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Area-Gomez E, Schon EA. Towards a Unitary Hypothesis of Alzheimer's Disease Pathogenesis. J Alzheimers Dis 2024; 98:1243-1275. [PMID: 38578892 DOI: 10.3233/jad-231318] [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] [Indexed: 04/07/2024]
Abstract
The "amyloid cascade" hypothesis of Alzheimer's disease (AD) pathogenesis invokes the accumulation in the brain of plaques (containing the amyloid-β protein precursor [AβPP] cleavage product amyloid-β [Aβ]) and tangles (containing hyperphosphorylated tau) as drivers of pathogenesis. However, the poor track record of clinical trials based on this hypothesis suggests that the accumulation of these peptides is not the only cause of AD. Here, an alternative hypothesis is proposed in which the AβPP cleavage product C99, not Aβ, is the main culprit, via its role as a regulator of cholesterol metabolism. C99, which is a cholesterol sensor, promotes the formation of mitochondria-associated endoplasmic reticulum (ER) membranes (MAM), a cholesterol-rich lipid raft-like subdomain of the ER that communicates, both physically and biochemically, with mitochondria. We propose that in early-onset AD (EOAD), MAM-localized C99 is elevated above normal levels, resulting in increased transport of cholesterol from the plasma membrane to membranes of intracellular organelles, such as ER/endosomes, thereby upregulating MAM function and driving pathology. By the same token, late-onset AD (LOAD) is triggered by any genetic variant that increases the accumulation of intracellular cholesterol that, in turn, boosts the levels of C99 and again upregulates MAM function. Thus, the functional cause of AD is upregulated MAM function that, in turn, causes the hallmark disease phenotypes, including the plaques and tangles. Accordingly, the MAM hypothesis invokes two key interrelated elements, C99 and cholesterol, that converge at the MAM to drive AD pathogenesis. From this perspective, AD is, at bottom, a lipid disorder.
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Affiliation(s)
- Estela Area-Gomez
- Department of Neurology, Columbia University, New York, NY, USA
- Centro de Investigaciones Biológicas "Margarita Salas", Spanish National Research Council, Madrid, Spain
| | - Eric A Schon
- Department of Neurology, Columbia University, New York, NY, USA
- Department of Genetics and Development>, Columbia University, New York, NY, USA
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2
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Gamit N, Patil M, B Sundrappa S, Sundaram SM, Sethi G, Dharmarajan A, Warrier S. Mesenchymal stem cell-derived rapid drug screening system for Alzheimer's disease for the identification of novel drugs. Drug Dev Res 2023; 84:1496-1512. [PMID: 37571798 DOI: 10.1002/ddr.22102] [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: 02/14/2023] [Revised: 06/11/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023]
Abstract
A reliable and efficient in vitro model is needed to screen drugs for Alzheimer's disease (AD), as many drugs are currently in the developmental stage. To address this, we developed an in vitro model using amniotic membrane-derived mesenchymal stem cells (AM-MSCs) to screen novel drugs for AD. We differentiated AM-MSCs into neurons and degenerated them using beta amyloid1-42 (Aß). We then tested AD drugs, which are commercially available such as donepezil, rivastigmine, memantine, citicoline, and two novel drugs, that is, probucol, an anti-hyperlipidaemic drug, and NMJ-2, a cinnamic acid analogue for their potential to protect the cells against neurodegeneration. We used gene expression and immunofluorescence staining to assess the neuroprotective ability of these drugs. We also measured the ability of these drugs to reduce lactate dehydrogenase, reactive oxygen species, and nitric oxide levels, as well as their ability to stabilize the mitochondrial membrane potential and increase acetylcholine (ACh) levels. The AD drugs and novel drugs reduced cytotoxicity and oxidative stress, stabilized mitochondrial membrane potential, and restored ACh levels. Furthermore, they reduced BACE1 expression, with a concomitant increase in the expression of cholinergic markers. This AM-MSCs-based AD-like model has immense potential to be an accurate human model and an alternative to animal models for testing a large number of lead compounds in a short time. Our results also suggest that the novel drugs probucol and NMJ-2 may protect against Aß-induced neurodegeneration.
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Affiliation(s)
- Naisarg Gamit
- Division of Cancer Stem Cells and Cardiovascular Regeneration, Manipal Institute of Regenerative Medicine, Manipal Academy of Higher Education (MAHE), Bangalore, India
| | - Manasi Patil
- Division of Cancer Stem Cells and Cardiovascular Regeneration, Manipal Institute of Regenerative Medicine, Manipal Academy of Higher Education (MAHE), Bangalore, India
| | - Soumya B Sundrappa
- Division of Cancer Stem Cells and Cardiovascular Regeneration, Manipal Institute of Regenerative Medicine, Manipal Academy of Higher Education (MAHE), Bangalore, India
| | - S Mohana Sundaram
- Division of Cancer Stem Cells and Cardiovascular Regeneration, Manipal Institute of Regenerative Medicine, Manipal Academy of Higher Education (MAHE), Bangalore, India
| | - Gautam Sethi
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Arun Dharmarajan
- Department of Biomedical Sciences, Faculty of Biomedical Sciences and Technology, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Sudha Warrier
- Division of Cancer Stem Cells and Cardiovascular Regeneration, Manipal Institute of Regenerative Medicine, Manipal Academy of Higher Education (MAHE), Bangalore, India
- Cuor Stem Cellutions Pvt Ltd, Manipal Institute of Regenerative Medicine, Manipal Academy of Higher Education (MAHE), Bangalore, India
- Department of Biotechnology, Faculty of Biomedical Sciences and Technology, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
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3
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Rudajev V, Novotny J. Cholesterol-dependent amyloid β production: space for multifarious interactions between amyloid precursor protein, secretases, and cholesterol. Cell Biosci 2023; 13:171. [PMID: 37705117 PMCID: PMC10500844 DOI: 10.1186/s13578-023-01127-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 09/05/2023] [Indexed: 09/15/2023] Open
Abstract
Amyloid β is considered a key player in the development and progression of Alzheimer's disease (AD). Many studies investigating the effect of statins on lowering cholesterol suggest that there may be a link between cholesterol levels and AD pathology. Since cholesterol is one of the most abundant lipid molecules, especially in brain tissue, it affects most membrane-related processes, including the formation of the most dangerous form of amyloid β, Aβ42. The entire Aβ production system, which includes the amyloid precursor protein (APP), β-secretase, and the complex of γ-secretase, is highly dependent on membrane cholesterol content. Moreover, cholesterol can affect amyloidogenesis in many ways. Cholesterol influences the stability and activity of secretases, but also dictates their partitioning into specific cellular compartments and cholesterol-enriched lipid rafts, where the amyloidogenic machinery is predominantly localized. The most complicated relationships have been found in the interaction between cholesterol and APP, where cholesterol affects not only APP localization but also the precise character of APP dimerization and APP processing by γ-secretase, which is important for the production of Aβ of different lengths. In this review, we describe the intricate web of interdependence between cellular cholesterol levels, cholesterol membrane distribution, and cholesterol-dependent production of Aβ, the major player in AD.
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Affiliation(s)
- Vladimir Rudajev
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jiri Novotny
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
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Huang Y, Zhang W, Guo X, Zhang Y, Wu J, Zu H. Cellular cholesterol loss by DHCR24 knockdown leads to Aβ production by changing APP intracellular localization. J Lipid Res 2023; 64:100367. [PMID: 37011864 PMCID: PMC10173783 DOI: 10.1016/j.jlr.2023.100367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/23/2023] [Accepted: 03/16/2023] [Indexed: 04/03/2023] Open
Abstract
For the past 20 years, the majority of cell culture studies reported that increasing cholesterol level increases amyloid-β (Aβ) production. Conversely, other studies and genetic evidences support that cellular cholesterol loss leads to Aβ generation. As a highly controversial issue in Alzheimer's disease (AD) pathogenesis,the apparent contradiction prompted us to again explore the role of cellular cholesterol in Aβ production. Here, we adopted new neuronal and astrocytic cell models induced by 3β-hydroxysterol-Δ24 reductase (DHCR24), which obviously differ from the widely used cell models with overexpressing amyloid precursor protein (APP) in the majority of previous studies. In neuronal and astrocytic cell model, we found that deficiency of cellular cholesterol by DHCR24 knock-down obviously increased intracellular and extracellular Aβ generation. Importantly, in cell models with overexpressing APP, we found that APP overexpression could disrupt cellular cholesterol homeostasis and affect function of cells, coupled with the increase of APP β-cleavage product, 99-residue transmembrane C-terminal domain (C99). Therefore, we suppose the results derived from the APP knock-in models will need to be re-evaluated. One rational explanation for the discrepancy between our outcomes and the previous studies could be attributed to the two different cell models. Mechanistically, we showed that cellular cholesterol loss obviously altered APP intracellular localization by affecting cholesterol-related trafficking protein of APP. Therefore, our outcomes strongly support cellular cholesterol loss by DHCR24 knockdown leads to Aβ production.
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Robinson MJ, Newbury S, Singh K, Leonenko Z, Beazely MA. The Interplay Between Cholesterol and Amyloid-β on HT22 Cell Viability, Morphology, and Receptor Tyrosine Kinase Signaling. J Alzheimers Dis 2023; 96:1663-1683. [PMID: 38073391 DOI: 10.3233/jad-230753] [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] [Indexed: 12/18/2023]
Abstract
BACKGROUND There is a lack of understanding in the molecular and cellular mechanisms of Alzheimer's disease that has hindered progress on therapeutic development. The focus has been on targeting toxic amyloid-β (Aβ) pathology, but these therapeutics have generally failed in clinical trials. Aβ is an aggregation-prone protein that has been shown to disrupt cell membrane structure in molecular biophysics studies and interfere with membrane receptor signaling in cell and animal studies. Whether the lipid membrane or specific receptors are the primary target of attack has not been determined. OBJECTIVE This work elucidates some of the interplay between membrane cholesterol and Aβ42 on HT22 neuronal cell viability, morphology, and platelet-derived growth factor (PDGF) signaling pathways. METHODS The effects of cholesterol depletion by methyl-β-cyclodextrin followed by treatment with Aβ and/or PDGF-AA were assessed by MTT cell viability assays, western blot, optical and AFM microscopy. RESULTS Cell viability studies show that cholesterol depletion was mildly protective against Aβ toxicity. Together cholesterol reduction and Aβ42 treatment compounded the disruption of the PDGFα receptor activation. Phase contrast optical microscopy and live cell atomic force microscopy imaging revealed that cytotoxic levels of Aβ42 caused morphological changes including cell membrane damage, cytoskeletal disruption, and impaired cell adhesion; cell damage was ameliorated by cellular cholesterol depletion. CONCLUSIONS Cholesterol depletion impacted the effects of Aβ42 on HT22 cell viability, morphology, and receptor tyrosine kinase signaling.
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Affiliation(s)
- Morgan J Robinson
- School of Pharmacy, University of Waterloo, Waterloo, ON, Canada
- Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, Canada
| | - Sean Newbury
- School of Pharmacy, University of Waterloo, Waterloo, ON, Canada
| | - Kartar Singh
- School of Pharmacy, University of Waterloo, Waterloo, ON, Canada
| | - Zoya Leonenko
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
- Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada
- Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, Canada
| | - Michael A Beazely
- School of Pharmacy, University of Waterloo, Waterloo, ON, Canada
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
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Kovacs T, Nagy P, Panyi G, Szente L, Varga Z, Zakany F. Cyclodextrins: Only Pharmaceutical Excipients or Full-Fledged Drug Candidates? Pharmaceutics 2022; 14:pharmaceutics14122559. [PMID: 36559052 PMCID: PMC9788615 DOI: 10.3390/pharmaceutics14122559] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 11/15/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022] Open
Abstract
Cyclodextrins, representing a versatile family of cyclic oligosaccharides, have extensive pharmaceutical applications due to their unique truncated cone-shaped structure with a hydrophilic outer surface and a hydrophobic cavity, which enables them to form non-covalent host-guest inclusion complexes in pharmaceutical formulations to enhance the solubility, stability and bioavailability of numerous drug molecules. As a result, cyclodextrins are mostly considered as inert carriers during their medical application, while their ability to interact not only with small molecules but also with lipids and proteins is largely neglected. By forming inclusion complexes with cholesterol, cyclodextrins deplete cholesterol from cellular membranes and thereby influence protein function indirectly through alterations in biophysical properties and lateral heterogeneity of bilayers. In this review, we summarize the general chemical principles of direct cyclodextrin-protein interactions and highlight, through relevant examples, how these interactions can modify protein functions in vivo, which, despite their huge potential, have been completely unexploited in therapy so far. Finally, we give a brief overview of disorders such as Niemann-Pick type C disease, atherosclerosis, Alzheimer's and Parkinson's disease, in which cyclodextrins already have or could have the potential to be active therapeutic agents due to their cholesterol-complexing or direct protein-targeting properties.
