101
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Sonawane KD, Barage SH. Structural analysis of membrane-bound hECE-1 dimer using molecular modeling techniques: insights into conformational changes and Aβ1–42 peptide binding. Amino Acids 2014; 47:543-59. [DOI: 10.1007/s00726-014-1887-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 11/28/2014] [Indexed: 10/24/2022]
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Vandal M, White PJ, Tremblay C, St-Amour I, Chevrier G, Emond V, Lefrançois D, Virgili J, Planel E, Giguere Y, Marette A, Calon F. Insulin reverses the high-fat diet-induced increase in brain Aβ and improves memory in an animal model of Alzheimer disease. Diabetes 2014; 63:4291-301. [PMID: 25008180 DOI: 10.2337/db14-0375] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Defects in insulin production and signaling are suspected to share a key role in diabetes and Alzheimer disease (AD), two age-related pathologies. In this study, we investigated the interrelation between AD and diabetes using a high-fat diet (HFD) in a mouse model of genetically induced AD-like neuropathology (3xTg-AD). We first observed that cerebral expression of human AD transgenes led to peripheral glucose intolerance, associated with pancreatic human Aβ accumulation. High-fat diet enhanced glucose intolerance, brain soluble Aβ, and memory impairment in 3xTg-AD mice. Strikingly, a single insulin injection reversed the deleterious effects of HFD on memory and soluble Aβ levels, partly through changes in Aβ production and/or clearance. Our results are consistent with the development of a vicious cycle between AD and diabetes, potentiating both peripheral metabolic disorders and AD neuropathology. The capacity of insulin to rapidly break the deleterious effects of this cycle on soluble Aβ concentrations and memory has important therapeutic implications.
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Affiliation(s)
- Milene Vandal
- Faculté de Pharmacie, Université Laval, Québec, Canada Axe Neurosciences, Centre de Recherche du Centre Hospitalier de l'Université Laval, Québec, Canada Institut des Nutraceutiques et des Aliments Fonctionnels, Université Laval, Québec, Canada
| | - Phillip J White
- Institut des Nutraceutiques et des Aliments Fonctionnels, Université Laval, Québec, Canada Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology Institute, Durham, NC Département de Medicine, Axe de Cardiologie, Faculté de Médicine de l'Université Laval, Québec, Canada Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Cyntia Tremblay
- Axe Neurosciences, Centre de Recherche du Centre Hospitalier de l'Université Laval, Québec, Canada
| | - Isabelle St-Amour
- Faculté de Pharmacie, Université Laval, Québec, Canada Axe Neurosciences, Centre de Recherche du Centre Hospitalier de l'Université Laval, Québec, Canada Département de Recherche et Développement, Héma-Québec, Québec, Canada
| | - Geneviève Chevrier
- Institut des Nutraceutiques et des Aliments Fonctionnels, Université Laval, Québec, Canada Département de Medicine, Axe de Cardiologie, Faculté de Médicine de l'Université Laval, Québec, Canada
| | - Vincent Emond
- Axe Neurosciences, Centre de Recherche du Centre Hospitalier de l'Université Laval, Québec, Canada
| | | | | | - Emmanuel Planel
- Axe Neurosciences, Centre de Recherche du Centre Hospitalier de l'Université Laval, Québec, Canada
| | - Yves Giguere
- Faculté de Médicine, Université Laval, Québec, Canada Centre de Recherche du Centre Hospitalier de l'Université de Québec, Hôpital Saint-François d'Assise, Québec, Canada
| | - Andre Marette
- Institut des Nutraceutiques et des Aliments Fonctionnels, Université Laval, Québec, Canada Département de Medicine, Axe de Cardiologie, Faculté de Médicine de l'Université Laval, Québec, Canada Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Frederic Calon
- Faculté de Pharmacie, Université Laval, Québec, Canada Axe Neurosciences, Centre de Recherche du Centre Hospitalier de l'Université Laval, Québec, Canada Institut des Nutraceutiques et des Aliments Fonctionnels, Université Laval, Québec, Canada
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103
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Guo X, Tang P, Liu P, Liu Y, Hou C, Li R. Meta-analysis of the association between two neprilysin gene polymorphisms and Alzheimer's disease. J Neurol Sci 2014; 346:6-10. [DOI: 10.1016/j.jns.2014.07.064] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 07/23/2014] [Accepted: 07/29/2014] [Indexed: 01/31/2023]
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104
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Philibert KD, Marr RA, Norstrom EM, Glucksman MJ. Identification and characterization of Aβ peptide interactors in Alzheimer's disease by structural approaches. Front Aging Neurosci 2014; 6:265. [PMID: 25346686 PMCID: PMC4191344 DOI: 10.3389/fnagi.2014.00265] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/12/2014] [Indexed: 01/11/2023] Open
Abstract
Currently, there are very limited pharmaceutical interventions for Alzheimer's disease (AD) to alleviate the amyloid burden implicated in the pathophysiology of the disease. Alzheimer's disease is characterized immunohistologically by the accumulation of senile plaques in the brain with afflicted patients progressively losing short-term memory and, ultimately, cognition. Although significant improvements in clinical diagnosis and care for AD patients have been made, effective treatments for this devastating disease remain elusive. A key component of the amyloid burden of AD comes from accumulation of the amyloid-beta (Aβ) peptide which comes from processing of the amyloid precursor protein (APP) by enzymes termed secretases, leading to production of these toxic Aβ peptides of 40-42 amino acids. New therapeutic approaches for reducing Aβ are warranted after the most logical avenues of inhibiting secretase activity appear less than optimal in ameliorating the progression of AD.Novel therapeutics may be gleaned from proteomics biomarker initiatives to yield detailed molecular interactions of enzymes and their potential substrates. Explicating the APPome by deciphering protein complexes forming in cells is a complementary approach to unveil novel molecular interactions with the amyloidogenic peptide precursor to both understand the biology and develop potential upstream drug targets. Utilizing these strategies we have identified EC 3.4.24.15 (EP24.15), a zinc metalloprotease related to neprilysin (NEP), with the ability to catabolize Aβ 1-42 by examining first potential in silico docking and then verification by mass spectrometry. In addition, a hormone carrier protein, transthyreitin (TTR), was identified and with its abundance in cerebrospinal fluid (CSF), found to clear Aβ by inhibiting formation of oligomeric forms of Aβ peptide. The confluence of complementary strategies may allow new therapeutic avenues as well as biomarkers for AD that will aid in diagnosis, prognosis and treatment.
