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Mahakud AK, Shaikh J, Rifa Iqbal VV, Gupta A, Tiwari A, Saleem M. Amyloids on Membrane Interfaces: Implications for Neurodegeneration. J Membr Biol 2022; 255:705-722. [PMID: 35670831 DOI: 10.1007/s00232-022-00245-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 05/12/2022] [Indexed: 12/24/2022]
Abstract
Membrane interfaces are vital for various cellular processes, and their involvement in neurodegenerative disorders such as Alzheimer's and Parkinson's disease has taken precedence in recent years. The amyloidogenic proteins associated with neurodegenerative diseases interact with the neuronal membrane through various means, which has implications for both the onset and progression of the disease. The parameters that regulate the interaction between the membrane and the amyloids remain poorly understood. The review focuses on the various aspects of membrane interactions of amyloids, particularly amyloid-β (Aβ) peptides and Tau involved in Alzheimer's and α-synuclein involved in Parkinson's disease. The genetic, cell biological, biochemical, and biophysical studies that form the basis for our current understanding of the membrane interactions of Aβ peptides, Tau, and α-synuclein are discussed.
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Affiliation(s)
- Amaresh Kumar Mahakud
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India.,Homi Bhabha National Institute, Mumbai, India
| | - Jafarulla Shaikh
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India.,Homi Bhabha National Institute, Mumbai, India
| | - V V Rifa Iqbal
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India.,Homi Bhabha National Institute, Mumbai, India
| | - Abhinav Gupta
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India.,Homi Bhabha National Institute, Mumbai, India
| | - Anuj Tiwari
- Department of Life Sciences, National Institute of Technology, Rourkela, India
| | - Mohammed Saleem
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India. .,Homi Bhabha National Institute, Mumbai, India.
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Kawahara M, Kato-Negishi M, Tanaka KI. Amyloids: Regulators of Metal Homeostasis in the Synapse. Molecules 2020; 25:molecules25061441. [PMID: 32210005 PMCID: PMC7145306 DOI: 10.3390/molecules25061441] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/17/2020] [Accepted: 03/20/2020] [Indexed: 12/11/2022] Open
Abstract
Conformational changes in amyloidogenic proteins, such as β-amyloid protein, prion proteins, and α-synuclein, play a critical role in the pathogenesis of numerous neurodegenerative diseases, including Alzheimer’s disease, prion disease, and Lewy body disease. The disease-associated proteins possess several common characteristics, including the ability to form amyloid oligomers with β-pleated sheet structure, as well as cytotoxicity, although they differ in amino acid sequence. Interestingly, these amyloidogenic proteins all possess the ability to bind trace metals, can regulate metal homeostasis, and are co-localized at the synapse, where metals are abundantly present. In this review, we discuss the physiological roles of these amyloidogenic proteins in metal homeostasis, and we propose hypothetical models of their pathogenetic role in the neurodegenerative process as the loss of normal metal regulatory functions of amyloidogenic proteins. Notably, these amyloidogenic proteins have the capacity to form Ca2+-permeable pores in membranes, suggestive of a toxic gain of function. Therefore, we focus on their potential role in the disruption of Ca2+ homeostasis in amyloid-associated neurodegenerative diseases.
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Sureda A, Capó X, Tejada S. Neuroprotective Effects of Flavonoid Compounds on Neuronal Death Associated to Alzheimer’s Disease. Curr Med Chem 2019; 26:5124-5136. [DOI: 10.2174/0929867325666171226103237] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 09/19/2017] [Accepted: 09/19/2017] [Indexed: 01/25/2023]
Abstract
Alzheimer’s disease is an increasing neurodegenerative pathology related to
age in many societies. Some aspects of the disease are related to the loss of neuronal cells
derived by the formation of extracellular neuritic plaques and the appearance of intracellular
neurofibrillary tangles, altogether generating an inflammatory and oxidative status.
