolites such, as 27-hydroxycholesterol (27-OHC) and 24S-hydroxycholesterol (24S-OHC). Not only neurons but also blood vessels and neuroglia, constituting neurovascular unit (NVU), are crucial for the brain cholesterol metabolism and undergo precise regulation by numerous modulators, metabolites and signal molecules. In physiological conditions maintaining the optimal cholesterol concentration is important for the energetic metabolism, composition of cell membranes and myelination. However, a growing body of evidence indicates the consequences of the cholesterol homeostasis dysregulation in several pathophysiological processes. There is a causal relationship between hypercholesterolemia and 1) development of type 2 diabetes due to long-term high-fat diet consumption, 2) significance of the oxidative stress consequences for cerebral amyloid angiopathy and neurodegenerative diseases, 3) insulin resistance on progression of the neurodegenerative brain diseases. In this review, we summarize the current state of knowledge concerning the cholesterol influence upon functioning of the NVU under physiological and pathological conditions.
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Affiliation(s)
- Ewelina Czuba
- Department of Anatomy and Neurobiology, Medical University of Gdańsk, 1 Dębinki Str, 80-211, Gdańsk, Poland.
| | - Aleksandra Steliga
- Department of Health Sciences, Pomeranian University of Słupsk, 64 Bohaterów Westerplatte Str, 76-200, Słupsk, Poland
| | - Grażyna Lietzau
- Department of Anatomy and Neurobiology, Medical University of Gdańsk, 1 Dębinki Str, 80-211, Gdańsk, Poland
| | - Przemysław Kowiański
- Department of Anatomy and Neurobiology, Medical University of Gdańsk, 1 Dębinki Str, 80-211, Gdańsk, Poland
- Department of Health Sciences, Pomeranian University of Słupsk, 64 Bohaterów Westerplatte Str, 76-200, Słupsk, Poland
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van Deijk ALF, Camargo N, Timmerman J, Heistek T, Brouwers JF, Mogavero F, Mansvelder HD, Smit AB, Verheijen MHG. Astrocyte lipid metabolism is critical for synapse development and function in vivo. Glia 2017; 65:670-682. [PMID: 28168742 DOI: 10.1002/glia.23120] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 01/08/2017] [Accepted: 01/10/2017] [Indexed: 12/21/2022]
Abstract
The brain is considered to be autonomous in lipid synthesis with astrocytes producing lipids far more efficiently than neurons. Accordingly, it is generally assumed that astrocyte-derived lipids are taken up by neurons to support synapse formation and function. Initial confirmation of this assumption has been obtained in cell cultures, but whether astrocyte-derived lipids support synapses in vivo is not known. Here, we address this issue and determined the role of astrocyte lipid metabolism in hippocampal synapse formation and function in vivo. Hippocampal protein expression for the sterol regulatory element-binding protein (SREBP) and its target gene fatty acid synthase (Fasn) was found in astrocytes but not in neurons. Diminishing SREBP activity in astrocytes using mice in which the SREBP cleavage-activating protein (SCAP) was deleted from GFAP-expressing cells resulted in decreased cholesterol and phospholipid secretion by astrocytes. Interestingly, SCAP mutant mice showed more immature synapses, lower presynaptic protein SNAP-25 levels as well as reduced numbers of synaptic vesicles, indicating impaired development of the presynaptic terminal. Accordingly, hippocampal short-term and long-term synaptic plasticity were defective in mutant mice. These findings establish a critical role for astrocyte lipid metabolism in presynaptic terminal development and function in vivo. GLIA 2017;65:670-682.