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Affiliation(s)
- Keith D Philibert
- Department of Biochemistry and Molecular Biology, Chicago Medical School, Rosalind Franklin University of Medicine and Science North Chicago, IL, USA
| | - Robert A Marr
- Department of Neuroscience, Chicago Medical School, Rosalind Franklin University of Medicine and Science North Chicago, IL, USA
| | - Eric M Norstrom
- Department of Biological Sciences, DePaul University Chicago, IL, USA
| | - Marc J Glucksman
- Department of Biochemistry and Molecular Biology, Chicago Medical School, Rosalind Franklin University of Medicine and Science North Chicago, IL, USA
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105
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Nalivaeva NN, Belyaev ND, Kerridge C, Turner AJ. Amyloid-clearing proteins and their epigenetic regulation as a therapeutic target in Alzheimer's disease. Front Aging Neurosci 2014; 6:235. [PMID: 25278875 PMCID: PMC4166351 DOI: 10.3389/fnagi.2014.00235] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 08/18/2014] [Indexed: 12/21/2022] Open
Abstract
Abnormal elevation of amyloid β-peptide (Aβ) levels in the brain is the primary trigger for neuronal cell death specific to Alzheimer’s disease (AD). It is now evident that Aβ levels in the brain are manipulable due to a dynamic equilibrium between its production from the amyloid precursor protein (APP) and removal by amyloid clearance proteins. Clearance can be either enzymic or non-enzymic (binding/transport proteins). Intriguingly several of the main amyloid-degrading enzymes (ADEs) are members of the M13 peptidase family (neprilysin (NEP), NEP2 and the endothelin converting enzymes (ECE-1 and -2)). A distinct metallopeptidase, insulin-degrading enzyme (IDE), also contributes to Aβ degradation in the brain. The ADE family currently embraces more than 20 members, both membrane-bound and soluble, and of differing cellular locations. NEP plays an important role in brain function terminating neuropeptide signals. Its decrease in specific brain areas with age or after hypoxia, ischaemia or stroke contribute significantly to the development of AD pathology. The recently discovered mechanism of epigenetic regulation of NEP (and other genes) by the APP intracellular domain (AICD) and its dependence on the cell type and APP isoform expression suggest possibilities for selective manipulation of NEP gene expression in neuronal cells. We have also observed that another amyloid-clearing protein, namely transthyretin (TTR), is also regulated in the neuronal cell by a mechanism similar to NEP. Dependence of amyloid clearance proteins on histone deacetylases and the ability of HDAC inhibitors to up-regulate their expression in the brain opens new avenues for developing preventive strategies in AD.
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Affiliation(s)
- Natalia N Nalivaeva
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds Leed, UK ; I.M.Sechenov Institute of Evolutionary Physiology and Biochemistry St. Petersburg, Russia
| | - Nikolai D Belyaev
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds Leed, UK
| | - Caroline Kerridge
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds Leed, UK ; Neurodegeneration DHT, Lilly, Erl Wood Manor Windlesham, Surrey, UK
| | - Anthony J Turner
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds Leed, UK
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106
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Marr RA, Hafez DM. Amyloid-beta and Alzheimer's disease: the role of neprilysin-2 in amyloid-beta clearance. Front Aging Neurosci 2014; 6:187. [PMID: 25165447 PMCID: PMC4131500 DOI: 10.3389/fnagi.2014.00187] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 07/09/2014] [Indexed: 12/14/2022] Open
Abstract
Accumulation of the amyloid-beta (Aβ) peptide is a central factor in Alzheimer's disease (AD) pathogenesis as supported by continuing evidence. This review concisely summarizes this evidence supporting a critical role for Aβ in AD before discussing the clearance of this peptide. Mechanisms of clearance of Aβ are critical for preventing pathological elevations in Aβ concentration. Direct degradation of Aβ by endopeptidases has emerged as one important pathway for clearance. Of particular interest are endopeptidases that are sensitive to the neprilysin (NEP) inhibitors thiorphan and phosphoramidon (i.e., are "NEP-like") as these inhibitors induce a dramatic increase in Aβ levels in rodents. This review will focus on neprilysin-2 (NEP2), a NEP-like endopeptidase which cooperates with NEP to control Aβ levels in the brain. The evidence for the involvement of NEP2 in AD is discussed as well as the therapeutic relevance with regards to gene therapy and the development of molecular markers for the disease.
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Affiliation(s)
- Robert A Marr
- Department of Neuroscience, Rosalind Franklin University of Medicine and Science North Chicago, IL, USA
| | - Daniel M Hafez
- Department of Neuroscience, Rosalind Franklin University of Medicine and Science North Chicago, IL, USA
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107
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Yoon SS, Jo SA. Mechanisms of Amyloid-β Peptide Clearance: Potential Therapeutic Targets for Alzheimer's Disease. Biomol Ther (Seoul) 2014; 20:245-55. [PMID: 24130920 PMCID: PMC3794520 DOI: 10.4062/biomolther.2012.20.3.245] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 05/01/2012] [Accepted: 05/01/2012] [Indexed: 11/30/2022] Open
Abstract
Amyloid-β peptide (Aβ) is still best known as a molecule to cause Alzheimer’s disease (AD) through accumulation and deposition within the frontal cortex and hippocampus in the brain. Thus, strategies on developing AD drugs have been focused on the reduc-tion of Aβ in the brain. Since accumulation of Aβ depends on the rate of its synthesis and clearance, the metabolic pathway of Aβ in the brain and the whole body should be carefully explored for AD research. Although the synthetic pathway of Aβ is equally important, we summarize primarily the clearance pathway in this paper because the former has been extensively reviewed in previous studies. The clearance of Aβ from the brain is accomplished by several mechanisms which include non-enzymatic and enzymatic pathways. Nonenzymatic pathway includes interstitial fluid drainage, uptake by microglial phagocytosis, and transport across the blood vessel walls into the circulation. Multiple Aβ-degrading enzymes (ADE) implicated in the clearance process have been identified, which include neprilysin, insulin-degrading enzyme, matrix metalloproteinase-9, glutamate carboxypeptidase II and others. A series of studies on Aβ clearance mechanism provide new insight into the pathogenesis of AD at the molecular level and suggest a new target for the development of novel therapeutics.
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Affiliation(s)
- Sang-Sun Yoon
- Department of Pharmacy, College of Pharmacy, Dankook University, Cheonan 330-714, Republic of Korea
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108
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Simulated Interactions between Endothelin Converting Enzyme and Aβ Peptide: Insights into Subsite Recognition and Cleavage Mechanism. Int J Pept Res Ther 2014. [DOI: 10.1007/s10989-014-9403-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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109
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Kerridge C, Belyaev ND, Nalivaeva NN, Turner AJ. The Aβ-clearance protein transthyretin, like neprilysin, is epigenetically regulated by the amyloid precursor protein intracellular domain. J Neurochem 2014; 130:419-31. [PMID: 24528201 DOI: 10.1111/jnc.12680] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 01/23/2014] [Accepted: 02/03/2014] [Indexed: 12/20/2022]
Abstract
Proteolytic cleavage of the amyloid precursor protein (APP) by the successive actions of β- and γ-secretases generates several biologically active metabolites including the amyloid β-peptide (Aβ) and the APP intracellular domain (AICD). By analogy with the Notch signalling pathway, AICD has been proposed to play a role in transcriptional regulation. Among the cohort of genes regulated by AICD is the Aβ-degrading enzyme neprilysin (NEP). AICD binds to the NEP promoter causing transcriptional activation by competitive replacement with histone deacetylases (HDACs) leading to increased levels of NEP activity and hence increased Aβ clearance. We now show that the Aβ-clearance protein transthyretin (TTR) is also epigenetically up-regulated by AICD. Like NEP regulation, AICD derived specifically from the neuronal APP isoform, APP695 , binds directly to the TTR promoter displacing HDAC1 and HDAC3. Cell treatment with the tyrosine kinase inhibitor Gleevec (imatinib) or with the alkalizing agent NH4 Cl causes an accumulation of 'functional' AICD capable of up-regulating both TTR and NEP, leading to a reduction in total cellular Aβ levels. Pharmacological regulation of both NEP and TTR might represent a viable therapeutic target in Alzheimer's disease.
