Cartilage acidic protein 1, a new member of the beta-propeller protein family with amyloid propensity.

Science.gov (United States)

Anjos, Liliana; Morgado, Isabel; Guerreiro, Marta; Cardoso, João C R; Melo, Eduardo P; Power, Deborah M

2017-02-01

Cartilage acidic protein1 (CRTAC1) is an extracellular matrix protein of chondrogenic tissue in humans and its presence in bacteria indicate it is of ancient origin. Structural modeling of piscine CRTAC1 reveals it belongs to the large family of beta-propeller proteins that in mammals have been associated with diseases, including amyloid diseases such as Alzheimer's. In order to characterize the structure/function evolution of this new member of the beta-propeller family we exploited the unique characteristics of piscine duplicate genes Crtac1a and Crtac1b and compared their structural and biochemical modifications with human recombinant CRTAC1. We demonstrate that CRTAC1 has a beta-propeller structure that has been conserved during evolution and easily forms high molecular weight thermo-stable aggregates. We reveal for the first time the propensity of CRTAC1 to form amyloid-like structures, and hypothesize that the aggregating property of CRTAC1 may be related to its disease-association. We further contribute to the general understating of CRTAC1's and beta-propeller family evolution and function. Proteins 2017; 85:242-255. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Lack of evidence for protein AA reactivity in amyloid deposits of lattice corneal dystrophy and amyloid corneal degeneration.

Science.gov (United States)

Gorevic, P D; Rodrigues, M M; Krachmer, J H; Green, C; Fujihara, S; Glenner, G G

1984-08-15

Amyloid fibrils occurring in primary and myeloma-associated (AL), secondary (AA), and certain neuropathic hereditary forms of systemic amyloidosis can be distinguished biochemically or immunohistologically as being composed of immunoglobulin light chain, protein AA, or prealbumin respectively. All types of systemic and several localized forms of amyloidosis contain amyloid P component (protein AP). We studied formalin-fixed tissue from eight cases of lattice corneal dystrophy by the immunoperoxidase method using antisera to proteins AA and AP, to normal serum prealbumin and prealbumin isolated from a case of hereditary amyloidosis, and to light-chain determinants; additional cases were examined by indirect immunofluorescence of fresh-frozen material. We found weak (1:10 dilution) staining with anti-AP, but no reactivity with other antisera. Congo red staining was resistant to pretreatment of sections with potassium permanganate, a characteristic of non-AA amyloid. Two-dimensional gels of solubilized proteins from frozen tissue from two cases of lattice corneal dystrophy resembled those obtained from normal human cornea. Western blots of two cases of polymorphous amyloid degeneration and solubilized protein from normal cornea did not react with radioactive iodine-labeled anti-AA or anti-AP with purified protein AP and unfixed protein AA amyloid tissue as controls. We were unable to corroborate the presence of protein AA in the amyloid deposits of lattice corneal dystrophy. Although staining with antiserum to protein AP was demonstrable, the molecular configuration of this protein in stromal deposits remains to be defined.

Glycation induces formation of amyloid cross-beta structure in albumin.

Science.gov (United States)

Bouma, Barend; Kroon-Batenburg, Loes M J; Wu, Ya-Ping; Brünjes, Bettina; Posthuma, George; Kranenburg, Onno; de Groot, Philip G; Voest, Emile E; Gebbink, Martijn F B G

2003-10-24

Amyloid fibrils are components of proteinaceous plaques that are associated with conformational diseases such as Alzheimer's disease, transmissible spongiform encephalopathies, and familial amyloidosis. Amyloid polypeptides share a specific quarternary structure element known as cross-beta structure. Commonly, fibrillar aggregates are modified by advanced glycation end products (AGE). In addition, AGE formation itself induces protein aggregation. Both amyloid proteins and protein-AGE adducts bind multiligand receptors, such as receptor for AGE, CD36, and scavenger receptors A and B type I, and the serine protease tissue-type plasminogen activator (tPA). Based on these observations, we hypothesized that glycation induces refolding of globular proteins, accompanied by formation of cross-beta structure. Using transmission electron microscopy, we demonstrate here that glycated albumin condensates into fibrous or amorphous aggregates. These aggregates bind to amyloid-specific dyes Congo red and thioflavin T and to tPA. In contrast to globular albumin, glycated albumin contains amino acid residues in beta-sheet conformation, as measured with circular dichroism spectropolarimetry. Moreover, it displays cross-beta structure, as determined with x-ray fiber diffraction. We conclude that glycation induces refolding of initially globular albumin into amyloid fibrils comprising cross-beta structure. This would explain how glycated ligands and amyloid ligands can bind to the same multiligand "cross-beta structure" receptors and to tPA.

Nasal administration of amyloid-beta peptide decreases cerebral amyloid burden in a mouse model of Alzheimer's disease

DEFF Research Database (Denmark)

Weiner, H L; Lemere, C A; Maron, R

2000-01-01

Progressive cerebral deposition of amyloid-beta (Abeta) peptide, an early and essential feature of Alzheimer's disease (AD), is accompanied by an inflammatory reaction marked by microgliosis, astrocytosis, and the release of proinflammatory cytokines. Mucosal administration of disease-implicated ......Progressive cerebral deposition of amyloid-beta (Abeta) peptide, an early and essential feature of Alzheimer's disease (AD), is accompanied by an inflammatory reaction marked by microgliosis, astrocytosis, and the release of proinflammatory cytokines. Mucosal administration of disease...... cerebral Abeta deposition, suggesting a novel mucosal immunological approach for the treatment and prevention of AD....

Mapping of the gene encoding the. beta. -amyloid precursor protein and its relationship to the Down syndrome region of chromosome 21

Energy Technology Data Exchange (ETDEWEB)

Patterson, D.; Gardiner, K.; Kao, F.T.; Tanzi, R.; Watkins, P.; Gusella, J.F. (Eleanor Roosevelt Institute for Cancer Research, Denver, CO (USA))

1988-11-01

The gene encoding the {beta}-amyloid precursor protein has been assigned to human chromosome 21, as has a gene responsible for at least some cases of familial Alzheimer disease. Linkage studies strongly suggest that the {beta}-amyloid precursor protein and the product corresponding to familial Alzheimer disease are from two genes, or at least that several million base pairs of DNA separate the markers. The precise location of the {beta}-amyloid precursor protein gene on chromosome 21 has not yet been determined. Here the authors show, by using a somatic-cell/hybrid-cell mapping panel, in situ hybridization, and transverse-alternating-field electrophoresis, that the {beta}-amyloid precursor protein gene is located on chromosome 21 very near the 21q21/21q/22 border and probably within the region of chromosome 21 that, when trisomic, results in Down syndrome.

{beta} - amyloid imaging probes

Energy Technology Data Exchange (ETDEWEB)

Jeong, Jae Min [Seoul National University College of Medicine, Seoul (Korea, Republic of)

2007-04-15

Imaging distribution of {beta} - amyloid plaques in Alzheimer's disease is very important for early and accurate diagnosis. Early trial of the {beta} -amyloid plaques includes using radiolabeled peptides which can be only applied for peripheral {beta} - amyloid plaques due to limited penetration through the blood brain barrier (BBB). Congo red or Chrysamine G derivatives were labeled with Tc-99m for imaging {beta} - amyloid plaques of Alzheimer patient's brain without success due to problem with BBB penetration. Thioflavin T derivatives gave breakthrough for {beta} - amyloid imaging in vivo, and a benzothiazole derivative [C-11]6-OH-BTA-1 brought a great success. Many other benzothiazole, benzoxazole, benzofuran, imidazopyridine, and styrylbenzene derivatives have been labeled with F-18 and I-123 to improve the imaging quality. However, [C-11]6-OH-BTA-1 still remains as the best. However, short half-life of C-11 is a limitation of wide distribution of this agent. So, it is still required to develop an Tc-99m, F-18 or I-123 labeled agent for {beta} - amyloid imaging agent.

Interaction of amyloid inhibitor proteins with amyloid beta peptides: insight from molecular dynamics simulations.

Directory of Open Access Journals (Sweden)

Payel Das

Full Text Available Knowledge of the detailed mechanism by which proteins such as human αB- crystallin and human lysozyme inhibit amyloid beta (Aβ peptide aggregation is crucial for designing treatment for Alzheimer's disease. Thus, unconstrained, atomistic molecular dynamics simulations in explicit solvent have been performed to characterize the Aβ17-42 assembly in presence of the αB-crystallin core domain and of lysozyme. Simulations reveal that both inhibitor proteins compete with inter-peptide interaction by binding to the peptides during the early stage of aggregation, which is consistent with their inhibitory action reported in experiments. However, the Aβ binding dynamics appear different for each inhibitor. The binding between crystallin and the peptide monomer, dominated by electrostatics, is relatively weak and transient due to the heterogeneous amino acid distribution of the inhibitor surface. The crystallin-bound Aβ oligomers are relatively long-lived, as they form more extensive contact surface with the inhibitor protein. In contrast, a high local density of arginines from lysozyme allows strong binding with Aβ peptide monomers, resulting in stable complexes. Our findings not only illustrate, in atomic detail, how the amyloid inhibitory mechanism of human αB-crystallin, a natural chaperone, is different from that of human lysozyme, but also may aid de novo design of amyloid inhibitors.

Cholesterol enhances amyloid {beta} deposition in mouse retina by modulating the activities of A{beta}-regulating enzymes in retinal pigment epithelial cells

Energy Technology Data Exchange (ETDEWEB)

Wang, Jiying [Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519 (Japan); Ohno-Matsui, Kyoko, E-mail: k.ohno.oph@tmd.ac.jp [Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519 (Japan); Morita, Ikuo [Section of Cellular Physiological Chemistry, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519 (Japan)

2012-08-10

Highlights: Black-Right-Pointing-Pointer Cholesterol-treated RPE produces more A{beta} than non-treated RPE. Black-Right-Pointing-Pointer Neprilysin expression and activity decreased in cholesterol-treated RPE. Black-Right-Pointing-Pointer {alpha}-Secretase expression and activity decreased in cholesterol-treated RPE. Black-Right-Pointing-Pointer Cholesterol-enriched diet induced subRPE deposits in aged mice. Black-Right-Pointing-Pointer A{beta} were present in cholesterol-enriched-diet-induced subRPE deposits in aged mice. -- Abstract: Subretinally-deposited amyloid {beta} (A{beta}) is a main contributor of developing age-related macular degeneration (AMD). However, the mechanism causing A{beta} deposition in AMD eyes is unknown. Hypercholesterolemia is a significant risk for developing AMD. Thus, we investigated the effects of cholesterol on A{beta} production in retinal pigment epithelial (RPE) cells in vitro and in the mouse retina in vivo. RPE cells isolated from senescent (12-month-old) C57BL/6 mice were treated with 10 {mu}g/ml cholesterol for 48 h. A{beta} amounts in culture supernatants were measured by ELISA. Activity and expression of enzymes and proteins that regulate A{beta} production were examined by activity assay and real time PCR. The retina of mice fed cholesterol-enriched diet was examined by transmission electron microscopy. Cholesterol significantly increased A{beta} production in cultured RPE cells. Activities of A{beta} degradation enzyme; neprilysin (NEP) and anti-amyloidogenic secretase; {alpha}-secretase were significantly decreased in cell lysates of cholesterol-treated RPE cells compared to non-treated cells, but there was no change in the activities of {beta}- or {gamma}-secretase. mRNA levels of NEP and {alpha}-secretase (ADAM10 and ADAM17) were significantly lower in cholesterol-treated RPE cells than non-treated cells. Senescent (12-month-old) mice fed cholesterol-enriched chow developed subRPE deposits containing A{beta}, whereas

Plasma Membrane Protein Profiling in Beta-Amyloid-Treated Microglia Cell Line.

Science.gov (United States)

Correani, Virginia; Di Francesco, Laura; Mignogna, Giuseppina; Fabrizi, Cinzia; Leone, Stefano; Giorgi, Alessandra; Passeri, Alessia; Casata, Roberto; Fumagalli, Lorenzo; Maras, Bruno; Schininà, M Eugenia

2017-09-01

In the responsiveness of microglia to toxic stimuli, plasma membrane proteins play a key role. In this study we treated with a synthetic beta amyloid peptide murine microglial cells metabolically differently labelled with stable isotope amino acids (SILAC). The plasma membrane was selectively enriched by a multi-stage aqueous two-phase partition system. We were able to identify by 1D-LC-MS/MS analyses 1577 proteins, most of them are plasma membrane proteins according to the Gene Ontology annotation. An unchanged level of amyloid receptors in this data set suggests that microglia preserve their responsiveness capability to the environment even after 24-h challenge with amyloid peptides. On the other hand, 14 proteins were observed to change their plasma membrane abundance to a statistically significant extent. Among these, we proposed as reliable biomarkers of the inflammatory microglia phenotype in AD damaged tissues MAP/microtubule affinity-regulating kinase 3 (MARK3), Interferon-induced transmembrane protein 3 (IFITM3), Annexins A5 and A7 (ANXA5, ANXA7) and Neuropilin-1 (NRP1), all proteins known to be involved in the inflammation processes and in microtubule network assembly rate. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Calcium ionophore A23187 specifically decreases the secretion of beta-secretase cleaved amyloid precursor protein during apoptosis in primary rat cortical cultures

DEFF Research Database (Denmark)

Sennvik, K; Benedikz, Eirikur; Fastbom, J

2001-01-01

Alzheimer's disease (AD) is characterized by the degeneration and loss of neurons, intracellular neurofibrillary tangles and the accumulation of extracellular senile plaques consisting mainly of beta-amyloid (A beta). A beta is generated from the amyloid precursor protein (APP) by sequential beta...

SERUM ANALYSIS OF AMYLOID BETA-PROTEIN 1-40 IN HEALTHY SUBJECTS, AUTISTIC CHILDREN AND ALZHEIMER’S PATIENTS

Directory of Open Access Journals (Sweden)

Vijendra K. SINGH

2008-06-01

Full Text Available Amyloid beta-protein1-40 (AP40 is a low molecu­lar weight peptide produced throughout life during normal cell metabolism and neurodegenerative diseases. Owing to its neurotrophic and neurotoxic effects, the present study was conducted to evalu­ate serum levels of AP40 in healthy subjects, au­tistic children and Alzheimer’s disease patients. Serum AP40 was measured by enzyme-linked im­munosorbent assay (ELISA. AP40 was signifi­cantly higher in normal children compared to nor­mal older controls, in normal children compared to autistic children, and in autistic children compared to Alzheimer’s patients (p value was less than 0.05 for all groups. This finding suggests an age-re­lated decline of serum AP40 in normal aging, as well as in autism and Alzheimer’s disease. This decline may result from abnormal processing of amyloid beta-protein precursor (APP during nor­mal aging and age-related diseases such as autism in children and Alzheimer’s disease in elderly. Possible explanations for this decline may include age-related increased interactions of AP40 with cytoskeletal proteins for brain tissue deposition, increased serine proteases for APP metabolism or hyperimmune reaction (antibodies to AP40 for removal of circulating AP40. To conclude, the AP40 metabolism declines with normal aging and in addition to its role in Alzheimer’s disease this protein might also be a contributing factor in au­tism.

Cerebral amyloid-beta protein accumulation with aging in cotton-top tamarins: a model of early Alzheimer's disease?

Science.gov (United States)

Lemere, Cynthia A; Oh, Jiwon; Stanish, Heather A; Peng, Ying; Pepivani, Imelda; Fagan, Anne M; Yamaguchi, Haruyasu; Westmoreland, Susan V; Mansfield, Keith G

2008-04-01

Alzheimer's disease (AD) is the most common progressive form of dementia in the elderly. Two major neuropathological hallmarks of AD include cerebral deposition of amyloid-beta protein (Abeta) into plaques and blood vessels, and the presence of neurofibrillary tangles in brain. In addition, activated microglia and reactive astrocytes are often associated with plaques and tangles. Numerous other proteins are associated with plaques in human AD brain, including Apo E and ubiquitin. The amyloid precursor protein and its shorter fragment, Abeta, are homologous between humans and non-human primates. Cerebral Abeta deposition has been reported previously for rhesus monkeys, vervets, squirrel monkeys, marmosets, lemurs, cynomologous monkeys, chimpanzees, and orangutans. Here we report, for the first time, age-related neuropathological changes in cotton-top tamarins (CTT, Saguinus oedipus), an endangered non-human primate native to the rainforests of Colombia and Costa Rica. Typical lifespan is 13-14 years of age in the wild and 15-20+ years in captivity. We performed detailed immunohistochemical analyses of Abeta deposition and associated pathogenesis in archived brain sections from 36 tamarins ranging in age from 6-21 years. Abeta plaque deposition was observed in 16 of the 20 oldest tamarins (>12 years). Plaques contained mainly Abeta42, and in the oldest animals, were associated with reactive astrocytes, activated microglia, Apo E, and ubiquitin-positive dystrophic neurites, similar to human plaques. Vascular Abeta was detected in 14 of the 20 aged tamarins; Abeta42 preceded Abeta40 deposition. Phospho-tau labeled dystrophic neurites and tangles, typically present in human AD, were absent in the tamarins. In conclusion, tamarins may represent a model of early AD pathology.

Arf6 controls beta-amyloid production by regulating macropinocytosis of the Amyloid Precursor Protein to lysosomes.

Science.gov (United States)

Tang, Weihao; Tam, Joshua H K; Seah, Claudia; Chiu, Justin; Tyrer, Andrea; Cregan, Sean P; Meakin, Susan O; Pasternak, Stephen H

2015-07-14

Alzheimer's disease (AD) is characterized by the deposition of Beta-Amyloid (Aβ) peptides in the brain. Aβ peptides are generated by cleavage of the Amyloid Precursor Protein (APP) by the β - and γ - secretase enzymes. Although this process is tightly linked to the internalization of cell surface APP, the compartments responsible are not well defined. We have found that APP can be rapidly internalized from the cell surface to lysosomes, bypassing early and late endosomes. Here we show by confocal microscopy and electron microscopy that this pathway is mediated by macropinocytosis. APP internalization is enhanced by antibody binding/crosslinking of APP suggesting that APP may function as a receptor. Furthermore, a dominant negative mutant of Arf6 blocks direct transport of APP to lysosomes, but does not affect classical endocytosis to endosomes. Arf6 expression increases through the hippocampus with the development of Alzheimer's disease, being expressed mostly in the CA1 and CA2 regions in normal individuals but spreading through the CA3 and CA4 regions in individuals with pathologically diagnosed AD. Disruption of lysosomal transport of APP reduces both Aβ40 and Aβ42 production by more than 30 %. Our findings suggest that the lysosome is an important site for Aβ production and that altering APP trafficking represents a viable strategy to reduce Aβ production.

IMPY, a potential {beta}-amyloid imaging probe for detection of prion deposits in scrapie-infected mice

Energy Technology Data Exchange (ETDEWEB)

Song, P.-J. [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France); Bernard, Serge [IFR135, F-37000 Tours (France); INRA, UR1282, IASP, 37380 Nouzilly (France)], E-mail: bernard@tours.inra.fr; Sarradin, Pierre [INRA, UR1282, IASP, 37380 Nouzilly (France); Vergote, Jackie [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France); Barc, Celine [INRA, UR1282, IASP, 37380 Nouzilly (France); Chalon, Sylvie [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France); Kung, M.-P.; Kung, Hank F. [Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Guilloteau, Denis [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France)

2008-02-15

Introduction: A potential single-photon emission computed tomography imaging agent for labeling of A{beta} plaques of Alzheimer's disease, IMPY (2-(4'-dimethylaminophenyl)-6-iodo-imidazo[1,2-a]pyridine), would be effective in detection of prion amyloid deposits in transmissible spongiform encephalopathies (TSEs). Methods: In vitro autoradiographic studies were carried out with [{sup 125}I]IMPY on brain sections from scrapie-infected mice and age-matched controls. Competition study was performed to evaluate the prion deposit binding specificity with nonradioactive IMPY. Results: Binding of [{sup 125}I]IMPY was observed in infected brain sections, while on age-matched control brain sections, there was no or very low labeling. Prion deposit binding was confirmed by histoblots with prion protein-specific monoclonal antibody 2D6. In the presence of nonradioactive IMPY, the binding of [{sup 125}I]IMPY was significantly inhibited in all regions studied. Conclusions: These findings indicate that IMPY can detect the prion deposits in vitro in scrapie-infected mice. Labeled with {sup 123}I, this ligand may be useful to quantitate prion deposit burdens in TSEs by in vivo imaging.

Resveratrol and Amyloid-Beta: Mechanistic Insights

Directory of Open Access Journals (Sweden)

Yongming Jia

2017-10-01

Full Text Available The amyloid-beta (Aβ hypothesis that dyshomeostasis between Aβ production and clearance is a very early, key molecular factor in the etiology of Alzheimer’s disease (AD has been proposed and examined in the AD research field. Scientists have focused on seeking natural products or drugs to influence the dynamic equilibrium of Aβ, targeting production and clearance of Aβ. There is emerging evidence that resveratrol (Res, a naturally occurring polyphenol mainly found in grapes and red wine, acts on AD in numerous in vivo and in vitro models. Res decreases the amyloidogenic cleavage of the amyloid precursor protein (APP, enhances clearance of amyloid beta-peptides, and reduces Aβ aggregation. Moreover, Res also protects neuronal functions through its antioxidant properties. This review discusses the action of Res on Aβ production, clearance and aggregation and multiple potential mechanisms, providing evidence of the useful of Res for AD treatment.

Neurofibrillary tangles and the deposition of a beta amyloid peptide with a novel N-terminal epitope in the brains of wild Tsushima leopard cats.

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James K Chambers

Full Text Available Beta amyloid (Aβ deposits are seen in aged individuals in many of the mammalian species that possess the same Aβ amino acid sequence as humans. Conversely, neurofibrillary tangles (NFT, the other hallmark lesion of Alzheimer's disease (AD, are extremely rare in these animals. We detected Aβ deposits in the brains of Tsushima leopard cats (Prionailurus bengalensis euptilurus that live exclusively on Tsushima Island, Japan. Aβ42 was deposited in a granular pattern in the neuropil of the pyramidal cell layer, but did not form argyrophilic senile plaques. These Aβ deposits were not immunolabeled with antibodies to the N-terminal of human Aβ. Sequence analysis of the amyloid precursor protein revealed an amino acid substitution at the 7th residue of the Aβ peptide. In a comparison with other mammalian animals that do develop argyrophilic senile plaques, we concluded that the alternative Aβ amino acid sequence displayed by leopard cats is likely to be related to its distinctive deposition pattern. Interestingly, most of the animals with these Aβ deposits also developed NFTs. The distributions of hyperphosphorylated tau-positive cells and the two major isoforms of aggregated tau proteins were quite similar to those seen in Alzheimer's disease. In addition, the unphosphorylated form of GSK-3β colocalized with hyperphosphorylated tau within the affected neurons. In conclusion, this animal species develops AD-type NFTs without argyrophilic senile plaques.

Loss of function of ATXN1 increases amyloid beta-protein levels by potentiating beta-secretase processing of beta-amyloid precursor protein.

Science.gov (United States)

Zhang, Can; Browne, Andrew; Child, Daniel; Divito, Jason R; Stevenson, Jesse A; Tanzi, Rudolph E

2010-03-19

Alzheimer disease (AD) is a devastating neurodegenerative disease with complex and strong genetic inheritance. Four genes have been established to either cause familial early onset AD (APP, PSEN1, and PSEN2) or to increase susceptibility for late onset AD (APOE). To date approximately 80% of the late onset AD genetic variance remains elusive. Recently our genome-wide association screen identified four novel late onset AD candidate genes. Ataxin 1 (ATXN1) is one of these four AD candidate genes and has been indicated to be the disease gene for spinocerebellar ataxia type 1, which is also a neurodegenerative disease. Mounting evidence suggests that the excessive accumulation of Abeta, the proteolytic product of beta-amyloid precursor protein (APP), is the primary AD pathological event. In this study, we ask whether ATXN1 may lead to AD pathogenesis by affecting Abeta and APP processing utilizing RNA interference in a human neuronal cell model and mouse primary cortical neurons. We show that knock-down of ATXN1 significantly increases the levels of both Abeta40 and Abeta42. This effect could be rescued with concurrent overexpression of ATXN1. Moreover, overexpression of ATXN1 decreased Abeta levels. Regarding the underlying molecular mechanism, we show that the effect of ATXN1 expression on Abeta levels is modulated via beta-secretase cleavage of APP. Taken together, ATXN1 functions as a genetic risk modifier that contributes to AD pathogenesis through a loss-of-function mechanism by regulating beta-secretase cleavage of APP and Abeta levels.

Quantifying the pattern of beta/A4 amyloid protein distribution in Alzheimer's disease by image analysis.

Science.gov (United States)

Bruce, C V; Clinton, J; Gentleman, S M; Roberts, G W; Royston, M C

1992-04-01

We have undertaken a study of the distribution of the beta/A4 amyloid deposited in the cerebral cortex in Alzheimer's disease. Previous studies which have examined the differential distribution of amyloid in the cortex in order to determine the laminar pattern of cortical pathology have not proved to be conclusive. We have developed an alternative method for the solution of this problem. It involves the immunostaining of sections followed by computer-enhanced image analysis. A mathematical model is then used to describe both the amount and the pattern of amyloid across the cortex. This method is both accurate and reliable and also removes many of the problems concerning inter and intra-rater variability in measurement. This method will provide the basis for further quantitative studies on the differential distribution of amyloid in Alzheimer's disease and other cases of dementia where cerebral amyloidosis occurs.

Microglia kill amyloid-beta1-42 damaged neurons by a CD14-dependent process

NARCIS (Netherlands)

Bate, Clive; Veerhuis, Robert; Eikelenboom, Piet; Williams, Alun

2004-01-01

Activated microglia are closely associated with neuronal damage in Alzheimer's disease. In the present study, neurons exposed to low concentrations of amyloid-beta1-42, a toxic fragment of the amyloid-beta protein, were killed by microglia in a process that required cell-cell contact. Pre-treating

Organotypic vibrosections from whole brain adult Alzheimer mice (overexpressing amyloid-precursor-protein with the Swedish-Dutch-Iowa mutations as a model to study clearance of beta-amyloid plaques

Directory of Open Access Journals (Sweden)

Christian eHumpel

2015-04-01

Full Text Available Alzheimer´s disease is a severe neurodegenerative disorder of the brain, pathologically characterized by extracellular beta-amyloid plaques, intraneuronal Tau inclusions, inflammation, reactive glial cells, vascular pathology and neuronal cell death. The degradation and clearance of beta-amyloid plaques is an interesting therapeutic approach, and the proteases neprilysin (NEP, insulysin and matrix metalloproteinases (MMP are of particular interest. The aim of this project was to establish and characterize a simple in vitro model to study the degrading effects of these proteases. Organoytpic brain vibrosections (120 µm thick were sectioned from adult (9 month old wildtype and transgenic mice (expressing amyloid precursor protein (APP harboring the Swedish K670N/M671L, Dutch E693Q, and Iowa D694N mutations; APP_SDI and cultured for 2 weeks. Plaques were stained by immunohistochemistry for beta-amyloid and Thioflavin S. Our data show that plaques were evident in 2 week old cultures from 9 month old transgenic mice. These plaques were surrounded by reactive GFAP+ astroglia and Iba1+ microglia. Incubation of fresh slices for 2 weeks with 1-0.1-0.01 µg/ml of NEP, insulysin, MMP-2 or MMP-9 showed that NEP, insulysin and MMP-9 markedly degradeded beta-amyloid plaques but only at the highest concentration. Our data provide for the first time a potent and powerful living brain vibrosection model containing a high number of plaques, which allows to rapidly and simply study the degradation and clearance of beta-amyloid plaques in vitro.

Specific localization and imaging of amyloid deposits in vivo using 123I-labeled serum amyloid P component

International Nuclear Information System (INIS)

Hawkins, P.N.; Myers, M.J.; Epenetos, A.A.; Caspi, D.; Pepys, M.B.

1988-01-01

Highly specific, high-resolution scintigraphic images of amyloid-laden organs in mice with experimentally induced amyloid A protein (AA) amyloidosis were obtained after intravenous injection of 123 I-labeled serum amyloid P component (SAP). Interestingly, a much higher proportion (up to 40%) of the injected dose of heterologous human SAP localized to amyloid and was retained there than was the case with isologous mouse SAP, indicating that human SAP binds more avidly to mouse AA fibrils than does mouse SAP. Specificity of SAP localization was established by the failure of the related proteins, human C-reactive protein and Limulus C-reactive protein, to deposit significantly in amyloid and by the absence of human SAP deposition in nonamyloidotic organs. However, only partial correlations were observed between the quantity of SAP localized and two independent estimates, histology and RIA for AA of the amount of amyloid in particular organs. It is not clear which of the three methods used reflects better the extent or clinical significance of the amyloid deposits but in vivo localization of radiolabeled SAP, detectable and quantifiable by gamma camera imaging, is apparently extremely sensitive. These findings establish the use of labeled SAP as a noninvasive in vivo diagnostic probe in experimental amyloidosis, potentially capable of revealing the natural history of the condition, and suggest that it may also be applicable generally as a specific targeting agent for diagnostic and even therapeutic purposes in clinical amyloidosis

Beta-structures in fibrous proteins.

Science.gov (United States)

Kajava, Andrey V; Squire, John M; Parry, David A D

2006-01-01

The beta-form of protein folding, one of the earliest protein structures to be defined, was originally observed in studies of silks. It was then seen in early studies of synthetic polypeptides and, of course, is now known to be present in a variety of guises as an essential component of globular protein structures. However, in the last decade or so it has become clear that the beta-conformation of chains is present not only in many of the amyloid structures associated with, for example, Alzheimer's Disease, but also in the prion structures associated with the spongiform encephalopathies. Furthermore, X-ray crystallography studies have revealed the high incidence of the beta-fibrous proteins among virulence factors of pathogenic bacteria and viruses. Here we describe the basic forms of the beta-fold, summarize the many different new forms of beta-structural fibrous arrangements that have been discovered, and review advances in structural studies of amyloid and prion fibrils. These and other issues are described in detail in later chapters.

Calcium-dependent and -independent binding of the pentraxin serum amyloid P component to glycosaminoglycans and amyloid proteins

DEFF Research Database (Denmark)

Danielsen, B; Sørensen, I J; Nybo, Mads

1997-01-01

precursor protein beta2M was observed. This binding was also enhanced at slightly acid pH, most pronounced at pH 5.0. The results of this study indicate that SAP can exhibit both Ca2(+)-dependent and -independent binding to ligands involved in amyloid fibril formation and that the binding is enhanced under...... and beta2M) by ELISA. An increase in the dose-dependent binding of SAP to heparan sulfate, AA-protein and beta2M was observed as the pH decreased from 8.0 to 5.0. Furthermore, a lower, but significant Ca2(+)-independent binding of SAP to heparan sulfate, dermatan sulfate, AA protein and the amyloid...

Molecular architecture of human prion protein amyloid: a parallel, in-register beta-structure.

Science.gov (United States)

Cobb, Nathan J; Sönnichsen, Frank D; McHaourab, Hassane; Surewicz, Witold K

2007-11-27

Transmissible spongiform encephalopathies (TSEs) represent a group of fatal neurodegenerative diseases that are associated with conformational conversion of the normally monomeric and alpha-helical prion protein, PrP(C), to the beta-sheet-rich PrP(Sc). This latter conformer is believed to constitute the main component of the infectious TSE agent. In contrast to high-resolution data for the PrP(C) monomer, structures of the pathogenic PrP(Sc) or synthetic PrP(Sc)-like aggregates remain elusive. Here we have used site-directed spin labeling and EPR spectroscopy to probe the molecular architecture of the recombinant PrP amyloid, a misfolded form recently reported to induce transmissible disease in mice overexpressing an N-terminally truncated form of PrP(C). Our data show that, in contrast to earlier, largely theoretical models, the con formational conversion of PrP(C) involves major refolding of the C-terminal alpha-helical region. The core of the amyloid maps to C-terminal residues from approximately 160-220, and these residues form single-molecule layers that stack on top of one another with parallel, in-register alignment of beta-strands. This structural insight has important implications for understanding the molecular basis of prion propagation, as well as hereditary prion diseases, most of which are associated with point mutations in the region found to undergo a refolding to beta-structure.

Generation of the beta-amyloid peptide and the amyloid precursor protein C-terminal fragment gamma are potentiated by FE65L1.

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Chang, Yang; Tesco, Giuseppina; Jeong, William J; Lindsley, Loren; Eckman, Elizabeth A; Eckman, Christopher B; Tanzi, Rudolph E; Guénette, Suzanne Y

2003-12-19

Members of the FE65 family of adaptor proteins, FE65, FE65L1, and FE65L2, bind the C-terminal region of the amyloid precursor protein (APP). Overexpression of FE65 and FE65L1 was previously reported to increase the levels of alpha-secretase-derived APP (APPs alpha). Increased beta-amyloid (A beta) generation was also observed in cells showing the FE65-dependent increase in APPs alpha. To understand the mechanism for the observed increase in both A beta and APPs alpha given that alpha-secretase cleavage of a single APP molecule precludes A beta generation, we examined the effects of FE65L1 overexpression on APP C-terminal fragments (APP CTFs). Our data show that FE65L1 potentiates gamma-secretase processing of APP CTFs, including the amyloidogenic CTF C99, accounting for the ability of FE65L1 to increase generation of APP C-terminal domain and A beta 40. The FE65L1 modulation of these processing events requires binding of FE65L1 to APP and APP CTFs and is not because of a direct effect on gamma-secretase activity, because Notch intracellular domain generation is not altered by FE65L1. Furthermore, enhanced APP CTF processing can be detected in early endosome vesicles but not in endoplasmic reticulum or Golgi membranes, suggesting that the effects of FE65L1 occur at or near the plasma membrane. Finally, although FE65L1 increases APP C-terminal domain production, it does not mediate the APP-dependent transcriptional activation observed with FE65.

Beta-amyloid precursor protein transgenic mice that harbor diffuse A beta deposits but do not form plaques show increased ischemic vulnerability: role of inflammation

Czech Academy of Sciences Publication Activity Database

Koistinaho, M.; Kettunen, M. I.; Goldsteins, G.; Keinänen, R.; Salminen, A.; Ort, Michael; Bureš, Jan; Liu, D.; Kauppinen, R. A.; Higgins, L. S.; Koistinaho, J.

2002-01-01

Roč. 99, č. 3 (2002), s. 1610-1615 ISSN 0027-8424 R&D Projects: GA ČR GA309/00/1656 Institutional research plan: CEZ:AV0Z5011922 Keywords : Beta-amyloid * Alzheimer disease * brain ischemia Subject RIV: FH - Neurology Impact factor: 10.701, year: 2002

Proteomic screening for amyloid proteins.

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Anton A Nizhnikov

Full Text Available Despite extensive study, progress in elucidation of biological functions of amyloids and their role in pathology is largely restrained due to the lack of universal and reliable biochemical methods for their discovery. All biochemical methods developed so far allowed only identification of glutamine/asparagine-rich amyloid-forming proteins or proteins comprising amyloids that form large deposits. In this article we present a proteomic approach which may enable identification of a broad range of amyloid-forming proteins independently of specific features of their sequences or levels of expression. This approach is based on the isolation of protein fractions enriched with amyloid aggregates via sedimentation by ultracentrifugation in the presence of strong ionic detergents, such as sarkosyl or SDS. Sedimented proteins are then separated either by 2D difference gel electrophoresis or by SDS-PAGE, if they are insoluble in the buffer used for 2D difference gel electrophoresis, after which they are identified by mass-spectrometry. We validated this approach by detection of known yeast prions and mammalian proteins with established capacity for amyloid formation and also revealed yeast proteins forming detergent-insoluble aggregates in the presence of human huntingtin with expanded polyglutamine domain. Notably, with one exception, all these proteins contained glutamine/asparagine-rich stretches suggesting that their aggregates arose due to polymerization cross-seeding by human huntingtin. Importantly, though the approach was developed in a yeast model, it can easily be applied to any organism thus representing an efficient and universal tool for screening for amyloid proteins.

Formation of soluble amyloid oligomers and amyloid fibrils by the multifunctional protein vitronectin

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Langen Ralf

2008-10-01

Full Text Available Abstract Background The multifunctional protein vitronectin is present within the deposits associated with Alzheimer disease (AD, age-related macular degeneration (AMD, atherosclerosis, systemic amyloidoses, and glomerulonephritis. The extent to which vitronectin contributes to amyloid formation within these plaques, which contain misfolded, amyloidogenic proteins, and the role of vitronectin in the pathophysiology of the aforementioned diseases is currently unknown. The investigation of vitronectin aggregation is significant since the formation of oligomeric and fibrillar structures are common features of amyloid proteins. Results We observed vitronectin immunoreactivity in senile plaques of AD brain, which exhibited overlap with the amyloid fibril-specific OC antibody, suggesting that vitronectin is deposited at sites of amyloid formation. Of particular interest is the growing body of evidence indicating that soluble nonfibrillar oligomers may be responsible for the development and progression of amyloid diseases. In this study we demonstrate that both plasma-purified and recombinant human vitronectin readily form spherical oligomers and typical amyloid fibrils. Vitronectin oligomers are toxic to cultured neuroblastoma and retinal pigment epithelium (RPE cells, possibly via a membrane-dependent mechanism, as they cause leakage of synthetic vesicles. Oligomer toxicity was attenuated in RPE cells by the anti-oligomer A11 antibody. Vitronectin fibrils contain a C-terminal protease-resistant fragment, which may approximate the core region of residues essential to amyloid formation. Conclusion These data reveal the propensity of vitronectin to behave as an amyloid protein and put forth the possibilities that accumulation of misfolded vitronectin may contribute to aggregate formation seen in age-related amyloid diseases.

Kinetically controlled thermal response of beta2-microglobulin amyloid fibrils.

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Sasahara, Kenji; Naiki, Hironobu; Goto, Yuji

2005-09-23

Calorimetric measurements were carried out using a differential scanning calorimeter in the temperature range from 10 to 120 degrees C for characterizing the thermal response of beta2-microglobulin amyloid fibrils. The thermograms of amyloid fibril solution showed a remarkably large decrease in heat capacity that was essentially released upon the thermal unfolding of the fibrils, in which the magnitude of negative heat capacity change was not explicable in terms of the current accessible surface area model of protein structural thermodynamics. The heat capacity-temperature curve of amyloid fibrils prior to the fibril unfolding exhibited an unusual dependence on the fibril concentration and the heating rate. Particularly, the heat needed to induce the thermal response was found to be linearly dependent on the heating rate, indicating that its thermal response is under a kinetic control and precluding the interpretation in terms of equilibrium thermodynamics. Furthermore, amyloid fibrils of amyloid beta peptides also exhibited a heating rate-dependent exothermic process before the fibril unfolding, indicating that the kinetically controlled thermal response may be a common phenomenon to amyloid fibrils. We suggest that the heating rate-dependent negative change in heat capacity is coupled to the association of amyloid fibrils with characteristic hydration pattern.

Evidence for novel beta-sheet structures in Iowa mutant beta-amyloid fibrils.

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Tycko, Robert; Sciarretta, Kimberly L; Orgel, Joseph P R O; Meredith, Stephen C

2009-07-07

Asp23-to-Asn mutation within the coding sequence of beta-amyloid, called the Iowa mutation, is associated with early onset, familial Alzheimer's disease and cerebral amyloid angiopathy, in which patients develop neuritic plaques and massive vascular deposition predominantly of the mutant peptide. We examined the mutant peptide, D23N-Abeta40, by electron microscopy, X-ray diffraction, and solid-state NMR spectroscopy. D23N-Abeta40 forms fibrils considerably faster than the wild-type peptide (k = 3.77 x 10(-3) min(-1) and 1.07 x 10(-4) min(-1) for D23N-Abeta40 and the wild-type peptide WT-Abeta40, respectively) and without a lag phase. Electron microscopy shows that D23N-Abeta40 forms fibrils with multiple morphologies. X-ray fiber diffraction shows a cross-beta pattern, with a sharp reflection at 4.7 A and a broad reflection at 9.4 A, which is notably smaller than the value for WT-Abeta40 fibrils (10.4 A). Solid-state NMR measurements indicate molecular level polymorphism of the fibrils, with only a minority of D23N-Abeta40 fibrils containing the in-register, parallel beta-sheet structure commonly found in WT-Abeta40 fibrils and most other amyloid fibrils. Antiparallel beta-sheet structures in the majority of fibrils are indicated by measurements of intermolecular distances through (13)C-(13)C and (15)N-(13)C dipole-dipole couplings. An intriguing possibility exists that there is a relationship between the aberrant structure of D23N-Abeta40 fibrils and the unusual vasculotropic clinical picture in these patients.

Diagnostic radionuclide imaging of amyloid: biological targeting by circulating human serum amyloid P component

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Hawkins, P.N.; Lavender, J.P.; Myers, M.J.; Pepys, M.B.

1988-06-25

The specific molecular affinity of the normal plasma protein, serum amyloid P component (SAP), for all known types of amyloid fibrils was used to develop a new general diagnostic method for in-vivo radionuclide imaging of amyloid deposits. After intravenous injection of /sup 123/I-labelled purified human SAP there was specific uptake into amyloid deposits in all affected patients, 7 with systematic AL amyloid, 5 with AA amyloid, and 2 with ..beta../sub 2/M amyloid, in contrast to the complete absence of any tissue localisation in 5 control subjects. Distinctive high-resolution scintigraphic images, even of minor deposits in the carpal regions, bone marrow, or adrenals, were obtained. This procedure should yield much information on the natural history and the management of amyloidosis, the presence of which has hitherto been confirmed only by biopsy. Clearance and metabolic studies indicated that, in the presence of extensive amyloidosis, the rate of synthesis of SAP was greatly increased despite maintenance of normal plasma levels. Futhermore, once localised to amyloid deposits the /sup 123/I-SAP persisted for long periods and was apparently protected from its normal rapid degradation. These findings shed new light on the pathophysiology of amyloid and may have implications for therapeutic strategies based upon specific molecular targeting with SAP.

Insulin inhibits amyloid beta-induced cell death in cultured human brain pericytes

NARCIS (Netherlands)

Rensink, Annemieke A M; Otte-Höller, Irene; de Boer, Roelie; Bosch, Remko R; ten Donkelaar, Hans J; de Waal, Robert M W; Verbeek, Marcel M; Kremer, Berry

Amyloid-beta (Abeta) deposition in the cerebral arterial and capillary walls is one of the characteristics of Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis-Dutch type. In vitro, Abeta1-40, carrying the "Dutch" mutation (DAbeta1-40), induced reproducible degeneration of

Amyloid Imaging in Aging and Dementia: Testing the Amyloid Hypothesis In Vivo

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G. D. Rabinovici

2009-01-01

Full Text Available Amyloid imaging represents a major advance in neuroscience, enabling the detection and quantification of pathologic protein aggregations in the brain. In this review we survey current amyloid imaging techniques, focusing on positron emission tomography (PET with ^{11}carbon-labelled Pittsburgh Compound-B (11C-PIB, the most extensively studied and best validated tracer. PIB binds specifically to fibrillar beta-amyloid (Aβ deposits, and is a sensitive marker for Aβ pathology in cognitively normal older individuals and patients with mild cognitive impairment (MCI and Alzheimer’s disease (AD. PIB-PET provides us with a powerful tool to examine in vivo the relationship between amyloid deposition, clinical symptoms, and structural and functional brain changes in the continuum between normal aging and AD. Amyloid imaging studies support a model in which amyloid deposition is an early event on the path to dementia, beginning insidiously in cognitively normal individuals, and accompanied by subtle cognitive decline and functional and structural brain changes suggestive of incipient AD. As patients progress to dementia, clinical decline and neurodegeneration accelerate and proceed independently of amyloid accumulation. In the future, amyloid imaging is likely to supplement clinical evaluation in selecting patients for anti-amyloid therapies, while MRI and FDG-PET may be more appropriate markers of clinical progression.

Multiscale Molecular Dynamics Simulations of Beta-Amyloid Interactions with Neurons

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Qiu, Liming; Vaughn, Mark; Cheng, Kelvin

2012-10-01

Early events of human beta-amyloid protein interactions with cholesterol-containing membranes are critical to understanding the pathogenesis of Alzheimer's disease (AD) and to exploring new therapeutic interventions of AD. Atomistic molecular dynamics (AMD) simulations have been extensively used to study the protein-lipid interaction at high atomic resolutions. However, traditional MD simulations are not efficient in sampling the phase space of complex lipid/protein systems with rugged free energy landscapes. Meanwhile, coarse-grained MD (CGD) simulations are efficient in the phase space sampling but suffered from low spatial resolutions and from the fact that the energy landscapes are not identical to those of the AMD. Here, a multiscale approach was employed to simulate the protein-lipid interactions of beta-amyloid upon its release from proteolysis residing in the neuronal membranes. We utilized a forward (AMD to CGD) and reverse (CGD-AMD) strategy to explore new transmembrane and surface protein configuration and evaluate the stabilization mechanisms by measuring the residue-specific protein-lipid or protein conformations. The detailed molecular interactions revealed in this multiscale MD approach will provide new insights into understanding the early molecular events leading to the pathogenesis of AD.

beta. -Amyloid gene dosage in Alzheimer's disease

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Murdoch, G H; Manuelidis, L; Kim, J H; Manuelidis, E E

1988-01-11

The 4-5 kd amyloid ..beta..-peptide is a major constituent of the characteristic amyloid plaque of Alzheimer's disease. It has been reported that some cases of sporatic Alzheimer's disease are associated with at least a partial duplication of chromosome 21 containing the gene corresponding to the 695 residue precursor of this peptide. To contribute to an understanding of the frequency to such a duplication event in the overall Alzheimer's population, the authors have determined the gene dosage of the ..beta..-amyloid gene in this collection of cases. All cases had a clinical diagnosis of Alzheimer's confirmed neuropathologically. Each Alzheimer's case had an apparent normal diploid ..beta..-amyloid gene dosage, while control Down's cases had the expected triploid dosage. Thus partial duplication of chromosome 21 may be a rare finding in Alzheimer's disease. Similar conclusions were just reported in several studies of the Harvard Alzheimer collection.

The role of mutated amyloid beta 1-42 stimulating dendritic cells in a PDAPP transgenic mouse

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LI Jia-lin

2012-06-01

Full Text Available Background Amyloid plaque is one of the pathological hallmarks of Alzheimer's disease (AD. Anti-beta-amyloid (Aβ immunotherapy is effective in removing brain Aβ, but has shown to be associated with detrimental effects. To avoid severe adverse effects such as meningoencephalitis induced by amyloid beta vaccine with adjuvant, and take advantage of amyloid beta antibody's therapeutic effect on Alzheimer's disease sufficiently, our group has developed a new Alzheimer vaccine with mutated amyloid beta 1-42 peptide stimulating dendritic cells (DC. Our previous work has confirmed that DC vaccine can induce adequate anti-amyloid beta antibody in PDAPP Tg mice safely and efficiently. The DC vaccine can improve impaired learning and memory in the Alzheimer's animal model, and did not cause microvasculitis, microhemorrhage or meningoencephalitis in the animal model. However, the exact mechanism of immunotherapy which reduces Aβ deposition remains unknown. In this report, we studied the mechanism of the vaccine, thinking that this may have implications for better understanding of the pathogenesis of Alzheimer's disease. Methods A new Alzheimer vaccine with mutated amyloid beta 1-42 peptide stimulating DC which were obtained from C57/B6 mouse bone marrow was developed. Amyloid beta with Freund's adjuvant was inoculated at the same time to act as positive control. After the treatment was done, the samples of brains were collected, fixed, cut. Immunohistochemical staining was performed to observe the expression of the nuclear hormone liver X receptor (LXR, membrane-bound protein tyrosine phosphatase (CD45, the ATP-binding cassette family of active transporters (ABCA1, receptor for advanced glycation end products (RAGE, β-site APP-cleaving enzyme (BACE and Aβ in mouse brain tissue. Semi-quantitative analysis was used to defect CA1, CA2, CA3, DG, Rad in hippocampus region and positive neuron in cortex region. Results Aβ was significantly reduced in the

A role for 12/15 lipoxygenase in the amyloid beta precursor protein metabolism.

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Succol, Francesca; Praticò, Domenico

2007-10-01

12/15 Lipoxygenase (12/15LO) protein levels and activity are increased in pathologically affected regions of Alzheimer's disease (AD) brains, compared with controls. Its metabolic products are elevated in cerebrospinal fluid of patients with AD and individuals with mild cognitive impairment, suggesting that this enzyme may be involved early in AD pathogenesis. Herein, we investigate the effect of pharmacologic inhibition of 12/15LO on the amyloid beta precursor protein (APP) metabolism. To this end, we used CHO and N2A cells stably expressing human APP with the Swedish mutant, and two structurally distinct and selective 12/15LO inhibitors, PD146176 and CDC. Our results demonstrated that both drugs dose-dependently reduced Abeta formation without affecting total APP levels. Interestingly, in the same cells we observed a significant reduction in secreted (s)APPbeta and beta-secretase (BACE), but not sAPPalpha and ADAM10 protein levels. Together, these data show for the first time that this enzymatic pathway influences Abeta formation whereby modulating the BACE proteolytic cascade. We conclude that specific pharmacologic inhibition of 12/15LO could represent a novel therapeutic target for treating or preventing AD pathology in humans.

Immunotherapy of Alzheimer's disease (AD): from murine models to anti-amyloid beta (Abeta) human monoclonal antibodies.

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Geylis, Valeria; Steinitz, Michael

2006-01-01

The deposition of amyloid beta (Abeta) protein is a key pathological feature in Alzheimer's disease (AD). In murine models of AD, both active and passive immunization against Abeta induce a marked reduction in amyloid brain burden and an improvement in cognitive functions. Preliminary results of a prematurely terminated clinical trial where AD patients were actively vaccinated with aggregated Abeta bear resemblance to those documented in murine models. Passive immunization of AD patients with anti-Abeta antibodies, in particular human antibodies, is a strategy that provides a more cautious management and control of any undesired side effects. Sera of all healthy adults contain anti-Abeta IgG autoimmune antibodies. Hence antigen-committed human B-cells are easily immortalized by Epstein-Barr virus (EBV) into anti-Abeta secreting cell lines. Two anti-Abeta human monoclonal antibodies which we recently prepared bind to the N-terminus of Abeta peptide and were shown to stain amyloid plaques in non-fixed brain sections from an AD patient. It is anticipated that specifically selected anti-Abeta human monoclonal antibodies could reduce and inhibit deposits of amyloid in brain while avoiding the cognitive decline that characterizes AD. In the future, this type of antibody may prove to be a promising immune therapy for the disease.

Mouse senile amyloid fibrils deposited in skeletal muscle exhibit amyloidosis-enhancing activity.

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Jinze Qian

2010-05-01

Full Text Available Amyloidosis describes a group of protein folding diseases in which amyloid proteins are abnormally deposited in organs and/or tissues as fine fibrils. Mouse senile amyloidosis is a disorder in which apolipoprotein A-II (apoA-II deposits as amyloid fibrils (AApoAII and can be transmitted from one animal to another both by the feces and milk excreted by mice with amyloidosis. Thus, mouse AApoAII amyloidosis has been demonstrated to be a "transmissible disease". In this study, to further characterize the transmissibility of amyloidosis, AApoAII amyloid fibrils were injected into transgenic Apoa2(cTg(+/- and normal R1.P1-Apoa2(c mice to induce AApoAII systemic amyloidosis. Two months later, AApoAII amyloid deposits were found in the skeletal muscles of amyloid-affected mice, primarily in the blood vessels and in the interstitial tissues surrounding muscle fibers. When amyloid fibrils extracted from the skeletal muscles were subjected to Western blot analysis, apoA-II was detected. Amyloid fibril fractions isolated from the muscles not only demonstrated the structure of amyloid fibrils but could also induce amyloidosis in young mice depending on its fibril conformation. These findings present a possible pathogenesis of amyloidosis: transmission of amyloid fibril conformation through muscle, and shed new light on the etiology involved in amyloid disorders.

Inhibition of Alzheimer amyloid {beta} aggregation by polyvalent trehalose

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Miura, Yoshiko; You, Chouga [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Ohnishi, Reiko [Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)], E-mail: miuray@jaist.ac.jp

2008-04-15

A glycopolymer carrying trehalose was found to suppress the formation of amyloid fibrils from the amyloid {beta} peptide (1-42) (A{beta}), as evaluated by thioflavin T assay and atomic force microscopy. Glycopolymers carrying sugar alcohols also changed the aggregation properties of A{beta}, and the inhibitory effect depended on the type of sugar and alkyl side chain. Neutralization activity was confirmed by in vitro assay using HeLa cells. The glycopolymer carrying trehalose strongly inhibited amyloid formation and neutralized cytotoxicity.

Disrupting beta-amyloid aggregation for Alzheimer disease treatment.

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Estrada, L D; Soto, C

2007-01-01

Alzheimer's disease is a devastating degenerative disorder for which there is no cure or effective treatment. Although the etiology of Alzheimer's disease is not fully understood, compelling evidence indicates that deposition of aggregates composed by a misfolded form of the amyloid beta peptide (Abeta) is the central event in the disease pathogenesis. Therefore, an attractive therapeutic strategy is to prevent or reverse Abeta misfolding and aggregation. Diverse strategies have been described to identify inhibitors of this process, including screening of libraries of small molecules chemical compounds, rational design of synthetic peptides, assessment of natural Abeta-binding proteins and stimulation of the immune system by vaccination. In this article we describe these different approaches, their principles and their potential strengths and weaknesses. Overall the available data suggest that the development of drugs to interfere with Abeta misfolding and aggregation is a feasible target that hold great promise for the treatment of Alzheimer's disease.

First demonstration of cerebrospinal fluid and plasma A beta lowering with oral administration of a beta-site amyloid precursor protein-cleaving enzyme 1 inhibitor in nonhuman primates.