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Affiliation(s)
- Anne-Lieke F van Deijk
- Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Nutabi Camargo
- Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Jaap Timmerman
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Tim Heistek
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Jos F Brouwers
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Yalelaan 1, 3584 CL Utrecht University, Utrecht, The Netherlands
| | - Floriana Mogavero
- Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - August B Smit
- Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Mark H G Verheijen
- Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
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10
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The impairment of cholesterol metabolism in Huntington disease. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1095-105. [DOI: 10.1016/j.bbalip.2014.12.018] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 12/19/2014] [Accepted: 12/21/2014] [Indexed: 02/02/2023]
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Abstract
Cholesterol is an essential component for neuronal physiology not only during development stage but also in the adult life. Cholesterol metabolism in brain is independent from that in peripheral tissues due to blood-brain barrier. The content of cholesterol in brain must be accurately maintained in order to keep brain function well. Defects in brain cholesterol metabolism has been shown to be implicated in neurodegenerative diseases, such as Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), and some cognitive deficits typical of the old age. The brain contains large amount of cholesterol, but the cholesterol metabolism and its complex homeostasis regulation are currently poorly understood. This review will seek to integrate current knowledge about the brain cholesterol metabolism with molecular mechanisms.
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Affiliation(s)
- Juan Zhang
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, 230026 China
| | - Qiang Liu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, 230026 China
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Abstract
Epidemiologic and experimental data suggest the involvement of cholesterol metabolism in the development and progression of Alzheimer disease and Niemann-Pick type C disease, but not of frontotemporal dementias. In these 3 neurodegenerative diseases, however, protein tau hyperphosphorylation and aggregation into neurofibrillary tangles are observed. To elucidate the relationship between cholesterol and tau, we compared sterol levels of neurons burdened with neurofibrillary tangles with those of their unaffected neighbors using semiquantitative filipin fluorescence microscopy in mice expressing P301L mutant human tau (a well-described model of FTDP-17) and in P301L transgenic mice lacking apolipoprotein E (the major cholesterol transporter in the brain). Cellular unesterified cholesterol was higher in neurons affected by tau pathology irrespective of apolipoprotein E deficiency. This argues for an impact of tau pathology on cellular cholesterol homeostasis. We suggest that there is a bidirectional mode of action: Disturbances in cellular cholesterol metabolism may promote tau pathology, but tau pathology may also alter neuronal cholesterol homeostasis; once it is established, a vicious cycle may promote neurofibrillary tangle formation.
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13
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Abad-Rodríguez J. ApoE isoform-related behavioral defects. Is chronic cholesterol loss-driven membrane disorganization behind? Exp Neurol 2013; 241:1-4. [DOI: 10.1016/j.expneurol.2012.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 11/30/2012] [Accepted: 12/07/2012] [Indexed: 10/27/2022]
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14
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Leoni V, Caccia C. 24S-hydroxycholesterol in plasma: a marker of cholesterol turnover in neurodegenerative diseases. Biochimie 2012; 95:595-612. [PMID: 23041502 DOI: 10.1016/j.biochi.2012.09.025] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 09/20/2012] [Indexed: 01/09/2023]
Abstract
Brain cholesterol is mainly involved in the cell membrane structure, in signal transduction, neurotransmitter release, synaptogenesis and membrane trafficking. Impairment of brain cholesterol metabolism was described in neurodegenerative diseases, such as Multiple Sclerosis, Alzheimer and Huntington Diseases. Since the blood-brain barrier efficiently prevents cholesterol uptake from the circulation into the brain, de novo synthesis is responsible for almost all cholesterol present there. Cholesterol is converted into 24S-hydroxycholesterol (24OHC) by cholesterol 24-hydroxylase (CYP46A1) expressed in neural cells. Plasma concentration of 24OHC depends upon the balance between cerebral production and hepatic elimination and is related to the number of metabolically active neurons in the brain. Factors affecting brain cholesterol turnover and liver elimination of oxysterols, together with the metabolism of plasma lipoproteins, genetic background, nutrition and lifestyle habits were found to significantly affect its plasma levels. Either increased or decreased plasma 24OHC concentrations were described in patients with neurodegenerative diseases. A group of evidence suggests that reduced levels of 24OHC are related to the loss of metabolically active cells and the degree of brain atrophy. Inflammation, dysfunction of BBB, increased cholesterol turnover might counteract this tendency resulting in increased levels or, in some cases, in unsignificant changes. The study of plasma 24OHC is likely to offer an insight about brain cholesterol turnover with a limited diagnostic power.