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Affiliation(s)
- Caroline Kerridge
- School of Molecular & Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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110
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Sodhi RK, Singh N. Retinoids as potential targets for Alzheimer's disease. Pharmacol Biochem Behav 2014; 120:117-23. [PMID: 24582848 DOI: 10.1016/j.pbb.2014.02.016] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 02/17/2014] [Accepted: 02/20/2014] [Indexed: 10/25/2022]
Abstract
Vitamin A and its derivatives, the retinoids, modulate several physiological and pathological processes through their interactions with nuclear retinoid receptor proteins termed as retinoic acid receptors (RARs) and retinoid X receptors (RXRs). An increasing body of evidence signifies the existence of retinoid signaling in diverse brain areas including cortex, amygdala, hypothalamus, hippocampus, and striatum suggesting its involvement in adult brain functions. Defective retinoid signaling has been evidenced in the pathology of Alzheimer's disease. Reports demonstrate that vitamin A deprived mice exhibit serious defects in spatial learning and memory signifying its importance in the maintenance of memory functions. Retinoid signaling impacts the development of AD pathology through multiple pathways. Ligand activation of RAR and RXR in APP/PS1 transgenic mice ameliorated the symptoms of AD and reduced amyloid accumulation and tau hyperphosphorylation. Retinoids also reduce the production of pro-inflammatory cytokines and chemokines by astrocytes and the microglia. Studies also suggest that neuronal cell lines treated with retinoid agonists exhibit an up-regulation in the expression and activity of choline acetyltransferase (ChAT). Reports depict that retinoic acid isomers enhance, the expression of genes linked with cholesterol efflux e.g. apoe, abca-1 and abcg-1 proteins in astrocytes. Furthermore numerous studies also indicate antioxidant potential of retinoids. Through this review we concisely summarize the biology of retinoids, emphasizing on their probable neuroprotective mechanisms that will help to elucidate the pivotal role of these receptors in AD pathology.
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Affiliation(s)
- Rupinder K Sodhi
- Pharmacology Division, Department of Pharmaceutical Sciences and Drug Research, Faculty of Medicine, Punjabi University, Patiala, 147002 Punjab, India
| | - Nirmal Singh
- Pharmacology Division, Department of Pharmaceutical Sciences and Drug Research, Faculty of Medicine, Punjabi University, Patiala, 147002 Punjab, India.
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111
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Kuruppu S, Rajapakse NW, Minond D, Smith AI. Production of soluble Neprilysin by endothelial cells. Biochem Biophys Res Commun 2014; 446:423-7. [PMID: 24495806 DOI: 10.1016/j.bbrc.2014.01.158] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 01/27/2014] [Indexed: 01/21/2023]
Abstract
A non-membrane bound form of Neprilysin (NEP) with catalytic activity has the potential to cleave substrates throughout the circulation, thus leading to systemic effects of NEP. We used the endothelial cell line Ea.hy926 to identify the possible role of exosomes and A Disintegrin and Metalloprotease 17 (ADAM-17) in the production of non-membrane bound NEP. Using a bradykinin based quenched fluorescent substrate (40 μM) assay, we determined the activity of recombinant human NEP (rhNEP; 12 ng), and NEP in the media of endothelial cells (10% v/v; after 24 h incubation with cells) to be 9.35±0.70 and 6.54±0.41 μmols of substrate cleaved over 3h, respectively. The presence of NEP in the media was also confirmed by Western blotting. At present there are no commercially available inhibitors specific for ADAM-17. We therefore synthesised two inhibitors TPI2155-14 and TPI2155-17, specific for ADAM-17 with IC50 values of 5.36 and 4.32 μM, respectively. Treatment of cells with TPI2155-14 (15 μM) and TPI2155-17 (4.3 μM) resulted in a significant decrease in NEP activity in media (62.37±1.43 and 38.30±4.70, respectively as a % of control; P<0.0001), implicating a possible role for ADAM-17 in NEP release. However, centrifuging media (100,000g for 1 h at 4 °C) removed all NEP activity from the supernatant indicating the likely role of exosomes in the release of NEP. Our data therefore indicated for the first time that NEP is released from endothelial cells via exosomes, and that this process is dependent on ADAM-17.
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Affiliation(s)
- Sanjaya Kuruppu
- Department of Biochemistry & Molecular Biology, Building 77, Monash University, Wellington Rd, Clayton, Vic 3800, Australia.
| | - Niwanthi W Rajapakse
- Department of Physiology, Building 13F, Monash University, Wellington Rd, Clayton, Vic 3800, Australia
| | - Dmitriy Minond
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port Saint Lucie, FL 34987, USA
| | - A Ian Smith
- Department of Biochemistry & Molecular Biology, Building 77, Monash University, Wellington Rd, Clayton, Vic 3800, Australia
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112
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The clearance of misfolded proteins in neurodegenerative diseases by zinc metalloproteases: An inorganic perspective. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2013.10.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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113
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Caillava C, Ranaldi S, Lauritzen I, Bauer C, Fareh J, Abraham JD, Checler F. Study on Aβ34 biology and detection in transgenic mice brains. Neurobiol Aging 2014; 35:1570-81. [PMID: 24495834 DOI: 10.1016/j.neurobiolaging.2014.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 01/02/2014] [Accepted: 01/08/2014] [Indexed: 11/28/2022]
Abstract
The β-amyloid precursor protein undergoes cleavages by β- and γ-secretasses yielding amyloid-β peptides (Aβ) that accumulate in Alzheimer's disease. Subsequently, Aβ peptides are targets of additional truncations or endoproteolytic cleavages explaining the diversity of Aβ-related fragments recovered in cell media or pathologic human fluids. Here, we focused on Aβ1-34 (Aβ34) that has been detected both in vitro and in vivo and that derives from the hydrolysis of Aβ by β-secretase. We have obtained and fully characterized by immunologic and biochemical approaches, a polyclonal antibody that specifically recognizes the C-terminus of Aβx-34. We present immunohistochemical evidence for the presence of Aβx-34 in the brain of 3xTg mice and Alzheimer's disease-affected human brains. Finally, we demonstrate a neprilysin-mediated degradation process of Aβ34 and the ability of synthetic Aβ34 to protect HEK cells overexpressing either wild type or Swedish-mutated β-amyloid precursor protein from apoptosis.