The accumulation of amyloids in cells induces the activation of the apoptotic cascade
which implies caspases activation. Alzheimer’s disease is treated with acetylcholine esterase
inhibitors, although their effects are still far away to reduce or eliminate the problems
associated with the pathology. The lack of effective treatment has led to the search
for new therapeutic alternatives based on natural products. Flavonoids comprise a group
of phenolic compounds that have gained great interest since they present great diversity of
biological activities. In the present work, we review the potential uses of flavonoids and
the proposed mechanisms of action as a new therapeutic strategy in neurological cell
death associated with Alzheimer’s disease.
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Affiliation(s)
- Antoni Sureda
- Research Group on Community Nutrition and Oxidative Stress, University of Balearic Islands, E-07122 Palma de Mallorca, Balearic Islands, Spain
| | - Xavier Capó
- Research Group on Community Nutrition and Oxidative Stress, University of Balearic Islands, E-07122 Palma de Mallorca, Balearic Islands, Spain
| | - Silvia Tejada
- CIBEROBN (Physiopathology of Obesity and Nutrition), E- 07122 Palma de Mallorca, Balearic Islands, Spain
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Effect of high fat diet on phenotype, brain transcriptome and lipidome in Alzheimer's model mice. Sci Rep 2017; 7:4307. [PMID: 28655926 PMCID: PMC5487356 DOI: 10.1038/s41598-017-04412-2] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 05/15/2017] [Indexed: 02/01/2023] Open
Abstract
We examined the effect of chronic high fat diet (HFD) on amyloid deposition and cognition of 12-months old APP23 mice, and correlated the phenotype to brain transcriptome and lipidome. HFD significantly increased amyloid plaques and worsened cognitive performance compared to mice on normal diet (ND). RNA-seq results revealed that in HFD mice there was an increased expression of genes related to immune response, such as Trem2 and Tyrobp. We found a significant increase of TREM2 immunoreactivity in the cortex in response to HFD, most pronounced in female mice that correlated to the amyloid pathology. Down-regulated by HFD were genes related to neuron projections and synaptic transmission in agreement to the significantly deteriorated neurite morphology and cognition in these mice. To examine the effect of the diet on the brain lipidome, we performed Shotgun Lipidomics. While there was no difference in the total amounts of phospholipids of each class, we revealed that the levels of 24 lipid sub-species in the brain were significantly modulated by HFD. Network visualization of correlated lipids demonstrated overall imbalance with most prominent effect on cardiolipin molecular sub-species. This integrative approach demonstrates that HFD elicits a complex response at molecular, cellular and system levels in the CNS.
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Villela D, Suemoto CK, Pasqualucci CA, Grinberg LT, Rosenberg C. Do Copy Number Changes in CACNA2D2, CACNA2D3, and CACNA1D Constitute a Predisposing Risk Factor for Alzheimer's Disease? Front Genet 2016; 7:107. [PMID: 27379157 PMCID: PMC4905985 DOI: 10.3389/fgene.2016.00107] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/27/2016] [Indexed: 01/05/2023] Open
Abstract
Dysregulation of calcium (Ca2+) homeostasis is now being recognized to be a key step in the pathogenesis of Alzheimer’s disease (AD). Data from the literature, in particular the association between AD and polymorphism that interfere with Ca2+ homeostasis indicates the presence of genetic factors in this process; further, presenilins mutations, which are known to cause the familial form of AD, are involved in the regulation of intracellular Ca2+ stores. Here, we wish to draw attention to rare DNA copy number variations identified in two subjects with late-onset AD that led to partial or full duplication of genes that encode different subunits of the same type of voltage-gated Ca2+ channels; these duplications of voltage-gated Ca2+ channel genes is consistent with the critical role of calcium signaling in molecular processes underlying memory as has been demonstrated by several studies.
