801
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Gau JT, Steinhilb ML, Kao TC, D'Amato CJ, Gaut JR, Frey KA, Turner RS. Stable beta-secretase activity and presynaptic cholinergic markers during progressive central nervous system amyloidogenesis in Tg2576 mice. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 160:731-8. [PMID: 11839594 PMCID: PMC1850661 DOI: 10.1016/s0002-9440(10)64893-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We examined presynaptic cholinergic markers and beta-secretase activity during progressive central nervous system amyloidogenesis in Tg2576 Alzheimer mice (transgenic for human amyloid precursor protein Swedish mutation; hAPPswe). At 14, 18, and 23 months of age there were no significant differences between wild-type and transgenic mice in four distinct central nervous system cholinergic indices--choline acetyltransferase and acetylcholinesterase activities, and binding to vesicular acetylcholine transporter and Na(+)-dependent high-affinity choline uptake sites. A novel enzyme-linked immunosorbent assay measuring only the secreted human beta-secretase cleavage product (APPsbetaswe) of APPswe also revealed no change with aging in Tg2576 mouse brain. In contrast, transgenic but not wild-type mice exhibited an age-dependent increase in soluble Abeta40 and Abeta42 levels and progressive amyloid deposition in brain. Thus, aging Tg2576 mice exhibited presynaptic cholinergic integrity despite progressively increased soluble Abeta40 and Abeta42 levels and amyloid plaque density in brain. Older Tg2576 mice may best resemble preclinical or early stages of human Alzheimer's disease with preserved presynaptic cholinergic innervation. Homeostatic APPsbetaswe levels with aging suggest that progressive amyloid deposition in brain results not from increased beta-secretase cleavage of APP but from impaired Abeta/amyloid clearance mechanisms.
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Affiliation(s)
- Jen-Tzer Gau
- Department of Medicine, Division of Geriatric Medicine, the Institute of Gerontology, University of Michigan, Ann Arbor, MI 48105, USA
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802
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Amyloid-associated neuron loss and gliogenesis in the neocortex of amyloid precursor protein transgenic mice. J Neurosci 2002. [PMID: 11784797 DOI: 10.1523/jneurosci.22-02-00515.2002] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
APP23 transgenic mice express mutant human amyloid precursor protein and develop amyloid plaques predominantly in neocortex and hippocampus progressively with age, similar to Alzheimer's disease. We have previously reported neuron loss in the hippocampal CA1 region of 14- to 18-month-old APP23 mice. In contrast, no neuron loss was found in neocortex. In the present study we have reinvestigated neocortical neuron numbers in adult and aged APP23 mice. Surprisingly, results revealed that 8-month-old APP23 mice have 13 and 14% more neocortical neurons compared with 8-month-old wild-type and 27-month-old APP23 mice, respectively. In 27-month-old APP23 mice we found an inverse correlation between amyloid load and neuron number. These results suggest that APP23 mice have more neurons until they develop amyloid plaques but then lose neurons in the process of cerebral amyloidogenesis. Supporting this notion, we found more neurons with a necrotic-apoptotic phenotype in the neocortex of 24-month-old APP23 mice compared with age-matched wild-type mice. Stimulated by recent reports that demonstrated neurogenesis after targeted neuron death in the mouse neocortex, we have also examined neurogenesis in APP23 mice. Strikingly, we found a fourfold to sixfold increase in newly produced cells in 24-month-old APP23 mice compared with both age-matched wild-type mice and young APP23 transgenic mice. However, subsequent cellular phenotyping revealed that none of the newly generated cells in neocortex had a neuronal phenotype. The majority were microglial and to a lesser extent astroglial cells. We conclude that cerebral amyloidosis in APP23 mice causes a modest neuron loss in neocortex and induces marked gliogenesis.
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803
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Bondolfi L, Calhoun M, Ermini F, Kuhn HG, Wiederhold KH, Walker L, Staufenbiel M, Jucker M. Amyloid-associated neuron loss and gliogenesis in the neocortex of amyloid precursor protein transgenic mice. J Neurosci 2002; 22:515-22. [PMID: 11784797 PMCID: PMC6758656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
APP23 transgenic mice express mutant human amyloid precursor protein and develop amyloid plaques predominantly in neocortex and hippocampus progressively with age, similar to Alzheimer's disease. We have previously reported neuron loss in the hippocampal CA1 region of 14- to 18-month-old APP23 mice. In contrast, no neuron loss was found in neocortex. In the present study we have reinvestigated neocortical neuron numbers in adult and aged APP23 mice. Surprisingly, results revealed that 8-month-old APP23 mice have 13 and 14% more neocortical neurons compared with 8-month-old wild-type and 27-month-old APP23 mice, respectively. In 27-month-old APP23 mice we found an inverse correlation between amyloid load and neuron number. These results suggest that APP23 mice have more neurons until they develop amyloid plaques but then lose neurons in the process of cerebral amyloidogenesis. Supporting this notion, we found more neurons with a necrotic-apoptotic phenotype in the neocortex of 24-month-old APP23 mice compared with age-matched wild-type mice. Stimulated by recent reports that demonstrated neurogenesis after targeted neuron death in the mouse neocortex, we have also examined neurogenesis in APP23 mice. Strikingly, we found a fourfold to sixfold increase in newly produced cells in 24-month-old APP23 mice compared with both age-matched wild-type mice and young APP23 transgenic mice. However, subsequent cellular phenotyping revealed that none of the newly generated cells in neocortex had a neuronal phenotype. The majority were microglial and to a lesser extent astroglial cells. We conclude that cerebral amyloidosis in APP23 mice causes a modest neuron loss in neocortex and induces marked gliogenesis.
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Affiliation(s)
- Luca Bondolfi
- Department of Neuropathology, Institute of Pathology, University of Basel, CH-4003 Basel, Switzerland
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804
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Wang HW, Pasternak JF, Kuo H, Ristic H, Lambert MP, Chromy B, Viola KL, Klein WL, Stine WB, Krafft GA, Trommer BL. Soluble oligomers of beta amyloid (1-42) inhibit long-term potentiation but not long-term depression in rat dentate gyrus. Brain Res 2002; 924:133-40. [PMID: 11750898 DOI: 10.1016/s0006-8993(01)03058-x] [Citation(s) in RCA: 401] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The dementia in Alzheimer disease (AD) is usually attributed to widespread neuronal loss in conjunction with the pathologic hallmarks of intracellular neurofibrillary tangles and extracellular plaques containing amyloid (A beta) in fibrillar form. Recently it has been demonstrated that non-fibrillar assemblies of A beta possess electrophysiologic activity, with the corollary that they may produce dementia by disrupting neuronal signaling prior to cell death. We therefore examined the effects of soluble oligomers of A beta(1-42) on long-term potentiation (LTP) and long-term depression (LTD), two cellular models of memory, in the dentate gyrus of rat hippocampal slices. Compared with vehicle controls, slices pre-incubated 60 min in the presence of A beta-derived diffusible ligands (ADDLs) showed no differences in threshold intensity to evoke a synaptic response, slope of field excitatory post-synaptic potentials (EPSPs), or the input/output function. Tetanus-induced LTP and reversal of LTD were strongly inhibited in ADDLs-treated slices whereas LTD was unaffected. These data suggest that soluble non-fibrillar amyloid may contribute to the pathogenesis of AD both by impairing LTP/memory formation at the cellular level and by creating 'neuroplasticity imbalance' manifested by unopposed LTD in the setting of impaired capacity for neural repair via reversal of LTD or LTP.
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Affiliation(s)
- Hai-Wei Wang
- Department of Pediatrics, Northwestern University Medical School and Evanston Hospital, Evanston, IL 60201, USA
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805
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Effects of Cerebrolysin™ on amyloid-β deposition in a transgenic model of Alzheimer’s disease. AGEING AND DEMENTIA CURRENT AND FUTURE CONCEPTS 2002. [DOI: 10.1007/978-3-7091-6139-5_31] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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806
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Rockenstein E, Mallory M, Mante M, Sisk A, Masliaha E. Early formation of mature amyloid-beta protein deposits in a mutant APP transgenic model depends on levels of Abeta(1-42). J Neurosci Res 2001; 66:573-82. [PMID: 11746377 DOI: 10.1002/jnr.1247] [Citation(s) in RCA: 179] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The main objective of the present study was to develop an alternative singly-transgenic (tg) hAPP model where amyloid deposition will occur at an earlier age. For this purpose, we generated lines of tg mice expressing hAPP751 cDNA containing the London (V717I) and Swedish (K670M/N671L) mutations under the regulatory control of the murine (m)Thy-1 gene (mThy1-hAPP751). In the brains of the highest (line 41) and intermediate (lines 16 and 11) expressers, high levels of hAPP expression were found in neurons in layers 4-5 of the neocortex, hippocampal CA1 and olfactory bulb. As early as 3-4 months of age, line 41 mice developed mature plaques in the frontal cortex, whereas at 5-7 months plaque formation extended to the hippocampus, thalamus and olfactory region. Ultrastructural and double-immunolabeling analysis confirmed that most plaques were mature and contained dystrophic neurites immunoreactive with antibodies against APP, synaptophysin, neurofilament and tau. In addition, a decrease in the number of synaptophysin-immunoreactive terminals was most prominent in the frontal cortex of mice from line 41. Mice from line 11 developed diffuse amyloid deposits at 11 months of age, whereas mice from line 16 did not show evidence of amyloid deposition. Analysis of Abeta by ELISA showed that levels of Abeta(1-40) were higher in mice that did not show any amyloid deposits (line 16), whereas Abeta(1-42) was the predominant species in tg animals from the lines showing plaque formation (lines 41 and 11). Taken together this study indicates that early onset plaque formation depends on levels of Abeta(1-42).