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Affiliation(s)
- Céline Caillava
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275 CNRS/UNS, Team "Fondation pour la Recherche Médicale" and "Labex Distalz", Valbonne, France
| | | | - Inger Lauritzen
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275 CNRS/UNS, Team "Fondation pour la Recherche Médicale" and "Labex Distalz", Valbonne, France
| | - Charlotte Bauer
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275 CNRS/UNS, Team "Fondation pour la Recherche Médicale" and "Labex Distalz", Valbonne, France
| | - Jeannette Fareh
- SysDiag CNRS-Bio-Rad, UMR3145, SysDiag,, Montpellier, France
| | | | - Frédéric Checler
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275 CNRS/UNS, Team "Fondation pour la Recherche Médicale" and "Labex Distalz", Valbonne, France.
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114
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Li B, Yu D, Xu Z. Activated protein C inhibits amyloid β production via promoting expression of ADAM-10. Brain Res 2014; 1545:35-44. [DOI: 10.1016/j.brainres.2013.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 11/11/2013] [Accepted: 12/04/2013] [Indexed: 10/25/2022]
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115
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Henderson SJ, Andersson C, Narwal R, Janson J, Goldschmidt TJ, Appelkvist P, Bogstedt A, Steffen AC, Haupts U, Tebbe J, Freskgård PO, Jermutus L, Burrell M, Fowler SB, Webster CI. Sustained peripheral depletion of amyloid-β with a novel form of neprilysin does not affect central levels of amyloid-β. ACTA ACUST UNITED AC 2013; 137:553-64. [PMID: 24259408 PMCID: PMC3914468 DOI: 10.1093/brain/awt308] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lowering levels of peripheral amyloid-β has been proposed as a strategy to reduce plaques in patients with Alzheimer’s disease. Henderson et al. test a modified version of the amyloid-degrading enzyme neprilysin in rats, monkeys and Tg2576 mice. Levels of amyloid-β were reduced in the bloodstream, but not in the CNS. Alzheimer’s disease is characterized by the accumulation of amyloid deposits in the brain and the progressive loss of cognitive functions. Although the precise role of amyloid-β in disease progression remains somewhat controversial, many efforts to halt or reverse disease progression have focussed on reducing its synthesis or enhancing its removal. It is believed that brain and peripheral soluble amyloid-β are in equilibrium and it has previously been hypothesized that a reduction in peripheral amyloid-β can lower brain amyloid-β, thereby reducing formation of plaques predominantly composed of insoluble amyloid-β; the so-called peripheral sink hypothesis. Here we describe the use of an amyloid-β degrading enzyme, the endogenous metallopeptidase neprilysin, which is fused to albumin to extend plasma half-life and has been engineered to confer increased amyloid-β degradation activity. We used this molecule to investigate the effect of degradation of peripheral amyloid-β on amyloid-β levels in the brain and cerebrospinal fluid after repeated intravenous dosing for up to 4 months in Tg2576 transgenic mice, and 1 month in rats and monkeys. This molecule proved highly effective at degradation of amyloid-β in the periphery but did not alter brain or cerebrospinal fluid amyloid-β levels, suggesting that the peripheral sink hypothesis is not valid and is the first time that this has been demonstrated in non-human primates.
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Affiliation(s)
- Simon J Henderson
- 1 MedImmune, Milstein Building, Granta Park, Cambridge, CB21 6GH, UK
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116
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Walter J, van Echten-Deckert G. Cross-talk of membrane lipids and Alzheimer-related proteins. Mol Neurodegener 2013; 8:34. [PMID: 24148205 PMCID: PMC4016522 DOI: 10.1186/1750-1326-8-34] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 09/25/2013] [Indexed: 12/18/2022] Open
Abstract
Alzheimer’s disease (AD) is neuropathologically characterized by the combined occurrence of extracellular β-amyloid plaques and intracellular neurofibrillary tangles in the brain. While plaques contain aggregated forms of the amyloid β-peptide (Aβ), tangles are formed by fibrillar forms of the microtubule associated protein tau. All mutations identified so far to cause familial forms of early onset AD (FAD) are localized close to or within the Aβ domain of the amyloid precursor protein (APP) or in the presenilin proteins that are essential components of a protease complex involved in the generation of Aβ. Mutations in the tau gene are not associated with FAD, but can cause other forms of dementia. The genetics of FAD together with biochemical and cell biological data, led to the formulation of the amyloid hypothesis, stating that accumulation and aggregation of Aβ is the primary event in the pathogenesis of AD, while tau might mediate its toxicity and neurodegeneration. The generation of Aβ involves sequential proteolytic cleavages of the amyloid precursor protein (APP) by enzymes called β-and γ-secretases. Notably, APP itself as well as the secretases are integral membrane proteins. Thus, it is very likely that membrane lipids are involved in the regulation of subcellular transport, activity, and metabolism of AD related proteins. Indeed, several studies indicate that membrane lipids, including cholesterol and sphingolipids (SLs) affect Aβ generation and aggregation. Interestingly, APP and other AD associated proteins, including β-and γ-secretases can, in turn, influence lipid metabolic pathways. Here, we review the close connection of cellular lipid metabolism and AD associated proteins and discuss potential mechanisms that could contribute to initiation and progression of AD.
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Affiliation(s)
- Jochen Walter
- Department of Neurology, University of Bonn, Sigmund-Freud-Str, 25, 53127, Bonn, Germany.
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McGeer PL, McGeer EG. The amyloid cascade-inflammatory hypothesis of Alzheimer disease: implications for therapy. Acta Neuropathol 2013; 126:479-97. [PMID: 24052108 DOI: 10.1007/s00401-013-1177-7] [Citation(s) in RCA: 300] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 09/03/2013] [Accepted: 09/05/2013] [Indexed: 12/14/2022]
Abstract
The amyloid cascade hypothesis is widely accepted as the centerpiece of Alzheimer disease (AD) pathogenesis. It proposes that abnormal production of beta amyloid protein (Abeta) is the cause of AD and that the neurotoxicity is due to Abeta itself or its oligomeric forms. We suggest that this, in itself, cannot be the cause of AD because demonstrating such toxicity requires micromolar concentrations of these Abeta forms, while their levels in brain are a million times lower in the picomolar range. AD probably results from the inflammatory response induced by extracellular Abeta deposits, which later become enhanced by aggregates of tau. The inflammatory response, which is driven by activated microglia, increases over time as the disease progresses. Disease-modifying therapeutic attempts to date have failed and may continue to do so as long as the central role of inflammation is not taken into account. Multiple epidemiological and animal model studies show that NSAIDs, the most widely used antiinflammatory agents, have a substantial sparing effect on AD. These studies provide a proof of concept regarding the anti-inflammatory approach to disease modification. Biomarker studies have indicated that early intervention may be necessary. They have established that disease onset occurs more than a decade before it becomes clinically evident. By combining biomarker and pathological data, it is possible to define six phases of disease development, each separated by about 5 years. Phase one can be identified by decreases in Abeta in the CSF, phase 2 by increases of tau in the CSF plus clear evidence of Abeta brain deposits by PET scanning, phase 3 by slight decreases in brain metabolic rate by PET-FDG scanning, phase 4 by slight decreases in brain volume by MRI scanning plus minimal cognitive impairment, phase 5 by increased scanning abnormalities plus clinical diagnosis of AD, and phase 6 by advanced AD requiring institutional care. Utilization of antiinflammatory agents early in the disease process remains an overlooked therapeutic opportunity. Such agents, while not preventative, have the advantage of being able to inhibit the consequences of both Abeta and tau aggregation. Since there is more than a decade between disease onset and cognitive decline, a window of opportunity exists to introduce truly effective disease-modifying regimens. Taking advantage of this opportunity is the challenge for the future.
