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Min JH, Sarlus H, Harris RA. Glycyl-l-histidyl-l-lysine prevents copper- and zinc-induced protein aggregation and central nervous system cell death in vitro. Metallomics 2024; 16:mfae019. [PMID: 38599632 PMCID: PMC11135135 DOI: 10.1093/mtomcs/mfae019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 04/09/2024] [Indexed: 04/12/2024]
Abstract
Common features of neurodegenerative diseases are oxidative and inflammatory imbalances as well as the misfolding of proteins. An excess of free metal ions can be pathological and contribute to cell death, but only copper and zinc strongly promote protein aggregation. Herein we demonstrate that the endogenous copper-binding tripeptide glycyl-l-histidyl-l-lysine (GHK) has the ability to bind to and reduce copper redox activity and to prevent copper- and zinc-induced cell death in vitro. In addition, GHK prevents copper- and zinc-induced bovine serum albumin aggregation and reverses aggregation through resolubilizing the protein. We further demonstrate the enhanced toxicity of copper during inflammation and the ability of GHK to attenuate this toxicity. Finally, we investigated the effects of copper on enhancing paraquat toxicity and report a protective effect of GHK. We therefore conclude that GHK has potential as a cytoprotective compound with regard to copper and zinc toxicity, with positive effects on protein solubility and aggregation that warrant further investigation in the treatment of neurodegenerative diseases.
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Affiliation(s)
- Jin-Hong Min
- Department of Clinical Neuroscience, Karolinska Institutet, Center for Molecular Medicine, Karolinska University Hospital, S-171 76 Stockholm, Sweden
| | - Heela Sarlus
- Department of Clinical Neuroscience, Karolinska Institutet, Center for Molecular Medicine, Karolinska University Hospital, S-171 76 Stockholm, Sweden
| | - Robert A Harris
- Department of Clinical Neuroscience, Karolinska Institutet, Center for Molecular Medicine, Karolinska University Hospital, S-171 76 Stockholm, Sweden
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2
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Wu J, Blum TB, Farrell DP, DiMaio F, Abrahams JP, Luo J. Cryo-electron Microscopy Imaging of Alzheimer's Amyloid-beta 42 Oligomer Displayed on a Functionally and Structurally Relevant Scaffold. Angew Chem Int Ed Engl 2021; 60:18680-18687. [PMID: 34042235 PMCID: PMC8457241 DOI: 10.1002/anie.202104497] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Indexed: 02/06/2023]
Abstract
Amyloid-β peptide (Aβ) oligomers are pathogenic species of amyloid aggregates in Alzheimer's disease. Like certain protein toxins, Aβ oligomers permeabilize cellular membranes, presumably through a pore formation mechanism. Owing to their structural and stoichiometric heterogeneity, the structure of these pores remains to be characterized. We studied a functional Aβ42-pore equivalent, created by fusing Aβ42 to the oligomerizing, soluble domain of the α-hemolysin (αHL) toxin. Our data reveal Aβ42-αHL oligomers to share major structural, functional, and biological properties with wild-type Aβ42-pores. Single-particle cryo-EM analysis of Aβ42-αHL oligomers (with an overall 3.3 Å resolution) reveals the Aβ42-pore region to be intrinsically flexible. The Aβ42-αHL oligomers will allow many of the features of the wild-type amyloid oligomers to be studied that cannot be otherwise, and may be a highly specific antigen for the development of immuno-base diagnostics and therapies.
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Affiliation(s)
- Jinming Wu
- Department of Biology and ChemistryPaul Scherrer Institute5232VilligenSwitzerland
| | - Thorsten B. Blum
- Department of Biology and ChemistryPaul Scherrer Institute5232VilligenSwitzerland
| | - Daniel P Farrell
- Department of BiochemistryUniversity of WashingtonSeattleWA98195USA
- Institute for Protein DesignUniversity of WashingtonSeattleWA98195USA
| | - Frank DiMaio
- Department of BiochemistryUniversity of WashingtonSeattleWA98195USA
- Institute for Protein DesignUniversity of WashingtonSeattleWA98195USA
| | - Jan Pieter Abrahams
- Department of Biology and ChemistryPaul Scherrer Institute5232VilligenSwitzerland
- BiozentrumUniversity of Basel4058BaselSwitzerland
| | - Jinghui Luo
- Department of Biology and ChemistryPaul Scherrer Institute5232VilligenSwitzerland
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3
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Cryo‐electron Microscopy Imaging of Alzheimer's Amyloid‐beta 42 Oligomer Displayed on a Functionally and Structurally Relevant Scaffold. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202104497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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4
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Longhena F, Spano P, Bellucci A. Targeting of Disordered Proteins by Small Molecules in Neurodegenerative Diseases. Handb Exp Pharmacol 2018; 245:85-110. [PMID: 28965171 DOI: 10.1007/164_2017_60] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The formation of protein aggregates and inclusions in the brain and spinal cord is a common neuropathological feature of a number of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and many others. These are commonly referred as neurodegenerative proteinopathies or protein-misfolding diseases. The main characteristic of protein aggregates in these disorders is the fact that they are enriched in amyloid fibrils. Since protein aggregation is considered to play a central role for the onset of neurodegenerative proteinopathies, research is ongoing to develop strategies aimed at preventing or removing protein aggregation in the brain of affected patients. Numerous studies have shown that small molecule-based approaches may be potentially the most promising for halting protein aggregation in neurodegenerative diseases. Indeed, several of these compounds have been found to interact with intrinsically disordered proteins and promote their clearing in experimental models. This notwithstanding, at present small molecule inhibitors still awaits achievements for clinical translation. Hopefully, if we determine whether the formation of insoluble inclusions is effectively neurotoxic and find a valid biomarker to assess their protein aggregation-inhibitory activity in the human central nervous system, the use of small molecule inhibitors will be considered as a cure for neurodegenerative protein-misfolding diseases.