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MESH Headings
- Aging/genetics
- Aging/metabolism
- Alzheimer Disease/genetics
- Alzheimer Disease/metabolism
- Alzheimer Disease/physiopathology
- Amyloid beta-Peptides/genetics
- Amyloid beta-Peptides/metabolism
- Amyloid beta-Peptides/ultrastructure
- Amyloid beta-Protein Precursor/genetics
- Amyloid beta-Protein Precursor/metabolism
- Animals
- Benzothiazoles
- Brain/metabolism
- Brain/pathology
- Brain/physiopathology
- Congo Red
- Disease Models, Animal
- Gene Expression Regulation, Developmental/physiology
- Mice
- Mice, Neurologic Mutants
- Mice, Transgenic
- Microscopy, Electron
- Mutagenesis, Insertional
- Mutation/physiology
- Neurites/metabolism
- Neurites/pathology
- Neurites/ultrastructure
- Neurons/metabolism
- Neurons/pathology
- Neurons/ultrastructure
- Peptide Fragments/genetics
- Peptide Fragments/metabolism
- Peptide Fragments/ultrastructure
- Plaque, Amyloid/genetics
- Plaque, Amyloid/metabolism
- Plaque, Amyloid/ultrastructure
- Presynaptic Terminals/metabolism
- Presynaptic Terminals/pathology
- Presynaptic Terminals/ultrastructure
- Promoter Regions, Genetic/physiology
- Thiazoles
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Affiliation(s)
- E Rockenstein
- Department of Neurosciences, University of California, San Diego, School of Medicine, La Jolla, California 92093-0624, USA
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807
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Abstract
Recent advances in behavioral analyses of transgenic mouse models of Alzheimer's disease (AD) are discussed, and their impact on our understanding of the molecular basis of cognitive impairment in AD is considered. Studies of the relationship between memory and A Beta in transgenic mice expressing the amyloid precursor protein (APP) and its variants suggest that aging promotes the formation of soluble A Beta assemblies mediating negative effects on memory. A significant component of memory loss in APP transgenic mice is apparently caused by soluble A Beta assemblies, but whether and how much of the dementia within individuals afflicted with AD is caused by these A Beta species is unclear. Future studies in composite transgenic mice developing amyloid plaques, neurofibrillary tangles, and other AD pathology may allow for the determination of the relative contribution of A Beta and non-A Beta components to dementia.
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Affiliation(s)
- K H Ashe
- Department of Neurology, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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808
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Lambert MP, Viola KL, Chromy BA, Chang L, Morgan TE, Yu J, Venton DL, Krafft GA, Finch CE, Klein WL. Vaccination with soluble Abeta oligomers generates toxicity-neutralizing antibodies. J Neurochem 2001; 79:595-605. [PMID: 11701763 DOI: 10.1046/j.1471-4159.2001.00592.x] [Citation(s) in RCA: 252] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In recent studies of transgenic models of Alzheimer's disease (AD), it has been reported that antibodies to aged beta amyloid peptide 1-42 (Abeta(1-42)) solutions (mixtures of Abeta monomers, oligomers and amyloid fibrils) cause conspicuous reduction of amyloid plaques and neurological improvement. In some cases, however, neurological improvement has been independent of obvious plaque reduction, and it has been suggested that immunization might neutralize soluble, non-fibrillar forms of Abeta. It is now known that Abeta toxicity resides not only in fibrils, but also in soluble protofibrils and oligomers. The current study has investigated the immune response to low doses of Abeta(1-42) oligomers and the characteristics of the antibodies they induce. Rabbits that were injected with Abeta(1-42) solutions containing only monomers and oligomers produced antibodies that preferentially bound to assembled forms of Abeta in immunoblots and in physiological solutions. The antibodies have proven useful for assays that can detect inhibitors of oligomer formation, for immunofluorescence localization of cell-attached oligomers to receptor-like puncta, and for immunoblots that show the presence of SDS-stable oligomers in Alzheimer's brain tissue. The antibodies, moreover, were found to neutralize the toxicity of soluble oligomers in cell culture. Results support the hypothesis that immunizations of transgenic mice derive therapeutic benefit from the immuno-neutralization of soluble Abeta-derived toxins. Analogous immuno-neutralization of oligomers in humans may be a key in AD vaccines.
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Affiliation(s)
- M P Lambert
- Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208, USA
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809
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Familial amyloid polyneuropathy: receptor for advanced glycation end products-dependent triggering of neuronal inflammatory and apoptotic pathways. J Neurosci 2001. [PMID: 11567048 DOI: 10.1523/jneurosci.21-19-07576.2001] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Familial amyloid polyneuropathy (FAP) is a neurodegenerative disorder associated with extracellular deposition of mutant transthyretin (TTR) amyloid fibrils, particularly in the peripheral nervous system. We have hypothesized that binding of TTR fibrils to the receptor for advanced glycation end products (RAGE) on critical cellular targets is associated with a destructive stress response underlying peripheral nerve dysfunction. Analysis of nerve biopsy samples from patients with FAP (n = 16) at different stages of disease (0-3), compared with age-matched controls (n = 4), by semiquantitative immunohistology and in situ hybridization showed increased levels of RAGE, beginning at the earliest stages of the disease (FAP 0; p < 0.02) and especially localized in axons. Upregulation of proinflammatory cytokines (tumor necrosis factor-alpha and interleukin-1beta) (approximately threefold; p < 0.02) and the inducible form of nitric oxide synthase (iNOS) ( approximately 2.5-fold; p < 0.04) was also observed in a distribution overlapping RAGE expression. Tyrosine nitration and increased activated caspase-3 in axons from FAP patients (p < 0.03) were apparent. Although these data suggest the presence of ongoing neuronal stress, there was no upregulation of neurotrophins (nerve growth factor and neurotrophin-3) in FAP nerves. Studies on cultured neuronal-like, Schwann, and endothelial cells incubated with TTR fibrils displayed RAGE-dependent expression of cytokines and iNOS at early times (6 and 12 hr, respectively), followed by later (24 hr) activation of caspase-3 and DNA fragmentation. We propose that the interaction of TTR fibrils with RAGE may contribute to cellular stress and toxicity in FAP. Furthermore, there is an apparent lack of responsiveness of Schwann cells in FAP nerve to provide neurotrophic factors.
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810
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Masliah E, Rockenstein E, Veinbergs I, Sagara Y, Mallory M, Hashimoto M, Mucke L. beta-amyloid peptides enhance alpha-synuclein accumulation and neuronal deficits in a transgenic mouse model linking Alzheimer's disease and Parkinson's disease. Proc Natl Acad Sci U S A 2001; 98:12245-50. [PMID: 11572944 PMCID: PMC59799 DOI: 10.1073/pnas.211412398] [Citation(s) in RCA: 442] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Alzheimer's disease and Parkinson's disease are associated with the cerebral accumulation of beta-amyloid and alpha-synuclein, respectively. Some patients have clinical and pathological features of both diseases, raising the possibility of overlapping pathogenetic pathways. We generated transgenic (tg) mice with neuronal expression of human beta-amyloid peptides, alpha-synuclein, or both. The functional and morphological alterations in doubly tg mice resembled the Lewy-body variant of Alzheimer's disease. These mice had severe deficits in learning and memory, developed motor deficits before alpha-synuclein singly tg mice, and showed prominent age-dependent degeneration of cholinergic neurons and presynaptic terminals. They also had more alpha-synuclein-immunoreactive neuronal inclusions than alpha-synuclein singly tg mice. Ultrastructurally, some of these inclusions were fibrillar in doubly tg mice, whereas all inclusions were amorphous in alpha-synuclein singly tg mice. beta-Amyloid peptides promoted aggregation of alpha-synuclein in a cell-free system and intraneuronal accumulation of alpha-synuclein in cell culture. beta-Amyloid peptides may contribute to the development of Lewy-body diseases by promoting the aggregation of alpha-synuclein and exacerbating alpha-synuclein-dependent neuronal pathologies. Therefore, treatments that block the production or accumulation of beta-amyloid peptides could benefit a broader spectrum of disorders than previously anticipated.
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Affiliation(s)
- E Masliah
- Department of Neurosciences, University of California at San Diego, La Jolla, CA 92093, USA.
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811
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Hafner JH, Cheung CL, Woolley AT, Lieber CM. Structural and functional imaging with carbon nanotube AFM probes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2001; 77:73-110. [PMID: 11473787 DOI: 10.1016/s0079-6107(01)00011-6] [Citation(s) in RCA: 280] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Atomic force microscopy (AFM) has great potential as a tool for structural biology, a field in which there is increasing demand to characterize larger and more complex biomolecular systems. However, the poorly characterized silicon and silicon nitride probe tips currently employed in AFM limit its biological applications. Carbon nanotubes represent ideal AFM tip materials due to their small diameter, high aspect ratio, large Young's modulus, mechanical robustness, well-defined structure, and unique chemical properties. Nanotube probes were first fabricated by manual assembly, but more recent methods based on chemical vapor deposition provide higher resolution probes and are geared towards mass production, including recent developments that enable quantitative preparation of individual single-walled carbon nanotube tips [J. Phys. Chem. B 105 (2001) 743]. The high-resolution imaging capabilities of these nanotube AFM probes have been demonstrated on gold nanoparticles and well-characterized biomolecules such as IgG and GroES. Using the nanotube probes, new biological structures have been investigated in the areas of amyloid-beta protein aggregation and chromatin remodeling, and new biotechnologies have been developed such as AFM-based haplotyping. In addition to measuring topography, chemically functionalized AFM probes can measure the spatial arrangement of chemical functional groups in a sample. However, standard silicon and silicon nitride tips, once functionalized, do not yield sufficient resolution to allow combined structural and functional imaging of biomolecules. The unique end-group chemistry of carbon nanotubes, which can be arbitrarily modified by established chemical methods, has been exploited for chemical force microscopy, allowing single-molecule measurements with well-defined functionalized tips.