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Affiliation(s)
- Tamas Kovacs
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Peter Nagy
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Lajos Szente
- CycloLab Cyclodextrin R & D Laboratory Ltd., H-1097 Budapest, Hungary
| | - Zoltan Varga
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Florina Zakany
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
- Correspondence:
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7
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Li CD, Junaid M, Shan X, Wang Y, Wang X, Khan A, Wei DQ. Effect of Cholesterol on C99 Dimerization: Revealed by Molecular Dynamics Simulations. Front Mol Biosci 2022; 9:872385. [PMID: 35928227 PMCID: PMC9343951 DOI: 10.3389/fmolb.2022.872385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/18/2022] [Indexed: 11/28/2022] Open
Abstract
C99 is the immediate precursor for amyloid beta (Aβ) and therefore is a central intermediate in the pathway that is believed to result in Alzheimer’s disease (AD). It has been suggested that cholesterol is associated with C99, but the dynamic details of how cholesterol affects C99 assembly and the Aβ formation remain unclear. To investigate this question, we employed coarse-grained and all-atom molecular dynamics simulations to study the effect of cholesterol and membrane composition on C99 dimerization. We found that although the existence of cholesterol delays C99 dimerization, there is no direct competition between C99 dimerization and cholesterol association. In contrast, the existence of cholesterol makes the C99 dimer more stable, which presents a cholesterol binding C99 dimer model. Cholesterol and membrane composition change the dimerization rate and conformation distribution of C99, which will subsequently influence the production of Aβ. Our results provide insights into the potential influence of the physiological environment on the C99 dimerization, which will help us understand Aβ formation and AD’s etiology.
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Affiliation(s)
- Cheng-Dong Li
- State Key Laboratory of Microbial Metabolism, Joint Laboratory of International Cooperation in Metabolic and Developmental Sciences, Ministry of Education, Department of Bioinformatics and Biological Statistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Muhammad Junaid
- State Key Laboratory of Microbial Metabolism, Joint Laboratory of International Cooperation in Metabolic and Developmental Sciences, Ministry of Education, Department of Bioinformatics and Biological Statistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaoqi Shan
- State Key Laboratory of Microbial Metabolism, Joint Laboratory of International Cooperation in Metabolic and Developmental Sciences, Ministry of Education, Department of Bioinformatics and Biological Statistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Yanjing Wang
- State Key Laboratory of Microbial Metabolism, Joint Laboratory of International Cooperation in Metabolic and Developmental Sciences, Ministry of Education, Department of Bioinformatics and Biological Statistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Xiangeng Wang
- State Key Laboratory of Microbial Metabolism, Joint Laboratory of International Cooperation in Metabolic and Developmental Sciences, Ministry of Education, Department of Bioinformatics and Biological Statistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Abbas Khan
- State Key Laboratory of Microbial Metabolism, Joint Laboratory of International Cooperation in Metabolic and Developmental Sciences, Ministry of Education, Department of Bioinformatics and Biological Statistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Dong-Qing Wei
- State Key Laboratory of Microbial Metabolism, Joint Laboratory of International Cooperation in Metabolic and Developmental Sciences, Ministry of Education, Department of Bioinformatics and Biological Statistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
- Peng Cheng Laboratory, Shenzhen, China
- *Correspondence: Dong-Qing Wei,
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8
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Suga K, Yamamoto-Hijikata S, Terao Y, Akagawa K, Ushimaru M. Golgi stress induces upregulation of the ER-Golgi SNARE Syntaxin-5, altered βAPP processing, and Caspase-3-dependent apoptosis in NG108-15 cells. Mol Cell Neurosci 2022; 121:103754. [PMID: 35842170 DOI: 10.1016/j.mcn.2022.103754] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 05/29/2022] [Accepted: 07/07/2022] [Indexed: 01/06/2023] Open
Abstract
The involvement of secretory pathways and Golgi dysfunction in neuronal cells during Alzheimer's disease progression is poorly understood. Our previous overexpression and knockdown studies revealed that the intracellular protein level of Syntaxin-5, an endoplasmic reticulum-Golgi soluble N-ethylmaleimide-sensitive factor-attachment protein receptor (SNARE), modulates beta-amyloid precursor protein processing in neuronal cells. We recently showed that changes in endogenous Syntaxin-5 protein expression occur under stress induction. Syntaxin-5 was upregulated by endoplasmic reticulum stress but was degraded by Caspase-3 during apoptosis in neuronal cells. In addition, we showed that sustained endoplasmic reticulum stress promotes Caspase-3-dependent apoptosis during the later phase of the endoplasmic reticulum stress response in NG108-15 cells. In this study, to elucidate the consequences of secretory pathway dysfunction in beta-amyloid precursor protein processing that lead to neuronal cell death, we examined the effect of various stresses on endoplasmic reticulum-Golgi SNARE expression and beta-amyloid precursor protein processing. By using compounds to disrupt Golgi function, we show that Golgi stress promotes upregulation of the endoplasmic reticulum-Golgi SNARE Syntaxin-5, and prolonged stress causes Caspase-3-dependent apoptosis. Golgi stress induced intracellular beta-amyloid precursor protein accumulation and a concomitant decrease in total amyloid-beta production. We also examined the protective effect of the chemical chaperone 4-phenylbutylate on changes in amyloid-beta production and the activation of Caspase-3 induced by endoplasmic reticulum and Golgi stress. The compound alleviated the increase in the amyloid-beta 1-42/amyloid-beta 1-40 ratio induced by endoplasmic reticulum and Golgi stress. Furthermore, 4-phenylbutylate could rescue Caspase-3-dependent apoptosis induced by prolonged organelle stress. These results suggest that organelle stress originating from the endoplasmic reticulum and Golgi has a substantial impact on the amyloidogenic processing of beta-amyloid precursor protein and Caspase-3-dependent apoptosis, leading to neuronal cell death.
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Affiliation(s)
- Kei Suga
- Department of Chemistry, Kyorin University, Faculty of Medicine, Mitaka, Tokyo 181-8611, Japan; Department of Medical Physiology, Kyorin University, Faculty of Medicine, Mitaka, Tokyo 181-8611, Japan.
| | | | - Yasuo Terao
- Department of Medical Physiology, Kyorin University, Faculty of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Kimio Akagawa
- Department of Medical Physiology, Kyorin University, Faculty of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Makoto Ushimaru
- Department of Chemistry, Kyorin University, Faculty of Medicine, Mitaka, Tokyo 181-8611, Japan
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9
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Pedrini S, Hone E, Gupta VB, James I, Teimouri E, Bush AI, Rowe CC, Villemagne VL, Ames D, Masters CL, Rainey-Smith S, Verdile G, Sohrabi HR, Raida MR, Wenk MR, Taddei K, Chatterjee P, Martins I, Laws SM, Martins RN. Plasma High Density Lipoprotein Small Subclass is Reduced in Alzheimer's Disease Patients and Correlates with Cognitive Performance. J Alzheimers Dis 2021; 77:733-744. [PMID: 32741823 PMCID: PMC7592676 DOI: 10.3233/jad-200291] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Background: The link between cholesterol and Alzheimer’s disease (AD) has received much attention, as evidence suggests high levels of cholesterol might be an AD risk factor. The carriage of cholesterol and lipids through the body is mediated via lipoproteins, some of which, particularly apolipoprotein E (ApoE), are intimately linked with AD. In humans, high density lipoprotein (HDL) is regarded as a “good” lipid complex due to its ability to enable clearance of excess cholesterol via ‘cholesterol reverse transport’, although its activities in the pathogenesis of AD are poorly understood. There are several subclasses of HDL; these range from the newly formed small HDL, to much larger HDL. Objective: We examined the major subclasses of HDL in healthy controls, mild cognitively impaired, and AD patients who were not taking statins to determine whether there were HDL profile differences between the groups, and whether HDL subclass levels correlated with plasma amyloid-β (Aβ) levels or brain Aβ deposition. Methods: Samples from AIBL cohort were used in this study. HDL subclass levels were assessed by Lipoprint while Aβ1–42 levels were assessed by ELISA. Brain Aβ deposition was assessed by PET scan. Statistical analysis was performed using parametric and non-parametric tests. Results: We found that small HDL subclass is reduced in AD patients and it correlates with cognitive performance while plasma Aβ concentrations do not correlate with lipid profile or HDL subfraction levels. Conclusion: Our data indicate that AD patients exhibit altered plasma HDL profile and that HDL subclasses correlate with cognitive performances.
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Affiliation(s)
- Steve Pedrini
- School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia.,CRC for Mental Health, Carlton South, Victoria, Australia
| | - Eugene Hone
- School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia.,CRC for Mental Health, Carlton South, Victoria, Australia
| | - Veer B Gupta
- School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia.,CRC for Mental Health, Carlton South, Victoria, Australia
| | - Ian James
- Institute for Immunology and Infectious Diseases, Murdoch University, Murdoch, WA, Australia
| | - Elham Teimouri
- School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Ashley I Bush
- CRC for Mental Health, Carlton South, Victoria, Australia.,The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Christopher C Rowe
- Department of Nuclear Medicine and Centre for PET, Austin Health, Heidelberg, Victoria, Australia
| | - Victor L Villemagne
- Department of Nuclear Medicine and Centre for PET, Austin Health, Heidelberg, Victoria, Australia
| | - David Ames
- National Ageing Research Institute, Parkville, Victoria, Australia.,University of Melbourne Academic unit for Psychiatry of Old Age, St George's Hospital, Kew, Victoria, Australia
| | - Colin L Masters
- The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia
| | | | - Giuseppe Verdile
- School of Biomedical Sciences, Curtin University, Bentley, WA, Australia
| | - Hamid R Sohrabi
- Centre for Healthy Ageing, School of Psychology and Exercise Science, Murdoch University, Murdoch, WA, Australia
| | - Manfred R Raida
- Life Science Institute, Singapore Lipidomics Incubator, National University of Singapore, Singapore
| | - Markus R Wenk
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Kevin Taddei
- School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia.,CRC for Mental Health, Carlton South, Victoria, Australia
| | - Pratishtha Chatterjee
- Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia
| | - Ian Martins
- School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia.,CRC for Mental Health, Carlton South, Victoria, Australia
| | - Simon M Laws
- School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia.,CRC for Mental Health, Carlton South, Victoria, Australia
| | - Ralph N Martins
- School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia.,CRC for Mental Health, Carlton South, Victoria, Australia.,Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia.,School of Psychiatry and Clinical Neurosciences, University of Western Australia, Crawley, WA, Australia
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10
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Capone R, Tiwari A, Hadziselimovic A, Peskova Y, Hutchison JM, Sanders CR, Kenworthy AK. The C99 domain of the amyloid precursor protein resides in the disordered membrane phase. J Biol Chem 2021; 296:100652. [PMID: 33839158 PMCID: PMC8113881 DOI: 10.1016/j.jbc.2021.100652] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 04/02/2021] [Accepted: 04/07/2021] [Indexed: 12/11/2022] Open
Abstract
Processing of the amyloid precursor protein (APP) via the amyloidogenic pathway is associated with the etiology of Alzheimer's disease. The cleavage of APP by β-secretase to generate the transmembrane 99-residue C-terminal fragment (C99) and subsequent processing of C99 by γ-secretase to yield amyloid-β (Aβ) peptides are essential steps in this pathway. Biochemical evidence suggests that amyloidogenic processing of C99 occurs in cholesterol- and sphingolipid-enriched liquid-ordered phase membrane rafts. However, direct evidence that C99 preferentially associates with these rafts has remained elusive. Here, we tested this by quantifying the affinity of C99-GFP for raft domains in cell-derived giant plasma membrane vesicles (GPMVs). We found that C99 was essentially excluded from ordered domains in vesicles from HeLa cells, undifferentiated SH-SY5Y cells, or SH-SY5Y-derived neurons; instead, ∼90% of C99 partitioned into disordered domains. The strong association of C99 with disordered domains occurred independently of its cholesterol-binding activity or homodimerization, or of the presence of the familial Alzheimer disease Arctic mutation (APP E693G). Finally, through biochemical studies we confirmed previous results, which showed that C99 is processed in the plasma membrane by α-secretase, in addition to the well-known γ-secretase. These findings suggest that C99 itself lacks an intrinsic affinity for raft domains, implying that either i) amyloidogenic processing of the protein occurs in disordered regions of the membrane, ii) processing involves a marginal subpopulation of C99 found in rafts, or iii) as-yet-unidentified protein-protein interactions with C99 in living cells drive this protein into membrane rafts to promote its cleavage therein.
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Affiliation(s)
- Ricardo Capone
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Ajit Tiwari
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | | | - Yelena Peskova
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA
| | - James M Hutchison
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Charles R Sanders
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA; Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Anne K Kenworthy
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA.