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Affiliation(s)
- Francesca Longhena
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa No. 11, Brescia, 25123, Italy
| | - PierFranco Spano
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa No. 11, Brescia, 25123, Italy
| | - Arianna Bellucci
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa No. 11, Brescia, 25123, Italy.
- Laboratory of Personalized and Preventive Medicine, University of Brescia, Brescia, Italy.
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5
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Steele JW, Gandy S. Apomorphine and Alzheimer Aβ: roles for regulated α cleavage, autophagy, and antioxidation? Ann Neurol 2011; 69:221-5. [PMID: 21387363 DOI: 10.1002/ana.22359] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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6
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Du D, Murray AN, Cohen E, Kim HE, Simkovsky R, Dillin A, Kelly JW. A kinetic aggregation assay allowing selective and sensitive amyloid-β quantification in cells and tissues. Biochemistry 2011; 50:1607-17. [PMID: 21268584 DOI: 10.1021/bi1013744] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The process of amyloid-β (Aβ) fibril formation is genetically and pathologically linked to Alzheimer's disease (AD). Thus, a selective and sensitive method for quantifying Aβ fibrils in complex biological samples allows a variety of hypotheses to be tested. Herein, we report the basis for a quantitative in vitro kinetic aggregation assay that detects seeding-competent Aβ aggregates in mammalian cell culture media, in Caenorhabditis elegans lysate, and in mouse brain homogenate. Sonicated, proteinase K-treated Aβ fibril-containing tissue homogenates or cell culture media were added to an initially monomeric Aβ(1-40) reporter peptide to seed an in vitro nucleated aggregation reaction. The reduction in the half-time (t(50)) of the amyloid growth phase is proportional to the quantity of seeding-competent Aβ aggregates present in the biological sample. An ion-exchange resin amyloid isolation strategy from complex biological samples is demonstrated as an alternative for improving the sensitivity and linearity of the kinetic aggregation assay.
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Affiliation(s)
- Deguo Du
- Howard Hughes Medical Institute, Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, California 92037, United States
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7
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Botev A, Munter LM, Wenzel R, Richter L, Althoff V, Ismer J, Gerling U, Weise C, Koksch B, Hildebrand PW, Bittl R, Multhaup G. The amyloid precursor protein C-terminal fragment C100 occurs in monomeric and dimeric stable conformations and binds γ-secretase modulators. Biochemistry 2011; 50:828-35. [PMID: 21186781 DOI: 10.1021/bi1014002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The amyloid-β (Aβ) peptide is contained within the C-terminal fragment (β-CTF) of the amyloid precursor protein (APP) and is intimately linked to Alzheimer's disease. In vivo, Aβ is generated by sequential cleavage of β-CTF within the γ-secretase module. To investigate γ-secretase function, in vitro assays are in widespread use which require a recombinant β-CTF substrate expressed in bacteria and purified from inclusion bodies, termed C100. So far, little is known about the conformation of C100 under different conditions of purification and refolding. Since C100 dimerization influences the efficiency and specificity of γ-secretase cleavage, it is also of great interest to determine the secondary structure and the oligomeric state of the synthetic substrate as well as the binding properties of small molecules named γ-secretase modulators (GSMs) which we could previously show to modulate APP transmembrane sequence interactions [Richter et al. (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 14597-14602]. Here, we use circular dichroism and continuous-wave electron spin resonance measurements to show that C100 purified in a buffer containing SDS at micelle-forming concentrations adopts a highly stable α-helical conformation, in which it shows little tendency to aggregate or to form higher oligomers than dimers. By surface plasmon resonance analysis and molecular modeling we show that the GSM sulindac sulfide binds to C100 and has a preference for C100 dimers.