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Affiliation(s)
- J H Hafner
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
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812
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Kirkitadze MD, Condron MM, Teplow DB. Identification and characterization of key kinetic intermediates in amyloid beta-protein fibrillogenesis. J Mol Biol 2001; 312:1103-19. [PMID: 11580253 DOI: 10.1006/jmbi.2001.4970] [Citation(s) in RCA: 557] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amyloid beta-protein (Abeta) assembly into toxic oligomeric and fibrillar structures is a seminal event in Alzheimer's disease, therefore blocking this process could have significant therapeutic benefit. A rigorous mechanistic understanding of Abeta assembly would facilitate the targeting and design of fibrillogenesis inhibitors. Prior studies have shown that Abeta fibrillogenesis involves conformational changes leading to the formation of extended beta-sheets and that an alpha-helix-containing intermediate may be involved. However, the significance of this intermediate has been a matter of debate. We report here that the formation of an oligomeric, alpha-helix-containing assembly is a key step in Abeta fibrillogenesis. The generality of this phenomenon was supported by conformational studies of 18 different Abeta peptides, including wild-type Abeta(1-40) and Abeta(1-42), biologically relevant truncated and chemically modified Abeta peptides, and Abeta peptides causing familial forms of cerebral amyloid angiopathy. Without exception, fibrillogenesis of these peptides involved an oligomeric alpha-helix-containing intermediate and the kinetics of formation of the intermediate and of fibrils was temporally correlated. The kinetics varied depending on amino acid sequence and the extent of peptide N- and C-terminal truncation. The pH dependence of helix formation suggested that Asp and His exerted significant control over this process and over fibrillogenesis in general. Consistent with this idea, Abeta peptides containing Asp-->Asn or His-->Gln substitutions showed altered fibrillogenesis kinetics. These data emphasize the importance of the dynamic interplay between Abeta monomer conformation and oligomerization state in controlling fibrillogenesis kinetics.
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Affiliation(s)
- M D Kirkitadze
- Center for Neurologic Diseases, Brigham and Women's Hospital, Boston, MA 02115, USA
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813
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Abstract
Interactions between amyloid beta-protein (Abeta) and lipids have been suggested to play important roles in the pathogenesis of Alzheimer's disease. However, the molecular mechanism underlying these interactions has not been fully understood. We examined the effect of Abeta on lipid metabolism in cultured neurons and astrocytes and found that oligomeric Abeta, but not monomeric or fibrillar Abeta, promoted lipid release from both types of cells in a dose- and time-dependent manner. The main components of lipids released after the addition of Abeta were cholesterol, phospholipids, and monosialoganglioside (GM1). Density-gradient and electron microscopic analyses of the conditioned media demonstrated that these Abeta and lipids formed particles and were recovered from the fractions at densities of approximately 1.08-1.18 g/ml, which were similar to those of high-density lipoprotein (HDL) generated by apolipoproteins. The lipid release mediated by Abeta was abolished by concomitant treatment with Congo red and the PKC inhibitor, H7, whereas it was not inhibited with N-acetyl-l-cysteine. These Abeta-lipid particles were not internalized into neurons, whereas HDL-like particles produced by apolipoprotein E were internalized. Our findings indicate that oligomeric Abeta promotes lipid release from neuronal membrane, which may lead to the disruption of neuronal lipid homeostasis and the loss of neuronal function.
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814
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Wong PC, Cai H, Borchelt DR, Price DL. Genetically engineered models relevant to neurodegenerative disorders: their value for understanding disease mechanisms and designing/testing experimental therapeutics. J Mol Neurosci 2001; 17:233-57. [PMID: 11816796 DOI: 10.1385/jmn:17:2:233] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Significant progress in the identification of disease-specific genes for a variety of neurodegenerative diseases have provided opportunities to understand molecular mechanisms and to test experimental therapeutic for these disorders. Recent works on clarifying the selective vulnerability of neurons and pathogenic mechanisms using genetically engineered mouse models of familial forms of Alzheimer's disease and motor neuron disease will be reviewed.
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Affiliation(s)
- P C Wong
- Department of Pathology The Johns Hopkins University School of Medicine, Baltimore, MD 21205-2196, USA
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815
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Sousa MM, Du Yan S, Fernandes R, Guimaraes A, Stern D, Saraiva MJ. Familial amyloid polyneuropathy: receptor for advanced glycation end products-dependent triggering of neuronal inflammatory and apoptotic pathways. J Neurosci 2001; 21:7576-86. [PMID: 11567048 PMCID: PMC6762914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
Familial amyloid polyneuropathy (FAP) is a neurodegenerative disorder associated with extracellular deposition of mutant transthyretin (TTR) amyloid fibrils, particularly in the peripheral nervous system. We have hypothesized that binding of TTR fibrils to the receptor for advanced glycation end products (RAGE) on critical cellular targets is associated with a destructive stress response underlying peripheral nerve dysfunction. Analysis of nerve biopsy samples from patients with FAP (n = 16) at different stages of disease (0-3), compared with age-matched controls (n = 4), by semiquantitative immunohistology and in situ hybridization showed increased levels of RAGE, beginning at the earliest stages of the disease (FAP 0; p < 0.02) and especially localized in axons. Upregulation of proinflammatory cytokines (tumor necrosis factor-alpha and interleukin-1beta) (approximately threefold; p < 0.02) and the inducible form of nitric oxide synthase (iNOS) ( approximately 2.5-fold; p < 0.04) was also observed in a distribution overlapping RAGE expression. Tyrosine nitration and increased activated caspase-3 in axons from FAP patients (p < 0.03) were apparent. Although these data suggest the presence of ongoing neuronal stress, there was no upregulation of neurotrophins (nerve growth factor and neurotrophin-3) in FAP nerves. Studies on cultured neuronal-like, Schwann, and endothelial cells incubated with TTR fibrils displayed RAGE-dependent expression of cytokines and iNOS at early times (6 and 12 hr, respectively), followed by later (24 hr) activation of caspase-3 and DNA fragmentation. We propose that the interaction of TTR fibrils with RAGE may contribute to cellular stress and toxicity in FAP. Furthermore, there is an apparent lack of responsiveness of Schwann cells in FAP nerve to provide neurotrophic factors.
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Affiliation(s)
- M M Sousa
- Institute for Cellular and Molecular Biology, Columbia University, New York, New York 10032, USA
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816
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Michikawa M, Gong JS, Fan QW, Sawamura N, Yanagisawa K. A novel action of alzheimer's amyloid beta-protein (Abeta): oligomeric Abeta promotes lipid release. J Neurosci 2001; 21:7226-35. [PMID: 11549733 PMCID: PMC6762992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
Interactions between amyloid beta-protein (Abeta) and lipids have been suggested to play important roles in the pathogenesis of Alzheimer's disease. However, the molecular mechanism underlying these interactions has not been fully understood. We examined the effect of Abeta on lipid metabolism in cultured neurons and astrocytes and found that oligomeric Abeta, but not monomeric or fibrillar Abeta, promoted lipid release from both types of cells in a dose- and time-dependent manner. The main components of lipids released after the addition of Abeta were cholesterol, phospholipids, and monosialoganglioside (GM1). Density-gradient and electron microscopic analyses of the conditioned media demonstrated that these Abeta and lipids formed particles and were recovered from the fractions at densities of approximately 1.08-1.18 g/ml, which were similar to those of high-density lipoprotein (HDL) generated by apolipoproteins. The lipid release mediated by Abeta was abolished by concomitant treatment with Congo red and the PKC inhibitor, H7, whereas it was not inhibited with N-acetyl-l-cysteine. These Abeta-lipid particles were not internalized into neurons, whereas HDL-like particles produced by apolipoprotein E were internalized. Our findings indicate that oligomeric Abeta promotes lipid release from neuronal membrane, which may lead to the disruption of neuronal lipid homeostasis and the loss of neuronal function.
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Affiliation(s)
- M Michikawa
- Department of Dementia Research, National Institute for Longevity Sciences, Obu, Aichi 474-8522, Japan.
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817
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Kurt MA, Davies DC, Kidd M, Duff K, Rolph SC, Jennings KH, Howlett DR. Neurodegenerative changes associated with beta-amyloid deposition in the brains of mice carrying mutant amyloid precursor protein and mutant presenilin-1 transgenes. Exp Neurol 2001; 171:59-71. [PMID: 11520121 DOI: 10.1006/exnr.2001.7717] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mutations of amyloid precursor protein (APP) and presenilin-1 (PS1) lead to an increase in beta-amyloid (Abeta) production. Despite the fact that a number of transgenic mice develop cerebral Abeta plaques, few have been subjected to ultrastructural investigation and the sequence of events leading to Abeta plaque formation is unclear. We therefore investigated the doubly transgenic (mutant APP(K670N,M671L)-mutant PS1(M146L)) mouse, which develops Abeta deposits much earlier than singly transgenic littermates. Widespread Abeta plaques with or without a distinct core were found in gray matter. Abeta plaques were also present in white matter. Astrocytosis was greater around gray matter plaques than around white matter plaques. In some plaques, Abeta cores were associated with cell profiles containing prominent endoplasmic reticulum and a homogeneous cytoplasm that appeared to be neuronal. The morphology and location of other profiles indicated them to be microglia or oligodendrocytes. Some Abeta fibrils appeared to lie within these profiles, but they may have been simply surrounded by the cell profile since the profile membrane was not always visible. Dark atrophic neurons, whose morphology suggested that they were apoptotic, were present around gray matter plaques. Cerebrovascular Abeta deposition was also observed in the brains of APP/PS1 transgenic mice. Thus, the amyloid deposition and neuropathology observed in APP/PS1 mouse brain are similar to those in Alzheimer's disease and they appear to develop earlier and become more severe than in the other transgenic models currently available.