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11
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Preta G. New Insights Into Targeting Membrane Lipids for Cancer Therapy. Front Cell Dev Biol 2020; 8:571237. [PMID: 32984352 PMCID: PMC7492565 DOI: 10.3389/fcell.2020.571237] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 08/13/2020] [Indexed: 12/15/2022] Open
Abstract
Modulation of membrane lipid composition and organization is currently developing as an effective therapeutic strategy against a wide range of diseases, including cancer. This field, known as membrane-lipid therapy, has risen from new discoveries on the complex organization of lipids and between lipids and proteins in the plasma membranes. Membrane microdomains present in the membrane of all eukaryotic cells, known as lipid rafts, have been recognized as an important concentrating platform for protein receptors involved in the regulation of intracellular signaling, apoptosis, redox balance and immune response. The difference in lipid composition between the cellular membranes of healthy cells and tumor cells allows for the development of novel therapies based on targeting membrane lipids in cancer cells to increase sensitivity to chemotherapeutic agents and consequently defeat multidrug resistance. In the current manuscript strategies based on influencing cholesterol/sphingolipids content will be presented together with innovative ones, more focused in changing biophysical properties of the membrane bilayer without affecting the composition of its constituents.
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Affiliation(s)
- Giulio Preta
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
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12
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The effects of melatonin, serotonin, tryptophan and NAS on the biophysical properties of DPPC monolayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183363. [DOI: 10.1016/j.bbamem.2020.183363] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 05/15/2020] [Accepted: 05/18/2020] [Indexed: 12/24/2022]
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13
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Agrawal RR, Montesinos J, Larrea D, Area-Gomez E, Pera M. The silence of the fats: A MAM's story about Alzheimer. Neurobiol Dis 2020; 145:105062. [PMID: 32866617 DOI: 10.1016/j.nbd.2020.105062] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 08/07/2020] [Accepted: 08/22/2020] [Indexed: 02/07/2023] Open
Abstract
The discovery of contact sites was a breakthrough in cell biology. We have learned that an organelle cannot function in isolation, and that many cellular functions depend on communication between two or more organelles. One such contact site results from the close apposition of the endoplasmic reticulum (ER) and mitochondria, known as mitochondria-associated ER membranes (MAMs). These intracellular lipid rafts serve as hubs for the regulation of cellular lipid and calcium homeostasis, and a growing body of evidence indicates that MAM domains modulate cellular function in both health and disease. Indeed, MAM dysfunction has been described as a key event in Alzheimer disease (AD) pathogenesis. Our most recent work shows that, by means of its affinity for cholesterol, APP-C99 accumulates in MAM domains of the ER and induces the uptake of extracellular cholesterol as well as its trafficking from the plasma membrane to the ER. As a result, MAM functionality becomes chronically upregulated while undergoing continual turnover. The goal of this review is to discuss the consequences of C99 elevation in AD, specifically the upregulation of cholesterol trafficking and MAM activity, which abrogate cellular lipid homeostasis and disrupt the lipid composition of cellular membranes. Overall, we present a novel framework for AD pathogenesis that can be linked to the many complex alterations that occur during disease progression, and that may open a door to new therapeutic strategies.
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Affiliation(s)
- Rishi R Agrawal
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Jorge Montesinos
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Delfina Larrea
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Estela Area-Gomez
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, 10032, USA; Department of Neurology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Marta Pera
- Departament of Basic Sciences, Facultat de Medicina I Ciències de la Salut, Universitat Internacional de Catalunya (UIC), Sant Cugat del Vallés, 08195, Spain.
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14
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Kulas JA, Weigel TK, Ferris HA. Insulin resistance and impaired lipid metabolism as a potential link between diabetes and Alzheimer's disease. Drug Dev Res 2020; 81:194-205. [PMID: 32022298 DOI: 10.1002/ddr.21643] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 12/20/2019] [Accepted: 01/23/2020] [Indexed: 12/13/2022]
Abstract
Diabetes disrupts organs throughout the body including the brain. Evidence suggests diabetes is a risk factor for Alzheimer's disease (AD) and neurodegeneration. In this review, we focus on understanding how diabetes contributes to the progression of neurodegeneration by influencing several aspects of the disease process. We emphasize the potential roles of brain insulin resistance, as well as cholesterol and lipid disruption, as factors which worsen AD.
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Affiliation(s)
- Joshua A Kulas
- Division of Endocrinology and Metabolism, University of Virginia, Charlottesville, Virginia
| | - Thaddeus K Weigel
- Department of Neuroscience, University of Virginia, Charlottesville, Virginia
| | - Heather A Ferris
- Division of Endocrinology and Metabolism, University of Virginia, Charlottesville, Virginia.,Department of Neuroscience, University of Virginia, Charlottesville, Virginia
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15
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Pan Y, Xu J, Chen C, Chen F, Jin P, Zhu K, Hu CW, You M, Chen M, Hu F. Royal Jelly Reduces Cholesterol Levels, Ameliorates Aβ Pathology and Enhances Neuronal Metabolic Activities in a Rabbit Model of Alzheimer's Disease. Front Aging Neurosci 2018; 10:50. [PMID: 29556189 PMCID: PMC5845009 DOI: 10.3389/fnagi.2018.00050] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 02/15/2018] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia characterized by aggregation of amyloid β (Aβ) and neuronal loss. One of the risk factors for AD is high cholesterol levels, which are known to promote Aβ deposition. Previous studies have shown that royal jelly (RJ), a product of worker bees, has potential neuroprotective effects and can attenuate Aβ toxicity. However, little is known about how RJ regulates Aβ formation and its effects on cholesterol levels and neuronal metabolic activities. Here, we investigated whether RJ can reduce cholesterol levels, regulate Aβ levels and enhance neuronal metabolic activities in an AD rabbit model induced by 2% cholesterol diet plus copper drinking water. Our results suggest that RJ significantly reduced the levels of plasma total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C), and decreased the level of Aβ in rabbit brains. RJ was also shown to markedly ameliorate amyloid deposition in AD rabbits from Aβ immunohistochemistry and thioflavin-T staining. Furthermore, our study suggests that RJ can reduce the expression levels of β-site APP cleaving enzyme-1 (BACE1) and receptor for advanced glycation end products (RAGE), and increase the expression levels of low density lipoprotein receptor-related protein 1 (LRP-1) and insulin degrading enzyme (IDE). In addition, we found that RJ remarkably increased the number of neurons, enhanced antioxidant capacities, inhibited activated-capase-3 protein expression, and enhanced neuronal metabolic activities by increasing N-acetyl aspartate (NAA) and glutamate and by reducing choline and myo-inositol in AD rabbits. Taken together, our data demonstrated that RJ could reduce cholesterol levels, regulate Aβ levels and enhance neuronal metabolic activities in AD rabbits, providing preclinical evidence that RJ treatment has the potential to protect neurons and prevent AD.
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Affiliation(s)
- Yongming Pan
- College of Animal Sciences, Zhejiang University, Hangzhou, China.,Comparative Medical Research Center, Experimental Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, China
| | - Jianqin Xu
- Comparative Medical Research Center, Experimental Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, China
| | - Cheng Chen
- Comparative Medical Research Center, Experimental Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, China
| | - Fangming Chen
- Comparative Medical Research Center, Experimental Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, China
| | - Ping Jin
- The First Affiliated Hospital, Zhejiang Chinese Medical University, Hangzhou, China
| | - Keyan Zhu
- Comparative Medical Research Center, Experimental Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, China
| | - Chenyue W Hu
- Department of Bioengineering, Rice University, Houston, TX, United States
| | - Mengmeng You
- College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Minli Chen
- Comparative Medical Research Center, Experimental Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, China
| | - Fuliang Hu
- College of Animal Sciences, Zhejiang University, Hangzhou, China
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16
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El Gaamouch F, Jing P, Xia J, Cai D. Alzheimer's Disease Risk Genes and Lipid Regulators. J Alzheimers Dis 2017; 53:15-29. [PMID: 27128373 DOI: 10.3233/jad-160169] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Brain lipid homeostasis plays an important role in Alzheimer's disease (AD) and other neurodegenerative disorders. Aggregation of amyloid-β peptide is one of the major events in AD. The complex interplay between lipids and amyloid-β accumulation has been intensively investigated. The proportions of lipid components including phospholipids, sphingolipids, and cholesterol are roughly similar across different brain regions under physiological conditions. However, disruption of brain lipid homeostasis has been described in AD and implicated in disease pathogenesis. Moreover, studies suggest that analysis of lipid composition in plasma and cerebrospinal fluid could improve our understanding of the disease development and progression, which could potentially serve as disease biomarkers and prognostic indicators for AD therapies. Here, we summarize the functional roles of AD risk genes and lipid regulators that modulate brain lipid homeostasis including different lipid species, lipid complexes, and lipid transporters, particularly their effects on amyloid processing, clearance, and aggregation, as well as neuro-toxicities that contribute to AD pathogenesis.
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Affiliation(s)
- Farida El Gaamouch
- James J Peters VA Medical Center, Research & Development, Bronx, NY, USA.,Department of Neurology, Alzheimer Disease Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ping Jing
- The Central Hospital of Wuhan, China
| | | | - Dongming Cai
- James J Peters VA Medical Center, Research & Development, Bronx, NY, USA.,Department of Neurology, Alzheimer Disease Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,The Central Hospital of Wuhan, China
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17
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Li CD, Xu Q, Gu RX, Qu J, Wei DQ. The dynamic binding of cholesterol to the multiple sites of C99: as revealed by coarse-grained and all-atom simulations. Phys Chem Chem Phys 2017; 19:3845-3856. [DOI: 10.1039/c6cp07873g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The multi-site cholesterol binding model of C99.
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Affiliation(s)
- Cheng-Dong Li
- State Key Laboratory of Microbial Metabolism and College of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai 200240
- China
- Beijing Key Laboratory of Bioprocess
| | - Qin Xu
- State Key Laboratory of Microbial Metabolism and College of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai 200240
- China
| | - Ruo-Xu Gu
- Centre for Molecular Simulation and Department of Biological Sciences
- University of Calgary
- Calgary
- Canada
| | - Jing Qu
- Beijing Key Laboratory of Bioprocess
- College of Life Science and Technology
- Beijing University of Chemical Technology
- Beijing
- P. R. China
| | - Dong-Qing Wei
- State Key Laboratory of Microbial Metabolism and College of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai 200240
- China
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18
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Shuang R, Rui X, Wenfang L. Phytosterols and Dementia. PLANT FOODS FOR HUMAN NUTRITION (DORDRECHT, NETHERLANDS) 2016; 71:347-354. [PMID: 27663717 DOI: 10.1007/s11130-016-0574-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
As the aging of the world's population is becoming increasingly serious, dementia-related diseases have become a hot topic in public health research. In recent years, human epidemiological studies have focused on lipid metabolism disorders and dementia. The efficacy of phytosterol intake as a cholesterol-lowering agent has been demonstrated. Phytosterols directly serve as ligands of the nuclear receptors, peroxisome proliferator-activated receptors (PPARs), activating Sirtuin 1 (SIRT-1), which are involved in the regulation of lipid metabolism and the pathogenesis of dementia. Moreover, phytosterols mediate cell and membrane cholesterol efflux or beta amyloid (Aβ) metabolism, which have preventative and therapeutic effects on dementia. Additionally, incorporation of plant sterols in lipid rafts can effectively reduce dietary fat and alter the dietary composition of fiber, fat and cholesterol to regulate appetite and calories. Overall, the objectives of this review are to explore whether phytosterols are a potentially effective target for the prevention of dementia and to discuss a possible molecular mechanism by which phytosterols play a role in the pathogenesis of dementia via the PPARs-SIRT-1 pathway.
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Affiliation(s)
- Rong Shuang
- Department of Public Health School, Wuhan University of Science & Technology, Wuhan, 430065, China.
| | - Xu Rui
- Department of Public Health School, Wuhan University of Science & Technology, Wuhan, 430065, China
| | - Li Wenfang
- Department of Public Health School, Wuhan University of Science & Technology, Wuhan, 430065, China.