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Affiliation(s)
- Valerio Leoni
- Laboratory of Clinical Pathology and Medical Genetics, Foundation IRCCS Institute of Neurology Carlo Besta, Milan, Italy.
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15
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Apolipoprotein E level and cholesterol are associated with reduced synaptic amyloid beta in Alzheimer's disease and apoE TR mouse cortex. Acta Neuropathol 2012; 123:39-52. [PMID: 22020632 DOI: 10.1007/s00401-011-0892-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 10/12/2011] [Accepted: 10/13/2011] [Indexed: 12/31/2022]
Abstract
The apolipoprotein E4 allele (APOE4) contributes to Alzheimer's disease (AD) risk and APOE2 is protective, but the relevant cellular mechanisms are unknown. We have used flow cytometry analysis to measure apolipoprotein E (apoE) and amyloid beta peptide (Aβ) levels in large populations of synaptic terminals from AD and aged cognitively normal controls, and demonstrate that modest but significant increases in soluble apoE levels accompany elevated Aβ in AD cortical synapses and in an APP/PS1 rat model of AD. Dual labeling experiments document co-localization of apoE and Aβ in individual synapses with concentration of Aβ in a small population of apoE-positive synapses in both AD and controls. Consistent with a clearance role, the apoE level was higher in Aβ-positive synapses in control cases. In aged targeted replacement mice expressing human apoE, apoE2/4 synaptic terminals demonstrated the highest level of apoE and the lowest level of Aβ compared to apoE3/3 and apoE4/4 lines. In apoE2/4 terminals, the pattern of immunolabeling for apoE and Aβ closely resembled the pattern in human control cases, and elevated apoE was accompanied by elevated free cholesterol in apoE2/4 synaptic terminals. These results are consistent with a role for APOE in Aβ clearance in AD synapses, and suggest that optimal lipidation of apoE2 compared to E3 and E4 makes an important contribution to Aβ clearance and synaptic function.
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16
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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: 325] [Impact Index Per Article: 25.0] [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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17
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Boche D, Denham N, Holmes C, Nicoll JAR. Neuropathology after active Abeta42 immunotherapy: implications for Alzheimer's disease pathogenesis. Acta Neuropathol 2010; 120:369-84. [PMID: 20632020 DOI: 10.1007/s00401-010-0719-5] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 07/07/2010] [Accepted: 07/07/2010] [Indexed: 12/26/2022]
Abstract
The amyloid cascade hypothesis of Alzheimer's disease (AD) is testable: it implies that interference with Abeta aggregation and plaque formation may be therapeutically useful. Abeta42 immunisation of amyloid precursor protein (APP) transgenic mice prevented plaque formation and caused removal of existing plaques. The first clinical studies of Abeta immunisation in AD patients (AN1792, Elan Pharmaceuticals) were halted when some patients suffered side effects. Since our confirmation that Abeta immunisation can prompt plaque removal in human AD, we have performed a clinical and neuropathological follow up of AD patients in the initial Elan Abeta immunisation trial. In immunised AD patients, we found: a lower Abeta load, with evidence that plaques had been removed; a reduced tau load in neuronal processes, but not in cell bodies; and no evidence of a beneficial effect on synapses. There were pathological "side effects" including: increased microglial activation; increased cerebral amyloid angiopathy; and there is some evidence for increased soluble/oligomeric Abeta. A pathophysiological mechanism involving effects on the cerebral vasculature is proposed for the clinical side effects observed with some active and passive vaccine protocols. Our current knowledge of the effects of Abeta immunotherapy is based on functional information from the early clinical trials and a few post mortem cases. Several further clinical studies are underway using a variety of protocols and important clinical, imaging and neuropathological data will become available in the near future. The information obtained will be important in helping to understand the pathogenesis not only of AD but also of other neurodegenerative disorders associated with protein aggregation.