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Sankaranarayanan, Sethu; Holahan, Marie A; Colussi, Dennis; Crouthamel, Ming-Chih; Devanarayan, Viswanath; Ellis, Joan; Espeseth, Amy; Gates, Adam T; Graham, Samuel L; Gregro, Allison R; Hazuda, Daria; Hochman, Jerome H; Holloway, Katharine; Jin, Lixia; Kahana, Jason; Lai, Ming-tain; Lineberger, Janet; McGaughey, Georgia; Moore, Keith P; Nantermet, Philippe; Pietrak, Beth; Price, Eric A; Rajapakse, Hemaka; Stauffer, Shaun; Steinbeiser, Melissa A; Seabrook, Guy; Selnick, Harold G; Shi, Xiao-Ping; Stanton, Matthew G; Swestock, John; Tugusheva, Katherine; Tyler, Keala X; Vacca, Joseph P; Wong, Jacky; Wu, Guoxin; Xu, Min; Cook, Jacquelynn J; Simon, Adam J

2009-01-01

beta-Site amyloid precursor protein (APP)-cleaving enzyme (BACE) 1 cleavage of amyloid precursor protein is an essential step in the generation of the potentially neurotoxic and amyloidogenic A beta 42 peptides in Alzheimer's disease. Although previous mouse studies have shown brain A beta lowering after BACE1 inhibition, extension of such studies to nonhuman primates or man was precluded by poor potency, brain penetration, and pharmacokinetics of available inhibitors. In this study, a novel tertiary carbinamine BACE1 inhibitor, tertiary carbinamine (TC)-1, was assessed in a unique cisterna magna ported rhesus monkey model, where the temporal dynamics of A beta in cerebrospinal fluid (CSF) and plasma could be evaluated. TC-1, a potent inhibitor (IC(50) approximately 0.4 nM), has excellent passive membrane permeability, low susceptibility to P-glycoprotein transport, and lowered brain A beta levels in a mouse model. Intravenous infusion of TC-1 led to a significant but transient lowering of CSF and plasma A beta levels in conscious rhesus monkeys because it underwent CYP3A4-mediated metabolism. Oral codosing of TC-1 with ritonavir, a potent CYP3A4 inhibitor, twice daily over 3.5 days in rhesus monkeys led to sustained plasma TC-1 exposure and a significant and sustained reduction in CSF sAPP beta, A beta 40, A beta 42, and plasma A beta 40 levels. CSF A beta 42 lowering showed an EC(50) of approximately 20 nM with respect to the CSF [TC-1] levels, demonstrating excellent concordance with its potency in a cell-based assay. These results demonstrate the first in vivo proof of concept of CSF A beta lowering after oral administration of a BACE1 inhibitor in a nonhuman primate.

Metabolic Characterization of Intact Cells Reveals Intracellular Amyloid Beta but Not Its Precursor Protein to Reduce Mitochondrial Respiration

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Schaefer, Patrick M.; von Einem, Bjoern; Walther, Paul; Calzia, Enrico; von Arnim, Christine A. F.

2016-01-01

One hallmark of Alzheimer´s disease are senile plaques consisting of amyloid beta (Aβ), which derives from the processing of the amyloid precursor protein (APP). Mitochondrial dysfunction has been linked to the pathogenesis of Alzheimer´s disease and both Aβ and APP have been reported to affect mitochondrial function in isolated systems. However, in intact cells, considering a physiological localization of APP and Aβ, it is pending what triggers the mitochondrial defect. Thus, the aim of this study was to dissect the impact of APP versus Aβ in inducing mitochondrial alterations with respect to their subcellular localization. We performed an overexpression of APP or beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), increasing APP and Aβ levels or Aβ alone, respectively. Conducting a comprehensive metabolic characterization we demonstrate that only APP overexpression reduced mitochondrial respiration, despite lower extracellular Aβ levels compared to BACE overexpression. Surprisingly, this could be rescued by a gamma secretase inhibitor, oppositionally indicating an Aβ-mediated mitochondrial toxicity. Analyzing Aβ localization revealed that intracellular levels of Aβ and an increased spatial association of APP/Aβ with mitochondria are associated with reduced mitochondrial respiration. Thus, our data provide marked evidence for a prominent role of intracellular Aβ accumulation in Alzheimer´s disease associated mitochondrial dysfunction. Thereby it highlights the importance of the localization of APP processing and intracellular transport as a decisive factor for mitochondrial function, linking two prominent hallmarks of neurodegenerative diseases. PMID:28005987

The common inhalation anesthetic isoflurane induces caspase activation and increases amyloid beta-protein level in vivo.

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Xie, Zhongcong; Culley, Deborah J; Dong, Yuanlin; Zhang, Guohua; Zhang, Bin; Moir, Robert D; Frosch, Matthew P; Crosby, Gregory; Tanzi, Rudolph E

2008-12-01

An estimated 200 million patients worldwide have surgery each year. Anesthesia and surgery have been reported to facilitate emergence of Alzheimer's disease. The commonly used inhalation anesthetic isoflurane has previously been reported to induce apoptosis, and to increase levels and aggregation of Alzheimer's disease-associated amyloid beta-protein (Abeta) in cultured cells. However, the in vivo relevance has not been addressed. We therefore set out to determine effects of isoflurane on caspase activation and levels of beta-site amyloid precursor protein-cleaving enzyme (BACE) and Abeta in naive mice, using Western blot, immunohistochemistry, and reverse transcriptase polymerase chain reaction. Here we show for the first time that a clinically relevant isoflurane anesthesia (1.4% isoflurane for 2 hours) leads to caspase activation and modest increases in levels of BACE 6 hours after anesthesia in mouse brain. Isoflurane anesthesia induces caspase activation, and increases levels of BACE and Abeta up to 24 hours after anesthesia. Isoflurane may increase BACE levels by reducing BACE degradation. Moreover, the Abeta aggregation inhibitor, clioquinol, was able to attenuate isoflurane-induced caspase-3 activation in vivo. Given that transient insults to brain may lead to long-term brain damage, these findings suggest that isoflurane may promote Alzheimer's disease neuropathogenesis and, as such, have implications for use of isoflurane in humans, pending human study confirmation.

Imaging characteristic of dual-phase 18F-florbetapir (AV-45/Amyvid) PET for the concomitant detection of perfusion deficits and beta-amyloid deposition in Alzheimer's disease and mild cognitive impairment

International Nuclear Information System (INIS)

Lin, Kun-Ju; Hsiao, Ing-Tsung; Hsieh, Chia-Ju; Wey, Shiaw-Pyng; Yen, Tzu-Chen; Hsu, Jung-Lung; Huang, Chin-Chang; Huang, Kuo-Lun

2016-01-01

We investigated dual-phase 18 F-florbetapir (AV-45/Amyvid) PET imaging for the concomitant detection of brain perfusion deficits and beta-amyloid deposition in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (MCI), and in cognitively healthy controls (HCs). A total of 82 subjects (24 AD patients, 44 MCI patients and 14 HCs) underwent both dual-phase 18 F-AV-45 PET and MRI imaging. Dual-phase dynamic PET imaging consisted of (1) five 1-min scans obtained 1 - 6 min after tracer injection (perfusion 18 F-AV-45 imaging, pAV-45), and (2) ten 1-min scans obtained 50 - 60 min after tracer injection (amyloid 18 F-AV-45 imaging). Amyloid-negative MCI/AD patients were excluded. Volume of interest analysis and statistical parametric mapping of pAV-45 and 18 F-AV-45 images were performed to investigate the perfusion deficits and the beta-amyloid burden in the three study groups. The associations between Mini-Mental State Examination (MMSE) scores and global perfusion deficits and amyloid deposition were investigated with linear and segmental linear correlation analyses. HCs generally had normal pAV-45 findings, whereas perfusion deficits were evident in the hippocampus, and temporal, parietal and middle frontal cortices in both MCI and AD patients. The motor-sensory cortex was relatively preserved. MMSE scores in the entire study cohort were significantly associated with the degree of perfusion impairment as assessed by pAV-45 imaging (r = 0.5156, P < 0.0001). 18 F-AV-45 uptake was significantly higher in AD patients than in the two other study groups. However, the correlation between MMSE scores and 18 F-AV-45 uptake in MCI patients was more of a binary phenomenon and began in MCI patients with MMSE score 23.14 when 18 F-AV-45 uptake was higher and MMSE score lower than in patients with early MCI. Amyloid deposition started in the precuneus and the frontal and temporal regions in early MCI, ultimately reaching the maximum burden in advanced

Amyloid-like protein inclusions in tobacco transgenic plants.

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Anna Villar-Piqué

Full Text Available The formation of insoluble protein deposits in human tissues is linked to the onset of more than 40 different disorders, ranging from dementia to diabetes. In these diseases, the proteins usually self-assemble into ordered β-sheet enriched aggregates known as amyloid fibrils. Here we study the structure of the inclusions formed by maize transglutaminase (TGZ in the chloroplasts of tobacco transplastomic plants and demonstrate that they have an amyloid-like nature. Together with the evidence of amyloid structures in bacteria and fungi our data argue that amyloid formation is likely a ubiquitous process occurring across the different kingdoms of life. The discovery of amyloid conformations inside inclusions of genetically modified plants might have implications regarding their use for human applications.

Nuclear imaging of amyloid deposits based upon thioflavins

International Nuclear Information System (INIS)

Wang Yanming; Wu Chunying; Wei Jinjun

2005-01-01

Alzheimer's Disease (AD) is a chronic neurodegenerative disorders characterized by the presence of amyloid deposits and neurofibrillar tangles in the brain. Direct assessment of local changes of amyloid deposits in vivo would greatly facilitate the diagnosis and therapeutic treatments of AD. The goal of this study is to develop small-molecule probes that can be used to follow amyloid deposition in vivo in patients with neurodegenerative diseases. Over the past years, we set out to develop a series of small molecules based on thioflavins as radiotracers for use in nuclear imaging modalities such as positron emission tomography and single photon emission computed tomography. The potential of these amyloid-imaging agents for in vivo studies of amyloid deposition has been evaluated based on the following methods: 1) spectrophotometric binding. assays with synthetic amyloid-β (Aβ) fibrils and AD brain homogenates; 2) fluorescent staining of brain tissue sections to evaluate specificity of binding to amyloid deposits; 3) fluorescent microscopy in mouse models to determine the brain permeability and characterize the binding specificity in vivo, and 4) PET studies in human subjects diagnosed with AD and age-matched control subjects. To date, we have identified some lead compounds as molecular probes with specificity towards amyloid deposits. The in vitro and in vivo binding properties of these compounds have been demonstrated in the following ways: 1) they selectively binds to Aβ fibrils; 2) they selectively stains amyloid deposits in AD brain tissue sections; 3) they readily penetrates the blood-brain barrier, selectively detects amyloid deposits in vivo iri living mice; and 4) One of these compounds, termed PIB, has been successfully used in PET studies in human subjects. In conclusion, amyloid-imaging probes have been developed that could be used to monitor amyloid load in vivo. Applications of the probes are under investigation for potential pathophysiology studies

Green-fluorescent protein+ Astrocytes Attach to beta-Amyloid Plaques in an Alzheimer Mouse Model and GFPare Sensitive for Clasmatodendrosis

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Christian eHumpel

2016-04-01

Full Text Available Alzheimer’s disease (AD is pathologically characterized by beta-amyloid (Aβ plaques and Tau pathology. It is well-established that Aβ plaques are surrounded by reactive astrocytes, highly expressing glial fibrillary acidic protein (GFAP. In order to study the cellular interaction of reactive astrocytes with Aβ plaques, we crossbred mice overexpressing amyloid precursor protein (APP with the Swedish-Dutch-Iowa mutations (APP-SweDI with mice expressing green fluorescent protein (GFP under the GFAP-promotor. Three-dimensional confocal microscopy revealed a tight association and intense sprouting of astrocytic fine branched processes towards Aβ plaques in 12 month old mice. In order to study phagocytosis, 110 µm thick brain slices from 12 month old crossbred mice were cultured overnight, however, we found that the GFP fluorescence faded away, distal processes degenerated and a complete loss of astrocytic morphology was seen (clasmatodendrosis. In summary, our data show that GFP+ reactive astrocytes make intense contact with Aβ plaques but these cells are highly vulnerable for degeneration.

Beyond the neurotransmitter-focused approach in treating Alzheimer's disease: drugs targeting beta-amyloid and tau protein.

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Panza, Francesco; Solfrizzi, Vincenzo; Frisardi, Vincenza; Imbimbo, Bruno P; Capurso, Cristiano; D'Introno, Alessia; Colacicco, Anna M; Seripa, Davide; Vendemiale, Gianluigi; Capurso, Antonio; Pilotto, Alberto

2009-12-01

Drugs currently used to treat Alzheimer's Disease (AD) have limited therapeutic value and do not affect the main neuropathological hallmarks of the disease, i.e., senile plaques and neurofibrillar tangles. Senile plaques are mainly formed of beta-amyloid (Abeta), a 42-aminoacid peptide. Neurofibrillar tangles are composed of paired helical filaments of hyperphosphorylated tau protein. New, potentially disease-modifying, therapeutic approaches are targeting Abeta and tau protein. Drugs directed against Abeta include active and passive immunization, that have been found to accelerate Abeta clearance from the brain. The most developmentally advanced monoclonal antibody directly targeting Abeta is bapineuzumab, now being studied in a large Phase III clinical trial. Compounds that interfere with proteases regulating Abeta formation from amyloid precursor protein (APP) are also actively pursued. The discovery of inhibitors of beta-secretase, the enzyme that regulates the first step of the amyloidogenic metabolism of APP, has been revealed to be particularly difficult due to inherent medicinal chemistry problems, and only one compound (CTS-21166) has reached clinical testing. Conversely, several compounds that inhibit gamma-secretase, the pivotal enzyme that generates Abeta, have been identified, the most advanced being LY-450139 (semagacestat), now in Phase III clinical development. Compounds that stimulate alpha-secretase, the enzyme responsible for the non-amyloidogenic metabolism of APP, are also being developed, and one of them, EHT-0202, has recently entered Phase II testing. Potent inhibitors of Abeta aggregation have also been identified, and one of such compounds, PBT-2, has provided encouraging neuropsychological results in a recently completed Phase II study. Therapeutic approaches directed against tau protein include inhibitors of glycogen synthase kinase- 3 (GSK-3), the enzyme responsible for tau phosphorylation and tau protein aggregation inhibitors. NP-12

Uncaria rhynchophylla, a Chinese medicinal herb, has potent antiaggregation effects on Alzheimer's beta-amyloid proteins.

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Fujiwara, Hironori; Iwasaki, Koh; Furukawa, Katsutoshi; Seki, Takashi; He, Mei; Maruyama, Masahiro; Tomita, Naoki; Kudo, Yukitsuka; Higuchi, Makoto; Saido, Takaomi C; Maeda, Sumihiro; Takashima, Akihiko; Hara, Masahiko; Ohizumi, Yasushi; Arai, Hiroyuki

2006-08-01

Because the deposition of beta-amyloid protein (Abeta) is a consistent pathological hallmark of Alzheimer's disease (AD) brains, inhibition of Abeta generation, prevention of Abeta fibril formation, or destabilization of preformed Abeta fibrils would be attractive therapeutic strategies for the treatment of AD. We examined the effects of several medicinal herbs used in traditional Chinese medical formulae on the formation and destabilization of Abeta fibrils by using the thioflavin T binding assay, atomic force microscopic imaging, and electrophoresis. Our study demonstrates that several of these herbs have potent inhibitory effects on fibril formation of both Abeta(1-40) and Abeta(1-42) in concentration-dependent manners; in particular, Uncaria rhynchophylla inhibited Abeta aggregation most intensively. Significant destabilization of preformed Abeta(1-40) and Abeta(1-42) fibrils was also induced by Uncaria rhynchophylla as well as some other herb extracts. Three-dimensional HPLC analysis indicated that the water extract of this herb contains several different chemical compounds, including oxindole and indol alkaloids, which have been regarded as neuroprotective. Our results suggest that Uncaria rhynchophylla has remarkably inhibitory effects on the regulation of Abeta fibrils, and we conclude that this medicinal herb could have the potency to be a novel therapeutic agent to prevent and/or cure AD.

Imaging characteristic of dual-phase {sup 18}F-florbetapir (AV-45/Amyvid) PET for the concomitant detection of perfusion deficits and beta-amyloid deposition in Alzheimer's disease and mild cognitive impairment

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Lin, Kun-Ju; Hsiao, Ing-Tsung; Hsieh, Chia-Ju; Wey, Shiaw-Pyng; Yen, Tzu-Chen [Linkou Chang Gung Memorial Hospital and University, Department of Nuclear Medicine and Molecular Imaging Center, Taoyuan (China); Chang Gung University, Department of Medical Imaging and Radiological Sciences and Healthy Aging Research Center, Taoyuan (China); Hsu, Jung-Lung [Linkou Chang Gung Memorial Hospital, Section of Dementia and Cognitive Impairment, Department of Neurology, Taoyuan (China); Taipei Medical University, Graduate Institute of Humanities in Medicine, Taipei (China); Huang, Chin-Chang; Huang, Kuo-Lun [Linkou Chang Gung Memorial Hospital and University, Department of Neurology, Taoyuan (China)

2016-07-15

We investigated dual-phase {sup 18}F-florbetapir (AV-45/Amyvid) PET imaging for the concomitant detection of brain perfusion deficits and beta-amyloid deposition in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (MCI), and in cognitively healthy controls (HCs). A total of 82 subjects (24 AD patients, 44 MCI patients and 14 HCs) underwent both dual-phase {sup 18}F-AV-45 PET and MRI imaging. Dual-phase dynamic PET imaging consisted of (1) five 1-min scans obtained 1 - 6 min after tracer injection (perfusion {sup 18}F-AV-45 imaging, pAV-45), and (2) ten 1-min scans obtained 50 - 60 min after tracer injection (amyloid {sup 18}F-AV-45 imaging). Amyloid-negative MCI/AD patients were excluded. Volume of interest analysis and statistical parametric mapping of pAV-45 and {sup 18}F-AV-45 images were performed to investigate the perfusion deficits and the beta-amyloid burden in the three study groups. The associations between Mini-Mental State Examination (MMSE) scores and global perfusion deficits and amyloid deposition were investigated with linear and segmental linear correlation analyses. HCs generally had normal pAV-45 findings, whereas perfusion deficits were evident in the hippocampus, and temporal, parietal and middle frontal cortices in both MCI and AD patients. The motor-sensory cortex was relatively preserved. MMSE scores in the entire study cohort were significantly associated with the degree of perfusion impairment as assessed by pAV-45 imaging (r = 0.5156, P < 0.0001). {sup 18}F-AV-45 uptake was significantly higher in AD patients than in the two other study groups. However, the correlation between MMSE scores and {sup 18}F-AV-45 uptake in MCI patients was more of a binary phenomenon and began in MCI patients with MMSE score 23.14 when {sup 18}F-AV-45 uptake was higher and MMSE score lower than in patients with early MCI. Amyloid deposition started in the precuneus and the frontal and temporal regions in early MCI, ultimately

Cromolyn Reduces Levels of the Alzheimer's Disease-Associated Amyloid β-Protein by Promoting Microglial Phagocytosis.

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Zhang, Can; Griciuc, Ana; Hudry, Eloise; Wan, Yu; Quinti, Luisa; Ward, Joseph; Forte, Angela M; Shen, Xunuo; Ran, ChongZhao; Elmaleh, David R; Tanzi, Rudolph E

2018-01-18

Amyloid-beta protein (Aβ) deposition is a pathological hallmark of Alzheimer's disease (AD). Aβ deposition triggers both pro-neuroinflammatory microglial activation and neurofibrillary tangle formation. Cromolyn sodium is an asthma therapeutic agent previously shown to reduce Aβ levels in transgenic AD mouse brains after one-week of treatment. Here, we further explored these effects as well as the mechanism of action of cromolyn, alone, and in combination with ibuprofen in APP Swedish -expressing Tg2576 mice. Mice were treated for 3 months starting at 5 months of age, when the earliest stages of β-amyloid deposition begin. Cromolyn, alone, or in combination with ibuprofen, almost completely abolished longer insoluble Aβ species, i.e. Aβ40 and Aβ42, but increased insoluble Aβ38 levels. In addition to its anti-aggregation effects on Aβ, cromolyn, alone, or plus ibuprofen, but not ibuprofen alone, increased microglial recruitment to, and phagocytosis of β-amyloid deposits in AD mice. Cromolyn also promoted Aβ42 uptake in microglial cell-based assays. Collectively, our data reveal robust effects of cromolyn, alone, or in combination with ibuprofen, in reducing aggregation-prone Aβ levels and inducing a neuroprotective microglial activation state favoring Aβ phagocytosis versus a pro-neuroinflammatory state. These findings support the use of cromolyn, alone, or with ibuprofen, as a potential AD therapeutic.

Blood-brain barrier dysfunction and amyloid precursor protein accumulation in microvascular compartment following ischemia-reperfusion brain injury with 1-year survival.

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Pluta, R

2003-01-01

This study examined the late microvascular consequences of brain ischemia due to cardiac arrest in rats. In reacted vibratome sections scattered foci of extravasated horseradish peroxidase were noted throughout the brain and did not appear to be restricted to any specific area of brain. Ultrastructural investigation of leaky sites frequently presented platelets adhering to the endothelium of venules and capillaries. Endothelial cells demonstrated pathological changes with evidence of perivascular astrocytic swelling. At the same time, we noted C-terminal of amyloid precursor protein/beta-amyloid peptide (CAPP/betaA) deposits in cerebral blood vessels, with a halo of CAPP/betaA immunoreactivity in the surrounding parenchyma suggested diffusion of CAPP/betaA out of the vascular compartment. Changes predominated in the hippocampus, cerebral and entorhinal cortex, corpus callosum, thalamus, basal ganglia and around the lateral ventricles. These data implicate delayed abnormal endothelial function of vessels following ischemia-reperfusion brain injury as a primary event in the pathogenesis of the recurrent cerebral infarction.

Lowering beta-amyloid levels rescues learning and memory in a Down syndrome mouse model.

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William J Netzer

Full Text Available beta-amyloid levels are elevated in Down syndrome (DS patients throughout life and are believed to cause Alzheimer's disease (AD in adult members of this population. However, it is not known if beta-amyloid contributes to intellectual disability in younger individuals. We used a gamma-secretase inhibitor to lower beta-amyloid levels in young mice that model DS. This treatment corrected learning deficits characteristic of these mice, suggesting that beta-amyloid-lowering therapies might improve cognitive function in young DS patients.

Amyloid beta precursor protein regulates male sexual behavior.

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Park, Jin Ho; Bonthius, Paul J; Tsai, Houng-Wei; Bekiranov, Stefan; Rissman, Emilie F

2010-07-28

Sexual behavior is variable between individuals, ranging from celibacy to sexual addictions. Within normal populations of individual men, ranging from young to middle aged, testosterone levels do not correlate with libido. To study the genetic mechanisms that contribute to individual differences in male sexual behavior, we used hybrid B6D2F1 male mice, which are a cross between two common inbred strains (C57BL/6J and DBA/2J). Unlike most laboratory rodent species in which male sexual behavior is highly dependent upon gonadal steroids, sexual behavior in a large proportion of these hybrid male mice after castration is independent of gonadal steroid hormones and their receptors; thus, we have the ability to discover novel genes involved in this behavior. Gene expression arrays, validation of gene candidates, and transgenic mice that overexpress one of the genes of interest were used to reveal genes involved in maintenance of male sexual behavior. Several genes related to neuroprotection and neurodegeneration were differentially expressed in the hypothalamus of males that continued to mate after castration. Male mice overexpressing the human form of one of these candidate genes, amyloid beta precursor protein (APP), displayed enhanced sexual behavior before castration and maintained sexual activity for a longer duration after castration compared with controls. Our results reveal a novel and unexpected relationship between APP and male sexual behavior. We speculate that declining APP during normal aging in males may contribute to the loss of sexual function.

PB1-F2 influenza A virus protein adopts a beta-sheet conformation and forms amyloid fibers in membrane environments.

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Chevalier, Christophe; Al Bazzal, Ali; Vidic, Jasmina; Février, Vincent; Bourdieu, Christiane; Bouguyon, Edwige; Le Goffic, Ronan; Vautherot, Jean-François; Bernard, Julie; Moudjou, Mohammed; Noinville, Sylvie; Chich, Jean-François; Da Costa, Bruno; Rezaei, Human; Delmas, Bernard

2010-04-23

The influenza A virus PB1-F2 protein, encoded by an alternative reading frame in the PB1 polymerase gene, displays a high sequence polymorphism and is reported to contribute to viral pathogenesis in a sequence-specific manner. To gain insights into the functions of PB1-F2, the molecular structure of several PB1-F2 variants produced in Escherichia coli was investigated in different environments. Circular dichroism spectroscopy shows that all variants have a random coil secondary structure in aqueous solution. When incubated in trifluoroethanol polar solvent, all PB1-F2 variants adopt an alpha-helix-rich structure, whereas incubated in acetonitrile, a solvent of medium polarity mimicking the membrane environment, they display beta-sheet secondary structures. Incubated with asolectin liposomes and SDS micelles, PB1-F2 variants also acquire a beta-sheet structure. Dynamic light scattering revealed that the presence of beta-sheets is correlated with an oligomerization/aggregation of PB1-F2. Electron microscopy showed that PB1-F2 forms amorphous aggregates in acetonitrile. In contrast, at low concentrations of SDS, PB1-F2 variants exhibited various abilities to form fibers that were evidenced as amyloid fibers in a thioflavin T assay. Using a recombinant virus and its PB1-F2 knock-out mutant, we show that PB1-F2 also forms amyloid structures in infected cells. Functional membrane permeabilization assays revealed that the PB1-F2 variants can perforate membranes at nanomolar concentrations but with activities found to be sequence-dependent and not obviously correlated with their differential ability to form amyloid fibers. All of these observations suggest that PB1-F2 could be involved in physiological processes through different pathways, permeabilization of cellular membranes, and amyloid fiber formation.

Lithium chloride increases the production of amyloid-beta peptide independently from its inhibition of glycogen synthase kinase 3.

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Feyt, Christine; Kienlen-Campard, Pascal; Leroy, Karelle; N'Kuli, Francisca; Courtoy, Pierre J; Brion, Jean-Pierre; Octave, Jean-Noël

2005-09-30

Glycogen synthase kinase 3 (GSK3) is able to phosphorylate tau at many sites that are found to be phosphorylated in paired helical filaments in Alzheimer disease. Lithium chloride (LiCl) efficiently inhibits GSK3 and was recently reported to also decrease the production of amyloid-beta peptide (Abeta) from its precursor, the amyloid precursor protein. Therefore, lithium has been proposed as a combined therapeutic agent, inhibiting both the hyperphosphorylation of tau and the production of Abeta. Here, we demonstrate that the inhibition of GSK3 by LiCl induced the nuclear translocation of beta-catenin in Chinese hamster ovary cells and rat cultured neurons, in which a decrease in tau phosphorylation was observed. In both cellular models, a nontoxic concentration of LiCl increased the production of Abeta by increasing the beta-cleavage of amyloid precursor protein, generating more substrate for an unmodified gamma-secretase activity. SB415286, another GSK3 inhibitor, induced the nuclear translocation of beta-catenin and slightly decreased Abeta production. It is concluded that the LiCl-mediated increase in Abeta production is not related to GSK3 inhibition.

Neuroinflammation and common mechanism in Alzheimer's disease and prion amyloidosis: amyloid-associated proteins, neuroinflammation and neurofibrillary degeneration

NARCIS (Netherlands)

Rozemuller, A.J.M.; Jansen, C.; Carrano, A.; van Haastert, E.S.; Hondius, D.; van der Vies, S.M.; Hoozemans, J.J.M.

2012-01-01

Background: In cases with a long (>1 year) clinical duration of prion disease, the prion protein can form amyloid deposits. These cases do not show accumulation of 4-kDa β-amyloid, which is observed in amyloid deposits in Alzheimer's disease (AD). In AD, amyloid is associated with inflammation and

CD147 is a regulatory subunit of the gamma-secretase complex inAlzheimer's disease amyloid beta-peptide production

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Zhou, Shuxia; Zhou, Hua; Walian, Peter J.; Jap, Bing K.

2005-04-06

{gamma}-secretase is a membrane protein complex that cleaves the {beta}-amyloid precursor protein (APP) within the transmembrane region, following prior processing by {beta}-secretase, producing amyloid {beta}-peptides (A{beta}{sub 40} and A{beta}{sub 42}). Errant production of A{beta}-peptides that substantially increases A{beta}{sub 42} production has been associated with the formation of amyloid plaques in Alzheimer's disease patients. Biophysical and genetic studies indicate that presenilin-1 (Psn-1), which contains the proteolytic active site, and three other membrane proteins, nicastrin (Nct), APH-1, and PEN-2 are required to form the core of the active {gamma}-secretase complex. Here, we report the purification of the native {gamma}-secretase complexes from HeLa cell membranes and the identification of an additional {gamma}-secretase complex subunit, CD147, a transmembrane glycoprotein with two immunoglobulin-like domains. The presence of this subunit as an integral part of the complex itself was confirmed through co-immunoprecipitation studies of the purified protein from HeLa cells and solubilized complexes from other cell lines such as neural cell HCN-1A and HEK293. Depletion of CD147 by RNA interference was found to increase the production of A{beta} peptides without changing the expression level of the other {gamma}-secretase components or APP substrates while CD147 overexpression had no statistically significant effect on amyloid {beta}-peptide production, other {gamma}-secretase components or APP substrates, indicating that the presence of the CD147 subunit within the {gamma}-secretase complex directly down-modulates the production of A{beta}-peptides. {gamma}-secretase was first recognized through its role in the production of the A{beta} peptides that are pathogenic in Alzheimer's disease (AD) (1). {gamma}-secretase is a membrane protein complex with unusual aspartyl protease activity that cleaves a variety of type I membrane proteins

Conformational changes of the amyloid beta-peptide (1-40) adsorbed on solid surfaces

NARCIS (Netherlands)

Giacomelli, CE; Norde, W

2005-01-01

The conformational change of the 39-43 residues of the amyloid beta-peptide (A beta) toward a beta-sheet enriched state promotes self-aggregation of the peptide molecules and constitutes the major peptide component of the amyloid plaques in Alzheimer patients. The crucial question behind the

Conformational changes of the amyloid beta-peptide (1-40) adsorbed on solid surfaces

NARCIS (Netherlands)

Giacomelli, C.E.; Norde, W.

2005-01-01

The conformational change of the 39-43 residues of the amyloid beta -peptide (A beta) toward a beta -sheet enriched state promotes self-aggregation of the peptide molecules and constitutes the major peptide component of the amyloid plaques in Alzheimer patients. The crucial question behind the

Beta-amyloid and cholinergic neurons

Czech Academy of Sciences Publication Activity Database

Doležal, Vladimír; Kašparová, Jana

2003-01-01

Roč. 28, 3-4 (2003), s. 499-506 ISSN 0364-3190 R&D Projects: GA ČR GA305/01/0283; GA AV ČR IAA5011206 Institutional research plan: CEZ:AV0Z5011922 Keywords : cholinergic neurons * AlzheimerŽs disease * beta-amyloid Subject RIV: FH - Neurology Impact factor: 1.511, year: 2003

[Effects of grain-sized moxibustion on learning and memory ability and amyloid deposition of transgenic Alzheimer's disease mice].

Science.gov (United States)

Yu, Jing; Chu, Jia-Mei; Gao, Ling-Ai; Zhang, Yong-Sheng; Bao, Ye-Hua

2014-02-01

To observe the effect of grain-sized moxibustion at "Xinshu" (BL 15) and "Shenshu" (BL 23) on memory-learning ability and amyloid deposition in transgenic Alzheimer's disease (AD) mice. seventeen amyloid precursor protein (APP)/presenilin (PS)1 (APP+/PS 1+) double transgenic 6799 mice aged 3-4 weeks were randomly divided into model group (n = 9) and moxibustion group (n = 8). Nine wide-type (C 57 BL/6 J) female mice were used as the normal control group. Moxibustion (ignited grain-sized moxa cone) was applied to bilateral "Xinshu" (BL 15) and "Shenshu" (BL 23) for about 30 s, once a day for 9 courses (10 days constitute a therapeutic course, with 2 days' break between every two courses). Morris water maze tests were performed to detect the mice's learning-memory ability. The alterations of beta-amyloid deposition (number of the positive plaques) in the cerebral cortex and hippocampus were detected by using an imaging analysis system following Congo red staining of the cerebral tissue sections. Compared with the normal group, the average escape latency of place navigation tests was significantly increased (P memory ability after moxibustion. Results of Congo red staining of the cerebral tissue showed that there were many irregular, uneven staining positive plaques in the cerebral cortex and hippocampus of AD mice in the model group. Compared with the model group, the positive plaque numbers in both cerebral cortex and hippocampus were considerably reduced in the moxibustion group (P memory ability and restrain the formation of amyloid deposition in AD mice.

Protein folding pathology in domestic animals.

Science.gov (United States)

Gruys, Erik

2004-10-01

Fibrillar proteins form structural elements of cells and the extracellular matrix. Pathological lesions of fibrillar microanatomical structures, or secondary fibrillar changes in globular proteins are well known. A special group concerns histologically amorphous deposits, amyloid. The major characteristics of amyloid are: apple green birefringence after Congo red staining of histological sections, and non-branching 7-10 nm thick fibrils on electron microscopy revealing a high content of cross beta pleated sheets. About 25 different types of amyloid have been characterised. In animals, AA-amyloid is the most frequent type. Other types of amyloid in animals represent: AIAPP (in cats), AApoAI, AApoAII, localised AL-amyloid, amyloid in odontogenic or mammary tumors and amyloid in the brain. In old dogs Abeta and in sheep APrPsc-amyloid can be encountered. AA-amyloidosis is a systemic disorder with a precursor in blood, acute phase serum amyloid A (SAA). In chronic inflammatory processes AA-amyloid can be deposited. A rapid crystallization of SAA to amyloid fibrils on small beta-sheeted fragments, the 'amyloid enhancing factor' (AEF), is known and the AEF has been shown to penetrate the enteric barrier. Amyloid fibrils can aggregate from various precursor proteins in vitro in particular at acidic pH and when proteolytic fragments are formed. Molecular chaperones influence this process. Tissue data point to amyloid fibrillogenesis in lysosomes and near cell surfaces. A comparison can be made of the fibrillogenesis in prion diseases and in enhanced AA-amyloidosis. In the reactive form, acute phase SAA is the supply of the precursor protein, whereas in the prion diseases, cell membrane proteins form a structural source. Abeta-amyloid in brain tissue of aged dogs showing signs of dementia forms a canine counterpart of senile dementia of the Alzheimer type (ccSDAT) in man. Misfolded proteins remain potential food hazards. Developments concerning prevention of amyloidogenesis

Chaperones ameliorate beta cell dysfunction associated with human islet amyloid polypeptide overexpression.

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Lisa Cadavez

Full Text Available In type 2 diabetes, beta-cell dysfunction is thought to be due to several causes, one being the formation of toxic protein aggregates called islet amyloid, formed by accumulations of misfolded human islet amyloid polypeptide (hIAPP. The process of hIAPP misfolding and aggregation is one of the factors that may activate the unfolded protein response (UPR, perturbing endoplasmic reticulum (ER homeostasis. Molecular chaperones have been described to be important in regulating ER response to ER stress. In the present work, we evaluate the role of chaperones in a stressed cellular model of hIAPP overexpression. A rat pancreatic beta-cell line expressing hIAPP exposed to thapsigargin or treated with high glucose and palmitic acid, both of which are known ER stress inducers, showed an increase in ER stress genes when compared to INS1E cells expressing rat IAPP or INS1E control cells. Treatment with molecular chaperone glucose-regulated protein 78 kDa (GRP78, also known as BiP or protein disulfite isomerase (PDI, and chemical chaperones taurine-conjugated ursodeoxycholic acid (TUDCA or 4-phenylbutyrate (PBA, alleviated ER stress and increased insulin secretion in hIAPP-expressing cells. Our results suggest that the overexpression of hIAPP induces a stronger response of ER stress markers. Moreover, endogenous and chemical chaperones are able to ameliorate induced ER stress and increase insulin secretion, suggesting that improving chaperone capacity can play an important role in improving beta-cell function in type 2 diabetes.

Calcium binding to beta-2-microglobulin at physiological pH drives the occurrence of conformational changes which cause the protein to precipitate into amorphous forms that subsequently transform into amyloid aggregates.

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Sukhdeep Kumar

Full Text Available Using spectroscopic, calorimetric and microscopic methods, we demonstrate that calcium binds to beta-2-microglobulin (β2m under physiological conditions of pH and ionic strength, in biological buffers, causing a conformational change associated with the binding of up to four calcium atoms per β2m molecule, with a marked transformation of some random coil structure into beta sheet structure, and culminating in the aggregation of the protein at physiological (serum concentrations of calcium and β2m. We draw attention to the fact that the sequence of β2m contains several potential calcium-binding motifs of the DXD and DXDXD (or DXEXD varieties. We establish (a that the microscopic aggregation seen at physiological concentrations of β2m and calcium turns into actual turbidity and visible precipitation at higher concentrations of protein and β2m, (b that this initial aggregation/precipitation leads to the formation of amorphous aggregates, (c that the formation of the amorphous aggregates can be partially reversed through the addition of the divalent ion chelating agent, EDTA, and (d that upon incubation for a few weeks, the amorphous aggregates appear to support the formation of amyloid aggregates that bind to the dye, thioflavin T (ThT, resulting in increase in the dye's fluorescence. We speculate that β2m exists in the form of microscopic aggregates in vivo and that these don't progress to form larger amyloid aggregates because protein concentrations remain low under normal conditions of kidney function and β2m degradation. However, when kidney function is compromised and especially when dialysis is performed, β2m concentrations probably transiently rise to yield large aggregates that deposit in bone joints and transform into amyloids during dialysis related amyloidosis.

Whole body amyloid deposition imaging by 123I-SAP scintigraphy

NARCIS (Netherlands)

van Rheenen, Ronald; Glaudemans, Andor; Hazenberg, Bouke

2011-01-01

Amyloidosis is the name of a group of diseases characterized by extracellular deposition of amyloid fibrils. Deposition of amyloid can be localized or systemic. The 123I-SAP-scan can be used to image extent and distribution of amyloid deposition in patients with systemic AA, AL and ATTR amyloidosis.

Development and characterization of a TAPIR-like mouse monoclonal antibody to amyloid-beta.

Science.gov (United States)

Wang, Jun; Hara, Hideo; Makifuchi, Takao; Tabira, Takeshi

2008-06-01

Tissue amyloid plaque immuno-reactive (TAPIR) antibody was better related to the effect of immunotherapy in Alzheimer's disease (AD) than ELISA antibody. Here we used a hybridoma technique to develop a TAPIR-like anti-human amyloid-beta (Abeta) mouse monoclonal antibody. The obtained monoclonal antibody, 3.4A10, was an IgG2b isotype and recognized N-terminal portion of Abeta1-42 without binding denatured or native amyloid-beta protein precursor. It had higher affinity to Abeta1-42 than to Abeta1-40 by Biacore affinity analysis and stained preferably the peripheral part of senile plaques and recognized the plaque core less than 4G8. It inhibited the Abeta1-42 fibril formation as well as degraded pre-aggregated Abeta1-42 peptide in a thioflavin T fluorescence spectrophotometry assay. The in vivo studies showed that 3.4A10 treatment decreased amyloid burden compared to the control group and significantly reduced Abeta42 levels rather than Abeta40 levels in brain lysates as well as the Abeta*56 oligomer (12mer) in TBS fraction of the brain lysates. 3.4A10 entered brain and decorated some plaques, which is surrounded by more Iba1-positive microglia. 3.4A10 therapy did not induce lymphocytic infiltration and obvious increase in microhemorrhage. We conclude that 3.4A10 is a TAPIR-like anti-human amyloid monoclonal antibody, and has a potential of therapeutic application for AD.

Towards a Pharmacophore for Amyloid

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Landau, Meytal; Sawaya, Michael R.; Faull, Kym F.; Laganowsky, Arthur; Jiang, Lin; Sievers, Stuart A.; Liu, Jie; Barrio, Jorge R.; Eisenberg, David (UCLA)

2011-09-16

Diagnosing and treating Alzheimer's and other diseases associated with amyloid fibers remains a great challenge despite intensive research. To aid in this effort, we present atomic structures of fiber-forming segments of proteins involved in Alzheimer's disease in complex with small molecule binders, determined by X-ray microcrystallography. The fiber-like complexes consist of pairs of {beta}-sheets, with small molecules binding between the sheets, roughly parallel to the fiber axis. The structures suggest that apolar molecules drift along the fiber, consistent with the observation of nonspecific binding to a variety of amyloid proteins. In contrast, negatively charged orange-G binds specifically to lysine side chains of adjacent sheets. These structures provide molecular frameworks for the design of diagnostics and drugs for protein aggregation diseases. The devastating and incurable dementia known as Alzheimer's disease affects the thinking, memory, and behavior of dozens of millions of people worldwide. Although amyloid fibers and oligomers of two proteins, tau and amyloid-{beta}, have been identified in association with this disease, the development of diagnostics and therapeutics has proceeded to date in a near vacuum of information about their structures. Here we report the first atomic structures of small molecules bound to amyloid. These are of the dye orange-G, the natural compound curcumin, and the Alzheimer's diagnostic compound DDNP bound to amyloid-like segments of tau and amyloid-{beta}. The structures reveal the molecular framework of small-molecule binding, within cylindrical cavities running along the {beta}-spines of the fibers. Negatively charged orange-G wedges into a specific binding site between two sheets of the fiber, combining apolar binding with electrostatic interactions, whereas uncharged compounds slide along the cavity. We observed that different amyloid polymorphs bind different small molecules, revealing that a

[Noopept improves the spatial memory and stimulates prefibrillar beta-amyloid(25-35) antibody production in mice].

Science.gov (United States)

Bobkova, N V; Gruden', M A; Samokhin, A N; Medvinskaia, N I; Morozova-Roch, L; Uudasheva, T A; Ostrovskaia, R U; Seredinin, S B

2005-01-01

The effects of the novel proline-containing nootropic and neuroprotective dipeptide noopept (GVS-111, N-phenylacetyl-L-prolylglycine ethyl ester) were studied on NMRI mice upon olfactory bulbectomy, which had been previously shown to imitate the main morphological and biochemical signs of Alzheimer's disease (AD). The spatial memory was assessed using the Morris (water maze) test; the immunological status was characterized by ELISA with antibodies to prefibrillar beta-amyloid(25-35), S100b protein, and protofilaments of equine lysozyme, which are the molecular factors involved in the pathogenesis of AD. The control (sham-operated) animals during the Morris test preferred a sector where the safety platform was placed during the learning session. Bulbectomized animals treated with saline failed to recognize this sector, while bulbectomized animals treated with noopept (0.01 mg/kg for 21 days) restored this predominance, thus demonstrating the improvement of the spatial memory. These animals also demonstrated an increase in the level of antibodies to beta-amyloid(25-35)--the effect, which was more pronounced in the sham-operated than in bulbectomized mice. The latter demonstrated a profound decrease of immunological reactivity in a large number of tests. Noopept, stimulating the production of antibodies to beta-amyloid(25-35), can attenuate the well-known neurotoxic effects of beta-amyloid. The obtained data on the mnemotropic and immunostimulant effects noopept are indicative of good prospects for the clinical usage of this drug in the therapy of patients with neurodegenerative diseases.

X11beta rescues memory and long-term potentiation deficits in Alzheimer's disease APPswe Tg2576 mice.

LENUS (Irish Health Repository)

Mitchell, Jacqueline C

2009-12-01

Increased production and deposition of amyloid beta-protein (Abeta) are believed to be key pathogenic events in Alzheimer\\'s disease. As such, routes for lowering cerebral Abeta levels represent potential therapeutic targets for Alzheimer\\'s disease. X11beta is a neuronal adaptor protein that binds to the intracellular domain of the amyloid precursor protein (APP). Overexpression of X11beta inhibits Abeta production in a number of experimental systems. However, whether these changes to APP processing and Abeta production induced by X11beta overexpression also induce beneficial effects to memory and synaptic plasticity are not known. We report here that X11beta-mediated reduction in cerebral Abeta is associated with normalization of both cognition and in vivo long-term potentiation in aged APPswe Tg2576 transgenic mice that model the amyloid pathology of Alzheimer\\'s disease. Overexpression of X11beta itself has no detectable adverse effects upon mouse behaviour. These findings support the notion that modulation of X11beta function represents a therapeutic target for Abeta-mediated neuronal dysfunction in Alzheimer\\'s disease.

Two distinct β-sheet structures in Italian-mutant amyloid-beta fibrils : a potential link to different clinical phenotypes

NARCIS (Netherlands)

Hubin, Ellen; Deroo, Stéphanie; Schierle, Gabriele Kaminksi; Kaminski, Clemens; Serpell, Louise; Subramaniam, Vinod; van Nuland, Nico; Broersen, Kerensa; Raussens, Vincent; Sarroukh, Rabia

2015-01-01

Most Alzheimer's disease (AD) cases are late-onset and characterized by the aggregation and deposition of the amyloid-beta (Aβ) peptide in extracellular plaques in the brain. However, a few rare and hereditary Aβ mutations, such as the Italian Glu22-to-Lys (E22K) mutation, guarantee the development

Characterization of the beta amyloid precursor protein-like gene in the central nervous system of the crab Chasmagnathus. Expression during memory consolidation.

Science.gov (United States)

Fustiñana, Maria Sol; Ariel, Pablo; Federman, Noel; Freudenthal, Ramiro; Romano, Arturo

2010-09-01

Human β-amyloid, the main component in the neuritic plaques found in patients with Alzheimer's disease, is generated by cleavage of the β-amyloid precursor protein. Beyond the role in pathology, members of this protein family are synaptic proteins and have been associated with synaptogenesis, neuronal plasticity and memory, both in vertebrates and in invertebrates. Consolidation is necessary to convert a short-term labile memory to a long-term and stable form. During consolidation, gene expression and de novo protein synthesis are regulated in order to produce key proteins for the maintenance of plastic changes produced during the acquisition of new information. Here we partially cloned and sequenced the beta-amyloid precursor protein like gene homologue in the crab Chasmagnathus (cappl), showing a 37% of identity with the fruit fly Drosophila melanogaster homologue and 23% with Homo sapiens but with much higher degree of sequence similarity in certain regions. We observed a wide distribution of cappl mRNA in the nervous system as well as in muscle and gills. The protein localized in all tissues analyzed with the exception of muscle. Immunofluorescence revealed localization of cAPPL in associative and sensory brain areas. We studied gene and protein expression during long-term memory consolidation using a well characterized memory model: the context-signal associative memory in this crab species. mRNA levels varied at different time points during long-term memory consolidation and correlated with cAPPL protein levels cAPPL mRNA and protein is widely distributed in the central nervous system of the crab and the time course of expression suggests a role of cAPPL during long-term memory formation.

Beta-amyloid deposition in patients with major depressive disorder with differing levels of treatment resistance: a pilot study.

Science.gov (United States)

Li, Peng; Hsiao, Ing-Tsung; Liu, Chia-Yih; Chen, Chia-Hsiang; Huang, She-Yao; Yen, Tzu-Chen; Wu, Kuan-Yi; Lin, Kun-Ju

2017-12-01

Lack of treatment response in patients with late-life depression is common. The role of brain beta-amyloid (Aβ) deposition in treatment outcome in subjects with late-life depression remains unclear. The present study aimed to investigate brain Aβ deposition in patients with major depressive disorder (MDD) with differing treatment outcomes in vivo using 18 F-florbetapir imaging. This study included 62 MDD patients and 18 healthy control subjects (HCs).We first employed the Maudsley staging method (MSM) to categorize MDD patients into two groups according to treatment response: mild treatment resistance (n = 29) and moderate-to-severe treatment resistance (n = 33).The standard uptake value ratio (SUVR) of each volume of interest was analysed, and voxel-wise comparisons were made between the MDD patients and HCs. Vascular risk factors, serum homocysteine level, and apolipoprotein E (ApoE) genotype were also determined. The MDD patients with moderate-to-severe treatment resistance had higher 18 F-florbetapir SUVRs than the HCs in the parietal region (P depressive symptoms may represent prodromal manifestations of Alzheimer's disease (AD). Depressive symptomatology in old age, particularly in subjects with a poor treatment response, may underscore early changes of AD-related pathophysiology.

Stereoselective determination of amino acids in beta-amyloid peptides and senile plaques.

Science.gov (United States)

Thorsén, G; Bergquist, J; Westlind-Danielsson, A; Josefsson, B

2001-06-01

A novel method for the determination of the enantiomeric composition of peptides is presented. In this paper, the focus has been on beta-amyloid peptides from deceased Alzheimer's disease patients. The peptides are hydrolyzed using mineral acid. The free amino acids are derivatized with the chiral reagent (+)- or (-)-1-(9-anthryl)-2-propyl chloroformate and subsequently separated using micellar electrokinetic chromatography (MEKC) and detected using laser-induced fluorescence (LIF) detection. The high separation efficiency of the MEKC-LIF system, yielding approximately 1 million theoretical plates/m for most amino acids, facilitates the simultaneous chiral determination of nine amino acids. The samples that have been analyzed were standard 1-40 beta-amyloid peptides, in vitro precipitated beta-amyloid fibrils, and human senile plaque samples.

APP processing and the APP-KPI domain involvement in the amyloid cascade.

Science.gov (United States)

Menéndez-González, M; Pérez-Pinera, P; Martínez-Rivera, M; Calatayud, M T; Blázquez Menes, B

2005-01-01

Alternative APP mRNA splicing can generate isoforms of APP containing a Kunitz protease inhibitor (KPI) domain. KPI is one of the main serine protease inhibitors. Protein and mRNA KPI(+)APP levels are elevated in Alzheimer's disease (AD) brain and are associated with increased amyloid beta deposition. In the last years increasing evidence on multiple points in the amyloid cascade where KPI(+)APP is involved has been accumulated, admitting an outstanding position in the pathogenesis of AD to the KPI domain. This review focuses on the APP processing, the molecular activity of KPI and its physiological and pathological roles and the KPI involvement in the amyloid cascade through the nerve growth factor, the lipoprotein receptor-related protein, the tumor necrosis factor-alpha converting enzyme and the Notch1 protein.

Changes of Functional and Directed Resting-State Connectivity Are Associated with Neuronal Oscillations, ApoE Genotype and Amyloid Deposition in Mild Cognitive Impairment

Directory of Open Access Journals (Sweden)

Lars Michels

2017-09-01

Full Text Available The assessment of effects associated with cognitive impairment using electroencephalography (EEG power mapping allows the visualization of frequency-band specific local changes in oscillatory activity. In contrast, measures of coherence and dynamic source synchronization allow for the study of functional and effective connectivity, respectively. Yet, these measures have rarely been assessed in parallel in the context of mild cognitive impairment (MCI and furthermore it has not been examined if they are related to risk factors of Alzheimer’s disease (AD such as amyloid deposition and apolipoprotein ε4 (ApoE allele occurrence. Here, we investigated functional and directed connectivities with Renormalized Partial Directed Coherence (RPDC in 17 healthy controls (HC and 17 participants with MCI. Participants underwent ApoE-genotyping and Pittsburgh compound B positron emission tomography (PiB-PET to assess amyloid deposition. We observed lower spectral source power in MCI in the alpha and beta bands. Coherence was stronger in HC than MCI across different neuronal sources in the delta, theta, alpha, beta and gamma bands. The directed coherence analysis indicated lower information flow between fronto-temporal (including the hippocampus sources and unidirectional connectivity in MCI. In MCI, alpha and beta RPDC showed an inverse correlation to age and gender; global amyloid deposition was inversely correlated to alpha coherence, RPDC and beta and gamma coherence. Furthermore, the ApoE status was negatively correlated to alpha coherence and RPDC, beta RPDC and gamma coherence. A classification analysis of cognitive state revealed the highest accuracy using EEG power, coherence and RPDC as input. For this small but statistically robust (Bayesian power analyses sample, our results suggest that resting EEG related functional and directed connectivities are sensitive to the cognitive state and are linked to ApoE and amyloid burden.

PEGylated nanoparticles bind to and alter amyloid-beta peptide conformation

DEFF Research Database (Denmark)

Brambilla, Davide; Verpillot, Romain; Le Droumaguet, Benjamin

2012-01-01

We have demonstrated that the polyethylene glycol (PEG) corona of long-circulating polymeric nanoparticles (NPs) favors interaction with the amyloid-beta (Aß(1-42)) peptide both in solution and in serum. The influence of PEGylation of poly(alkyl cyanoacrylate) and poly(lactic acid) NPs on the int......We have demonstrated that the polyethylene glycol (PEG) corona of long-circulating polymeric nanoparticles (NPs) favors interaction with the amyloid-beta (Aß(1-42)) peptide both in solution and in serum. The influence of PEGylation of poly(alkyl cyanoacrylate) and poly(lactic acid) NPs...

How ionic strength affects the conformational behavior of human and rat beta amyloids--a computational study.

Directory of Open Access Journals (Sweden)

Zdeněk Kříž

Full Text Available Progressive cerebral deposition of amyloid beta occurs in Alzheimers disease and during the aging of certain mammals (human, monkey, dog, bear, cow, cat but not others (rat, mouse. It is possibly due to different amino acid sequences at positions 5, 10 and 13. To address this issue, we performed series of 100 ns long trajectories (each trajectory was run twice with different initial velocity distribution on amyloid beta (1-42 with the human and rat amino acid sequence in three different environments: water with only counter ions, water with NaCl at a concentration of 0.15 M as a model of intracellular Na(+ concentration at steady state, and water with NaCl at a concentration of 0.30 M as a model of intracellular Na(+ concentration under stimulated conditions. We analyzed secondary structure stability, internal hydrogen bonds, and residual fluctuation. It was observed that the change in ionic strength affects the stability of internal hydrogen bonds. Increasing the ionic strength increases atomic fluctuation in the hydrophobic core of the human amyloid, and decreases the atomic fluctuation in the case of rat amyloid. The secondary structure analyses show a stable α-helix part between residues 10 and 20. However, C-terminus of investigated amyloids is much more flexible showing no stable secondary structure elements. Increasing ionic strength of the solvent leads to decreasing stability of the secondary structural elements. The difference in conformational behavior of the three amino acids at position 5, 10 and 13 for human and rat amyloids significantly changes the conformational behavior of the whole peptide.

Anti-amyloid treatments in Alzheimer's disease.