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19
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Brambillaa A, Lonati E, Milani C, Rizzo AM, Farina F, Botto L, Masserini M, Palestini P, Bulbarelli A. Ischemic conditions and ß-secretase activation: The impact of membrane cholesterol enrichment as triggering factor in rat brain endothelial cells. Int J Biochem Cell Biol 2016; 69:95-104. [PMID: 27022655 DOI: 10.1016/j.biocel.2015.10.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Among harmful conditions damaging the blood–brain barrier, cerebral stroke and reperfusion injuries were proposed as contributing factors to Alzheimer's disease etiology. Indeed it was reported that ischemic conditions promote β-amyloid peptide production in brain endothelial cells, although implicated mechanisms are yet not fully understood.Oxidative injury related to ischemia affects membrane-lipids profile by altering their biochemical properties and structural dynamics, which are also believed to play significant role in the amyloid precursor protein processing, suggesting a link between alterations in lipid membrane composition and β-amyloid peptide production enhancement.Using brain microvascular endothelial cells, here we demonstrate how oxygen and glucose deprivation followed by normal conditions restoration, mimicking ischemic environment, increases cell cholesterol amount (+20%), reduces membrane fluidity and results in strong activation (+40%) of β-secretase 1 enzymatic activity. Moreover, we observed an increase of amyloid precursor protein and β-secretase 1 protein levels with altered localization in non-discrete (Triton X-100 soluble) membrane domains, leading to an enhanced production of amyloid precursor protein β-carboxyl-terminal fragment. Therefore, lipid alterations induced by oxygen and glucose deprivation enhance β-secretase 1 activity, favor its proximity to amyloid precursor protein and may concur to increased amyloidogenic cleavage. The latter, represents a detrimental event that may contribute to β-amyloid homeostasis impairment in the brain and to Alzheimer's disease-related BBB dysfunctions.
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20
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Piedrahita D, Castro-Alvarez JF, Boudreau RL, Villegas-Lanau A, Kosik KS, Gallego-Gomez JC, Cardona-Gómez GP. β-Secretase 1's Targeting Reduces Hyperphosphorilated Tau, Implying Autophagy Actors in 3xTg-AD Mice. Front Cell Neurosci 2016; 9:498. [PMID: 26778963 PMCID: PMC4705306 DOI: 10.3389/fncel.2015.00498] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 12/11/2015] [Indexed: 01/08/2023] Open
Abstract
β-site APP cleaving enzyme 1 (BACE1) initiates APP cleavage, which has been reported to be an inducer of tau pathology by altering proteasome functions in Alzheimer’s disease (AD). However, the exact relationship between BACE1 and PHF (Paired Helical Filaments) formation is not clear. In this study, we confirm that BACE1 and Hsc70 are upregulated in the brains of AD patients, and we demonstrate that both proteins show enhanced expression in lipid rafts from AD-affected triple transgenic mouse brains. BACE1 targeting increased Hsc70 levels in the membrane and cytoplasm fractions and downregulated Hsp90 and CHIP in the nucleus in the hippocampi of 3xTg-AD mice. However, these observations occurred in a proteasome-independent manner in vitro. The BACE1miR-induced reduction of soluble hyperphosphorylated tau was associated with a decrease in MAPK activity. However, the BACE1 RNAi-mediated reduction of hyperphosphorylated tau was only blocked by 3-MA (3-methyladenine) in vitro, and it resulted in the increase of Hsc70 and LAMP2 in lipid rafts from hippocampi of 3xTg-AD mice, and upregulation of survival and homeostasis signaling. In summary, our findings suggest that BACE1 silencing neuroprotects reducing soluble hyperphosphorylated tau, modulating certain autophagy-related proteins in aged 3xTg-AD mice.
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Affiliation(s)
- Diego Piedrahita
- Cellular and Molecular Neurobiology Area, Viral Vector Core and Gene Therapy, University of Antioquia Medellin, Antioquia, Colombia
| | - John Fredy Castro-Alvarez
- Cellular and Molecular Neurobiology Area, Viral Vector Core and Gene Therapy, University of Antioquia Medellin, Antioquia, Colombia
| | | | - Andres Villegas-Lanau
- Neurobank, Neuroscience Group of Antioquia, Faculty of Medicine, SIU, University of Antioquia Medellín, Colombia
| | - Kenneth S Kosik
- Department of Molecular Cellular Developmental Biology, Neuroscience Research Institute, University of California Santa Barbara Santa Barbara, CA, USA
| | - Juan Carlos Gallego-Gomez
- Cellular and Molecular Neurobiology Area, Viral Vector Core and Gene Therapy, University of Antioquia Medellin, Antioquia, Colombia
| | - Gloria Patricia Cardona-Gómez
- Cellular and Molecular Neurobiology Area, Viral Vector Core and Gene Therapy, University of Antioquia Medellin, Antioquia, Colombia
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21
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Chen YL, Wang LM, Chen Y, Gao JY, Marshall C, Cai ZY, Hu G, Xiao M. Changes in astrocyte functional markers and β-amyloid metabolism-related proteins in the early stages of hypercholesterolemia. Neuroscience 2015; 316:178-91. [PMID: 26724580 DOI: 10.1016/j.neuroscience.2015.12.039] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 12/11/2015] [Accepted: 12/19/2015] [Indexed: 12/21/2022]
Abstract
Cholesterol is an essential substance for maintaining normal structure and function of the brain. But unfortunately, a long-term high-cholesterol diet can lead to a variety of pathological changes of the brain such as β-amyloid (Aβ) accumulation, Tau hyperphosphorylation, reactive gliosis, neuroinflammation, neuronal death and synaptic degeneration. These pathological changes have complex internal relations with one other, causing memory impairment and participating in the pathogenesis of Alzheimer's disease (AD). However, early hypercholesterolemia-induced events that lead to brain deterioration are not clear. To address this, 6-month-old female mice were fed a 3% cholesterol diet for 8weeks, followed by behavioral, biochemical and neuropathological analyses. The high-cholesterol-fed mice did not show neuronal and synaptic impairment or cognitive deficits compared with mice given a normal diet, but astrocytes were mildly activated with increased expression of functional markers including apolipoprotein E and aquaporin 4 in the hippocampus. Hippocampal interleukin-1β expression slightly increased, but interleukin-6 (IL-6) and tumor necrosis factor-α did not change significantly compared with those in the control group. Levels of Aβ, and its precursor protein, were unaffected, but levels of presenilin 1 and insulin-degrading enzyme (IDE), that initiate Aβ generation and degradation, respectively, increased in the hippocampus of the model mice. In addition, Tau phosphorylation levels were not different between the control and model groups. These results suggest that changes in astrocyte functional markers and Aβ metabolism proteins, which contribute to maintaining brain cholesterol and Aβ homeostasis, are early events in the process of hypercholesterolemia-related neuropathological changes.
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Affiliation(s)
- Y L Chen
- Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, 140 Hanzhong Road, Nanjing, Jiangsu 210029, China
| | - L M Wang
- Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, 140 Hanzhong Road, Nanjing, Jiangsu 210029, China
| | - Y Chen
- Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, 140 Hanzhong Road, Nanjing, Jiangsu 210029, China
| | - J Y Gao
- Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, 140 Hanzhong Road, Nanjing, Jiangsu 210029, China
| | - C Marshall
- Department of Rehabilitation Sciences, University of Kentucky Center of Excellence in Rural Health, Hazard, KY, USA
| | - Z Y Cai
- Department of Neurology, Shiyan Renmin Hospital, Hubei University of Medicine, No 39 Chaoyang Middle Road, Shiyan, Hubei Province 442000, People's Republic of China
| | - G Hu
- Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, 140 Hanzhong Road, Nanjing, Jiangsu 210029, China
| | - M Xiao
- Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, 140 Hanzhong Road, Nanjing, Jiangsu 210029, China.
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22
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The Deleterious Effects of Oxidative and Nitrosative Stress on Palmitoylation, Membrane Lipid Rafts and Lipid-Based Cellular Signalling: New Drug Targets in Neuroimmune Disorders. Mol Neurobiol 2015; 53:4638-58. [PMID: 26310971 DOI: 10.1007/s12035-015-9392-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Accepted: 08/11/2015] [Indexed: 12/18/2022]
Abstract
Oxidative and nitrosative stress (O&NS) is causatively implicated in the pathogenesis of Alzheimer's and Parkinson's disease, multiple sclerosis, chronic fatigue syndrome, schizophrenia and depression. Many of the consequences stemming from O&NS, including damage to proteins, lipids and DNA, are well known, whereas the effects of O&NS on lipoprotein-based cellular signalling involving palmitoylation and plasma membrane lipid rafts are less well documented. The aim of this narrative review is to discuss the mechanisms involved in lipid-based signalling, including palmitoylation, membrane/lipid raft (MLR) and n-3 polyunsaturated fatty acid (PUFA) functions, the effects of O&NS processes on these processes and their role in the abovementioned diseases. S-palmitoylation is a post-translational modification, which regulates protein trafficking and association with the plasma membrane, protein subcellular location and functions. Palmitoylation and MRLs play a key role in neuronal functions, including glutamatergic neurotransmission, and immune-inflammatory responses. Palmitoylation, MLRs and n-3 PUFAs are vulnerable to the corruptive effects of O&NS. Chronic O&NS inhibits palmitoylation and causes profound changes in lipid membrane composition, e.g. n-3 PUFA depletion, increased membrane permeability and reduced fluidity, which together lead to disorders in intracellular signal transduction, receptor dysfunction and increased neurotoxicity. Disruption of lipid-based signalling is a source of the neuroimmune disorders involved in the pathophysiology of the abovementioned diseases. n-3 PUFA supplementation is a rational therapeutic approach targeting disruptions in lipid-based signalling.
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23
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Bauereiss A, Welzel O, Jung J, Grosse-Holz S, Lelental N, Lewczuk P, Wenzel EM, Kornhuber J, Groemer TW. Surface Trafficking of APP and BACE in Live Cells. Traffic 2015; 16:655-75. [PMID: 25712587 PMCID: PMC6680167 DOI: 10.1111/tra.12270] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 02/06/2015] [Accepted: 02/09/2015] [Indexed: 12/22/2022]
Abstract
Amyloid‐β (Aβ)‐peptide, the major constituent of the plaques that develop during Alzheimer's disease, is generated via the cleavage of Aβ precursor protein (APP) by β‐site APP‐cleaving enzyme (BACE). Using live‐cell imaging of APP and BACE labeled with pH‐sensitive proteins, we could detect the release events of APP and BACE and their distinct kinetics. We provide kinetic evidence for the cleavage of APP by α‐secretase on the cellular surface after exocytosis. Furthermore, simultaneous dual‐color evanescent field illumination revealed that the two proteins are trafficked to the surface in separate compartments. Perturbing the membrane lipid composition resulted in a reduced frequency of exocytosis and affected BACE more strongly than APP. We propose that surface fusion frequency is a key factor regulating the aggregation of APP and BACE in the same membrane compartment and that this process can be modulated via pharmacological intervention.
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Affiliation(s)
- Anna Bauereiss
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054, Erlangen, Germany
| | - Oliver Welzel
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054, Erlangen, Germany
| | - Jasmin Jung
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054, Erlangen, Germany
| | - Simon Grosse-Holz
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054, Erlangen, Germany
| | - Natalia Lelental
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054, Erlangen, Germany
| | - Piotr Lewczuk
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054, Erlangen, Germany
| | - Eva M Wenzel
- Institute for Cancer Research, Department of Biochemistry, The Norwegian Radium Hospital, Montebello, N-0310, Oslo, Norway
| | - Johannes Kornhuber
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054, Erlangen, Germany
| | - Teja W Groemer
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054, Erlangen, Germany
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24
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Alterations in Cholesterol and Ganglioside GM1 Content of Lipid Rafts in Platelets From Patients With Alzheimer Disease. Alzheimer Dis Assoc Disord 2015; 29:63-9. [DOI: 10.1097/wad.0000000000000041] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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25
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Cholesterol balance in prion diseases and Alzheimer's disease. Viruses 2014; 6:4505-35. [PMID: 25419621 PMCID: PMC4246236 DOI: 10.3390/v6114505] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/08/2014] [Accepted: 11/14/2014] [Indexed: 12/16/2022] Open
Abstract
Prion diseases are transmissible and fatal neurodegenerative disorders of humans and animals. They are characterized by the accumulation of PrPSc, an aberrantly folded isoform of the cellular prion protein PrPC, in the brains of affected individuals. PrPC is a cell surface glycoprotein attached to the outer leaflet of the plasma membrane by a glycosyl-phosphatidyl-inositol (GPI) anchor. Specifically, it is associated with lipid rafts, membrane microdomains enriched in cholesterol and sphinoglipids. It has been established that inhibition of endogenous cholesterol synthesis disturbs lipid raft association of PrPC and prevents PrPSc accumulation in neuronal cells. Additionally, prion conversion is reduced upon interference with cellular cholesterol uptake, endosomal export, or complexation at the plasma membrane. Altogether, these results demonstrate on the one hand the importance of cholesterol for prion propagation. On the other hand, growing evidence suggests that prion infection modulates neuronal cholesterol metabolism. Similar results were reported in Alzheimer’s disease (AD): whereas amyloid β peptide formation is influenced by cellular cholesterol, levels of cholesterol in the brains of affected individuals increase during the clinical course of the disease. In this review, we summarize commonalities of alterations in cholesterol homeostasis and discuss consequences for neuronal function and therapy of prion diseases and AD.
