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Romo EZ, Hong BV, Patel RY, Agus JK, Harvey DJ, Maezawa I, Jin LW, Lebrilla CB, Zivkovic AM. Elevated lipopolysaccharide binding protein in Alzheimer's disease patients with APOE3/E3 but not APOE3/E4 genotype. Front Neurol 2024; 15:1408220. [PMID: 38882697 PMCID: PMC11177782 DOI: 10.3389/fneur.2024.1408220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 05/16/2024] [Indexed: 06/18/2024] Open
Abstract
Introduction The role of lipopolysaccharide binding protein (LBP), an inflammation marker of bacterial translocation from the gastrointestinal tract, in Alzheimer's disease (AD) is not clearly understood. Methods In this study the concentrations of LBP were measured in n = 79 individuals: 20 apolipoprotein E (APOE)3/E3 carriers with and 20 without AD dementia, and 19 APOE3/E4 carriers with and 20 without AD dementia. LBP was found to be enriched in the 1.21-1.25 g/mL density fraction of plasma, which has previously been shown to be enriched in intestinally derived high-density lipoproteins (HDL). LBP concentrations were measured by ELISA. Results LBP was significantly increased within the 1.21-1.25 g/mL density fraction of plasma in APOE3/E3 AD patients compared to controls, but not APOE3/E4 patients. LBP was positively correlated with Clinical Dementia Rating (CDR) and exhibited an inverse relationship with Verbal Memory Score (VMS). Discussion These results underscore the potential contribution of gut permeability to bacterial toxins, measured as LBP, as an inflammatory mediator in the development of AD, particularly in individuals with the APOE3/E3 genotype, who are genetically at 4-12-fold lower risk of AD than individuals who express APOE4.
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Affiliation(s)
- Eduardo Z Romo
- Department of Nutrition, University of California, Davis, Davis, CA, United States
| | - Brian V Hong
- Department of Nutrition, University of California, Davis, Davis, CA, United States
| | - Rishi Y Patel
- Department of Nutrition, University of California, Davis, Davis, CA, United States
| | - Joanne K Agus
- Department of Nutrition, University of California, Davis, Davis, CA, United States
| | - Danielle J Harvey
- Department of Public Health Sciences, University of California, Davis, Davis, CA, United States
| | - Izumi Maezawa
- Department of Pathology and Laboratory Medicine, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Lee-Way Jin
- Department of Pathology and Laboratory Medicine, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Carlito B Lebrilla
- Department of Chemistry, University of California, Davis, Davis, CA, United States
| | - Angela M Zivkovic
- Department of Nutrition, University of California, Davis, Davis, CA, United States
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Komai M, Noda Y, Ikeda A, Kaneshiro N, Kamikubo Y, Sakurai T, Uehara T, Takasugi N. Nuclear SphK2/S1P signaling is a key regulator of ApoE production and Aβ uptake in astrocytes. J Lipid Res 2024; 65:100510. [PMID: 38280459 PMCID: PMC10907773 DOI: 10.1016/j.jlr.2024.100510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/29/2024] Open
Abstract
The link between changes in astrocyte function and the pathological progression of Alzheimer's disease (AD) has attracted considerable attention. Interestingly, activated astrocytes in AD show abnormalities in their lipid content and metabolism. In particular, the expression of apolipoprotein E (ApoE), a lipid transporter, is decreased. Because ApoE has anti-inflammatory and amyloid β (Aβ)-metabolizing effects, the nuclear receptors, retinoid X receptor (RXR) and LXR, which are involved in ApoE expression, are considered promising therapeutic targets for AD. However, the therapeutic effects of agents targeting these receptors are limited or vary considerably among groups, indicating the involvement of an unknown pathological factor that modifies astrocyte and ApoE function. Here, we focused on the signaling lipid, sphingosine-1-phosphate (S1P), which is mainly produced by sphingosine kinase 2 (SphK2) in the brain. Using astrocyte models, we found that upregulation of SphK2/S1P signaling suppressed ApoE induction by both RXR and LXR agonists. We also found that SphK2 activation reduced RXR binding to the APOE promoter region in the nucleus, suggesting the nuclear function of SphK2/S1P. Intriguingly, suppression of SphK2 activity by RNA knockdown or specific inhibitors upregulated lipidated ApoE induction. Furthermore, the induced ApoE facilitates Aβ uptake in astrocytes. Together with our previous findings that SphK2 activity is upregulated in AD brain and promotes Aβ production in neurons, these results indicate that SphK2/S1P signaling is a promising multifunctional therapeutic target for AD that can modulate astrocyte function by stabilizing the effects of RXR and LXR agonists, and simultaneously regulate neuronal pathogenesis.
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Affiliation(s)
- Masato Komai
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan; Research Fellow of Japan Society for the Promotion of Science, Chiyoda, Tokyo, Japan
| | - Yuka Noda
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan
| | - Atsuya Ikeda
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan
| | - Nanaka Kaneshiro
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan
| | - Yuji Kamikubo
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo, Tokyo, Japan
| | - Takashi Sakurai
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo, Tokyo, Japan
| | - Takashi Uehara
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan
| | - Nobumasa Takasugi
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan; Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo, Tokyo, Japan.