Science.gov (United States)

Sapra, Mamta; Kim, Kye Y

2009-06-01

Alzheimer's disease is one of the most challenging threats to the healthcare system in society. One of the main characteristic of Alzheimer's disease (AD) pathology is formation of amyloid plaques from accumulation of amyloid beta peptide. The therapeutic agents that are currently available for AD including acetylcholinesterase inhibitors (AchEIs) and the N-methyl-D-aspartate (NMDA) antagonist are focused on improving the symptoms and do not revert the progression of the disease. This limitation coupled with the burgeoning increase in the prevalence of AD and resultant impact on healthcare economics calls for more substantial treatments for AD. According to the leading amyloid hypothesis, cleavage of amyloid precursor protein to release amyloid beta peptide is the critical event in pathogenesis of Alzheimer's disease. Recently treatment strategies have been focused on modifying the formation, clearance and accumulation of neurotoxic amyloid beta peptide. This article reviews different therapeutic approaches that have been investigated to target amyloid beta ranging from secretase modulators, antiaggregation agents to amyloid immunotherapy. Authors review the different novel drugs which are in clinical trials.

The role of beta amyloid in Alzheimer's disease: still a cause of everything or the only one who got caught?

Science.gov (United States)

Verdile, Giuseppe; Fuller, Stephanie; Atwood, Craig S; Laws, Simon M; Gandy, Samuel E; Martins, Ralph N

2004-10-01

The beta amyloid (A beta) protein is a key molecule in the pathogenesis of Alzheimer's disease (AD). The tendency of the A beta peptide to aggregate, its reported neurotoxicity, and genetic linkage studies, have led to a hypothesis of AD pathogenesis that many AD researchers term the amyloid cascade hypothesis. In this hypothesis, an increased production of A beta results in neurodegeneration and ultimately dementia through a cascade of events. In the past 15 years, debate amongst AD researchers has arisen as to whether A beta is a cause or an effect of the pathogenic process. Recent in vitro and in vivo research has consolidated the theory that A beta is the primary cause, initiating secondary events, culminating in the neuropathological hallmarks associated with AD. This research has led to the development of therapeutic agents, currently in human clinical trials, which target A beta.

[Development of anti-Alzheimer's disease drug based on beta-amyloid hypothesis].

Science.gov (United States)

Sugimoto, Hachiro

2010-04-01

Currently, there are five anti-Alzheimer's disease drugs approved. These are tacrine, donepezil, rivastigmine, galantamine, and memantine. The mechanism of the first four drugs is acetylcholinesterase inhibition, while memantine is an NMDA-receptor antagonist. However, these drugs do not cure Alzheimer's, but are only symptomatic treatments. Therefore, a cure for Alzheimer's disease is truly needed. Alzheimer's disease is a progressive neurodegenerative disease characterized by cognitive deficits. The cause of the disease is not well understood, but research indicates that the aggregation of beta-amyloid is the fundamental cause. This theory suggests that beta-amyloid aggregation causes neurotoxicity. Therefore, development of the next anti-Alzheimer's disease drug is based on the beta-amyloid theory. We are now studying natural products, such as mulberry leaf extracts and curcumin derivatives, as potential cure for Alzheimer's disease. In this report, we describe some data about these natural products and derivatives.

The proteome response to amyloid protein expression in vivo.

Directory of Open Access Journals (Sweden)

Ricardo A Gomes

Full Text Available Protein misfolding disorders such as Alzheimer, Parkinson and transthyretin amyloidosis are characterized by the formation of protein amyloid deposits. Although the nature and location of the aggregated proteins varies between different diseases, they all share similar molecular pathways of protein unfolding, aggregation and amyloid deposition. Most effects of these proteins are likely to occur at the proteome level, a virtually unexplored reality. To investigate the effects of an amyloid protein expression on the cellular proteome, we created a yeast expression system using human transthyretin (TTR as a model amyloidogenic protein. We used Saccharomyces cerevisiae, a living test tube, to express native TTR (non-amyloidogenic and the amyloidogenic TTR variant L55P, the later forming aggregates when expressed in yeast. Differential proteome changes were quantitatively analyzed by 2D-differential in gel electrophoresis (2D-DIGE. We show that the expression of the amyloidogenic TTR-L55P causes a metabolic shift towards energy production, increased superoxide dismutase expression as well as of several molecular chaperones involved in protein refolding. Among these chaperones, members of the HSP70 family and the peptidyl-prolyl-cis-trans isomerase (PPIase were identified. The latter is highly relevant considering that it was previously found to be a TTR interacting partner in the plasma of ATTR patients but not in healthy or asymptomatic subjects. The small ubiquitin-like modifier (SUMO expression is also increased. Our findings suggest that refolding and degradation pathways are activated, causing an increased demand of energetic resources, thus the metabolic shift. Additionally, oxidative stress appears to be a consequence of the amyloidogenic process, posing an enhanced threat to cell survival.

Chronic treatment with amyloid beta(1-42) inhibits non-cholinergic high-affinity choline transport in NG108-15 cells through protein kinase C signaling

Czech Academy of Sciences Publication Activity Database

Nováková, Jana; Mikasová, Lenka; Machová, Eva; Lisá, Věra; Doležal, Vladimír

2005-01-01

Roč. 1062, č. 1-2 (2005), s. 101-110 ISSN 0006-8993 R&D Projects: GA AV ČR(CZ) IAA5011206; GA MŠk(CZ) LC554 Grant - others:Lipidiet(XE) QLK1-CT-2002-00172 Institutional research plan: CEZ:AV0Z50110509 Keywords : choline transporter * beta-amyloid * protein kinase C Subject RIV: ED - Physiology Impact factor: 2.296, year: 2005

Significant association between renal function and area of amyloid deposition in kidney biopsy specimens in both AA amyloidosis associated with rheumatoid arthritis and AL amyloidosis.

Science.gov (United States)

Kuroda, Takeshi; Tanabe, Naohito; Hasegawa, Eriko; Wakamatsu, Ayako; Nozawa, Yukiko; Sato, Hiroe; Nakatsue, Takeshi; Wada, Yoko; Ito, Yumi; Imai, Naofumi; Ueno, Mitsuhiro; Nakano, Masaaki; Narita, Ichiei

2017-06-01

The kidney is a major target organ for systemic amyloidosis, which results in proteinuria and an elevated serum creatinine level. The clinical manifestations and precursor proteins of amyloid A (AA) and light-chain (AL) amyloidosis are different, and the renal damage due to amyloid deposition also seems to differ. The purpose of this study was to clarify haw the difference in clinical features between AA and AL amyloidosis are explained by the difference in the amount and distribution of amyloid deposition in the renal tissues. A total of 119 patients participated: 58 patients with an established diagnosis of AA amyloidosis (AA group) and 61 with AL amyloidosis (AL group). We retrospectively investigated the correlation between clinical data, pathological manifestations, and the area occupied by amyloid in renal biopsy specimens. In most of the renal specimens the percentage area occupied by amyloid was less than 10%. For statistical analyses, the percentage area of amyloid deposition was transformed to a common logarithmic value (Log 10 %amyloid). The results of sex-, age-, and Log 10 %amyloid-adjusted analyses showed that systolic blood pressure (SBP) was higher in the AA group. In terms of renal function parameters, serum creatinine, creatinine clearance (Ccr) and estimated glomerular filtration rate (eGFR) indicated significant renal impairment in the AA group, whereas urinary protein indicated significant renal impairment in the AL group. Pathological examinations revealed amyloid was predominantly deposited at glomerular basement membrane (GBM) and easily transferred to the mesangial area in the AA group, and it was predominantly deposited at in the AL group. The degree of amyloid deposition in the glomerular capillary was significantly more severe in AL group. The frequency of amyloid deposits in extraglomerular mesangium was not significantly different between the two groups, but in AA group, the degree amyloid deposition was significantly more severe, and

Amyloid β-sheet mimics that antagonize protein aggregation and reduce amyloid toxicity

Science.gov (United States)

Cheng, Pin-Nan; Liu, Cong; Zhao, Minglei; Eisenberg, David; Nowick, James S.

2012-11-01

The amyloid protein aggregation associated with diseases such as Alzheimer's, Parkinson's and type II diabetes (among many others) features a bewildering variety of β-sheet-rich structures in transition from native proteins to ordered oligomers and fibres. The variation in the amino-acid sequences of the β-structures presents a challenge to developing a model system of β-sheets for the study of various amyloid aggregates. Here, we introduce a family of robust β-sheet macrocycles that can serve as a platform to display a variety of heptapeptide sequences from different amyloid proteins. We have tailored these amyloid β-sheet mimics (ABSMs) to antagonize the aggregation of various amyloid proteins, thereby reducing the toxicity of amyloid aggregates. We describe the structures and inhibitory properties of ABSMs containing amyloidogenic peptides from the amyloid-β peptide associated with Alzheimer's disease, β2-microglobulin associated with dialysis-related amyloidosis, α-synuclein associated with Parkinson's disease, islet amyloid polypeptide associated with type II diabetes, human and yeast prion proteins, and Tau, which forms neurofibrillary tangles.

Minocycline does not affect amyloid beta phagocytosis by human microglial cells

NARCIS (Netherlands)

Familian, Atoosa; Eikelenboom, Piet; Veerhuis, Robert

2007-01-01

Activated microglia accumulate in amyloid beta (Abeta) plaques containing amyloid associated factors SAP and C1q in Alzheimer's disease (AD) brain. Microglia are involved in AD pathogenesis by promoting Abeta plaque formation and production of pro-inflammatory cytokines. On the other hand,

Characterization of the beta amyloid precursor protein-like gene in the central nervous system of the crab Chasmagnathus. Expression during memory consolidation

Directory of Open Access Journals (Sweden)

Fustiñana Maria

2010-09-01

Full Text Available Abstract Background Human β-amyloid, the main component in the neuritic plaques found in patients with Alzheimer's disease, is generated by cleavage of the β-amyloid precursor protein. Beyond the role in pathology, members of this protein family are synaptic proteins and have been associated with synaptogenesis, neuronal plasticity and memory, both in vertebrates and in invertebrates. Consolidation is necessary to convert a short-term labile memory to a long-term and stable form. During consolidation, gene expression and de novo protein synthesis are regulated in order to produce key proteins for the maintenance of plastic changes produced during the acquisition of new information. Results Here we partially cloned and sequenced the beta-amyloid precursor protein like gene homologue in the crab Chasmagnathus (cappl, showing a 37% of identity with the fruit fly Drosophila melanogaster homologue and 23% with Homo sapiens but with much higher degree of sequence similarity in certain regions. We observed a wide distribution of cappl mRNA in the nervous system as well as in muscle and gills. The protein localized in all tissues analyzed with the exception of muscle. Immunofluorescence revealed localization of cAPPL in associative and sensory brain areas. We studied gene and protein expression during long-term memory consolidation using a well characterized memory model: the context-signal associative memory in this crab species. mRNA levels varied at different time points during long-term memory consolidation and correlated with cAPPL protein levels Conclusions cAPPL mRNA and protein is widely distributed in the central nervous system of the crab and the time course of expression suggests a role of cAPPL during long-term memory formation.

The Golgi-Localized γ-Ear-Containing ARF-Binding (GGA Proteins Alter Amyloid-β Precursor Protein (APP Processing through Interaction of Their GAE Domain with the Beta-Site APP Cleaving Enzyme 1 (BACE1.

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Bjoern von Einem

Full Text Available Proteolytic processing of amyloid-β precursor protein (APP by beta-site APP cleaving enzyme 1 (BACE1 is the initial step in the production of amyloid beta (Aβ, which accumulates in senile plaques in Alzheimer's disease (AD. Essential for this cleavage is the transport and sorting of both proteins through endosomal/Golgi compartments. Golgi-localized γ-ear-containing ARF-binding (GGA proteins have striking cargo-sorting functions in these pathways. Recently, GGA1 and GGA3 were shown to interact with BACE1, to be expressed in neurons, and to be decreased in AD brain, whereas little is known about GGA2. Since GGA1 impacts Aβ generation by confining APP to the Golgi and perinuclear compartments, we tested whether all GGAs modulate BACE1 and APP transport and processing. We observed decreased levels of secreted APP alpha (sAPPα, sAPPβ, and Aβ upon GGA overexpression, which could be reverted by knockdown. GGA-BACE1 co-immunoprecipitation was impaired upon GGA-GAE but not VHS domain deletion. Autoinhibition of the GGA1-VHS domain was irrelevant for BACE1 interaction. Our data suggest that all three GGAs affect APP processing via the GGA-GAE domain.

Alzheimer's disease amyloid-beta links lens and brain pathology in Down syndrome.

Directory of Open Access Journals (Sweden)

Juliet A Moncaster

2010-05-01

Full Text Available Down syndrome (DS, trisomy 21 is the most common chromosomal disorder and the leading genetic cause of intellectual disability in humans. In DS, triplication of chromosome 21 invariably includes the APP gene (21q21 encoding the Alzheimer's disease (AD amyloid precursor protein (APP. Triplication of the APP gene accelerates APP expression leading to cerebral accumulation of APP-derived amyloid-beta peptides (Abeta, early-onset AD neuropathology, and age-dependent cognitive sequelae. The DS phenotype complex also includes distinctive early-onset cerulean cataracts of unknown etiology. Previously, we reported increased Abeta accumulation, co-localizing amyloid pathology, and disease-linked supranuclear cataracts in the ocular lenses of subjects with AD. Here, we investigate the hypothesis that related AD-linked Abeta pathology underlies the distinctive lens phenotype associated with DS. Ophthalmological examinations of DS subjects were correlated with phenotypic, histochemical, and biochemical analyses of lenses obtained from DS, AD, and normal control subjects. Evaluation of DS lenses revealed a characteristic pattern of supranuclear opacification accompanied by accelerated supranuclear Abeta accumulation, co-localizing amyloid pathology, and fiber cell cytoplasmic Abeta aggregates (approximately 5 to 50 nm identical to the lens pathology identified in AD. Peptide sequencing, immunoblot analysis, and ELISA confirmed the identity and increased accumulation of Abeta in DS lenses. Incubation of synthetic Abeta with human lens protein promoted protein aggregation, amyloid formation, and light scattering that recapitulated the molecular pathology and clinical features observed in DS lenses. These results establish the genetic etiology of the distinctive lens phenotype in DS and identify the molecular origin and pathogenic mechanism by which lens pathology is expressed in this common chromosomal disorder. Moreover, these findings confirm increased Abeta

alpha7 Nicotinic acetylcholine receptor knockout selectively enhances ethanol-, but not beta-amyloid-induced neurotoxicity.

Science.gov (United States)

de Fiebre, Nancyellen C; de Fiebre, Christopher M

2005-01-03

The alpha7 subtype of nicotinic acetylcholine receptor (nAChR) has been implicated as a potential site of action for two neurotoxins, ethanol and the Alzheimer's disease related peptide, beta-amyloid. Here, we utilized primary neuronal cultures of cerebral cortex from alpha7 nAChR null mutant mice to examine the role of this receptor in modulating the neurotoxic properties of subchronic, "binge" ethanol and beta-amyloid. Knockout of the alpha7 nAChR gene selectively enhanced ethanol-induced neurotoxicity in a gene dosage-related fashion. Susceptibility of cultures to beta-amyloid induced toxicity, however, was unaffected by alpha7 nAChR gene null mutation. Further, beta-amyloid did not inhibit the binding of the highly alpha7-selective radioligand, [(125)I]alpha-bungarotoxin. On the other hand, in studies in Xenopus oocytes ethanol efficaciously inhibited alpha7 nAChR function. These data suggest that alpha7 nAChRs modulate the neurotoxic effects of binge ethanol, but not the neurotoxicity produced by beta-amyloid. It is hypothesized that inhibition of alpha7 nAChRs by ethanol provides partial protection against the neurotoxic properties of subchronic ethanol.

Detection of AA-type amyloid protein in labial salivary glands.

Science.gov (United States)

Sacsaquispe, Sonia-Julia; Antúnez-de Mayolo, Eleazar-Antonio; Vicetti, Rodolfo; Delgado, Wilson-Alejandro

2011-03-01

Among the diverse forms of amyloidosis, secondary type is the most frequent one. Diagnosis of amyloid deposition is based on the identification of the fibrillary protein amyloid by means of Congo Red (CR) or crystal violet (CV) stains, but these techniques do not differentiate between the different types of amyloid fibrils. The aim of this study was to identify by immunofluorescence (IF) AA amyloid a pathological fibrillar low-molecular-weight protein formed by cleavage of serum amyloid A (SAA) protein in labial salivary gland (LSG) biopsies from patients with secondary amyloidosis. 98 LSG were studied, 65 were from patients with secondary amyloidosis and 33 from subjects with chronic inflammatory diseases without evidence of this anomaly. All sections were stained with hematoxylin and eosin (H &E), CV, CR and IF using anti-AA antibodies. Positive and negative controls were used for all techniques. CV and CR demonstrated that the amyloid substance was found mainly distributed periductally (93.8%), followed by periacinar and perivascular locations (p <0.001); however, the IF demonstrated that amyloid AA substance predominates in the periacinar area (73.8%), followed by periductal and perivascular locations (p <0.001). IF has a sensitivity of 83%, 100% of specificity, 100% of predictive positive value and 75% of predictive negative value. The results of this study confirm the efficacy of the LSG biopsy as a highly reliable method for diagnosis of secondary amyloidosis.

Chemokines, macrophage inflammatory protein-2 and stromal cell-derived factor-1{alpha}, suppress amyloid {beta}-induced neurotoxicity

Energy Technology Data Exchange (ETDEWEB)

Raman, Dayanidhi; Milatovic, Snjezana-Zaja [Department of Cancer Biology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States); Milatovic, Dejan [Department of Pediatrics/Pediatric Toxicology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States); Splittgerber, Ryan [Department of Cancer Biology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States); Fan, Guo-Huang [Department of Neurobiology and Neurotoxicology, Meharry Medical College, Nashville, TN 37221 (United States); Richmond, Ann, E-mail: ann.richmond@vanderbilt.edu [VA Medical Center, Nashville, TN 37232 (United States); Department of Cancer Biology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States)

2011-11-15

Alzheimer's disease (AD) is characterized by a progressive cognitive decline and accumulation of neurotoxic oligomeric peptides amyloid-{beta} (A{beta}). Although the molecular events are not entirely known, it has become evident that inflammation, environmental and other risk factors may play a causal, disruptive and/or protective role in the development of AD. The present study investigated the ability of the chemokines, macrophage inflammatory protein-2 (MIP-2) and stromal cell-derived factor-1{alpha} (SDF-1{alpha}), the respective ligands for chemokine receptors CXCR2 and CXCR4, to suppress A{beta}-induced neurotoxicity in vitro and in vivo. Pretreatment with MIP-2 or SDF-1{alpha} significantly protected neurons from A{beta}-induced dendritic regression and apoptosis in vitro through activation of Akt, ERK1/2 and maintenance of metalloproteinase ADAM17 especially with SDF-1{alpha}. Intra-cerebroventricular (ICV) injection of A{beta} led to reduction in dendritic length and spine density of pyramidal neurons in the CA1 area of the hippocampus and increased oxidative damage 24 h following the exposure. The A{beta}-induced morphometric changes of neurons and increase in biomarkers of oxidative damage, F{sub 2}-isoprostanes, were significantly inhibited by pretreatment with the chemokines MIP-2 or SDF-1{alpha}. Additionally, MIP-2 or SDF-1{alpha} was able to suppress the aberrant mislocalization of p21-activated kinase (PAK), one of the proteins involved in the maintenance of dendritic spines. Furthermore, MIP-2 also protected neurons against A{beta} neurotoxicity in CXCR2-/- mice, potentially through observed up regulation of CXCR1 mRNA. Understanding the neuroprotective potential of chemokines is crucial in defining the role for their employment during the early stages of neurodegeneration. -- Research highlights: Black-Right-Pointing-Pointer Neuroprotective ability of the chemokines MIP2 and CXCL12 against A{beta} toxicity. Black-Right-Pointing-Pointer MIP

Cross-interactions between the Alzheimer Disease Amyloid-β Peptide and Other Amyloid Proteins: A Further Aspect of the Amyloid Cascade Hypothesis.

Science.gov (United States)

Luo, Jinghui; Wärmländer, Sebastian K T S; Gräslund, Astrid; Abrahams, Jan Pieter

2016-08-05

Many protein folding diseases are intimately associated with accumulation of amyloid aggregates. The amyloid materials formed by different proteins/peptides share many structural similarities, despite sometimes large amino acid sequence differences. Some amyloid diseases constitute risk factors for others, and the progression of one amyloid disease may affect the progression of another. These connections are arguably related to amyloid aggregates of one protein being able to directly nucleate amyloid formation of another, different protein: the amyloid cross-interaction. Here, we discuss such cross-interactions between the Alzheimer disease amyloid-β (Aβ) peptide and other amyloid proteins in the context of what is known from in vitro and in vivo experiments, and of what might be learned from clinical studies. The aim is to clarify potential molecular associations between different amyloid diseases. We argue that the amyloid cascade hypothesis in Alzheimer disease should be expanded to include cross-interactions between Aβ and other amyloid proteins. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Effect of copper (II) ion against elongation behavior of amyloid {beta} fibrils on liposome membranes

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Shimanouchi, T.; Onishi, R.; Kitaura, N.; Umakoshi, H.; Kuboi, R. [Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka (Japan)

2012-01-15

The fibril growth behavior of amyloid {beta} protein (A{beta}) on cell membranes is relating to the progression of Alzheimer's disease. This growth behavior of A{beta} fibrils is sensitively affected by the metal ions, neurotransmitters, or bioreactive substrate. The inhibitory effect of those materials was quantitatively estimated from the viewpoints of ''crystal growth''. In a bulk aqueous solution, copper (II) ion showed the strong inhibitory effect on the growth of A{beta} fibrils. Meanwhile, the addition of a closed-phospholipid bilayer membrane (liposome) could reduce the above inhibitory effect of copper (II) ion. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Familial Alzheimer's disease mutations in presenilin 1 do not alter levels of the secreted amyloid-beta protein precursor generated by beta-secretase cleavage.

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Zhang, Can; Browne, Andrew; Kim, Doo Yeon; Tanzi, Rudolph E

2010-02-01

Alzheimer's disease (AD) is an insidious and progressive disease with a genetically complex and heterogenous etiology. More than 200 fully penetrant mutations in the amyloid beta-protein precursor (APP), presenilin 1 (or PSEN1), and presenilin 2 (PSEN2) have been linked to early-onset familial AD (FAD). 177 PSEN1 FAD mutations have been identified so far and account for more than approximately 80% of all FAD mutations. All PSEN1 FAD mutations can increase the Abeta42:Abeta40 ratio with seemingly different and incompletely understood mechanisms. A recent study has shown that the 286 amino acid N-terminal fragment of APP (N-APP), a proteolytic product of beta-secretase-derived secreted form of APP (sAPPbeta), could bind the death receptor, DR6, and lead to neurodegeneration. Here we asked whether PSEN1 FAD mutations lead to neurodegeneration by modulating sAPPbeta levels. All four different PSEN1 FAD mutations tested (in three mammalian cell lines) did not alter sAPPbeta levels. Therefore PS1 mutations do not appear to contribute to AD pathogenesis via altered production of sAPPbeta.

The Alzheimer's disease-associated amyloid beta-protein is an antimicrobial peptide.

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Stephanie J Soscia

2010-03-01

Full Text Available The amyloid beta-protein (Abeta is believed to be the key mediator of Alzheimer's disease (AD pathology. Abeta is most often characterized as an incidental catabolic byproduct that lacks a normal physiological role. However, Abeta has been shown to be a specific ligand for a number of different receptors and other molecules, transported by complex trafficking pathways, modulated in response to a variety of environmental stressors, and able to induce pro-inflammatory activities.Here, we provide data supporting an in vivo function for Abeta as an antimicrobial peptide (AMP. Experiments used established in vitro assays to compare antimicrobial activities of Abeta and LL-37, an archetypical human AMP. Findings reveal that Abeta exerts antimicrobial activity against eight common and clinically relevant microorganisms with a potency equivalent to, and in some cases greater than, LL-37. Furthermore, we show that AD whole brain homogenates have significantly higher antimicrobial activity than aged matched non-AD samples and that AMP action correlates with tissue Abeta levels. Consistent with Abeta-mediated activity, the increased antimicrobial action was ablated by immunodepletion of AD brain homogenates with anti-Abeta antibodies.Our findings suggest Abeta is a hitherto unrecognized AMP that may normally function in the innate immune system. This finding stands in stark contrast to current models of Abeta-mediated pathology and has important implications for ongoing and future AD treatment strategies.

Aluminum complexing enhances amyloid beta protein penetration of blood-brain barrier.

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Banks, William A; Niehoff, Michael L; Drago, Denise; Zatta, Paolo

2006-10-20

A significant co-morbidity of Alzheimer's disease and cerebrovascular impairment suggests that cerebrovascular dysregulation is an important feature of dementia. Amyloid beta protein (Abeta), a relevant risk factor in Alzheimer's disease, has neurotoxic properties and is thought to play a critical role in the cognitive impairments. Previously, we demonstrated that the 42mer of Abeta (Abeta42) complexed with aluminum (Al-Abeta42) is much more cytotoxic than non-complexed Abeta42. The level of Abeta in the brain is a balance between synthesis, degradation, and fluxes across the blood-brain barrier (BBB). In the present paper, we determined whether complexing with aluminum affected the ability of radioactively iodinated Abeta to cross the in vivo BBB. We found that the rates of uptake of Al-Abeta42 and Abeta42 were similar, but that Al-Abeta42 was sequestered by brain endothelial cells much less than Abeta42 and so more readily entered the parenchymal space of the brain. Al-Abeta42 also had a longer half-life in blood and had increased permeation at the striatum and thalamus. Brain-to-blood transport was similar for Al-Abeta42 and Abeta42. In conclusion, complexing with aluminum affects some aspects of blood-to-brain permeability so that Al-Abeta42 would have more ready access to brain cells than Abeta42.

Absence of beta-amyloid in cortical cataracts of donors with and without Alzheimer's disease.

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Michael, Ralph; Rosandić, Jurja; Montenegro, Gustavo A; Lobato, Elvira; Tresserra, Francisco; Barraquer, Rafael I; Vrensen, Gijs F J M

2013-01-01

Eye lenses from human donors with and without Alzheimer's disease (AD) were studied to evaluate the presence of amyloid in cortical cataract. We obtained 39 lenses from 21 postmortem donors with AD and 15 lenses from age-matched controls provided by the Banco de Ojos para Tratamientos de la Ceguera (Barcelona, Spain). For 17 donors, AD was clinically diagnosed by general physicians and for 4 donors the AD diagnosis was neuropathologically confirmed. Of the 21 donors with AD, 6 had pronounced bilateral cortical lens opacities and 15 only minor or no cortical opacities. As controls, 7 donors with pronounced cortical opacities and 8 donors with almost transparent lenses were selected. All lenses were photographed in a dark field stereomicroscope. Histological sections were analyzed using a standard and a more sensitive Congo red protocol, thioflavin staining and beta-amyloid immunohistochemistry. Brain tissue from two donors, one with cerebral amyloid angiopathy and another with advanced AD-related changes and one cornea with lattice dystrophy were used as positive controls for the staining techniques. Thioflavin, standard and modified Congo red staining were positive in the control brain tissues and in the dystrophic cornea. Beta-amyloid immunohistochemistry was positive in the brain tissues but not in the cornea sample. Lenses from control and AD donors were, without exception, negative after Congo red, thioflavin, and beta-amyloid immunohistochemical staining. The results of the positive control tissues correspond well with known observations in AD, amyloid angiopathy and corneas with lattice dystrophy. The absence of staining in AD and control lenses with the techniques employed lead us to conclude that there is no beta-amyloid in lenses from donors with AD or in control cortical cataracts. The inconsistency with previous studies of Goldstein et al. (2003) and Moncaster et al. (2010), both of which demonstrated positive Congo red, thioflavin, and beta-amyloid

Tetrahydroxystilbene glucoside modulates amyloid precursor protein processing via activation of AKT-GSK3β pathway in cells and in APP/PS1 transgenic mice.

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Yin, Xiaomin; Chen, Chen; Xu, Ting; Li, Lin; Zhang, Lan

2018-01-01

Alternative splicing of amyloid precursor protein (APP) exon 7 generates the isoforms containing a Kunitz protease inhibitor (KPI) domain. APP-KPI levels in the brain are correlated with amyloid beta (Aβ) production. Here, we determined the effect of Tetrahydroxystilbene glucoside (TSG) on the AKT-GSK3β pathway. We found GSK3β increased APP-KPI inclusion level and interacted with the splicing factor ASF. TSG was intragastrically administered to 5-month-old APP/PS1 transgenic mice for 12 months. We found that the activated the AKT-GSK3β signaling pathway suppressed APP-KPI inclusion. Moreover, TSG treatment attenuated amyloid deposition in APP/PS1 mice. This study demonstrates the neuroprotective effect of TSG on APP expression, suggesting that TSG may be beneficial for AD prevention and treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Amyloid- and FDG-PET in sporadic Creutzfeldt-Jakob disease: Correlation with pathological prion protein in neuropathology.

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Matías-Guiu, Jordi A; Guerrero-Márquez, Carmen; Cabrera-Martín, María Nieves; Gómez-Pinedo, Ulises; Romeral, María; Mayo, Diego; Porta-Etessam, Jesús; Moreno-Ramos, Teresa; Carreras, José Luis; Matías-Guiu, Jorge

2017-05-04

The role of positron emission tomography (PET) in Creutzfeldt-Jakob disease is less defined than in other neurodegenerative diseases. We studied the correlation between the uptake of 18 F-florbetaben and 18 F-fluorodeoxyglucose with pathological prion protein deposition in histopathology in a case. A patient with 80 y old with a rapid neurological deterioration with a confirmed diagnosis of CJD was studied. PET and MRI studies were performed between 13-20 d before the death. A region of interest analysis was performed using Statistical Parametric Mapping. MRI showed atrophy with no other alterations. FDG-PET showed extensive areas of hypometabolism including left frontoparietal lobes as well as bilateral thalamus. Correlation between uptake of 18 F-florbetaben and pathological prion protein deposition was r = 0.786 (p < 0.05). Otherwise, correlation between uptake of 18 F-FDG and pathological prion protein was r = 0.357 (p = 0.385). Immunohistochemistry with β-amyloid did not show amyloid deposition or neuritic plaques. Our study supports the use of FDG-PET in the assessment of CJD. FDG-PET may be especially useful in cases of suspected CJD and negative MRI. Furthermore, this case report provides more evidence about the behavioral of amyloid tracers, and the possibility of a low-affinity binding to other non-amyloid proteins, such as the pathological prion protein, is discussed.

Data supporting beta-amyloid dimer structural transitions and protein–lipid interactions on asymmetric lipid bilayer surfaces using MD simulations on experimentally derived NMR protein structures

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Sara Y. Cheng

2016-06-01

Full Text Available This data article supports the research article entitled “Maximally Asymmetric Transbilayer Distribution of Anionic Lipids Alters the Structure and interaction with Lipids of an Amyloidogenic Protein Dimer Bound to the Membrane Surface” [1]. We describe supporting data on the binding kinetics, time evolution of secondary structure, and residue-contact maps of a surface-absorbed beta-amyloid dimer protein on different membrane surfaces. We further demonstrate the sorting of annular and non-annular regions of the protein/lipid bilayer simulation systems, and the correlation of lipid-number mismatch and surface area per lipid mismatch of asymmetric lipid membranes.

Quantification of amyloid-beta 40 in cerebrospinal fluid

NARCIS (Netherlands)

Verwey, N.A.; Veerhuis, R.; Twaalfhoven, H.A.M.; Wouters, D.; Hoozemans, J.J.M.; Bollen, Y.J.M.; Killestein, J.; Bibl, M.; Wiltfang, J.; Hack, C.E.; Scheltens, P.; Blankenstein, M.A.

2009-01-01

Background: Truncated forms and full-length forms of the amyloid-beta 40 (Aβ40) are key molecules in the pathogenesis of dementia, and are detectable in CSF. Reliable methods to detect these biomarkers in CSF are of great importance for understanding the disease mechanisms and for diagnostic

Heterologous amyloid seeding: revisiting the role of acetylcholinesterase in Alzheimer's disease.

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Létitia Jean

2007-07-01

Full Text Available Neurodegenerative diseases associated with abnormal protein folding and ordered aggregation require an initial trigger which may be infectious, inherited, post-inflammatory or idiopathic. Proteolytic cleavage to generate vulnerable precursors, such as amyloid-beta peptide (Abeta production via beta and gamma secretases in Alzheimer's Disease (AD, is one such trigger, but the proteolytic removal of these fragments is also aetiologically important. The levels of Abeta in the central nervous system are regulated by several catabolic proteases, including insulysin (IDE and neprilysin (NEP. The known association of human acetylcholinesterase (hAChE with pathological aggregates in AD together with its ability to increase Abeta fibrilization prompted us to search for proteolytic triggers that could enhance this process. The hAChE C-terminal domain (T40, AChE(575-614 is an exposed amphiphilic alpha-helix involved in enzyme oligomerisation, but it also contains a conformational switch region (CSR with high propensity for conversion to non-native (hidden beta-strand, a property associated with amyloidogenicity. A synthetic peptide (AChE(586-599 encompassing the CSR region shares homology with Abeta and forms beta-sheet amyloid fibrils. We investigated the influence of IDE and NEP proteolysis on the formation and degradation of relevant hAChE beta-sheet species. By combining reverse-phase HPLC and mass spectrometry, we established that the enzyme digestion profiles on T40 versus AChE(586-599, or versus Abeta, differed. Moreover, IDE digestion of T40 triggered the conformational switch from alpha- to beta-structures, resulting in surfactant CSR species that self-assembled into amyloid fibril precursors (oligomers. Crucially, these CSR species significantly increased Abeta fibril formation both by seeding the energetically unfavorable formation of amyloid nuclei and by enhancing the rate of amyloid elongation. Hence, these results may offer an explanation

Natural Modulators of Amyloid-Beta Precursor Protein Processing

Science.gov (United States)

Zhang, Can; Tanzi, Rudolph E.

2013-01-01

Alzheimer’s disease (AD) is a devastating neurodegenerative disease and the primary cause of dementia, with no cure currently available. The pathogenesis of AD is believed to be primarily driven by Aβ, the principal component of senile plaques. Aβ is an ~4 kDa peptide generated from the amyloid-β precursor protein (APP) through proteolytic secretases. Natural products, particularly those utilized in traditional Chinese medicine (TCM), have a long history alleviating common clinical disorders, including dementia. However, the cell/molecular pathways mediated by these natural products are largely unknown until recently when the underlying molecular mechanisms of the disorders begin to be elucidated. Here, the mechanisms with which natural products modulate the pathogenesis of AD are discussed, in particular, by focusing on their roles in the processing of APP. PMID:22998566

Beta-amyloid, cholinergní neurony a Alzheimerova choroba

Czech Academy of Sciences Publication Activity Database

Kašparová, Jana; Doležal, Vladimír

2002-01-01

Roč. 51, č. 2 (2002), s. 82-94 ISSN 0009-0557 R&D Projects: GA MZd NF5183; GA ČR GA305/01/0283 Institutional research plan: CEZ:AV0Z5011922 Keywords : Alzheimer 's disease * beta-amyloid * cholinergic neurons Subject RIV: FR - Pharmacology ; Medidal Chemistry

Evaluation of the amyloid beta-GFP fusion protein as a model of amyloid beta peptides-mediated aggregation: A study of DNAJB6 chaperone

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Rasha Mohamed Hussein

2015-07-01

Full Text Available Alzheimer’s disease is a progressive neurodegenerative disease characterized by the accumulation and aggregation of extracellular amyloid β (Aβ peptides and intracellular aggregation of hyper-phosphorylated tau protein. Recent evidence indicates that accumulation and aggregation of intracellular amyloid β peptides may also play a role in disease pathogenesis. This would suggest that intracellular Heat Shock Proteins (HSP that maintain cellular protein homeostasis might be candidates for disease amelioration. We recently found that DNAJB6, a member of DNAJ family of heat shock proteins, effectively prevented the aggregation of short aggregation-prone peptides containing large poly glutamines (associated with CAG repeat diseases both in vitro and in cells. Moreover, recent in vitro data showed that DNAJB6 can delay the aggregation of Aβ42 peptides. In this study, we investigated the ability of DNAJB6 to prevent the aggregation of extracellular and intracellular Aβ peptides using transfection of HEK293 cells with Aβ-GFP fusion construct and performing western blotting and immunofluorescence techniques. We found that DNAJB6 indeed suppresses Aβ-GFP aggregation, but not seeded aggregation initiated by extracellular Aβ peptides. Unexpectedly and unlike what we found for peptide-mediated aggregation, DNAJB6 required interaction with HSP70 to prevent the aggregation of the Aβ-GFP fusion protein and its J-domain was crucial for its anti-aggregation effect. In addition, other DNAJ proteins as well as HSPA1a overexpression also suppressed Aβ-GFP aggregation efficiently. Our findings suggest that Aβ aggregation differs from poly Q peptide induced aggregation in terms of chaperone handling and sheds doubt on the usage of Aβ-GFP fusion construct for studying Aβ peptide aggregation in cells.

Quantification of beta A4 protein deposition in the medial temporal lobe: a comparison of Alzheimer's disease and senile dementia of the Lewy body type.

Science.gov (United States)

Gentleman, S M; Williams, B; Royston, M C; Jagoe, R; Clinton, J; Perry, R H; Ince, P G; Allsop, D; Polak, J M; Roberts, G W

1992-08-03

The distribution of beta-amyloid protein (beta A4) was examined in the medial temporal lobes from cases of Alzheimer's disease (AD) (n = 13), senile dementia of Lewy body type (SDLT) (n = 12) and age matched controls (n = 9). Using a previously described image analysis technique the extent of beta A4 pathology was determined in ten distinct anatomical sites within the medial temporal lobe. AD and SDLT cases contained very similar amounts of beta A4 in the areas sampled and both contained significantly more beta A4 than the age matched controls, particularly in the dentate and parahippocampal gyri. The similarity of the beta A4 load in the two conditions is in contrast to reported differences in the number of neurofibrillary tangles which can be observed. It is suggested that AD and SDLT represent a spectrum of pathology which centres around the aberrant processing of the beta A4 precursor protein.

Elucidation of amyloid beta-protein oligomerization mechanisms: discrete molecular dynamics study.

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Urbanc, B; Betnel, M; Cruz, L; Bitan, G; Teplow, D B

2010-03-31

Oligomers of amyloid beta-protein (Abeta) play a central role in the pathology of Alzheimer's disease. Of the two predominant Abeta alloforms, Abeta(1-40) and Abeta(1-42), Abeta(1-42) is more strongly implicated in the disease. We elucidated the structural characteristics of oligomers of Abeta(1-40) and Abeta(1-42) and their Arctic mutants, [E22G]Abeta(1-40) and [E22G]Abeta(1-42). We simulated oligomer formation using discrete molecular dynamics (DMD) with a four-bead protein model, backbone hydrogen bonding, and residue-specific interactions due to effective hydropathy and charge. For all four peptides under study, we derived the characteristic oligomer size distributions that were in agreement with prior experimental findings. Unlike Abeta(1-40), Abeta(1-42) had a high propensity to form paranuclei (pentameric or hexameric) structures that could self-associate into higher-order oligomers. Neither of the Arctic mutants formed higher-order oligomers, but [E22G]Abeta(1-40) formed paranuclei with a similar propensity to that of Abeta(1-42). Whereas the best agreement with the experimental data was obtained when the charged residues were modeled as solely hydrophilic, further assembly from spherical oligomers into elongated protofibrils was induced by nonzero electrostatic interactions among the charged residues. Structural analysis revealed that the C-terminal region played a dominant role in Abeta(1-42) oligomer formation whereas Abeta(1-40) oligomerization was primarily driven by intermolecular interactions among the central hydrophobic regions. The N-terminal region A2-F4 played a prominent role in Abeta(1-40) oligomerization but did not contribute to the oligomerization of Abeta(1-42) or the Arctic mutants. The oligomer structure of both Arctic peptides resembled Abeta(1-42) more than Abeta(1-40), consistent with their potentially more toxic nature.

In vivo changes in microglial activation and amyloid deposits in brain regions with hypometabolism in Alzheimer's disease

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Yokokura, Masamichi; Mori, Norio; Yoshihara, Yujiro; Wakuda, Tomoyasu; Takebayashi, Kiyokazu; Iwata, Yasuhide; Nakamura, Kazuhiko [Hamamatsu University School of Medicine, Department of Psychiatry and Neurology, Hamamatsu (Japan); Yagi, Shunsuke; Ouchi, Yasuomi [Hamamatsu University School of Medicine, Laboratory of Human Imaging Research, Molecular Imaging Frontier Research Center, Hamamatsu (Japan); Yoshikawa, Etsuji [Hamamatsu Photonics K.K., Central Research Laboratory, Hamamatsu (Japan); Kikuchi, Mitsuru [Kanazawa University, Department of Psychiatry and Neurobiology, Graduate School of Medical Science, Kanazawa (Japan); Sugihara, Genichi; Suda, Shiro; Tsuchiya, Kenji J.; Suzuki, Katsuaki [Hamamatsu University School of Medicine, Research Center for Child Mental Development, Hamamatsu (Japan); Ueki, Takatoshi [Hamamatsu University School of Medicine, Department of Anatomy, Hamamatsu (Japan)

2011-02-15

Amyloid {beta} protein (A{beta}) is known as a pathological substance in Alzheimer's disease (AD) and is assumed to coexist with a degree of activated microglia in the brain. However, it remains unclear whether these two events occur in parallel with characteristic hypometabolism in AD in vivo. The purpose of the present study was to clarify the in vivo relationship between A{beta} accumulation and neuroinflammation in those specific brain regions in early AD. Eleven nootropic drug-naive AD patients underwent a series of positron emission tomography (PET) measurements with [{sup 11}C](R)PK11195, [{sup 11}C]PIB and [{sup 18}F]FDG and a battery of cognitive tests within the same day. The binding potentials (BPs) of [{sup 11}C](R)PK11195 were directly compared with those of [{sup 11}C]PIB in the brain regions with reduced glucose metabolism. BPs of [{sup 11}C](R)PK11195 and [{sup 11}C]PIB were significantly higher in the parietotemporal regions of AD patients than in ten healthy controls. In AD patients, there was a negative correlation between dementia score and [{sup 11}C](R)PK11195 BPs, but not [{sup 11}C]PIB, in the limbic, precuneus and prefrontal regions. Direct comparisons showed a significant negative correlation between [{sup 11}C](R)PK11195 and [{sup 11}C]PIB BPs in the posterior cingulate cortex (PCC) (p < 0.05, corrected) that manifested the most severe reduction in [{sup 18}F]FDG uptake. A lack of coupling between microglial activation and amyloid deposits may indicate that A{beta} accumulation shown by [{sup 11}C]PIB is not always the primary cause of microglial activation, but rather the negative correlation present in the PCC suggests that microglia can show higher activation during the production of A{beta} in early AD. (orig.)

Chemical Methods to Knock Down the Amyloid Proteins

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Na Gao

2017-06-01

Full Text Available Amyloid proteins are closely related with amyloid diseases and do tremendous harm to human health. However, there is still a lack of effective strategies to treat these amyloid diseases, so it is important to develop novel methods. Accelerating the clearance of amyloid proteins is a favorable method for amyloid disease treatment. Recently, chemical methods for protein reduction have been developed and have attracted much attention. In this review, we focus on the latest progress of chemical methods that knock down amyloid proteins, including the proteolysis-targeting chimera (PROTAC strategy, the “recognition-cleavage” strategy, the chaperone-mediated autophagy (CMA strategy, the selectively light-activatable organic and inorganic molecules strategy and other chemical strategies.

Oxidative stress and the amyloid beta peptide in Alzheimer’s disease

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C. Cheignon

2018-04-01

Full Text Available Oxidative stress is known to play an important role in the pathogenesis of a number of diseases. In particular, it is linked to the etiology of Alzheimer’s disease (AD, an age-related neurodegenerative disease and the most common cause of dementia in the elderly. Histopathological hallmarks of AD are intracellular neurofibrillary tangles and extracellular formation of senile plaques composed of the amyloid-beta peptide (Aβ in aggregated form along with metal-ions such as copper, iron or zinc. Redox active metal ions, as for example copper, can catalyze the production of Reactive Oxygen Species (ROS when bound to the amyloid-β (Aβ. The ROS thus produced, in particular the hydroxyl radical which is the most reactive one, may contribute to oxidative damage on both the Aβ peptide itself and on surrounding molecule (proteins, lipids, …. This review highlights the existing link between oxidative stress and AD, and the consequences towards the Aβ peptide and surrounding molecules in terms of oxidative damage. In addition, the implication of metal ions in AD, their interaction with the Aβ peptide and redox properties leading to ROS production are discussed, along with both in vitro and in vivo oxidation of the Aβ peptide, at the molecular level. Keywords: Oxidative stress, Amyloid beta peptide, Metal-ions, Reactive oxygen species, Oxidative damages

Impact of amyloid imaging on drug development in Alzheimer's disease

Energy Technology Data Exchange (ETDEWEB)

Mathis, Chester A. [Department of Radiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213 (United States)], E-mail: mathisca@upmc.edu; Lopresti, Brian J. [Department of Radiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213 (United States); Klunk, William E. [Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213 (United States)

2007-10-15

Imaging agents capable of assessing amyloid-beta (A{beta}) content in vivo in the brains of Alzheimer's disease (AD) subjects likely will be important as diagnostic agents to detect A{beta} plaques in the brain as well as to help test the amyloid cascade hypothesis of AD and as an aid to assess the efficacy of anti-amyloid therapeutics currently under development and in clinical trials. Positron emission tomography (PET) imaging studies of amyloid deposition in human subjects with several A{beta} imaging agents are currently underway. We reported the first PET studies of the carbon 11-labeled thioflavin-T derivative Pittsburgh Compound B in 2004, and this work has subsequently been extended to include a variety of subject groups, including AD patients, mild cognitive impairment patients and healthy controls. The ability to quantify regional A{beta} plaque load in the brains of living human subjects has provided a means to begin to apply this technology as a diagnostic agent to detect regional concentrations of A{beta} plaques and as a surrogate marker of therapeutic efficacy in anti-amyloid drug trials.

A hydrogel biosensor for high selective and sensitive detection of amyloid-beta oligomers

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Sun LP

2018-02-01

Full Text Available Liping Sun,1 Yong Zhong,1 Jie Gui,1 Xianwu Wang,1 Xiaorong Zhuang,2 Jian Weng1 1Key Laboratory of Biomedical Engineering of Fujian Province, Research Center of Biomedical Engineering of Xiamen, Department of Biomaterials, College of Materials, Xiamen University, 2Department of Neurology, The Affiliated Zhongshan Hospital of Xiamen University, Xiamen, People’s Republic of China Background: Alzheimer’s disease (AD is a neurodegenerative disorder characterized by progressive cognitive and memory impairment. It is the most common neurological disease that causes dementia. Soluble amyloid-beta oligomers (AβO in blood or cerebrospinal fluid (CSF are the pathogenic biomarker correlated with AD. Methods: A simple electrochemical biosensor using graphene oxide/gold nanoparticles (GNPs hydrogel electrode was developed in this study. Thiolated cellular prion protein (PrPC peptide probe was immobilized on GNPs of the hydrogel electrode to construct an AβO biosensor. Electrochemical impedance spectroscopy was utilized for AβO analysis. Results: The specific binding between AβO and PrPC probes on the hydrogel electrode resulted in an increase in the electron-transfer resistance. The biosensor showed high specificity and sensitivity for AβO detection. It could selectively differentiate AβO from amyloid-beta (Aβ monomers or fibrils. Meanwhile, it was highly sensitive to detect as low as 0.1 pM AβO in artificial CSF or blood plasma. The linear range for AβO detection is from 0.1 pM to 10 nM. Conclusion: This biosensor could be used as a cost-effective tool for early diagnosis of AD due to its high electrochemical performance and bionic structure. Keywords: Alzheimer’s disease, amyloid-beta oligomer, graphene, gold nanoparticles, biosensor

Clinical and imaging correlates of amyloid deposition in dementia with Lewy bodies.

Science.gov (United States)

Donaghy, Paul C; Firbank, Michael J; Thomas, Alan J; Lloyd, Jim; Petrides, George; Barnett, Nicola; Olsen, Kirsty; O'Brien, John T

2018-04-19

Amyloid deposition is common in dementia with Lewy bodies, but its pathophysiological significance is unclear. The objective of this study was to investigate the relationship between amyloid deposition and clinical profile, gray matter volume, and brain perfusion in dementia with Lewy bodies. Dementia with Lewy bodies (n = 37), Alzheimer's disease (n = 20), and controls (n = 20) underwent a thorough clinical assessment, 3T MRI, and early- and late-phase 18 F-Florbetapir PET-CT to assess cortical perfusion and amyloid deposition, respectively. Amyloid scans were visually categorized as positive or negative. Image analysis was carried out using statistical parametric mapping (SPM) 8. There were no significant differences between amyloid-positive and amyloid-negative dementia with Lewy bodies cases in age (P = .78), overall cognitive impairment (P = .83), level of functional impairment (P = .80), or any other clinical or cognitive scale. There were also no significant differences in hippocampal or gray matter volumes. However, amyloid-positive dementia with Lewy bodies cases had lower medial temporal lobe perfusion (P = .03) than amyloid-negative cases, although a combination of medial temporal lobe perfusion, hippocampal volume, and cognitive measures was unable to accurately predict amyloid status in dementia with Lewy bodies. Amyloid deposition was not associated with differences in clinical or neuropsychological profiles in dementia with Lewy bodies, but was associated with imaging evidence of medial temporal lobe dysfunction. The presence of amyloid in dementia with Lewy bodies cannot be identified on the basis of clinical and other imaging features and will require direct assessment via PET imaging or CSF. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf

Effects of Capsule Yi -Zhi on learning and memory disorder and beta-amyloid peptide induced neurotoxicity in rats

Institute of Scientific and Technical Information of China (English)

XUJiang-Ping; WUHang-Yu; LILin

2004-01-01

AIM To investigate the effects of Capsule Yi-Zhi (CYZ) on learning and memory disorder and beta-amyloid protein induced neurotoxieity in rats. Methods Various doses of CYZ were administered to Sprague-Dawley (SD) rats for 8 days, twice a day. Then scopolamine hydrobromide (Sco) intraperitoneal injection was performed on each rat and the

HIV-1 stimulates nuclear entry of amyloid beta via dynamin dependent EEA1 and TGF-β/Smad signaling

International Nuclear Information System (INIS)

András, Ibolya E.; Toborek, Michal

2014-01-01

Clinical evidence indicates increased amyloid deposition in HIV-1-infected brains, which contributes to neurocognitive dysfunction in infected patients. Here we show that HIV-1 exposure stimulates amyloid beta (Aβ) nuclear entry in human brain endothelial cells (HBMEC), the main component of the blood–brain barrier (BBB). Treatment with HIV-1 and/or Aβ resulted in concurrent increase in early endosomal antigen-1 (EEA1), Smad, and phosphorylated Smad (pSmad) in nuclear fraction of HBMEC. A series of inhibition and silencing studies indicated that Smad and EEA1 closely interact by influencing their own nuclear entry; the effect that was attenuated by dynasore, a blocker of GTP-ase activity of dynamin. Importantly, inhibition of dynamin, EEA1, or TGF-β/Smad effectively attenuated HIV-1-induced Aβ accumulation in the nuclei of HBMEC. The present study indicates that nuclear uptake of Aβ involves the dynamin-dependent EEA1 and TGF-β/Smad signaling pathways. These results identify potential novel targets to protect against HIV-1-associated dysregulation of amyloid processes at the BBB level. - Highlights: • HIV-1 induces nuclear accumulation of amyloid beta (Aβ) in brain endothelial cells. • EEA-1 and TGF-Β/Smad act in concert to regulate nuclear entry of Aβ. • Dynamin appropriates the EEA-1 and TGF-Β/Smad signaling. • Dynamin serves as a master regulator of HIV-1-induced nuclear accumulation of Aβ

HIV-1 stimulates nuclear entry of amyloid beta via dynamin dependent EEA1 and TGF-β/Smad signaling

Energy Technology Data Exchange (ETDEWEB)

András, Ibolya E., E-mail: iandras@med.miami; Toborek, Michal, E-mail: mtoborek@med.miami.edu

2014-04-15

Clinical evidence indicates increased amyloid deposition in HIV-1-infected brains, which contributes to neurocognitive dysfunction in infected patients. Here we show that HIV-1 exposure stimulates amyloid beta (Aβ) nuclear entry in human brain endothelial cells (HBMEC), the main component of the blood–brain barrier (BBB). Treatment with HIV-1 and/or Aβ resulted in concurrent increase in early endosomal antigen-1 (EEA1), Smad, and phosphorylated Smad (pSmad) in nuclear fraction of HBMEC. A series of inhibition and silencing studies indicated that Smad and EEA1 closely interact by influencing their own nuclear entry; the effect that was attenuated by dynasore, a blocker of GTP-ase activity of dynamin. Importantly, inhibition of dynamin, EEA1, or TGF-β/Smad effectively attenuated HIV-1-induced Aβ accumulation in the nuclei of HBMEC. The present study indicates that nuclear uptake of Aβ involves the dynamin-dependent EEA1 and TGF-β/Smad signaling pathways. These results identify potential novel targets to protect against HIV-1-associated dysregulation of amyloid processes at the BBB level. - Highlights: • HIV-1 induces nuclear accumulation of amyloid beta (Aβ) in brain endothelial cells. • EEA-1 and TGF-Β/Smad act in concert to regulate nuclear entry of Aβ. • Dynamin appropriates the EEA-1 and TGF-Β/Smad signaling. • Dynamin serves as a master regulator of HIV-1-induced nuclear accumulation of Aβ.

PPARgamma agonist curcumin reduces the amyloid-beta-stimulated inflammatory responses in primary astrocytes.