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Affiliation(s)
- Patrick L McGeer
- Kinsmen Laboratory of Neurological Research, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, V6T1Z3, Canada,
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Sarasa L, Allué JA, Pesini P, González-Martínez Á, Sarasa M. Identification of β-amyloid species in canine cerebrospinal fluid by mass spectrometry. Neurobiol Aging 2013; 34:2125-32. [DOI: 10.1016/j.neurobiolaging.2013.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 02/12/2013] [Accepted: 03/11/2013] [Indexed: 01/20/2023]
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Leissring MA, Turner AJ. Regulation of distinct pools of amyloid β-protein by multiple cellular proteases. ALZHEIMERS RESEARCH & THERAPY 2013; 5:37. [PMID: 23953275 PMCID: PMC3978621 DOI: 10.1186/alzrt194] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Alzheimer’s disease (AD) is a progressive, age-related neurodegenerative disorder characterized by extracellular and intracellular deposition of the amyloid β-protein (Aβ). The study of rare, familial forms of AD has shown that sustained elevations in the production of Aβ (either all forms or specific pathogenic variants thereof) are sufficient to trigger the full spectrum of cognitive and histopathological features of the disease. Although the exact cause or causes remain unknown, emerging evidence suggests that impairments in the clearance of Aβ, after it is produced, may underlie the vast majority of sporadic AD cases. This review focuses on Aβ-degrading proteases (AβDPs), which have emerged as particularly important mediators of Aβ clearance. A wide variety of proteases that – by virtue of their particular regional and subcellular localization profiles – define distinct pools of Aβ have been identified. Different pools of Aβ, in turn, may contribute differentially to the pathogenesis of the disease. The study of individual AβDPs, therefore, promises to offer new insights into the mechanistic basis of AD pathogenesis and, ultimately, may facilitate the development of effective methods for its prevention or treatment or both.
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Affiliation(s)
- Malcolm A Leissring
- Department of Neuroscience, Mayo Clinic, Birdsall Building, Room 117, Jacksonville, FL 32224, USA
| | - Anthony J Turner
- School of Molecular & Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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Crane PK, Walker R, Hubbard RA, Li G, Nathan DM, Zheng H, Haneuse S, Craft S, Montine TJ, Kahn SE, McCormick W, McCurry SM, Bowen JD, Larson EB. Glucose levels and risk of dementia. N Engl J Med 2013; 369:540-8. [PMID: 23924004 PMCID: PMC3955123 DOI: 10.1056/nejmoa1215740] [Citation(s) in RCA: 591] [Impact Index Per Article: 53.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Diabetes is a risk factor for dementia. It is unknown whether higher glucose levels increase the risk of dementia in people without diabetes. METHODS We used 35,264 clinical measurements of glucose levels and 10,208 measurements of glycated hemoglobin levels from 2067 participants without dementia to examine the relationship between glucose levels and the risk of dementia. Participants were from the Adult Changes in Thought study and included 839 men and 1228 women whose mean age at baseline was 76 years; 232 participants had diabetes, and 1835 did not. We fit Cox regression models, stratified according to diabetes status and adjusted for age, sex, study cohort, educational level, level of exercise, blood pressure, and status with respect to coronary and cerebrovascular diseases, atrial fibrillation, smoking, and treatment for hypertension. RESULTS During a median follow-up of 6.8 years, dementia developed in 524 participants (74 with diabetes and 450 without). Among participants without diabetes, higher average glucose levels within the preceding 5 years were related to an increased risk of dementia (P=0.01); with a glucose level of 115 mg per deciliter (6.4 mmol per liter) as compared with 100 mg per deciliter (5.5 mmol per liter), the adjusted hazard ratio for dementia was 1.18 (95% confidence interval [CI], 1.04 to 1.33). Among participants with diabetes, higher average glucose levels were also related to an increased risk of dementia (P=0.002); with a glucose level of 190 mg per deciliter (10.5 mmol per liter) as compared with 160 mg per deciliter (8.9 mmol per liter), the adjusted hazard ratio was 1.40 (95% CI, 1.12 to 1.76). CONCLUSIONS Our results suggest that higher glucose levels may be a risk factor for dementia, even among persons without diabetes. (Funded by the National Institutes of Health.)
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Affiliation(s)
- Paul K Crane
- Department of Medicine, University of Washington, Seattle, WA, USA.
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Anand R, Gill KD, Mahdi AA. Therapeutics of Alzheimer's disease: Past, present and future. Neuropharmacology 2013; 76 Pt A:27-50. [PMID: 23891641 DOI: 10.1016/j.neuropharm.2013.07.004] [Citation(s) in RCA: 500] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 06/26/2013] [Accepted: 07/02/2013] [Indexed: 12/15/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia worldwide. The etiology is multifactorial, and pathophysiology of the disease is complex. Data indicate an exponential rise in the number of cases of AD, emphasizing the need for developing an effective treatment. AD also imposes tremendous emotional and financial burden to the patient's family and community. The disease has been studied over a century, but acetylcholinesterase inhibitors and memantine are the only drugs currently approved for its management. These drugs provide symptomatic improvement alone but do less to modify the disease process. The extensive insight into the molecular and cellular pathomechanism in AD over the past few decades has provided us significant progress in the understanding of the disease. A number of novel strategies that seek to modify the disease process have been developed. The major developments in this direction are the amyloid and tau based therapeutics, which could hold the key to treatment of AD in the near future. Several putative drugs have been thoroughly investigated in preclinical studies, but many of them have failed to produce results in the clinical scenario; therefore it is only prudent that lessons be learnt from the past mistakes. The current rationales and targets evaluated for therapeutic benefit in AD are reviewed in this article. This article is part of the Special Issue entitled 'The Synaptic Basis of Neurodegenerative Disorders'.
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Affiliation(s)
- R Anand
- Department of Biochemistry, Christian Medical College, Vellore 632002, Tamilnadu, India.
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Hippocampal gene expression meta-analysis identifies aging and age-associated spatial learning impairment (ASLI) genes and pathways. PLoS One 2013; 8:e69768. [PMID: 23874995 PMCID: PMC3715497 DOI: 10.1371/journal.pone.0069768] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 06/14/2013] [Indexed: 11/19/2022] Open
Abstract
A number of gene expression microarray studies have been carried out in the past, which studied aging and age-associated spatial learning impairment (ASLI) in the hippocampus in animal models, with varying results. Data from such studies were never integrated to identify the most significant ASLI genes and to understand their effect. In this study we integrated these data involving rats using meta-analysis. Our results show that proper removal of batch effects from microarray data generated from different laboratories is necessary before integrating them for meta-analysis. Our meta-analysis has identified a number of significant differentially expressed genes across age or across ASLI. These genes affect many key functions in the aged compared to the young rats, which include viability of neurons, cell-to-cell signalling and interaction, migration of cells, neuronal growth, and synaptic plasticity. These functional changes due to the altered gene expression may manifest into various neurodegenerative diseases and disorders, some of which leading into syndromic memory impairments. While other aging related molecular changes can result into altered synaptic plasticity simply causing normal aging related non-syndromic learning or spatial learning impairments such as ASLI.