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Specific antibody binding to the APP672-699 region shifts APP processing from α- to β-cleavage. Cell Death Dis 2014; 5:e1374. [PMID: 25118934 PMCID: PMC4454311 DOI: 10.1038/cddis.2014.336] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/02/2014] [Accepted: 07/09/2014] [Indexed: 12/13/2022]
Abstract
Alzheimer's disease (AD), a progressive neurodegenerative disorder that is the most common cause of dementia in the elderly, is characterized by the accumulation of amyloid-β (Aβ) plaques and neurofibrillary tangles, as well as a progressive loss of synapses and neurons in the brain. The major pertinacious component of amyloid plaques is Aβ, a variably sized peptide derived from the integral membrane protein amyloid precursor protein (APP). The Aβ region of APP locates partly within its ecto- and trans-membrane domains. APP is cleaved by three proteases, designated as α-, β-, and γ-secretases. Processing by β- and γ-secretase cleaves the N- and C-terminal ends of the Aβ region, respectively, releasing Aβ, whereas α-secretase cleaves within the Aβ sequence, releasing soluble APPα (sAPPα). The γ-secretase cleaves at several adjacent sites to yield Aβ species containing 39-43 amino acid residues. Both α- and β-cleavage sites of human wild-type APP are located in APP672-699 region (ectodomain of β-C-terminal fragment, ED-β-CTF or ED-C99). Therefore, the amino acid residues within or near this region are definitely pivotal for human wild-type APP function and processing. Here, we report that one ED-C99-specific monoclonal antibody (mAbED-C99) blocks human wild-type APP endocytosis and shifts its processing from α- to β-cleavage, as evidenced by elevated accumulation of cell surface full-length APP and β-CTF together with reduced sAPPα and α-CTF levels. Moreover, mAbED-C99 enhances the interactions of APP with cholesterol. Consistently, intracerebroventricular injection of mAbED-C99 to human wild-type APP transgenic mice markedly increases membrane-associated β-CTF. All these findings suggest that APP672-699 region is critical for human wild-type APP processing and may provide new clues for the pathogenesis of sporadic AD.
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Shinohara M, Sato N, Shimamura M, Kurinami H, Hamasaki T, Chatterjee A, Rakugi H, Morishita R. Possible modification of Alzheimer's disease by statins in midlife: interactions with genetic and non-genetic risk factors. Front Aging Neurosci 2014; 6:71. [PMID: 24795626 PMCID: PMC4005936 DOI: 10.3389/fnagi.2014.00071] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Accepted: 03/30/2014] [Indexed: 12/28/2022] Open
Abstract
The benefits of statins, commonly prescribed for hypercholesterolemia, in treating Alzheimer's disease (AD) have not yet been fully established. A recent randomized clinical trial did not show any therapeutic effects of two statins on cognitive function in AD. Interestingly, however, the results of the Rotterdam study, one of the largest prospective cohort studies, showed reduced risk of AD in statin users. Based on the current understanding of statin actions and AD pathogenesis, it is still worth exploring whether statins can prevent AD when administered decades before the onset of AD or from midlife. This review discusses the possible beneficial effects of statins, drawn from previous clinical observations, pathogenic mechanisms, which include β-amyloid (Aβ) and tau metabolism, genetic and non-genetic risk factors (apolipoprotein E, cholesterol, sex, hypertension, and diabetes), and other clinical features (vascular dysfunction and oxidative and inflammatory stress) of AD. These findings suggest that administration of statins in midlife might prevent AD in late life by modifying genetic and non-genetic risk factors for AD. It should be clarified whether statins inhibit Aβ accumulation, tau pathological features, and brain atrophy in humans. To answer this question, a randomized controlled study using amyloid positron emission tomography (PET), tau-PET, and magnetic resonance imaging would be useful. This clinical evaluation could help us to overcome this devastating disease.
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Affiliation(s)
- Mitsuru Shinohara
- Department of Clinical Gene Therapy, Graduate School of Medicine, Osaka UniversitySuita, Japan
- Department of Geriatric Medicine, Graduate School of Medicine, Osaka UniversitySuita, Japan
| | - Naoyuki Sato
- Department of Clinical Gene Therapy, Graduate School of Medicine, Osaka UniversitySuita, Japan
- Department of Geriatric Medicine, Graduate School of Medicine, Osaka UniversitySuita, Japan
| | - Munehisa Shimamura
- Division of Vascular Medicine and Epigenetics, Department of Child Development, United Graduate School of Child Development, Osaka University Office for University-Industry CollaborationSuita, Japan
| | - Hitomi Kurinami
- Division of Vascular Medicine and Epigenetics, Department of Child Development, United Graduate School of Child Development, Osaka University Office for University-Industry CollaborationSuita, Japan
| | - Toshimitsu Hamasaki
- Department of Biomedical Statistics, Graduate School of Medicine, Osaka UniversitySuita, Japan
| | - Amarnath Chatterjee
- Department of Clinical Gene Therapy, Graduate School of Medicine, Osaka UniversitySuita, Japan
| | - Hiromi Rakugi
- Department of Geriatric Medicine, Graduate School of Medicine, Osaka UniversitySuita, Japan
| | - Ryuichi Morishita
- Department of Clinical Gene Therapy, Graduate School of Medicine, Osaka UniversitySuita, Japan
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García-Ayllón MS, Campanari ML, Montenegro MF, Cuchillo-Ibáñez I, Belbin O, Lleó A, Tsim K, Vidal CJ, Sáez-Valero J. Presenilin-1 influences processing of the acetylcholinesterase membrane anchor PRiMA. Neurobiol Aging 2014; 35:1526-36. [PMID: 24612677 DOI: 10.1016/j.neurobiolaging.2014.01.147] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 01/26/2014] [Accepted: 01/30/2014] [Indexed: 01/13/2023]
Abstract
Presenilin-1 (PS1) is the catalytic component of the γ-secretase complex. In this study, we explore if PS1 participates in the processing of the cholinergic acetylcholinesterase (AChE). The major AChE variant expressed in the brain is a tetramer (G(4)) bound to a proline-rich membrane anchor (PRiMA). Overexpression of the transmembrane PRiMA protein in Chinese hamster ovary cells expressing AChE and treated with the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester have enabled us to study whether, through its γ-secretase activity, PS1 participates in the processing of PRiMA-linked AChE. γ-Secretase inhibition led to a notable increase in the level of PRiMA-linked AChE, suggesting that γ-secretase is involved in the cleavage of PRiMA. We demonstrate that cleavage of PRiMA by γ-secretase results in a C-terminal PRiMA fragment. Immunofluorescence labeling allowed us to identify this PRiMA fragment in the nucleus. Moreover, we have determined changes in the proportion of the raft-residing AChE-PRiMA in a PS1 conditional knockout mouse. Our results are of interest as both enzymes have therapeutic relevance for Alzheimer's disease.
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Affiliation(s)
- María-Salud García-Ayllón
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (CSIC), Sant Joan d'Alacant, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Unidad de Investigación, Hospital General Universitario de Elche, Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunitat Valenciana (FISABIO), Elche, Spain
| | - María-Letizia Campanari
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (CSIC), Sant Joan d'Alacant, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - María-Fernanda Montenegro
- Departamento de Bioquímica y Biología Molecular-A, Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", Murcia, Spain
| | - Inmaculada Cuchillo-Ibáñez
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (CSIC), Sant Joan d'Alacant, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Olivia Belbin
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Memory Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Alberto Lleó
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Memory Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Karl Tsim
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Cecilio J Vidal
- Departamento de Bioquímica y Biología Molecular-A, Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", Murcia, Spain
| | - Javier Sáez-Valero
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (CSIC), Sant Joan d'Alacant, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
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Rubio-Moscardo F, Setó-Salvia N, Pera M, Bosch-Morató M, Plata C, Belbin O, Gené G, Dols-Icardo O, Ingelsson M, Helisalmi S, Soininen H, Hiltunen M, Giedraitis V, Lannfelt L, Frank A, Bullido M, Combarros O, Sánchez-Juan P, Boada M, Tárraga L, Pastor P, Pérez-Tur J, Baquero M, Molinuevo JL, Sánchez-Valle R, Fuentes-Prior P, Fortea J, Blesa R, Muñoz FJ, Lleó A, Valverde MA, Clarimón J. Rare variants in calcium homeostasis modulator 1 (CALHM1) found in early onset Alzheimer's disease patients alter calcium homeostasis. PLoS One 2013; 8:e74203. [PMID: 24069280 PMCID: PMC3775809 DOI: 10.1371/journal.pone.0074203] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 07/29/2013] [Indexed: 11/24/2022] Open
Abstract
Calcium signaling in the brain is fundamental to the learning and memory process and there is evidence to suggest that its dysfunction is involved in the pathological pathways underlying Alzheimer’s disease (AD). Recently, the calcium hypothesis of AD has received support with the identification of the non-selective Ca2+-permeable channel CALHM1. A genetic polymorphism (p. P86L) in CALHM1 reduces plasma membrane Ca2+ permeability and is associated with an earlier age-at-onset of AD. To investigate the role of CALHM1 variants in early-onset AD (EOAD), we sequenced all CALHM1 coding regions in three independent series comprising 284 EOAD patients and 326 controls. Two missense mutations in patients (p.G330D and p.R154H) and one (p.A213T) in a control individual were identified. Calcium imaging analyses revealed that while the mutation found in a control (p.A213T) behaved as wild-type CALHM1 (CALHM1-WT), a complete abolishment of the Ca2+ influx was associated with the mutations found in EOAD patients (p.G330D and p.R154H). Notably, the previously reported p. P86L mutation was associated with an intermediate Ca2+ influx between the CALHM1-WT and the p.G330D and p.R154H mutations. Since neither expression of wild-type nor mutant CALHM1 affected amyloid ß-peptide (Aß) production or Aß-mediated cellular toxicity, we conclude that rare genetic variants in CALHM1 lead to Ca2+ dysregulation and may contribute to the risk of EOAD through a mechanism independent from the classical Aß cascade.
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Affiliation(s)
- Fanny Rubio-Moscardo
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, University Pompeu Fabra, Barcelona, Spain
| | - Núria Setó-Salvia
- Memory Unit, Neurology Department, Hospital de Sant Pau (Sant Pau Biomedical Research Institute), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Marta Pera
- Memory Unit, Neurology Department, Hospital de Sant Pau (Sant Pau Biomedical Research Institute), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Mònica Bosch-Morató
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, University Pompeu Fabra, Barcelona, Spain
| | - Cristina Plata
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, University Pompeu Fabra, Barcelona, Spain
| | - Olivia Belbin
- Memory Unit, Neurology Department, Hospital de Sant Pau (Sant Pau Biomedical Research Institute), Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
| | - Gemma Gené
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, University Pompeu Fabra, Barcelona, Spain
| | - Oriol Dols-Icardo
- Memory Unit, Neurology Department, Hospital de Sant Pau (Sant Pau Biomedical Research Institute), Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
| | - Martin Ingelsson
- Department of Public Health, Geriatrics, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Seppo Helisalmi
- Institute of Clinical Medicine – Neurology, University of Eastern Finland and the Department of Neurology, Kuopio University Hospital, Kuopio, Finland
| | - Hilkka Soininen
- Institute of Clinical Medicine – Neurology, University of Eastern Finland and the Department of Neurology, Kuopio University Hospital, Kuopio, Finland
| | - Mikko Hiltunen
- Institute of Clinical Medicine – Neurology, University of Eastern Finland and the Department of Neurology, Kuopio University Hospital, Kuopio, Finland
| | - Vilmantas Giedraitis
- Department of Public Health, Geriatrics, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Lars Lannfelt
- Department of Public Health, Geriatrics, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Ana Frank
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
- Institute of Sanitary Research “Hospital la Paz” (IdIPaz), Madrid, Spain
| | - MªJesús Bullido
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
- Institute of Sanitary Research “Hospital la Paz” (IdIPaz), Madrid, Spain
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain
| | - Onofre Combarros
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
- Neurology Service, University Hospital Marqués de Valdecilla (University of Cantabria and IFIMAV), Santander, Spain
| | - Pascual Sánchez-Juan
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
- Neurology Service, University Hospital Marqués de Valdecilla (University of Cantabria and IFIMAV), Santander, Spain
| | - Mercè Boada
- Alzheimer Research Center and Memory Clinic, Fundació ACE, Institut Català de Neurociències Aplicades, Barcelona, Spain
- Hospital Universitari Vall d’Hebron, Institut de Recerca, Universitat Autònoma de Barcelona (VHIR-UAB), Barcelona, Spain
| | - Lluís Tárraga
- Alzheimer Research Center and Memory Clinic, Fundació ACE, Institut Català de Neurociències Aplicades, Barcelona, Spain
| | - Pau Pastor
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
- Neurogenetics Laboratory, Division of Neurociences, Center for Applied Medical Research (CIMA) University of Navarra Medical School, Pamplona, Spain
| | - Jordi Pérez-Tur
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
- Institut de Biomedicina de Valencia-CSIC, Valencia, Spain
| | - Miquel Baquero
- Neurology Department, Hospital Universitario “La Fe”, Valencia, Spain
| | | | | | - Pablo Fuentes-Prior
- Molecular Basis of Diseases Unit, IIB-Sant Pau, Hospital de la Santa Creu i Sant, Pau, Barcelona, Spain
| | - Juan Fortea
- Memory Unit, Neurology Department, Hospital de Sant Pau (Sant Pau Biomedical Research Institute), Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
| | - Rafael Blesa
- Memory Unit, Neurology Department, Hospital de Sant Pau (Sant Pau Biomedical Research Institute), Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
| | - Francisco J. Muñoz
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, University Pompeu Fabra, Barcelona, Spain
| | - Alberto Lleó
- Memory Unit, Neurology Department, Hospital de Sant Pau (Sant Pau Biomedical Research Institute), Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
| | - Miguel A. Valverde
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, University Pompeu Fabra, Barcelona, Spain
- * E-mail: (JC); (MAV)
| | - Jordi Clarimón
- Memory Unit, Neurology Department, Hospital de Sant Pau (Sant Pau Biomedical Research Institute), Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBERNED, Center for Networked Biomedical Research into Neurodegenerative Diseases, Madrid, Spain
- * E-mail: (JC); (MAV)
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Trushina E, Canaria CA, Lee DY, McMurray CT. Loss of caveolin-1 expression in knock-in mouse model of Huntington's disease suppresses pathophysiology in vivo. Hum Mol Genet 2013; 23:129-44. [PMID: 24021477 DOI: 10.1093/hmg/ddt406] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Loss of cholesterol homeostasis and altered vesicle trafficking have been detected in Huntington's disease (HD) cellular and animal models, yet the role of these dysfunctions in pathophysiology of HD is unknown. We demonstrate here that defects in caveolar-related cholesterol trafficking directly contribute to the mechanism of HD in vivo. We generated new mouse models that express mutant Huntington's protein (mhtt), but have partial or total loss of caveolin-1 (Cav1) expression. Fluorescence resonance energy transfer dequenching confirms a direct interaction between mhtt and Cav1. Mhtt-expressing neurons exhibited cholesterol accumulation and suppressed caveolar-related post-Golgi trafficking from endoplasmic reticulum/Golgi to plasma membrane. Loss or reduction of Cav1 expression in a knock-in HD mouse model rescues the cholesterol phenotype in neurons and significantly delays the onset of motor decline and development of neuronal inclusions. We propose that aberrant interaction between Cav1 and mhtt leads to altered cholesterol homeostasis and plays a direct causative role in the onset of HD pathophysiology in vivo.