Science.gov (United States)

Wang, Hong-Mei; Zhao, Yan-Xin; Zhang, Shi; Liu, Gui-Dong; Kang, Wen-Yan; Tang, Hui-Dong; Ding, Jian-Qing; Chen, Sheng-Di

2010-01-01

Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder. Accumulating data indicate that astrocytes play an important role in the neuroinflammation related to the pathogenesis of AD. It has been shown that microglia and astrocytes are activated in AD brain and amyloid-beta (Abeta) can increase the expression of cyclooxygenase 2 (COX-2), interleukin-1, and interleukin-6. Suppressing the inflammatory response caused by activated astrocytes may help to inhibit the development of AD. Curcumin is a major constituent of the yellow curry spice turmeric and proved to be a potential anti-inflammatory drug in arthritis and colitis. There is a low age-adjusted prevalence of AD in India, a country where turmeric powder is commonly used as a culinary compound. Curcumin has been shown to suppress activated astroglia in amyloid-beta protein precursor transgenic mice. The real mechanism by which curcumin inhibits activated astroglia is poorly understood. Here we report that the expression of COX-2 and glial fibrillary acidic protein were enhanced and that of peroxisome proliferator-activated receptor gamma (PPARgamma) was decreased in Abeta(25-35)-treated astrocytes. In line with these results, nuclear factor-kappaB translocation was increased in the presence of Abeta. All these can be reversed by the pretreatment of curcumin. Furthermore, GW9662, a PPARgamma antagonist, can abolish the anti-inflammatory effect of curcumin. These results show that curcumin might act as a PPARgamma agonist to inhibit the inflammation in Abeta-treated astrocytes.

Timing of neurodegeneration and beta-amyloid (Abeta) peptide deposition in the brain of aging kokanee salmon.

Science.gov (United States)

Maldonado, Tammy A; Jones, Richard E; Norris, David O

2002-10-01

Brains of kokanee salmon (Oncorhynchus nerka kennerlyi) in one of four reproductive stages (sexually immature, maturing, sexually mature, and spawning) were stained with cresyl violet and silver stain to visualize neurodegeneration. These reproductive stages correlate with increasing somatic aging of kokanee salmon, which die after spawning. Twenty-four regions of each brain were examined. Brains of sexually immature fish exhibited low levels of neurodegeneration, whereas neurodegeneration was more marked in maturing fish and greatest in spawning fish. Neurodegeneration was present in specific regions of the telencephalon, diencephalon, mesencephalon, and rhombencephalon. Pyknotic neurons were observed in all regions previously reported to be immunopositive for A beta. Regions that did not exhibit neurodegeneration during aging included the magnocellular vestibular nucleus, the nucleus lateralis tuberis of the hypothalamus, and Purkinje cells of the cerebellum, all of which also lack A beta; perhaps these regions are neuroprotected. In 14 of 16 brain areas for which data were available on both the increase in A beta deposition and pyknosis, neurodegeneration preceded or appeared more or less simultaneously with A beta production, whereas in only two regions did A beta deposition precede neurodegeneration. This information supports the hypothesis that A beta deposition is a downstream product of neurodegeneration in most brain regions. Other conclusions are that the degree of neurodegeneration varies among brain regions, neurodegeneration begins in maturing fish and peaks in spawning fish, the timing of neurodegeneration varies among brain regions, and some regions do not exhibit accelerated neurodegeneration during aging. Copyright 2002 Wiley Periodicals, Inc.

Co-deposition of basement membrane components during the induction of murine splenic AA amyloid

DEFF Research Database (Denmark)

Lyon, A W; Narindrasorasak, S; Young, I D

1991-01-01

Past studies have demonstrated that during murine AA amyloid induction there is co-deposition of the AA amyloid peptide and the basement membrane form of heparan sulfate proteoglycan. The synthesis and accumulation of heparan sulfate proteoglycan does not usually occur in the absence of other...... basement membrane components, such as type IV collagen, laminin, and fibronectin. Using immunohistochemical techniques, the present experiments have demonstrated that in addition to the heparan sulfate proteoglycan, there are other basement membrane components present in splenic AA amyloid deposits...... and these are present as soon as AA amyloid deposits are detectable. The results indicate that within the time constraints imposed by the experiments, the basement membrane components, fibronectin, laminin, type IV collagen, and heparan sulfate proteoglycan are co-deposited 36 to 48 hours after the AgNO3 and amyloid...

A hydrogel biosensor for high selective and sensitive detection of amyloid-beta oligomers.

Science.gov (United States)

Sun, Liping; Zhong, Yong; Gui, Jie; Wang, Xianwu; Zhuang, Xiaorong; Weng, Jian

2018-01-01

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive and memory impairment. It is the most common neurological disease that causes dementia. Soluble amyloid-beta oligomers (AβO) in blood or cerebrospinal fluid (CSF) are the pathogenic biomarker correlated with AD. A simple electrochemical biosensor using graphene oxide/gold nanoparticles (GNPs) hydrogel electrode was developed in this study. Thiolated cellular prion protein (PrP C ) peptide probe was immobilized on GNPs of the hydrogel electrode to construct an AβO biosensor. Electrochemical impedance spectroscopy was utilized for AβO analysis. The specific binding between AβO and PrP C probes on the hydrogel electrode resulted in an increase in the electron-transfer resistance. The biosensor showed high specificity and sensitivity for AβO detection. It could selectively differentiate AβO from amyloid-beta (Aβ) monomers or fibrils. Meanwhile, it was highly sensitive to detect as low as 0.1 pM AβO in artificial CSF or blood plasma. The linear range for AβO detection is from 0.1 pM to 10 nM. This biosensor could be used as a cost-effective tool for early diagnosis of AD due to its high electrochemical performance and bionic structure.

Neuroinflammation and Complexes of 17 beta-Hydroxysteroid Dehydrogenase type 10-Amyloid beta in Alzheimer's Disease

Czech Academy of Sciences Publication Activity Database

Krištofíková, Z.; Řípová, D.; Bartoš, A.; Bocková, Markéta; Hegnerová, Kateřina; Říčný, J.; Čechová, L.; Vrajová, M.; Homola, Jiří

2013-01-01

Roč. 10, č. 2 (2013), s. 165-173 ISSN 1567-2050 R&D Projects: GA MZd(CZ) NT11225 Institutional support: RVO:67985882 Keywords : Amyloid beta * mitochondrial enzyme * Alzheimer 's disease Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 3.796, year: 2013

Neurodegeneration in Alzheimer Disease: Role of Amyloid Precursor Protein and Presenilin 1 Intracellular Signaling

Directory of Open Access Journals (Sweden)

Mario Nizzari

2012-01-01

Full Text Available Alzheimer disease (AD is a heterogeneous neurodegenerative disorder characterized by (1 progressive loss of synapses and neurons, (2 intracellular neurofibrillary tangles, composed of hyperphosphorylated Tau protein, and (3 amyloid plaques. Genetically, AD is linked to mutations in few proteins amyloid precursor protein (APP and presenilin 1 and 2 (PS1 and PS2. The molecular mechanisms underlying neurodegeneration in AD as well as the physiological function of APP are not yet known. A recent theory has proposed that APP and PS1 modulate intracellular signals to induce cell-cycle abnormalities responsible for neuronal death and possibly amyloid deposition. This hypothesis is supported by the presence of a complex network of proteins, clearly involved in the regulation of signal transduction mechanisms that interact with both APP and PS1. In this review we discuss the significance of novel finding related to cell-signaling events modulated by APP and PS1 in the development of neurodegeneration.

Studies of the aggregation of mutant proteins in vitro provide insights into the genetics of amyloid diseases.

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Chiti, Fabrizio; Calamai, Martino; Taddei, Niccolo; Stefani, Massimo; Ramponi, Giampietro; Dobson, Christopher M

2002-12-10

Protein aggregation and the formation of highly insoluble amyloid structures is associated with a range of debilitating human conditions, which include Alzheimer's disease, Parkinson's disease, and the Creutzfeldt-Jakob disease. Muscle acylphosphatase (AcP) has already provided significant insights into mutational changes that modulate amyloid formation. In the present paper, we have used this system to investigate the effects of mutations that modify the charge state of a protein without affecting significantly the hydrophobicity or secondary structural propensities of the polypeptide chain. A highly significant inverse correlation was found to exist between the rates of aggregation of the protein variants under denaturing conditions and their overall net charge. This result indicates that aggregation is generally favored by mutations that bring the net charge of the protein closer to neutrality. In light of this finding, we have analyzed natural mutations associated with familial forms of amyloid diseases that involve alteration of the net charge of the proteins or protein fragments associated with the diseases. Sixteen mutations have been identified for which the mechanism of action that causes the pathological condition is not yet known or fully understood. Remarkably, 14 of these 16 mutations cause the net charge of the corresponding peptide or protein that converts into amyloid deposits to be reduced. This result suggests that charge has been a key parameter in molecular evolution to ensure the avoidance of protein aggregation and identifies reduction of the net charge as an important determinant in at least some forms of protein deposition diseases.

Amyloid-degrading ability of nattokinase from Bacillus subtilis natto.

Science.gov (United States)

Hsu, Ruei-Lin; Lee, Kung-Ta; Wang, Jung-Hao; Lee, Lily Y-L; Chen, Rita P-Y

2009-01-28

More than 20 unrelated proteins can form amyloid fibrils in vivo which are related to various diseases, such as Alzheimer's disease, prion disease, and systematic amyloidosis. Amyloid fibrils are an ordered protein aggregate with a lamellar cross-beta structure. Enhancing amyloid clearance is one of the targets of the therapy of these amyloid-related diseases. Although there is debate on whether the toxicity is due to amyloids or their precursors, research on the degradation of amyloids may help prevent or alleviate these diseases. In this study, we explored the amyloid-degrading ability of nattokinase, a fibrinolytic subtilisin-like serine protease, and determined the optimal conditions for amyloid hydrolysis. This ability is shared by proteinase K and subtilisin Carlsberg, but not by trypsin or plasmin.

Proteomics with Mass Spectrometry Imaging: Beyond Amyloid Typing.

Science.gov (United States)

Lavatelli, Francesca; Merlini, Giampaolo

2018-04-01

Detection and typing of amyloid deposits in tissues are two crucial steps in the management of systemic amyloidoses. The presence of amyloid deposits is routinely evaluated through Congo red staining, whereas proteomics is now a mainstay in the identification of the deposited proteins. In article number 1700236, Winter et al. [Proteomics 2017, 17, Issue 22] describe a novel method based on MALDI-MS imaging coupled to ion mobility separation and peptide filtering, to detect the presence of amyloid in histology samples and to identify its composition, while preserving the spatial distribution of proteins in tissues. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein kinase C involvement in the acetylcholine release reduction induced by amyloid-beta(25-35) aggregates on neuromuscular synapses.

Science.gov (United States)

Tomàs, Marta; Garcia, Neus; Santafé, Manuel M; Lanuza, Maria; Tomàs, Josep

2009-01-01

Using intracellular recording of the diaphragm muscle of adult rats, we have investigated the short-term functional effects of amyloid-beta (Abeta(25-35) peptide aggregates on the modulation of acetylcholine (ACh) release and the involvement of protein kinase C (PKC). The non-aggregated form of this peptide does not change the evoked and spontaneous transmitter release parameters on the neuromuscular synapse. However, the aggregated form of Abeta(25-35) acutely interferes with evoked quantal ACh release (approximately 40% reduction) when synaptic activity in the ex vivo neuromuscular preparation is maintained by low frequency (1 Hz) electrical stimulation. This effect is partially dependent on the activity of PKC that may have a permissive action. The end result of Abeta(25-35) is in opposition to the PKC-dependent maintenance effect on ACh release manifested in active synapses.

Conformational dynamics of amyloid proteins at the aqueous interface

Science.gov (United States)

Armbruster, Matthew; Horst, Nathan; Aoki, Brendy; Malik, Saad; Soto, Patricia

2013-03-01

Amyloid proteins is a class of proteins that exhibit distinct monomeric and oligomeric conformational states hallmark of deleterious neurological diseases for which there are not yet cures. Our goal is to examine the extent of which the aqueous/membrane interface modulates the folding energy landscape of amyloid proteins. To this end, we probe the dynamic conformational ensemble of amyloids (monomer prion protein and Alzheimer's Ab protofilaments) interacting with model bilayers. We will present the results of our coarse grain molecular modeling study in terms of the existence of preferential binding spots of the amyloid to the bilayer and the response of the bilayer to the interaction with the amyloid. NSF Nebraska EPSCoR First Award

Modeling the Aggregation Propensity and Toxicity of Amyloid-β Variants

DEFF Research Database (Denmark)

Tiwari, Manish Kumar; Kepp, Kasper Planeta

2015-01-01

Protein aggregation is a hallmark of many neurodegenerative disorders. Alzheimer’s disease (AD) is directly linked to deposits of amyloid-β (Aβ) derived from the amyloid-β protein precursor (AβPP), and multiple experimental studies have investigated the aggregation behavior of these amyloids...

Alzheimer's disease risk gene CD33 inhibits microglial uptake of amyloid beta.

Science.gov (United States)

Griciuc, Ana; Serrano-Pozo, Alberto; Parrado, Antonio R; Lesinski, Andrea N; Asselin, Caroline N; Mullin, Kristina; Hooli, Basavaraj; Choi, Se Hoon; Hyman, Bradley T; Tanzi, Rudolph E

2013-05-22

The transmembrane protein CD33 is a sialic acid-binding immunoglobulin-like lectin that regulates innate immunity but has no known functions in the brain. We have previously shown that the CD33 gene is a risk factor for Alzheimer's disease (AD). Here, we observed increased expression of CD33 in microglial cells in AD brain. The minor allele of the CD33 SNP rs3865444, which confers protection against AD, was associated with reductions in both CD33 expression and insoluble amyloid beta 42 (Aβ42) levels in AD brain. Furthermore, the numbers of CD33-immunoreactive microglia were positively correlated with insoluble Aβ42 levels and plaque burden in AD brain. CD33 inhibited uptake and clearance of Aβ42 in microglial cell cultures. Finally, brain levels of insoluble Aβ42 as well as amyloid plaque burden were markedly reduced in APP(Swe)/PS1(ΔE9)/CD33(-/-) mice. Therefore, CD33 inactivation mitigates Aβ pathology and CD33 inhibition could represent a novel therapy for AD. Copyright © 2013 Elsevier Inc. All rights reserved.

Mitochondrion-derived reactive oxygen species lead to enhanced amyloid beta formation

NARCIS (Netherlands)

Leuner, K.; Schutt, T.; Kurz, C.; Eckert, S.H.; Schiller, C.; Occhipinti, A.; Mai, S.; Jendrach, M.; Eckert, G.P.; Kruse, S.E.; Palmiter, R.D.; Brandt, U.; Drose, S.; Wittig, I.; Willem, M.; Haass, C.; Reichert, A.S.; Muller, W.E.

2012-01-01

AIMS: Intracellular amyloid beta (Abeta) oligomers and extracellular Abeta plaques are key players in the progression of sporadic Alzheimer's disease (AD). Still, the molecular signals triggering Abeta production are largely unclear. We asked whether mitochondrion-derived reactive oxygen species

Protein Folding and Aggregation into Amyloid: The Interference by Natural Phenolic Compounds

Directory of Open Access Journals (Sweden)

Massimo Stefani

2013-06-01

Full Text Available Amyloid aggregation is a hallmark of several degenerative diseases affecting the brain or peripheral tissues, whose intermediates (oligomers, protofibrils and final mature fibrils display different toxicity. Consequently, compounds counteracting amyloid aggregation have been investigated for their ability (i to stabilize toxic amyloid precursors; (ii to prevent the growth of toxic oligomers or speed that of fibrils; (iii to inhibit fibril growth and deposition; (iv to disassemble preformed fibrils; and (v to favor amyloid clearance. Natural phenols, a wide panel of plant molecules, are one of the most actively investigated categories of potential amyloid inhibitors. They are considered responsible for the beneficial effects of several traditional diets being present in green tea, extra virgin olive oil, red wine, spices, berries and aromatic herbs. Accordingly, it has been proposed that some natural phenols could be exploited to prevent and to treat amyloid diseases, and recent studies have provided significant information on their ability to inhibit peptide/protein aggregation in various ways and to stimulate cell defenses, leading to identify shared or specific mechanisms. In the first part of this review, we will overview the significance and mechanisms of amyloid aggregation and aggregate toxicity; then, we will summarize the recent achievements on protection against amyloid diseases by many natural phenols.

Fetzima (levomilnacipran), a drug for major depressive disorder as a dual inhibitor for human serotonin transporters and beta-site amyloid precursor protein cleaving enzyme-1.

Science.gov (United States)

Rizvi, Syed Mohd Danish; Shaikh, Sibhghatulla; Khan, Mahiuddin; Biswas, Deboshree; Hameed, Nida; Shakil, Shazi

2014-01-01

Pharmacological management of Major Depressive Disorder includes the use of serotonin reuptake inhibitors which targets serotonin transporters (SERT) to increase the synaptic concentrations of serotonin. Beta-site amyloid precursor protein cleaving enzyme-1 (BACE-1) is responsible for amyloid β plaque formation. Hence it is an interesting target for Alzheimer's disease (AD) therapy. This study describes molecular interactions of a new Food and Drug Administration approved antidepressant drug named 'Fetzima' with BACE-1 and SERT. Fetzima is chemically known as levomilnacipran. The study has explored a possible link between the treatment of Depression and AD. 'Autodock 4.2' was used for docking study. The free energy of binding (ΔG) values for 'levomilnacipran-SERT' interaction and 'levomilnacipran-BACE1' interaction were found to be -7.47 and -8.25 kcal/mol, respectively. Levomilnacipran was found to interact with S438, known to be the most important amino acid residue of serotonin binding site of SERT during 'levomilnacipran-SERT' interaction. In the case of 'levomilnacipran-BACE1' interaction, levomilnacipran interacted with two very crucial aspartic acid residues of BACE-1, namely, D32 and D228. These residues are accountable for the cleavage of amyloid precursor protein and the subsequent formation of amyloid β plaques in AD brain. Hence, Fetzima (levomilnacipran) might act as a potent dual inhibitor of SERT and BACE-1 and expected to form the basis of a future dual therapy against depression and AD. It is an established fact that development of AD is associated with Major Depressive Disorder. Therefore, the design of new BACE-1 inhibitors based on antidepressant drug scaffolds would be particularly beneficial.

Astrocytic expression of the Alzheimer's disease beta-secretase (BACE1) is stimulus-dependent

DEFF Research Database (Denmark)

Hartlage-Rübsamen, Maike; Zeitschel, Ulrike; Apelt, Jenny

2003-01-01

The beta-site APP-cleaving enzyme (BACE1) is a prerequisite for the generation of beta-amyloid peptides, which give rise to cerebrovascular and parenchymal beta-amyloid deposits in the brain of Alzheimer's disease patients. BACE1 is neuronally expressed in the brains of humans and experimental...... paradigms studied. In contrast, BACE1 expression by reactive astrocytes was evident in chronic but not in acute models of gliosis. Additionally, we observed BACE1-immunoreactive astrocytes in proximity to beta-amyloid plaques in the brains of aged Tg2576 mice and Alzheimer's disease patients....

Functional Amyloid Formation within Mammalian Tissue.

Directory of Open Access Journals (Sweden)

2005-11-01

Full Text Available Amyloid is a generally insoluble, fibrous cross-beta sheet protein aggregate. The process of amyloidogenesis is associated with a variety of neurodegenerative diseases including Alzheimer, Parkinson, and Huntington disease. We report the discovery of an unprecedented functional mammalian amyloid structure generated by the protein Pmel17. This discovery demonstrates that amyloid is a fundamental nonpathological protein fold utilized by organisms from bacteria to humans. We have found that Pmel17 amyloid templates and accelerates the covalent polymerization of reactive small molecules into melanin-a critically important biopolymer that protects against a broad range of cytotoxic insults including UV and oxidative damage. Pmel17 amyloid also appears to play a role in mitigating the toxicity associated with melanin formation by sequestering and minimizing diffusion of highly reactive, toxic melanin precursors out of the melanosome. Intracellular Pmel17 amyloidogenesis is carefully orchestrated by the secretory pathway, utilizing membrane sequestration and proteolytic steps to protect the cell from amyloid and amyloidogenic intermediates that can be toxic. While functional and pathological amyloid share similar structural features, critical differences in packaging and kinetics of assembly enable the usage of Pmel17 amyloid for normal function. The discovery of native Pmel17 amyloid in mammals provides key insight into the molecular basis of both melanin formation and amyloid pathology, and demonstrates that native amyloid (amyloidin may be an ancient, evolutionarily conserved protein quaternary structure underpinning diverse pathways contributing to normal cell and tissue physiology.

Functional amyloid formation within mammalian tissue.

Directory of Open Access Journals (Sweden)

Douglas M Fowler

2006-01-01

Full Text Available Amyloid is a generally insoluble, fibrous cross-beta sheet protein aggregate. The process of amyloidogenesis is associated with a variety of neurodegenerative diseases including Alzheimer, Parkinson, and Huntington disease. We report the discovery of an unprecedented functional mammalian amyloid structure generated by the protein Pmel17. This discovery demonstrates that amyloid is a fundamental nonpathological protein fold utilized by organisms from bacteria to humans. We have found that Pmel17 amyloid templates and accelerates the covalent polymerization of reactive small molecules into melanin-a critically important biopolymer that protects against a broad range of cytotoxic insults including UV and oxidative damage. Pmel17 amyloid also appears to play a role in mitigating the toxicity associated with melanin formation by sequestering and minimizing diffusion of highly reactive, toxic melanin precursors out of the melanosome. Intracellular Pmel17 amyloidogenesis is carefully orchestrated by the secretory pathway, utilizing membrane sequestration and proteolytic steps to protect the cell from amyloid and amyloidogenic intermediates that can be toxic. While functional and pathological amyloid share similar structural features, critical differences in packaging and kinetics of assembly enable the usage of Pmel17 amyloid for normal function. The discovery of native Pmel17 amyloid in mammals provides key insight into the molecular basis of both melanin formation and amyloid pathology, and demonstrates that native amyloid (amyloidin may be an ancient, evolutionarily conserved protein quaternary structure underpinning diverse pathways contributing to normal cell and tissue physiology.

Interconverting conformations of variants of the human amyloidogenic protein beta2-microglobulin quantitatively characterized by dynamic capillary electrophoresis and computer simulation

DEFF Research Database (Denmark)

Heegaard, Niels H H; Jørgensen, Thomas J D; Cheng, Lei

2006-01-01

Capillary electrophoretic separation profiles of cleaved variants of beta2-microglobulin (beta2m) reflect the conformational equilibria existing in solutions of these proteins. The characterization of these equilibria is of interest since beta2m is responsible for amyloid formation in dialysis-re...

The effects of white matter hyperintensities and amyloid deposition on Alzheimer dementia

Directory of Open Access Journals (Sweden)

Brian A. Gordon

2015-01-01

Conclusions: The amount of amyloid deposition and white matter damage independently predicts cognitive impairment. This suggests a diagnostic utility of qualitative white matter scales in addition to measuring amyloid levels.

Amyloid-β Peptide Induces Prion Protein Amyloid Formation: Evidence for Its Widespread Amyloidogenic Effect.

Science.gov (United States)

Honda, Ryo

2018-04-12

Transmissible spongiform encephalopathy is associated with misfolding of prion protein (PrP) into an amyloid β-rich aggregate. Previous studies have indicated that PrP interacts with Alzheimer's disease amyloid-β peptide (Aβ), but it remains elusive how this interaction impacts on the misfolding of PrP. This study presents the first in vitro evidence that Aβ induces PrP-amyloid formation at submicromolar concentrations. Interestingly, systematic mutagenesis of PrP revealed that Aβ requires no specific amino acid sequences in PrP, and induces the misfolding of other unrelated proteins (insulin and lysozyme) into amyloid fibrils in a manner analogous to PrP. This unanticipated nonspecific amyloidogenic effect of Aβ indicates that this peptide might be involved in widespread protein aggregation, regardless of the amino acid sequences of target proteins, and exacerbate the pathology of many neurodegenerative diseases. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Behavioural problems and personality change related to cerebral amyloid angiopathy].

Science.gov (United States)

Gahr, Maximilian; Connemann, Bernhard J; Schönfeldt-Lecuona, Carlos

2012-11-01

Cerebral amyloid angiopathy (CAA) belongs to the group of amyloidoses that are characterized by the deposition of insoluble and tissue-damaging amyloid proteins. Spontaneous intracerebral hemorrhage is the common clinical presentation of CAA resulting from the degenerative effect of beta amyloid on the cerebral vascular system. Though CAA is rather a neurological disease psychiatric symptoms can occur and even dominate the clinical picture. A case report is presented in order to illustrate the association between CAA and psychiatric symptoms. We report the case of a 54-year-old female patient with radiologic references to a probable CAA and mild cognitive impairment who developed behavioural difficulties and personality change that necessitated a psychiatric treatment. Psychiatric symptoms were most likely due to CAA. CAA can be associated with psychiatric symptoms and hence should be considered in the treatment of elderly patients with behavioural problems or personality changes. Diagnostic neuroimaging and examination of cerebrospinal fluid is recommended. © Georg Thieme Verlag KG Stuttgart · New York.

Multiple Myeloma Presenting as Massive Amyloid Deposition in a Parathyroid Gland Associated with Amyloid Goiter: A Medullary Thyroid Carcinoma Mimic on Intra-operative Frozen Section.

Science.gov (United States)

Hill, Kirk; Diaz, Jason; Hagemann, Ian S; Chernock, Rebecca D

2018-06-01

Clinical examples of amyloid deposition in parathyroid glands are exceedingly rare and usually present as an incidental finding in a patient with amyloid goiter. Here, we present the first histologically documented case of parathyroid amyloid deposition that presented as a mass. The patient did not have hyperparathyroidism. The parathyroid gland was submitted for intra-operative frozen section and concern for medullary thyroid carcinoma was raised. An important histologic clue arguing against medullary thyroid carcinoma was the evenly dispersed nature of the amyloid. Histologic perinuclear clearing and parathyroid hormone immunohistochemistry confirmed parathyroid origin on permanent sections. The patient was also found to have associated amyloid goiter. Mass spectrometry of the amyloid showed it to be composed of kappa light chains. On further work-up, the patient was diagnosed with multiple myeloma. Awareness of parathyroid amyloid deposition is important as it is a histologic mimic of medullary thyroid carcinoma, especially on frozen section. Amyloid typing with evaluation for multiple myeloma in any patient with kappa or lambda light chain restriction is also important.

Differential regulation of amyloid precursor protein sorting with pathological mutations results in a distinct effect on amyloid-β production.

Science.gov (United States)

Lin, Yen-Chen; Wang, Jia-Yi; Wang, Kai-Chen; Liao, Jhih-Ying; Cheng, Irene H

2014-11-01

The deposition of amyloid-β (Aβ) peptide, which is generated from amyloid precursor protein (APP), is the pathological hallmark of Alzheimer's disease (AD). Three APP familial AD mutations (D678H, D678N, and H677R) located at the sixth and seventh amino acid of Aβ have distinct effect on Aβ aggregation, but their influence on the physiological and pathological roles of APP remain unclear. We found that the D678H mutation strongly enhances amyloidogenic cleavage of APP, thus increasing the production of Aβ. This enhancement of amyloidogenic cleavage is likely because of the acceleration of APPD678H sorting into the endosomal-lysosomal pathway. In contrast, the APPD678N and APPH677R mutants do not cause the same effects. Therefore, this study indicates a regulatory role of D678H in APP sorting and processing, and provides genetic evidence for the importance of APP sorting in AD pathogenesis. The internalization of amyloid precursor protein (APP) increases its opportunity to be processed by β-secretase and to produce Amyloid-β (Aβ) that causes Alzheimer's disease (AD). We report a pathogenic APPD678H mutant that enhances APP internalization into the endosomal-lysosomal pathway and thus promotes the β-secretase cleavage and Aβ production. This study provides genetic evidence for the importance of APP sorting in AD pathogenesis. © 2014 International Society for Neurochemistry.

Biofilm inhibitors that target amyloid proteins.

Science.gov (United States)

Romero, Diego; Sanabria-Valentín, Edgardo; Vlamakis, Hera; Kolter, Roberto

2013-01-24

Bacteria establish stable communities, known as biofilms, that are resistant to antimicrobials. Biofilm robustness is due to the presence of an extracellular matrix, which for several species-among them Bacillus subtilis-includes amyloid-like protein fibers. In this work, we show that B. subtilis biofilms can be a simple and reliable tool for screening of molecules with antiamyloid activity. We identified two molecules, AA-861 and parthenolide, which efficiently inhibited biofilms by preventing the formation of amyloid-like fibers. Parthenolide also disrupted pre-established biofilms. These molecules also impeded the formation of biofilms of other bacterial species that secrete amyloid proteins, such as Bacillus cereus and Escherichia coli. Furthermore, the identified molecules decreased the conversion of the yeast protein New1 to the prion state in a heterologous host, indicating the broad range of activity of the molecules. Copyright © 2013 Elsevier Ltd. All rights reserved.

Alzheimer’s Disease Risk Gene CD33 Inhibits Microglial Uptake of Amyloid Beta

Science.gov (United States)

Griciuc, Ana; Serrano-Pozo, Alberto; Parrado, Antonio R.; Lesinski, Andrea N.; Asselin, Caroline N.; Mullin, Kristina; Hooli, Basavaraj; Choi, Se Hoon; Hyman, Bradley T.; Tanzi, Rudolph E.

2013-01-01

SUMMARY The transmembrane protein CD33 is a sialic acid-binding immunoglobulin-like lectin that regulates innate immunity but has no known functions in the brain. We have previously shown that the CD33 gene is a risk factor for Alzheimer’s disease (AD). Here, we observed increased expression of CD33 in microglial cells in AD brain. The minor allele of the CD33 SNP rs3865444, which confers protection against AD, was associated with reductions in both CD33 expression and insoluble amyloid beta 42 (Aβ42) levels in AD brain. Furthermore, the numbers of CD33-immunoreactive microglia were positively correlated with insoluble Aβ42 levels and plaque burden in AD brain. CD33 inhibited uptake and clearance of Aβ42 in microglial cell cultures. Finally, brain levels of insoluble Aβ42 as well as amyloid plaque burden were markedly reduced in APPSwe/PS1ΔE9/CD33−/− mice. Therefore, CD33 inactivation mitigates Aβ pathology and CD33 inhibition could represent a novel therapy for AD. PMID:23623698

The Aggregation Potential of the 1-15-and 1-16-Fragments of the Amyloid beta Peptide and Their Influence on the Aggregation of A beta 40

NARCIS (Netherlands)

Shabestari, M.; Plug, T.; Motazacker, M. M.; Meeuwenoord, N. J.; Filippov, D. V.; Meijers, J. C. M.; Huber, M.

2013-01-01

The aggregation of amyloid beta (A beta) peptide is important in Alzheimer's disease. Shorter A beta fragments may reduce A beta's cytotoxicity and are used in diagnostics. The aggregation of A beta 16 is controversial; Liu et al. (J. Neurosci. Res. 75:162-171, 2004) and Liao et al. (FEBS Lett.

DNA polymerase-beta is expressed early in neurons of Alzheimer's disease brain and is loaded into DNA replication forks in neurons challenged with beta-amyloid

NARCIS (Netherlands)

Copani, Agata; Hoozemans, Jeroen J. M.; Caraci, Filippo; Calafiore, Marco; van Haastert, Elise S.; Veerhuis, Robert; Rozemuller, Annemieke J. M.; Aronica, Eleonora; Sortino, Maria Angela; Nicoletti, Ferdinando

2006-01-01

Cultured neurons exposed to synthetic beta-amyloid (Abeta) fragments reenter the cell cycle and initiate a pathway of DNA replication that involves the repair enzyme DNA polymerase-beta (DNA pol-beta) before undergoing apoptotic death. In this study, by performing coimmunoprecipitation experiments

Adiponectin is protective against oxidative stress induced cytotoxicity in amyloid-beta neurotoxicity.

Directory of Open Access Journals (Sweden)

Koon-Ho Chan

Full Text Available Beta-amyloid (Aβ neurotoxicity is important in Alzheimer's disease (AD pathogenesis. Aβ neurotoxicity causes oxidative stress, inflammation and mitochondrial damage resulting in neuronal degeneration and death. Oxidative stress, inflammation and mitochondrial failure are also pathophysiological mechanisms of type 2 diabetes (T(2DM which is characterized by insulin resistance. Interestingly, T(2DM increases risk to develop AD which is associated with reduced neuronal insulin sensitivity (central insulin resistance. We studied the potential protective effect of adiponectin (an adipokine with insulin-sensitizing, anti-inflammatory and anti-oxidant properties against Aβ neurotoxicity in human neuroblastoma cells (SH-SY5Y transfected with the Swedish amyloid precursor protein (Sw-APP mutant, which overproduced Aβ with abnormal intracellular Aβ accumulation. Cytotoxicity was measured by assay for lactate dehydrogenase (LDH released upon cell death and lysis. Our results revealed that Sw-APP transfected SH-SY5Y cells expressed both adiponectin receptor 1 and 2, and had increased AMP-activated protein kinase (AMPK activation and enhanced nuclear factor-kappa B (NF-κB activation compared to control empty-vector transfected SH-SY5Y cells. Importantly, adiponectin at physiological concentration of 10 µg/ml protected Sw-APP transfected SH-SY5Y cells against cytotoxicity under oxidative stress induced by hydrogen peroxide. This neuroprotective action of adiponectin against Aβ neurotoxicity-induced cytotoxicity under oxidative stress involved 1 AMPK activation mediated via the endosomal adaptor protein APPL1 (adaptor protein with phosphotyrosine binding, pleckstrin homology domains and leucine zipper motif and possibly 2 suppression of NF-κB activation. This raises the possibility of novel therapies for AD such as adiponectin receptor agonists.

[A representative case of joint contracture as a main feature of AL amyloid deposits identified in the skeletal muscles].

Science.gov (United States)

Matsumura, Erika; Yamaguchi, Tetsuto; Tomidokoro, Yasushi; Ishii, Akiko; Tamaoka, Akira

2014-01-01

A 68-year-old man, with a history of type 2 diabetes mellitus and chronic kidney impairment, had been suffering from progressive knee joint contracture and dysesthesia of the lower extremities for 4 years. When he walked, his knees remained bent owing to contracture of the knee joints. There was no evidence of muscle pseudohypertrophy, intramuscular nodules, or muscle weakness. Clinical examination revealed IgA λ M-protein, reticular high-signal intensity lesions demonstrated by magnetic resonance T2-short TI IR(STIR) imaging of the lower extremity muscles, and a mixture of neurogenic and myogenic changes demonstrated by needle electromyography. A biopsy specimen from the vastus lateralis muscle identified Aλ amyloid deposits around the vessels, establishing a diagnosis of amyloid myopathy based on systemic AL amyloidosis. This case demonstrated that joint contracture and reticular lesions shown by magnetic resonance STIR imaging of the muscles can alert the physician to consider muscle biopsy to investigate deposition of amyloid in the skeletal muscles even in the absence of muscle pseudohypertrophy or weakness, both of which are characteristic of amyloid myopathy.

Potential of beta-adrenergic agonists for increasing protein deposition in ruminants in developing countries

International Nuclear Information System (INIS)

Berschauer, F.

1989-01-01

Various substituted phenylethanolamines, acting on the sympathetic nervous system, have been shown to increase protein retention (via decreased proteolysis) and reduce fat deposition (via increased lipolysis and reduced lipogenesis) in ruminants and monogastrics. Research with finishing lambs in developed countries show various beta-adrenergic agonists to improve growth rate (by 18%), feed conversion (by 12%) and carcass quality (28% increase in area of longissimus dorsi and 33% reduction in subcutaneous fat). Similar effects of beta-agonists on carcass composition of well fed cattle have been reported. The effects of beta-agonists on livestock in developing countries of the tropics have not yet been investigated, but their effects in increasing metabolic rate suggest that treated ruminants would be more vulnerable to hot environments. Beta-agonists appear to improve nitrogen retention to a greater extent in breeds with a lower potential for muscle growth. In view of this, they might be particularly effective in improving nitrogen retention in tropical breeds which have a low growth potential. This aspect, together with the response of undernourished animals in the developing countries, needs investigation. Beta-adrenergic agonists are not yet registered for use in animal production, but product licenses for some of them are expected to be granted soon. (author). 31 refs, 1 fig., 12 tabs

Comparison of the binding characteristics of [{sup 18}F]THK-523 and other amyloid imaging tracers to Alzheimer's disease pathology

Energy Technology Data Exchange (ETDEWEB)

Harada, Ryuichi; Okamura, Nobuyuki; Yoshikawa, Takeo; Yanai, Kazuhiko [Tohoku University School of Medicine, Department of Pharmacology, Sendai (Japan); Furumoto, Shozo [Tohoku University School of Medicine, Department of Pharmacology, Sendai (Japan); Tohoku University, Division of Radiopharmaceutical Chemistry, Cyclotron and Radioisotope Center, Sendai (Japan); Tago, Tetsuro; Iwata, Ren [Tohoku University, Division of Radiopharmaceutical Chemistry, Cyclotron and Radioisotope Center, Sendai (Japan); Maruyama, Masahiro; Higuchi, Makoto [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Arai, Hiroyuki [Tohoku University, Department of Geriatrics and Gerontology, Institute of Development, Aging and Cancer, Sendai (Japan); Kudo, Yukitsuka [Tohoku University, Innovation of New Biomedical Engineering Center, Sendai (Japan)

2013-01-15

Extensive deposition of senile plaques and neurofibrillary tangles in the brain is a pathological hallmark of Alzheimer's disease (AD). Although several PET imaging agents have been developed for in vivo detection of senile plaques, no PET probe is currently available for selective detection of neurofibrillary tangles in the living human brain. Recently, [{sup 18}F]THK-523 was developed as a potential in vivo imaging probe for tau pathology. The purpose of this study was to compare the binding properties of [{sup 18}F]THK-523 and other amyloid imaging agents, including PiB, BF-227 and FDDNP, to synthetic protein fibrils and human brain tissue. In vitro radioligand binding assays were conducted using synthetic amyloid {beta}{sub 42} and K18{Delta}K280-tau fibrils. Nonspecific binding was determined by the addition of unlabelled compounds at a concentration of 2 {mu}M. To examine radioligand binding to neuropathological lesions, in vitro autoradiography was conducted using sections of AD brain. [{sup 18}F]THK-523 showed higher affinity for tau fibrils than for A{beta} fibrils, whereas the other probes showed a higher affinity for A{beta} fibrils. The autoradiographic analysis indicated that [{sup 18}F]THK-523 accumulated in the regions containing a high density of tau protein deposits. Conversely, PiB and BF-227 accumulated in the regions containing a high density of A{beta} plaques. These findings suggest that the unique binding profile of [{sup 18}F]THK-523 can be used to identify tau deposits in AD brain. (orig.)

Synovial deposition of wild-type transthyretin-derived amyloid in knee joint osteoarthritis patients.

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Takanashi, Tetsuo; Matsuda, Masayuki; Yazaki, Masahide; Yamazaki, Hideshi; Nawata, Masashi; Katagiri, Yoshiki; Ikeda, Shu-Ichi

2013-09-01

To investigate histological features of deposited amyloid in the synovial tissue and its clinical significance in knee joint osteoarthritis (OA) patients. We prospectively enrolled 232 consecutive patients who underwent arthroplasty or total replacement of the knee joint for treatment of OA. Congo red staining and immunohistochemistry were performed in the synovial tissue obtained at surgery. When transthyretin (TTR)-derived amyloid was positive, we analyzed all 4 exons of the TTR gene using the direct DNA sequencing method in order to detect mutations. We analyzed 322 specimens in this study. Twenty-six specimens (8.1%) obtained from 21 patients (5 men and 16 women; mean, 79.0 ± 4.6 years) showed deposition of amyloid, which was positively stained with the anti-TTR antibody. Eighteen patients showed inhomogeneous accumulations of amyloid in the loose connective tissue under the synovial epithelia sometimes with nodule formation, while in the remaining three, small vessels in the adipose tissue were involved. Medical records of these patients revealed nothing remarkable in the clinical course, laboratory data or macroscopic intraarticular findings at surgery. No mutations were detectable in the TTR gene analysis. Wild-type TTR-derived amyloid may affect the synovial tissue as a result of long-term mechanical stress or as a part of senile systemic amyloidosis in approximately 8% of knee joint OA patients. No obvious clinical significance was found in synovial deposition of amyloid.

2A4 binds soluble and insoluble light chain aggregates from AL amyloidosis patients and promotes clearance of amyloid deposits by phagocytosis †.

Science.gov (United States)

Renz, Mark; Torres, Ronald; Dolan, Philip J; Tam, Stephen J; Tapia, Jose R; Li, Lauri; Salmans, Joshua R; Barbour, Robin M; Shughrue, Paul J; Nijjar, Tarlochan; Schenk, Dale; Kinney, Gene G; Zago, Wagner

2016-09-01

Amyloid light chain (AL) amyloidosis is characterized by misfolded light chain (LC) (amyloid) deposition in various peripheral organs, leading to progressive dysfunction and death. There are no regulatory agency-approved treatments for AL amyloidosis, and none of the available standard of care approaches directly targets the LC protein that constitutes the amyloid. NEOD001, currently in late-stage clinical trials, is a conformation-specific, anti-LC antibody designed to specifically target misfolded LC aggregates and promote phagocytic clearance of AL amyloid deposits. The present study demonstrated that the monoclonal antibody 2A4, the murine form of NEOD001, binds to patient-derived soluble and insoluble LC aggregates and induces phagocytic clearance of AL amyloid in vitro. 2A4 specifically labeled all 21 fresh-frozen organ samples studied, which were derived from 10 patients representing both κ and λ LC amyloidosis subtypes. 2A4 immunoreactivity largely overlapped with thioflavin T-positive labeling, and 2A4 bound both soluble and insoluble LC aggregates extracted from patient tissue. Finally, 2A4 induced macrophage engagement and phagocytic clearance of AL amyloid deposits in vitro. These findings provide further evidence that 2A4/NEOD001 can effectively clear and remove human AL-amyloid from tissue and further support the rationale for the evaluation of NEOD001 in patients with AL amyloidosis.

2A4 binds soluble and insoluble light chain aggregates from AL amyloidosis patients and promotes clearance of amyloid deposits by phagocytosis †

Science.gov (United States)

Renz, Mark; Torres, Ronald; Dolan, Philip J.; Tam, Stephen J.; Tapia, Jose R.; Li, Lauri; Salmans, Joshua R.; Barbour, Robin M.; Shughrue, Paul J.; Nijjar, Tarlochan; Schenk, Dale; Kinney, Gene G.; Zago, Wagner

2016-01-01

Abstract Amyloid light chain (AL) amyloidosis is characterized by misfolded light chain (LC) (amyloid) deposition in various peripheral organs, leading to progressive dysfunction and death. There are no regulatory agency–approved treatments for AL amyloidosis, and none of the available standard of care approaches directly targets the LC protein that constitutes the amyloid. NEOD001, currently in late-stage clinical trials, is a conformation-specific, anti-LC antibody designed to specifically target misfolded LC aggregates and promote phagocytic clearance of AL amyloid deposits. The present study demonstrated that the monoclonal antibody 2A4, the murine form of NEOD001, binds to patient-derived soluble and insoluble LC aggregates and induces phagocytic clearance of AL amyloid in vitro. 2A4 specifically labeled all 21 fresh-frozen organ samples studied, which were derived from 10 patients representing both κ and λ LC amyloidosis subtypes. 2A4 immunoreactivity largely overlapped with thioflavin T–positive labeling, and 2A4 bound both soluble and insoluble LC aggregates extracted from patient tissue. Finally, 2A4 induced macrophage engagement and phagocytic clearance of AL amyloid deposits in vitro. These findings provide further evidence that 2A4/NEOD001 can effectively clear and remove human AL-amyloid from tissue and further support the rationale for the evaluation of NEOD001 in patients with AL amyloidosis. PMID:27494229

The proton-pump inhibitor lansoprazole enhances amyloid beta production.

Science.gov (United States)

Badiola, Nahuai; Alcalde, Victor; Pujol, Albert; Münter, Lisa-Marie; Multhaup, Gerd; Lleó, Alberto; Coma, Mireia; Soler-López, Montserrat; Aloy, Patrick

2013-01-01

A key event in the pathogenesis of Alzheimer's disease (AD) is the accumulation of amyloid-β (Aβ) species in the brain, derived from the sequential cleavage of the amyloid precursor protein (APP) by β- and γ-secretases. Based on a systems biology study to repurpose drugs for AD, we explore the effect of lansoprazole, and other proton-pump inhibitors (PPIs), on Aβ production in AD cellular and animal models. We found that lansoprazole enhances Aβ37, Aβ40 and Aβ42 production and lowers Aβ38 levels on amyloid cell models. Interestingly, acute lansoprazole treatment in wild type and AD transgenic mice promoted higher Aβ40 levels in brain, indicating that lansoprazole may also exacerbate Aβ production in vivo. Overall, our data presents for the first time that PPIs can affect amyloid metabolism, both in vitro and in vivo.

Antagonizing beta-amyloid peptide neurotoxicity of the anti-aging fungus Ganoderma lucidum.

Science.gov (United States)

Lai, Cora Sau-Wan; Yu, Man-Shan; Yuen, Wai-Hung; So, Kwok-Fai; Zee, Sze-Yong; Chang, Raymond Chuen-Chung

2008-01-23

Ganoderma lucidum (Leyss. ex Fr.) Karst. (Lingzhi) is a medicinal fungus used clinically in many Asian countries to promote health and longevity. Synaptic degeneration is another key mode of neurodegeneration in Alzheimer's disease (AD). Recent studies have shown the loss of synaptic density proteins in each individual neuron during the progression of AD. It was recently reported that beta-amyloid (Abeta) could cause synaptic dysfunction and contribute to AD pathology. In this study, we reported that aqueous extract of G. lucidum significantly attenuated Abeta-induced synaptotoxicity by preserving the synaptic density protein, synaptophysin. In addition, G. lucidum aqueous extract antagonized Abeta-triggered DEVD cleavage activities in a dose-dependent manner. Further studies elucidated that phosphorylation of c-Jun N-terminal kinase, c-Jun, and p38 MAP kinase was attenuated by G. lucidum in Abeta-stressed neurons. Taken together, the results prove a hypothesis that anti-aging G. lucidum can prevent harmful effects of the exterminating toxin Abeta in AD.

Reduced amyloidogenic processing of the amyloid beta-protein precursor by the small-molecule Differentiation Inducing Factor-1.

Science.gov (United States)

Myre, Michael A; Washicosky, Kevin; Moir, Robert D; Tesco, Giuseppina; Tanzi, Rudolph E; Wasco, Wilma

2009-04-01

The detection of cell cycle proteins in Alzheimer's disease (AD) brains may represent an early event leading to neurodegeneration. To identify cell cycle modifiers with anti-Abeta properties, we assessed the effect of Differentiation-Inducing Factor-1 (DIF-1), a unique, small-molecule from Dictyostelium discoideum, on the proteolysis of the amyloid beta-protein precursor (APP) in a variety of different cell types. We show that DIF-1 slows cell cycle progression through G0/G1 that correlates with a reduction in cyclin D1 protein levels. Western blot analysis of DIF-treated cells and conditioned medium revealed decreases in the levels of secreted APP, mature APP, and C-terminal fragments. Assessment of conditioned media by sandwich ELISA showed reduced levels of Abeta40 and Abeta42, also demonstrating that treatment with DIF-1 effectively decreases the ratio of Abeta42 to Abeta40. In addition, DIF-1 significantly diminished APP phosphorylation at residue T668. Interestingly, site-directed mutagenesis of APP residue Thr668 to alanine or glutamic acid abolished the effect of DIF-1 on APP proteolysis and restored secreted levels of Abeta. Finally, DIF-1 prevented the accumulation of APP C-terminal fragments induced by the proteasome inhibitor lactacystin, and calpain inhibitor N-acetyl-leucyl-leucyl-norleucinal (ALLN). Our findings suggest that DIF-1 affects G0/G1-associated amyloidogenic processing of APP by a gamma-secretase-, proteasome- and calpain-insensitive pathway, and that this effect requires the presence of residue Thr668.

Short-term effects of beta-amyloid25-35 peptide aggregates on transmitter release in neuromuscular synapses.

Science.gov (United States)

Garcia, Neus; Santafé, Manel M; Tomàs, Marta; Lanuza, Maria A; Tomàs, Josep

2008-03-01

The beta-amyloid (AB) peptide25-35 contains the functional domain of the AB precursor protein that is both required for neurotrophic effects in normal neural tissues and is involved in the neurotoxic effects in Alzheimer disease. We demonstrated the presence of the amyloid precursor protein/AB peptide in intramuscular axons, presynaptic motor nerve terminals, terminal and myelinating Schwann cells, and the postsynaptic and subsarcolemmal region in the Levator auris longus muscle of adult rats by immunocytochemistry. Using intracellular recording, we investigated possible short-term functional effects of the AB fragment (0.1-10 micromol/L) on acetylcholine release in adult and newborn motor end plates. We found no change in evoked, spontaneous transmitter release or resting membrane potential of the muscle cells. A previous block of the presynaptic muscarinic receptor subtypes and a previous block or stimulation of protein kinase C revealed no masked effect of the peptide on the regulation of transmitter release. The aggregated form of AB peptide25-35, however, interfered acutely with acetylcholine release (quantal content reduction) when synaptic activity was maintained by electric stimulation. The possible relevance of this inhibition of neurotransmission by AB peptide25-35 to the pathogenesis of Alzheimer remains to be determined.

Amyloid protein unfolding and insertion kinetics on neuronal membrane mimics

Science.gov (United States)

Qiu, Liming; Buie, Creighton; Vaughn, Mark; Cheng, Kwan

2010-03-01

Atomistic details of beta-amyloid (Aβ ) protein unfolding and lipid interaction kinetics mediated by the neuronal membrane surface are important for developing new therapeutic strategies to prevent and cure Alzheimer's disease. Using all-atom MD simulations, we explored the early unfolding and insertion kinetics of 40 and 42 residue long Aβ in binary lipid mixtures with and without cholesterol that mimic the cholesterol-depleted and cholesterol-enriched lipid nanodomains of neurons. The protein conformational transition kinetics was evaluated from the secondary structure profile versus simulation time plot. The extent of membrane disruption was examined by the calculated order parameters of lipid acyl chains and cholesterol fused rings as well as the density profiles of water and lipid headgroups at defined regions across the lipid bilayer from our simulations. Our results revealed that both the cholesterol content and the length of the protein affect the protein-insertion and membrane stability in our model lipid bilayer systems.

Interaction between amyloid beta peptide and an aggregation blocker peptide mimicking islet amyloid polypeptide.

Directory of Open Access Journals (Sweden)

Nasrollah Rezaei-Ghaleh

Full Text Available Assembly of amyloid-beta peptide (Aβ into cytotoxic oligomeric and fibrillar aggregates is believed to be a major pathologic event in Alzheimer's disease (AD and interfering with Aβ aggregation is an important strategy in the development of novel therapeutic approaches. Prior studies have shown that the double N-methylated analogue of islet amyloid polypeptide (IAPP IAPP-GI, which is a conformationally constrained IAPP analogue mimicking a non-amyloidogenic IAPP conformation, is capable of blocking cytotoxic self-assembly of Aβ. Here we investigate the interaction of IAPP-GI with Aβ40 and Aβ42 using NMR spectroscopy. The most pronounced NMR chemical shift changes were observed for residues 13-20, while residues 7-9, 15-16 as well as the C-terminal half of Aβ--that is both regions of the Aβ sequence that are converted into β-strands in amyloid fibrils--were less accessible to solvent in the presence of IAPP-GI. At the same time, interaction of IAPP-GI with Aβ resulted in a concentration-dependent co-aggregation of Aβ and IAPP-GI that was enhanced for the more aggregation prone Aβ42 peptide. On the basis of the reduced toxicity of the Aβ peptide in the presence of IAPP-GI, our data are consistent with the suggestion that IAPP-GI redirects Aβ into nontoxic "off-pathway" aggregates.

A carrier for non-covalent delivery of functional beta-galactosidase and antibodies against amyloid plaques and IgM to the brain.

Directory of Open Access Journals (Sweden)

Gobinda Sarkar

Full Text Available BACKGROUND: Therapeutic intervention of numerous brain-associated disorders currently remains unrealized due to serious limitations imposed by the blood-brain-barrier (BBB. The BBB generally allows transport of small molecules, typically <600 daltons with high octanol/water partition coefficients, but denies passage to most larger molecules. However, some receptors present on the BBB allow passage of cognate proteins to the brain. Utilizing such receptor-ligand systems, several investigators have developed methods for delivering proteins to the brain, a critical requirement of which involves covalent linking of the target protein to a carrier entity. Such covalent modifications involve extensive preparative and post-preparative chemistry that poses daunting limitations in the context of delivery to any organ. Here, we report creation of a 36-amino acid peptide transporter, which can transport a protein to the brain after routine intravenous injection of the transporter-protein mixture. No covalent linkage of the protein with the transporter is necessary. APPROACH: A peptide transporter comprising sixteen lysine residues and 20 amino acids corresponding to the LDLR-binding domain of apolipoprotein E (ApoE was synthesized. Transport of beta-galactosidase, IgG, IgM, and antibodies against amyloid plques to the brain upon iv injection of the protein-transporter mixture was evaluated through staining for enzyme activity or micro single photon emission tomography (micro-SPECT or immunostaining. Effect of the transporter on the integrity of the BBB was also investigated. PRINCIPAL FINDINGS: The transporter enabled delivery to the mouse brain of functional beta-galactosidase, human IgG and IgM, and two antibodies that labeled brain-associated amyloid beta plaques in a mouse model of Alzheimer's disease. SIGNIFICANCE: The results suggest the transporter is able to transport most or all proteins to the brain without the need for chemically linking the

α-Synuclein Amyloids Hijack Prion Protein to Gain Cell Entry, Facilitate Cell-to-Cell Spreading and Block Prion Replication.

Science.gov (United States)

Aulić, Suzana; Masperone, Lara; Narkiewicz, Joanna; Isopi, Elisa; Bistaffa, Edoardo; Ambrosetti, Elena; Pastore, Beatrice; De Cecco, Elena; Scaini, Denis; Zago, Paola; Moda, Fabio; Tagliavini, Fabrizio; Legname, Giuseppe

2017-08-30

The precise molecular mechanism of how misfolded α-synuclein (α-Syn) accumulates and spreads in synucleinopathies is still unknown. Here, we show the role of the cellular prion protein (PrP C ) in mediating the uptake and the spread of recombinant α-Syn amyloids. The in vitro data revealed that the presence of PrP C fosters the higher uptake of α-Syn amyloid fibrils, which was also confirmed in vivo in wild type (Prnp +/+ ) compared to PrP knock-out (Prnp -/- ) mice. Additionally, the presence of α-Syn amyloids blocked the replication of scrapie prions (PrP Sc ) in vitro and ex vivo, indicating a link between the two proteins. Indeed, whilst PrP C is mediating the internalization of α-Syn amyloids, PrP Sc is not able to replicate in their presence. This observation has pathological relevance, since several reported case studies show that the accumulation of α-Syn amyloid deposits in Creutzfeldt-Jakob disease patients is accompanied by a longer disease course.