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Affiliation(s)
- Darine Villela
- Human Genome and Stem-Cell Research Center, Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo Brazil
| | - Claudia K Suemoto
- Discipline of Geriatrics, Department of Clinical Medicine, School of Medicine, University of São Paulo, São PauloBrazil; Brazilian Aging Brain Study Group - LIM22, Department of Pathology, School of Medicine, University of São Paulo, São PauloBrazil
| | - Carlos A Pasqualucci
- Brazilian Aging Brain Study Group - LIM22, Department of Pathology, School of Medicine, University of São Paulo, São PauloBrazil; Department of Pathology, School of Medicine, University of São Paulo, São PauloBrazil
| | - Lea T Grinberg
- Brazilian Aging Brain Study Group - LIM22, Department of Pathology, School of Medicine, University of São Paulo, São PauloBrazil; Memory and Aging Center, Department of Neurology, University of California, San Francisco, San Francisco, CAUSA
| | - Carla Rosenberg
- Human Genome and Stem-Cell Research Center, Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo Brazil
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Garcia-Ratés S, Morrill P, Tu H, Pottiez G, Badin AS, Tormo-Garcia C, Heffner C, Coen CW, Greenfield SA. (I) Pharmacological profiling of a novel modulator of the α7 nicotinic receptor: Blockade of a toxic acetylcholinesterase-derived peptide increased in Alzheimer brains. Neuropharmacology 2016; 105:487-499. [PMID: 26867503 DOI: 10.1016/j.neuropharm.2016.02.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 02/01/2016] [Accepted: 02/05/2016] [Indexed: 01/08/2023]
Abstract
The primary cause of Alzheimer's disease is unlikely to be the much studied markers amyloid beta or tau. Their widespread distribution throughout the brain does not account for the specific identity and deep subcortical location of the primarily vulnerable neurons. Moreover an unusual and intriguing feature of these neurons is that, despite their diverse transmitters, they all contain acetylcholinesterase. Here we show for the first time that (1) a peptide derived from acetylcholinesterase, with independent trophic functions that turn toxic in maturity, is significantly raised in the Alzheimer midbrain and cerebrospinal fluid; (2) a synthetic version of this peptide enhances calcium influx and eventual production of amyloid beta and tau phosphorylation via an allosteric site on the α7 nicotinic receptor; (3) a synthetic cyclic version of this peptide is neuroprotective against the toxicity not only of its linear counterpart but also of amyloid beta, thereby opening up the prospect of a novel therapeutic approach.
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Affiliation(s)
- Sara Garcia-Ratés
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom.
| | - Paul Morrill
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
| | - Henry Tu
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
| | - Gwenael Pottiez
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
| | - Antoine-Scott Badin
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
| | - Cristina Tormo-Garcia
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
| | - Catherine Heffner
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
| | - Clive W Coen
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
| | - Susan A Greenfield
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
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TREM2 lipid sensing sustains the microglial response in an Alzheimer's disease model. Cell 2015; 160:1061-71. [PMID: 25728668 PMCID: PMC4477963 DOI: 10.1016/j.cell.2015.01.049] [Citation(s) in RCA: 1141] [Impact Index Per Article: 126.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 12/11/2014] [Accepted: 01/26/2015] [Indexed: 11/24/2022]
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is a microglia surface receptor that triggers intracellular protein tyrosine phosphorylation. Recent genome-wide association studies have shown that a rare R47H mutation of TREM2 correlates with a substantial increase in the risk of developing Alzheimer's disease (AD). To address the basis for this genetic association, we studied TREM2 deficiency in the 5XFAD mouse model of AD. We found that TREM2 deficiency and haploinsufficiency augment β-amyloid (Aβ) accumulation due to dysfunctional response of microglia, which become apoptotic and fail to cluster around Aβ plaques. We further demonstrate that TREM2 senses a broad array of anionic and zwitterionic lipids known to associate with fibrillar Aβ in lipid membranes and to be exposed on the surface of damaged neurons. Remarkably, the R47H mutation impairs TREM2 detection of lipid ligands. Thus, TREM2 detects damage-associated lipid patterns associated with neurodegeneration, sustaining microglia response to Aβ accumulation.
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8
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Prada I, Furlan R, Matteoli M, Verderio C. Classical and unconventional pathways of vesicular release in microglia. Glia 2013; 61:1003-17. [PMID: 23625857 DOI: 10.1002/glia.22497] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/22/2013] [Indexed: 12/30/2022]
Abstract
Emerging evidence indicates that activation of microglia, the immune cells of the brain, is strictly associated to both secretion of soluble molecules and release of extracellular membrane vesicles (EMVs) into the pericellular space. Through these processes, microglia heavily influence brain cell functions, either propagating inflammation and causing damage to neurons or playing a supportive, neuroprotective role. In this review, we highlight the emerging concepts related to vesicular mechanisms of secretion operating in microglial cells, with the aim of dissecting how microglia communicate with other cell types within the brain microenvironment in health and disease.