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WANG JISHENG, WU FENGMING, SHI CHUN. Substitution of membrane cholesterol with β-sitosterol promotes nonamyloidogenic cleavage of endogenous amyloid precursor protein. Neuroscience 2013; 247:227-33. [DOI: 10.1016/j.neuroscience.2013.05.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Revised: 05/02/2013] [Accepted: 05/14/2013] [Indexed: 10/26/2022]
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Song Y, Hustedt EJ, Brandon S, Sanders CR. Competition between homodimerization and cholesterol binding to the C99 domain of the amyloid precursor protein. Biochemistry 2013; 52:5051-64. [PMID: 23865807 DOI: 10.1021/bi400735x] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The 99-residue transmembrane C-terminal domain (C99, also known as β-CTF) of the amyloid precursor protein (APP) is the product of the β-secretase cleavage of the full-length APP and is the substrate for γ-secretase cleavage. The latter cleavage releases the amyloid-β polypeptides that are closely associated with Alzheimer's disease. C99 is thought to form homodimers; however, the free energy in favor of dimerization has not previously been quantitated. It was also recently documented that cholesterol forms a 1:1 complex with monomeric C99 in bicelles. Here, the affinities for both homodimerization and cholesterol binding to C99 were measured in bilayered lipid vesicles using both electron paramagnetic resonance (EPR) and Förster resonance energy transfer (FRET) methods. Homodimerization and cholesterol binding were seen to be competitive processes that center on the transmembrane G₇₀₀XXXG₇₀₄XXXG₇₀₈ glycine-zipper motif and adjacent Gly709. On one hand, the observed Kd for cholesterol binding (Kd = 2.7 ± 0.3 mol %) is on the low end of the physiological cholesterol concentration range in mammalian cell membranes. On the other hand, the observed K(d) for homodimerization (K(d) = 0.47 ± 0.15 mol %) likely exceeds the physiological concentration range for C99. These results suggest that the 1:1 cholesterol/C99 complex will be more highly populated than C99 homodimers under most physiological conditions. These observations are of relevance for understanding the γ-secretase cleavage of C99.
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Affiliation(s)
- Yuanli Song
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
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Schon EA, Area-Gomez E. Mitochondria-associated ER membranes in Alzheimer disease. Mol Cell Neurosci 2013; 55:26-36. [DOI: 10.1016/j.mcn.2012.07.011] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 07/26/2012] [Accepted: 07/27/2012] [Indexed: 01/03/2023] Open
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Flix B, de la Torre C, Castillo J, Casal C, Illa I, Gallardo E. Dysferlin interacts with calsequestrin-1, myomesin-2 and dynein in human skeletal muscle. Int J Biochem Cell Biol 2013; 45:1927-38. [PMID: 23792176 DOI: 10.1016/j.biocel.2013.06.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 05/24/2013] [Accepted: 06/09/2013] [Indexed: 11/25/2022]
Abstract
Dysferlinopathies are a group of progressive muscular dystrophies characterized by mutations in the gene DYSF. These mutations cause scarcity or complete absence of dysferlin, a protein that is expressed in skeletal muscle and plays a role in membrane repair. Our objective was to unravel the proteins that constitute the dysferlin complex and their interaction within the complex using immunoprecipitation assays (IP), blue native gel electrophoresis (BN) in healthy adult skeletal muscle and healthy cultured myotubes, and fluorescence lifetime imaging-fluorescence resonance energy transfer (FLIM-FRET) analysis in healthy myotubes. The combination of immunoprecipitations and blue native electrophoresis allowed us to identify previously reported partners of dysferlin - such as caveolin-3, AHNAK, annexins, or Trim72/MG53 - and new interacting partners. Fluorescence lifetime imaging showed a direct interaction of dysferlin with Trim72/MG53, AHNAK, cytoplasmic dynein, myomesin-2 and calsequestrin-1, but not with caveolin-3 or dystrophin. In conclusion, although IP and BN are useful tools to identify the proteins in a complex, techniques such as fluorescence lifetime imaging analysis are needed to determine the direct and indirect interactions of these proteins within the complex. This knowledge may help us to better understand the roles of dysferlin in muscle tissue and identify new genes involved in muscular dystrophies in which the responsible gene is unknown.
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Affiliation(s)
- Bàrbara Flix
- Servei de Neurologia, Laboratori de Neurologia Experimental, Hospital de la Santa Creu i Sant Pau i Institut de Recerca de HSCSP, Barcelona, Spain
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Prazosin, an α1-adrenoceptor antagonist, prevents memory deterioration in the APP23 transgenic mouse model of Alzheimer's disease. Neurobiol Aging 2013; 34:1105-15. [DOI: 10.1016/j.neurobiolaging.2012.09.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 09/05/2012] [Accepted: 09/07/2012] [Indexed: 01/16/2023]
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von Einem B, Weber P, Wagner M, Malnar M, Kosicek M, Hecimovic S, von Arnim CAF, Schneckenburger H. Cholesterol-dependent energy transfer between fluorescent proteins-insights into protein proximity of APP and BACE1 in different membranes in Niemann-Pick type C disease cells. Int J Mol Sci 2012; 13:15801-12. [PMID: 23443094 PMCID: PMC3546662 DOI: 10.3390/ijms131215801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 11/14/2012] [Accepted: 11/15/2012] [Indexed: 12/27/2022] Open
Abstract
Förster resonance energy transfer (FRET) -based techniques have recently been applied to study the interactions between β-site APP-cleaving enzyme-GFP (BACE1-GFP) and amyloid precursor protein-mRFP (APP-mRFP) in U373 glioblastoma cells. In this context, the role of APP-BACE1 proximity in Alzheimer’s disease (AD) pathogenesis has been discussed. FRET was found to depend on intracellular cholesterol levels and associated alterations in membrane stiffness. Here, NPC1 null cells (CHO-NPC1−/−), exhibiting increased cholesterol levels and disturbed cholesterol transport similar to that observed in Niemann-Pick type C disease (NPC), were used to analyze the influence of altered cholesterol levels on APP-BACE1 proximity. Fluorescence lifetime measurements of whole CHO-wild type (WT) and CHO-NPC1−/− cells (EPI-illumination microscopy), as well as their plasma membranes (total internal reflection fluorescence microscopy, TIRFM), were performed. Additionally, generalized polarization (GP) measurements of CHO-WT and CHO-NPC1−/− cells incubated with the fluorescence marker laurdan were performed to determine membrane stiffness of plasma- and intracellular-membranes. CHO-NPC1−/− cells showed higher membrane stiffness at intracellular- but not plasma-membranes, equivalent to cholesterol accumulation in late endosomes/lysosomes. Along with higher membrane stiffness, the FRET efficiency between BACE1-GFP and APP-mRFP was reduced at intracellular membranes, but not within the plasma membrane of CHO-NPC1−/−. Our data show that FRET combined with TIRF is a powerful technique to determine protein proximity and membrane fluidity in cellular models of neurodegenerative diseases.
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Affiliation(s)
- Bjoern von Einem
- Department of Experimental Neurology, Ulm University, Helmholtz Str. 8/1, 89081 Ulm, Germany; E-Mails: (B.E.); (C.A.F.A.)
| | - Petra Weber
- Institut für Angewandte Forschung, Hochschule Aalen, Anton-Huber Str. 21, 73430 Aalen, Germany; E-Mails: (P.W.); (M.W.)
| | - Michael Wagner
- Institut für Angewandte Forschung, Hochschule Aalen, Anton-Huber Str. 21, 73430 Aalen, Germany; E-Mails: (P.W.); (M.W.)
| | - Martina Malnar
- Division of Molecular Medicine, Rudjer Boskovic Institute, Bijenicka 54, 10000 Zagreb, Croatia; E-Mails: (M.M.); (M.K.); (S.H.)
| | - Marko Kosicek
- Division of Molecular Medicine, Rudjer Boskovic Institute, Bijenicka 54, 10000 Zagreb, Croatia; E-Mails: (M.M.); (M.K.); (S.H.)
| | - Silva Hecimovic
- Division of Molecular Medicine, Rudjer Boskovic Institute, Bijenicka 54, 10000 Zagreb, Croatia; E-Mails: (M.M.); (M.K.); (S.H.)
| | - Christine A. F. von Arnim
- Department of Experimental Neurology, Ulm University, Helmholtz Str. 8/1, 89081 Ulm, Germany; E-Mails: (B.E.); (C.A.F.A.)
| | - Herbert Schneckenburger
- Institut für Angewandte Forschung, Hochschule Aalen, Anton-Huber Str. 21, 73430 Aalen, Germany; E-Mails: (P.W.); (M.W.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +49-7361-576-3401
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Control of Aβ release from human neurons by differentiation status and RET signaling. Neurobiol Aging 2012; 34:184-99. [PMID: 22534065 DOI: 10.1016/j.neurobiolaging.2012.03.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 02/14/2012] [Accepted: 03/24/2012] [Indexed: 12/28/2022]
Abstract
Few studies have compared the processing of endogenous human amyloid precursor protein (APP) in younger and older neurons. Here, we characterized LUHMES cells as a human model to study Alzheimer's disease-related processes during neuronal maturation and aging. Differentiated LUHMES expressed and spontaneously processed APP via the secretase pathways, and they secreted amyloid β (Aβ) peptide. This was inhibited by cholesterol depletion or secretase inhibition, but not by block of tau phosphorylation. In vitro aged cells increased Aβ secretion without upregulation of APP or secretases. We identified the medium constituent glial cell line-derived neurotrophic factor (GDNF) as responsible for this effect. GDNF-triggered Aβ release was associated with rapid upregulation of the GDNF coreceptor "rearranged during transfection" (RET). Other direct (neurturin) or indirect (nerve growth factor) RET activators also increased Aβ, whereas different neurotrophins were ineffective. Downstream of RET, we found activation of protein kinase B (AKT) to be involved. Accordingly, inhibitors of the AKT regulator phosphatidylinositol-3-kinase completely blocked GDNF-triggered AKT phosphorylation and Aβ increase. This suggests that RET signaling affects Aβ release from aging neurons.