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Affiliation(s)
- M A Kurt
- St George's Hospital Medical School, London, United Kingdom
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818
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Janus C, Phinney AL, Chishti MA, Westaway D. New developments in animal models of Alzheimer's disease. Curr Neurol Neurosci Rep 2001; 1:451-7. [PMID: 11898556 DOI: 10.1007/s11910-001-0105-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Alzheimer's disease (AD) is characterized by deterioration in mental function leading to dementia, deposition of amyloid plaques and neurofibrillary tangles (NFTs), and neuronal loss. The major component of plaques is the amyloid-beta peptide (A beta), whereas NFTs are assemblies of hyperphosphorylated forms of the microtubule-associated protein tau. Electron microscopy of NFTs reveals structures known as paired helical filaments (PHFs). In familial AD (FAD), mutations in three distinct genes drive A beta synthesis by favoring endoproteolytic secretase cleavages that liberate A beta from the Alzheimer beta-amyloid precursor protein (APP). This suggests that excess A beta initiates a pathogenic cascade in humans that culminates in all the pathologic and cellular hallmarks of AD. Building upon the knowledge of FAD mutations, incremental technical advances have now allowed reproduceable creation of APP transgenic mice that exhibit AD-like amyloid pathology and A beta burdens. These transgenic mouse lines also exhibit deficits in spatial reference and working memory, with immunization against A beta abrogating both AD-associated phenotypes. Besides establishing a proof of principle for A beta-directed therapies, these findings suggest a potential to identify individual elements in the pathogenic pathway that lead to cognitive dysfunction. Furthermore, transgenic APP mice with potent amyloid deposition will likely form a beach-head to capture the final elements of AD neuropathology--cell loss and NFTs composed of PHFs--that are missing from current transgenic models.
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Affiliation(s)
- C Janus
- Centre for Research in Neurodegenerative Diseases, University of Toronto, Tanz Neuroscience Building, 6 Queen's Park Crescent West, Toronto, Ontario M55 3H2, Canada
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819
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Monsonego A, Maron R, Zota V, Selkoe DJ, Weiner HL. Immune hyporesponsiveness to amyloid beta-peptide in amyloid precursor protein transgenic mice: implications for the pathogenesis and treatment of Alzheimer's disease. Proc Natl Acad Sci U S A 2001; 98:10273-8. [PMID: 11517335 PMCID: PMC56951 DOI: 10.1073/pnas.191118298] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alzheimer's disease is a dementia that involves progressive deposition of amyloid beta-protein (Abeta) in brain regions important for memory and cognition, followed by secondary inflammation that contributes to the neuropathologic process. Immunization with Abeta can reduce cerebral Abeta burden and consequent neuropathologic changes in the brains of mice transgenic for the beta-amyloid precursor protein (APP). We found that transgenic expression of human APP in B6SJL mice, under the prion promoter, results in immune hyporesponsiveness to human Abeta, in terms of both antibody and cellular immune responses. The decreased antibody responses were related not to B cell tolerance but rather to the inability of Abeta-specific T cells to provide help for antibody production. The immune hyporesponsiveness could be overcome if T cell help was provided by coupling an Abeta B cell epitope to BSA. Our results suggest that expression of APP in transgenic mice is associated with an Abeta-specific impaired adaptive immune response that may contribute to the neuropathology. Moreover, humans with life-long elevation of brain and peripheral Abeta (e.g., patients with presenilin mutations or Down syndrome) could have reduced immune responses to Abeta vaccination.
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Affiliation(s)
- A Monsonego
- Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, 77 Avenue Louis Pasteur, HIM 730, Boston, MA 02115, USA
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820
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Generation of aggregated beta-amyloid in the rat hippocampus impairs synaptic transmission and plasticity and causes memory deficits. J Neurosci 2001. [PMID: 11466442 DOI: 10.1523/jneurosci.21-15-05703.2001] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We injected a combination of the beta-amyloids (Abetas) Abeta40 and Abeta43 to "seed" formation of amyloid deposits in the dorsal dentate gyrus of rats in vivo, on the basis of a theory of Jarrett and Landsbury (1993). Rats were tested on several different learning tasks, and synaptic transmission and plasticity were assessed in vivo. Between 7 and 16 weeks after injection, we found aggregated amyloid material, reactive astrocytosis, microgliosis, and cell loss around the sites of injection. Rats were impaired specifically in working memory type tasks in accordance with the type of memory deficit observed in the early stages of Alzheimer's disease. Synaptic transmission and long-term potentiation, a candidate cellular mechanism for memory, were severely impaired in vivo. Injections of the same dose of fragments individually did not induce these effects. These findings suggest that aggregated amyloid material induces cognitive deficits similar to those observed in the early phases of Alzheimer's disease via an alteration in neuronal transmission and plasticity.
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821
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Le R, Cruz L, Urbanc B, Knowles RB, Hsiao-Ashe K, Duff K, Irizarry MC, Stanley HE, Hyman BT. Plaque-induced abnormalities in neurite geometry in transgenic models of Alzheimer disease: implications for neural system disruption. J Neuropathol Exp Neurol 2001; 60:753-8. [PMID: 11487049 DOI: 10.1093/jnen/60.8.753] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Neurites that pass through amyloid-beta deposits in Alzheimer disease (AD) undergo 3 changes: they develop phosphorylated tau immunoreactivity; the density of SMI-32-positive dendrites diminishes; and they also develop a marked alteration in their geometric features, changing from being nearly straight to being quite curvy. The extent to which the latter 2 phenomena are related to phosphorylated tau is unknown. We have now examined whether amyloid-beta deposits in APP695Sw transgenic mice, which have only rare phosphorylated tau containing neurites. develop these changes. We found that dendritic density is diminished within the boundaries of amyloid-beta plaques, with the greatest loss (about 80%, p < 0.001) within the boundaries of thioflavine S cores. Remaining dendrites within plaques develop substantial morphological alterations quantitatively similar to those seen in AD. A statistically significant but smaller degree of change in geometry was seen in the immediate vicinity around plaques, suggesting a propagation of cytoskeletal disruption from the center of the plaque outward. We examined the possible physiological consequences of this change in dendritic geometry using a standard cable-theory model. We found a predicted delay of several milliseconds in about one quarter of the dendrites passing through a thioflavine S plaque. These results are consistent with previous observations in AD, and suggest that thioflavine S-positive amyloid-beta deposits have a marked effect on dendritic microarchitecture in the cortex, even in the relative absence of phosphorylated tau alterations.
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Affiliation(s)
- R Le
- Department of Neurology, Massachusetts General Hospital, Charlestown, USA
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822
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Abstract
The availability of the recently published DNA sequence of human chromosome 21 (HSA21) is a landmark contribution that will have an immediate impact on the study of the role of specific genes to Down syndrome (DS). Trisomy 21 or DS is the only autosomal aneuploidy that is not lethal in the fetal or early postnatal period. DS phenotypes show variable penetrance, affecting many different organs, including brain (mental retardation, early onset of Alzheimer's disease, AD), muscle (hypotonia), skeleton, and blood. DS phenotypes may stem directly from the cumulative effect of overexpression of specific HSA21 gene products or indirectly through the interaction of these gene products with the whole genome, transcriptome, or proteome. Mouse genetic models have played an important role in the elucidation of the contribution of specific genes to the DS phenotype. To date, the strategies used for modeling DS in mice have been three: (1) to assess single-gene contributions to DS phenotype, using transgenic techniques to create models overexpressing single or combinations of genes, (2) to assess the effects of overexpressing large foreign DNA pieces, introduced on yeast artificial chromosomes (YACs) or bacterial artificial chromosomes (BACs) into transgenic mice, and (3) mouse trisomies that carry all or part of MMU16, which has regions of conserved homology with HSA21. Here we review the existing murine models and the relevance of their contribution to DS research.
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Affiliation(s)
- M Dierssen
- Down Syndrome Research Group, Medical and Molecular Genetics Center-IRO, Hospital Duran i Reynals, Granvia km 2.7, 08907 L'Hospitalet de Llobregat, Barcelona, Spain.
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823
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Stéphan A, Laroche S, Davis S. Generation of aggregated beta-amyloid in the rat hippocampus impairs synaptic transmission and plasticity and causes memory deficits. J Neurosci 2001; 21:5703-14. [PMID: 11466442 PMCID: PMC6762634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
Abstract
We injected a combination of the beta-amyloids (Abetas) Abeta40 and Abeta43 to "seed" formation of amyloid deposits in the dorsal dentate gyrus of rats in vivo, on the basis of a theory of Jarrett and Landsbury (1993). Rats were tested on several different learning tasks, and synaptic transmission and plasticity were assessed in vivo. Between 7 and 16 weeks after injection, we found aggregated amyloid material, reactive astrocytosis, microgliosis, and cell loss around the sites of injection. Rats were impaired specifically in working memory type tasks in accordance with the type of memory deficit observed in the early stages of Alzheimer's disease. Synaptic transmission and long-term potentiation, a candidate cellular mechanism for memory, were severely impaired in vivo. Injections of the same dose of fragments individually did not induce these effects. These findings suggest that aggregated amyloid material induces cognitive deficits similar to those observed in the early phases of Alzheimer's disease via an alteration in neuronal transmission and plasticity.