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Affiliation(s)
- Anne Botev
- Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
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8
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Formation of amyloid-beta oligomers in brain vascular smooth muscle cells transiently exposed to iron-induced oxidative stress. Acta Neuropathol 2009; 117:557-67. [PMID: 19221770 DOI: 10.1007/s00401-009-0497-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 02/06/2009] [Accepted: 02/08/2009] [Indexed: 12/22/2022]
Abstract
Vascular smooth muscle cells are involved in deposition of amyloid in brain blood vessels. Accumulation of amyloid-beta peptide (Abeta) in cultured brain vascular smooth muscle cells that overexpress human amyloid-beta precursor protein (APP) Swedish, is strongly enhanced by exposure to iron ions. We studied cellular accumulation of Abeta and APP processing in vascular smooth muscle cells during recovery after exposure to ferrous ions using cells cultured from Tg2576 mice. The treatment with ferrous ions for 24 and 48 h significantly increased the intracellular levels of ferric, but not ferrous iron. The treatment led to cellular accumulation of C-terminal fragments of APP and to a decreased secretion of APP, Abeta1-40, and Abeta1-42, all of which were quickly normalized in iron-free culture conditions. These effects of iron were neutralized by alpha-tocopherol, suggesting the role of oxygen reactive species in altered APP processing. Formation of abundant Abeta oligomers, mainly Abeta1-40 tetramers and pentamers, were detected in iron-treated cells, particularly during subsequent culture in iron-free media for up to 72 h. The data suggest that transient increases in local availability of iron in brain blood vessel walls in vivo, e.g., after microhemorrhages, may trigger Abeta oligomerization.
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9
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Bolukbasi Hatip FF, Matsunaga Y, Yamada T. Specific reactivity of mild/severe Alzheimer's disease patient's sera to antibody against Abeta1-40 epitope 17-21. Acta Neurol Scand 2008; 117:404-8. [PMID: 18005218 DOI: 10.1111/j.1600-0404.2007.00959.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To detect the reactivity pattern of sera from patients with mild and severe Alzheimer's disease (AD) to specific antibodies targeting different epitopes in the primary structure of amyloid-beta (Abeta). MATERIALS AND METHODS Sera from patients diagnosed with mild or severe AD were used. The reactivity of sera to monoclonal antibodies recognizing 1-7, 5-10, 9-14 and 17-21 epitopes of Abeta1-40 at 36-42 degrees C was determined by an enzyme-linked immunosorbent assay. Proteinase K digestion of Abeta1-40 was investigated by dot blotting at 36 and 40 degrees C. RESULTS Sera of patients with AD displayed reactivity only with monoclonal antibody recognizing the epitope 17-21 (4G8). The reactivity of sera from patients with severe AD was less than that of sera from patients with mild AD at temperatures 36-41 degrees C, with no difference at 42 degrees C. Patients with severe AD displayed lesser digestion with proteinase K. CONCLUSIONS Sera derived from patients with AD could react with monoclonal antibodies directed to 17-21 sequences of Abeta1-40 in a temperature-dependent manner. The severity of AD is associated with greater Abeta1-40 aggregation and resistance to proteinase K. The present results may be of value in staging and following up of patients with AD.
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Affiliation(s)
- F F Bolukbasi Hatip
- Department of Pharmacology, Faculty of Medicine, Pamukkale University, Kinikli Campus, Denizli, Turkey
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10
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Yang ZQ, Yang SF, Yang JQ, Zhou QX, Li SL. Protective effects and mechanism of total coptis alkaloids on A β25–35 induced learning and memory dysfunction in rats. Chin J Integr Med 2007; 13:50-4. [PMID: 17578319 DOI: 10.1007/s11655-007-0050-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To observe the effect of total coptis alkaloids (TCA) on beta -amyloid peptide (A beta 25-35) induced learning and memory dysfunction in rats, and to explore its mechanism. METHODS Forty male Wistar rats were randomly divided into four groups: the control group, the model group, the TCA low dose (60 mg/kg) group and the TCA high dose (120 mg/kg) group, 10 in each. A beta 25-35 (5microl, 2 microg/microl) was injected into bilateral hippocampi of each rat to induce learning and memory dysfunction. TCA were administered through intragavage for consecutive 15 days. Morris Water Maze test was used to assess the impairment of learning and memory; concentration of malondialdehyde (MDA) in cerebral cortex was determined by thiobarbituric acid reactive substance to indicate the level of lipid peroxidation in brain tissues; activity of manganese-superoxide dismutase (Mn-SOD) in cerebral cortex was determined by xanthine-oxidase to indicate the activity of the enzyme; and NF- kappa B protein expression in cerebral cortex was measured by SP immunohistochemistry. RESULTS (1) Morris Water Maze test showed that, during the 4 consecutive days of acquisition trials, the rats in the model group took longer latency and searching distance than those in the control group (P<0.01), which could be shortened by high dose TCA (P<0.05); during the spatial probe trial on the fifth day, the rats in the model group took shorter searching time and distance on the previous flat area than those in the control group (P<0.01), which could be prolonged after TCA treatment (for low dose group, P<0.05; for high dose group, P<0.01). (2) Analysis of cerebral cortical tissues showed that, compared with the control group, MDA level got significantly increased and Mn-SOD activity decreased in the model group (both P<0.01). After having been treated with TCA, the MDA level got significantly decreased (P<0.05 and P<0.01 respectively for low and high dose group), while relative increase of Mn-SOD activity only appeared in high dose group (P<0.05). (3) Immunohistochemistry analysis showed the protein expression of NF- kappa B got significantly increased after modeling, while high dose TCA can significantly inhibit it. CONCLUSION TCA could improve A beta 25-35 induced dysfunction of learning and memory in rats, and its protective mechanism is associated with its actions in decreasing MDA level, increasing Mn-SOD activity and inhibiting the expression of NF-kappa B in cerebral cortex.