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18
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Ong WY, Kim JH, He X, Chen P, Farooqui AA, Jenner AM. Changes in brain cholesterol metabolome after excitotoxicity. Mol Neurobiol 2010; 41:299-313. [PMID: 20140539 DOI: 10.1007/s12035-010-8099-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 01/07/2010] [Indexed: 12/15/2022]
Abstract
Excitotoxicity due to excess stimulation of glutamate receptors in neurons is accompanied by increased Ca(2+) influx, stimulation of Ca(2+)-dependent enzymes, ATP depletion, increase in lipid peroxidation products, and loss of glutathione. These changes resemble neurochemical alterations in acute neuronal injury (stroke, spinal cord injury, and traumatic brain injury) and chronic neurodegenerative diseases such as Alzheimer's disease. Intracerebroventricular injection of the potent glutamate analog kainate in rats results in increased cholesterol concentration in the hippocampus at short to medium time intervals, i.e., 3 days-1 week post-injection, as detected by gas chromatography-mass spectrometry in the lesioned hippocampus. This is accompanied by an early increase in levels of cholesterol biosynthetic precursors and increases in both enzymatically derived oxysterols such as 24-hydroxycholesterol and cholesterol oxidation products (COPs) generated by reactive oxygen species, including cholesterol epoxides and 7-ketocholesterol. In contrast to COPs, no change in concentration of the neurosteroid pregnenolone was found after KA injury. Cholesterol and COPs significantly increase exocytosis in cultured PC12 cells and neurons, and both oxysterols and COPs are able to induce cytotoxic and apoptotic injuries in different cell types, including neurons. Together, the findings suggest that increased cholesterol and COPs after KA excitotoxicity could themselves lead to disturbed neuronal ion homeostasis, increased neurotransmitter release, and propagation of excitotoxicity.
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Affiliation(s)
- Wei-Yi Ong
- Department of Anatomy, National University of Singapore, Singapore, 119260, Singapore.
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19
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Abstract
AbstractGangliosides are membrane glycosphingolipids bearing sialic acid residues. Within membranes, gangliosides are specifically enriched in highly organized domains, lipid rafts, and are attributed with diverse functions such as intercellular interactions, cell recognition, neurotransmission, and signal transduction. The highest concentration and variability of ganglioside structures are found in the human brain. Specific temporal and regional distribution of brain gangliosides has been reported; moreover, gangliosides may serve as markers of neurodevelopmental stages, aging and neurodegeneration. Brain ganglioside content and composition as well as ganglioside metabolism are altered in Alzheimer’s disease. It appears that the alterations of ganglioside metabolism leading to changes in membrane physico-chemical properties are not merely a consequence of primary pathology, but may also be involved in the early pathogenesis of Alzheimer’s disease through documented effects on APP proteolytic processing and amyloid aggregation. Investigations of glycolipid metabolic alterations which accompany neurodegenerative disorders provide insight into pathogenetic mechanisms and enable recognition of diagnostic markers as well as molecular structures acting as therapeutic tools interfering with cascade of pathological events.
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20
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Fraser T, Tayler H, Love S. Fatty acid composition of frontal, temporal and parietal neocortex in the normal human brain and in Alzheimer's disease. Neurochem Res 2009; 35:503-13. [PMID: 19904605 DOI: 10.1007/s11064-009-0087-5] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2009] [Indexed: 11/29/2022]
Abstract
Dietary omega3-polyunsaturated fatty acids are thought to influence the risk of Alzheimer's disease (AD), and supplemental docosahexaenoic acid (DHA; 22:6n-3) has been reported to reduce neurodegeneration in mouse models of AD. We have analysed the fatty acid composition of frontal, temporal and parietal neocortex in 58 normal and 114 AD brains. Significant reductions were found for stearic acid (18:0) in frontal and temporal cortex and arachidonic acid (20:4n-6) in temporal cortex in AD, and increases in oleic acid in frontal and temporal cortex (18:1n-9) and palmitic acid (16:0) in parietal cortex. DHA level varied more in AD than controls but the mean values were not significantly different. Fatty acid composition was not related to APOE genotype, age, gender or post-mortem delay. Further research is needed to distinguish between alterations that are secondary to AD and those that contribute to the disease process.