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Affiliation(s)
- A Stéphan
- Laboratoire de Neurobiologie de l'Apprentissage, de la Mémoire et de la Communication, Centre National de la Recherche Scientifique Unité Mixte de Recherche 8620, Université Paris Sud, 91405 Orsay, France
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824
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Age-related impairment of synaptic transmission but normal long-term potentiation in transgenic mice that overexpress the human APP695SWE mutant form of amyloid precursor protein. J Neurosci 2001. [PMID: 11425896 DOI: 10.1523/jneurosci.21-13-04691.2001] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We have studied synaptic function in a transgenic mouse strain relevant to Alzheimer's disease (AD), overexpressing the 695 amino acid isoform of human amyloid precursor protein with K670N and M671L mutations (APP(695)SWE mice), which is associated with early-onset familial AD. Aged-transgenic mice had substantially elevated levels of Abeta (up to 22 micromol/gm) and displayed characteristic Abeta plaques. Hippocampal slices from 12-month-old APP(695)SWE transgenic animals displayed reduced levels of synaptic transmission in the CA1 region when compared with wild-type littermate controls. Inclusion of the ionotropic glutamate receptor antagonist kynurenate during preparation of brain slices abolished this deficit. At 18 months of age, a selective deficit in basal synaptic transmission was observed in the CA1 region despite treatment with kynurenate. Paired-pulse facilitation and long-term potentiation (LTP) were normal in APP(695)SWE transgenic mice at both 12 and 18 months of age. Thus, although aged APP(695)SWE transgenic mice have greatly elevated levels of Abeta protein, increased numbers of plaques, and reduced basal synaptic transmission, LTP can still be induced and expressed normally. We conclude that increased susceptibility to excitotoxicity rather than a specific effect on LTP is the primary cause of cognitive deficits in APP(695)SWE mice.
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825
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Fitzjohn SM, Morton RA, Kuenzi F, Rosahl TW, Shearman M, Lewis H, Smith D, Reynolds DS, Davies CH, Collingridge GL, Seabrook GR. Age-related impairment of synaptic transmission but normal long-term potentiation in transgenic mice that overexpress the human APP695SWE mutant form of amyloid precursor protein. J Neurosci 2001; 21:4691-8. [PMID: 11425896 PMCID: PMC6762352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2001] [Revised: 04/12/2001] [Accepted: 04/18/2001] [Indexed: 02/20/2023] Open
Abstract
We have studied synaptic function in a transgenic mouse strain relevant to Alzheimer's disease (AD), overexpressing the 695 amino acid isoform of human amyloid precursor protein with K670N and M671L mutations (APP(695)SWE mice), which is associated with early-onset familial AD. Aged-transgenic mice had substantially elevated levels of Abeta (up to 22 micromol/gm) and displayed characteristic Abeta plaques. Hippocampal slices from 12-month-old APP(695)SWE transgenic animals displayed reduced levels of synaptic transmission in the CA1 region when compared with wild-type littermate controls. Inclusion of the ionotropic glutamate receptor antagonist kynurenate during preparation of brain slices abolished this deficit. At 18 months of age, a selective deficit in basal synaptic transmission was observed in the CA1 region despite treatment with kynurenate. Paired-pulse facilitation and long-term potentiation (LTP) were normal in APP(695)SWE transgenic mice at both 12 and 18 months of age. Thus, although aged APP(695)SWE transgenic mice have greatly elevated levels of Abeta protein, increased numbers of plaques, and reduced basal synaptic transmission, LTP can still be induced and expressed normally. We conclude that increased susceptibility to excitotoxicity rather than a specific effect on LTP is the primary cause of cognitive deficits in APP(695)SWE mice.
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Affiliation(s)
- S M Fitzjohn
- Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, Bristol, BS8 1TD, United Kingdom.
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826
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El-Agnaf OM, Nagala S, Patel BP, Austen BM. Non-fibrillar oligomeric species of the amyloid ABri peptide, implicated in familial British dementia, are more potent at inducing apoptotic cell death than protofibrils or mature fibrils. J Mol Biol 2001; 310:157-68. [PMID: 11419943 DOI: 10.1006/jmbi.2001.4743] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Familial British dementia (FBD) is an autosomal dominant neurodegenerative disorder, with biochemical and pathological similarities to Alzheimer's disease. FBD is associated with a point mutation in the stop codon of the BRI gene. The mutation extends the length of the wild-type protein by 11 amino acids, and following proteolytic cleavage, results in the production of a cyclic peptide (ABri) 11 amino acids longer than the wild-type (WT) peptide produced from the normal gene BRI. ABri was found to be the main component of amyloid deposits in FBD brains. However, pathological examination of FBD brains has shown the presence of ABri as non-fibrillar deposits as well as amyloid fibrils. Taken together, the genetic, pathological and biochemical data support the hypothesis that ABri deposits play a central role in the pathogenesis of FBD. Here we report that ABri, but not WT peptide, can oligomerise and form amyloid-like fibrils. We show for the first time that ABri induces apoptotic cell death, whereas WT is not toxic to cells. Moreover, we report the novel findings that non-fibrillar oligomeric species of ABri are more toxic than protofibrils and mature fibrils. These findings provide evidence that non-fibrillar oligomeric species are likely to play a critical role in the pathogenesis of FBD and suggest that a similar process may also operate in other neurodegenerative diseases.
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Affiliation(s)
- O M El-Agnaf
- Department of Surgery, Neurodegeneration Unit, St. George's Hospital Medical School, Cranmer Terrace, London, Tooting, SW17 0RE, UK.
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827
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Aksenov MY, Aksenova MV, Butterfield DA, Geddes JW, Markesbery WR. Protein oxidation in the brain in Alzheimer's disease. Neuroscience 2001; 103:373-83. [PMID: 11246152 DOI: 10.1016/s0306-4522(00)00580-7] [Citation(s) in RCA: 349] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In this study we used immunohistochemistry and two-dimensional fingerprinting of oxidatively modified proteins (two-dimensional Oxyblot) together to investigate protein carbonyl formation in the Alzheimer's disease brain. Increased protein oxidation was detected in sections from the hippocampus and parahippocampal gyrus, superior and middle temporal gyri of six Alzheimer's disease and six age-matched control human subjects, but not in the cerebellum. In two brain regions severely affected by Alzheimer's disease pathology, prominent protein carbonyl immunoreactivity was localized in the cytoplasm of neurons without visual pathomorphological changes and degenerating neurons, suggesting that intracellular proteins might be significantly affected by oxidative modifications. Following two-dimensional electrophoresis the positions of some individual proteins were identified using specific antibodies, and immunoblot analysis for protein carbonyls was performed. These studies demonstrated the presence of protein carbonyl immunoreactivity in beta-tubulin, beta-actin and creatine kinase BB in Alzheimer's disease and control brain extracts. Protein carbonyls were undetectable in spots matching glial fibrillary acidic protein and tau isoforms. Specific protein carbonyl levels in beta-actin and creatine kinase BB were significantly higher in Alzheimer's disease than in control brain extract. beta-Tubulin did not demonstrate a significant increase in specific protein carbonyl content in Alzheimer's disease brains. We suggest that oxidative stress-induced injury may involve the selective modification of different intracellular proteins, including key enzymes and structural proteins, which precedes and may lead to the neurofibrillary degeneration of neurons in the Alzheimer's disease brain.
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Affiliation(s)
- M Y Aksenov
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA.
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828
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Chishti MA, Yang DS, Janus C, Phinney AL, Horne P, Pearson J, Strome R, Zuker N, Loukides J, French J, Turner S, Lozza G, Grilli M, Kunicki S, Morissette C, Paquette J, Gervais F, Bergeron C, Fraser PE, Carlson GA, George-Hyslop PS, Westaway D. Early-onset amyloid deposition and cognitive deficits in transgenic mice expressing a double mutant form of amyloid precursor protein 695. J Biol Chem 2001; 276:21562-70. [PMID: 11279122 DOI: 10.1074/jbc.m100710200] [Citation(s) in RCA: 667] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We have created early-onset transgenic (Tg) models by exploiting the synergistic effects of familial Alzheimer's disease mutations on amyloid beta-peptide (Abeta) biogenesis. TgCRND8 mice encode a double mutant form of amyloid precursor protein 695 (KM670/671NL+V717F) under the control of the PrP gene promoter. Thioflavine S-positive Abeta amyloid deposits are present at 3 months, with dense-cored plaques and neuritic pathology evident from 5 months of age. TgCRND8 mice exhibit 3,200-4,600 pmol of Abeta42 per g brain at age 6 months, with an excess of Abeta42 over Abeta40. High level production of the pathogenic Abeta42 form of Abeta peptide was associated with an early impairment in TgCRND8 mice in acquisition and learning reversal in the reference memory version of the Morris water maze, present by 3 months of age. Notably, learning impairment in young mice was offset by immunization against Abeta42 (Janus, C., Pearson, J., McLaurin, J., Mathews, P. M., Jiang, Y., Schmidt, S. D., Chishti, M. A., Horne, P., Heslin, D., French, J., Mount, H. T. J., Nixon, R. A., Mercken, M., Bergeron, C., Fraser, P. E., St. George-Hyslop, P., and Westaway, D. (2000) Nature 408, 979-982). Amyloid deposition in TgCRND8 mice was enhanced by the expression of presenilin 1 transgenes including familial Alzheimer's disease mutations; for mice also expressing a M146L+L286V presenilin 1 transgene, amyloid deposits were apparent by 1 month of age. The Tg mice described here suggest a potential to investigate aspects of Alzheimer's disease pathogenesis, prophylaxis, and therapy within short time frames.