Reducing the Levels of Akt Activation by PDK1 Knock-in Mutation Protects Neuronal Cultures against Synthetic Amyloid-Beta Peptides

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Shaobin Yang

2018-01-01

Full Text Available The Akt kinase has been widely assumed for years as a key downstream effector of the PI3K signaling pathway in promoting neuronal survival. This notion was however challenged by the finding that neuronal survival responses were still preserved in mice with reduced Akt activity. Moreover, here we show that the Akt signaling is elevated in the aged brain of two different mice models of Alzheimer Disease. We manipulate the rate of Akt stimulation by employing knock-in mice expressing a mutant form of PDK1 (phosphoinositide-dependent protein kinase 1 with reduced, but not abolished, ability to activate Akt. We found increased membrane localization and activity of the TACE/ADAM17 α-secretase in the brain of the PDK1 mutant mice with concomitant TNFR1 processing, which provided neurons with resistance against TNFα-induced neurotoxicity. Opposite to the Alzheimer Disease transgenic mice, the PDK1 knock-in mice exhibited an age-dependent attenuation of the unfolding protein response, which protected the mutant neurons against endoplasmic reticulum stressors. Moreover, these two mechanisms cooperatively provide the mutant neurons with resistance against amyloid-beta oligomers, and might singularly also contribute to protect these mice against amyloid-beta pathology.

Amyloid beta inhibits olfactory bulb activity and the ability to smell.

Directory of Open Access Journals (Sweden)

Reynaldo Alvarado-Martínez

Full Text Available Early olfactory dysfunction has been consistently reported in both Alzheimer's disease (AD and in transgenic mice that reproduce some features of this disease. In AD transgenic mice, alteration in olfaction has been associated with increased levels of soluble amyloid beta protein (Aβ as well as with alterations in the oscillatory network activity recorded in the olfactory bulb (OB and in the piriform cortex. However, since AD is a multifactorial disease and transgenic mice suffer a variety of adaptive changes, it is still unknown if soluble Aβ, by itself, is responsible for OB dysfunction both at electrophysiological and behavioral levels. Thus, here we tested whether or not Aβ directly affects OB network activity in vitro in slices obtained from mice and rats and if it affects olfactory ability in these rodents. Our results show that Aβ decreases, in a concentration- and time-dependent manner, the network activity of OB slices at clinically relevant concentrations (low nM and in a reversible manner. Moreover, we found that intrabulbar injection of Aβ decreases the olfactory ability of rodents two weeks after application, an effect that is not related to alterations in motor performance or motivation to seek food and that correlates with the presence of Aβ deposits. Our results indicate that Aβ disrupts, at clinically relevant concentrations, the network activity of the OB in vitro and can trigger a disruption in olfaction. These findings open the possibility of exploring the cellular mechanisms involved in early pathological AD as an approach to reduce or halt its progress.

Caspase activation increases beta-amyloid generation independently of caspase cleavage of the beta-amyloid precursor protein (APP).

Science.gov (United States)

Tesco, Giuseppina; Koh, Young Ho; Tanzi, Rudolph E

2003-11-14

The amyloid precursor protein (APP) undergoes "alternative" proteolysis mediated by caspases. Three major caspase recognition sites have been identified in the APP, i.e. one at the C terminus (Asp720) and two at the N terminus (Asp197 and Asp219). Caspase cleavage at Asp720 has been suggested as leading to increased production of Abeta. Thus, we set out to determine which putative caspase sites in APP, if any, are cleaved in Chinese hamster ovary cell lines concurrently with the increased Abeta production that occurs during apoptosis. We found that cleavage at Asp720 occurred concurrently with caspase 3 activation and the increased production of total secreted Abeta and Abeta1-42 in association with staurosporine- and etoposide-induced apoptosis. To investigate the contribution of caspase cleavage of APP to Abeta generation, we expressed an APP mutant truncated at Asp720 that mimics APP caspase cleavage at the C-terminal site. This did not increase Abeta generation but, in contrast, dramatically decreased Abeta production in Chinese hamster ovary cells. Furthermore, the ablation of caspase-dependent cleavage at Asp720, Asp197, and Asp219 (by site-directed mutagenesis) did not prevent enhanced Abeta production following etoposide-induced apoptosis. These findings indicate that the enhanced Abeta generation associated with apoptosis does not require cleavage of APP at its C-terminal (Asp720) and/or N-terminal caspase sites.

Cerebrospinal Fluid Amyloid Beta and Tau Concentrations Are Not Modulated by 16 Weeks of Moderate- to High-Intensity Physical Exercise in Patients with Alzheimer Disease

DEFF Research Database (Denmark)

Steen Jensen, Camilla; Portelius, Erik; Siersma, Volkert

2016-01-01

BACKGROUND: Physical exercise may have some effect on cognition in patients with Alzheimer disease (AD). However, the underlying biochemical effects are unclear. Animal studies have shown that amyloid beta (Aβ), one of the pathological hallmarks of AD, can be altered with high levels of physical...... of Life, Physical Health and Functional Ability in Alzheimer's Disease: The Effect of Physical Exercise (ADEX) study we analyzed cerebrospinal fluid samples for Aβ species, total tau (t-tau), phosphorylated tau (p-tau) and soluble amyloid precursor protein (sAPP) species. We also assessed the patients...

[Clinical Laboratory Test Using Proteomics: The Usefulness of Proteomic Techniques for Amyloid Typing].

Science.gov (United States)

Tasaki, Masayoshi; Obayashi, Konen; Ando, Yukio

2015-08-01

Amyloidosis is a heterogeneous group of disorders characterized by the deposition of amyloid fibrils. To diagnose amyloidosis, it is important to detect amyloid deposits and identify the amyloid precursor protein in specimens, such as tissues and serum. Mass spectrometry is a powerful tool to measure the molecular weight and identify the protein. Recently, mass spectrometries such as liquid chromatography/tandem mass spectrometry and surface-enhanced laser desorption/ionization time of flight mass spectrometry, have made a contribution to amyloid typing. In the paper, we describe the usefulness of mass spectrometric analyses for the typing of amyloidosis.

Intracellular trafficking of the β-secretase and processing of amyloid precursor protein.

Science.gov (United States)

Zhi, Pei; Chia, Pei Zhi Cheryl; Chia, Cheryl; Gleeson, Paul A

2011-09-01

The main component of the amyloid plaques found in the brains of those with Alzheimer's disease (AD) is a polymerized form of the β-amyloid peptide (Aβ) and is considered to play a central role in the pathogenesis of this neurodegenerative disorder. Aβ is derived from the proteolytic processing of the amyloid precursor protein (APP). Beta site APP-cleaving enzyme, BACE1 (also known as β-secretase) is a membrane-bound aspartyl protease responsible for the initial step in the generation of Aβ peptide and is thus a prime target for therapeutic intervention. Substantive evidence now indicates that the processing of APP by BACE1 is regulated by the intracellular sorting of the enzyme and, moreover, perturbations in these intracellular trafficking pathways have been linked to late-onset AD. In this review, we highlight the recent advances in the understanding of the regulation of the intracellular sorting of BACE1 and APP and illustrate why the trafficking of these cargos represent a key issue for understanding the membrane-mediated events associated with the generation of the neurotoxic Aβ products in AD. Copyright © 2011 International Union of Biochemistry and Molecular Biology, Inc.

A single amino acid difference between the intracellular domains of amyloid precursor protein and amyloid-like precursor protein 2 enables induction of synaptic depression and block of long-term potentiation.

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Trillaud-Doppia, Emilie; Paradis-Isler, Nicolas; Boehm, Jannic

2016-07-01

Alzheimer disease (AD) is initially characterized as a disease of the synapse that affects synaptic transmission and synaptic plasticity. While amyloid-beta and tau have been traditionally implicated in causing AD, recent studies suggest that other factors, such as the intracellular domain of the amyloid-precursor protein (APP-ICD), can also play a role in the development of AD. Here, we show that the expression of APP-ICD induces synaptic depression, while the intracellular domain of its homolog amyloid-like precursor protein 2 (APLP2-ICD) does not. We are able to show that this effect by APP-ICD is due to a single alanine vs. proline difference between APP-ICD and APLP2-ICD. The alanine in APP-ICD and the proline in APLP2-ICD lie directly behind a conserved caspase cleavage site. Inhibition of caspase cleavage of APP-ICD prevents the induction of synaptic depression. Finally, we show that the expression of APP-ICD increases and facilitates long-term depression and blocks induction of long-term potentiation. The block in long-term potentiation can be overcome by mutating the aforementioned alanine in APP-ICD to the proline of APLP2. Based on our results, we propose the emergence of a new APP critical domain for the regulation of synaptic plasticity and in consequence for the development of AD. Copyright © 2016 Elsevier Inc. All rights reserved.

Detection of Alzheimer's amyloid beta aggregation by capturing molecular trails of individual assemblies

International Nuclear Information System (INIS)

Vestergaard, Mun'delanji; Hamada, Tsutomu; Saito, Masato; Yajima, Yoshifumi; Kudou, Monotori; Tamiya, Eiichi; Takagi, Masahiro

2008-01-01

Assembly of Amyloid beta (Aβ) peptides, in particular Aβ-42 is central to the formation of the amyloid plaques associated with neuro-pathologies such as Alzheimer's disease (AD). Molecular assembly of individual Aβ-42 species was observed using a simple fluorescence microscope. From the molecular movements (aka Brownian motion) of the individual peptide assemblies, we calculated a temporal evolution of the hydrodynamic radius (R H ) of the peptide at physiological temperature and pH. The results clearly show a direct relationship between R H of Aβ-42 and incubation period, corresponding to the previously reported peptide's aggregation kinetics. The data correlates highly with in solution-based label-free electrochemical detection of the peptide's aggregation, and Aβ-42 deposited on a solid surface and analysed using atomic force microscopy (AFM). To the best of our knowledge, this is the first analysis and characterisation of Aβ aggregation based on capturing molecular trails of individual assemblies. The technique enables both real-time observation and a semi-quantitative distribution profile of the various stages of Aβ assembly, at microM peptide concentration. Our method is a promising candidate for real-time observation and analysis of the effect of other pathologically-relevant molecules such as metal ions on pathways to Aβ oligomerisation and aggregation. The method is also a promising screening tool for AD therapeutics that target Aβ assembly.

Induction of complement proteins in a mouse model for cerebral microvascular Aβ deposition

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DeFilippis Kelly

2007-09-01

Full Text Available Abstract The deposition of amyloid β-protein (Aβ in cerebral vasculature, known as cerebral amyloid angiopathy (CAA, is a common pathological feature of Alzheimer's disease and related disorders. In familial forms of CAA single mutations in the Aβ peptide have been linked to the increase of vascular Aβ deposits accompanied by a strong localized activation of glial cells and elevated expression of neuroinflammatory mediators including complement proteins. We have developed human amyloid-β precursor protein transgenic mice harboring two CAA Aβ mutations (Dutch E693Q and Iowa D694N that mimic the prevalent cerebral microvascular Aβ deposition observed in those patients, and the Swedish mutations (K670N/M671L to increase Aβ production. In these Tg-SwDI mice, we have reported predominant fibrillar Aβ along microvessels in the thalamic region and diffuse plaques in cortical region. Concurrently, activated microglia and reactive astrocytes have been detected primarily in association with fibrillar cerebral microvascular Aβ in this model. Here we show that three native complement components in classical and alternative complement pathways, C1q, C3, and C4, are elevated in Tg-SwDI mice in regions rich in fibrillar microvascular Aβ. Immunohistochemical staining of all three proteins was increased in thalamus, hippocampus, and subiculum, but not frontal cortex. Western blot analysis showed significant increases of all three proteins in the thalamic region (with hippocampus as well as the cortical region, except C3 that was below detection level in cortex. Also, in the thalamic region (with hippocampus, C1q and C3 mRNAs were significantly up-regulated. These complement proteins appeared to be expressed largely by activated microglial cells associated with the fibrillar microvascular Aβ deposits. Our findings demonstrate that Tg-SwDI mice exhibit elevated complement protein expression in response to fibrillar vascular Aβ deposition that is

AL amyloid imaging and therapy with a monoclonal antibody to a cryptic epitope on amyloid fibrils.

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Jonathan S Wall

Full Text Available The monoclonal antibody 2A4 binds an epitope derived from a cleavage site of serum amyloid protein A (sAA containing a -Glu-Asp- amino acid pairing. In addition to its reactivity with sAA amyloid deposits, the antibody was also found to bind amyloid fibrils composed of immunoglobulin light chains. The antibody binds to synthetic fibrils and human light chain (AL amyloid extracts with high affinity even in the presence of soluble light chain proteins. Immunohistochemistry with biotinylated 2A4 demonstrated positive reaction with ALκ and ALλ human amyloid deposits in various organs. Surface plasmon resonance analyses using synthetic AL fibrils as a substrate revealed that 2A4 bound with a K(D of ∼10 nM. Binding was inhibited in the presence of the -Glu-Asp- containing immunogen peptide. Radiolabeled 2A4 specifically localized with human AL amyloid extracts implanted in mice (amyloidomas as evidenced by single photon emission (SPECT imaging. Furthermore, co-localization of the radiolabeled mAb with amyloid was shown in biodistribution and micro-autoradiography studies. Treatment with 2A4 expedited regression of ALκ amyloidomas in mice, likely mediated by the action of macrophages and neutrophils, relative to animals that received a control antibody. These data indicate that the 2A4 mAb might be of interest for potential imaging and immunotherapy in patients with AL amyloidosis.

Indirubin-3′-monoxime suppresses amyloid-beta-induced apoptosis by inhibiting tau hyperphosphorylation

Institute of Scientific and Technical Information of China (English)

Shu-gang Zhang; Xiao-shan Wang; Ying-dong Zhang; Qing Di; Jing-ping Shi; Min Qian; Li-gang Xu; Xing-jian Lin; Jie Lu

2016-01-01

Indirubin-3′-monoxime is an effective inhibitor of cyclin-dependent protein kinases, and may play an obligate role in neuronal apopto-sis in Alzheimer’s disease. Here, we found that indirubin-3′-monoxime improved the morphology and increased the survival rate of SH-SY5Y cells exposed to amyloid-beta 25–35 (Aβ25–35), and also suppressed apoptosis by reducing tau phosphorylation at Ser199 and Thr205. Furthermore, indirubin-3′-monoxime inhibited phosphorylation of glycogen synthase kinase-3β (GSK-3β). Our results suggest that in-dirubin-3′-monoxime reduced Aβ25–35-induced apoptosis by suppressing tau hyperphosphorylationvia a GSK-3β-mediated mechanism. Indirubin-3′-monoxime is a promising drug candidate for Alzheimer’s disease.

A Peptide-Fc Opsonin with Pan-Amyloid Reactivity

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James S. Foster

2017-09-01

Full Text Available There is a continuing need for therapeutic interventions for patients with the protein misfolding disorders that result in systemic amyloidosis. Recently, specific antibodies have been employed to treat AL amyloidosis by opsonizing tissue amyloid deposits thereby inducing cell-mediated dissolution and organ improvement. To develop a pan-amyloid therapeutic agent, we have produced an Fc-fusion product incorporating a peptide, p5, which binds many if not all forms of amyloid. This protein, designated Fcp5, expressed in mammalian cells, forms the desired bivalent dimer structure and retains pan-amyloid reactivity similar to the p5 peptide as measured by immunosorbent assays, immunohistochemistry, surface plasmon resonance, and pulldown assays using radioiodinated Fcp5. Additionally, Fcp5 was capable of opsonizing amyloid fibrils in vitro using a pH-sensitive fluorescence assay of phagocytosis. In mice,125 I-labeled Fcp5 exhibited an extended serum circulation time, relative to the p5 peptide. It specifically bound AA amyloid deposits in diseased mice, as evidenced by biodistribution and microautoradiographic methods, which coincided with an increase in active, Iba-1-positive macrophages in the liver at 48 h postinjection of Fcp5. In healthy mice, no specific tissue accumulation was observed. The data indicate that polybasic, pan-amyloid-targeting peptides, in the context of an Fc fusion, can yield amyloid reactive, opsonizing reagents that may serve as next-generation immunotherapeutics.

Amyloid and immune homeostasis.

Science.gov (United States)

Wang, Ying-Hui; Zhang, Yu-Gen

2018-03-01

Extracellular amyloid deposition defines a range of amyloidosis and amyloid-related disease. Addition to primary and secondary amyloidosis, amyloid-related disease can be observed in different tissue/organ that sharing the common pathogenesis based on the formation of amyloid deposition. Currently, both Alzheimer's disease and type 2 diabetes can be diagnosed with certainly only based on the autopsy results, by which amyloidosis of the associative tissue/organ is observed. Intriguingly, since it demonstrated that amyloid deposits trigger inflammatory reaction through the activation of cascaded immune response, wherein several lines of evidence implies a protective role of amyloid in preventing autoimmunity. Furthermore, attempts for preventing amyloid formation and/or removing amyloid deposits from the brain have caused meningoencephalitis and consequent deaths among the subjects. Hence, it is important to note that amyloid positively participates in maintaining immune homeostasis and contributes to irreversible inflammatory response. In this review, we will focus on the interactive relationship between amyloid and the immune system, discussing the potential functional roles of amyloid in immune tolerance and homeostasis. Copyright © 2017 Elsevier GmbH. All rights reserved.

Increased KPI containing amyloid precursor protein in experimental autoimmune encephalomyelitis brains.

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Beilin, Orit; Karussis, Dimitrios M; Korczyn, Amos D; Gurwitz, David; Aronovich, Ramona; Mizrachi-Kol, Rachel; Chapman, Joab

2007-04-16

Amyloid precursor protein can be translated from three alternatively spliced mRNAs. We measured levels of amyloid precursor protein isoforms containing the Kunitz protease inhibitor domain (KPIAPP), and amyloid precursor protein without the Kunitz protease inhibitor domain (KPIAPP) in brain homogenates of acute experimental autoimmune encephalomyelitis mice. At the preclinical phase of the disease, both KPIAPP and KPIAPP levels were significantly higher in homogenates from brains of autoimmune encephalomyelitis mice, whereas at the acute phase of the disease only KPIAPP remained significantly elevated compared with controls. At the recovery phase, no differences were observed between the groups. The early and isoform-specific elevation of KPIAPP in autoimmune encephalomyelitis mice suggests a possible role for amyloid precursor protein in the immune response mediating the disease.

Vitamin D receptor is present on the neuronal plasma membrane and is co-localized with amyloid precursor protein, ADAM10 or Nicastrin.

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Dursun, Erdinç; Gezen-Ak, Duygu

2017-01-01

Our recent study indicated that vitamin D and its receptors are important parts of the amyloid processing pathway in neurons. Yet the role of vitamin D receptor (VDR) in amyloid pathogenesis is complex and all regulations over the production of amyloid beta cannot be explained solely with the transcriptional regulatory properties of VDR. Given that we hypothesized that VDR might exist on the neuronal plasma membrane in close proximity with amyloid precursor protein (APP) and secretase complexes. The present study primarily focused on the localization of VDR in neurons and its interaction with amyloid pathology-related proteins. The localization of VDR on neuronal membranes and its co-localization with target proteins were investigated with cell surface staining followed by immunofluorescence labelling. The FpClass was used for protein-protein interaction prediction. Our results demonstrated the localization of VDR on the neuronal plasma membrane and the co-localization of VDR and APP or ADAM10 or Nicastrin and limited co-localization of VDR and PS1. E-cadherin interaction with APP or the γ-secretase complex may involve NOTCH1, NUMB, or FHL2, according to FpClass. This suggested complex might also include VDR, which greatly contributes to Ca+2 hemostasis with its ligand vitamin D. Consequently, we suggested that VDR might be a member of this complex also with its own non-genomic action and that it can regulate the APP processing pathway in this way in neurons.

Selective inhibition of phosphodiesterases 4, 5 and 9 induces HSP20 phosphorylation and attenuates amyloid beta 1-42 mediated cytotoxicity

OpenAIRE

Cameron, Ryan T.; Whiteley, Ellanor; Day, Jon P.; Parachikova, Anna I.; Baillie, George S.

2017-01-01

Phosphodiesterase (PDE) inhibitors are currently under evaluation as agents that may facilitate the improvement of cognitive impairment associated with Alzheimer's disease. Our aim was to determine whether inhibitors of PDEs 4, 5 and 9 could alleviate the cytotoxic effects of amyloid beta 1?42 (A?1?42) via a mechanism involving the small heatshock protein HSP20. We show that inhibition of PDEs 4, 5 and 9 but not 3 induces the phosphorylation of HSP20 which, in turn, increases the colocalisati...

Pittsburgh Compound B and AV-1451 positron emission tomography assessment of molecular pathologies of Alzheimer's disease in progressive supranuclear palsy.

Science.gov (United States)

Whitwell, Jennifer L; Ahlskog, J Eric; Tosakulwong, Nirubol; Senjem, Matthew L; Spychalla, Anthony J; Petersen, Ronald C; Jack, Clifford R; Lowe, Val J; Josephs, Keith A

2018-03-01

Little is known about Alzheimer's disease molecular proteins, beta-amyloid and paired helical filament (PHF) tau, in progressive supranuclear palsy (PSP). Recent techniques have been developed to allow for investigations of these proteins in PSP. We determined the frequency of beta-amyloid deposition in PSP, and whether beta-amyloid deposition in PSP is associated with PHF-tau deposition pattern, or clinical features. Thirty probable PSP participants underwent MRI, [ 18 F]AV-1451 PET and Pittsburgh compound B (PiB) PET. Apolipoprotein (APOE) genotyping was also performed. A global PiB standard-uptake value ratio (SUVR) was calculated. AV-1451 SUVRs were calculated for a set of Alzheimer's disease (AD)-related regions and a set of PSP-related regions. Voxel-level analyses were conducted to assess for differences in AV-1451 uptake patterns and MRI atrophy between PiB(+) and PiB(-) cases compared to 60 normal PiB(-) controls. Statistical testing for correlations and associations between variables of interest were also performed. Twelve subjects (40%) showed beta-amyloid deposition. Higher PiB SUVR correlated with older age but not with AV-1451 SUVR in the AD- or PSP-related regions. Higher AV-1451 SUVR in AD-related regions was associated with higher AV-1451 SUVR in PSP-related regions. We found little evidence for beta-amyloid related differences in clinical metrics, proportion of APOE e4 carriers, pattern of AV-1451 uptake, or pattern of atrophy. Beta-amyloid deposition occurs in a relatively high proportion of PSP subjects. Unlike in Alzheimer's disease, however, there is little evidence that beta-amyloid, and PHF-tau, play a significant role in neurodegeneration in PSP. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cerebral amyloid angiopathy, blood-brain barrier disruption and amyloid accumulation in SAMP8 mice.

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del Valle, Jaume; Duran-Vilaregut, Joaquim; Manich, Gemma; Pallàs, Mercè; Camins, Antoni; Vilaplana, Jordi; Pelegrí, Carme

2011-01-01

Cerebrovascular dysfunction and β-amyloid peptide deposition on the walls of cerebral blood vessels might be an early event in the development of Alzheimer's disease. Here we studied the time course of amyloid deposition in blood vessels and blood-brain barrier (BBB) disruption in the CA1 subzone of the hippocampus of SAMP8 mice and the association between these two variables. We also studied the association between the amyloid deposition in blood vessels and the recently described amyloid clusters in the parenchyma, as well as the association of these clusters with vessels in which the BBB is disrupted. SAMP8 mice showed greater amyloid deposition in blood vessels than age-matched ICR-CD1 control mice. Moreover, at 12 months of age the number of vessels with a disrupted BBB had increased in both strains, especially SAMP8 animals. At this age, all the vessels with amyloid deposition showed BBB disruption, but several capillaries with an altered BBB showed no amyloid on their walls. Moreover, amyloid clusters showed no spatial association with vessels with amyloid deposition, nor with vessels in which the BBB had been disrupted. Finally, we can conclude that vascular amyloid deposition seems to induce BBB alterations, but BBB disruption may also be due to other factors. Copyright © 2011 S. Karger AG, Basel.

Differential recruitment efficacy of patient-derived amyloidogenic and myeloma light chain proteins by synthetic fibrils-A metric for predicting amyloid propensity.

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Emily B Martin

Full Text Available Monoclonal free light chain (LC proteins are present in the circulation of patients with immunoproliferative disorders such as light chain (AL amyloidosis and multiple myeloma (MM. Light chain-associated amyloid is a complex pathology composed of proteinaceous fibrils and extracellular matrix proteins found in all patients with AL and in ~10-30% of patients who presented with MM. Amyloid deposits systemically in multiple organs and tissues leading to dysfunction and ultimately death. The overall survival of patients with amyloidosis is worse than for those with early stage MM.We have developed a sensitive binding assay quantifying the recruitment of full length, patient-derived LC proteins by synthetic amyloid fibrils, as a method for studying their amyloidogenic potential. In a survey of eight urinary LC, both AL and MM-associated proteins were recruited by synthetic amyloid fibrils; however, AL-associated LC bound significantly more efficiently (p < 0.05 than did MM LCs. The LC proteins used in this study were isolated from urine and presumed to represent a surrogate of serum free light chains.The binding of LC to synthetic fibrils in this assay accurately differentiated LC with amyloidogenic propensity from MM LC that were not associated with clinical amyloid disease. Notably, the LC from a MM patient who subsequently developed amyloid behaved as an AL-associated protein in the assay, indicating the possibility for identifying MM patients at risk for developing amyloidosis based on the light chain recruitment efficacy. With this information, at risk patients can be monitored more closely for the development of amyloidosis, allowing timely administration of novel, amyloid-directed immunotherapies-this approach may improve the prognosis for these patients.

Radioiodinated benzimidazole derivatives as single photon emission computed tomography probes for imaging of {beta}-amyloid plaques in Alzheimer's disease

Energy Technology Data Exchange (ETDEWEB)

Cui Mengchao [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875 (China); Ono, Masahiro, E-mail: ono@pharm.kyoto-u.ac.j [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Kimura, Hiroyuki; Kawashima, Hidekazu [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Liu Boli [Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875 (China); Saji, Hideo, E-mail: hsaji@pharm.kyoto-u.ac.j [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan)

2011-04-15

Five iodinated 2-phenyl-1H-benzo[d]imidazole derivatives were synthesized and evaluated as potential probes for {beta}-amyloid (A{beta}) plaques. One of the compounds, 4-(6-iodo-1H-benzo[d]imidazol-2-yl)-N,N-dimethylaniline (12), showed excellent affinity for A{beta}{sub 1-42} aggregates (K{sub i}=9.8 nM). Autoradiography with sections of postmortem Alzheimer's disease (AD) brain revealed that a radioiodinated probe [{sup 125}I]12, labeled A{beta} plaques selectively with low nonspecific binding. Biodistribution experiments with normal mice injected intravenously with [{sup 125}I]12 showed high uptake [4.14 percent injected dose per gram (% ID/g) at 2 min] into and rapid clearance (0.15% ID/g at 60 min) from the brain, which may bring about a good signal-to-noise ratio and therefore achieve highly sensitive detection of A{beta} plaques. In addition, [{sup 125}I]12 labeled amyloid plaques in vivo in an AD transgenic model. The preliminary results strongly suggest that [{sup 125}I]12 bears characteristics suitable for detecting amyloid plaques in vivo. When labeled with {sup 123}I, it may be a useful SPECT imaging agent for A{beta} plaques in the brain of living AD patients.

Complement activation by the amyloid proteins A beta peptide and beta 2-microglobulin

DEFF Research Database (Denmark)

Nybo, Mads; Nielsen, E H; Svehag, S E

1999-01-01

component nor heparan sulfate did significantly alter the A beta-induced CA. The results indicate that not only fibrillar A beta but also oligomers of, in particular, beta 2M from patients with dialysis-associated amyloidosis are capable of inducing CA at supra-physiological concentrations....

Unfolded protein response and activated degradative pathways regulation in GNE myopathy.

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Honghao Li

Full Text Available Although intracellular beta amyloid (Aβ accumulation is known as an early upstream event in the degenerative course of UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE myopathy, the process by which Aβdeposits initiate various degradative pathways, and their relationship have not been fully clarified. We studied the possible secondary responses after amyloid beta precursor protein (AβPP deposition including unfolded protein response (UPR, ubiquitin proteasome system (UPS activation and its correlation with autophagy system. Eight GNE myopathy patients and five individuals with normal muscle morphology were included in this study. We performed immunofluorescence and immunoblotting to investigate the expression of AβPP, phosphorylated tau (p-tau and endoplasmic reticulum molecular chaperones. Proteasome activities were measured by cleavage of fluorogenic substrates. The expression of proteasome subunits and linkers between proteasomal and autophagy systems were also evaluated by immunoblotting and relative quantitative real-time RT-PCR. Four molecular chaperones, glucose-regulated protein 94 (GRP94, glucose-regulated protein 78 (GRP78, calreticulin and calnexin and valosin containing protein (VCP were highly expressed in GNE myopathy. 20S proteasome subunits, three main proteasome proteolytic activities, and the factors linking UPS and autophagy system were also increased. Our study suggests that AβPP deposition results in endoplasmic reticulum stress (ERS and highly expressed VCP deliver unfolded proteins from endoplasmic reticulum to proteosomal system which is activated in endoplasmic reticulum associated degradation (ERAD in GNE myopathy. Excessive ubiquitinated unfolded proteins are exported by proteins that connect UPS and autophagy to autophagy system, which is activated as an alternative pathway for degradation.

Beta-amyloid deposition and cognitive function in patients with major depressive disorder with different subtypes of mild cognitive impairment: 18F-florbetapir (AV-45/Amyvid) PET study

International Nuclear Information System (INIS)

Wu, Kuan-Yi; Liu, Chia-Yih; Chen, Chia-Hsiang; Lee, Chin-Pang; Chen, Cheng-Sheng; Hsiao, Ing-Tsung; Hsieh, Chia-Ju; Yen, Tzu-Chen; Lin, Kun-Ju

2016-01-01

The objective of this study was to evaluate the amyloid burden, as assessed by 18 F-florbetapir (AV-45/Amyvid) positron emission tomography PET, in patients with major depressive disorder (MDD) with different subtypes of mild cognitive impairment (MCI) and the relationship between amyloid burden and cognition in MDD patients. The study included 55 MDD patients without dementia and 21 healthy control subjects (HCs) who were assessed using a comprehensive cognitive test battery and 18 F-florbetapir PET imaging. The standardized uptake value ratios (SUVR) in eight cortical regions using the whole cerebellum as reference region were determined and voxel-wise comparisons between the HC and MDD groups were performed. Vascular risk factors, serum homocysteine level and the apolipoprotein E (ApoE) genotype were also determined. Among the 55 MDD patients, 22 (40.0 %) had MCI, 12 (21.8 %) non-amnestic MCI (naMCI) and 10 (18.2 %) amnestic MCI (aMCI). The MDD patients with aMCI had the highest relative 18 F-florbetapir uptake in all cortical regions, and a significant difference in relative 18 F-florbetapir uptake was found in the parietal region as compared with that in naMCI subjects (P < 0.05) and HCs (P < 0.01). Voxel-wise analyses revealed significantly increased relative 18 F-florbetapir uptake in the MDD patients with aMCI and naMCI in the frontal, parietal, temporal and occipital areas (P < 0.005). The global cortical SUVR was significantly negatively correlated with MMSE score (r = -0.342, P = 0.010) and memory function (r = -0.328, P = 0.015). The negative correlation between the global SUVR and memory in the MDD patients remained significant in multiple regression analyses that included age, educational level, ApoE genotype, and depression severity (β = -3.607, t = -2.874, P = 0.006). We found preliminary evidence of brain beta-amyloid deposition in MDD patients with different subtypes of MCI. Our findings in MDD patients support the hypothesis that a higher

Cationization increases brain distribution of an amyloid-beta protofibril selective F(ab')2 fragment

OpenAIRE

Syvänen, Stina; Edén, Desireé; Sehlin, Dag

2017-01-01

Antibodies and fragments thereof are, because of high selectivity for their targets, considered as potential therapeutics and biomarkers for several neurological disorders. However, due to their large molecular size, antibodies/fragments do not easily penetrate into the brain. The aim of the present study was to improve the brain distribution via adsorptive-mediated transcytosis of an amyloid-beta (A beta) protofibril selective F(ab')2 fragment (F(ab')2-h158). F(ab')2-h158 was cationized to d...

Numb endocytic adapter proteins regulate the transport and processing of the amyloid precursor protein in an isoform-dependent manner: implications for Alzheimer disease pathogenesis.

Science.gov (United States)

Kyriazis, George A; Wei, Zelan; Vandermey, Miriam; Jo, Dong-Gyu; Xin, Ouyang; Mattson, Mark P; Chan, Sic L

2008-09-12

Central to the pathogenesis of Alzheimer disease is the aberrant processing of the amyloid precursor protein (APP) to generate amyloid beta-peptide (Abeta), the principle component of amyloid plaques. The cell fate determinant Numb is a phosphotyrosine binding domain (PTB)-containing endocytic adapter protein that interacts with the carboxyl-terminal domain of APP. The physiological relevance of this interaction is unknown. Mammals produce four alternatively spliced variants of Numb that differ in the length of their PTB and proline-rich region. In the current study, we determined the influence of the four human Numb isoforms on the intracellular trafficking and processing of APP. Stable expression of Numb isoforms that differ in the PTB but not in the proline-rich region results in marked differences in the sorting of APP to the recycling and degradative pathways. Neural cells expressing Numb isoforms that lack the insert in the PTB (short PTB (SPTB)) exhibited marked accumulation of APP in Rab5A-labeled early endosomal and recycling compartments, whereas those expressing isoforms with the insertion in the PTB (long PTB (LPTB)) exhibited reduced amounts of cellular APP and its proteolytic derivatives relative to parental control cells. Neither the activities of the beta- and gamma-secretases nor the expression of APP mRNA were significantly different in the stably transfected cells, suggesting that the differential effects of the Numb proteins on APP metabolism is likely to be secondary to altered APP trafficking. In addition, the expression of SPTB-Numb increases at the expense of LPTB-Numb in neuronal cultures subjected to stress, suggesting a role for Numb in stress-induced Abeta production. Taken together, these results suggest distinct roles for the human Numb isoforms in APP metabolism and may provide a novel potential link between altered Numb isoform expression and increased Abeta generation.

Amyloid-beta binds catalase with high affinity and inhibits hydrogen peroxide breakdown.

OpenAIRE

Milton, N G

1999-01-01

Amyloid-beta (Abeta) specifically bound purified catalase with high affinity and inhibited catalase breakdown of H(2)O(2). The Abeta-induced catalase inhibition involved formation of the inactive catalase Compound II and was reversible. CatalaseAbeta interactions provide rapid functional assays for the cytotoxic domain of Abeta and suggest a mechanism for some of the observed actions of Abeta plus catalase in vitro.

Down's Syndrome with Alzheimer's Disease-Like Pathology: What Can It Teach Us about the Amyloid Cascade Hypothesis?

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Rania M. Bakkar

2010-01-01

Full Text Available Down's syndrome (DS, trisomy 21 represents a complex genetic abnormality that leads to pathology in later life that is similar to Alzheimer's disease (AD. We compared two cases of DS with APOE 3/3 genotypes, a similar age at death, and comparable amyloid-beta 42 peptide (A42 burdens in the brain but that differed markedly in the severity of AD-like pathology. One exhibited extensive neurofibrillary pathology whereas the other showed minimal features of this type. Comparable loads of A42 could relate to the cases' similar life-time accumulation of A due to trisomy 21-enhanced metabolism of amyloid precursor protein (APP. The cases' significant difference in AD-like pathology, however, suggests that parenchymal deposition of A42, even when extensive, may not inevitably trigger AD-like tau pathology (though it may be necessary. Thus, these observations of a natural experiment may contribute to understanding the nuances of the amyloid cascade hypothesis of AD pathogenesis.

Bloodstream Amyloid-beta (1-40) Peptide, Cognition, and Outcomes in Heart Failure.

Science.gov (United States)

Bayes-Genis, Antoni; Barallat, Jaume; de Antonio, Marta; Domingo, Mar; Zamora, Elisabet; Vila, Joan; Subirana, Isaac; Gastelurrutia, Paloma; Pastor, M Cruz; Januzzi, James L; Lupón, Josep

2017-11-01

In the brain, amyloid-beta generation participates in the pathophysiology of cognitive disorders; in the bloodstream, the role of amyloid-beta is uncertain but may be linked to sterile inflammation and senescence. We explored the relationship between blood levels of amyloid-beta 1-40 peptide (Aβ40), cognition, and mortality (all-cause, cardiovascular, and heart failure [HF]-related) in ambulatory patients with HF. Bloodstream Aβ40 was measured in 939 consecutive patients with HF. Cognition was evaluated with the Pfeiffer questionnaire (adjusted for educational level) at baseline and during follow-up. Multivariate Cox regression analyses and measurements of performance (discrimination, calibration, and reclassification) were used, with competing risk for specific causes of death. Over 5.1 ± 2.9 years, 471 patients died (all-cause): 250 from cardiovascular causes and 131 HF-related. The median Aβ40 concentration was 519.1 pg/mL [Q1-Q3: 361.8-749.9 pg/mL]. The Aβ40 concentration correlated with age, body mass index, renal dysfunction, and New York Heart Association functional class (all P < .001). There were no differences in Aβ40 in patients with and without cognitive impairment at baseline (P = .97) or during follow-up (P = .20). In multivariable analysis, including relevant clinical predictors and N-terminal pro-B-type natriuretic peptide, Aβ40 remained significantly associated with all-cause death (HR, 1.22; 95%CI, 1.10-1.35; P < .001) and cardiovascular death (HR, 1.18; 95%CI, 1.03-1.36; P = .02), but not with HF-related death (HR, 1.13; 95%CI, 0.93-1.37; P = .22). Circulating Aβ40 improved calibration and patient reclassification. Blood levels of Aβ40 are not associated with cognitive decline in HF. Circulating Aβ40 was predictive of mortality and may indicate systemic aging. Copyright © 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

Schisandrin B protects PC12 cells by decreasing the expression of amyloid precursor protein and vacuolar protein sorting 35★

Science.gov (United States)

Yan, Mingmin; Mao, Shanping; Dong, Huimin; Liu, Baohui; Zhang, Qian; Pan, Gaofeng; Fu, Zhiping

2012-01-01

PC12 cell injury was induced using 20 μM amyloid β-protein 25–35 to establish a model of Alzheimer's disease. The cells were then treated with 5, 10, and 25 μM Schisandrin B. Methylthiazolyldiphenyl-tetrazolium bromide assays and Hoechst 33342 staining results showed that with increasing Schisandrin B concentration, the survival rate of PC12 cells injured by amyloid β-protein 25–35 gradually increased and the rate of apoptosis gradually decreased. Reverse transcription-PCR, immunocytochemical staining and western blot results showed that with increasing Schisandrin B concentration, the mRNA and protein expression of vacuolar protein sorting 35 and amyloid precursor protein were gradually decreased. Vacuolar protein sorting 35 and amyloid precursor protein showed a consistent trend for change. These findings suggest that 5, 10, and 25 μM Schisandrin B antagonizes the cellular injury induced by amyloid β-protein 25–35 in a dose-dependent manner. This may be caused by decreasing the expression of vacuolar protein sorting 35 and amyloid precursor protein. PMID:25745458

AMYPdb: A database dedicated to amyloid precursor proteins

Directory of Open Access Journals (Sweden)

Delamarche Christian

2008-06-01

Full Text Available Abstract Background Misfolding and aggregation of proteins into ordered fibrillar structures is associated with a number of severe pathologies, including Alzheimer's disease, prion diseases, and type II diabetes. The rapid accumulation of knowledge about the sequences and structures of these proteins allows using of in silico methods to investigate the molecular mechanisms of their abnormal conformational changes and assembly. However, such an approach requires the collection of accurate data, which are inconveniently dispersed among several generalist databases. Results We therefore created a free online knowledge database (AMYPdb dedicated to amyloid precursor proteins and we have performed large scale sequence analysis of the included data. Currently, AMYPdb integrates data on 31 families, including 1,705 proteins from nearly 600 organisms. It displays links to more than 2,300 bibliographic references and 1,200 3D-structures. A Wiki system is available to insert data into the database, providing a sharing and collaboration environment. We generated and analyzed 3,621 amino acid sequence patterns, reporting highly specific patterns for each amyloid family, along with patterns likely to be involved in protein misfolding and aggregation. Conclusion AMYPdb is a comprehensive online database aiming at the centralization of bioinformatic data regarding all amyloid proteins and their precursors. Our sequence pattern discovery and analysis approach unveiled protein regions of significant interest. AMYPdb is freely accessible 1.

Ubiquilin 1 modulates amyloid precursor protein trafficking and Abeta secretion.

Science.gov (United States)

Hiltunen, Mikko; Lu, Alice; Thomas, Anne V; Romano, Donna M; Kim, Minji; Jones, Phill B; Xie, Zhongcong; Kounnas, Maria Z; Wagner, Steven L; Berezovska, Oksana; Hyman, Bradley T; Tesco, Giuseppina; Bertram, Lars; Tanzi, Rudolph E

2006-10-27

Ubiquilin 1 (UBQLN1) is a ubiquitin-like protein, which has been shown to play a central role in regulating the proteasomal degradation of various proteins, including the presenilins. We recently reported that DNA variants in UBQLN1 increase the risk for Alzheimer disease, by influencing expression of this gene in brain. Here we present the first assessment of the effects of UBQLN1 on the metabolism of the amyloid precursor protein (APP). For this purpose, we employed RNA interference to down-regulate UBQLN1 in a variety of neuronal and non-neuronal cell lines. We demonstrate that down-regulation of UBQLN1 accelerates the maturation and intracellular trafficking of APP, while not interfering with alpha-, beta-, or gamma-secretase levels or activity. UBQLN1 knockdown increased the ratio of APP mature/immature, increased levels of full-length APP on the cell surface, and enhanced the secretion of sAPP (alpha- and beta-forms). Moreover, UBQLN1 knockdown increased levels of secreted Abeta40 and Abeta42. Finally, employing a fluorescence resonance energy transfer-based assay, we show that UBQLN1 and APP come into close proximity in intact cells, independently of the presence of the presenilins. Collectively, our findings suggest that UBQLN1 may normally serve as a cytoplasmic "gatekeeper" that may control APP trafficking from intracellular compartments to the cell surface. These findings suggest that changes in UBQLN1 steady-state levels affect APP trafficking and processing, thereby influencing the generation of Abeta.

An X11alpha/FSBP complex represses transcription of the GSK3beta gene promoter.

LENUS (Irish Health Repository)

Lau, Kwok-Fai

2010-08-04

X11alpha is a neuronal adaptor protein that interacts with the amyloid precursor protein (APP) through a centrally located phosphotyrosine binding domain to inhibit the production of Abeta peptide that is deposited in Alzheimer\\'s disease brains. X11alpha also contains two C-terminal postsynaptic density-95, large discs, zona occludens 1 (PDZ) domains, and we show here that through its PDZ domains, X11alpha interacts with a novel transcription factor, fibrinogen silencer binding protein. Moreover, we show that an X11alpha\\/fibrinogen silencer binding protein complex signals to the nucleus to repress glycogen synthase kinase-3beta promoter activity. Glycogen synthase kinase-3beta is a favoured candidate kinase for phosphorylating tau in Alzheimer\\'s disease. Our findings show a new function for X11alpha that may impact on Alzheimer\\'s disease pathogenesis.

Soluble beta-amyloid precursor protein is related to disease progression in amyotrophic lateral sclerosis.

Directory of Open Access Journals (Sweden)

Petra Steinacker

Full Text Available BACKGROUND: Biomarkers of disease progression in amyotrophic lateral sclerosis (ALS could support the identification of beneficial drugs in clinical trials. We aimed to test whether soluble fragments of beta-amyloid precursor protein (sAPPα and sAPPß correlated with clinical subtypes of ALS and were of prognostic value. METHODOLOGY/PRINCIPAL FINDINGS: In a cross-sectional study including patients with ALS (N = 68 with clinical follow-up data over 6 months, Parkinson's disease (PD, N = 20, and age-matched controls (N = 40, cerebrospinal fluid (CSF levels of sAPPα a, sAPPß and neurofilaments (NfH(SMI35 were measured by multiplex assay, Progranulin by ELISA. CSF sAPPα and sAPPß levels were lower in ALS with a rapidly-progressive disease course (p = 0.03, and p = 0.02 and with longer disease duration (p = 0.01 and p = 0.01, respectively. CSF NfH(SMI35 was elevated in ALS compared to PD and controls, with highest concentrations found in patients with rapid disease progression (p<0.01. High CSF NfH(SMI3 was linked to low CSF sAPPα and sAPPß (p = 0.001, and p = 0.007, respectively. The ratios CSF NfH(SMI35/CSF sAPPα,-ß were elevated in patients with fast progression of disease (p = 0.002 each. CSF Progranulin decreased with ongoing disease (p = 0.04. CONCLUSIONS: This study provides new CSF candidate markers associated with progression of disease in ALS. The data suggest that a deficiency of cellular neuroprotective mechanisms (decrease of sAPP is linked to progressive neuro-axonal damage (increase of NfH(SMI35 and to progression of disease.

Chirality and chiroptical properties of amyloid fibrils.

Science.gov (United States)

Dzwolak, Wojciech

2014-09-01

Chirality of amyloid fibrils-linear beta-sheet-rich aggregates of misfolded protein chains-often manifests in morphological traits such as helical twist visible in atomic force microscopy and in chiroptical properties accessible to vibrational circular dichroism (VCD). According to recent studies the relationship between molecular chirality of polypeptide building blocks and superstructural chirality of amyloid fibrils may be more intricate and less deterministic than previously assumed. Several puzzling experimental findings have put into question earlier intuitive ideas on: 1) the bottom-up chirality transfer upon amyloidogenic self-assembly, and 2) the structural origins of chiroptical properties of protein aggregates. For example, removal of a single amino acid residue from an amyloidogenic all-L peptide was shown to reverse handedness of fibrils. On the other hand, certain types of amyloid aggregates revealed surprisingly strong VCD spectra with the sign and shape dependent on the conditions of fibrillation. Hence, microscopic and chiroptical studies have highlighted chirality as one more aspect of polymorphism of amyloid fibrils. This brief review is intended to outline the current state of research on amyloid-like fibrils from the perspective of their structural and superstructural chirality and chiroptical properties. © 2014 Wiley Periodicals, Inc.

Low background and high contrast PET imaging of amyloid-{beta} with [{sup 11}C]AZD2995 and [{sup 11}C]AZD2184 in Alzheimer's disease patients

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Forsberg, Anton; Andersson, Jan; Varnaes, Katarina; Halldin, Christer [Karolinska Institutet, Centre for Psychiatry Research, Department of Clinical Neuroscience, Stockholm (Sweden); Jureus, Anders; Swahn, Britt-Marie; Sandell, Johan; Julin, Per; Svensson, Samuel [AstraZeneca Research and Development, Neuroscience Research and Therapy Area, Soedertaelje (Sweden); Cselenyi, Zsolt; Schou, Magnus; Johnstroem, Peter; Farde, Lars [Karolinska Institutet, Centre for Psychiatry Research, Department of Clinical Neuroscience, Stockholm (Sweden); Karolinska Hospital, AstraZeneca Translational Sciences Centre, PET CoE, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm (Sweden); Eriksdotter, Maria; Freund-Levi, Yvonne [Karolinska Institutet, Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Stockholm (Sweden); Karolinska University Hospital, Department of Geriatric Medicine, Stockholm (Sweden); Jeppsson, Fredrik [AstraZeneca Research and Development, Neuroscience Research and Therapy Area, Soedertaelje (Sweden); Karolinska Institutet, Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Stockholm (Sweden)

2013-04-15

The aim of this study was to evaluate AZD2995 side by side with AZD2184 as novel PET radioligands for imaging of amyloid-{beta} in Alzheimer's disease (AD). In vitro binding of tritium-labelled AZD2995 and AZD2184 was studied and compared with that of the established amyloid-{beta} PET radioligand PIB. Subsequently, a first-in-human in vivo PET study was performed using [{sup 11}C]AZD2995 and [{sup 11}C]AZD2184 in three healthy control subjects and seven AD patients. AZD2995, AZD2184 and PIB were found to share the same binding site to amyloid-{beta}. [{sup 3}H]AZD2995 had the highest signal-to-background ratio in brain tissue from patients with AD as well as in transgenic mice. However, [{sup 11}C]AZD2184 had superior imaging properties in PET, as shown by larger effect sizes comparing binding potential values in cortical regions of AD patients and healthy controls. Nevertheless, probably due to a lower amount of nonspecific binding, the group separation of the distribution volume ratio values of [{sup 11}C]AZD2995 was greater in areas with lower amyloid-{beta} load, e.g. the hippocampus. Both AZD2995 and AZD2184 detect amyloid-{beta} with high affinity and specificity and also display a lower degree of nonspecific binding than that reported for PIB. Overall [{sup 11}C]AZD2184 seems to be an amyloid-{beta} radioligand with higher uptake and better group separation when compared to [{sup 11}C]AZD2995. However, the very low nonspecific binding of [{sup 11}C]AZD2995 makes this radioligand potentially interesting as a tool to study minute levels of amyloid-{beta}. This sensitivity may be important in investigating, for example, early prodromal stages of AD or in the longitudinal study of a disease modifying therapy. (orig.)

A beta2-microglobulin cleavage variant fibrillates at near-physiological pH

DEFF Research Database (Denmark)

Corlin, Dorthe B; Johnsen, Christina K; Nissen, Mogens H

2009-01-01

Beta2-microglobulin (beta2m) deposits as amyloid in dialysis-related amyloidosis (DRA), predominantly in joints. The molecular mechanisms underlying the amyloidogenicity of beta2m are still largely unknown. In vitro, acidic conditions, pH ... several days. Here, we show that amyloid fibrils are generated in less than an hour when a cleavage variant of beta2m--found in the circulation of many dialysis patients--is exposed to pH levels (pH 6.6) occurring in joints during inflammation. Aggregation and fibrillation, including seeding effects...... with intact, native beta2m were studied by Thioflavin T fluorescence spectroscopy, turbidimetry, capillary electrophoresis, and electron microscopy. We conclude that a biologically relevant variant of beta2m is amyloidogenic at slightly acidic pH. Also, only a very small amount of preformed fibrils...

Amyloid-beta transporter expression at the blood-CSF barrier is age-dependent

Directory of Open Access Journals (Sweden)

Pascale Crissey L

2011-07-01

Full Text Available Abstract Background Age is the major risk factor for many neurodegenerative diseases, including Alzheimer's disease (AD. There is an accumulation of amyloid-beta peptides (Aβ in both the AD brain and the normal aging brain. Clearance of Aβ from the brain occurs via active transport at the blood-brain barrier (BBB and blood-cerebrospinal fluid barrier (BCSFB. With increasing age, the expression of the Aβ efflux transporters is decreased and the Aβ influx transporter expression is increased at the BBB, adding to the amyloid burden in the brain. Expression of the Aβ transporters at the choroid plexus (CP epithelium as a function of aging was the subject of this study. Methods This project investigated the changes in expression of the Aβ transporters, the low density lipoprotein receptor-related protein-1 (LRP-1, P-glycoprotein (P-gp, LRP-2 (megalin and the receptor for advanced glycation end-products (RAGE at the BCSFB in Brown-Norway/Fischer rats at ages 3, 6, 9, 12, 20, 30 and 36 months, using real time RT-PCR to measure transporter mRNA expression, and immunohistochemistry (IHC to measure transporter protein in isolated rat CP. Results There was an increase in the transcription of the Aβ efflux transporters, LRP-1 and P-gp, no change in RAGE expression and a decrease in LRP-2, the CP epithelium influx transporter, at the BCSFB with aging. Decreased Aβ42 concentration in the CP, as measured by quantitative IHC, was associated with these Aβ transporter alterations. Conclusions Age-dependent alterations in the CP Aβ transporters are associated with a decrease in Aβ42 accumulation in the CP, and are reciprocal to the changes seen in these transporters at the BBB, suggesting a possible compensatory role for the BCSFB in Aβ clearance in aging.

secHsp70 as a tool to approach amyloid-β42 and other extracellular amyloids.

Science.gov (United States)

De Mena, Lorena; Chhangani, Deepak; Fernandez-Funez, Pedro; Rincon-Limas, Diego E

2017-07-03

Self-association of amyloidogenic proteins is the main pathological trigger in a wide variety of neurodegenerative disorders. These aggregates are deposited inside or outside the cell due to hereditary mutations, environmental exposures or even normal aging. Cumulative evidence indicates that the heat shock chaperone Hsp70 possesses robust neuroprotection against various intracellular amyloids in Drosophila and mouse models. However, its protective role against extracellular amyloids was largely unknown as its presence outside the cells is very limited. Our recent manuscript in PNAS revealed that an engineered form of secreted Hsp70 (secHsp70) is highly protective against toxicity induced by extracellular deposition of the amyloid-β42 (Aβ42) peptide. In this Extra View article, we extend our analysis to other members of the heat shock protein family. We created PhiC31-based transgenic lines for human Hsp27, Hsp40, Hsp60 and Hsp70 and compared their activities in parallel against extracellular Aβ42. Strikingly, only secreted Hsp70 exhibits robust protection against Aβ42-triggered toxicity in the extracellular milieu. These observations indicate that the ability of secHsp70 to suppress Aβ42 insults is quite unique and suggest that targeted secretion of Hsp70 may represent a new therapeutic approach against Aβ42 and other extracellular amyloids. The potential applications of this engineered chaperone are discussed.

Assessment of the nature interactions of β-amyloid protein by a nanoprobe method.