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Affiliation(s)
- Thomas Fraser
- Dementia Research Group, Institute of Clinical Neurosciences, University of Bristol, Frenchay Hospital, Bristol, BS16 1LE, UK
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Ghribi O. Potential mechanisms linking cholesterol to Alzheimer's disease-like pathology in rabbit brain, hippocampal organotypic slices, and skeletal muscle. J Alzheimers Dis 2009; 15:673-84. [PMID: 19096164 DOI: 10.3233/jad-2008-15412] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Epidemiological, animal, and cellular studies suggest that abnormalities in cholesterol metabolism are important in the pathogenesis of Alzheimer's disease (AD), potentially by increasing amyloid-beta (Abeta) peptide levels. Accumulation of Abeta in the brain is suggested to play a key role in the neurodegenerative processes by triggering the hyperphosphorylation of tau and the neuronal death that develop in the course of AD. However, the mechanisms by which cholesterol increases Abeta levels are still ill-defined. Previous and ongoing work from our laboratory indicates that hypercholesterolemia leads to the increased neuronal content of cholesterol and increased levels and processing of the amyloid-beta protein precursor (AbetaPP). We also have found that the oxidized cholesterol metabolite, 27-hydroxycholesterol, increases Abeta levels in both organotypic hippocampal slices and in neuronal preparations cultured from adult rabbits. This cholesterol metabolite is predominantly formed in the circulation and, in contrast to cholesterol, has the ability to cross into the brain. These results may indicate that 27-hydroxycholesterol is the link between circulating cholesterol and AD-like pathology in the brain. We also have found pathological hallmarks in the skeletal muscle of cholesterol-fed rabbits that are suggestive of inclusion body myositis, a disease that shares some pathological similarities with AD.
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Affiliation(s)
- Othman Ghribi
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, ND 58202, USA.
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22
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Hartmann T. Role of amyloid precursor protein, amyloid-beta and gamma-secretase in cholesterol maintenance. NEURODEGENER DIS 2006; 3:305-11. [PMID: 17047372 DOI: 10.1159/000095271] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Lipids play an important part as risk factors for Alzheimer's disease. This article summarizes the current understanding of the molecular mechanism by which amyloid-beta (Abeta) peptides regulate cholesterol and sphingomyelin metabolism, and how in return cholesterol and sphingomyelin regulate Abeta peptide production. An understanding of the physiological function of amyloid precursor protein processing and Abeta function is critical for the development of future therapeutic approaches, e.g. statin treatment.
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Affiliation(s)
- Tobias Hartmann
- Center for Molecular Biology, University of Heidelberg, Heidelberg, Germany.
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23
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Carter CJ. Convergence of genes implicated in Alzheimer's disease on the cerebral cholesterol shuttle: APP, cholesterol, lipoproteins, and atherosclerosis. Neurochem Int 2006; 50:12-38. [PMID: 16973241 DOI: 10.1016/j.neuint.2006.07.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Revised: 06/30/2006] [Accepted: 07/11/2006] [Indexed: 11/24/2022]
Abstract
Polymorphic genes associated with Alzheimer's disease (see ) delineate a clearly defined pathway related to cerebral and peripheral cholesterol and lipoprotein homoeostasis. They include all of the key components of a glia/neurone cholesterol shuttle including cholesterol binding lipoproteins APOA1, APOA4, APOC1, APOC2, APOC3, APOD, APOE and LPA, cholesterol transporters ABCA1, ABCA2, lipoprotein receptors LDLR, LRP1, LRP8 and VLDLR, and the cholesterol metabolising enzymes CYP46A1 and CH25H, whose oxysterol products activate the liver X receptor NR1H2 and are metabolised to esters by SOAT1. LIPA metabolises cholesterol esters, which are transported by the cholesteryl ester transport protein CETP. The transcription factor SREBF1 controls the expression of most enzymes of cholesterol synthesis. APP is involved in this shuttle as it metabolises cholesterol to 7-betahydroxycholesterol, a substrate of SOAT1 and HSD11B1, binds to APOE and is tethered to LRP1 via APPB1, APBB2 and APBB3 at the cytoplasmic domain and via LRPAP1 at the extracellular domain. APP