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Affiliation(s)
- M A Chishti
- Centre for Research in Neurodegenerative Diseases, the Department of Laboratory Medicine, Division of Neurology, University Health Network, University of Toronto, Toronto, Ontario M5S 3H2, Canada
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829
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Use-dependent effects of amyloidogenic fragments of (beta)-amyloid precursor protein on synaptic plasticity in rat hippocampus in vivo. J Neurosci 2001. [PMID: 11160403 DOI: 10.1523/jneurosci.21-04-01327.2001] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The Alzheimer's disease-related beta-amyloid precursor protein (beta-APP) is metabolized to a number of potentially amyloidogenic peptides that are believed to be pathogenic. Application of relatively low concentrations of the soluble forms of these peptides has previously been shown to block high-frequency stimulation-induced long-term potentiation (LTP) of glutamatergic transmission in the hippocampus. The present experiments examined how these peptides affect low-frequency stimulation-induced long-term depression (LTD) and the reversal of LTP (depotentiation). We discovered that beta-amyloid peptide (Abeta1-42) and the Abeta-containing C -terminus of beta-APP (CT) facilitate the induction of LTD in the CA1 area of the intact rat hippocampus. The LTD was frequency- and NMDA receptor-dependent. Thus, although low-frequency stimulation alone was ineffective, after intracerebroventricular injection of Abeta1-42, it induced an LTD that was blocked by d-(-)-2-amino-5-phosphonopentanoic acid. Furthermore, an NMDA receptor-dependent depotentiation was induced in a time-dependent manner, being evoked by injection of CT 10 min, but not 1 hr, after LTP induction. These use- and time-dependent effects of the amyloidogenic peptides on synaptic plasticity promote long-lasting reductions in synaptic strength and oppose activity-dependent strengthening of transmission in the hippocampus. This will result in a profound disruption of information processing dependent on hippocampal synaptic plasticity.
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830
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Tong L, Thornton PL, Balazs R, Cotman CW. Beta -amyloid-(1-42) impairs activity-dependent cAMP-response element-binding protein signaling in neurons at concentrations in which cell survival Is not compromised. J Biol Chem 2001; 276:17301-6. [PMID: 11278679 DOI: 10.1074/jbc.m010450200] [Citation(s) in RCA: 175] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cognitive impairment is a major feature of Alzheimer's disease and is accompanied by beta-amyloid (Abeta) deposition. Transgenic animal models that overexpress Abeta exhibit learning and memory impairments, but neuronal degeneration is not a consistent characteristic. We report that levels of Abeta-(1-42), which do not compromise the survival of cortical neurons, may indeed interfere with functions critical for neuronal plasticity. Pretreatment with Abeta-(1-42), at sublethal concentrations, resulted in a suppression of cAMP-response element-binding protein (CREB) phosphorylation, induced by exposure to either 30 mm KCl or 10 microm N-methyl-d-aspartate. The effects of Abeta-(1-42) seem to involve mechanisms unrelated to degenerative changes, since Abeta-(25-35), a toxic fragment of Abeta, at sublethal concentrations did not interfere with activity-dependent CREB phosphorylation. Furthermore, caspase inhibitors failed to counteract the Abeta-(1-42)-evoked suppression of CREB activation. Abeta-(1-42) also interfered with events downstream of activated CREB. The Abeta-(1-42) treatment suppressed the activation of the cAMP response element-containing brain-derived neurotrophic factor (BDNF) exon III promoter and the expression of BDNF exon IIII mRNA induced by neuronal depolarization. In view of the critical role of CREB and BDNF in neuronal plasticity, including learning and memory, the observations indicate a novel pathway through which Abeta may interfere with neuronal functions and contribute to cognitive deficit in Alzheimer's disease before the stage of massive neuronal degeneration.
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Affiliation(s)
- L Tong
- University of California, Irvine Institute for Brain Aging and Dementia, Irvine, California 92697-4540, USA.
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831
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Wyss-Coray T, Lin C, Yan F, Yu GQ, Rohde M, McConlogue L, Masliah E, Mucke L. TGF-beta1 promotes microglial amyloid-beta clearance and reduces plaque burden in transgenic mice. Nat Med 2001; 7:612-8. [PMID: 11329064 DOI: 10.1038/87945] [Citation(s) in RCA: 455] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Abnormal accumulation of the amyloid-beta peptide (Abeta) in the brain appears crucial to pathogenesis in all forms of Alzheimer disease (AD), but the underlying mechanisms in the sporadic forms of AD remain unknown. Transforming growth factor beta1 (TGF-beta1), a key regulator of the brain's responses to injury and inflammation, has been implicated in Abeta deposition in vivo. Here we demonstrate that a modest increase in astroglial TGF-beta1 production in aged transgenic mice expressing the human beta-amyloid precursor protein (hAPP) results in a three-fold reduction in the number of parenchymal amyloid plaques, a 50% reduction in the overall Abeta load in the hippocampus and neocortex, and a decrease in the number of dystrophic neurites. In mice expressing hAPP and TGF-beta1, Abeta accumulated substantially in cerebral blood vessels, but not in parenchymal plaques. In human cases of AD, Abeta immunoreactivity associated with parenchymal plaques was inversely correlated with Abeta in blood vessels and cortical TGF-beta1 mRNA levels. The reduction of parenchymal plaques in hAPP/TGF-beta1 mice was associated with a strong activation of microglia and an increase in inflammatory mediators. Recombinant TGF-beta1 stimulated Abeta clearance in microglial cell cultures. These results demonstrate that TGF-beta1 is an important modifier of amyloid deposition in vivo and indicate that TGF-beta1 might promote microglial processes that inhibit the accumulation of Abeta in the brain parenchyma.
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Affiliation(s)
- T Wyss-Coray
- Gladstone Institute of Neurological Disease, University of California, San Francisco, California, USA.
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832
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Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder that is claiming an increasing number of victims as the world population ages. The identification of gene mutations and polymorphisms that either cause AD or significantly increase the risk for developing it enabled the creation of a whole generation of realistic rodent models of the disease. Animals expressing mutated human amyloid precursor protein and presenilin 1 show dramatic parallels to AD, although none of the models appear to capture the full range of pathologies that characterize the human disease. Increased refinement of these models will enhance the already tantalizing possibility of treatment.
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Affiliation(s)
- P F Chapman
- Cardiff School of Biosciences, Cardiff University, Biomedical Sciences Building, PO Box 911, Cardiff, UK CF10 3US.
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833
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Liu Q, Kawai H, Berg DK. beta -Amyloid peptide blocks the response of alpha 7-containing nicotinic receptors on hippocampal neurons. Proc Natl Acad Sci U S A 2001; 98:4734-9. [PMID: 11274373 PMCID: PMC31903 DOI: 10.1073/pnas.081553598] [Citation(s) in RCA: 256] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2000] [Indexed: 11/18/2022] Open
Abstract
Alzheimer's disease produces a devastating decline in mental function, with profound effects on learning and memory. Early consequences of the disease include the specific loss of cholinergic neurons in brain, diminished cholinergic signaling, and the accumulation of beta-amyloid peptide in neuritic plaques. Of the nicotinic acetylcholine receptors at risk, the most critical may be those containing the alpha7 gene product (alpha7-nAChRs), because they are widespread, have a high relative permeability to calcium, and regulate numerous cellular events in the nervous system. With the use of whole-cell patch-clamp recording we show here that nanomolar concentrations of beta-amyloid peptides specifically and reversibly block alpha7-nAChRs on rat hippocampal neurons in culture. The block is noncompetitive, voltage-independent, and use-independent and is mediated through the N-terminal extracellular domain of the receptor. It does not appear to require either calcium influx or G protein activation. beta-Amyloid blockade is likely to be a common feature of alpha7-nAChRs because it applies to the receptors at both somato-dendritic and presynaptic locations on rat hippocampal neurons and extends to homologous receptors on chick ciliary ganglion neurons as well. Because alpha7-nAChRs in the central nervous system are thought to have numerous functions and recently have been implicated in learning and memory, impaired receptor function in this case may contribute to cognitive deficits associated with Alzheimer's disease.
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Affiliation(s)
- Q Liu
- Neurobiology Section, Division of Biology, University of California at San Diego, La Jolla, CA 92093-0357, USA
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834
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Abstract
Rapid progress in deciphering the biological mechanism of Alzheimer's disease (AD) has arisen from the application of molecular and cell biology to this complex disorder of the limbic and association cortices. In turn, new insights into fundamental aspects of protein biology have resulted from research on the disease. This beneficial interplay between basic and applied cell biology is well illustrated by advances in understanding the genotype-to-phenotype relationships of familial Alzheimer's disease. All four genes definitively linked to inherited forms of the disease to date have been shown to increase the production and/or deposition of amyloid beta-protein in the brain. In particular, evidence that the presenilin proteins, mutations in which cause the most aggressive form of inherited AD, lead to altered intramembranous cleavage of the beta-amyloid precursor protein by the protease called gamma-secretase has spurred progress toward novel therapeutics. The finding that presenilin itself may be the long-sought gamma-secretase, coupled with the recent identification of beta-secretase, has provided discrete biochemical targets for drug screening and development. Alternate and novel strategies for inhibiting the early mechanism of the disease are also emerging. The progress reviewed here, coupled with better ability to diagnose the disease early, bode well for the successful development of therapeutic and preventative drugs for this major public health problem.
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Affiliation(s)
- D J Selkoe
- Department of Neurology and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts, USA
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835
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Turner RS. Alzheimer's disease in man and transgenic mice: females at higher risk. THE AMERICAN JOURNAL OF PATHOLOGY 2001; 158:797-801. [PMID: 11238027 PMCID: PMC1850377 DOI: 10.1016/s0002-9440(10)64026-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/03/2001] [Indexed: 02/04/2023]
Affiliation(s)
- R S Turner
- Department of Neurology, University of Michigan, Ann Arbor, MI 48105, USA.