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Affiliation(s)
- Zheng-qin Yang
- Department of Nuclear Medicine, Chongqing University of Medical Science, Chongqing 400016.
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11
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Li QX, Mok SS, Laughton KM, McLean CA, Volitakis I, Cherny RA, Cheung NS, White AR, Masters CL. Overexpression of Abeta is associated with acceleration of onset of motor impairment and superoxide dismutase 1 aggregation in an amyotrophic lateral sclerosis mouse model. Aging Cell 2006; 5:153-65. [PMID: 16626394 DOI: 10.1111/j.1474-9726.2006.00200.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Transgenic mice carrying mutant Cu/Zn superoxide dismutase (SOD1) recapitulate the motor impairment of human amyotrophic lateral sclerosis (ALS). The amyloid-beta (Abeta) peptide associated with Alzheimer's disease is neurotoxic. To investigate the potential role of Abeta in ALS development, we generated a double transgenic mouse line that overexpresses SOD1(G93A) and amyloid precursor protein (APP)-C100. The transgenic mouse C100.SOD1(G93A) overexpresses Abeta and shows earlier onset of motor impairment but has the same lifespan as the single transgenic SOD1(G93A) mouse. To determine the mechanism associated with this early-onset phenotype, we measured copper and zinc levels in brain and spinal cord and found both significantly elevated in the single and double transgenic mice compared with their littermate control mice. Increased glial fibrillary acidic protein and decreased APP levels in the spinal cord of C100.SOD1(G93A) mice compared with the SOD1(G93A) mice agree with the neuronal damage observed by immunohistochemical analysis. In the spinal cords of C100.SOD1(G93A) double transgenic mice, soluble Abeta was elevated in mice at end-stage disease compared with the pre-symptomatic stage. Buffer-insoluble SOD1 aggregates were significantly elevated in the pre-symptomatic mice of C100.SOD1(G93A) compared with the age-matched SOD1(G93A) mice, correlating with the earlier onset of motor impairment in the C100.SOD1(G93A) mice. This study supports abnormal SOD1 protein aggregation as the pathogenic mechanism in ALS, and implicates a potential role for Abeta in the development of ALS by exacerbating SOD1(G93A) aggregation.
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Affiliation(s)
- Qiao-Xin Li
- Department of Pathology, The University of Melbourne, and The Mental Health Research Institute of Victoria, Parkville, Vic. 3010, Australia.
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Frackowiak J, Potempska A, LeVine H, Haske T, Dickson D, Mazur-Kolecka B. Extracellular Deposits of Aβ Produced in Cultures of Alzheimer Disease Brain Vascular Smooth Muscle Cells. J Neuropathol Exp Neurol 2005; 64:82-90. [PMID: 15715088 DOI: 10.1093/jnen/64.1.82] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Alzheimer disease (AD) and Down syndrome (DS) brains contain deposits of amyloid-beta peptide that are located extracellularly in the neuropil and in blood vessels walls. A small fraction of brain Abeta is detected intracellularly in neurons, smooth muscle cells, and microglia. The roles of these extracellular and intracellular pools of Abeta in pathogenesis of AD-type dementia are controversial. Cell culture models of vascular amyloidosis-beta revealed intracellular, but not extracellular deposition of Abeta. Here we demonstrate for the first time, formation of extracellular deposits of Abeta in primary cultures of vascular smooth muscle cells isolated from AD cases with cerebrovascular amyloid angiopathy. Extracellular Abeta deposition required the use of cultures that produced high quantities of Abeta, which contained at least 50% of cells forming intracellular Abeta deposits, and providing extracellular matrix proteins. During 12 days of culture in this system, we observed accumulation of nonfibrillar, granular deposits in extracellular matrix, similar to early stages of vascular amyloidogenesis in vivo. This is a valuable system to study the effects of various potential amyloidogenic factors on formation of extracellular Abeta deposits.
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Affiliation(s)
- Janusz Frackowiak
- NYS Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314, USA.
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Verdile G, Groth D, Mathews PM, St George-Hyslop P, Fraser PE, Ramabhadran TV, Kwok JBJ, Schofield PR, Carter T, Gandy S, Martins RN. Baculoviruses expressing the human familial Alzheimer's disease presenilin 1 mutation lacking exon 9 increase levels of an amyloid beta-like protein in Sf9 cells. Mol Psychiatry 2004; 9:594-602. [PMID: 14993906 DOI: 10.1038/sj.mp.4001458] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Presenilin 1 (PS1) plays a pivotal role in the production of the amyloid-beta protein (Abeta) that is central to the pathogenesis of Alzheimer's disease. PS1 regulates the intramembranous proteolysis of a 99-amino-acid C-terminal fragment of the amyloid precursor protein (APP-C99), a cleavage event that releases Abeta following a reaction catalyzed by an enzyme termed 'gamma-secretase'. The molecular mechanism of PS1-mediated, gamma-secretase cleavage remains largely unresolved. In particular, controversy surrounds whether PS1 includes the catalytic site of the gamma-secretase protease or whether instead PS1 mediates gamma-secretase activity indirectly, perhaps by regulating the trafficking or presentation of substrates to the 'authentic' protease, which may be a molecule distinct from PS1. To address this issue, the baculovirus expression system was used to co-express: (i) APP-C99; (ii) a pathogenic, constitutively active mutant form of PS1 lacking exon 9 (PS1DeltaE9); (iii) nicastrin and (iv) tropomyosin in Spodoptera frugiperda (Sf9) cells. Cells infected with APP-C99 alone produced an Abeta-like species, and levels of this species were enhanced by the addition of baculoviruses bearing the PS1DeltaE9 mutation. The addition to APP-C99-infected cells of baculoviruses bearing nicastrin, also a transmembrane protein, had a neutral or inhibitory effect on the reaction; tropomyosin viruses had the same effect as nicastrin viruses. These results suggest that PS1DeltaE9 molecules expressed in Sf9 cells retain the ability to modulate Abeta levels. Baculoviral-expressed PS1DeltaE9 provides a source of microgram quantities of bioactive molecules for use as starting material for purifying and reconstituting gamma-secretase activity from its individual purified component parts.