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Li Y, Chang J, Chen X, Liu J, Zhao L. Advances in the Study of APOE and Innate Immunity in Alzheimer's Disease. J Alzheimers Dis 2023:JAD230179. [PMID: 37182889 DOI: 10.3233/jad-230179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Alzheimer's disease (AD) is a progressive degenerative disease of the nervous system (CNS) with an insidious onset. Clinically, it is characterized by a full range of dementia manifestations including memory impairment, aphasia, loss of speech, loss of use, loss of recognition, impairment of visuospatial skills, and impairment of executive function, as well as changes in personality and behavior. The exact cause of AD has not yet been identified. Nevertheless, modern research indicates that genetic factors contribute to 70% of human's risk of AD. Apolipoprotein (APOE) accounts for up to 90% of the genetic predisposition. APOE is a crucial gene that cannot be overstated. In addition, innate immunity plays a significant role in the etiology and treatment of AD. Understanding the different subtypes of APOE and their interconnections is of paramount importance. APOE and innate immunity, along with their relationship to AD, are primary research motivators for in-depth research and clinical trials. The exploration of novel technologies has led to an increasing trend in the study of AD at the cellular and molecular levels and continues to make more breakthroughs and progress. As of today, there is no effective treatment available for AD around the world. This paper aims to summarize and analyze the role of APOE and innate immunity, as well as development trends in recent years. It is anticipated that APOE and innate immunity will provide a breakthrough for humans to hinder AD progression in the near future.
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Affiliation(s)
- Yujiao Li
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China
- National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, China
| | - Jun Chang
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China
- National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, China
| | - Xi Chen
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China
- National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, China
| | - Jianwei Liu
- Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Lan Zhao
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China
- National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, China
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Mathew A, Balaji E V, Pai SRK, Kishore A, Pai V, Pemmireddy R, K S C. Current Drug Targets in Alzheimer's Associated Memory Impairment: A Comprehensive Review. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2023; 22:255-275. [PMID: 35366787 DOI: 10.2174/1871527321666220401124719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 12/17/2021] [Accepted: 01/19/2022] [Indexed: 12/16/2022]
Abstract
Alzheimer's disease (AD) is the most prevalent form of dementia among geriatrics. It is a progressive, degenerative neurologic disorder that causes memory and cognition loss. The accumulation of amyloid fibrils and neurofibrillary tangles in the brain of AD patients is a distinguishing feature of the disease. Therefore, most of the current therapeutic goals are targeting inhibition of beta-amyloid synthesis and aggregation as well as tau phosphorylation and aggregation. There is also a loss of the cholinergic neurons in the basal forebrain, and first-generation therapeutic agents were primarily focused on compensating for this loss of neurons. However, cholinesterase inhibitors can only alleviate cognitive symptoms of AD and cannot reduce the progression of the disease. Understanding the molecular and cellular changes associated with AD pathology has advanced significantly in recent decades. The etiology of AD is complex, with a substantial portion of sporadic AD emerging from unknown reasons and a lesser proportion of early-onset familial AD (FAD) caused by a mutation in several genes, such as the amyloid precursor protein (APP), presenilin 1 (PS1), and presenilin 2 (PS2) genes. Hence, efforts are being made to discover novel strategies for these targets for AD therapy. A new generation of AChE and BChE inhibitors is currently being explored and evaluated in human clinical trials for AD symptomatic treatment. Other approaches for slowing the progression of AD include serotonergic modulation, H3 receptor antagonism, phosphodiesterase, COX-2, and MAO-B inhibition. The present review provides an insight into the possible therapeutic strategies and their molecular mechanisms, enlightening the perception of classical and future treatment approaches.
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Affiliation(s)
- Anna Mathew
- Department of Pharmacognosy, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Vignesh Balaji E
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Sreedhara Ranganath K Pai
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Anoop Kishore
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Vasudev Pai
- Department of Pharmacognosy, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Ramadevi Pemmireddy
- Department of Pharmacognosy, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Chandrashekar K S
- Department of Pharmacognosy, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
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Noveir SD, Kerman BE, Xian H, Meuret C, Smadi S, Martinez AE, Johansson J, Zetterberg H, Parks BA, Kuklenyik Z, Mack WJ, Johansson JO, Yassine HN. Effect of the ABCA1 agonist CS-6253 on amyloid-β and lipoprotein metabolism in cynomolgus monkeys. Alzheimers Res Ther 2022; 14:87. [PMID: 35751102 PMCID: PMC9229758 DOI: 10.1186/s13195-022-01028-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 06/07/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Inducing brain ATP-binding cassette 1 (ABCA1) activity in Alzheimer's disease (AD) mouse models is associated with improvement in AD pathology. The purpose of this study was to investigate the effects of the ABCA1 agonist peptide CS-6253 on amyloid-β peptides (Aβ) and lipoproteins in plasma and cerebrospinal fluid (CSF) of cynomolgus monkeys, a species with amyloid and lipoprotein metabolism similar to humans. METHODS CS-6253 peptide was injected intravenously into cynomolgus monkeys at various doses in three different studies. Plasma and CSF samples were collected at several time points before and after treatment. Levels of cholesterol, triglyceride (TG), lipoprotein particles, apolipoproteins, and Aβ were measured using ELISA, ion-mobility analysis, and asymmetric-flow field-flow fractionation (AF4). The relationship between the change in levels of these biomarkers was analyzed using multiple linear regression models and linear mixed-effects models. RESULTS Following CS-6253 intravenous injection, within minutes, small plasma high-density lipoprotein (HDL) particles were increased. In two independent experiments, plasma TG, apolipoprotein E (apoE), and Aβ42/40 ratio were transiently increased following CS-6253 intravenous injection. This change was associated with a non-significant decrease in CSF Aβ42. Both plasma total cholesterol and HDL-cholesterol levels were reduced following treatment. AF4 fractionation revealed that CS-6253 treatment displaced apoE from HDL to intermediate-density- and low density-lipoprotein (IDL/LDL)-sized particles in plasma. In contrast to plasma, CS-6253 had no effect on the assessed CSF apolipoproteins or lipids. CONCLUSIONS Treatment with the ABCA1 agonist CS-6253 appears to favor Aβ clearance from the brain.