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Affiliation(s)
- Ilaria Prada
- Humanitas Clinical and Research Center, Rozzano (MI), Italy
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Granic A, Potter H. Mitotic spindle defects and chromosome mis-segregation induced by LDL/cholesterol-implications for Niemann-Pick C1, Alzheimer's disease, and atherosclerosis. PLoS One 2013; 8:e60718. [PMID: 23593294 PMCID: PMC3625184 DOI: 10.1371/journal.pone.0060718] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Accepted: 03/01/2013] [Indexed: 12/17/2022] Open
Abstract
Elevated low-density lipoprotein (LDL)-cholesterol is a risk factor for both Alzheimer's disease (AD) and Atherosclerosis (CVD), suggesting a common lipid-sensitive step in their pathogenesis. Previous results show that AD and CVD also share a cell cycle defect: chromosome instability and up to 30% aneuploidy-in neurons and other cells in AD and in smooth muscle cells in atherosclerotic plaques in CVD. Indeed, specific degeneration of aneuploid neurons accounts for 90% of neuronal loss in AD brain, indicating that aneuploidy underlies AD neurodegeneration. Cell/mouse models of AD develop similar aneuploidy through amyloid-beta (Aß) inhibition of specific microtubule motors and consequent disruption of mitotic spindles. Here we tested the hypothesis that, like upregulated Aß, elevated LDL/cholesterol and altered intracellular cholesterol homeostasis also causes chromosomal instability. Specifically we found that: 1) high dietary cholesterol induces aneuploidy in mice, satisfying the hypothesis' first prediction, 2) Niemann-Pick C1 patients accumulate aneuploid fibroblasts, neurons, and glia, demonstrating a similar aneugenic effect of intracellular cholesterol accumulation in humans 3) oxidized LDL, LDL, and cholesterol, but not high-density lipoprotein (HDL), induce chromosome mis-segregation and aneuploidy in cultured cells, including neuronal precursors, indicating that LDL/cholesterol directly affects the cell cycle, 4) LDL-induced aneuploidy requires the LDL receptor, but not Aß, showing that LDL works differently than Aß, with the same end result, 5) cholesterol treatment disrupts the structure of the mitotic spindle, providing a cell biological mechanism for its aneugenic activity, and 6) ethanol or calcium chelation attenuates lipoprotein-induced chromosome mis-segregation, providing molecular insights into cholesterol's aneugenic mechanism, specifically through its rigidifying effect on the cell membrane, and potentially explaining why ethanol consumption reduces the risk of developing atherosclerosis or AD. These results suggest a novel, cell cycle mechanism by which aberrant cholesterol homeostasis promotes neurodegeneration and atherosclerosis by disrupting chromosome segregation and potentially other aspects of microtubule physiology.
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Affiliation(s)
- Antoneta Granic
- Department of Neurology and Linda Crnic Institute for Down Syndrome, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- Institute for Ageing and Health, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Huntington Potter
- Department of Neurology and Linda Crnic Institute for Down Syndrome, University of Colorado School of Medicine, Aurora, Colorado, United States of America
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Kawahara M, Ohtsuka I, Yokoyama S, Kato-Negishi M, Sadakane Y. Membrane Incorporation, Channel Formation, and Disruption of Calcium Homeostasis by Alzheimer's β-Amyloid Protein. Int J Alzheimers Dis 2011; 2011:304583. [PMID: 21547225 PMCID: PMC3087492 DOI: 10.4061/2011/304583] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2010] [Revised: 12/22/2010] [Accepted: 01/27/2011] [Indexed: 01/09/2023] Open
Abstract
Oligomerization, conformational changes, and the consequent neurodegeneration of Alzheimer's β-amyloid protein (AβP) play crucial roles in the pathogenesis of Alzheimer's disease (AD). Mounting evidence suggests that oligomeric AβPs cause the disruption of calcium homeostasis, eventually leading to neuronal death. We have demonstrated that oligomeric AβPs directly incorporate into neuronal membranes, form cation-sensitive ion channels (“amyloid channels”), and cause the disruption of calcium homeostasis via the amyloid channels. Other disease-related amyloidogenic proteins, such as prion protein in prion diseases or α-synuclein in dementia with Lewy bodies, exhibit similarities in the incorporation into membranes and the formation of calcium-permeable channels. Here, based on our experimental results and those of numerous other studies, we review the current understanding of the direct binding of AβP into membrane surfaces and the formation of calcium-permeable channels. The implication of composition of membrane lipids and the possible development of new drugs by influencing membrane properties and attenuating amyloid channels for the treatment and prevention of AD is also discussed.