cleavage products are also able to prevent cholesterol binding to APOE. BACE cleaves both APP and LRP1. Gamma-secretase (PSEN1, PSEN2, NCSTN) cleaves LRP1 and LRP8 as well as APP and their degradation products control transcription factor TFCP2, which regulates thymidylate synthase (TS) and GSK3B expression. GSK3B is known to phosphorylate the microtubule protein tau (MAPT). Dysfunction of this cascade, carved out by genes implicated in Alzheimer's disease, may play a major role in its pathology. Many other genes associated with Alzheimer's disease affect cholesterol or lipoprotein function and/or have also been implicated in atherosclerosis, a feature of Alzheimer's disease, and this duality may well explain the close links between vascular and cerebral pathology in Alzheimer's disease. The definition of many of these genes as risk factors is highly contested. However, when polymorphic susceptibility genes belong to the same signaling pathway, the risk associated with multigenic disease is better related to the integrated effects of multiple polymorphisms of genes within the same pathway than to variants in any single gene [Wu, X., Gu, J., Grossman, H.B., Amos, C.I., Etzel, C., Huang, M., Zhang, Q., Millikan, R.E., Lerner, S., Dinney, C.P., Spitz, M.R., 2006. Bladder cancer predisposition: a multigenic approach to DNA-repair and cell-cycle-control genes. Am. J. Hum. Genet. 78, 464-479.]. Thus, the fact that Alzheimer's disease susceptibility genes converge on a clearly defined signaling network has important implications for genetic association studies.
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24
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Abstract
Cholesterol and the cholesterol oxide 24S-hydroxycholesterol (24S-HC) are highly enriched in the human CNS. Clinical, genetic, neurochemical and epidemiological evidence continue to support dysfunctional cholesterol metabolism as an important contributing factor driving the development and/or progression of Alzheimer's disease (AD) neuropathology. Cholesterol overabundance in the brain plasma membrane lipid- raft domains, appears to be fundamental to the generation of the more neurotoxic forms of amyloid-beta (Abeta) peptide from beta-amyloid holoprotein precursor. 24S-HC may have a pivotal role in promoting altered inflammatory signaling, apoptotic genetic responses and AD-type change. In clinical studies, cholesterol-lowering statins, nonsteroidal anti-inflammatory drugs, cholesterol absorption/transport inhibitors and related modulators of cholesterol trafficking have demonstrated some pharmacological benefit for the treatment of AD, but overall their efficacy at slowing the cognitive decline and the progression of AD remains controversial and open to question.
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Affiliation(s)
- Walter J Lukiw
- Louisiana State University Health Sciences Center, LSU Neuroscience Center and Department of Ophthalmology, 2020 Gravier Street, Suite 8B8, New Orleans, LA 70112-2272, USA.
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25
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Huq MDM, Tsai NP, Gupta P, Wei LN. Regulation of retinal dehydrogenases and retinoic acid synthesis by cholesterol metabolites. EMBO J 2006; 25:3203-13. [PMID: 16763553 PMCID: PMC1500992 DOI: 10.1038/sj.emboj.7601181] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Accepted: 05/15/2006] [Indexed: 11/09/2022] Open
Abstract
Retinoic acid (RA) constitutes the major active ingredient of vitamin A and is required for various biological processes. The tissue RA level is maintained through a cascade of metabolic reactions where retinal dehydrogenases (RALDHs) catalyze the terminal reaction of RA biosynthesis from retinal, a rate-limiting step. We showed that dietary supplement of cholesterol enhanced the expression of RALDH1 and 2 genes and the cellular RA content in vital organs such as brain, kidney, liver and heart. Consistently, the cholesterol-lowering agent (pravastatin sodium) downregulated the expression of RALDH1 and 2 genes in several organs especially the liver and in cultured liver cells. Further, cholesterol metabolites, predominantly the oxysterols, the natural ligands for liver X receptor (LXR), induced these genes via upregulation of sterol regulatory element binding protein-1c (SREBP-1c) that bound to the regulatory regions of these genes. Knockdown of LXRalpha/beta or SREBP-1c downregulated the expression of RALDH genes, which could be rescued by re-expressing SREBP-1c, suggesting SREBP-1c as a direct positive regulator for these genes. This study uncovered a novel crosstalk between cholesterol and RA biosynthesis.