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Affiliation(s)
- Sasan D Noveir
- Departments of Medicine and Neurology, University of Southern California, Los Angeles, CA, 90033, USA
| | - Bilal E Kerman
- Departments of Medicine and Neurology, University of Southern California, Los Angeles, CA, 90033, USA
| | - Haotian Xian
- Departments of Medicine and Neurology, University of Southern California, Los Angeles, CA, 90033, USA
| | - Cristiana Meuret
- Departments of Medicine and Neurology, University of Southern California, Los Angeles, CA, 90033, USA
| | - Sabrina Smadi
- Departments of Medicine and Neurology, University of Southern California, Los Angeles, CA, 90033, USA
| | - Ashley E Martinez
- Departments of Medicine and Neurology, University of Southern California, Los Angeles, CA, 90033, USA
| | | | - Henrik Zetterberg
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the, Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
- Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, UK
- UK Dementia Research Institute at UCL, London, UK
- Hong Kong Center for Neurodegenerative Diseases, Hong Kong, China
| | - Bryan A Parks
- Centers for Disease Control and Prevention, Atlanta, GA, 30341, USA
| | | | - Wendy J Mack
- Department of Population and Public Health Sciences, University of Southern California, Los Angeles, CA, 90033, USA
| | | | - Hussein N Yassine
- Departments of Medicine and Neurology, University of Southern California, Los Angeles, CA, 90033, USA.
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Lewandowski CT, Laham MS, Thatcher GR. Remembering your A, B, C's: Alzheimer's disease and ABCA1. Acta Pharm Sin B 2022; 12:995-1018. [PMID: 35530134 PMCID: PMC9072248 DOI: 10.1016/j.apsb.2022.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/27/2021] [Accepted: 01/07/2022] [Indexed: 12/24/2022] Open
Abstract
The function of ATP binding cassette protein A1 (ABCA1) is central to cholesterol mobilization. Reduced ABCA1 expression or activity is implicated in Alzheimer's disease (AD) and other disorders. Therapeutic approaches to boost ABCA1 activity have yet to be translated successfully to the clinic. The risk factors for AD development and progression, including comorbid disorders such as type 2 diabetes and cardiovascular disease, highlight the intersection of cholesterol transport and inflammation. Upregulation of ABCA1 can positively impact APOE lipidation, insulin sensitivity, peripheral vascular and blood–brain barrier integrity, and anti-inflammatory signaling. Various strategies towards ABCA1-boosting compounds have been described, with a bias toward nuclear hormone receptor (NHR) agonists. These agonists display beneficial preclinical effects; however, important side effects have limited development. In particular, ligands that bind liver X receptor (LXR), the primary NHR that controls ABCA1 expression, have shown positive effects in AD mouse models; however, lipogenesis and unwanted increases in triglyceride production are often observed. The longstanding approach, focusing on LXRβ vs. LXRα selectivity, is over-simplistic and has failed. Novel approaches such as phenotypic screening may lead to small molecule NHR modulators that elevate ABCA1 function without inducing lipogenesis and are clinically translatable.
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7
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Neuronal ROS-induced glial lipid droplet formation is altered by loss of Alzheimer's disease-associated genes. Proc Natl Acad Sci U S A 2021; 118:2112095118. [PMID: 34949639 PMCID: PMC8719885 DOI: 10.1073/pnas.2112095118] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2021] [Indexed: 01/02/2023] Open
Abstract
A growing list of Alzheimer's disease (AD) genetic risk factors is being identified, but the contribution of each variant to disease mechanism remains largely unknown. We have previously shown that elevated levels of reactive oxygen species (ROS) induces lipid synthesis in neurons leading to the sequestration of peroxidated lipids in glial lipid droplets (LD), delaying neurotoxicity. This neuron-to-glia lipid transport is APOD/E-dependent. To identify proteins that modulate these neuroprotective effects, we tested the role of AD risk genes in ROS-induced LD formation and demonstrate that several genes impact neuroprotective LD formation, including homologs of human ABCA1, ABCA7, VLDLR, VPS26, VPS35, AP2A, PICALM, and CD2AP Our data also show that ROS enhances Aβ42 phenotypes in flies and mice. Finally, a peptide agonist of ABCA1 restores glial LD formation in a humanized APOE4 fly model, highlighting a potentially therapeutic avenue to prevent ROS-induced neurotoxicity. This study places many AD genetic risk factors in a ROS-induced neuron-to-glia lipid transfer pathway with a critical role in protecting against neurotoxicity.