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Somatostatin receptor subtype-4 agonist NNC 26-9100 mitigates the effect of soluble Aβ(42) oligomers via a metalloproteinase-dependent mechanism. Brain Res 2013; 1520:145-56. [PMID: 23669069 DOI: 10.1016/j.brainres.2013.05.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 05/01/2013] [Accepted: 05/04/2013] [Indexed: 02/07/2023]
Abstract
Soluble amyloid-β peptide (Aβ) oligomers have been hypothesized to be primary mediators of Alzheimer's disease progression. In this regard, reduction of soluble Aβ-oligomers levels within the brain may provide a viable means in which to treat the disease. Somatostatin receptor subtype-4 (SSTR4) agonists have been proposed to reduce Aβ levels in the brain via enhancement of enzymatic degradation. Herein we evaluated the effect of selective SSTR4 agonist NNC 26-9100 on the changes in learning and soluble Aβ42 oligomer brain content with and without co-administration of the M13-metalloproteinase family enzyme-inhibitor phosphoramidon, using the senescence-accelerated mouse prone-8 (SAMP8) model. NNC 26-9100 treatment (0.2 µg i.c.v. in 2 µL) improved learning, which was blocked by phosphoramidon (1 and 10mM, respectively). NNC 26-9100 decreased total soluble Aβ42, an effect which was blocked by phosphoramidon (10mM). Extracellular, intracellular, and membrane fractions were then isolated from cortical tissue and assessed for soluble oligomer alterations. NNC 26-9100 decreased the Aβ42 trimeric (12 kDa) form within the extracellular and intracellular fractions, and produced a band-split effect of the Aβ42 hexameric (25 kDa) form within the extracellular fraction. These effects were also blocked by phosphoramdon (1 and 10mM, respectively). Subsequent evaluation of NNC 26-9100 in APPswe Tg2576 transgenic mice showed a similar learning improvement and corresponding reduction in soluble Aβ42 oligomers within extracellular, intracellular, and membrane fractions. These data support the hypothesis that NNC 26-9100 reduces soluble Aβ42 oligomers and enhances learning through a phosphoramidon-sensitive metalloproteinase-dependent mechanism.
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Octave JN, Pierrot N, Ferao Santos S, Nalivaeva NN, Turner AJ. From synaptic spines to nuclear signaling: nuclear and synaptic actions of the amyloid precursor protein. J Neurochem 2013; 126:183-90. [DOI: 10.1111/jnc.12239] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Revised: 02/25/2013] [Accepted: 02/26/2013] [Indexed: 10/27/2022]
Affiliation(s)
- Jean-Noël Octave
- Université Catholique de Louvain; Institute of Neuroscience (IoNS); Brussels Belgium
| | - Nathalie Pierrot
- Université Catholique de Louvain; Institute of Neuroscience (IoNS); Brussels Belgium
| | - Susana Ferao Santos
- Université Catholique de Louvain; Institute of Neuroscience (IoNS); Brussels Belgium
| | - Natalia N. Nalivaeva
- School of Molecular and Cellular Biology; Faculty of Biological Sciences; University of Leeds; Leeds UK
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry; RAS; St. Petersburg Russia
| | - Anthony J. Turner
- School of Molecular and Cellular Biology; Faculty of Biological Sciences; University of Leeds; Leeds UK
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Shinohara M, Petersen RC, Dickson DW, Bu G. Brain regional correlation of amyloid-β with synapses and apolipoprotein E in non-demented individuals: potential mechanisms underlying regional vulnerability to amyloid-β accumulation. Acta Neuropathol 2013; 125:535-47. [PMID: 23371365 DOI: 10.1007/s00401-013-1086-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/15/2013] [Accepted: 01/20/2013] [Indexed: 12/12/2022]
Abstract
To reveal the underlying mechanisms responsible for the regional vulnerability to amyloid-β (Aβ) accumulation prior to the development of Alzheimer's disease, we studied distribution of Aβ, apolipoprotein E (apoE), synaptic markers, and other molecules involved in Aβ metabolism in multiple brain areas of non-demented individuals. Twelve brain regions including neocortical, limbic, and subcortical areas were dissected from brains of non-demented individuals and extracted according to increasing insolubility by a sequential three-step method. The levels of Aβ40, Aβ42, apoE, APP, APP-CTFβ, BACE1, presenilin-1, neprilysin, insulysin, LRP1, LDLR, synaptophysin, PSD95, GFAP, and lactate were determined by ELISAs or enzymatic assays. The regional distribution of apoE showed moderate-to-strong inverse correlation with levels of Aβ, especially insoluble Aβ40. On the other hand, the regional distributions of synaptic markers, particularly PSD95, showed moderate-to-strong positive correlation with levels of Aβ, especially soluble Aβ40. The regional correlations between Aβ and LRP1, GFAP, or lactate were mild-to-moderate. Moderate-to-strong positive regional correlations were observed between apoE and GFAP or lactate and between PSD95 and LRP1. No significant regional correlations were detected between Aβ and APP, APP-CTFβ, BACE1, or presenilin-1, those involved in Aβ production. There were no significant negative regional correlations between Aβ and two major Aβ degrading enzymes, neprilysin and insulysin. These regional correlations remained consistent regardless of the degree of Aβ accumulation. The regional vulnerability to Aβ accumulation may be due to a net balance between two competing processes: (1) synapses involved in promoting the initial Aβ accumulation and (2) astrocyte-derived apoE involved in preventing Aβ accumulation.
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Affiliation(s)
- Mitsuru Shinohara
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA
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Elali A, Rivest S. The role of ABCB1 and ABCA1 in beta-amyloid clearance at the neurovascular unit in Alzheimer's disease. Front Physiol 2013; 4:45. [PMID: 23494712 PMCID: PMC3595512 DOI: 10.3389/fphys.2013.00045] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Accepted: 02/27/2013] [Indexed: 11/13/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects elderly persons, evolving with age to reach severe cognitive impairment. Amyloid deposits and neurofibrillary tangles constitute the main pathological hallmarks of AD. Amyloid deposits are initiated by the excessive production and accumulation of beta-amyloid (Aβ) peptides in the brain. The dysfunction of the Neurovascular Unit (NVU) has been proposed to be causative in AD development, due to an impaired clearance of Aβ from the brain. Cells forming the NVU express several Adenosine Triphosphate ATP-Binding Cassette (ABC) transporters, among which ABCB1 and ABCA1 play an important role in Aβ processing. The drug transporter ABCB1 directly transports Aβ from the brain into the blood circulation, whereas the cholesterol transporter ABCA1 neutralizes Aβ aggregation capacity in an Apolipoprotein E (ApoE)-dependent manner, facilitating Aβ subsequent elimination from the brain. In the present minireview, we will summarize the contribution of ABCB1, and ABCA1 at the NVU in Aβ clearance. Moreover, we will outline and discuss the possible collaboration of ABCB1, and ABCA1 at the NVU in mediating an efficient clearance of Aβ from the brain.