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836
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Selkoe DJ. Toward a comprehensive theory for Alzheimer's disease. Hypothesis: Alzheimer's disease is caused by the cerebral accumulation and cytotoxicity of amyloid beta-protein. Ann N Y Acad Sci 2001; 924:17-25. [PMID: 11193794 DOI: 10.1111/j.1749-6632.2000.tb05554.x] [Citation(s) in RCA: 493] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A central challenge of research on Alzheimer's disease (AD) is to assemble the enormous body of scientific observations about the disorder, some of them seemingly in conflict with others, into a coherent and credible mechanism of pathogenesis. In this article, I attempt to synthesize the disparate findings on AD into a unified sequence that essentially begins with alterations in the production or clearance of the amyloid beta-protein (A beta). Mounting evidence from many laboratories supports an A beta accumulation in limbic and association cortices as the fundamental initiator of the disease, with attendant therapeutic implications.
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Affiliation(s)
- D J Selkoe
- Department of Neurology, Harvard Medical School, and Center for Neurologic Diseases, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
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837
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Kim JH, Anwyl R, Suh YH, Djamgoz MB, Rowan MJ. Use-dependent effects of amyloidogenic fragments of (beta)-amyloid precursor protein on synaptic plasticity in rat hippocampus in vivo. J Neurosci 2001; 21:1327-33. [PMID: 11160403 PMCID: PMC6762223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
The Alzheimer's disease-related beta-amyloid precursor protein (beta-APP) is metabolized to a number of potentially amyloidogenic peptides that are believed to be pathogenic. Application of relatively low concentrations of the soluble forms of these peptides has previously been shown to block high-frequency stimulation-induced long-term potentiation (LTP) of glutamatergic transmission in the hippocampus. The present experiments examined how these peptides affect low-frequency stimulation-induced long-term depression (LTD) and the reversal of LTP (depotentiation). We discovered that beta-amyloid peptide (Abeta1-42) and the Abeta-containing C -terminus of beta-APP (CT) facilitate the induction of LTD in the CA1 area of the intact rat hippocampus. The LTD was frequency- and NMDA receptor-dependent. Thus, although low-frequency stimulation alone was ineffective, after intracerebroventricular injection of Abeta1-42, it induced an LTD that was blocked by d-(-)-2-amino-5-phosphonopentanoic acid. Furthermore, an NMDA receptor-dependent depotentiation was induced in a time-dependent manner, being evoked by injection of CT 10 min, but not 1 hr, after LTP induction. These use- and time-dependent effects of the amyloidogenic peptides on synaptic plasticity promote long-lasting reductions in synaptic strength and oppose activity-dependent strengthening of transmission in the hippocampus. This will result in a profound disruption of information processing dependent on hippocampal synaptic plasticity.
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Affiliation(s)
- J H Kim
- Departments of Pharmacology, Trinity College, Dublin 2, Ireland
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838
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Cha JH, Farrell LA, Ahmed SF, Frey A, Hsiao-Ashe KK, Young AB, Penney JB, Locascio JJ, Hyman BT, Irizarry MC. Glutamate receptor dysregulation in the hippocampus of transgenic mice carrying mutated human amyloid precursor protein. Neurobiol Dis 2001; 8:90-102. [PMID: 11162243 DOI: 10.1006/nbdi.2000.0330] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Alzheimer's disease transgenic mice overexpressing human amyloid precursor protein (hAPP) with the Swedish double mutation (hAPP(Sw)) develop age-related amyloid deposition and behavioral and electrophysiologic changes by an unknown mechanism. Analysis of glutamatergic receptor subtypes in 4- and 15-month-old heterozygous hAPP(Sw) transgenic mice revealed a selective increase in AMPA receptor binding in the hippocampus of 15-month-old transgenic mice, which have established cortical and hippocampal amyloid deposits. There were no significant alterations of GluR1, GluR2, and GluR4 protein expression by semiquantitative confocal analysis or GluR1 mRNA by in situ hybridization. There was no significant alteration in NMDA, in group I and II metabotropic glutamate and in muscarinic receptor binding, or in striatal dopamine and adenosine receptor binding in 15-month-old mice. These data suggest that mutant APP overexpression or age-related amyloid deposition produce a subtle specific alteration in hippocampal glutamate receptors with aging.
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MESH Headings
- Amyloid beta-Protein Precursor/genetics
- Amyloid beta-Protein Precursor/metabolism
- Animals
- Autoradiography
- Cholinesterases/metabolism
- Hippocampus/enzymology
- Hippocampus/metabolism
- Humans
- In Situ Hybridization
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Mutation
- Receptors, AMPA/genetics
- Receptors, AMPA/metabolism
- Receptors, Dopamine/metabolism
- Receptors, Glutamate/genetics
- Receptors, Glutamate/metabolism
- Receptors, Metabotropic Glutamate/genetics
- Receptors, Metabotropic Glutamate/metabolism
- Receptors, Muscarinic/genetics
- Receptors, Muscarinic/metabolism
- Receptors, N-Methyl-D-Aspartate/genetics
- Receptors, N-Methyl-D-Aspartate/metabolism
- Receptors, Purinergic P1/metabolism
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Affiliation(s)
- J H Cha
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
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839
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Freir DB, Holscher C, Herron CE. Blockade of long-term potentiation by beta-amyloid peptides in the CA1 region of the rat hippocampus in vivo. J Neurophysiol 2001; 85:708-13. [PMID: 11160505 DOI: 10.1152/jn.2001.85.2.708] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of intracerebroventricular (icv) injections of beta-amyloid peptide fragments Abeta[15-25], Abeta[25-35], and Abeta[35-25] were examined on synaptic transmission and long-term potentiation (LTP) in the hippocampal CA1 region in vivo. Rats were anesthetized using urethan, and changes in synaptic efficacy were determined from the slope of the excitatory postsynaptic potential (EPSP). Baseline synaptic responses were monitored for 30 min prior to icv injection of Abeta peptides or vehicle. High-frequency stimulation (HFS) to induce LTP was applied to the Schaffer-collateral pathway 5 min or 1 h following the icv injection. HFS comprised 3 episodes of 10 stimuli at 200 Hz, 10 times, applied at 30-s intervals. Normal LTP measured 30 min following HFS, was produced following icv injection of vehicle (191 +/- 17%, mean +/- SE, n = 6) or Abeta[15-25; 100 nmol] (177 +/- 6%, n = 6) 1 h prior to HFS. LTP was, however, markedly reduced by Abeta[25-35; 10 nmol] (129 +/- 9%, n = 6, P < 0.001) and blocked by Abeta[25-35; 100 nmol] (99 +/- 6%, n = 6, P < 0.001). Injection of the reverse peptide, Abeta[35-25], also impaired LTP at concentrations of 10 nmol (136 +/- 3%, n = 6, P < 0.01) and 100 nmol (144 +/- 7, n = 8, P < 0.05). Using a different protocol, HFS was delivered 5 min following Abeta injections, and LTP was measured 1 h post HFS. Stable LTP was produced in the control group (188 +/- 15%, n = 7) and blocked by Abeta[25-35, 100 nmol] (108 +/- 15%, n = 6, P < 0.001). A lower dose of Abeta[25-35; 10 nmol] did not significantly impair LTP (176 +/- 30%, n = 4). The Abeta-peptides tested were also shown to have no significant effect on paired pulse facilitation (interstimulus interval of 50 ms), suggesting that neither presynaptic transmitter release or activity of interneurons in vivo are affected. The effects of Abeta on LTP are therefore likely to be mediated via a postsynaptic mechanism. This in vivo model of LTP is extremely sensitive to Abeta-peptides that can impair LTP in a time- ([25-35]) and concentration-dependent manner ([25-35] and [35-25]). These effects of Abeta-peptides may then contribute to the cognitive deficits associated with Alzheimer's disease.
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Affiliation(s)
- D B Freir
- Department of Human Anatomy and Physiology, University College Dublin, Dublin 2, Ireland
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840
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Janus C, Pearson J, McLaurin J, Mathews PM, Jiang Y, Schmidt SD, Chishti MA, Horne P, Heslin D, French J, Mount HT, Nixon RA, Mercken M, Bergeron C, Fraser PE, St George-Hyslop P, Westaway D. A beta peptide immunization reduces behavioural impairment and plaques in a model of Alzheimer's disease. Nature 2000; 408:979-82. [PMID: 11140685 DOI: 10.1038/35050110] [Citation(s) in RCA: 1061] [Impact Index Per Article: 44.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Much evidence indicates that abnormal processing and extracellular deposition of amyloid-beta peptide (A beta), a proteolytic derivative of the beta-amyloid precursor protein (betaAPP), is central to the pathogenesis of Alzheimer's disease (reviewed in ref. 1). In the PDAPP transgenic mouse model of Alzheimer's disease, immunization with A beta causes a marked reduction in burden of the brain amyloid. Evidence that A beta immunization also reduces cognitive dysfunction in murine models of Alzheimer's disease would support the hypothesis that abnormal A beta processing is essential to the pathogenesis of Alzheimer's disease, and would encourage the development of other strategies directed at the 'amyloid cascade'. Here we show that A beta immunization reduces both deposition of cerebral fibrillar A beta and cognitive dysfunction in the TgCRND8 murine model of Alzheimer's disease without, however, altering total levels of A beta in the brain. This implies that either a approximately 50% reduction in dense-cored A beta plaques is sufficient to affect cognition, or that vaccination may modulate the activity/abundance of a small subpopulation of especially toxic A beta species.