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Kloske CM, Dugan AJ, Weekman EM, Winder Z, Patel E, Nelson PT, Fardo DW, Wilcock DM. Inflammatory Pathways Are Impaired in Alzheimer Disease and Differentially Associated With Apolipoprotein E Status. J Neuropathol Exp Neurol 2021; 80:922-932. [PMID: 34486652 PMCID: PMC8557334 DOI: 10.1093/jnen/nlab085] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Alzheimer disease (AD) is a neurodegenerative disease characterized by a cognitive decline leading to dementia. The most impactful genetic risk factor is apolipoprotein E (APOE). APOE-ε4 significantly increases AD risk, APOE-ε3 is the most common gene variant, and APOE-ε2 protects against AD. However, the underlying mechanisms of APOE-ε4 on AD risk remains unclear, with APOE-ε4 impacting many pathways. We investigated how the APOE isoforms associated with the neuroinflammatory state of the brain with and without AD pathology. Frozen brain tissue from the superior and middle temporal gyrus was analyzed from APOE-ε3/3 (n = 9) or APOE-ε4/4 (n = 10) participants with AD pathology and APOE-ε3/3 (n = 9) participants without AD pathology. We determined transcript levels of 757 inflammatory related genes using the NanoString Human Neuroinflammation Panel. We found significant pathways impaired in APOE-ε4/4-AD individuals compared to APOE-ε3/3-AD. Of interest, expression of genes related to microglial activation (SALL1), motility (FSCN1), epigenetics (DNMT1), and others showed altered expression. Additionally, we performed immunohistochemistry of P2RY12 to confirm reduced microglial activation. Our results suggest APOE-ε3 responds to AD pathology while potentially having a harmful long-term inflammatory response, while APOE-ε4 shows a weakened response to pathology. Overall, APOE isoforms appear to modulate the brain immune response to AD-type pathology.
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Affiliation(s)
- Courtney M Kloske
- From the Department of Physiology, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Adam J Dugan
- Department of Biostatistics, College of Public Health, University of Kentucky, Lexington, Kentucky, USA
| | - Erica M Weekman
- From the Department of Physiology, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Zachary Winder
- From the Department of Physiology, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Ela Patel
- Department of Pathology and Laboratory Medicine, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Peter T Nelson
- Department of Pathology and Laboratory Medicine, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - David W Fardo
- Department of Biostatics, Sanders-Brown Center on Aging, College of Public Health, University of Kentucky, Lexington, Kentucky, USA
| | - Donna M Wilcock
- From the Department of Physiology, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
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Hudák A, Jósvay K, Domonkos I, Letoha A, Szilák L, Letoha T. The Interplay of Apoes with Syndecans in Influencing Key Cellular Events of Amyloid Pathology. Int J Mol Sci 2021; 22:ijms22137070. [PMID: 34209175 PMCID: PMC8268055 DOI: 10.3390/ijms22137070] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/20/2021] [Accepted: 06/28/2021] [Indexed: 01/06/2023] Open
Abstract
Apolipoprotein E (ApoE) isoforms exert intricate effects on cellular physiology beyond lipid transport and metabolism. ApoEs influence the onset of Alzheimer’s disease (AD) in an isoform-dependent manner: ApoE4 increases AD risk, while ApoE2 decreases it. Previously we demonstrated that syndecans, a transmembrane proteoglycan family with increased expression in AD, trigger the aggregation and modulate the cellular uptake of amyloid beta (Aβ). Utilizing our previously established syndecan-overexpressing cellular assays, we now explore how the interplay of ApoEs with syndecans contributes to key events, namely uptake and aggregation, in Aβ pathology. The interaction of ApoEs with syndecans indicates isoform-specific characteristics arising beyond the frequently studied ApoE–heparan sulfate interactions. Syndecans, and among them the neuronal syndecan-3, increased the cellular uptake of ApoEs, especially ApoE2 and ApoE3, while ApoEs exerted opposing effects on syndecan-3-mediated Aβ uptake and aggregation. ApoE2 increased the cellular internalization of monomeric Aβ, hence preventing its extracellular aggregation, while ApoE4 decreased it, thus helping the buildup of extracellular plaques. The contrary effects of ApoE2 and ApoE4 remained once Aβ aggregated: while ApoE2 reduced the uptake of Aβ aggregates, ApoE4 facilitated it. Fibrillation studies also revealed ApoE4′s tendency to form fibrillar aggregates. Our results uncover yet unknown details of ApoE cellular biology and deepen our molecular understanding of the ApoE-dependent mechanism of Aβ pathology.
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Affiliation(s)
- Anett Hudák
- Pharmacoidea Ltd., H-6726 Szeged, Hungary; (A.H.); (L.S.)
| | - Katalin Jósvay
- Institute of Biochemistry, Biological Research Centre, H-6726 Szeged, Hungary;
| | - Ildikó Domonkos
- Institute of Plant Biology, Biological Research Centre, H-6726 Szeged, Hungary;
| | - Annamária Letoha
- Department of Medicine, Albert Szent-Györgyi Clinical Center, Faculty of Medicine, University of Szeged, H-6725 Szeged, Hungary;
| | - László Szilák
- Pharmacoidea Ltd., H-6726 Szeged, Hungary; (A.H.); (L.S.)
| | - Tamás Letoha
- Pharmacoidea Ltd., H-6726 Szeged, Hungary; (A.H.); (L.S.)
- Correspondence: ; Tel.: +36-(30)-2577393
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10
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Samant NP, Gupta GL. Novel therapeutic strategies for Alzheimer's disease targeting brain cholesterol homeostasis. Eur J Neurosci 2020; 53:673-686. [PMID: 32852876 DOI: 10.1111/ejn.14949] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/16/2020] [Accepted: 08/17/2020] [Indexed: 01/04/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common cause of dementia. Aβ plaques and tauopathy are two major concerns associated with AD. Moreover, excessive Aβ accumulation can lead to other nonspecific metabolic brain abnormalities. There are various genetic, environmental, and other risk factors associated with AD. Identification of risk factors and its mechanisms by which these factors impart role in AD pathology would be helpful for the prevention of AD progression. Altered cholesterol homeostasis could be considered as a risk factor for AD progression. Brain cholesterol dysmetabolism is recognized as one of the crucial attributes for AD that affect major hallmarks of AD including neurodegeneration. To fill the gap between altered cholesterol levels in the brain and AD, the researchers started focusing on statins as re-purposing drugs for AD treatment. The various other hypothesis has been suggested due to a lack of beneficial results of statins in clinical trials, such as reduced brain cholesterol could underlie poor cognition. Unfortunately, it is still unclear, whether an increase or decrease in brain cholesterol levels responsible for Alzheimer's disease or not. Presently, scientists believed that managing the level of cholesterol in the brain may help as an alternative treatment strategy for AD. In this review, we focused on the therapeutic strategies for AD by targeting brain cholesterol levels.