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Affiliation(s)
- G Verdile
- Sir James McCusker Alzheimer's Disease Research Unit, University of Western Australia, School of Psychiatry and Clinical Neurosciences, Hollywood Private Hospital, Nedlands, WA, Australia
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14
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Abstract
Biochemical and genetic evidence indicates the balance of biogenesis/clearance of Abeta amyloid peptides is altered in Alzheimer's disease. Abeta is derived, by two sequential cleavages, from the receptor-like amyloid precursor protein (APP). The proteases involved are beta-secretase, identified as the novel aspartyl protease BACE, and gamma-secretase, a multimeric complex containing the presenilins (PS). Gamma-secretase can release either Abeta40 or the more aggregating and cytotoxic Abeta42. Secreted Abeta peptides become either degraded by the metalloproteases insulin-degrading enzyme (IDE) and neprilysin or metabolized through receptor uptake mediated by apolipoprotein E. Therapeutic approaches based on secretase inhibition or amyloid clearance are currently under development.
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Affiliation(s)
- Geneviève Evin
- Department of Pathology, The University of Melbourne and Mental Health Research Institute, Parkville, Vic. 3010, Australia.
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15
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Glabe C. Intracellular mechanisms of amyloid accumulation and pathogenesis in Alzheimer's disease. J Mol Neurosci 2001; 17:137-45. [PMID: 11816787 DOI: 10.1385/jmn:17:2:137] [Citation(s) in RCA: 166] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cell-culture studies have revealed some of the fundamental features of the interaction of amyloid Abeta with cells and the mechanism of amyloid accumulation and pathogenesis in vitro. A(beta)1-42, the longer isoform of amyloid that is preferentially concentrated in senile plaque (SP) amyloid deposits in Alzheimer's disease (AD), is resistant to degradation and accumulates as insoluble aggregates in late endosomes or lysosomes. Once these aggregates have nucleated inside the cell, they grow by the addition of aberrantly folded APP and amyloidgenic fragments of APP, that would otherwise be degraded, onto the amyloid lattice in a fashion analogous to prion replication. This accumulation of heterogeneous aggregated APP fragments and Abeta appears to mimic the pathophysiologyof dystrophic neurites, where the same spectrum of components has been identified by immunohistochemistry. In the brain, this residue appears to be released into the extracellular space, possibly by a partially apoptotic mechanism that is restricted to the distal compartments of the neuron. Ultimately, this insoluble residue may be further digested to the protease-resistant A(beta)n-42 core, perhaps by microglia, where it accumulates as senile plaques. Thus, the dystrophic neurites are likely to be the source of the immediate precursors of amyloid in the senile plaques. This is the opposite of the commonly held view that extracellular accumulation of amyloid induces dystrophic neurites. Many of the key pathological events of AD may also be directly related to the intracellular accumulation of this insoluble amyloid. The aggregated, intracellular amyloid induces the production of reactive oxygen species (ROS) and lipid peroxidation products and ultimately results in the leakage of the lysosomal membrane. The breakdown of the lysosomal membrane may be a key pathogenic event, leading to the release of heparan sulfate and lysosomal hydrolases into the cytosol. Together, these observations provide the novel view that amyloid deposits and some of the early events of amyloid pathogenesis initiate randomly within single cells in AD. This pathogenic mechanism can explain some of the more enigmatic features of Alzheimer's pathogenesis, like the focal nature of amyloid plaques, the relationship between amyloid, dystrophic neurites and neurofibrillary-tangle pathology, and the miscompartmentalization of extracellular and cytosolic components observed in AD brain.
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Affiliation(s)
- C Glabe
- Department of Molecular Biology and Biochemistry, University of California, Irvine 92697, USA.