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Affiliation(s)
- Masahiro Kawahara
- Department of Analytical Chemistry, School of Pharmaceutical Sciences, Kyushu University of Health and Welfare, 1714-1 Yoshino-cho, Nobeoka-shi, Miyazaki 882-8508, Japan
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Granzotto A, Bolognin S, Scancar J, Milacic R, Zatta P. Beta-amyloid toxicity increases with hydrophobicity in the presence of metal ions. MONATSHEFTE FUR CHEMIE 2011. [DOI: 10.1007/s00706-011-0470-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Aluminum enhances the toxic effects of amyloid β-peptide on cell membranes and a molecular model. MONATSHEFTE FUR CHEMIE 2011. [DOI: 10.1007/s00706-011-0471-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Tamboli IY, Barth E, Christian L, Siepmann M, Kumar S, Singh S, Tolksdorf K, Heneka MT, Lütjohann D, Wunderlich P, Walter J. Statins promote the degradation of extracellular amyloid {beta}-peptide by microglia via stimulation of exosome-associated insulin-degrading enzyme (IDE) secretion. J Biol Chem 2010; 285:37405-14. [PMID: 20876579 DOI: 10.1074/jbc.m110.149468] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epidemiological studies indicate that intake of statins decrease the risk of developing Alzheimer disease. Cellular and in vivo studies suggested that statins might decrease the generation of the amyloid β-peptide (Aβ) from the β-amyloid precursor protein. Here, we show that statins potently stimulate the degradation of extracellular Aβ by microglia. The statin-dependent clearance of extracellular Aβ is mainly exerted by insulin-degrading enzyme (IDE) that is secreted in a nonconventional pathway in association with exosomes. Stimulated IDE secretion and Aβ degradation were also observed in blood of mice upon peripheral treatment with lovastatin. Importantly, increased IDE secretion upon lovastatin treatment was dependent on protein isoprenylation and up-regulation of exosome secretion by fusion of multivesicular bodies with the plasma membrane. These data demonstrate a novel pathway for the nonconventional secretion of IDE via exosomes. The modulation of this pathway could provide a new strategy to enhance the extracellular clearance of Aβ.
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Affiliation(s)
- Irfan Y Tamboli
- Departments of Neurology, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
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Harris JR, Milton NGN. Cholesterol in Alzheimer's disease and other amyloidogenic disorders. Subcell Biochem 2010; 51:47-75. [PMID: 20213540 DOI: 10.1007/978-90-481-8622-8_2] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The complex association of cholesterol metabolism and Alzheimer's disease is presented in depth, including the possible benefits to be gained from cholesterol-lowering statin therapy. Then follows a survey of the role of neuronal membrane cholesterol in Abeta pore formation and Abeta fibrillogenesis, together with the link with membrane raft domains and gangliosides. The contribution of structural studies to Abeta fibrillogenesis, using TEM and AFM, is given some emphasis. The role of apolipoprotein E and its isoforms, in particular ApoE4, in cholesterol and Abeta binding is presented, in relation to genetic risk factors for Alzheimer's disease. Increasing evidence suggests that cholesterol oxidation products are of importance in generation of Alzheimer's disease, possibly induced by Abeta-produced hydrogen peroxide. The body of evidence for a link between cholesterol in atherosclerosis and Alzheimer's disease is increasing, along with an associated inflammatory response. The possible role of cholesterol in tau fibrillization, tauopathies and in some other non-Abeta amyloidogenic disorders is surveyed.