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Affiliation(s)
- Nikita Patil Samant
- Shobhaben Pratapbhai Patel School of Pharmacy & Taechnology Management, SVKM'S NMIMS, Mumbai, India
| | - Girdhari Lal Gupta
- Shobhaben Pratapbhai Patel School of Pharmacy & Taechnology Management, SVKM'S NMIMS, Mumbai, India
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11
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The Role of HDL and HDL Mimetic Peptides as Potential Therapeutics for Alzheimer's Disease. Biomolecules 2020; 10:biom10091276. [PMID: 32899606 PMCID: PMC7563116 DOI: 10.3390/biom10091276] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/25/2020] [Accepted: 08/31/2020] [Indexed: 12/11/2022] Open
Abstract
The role of high-density lipoproteins (HDL) in the cardiovascular system has been extensively studied and the cardioprotective effects of HDL are well established. As HDL particles are formed both in the systemic circulation and in the central nervous system, the role of HDL and its associated apolipoproteins in the brain has attracted much research interest in recent years. Alzheimer’s disease (AD) is the most prevalent neurodegenerative disorder and the leading cause of dementia worldwide, for which there currently exists no approved disease modifying treatment. Multiple lines of evidence, including a number of large-scale human clinical studies, have shown a robust connection between HDL levels and AD. Low levels of HDL are associated with increased risk and severity of AD, whereas high levels of HDL are correlated with superior cognitive function. Although the mechanisms underlying the protective effects of HDL in the brain are not fully understood, many of the functions of HDL, including reverse lipid/cholesterol transport, anti-inflammation/immune modulation, anti-oxidation, microvessel endothelial protection, and proteopathy modification, are thought to be critical for its beneficial effects. This review describes the current evidence for the role of HDL in AD and the potential of using small peptides mimicking HDL or its associated apolipoproteins (HDL-mimetic peptides) as therapeutics to treat AD.
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12
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ApoE Lipidation as a Therapeutic Target in Alzheimer's Disease. Int J Mol Sci 2020; 21:ijms21176336. [PMID: 32882843 PMCID: PMC7503657 DOI: 10.3390/ijms21176336] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 08/28/2020] [Accepted: 08/30/2020] [Indexed: 12/19/2022] Open
Abstract
Apolipoprotein E (APOE) is the major cholesterol carrier in the brain, affecting various normal cellular processes including neuronal growth, repair and remodeling of membranes, synaptogenesis, clearance and degradation of amyloid β (Aβ) and neuroinflammation. In humans, the APOE gene has three common allelic variants, termed E2, E3, and E4. APOE4 is considered the strongest genetic risk factor for Alzheimer’s disease (AD), whereas APOE2 is neuroprotective. To perform its normal functions, apoE must be secreted and properly lipidated, a process influenced by the structural differences associated with apoE isoforms. Here we highlight the importance of lipidated apoE as well as the APOE-lipidation targeted therapeutic approaches that have the potential to correct or prevent neurodegeneration. Many of these approaches have been validated using diverse cellular and animal models. Overall, there is great potential to improve the lipidated state of apoE with the goal of ameliorating APOE-associated central nervous system impairments.
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Kloske CM, Wilcock DM. The Important Interface Between Apolipoprotein E and Neuroinflammation in Alzheimer's Disease. Front Immunol 2020; 11:754. [PMID: 32425941 PMCID: PMC7203730 DOI: 10.3389/fimmu.2020.00754] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 04/02/2020] [Indexed: 12/13/2022] Open
Abstract
Alzheimer’s disease (AD) is the most prevalent form of neurodegenerative disease, currently affecting over 5 million Americans with projections expected to rise as the population ages. The hallmark pathologies of AD are Aβ plaques composed of aggregated beta-amyloid (Aβ), and tau tangles composed of hyperphosphorylated, aggregated tau. These pathologies are typically accompanied by an increase in neuroinflammation as an attempt to ameliorate the pathology. This idea has pushed the field toward focusing on mechanisms and the influence neuroinflammation has on disease progression. The vast majority of AD cases are sporadic and therefore, researchers investigate genetic risk factors that could lead to AD. Apolipoprotein E (ApoE) is the largest genetic risk factor for developing AD. ApoE has 3 isoforms-ApoE2, ApoE3, and ApoE4. ApoE4 constitutes an increased risk of AD, with one copy increasing the risk about 4-fold and two copies increasing the risk about 15-fold compared to those with the ApoE3 allele. ApoE4 has been shown to play a role in Aβ deposition, tau tangle formation, neuroinflammation and many subsequent pathways. However, while we know that ApoE4 plays a role in these pathways and virtually all aspects of AD, the exact mechanism of how ApoE4 impacts AD progression is murky at best and therefore the role ApoE4 plays in these pathways needs to be elucidated. This review aims to discuss the current literature regarding the pathways and mechanisms of ApoE4 in AD progression with a focus on its role in neuroinflammation.