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Vanmierlo T, Weingärtner O, van der Pol S, Husche C, Kerksiek A, Friedrichs S, Sijbrands E, Steinbusch H, Grimm M, Hartmann T, Laufs U, Böhm M, de Vries HE, Mulder M, Lütjohann D. Dietary intake of plant sterols stably increases plant sterol levels in the murine brain. J Lipid Res 2012; 53:726-35. [PMID: 22279184 DOI: 10.1194/jlr.m017244] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Plant sterols such as sitosterol and campesterol are frequently administered as cholesterol-lowering supplements in food. Recently, it has been shown in mice that, in contrast to the structurally related cholesterol, circulating plant sterols can enter the brain. We questioned whether the accumulation of plant sterols in murine brain is reversible. After being fed a plant sterol ester-enriched diet for 6 weeks, C57BL/6NCrl mice displayed significantly increased concentrations of plant sterols in serum, liver, and brain by 2- to 3-fold. Blocking intestinal sterol uptake for the next 6 months while feeding the mice with a plant stanol ester-enriched diet resulted in strongly decreased plant sterol levels in serum and liver, without affecting brain plant sterol levels. Relative to plasma concentrations, brain levels of campesterol were higher than sitosterol, suggesting that campesterol traverses the blood-brain barrier more efficiently. In vitro experiments with brain endothelial cell cultures showed that campesterol crossed the blood-brain barrier more efficiently than sitosterol. We conclude that, over a 6-month period, plant sterol accumulation in murine brain is virtually irreversible.
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Affiliation(s)
- Tim Vanmierlo
- Institute of Clinical Chemistry and Clinical Pharmacology, University of Bonn, Bonn, Germany
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Probucol, a lipid-lowering drug, prevents cognitive and hippocampal synaptic impairments induced by amyloid β peptide in mice. Exp Neurol 2011; 233:767-75. [PMID: 22173317 DOI: 10.1016/j.expneurol.2011.11.036] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 11/17/2011] [Accepted: 11/25/2011] [Indexed: 11/20/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by synaptic loss and cognitive impairments. The presence of extracellular senile plaques (mainly composed of amyloid-β (Aβ) peptide) is an important molecular hallmark in AD and neuronal damage has been attributed, at least in part, to Aβ-mediated toxicity. Although the molecular mechanisms involved in the pathogenesis of AD are not yet completely understood, several lines of evidence indicate that oxidative stress and cholesterol dyshomeostasis play crucial roles in mediating the synaptic loss and cognitive deficits observed in AD patients. This study evaluated the effects of Probucol, a phenolic lipid-lowering agent with anti-inflammatory and antioxidant properties, on biochemical parameters related to oxidative stress and synaptic function (hippocampal glutathione and synaptophysin levels; glutathione peroxidase, glutathione reductase and acetylcholinesterase activities; lipid peroxidation), as well as on behavioral parameters related to the cognitive function (displaced and new object recognition tasks) in Aβ-exposed mice. Animals were treated with a single intracerebroventricular (i.c.v.) injection of aggregated Aβ(1-40) (400 pmol/site) and, subsequently, received Probucol (10 mg/kg, i.p.) once a day, during the following 2 weeks. At the end of treatments, Aβ(1-40)-exposed animals showed a significant impairment on learning-memory ability, which was paralleled by a significant decrease in hippocampal synaptophysin levels, as well as by an increase in hippocampal acetylcholinesterase activity. Importantly, Probucol treatment blunted the deleterious effects of Aβ(1-40) on learning-memory ability and hippocampal biochemistry. Although Aβ(1-40) treatment did not change hippocampal glutathione levels and glutathione peroxidase (GPx) and glutathione reductase (GR) activities, Aβ(1-40)-exposed animals showed increased hippocampal lipid peroxidation and this event was completely blunted by Probucol treatment. These findings reinforce and extend the notion of the hazardous effects of Aβ(1-40) toward hippocampal synaptic homeostasis and cognitive functions. In addition, the present results indicate that Probucol is able to counteract the cognitive and biochemical impairments induced by i.c.v. Aβ(1-40) administration in mice. The study is the first to report the protective effects of Probucol (a "non-statin cholesterol-lowering drug") against Aβ(1-40)-induced synaptic and behavioral impairments, rendering this compound a promising molecule for further pharmacological studies on the search for therapeutic strategies to treat or prevent AD.
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40
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Badiola N, de Oliveira RM, Herrera F, Guardia-Laguarta C, Gonçalves SA, Pera M, Suárez-Calvet M, Clarimon J, Outeiro TF, Lleó A. Tau enhances α-synuclein aggregation and toxicity in cellular models of synucleinopathy. PLoS One 2011; 6:e26609. [PMID: 22039514 PMCID: PMC3200341 DOI: 10.1371/journal.pone.0026609] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 09/29/2011] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The simultaneous accumulation of different misfolded proteins in the central nervous system is a common feature in many neurodegenerative diseases. In most cases, co-occurrence of abnormal deposited proteins is observed in different brain regions and cell populations, but, in some instances, the proteins can be found in the same cellular aggregates. Co-occurrence of tau and α-synuclein (α-syn) aggregates has been described in neurodegenerative disorders with primary deposition of α-syn, such as Parkinson's disease and dementia with Lewy bodies. Although it is known that tau and α-syn have pathological synergistic effects on their mutual fibrillization, the underlying biological effects remain unclear. METHODOLOGY/PRINCIPAL FINDINGS We used different cell models of synucleinopathy to investigate the effects of tau on α-syn aggregation. Using confocal microscopy and FRET-based techniques we observed that tau colocalized and interacted with α-syn aggregates. We also found that tau overexpression changed the pattern of α-syn aggregation, reducing the size and increasing the number of aggregates. This shift was accompanied by an increase in the levels of insoluble α-syn. Furthermore, co-transfection of tau increased secreted α-syn and cytotoxicity. CONCLUSIONS/SIGNIFICANCE Our data suggest that tau enhances α-syn aggregation and toxicity and disrupts α-syn inclusion formation. This pathological synergistic effect between tau and α-syn may amplify the deleterious process and spread the damage in neurodegenerative diseases that show co-occurrence of both pathologies.
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Affiliation(s)
- Nahuai Badiola
- Instituto de Investigacions Biomediques Sant Pau, Hospital de Sant Pau, Barcelona, Spain
- Centro de Investigación Biomédica en Red para enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | | | - Federico Herrera
- Cell and Molecular Neuroscience Unit, Instituto de Medicina Molecular, Lisbon, Portugal
| | - Cristina Guardia-Laguarta
- Instituto de Investigacions Biomediques Sant Pau, Hospital de Sant Pau, Barcelona, Spain
- Centro de Investigación Biomédica en Red para enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Susana A. Gonçalves
- Cell and Molecular Neuroscience Unit, Instituto de Medicina Molecular, Lisbon, Portugal
| | - Marta Pera
- Instituto de Investigacions Biomediques Sant Pau, Hospital de Sant Pau, Barcelona, Spain
- Centro de Investigación Biomédica en Red para enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Marc Suárez-Calvet
- Instituto de Investigacions Biomediques Sant Pau, Hospital de Sant Pau, Barcelona, Spain
- Centro de Investigación Biomédica en Red para enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Jordi Clarimon
- Instituto de Investigacions Biomediques Sant Pau, Hospital de Sant Pau, Barcelona, Spain
- Centro de Investigación Biomédica en Red para enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Tiago Fleming Outeiro
- Cell and Molecular Neuroscience Unit, Instituto de Medicina Molecular, Lisbon, Portugal
- Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Alberto Lleó
- Instituto de Investigacions Biomediques Sant Pau, Hospital de Sant Pau, Barcelona, Spain
- Centro de Investigación Biomédica en Red para enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
- * E-mail:
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Vanmierlo T, Popp J, Kölsch H, Friedrichs S, Jessen F, Stoffel-Wagner B, Bertsch T, Hartmann T, Maier W, von Bergmann K, Steinbusch H, Mulder M, Lütjohann D. The plant sterol brassicasterol as additional CSF biomarker in Alzheimer's disease. Acta Psychiatr Scand 2011; 124:184-92. [PMID: 21585343 DOI: 10.1111/j.1600-0447.2011.01713.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Plant sterols (sitosterol, campesterol, stigmasterol and brassicasterol) are solely dietary-derivable sterols that are structurally very similar to cholesterol. In contrast to peripheral cholesterol, plant sterols can cross the blood-brain barrier and accumulate within mammalian brain. As an impaired function of the cerebrospinal fluid (CSF)-blood barrier is linked to neurodegenerative disorders, i.e. Alzheimer's disease (AD), we investigated whether this results in altered plant sterol concentrations in CSF. METHOD Applying gas chromatography/mass spectrometry analysis, plant sterol concentrations were measured in plasma and CSF of patients with AD (n = 67) and controls (n = 29). Age, gender, plasma-to-CSF albumin ratio, CSF Aβ(42) , CSF pTau, APOE4 genotype, and serum creatinine were applied as covariates in the statistical analysis for individual plant sterols in order to compare plasma and CSF plant sterol concentrations between patients with AD and controls. RESULTS Albumin quotient was a consistent predictor in CSF for cholesterol and methyl plant sterols campesterol and brassicasterol. Comparison of lipid parameters per diagnosis based on relevant predictors revealed significantly lower concentrations of brassicasterol (P < 0.001) in CSF of patients with AD. Binary logistic regression analysis revealed that brassicasterol improved the predictive value when added to pTau and Aβ42 in a biomarker model. CONCLUSION Brassicasterol might be a relevant additional biomarker in AD.
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Affiliation(s)
- T Vanmierlo
- Institute of Clinical Chemistry and Clinical Pharmacology, University Clinics Bonn, Germany
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Groemer TW, Thiel CS, Holt M, Riedel D, Hua Y, Hüve J, Wilhelm BG, Klingauf J. Amyloid precursor protein is trafficked and secreted via synaptic vesicles. PLoS One 2011; 6:e18754. [PMID: 21556148 PMCID: PMC3083403 DOI: 10.1371/journal.pone.0018754] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 03/16/2011] [Indexed: 02/04/2023] Open
Abstract
A large body of evidence has implicated amyloid precursor protein (APP) and its proteolytic derivatives as key players in the physiological context of neuronal synaptogenesis and synapse maintenance, as well as in the pathology of Alzheimer's Disease (AD). Although APP processing and release are known to occur in response to neuronal stimulation, the exact mechanism by which APP reaches the neuronal surface is unclear. We now demonstrate that a small but relevant number of synaptic vesicles contain APP, which can be released during neuronal activity, and most likely represent the major exocytic pathway of APP. This novel finding leads us to propose a revised model of presynaptic APP trafficking that reconciles existing knowledge on APP with our present understanding of vesicular release and recycling.
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Affiliation(s)
- Teja W. Groemer
- Department of Membrane Biophysics, Max Planck Institute for Biophysical
Chemistry, Göttingen, Germany
- Department of Psychiatry and Psychotherapy, University of Erlangen,
Erlangen, Germany
| | - Cora S. Thiel
- Department of Membrane Biophysics, Max Planck Institute for Biophysical
Chemistry, Göttingen, Germany
- Institute of Medical Physics and Biophysics, University of Münster,
Münster, Germany
| | - Matthew Holt
- Department of Neurobiology, Max Planck Institute for Biophysical
Chemistry, Göttingen, Germany
- * E-mail: (MH); (JK)
| | - Dietmar Riedel
- Electron Microscopy Group, Max Planck Institute for Biophysical
Chemistry, Göttingen, Germany
| | - Yunfeng Hua
- Department of Membrane Biophysics, Max Planck Institute for Biophysical
Chemistry, Göttingen, Germany
- Institute of Medical Physics and Biophysics, University of Münster,
Münster, Germany
| | - Jana Hüve
- Fluorescence Microscopy Facility Münster, Institute of Medical
Physics and Biophysics, University of Münster, Münster,
Germany
| | - Benjamin G. Wilhelm
- Department of Membrane Biophysics, Max Planck Institute for Biophysical
Chemistry, Göttingen, Germany
| | - Jürgen Klingauf
- Department of Membrane Biophysics, Max Planck Institute for Biophysical
Chemistry, Göttingen, Germany
- Institute of Medical Physics and Biophysics, University of Münster,
Münster, Germany
- * E-mail: (MH); (JK)
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Grimm MOW, Kuchenbecker J, Grösgen S, Burg VK, Hundsdörfer B, Rothhaar TL, Friess P, de Wilde MC, Broersen LM, Penke B, Péter M, Vígh L, Grimm HS, Hartmann T. Docosahexaenoic acid reduces amyloid beta production via multiple pleiotropic mechanisms. J Biol Chem 2011; 286:14028-39. [PMID: 21324907 DOI: 10.1074/jbc.m110.182329] [Citation(s) in RCA: 159] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alzheimer disease is characterized by accumulation of the β-amyloid peptide (Aβ) generated by β- and γ-secretase processing of the amyloid precursor protein (APP). The intake of the polyunsaturated fatty acid docosahexaenoic acid (DHA) has been associated with decreased amyloid deposition and a reduced risk in Alzheimer disease in several epidemiological trials; however, the exact underlying molecular mechanism remains to be elucidated. Here, we systematically investigate the effect of DHA on amyloidogenic and nonamyloidogenic APP processing and the potential cross-links to cholesterol metabolism in vivo and in vitro. DHA reduces amyloidogenic processing by decreasing β- and γ-secretase activity, whereas the expression and protein levels of BACE1 and presenilin1 remain unchanged. In addition, DHA increases protein stability of α-secretase resulting in increased nonamyloidogenic processing. Besides the known effect of DHA to decrease cholesterol de novo synthesis, we found cholesterol distribution in plasma membrane to be altered. In the presence of DHA, cholesterol shifts from raft to non-raft domains, and this is accompanied by a shift in γ-secretase activity and presenilin1 protein levels. Taken together, DHA directs amyloidogenic processing of APP toward nonamyloidogenic processing, effectively reducing Aβ release. DHA has a typical pleiotropic effect; DHA-mediated Aβ reduction is not the consequence of a single major mechanism but is the result of combined multiple effects.