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Affiliation(s)
- J Robin Harris
- Institute of Zoology, University of Mainz, D-55099, Mainz, Germany.
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15
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Cecchi C, Nichino D, Zampagni M, Bernacchioni C, Evangelisti E, Pensalfini A, Liguri G, Gliozzi A, Stefani M, Relini A. A protective role for lipid raft cholesterol against amyloid-induced membrane damage in human neuroblastoma cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2204-16. [DOI: 10.1016/j.bbamem.2009.07.019] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 07/16/2009] [Accepted: 07/23/2009] [Indexed: 12/14/2022]
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Bakota L, Brandt R. Chapter 2 Live‐Cell Imaging in the Study of Neurodegeneration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 276:49-103. [DOI: 10.1016/s1937-6448(09)76002-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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17
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Kraus B, Wolff H, Heilmann J, Elstner EF. Influence of Hypericum perforatum extract and its single compounds on amyloid-beta mediated toxicity in microglial cells. Life Sci 2007; 81:884-94. [PMID: 17725929 DOI: 10.1016/j.lfs.2007.07.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Revised: 07/04/2007] [Accepted: 07/12/2007] [Indexed: 01/13/2023]
Abstract
As immunocompetent cells of the brain, microglia are able to counteract the damaging effects of amyloid-beta in Alzheimer's disease by phagocytosis-mediated clearance of protein aggregates. The survival and health of microglia are therefore critical for attenuating and preventing neurodegenerative diseases. In a microglial cell line pretreated with St. John's wort (Hypericum perforatum L.) extract (HPE), the cell death evoked by treatment with amyloid-beta (25-35) and (1-40) was attenuated significantly in a dose-dependent manner. Investigation of the single compounds in the extract revealed that the flavanols (+)-catechin and (-)-epicatechin increase cell viability slightly, whereas the flavonol quercetin and its glycosides rutin, hyperosid and quercitrin showed no effect on cell viability. In contrast, at the same concentration, the flavonoids reduced the formation of amyloid-induced reactive oxygen species in microglia, indicating that improvement of cell viability by the catechins is not correlated to the antioxidant activity. No influence of HPE on the capacity of microglia to phagocytose sub-toxic concentrations of fibrillar amyloid-beta (1-40) was observed. Other experiments showed that HPE, (+)-catechin and (-)-epicatechin can alter cellular membrane fluidity and thereby may have a beneficial effect on cell health. Our findings provide in vitro evidence that treatment especially with the complex plant extract HPE may restore or improve microglial viability and thereby attenuate amyloid-beta mediated toxicity in Alzheimer's disease.
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Affiliation(s)
- Birgit Kraus
- Chair of Phytopathology, Technical University of Munich, Wissenschaftszentrum Weihenstephan, Am Hochanger 2, Freising, Germany.
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Small DH, Maksel D, Kerr ML, Ng J, Hou X, Chu C, Mehrani H, Unabia S, Azari MF, Loiacono R, Aguilar MI, Chebib M. The ?-amyloid protein of Alzheimer?s disease binds to membrane lipids but does not bind to the ?7 nicotinic acetylcholine receptor. J Neurochem 2007; 101:1527-38. [PMID: 17286584 DOI: 10.1111/j.1471-4159.2006.04444.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Accumulation of the amyloid protein (Abeta) in the brain is an important step in the pathogenesis of Alzheimer's disease. However, the mechanism by which Abeta exerts its neurotoxic effect is largely unknown. It has been suggested that the peptide can bind to the alpha7 nicotinic acetylcholine receptor (alpha7nAChR). In this study, we examined the binding of Abeta1-42 to endogenous and recombinantly expressed alpha7nAChRs. Abeta1-42 did neither inhibit the specific binding of alpha7nAChR ligands to rat brain homogenate or slice preparations, nor did it influence the activity of alpha7nAChRs expressed in Xenopus oocytes. Similarly, Abeta1-42 did not compete for alpha-bungarotoxin-binding sites on SH-SY5Y cells stably expressing alpha7nAChRs. The effect of the Abeta1-42 on tau phosphorylation was also examined. Although Abeta1-42 altered tau phosphorylation in alpha7nAChR-transfected SH-SY5Y cells, the effect of the peptide was unrelated to alpha7nAChR expression or activity. Binding studies using surface plasmon resonance indicated that the majority of the Abeta bound to membrane lipid, rather than to a protein component. Fluorescence anisotropy experiments indicated that Abeta may disrupt membrane lipid structure or fluidity. We conclude that the effects of Abeta are unlikely to be mediated by direct binding to the alpha7nAChR. Instead, we speculate that Abeta may exert its effects by altering the packing of lipids within the plasma membrane, which could, in turn, influence the function of a variety of receptors and channels on the cell surface.