Science.gov (United States)

Caballero, Leonardo; Mena, Juan; Morales-Alvarez, Aurora; Kogan, Marcelo J; Melo, Francisco

2015-01-01

We present a method based on atomic force microscopy (AFM) to assess the work of adhesion between the interfaces of gold AFM tips functionalized with three peptides derived from β-sheet breaker LPFFD [CLPFFD-NH2 (i0) and their isomers CDLPFF-NH2 (i1) and CLPDFF-NH2 (i2)], and the beta-amyloid protein (Aβ1-42). β-Amyloid protein was deposited onto a highly oriented graphite (HOPG) surface as protofibrils and fibrils. The presence of the residues Leu (L), Phe (F), and Phe (F), which are also present in the native sequence, confirm that the peptides are able to bind to the aggregates of Aβ1-42 fibrils and protofibrils. Force of adhesion data were directly obtained from the maximum force on retraction, and the work of adhesion was calculated from the Jhonson-Kendall-Roberts model (JKR-Model). Both the polar and dispersive contributions to the surface energy of the peptides i0, i1, and i2, as well as Aβ1-42 fibrils and protofibrils, were determined by means of measuring the contact angle and using the two-fluid method. The macroscopic energies of the functionalized gold surfaces do not differ significantly between isomers, which confirms the similar nature of the peptides i0, i1, and i2 but suggests that the macroscopic measurements are not able to distinguish specific sequences. The nanoprobe reveals a typical adhesion work value associated with the interaction of protofibrils with i0 and i2; this value is three times higher than that of i1. The difference is attributed to the hydrophobic nature of protofibrils, the predominant exposition of hydrophobic residues of the peptides i0 and i2, with respect to i1, and the degree of functionalization. i0 and i2 presented a slight adhesion with Aβ fibrils, which is associated with the exposed hydrophilic groups of these fibrils (onto HOPG) compared to the protofibrils. However, i1 showed interaction with both Aβ fibrils and protofibrils. For this, we propose an explanation based on the fact that the peptide i1 locates

Is Verbal Episodic Memory in Elderly with Amyloid Deposits Preserved Through Altered Neuronal Function?

NARCIS (Netherlands)

Ossenkoppele, R.; Madison, C.; Oh, H.; Wirth, M.; van Berckel, B.N.M.; Jagust, W.J.

2014-01-01

A potential mechanism that enables intellectual preservation in cognitively normal elderly that harbor beta-amyloid (Aβ) pathology is heightened cerebral glucose metabolism. To investigate cross-sectional inter-relationships between Aβ, glucose metabolism, and cognition, 81 subjects (mean age: 75±7

Levels of amyloid-beta-42 and CSF pressure are directly related in patients with Alzheimer's disease.

Science.gov (United States)

Schirinzi, Tommaso; Di Lazzaro, Giulia; Sancesario, Giulia Maria; Colona, Vito Luigi; Scaricamazza, Eugenia; Mercuri, Nicola Biagio; Martorana, Alessandro; Sancesario, Giuseppe

2017-12-01

Experimental data suggest that the cerebrospinal fluid (CSF) dynamic is involved in the clearance of beta-amyloid, a key event in the pathogenesis of Alzheimer's disease (AD). At this regard no evidence still exists in vivo. In this study we explored the relationships between CSF pressure and AD pathology, as measured with CSF core biomarkers. We enrolled 16 patients with probable AD and 21 controls, collecting demographics, clinical data, CSF opening pressure and CSF levels of beta-amyloid-42 fragment (Aβ42), total-tau (t-tau), phosphorylated-tau-181 (p-tau), albumin and albumin ratio. Differences between the groups were calculated with non-parametric tests, while correlations among all parameters were separately calculated with Spearman's test in each group. The groups significantly differed in biomarkers' concentration with lower Aβ42, and higher t-tau and p-tau in AD patients. Moreover, CSF pressure was significantly lower in AD group (11.0 ± 2.8 vs. 13.3 ± 3.0 mmHg, p < 0.05) and directly correlated with Aβ42 levels (R = 0.512; p < 0.05), but not with other biomarkers or parameters. No significant correlations emerged for biomarkers in control group. AD patients exhibit low CSF pressure whose values are directly and selectively related to CSF Aβ42 levels. This interesting correlation may confirm in vivo the association between CSF dynamic and beta-amyloid metabolism occurring in AD.

Beta-amyloid deposition and cognitive function in patients with major depressive disorder with different subtypes of mild cognitive impairment: {sup 18}F-florbetapir (AV-45/Amyvid) PET study

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Wu, Kuan-Yi; Liu, Chia-Yih; Chen, Chia-Hsiang; Lee, Chin-Pang [Chang Gung Memorial Hospital and Chang Gung University, Department of Psychiatry, Tao-Yuan (China); Chen, Cheng-Sheng [Kaohsiung Medical University Hospital and College of Medicine, Kaohsiung Medical University, Department of Psychiatry, Kaohsiung (China); Hsiao, Ing-Tsung; Hsieh, Chia-Ju; Yen, Tzu-Chen; Lin, Kun-Ju [Chang Gung Memorial Hospital, Department of Nuclear Medicine and Molecular Imaging Center, Kuei Shan Hsiang, Taoyuan (China); Chang Gung University, Department of Medical Imaging and Radiological Sciences and Healthy Aging Research Center, Tao-Yuan (China)

2016-06-15

The objective of this study was to evaluate the amyloid burden, as assessed by {sup 18}F-florbetapir (AV-45/Amyvid) positron emission tomography PET, in patients with major depressive disorder (MDD) with different subtypes of mild cognitive impairment (MCI) and the relationship between amyloid burden and cognition in MDD patients. The study included 55 MDD patients without dementia and 21 healthy control subjects (HCs) who were assessed using a comprehensive cognitive test battery and {sup 18}F-florbetapir PET imaging. The standardized uptake value ratios (SUVR) in eight cortical regions using the whole cerebellum as reference region were determined and voxel-wise comparisons between the HC and MDD groups were performed. Vascular risk factors, serum homocysteine level and the apolipoprotein E (ApoE) genotype were also determined. Among the 55 MDD patients, 22 (40.0 %) had MCI, 12 (21.8 %) non-amnestic MCI (naMCI) and 10 (18.2 %) amnestic MCI (aMCI). The MDD patients with aMCI had the highest relative {sup 18}F-florbetapir uptake in all cortical regions, and a significant difference in relative {sup 18}F-florbetapir uptake was found in the parietal region as compared with that in naMCI subjects (P < 0.05) and HCs (P < 0.01). Voxel-wise analyses revealed significantly increased relative {sup 18}F-florbetapir uptake in the MDD patients with aMCI and naMCI in the frontal, parietal, temporal and occipital areas (P < 0.005). The global cortical SUVR was significantly negatively correlated with MMSE score (r = -0.342, P = 0.010) and memory function (r = -0.328, P = 0.015). The negative correlation between the global SUVR and memory in the MDD patients remained significant in multiple regression analyses that included age, educational level, ApoE genotype, and depression severity (β = -3.607, t = -2.874, P = 0.006). We found preliminary evidence of brain beta-amyloid deposition in MDD patients with different subtypes of MCI. Our findings in MDD patients support the

Primary cutaneous marginal zone B-cell lymphoma with amyloid deposition: report of two cases with review of literature.

Science.gov (United States)

Zhang, Hai-Yan; Liu, An-Li; Zhou, Ling-sheng; He, Miao-Xia; Wang, Jian-Xin

2010-06-01

Amyloid deposition is rare. If there was a great amount of amyloid depositions in the skin tissue, it would be considered to be amyloid deposition disease at first, and then primary cutaneous marginal zone B-cell lymphoma (PCMZL). This study was to analyze the diagnosis and differential diagnosis of two cases of PCMZL with amyloid deposition. Clinicopathologic characteristics and follow-up of two cases of PCMZL were analyzed. Immunohistochemical staining was performed by EnVision method using antibodies LCA, CD19, CD20, CD79a, CD3, CD7, MUM1, kappa, lambda, Ki-67. IgH and TCRgamma gene rearrangement was detected by polymerase chain reactive (PCR). Case 1, a 71-year-old Chinese male, had a subcutaneous mass on the right elbow that was initially diagnosed with "amyloidosis" in 2004. Three years after the initial diagnosis, he developed recurrences on the right para-auxillary that was still diagnosed with "probably amyloidosis". Four years after the first diagnosis, the patient presented a lesion on the right para-auxillary with a diameter of 2 cm and a lesion on the temporal-parietal dural with a size of 6.0 cmx3.0 cmx3.0 cm. Case 2, a 68-year-old Chinese male, had a subcutaneous mass next to back of the left ear with a size of 9.0 cmx5.0 cm, and he underwent a operation one year previously because of subcutaneous mass in the same site. Microscopically, the tumors of both cases were located in dermis and subcutaneous, tumor cells were medium size with a nodular or diffuse distribution, and some of tumor cells were plasmacytoid/plasma cells. Morphologically, the temporal-parietal dural lesion was similar to subcutaneous lesion and infiltrated into cranial (case 1). Juxtaposed the tumor cells of two cases, there were the large amyloid deposits of amorphous hyaline material and concentrically laminated hyaline spherules in case 1, while cord-like amyloid deposits in case 2. Reactive lymphoid follicles with germinal centers and foreign body giant cells in the stroma were

Red mold rice ameliorates impairment of memory and learning ability in intracerebroventricular amyloid beta-infused rat by repressing amyloid beta accumulation.

Science.gov (United States)

Lee, Chun-Lin; Kuo, Tzong-Fu; Wang, Jyh-Jye; Pan, Tzu-Ming

2007-11-01

Amyloid beta (Abeta) peptide related to the onset of Alzheimer's disease (AD) damaged neurons and further resulted in dementia. Monascus-fermented red mold rice (RMR), a traditional Chinese medicine as well as health food, includes monacolins (with the same function as statins) and multifunctional metabolites. In this study, ethanol extract of RMR (RE) was used to evaluate neuroprotection against Abeta40 neurotoxicity in PC12 cells. Furthermore, the effects of dietary administration of RMR on memory and learning abilities are confirmed in an animal model of AD rats infused with Abeta40 into the cerebral ventricle. During continuous Abeta40 infusion for 28 days, the rats of test groups were administered RMR or lovastatin. Memory and learning abilities were evaluated in the water maze and passive avoidance tasks. After sacrifice, cerebral cortex and hippocampus were collected for the examination of AD risk factors. The in vitro results clearly indicate that RE provides stronger neuroprotection in rescuing cell viability as well as repressing inflammatory response and oxidative stress. RMR administration potently reverses the memory deficit in the memory task. Abeta40 infusion increases acetylcholinesterase activity, reactive oxygen species, and lipid peroxidation and decreases total antioxidant status and superoxide dismutase activity in brain, but these damages were potently reversed by RMR administration, and the protection was more significant than that with lovastatin administration. The protection provided by RMR is able to prevent Abeta fibrils from being formed and deposited in hippocampus and further decrease Abeta40 accumulation, even though Abeta40 solution was infused into brain continuously. (c) 2007 Wiley-Liss, Inc.

Exploring new biological functions of amyloids: bacteria cell agglutination mediated by host protein aggregation.

Directory of Open Access Journals (Sweden)

Marc Torrent

Full Text Available Antimicrobial proteins and peptides (AMPs are important effectors of the innate immune system that play a vital role in the prevention of infections. Recent advances have highlighted the similarity between AMPs and amyloid proteins. Using the Eosinophil Cationic Protein as a model, we have rationalized the structure-activity relationships between amyloid aggregation and antimicrobial activity. Our results show how protein aggregation can induce bacteria agglutination and cell death. Using confocal and total internal reflection fluorescence microscopy we have tracked the formation in situ of protein amyloid-like aggregates at the bacteria surface and on membrane models. In both cases, fibrillar aggregates able to bind to amyloid diagnostic dyes were detected. Additionally, a single point mutation (Ile13 to Ala can suppress the protein amyloid behavior, abolishing the agglutinating activity and impairing the antimicrobial action. The mutant is also defective in triggering both leakage and lipid vesicle aggregation. We conclude that ECP aggregation at the bacterial surface is essential for its cytotoxicity. Hence, we propose here a new prospective biological function for amyloid-like aggregates with potential biological relevance.

Effect of four medicinal plants on amyloid-beta induced neurotoxicity in SH-SY5Y Cells

CSIR Research Space (South Africa)

Adewusi, EA

2013-01-01

Full Text Available Amyloid-beta peptide (Aß) is implicated in the pathogenesis of Alzheimer’s disease (AD), a neurodegenerative disorder. This study was designed to determine the effect of four medicinal plants used to treat neurodegenerative diseases on Aß...

Amyloid-beta induced CA1 pyramidal cell loss in young adult rats is alleviated by systemic treatment with FGL, a neural cell adhesion molecule-derived mimetic peptide.

Directory of Open Access Journals (Sweden)

Nicola J Corbett

Full Text Available Increased levels of neurotoxic amyloid-beta in the brain are a prominent feature of Alzheimer's disease. FG-Loop (FGL, a neural cell adhesion molecule-derived peptide that corresponds to its second fibronectin type III module, has been shown to provide neuroprotection against a range of cellular insults. In the present study impairments in social recognition memory were seen 24 days after a 5 mg/15 µl amyloid-beta(25-35 injection into the right lateral ventricle of the young adult rat brain. This impairment was prevented if the animal was given a systemic treatment of FGL. Unbiased stereology was used to investigate the ability of FGL to alleviate the deleterious effects on CA1 pyramidal cells of the amyloid-beta(25-35 injection. NeuN, a neuronal marker (for nuclear staining was used to identify pyramidal cells, and immunocytochemistry was also used to identify inactive glycogen synthase kinase 3beta (GSK3β and to determine the effects of amyloid-beta(25-35 and FGL on the activation state of GSK3β, since active GSK3β has been shown to cause a range of AD pathologies. The cognitive deficits were not due to hippocampal atrophy as volume estimations of the entire hippocampus and its regions showed no significant loss, but amyloid-beta caused a 40% loss of pyramidal cells in the dorsal CA1 which was alleviated partially by FGL. However, FGL treatment without amyloid-beta was also found to cause a 40% decrease in CA1 pyramidal cells. The action of FGL may be due to inactivation of GSK3β, as an increased proportion of CA1 pyramidal neurons contained inactive GSK3β after FGL treatment. These data suggest that FGL, although potentially disruptive in non-pathological conditions, can be neuroprotective in disease-like conditions.

Tuning the stereo-hindrance of a curcumin scaffold for the selective imaging of the soluble forms of amyloid beta species.

Science.gov (United States)

Li, Yuyan; Yang, Jian; Liu, Hongwu; Yang, Jing; Du, Lei; Feng, Haiwei; Tian, Yanli; Cao, Jianqin; Ran, Chongzhao

2017-11-01

Amyloid peptides and proteins are associated with the pathologies of numerous diseases. In the progression of a disease, amyloids exist in soluble and insoluble forms, which are the dominant species at different stages of the disease and they have different degrees of toxicity. However, differentiating between the soluble and insoluble forms is very challenging with small molecule probes due to multiple obstacles that need to be overcome. Inspired by the recognition principle of antibodies for sAβ, we hypothesized that the accessibility/tightness of soluble and insoluble amyloids could be utilized to design imaging probes to recognize different amyloid forms and the stereo-hindrance tuning strategy could be used to design imaging probes for selectively detecting the soluble amyloid beta (sAβ) species in Alzheimer's disease (AD). Herein, we demonstrated that tuning the stereo-hindrance of the phenoxy-alkyl chains at the 4-position of a curcumin scaffold could lead to certain selectivity for sAβ over insoluble Aβs (insAβ). Among the designed compounds, CRANAD-102 showed a 68-fold higher affinity for sAβ than for insAβ (7.5 ± 10 nM vs. 505.9 ± 275.9 nM). Moreover, our imaging data indicated that CRANAD-102 was indeed capable of detecting sAβ in vivo using 4 month old APP/PS1 mice, in which sAβ is the predominant species in the brain. In addition, we also demonstrated that CRANAD-102 could be used to monitor the increase in sAβ loading from the ages of 4 months old to 12 months old. We believe that CRANAD-102 can be a useful probe for selectively detecting sAβ species in AD and that our probe designing strategy can be applied to other amyloids and will have tremendous impact on AD drug development and other amyloid research.

Amyloid beta peptide immunotherapy in Alzheimer disease.

Science.gov (United States)

Delrieu, J; Ousset, P J; Voisin, T; Vellas, B

2014-12-01

Recent advances in the understanding of Alzheimer's disease pathogenesis have led to the development of numerous compounds that might modify the disease process. Amyloid β peptide represents an important molecular target for intervention in Alzheimer's disease. The main purpose of this work is to review immunotherapy studies in relation to the Alzheimer's disease. Several types of amyloid β peptide immunotherapy for Alzheimer's disease are under investigation, active immunization and passive administration with monoclonal antibodies directed against amyloid β peptide. Although immunotherapy approaches resulted in clearance of amyloid plaques in patients with Alzheimer's disease, this clearance did not show significant cognitive effect for the moment. Currently, several amyloid β peptide immunotherapy approaches are under investigation but also against tau pathology. Results from amyloid-based immunotherapy studies in clinical trials indicate that intervention appears to be more effective in early stages of amyloid accumulation in particular solanezumab with a potential impact at mild Alzheimer's disease, highlighting the importance of diagnosing Alzheimer's disease as early as possible and undertaking clinical trials at this stage. In both phase III solanezumab and bapineuzumab trials, PET imaging revealed that about a quarter of patients lacked fibrillar amyloid pathology at baseline, suggesting that they did not have Alzheimer's disease in the first place. So a new third phase 3 clinical trial for solanezumab, called Expedition 3, in patients with mild Alzheimer's disease and evidence of amyloid burden has been started. Thus, currently, amyloid intervention is realized at early stage of the Alzheimer's disease in clinical trials, at prodromal Alzheimer's disease, or at asymptomatic subjects or at risk to develop Alzheimer's disease and or at asymptomatic subjects with autosomal dominant mutation. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Chronic exposure of NG108-15 cells to amyloid beta peptide (A beta(1-42)) abolishes calcium influx via N-type calcium channels

Czech Academy of Sciences Publication Activity Database

Kašparová, Jana; Lisá, Věra; Tuček, Stanislav; Doležal, Vladimír

2001-01-01

Roč. 26, 8-9 (2001), s. 1079-1084 ISSN 0364-3190 R&D Projects: GA MZd NF5183 Institutional research plan: CEZ:AV0Z5011922 Keywords : amyloid beta peptide * Alzheimer's disease * calcium Subject RIV: FH - Neurology Impact factor: 1.638, year: 2001

A-Raf kinase is a new interacting partner of protein kinase CK2 beta subunit

DEFF Research Database (Denmark)

Boldyreff, B; Issinger, O G

1997-01-01

In a search for protein kinase CK2 beta subunit binding proteins using the two-hybrid system, more than 1000 positive clones were isolated. Beside clones for the alpha' and beta subunit of CK2, there were clones coding for a so far unknown protein, whose partial cDNA sequence was already deposited...

Imaging characteristics of subcutaneous amyloid deposits in diabetic patients: the ''insulin ball''

Energy Technology Data Exchange (ETDEWEB)

Tanio, Noriko; Nozaki, Taiki; Matsusako, Masaki; Starkey, Jay [St. Luke' s International Hospital, Department of Radiology, Tokyo (Japan); Suzuki, Koyu [St. Luke' s International Hospital, Department of Pathology, Tokyo (Japan)

2018-01-15

The purpose of this study was to describe the imaging characteristics of subcutaneous amyloid deposits occurring at sites of insulin injection, commonly known as ''insulin balls,'' in diabetic patients on ultrasound, CT, and MRI with pathologic correlation. We retrospectively reviewed the radiographic findings of 14 lesions in 9 patients diagnosed with subcutaneous amyloid deposits at our institution between 2005-2015. Three board-certified radiologists analyzed the following: (1) the shape, size, margin, morphologic characteristics, and blood flow on US using the color Doppler signal, (2) shape, size, margin, attenuation, and presence or absence of contrast enhancement on CT, and (3) shape, size, margin, signal intensity, and presence or absence of contrast enhancement on MRI. All lesions showed ill-defined hypovascular subcutaneous nodules with irregular margins. The median diameter of lesions was 50.4 mm on US, 46.8 mm on CT, and 51.4 mm on MRI. The internal echogenicity of subcutaneous amyloid deposits was hypoechoic and heterogeneous on US. All lesions showed isodensity compared to muscle with irregular margins and minimal contrast enhancement on CT. Both T1- and T2-weighted MR images showed low signal intensity compared with subcutaneous fat. Normal diffusion and minimal contrast enhancement were seen. Subcutaneous amyloid deposits which cause insulin resistance are typically ill-defined and heterogeneous hypovascular subcutaneous nodules with irregular margins on imaging that correspond to insulin injection sites. It is also characteristic that T2WI shows low intensity compared with fat on MRI, reflective of the amyloid content. (orig.)

Imaging characteristics of subcutaneous amyloid deposits in diabetic patients: the ''insulin ball''

International Nuclear Information System (INIS)

Tanio, Noriko; Nozaki, Taiki; Matsusako, Masaki; Starkey, Jay; Suzuki, Koyu

2018-01-01

The purpose of this study was to describe the imaging characteristics of subcutaneous amyloid deposits occurring at sites of insulin injection, commonly known as ''insulin balls,'' in diabetic patients on ultrasound, CT, and MRI with pathologic correlation. We retrospectively reviewed the radiographic findings of 14 lesions in 9 patients diagnosed with subcutaneous amyloid deposits at our institution between 2005-2015. Three board-certified radiologists analyzed the following: (1) the shape, size, margin, morphologic characteristics, and blood flow on US using the color Doppler signal, (2) shape, size, margin, attenuation, and presence or absence of contrast enhancement on CT, and (3) shape, size, margin, signal intensity, and presence or absence of contrast enhancement on MRI. All lesions showed ill-defined hypovascular subcutaneous nodules with irregular margins. The median diameter of lesions was 50.4 mm on US, 46.8 mm on CT, and 51.4 mm on MRI. The internal echogenicity of subcutaneous amyloid deposits was hypoechoic and heterogeneous on US. All lesions showed isodensity compared to muscle with irregular margins and minimal contrast enhancement on CT. Both T1- and T2-weighted MR images showed low signal intensity compared with subcutaneous fat. Normal diffusion and minimal contrast enhancement were seen. Subcutaneous amyloid deposits which cause insulin resistance are typically ill-defined and heterogeneous hypovascular subcutaneous nodules with irregular margins on imaging that correspond to insulin injection sites. It is also characteristic that T2WI shows low intensity compared with fat on MRI, reflective of the amyloid content. (orig.)

Dynamic relationships between age, amyloid-β deposition, and glucose metabolism link to the regional vulnerability to Alzheimer’s disease

Science.gov (United States)

Madison, Cindee; Baker, Suzanne; Rabinovici, Gil; Jagust, William

2016-01-01

Abstract See Hansson and Gouras (doi:10.1093/aww146) for a scientific commentary on this article. Although some brain regions such as precuneus and lateral temporo-parietal cortex have been shown to be more vulnerable to Alzheimer’s disease than other areas, a mechanism underlying the differential regional vulnerability to Alzheimer’s disease remains to be elucidated. Using fluorodeoxyglucose and Pittsburgh compound B positron emission tomography imaging glucose metabolism and amyloid-β deposition, we tested whether and how life-long changes in glucose metabolism relate to amyloid-β deposition and Alzheimer’s disease-related hypometabolism. Nine healthy young adults (age range: 20–30), 96 cognitively normal older adults (age range: 61–96), and 20 patients with Alzheimer’s disease (age range: 50–90) were scanned using fluorodeoxyglucose and Pittsburgh compound B positron emission tomography. Among cognitively normal older subjects, 32 were further classified as amyloid-positive, with 64 as amyloid-negative. To assess the contribution of glucose metabolism to the regional vulnerability to amyloid-β deposition, we defined the highest and lowest metabolic regions in young adults and examined differences in amyloid deposition between these regions across groups. Two-way analyses of variance were conducted to assess regional differences in age and amyloid-β-related changes in glucose metabolism. Multiple regressions were applied to examine the association between amyloid-β deposition and regional glucose metabolism. Both region of interest and whole-brain voxelwise analyses were conducted to complement and confirm the results derived from the other approach. Regional differences in glucose metabolism between the highest and lowest metabolism regions defined in young adults (T = 12.85, P glucose metabolism regions defined in young adults (T = 2.05, P glucose metabolism were found such that frontal glucose metabolism was reduced with age, while glucose

Amyloid and metabolic positron emission tomography imaging of cognitively normal adults with Alzheimer's parents

DEFF Research Database (Denmark)

Mosconi, Lisa; Rinne, Juha O; Tsui, Wai H

2013-01-01

This study examines the relationship between fibrillar beta-amyloid (Aβ) deposition and reduced glucose metabolism, a proxy for neuronal dysfunction, in cognitively normal (NL) individuals with a parent affected by late-onset Alzheimer's disease (AD). Forty-seven 40-80-year-old NL received positr...

Mitogen-activated protein kinase signaling pathways promote low-density lipoprotein receptor-related protein 1-mediated internalization of beta-amyloid protein in primary cortical neurons.

Science.gov (United States)

Yang, Wei-Na; Ma, Kai-Ge; Qian, Yi-Hua; Zhang, Jian-Shui; Feng, Gai-Feng; Shi, Li-Li; Zhang, Zhi-Chao; Liu, Zhao-Hui

2015-07-01

Mounting evidence suggests that the pathological hallmarks of Alzheimer's disease (AD) are caused by the intraneuronal accumulation of beta-amyloid protein (Aβ). Reuptake of extracellular Aβ is believed to contribute significantly to the intraneuronal Aβ pool in the early stages of AD. Published reports have claimed that the low-density lipoprotein receptor-related protein 1 (LRP1) mediates Aβ1-42 uptake and lysosomal trafficking in GT1-7 neuronal cells and mouse embryonic fibroblast non-neuronal cells. However, there is no direct evidence supporting the role of LRP1 in Aβ internalization in primary neurons. Our recent study indicated that p38 MAPK and ERK1/2 signaling pathways are involved in regulating α7 nicotinic acetylcholine receptor (α7nAChR)-mediated Aβ1-42 uptake in SH-SY5Y cells. This study was designed to explore the regulation of MAPK signaling pathways on LRP1-mediated Aβ internalization in neurons. We found that extracellular Aβ1-42 oligomers could be internalized into endosomes/lysosomes and mitochondria in cortical neurons. Aβ1-42 and LRP1 were also found co-localized in neurons during Aβ1-42 internalization, and they could form Aβ1-42-LRP1 complex. Knockdown of LRP1 expression significantly decreased neuronal Aβ1-42 internalization. Finally, we identified that p38 MAPK and ERK1/2 signaling pathways regulated the internalization of Aβ1-42 via LRP1. Therefore, these results demonstrated that LRP1, p38 MAPK and ERK1/2 mediated the internalization of Aβ1-42 in neurons and provided evidence that blockade of LRP1 or inhibitions of MAPK signaling pathways might be a potential approach to lowering brain Aβ levels and served a potential therapeutic target for AD. Copyright © 2015 Elsevier Ltd. All rights reserved.

Protein Polymers and Amyloids

DEFF Research Database (Denmark)

Risør, Michael Wulff

2014-01-01

Several human disorders are caused by a common general disease mechanism arising from abnormal folding and aggregation of the underlying protein. These include the prevalent dementias like Alzheimer’s and Parkinson’s, where accumulation of protein fibrillar structures, known as amyloid fibrils......, is a general hallmark. They also include the α1-antitrypsin deficiency, where disease-causing mutations in the serine protease inhibitor, α1-antitrypsin (α1AT), leads to accumulation of the aberrant protein in the liver of these patients. The native metastable structure of α1AT constitutes a molecular trap...... that inhibits its target protease through a large conformational change but mutations compromise this function and cause premature structural collapse into hyperstable polymers. Understanding the conformational disorders at a molecular level is not only important for our general knowledge on protein folding...

Curcumin Decreases Amyloid-β Peptide Levels by Attenuating the Maturation of Amyloid-β Precursor Protein*

Science.gov (United States)

Zhang, Can; Browne, Andrew; Child, Daniel; Tanzi, Rudolph E.

2010-01-01

Alzheimer disease (AD) is a devastating neurodegenerative disease with no cure. The pathogenesis of AD is believed to be driven primarily by amyloid-β (Aβ), the principal component of senile plaques. Aβ is an ∼4-kDa peptide generated via cleavage of the amyloid-β precursor protein (APP). Curcumin is a compound in the widely used culinary spice, turmeric, which possesses potent and broad biological activities, including anti-inflammatory and antioxidant activities, chemopreventative effects, and effects on protein trafficking. Recent in vivo studies indicate that curcumin is able to reduce Aβ-related pathology in transgenic AD mouse models via unknown molecular mechanisms. Here, we investigated the effects of curcumin on Aβ levels and APP processing in various cell lines and mouse primary cortical neurons. We show for the first time that curcumin potently lowers Aβ levels by attenuating the maturation of APP in the secretory pathway. These data provide a mechanism of action for the ability of curcumin to attenuate amyloid-β pathology. PMID:20622013

Detection of Alzheimer’s disease amyloid-beta plaque deposition by deep brain impedance profiling

Science.gov (United States)

Béduer, Amélie; Joris, Pierre; Mosser, Sébastien; Fraering, Patrick C.; Renaud, Philippe

2015-04-01

Objective. Alzheimer disease (AD) is the most common form of neurodegenerative disease in elderly people. Toxic brain amyloid-beta (Aß) aggregates and ensuing cell death are believed to play a central role in the pathogenesis of the disease. In this study, we investigated if we could monitor the presence of these aggregates by performing in situ electrical impedance spectroscopy measurements in AD model mice brains. Approach. In this study, electrical impedance spectroscopy measurements were performed post-mortem in APPPS1 transgenic mice brains. This transgenic model is commonly used to study amyloidogenesis, a pathological hallmark of AD. We used flexible probes with embedded micrometric electrodes array to demonstrate the feasibility of detecting senile plaques composed of Aß peptides by localized impedance measurements. Main results. We particularly focused on deep brain structures, such as the hippocampus. Ex vivo experiments using brains from young and old APPPS1 mice lead us to show that impedance measurements clearly correlate with the percentage of Aβ plaque load in the brain tissues. We could monitor the effects of aging in the AD APPPS1 mice model. Significance. We demonstrated that a localized electrical impedance measurement constitutes a valuable technique to monitor the presence of Aβ-plaques, which is complementary with existing imaging techniques. This method does not require prior Aβ staining, precluding the risk of variations in tissue uptake of dyes or tracers, and consequently ensuring reproducible data collection.

Biological markers of amyloid beta-related mechanisms in Alzheimer's disease.

LENUS (Irish Health Repository)

Hampel, Harald

2010-06-01

Recent research progress has given detailed knowledge on the molecular pathogenesis of Alzheimer\\'s disease (AD), which has been translated into an intense, ongoing development of disease-modifying treatments. Most new drug candidates are targeted on inhibiting amyloid beta (Abeta) production and aggregation. In drug development, it is important to co-develop biomarkers for Abeta-related mechanisms to enable early diagnosis and patient stratification in clinical trials, and to serve as tools to identify and monitor the biochemical effect of the drug directly in patients. Biomarkers are also requested by regulatory authorities to serve as safety measurements. Molecular aberrations in the AD brain are reflected in the cerebrospinal fluid (CSF). Core CSF biomarkers include Abeta isoforms (Abeta40\\/Abeta42), soluble APP isoforms, Abeta oligomers and beta-site APP-cleaving enzyme 1 (BACE1). This article reviews recent research advances on core candidate CSF and plasma Abeta-related biomarkers, and gives a conceptual review on how to implement biomarkers in clinical trials in AD.

Biological markers of amyloid beta-related mechanisms in Alzheimer's disease.

LENUS (Irish Health Repository)

Hampel, Harald

2012-02-01

Recent research progress has given detailed knowledge on the molecular pathogenesis of Alzheimer\\'s disease (AD), which has been translated into an intense, ongoing development of disease-modifying treatments. Most new drug candidates are targeted on inhibiting amyloid beta (Abeta) production and aggregation. In drug development, it is important to co-develop biomarkers for Abeta-related mechanisms to enable early diagnosis and patient stratification in clinical trials, and to serve as tools to identify and monitor the biochemical effect of the drug directly in patients. Biomarkers are also requested by regulatory authorities to serve as safety measurements. Molecular aberrations in the AD brain are reflected in the cerebrospinal fluid (CSF). Core CSF biomarkers include Abeta isoforms (Abeta40\\/Abeta42), soluble APP isoforms, Abeta oligomers and beta-site APP-cleaving enzyme 1 (BACE1). This article reviews recent research advances on core candidate CSF and plasma Abeta-related biomarkers, and gives a conceptual review on how to implement biomarkers in clinical trials in AD.

Cellular demise and inflammatory microglial activation during beta-amyloid toxicity are governed by Wnt1 and canonical signaling pathways.

Science.gov (United States)

Chong, Zhao Zhong; Li, Faqi; Maiese, Kenneth

2007-06-01

Initially described as a modulator of embryogenesis for a number of organ systems, Wnt1 has recently been linked to the development of several neurodegenerative disorders, none being of greater significance than Alzheimer's disease. We therefore examined the ability of Wnt1 to oversee vital pathways responsible for cell survival during beta-amyloid (Abeta1-42) exposure. Here we show that Wnt1 is critical for protection in the SH-SY5Y neuronal cell line against genomic DNA degradation, membrane phosphatidylserine (PS) exposure, and microglial activation, since these neuroprotective attributes of Wnt1 are lost during gene silencing of Wnt1 protein expression. Intimately tied to Wnt1 protection is the presence and activation of Akt1. Pharmacological inhibition of the PI 3-K pathway or gene silencing of Akt1 expression can abrogate the protective capacity of Wnt1. Closely aligned with Wnt1 and Akt1 are the integrated canonical pathways of synthase kinase-3beta (GSK-3beta) and beta-catenin. Through Akt1 dependent pathways, Wnt1 phosphorylates GSK-3beta and maintains beta-catenin integrity to insure its translocation from the cytoplasm to the nucleus to block apoptosis. Our work outlines a highly novel role for Wnt1 and its integration with Akt1, GSK-3beta, and beta-catenin to foster neuronal cell survival and repress inflammatory microglial activation that can identify new avenues of therapy against neurodegenerative disorders.

Calumenin interacts with serum amyloid P component

DEFF Research Database (Denmark)

Vorum, H; Jacobsen, Christian; Honoré, Bent

2000-01-01

with calumenin in the presence of Ca(2+). Amino acid sequencing identified this protein as serum amyloid P component (SAP). Furthermore, we verified and characterized the calumenin-SAP interaction by the surface plasmon resonance technique. The findings indicate that calumenin may participate...... in the immunological defense system and could be involved in the pathological process of amyloidosis that leads to formation of amyloid deposits seen in different types of tissues. Udgivelsesdato: 2000-Jan-14...

Spectroscopic study of Alzheimer's amyloid fibrils using terahertz time domain spectroscopy

International Nuclear Information System (INIS)

Jung, Euna; Kim, Jeonghoi; Han, Younho; Moon, Kiwon; Lim, Meehyun; Han, Haewook; Park, Joonhyuck; Kim, Sungjee

2008-01-01

Alzheimer's disease, one of the most common neurodegenerative diseases, is characterized by extensive amyloid deposition. Amyloid deposits contain the abundant fibrils formed by amyloid β protein (Aβ). Because amyloid fibrils are associated with amyloid diseases, including Alzheimer's disease, type 2 diabetes, prion disease, Parkinson's disease, senile systemic amyloidosis and Huntington's disease, there has been considerable interest within the biomedical and biochemical research communities. In transmission electron microscopic (TEM)images, amyloid firils are 0.1∼10μm long and approximately 10nm wide. Amyloid fibrils commonly exhibit self assembled filaments, often described as twisted or parallel assemblies of finer protofilaments. They are formed by the spontaneous aggregation of a wide variety of peptides and proteins. Structural studies of amyloid fibrils have revealed that the common structural motif of virtually all amyloid fibrils consists of cross β sheets in which the peptide strands are arranged perpendicular to the long axis of the fiber. But little was known until recently about the molecular level structures of amyloid fibils. Therefore, spectroscopic investigation of both amyloid fibrils and Aβ at the molecular level can provide the significant evidence for the molecular understanding of amyloidogenesis and for the development of innovative therapeutic and diagnostic approaches. We used terahertz time domain spectroscopy (THz TDS)to investigate both Aβ and amyloid fibril. THz TDS, developed over the last two decades, is a powerful tool to extract the properties of biomaterials and provides unique spectral signatures of biomolecules within 0.1∼10THz, which exists between microwave and infrared frequency range. Current interest in THz radiation arises from its capability of probing the delocalized collective vibrational modes in proteins. Studying the collective modes of proteins in THz frequency range can play an important role in

Quantification of amyloid deposits and oxygen extraction fraction in the brain with multispectral optoacoustic imaging in arcAβ mouse model of Alzheimer's disease

Science.gov (United States)

Ni, Ruiqing; Vaas, Markus; Rudin, Markus; Klohs, Jan

2018-02-01

Beta-amyloid (Aβ) deposition and vascular dysfunction are important contributors to the pathogenesis in Alzheimer's disease (AD). However, the spatio-temporal relationship between an altered oxygen metabolism and Aβ deposition in the brain remains elusive. Here we provide novel in-vivo estimates of brain Aβ load with Aβ-binding probe CRANAD-2 and measures of brain oxygen saturation by using multi-spectral optoacoustic imaging (MSOT) and perfusion imaging with magnetic resonance imaging (MRI) in arcAβ mouse models of AD. We demonstrated a decreased cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) in the cortical region of the arcAβ mice compared to wildtype littermates at 24 months. In addition, we showed proof-of-concept for the detection of cerebral Aβ deposits in brain from arcAβ mice compared to wild-type littermates.

APOE ε4 influences β-amyloid deposition in primary progressive aphasia and speech apraxia.

Science.gov (United States)

Josephs, Keith A; Duffy, Joseph R; Strand, Edythe A; Machulda, Mary M; Senjem, Matthew L; Lowe, Val J; Jack, Clifford R; Whitwell, Jennifer L

2014-11-01

Apolipoprotein E ε4 (APOE ε4) is a risk factor for β-amyloid deposition in Alzheimer's disease dementia. Its influence on β-amyloid deposition in speech and language disorders, including primary progressive aphasia (PPA), is unclear. One hundred thirty subjects with PPA or progressive speech apraxia underwent APOE genotyping and Pittsburgh compound B (PiB) PET scanning. The relationship between APOE ε4 and PiB status, as well as severity and regional distribution of PiB, was assessed. Forty-five subjects had an APOE ε4 allele and 60 subjects were PiB-positive. The odds ratio for a subject with APOE ε4 being PiB-positive compared with a subject without APOE ε4 being PiB-positive was 10.2 (95% confidence interval, 4.4-25.5; P speech apraxia but does not influence regional β-amyloid distribution or severity. Copyright © 2014 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

COPS5 (Jab1) protein increases β site processing of amyloid precursor protein and amyloid β peptide generation by stabilizing RanBP9 protein levels.

Science.gov (United States)

Wang, Hongjie; Dey, Debleena; Carrera, Ivan; Minond, Dmitriy; Bianchi, Elisabetta; Xu, Shaohua; Lakshmana, Madepalli K

2013-09-13

Increased processing of amyloid precursor protein (APP) and accumulation of neurotoxic amyloid β peptide (Aβ) in the brain is central to the pathogenesis of Alzheimer's disease (AD). Therefore, the identification of molecules that regulate Aβ generation is crucial for future therapeutic approaches for AD. We demonstrated previously that RanBP9 regulates Aβ generation in a number of cell lines and primary neuronal cultures by forming tripartite protein complexes with APP, low-density lipoprotein-related protein, and BACE1, consequently leading to increased amyloid plaque burden in the brain. RanBP9 is a scaffold protein that exists and functions in multiprotein complexes. To identify other proteins that may bind RanBP9 and regulate Aβ levels, we used a two-hybrid analysis against a human brain cDNA library and identified COPS5 as a novel RanBP9-interacting protein. This interaction was confirmed by coimmunoprecipitation experiments in both neuronal and non-neuronal cells and mouse brain. Colocalization of COPS5 and RanBP9 in the same subcellular compartments further supported the interaction of both proteins. Furthermore, like RanBP9, COPS5 robustly increased Aβ generation, followed by increased soluble APP-β (sAPP-β) and decreased soluble-APP-α (sAPP-α) levels. Most importantly, down-regulation of COPS5 by siRNAs reduced Aβ generation, implying that endogenous COPS5 regulates Aβ generation. Finally, COPS5 levels were increased significantly in AD brains and APΔE9 transgenic mice, and overexpression of COPS5 strongly increased RanBP9 protein levels by increasing its half-life. Taken together, these results suggest that COPS5 increases Aβ generation by increasing RanBP9 levels. Thus, COPS5 is a novel RanBP9-binding protein that increases APP processing and Aβ generation by stabilizing RanBP9 protein levels.

Overproduction, purification, crystallization and preliminary X-ray analysis of human Fe65-PTB2 in complex with the amyloid precursor protein intracellular domain

Energy Technology Data Exchange (ETDEWEB)

Radzimanowski, Jens [Heidelberg University Biochemistry Center, INF328, D-69120 Heidelberg (Germany); Beyreuther, Konrad [Center for Molecular Biology, University Heidelberg, INF282, D-69120 Heidelberg (Germany); Sinning, Irmgard; Wild, Klemens, E-mail: klemens.wild@bzh.uni-heidelberg.de [Heidelberg University Biochemistry Center, INF328, D-69120 Heidelberg (Germany)

2008-05-01

Alzheimer’s disease is characterized by proteolytic processing of the amyloid precursor protein (APP), which releases the aggregation-prone amyloid-β (Aβ) peptide and liberates the intracellular domain (AICD) that interacts with various adaptor proteins. The crystallized AICD–Fe65-PTB2 complex is of central importance for APP translocation, nuclear signalling, processing and Aβ generation. Alzheimer’s disease is associated with typical brain deposits (senile plaques) that mainly contain the neurotoxic amyloid β peptide. This peptide results from proteolytic processing of the type I transmembrane protein amyloid precursor protein (APP). During this proteolytic pathway the APP intracellular domain (AICD) is released into the cytosol, where it associates with various adaptor proteins. The interaction of the AICD with the C-terminal phosphotyrosine-binding domain of Fe65 (Fe65-PTB2) regulates APP translocation, signalling and processing. Human AICD and Fe65-PTB2 have been cloned, overproduced and purified in large amounts in Escherichia coli. A complex of Fe65-PTB2 with the C-terminal 32 amino acids of the AICD gave well diffracting hexagonal crystals and data have been collected to 2.1 Å resolution. Initial phases obtained by the molecular-replacement method are of good quality and revealed well defined electron density for the substrate peptide.

Monomeric Amyloid Beta Peptide in Hexafluoroisopropanol Detected by Small Angle Neutron Scattering.

Directory of Open Access Journals (Sweden)

Bo Zhang-Haagen

Full Text Available Small proteins like amyloid beta (Aβ monomers are related to neurodegenerative disorders by aggregation to insoluble fibrils. Small angle neutron scattering (SANS is a nondestructive method to observe the aggregation process in solution. We show that SANS is able to resolve monomers of small molecular weight like Aβ for aggregation studies. We examine Aβ monomers after prolonged storing in d-hexafluoroisopropanol (dHFIP by using SANS and dynamic light scattering (DLS. We determined the radius of gyration from SANS as 1.0±0.1 nm for Aβ1-40 and 1.6±0.1 nm for Aβ1-42 in agreement with 3D NMR structures in similar solvents suggesting a solvent surface layer with 5% increased density. After initial dissolution in dHFIP Aβ aggregates sediment with a major component of pure monomers showing a hydrodynamic radius of 1.8±0.3 nm for Aβ1-40 and 3.2±0.4 nm for Aβ1-42 including a surface layer of dHFIP solvent molecules.

Specific recognition of the C-terminal end of A beta 42 by a high affinity monoclonal antibody

DEFF Research Database (Denmark)

Axelsen, Trine Veje; Holm, Arne; Birkelund, Svend

2009-01-01

The neurotoxic peptide A beta(42) is derived from the amyloid precursor protein by proteolytic cleavage and is deposited in the brain of patients suffering from Alzheimer's disease (AD). In this study we generate a high affinity monoclonal antibody that targets the C-terminal end of A beta(42......) with high specificity. By this is meant that the paratope of the antibody must enclose the C-terminal end of A beta(42) including the carboxy-group of amino acid 42, and not just recognize a linear epitope in the C-terminal part of A beta. This has been accomplished by using a unique antigen construct made...... by the Ligand Presenting Assembly technology (LPA technology). This strategy results in dimeric presentation of the free C-terminal end of A beta(42). The generated Mab A beta1.1 is indeed specific for the C-terminal end of A beta(42) to which it binds with high affinity. Mab A beta1.1 recognizes the epitope...

High plasma levels of islet amyloid polypeptide in young with new-onset of type 1 diabetes mellitus.

Directory of Open Access Journals (Sweden)

Johan F Paulsson

Full Text Available AIMS/HYPOTHESIS: Islet amyloid polypeptide (IAPP is a beta cell hormone secreted together with insulin upon glucose stimulation. IAPP participates in normal glucose regulation, but IAPP is also known for its ability to misfold and form islet amyloid. Amyloid fibrils form through smaller cell toxic intermediates and deposited amyloid disrupts normal islet architecture. Even though IAPP and amyloid formation are much discussed in type 2 diabetes, our aim was to study the significance of IAPP in type 1 diabetes. RESULTS: Plasma IAPP levels in children and adolescents with newly diagnosed type 1 diabetes (n = 224 were analysed and concentrations exceeding 100 pmol/L (127.2-888.7 pmol/L were found in 11% (25/224. The IAPP increase did not correlate with C-peptide levels. CONCLUSIONS/INTERPRETATION: Plasma levels of IAPP and insulin deviate in a subpopulation of young with newly-diagnosed type 1 diabetes. The determined elevated levels of IAPP might increase the risk for IAPP misfolding and formation of cell toxic amyloid in beta cells. This finding add IAPP-aggregation to the list over putative pathological factors causing type 1 diabetes.

Neuroprotective Effect of Fisetin Against Amyloid-Beta-Induced Cognitive/Synaptic Dysfunction, Neuroinflammation, and Neurodegeneration in Adult Mice.

Science.gov (United States)

Ahmad, Ashfaq; Ali, Tahir; Park, Hyun Young; Badshah, Haroon; Rehman, Shafiq Ur; Kim, Myeong Ok

2017-04-01

Alzheimer's disease (AD) is a devastating and progressive neurodegenerative disease and is characterized pathologically by the accumulation of amyloid beta (Aβ) and the hyperphosphorylation of tau proteins in the brain. The deposition of Aβ aggregates triggers synaptic dysfunction, hyperphosphorylation of tau, and neurodegeneration, which lead to cognitive disorders. Here, we investigated the neuroprotective effect of fisetin in the Aβ 1-42 mouse model of AD. Single intracerebroventricular injections of Aβ 1-42 (3 μl/5 min/mouse) markedly induced memory/synaptic deficits, neuroinflammation, and neurodegeneration. Intraperitoneal injections of fisetin at a dose of 20 mg/kg/day for 2 weeks starting 24 h after Aβ 1-42 injection significantly decreased the Aβ 1-42 -induced accumulation of Aβ, BACE-1 expression, and hyperphosphorylation of tau protein at serine 413. Fisetin treatment also markedly reversed Aβ 1-42 -induced synaptic dysfunction by increasing the levels of both presynaptic (SYN and SNAP-25) and postsynaptic proteins (PSD-95, SNAP-23, p-GluR1 (Ser 845), p-CREB (Ser 133) and p-CAMKII (Thr 286) and ultimately improved mouse memory, as observed in the Morris water maze test. Fisetin significantly activated p-PI3K, p-Akt (Ser 473), and p-GSK3β (Ser 9) expression in Aβ 1-42 -treated mice. Moreover, fisetin prevented neuroinflammation by suppressing various activated neuroinflammatory mediators and gliosis; it also suppressed the apoptotic neurodegeneration triggered by Aβ 1-42 injections in the mouse hippocampus. Fluorojade-B and immunohistochemical staining for caspase-3 revealed that fisetin prevented neurodegeneration in Aβ 1-42 -treated mice. Our results suggest that fisetin has a potent neuroprotective effect against Aβ 1-42 -induced neurotoxicity. These results demonstrate that polyphenolic flavonoids such as fisetin could be a beneficial, effective and safe neuroprotective agent for preventing neurological disorders such as AD.

Amyloid-beta aggregates cause alterations of astrocytic metabolic phenotype: impact on neuronal viability

OpenAIRE

Allaman, Igor; Gavillet, Mathilde; Bélanger, Mireille; Laroche, Thierry; Viertl, David; Lashuel, Hilal A.; Magistretti, Pierre J.

2010-01-01

Amyloid-beta (Abeta) peptides play a key role in the pathogenesis of Alzheimer's disease and exert various toxic effects on neurons; however, relatively little is known about their influence on glial cells. Astrocytes play a pivotal role in brain homeostasis, contributing to the regulation of local energy metabolism and oxidative stress defense, two aspects of importance for neuronal viability and function. In the present study, we explored the effects of Abeta peptides on glucose metabolism ...

Distinct prion-like strains of amyloid beta implicated in phenotypic diversity of Alzheimer's disease.

Science.gov (United States)

Cohen, Mark; Appleby, Brian; Safar, Jiri G

2016-01-01

Vast evidence on human prions demonstrates that variable disease phenotypes, rates of propagation, and targeting of distinct brain structures are determined by unique conformers (strains) of pathogenic prion protein (PrP(Sc)). Recent progress in the development of advanced biophysical tools that inventory structural characteristics of amyloid beta (Aβ) in the brain cortex of phenotypically diverse Alzheimer's disease (AD) patients, revealed unique spectrum of oligomeric particles in the cortex of rapidly progressive cases, implicating these structures in variable rates of propagation in the brain, and in distict disease manifestation. Since only ∼30% of phenotypic diversity of AD can be explained by polymorphisms in risk genes, these and transgenic bioassay data argue that structurally distinct Aβ particles play a major role in the diverse pathogenesis of AD, and may behave as distinct prion-like strains encoding diverse phenotypes. From these observations and our growing understanding of prions, there is a critical need for new strain-specific diagnostic strategies for misfolded proteins causing these elusive disorders. Since targeted drug therapy can induce mutation and evolution of prions into new strains, effective treatments of AD will require drugs that enhance clearance of pathogenic conformers, reduce the precursor protein, or inhibit the conversion of precursors into prion-like states.

The amyloid precursor-like protein (APLP) gene maps to the long arm of human chromosome 19

Energy Technology Data Exchange (ETDEWEB)

Wasco, W.; Tanzi, R.E. (Harvard Medical School, Boston, MA (United States)); Brook, J.D. (Center for Medical Genetics, Nottingham (United Kingdom))

1993-01-01

We have recently isolated a cDNA from a mouse brain library that encodes a protein whose predicted amino acid sequence is 42% identical and 64% similar to that of the amyloid [beta] protein precursor (APP; 16). This 653-amino-acid amyloid precursor-like protein (APLP) is similar to APP in overall structure as well as amino acid sequence. The amino acid homologies are particularly strong in three distinct regions of the proteins where the identities are 47, 54, and 56% (16). All three of these regions are also conserved in the Drosophila APP-like gene, APPL (11). Notably, 12 cysteine residues and a N -glyco-sylation site are conserved in the extracellular portion of APLP and APP, and a clathrin-binding domain is conserved in the cytoplasmic domain. The cytoplasmic domain is also conserved in a partial CDNA reported to encode an APP-like gene in rat testes (17), These data suggest that APLP and APP are members of a highly conserved gene family. A panel of DNAs from 31 human-rodent somatic cell lines of known karyotype was digested with EcoR1. These DNAs were then probed with the human APLP cDNA clone and the hybridization pattern was consistent with the assignment of the APLP locus to chromosome 19. 17 refs., 1 fig.

A Drosophila gene encoding a protein resembling the human β-amyloid protein precursor

International Nuclear Information System (INIS)

Rosen, D.R.; Martin-Morris, L.; Luo, L.; White, K.

1989-01-01

The authors have isolated genomic and cDNA clones for a Drosophila gene resembling the human β-amyloid precursor protein (APP). This gene produces a nervous system-enriched 6.5-kilobase transcript. Sequencing of cDNAs derived from the 6.5-kilobase transcript predicts an 886-amino acid polypeptide. This polypeptide contains a putative transmembrane domain and exhibits strong sequence similarity to cytoplasmic and extracellular regions of the human β-amyloid precursor protein. There is a high probability that this Drosophila gene corresponds to the essential Drosophila locus vnd, a gene required for embryonic nervous system development

Is verbal episodic memory in elderly with amyloid deposits preserved through altered neuronal function?