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Affiliation(s)
- C Janus
- Centre for Research in Neurodegenerative Diseases, Department of Medicine, University of Toronto, Ontario, Canada
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841
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Mucke L, Yu GQ, McConlogue L, Rockenstein EM, Abraham CR, Masliah E. Astroglial expression of human alpha(1)-antichymotrypsin enhances alzheimer-like pathology in amyloid protein precursor transgenic mice. THE AMERICAN JOURNAL OF PATHOLOGY 2000; 157:2003-10. [PMID: 11106573 PMCID: PMC1885780 DOI: 10.1016/s0002-9440(10)64839-0] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/08/2000] [Indexed: 01/10/2023]
Abstract
Proteases and their inhibitors play key roles in physiological and pathological processes. Cerebral amyloid plaques are a pathological hallmark of Alzheimer's disease (AD). They contain amyloid-ss (Ass) peptides in tight association with the serine protease inhibitor alpha(1)-antichymotrypsin.(1,2) However, it is unknown whether the increased expression of alpha(1)-antichymotrypsin found in AD brains counteracts or contributes to the disease. We used regulatory sequences of the glial fibrillary acidic protein gene(3) to express human alpha(1)-antichymotrypsin (hACT) in astrocytes of transgenic mice. These mice were crossed with transgenic mice that produce human amyloid protein precursors (hAPP) and Ass in neurons.(4,5) No amyloid plaques were found in transgenic mice expressing hACT alone, whereas hAPP transgenic mice and hAPP/hACT doubly transgenic mice developed typical AD-like amyloid plaques in the hippocampus and neocortex around 6 to 8 months of age. Co-expression of hAPP and hACT significantly increased the plaque burden at 7 to 8, 14, and 20 months. Both hAPP and hAPP/hACT mice showed significant decreases in synaptophysin-immunoreactive presynaptic terminals in the dentate gyrus, compared with nontransgenic littermates. Our results demonstrate that hACT acts as an amyloidogenic co-factor in vivo and suggest that the role of hACT in AD is pathogenic.
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Affiliation(s)
- L Mucke
- Gladstone Institute of Neurological Disease, Department of Neurology, and Neuroscience Program, University of California San Francisco, San Francisco, California, USA.
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842
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Woolley AT, Cheung CL, Hafner JH, Lieber CM. Structural biology with carbon nanotube AFM probes. CHEMISTRY & BIOLOGY 2000; 7:R193-204. [PMID: 11094343 DOI: 10.1016/s1074-5521(00)00037-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Carbon nanotubes represent ideal probes for high-resolution structural and chemical imaging of biomolecules with atomic force microscopy. Recent advances in fabrication of carbon nanotube probes with sub-nanometer radii promise to yield unique insights into the structure, dynamics and function of biological macromolecules and complexes.
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Affiliation(s)
- A T Woolley
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
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843
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Longo VD, Viola KL, Klein WL, Finch CE. Reversible inactivation of superoxide-sensitive aconitase in Abeta1-42-treated neuronal cell lines. J Neurochem 2000; 75:1977-85. [PMID: 11032887 DOI: 10.1046/j.1471-4159.2000.0751977.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The activity of the superoxide-sensitive enzyme aconitase was monitored to evaluate the generation of superoxide in neuronal cell lines treated with beta-amyloid (Abeta) peptide 1-42. Treatment of differentiated and undifferentiated rat PC12 and human neuroblastoma SK-N-SH cells with soluble Abeta1-42 (Abeta-derived diffusible ligands) or fibrillar Abeta1-42 caused a 35% reversible inactivation of aconitase, which preceded loss of viability and was correlated with altered cellular function. Aconitase was reactivated upon incubation of cellular extracts with iron and sulfur, suggesting that Abeta causes the release of iron from 4Fe-4S clusters. Abeta neurotoxicity was partially blocked by the iron chelator deferoxamine. These data suggest that increased superoxide generation and the release of iron from 4Fe-4S clusters are early events in Abeta1-42 neurotoxicity.
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Affiliation(s)
- V D Longo
- Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, California 90089-0191, USA.
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844
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Giacchino J, Criado JR, Games D, Henriksen S. In vivo synaptic transmission in young and aged amyloid precursor protein transgenic mice. Brain Res 2000; 876:185-90. [PMID: 10973607 DOI: 10.1016/s0006-8993(00)02615-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Alzheimer's disease (AD) is characterized by progressive neurodegeneration and cognitive impairment. We examined in vivo alterations in hippocampal neurotransmission in both young and aged PDAPP transgenic mice and nontransgenic littermates. We now report that in vivo abnormal neurotransmission in hippocampal circuits of PDAPP mice precedes beta deposition and neurodegeneration. These in vivo data provide the first evidence that dysfunction in hippocampal neuronal circuits may not be correlated with age-related extracellular beta plaque deposition.
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Affiliation(s)
- J Giacchino
- Department of Neuropharmacology (CVN-13), The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037, USA
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845
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Lefterov IM, Koldamova RP, Lazo JS. Human bleomycin hydrolase regulates the secretion of amyloid precursor protein. FASEB J 2000; 14:1837-47. [PMID: 10973933 DOI: 10.1096/fj.99-0938com] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Human bleomycin hydrolase (hBH) is a neutral cysteine protease genetically associated with increased risk for Alzheimer disease. We show here that ectopic expression of hBH in 293APPwt and CHOAPPsw cells altered the processing of amyloid precursor protein (APP) and increased significantly the release of its proteolytic fragment, beta amyloid (Abeta). We also found that hBH interacted and colocalized with APP as determined by subcellular fractionation, in vitro binding assay, and confocal immunolocalization. Metabolic labeling and pulse-chase experiments showed that ectopic hBH expression increased secretion of soluble APPalpha/beta products without changing the half-life of cellular APP. We also observed that this increased Abeta secretion was independent of hBH isoforms. Our findings suggest a regulatory role for hBH in APP processing pathways.
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Affiliation(s)
- I M Lefterov
- Department of Pharmacology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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846
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Minamide LS, Striegl AM, Boyle JA, Meberg PJ, Bamburg JR. Neurodegenerative stimuli induce persistent ADF/cofilin-actin rods that disrupt distal neurite function. Nat Cell Biol 2000; 2:628-36. [PMID: 10980704 DOI: 10.1038/35023579] [Citation(s) in RCA: 285] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Inclusions containing actin-depolymerizing factor (ADF) and cofilin, abundant proteins in adult human brain, are prominent in hippocampal and cortical neurites of the post-mortem brains of Alzheimer's patients, especially in neurites contacting amyloid deposits. The origin and role of these inclusions in neurodegeneration are, however, unknown. Here we show that mediators of neurodegeneration induce the rapid formation of transient or persistent rod-like inclusions containing ADF/cofilin and actin in axons and dendrites of cultured hippocampal neurons. Rods form spontaneously within neurons overexpressing active ADF/cofilin, suggesting that the activation (by dephosphorylation) of ADF/cofilin that occurs in response to neurodegenerative stimuli is sufficient to induce rod formation. Persistent rods that span the diameter of the neurite disrupt microtubules and cause degeneration of the distal neurite without killing the neuron. These findings suggest a common pathway that can lead to loss of synapses.
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Affiliation(s)
- L S Minamide
- Department of Biochemistry and Molecular Biology, and the Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado 80523-1870, USA
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847
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848
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Chapman RS, Hesketh LJ. Behavioral phenotype of individuals with Down syndrome. MENTAL RETARDATION AND DEVELOPMENTAL DISABILITIES RESEARCH REVIEWS 2000; 6:84-95. [PMID: 10899801 DOI: 10.1002/1098-2779(2000)6:2<84::aid-mrdd2>3.0.co;2-p] [Citation(s) in RCA: 338] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Evidence is reviewed for a developmentally-emerging behavioral phenotype in individuals with Down syndrome that includes significant delay in nonverbal cognitive development accompanied by additional, specific deficits in speech, language production, and auditory short-term memory in infancy and childhood, but fewer adaptive behavior problems than individuals with other cognitive disabilities. Evidence of dementia emerges for up to half the individuals studied after age 50. Research issues affecting control group selection in establishing phenotypic characteristics are discussed, as well as the possible genetic mechanisms underlying variation in general cognitive delay, specific language impairment, and adult dementia. MRDD Research Reviews 2000;6:84-95. Wiley-Liss, Inc.
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Affiliation(s)
- R S Chapman
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.
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849
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Abstract
Alzheimer's disease (AD), characterized by neuritic plaques and neurofibrillary tangles of the brain, is experienced by more and more elderly people in a form of senile dementia. Four genes are closely linked with AD and are located on chromosomes 21, 19, 14 and 1. Transgenic technology enables the development of animal models for research into this human disease. Recently reported transgenic AD mouse models, which express AD-related mutant human genes, develop some significant aspects of AD-like pathology. The specific role of these mice in representing different targets, the consequent pathology of AD and the availability of this increasingly popular tool for investigating new therapeutic strategies for AD are reviewed.
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Affiliation(s)
- P Yu
- General Toxicology I Unit, Istituto di Ricerche Biomediche 'A. Marxer' LCG RBM S.p.A, Via Ribes 1, 10010 Colleretto Giacosa (TO), Italy
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850
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Roher AE, Baudry J, Chaney MO, Kuo YM, Stine WB, Emmerling MR. Oligomerizaiton and fibril asssembly of the amyloid-beta protein. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1502:31-43. [PMID: 10899429 DOI: 10.1016/s0925-4439(00)00030-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In this chapter, we attempt to analyze the evolution of the amyloid-beta (Abeta) molecular structure from its inception as part of the Abeta precursor protein to its release by the secretases and its extrusion from membrane into an aqueous environment. Biophysical studies suggest that the Abeta peptide sustains a series of transitions from a molecule rich in alpha-helix to a molecule in which beta-strands prevail. It is proposed that initially the extended C-termini of two opposing Abeta dimers form an antiparallel beta-sheet and that the subsequent addition of dimers generates a helical Abeta protofilament. Two or more protofilaments create a strand in which the hydrophobic core of the beta-sheets is shielded from the aqueous environment by the N-terminal polar domains of the Abeta dimers. Once the nucleation has occurred, the Abeta filament grows in length by the addition of dimers or tetramers.
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Affiliation(s)
- A E Roher
- Haldeman Laboratory for Alzheimer's Disease Research, Sun Health Research Institute, Sun City, AZ 85351, USA.
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