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Affiliation(s)
- David H Small
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia.
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Masters CL, Cappai R, Barnham KJ, Villemagne VL. Molecular mechanisms for Alzheimer's disease: implications for neuroimaging and therapeutics. J Neurochem 2006; 97:1700-25. [PMID: 16805778 DOI: 10.1111/j.1471-4159.2006.03989.x] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Alzheimer's disease is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are beta-amyloid (Abeta) plaques, neurofibrillary tangles, synaptic loss and reactive gliosis. The current therapeutic effort is directed towards developing drugs that reduce Abeta burden or toxicity by inhibiting secretase cleavage, Abeta aggregation, Abeta toxicity, Abeta metal interactions or by promoting Abeta clearance. A number of clinical trials are currently in progress based on these different therapeutic strategies and they should indicate which, if any, of these approaches will be efficacious. Current diagnosis of Alzheimer's disease is made by clinical, neuropsychologic and neuroimaging assessments. Routine structural neuroimaging evaluation with computed tomography and magnetic resonance imaging is based on non-specific features such as atrophy, a late feature in the progression of the disease, hence the crucial importance of developing new approaches for early and specific recognition at the prodromal stages of Alzheimer's disease. Functional neuroimaging techniques such as functional magnetic resonance imaging, magnetic resonance spectroscopy, positron emission tomography and single photon emission computed tomography, possibly in conjunction with other related Abeta biomarkers in plasma and CSF, could prove to be valuable in the differential diagnosis of Alzheimer's disease, as well as in assessing prognosis. With the advent of new therapeutic strategies there is increasing interest in the development of magnetic resonance imaging contrast agents and positron emission tomography and single photon emission computed tomography radioligands that will permit the assessment of Abeta burden in vivo.
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Affiliation(s)
- Colin L Masters
- Department of Pathology, The University of Melbourne, VIC, Australia.
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Smith DP, Smith DG, Curtain CC, Boas JF, Pilbrow JR, Ciccotosto GD, Lau TL, Tew DJ, Perez K, Wade JD, Bush AI, Drew SC, Separovic F, Masters CL, Cappai R, Barnham KJ. Copper-mediated Amyloid-β Toxicity Is Associated with an Intermolecular Histidine Bridge. J Biol Chem 2006; 281:15145-54. [PMID: 16595673 DOI: 10.1074/jbc.m600417200] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Amyloid-beta peptide (Abeta) is pivotal to the pathogenesis of Alzheimer disease. Here we report the formation of a toxic Abeta-Cu2+ complex formed via a histidine-bridged dimer, as observed at Cu2+/peptide ratios of >0.6:1 by EPR spectroscopy. The toxicity of the Abeta-Cu2+ complex to cultured primary cortical neurons was attenuated when either the pi -or tau-nitrogen of the imidazole side chains of His were methylated, thereby inhibiting formation of the His bridge. Toxicity did not correlate with the ability to form amyloid or perturb the acyl-chain region of a lipid membrane as measured by diphenyl-1,3,5-hexatriene anisotropy, but did correlate with lipid peroxidation and dityrosine formation. 31P magic angle spinning solid-state NMR showed that Abeta and Abeta-Cu2+ complexes interacted at the surface of a lipid membrane. These findings indicate that the generation of the Abeta toxic species is modulated by the Cu2+ concentration and the ability to form an intermolecular His bridge.
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Affiliation(s)
- David P Smith
- Department of Pathology, Centre for Neuroscience, and School of Chemistry, University of Melbourne, Victoria 3010, Australia
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