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16
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Pinnix I, Musunuru U, Tun H, Sridharan A, Golde T, Eckman C, Ziani-Cherif C, Onstead L, Sambamurti K. A novel gamma -secretase assay based on detection of the putative C-terminal fragment-gamma of amyloid beta protein precursor. J Biol Chem 2001; 276:481-7. [PMID: 11035007 DOI: 10.1074/jbc.m005968200] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alzheimer's disease is characterized by the deposits of the 4-kDa amyloid beta peptide (A beta). The A beta protein precursor (APP) is cleaved by beta-secretase to generate a C-terminal fragment, CTF beta, which in turn is cleaved by gamma-secretase to generate A beta. Alternative cleavage of the APP by alpha-secretase at A beta 16/17 generates the C-terminal fragment, CTFalpha. In addition to A beta, endoproteolytic cleavage of CTF alpha and CTF beta by gamma-secretase should yield a C-terminal fragment of 57-59 residues (CTF gamma). However, CTF gamma has not yet been reported in either brain or cell lysates, presumably due to its instability in vivo. We detected the in vitro generation of A beta as well as an approximately 6-kDa fragment from guinea pig brain membranes. We have provided biochemical and pharmacological evidence that this 6-kDa fragment is the elusive CTF gamma, and we describe an in vitro assay for gamma-secretase activity. The fragment migrates with a synthetic peptide corresponding to the 57-residue CTF gamma fragment. Three compounds previously identified as gamma-secretase inhibitors, pepstatin-A, MG132, and a substrate-based difluoroketone (t-butoxycarbonyl-Val-Ile-(S)-4-amino-3-oxo-2, 2-difluoropentanoyl-Val-Ile-OMe), reduced the yield of CTF gamma, providing additional evidence that the fragment arises from gamma-secretase cleavage. Consistent with reports that presenilins are the elusive gamma-secretases, subcellular fractionation studies showed that presenilin-1, CTF alpha, and CTF beta are enriched in the CTF gamma-generating fractions. The in vitro gamma-secretase assay described here will be useful for the detailed characterization of the enzyme and to screen for gamma-secretase inhibitors.
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Affiliation(s)
- I Pinnix
- Mayo Clinic, Jacksonville, Florida 32224, USA
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17
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Abstract
In this review, we argue that at least one insult that causes Alzheimer's disease (AD) is disruption of the normal function of the amyloid precursor protein (APP). Familial Alzheimer's disease (FAD) mutations in APP cause a disease phenotype that is identical (with the exception that they cause an earlier onset of the disease) to that of 'sporadic' AD. This suggests that there are molecular pathways common to FAD and sporadic AD. In addition, all individuals with Down syndrome, who carry an extra copy of chromosome 21 and overexpress APP several-fold in the brain, develop the pathology of AD if they live past the age of 40. These data support the primacy of APP in the disease. Although APP is the source of the beta-amyloid (Abeta) that is deposited in amyloid plaques in AD brain, the primacy of APP in AD may not lie in the production of Abeta from this molecule. We suggest instead that APP normally functions in the brain as a cell surface signaling molecule, and that a disruption of this normal function of APP is at least one cause of the neurodegeneration and consequent dementia in AD. We hypothesize in addition that disruption of the normal signaling function of APP causes cell cycle abnormalities in the neuron, and that these abnormalities constitute one mechanism of neuronal death in AD. Data supporting these hypotheses have come from investigations of the molecular consequences of neuronal expression of FAD mutants of APP or overexpression of wild type APP, as well as from identification of binding proteins for the carboxyl-terminus (C-terminus) of APP.
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Affiliation(s)
- R L Neve
- Department of Psychiatry, Harvard Medical School, MRC 223 McLean Hospital, 115 Mill St., 02478, Belmont, MA, USA.
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18
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Chen F, Yang DS, Petanceska S, Yang A, Tandon A, Yu G, Rozmahel R, Ghiso J, Nishimura M, Zhang DM, Kawarai T, Levesque G, Mills J, Levesque L, Song YQ, Rogaeva E, Westaway D, Mount H, Gandy S, St George-Hyslop P, Fraser PE. Carboxyl-terminal fragments of Alzheimer beta-amyloid precursor protein accumulate in restricted and unpredicted intracellular compartments in presenilin 1-deficient cells. J Biol Chem 2000; 275:36794-802. [PMID: 10962005 DOI: 10.1074/jbc.m006986200] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Absence of functional presenilin 1 (PS1) protein leads to loss of gamma-secretase cleavage of the amyloid precursor protein (betaAPP), resulting in a dramatic reduction in amyloid beta peptide (Abeta) production and accumulation of alpha- or beta-secretase-cleaved COOH-terminal fragments of betaAPP (alpha- or beta-CTFs). The major COOH-terminal fragment (CTF) in brain was identified as betaAPP-CTF-(11-98), which is consistent with the observation that cultured neurons generate primarily Abeta-(11-40). In PS1(-/-) murine neurons and fibroblasts expressing the loss-of-function PS1(D385A) mutant, CTFs accumulated in the endoplasmic reticulum, Golgi, and lysosomes, but not late endosomes. There were some subtle differences in the subcellular distribution of CTFs in PS1(-/-) neurons as compared with PS1(D385A) mutant fibroblasts. However, there was no obvious redistribution of full-length betaAPP or of markers of other organelles in either mutant. Blockade of endoplasmic reticulum-to-Golgi trafficking indicated that in PS1(-/-) neurons (as in normal cells) trafficking of betaAPP to the Golgi compartment is necessary before alpha- and beta-secretase cleavages occur. Thus, although we cannot exclude a specific role for PS1 in trafficking of CTFs, these data argue against a major role in general protein trafficking. These results are more compatible with a role for PS1 either as the actual gamma-secretase catalytic activity or in other functions indirectly related to gamma-secretase catalysis (e.g. an activator of gamma-secretase, a substrate adaptor for gamma-secretase, or delivery of gamma-secretase to betaAPP-containing compartments).