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Affiliation(s)
- Ayman Elali
- Laboratory of Neurosciences, Department of Molecular Medicine, Faculty of Medicine, CHU de Québec Research Center, Laval University Québec, QC, Canada
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127
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Goncalves MB, Clarke E, Hobbs C, Malmqvist T, Deacon R, Jack J, Corcoran JPT. Amyloid β inhibits retinoic acid synthesis exacerbating Alzheimer disease pathology which can be attenuated by an retinoic acid receptor α agonist. Eur J Neurosci 2013; 37:1182-92. [PMID: 23379615 PMCID: PMC3655538 DOI: 10.1111/ejn.12142] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 12/23/2012] [Indexed: 12/03/2022]
Abstract
The retinoic acid receptor (RAR) α system plays a key role in the adult brain, participating in the homeostatic control of synaptic plasticity, essential for memory function. Here we show that RARα signalling is down-regulated by amyloid beta (Aβ), which inhibits the synthesis of the endogenous ligand, retinoic acid (RA). This results in the counteraction of a variety of RARα-activated pathways that are key in the aetiopathology of Alzheimer's disease (AD) but which can be reversed by an RARα agonist. RARα signalling improves cognition in the Tg2576 mice, it has an anti-inflammatory effect and promotes Aβ clearance by increasing insulin degrading enzyme and neprilysin activity in both microglia and neurons. In addition, RARα signalling prevents tau phosphorylation. Therefore, stimulation of the RARα signalling pathway using a synthetic agonist, by both clearing Aβ and counteracting some of its toxic effects, offers therapeutic potential for the treatment of AD.
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Affiliation(s)
- Maria B Goncalves
- The Wolfson Centre For Age-Related Diseases, King's College London, Guy's Campus, London, SE11UL, UK
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Shen YE, Wang Y, Yu GC, Liu C, Zhang ZY, Zhang LM. Effects of edaravone on amyloid-β precursor protein processing in SY5Y-APP695 cells. Neurotox Res 2013; 24:139-47. [PMID: 23325603 DOI: 10.1007/s12640-012-9370-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 12/18/2012] [Accepted: 12/21/2012] [Indexed: 01/09/2023]
Abstract
Previous reports have revealed that reactive oxygen species (ROS) is involved in the development of Alzheimer's disease (AD), and recent studies indicate that free radical-generating systems can regulate amyloid-β precursor protein (APP) processing. Edaravone is a novel free radical scavenger currently used to reduce cerebral damages after acute cerebral infarction. In the present study, we used SH-SY5Y cells stably transfected with the human "Swedish" APP mutation APP695 (SY5Y-APP695swe) as an in vitro model to investigate the effect of edaravone on APP processing. The result showed that edaravone treatment for 24 h down-regulated β-amyloid (Aβ) production in a dose-dependent manner. Moreover, edaravone modulated APP processing by increasing α-secretase-derived APP fragments and decreasing β-secretase-derived APP fragments. In addition, the mRNA and protein levels of insulin degrading enzyme (IDE) and neprilysin (NEP), two key Aβ degrading enzymes, were not changed after edaravone administration. Taken together, our data suggested that edaravone played an important role in regulating Aβ production by enhancing the non-amyloidogenic pathway and inhibiting the amyloidogenic pathway. Thus, edaravone may be potentially useful for treating Alzheimer's disease (AD).
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Affiliation(s)
- Yue-E Shen
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, 23 You Zheng Steet, Nan Gang District, 150001 Harbin, China
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Park SM, Kim KS. Proteolytic clearance of extracellular α-synuclein as a new therapeutic approach against Parkinson disease. Prion 2012; 7:121-6. [PMID: 23154633 DOI: 10.4161/pri.22850] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Many neurodegenerative diseases such as Alzheimer disease and Parkinson disease show similar characteristics. They typically show deposits of protein aggregates, the formation of which is considered important in their pathogenesis. Recently, aggregation-prone proteins have been shown to spread between cells and so may contribute to the pathogenesis of diseases like prion disease. Such a pathogenesis pathway is possibly common to many neurodegenerative diseases. If confirmed, it could allow the development of therapeutic interventions against many such diseases. In Parkinson disease, α-synuclein, a major component of cytosolic protein inclusions named Lewy body, has been shown to be released and taken up by cells, which may facilitate its progressive pathological spreading between cells. Accordingly, inhibition of spreading by targeting extracellular α-synuclein may represent a new therapy against Parkinson disease. Research into the intercellular spreading of extracellular protein aggregations of α-synuclein and its clearance pathway are reviewed here with a focus on the proteolytic clearance pathway as a therapeutic target for the treatment of Parkinson disease. Considering the similar characteristics of aggregation-prone proteins, these clearance systems might allow treatment of other neurodegenerative diseases beyond Parkinson disease.
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Affiliation(s)
- Sang Myun Park
- Department of Pharmacology, Neuroscience Graduate Program, Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, South Korea.
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131
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Briones TL, Darwish H. Vitamin D mitigates age-related cognitive decline through the modulation of pro-inflammatory state and decrease in amyloid burden. J Neuroinflammation 2012; 9:244. [PMID: 23098125 PMCID: PMC3520725 DOI: 10.1186/1742-2094-9-244] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 10/17/2012] [Indexed: 11/23/2022] Open
Abstract
Background Increasing evidence shows an association between the use of vitamin D and improvement in age-related cognitive decline. In this study, we investigated the possible mechanisms involved in the neuroprotective effects of vitamin D on age-related brain changes and cognitive function. Methods Male F344 rats aged 20 months (old) and 6 months (young) were used and randomly assigned to either vitamin D supplementation or no supplementation (control). A total of n = 39 rats were used in the study. Rats were individually housed and the supplementation group received a subcutaneous injection of vitamin D (1, α25-dihydroxyvitamin D3) 42 I.U./Kg for 21 days. Control animals received equal volume of normal saline. Behavioral testing in water maze and spontaneous object recognition tasks started on day 14. Levels of interleukin (IL)-1β and IL-10 were quantified to assess inflammatory state. Also, beta amyloid (Aβ) clearance and Aβ load were measured. Results Our results show that: (1) aged rats demonstrated significant learning and memory impairment overall compared to younger animals. However, the age-related decline in learning and memory was ameliorated by the supplementation of vitamin D. No vitamin D effect on learning and memory was seen in the young animals; 2) the pro-inflammatory cytokine IL-1β is significantly increased while the anti-inflammatory cytokine IL-10 is significantly decreased in the aged rats compared to the young animals; but this age-related change in inflammatory state was mitigated by vitamin D supplementation. No effects of vitamin D were seen on the IL-1β and IL-10 expression in the young rats; (3) vitamin D increased Aβ clearance and decreased amyloid burden in the aged rats while no significant difference was seen between the young animal groups. Conclusions Our data suggest that vitamin D supplementation modulated age-related increase in pro-inflammatory state and amyloid burden. It is possible that these effects of vitamin D mediated the decrease memory impairment seen in the aged rats making it a useful therapeutic option to alleviate the effects of aging on cognitive function.