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Affiliation(s)
- Courtney M Kloske
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - Donna M Wilcock
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
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Central and Peripheral Mechanisms in ApoE4-Driven Diabetic Pathology. Int J Mol Sci 2020; 21:ijms21041289. [PMID: 32075060 PMCID: PMC7072920 DOI: 10.3390/ijms21041289] [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: 12/22/2019] [Revised: 01/27/2020] [Accepted: 02/03/2020] [Indexed: 12/16/2022] Open
Abstract
Apolipoprotein E (APOE) ε4 gene allele and type 2 diabetes mellitus (T2DM) are prime risk factors for Alzheimer’s disease (AD). Despite evidence linking T2DM and apoE4, the mechanism underlying their interaction is yet to be determined. In the present study, we employed a model of APOE-targeted replacement mice and high-fat diet (HFD)-induced insulin resistance to investigate diabetic mechanisms associated with apoE4 pathology and the extent to which they are driven by peripheral and central processes. Results obtained revealed an intriguing pattern, in which under basal conditions, apoE4 mice display impaired glucose and insulin tolerance and decreased insulin secretion, as well as cognitive and sensorimotor characteristics relative to apoE3 mice, while the HFD impairs apoE3 mice without significantly affecting apoE4 mice. Measurements of weight and fasting blood glucose levels increased in a time-dependent manner following the HFD, though no effect of genotype was observed. Interestingly, sciatic electrophysiological and skin intra-epidermal nerve fiber density (IENFD) peripheral measurements were not affected by the APOE genotype or HFD, suggesting that the observed sensorimotor and cognitive phenotypes are related to central nervous system processes. Indeed, measurements of hippocampal insulin receptor and glycogen synthase kinase-3β (GSK-3β) activation revealed a pattern similar to that obtained in the behavioral measurements while Akt activation presented a dominant effect of diet. HFD manipulation induced genotype-independent hyperlipidation of apoE, and reduced levels of brain apoE in apoE3 mice, rendering them similar to apoE4 mice, whose brain apoE levels were not affected by the diet. No such effect was observed in the peripheral plasma levels of apoE, suggesting that the pathological effects of apoE4 under the control diet and apoE3 under HFD conditions are related to the decreased levels of brain apoE. Taken together, our data suggests that diabetic mechanisms play an important role in mediating the pathological effects of apoE4 and that consequently, diabetic-related therapy may be useful in treating apoE4 pathology in AD.
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Williams T, Borchelt DR, Chakrabarty P. Therapeutic approaches targeting Apolipoprotein E function in Alzheimer's disease. Mol Neurodegener 2020; 15:8. [PMID: 32005122 PMCID: PMC6995170 DOI: 10.1186/s13024-020-0358-9] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 01/14/2020] [Indexed: 12/12/2022] Open
Abstract
One of the primary genetic risk factors for Alzheimer’s disease (AD) is the presence of the Ɛ4 allele of apolipoprotein E (APOE). APOE is a polymorphic lipoprotein that is a major cholesterol carrier in the brain. It is also involved in various cellular functions such as neuronal signaling, neuroinflammation and glucose metabolism. Humans predominantly possess three different allelic variants of APOE, termed E2, E3, and E4, with the E3 allele being the most common. The presence of the E4 allele is associated with increased risk of AD whereas E2 reduces the risk. To understand the molecular mechanisms that underlie APOE-related genetic risk, considerable effort has been devoted towards developing cellular and animal models. Data from these models indicate that APOE4 exacerbates amyloid β plaque burden in a dose-dependent manner. and may also enhance tau pathogenesis in an isoform-dependent manner. Other studies have suggested APOE4 increases the risk of AD by mechanisms that are distinct from modulation of Aβ or tau pathology. Further, whether plasma APOE, by influencing systemic metabolic pathways, can also possibly alter CNS function indirectly is not complete;y understood. Collectively, the available studies suggest that APOE may impact multiple signaling pathways and thus investigators have sought therapeutics that would disrupt pathological functions of APOE while preserving or enhancing beneficial functions. This review will highlight some of the therapeutic strategies that are currently being pursued to target APOE4 towards preventing or treating AD and we will discuss additional strategies that holds promise for the future.
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Affiliation(s)
- Tosha Williams
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.,Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA
| | - David R Borchelt
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.,Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.,McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA
| | - Paramita Chakrabarty
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA. .,Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA. .,McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA.
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APOE in the normal brain. Neurobiol Dis 2020; 136:104724. [PMID: 31911114 DOI: 10.1016/j.nbd.2019.104724] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/19/2019] [Accepted: 12/31/2019] [Indexed: 12/25/2022] Open
Abstract
The APOE4 protein affects the primary neuropathological markers of Alzheimer's disease (AD): amyloid plaques, neurofibrillary tangles, and gliosis. These interactions have been investigated to understand the strong effect of APOE genotype on risk of AD. However, APOE genotype has strong effects on processes in normal brains, in the absence of the hallmarks of AD. We propose that CNS APOE is involved in processes in the normal brains that in later years apply specifically to processes of AD pathogenesis. We review the differences of the APOE protein found in the CNS compared to the plasma, including post-translational modifications (glycosylation, lipidation, multimer formation), focusing on ways that the common APOE isoforms differ from each other. We also review structural and functional studies of young human brains and control APOE knock-in mouse brains. These approaches demonstrate the effects of APOE genotype on microscopic neuron structure, gross brain structure, and behavior, primarily related to the hippocampal areas. By focusing on the effects of APOE genotype on normal brain function, approaches can be pursued to identify biomarkers of APOE dysfunction, to promote normal functions of the APOE4 isoform, and to prevent the accumulation of the pathologic hallmarks of AD with aging.