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Affiliation(s)
- M D Mostaqul Huq
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Nien-Pei Tsai
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Pawan Gupta
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Li-Na Wei
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN, USA
- Department of Pharmacology, University of Minnesota Medical School, 6-120 Jackson Hall, 321 Church St SE, Minneapolis, MN 55455, USA. Tel.: +1 612 6259402; Fax: +1 612 6258408; E-mail:
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26
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Graziani A, Rosker C, Kohlwein S, Zhu M, Romanin C, Sattler W, Groschner K, Poteser M. Cellular cholesterol controls TRPC3 function: evidence from a novel dominant-negative knockdown strategy. Biochem J 2006; 396:147-55. [PMID: 16448384 PMCID: PMC1449990 DOI: 10.1042/bj20051246] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
TRPC3 (canonical transient receptor potential protein 3) has been suggested to be a component of cation channel complexes that are targeted to cholesterol-rich lipid membrane microdomains. In the present study, we investigated the potential role of membrane cholesterol as a regulator of cellular TRPC3 conductances. Functional experiments demonstrated that cholesterol loading activates a non-selective cation conductance and a Ca2+ entry pathway in TRPC3-overexpressing cells but not in wild-type HEK-293 (human embryonic kidney 293) cells. The cholesterol-induced membrane conductance exhibited a current-to-voltage relationship similar to that observed upon PLC (phospholipase C)-dependent activation of TRPC3 channels. Nonetheless, the cholesterol-activated conductance lacked negative modulation by extracellular Ca2+, a typical feature of agonist-activated TRPC3 currents. Involvement of TRPC3 in the cholesterol-dependent membrane conductance was further corroborated by a novel dominant-negative strategy for selective blockade of TRPC3 channel activity. Expression of a TRPC3 mutant, which contained a haemagglutinin epitope tag in the second extracellular loop, conferred antibody sensitivity to both the classical PLC-activated as well as the cholesterol-activated conductance in TRPC3-expressing cells. Moreover, cholesterol loading as well as PLC stimulation was found to increase surface expression of TRPC3. Promotion of TRPC3 membrane expression by cholesterol was persistent over 30 min, while PLC-mediated enhancement of plasma membrane expression of TRPC3 was transient in nature. We suggest the cholesterol content of the plasma membrane as a determinant of cellular TRPC3 activity and provide evidence for cholesterol dependence of TRPC3 surface expression.
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Affiliation(s)
- Annarita Graziani
- *Institute of Pharmaceutical Sciences, Pharmacology and Toxicology, Karl-Franzens-University of Graz, Universitaetsplatz 2, A-8010 Graz, Austria
| | - Christian Rosker
- *Institute of Pharmaceutical Sciences, Pharmacology and Toxicology, Karl-Franzens-University of Graz, Universitaetsplatz 2, A-8010 Graz, Austria
| | - Sepp D. Kohlwein
- †Institute of Molecular Biosciences, Karl-Franzens-University of Graz, A-8010 Graz, Austria
| | - Michael X. Zhu
- ‡Department of Neuroscience and Center for Molecular Neurobiology, The Ohio State University, Columbus, OH 43210, U.S.A
| | | | - Wolfgang Sattler
- ∥Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University Graz, A-8010 Graz, Austria
| | - Klaus Groschner
- *Institute of Pharmaceutical Sciences, Pharmacology and Toxicology, Karl-Franzens-University of Graz, Universitaetsplatz 2, A-8010 Graz, Austria
- To whom correspondence should be addressed (email )
| | - Michael Poteser
- *Institute of Pharmaceutical Sciences, Pharmacology and Toxicology, Karl-Franzens-University of Graz, Universitaetsplatz 2, A-8010 Graz, Austria
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