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Affiliation(s)
- Teresita L Briones
- Department of Adult Health, Wayne State University, 5557 Cass Ave, Cohn Bldg, Rm 344, Detroit, MI 48202, USA.
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van Echten-Deckert G, Walter J. Sphingolipids: Critical players in Alzheimer’s disease. Prog Lipid Res 2012; 51:378-93. [DOI: 10.1016/j.plipres.2012.07.001] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 07/06/2012] [Indexed: 12/20/2022]
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Abstract
The conventional view of AD (Alzheimer's disease) is that much of the pathology is driven by an increased load of β-amyloid in the brain of AD patients (the 'Amyloid Hypothesis'). Yet, many therapeutic strategies based on lowering β-amyloid have so far failed in clinical trials. This failure of β-amyloid-lowering agents has caused many to question the Amyloid Hypothesis itself. However, AD is likely to be a complex disease driven by multiple factors. In addition, it is increasingly clear that β-amyloid processing involves many enzymes and signalling pathways that play a role in a diverse array of cellular processes. Thus the clinical failure of β-amyloid-lowering agents does not mean that the hypothesis itself is incorrect; it may simply mean that manipulating β-amyloid directly is an unrealistic strategy for therapeutic intervention, given the complex role of β-amyloid in neuronal physiology. Another possible problem may be that toxic β-amyloid levels have already caused irreversible damage to downstream cellular pathways by the time dementia sets in. We argue in the present review that a more direct (and possibly simpler) approach to AD therapeutics is to rescue synaptic dysfunction directly, by focusing on the mechanisms by which elevated levels of β-amyloid disrupt synaptic physiology.
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Affiliation(s)
- Andrew F Teich
- Department of Pathology and Cell Biology, Columbia University Medical Center, 630 West 168th Street, PH15-124, New York, NY 10032, USA.
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134
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Hall D, Edskes H. Computational modeling of the relationship between amyloid and disease. Biophys Rev 2012; 4:205-222. [PMID: 23495357 PMCID: PMC3595053 DOI: 10.1007/s12551-012-0091-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 06/21/2012] [Indexed: 01/29/2023] Open
Abstract
Amyloid is a title conferred upon a special type of linear protein aggregate that exhibits a common set of structural features and dye binding capabilities. The formation of amyloid is associated with over twenty-seven distinct human diseases which are collectively referred to as the amyloidoses. Although there is great diversity amongst the amyloidoses with regard to the polypeptide monomeric precursor, targeted tissues and the nature and time course of disease development, the common underlying link of a structurally similar amyloid aggregate has prompted the search for a unified theory of disease progression in which amyloid production is the central element. Computational modeling has allowed the formulation and testing of scientific hypotheses for exploring this relationship. However, the majority of computational studies on amyloid aggregation are pitched at the atomistic level of description, in simple ideal solution environments, with simulation time scales of the order of microseconds and system sizes limited to a hundred monomers (or less). The experimental reality is that disease related amyloid aggregation processes occur in extremely complex reaction environments (i.e. the human body), over time-scales of months to years with monitoring of the reaction achieved using extremely coarse or indirect experimental markers that yield little or no atomistic insight. Clearly a substantial gap exists between computational and experimental communities with a deficit of 'useful' computational methodology that can be directly related to available markers of disease progression. This Review will place its focus on the development of these latter types of computational models and discuss them in relation to disease onset and progression.
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Affiliation(s)
- Damien Hall
- Institute of Basic Medical Science, University of Tsukuba, Lab 225-B, Building D. 1-1-1 Tennodai, Tsukuba-shi, Ibaraki-ken 305-8577 Japan
| | - Herman Edskes
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830 USA
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Nalivaeva NN, Belyaev ND, Zhuravin IA, Turner AJ. The Alzheimer's amyloid-degrading peptidase, neprilysin: can we control it? Int J Alzheimers Dis 2012; 2012:383796. [PMID: 22900228 PMCID: PMC3412116 DOI: 10.1155/2012/383796] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 06/01/2012] [Indexed: 02/07/2023] Open
Abstract
The amyloid cascade hypothesis of Alzheimer's disease (AD) postulates that accumulation in the brain of amyloid β-peptide (Aβ) is the primary trigger for neuronal loss specific to this pathology. In healthy brain, Aβ levels are regulated by a dynamic equilibrium between Aβ release from the amyloid precursor protein (APP) and its removal by perivascular drainage or by amyloid-degrading enzymes (ADEs). During the last decade, the ADE family was fast growing, and currently it embraces more than 20 members. There are solid data supporting involvement of each of them in Aβ clearance but a zinc metallopeptidase neprilysin (NEP) is considered as a major ADE. NEP plays an important role in brain function due to its role in terminating neuropeptide signalling and its decrease during ageing or after such pathologies as hypoxia or ischemia contribute significantly to the development of AD pathology. The recently discovered mechanism of epigenetic regulation of NEP by the APP intracellular domain (AICD) opens new avenues for its therapeutic manipulation and raises hope for developing preventive strategies in AD. However, consideration needs to be given to the diverse physiological roles of NEP. This paper critically evaluates general biochemical and physiological functions of NEP and their therapeutic relevance.
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Affiliation(s)
- N. N. Nalivaeva
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, RAS, 44 Thorez Avenue, Saint Petersburg 194223, Russia
| | - N. D. Belyaev
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - I. A. Zhuravin
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, RAS, 44 Thorez Avenue, Saint Petersburg 194223, Russia
| | - A. J. Turner
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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Kukday SS, Manandhar SP, Ludley MC, Burriss ME, Alper BJ, Schmidt WK. Cell-permeable, small-molecule activators of the insulin-degrading enzyme. ACTA ACUST UNITED AC 2012; 17:1348-61. [PMID: 22740246 DOI: 10.1177/1087057112451921] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The insulin-degrading enzyme (IDE) cleaves numerous small peptides, including biologically active hormones and disease-related peptides. The propensity of IDE to degrade neurotoxic Aβ peptides marks IDE as a potential therapeutic target for Alzheimer disease. Using a synthetic reporter based on the yeast a-factor mating pheromone precursor, which is cleaved by multiple IDE orthologs, we identified seven small molecules that stimulate rat IDE activity in vitro. Half-maximal activation of IDE by the compounds is observed in vitro in the range of 43 to 198 µM. All compounds decrease the K(m) of IDE. Four compounds activate IDE in the presence of the competing substrate insulin, which disproportionately inhibits IDE activity. Two compounds stimulate rat IDE activity in a cell-based assay, indicating that they are cell permeable. The compounds demonstrate specificity for rat IDE since they do not enhance the activities of IDE orthologs, including human IDE, and they appear specific for a-factor-based reporters since they do not enhance rat IDE-mediated cleavage of Aβ-based reporters. Our results suggest that IDE activators function in the context of specific enzyme-substrate pairs, indicating that the choice of substrate must be considered in addition to target validation in IDE activator screens.
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137
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Grasso G, Giuffrida ML, Rizzarelli E. Metallostasis and amyloid β-degrading enzymes. Metallomics 2012; 4:937-49. [DOI: 10.1039/c2mt20105d] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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