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Affiliation(s)
- Marcus O W Grimm
- Department of Neurodegeneration and Neurobiology, Deutsches Institut für DemenzPrävention, Saarland University, 66421 Homburg, Germany.
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Rushworth JV, Hooper NM. Lipid Rafts: Linking Alzheimer's Amyloid-β Production, Aggregation, and Toxicity at Neuronal Membranes. Int J Alzheimers Dis 2010; 2011:603052. [PMID: 21234417 PMCID: PMC3014710 DOI: 10.4061/2011/603052] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 11/03/2010] [Indexed: 01/03/2023] Open
Abstract
Lipid rafts are membrane microdomains, enriched in cholesterol and sphingolipids, into which specific subsets of proteins and lipids partition, creating cell-signalling platforms that are vital for neuronal functions. Lipid rafts play at least three crucial roles in Alzheimer's Disease (AD), namely, in promoting the generation of the amyloid-β (Aβ) peptide, facilitating its aggregation upon neuronal membranes to form toxic oligomers and hosting specific neuronal receptors through which the AD-related neurotoxicity and memory impairments of the Aβ oligomers are transduced. Recent evidence suggests that Aβ oligomers may exert their deleterious effects through binding to, and causing the aberrant clustering of, lipid raft proteins including the cellular prion protein and glutamate receptors. The formation of these pathogenic lipid raft-based platforms may be critical for the toxic signalling mechanisms that underlie synaptic dysfunction and neuropathology in AD.
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Affiliation(s)
- Jo V. Rushworth
- Institute of Molecular and Cellular Biology, Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Nigel M. Hooper
- Institute of Molecular and Cellular Biology, Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, LIGHT Laboratories, Clarendon Way, University of Leeds, Leeds LS2 9JT, UK
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Giménez-Llort L, García Y, Buccieri K, Revilla S, Suñol C, Cristofol R, Sanfeliu C. Gender-Specific Neuroimmunoendocrine Response to Treadmill Exercise in 3xTg-AD Mice. Int J Alzheimers Dis 2010; 2010:128354. [PMID: 20981262 PMCID: PMC2964036 DOI: 10.4061/2010/128354] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2010] [Accepted: 08/09/2010] [Indexed: 12/04/2022] Open
Abstract
The 3xTg-AD mouse develops a progressive Alzheimer's disease- (AD-) like brain pathology that causes cognitive- and neuropsychiatric-like symptoms of dementia. Since its neuroimmunoendocrine axis is likewise impaired, this mouse is also useful for modelling complex age-related neurodegeneration. This study analyzed behavioral, physiological, neurochemical, pathological and immunoendocrine alterations in male and female 3xTg-AD mice and assayed the effects of a short therapy of forced physical exercise at the moderate pathology stage of 6 months of age. Gender effects were observed in most AD-related pathology and dysfunctions. Five weeks of treadmill training produced beneficial effects, such as the reduction of brain oxidative stress and GABA-A receptor dysfunction in males and improvement of sensorimotor function in females. In both sexes, exercise decreased the brain amyloid β 42/40 ratio levels. The results highlight the importance of analyzing experimental therapies in both mouse model genders in order to improve our understanding of the disease and develop more appropriate therapies.
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Affiliation(s)
- Lydia Giménez-Llort
- Medical Psychology Unit, Department of Psychiatry and Forensic Medicine, Institute of Neuroscience, Autonomous University of Barcelona, Bellaterra, 08193 Barcelona, Spain
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beta-Amyloid disrupts activity-dependent gene transcription required for memory through the CREB coactivator CRTC1. J Neurosci 2010; 30:9402-10. [PMID: 20631169 DOI: 10.1523/jneurosci.2154-10.2010] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Activity-dependent gene expression mediating changes of synaptic efficacy is important for memory storage, but the mechanisms underlying gene transcriptional changes in age-related memory disorders are poorly understood. In this study, we report that gene transcription mediated by the cAMP-response element binding protein (CREB)-regulated transcription coactivator CRTC1 is impaired in neurons and brain from an Alzheimer's disease (AD) transgenic mouse expressing the human beta-amyloid precursor protein (APP(Sw,Ind)). Suppression of CRTC1-dependent gene transcription by beta-amyloid (Abeta) in response to cAMP and Ca(2+) signals is mediated by reduced calcium influx and disruption of PP2B/calcineurin-dependent CRTC1 dephosphorylation at Ser151. Consistently, expression of CRTC1 or active CRTC1 S151A and calcineurin mutants reverse the deficits on CRTC1 transcriptional activity in APP(Sw,Ind) neurons. Inhibition of calcium influx by pharmacological blockade of L-type voltage-gated calcium channels (VGCCs), but not by blocking NMDA or AMPA receptors, mimics the decrease on CRTC1 transcriptional activity observed in APP(Sw,Ind) neurons, whereas agonists of L-type VGCCs reverse efficiently these deficits. Consistent with a role of CRTC1 on Abeta-induced synaptic and memory dysfunction, we demonstrate a selective reduction of CRTC1-dependent genes related to memory (Bdnf, c-fos, and Nr4a2) coinciding with hippocampal-dependent spatial memory deficits in APP(Sw,Ind) mice. These findings suggest that CRTC1 plays a key role in coupling synaptic activity to gene transcription required for hippocampal-dependent memory, and that Abeta could disrupt cognition by affecting CRTC1 function.
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47
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Shinohara M, Sato N, Kurinami H, Takeuchi D, Takeda S, Shimamura M, Yamashita T, Uchiyama Y, Rakugi H, Morishita R. Reduction of brain beta-amyloid (Abeta) by fluvastatin, a hydroxymethylglutaryl-CoA reductase inhibitor, through increase in degradation of amyloid precursor protein C-terminal fragments (APP-CTFs) and Abeta clearance. J Biol Chem 2010; 285:22091-102. [PMID: 20472556 DOI: 10.1074/jbc.m110.102277] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Epidemiological studies suggest that statins (hydroxymethylglutaryl-CoA reductase inhibitors) could reduce the risk of Alzheimer disease. Although one possible explanation is through an effect on beta-amyloid (Abeta) metabolism, its effect remains to be elucidated. Here, we explored the molecular mechanisms of how statins influence Abeta metabolism. Fluvastatin at clinical doses significantly reduced Abeta and amyloid precursor protein C-terminal fragment (APP-CTF) levels among APP metabolites in the brain of C57BL/6 mice. Chronic intracerebroventricular infusion of lysosomal inhibitors blocked these effects, indicating that up-regulation of the lysosomal degradation of endogenous APP-CTFs is involved in reduced Abeta production. Biochemical analysis suggested that this was mediated by enhanced trafficking of APP-CTFs from endosomes to lysosomes, associated with marked changes of Rab proteins, which regulate endosomal function. In primary neurons, fluvastatin enhanced the degradation of APP-CTFs through an isoprenoid-dependent mechanism. Because our previous study suggests additive effects of fluvastatin on Abeta metabolism, we examined Abeta clearance rates by using the brain efflux index method and found its increased rates at high Abeta levels from brain. As LRP1 in brain microvessels was increased, up-regulation of LRP1-mediated Abeta clearance at the blood-brain barrier might be involved. In cultured brain microvessel endothelial cells, fluvastatin increased LRP1 and the uptake of Abeta, which was blocked by LRP1 antagonists, through an isoprenoid-dependent mechanism. Overall, the present study demonstrated that fluvastatin reduced Abeta level by an isoprenoid-dependent mechanism. These results have important implications for the development of disease-modifying therapy for Alzheimer disease as well as understanding of Abeta metabolism.
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Affiliation(s)
- Mitsuru Shinohara
- Department of Clinical Gene Therapy, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
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Dickstein DL, Walsh J, Brautigam H, Stockton SD, Gandy S, Hof PR. Role of vascular risk factors and vascular dysfunction in Alzheimer's disease. ACTA ACUST UNITED AC 2010; 77:82-102. [PMID: 20101718 DOI: 10.1002/msj.20155] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Recent findings indicate that vascular risk factors and neurovascular dysfunction play integral roles in the pathogenesis of Alzheimer's disease. In addition to aging, the most common risk factors for Alzheimer's disease are apolipoprotein e4 allele, hypertension, hypotension, diabetes, and hypercholesterolemia. All of these can be characterized by vascular pathology attributed to conditions such as cerebral amyloid angiopathy and subsequent blood-brain barrier dysfunction. Many epidemiological, clinical, and pharmacotherapeutic studies have assessed the associations between such risk factors and Alzheimer's disease and have found positive associations between hypertension, hypotension, and diabetes mellitus. However, there are still many conflicting results from these population-based studies, and they should be interpreted carefully. Recognition of these factors and the mechanisms by which they contribute to Alzheimer's disease will be beneficial in the current treatment regimens for Alzheimer's disease and in the development of future therapies. Here we discuss vascular factors with respect to Alzheimer's disease and dementia and review the factors that give rise to vascular dysfunction and contribute to Alzheimer's disease.
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Affiliation(s)
- Dara L Dickstein
- Department of Neuroscience and Kastor Neurobiology of Aging Laboratories, Mount Sinai School of Medicine, New York, NY, USA.
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49
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Beel AJ, Sakakura M, Barrett PJ, Sanders CR. Direct binding of cholesterol to the amyloid precursor protein: An important interaction in lipid-Alzheimer's disease relationships? Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:975-82. [PMID: 20304095 DOI: 10.1016/j.bbalip.2010.03.008] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 03/10/2010] [Accepted: 03/10/2010] [Indexed: 12/21/2022]
Abstract
It is generally believed that cholesterol homoeostasis in the brain is both linked to and impacted by Alzheimer's disease (AD). For example, elevated levels of cholesterol in neuronal plasma and endosome membranes appear to be a pro-amyloidogenic factor. The recent observation that the C-terminal transmembrane domain (C99, also known as the beta-C-terminal fragment, or beta-CTF) of the amyloid precursor protein (APP) specifically binds cholesterol helps to tie together previously loose ends in the web of our understanding of Alzheimer's-cholesterol relationships. In particular, binding of cholesterol to C99 appears to favor the amyloidogenic pathway in cells by promoting localization of C99 in lipid rafts. In turn, the products of this pathway-amyloid-beta and the intracellular domain of the APP (AICD)-may down-regulate ApoE-mediated cholesterol uptake and cholesterol biosynthesis. If confirmed, this negative-feedback loop for membrane cholesterol levels has implications for understanding the function of the APP and for devising anti-amyloidogenic preventive strategies for AD.
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Affiliation(s)
- Andrew J Beel
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-8725, USA
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50
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Clinical, neuropathologic, and biochemical profile of the amyloid precursor protein I716F mutation. J Neuropathol Exp Neurol 2010; 69:53-9. [PMID: 20010303 DOI: 10.1097/nen.0b013e3181c6b84d] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
We report the clinical, pathologic, and biochemical characteristics of the recently described amyloid precursor protein (APP) I716F mutation. We present the clinical findings of individuals carrying the APP I716F mutation and the neuropathologic examination of the proband. The mutation was found in a patient with Alzheimer disease with onset at the age of 31 years and death at age 36 years and who had a positive family history of early-onset Alzheimer disease. Neuropathologic examination showed abundant diffuse amyloid plaques mainly composed of amyloid-beta42 and widespread neurofibrillary pathology. Lewy bodies were found in the amygdala. Chinese hamster ovary cells transfected with this mutation showed a marked increase in the amyloid-beta42/40 ratio and APP C-terminal fragments and a decrease in APP intracellular domain production, suggesting reduced APP proteolysis by gamma-secretase. Taken together, these findings indicate that the APP I716F mutation is associated with the youngest age of onset for this locus and strengthen the inverse association between amyloid-beta42/40 ratio and age of onset. The mutation leads to a protein that is poorly processed by gamma-secretase. This loss of function may be an additional mechanism by which some mutations around the gamma-secretase cleavage site lead to familial Alzheimer disease.
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