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Ossenkoppele, Rik; Madison, Cindee; Oh, Hwamee; Wirth, Miranka; van Berckel, Bart N M; Jagust, William J

2014-08-01

A potential mechanism that enables intellectual preservation in cognitively normal elderly that harbor beta-amyloid (Aβ) pathology is heightened cerebral glucose metabolism. To investigate cross-sectional inter-relationships between Aβ, glucose metabolism, and cognition, 81 subjects (mean age: 75 ± 7 years) underwent [(11)C]Pittsburgh Compound-B and [(18)F]fluorodeoxyglucose positron emission tomography scans and neuropsychological testing. They were divided into low-Aβ (n = 53), intermediate-Aβ (n = 13) and high-Aβ (n = 15) groups as defined by their global cortical [(11)C]PIB retention. Glucose metabolism was assessed using a MetaROI mask that covers metabolically critical regions in Alzheimer's disease (AD) (i.e., posterior cingulate and bilateral angular and inferior temporal gyri). Previously validated factor scores for verbal and visual episodic memory, semantic memory, working memory, and executive functioning were used to evaluate cognitive performances. Greater Aβ deposition in the precuneus was associated with higher metabolic activity (at trend level) and lower visual episodic memory scores. Glucose metabolism did not correlate with cognition across all subjects. However, heightened metabolic activity was associated with better verbal episodic memory performance in subjects with elevated amyloid levels. This preliminary study suggests that neural compensation, as a manifestation of brain reserve, enables elderly supposedly on the path to AD, at least temporarily, to preserve cognitive function. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

IMPY, a potential β-amyloid imaging probe for detection of prion deposits in scrapie-infected mice

International Nuclear Information System (INIS)

Song, P.-J.; Bernard, Serge; Sarradin, Pierre; Vergote, Jackie; Barc, Celine; Chalon, Sylvie; Kung, M.-P.; Kung, Hank F.; Guilloteau, Denis

2008-01-01

Introduction: A potential single-photon emission computed tomography imaging agent for labeling of Aβ plaques of Alzheimer's disease, IMPY (2-(4'-dimethylaminophenyl)-6-iodo-imidazo[1,2-a]pyridine), would be effective in detection of prion amyloid deposits in transmissible spongiform encephalopathies (TSEs). Methods: In vitro autoradiographic studies were carried out with [ 125 I]IMPY on brain sections from scrapie-infected mice and age-matched controls. Competition study was performed to evaluate the prion deposit binding specificity with nonradioactive IMPY. Results: Binding of [ 125 I]IMPY was observed in infected brain sections, while on age-matched control brain sections, there was no or very low labeling. Prion deposit binding was confirmed by histoblots with prion protein-specific monoclonal antibody 2D6. In the presence of nonradioactive IMPY, the binding of [ 125 I]IMPY was significantly inhibited in all regions studied. Conclusions: These findings indicate that IMPY can detect the prion deposits in vitro in scrapie-infected mice. Labeled with 123 I, this ligand may be useful to quantitate prion deposit burdens in TSEs by in vivo imaging

Gold Nanoparticles and Microwave Irradiation Inhibit Beta-Amyloid Amyloidogenesis

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Bastus Neus

2008-01-01

Full Text Available Abstract Peptide-Gold nanoparticles selectively attached to β-amyloid protein (Aβ amyloidogenic aggregates were irradiated with microwave. This treatment produces dramatic effects on the Aβ aggregates, inhibiting both the amyloidogenesis and the restoration of the amyloidogenic potential. This novel approach offers a new strategy to inhibit, locally and remotely, the amyloidogenic process, which could have application in Alzheimer’s disease therapy. We have studied the irradiation effect on the amyloidogenic process in the presence of conjugates peptide-nanoparticle by transmission electronic microscopy observations and by Thioflavine T assays to quantify the amount of fibrils in suspension. The amyloidogenic aggregates rather than the amyloid fibrils seem to be better targets for the treatment of the disease. Our results could contribute to the development of a new therapeutic strategy to inhibit the amyloidogenic process in Alzheimer’s disease.

A subcutaneous cellular implant for passive immunization against amyloid-β reduces brain amyloid and tau pathologies.

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Lathuilière, Aurélien; Laversenne, Vanessa; Astolfo, Alberto; Kopetzki, Erhard; Jacobsen, Helmut; Stampanoni, Marco; Bohrmann, Bernd; Schneider, Bernard L; Aebischer, Patrick

2016-05-01

Passive immunization against misfolded toxic proteins is a promising approach to treat neurodegenerative disorders. For effective immunotherapy against Alzheimer's disease, recent clinical data indicate that monoclonal antibodies directed against the amyloid-β peptide should be administered before the onset of symptoms associated with irreversible brain damage. It is therefore critical to develop technologies for continuous antibody delivery applicable to disease prevention. Here, we addressed this question using a bioactive cellular implant to deliver recombinant anti-amyloid-β antibodies in the subcutaneous tissue. An encapsulating device permeable to macromolecules supports the long-term survival of myogenic cells over more than 10 months in immunocompetent allogeneic recipients. The encapsulated cells are genetically engineered to secrete high levels of anti-amyloid-β antibodies. Peripheral implantation leads to continuous antibody delivery to reach plasma levels that exceed 50 µg/ml. In a proof-of-concept study, we show that the recombinant antibodies produced by this system penetrate the brain and bind amyloid plaques in two mouse models of the Alzheimer's pathology. When encapsulated cells are implanted before the onset of amyloid plaque deposition in TauPS2APP mice, chronic exposure to anti-amyloid-β antibodies dramatically reduces amyloid-β40 and amyloid-β42 levels in the brain, decreases amyloid plaque burden, and most notably, prevents phospho-tau pathology in the hippocampus. These results support the use of encapsulated cell implants for passive immunotherapy against the misfolded proteins, which accumulate in Alzheimer's disease and other neurodegenerative disorders. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Astrocytosis precedes amyloid plaque deposition in Alzheimer APPswe transgenic mouse brain: a correlative positron emission tomography and in vitro imaging study

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Rodriguez-Vieitez, Elena; Ni, Ruiqing; Voytenko, Larysa; Marutle, Amelia [Karolinska Institutet, Division of Translational Alzheimer Neurobiology, Centre for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Stockholm (Sweden); Gulyas, Balazs; Halldin, Christer [Karolinska Institutet, Centre for Psychiatric Research, Department of Clinical Neuroscience, Stockholm (Sweden); Nanyang Technological University, NTU - Imperial College, Lee Kong Chian School of Medicine, Singapore (Singapore); Toth, Miklos; Haeggkvist, Jenny [Karolinska Institutet, Centre for Psychiatric Research, Department of Clinical Neuroscience, Stockholm (Sweden); Nordberg, Agneta [Karolinska Institutet, Division of Translational Alzheimer Neurobiology, Centre for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Stockholm (Sweden); Karolinska University Hospital Huddinge, Department of Geriatric Medicine, Stockholm (Sweden)

2015-04-17

Pathological studies suggest that neuroinflammation is exacerbated by increased beta-amyloid (Aβ) levels in the brain early in Alzheimer's disease (AD). The time course and relationships between astrocytosis and Aβ deposition were examined using multitracer in vivo positron emission tomography (PET) imaging in an AD transgenic mouse model, followed by postmortem autoradiography and immunohistochemistry analysis. PET imaging with the amyloid plaque tracer {sup 11}C-AZD2184 and the astroglial tracer {sup 11}C-deuterium-L-deprenyl ({sup 11}C-DED) was carried out in APPswe mice aged 6, 8-15 and 18-24 months (4-6 animals/group) and in wild-type (wt) mice aged 8-15 and 18-24 months (3-6 animals/group). Tracer uptake was quantified by region of interest analysis using PMOD software and a 3-D digital mouse brain atlas. Postmortem brain tissues from the same APPswe and wt mice in all age groups were analysed for Aβ deposition and astrocytosis by in vitro autoradiography using {sup 3}H-AZD2184, {sup 3}H-Pittsburgh compound B (PIB) and {sup 3}H-L-deprenyl and immunostaining performed with antibodies for Aβ{sub 42} and glial fibrillary acidic protein (GFAP) in sagittal brain sections. {sup 11}C-AZD2184 PET retention in the cerebral cortices of APPswe mice was significantly higher at 18-24 months than in age-matched wt mice. Cortical and hippocampal {sup 11}C-DED PET binding was significantly higher at 6 months than at 8-15 months or 18-24 months in APPswe mice, and it was also higher than at 8-15 months in wt mice. In vitro autoradiography {sup 3}H-AZD2184 and {sup 3}H-PIB binding confirmed the in vivo findings with {sup 11}C-AZD2184 and demonstrated age-dependent increases in Aβ deposition in APPswe cortex and hippocampus. There were no significant differences between APPswe and wt mice in {sup 3}H-L-deprenyl autoradiography binding across age groups. Immunohistochemical quantification demonstrated more Aβ{sub 42} deposits in the cortex and hippocampus and more

Bioassay-Guided Isolation of Neuroprotective Compounds from Uncaria rhynchophylla against Beta-Amyloid-Induced Neurotoxicity.

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Xian, Yan-Fang; Lin, Zhi-Xiu; Mao, Qing-Qiu; Hu, Zhen; Zhao, Ming; Che, Chun-Tao; Ip, Siu-Po

2012-01-01

Uncaria rhynchophylla is a component herb of many Chinese herbal formulae for the treatment of neurodegenerative diseases. Previous study in our laboratory has demonstrated that an ethanol extract of Uncaria rhynchophylla ameliorated cognitive deficits in a mouse model of Alzheimer's disease induced by D-galactose. However, the active ingredients of Uncaria rhynchophylla responsible for the anti-Alzheimer's disease activity have not been identified. This study aims to identify the active ingredients of Uncaria rhynchophylla by a bioassay-guided fractionation approach and explore the acting mechanism of these active ingredients by using a well-established cellular model of Alzheimer's disease, beta-amyloid- (Aβ-) induced neurotoxicity in PC12 cells. The results showed that six alkaloids, namely, corynoxine, corynoxine B, corynoxeine, isorhynchophylline, isocorynoxeine, and rhynchophylline were isolated from the extract of Uncaria rhynchophylla. Among them, rhynchophylline and isorhynchophylline significantly decreased Aβ-induced cell death, intracellular calcium overloading, and tau protein hyperphosphorylation in PC12 cells. These results suggest that rhynchophylline and isorhynchophylline are the major active ingredients responsible for the protective action of Uncaria rhynchophylla against Aβ-induced neuronal toxicity, and their neuroprotective effect may be mediated, at least in part, by inhibiting intracellular calcium overloading and tau protein hyperphosphorylation.

Thermal Stability Threshold for Amyloid Formation in Light Chain Amyloidosis

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Tanya L. Poshusta

2013-11-01

Full Text Available Light chain (AL amyloidosis is a devastating disease characterized by amyloid deposits formed by immunoglobulin light chains. Current available treatments involve conventional chemotherapy and autologous stem cell transplant. We have recently concluded a phase III trial comparing these two treatments. AL amyloidosis patients who achieve hematological complete response (CR do not necessarily achieve organ response regardless of the treatment they received. In order to investigate the possible correlation between amyloid formation kinetics and organ response, we selected AL amyloidosis patients from the trial with kidney involvement and CR after treatment. Six patients were selected and their monoclonal immunoglobulin light chains were characterized. The proteins showed differences in their stability and their kinetics of amyloid formation. A correlation was detected at pH 7.4, showing that less stable proteins are more likely to form amyloid fibrils. AL-T03 is too unstable to form amyloid fibrils at pH 7.4. This protein was found in the only patient in the study that had organ response, suggesting that partially folded species are required for amyloid formation to occur in AL amyloidosis.

Functional amyloids in bacteria.

Science.gov (United States)

Romero, Diego; Kolter, Roberto

2014-06-01

The term amyloidosis is used to refer to a family of pathologies altering the homeostasis of human organs. Despite having a name that alludes to starch content, the amyloid accumulations are made up of proteins that polymerize as long and rigid fibers. Amyloid proteins vary widely with respect to their amino acid sequences but they share similarities in their quaternary structure; the amyloid fibers are enriched in β-sheets arranged perpendicular to the axis of the fiber. This structural feature provides great robustness, remarkable stability, and insolubility. In addition, amyloid proteins specifically stain with certain dyes such as Congo red and thioflavin-T. The aggregation into amyloid fibers, however, it is not restricted to pathogenic processes, rather it seems to be widely distributed among proteins and polypeptides. Amyloid fibers are present in insects, fungi and bacteria, and they are important in maintaining the homeostasis of the organism. Such findings have motivated the use of the term "functional amyloid" to differentiate these amyloid proteins from their toxic siblings. This review focuses on systems that have evolved in bacteria that control the expression and assembly of amyloid proteins on cell surfaces, such that the robustness of amyloid proteins are used towards a beneficial end. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

The pathogenic implication of abnormal interaction between apolipoprotein E isoforms, amyloid-beta peptides, and sulfatides in Alzheimer's disease.

Science.gov (United States)

Han, Xianlin

2010-06-01

Alzheimer's disease (AD) is the most common cause of dementia in the aging population. Prior work has shown that the epsilon4 allele of apolipoprotein E (apoE4) is a major risk factor for "sporadic" AD, which accounts for >99% of AD cases without a defined underlying mechanism. Recently, we have demonstrated that sulfatides are substantially and specifically depleted at the very early stage of AD. To identify the mechanism(s) of sulfatide loss concurrent with AD onset, we have found that: (1) sulfatides are specifically associated with apoE-associated particles in cerebrospinal fluid (CSF); (2) apoE modulates cellular sulfatide levels; and (3) the modulation of sulfatide content is apoE isoform dependent. These findings not only lead to identification of the potential mechanisms underlying sulfatide depletion at the earliest stages of AD but also serve as mechanistic links to explain the genetic association of apoE4 with AD. Moreover, our recent studies further demonstrated that (1) apoE mediates sulfatide depletion in amyloid-beta precursor protein transgenic mice; (2) sulfatides enhance amyloid beta (Abeta) peptides binding to apoE-associated particles; (3) Abeta42 content notably correlates with sulfatide content in CSF; (4) sulfatides markedly enhance the uptake of Abeta peptides; and (5) abnormal sulfatide-facilitated Abeta uptake results in the accumulation of Abeta in lysosomes. Collectively, our studies clearly provide a link between apoE, Abeta, and sulfatides in AD and establish a foundation for the development of effective therapeutic interventions for AD.

Calumenin interacts with serum amyloid P component

DEFF Research Database (Denmark)

Vorum, H; Jacobsen, Christian; Honoré, Bent

2000-01-01

We recently reported the identification of human calumenin, a novel Ca(2+) binding, transformation-sensitive and secreted protein [Vorum et al. (1998) Biochim. Biophys. Acta 1386, 121-131; Vorum et al. (1999) Exp. Cell Res. 248, 473-481] belonging to the family of multiple EF-hand proteins...... with calumenin in the presence of Ca(2+). Amino acid sequencing identified this protein as serum amyloid P component (SAP). Furthermore, we verified and characterized the calumenin-SAP interaction by the surface plasmon resonance technique. The findings indicate that calumenin may participate...... in the immunological defense system and could be involved in the pathological process of amyloidosis that leads to formation of amyloid deposits seen in different types of tissues. Udgivelsesdato: 2000-Jan-14...

Dissociation between brain amyloid deposition and metabolism in early mild cognitive impairment.

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Liyong Wu

Full Text Available The hypothetical model of dynamic biomarkers for Alzheimer's disease (AD describes high amyloid deposition and hypometabolism at the mild cognitive impairment (MCI stage. However, it remains unknown whether brain amyloidosis and hypometabolism follow the same trajectories in MCI individuals. We used the concept of early MCI (EMCI and late MCI (LMCI as defined by the Alzheimer's disease Neuroimaging Initiative (ADNI-Go in order to compare the biomarker profile between EMCI and LMCI.To examine the global and voxel-based neocortical amyloid burden and metabolism among individuals who are cognitively normal (CN, as well as those with EMCI, LMCI and mild AD.In the present study, 354 participants, including CN (n = 109, EMCI (n = 157, LMCI (n = 39 and AD (n = 49, were enrolled between September 2009 and November 2011 through ADNI-GO and ADNI-2. Brain amyloid load and metabolism were estimated using [(18F]AV45 and [(18F]fluorodeoxyglucose ([(18F]FDG PET, respectively. Uptake ratio images of [(18F]AV45 and [(18F]FDG were calculated by dividing the summed PET image by the median counts of the grey matter of the cerebellum and pons, respectively. Group differences of global [(18F]AV45 and [(18F]FDG were analyzed using ANOVA, while the voxel-based group differences were estimated using statistic parametric mapping (SPM.EMCI patients showed higher global [(18F]AV45 retention compared to CN and lower uptake compared to LMCI. SPM detected higher [(18F]AV45 uptake in EMCI compared to CN in the precuneus, posterior cingulate, medial and dorsal lateral prefrontal cortices, bilaterally. EMCI showed lower [(18F]AV45 retention than LMCI in the superior temporal, inferior parietal, as well as dorsal lateral prefrontal cortices, bilaterally. Regarding to the global [(18F]FDG, EMCI patients showed no significant difference from CN and a higher uptake ratio compared to LMCI. At the voxel level, EMCI showed higher metabolism in precuneus, hippocampus, entorhinal and

Role of CC chemokines (macrophage inflammatory protein-1 beta, monocyte chemoattractant protein-1, RANTES) in acute lung injury in rats

DEFF Research Database (Denmark)

Bless, N M; Huber-Lang, M; Guo, R F

2000-01-01

The role of the CC chemokines, macrophage inflammatory protein-1 beta (MIP-1 beta), monocyte chemotactic peptide-1 (MCP-1), and RANTES, in acute lung inflammatory injury induced by intrapulmonary deposition of IgG immune complexes injury in rats was determined. Rat MIP-1 beta, MCP-1, and RANTES...... were cloned, the proteins were expressed, and neutralizing Abs were developed. mRNA and protein expression for MIP-1 beta and MCP-1 were up-regulated during the inflammatory response, while mRNA and protein expression for RANTES were constitutive and unchanged during the inflammatory response....... Treatment of rats with anti-MIP-1 beta Ab significantly decreased vascular permeability by 37% (p = 0.012), reduced neutrophil recruitment into lung by 65% (p = 0.047), and suppressed levels of TNF-alpha in bronchoalveolar lavage fluids by 61% (p = 0.008). Treatment of rats with anti-rat MCP-1 or anti...

Massive accumulation of luminal protease-deficient axonal lysosomes at Alzheimer's disease amyloid plaques.

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Gowrishankar, Swetha; Yuan, Peng; Wu, Yumei; Schrag, Matthew; Paradise, Summer; Grutzendler, Jaime; De Camilli, Pietro; Ferguson, Shawn M

2015-07-14

Through a comprehensive analysis of organellar markers in mouse models of Alzheimer's disease, we document a massive accumulation of lysosome-like organelles at amyloid plaques and establish that the majority of these organelles reside within swollen axons that contact the amyloid deposits. This close spatial relationship between axonal lysosome accumulation and extracellular amyloid aggregates was observed from the earliest stages of β-amyloid deposition. Notably, we discovered that lysosomes that accumulate in such axons are lacking in multiple soluble luminal proteases and thus are predicted to be unable to efficiently degrade proteinaceous cargos. Of relevance to Alzheimer's disease, β-secretase (BACE1), the protein that initiates amyloidogenic processing of the amyloid precursor protein and which is a substrate for these proteases, builds up at these sites. Furthermore, through a comparison between the axonal lysosome accumulations at amyloid plaques and neuronal lysosomes of the wild-type brain, we identified a similar, naturally occurring population of lysosome-like organelles in neuronal processes that is also defined by its low luminal protease content. In conjunction with emerging evidence that the lysosomal maturation of endosomes and autophagosomes is coupled to their retrograde transport, our results suggest that extracellular β-amyloid deposits cause a local impairment in the retrograde axonal transport of lysosome precursors, leading to their accumulation and a blockade in their further maturation. This study both advances understanding of Alzheimer's disease brain pathology and provides new insights into the subcellular organization of neuronal lysosomes that may have broader relevance to other neurodegenerative diseases with a lysosomal component to their pathology.

Staphylococcal Bap Proteins Build Amyloid Scaffold Biofilm Matrices in Response to Environmental Signals.

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Agustina Taglialegna

2016-06-01

Full Text Available Biofilms are communities of bacteria that grow encased in an extracellular matrix that often contains proteins. The spatial organization and the molecular interactions between matrix scaffold proteins remain in most cases largely unknown. Here, we report that Bap protein of Staphylococcus aureus self-assembles into functional amyloid aggregates to build the biofilm matrix in response to environmental conditions. Specifically, Bap is processed and fragments containing at least the N-terminus of the protein become aggregation-prone and self-assemble into amyloid-like structures under acidic pHs and low concentrations of calcium. The molten globule-like state of Bap fragments is stabilized upon binding of the cation, hindering its self-assembly into amyloid fibers. These findings define a dual function for Bap, first as a sensor and then as a scaffold protein to promote biofilm development under specific environmental conditions. Since the pH-driven multicellular behavior mediated by Bap occurs in coagulase-negative staphylococci and many other bacteria exploit Bap-like proteins to build a biofilm matrix, the mechanism of amyloid-like aggregation described here may be widespread among pathogenic bacteria.

Formation of a stable oligomer of beta-2 microglobulin requires only transient encounter with Cu(II).

Science.gov (United States)

Calabrese, Matthew F; Miranker, Andrew D

2007-03-16

Beta-2 Microglobulin (beta2m) is a small, globular protein, with high solubility under conditions comparable to human serum. A complication of hemodialysis in renal failure patients is the deposition of unmodified beta2m as amyloid fibers. In vitro, exposure of beta2m to equimolar Cu(2+) under near-physiological conditions can result in self-association leading to amyloid fiber formation. Previously, we have shown that the early steps in this process involve a catalyzed structural rearrangement followed by formation of discrete oligomers. These oligomers, however, have a continued requirement for Cu(2+) while mature fibers are resistant to addition of metal chelate. Here, we report that the transition from Cu(2+) dependent to chelate resistant states occurs in the context of small oligomers, dimeric to hexameric in size. These species require Cu(2+) to form, but once generated, do not need metal cation for stability. Importantly, this transition occurs gradually over several days and the resulting oligomers are isolatable and kinetically stable on timescales exceeding weeks. In addition, formation is enhanced by levels of urea similar to those found in hemodialysis patients. Our results are consistent with our hypothesis that transient encounter of full-length wild-type beta2m with transition metal cation at the dialysis membrane interface is causal to dialysis related amyloidosis.

Spectroscopic study of Alzheimer's amyloid fibrils using terahertz time domain spectroscopy

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Jung, Euna; Kim, Jeonghoi; Han, Younho; Moon, Kiwon; Lim, Meehyun; Han, Haewook; Park, Joonhyuck; Kim, Sungjee [POSTECH, Pohang (Korea, Republic of)

2008-11-15

Alzheimer's disease, one of the most common neurodegenerative diseases, is characterized by extensive amyloid deposition. Amyloid deposits contain the abundant fibrils formed by amyloid β protein (Aβ). Because amyloid fibrils are associated with amyloid diseases, including Alzheimer's disease, type 2 diabetes, prion disease, Parkinson's disease, senile systemic amyloidosis and Huntington's disease, there has been considerable interest within the biomedical and biochemical research communities. In transmission electron microscopic (TEM)images, amyloid firils are 0.1∼10μm long and approximately 10nm wide. Amyloid fibrils commonly exhibit self assembled filaments, often described as twisted or parallel assemblies of finer protofilaments. They are formed by the spontaneous aggregation of a wide variety of peptides and proteins. Structural studies of amyloid fibrils have revealed that the common structural motif of virtually all amyloid fibrils consists of cross β sheets in which the peptide strands are arranged perpendicular to the long axis of the fiber. But little was known until recently about the molecular level structures of amyloid fibils. Therefore, spectroscopic investigation of both amyloid fibrils and Aβ at the molecular level can provide the significant evidence for the molecular understanding of amyloidogenesis and for the development of innovative therapeutic and diagnostic approaches. We used terahertz time domain spectroscopy (THz TDS)to investigate both Aβ and amyloid fibril. THz TDS, developed over the last two decades, is a powerful tool to extract the properties of biomaterials and provides unique spectral signatures of biomolecules within 0.1∼10THz, which exists between microwave and infrared frequency range. Current interest in THz radiation arises from its capability of probing the delocalized collective vibrational modes in proteins. Studying the collective modes of proteins in THz frequency range can play an

Small heat shock proteins potentiate amyloid dissolution by protein disaggregases from yeast and humans.

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Martin L Duennwald

Full Text Available How small heat shock proteins (sHsps might empower proteostasis networks to control beneficial prions or disassemble pathological amyloid is unknown. Here, we establish that yeast sHsps, Hsp26 and Hsp42, inhibit prionogenesis by the [PSI+] prion protein, Sup35, via distinct and synergistic mechanisms. Hsp42 prevents conformational rearrangements within molten oligomers that enable de novo prionogenesis and collaborates with Hsp70 to attenuate self-templating. By contrast, Hsp26 inhibits self-templating upon binding assembled prions. sHsp binding destabilizes Sup35 prions and promotes their disaggregation by Hsp104, Hsp70, and Hsp40. In yeast, Hsp26 or Hsp42 overexpression prevents [PSI+] induction, cures [PSI+], and potentiates [PSI+]-curing by Hsp104 overexpression. In vitro, sHsps enhance Hsp104-catalyzed disaggregation of pathological amyloid forms of α-synuclein and polyglutamine. Unexpectedly, in the absence of Hsp104, sHsps promote an unprecedented, gradual depolymerization of Sup35 prions by Hsp110, Hsp70, and Hsp40. This unanticipated amyloid-depolymerase activity is conserved from yeast to humans, which lack Hsp104 orthologues. A human sHsp, HspB5, stimulates depolymerization of α-synuclein amyloid by human Hsp110, Hsp70, and Hsp40. Thus, we elucidate a heretofore-unrecognized human amyloid-depolymerase system that could have applications in various neurodegenerative disorders.

A systematic review of amyloid-beta peptides as putative mediators of the association between affective disorders and Alzheimer's disease

DEFF Research Database (Denmark)

Abbasowa, Leda; Heegaard, N. H. H.

2014-01-01

Background: Affective disorders are associated with an increased occurrence of cognitive deficits and have been linked to cognitive impairment and Alzheimer's disease. The putative molecular mechanisms involved in these associations are however not clear. The aim of this systematic review...... were limited by very low sample numbers. Finally, different assays for amyloid-beta were utilized in the different studies, thus hampering comparisons. Conclusion: To unravel possible risk relations and causalities between affective disorder and Alzheimer's disease and to determine how amyloid...

Amyloid-Beta Induced Changes in Vesicular Transport of BDNF in Hippocampal Neurons

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Bianca Seifert

2016-01-01

Full Text Available The neurotrophin brain derived neurotrophic factor (BDNF is an important growth factor in the CNS. Deficits in transport of this secretory protein could underlie neurodegenerative diseases. Investigation of disease-related changes in BDNF transport might provide insights into the cellular mechanism underlying, for example, Alzheimer’s disease (AD. To analyze the role of BDNF transport in AD, live cell imaging of fluorescently labeled BDNF was performed in hippocampal neurons of different AD model systems. BDNF and APP colocalized with low incidence in vesicular structures. Anterograde as well as retrograde transport of BDNF vesicles was reduced and these effects were mediated by factors released from hippocampal neurons into the extracellular medium. Transport of BDNF was altered at a very early time point after onset of human APP expression or after acute amyloid-beta(1-42 treatment, while the activity-dependent release of BDNF remained unaffected. Taken together, extracellular cleavage products of APP induced rapid changes in anterograde and retrograde transport of BDNF-containing vesicles while release of BDNF was unaffected by transgenic expression of mutated APP. These early transport deficits might lead to permanently impaired brain functions in the adult brain.

Individualized quantification of brain {beta}-amyloid burden: results of a proof of mechanism phase 0 florbetaben PET trial in patients with Alzheimer's disease and healthy controls

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Barthel, Henryk; Luthardt, Julia; Becker, Georg; Patt, Marianne; Sattler, Bernhard; Schildan, Andreas; Hesse, Swen; Meyer, Philipp M.; Sabri, Osama [University of Leipzig, Department of Nuclear Medicine, Leipzig (Germany); Hammerstein, Eva; Hartwig, Kristin; Gertz, Hermann-Josef [University of Leipzig, Department of Psychiatry, Leipzig (Germany); Eggers, Birk [Arzneimittelforschung Leipzig GmbH, Leipzig (Germany); Wolf, Henrike [University of Leipzig, Department of Psychiatry, Leipzig (Germany); University of Zurich, Department of Psychiatry, Zurich (Switzerland); Zimmermann, Torsten; Reischl, Joachim; Rohde, Beate; Reininger, Cornelia [Bayer Healthcare, Berlin (Germany)

2011-09-15

Complementing clinical findings with those generated by biomarkers - such as {beta}-amyloid-targeted positron emission tomography (PET) imaging - has been proposed as a means of increasing overall accuracy in the diagnosis of Alzheimer's disease (AD). Florbetaben ([{sup 18}F]BAY 94-9172) is a novel {beta}-amyloid PET tracer currently in global clinical development. We present the results of a proof of mechanism study in which the diagnostic efficacy, pharmacokinetics, safety and tolerability of florbetaben were assessed. The value of various quantitative parameters derived from the PET scans as potential surrogate markers of cognitive decline was also investigated. Ten patients with mild-moderate probable AD (DSM-IV and NINCDS-ADRDA criteria) and ten age-matched ({>=} 55 years) healthy controls (HCs) were administered a single dose of 300 MBq florbetaben, which contained a tracer mass dose of < 5 {mu}g. The 70-90 min post-injection brain PET data were visually analysed by three blinded experts. Quantitative assessment was also performed via MRI-based, anatomical sampling of predefined volumes of interest (VOI) and subsequent calculation of standardized uptake value (SUV) ratios (SUVRs, cerebellar cortex as reference region). Furthermore, single-case, voxelwise analysis was used to calculate individual ''whole brain {beta}-amyloid load''. Visual analysis of the PET data revealed nine of the ten AD, but only one of the ten HC brains to be {beta}-amyloid positive (p = 0.001), with high inter-reader agreement (weighted kappa {>=} 0.88). When compared to HCs, the neocortical SUVRs were significantly higher in the ADs (with descending order of effect size) in frontal cortex, lateral temporal cortex, occipital cortex, anterior and posterior cingulate cortices, and parietal cortex (p = 0.003-0.010). Voxel-based group comparison confirmed these differences. Amongst the PET-derived parameters, the Statistical Parametric Mapping-based whole brain

Structural and conformational variants of human beta2-microglobulin characterized by capillary electrophoresis and complementary separation methods

DEFF Research Database (Denmark)

Heegaard, Niels H H; Rovatti, Luca; Nissen, Mogens H

2003-01-01

The small (Mr = 11729) serum protein beta2-microglobulin is prone to precipitate as amyloid in a protein conformational disorder (PCD) that occurs in a significant number of patients on chronic hemodialysis. Analyses by capillary electrophoresis (CE) were undertaken to study beta2-microglobulin...

Aggregation properties of a short peptide that mediates amyloid fibril ...

Indian Academy of Sciences (India)

Short peptides have been identified from amyloidogenic proteins that form amyloid fibrils in isolation. The ... proteins. These peptide fibrils have the conformational features of β-structure that .... water and immediately deposited on freshly cleaved surface of mica .... with the peptide via electrostatic interactions. NaCl would.

Interhemispheric EEG differences in olfactory bulbectomized rats with different cognitive abilities and brain beta-amyloid levels.

Science.gov (United States)

Bobkova, Natalia; Vorobyov, Vasily; Medvinskaya, Natalia; Aleksandrova, Irina; Nesterova, Inna

2008-09-26

Alterations in electroencephalogram (EEG) asymmetry and deficits in interhemispheric integration of information have been shown in patients with Alzheimer's disease (AD). However, no direct evidence of an association between EEG asymmetry, morphological markers in the brain, and cognition was found either in AD patients or in AD models. In this study we used rats with bilateral olfactory bulbectomy (OBX) as one of the AD models and measured their learning/memory abilities, brain beta-amyloid levels and EEG spectra in symmetrical frontal and occipital cortices. One year after OBX or sham-surgery, the rats were tested with the Morris water paradigm and assigned to three groups: sham-operated rats, SO, and OBX rats with virtually normal, OBX(+), or abnormal, OBX(-), learning (memory) abilities. In OBX vs. SO, the theta EEG activity was enhanced to a higher extent in the right frontal cortex and in the left occipital cortex. This produced significant interhemispheric differences in the frontal cortex of the OBX(-) rats and in the occipital cortex of both OBX groups. The beta1 EEG asymmetry in SO was attenuated in OBX(+) and completely eliminated in OBX(-). OBX produced highly significant beta2 EEG decline in the right frontal cortex, with OBX(-)>OBX(+) rank order of strength. The beta-amyloid level, examined by post-mortem immunological DOT-analysis in the cortex-hippocampus samples, was about six-fold higher in OBX(-) than in SO, but significantly less (enhanced by 82% vs. SO) in OBX(+) than in OBX(-). The involvement of the brain mediatory systems in the observed EEG asymmetry differences is discussed.

Amyloid Precursor Proteins Are Dynamically Trafficked and Processed During Neuronal Development

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Jenna M. Ramaker

2016-11-01

Full Text Available Proteolytic processing of the Amyloid Precursor Protein (APP produces beta-amyloid (Aβ peptide fragments that accumulate in Alzheimer’s Disease (AD, but APP may also regulate multiple aspects of neuronal development, albeit via mechanisms that are not well understood. APP is a member of a family of transmembrane glycoproteins expressed by all higher organisms, including two mammalian orthologs (APLP1 and APLP2 that have complicated investigations into the specific activities of APP. By comparison, insects express only a single APP-related protein (APP-Like, or APPL that contains the same protein interaction domains identified in APP. However, unlike its mammalian orthologs, APPL is only expressed by neurons, greatly simplifying an analysis of its functions in vivo. Like APP, APPL is processed by secretases to generate a similar array of extracellular and intracellular cleavage fragments, as well as an Aβ-like fragment that can induce neurotoxic responses in the brain. Exploiting the complementary advantages of two insect models (Drosophila melanogaster and Manduca sexta, we have investigated the regulation of APPL trafficking and processing with respect to different aspects of neuronal development. By comparing the behavior of endogenously expressed APPL with fluorescently tagged versions of APPL and APP, we have shown that some full-length protein is consistently trafficked into the most motile regions of developing neurons both in vitro and in vivo. Concurrently, much of the holoprotein is rapidly processed into N- and C-terminal fragments that undergo bi-directional transport within distinct vesicle populations. Unexpectedly, we also discovered that APPL can be transiently sequestered into an amphisome-like compartment in developing neurons, while manipulations targeting APPL cleavage altered their motile behavior in cultured embryos. These data suggest that multiple mechanisms restrict the bioavailability of the holoprotein to regulate

Massive accumulation of luminal protease-deficient axonal lysosomes at Alzheimer’s disease amyloid plaques

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Gowrishankar, Swetha; Yuan, Peng; Wu, Yumei; Schrag, Matthew; Paradise, Summer; Grutzendler, Jaime; De Camilli, Pietro; Ferguson, Shawn M.

2015-01-01

Through a comprehensive analysis of organellar markers in mouse models of Alzheimer’s disease, we document a massive accumulation of lysosome-like organelles at amyloid plaques and establish that the majority of these organelles reside within swollen axons that contact the amyloid deposits. This close spatial relationship between axonal lysosome accumulation and extracellular amyloid aggregates was observed from the earliest stages of β-amyloid deposition. Notably, we discovered that lysosomes that accumulate in such axons are lacking in multiple soluble luminal proteases and thus are predicted to be unable to efficiently degrade proteinaceous cargos. Of relevance to Alzheimer’s disease, β-secretase (BACE1), the protein that initiates amyloidogenic processing of the amyloid precursor protein and which is a substrate for these proteases, builds up at these sites. Furthermore, through a comparison between the axonal lysosome accumulations at amyloid plaques and neuronal lysosomes of the wild-type brain, we identified a similar, naturally occurring population of lysosome-like organelles in neuronal processes that is also defined by its low luminal protease content. In conjunction with emerging evidence that the lysosomal maturation of endosomes and autophagosomes is coupled to their retrograde transport, our results suggest that extracellular β-amyloid deposits cause a local impairment in the retrograde axonal transport of lysosome precursors, leading to their accumulation and a blockade in their further maturation. This study both advances understanding of Alzheimer’s disease brain pathology and provides new insights into the subcellular organization of neuronal lysosomes that may have broader relevance to other neurodegenerative diseases with a lysosomal component to their pathology. PMID:26124111

Iron Biochemistry is Correlated with Amyloid Plaque Morphology in an Established Mouse Model of Alzheimer's Disease.

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Telling, Neil D; Everett, James; Collingwood, Joanna F; Dobson, Jon; van der Laan, Gerrit; Gallagher, Joseph J; Wang, Jian; Hitchcock, Adam P

2017-10-19

A signature characteristic of Alzheimer's disease (AD) is aggregation of amyloid-beta (Aβ) fibrils in the brain. Nevertheless, the links between Aβ and AD pathology remain incompletely understood. It has been proposed that neurotoxicity arising from aggregation of the Aβ 1-42 peptide can in part be explained by metal ion binding interactions. Using advanced X-ray microscopy techniques at sub-micron resolution, we investigated relationships between iron biochemistry and AD pathology in intact cortex from an established mouse model over-producing Aβ. We found a direct correlation of amyloid plaque morphology with iron, and evidence for the formation of an iron-amyloid complex. We also show that iron biomineral deposits in the cortical tissue contain the mineral magnetite, and provide evidence that Aβ-induced chemical reduction of iron could occur in vivo. Our observations point to the specific role of iron in amyloid deposition and AD pathology, and may impact development of iron-modifying therapeutics for AD. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Solitary osteosclerotic plasmacytoma: association with demyelinating polyneuropathy and amyloid deposition

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Voss, S.D.; Hall, F.M. [Dept. of Radiology, Beth Israel Deaconess Medical Center, Boston, MA (United States); Harvard Medical School, Boston, MA (United States); Murphey, M.D. [Dept. of Radiologic Pathology, Armed Forces Institute of Pathology, Washington, DC (United States); Dept. of Radiology and Nuclear Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD (United States); Department of Radiology, University of Maryland School of Medicine, Baltimore, Maryland (United States)

2001-09-01

A 51-year-old man presented with a 1-year history of polyneuropathy necessitating the use of a wheelchair. Initial diagnosis was idiopathic chronic inflammatory demyelinating polyneuropathy (CIDP) and associated monoclonal gammopathy. Investigations for multiple myeloma, including bone marrow aspiration and biopsy, were negative. What was initially felt to be an incidental osteosclerotic focus noted on the radiographic bone survey was eventually shown to be a solitary osteosclereotic plasmacytoma with associated amyloid. This dramatically altered treatment. This case emphasizes the importance of including osteosclerotic plasmacytoma in the differential diagnosis of a focal sclerotic bone lesion in the clinical setting of polyneuropathy. These lesions are less likely to progress to multiple myeloma than lytic plasma cell neoplasms, and the presence of polyneuropathy often results in earlier diagnosis and treatment with enhanced prospect of cure. The finding of amyloid deposition within the osteosclerotic lesion may be of prognostic importance. (orig.)

The Common Inhalational Anesthetic Sevoflurane Induces Apoptosis and Increases β-Amyloid Protein Levels

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Dong, Yuanlin; Zhang, Guohua; Zhang, Bin; Moir, Robert D.; Xia, Weiming; Marcantonio, Edward R.; Culley, Deborah J.; Crosby, Gregory; Tanzi, Rudolph E.; Xie, Zhongcong

2009-01-01

Objective: To assess the effects of sevoflurane, the most commonly used inhalation anesthetic, on apoptosis and β-amyloid protein (Aβ) levels in vitro and in vivo. Subjects: Naive mice, H4 human neuroglioma cells, and H4 human neuroglioma cells stably transfected to express full-length amyloid precursor protein. Interventions: Human H4 neuroglioma cells stably transfected to express full-length amyloid precursor protein were exposed to 4.1% sevoflurane for 6 hours. Mice received 2.5% sevoflurane for 2 hours. Caspase-3 activation, apoptosis, and Aβ levels were assessed. Results: Sevoflurane induced apoptosis and elevated levels of β-site amyloid precursor protein-cleaving enzyme and Aβ in vitro and in vivo. The caspase inhibitor Z-VAD decreased the effects of sevoflurane on apoptosis and Aβ. Sevoflurane-induced caspase-3 activation was attenuated by the γ-secretase inhibitor L-685,458 and was potentiated by Aβ. These results suggest that sevoflurane induces caspase activation which, in turn, enhances β-site amyloid precursor protein–cleaving enzyme and Aβ levels. Increased Aβ levels then induce further rounds of apoptosis. Conclusions: These results suggest that inhalational anesthetic sevoflurane may promote Alzheimer disease neuropathogenesis. If confirmed in human subjects, it may be prudent to caution against the use of sevoflurane as an anesthetic, especially in those suspected of possessing excessive levels of cerebral Aβ. PMID:19433662

Transthyretin protects against A-beta peptide toxicity by proteolytic cleavage of the peptide: a mechanism sensitive to the Kunitz protease inhibitor.

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Rita Costa

Full Text Available Alzheimer's disease (AD is a neurodegenerative disorder characterized by the deposition of amyloid beta-peptide (A-Beta in the brain. Transthyretin (TTR is a tetrameric protein of about 55 kDa mainly produced in the liver and choroid plexus of the brain. The known physiological functions of TTR are the transport of thyroid hormone T(4 and retinol, through binding to the retinol binding protein. TTR has also been established as a cryptic protease able to cleave ApoA-I in vitro. It has been described that TTR is involved in preventing A-Beta fibrilization, both by inhibiting and disrupting A-Beta fibrils, with consequent abrogation of toxicity. We further characterized the nature of the TTR/A-Beta interaction and found that TTR, both recombinant or isolated from human sera, was able to proteolytically process A-Beta, cleaving the peptide after aminoacid residues 1, 2, 3, 10, 13, 14,16, 19 and 27, as determined by mass spectrometry, and reversed phase chromatography followed by N-terminal sequencing. A-Beta peptides (1-14 and (15-42 showed lower amyloidogenic potential than the full length counterpart, as assessed by thioflavin binding assay and ultrastructural analysis by transmission electron microscopy. A-Beta cleavage by TTR was inhibited in the presence of an alphaAPP peptide containing the Kunitz Protease Inhibitor (KPI domain but not in the presence of the secreted alphaAPP derived from the APP isoform 695 without the KPI domain. TTR was also able to degrade aggregated forms of A-Beta peptide. Our results confirmed TTR as a protective molecule in AD, and prompted A-Beta proteolysis by TTR as a protective mechanism in this disease. TTR may prove to be a useful therapeutic agent for preventing or retarding the cerebral amyloid plaque formation implicated in AD pathology.

Amyloid cascade hypothesis: Pathogenesis and therapeutic strategies in Alzheimer's disease.

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Barage, Sagar H; Sonawane, Kailas D

2015-08-01

Alzheimer's disease is an irreversible, progressive neurodegenerative disorder. Various therapeutic approaches are being used to improve the cholinergic neurotransmission, but their role in AD pathogenesis is still unknown. Although, an increase in tau protein concentration in CSF has been described in AD, but several issues remains unclear. Extensive and accurate analysis of CSF could be helpful to define presence of tau proteins in physiological conditions, or released during the progression of neurodegenerative disease. The amyloid cascade hypothesis postulates that the neurodegeneration in AD caused by abnormal accumulation of amyloid beta (Aβ) plaques in various areas of the brain. The amyloid hypothesis has continued to gain support over the last two decades, particularly from genetic studies. Therefore, current research progress in several areas of therapies shall provide an effective treatment to cure this devastating disease. This review critically evaluates general biochemical and physiological functions of Aβ directed therapeutics and their relevance. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bioassay-Guided Isolation of Neuroprotective Compounds from Uncaria rhynchophylla against Beta-Amyloid-Induced Neurotoxicity

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Yan-Fang Xian

2012-01-01

Full Text Available Uncaria rhynchophylla is a component herb of many Chinese herbal formulae for the treatment of neurodegenerative diseases. Previous study in our laboratory has demonstrated that an ethanol extract of Uncaria rhynchophylla ameliorated cognitive deficits in a mouse model of Alzheimer’s disease induced by D-galactose. However, the active ingredients of Uncaria rhynchophylla responsible for the anti-Alzheimer’s disease activity have not been identified. This study aims to identify the active ingredients of Uncaria rhynchophylla by a bioassay-guided fractionation approach and explore the acting mechanism of these active ingredients by using a well-established cellular model of Alzheimer’s disease, beta-amyloid- (Aβ- induced neurotoxicity in PC12 cells. The results showed that six alkaloids, namely, corynoxine, corynoxine B, corynoxeine, isorhynchophylline, isocorynoxeine, and rhynchophylline were isolated from the extract of Uncaria rhynchophylla. Among them, rhynchophylline and isorhynchophylline significantly decreased Aβ-induced cell death, intracellular calcium overloading, and tau protein hyperphosphorylation in PC12 cells. These results suggest that rhynchophylline and isorhynchophylline are the major active ingredients responsible for the protective action of Uncaria rhynchophylla against Aβ-induced neuronal toxicity, and their neuroprotective effect may be mediated, at least in part, by inhibiting intracellular calcium overloading and tau protein hyperphosphorylation.

Associations Between β-Amyloid Kinetics and the β-Amyloid Diurnal Pattern in the Central Nervous System.

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Lucey, Brendan P; Mawuenyega, Kwasi G; Patterson, Bruce W; Elbert, Donald L; Ovod, Vitaliy; Kasten, Tom; Morris, John C; Bateman, Randall J

2017-02-01

Recent studies found that the concentration of amyloid-β (Aβ) fluctuates with the sleep-wake cycle. Although the amplitude of this day/night pattern attenuates with age and amyloid deposition, to our knowledge, the association of Aβ kinetics (ie, production, turnover, and clearance) with this oscillation has not been studied. To determine the association between Aβ kinetics, age, amyloid levels, and the Aβ day/night pattern in humans. We measured Aβ concentrations and kinetics in 77 adults aged 60 to 87 years with and without amyloid deposition by a novel precise mass spectrometry method at the Washington University School of Medicine in St Louis, Missouri. We compared findings of 2 orthogonal methods, enzyme-linked immunosorbent assay and mass spectrometry, to validate the day/night patterns and determine more precise estimates of the cosinor parameters. In vivo labeling of central nervous system proteins with stable isotopically labeled leucine was performed, and kinetics of Aβ40 and Aβ42 were measured. Serial cerebrospinal fluid collection via indwelling lumbar catheter over 36 to 48 hours before, during, and after in vivo labeling, with a 9-hour primed constant infusion of 13C6-leucine. The amplitude, linear increase, and other cosinor measures of each participant's serial cerebrospinal fluid Aβ concentrations and Aβ turnover rates. Of the 77 participants studied, 46 (59.7%) were men, and the mean (range) age was 72.6 (60.4-87.7) years. Day/night patterns in Aβ concentrations were more sharply defined by the precise mass spectrometry method than by enzyme-linked immunosorbent assay (mean difference of SD of residuals: Aβ40, -7.42 pM; P effects of age and amyloid on Aβ42 amplitude at least partially affect each other. Production and turnover rates suggest that day/night Aβ patterns are modulated by both production and clearance mechanisms active in sleep-wake cycles and that amyloid deposition may impair normal circadian patterns. These findings

Apolipoproteins E and J interfere with amyloid-beta uptake by primary human astrocytes and microglia in vitro

NARCIS (Netherlands)

Mulder, S.D.; Nielsen, H.M.; Blankenstein, M.A.; Eikelenboom, P.; Veerhuis, R.

2014-01-01

Defective clearance of the amyloid-β peptide (Aβ) from the brain is considered a strong promoter in Alzheimer's disease (AD) pathogenesis. Astrocytes and microglia are important mediators of Aβ clearance and Aβ aggregation state and the presence of amyloid associated proteins (AAPs), such as

The effect of simvastatin treatment on the amyloid precursor protein and brain cholesterol metabolism in patients with Alzheimer's disease

DEFF Research Database (Denmark)

Hoglund, K; Thelen, K M; Syversen, S

2005-01-01

During the last years, several clinical studies have been published trying to elucidate the effect of statin treatment on amyloid precursor protein (APP) processing and metabolism of brain cholesterol in Alzheimer's disease (AD) in humans. We present an open biochemical study where 19 patients...... with AD have been treated with simvastatin (20 mg/day) for 12 months. The aim was to further investigate the effect of simvastatin treatment on cerebrospinal fluid (CSF) biomarkers of APP processing, AD biomarkers as total tau and tau phosphorylated at threonine 181, brain cholesterol metabolism as well...... as on cognitive decline in patients with AD. Despite biochemical data suggesting that treatment with 20 mg/day of simvastatin for 12 months does affect the brain cholesterol metabolism, we did not find any change in CSF or plasma levels of beta-amyloid (Abeta)(1-42). However, by analysis of APP isoforms, we found...

Evaluation of systemic amyloidosis by scintigraphy with 123I-labeled serum amyloid P component

International Nuclear Information System (INIS)

Hawkins, P.N.; Lavender, J.P.; Pepys, M.B.

1990-01-01

In systemic amyloidosis the distribution and progression of disease have been difficult to monitor, because they can be demonstrated only by biopsy. Serum amyloid P component (SAP) is a normal circulating plasma protein that is deposited on amyloid fibrils because of its specific binding affinity for them. We investigated whether labeled SAP could be used to locate amyloid deposits. Purified human SAP labeled with iodine-123 was given intravenously to 50 patients with biopsy-proved systemic amyloidosis--25 with the AL (primary) type and 25 with the AA (secondary) type--and to 26 control patients with disease and 10 healthy subjects. Whole-body images and regional views were obtained after 24 hours and read in a blinded fashion. In the patients with amyloidosis the 123I-SAP was localized rapidly and specifically in amyloid deposits. The scintigraphic images obtained were characteristic and appeared to identify the extent of amyloid deposition in all 50 patients. There was no uptake of the 123I-SAP by the control patients and the healthy subjects. In all patients with AA amyloidosis the spleen was affected, whereas the scans showed uptake in the heart, skin, carpal region, and bone marrow only in patients with the AL type. Positive images were seen in six patients in whom biopsies had been negative or unsuccessful; in all six, amyloid was subsequently found on biopsy or at autopsy. Progressive amyloid deposition was observed in 9 of 11 patients studied serially. Scintigraphy after the injection of 123I-SAP can be used for diagnosing, locating, and monitoring the extent of systemic amyloidosis

Impact of amyloid-beta changes on cognitive outcomes in Alzheimer's disease: analysis of clinical trials using a quantitative systems pharmacology model.

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Geerts, Hugo; Spiros, Athan; Roberts, Patrick

2018-02-02

Despite a tremendous amount of information on the role of amyloid in Alzheimer's disease (AD), almost all clinical trials testing this hypothesis have failed to generate clinically relevant cognitive effects. We present an advanced mechanism-based and biophysically realistic quantitative systems pharmacology computer model of an Alzheimer-type neuronal cortical network that has been calibrated with Alzheimer Disease Assessment Scale, cognitive subscale (ADAS-Cog) readouts from historical clinical trials and simulated the differential impact of amyloid-beta (Aβ40 and Aβ42) oligomers on glutamate and nicotinic neurotransmission. Preclinical data suggest a beneficial effect of shorter Aβ forms within a limited dose range. Such a beneficial effect of Aβ40 on glutamate neurotransmission in human patients is absolutely necessary to reproduce clinical data on the ADAS-Cog in minimal cognitive impairment (MCI) patients with and without amyloid load, the effect of APOE genotype effect on the slope of the cognitive trajectory over time in placebo AD patients and higher sensitivity to cholinergic manipulation with scopolamine associated with higher Aβ in MCI subjects. We further derive a relationship between units of Aβ load in our model and the standard uptake value ratio from amyloid imaging. When introducing the documented clinical pharmacodynamic effects on Aβ levels for various amyloid-related clinical interventions in patients with low Aβ baseline, the platform predicts an overall significant worsening for passive vaccination with solanezumab, beta-secretase inhibitor verubecestat and gamma-secretase inhibitor semagacestat. In contrast, all three interventions improved cognition in subjects with moderate to high baseline Aβ levels, with verubecestat anticipated to have the greatest effect (around ADAS-Cog value 1.5 points), solanezumab the lowest (0.8 ADAS-Cog value points) and semagacestat in between. This could explain the success of many amyloid

Correlations between serum levels of beta amyloid, cerebrospinal levels of tau and phospho tau, and delayed response tasks in young and aged cynomolgus monkeys (Macaca fascicularis)

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Darusman, Huda Shalahudin; Sajuthi, D; Kalliokoski, O

2013-01-01

In an attempt to explore cynomolgus monkeys as an animal model for Alzheimer's disease, the present study focused on the Alzheimer's biomarkers beta amyloid 1-42 (Aβ42 ) in serum, and total tau (t-tau) and phosphorylated tau (p-tau) levels in cerebrospinal fluid.......In an attempt to explore cynomolgus monkeys as an animal model for Alzheimer's disease, the present study focused on the Alzheimer's biomarkers beta amyloid 1-42 (Aβ42 ) in serum, and total tau (t-tau) and phosphorylated tau (p-tau) levels in cerebrospinal fluid....

BetaTPred: prediction of beta-TURNS in a protein using statistical algorithms.

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Kaur, Harpreet; Raghava, G P S

2002-03-01

beta-turns play an important role from a structural and functional point of view. beta-turns are the most common type of non-repetitive structures in proteins and comprise on average, 25% of the residues. In the past numerous methods have been developed to predict beta-turns in a protein. Most of these prediction methods are based on statistical approaches. In order to utilize the full potential of these methods, there is a need to develop a web server. This paper describes a web server called BetaTPred, developed for predicting beta-TURNS in a protein from its amino acid sequence. BetaTPred allows the user to predict turns in a protein using existing statistical algorithms. It also allows to predict different types of beta-TURNS e.g. type I, I', II, II', VI, VIII and non-specific. This server assists the users in predicting the consensus beta-TURNS in a protein. The server is accessible from http://imtech.res.in/raghava/betatpred/

Einfluß einer In-vitro- und In-vivo-Cholesterol-Modulation in Hirnmembranen auf die zellulären Effekte von Amyloid-beta-Peptid

OpenAIRE

Kirsch, Christopher

2003-01-01

Die exzessive Bildung und Ablagerung von aggregiertem Amyloid beta-Peptid im Gehirn von Alzheimer Patienten wird allgemein als zentrales Ereignis im Rahmen des Neurodegenerationsprozesses der Alzheimer Demenz betrachtet. Der Amyloid-Stoffwechsel ist dabei in sehr vielfältiger Weise mit dem zellulären Cholesterol-Stoffwechsel verknüpft. Hohe Cholesterolspiegel in spezifischen Membrandomänen wie Lipid-Rafts forcieren sehr wahrscheinlich die zelluläre Produktion als auch die Fibrillogenese von A...

Voluntary Exercise Promotes Glymphatic Clearance of Amyloid Beta and Reduces the Activation of Astrocytes and Microglia in Aged Mice.