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Affiliation(s)
- F Chen
- Centre for Research in Neurodegenerative Diseases, Departments of Laboratory Medicine and Pathobiology, Medical Biophysics and Medicine, University of Toronto, Ontario, Canada
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19
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Kimberly WT, Xia W, Rahmati T, Wolfe MS, Selkoe DJ. The transmembrane aspartates in presenilin 1 and 2 are obligatory for gamma-secretase activity and amyloid beta-protein generation. J Biol Chem 2000; 275:3173-8. [PMID: 10652302 DOI: 10.1074/jbc.275.5.3173] [Citation(s) in RCA: 195] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The discovery that a deficiency of presenilin 1 (PS1) decreases the production of amyloid beta-protein (Abeta) identified the presenilins as important mediators of the gamma-secretase cleavage of beta-amyloid precursor protein (APP). Recently, we found that two conserved transmembrane (TM) aspartates in PS1 are critical for Abeta production, providing evidence that PS1 either functions as a required diaspartyl cofactor for gamma-secretase or is itself gamma-secretase. Presenilin 2 (PS2) shares substantial sequence and possibly functional homology with PS1. Here, we show that the two TM aspartates in PS2 are also critical for gamma-secretase activity, providing further evidence that PS2 is functionally homologous to PS1. Cells stably co-expressing TM Asp --> Ala mutations in both PS1 and PS2 show further accumulation of the APP-derived gamma-secretase substrates, C83 and C99. The production of Abeta is reduced to undetectable levels in the conditioned media of these cells. Furthermore, endoproteolysis of the exogenous Asp mutant PS2 is absent, and endogenous PS1 C-terminal fragments are diminished to undetectable levels. Therefore, the co-expression of PS1 and PS2 TM Asp --> Ala mutants suppresses the formation of any detectable PS1 or PS2 heterodimeric fragments and essentially abolishes the production of Abeta. These results explain the residual Abeta production seen in PS1-deficient cells and demonstrate the absolute requirement of functional presenilins for Abeta generation. We conclude that presenilins, and their TM aspartates in particular, are attractive targets for lowering Abeta therapeutically to prevent Alzheimer's disease.
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Affiliation(s)
- W T Kimberly
- Department of Neurology, Harvard Medical School and Center for Neurologic Diseases, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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20
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Secondary structural modifications of Aβ(1–40) induced by multiple 2-acetoxy-4-methoxybenzyl (acetylHmb) protection. Int J Pept Res Ther 1999. [DOI: 10.1007/bf02443424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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21
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Clippingdale AB, Macris M, Wade JD, Barrow CJ. Synthesis and secondary structural studies of penta(acetyl-Hmb)A beta(1-40). THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 1999; 53:665-72. [PMID: 10408341 DOI: 10.1034/j.1399-3011.1999.00065.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The Fmoc solid phase synthesis of A beta(1-40), a strongly aggregating peptide found in Alzheimer's disease brain, was performed using 2-hydroxy-4-methoxybenzyl (Hmb) backbone amide protection. Hmb-Gly residues were incorporated using N(alpha)-Fmoc-Hmb-Gly-OH rather than N,O-bisFmoc-Hmb-Gly-OPfp. Amino acid acylation of the sterically hindered Hmb-amino acids was monitored using 'semi-on-line' MALDI-TOF-MS in a novel application of this technique which significantly simplified the successful incorporation of these residues. Standard coupling conditions in N,N-dimethylformamide (DMF) were used throughout the synthesis. Comparative structural studies of acetyl-Hmb-protected and native A beta(1-40) were performed to investigate the structural basis of Hmb-mediated disaggregation. The incorporation of backbone amide protection was observed by circular dichroism spectroscopy and gel electrophoresis to strongly affect the solution structure of A beta(1-40). Despite the reported structure-breaking activity of Hmb groups, penta(acetyl-Hmb)A beta(1-40) was found to adopt both alpha-helix and intermolecular beta-sheet conformations. In 100% TFE a mixed alpha-helix/random coil structure was formed by the protected peptide indicating reduced alpha-helical propensity relative to A beta(1-40). The protected peptide formed beta-sheet structures in aqueous buffer. Gel electrophoresis indicated that, unlike native A beta(1-40), penta(acetyl-Hmb)A beta(1-40) did not form large aggregate species.