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Torres S, García-Ruiz CM, Fernandez-Checa JC. Mitochondrial Cholesterol in Alzheimer's Disease and Niemann-Pick Type C Disease. Front Neurol 2019; 10:1168. [PMID: 31787922 PMCID: PMC6854033 DOI: 10.3389/fneur.2019.01168] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 10/18/2019] [Indexed: 02/05/2023] Open
Abstract
Mitochondrial dysfunction has been recognized as a key player in neurodegenerative diseases, including Alzheimer's disease (AD) and Niemann–Pick type C (NPC) disease. While the pathogenesis of both diseases is different, disruption of intracellular cholesterol trafficking has emerged as a common feature of both AD and NPC disease. Nutritional or genetic mitochondrial cholesterol accumulation sensitizes neurons to Aβ-mediated neurotoxicity in vitro and promotes cognitive decline in AD models. In addition to the primary accumulation of cholesterol and sphingolipids in lysosomes, NPC disease is also characterized by an increase in mitochondrial cholesterol levels in affected organs, predominantly in brain and liver. In both diseases, mitochondrial cholesterol accumulation disrupts membrane physical properties and restricts the transport of glutathione into mitochondrial matrix, thus impairing the mitochondrial antioxidant defense strategy. The underlying mechanisms leading to mitochondrial cholesterol accumulation in AD and NPC diseases are not fully understood. In the present manuscript, we discuss evidence for the potential role of StARD1 in promoting the trafficking of cholesterol to mitochondria in AD and NPC, whose upregulation involves an endoplasmic reticulum stress and a decrease in acid ceramidase expression, respectively. These findings imply that targeting StARD1 or boosting the mitochondrial antioxidant defense may emerge as a promising approach for both AD and NPC disease.
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Affiliation(s)
- Sandra Torres
- Department of Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.,Liver Unit and Hospital Clinc I Provincial, Centro de Investigación Biomédica en Red (CIBEREHD), Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Carmen M García-Ruiz
- Department of Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.,Liver Unit and Hospital Clinc I Provincial, Centro de Investigación Biomédica en Red (CIBEREHD), Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.,Southern California Research Center for ALDP and Cirrhosis, Los Angeles, CA, United States
| | - Jose C Fernandez-Checa
- Department of Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.,Liver Unit and Hospital Clinc I Provincial, Centro de Investigación Biomédica en Red (CIBEREHD), Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.,Southern California Research Center for ALDP and Cirrhosis, Los Angeles, CA, United States
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Abstract
BACKGROUND The growing body of evidence indicating the heterogeneity of Alzheimer's disease (AD), coupled with disappointing clinical studies directed at a fit-for-all therapy, suggest that the development of a single magic cure suitable for all cases may not be possible. This calls for a shift in paradigm where targeted treatment is developed for specific AD subpopulations that share distinct genetic or pathological properties. Apolipoprotein E4 (apoE4), the most prevalent genetic risk factor of AD, is expressed in more than half of AD patients and is thus an important possible AD therapeutic target. REVIEW This review focuses initially on the pathological effects of apoE4 in AD, as well as on the corresponding cellular and animal models and the suggested cellular and molecular mechanisms which mediate them. The second part of the review focuses on recent apoE4-targeted (from the APOE gene to the apoE protein and its interactors) therapeutic approaches that have been developed in animal models and are ready to be translated to human. Further, the issue of whether the pathological effects of apoE4 are due to loss of protective function or due to gain of toxic function is discussed herein. It is possible that both mechanisms coexist, with certain constituents of the apoE4 molecule and/or its downstream signaling mediating a toxic effect, while others are associated with a loss of protective function. CONCLUSION ApoE4 is a promising AD therapeutic target that remains understudied. Recent studies are now paving the way for effective apoE4-directed AD treatment approaches.
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Cell-specific and region-specific transcriptomics in the multiple sclerosis model: Focus on astrocytes. Proc Natl Acad Sci U S A 2018; 115:E302-E309. [PMID: 29279367 PMCID: PMC5777065 DOI: 10.1073/pnas.1716032115] [Citation(s) in RCA: 168] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Changes in gene expression that occur across the central nervous system (CNS) during neurological diseases do not address the heterogeneity of cell types from one CNS region to another and are complicated by alterations in cellular composition during disease. Multiple sclerosis (MS) is multifocal by definition. Here, a cell-specific and region-specific transcriptomics approach was used to determine gene expression changes in astrocytes in the most widely used MS model, experimental autoimmune encephalomyelitis (EAE). Astrocyte-specific RNAs from various neuroanatomic regions were attained using RiboTag technology. Sequencing and bioinformatics analyses showed that EAE-induced gene expression changes differed between neuroanatomic regions when comparing astrocytes from spinal cord, cerebellum, cerebral cortex, and hippocampus. The top gene pathways that were changed in astrocytes from spinal cord during chronic EAE involved decreases in expression of cholesterol synthesis genes while immune pathway gene expression in astrocytes was increased. Optic nerve from EAE and optic chiasm from MS also showed decreased cholesterol synthesis gene expression. The potential role of cholesterol synthesized by astrocytes during EAE and MS is discussed. Together, this provides proof-of-concept that a cell-specific and region-specific gene expression approach can provide potential treatment targets in distinct neuroanatomic regions during multifocal neurological diseases.