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Affiliation(s)
- A B Clippingdale
- School of Chemistry and Howard Florey Institute of Experimental Physiology and Medicine, The University of Melbourne, Parkville, Victoria, Australia
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22
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Culvenor JG, Henry A, Hartmann T, Evin G, Galatis D, Friedhuber A, Jayasena UL, Underwood JR, Beyreuther K, Masters CL, Cappai R. Subcellular localization of the Alzheimer's disease amyloid precursor protein and derived polypeptides expressed in a recombinant yeast system. Amyloid 1998; 5:79-89. [PMID: 9686302 DOI: 10.3109/13506129808995285] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Different isoforms and derived polypeptides of the Alzheimer's disease amyloid protein precursor (A beta PP) have been expressed in the yeast Pichia pastoris. The expression characteristics of the different A beta PP polypeptides were studied by post-embedding immunogold electron microscopy with various A beta PP antibodies. The site of intracellular expression could be readily identified with specific antibodies. Full length A beta PP was expressed in association with the nuclear membrane and the endoplasmic reticulum. Secretory derivatives of A beta PP were localized in membrane-bound secretory vesicles. A construct encoding two copies of beta A4[1-42] linked head-to-tail (beta A4duplex) accumulated as irregular dense cytoplasmic and intranuclear inclusions which reacted with all beta A4 antibodies tested. A beta A4-C-terminal construct accumulated into membranous structures in the cytoplasm and nucleus and reacted with most antibodies to beta A4 and the cytoplasmic domain of A beta PP. The two shorter constructs containing the beta A4 sequence formed similar intranuclear aggregates to those reported for intranuclear inclusions of polyglutamine peptides from huntingtin (in Huntington's disease) and ataxin protein fragments (in spinocerebellar ataxia). This is of interest because intracellular aggregation of the polyglutamine and beta A4 peptides may affect cells by similar toxic mechanisms. These studies demonstrate clear differences in the expression properties of different A beta PP polypeptides.
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Affiliation(s)
- J G Culvenor
- Department of Pathology, University of Melbourne, Victoria, Australia.
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23
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Kisilevsky R, Fraser PE. A beta amyloidogenesis: unique, or variation on a systemic theme? Crit Rev Biochem Mol Biol 1998; 32:361-404. [PMID: 9383610 DOI: 10.3109/10409239709082674] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
For more than a century amyloid was considered to be an interesting, unique, but inconsequential pathologic entity that rarely caused significant clinical problems. We now recognize that amyloid is not one entity. In vivo it is a uniform organization of a disease, or process, specific protein co-deposited with a set of common structural components. Amyloid has been implicated in the pathogenesis of diseases affecting millions of patients. These range from Alzheimer's disease, adult-onset diabetes, consequences of prolonged renal dialysis, to the historically recognized systemic forms associated with inflammation and plasma cell disturbances. Strong evidence is emerging that even when deposited in local organ sites significant physiologic effects may ensue. With emphasis on A beta amyloid, we review the present definition, classification, and general in vivo pathogenetic events believed to be involved in the deposition of amyloids. This encompasses the need for an adequate amyloid precursor protein pool, whether precursor proteolysis is required prior to deposition, amyloidogenic amino acid sequences, fibrillogenic nucleating particles, and an in vivo microenvironment conducive to fibrillogenesis. The latter includes several components that seem to be part of all amyloids. The role these common components may play in amyloid accumulation, why amyloids tend to be associated with basement membranes, and how one may use these findings for anti-amyloid therapeutic strategies is also examined.
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Affiliation(s)
- R Kisilevsky
- Department of Pathology, Queen's University, Kingston, Ontario Canada
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24
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McPhie DL, Lee RK, Eckman CB, Olstein DH, Durham SP, Yager D, Younkin SG, Wurtman RJ, Neve RL. Neuronal expression of beta-amyloid precursor protein Alzheimer mutations causes intracellular accumulation of a C-terminal fragment containing both the amyloid beta and cytoplasmic domains. J Biol Chem 1997; 272:24743-6. [PMID: 9312066 DOI: 10.1074/jbc.272.40.24743] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Five different Alzheimer mutations of the beta-amyloid precursor protein (APP) were expressed in neurons via recombinant herpes simplex virus (HSV) vectors, and the levels of APP metabolites were quantified. The predominant intracellular accumulation product was a C-terminal fragment of APP that co-migrated with the protein product of an HSV recombinant expressing the C-terminal 100 amino acids (C100) of APP, which is known to cause neurodegeneration. Fractionation studies revealed that the C-terminal fragment generated by expression of the Alzheimer mutations, like C100, partitioned into membrane fractions and was particularly enriched in synaptosomes. The processing abnormality caused by expression of the Alzheimer mutations occurs predominantly in neurons. Expression of these mutations or of C100 alone in neurons caused increased secretion of Abeta relative to that of neurons infected with wild type APP recombinant vectors. These data show that expression of APP mutations that cause familial Alzheimer's disease increases the intracellular accumulation of potentially amyloidogenic and neurotoxic C-terminal fragments of APP in neurons.
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Affiliation(s)
- D L McPhie
- Department of Genetics, Harvard Medical School, McLean Hospital, Belmont, Massachusetts 02178, USA
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25
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Lansbury PT. Inhibition of amyloid formation: a strategy to delay the onset of Alzheimer's disease. Curr Opin Chem Biol 1997; 1:260-7. [PMID: 9667848 DOI: 10.1016/s1367-5931(97)80018-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Converging evidence suggests that the formation of amyloid plaques may play a central role in the pathogenesis of Alzheimer's disease and that blocking amyloid formation may be an effective therapeutic strategy.
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Affiliation(s)
- P T Lansbury
- Center for Neurologic Diseases, Brigham and Women's Hospital, Boston, MA 02115, USA.
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