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Arenas F, Garcia-Ruiz C, Fernandez-Checa JC. Intracellular Cholesterol Trafficking and Impact in Neurodegeneration. Front Mol Neurosci 2017; 10:382. [PMID: 29204109 PMCID: PMC5698305 DOI: 10.3389/fnmol.2017.00382] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/02/2017] [Indexed: 12/13/2022] Open
Abstract
Cholesterol is a critical component of membrane bilayers where it plays key structural and functional roles by regulating the activity of diverse signaling platforms and pathways. Particularly enriched in brain, cholesterol homeostasis in this organ is singular with respect to other tissues and exhibits a heterogeneous regulation in distinct brain cell populations. Due to the key role of cholesterol in brain physiology and function, alterations in cholesterol homeostasis and levels have been linked to brain diseases and neurodegeneration. In the case of Alzheimer disease (AD), however, this association remains unclear with evidence indicating that either increased or decreased total brain cholesterol levels contribute to this major neurodegenerative disease. Here, rather than analyzing the role of total cholesterol levels in neurodegeneration, we focus on the contribution of intracellular cholesterol pools, particularly in endolysosomes and mitochondria through its trafficking via specialized membrane domains delineated by the contacts between endoplasmic reticulum and mitochondria, in the onset of prevalent neurodegenerative diseases such as AD, Parkinson disease, and Huntington disease as well as in lysosomal disorders like Niemann-Pick type C disease. We dissect molecular events associated with intracellular cholesterol accumulation, especially in mitochondria, an event that results in impaired mitochondrial antioxidant defense and function. A better understanding of the mechanisms involved in the distribution of cholesterol in intracellular compartments may shed light on the role of cholesterol homeostasis disruption in neurodegeneration and may pave the way for specific intervention opportunities.
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Affiliation(s)
- Fabian Arenas
- Department of Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
- Liver Unit and Hospital Clinic I Provincial, IDIBAPS, Barcelona, Spain
- Centro de Investigación Biomédica en Red, CIBEREHD, Barcelona, Spain
| | - Carmen Garcia-Ruiz
- Department of Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
- Liver Unit and Hospital Clinic I Provincial, IDIBAPS, Barcelona, Spain
- Centro de Investigación Biomédica en Red, CIBEREHD, Barcelona, Spain
- Southern California Research Center for ALDP and Cirrhosis, Los Angeles, CA, United States
| | - Jose C. Fernandez-Checa
- Department of Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
- Liver Unit and Hospital Clinic I Provincial, IDIBAPS, Barcelona, Spain
- Centro de Investigación Biomédica en Red, CIBEREHD, Barcelona, Spain
- Southern California Research Center for ALDP and Cirrhosis, Los Angeles, CA, United States
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Bar R, Boehm-Cagan A, Luz I, Kleper-Wall Y, Michaelson DM. The effects of apolipoprotein E genotype, α-synuclein deficiency, and sex on brain synaptic and Alzheimer's disease-related pathology. ALZHEIMER'S & DEMENTIA: DIAGNOSIS, ASSESSMENT & DISEASE MONITORING 2017; 10:1-11. [PMID: 29159264 PMCID: PMC5678739 DOI: 10.1016/j.dadm.2017.08.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Introduction Alzheimer's disease (AD) and synucleinopathies share common pathological mechanisms. Apolipoprotein E4 (apoE4), the most prevalent genetic risk factor for AD, also increases the risk for dementia in pure synucleinopathies. We presently examined the effects of α-synuclein deficiency (α-syn−/−) and sex on apoE4-driven pathologies. Methods AD-related, synaptic, and vascular markers were analyzed in female and male α-syn−/− and α-syn+/+ apoE4, apoE3, and apoE3/E4 mice. Results ApoE4 was hypolipidated, and this effect was unchanged by α-syn−/− and sex. The levels of synaptic markers were lower, and the levels of AD-related parameters were higher in female α-syn−/− apoE4 mice compared with the corresponding apoE3 mice. By comparison, apoE4 had small effects on the AD parameters of male and female α-syn+/+ apoE4 mice. Discussion Although α-syn−/− does not affect the upstream lipidation impairment of apoE4, it acts as a “second hit” enhancer of the subsequent apoE4-driven pathologies.
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Affiliation(s)
- Roni Bar
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Anat Boehm-Cagan
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Ishai Luz
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Yarden Kleper-Wall
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Daniel M Michaelson
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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Astrocytic transporters in Alzheimer's disease. Biochem J 2017; 474:333-355. [DOI: 10.1042/bcj20160505] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 11/16/2016] [Accepted: 11/29/2016] [Indexed: 12/26/2022]
Abstract
Astrocytes play a fundamental role in maintaining the health and function of the central nervous system. Increasing evidence indicates that astrocytes undergo both cellular and molecular changes at an early stage in neurological diseases, including Alzheimer's disease (AD). These changes may reflect a change from a neuroprotective to a neurotoxic phenotype. Given the lack of current disease-modifying therapies for AD, astrocytes have become an interesting and viable target for therapeutic intervention. The astrocyte transport system covers a diverse array of proteins involved in metabolic support, neurotransmission and synaptic architecture. Therefore, specific targeting of individual transporter families has the potential to suppress neurodegeneration, a characteristic hallmark of AD. A small number of the 400 transporter superfamilies are expressed in astrocytes, with evidence highlighting a fraction of these are implicated in AD. Here, we review the current evidence for six astrocytic transporter subfamilies involved in AD, as reported in both animal and human studies. This review confirms that astrocytes are indeed a viable target, highlights the complexities of studying astrocytes and provides future directives to exploit the potential of astrocytes in tackling AD.
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