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He, Xiao-Fei; Liu, Dong-Xu; Zhang, Qun; Liang, Feng-Ying; Dai, Guang-Yan; Zeng, Jin-Sheng; Pei, Zhong; Xu, Guang-Qing; Lan, Yue

2017-01-01

Age is characterized by chronic inflammation, leading to synaptic dysfunction and dementia because the clearance of protein waste is reduced. The clearance of proteins depends partly on the permeation of the blood-brain barrier (BBB) or on the exchange of water and soluble contents between the cerebrospinal fluid (CSF) and the interstitial fluid (ISF). A wealth of evidence indicates that physical exercise improves memory and cognition in neurodegenerative diseases during aging, such as Alzheimer's disease (AD), but the influence of physical training on glymphatic clearance, BBB permeability and neuroinflammation remains unclear. In this study, glymphatic clearance and BBB permeability were evaluated in aged mice using in vivo two-photon imaging. The mice performed voluntary wheel running exercise and their water-maze cognition was assessed; the expression of the astrocytic water channel aquaporin 4 (AQP4), astrocyte and microglial activation, and the accumulation of amyloid beta (Aβ) were evaluated with immunofluorescence or an enzyme-linked immunosorbent assay (ELISA); synaptic function was investigated with Thy1 -green fluorescent protein (GFP) transgenic mice and immunofluorescent staining. Voluntary wheel running significantly improved water-maze cognition in the aged mice, accelerated the efficiency of glymphatic clearance, but which did not affect BBB permeability. The numbers of activated astrocytes and microglia decreased, AQP4 expression increased, and the distribution of astrocytic AQP4 was rearranged. Aβ accumulation decreased, whereas dendrites, dendritic spines and postsynaptic density protein (PSD95) increased. Our study suggests that voluntary wheel running accelerated glymphatic clearance but not BBB permeation, improved astrocytic AQP4 expression and polarization, attenuated the accumulation of amyloid plaques and neuroinflammation, and ultimately protected mice against synaptic dysfunction and a decline in spatial cognition. These data suggest

Voluntary Exercise Promotes Glymphatic Clearance of Amyloid Beta and Reduces the Activation of Astrocytes and Microglia in Aged Mice

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Xiao-fei He

2017-05-01

Full Text Available Age is characterized by chronic inflammation, leading to synaptic dysfunction and dementia because the clearance of protein waste is reduced. The clearance of proteins depends partly on the permeation of the blood–brain barrier (BBB or on the exchange of water and soluble contents between the cerebrospinal fluid (CSF and the interstitial fluid (ISF. A wealth of evidence indicates that physical exercise improves memory and cognition in neurodegenerative diseases during aging, such as Alzheimer’s disease (AD, but the influence of physical training on glymphatic clearance, BBB permeability and neuroinflammation remains unclear. In this study, glymphatic clearance and BBB permeability were evaluated in aged mice using in vivo two-photon imaging. The mice performed voluntary wheel running exercise and their water-maze cognition was assessed; the expression of the astrocytic water channel aquaporin 4 (AQP4, astrocyte and microglial activation, and the accumulation of amyloid beta (Aβ were evaluated with immunofluorescence or an enzyme-linked immunosorbent assay (ELISA; synaptic function was investigated with Thy1–green fluorescent protein (GFP transgenic mice and immunofluorescent staining. Voluntary wheel running significantly improved water-maze cognition in the aged mice, accelerated the efficiency of glymphatic clearance, but which did not affect BBB permeability. The numbers of activated astrocytes and microglia decreased, AQP4 expression increased, and the distribution of astrocytic AQP4 was rearranged. Aβ accumulation decreased, whereas dendrites, dendritic spines and postsynaptic density protein (PSD95 increased. Our study suggests that voluntary wheel running accelerated glymphatic clearance but not BBB permeation, improved astrocytic AQP4 expression and polarization, attenuated the accumulation of amyloid plaques and neuroinflammation, and ultimately protected mice against synaptic dysfunction and a decline in spatial cognition

Significant association between renal function and amyloid-positive area in renal biopsy specimens in AL amyloidosis

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Kuroda Takeshi

2012-09-01

Full Text Available Abstract Background The kidney is a major target organ for systemic amyloidosis that often affects the kidney including proteinura, and elevated serum creatinine (Cr. The correlation between amount of amyloid deposits and clinical parameters is not known. The aim of this study was to clarify correlation the amyloid area in all renal biopsy specimen and clinical parameters. Methods Fifty-eight patients with an established diagnosis of AL amyloidosis participated in the study. All patients showed amyloid deposits in renal biopsies. We retrospectively investigated the correlation between clinical data and amyloid occupied area in whole renal biopsy specimens. Results The area occupied by amyloid was less than 10% in 57 of the 58 patients, and was under 2% in 40. For statistical analyses, %amyloid-positive areas were transformed to common logarithmic values (Log10%amyloid. Cr showed significant correlation with Log10%amyloid and estimated glomerular filtration rate (eGFR showed the significant negative correlation. Patient age, cleatinine clearance (Ccr, blood urea nitorogen, and urinary protein was not significantly correlated with Log10%amyloid. The correlation with other clinical factors such as sex, and serum concentrations of total protein, albumin, immunoglobulins, compliments was evaluated. None of these factors significantly correlated with Log10%amyloid. According to sex- and age- adjusted multiple linear regression analysis, Log10%amyloid had significant positive association with Cr and significant negative association with eGFR. Conclusion There is significant association between amyloid-positive area in renal tissue and renal function, especially Cr and eGFR. The level of Cr and eGFR may be a marker of amount of amyloid in renal tissue.

The Nucleation of Protein Aggregates - From Crystals to Amyloid Fibrils.

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Buell, Alexander K

2017-01-01

The condensation and aggregation of individual protein molecules into dense insoluble phases is of relevance in such diverse fields as materials science, medicine, structural biology and pharmacology. A common feature of these condensation phenomena is that they usually are nucleated processes, i.e. the first piece of the condensed phase is energetically costly to create and hence forms slowly compared to its subsequent growth. Here we give a compact overview of the differences and similarities of various protein nucleation phenomena, their theoretical description in the framework of colloid and polymer science and their experimental study. Particular emphasis is put on the nucleation of a specific type of filamentous protein aggregates, amyloid fibrils. The current experimentally derived knowledge on amyloid fibril nucleation is critically assessed, and we argue that it is less advanced than is generally believed. This is due to (I) the lack of emphasis that has been put on the distinction between homogeneous and heterogeneous nucleation in experimental studies (II) the use of oversimplifying and/or inappropriate theoretical frameworks for the analysis of kinetic data of amyloid fibril nucleation. A strategy is outlined and advocated of how our understanding of this important class of processes can be improved in the future. © 2017 Elsevier Inc. All rights reserved.

Cerebral amyloid angiopathy: diagnosis and potential therapies.

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Weber, Stewart A; Patel, Ranish K; Lutsep, Helmi L

2018-06-01

Cerebral amyloid angiopathy (CAA) is characterized by the pathologic deposition of amyloid-beta within cortical and leptomeningeal arteries, arterioles, capillaries and, in rare cases, the venules of the brain. It is often associated with the development of lobar intracerebral hemorrhages (ICHs) but may cause other neurologic symptoms or be asymptomatic. Magnetic resonance imaging characteristics, such as lobar microbleeds, support a diagnosis of CAA and assist with hemorrhage risk assessments. Immunosuppressants are used to treat rarer inflammatory forms of CAA. For the more common forms of CAA, the use of antihypertensive medications can prevent ICH recurrence while the use of antithrombotics may increase hemorrhage risk. Anti-amyloid approaches to treatment have not yet been investigated in phase 3 trials. Areas covered: A literature search was conducted using MEDLINE on the topics of imaging, biomarkers, ICH prevention and treatment trials in CAA, focusing on its current diagnosis and management and opportunities for future therapeutic approaches. Expert commentary: There is likely a significant unrecognized burden of CAA in the elderly population. Continued research efforts to discover biomarkers that allow the early diagnosis of CAA will enhance the opportunity to develop treatment interventions.

Treatment of amyloidosis.

Science.gov (United States)

Tan, S Y; Pepys, M B; Hawkins, P N

1995-08-01

has been recently reported. Serum amyloid P component scans show regression of associated visceral amyloidosis. This surgical form of gene therapy holds much promise for patients with familial amyloid polyneuropathy and has been widely adopted. The only other form of amyloidosis in which the supply of the fibril precursor protein can be sharply reduced is beta 2M amyloidosis in long-term hemodialysis patients. Renal transplantation lowers the plasma concentration of beta 2M to normal levels and is associated with rapid improvement of the osteoarticular symptoms. Preliminary observations suggest that the beta 2M amyloid deposits also can regress in some patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Natural Amyloid-Beta Oligomers Acutely Impair the Formation of a Contextual Fear Memory in Mice

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Kittelberger, Kara A.; Piazza, Fabrizio; Tesco, Giuseppina; Reijmers, Leon G.

2012-01-01

Memory loss is one of the hallmark symptoms of Alzheimer's disease (AD). It has been proposed that soluble amyloid-beta (Abeta) oligomers acutely impair neuronal function and thereby memory. We here report that natural Abeta oligomers acutely impair contextual fear memory in mice. A natural Abeta oligomer solution containing Abeta monomers, dimers, trimers, and tetramers was derived from the conditioned medium of 7PA2 cells, a cell line that expresses human amyloid precursor protein containing the Val717Phe familial AD mutation. As a control we used 7PA2 conditioned medium from which Abeta oligomers were removed through immunodepletion. Separate groups of mice were injected with Abeta and control solutions through a cannula into the lateral brain ventricle, and subjected to fear conditioning using two tone-shock pairings. One day after fear conditioning, mice were tested for contextual fear memory and tone fear memory in separate retrieval trials. Three experiments were performed. For experiment 1, mice were injected three times: 1 hour before and 3 hours after fear conditioning, and 1 hour before context retrieval. For experiments 2 and 3, mice were injected a single time at 1 hour and 2 hours before fear conditioning respectively. In all three experiments there was no effect on tone fear memory. Injection of Abeta 1 hour before fear conditioning, but not 2 hours before fear conditioning, impaired the formation of a contextual fear memory. In future studies, the acute effect of natural Abeta oligomers on contextual fear memory can be used to identify potential mechanisms and treatments of AD associated memory loss. PMID:22238679

Interactions between two beta-sheets. Energetics of beta/beta packing in proteins.

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Chou, K C; Némethy, G; Rumsey, S; Tuttle, R W; Scheraga, H A

1986-04-20

The analysis of the interactions between regularly folded segments of the polypeptide chain contributes to an understanding of the energetics of protein folding. Conformational energy-minimization calculations have been carried out to determine the favorable ways of packing two right-twisted beta-sheets. The packing of two five-stranded beta-sheets was investigated, with the strands having the composition CH3CO-(L-Ile)6-NHCH3 in one beta-sheet and CH3CO-(L-Val)6-NHCH3 in the other. Two distinct classes of low-energy packing arrangements were found. In the class with lowest energies, the strands of the two beta-sheets are aligned nearly parallel (or antiparallel) with each other, with a preference for a negative orientation angle, because this arrangement corresponds to the best complementary packing of the two twisted saddle-shaped beta-sheets. In the second class, with higher interaction energies, the strands of the two beta-sheets are oriented nearly perpendicular to each other. While the surfaces of the two beta-sheets are not complementary in this arrangement, there is good packing between the corner of one beta-sheet and the interior part of the surface of the other, resulting in a favorable energy of packing. Both classes correspond to frequently observed orientations of beta-sheets in proteins. In proteins, the second class of packing is usually observed when the two beta-sheets are covalently linked, i.e. when a polypeptide strand passes from one beta-sheet to the other, but we have shown here that a large contribution to the stabilization of this packing arrangement arises from noncovalent interactions.

Shear-Induced Amyloid Formation in the Brain: I. Potential Vascular and Parenchymal Processes.

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Trumbore, Conrad N

2016-09-06

Shear distortion of amyloid-beta (Aβ) solutions accelerates amyloid cascade reactions that may yield different toxic oligomers than those formed in quiescent solutions. Recent experiments indicate that cerebrospinal fluid (CSF) and interstitial fluid (ISF) containing Aβ flow through narrow brain perivascular pathways and brain parenchyma. This paper suggests that such flow causes shear distortion of Aβ molecules involving conformation changes that may be one of the initiating events in the etiology of Alzheimer's disease. Aβ shearing can occur in or around brain arteries and arterioles and is suggested as the origin of cerebral amyloid angiopathy deposits in cerebrovascular walls. Comparatively low flow rates of ISF within the narrow extracellular spaces (ECS) of the brain parenchyma are suggested as a possible initiating factor in both the formation of neurotoxic Aβ42 oligomers and amyloid fibrils. Aβ42 in slow-flowing ISF can gain significant shear energy at or near the walls of tortuous brain ECS flow paths, promoting the formation of a shear-distorted, excited state hydrophobic Aβ42* conformation. This Aβ42* molecule could possibly be involved in one of two paths, one involving rapid adsorption to a brain membrane surface, ultimately forming neurotoxic oligomers on membranes, and the other ultimately forming plaque within the ECS flow pathways. Rising Aβ concentrations combined with shear at or near critical brain membranes are proposed as contributing factors to Alzheimer's disease neurotoxicity. These hypotheses may be applicable in other neurodegenerative diseases, including tauopathies and alpha-synucleinopathies, in which shear-distorted proteins also may form in the brain ECS.

Nanoparticles and amyloid systems: A fatal encounter?

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Abel, Bernd [Leibniz Institute of Surface Modification, Chemical Department, Permoserstr. 15, D-04318 Leipzig, Germany and Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, Linnéstr. 3, D-04103 Leipzig (Germany)

2014-10-06

Nanoparticles (NPs) are used in many products of our daily life, however, there has been concern that they may also be harmful to human health. Recently NPs have been found to accelerate the fibrillation kinetics of amyloid systems. In the past this has been preliminarily attributed to a nucleation effect. Nanoparticle surfaces and interfaces appear to limit the degrees of freedom of amyloid systems (i.e., peptides and proteins) due to a phase space constraint such that rapid cross-beta structures are formed faster than without interface interactions and in turn fibril formation is enhanced significantly. Here we explore if lipid bilayers in the form of liposomes (140nm) also accelerate fibril formation for amyloid systems. We have investigated a fragment NNFGAIL of the Human islet amyloid polypeptide (hIAPP) in contact with 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) liposomes in aqueous solution. We found that the lipid bilayer vesicles do accelerate fibril formation in time-resolved off-line detected atomic force microscopy experiments. Characteristic Thioflavine-T fluorescence on the same structures verify that the structures consist of aggregated peptides in a typical cross-β-structure arrangement.

Constant region of a kappa III immunoglobulin light chain as a major AL-amyloid protein

DEFF Research Database (Denmark)

Engvig, J P; Olsen, K E; Gislefoss, R E

1998-01-01

AL-amyloidoses are generally described as a group of disorders in which N-terminal fragments of monoclonal immunoglobulin light chains are transferred into amyloid fibrils. We have, by amino acid sequence analyses and immunological methods, characterized the Bence-Jones protein and the correspond......AL-amyloidoses are generally described as a group of disorders in which N-terminal fragments of monoclonal immunoglobulin light chains are transferred into amyloid fibrils. We have, by amino acid sequence analyses and immunological methods, characterized the Bence-Jones protein...... and the corresponding AL protein as a kappa III immunoglobulin light chain from material of a patient with systemic AL-amyloidosis presenting as a local inguinal tumour. The two proteins showed some unique features. The major part of the AL amyloid fibril protein consisted of C-terminal fragments of the Bence......-Jones protein. Furthermore, both the Bence-Jones protein and the AL protein were glycosylated, with possibly a glycosylation in the constant part of the light chain....

Cerebral Amyloid Angiopathy-Related Inflammation: Report of a Case with Very Difficult Therapeutic Management

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Francesca Crosta

2015-01-01

Full Text Available Background. Cerebral amyloid angiopathy-related inflammation (CAA-ri results from autoimmune response to beta-amyloid deposits in cerebral vessels. Its clinical course and complications have seldom been described in literature. Case Report. In a patient presenting with delirium and left hemiparesis the diagnosis of CAA-ri was supported by the finding of elevated anti-amyloid autoantibodies in the cerebrospinal fluid (CSF. Steroid therapy produced significant improvements in clinical and investigational assessments, but after two months, it caused Acute Respiratory Distress Syndrome. After steroid therapy discontinuation the patient presented a rapidly progressive dementia, Guillain-Barré syndrome, new cerebral ischemic lesions, and thrombosis of the right cephalic and subclavian veins that were treated with subcutaneous heparin. After a week the patient died because of brain hemorrhage. Conclusion. This case suggests caution in steroid therapy discontinuation and antithrombotic therapy administration in patients with CAA-ri. The CSF search of anti-amyloid autoantibodies could be helpful to support the diagnosis.

The soluble transcobalamin receptor (sCD320) is present in cerebrospinal fluid and correlates to dementia-related biomarkers tau proteins and amyloid-beta

DEFF Research Database (Denmark)

Abuyaman, Omar; Nexo, Ebba

2015-01-01

BACKGROUND: Cellular uptake of vitamin B12 (B12) demands binding of the vitamin to transcobalamin (TC) and recognition of TC-B12 (holoTC) by the receptor CD320. Recently, we identified a soluble form of CD320 (sCD320) in human plasma. Here we present data on the occurrence of this soluble receptor...... phospho-tau (181P) (p-tau), total tau (t-tau) and amyloid-beta 1-42 (Aβ) (n = 177) employing commercial ELISA kits (Innogenetics Company). Size exclusion chromatography was performed on a Superdex 200 column. RESULTS: The median sCD320 concentration in CSF (14 pmol/L) is around five times lower than...

Amyloid Deposition in Transplanted Human Pancreatic Islets: A Conceivable Cause of Their Long-Term Failure

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Arne Andersson

2008-01-01

Full Text Available Following the encouraging report of the Edmonton group, there was a rejuvenation of the islet transplantation field. After that, more pessimistic views spread when long-term results of the clinical outcome were published. A progressive loss of the β-cell function meant that almost all patients were back on insulin therapy after 5 years. More than 10 years ago, we demonstrated that amyloid deposits rapidly formed in human islets and in mouse islets transgenic for human IAPP when grafted into nude mice. It is, therefore, conceivable to consider amyloid formation as one potential candidate for the long-term failure. The present paper reviews attempts in our laboratories to elucidate the dynamics of and mechanisms behind the formation of amyloid in transplanted islets with special emphasis on the impact of long-term hyperglycemia.

Amyloid precursor protein secretases as therapeutic targets for traumatic brain injury

OpenAIRE

Loane, David J; Pocivavsek, Ana; Moussa, Charbel E-H; Thompson, Rachel; Matsuoka, Yasuji; Faden, Alan I; Rebeck, G William; Burns, Mark P

2009-01-01

Amyloid-β (Aβ) peptides, found in Alzheimer’s disease brain, accumulate rapidly after traumatic brain injury (TBI) in both humans and animals. Here we show that blocking either β- or γ-secretase, enzymes required for production of Aβ from amyloid precursor protein (APP), can ameliorate motor and cognitive deficits and reduce cell loss after experimental TBI in mice. Thus, APP secretases are promising targets for treatment of TBI.

Differential regulation of amyloid-β-protein mRNA expression within hippocampal neuronal subpopulations in Alzheimer disease

International Nuclear Information System (INIS)

Higgins, G.A.; Lewis, D.A.; Bahmanyar, S.; Goldgaber, D.; Gajdusek, D.C.; Young, W.G.; Morrison, J.H.; Wilson, M.C.

1988-01-01

The authors have mapped the neuroanatomical distribution of amyloid-β-protein mRNA within neuronal subpopulations of the hippocampal formation in the cynomolgus monkey (Macaca fascicularis), normal aged human, and patients with Alzheimer disease. Amyloid-β-protein mRNA appears to be expressed in all hippocampal neurons, but at different levels of abundance. In the central nervous system of monkey and normal aged human, image analysis shows that neurons of the dentate gyrus and cornu Ammonis fields contain a 2.5-times-greater hybridization signal than is present in neurons of the subiculum and entorhinal cortex. In contrast, in the Alzheimer disease hippocampal formation, the levels of amyloid-β-protein mRNA in the cornu Ammonis field 3 and parasubiculum are equivalent. These findings suggest that within certain neuronal subpopulations cell type-specific regulation of amyloid-β-protein gene expression may be altered in Alzheimer disease

Synthesis, Molecular Modelling and Biological Evaluation of Novel Heterodimeric, Multiple Ligands Targeting Cholinesterases and Amyloid Beta

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Michalina Hebda

2016-03-01

Full Text Available Cholinesterases and amyloid beta are one of the major biological targets in the search for a new and efficacious treatment of Alzheimer’s disease. The study describes synthesis and pharmacological evaluation of new compounds designed as dual binding site acetylcholinesterase inhibitors. Among the synthesized compounds, two deserve special attention—compounds 42 and 13. The former is a saccharin derivative and the most potent and selective acetylcholinesterase inhibitor (EeAChE IC50 = 70 nM. Isoindoline-1,3-dione derivative 13 displays balanced inhibitory potency against acetyl- and butyrylcholinesterase (BuChE (EeAChE IC50 = 0.76 μM, EqBuChE IC50 = 0.618 μM, and it inhibits amyloid beta aggregation (35.8% at 10 μM. Kinetic studies show that the developed compounds act as mixed or non-competitive acetylcholinesterase inhibitors. According to molecular modelling studies, they are able to interact with both catalytic and peripheral active sites of the acetylcholinesterase. Their ability to cross the blood-brain barrier (BBB was confirmed in vitro in the parallel artificial membrane permeability BBB assay. These compounds can be used as a solid starting point for further development of novel multifunctional ligands as potential anti-Alzheimer’s agents.

Automated solid-state NMR resonance assignment of protein microcrystals and amyloids

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Elena [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany); Gath, Julia [ETH Zurich, Physical Chemistry (Switzerland); Habenstein, Birgit [UMR 5086 CNRS/Universite de Lyon 1, Institut de Biologie et Chimie des Proteines (France); Ravotti, Francesco; Szekely, Kathrin; Huber, Matthias [ETH Zurich, Physical Chemistry (Switzerland); Buchner, Lena [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany); Boeckmann, Anja, E-mail: a.bockmann@ibcp.fr [UMR 5086 CNRS/Universite de Lyon 1, Institut de Biologie et Chimie des Proteines (France); Meier, Beat H., E-mail: beme@ethz.ch [ETH Zurich, Physical Chemistry (Switzerland); Guentert, Peter, E-mail: guentert@em.uni-frankfurt.de [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany)

2013-07-15

Solid-state NMR is an emerging structure determination technique for crystalline and non-crystalline protein assemblies, e.g., amyloids. Resonance assignment constitutes the first and often very time-consuming step to a structure. We present ssFLYA, a generally applicable algorithm for automatic assignment of protein solid-state NMR spectra. Application to microcrystals of ubiquitin and the Ure2 prion C-terminal domain, as well as amyloids of HET-s(218-289) and {alpha}-synuclein yielded 88-97 % correctness for the backbone and side-chain assignments that are classified as self-consistent by the algorithm, and 77-90 % correctness if also assignments classified as tentative by the algorithm are included.

Direct interaction of beta-amyloid with Na,K-ATPase as a putative regulator of the enzyme function

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Petrushanko, Irina Yu.; Mitkevich, Vladimir A.; Anashkina, Anastasia A.; Adzhubei, Alexei A.; Burnysheva, Ksenia M.; Lakunina, Valentina A.; Kamanina, Yulia V.; Dergousova, Elena A.; Lopina, Olga D.; Ogunshola, Omolara O.; Bogdanova, Anna Yu.; Makarov, Alexander A.

2016-06-01

By maintaining the Na+ and K+ transmembrane gradient mammalian Na,K-ATPase acts as a key regulator of neuronal electrotonic properties. Na,K-ATPase has an important role in synaptic transmission and memory formation. Accumulation of beta-amyloid (Aβ) at the early stages of Alzheimer’s disease is accompanied by reduction of Na,K-ATPase functional activity. The molecular mechanism behind this phenomenon is not known. Here we show that the monomeric Aβ(1-42) forms a tight (Kd of 3 μM), enthalpy-driven equimolar complex with α1β1 Na,K-ATPase. The complex formation results in dose-dependent inhibition of the enzyme hydrolytic activity. The binding site of Aβ(1-42) is localized in the “gap” between the alpha- and beta-subunits of Na,K-ATPase, disrupting the enzyme functionality by preventing the subunits from shifting towards each other. Interaction of Na,K-ATPase with exogenous Aβ(1-42) leads to a pronounced decrease of the enzyme transport and hydrolytic activity and Src-kinase activation in neuroblastoma cells SH-SY5Y. This interaction allows regulation of Na,K-ATPase activity by short-term increase of the Aβ(1-42) level. However prolonged increase of Aβ(1-42) level under pathological conditions could lead to chronical inhibition of Na,K-ATPase and disruption of neuronal function. Taken together, our data suggest the role of beta-amyloid as a novel physiological regulator of Na,K-ATPase.

Activation of the endoplasmic reticulum stress response by the amyloid-beta 1-40 peptide in brain endothelial cells.

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Fonseca, Ana Catarina R G; Ferreiro, Elisabete; Oliveira, Catarina R; Cardoso, Sandra M; Pereira, Cláudia F

2013-12-01

Neurovascular dysfunction arising from endothelial cell damage is an early pathogenic event that contributes to the neurodegenerative process occurring in Alzheimer's disease (AD). Since the mechanisms underlying endothelial dysfunction are not fully elucidated, this study was aimed to explore the hypothesis that brain endothelial cell death is induced upon the sustained activation of the endoplasmic reticulum (ER) stress response by amyloid-beta (Aβ) peptide, which deposits in the cerebral vessels in many AD patients and transgenic mice. Incubation of rat brain endothelial cells (RBE4 cell line) with Aβ1-40 increased the levels of several markers of ER stress-induced unfolded protein response (UPR), in a time-dependent manner, and affected the Ca(2+) homeostasis due to the release of Ca(2+) from this intracellular store. Finally, Aβ1-40 was shown to activate both mitochondria-dependent and -independent apoptotic cell death pathways. Enhanced release of cytochrome c from mitochondria and activation of the downstream caspase-9 were observed in cells treated with Aβ1-40 concomitantly with caspase-12 activation. Furthermore, Aβ1-40 activated the apoptosis effectors' caspase-3 and promoted the translocation of apoptosis-inducing factor (AIF) to the nucleus demonstrating the involvement of caspase-dependent and -independent mechanisms during Aβ-induced endothelial cell death. In conclusion, our data demonstrate that ER stress plays a significant role in Aβ1-40-induced apoptotic cell death in brain endothelial cells suggesting that ER stress-targeted therapeutic strategies might be useful in AD to counteract vascular defects and ultimately neurodegeneration. © 2013.

Membrane Incorporation, Channel Formation, and Disruption of Calcium Homeostasis by Alzheimer's β-Amyloid Protein

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Masahiro Kawahara

2011-01-01

Full Text Available Oligomerization, conformational changes, and the consequent neurodegeneration of Alzheimer's β-amyloid protein (AβP play crucial roles in the pathogenesis of Alzheimer's disease (AD. Mounting evidence suggests that oligomeric AβPs cause the disruption of calcium homeostasis, eventually leading to neuronal death. We have demonstrated that oligomeric AβPs directly incorporate into neuronal membranes, form cation-sensitive ion channels (“amyloid channels”, and cause the disruption of calcium homeostasis via the amyloid channels. Other disease-related amyloidogenic proteins, such as prion protein in prion diseases or α-synuclein in dementia with Lewy bodies, exhibit similarities in the incorporation into membranes and the formation of calcium-permeable channels. Here, based on our experimental results and those of numerous other studies, we review the current understanding of the direct binding of AβP into membrane surfaces and the formation of calcium-permeable channels. The implication of composition of membrane lipids and the possible development of new drugs by influencing membrane properties and attenuating amyloid channels for the treatment and prevention of AD is also discussed.

The alpha7 nicotinic acetylcholine receptor-selective antagonist, methyllycaconitine, partially protects against beta-amyloid1-42 toxicity in primary neuron-enriched cultures.

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Martin, Shelley E; de Fiebre, Nancy Ellen C; de Fiebre, Christopher M

2004-10-01

Studies have suggested that the neuroprotective actions of alpha7 nicotinic agonists arise from activation of receptors and not from the extensive desensitization which rapidly follows activation. Here, we report that the alpha7-selective nicotinic antagonist, methyllycaconitine (MLA), protects against beta-amyloid-induced neurotoxicity; whereas the alpha4beta2-selective antagonist, dihydro-beta-erythroidine, does not. These findings suggest that neuroprotective actions of alpha7-acting agents arise from receptor inhibition/desensitization and that alpha7 antagonists may be useful neuroprotective agents.

Endocytic vesicle rupture is a conserved mechanism of cellular invasion by amyloid proteins.

Science.gov (United States)

Flavin, William P; Bousset, Luc; Green, Zachary C; Chu, Yaping; Skarpathiotis, Stratos; Chaney, Michael J; Kordower, Jeffrey H; Melki, Ronald; Campbell, Edward M

2017-10-01

Numerous pathological amyloid proteins spread from cell to cell during neurodegenerative disease, facilitating the propagation of cellular pathology and disease progression. Understanding the mechanism by which disease-associated amyloid protein assemblies enter target cells and induce cellular dysfunction is, therefore, key to understanding the progressive nature of such neurodegenerative diseases. In this study, we utilized an imaging-based assay to monitor the ability of disease-associated amyloid assemblies to rupture intracellular vesicles following endocytosis. We observe that the ability to induce vesicle rupture is a common feature of α-synuclein (α-syn) assemblies, as assemblies derived from WT or familial disease-associated mutant α-syn all exhibited the ability to induce vesicle rupture. Similarly, different conformational strains of WT α-syn assemblies, but not monomeric or oligomeric forms, efficiently induced vesicle rupture following endocytosis. The ability to induce vesicle rupture was not specific to α-syn, as amyloid assemblies of tau and huntingtin Exon1 with pathologic polyglutamine repeats also exhibited the ability to induce vesicle rupture. We also observe that vesicles ruptured by α-syn are positive for the autophagic marker LC3 and can accumulate and fuse into large, intracellular structures resembling Lewy bodies in vitro. Finally, we show that the same markers of vesicle rupture surround Lewy bodies in brain sections from PD patients. These data underscore the importance of this conserved endocytic vesicle rupture event as a damaging mechanism of cellular invasion by amyloid assemblies of multiple neurodegenerative disease-associated proteins, and suggest that proteinaceous inclusions such as Lewy bodies form as a consequence of continued fusion of autophagic vesicles in cells unable to degrade ruptured vesicles and their amyloid contents.

Bifunctional fluorescent probes for detection of amyloid aggregates and reactive oxygen species.

Science.gov (United States)

Needham, Lisa-Maria; Weber, Judith; Fyfe, James W B; Kabia, Omaru M; Do, Dung T; Klimont, Ewa; Zhang, Yu; Rodrigues, Margarida; Dobson, Christopher M; Ghandi, Sonia; Bohndiek, Sarah E; Snaddon, Thomas N; Lee, Steven F

2018-02-01

Protein aggregation into amyloid deposits and oxidative stress are key features of many neurodegenerative disorders including Parkinson's and Alzheimer's disease. We report here the creation of four highly sensitive bifunctional fluorescent probes, capable of H 2 O 2 and/or amyloid aggregate detection. These bifunctional sensors use a benzothiazole core for amyloid localization and boronic ester oxidation to specifically detect H 2 O 2 . We characterized the optical properties of these probes using both bulk fluorescence measurements and single-aggregate fluorescence imaging, and quantify changes in their fluorescence properties upon addition of amyloid aggregates of α-synuclein and pathophysiological H 2 O 2 concentrations. Our results indicate these new probes will be useful to detect and monitor neurodegenerative disease.

Bifunctional fluorescent probes for detection of amyloid aggregates and reactive oxygen species

Science.gov (United States)

Needham, Lisa-Maria; Weber, Judith; Fyfe, James W. B.; Kabia, Omaru M.; Do, Dung T.; Klimont, Ewa; Zhang, Yu; Rodrigues, Margarida; Dobson, Christopher M.; Ghandi, Sonia; Bohndiek, Sarah E.; Snaddon, Thomas N.; Lee, Steven F.

2018-02-01

Protein aggregation into amyloid deposits and oxidative stress are key features of many neurodegenerative disorders including Parkinson's and Alzheimer's disease. We report here the creation of four highly sensitive bifunctional fluorescent probes, capable of H2O2 and/or amyloid aggregate detection. These bifunctional sensors use a benzothiazole core for amyloid localization and boronic ester oxidation to specifically detect H2O2. We characterized the optical properties of these probes using both bulk fluorescence measurements and single-aggregate fluorescence imaging, and quantify changes in their fluorescence properties upon addition of amyloid aggregates of α-synuclein and pathophysiological H2O2 concentrations. Our results indicate these new probes will be useful to detect and monitor neurodegenerative disease.

Cross dimerization of amyloid-β and αsynuclein proteins in aqueous environment: a molecular dynamics simulations study.

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Jaya C Jose

Full Text Available Self-assembly of the intrinsically unstructured proteins, amyloid beta (Aβ and alpha synclein (αSyn, are associated with Alzheimer's Disease, and Parkinson's and Lewy Body Diseases, respectively. Importantly, pathological overlaps between these neurodegenerative diseases, and the possibilities of interactions between Aβ and αSyn in biological milieu emerge from several recent clinical reports and in vitro studies. Nevertheless, there are very few molecular level studies that have probed the nature of spontaneous interactions between these two sequentially dissimilar proteins and key characteristics of the resulting cross complexes. In this study, we have used atomistic molecular dynamics simulations to probe the possibility of cross dimerization between αSyn1-95 and Aβ1-42, and thereby gain insights into their plausible early assembly pathways in aqueous environment. Our analyses indicate a strong probability of association between the two sequences, with inter-protein attractive electrostatic interactions playing dominant roles. Principal component analysis revealed significant heterogeneity in the strength and nature of the associations in the key interaction modes. In most, the interactions of repeating Lys residues, mainly in the imperfect repeats 'KTKEGV' present in αSyn1-95 were found to be essential for cross interactions and formation of inter-protein salt bridges. Additionally, a hydrophobicity driven interaction mode devoid of salt bridges, where the non-amyloid component (NAC region of αSyn1-95 came in contact with the hydrophobic core of Aβ1-42 was observed. The existence of such hetero complexes, and therefore hetero assembly pathways may lead to polymorphic aggregates with variations in pathological attributes. Our results provide a perspective on development of therapeutic strategies for preventing pathogenic interactions between these proteins.

Genome-wide association study of CSF levels of 59 alzheimer's disease candidate proteins: significant associations with proteins involved in amyloid processing and inflammation.

Science.gov (United States)

Kauwe, John S K; Bailey, Matthew H; Ridge, Perry G; Perry, Rachel; Wadsworth, Mark E; Hoyt, Kaitlyn L; Staley, Lyndsay A; Karch, Celeste M; Harari, Oscar; Cruchaga, Carlos; Ainscough, Benjamin J; Bales, Kelly; Pickering, Eve H; Bertelsen, Sarah; Fagan, Anne M; Holtzman, David M; Morris, John C; Goate, Alison M

2014-10-01

Cerebrospinal fluid (CSF) 42 amino acid species of amyloid beta (Aβ42) and tau levels are strongly correlated with the presence of Alzheimer's disease (AD) neuropathology including amyloid plaques and neurodegeneration and have been successfully used as endophenotypes for genetic studies of AD. Additional CSF analytes may also serve as useful endophenotypes that capture other aspects of AD pathophysiology. Here we have conducted a genome-wide association study of CSF levels of 59 AD-related analytes. All analytes were measured using the Rules Based Medicine Human DiscoveryMAP Panel, which includes analytes relevant to several disease-related processes. Data from two independently collected and measured datasets, the Knight Alzheimer's Disease Research Center (ADRC) and Alzheimer's Disease Neuroimaging Initiative (ADNI), were analyzed separately, and combined results were obtained using meta-analysis. We identified genetic associations with CSF levels of 5 proteins (Angiotensin-converting enzyme (ACE), Chemokine (C-C motif) ligand 2 (CCL2), Chemokine (C-C motif) ligand 4 (CCL4), Interleukin 6 receptor (IL6R) and Matrix metalloproteinase-3 (MMP3)) with study-wide significant p-values (pprocessing and pro-inflammatory signaling. SNPs associated with ACE, IL6R and MMP3 protein levels are located within the coding regions of the corresponding structural gene. The SNPs associated with CSF levels of CCL4 and CCL2 are located in known chemokine binding proteins. The genetic associations reported here are novel and suggest mechanisms for genetic control of CSF and plasma levels of these disease-related proteins. Significant SNPs in ACE and MMP3 also showed association with AD risk. Our findings suggest that these proteins/pathways may be valuable therapeutic targets for AD. Robust associations in cognitively normal individuals suggest that these SNPs also influence regulation of these proteins more generally and may therefore be relevant to other diseases.

Amyloid domains in the cell nucleus controlled by nucleoskeletal protein lamin B1 reveal a new pathway of mercury neurotoxicity

Science.gov (United States)

Arnhold, Florian; Gührs, Karl-Heinz

2015-01-01

Mercury (Hg) is a bioaccumulating trace metal that globally circulates the atmosphere and waters in its elemental, inorganic and organic chemical forms. While Hg represents a notorious neurotoxicant, the underlying cellular pathways are insufficiently understood. We identify amyloid protein aggregation in the cell nucleus as a novel pathway of Hg-bio-interactions. By mass spectrometry of purified protein aggregates, a subset of spliceosomal components and nucleoskeletal protein lamin B1 were detected as constituent parts of an Hg-induced nuclear aggregome network. The aggregome network was located by confocal imaging of amyloid-specific antibodies and dyes to amyloid cores within splicing-speckles that additionally recruit components of the ubiquitin-proteasome system. Hg significantly enhances global proteasomal activity in the nucleus, suggesting that formation of amyloid speckles plays a role in maintenance of protein homeostasis. RNAi knock down showed that lamin B1 for its part regulates amyloid speckle formation and thus likewise participates in nuclear protein homeostasis. As the Hg-induced cascade of interactions between the nucleoskeleton and protein homeostasis reduces neuronal signalling, amyloid fibrillation in the cell nucleus is introduced as a feature of Hg-neurotoxicity that opens new avenues of future research. Similar to protein aggregation events in the cytoplasm that are controlled by the cytoskeleton, amyloid fibrillation of nuclear proteins may be driven by the nucleoskeleton. PMID:25699204

Yeast prion architecture explains how proteins can be genes

Science.gov (United States)

Wickner, Reed

2013-03-01

Prions (infectious proteins) transmit information without an accompanying DNA or RNA. Most yeast prions are self-propagating amyloids that inactivate a normally functional protein. A single protein can become any of several prion variants, with different manifestations due to different amyloid structures. We showed that the yeast prion amyloids of Ure2p, Sup35p and Rnq1p are folded in-register parallel beta sheets using solid state NMR dipolar recoupling experiments, mass-per-filament-length measurements, and filament diameter measurements. The extent of beta sheet structure, measured by chemical shifts in solid-state NMR and acquired protease-resistance on amyloid formation, combined with the measured filament diameters, imply that the beta sheets must be folded along the long axis of the filament. We speculate that prion variants of a single protein sequence differ in the location of these folds. Favorable interactions between identical side chains must hold these structures in-register. The same interactions must guide an unstructured monomer joining the end of a filament to assume the same conformation as molecules already in the filament, with the turns at the same locations. In this way, a protein can template its own conformation, in analogy to the ability of a DNA molecule to template its sequence by specific base-pairing. Bldg. 8, Room 225, NIH, 8 Center Drive MSC 0830, Bethesda, MD 20892-0830, wickner@helix.nih.gov, 301-496-3452

Regulation of amyloid precursor protein processing by its KFERQ motif.

Science.gov (United States)

Park, Ji-Seon; Kim, Dong-Hou; Yoon, Seung-Yong

2016-06-01

Understanding of trafficking, processing, and degradation mechanisms of amyloid precursor protein (APP) is important because APP can be processed to produce β-amyloid (Aβ), a key pathogenic molecule in Alzheimer's disease (AD). Here, we found that APP contains KFERQ motif at its C-terminus, a consensus sequence for chaperone-mediated autophagy (CMA) or microautophagy which are another types of autophagy for degradation of pathogenic molecules in neurodegenerative diseases. Deletion of KFERQ in APP increased C-terminal fragments (CTFs) and secreted N-terminal fragments of APP and kept it away from lysosomes. KFERQ deletion did not abolish the interaction of APP or its cleaved products with heat shock cognate protein 70 (Hsc70), a protein necessary for CMA or microautophagy. These findings suggest that KFERQ motif is important for normal processing and degradation of APP to preclude the accumulation of APP-CTFs although it may not be important for CMA or microautophagy. [BMB Reports 2016; 49(6): 337-342].

Alzheimer's Disease: APP, Gamma Secretase, APOE, CLU, CR1, PICALM, ABCA7, BIN1, CD2AP, CD33, EPHA1, and MS4A2, and Their Relationships with Herpes Simplex, C. Pneumoniae, Other Suspect Pathogens, and the Immune System

Directory of Open Access Journals (Sweden)

Chris Carter

2011-01-01

Full Text Available Alzheimer's disease susceptibility genes, APP and gamma-secretase, are involved in the herpes simplex life cycle, and that of other suspect pathogens (C. pneumoniae, H. pylori, C. neoformans, B. burgdorferri, P. gingivalis or immune defence. Such pathogens promote beta-amyloid deposition and tau phosphorylation and may thus be causative agents, whose effects are conditioned by genes. The antimicrobial effects of beta-amyloid, the localisation of APP/gamma-secretase in immunocompetent dendritic cells, and gamma secretase cleavage of numerous pathogen receptors suggest that this network is concerned with pathogen disposal, effects which may be abrogated by the presence of beta-amyloid autoantibodies in the elderly. These autoantibodies, as well as those to nerve growth factor and tau, also observed in Alzheimer's disease, may well be antibodies to pathogens, due to homology between human autoantigens and pathogen proteins. NGF or tau antibodies promote beta-amyloid deposition, neurofibrillary tangles, or cholinergic neuronal loss, and, with other autoantibodies, such as anti-ATPase, are potential agents of destruction, whose formation is dictated by sequence homology between pathogen and human proteins, and thus by pathogen strain and human genes. Pathogen elimination in the ageing population and removal of culpable autoantibodies might reduce the incidence and offer hope for a cure in this affliction.

Ranking beta sheet topologies of proteins

DEFF Research Database (Denmark)

Fonseca, Rasmus; Helles, Glennie; Winter, Pawel

2010-01-01

One of the challenges of protein structure prediction is to identify long-range interactions between amino acids. To reliably predict such interactions, we enumerate, score and rank all beta-topologies (partitions of beta-strands into sheets, orderings of strands within sheets and orientations...... of paired strands) of a given protein. We show that the beta-topology corresponding to the native structure is, with high probability, among the top-ranked. Since full enumeration is very time-consuming, we also suggest a method to deal with proteins with many beta-strands. The results reported...... in this paper are highly relevant for ab initio protein structure prediction methods based on decoy generation. The top-ranked beta-topologies can be used to find initial conformations from which conformational searches can be started. They can also be used to filter decoys by removing those with poorly...

Octylphenol (OP) alters the expression of members of the amyloid protein family in the hypothalamus of the snapping turtle, Chelydra serpentina serpentina.

Science.gov (United States)

Trudeau, Vance L; Chiu, Suzanne; Kennedy, Sean W; Brooks, Ronald J

2002-03-01

The gonadal estrogen estradiol-17beta (E(2)) is important for developing and regulating hypothalamic function and many aspects of reproduction in vertebrates. Pollutants such as octylphenol (OP) that mimic the actions of estrogens are therefore candidate endocrine-disrupting chemicals. We used a differential display strategy (RNA-arbitrarily primed polymerase chain reaction) to isolate partial cDNA sequences of neurotransmitter, developmental, and disease-related genes that may be regulated by OP or E(2) in the snapping turtle Chelydra serpentina serpentina hypothalamus. Hatchling and year-old male snapping turtles were exposed to a 10 ng/mL nominal concentration of waterborne OP or E(2) for 17 days. One transcript [421 base pairs (bp)] regulated by OP and E(2) was 93% identical to human APLP-2. APLP-2 and the amyloid precursor protein (APP) regulate neuronal differentiation and are also implicated in the genesis of Alzheimer disease in humans. Northern blot analysis determined that the turtle hypothalamus contains a single APLP-2 transcript of 3.75 kb in length. Exposure to OP upregulated hypothalamic APLP-2 mRNA levels 2-fold (p < 0.05) in month-old and yearling turtles. E(2) did not affect APLP-2 mRNA levels in hatchlings but stimulated a 2-fold increase (p < 0.05) in APLP-2 mRNA levels in yearling males. The protein beta-amyloid, a selectively processed peptide derived from APP, is also involved in neuronal differentiation, and accumulation of this neurotoxic peptide causes neuronal degeneration in the brains of patients with Alzheimer disease. Therefore, we also sought to determine the effects of estrogens on the expression of beta-amyloid. Using homology cloning based on known sequences, we isolated a cDNA fragment (474 bp) from turtle brain with 88% identity to human APP. Northern blot analysis determined that a single 3.5-kb transcript was expressed in the turtle hypothalamus. Waterborne OP also increased the expression of hypothalamic APP after 35 days of

Automated solid-state NMR resonance assignment of protein microcrystals and amyloids

International Nuclear Information System (INIS)

Schmidt, Elena; Gath, Julia; Habenstein, Birgit; Ravotti, Francesco; Székely, Kathrin; Huber, Matthias; Buchner, Lena; Böckmann, Anja; Meier, Beat H.; Güntert, Peter

2013-01-01

Solid-state NMR is an emerging structure determination technique for crystalline and non-crystalline protein assemblies, e.g., amyloids. Resonance assignment constitutes the first and often very time-consuming step to a structure. We present ssFLYA, a generally applicable algorithm for automatic assignment of protein solid-state NMR spectra. Application to microcrystals of ubiquitin and the Ure2 prion C-terminal domain, as well as amyloids of HET-s(218–289) and α-synuclein yielded 88–97 % correctness for the backbone and side-chain assignments that are classified as self-consistent by the algorithm, and 77–90 % correctness if also assignments classified as tentative by the algorithm are included

Hemin as a generic and potent protein misfolding inhibitor

Energy Technology Data Exchange (ETDEWEB)

Liu, Yanqin [School of Chemistry and Physics, The University of Adelaide, Adelaide, SA 5005 (Australia); Carver, John A. [Discipline of Pharmacology, The University of Adelaide, Adelaide, SA 5005 (Australia); Ho, Lam H.; Elias, Abigail K. [School of Chemistry and Physics, The University of Adelaide, Adelaide, SA 5005 (Australia); Musgrave, Ian F. [Research School of Chemistry, The Australian National University, Canberra, ACT 0200 (Australia); Pukala, Tara L., E-mail: tara.pukala@adelaide.edu.au [School of Chemistry and Physics, The University of Adelaide, Adelaide, SA 5005 (Australia)

2014-11-14

Highlights: • Hemin prevents Aβ42, α-synuclein and RCM-κ-casein forming amyloid fibrils. • Hemin inhibits the β-sheet structure formation of Aβ42. • Hemin reduces the cell toxicity caused by fibrillar Aβ42. • Hemin dissociates partially formed Aβ42 fibrils. • Hemin prevents amorphous aggregation by ADH, catalase and γs-crystallin. - Abstract: Protein misfolding causes serious biological malfunction, resulting in diseases including Alzheimer’s disease, Parkinson’s disease and cataract. Molecules which inhibit protein misfolding are a promising avenue to explore as therapeutics for the treatment of these diseases. In the present study, thioflavin T fluorescence and transmission electron microscopy experiments demonstrated that hemin prevents amyloid fibril formation of kappa-casein, amyloid beta peptide and α-synuclein by blocking β-sheet structure assembly which is essential in fibril aggregation. Further, inhibition of fibril formation by hemin significantly reduces the cytotoxicity caused by fibrillar amyloid beta peptide in vitro. Interestingly, hemin degrades partially formed amyloid fibrils and prevents further aggregation to mature fibrils. Light scattering assay results revealed that hemin also prevents protein amorphous aggregation of alcohol dehydrogenase, catalase and γs-crystallin. In summary, hemin is a potent agent which generically stabilises proteins against aggregation, and has potential as a key molecule for the development of therapeutics for protein misfolding diseases.

Disease Transmission by Misfolded Prion-Protein Isoforms, Prion-Like Amyloids, Functional Amyloids and the Central Dogma.

Science.gov (United States)

Daus, Martin L

2016-01-04

In 1982, the term "prions" (proteinaceous infectious particles) was coined to specify a new principle of infection. A misfolded isoform of a cellular protein has been described as the causative agent of a fatal neurodegenerative disease. At the beginning of prion research scientists assumed that the infectious agent causing transmissible spongiform encephalopathy (TSE) was a virus, but some unconventional properties of these pathogens were difficult to bring in line with the prevailing viral model. The discovery that prions (obviously devoid of any coding nucleic acid) can store and transmit information similarly to DNA was initially even denoted as being "heretical" but is nowadays mainly accepted by the scientific community. This review describes, from a historical point of view, how the "protein-only hypothesis" expands the Central Dogma. Definition of both, the prion principle and the Central Dogma, have been essential steps to understand information storage and transfer within and among cells and organisms. Furthermore, the current understanding of the infectivity of prion-proteins after misfolding is summarized succinctly. Finally, prion-like amyloids and functional amyloids, as found in yeast and bacteria, will be discussed.

Disease Transmission by Misfolded Prion-Protein Isoforms, Prion-Like Amyloids, Functional Amyloids and the Central Dogma

Directory of Open Access Journals (Sweden)

Martin L. Daus

2016-01-01

Full Text Available In 1982, the term “prions” (proteinaceous infectious particles was coined to specify a new principle of infection. A misfolded isoform of a cellular protein has been described as the causative agent of a fatal neurodegenerative disease. At the beginning of prion research scientists assumed that the infectious agent causing transmissible spongiform encephalopathy (TSE was a virus, but some unconventional properties of these pathogens were difficult to bring in line with the prevailing viral model. The discovery that prions (obviously devoid of any coding nucleic acid can store and transmit information similarly to DNA was initially even denoted as being “heretical” but is nowadays mainly accepted by the scientific community. This review describes, from a historical point of view, how the “protein-only hypothesis” expands the Central Dogma. Definition of both, the prion principle and the Central Dogma, have been essential steps to understand information storage and transfer within and among cells and organisms. Furthermore, the current understanding of the infectivity of prion-proteins after misfolding is summarized succinctly. Finally, prion-like amyloids and functional amyloids, as found in yeast and bacteria, will be discussed.

Increasing protein stability by improving beta-turns.

Science.gov (United States)

Fu, Hailong; Grimsley, Gerald R; Razvi, Abbas; Scholtz, J Martin; Pace, C Nick

2009-11-15

Our goal was to gain a better understanding of how protein stability can be increased by improving beta-turns. We studied 22 beta-turns in nine proteins with 66-370 residues by replacing other residues with proline and glycine and measuring the stability. These two residues are statistically preferred in some beta-turn positions. We studied: Cold shock protein B (CspB), Histidine-containing phosphocarrier protein, Ubiquitin, Ribonucleases Sa2, Sa3, T1, and HI, Tryptophan synthetase alpha-subunit, and Maltose binding protein. Of the 15 single proline mutations, 11 increased stability (Average = 0.8 +/- 0.3; Range = 0.3-1.5 kcal/mol), and the stabilizing effect of double proline mutants was additive. On the basis of this and our previous work, we conclude that proteins can generally be stabilized by replacing nonproline residues with proline residues at the i + 1 position of Type I and II beta-turns and at the i position in Type II beta-turns. Other turn positions can sometimes be used if the phi angle is near -60 degrees for the residue replaced. It is important that the side chain of the residue replaced is less than 50% buried. Identical substitutions in beta-turns in related proteins give similar results. Proline substitutions increase stability mainly by decreasing the entropy of the denatured state. In contrast, the large, diverse group of proteins considered here had almost no residues in beta-turns that could be replaced by Gly to increase protein stability. Improving beta-turns by substituting Pro residues is a generally useful way of increasing protein stability. 2009 Wiley-Liss, Inc.

Differences in functional brain connectivity alterations associated with cerebral amyloid deposition in amnestic mild cognitive impairment

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Dahyun eYi

2015-02-01

Full Text Available Despite potential implications for the early detection of impending AD, very little is known about the differences of large scale brain networks between amnestic MCI (aMCI with high cerebral amyloid beta protein (Aβ deposition (i.e., aMCI+ and aMCI with no or very little Aβ deposition (i.e., aMCI-. We first aimed to extend the current literature on altering intrinsic functional connectivity (FC of the default mode network (DMN and salience network (SN from CN to AD dementia. Second, we further examined the differences of the DMN and the SN between aMCI-, aMCI+, and CN. Forty-three older adult (12 CN, 10 aMCI+, 10 aMCI-, and 11 AD dementia subjects were included. All participants received clinical and neuropsychological assessment, resting state functional MRI, structural MRI, and Pittsburgh compound-B-PET scans. FC data were preprocessed using Multivariate Exploratory Linear Optimized Decomposition into Independent Components of FSL. Group comparisons were carried out using the dual-regression approach. In addition, to verify presence of grey matter (GM volume changes with intrinsic functional network alterations, Voxel Based Morphometry was performed on the acquired T1-weighted data. As expected, AD dementia participants exhibited decreased FC in the DMN compared to CN (in precuneus and cingulate gyrus. The degree of alteration in the DMN in aMCI+ compared to CN was intermediate to that of AD. In contrast, aMCI- exhibited increased FC in the DMN compared to CN (in precuneus as well as aMCI+. In terms of the SN, aMCI- exhibited decreased FC compared to both CN and aMCI+ particularly in the inferior frontal gyrus. FC within the SN in aMCI+ and AD did not differ from CN. Compared to CN, aMCI- showed atrophy in bilateral superior temporal gyri whereas aMCI+ showed atrophy in right precuneus. The results indicate that despite of the similarity in cross-sectional cognitive features aMCI- has quite different functional brain connectivity compared to

Redundancy and divergence in the amyloid precursor protein family.

Science.gov (United States)

Shariati, S Ali M; De Strooper, Bart

2013-06-27

Gene duplication provides genetic material required for functional diversification. An interesting example is the amyloid precursor protein (APP) protein family. The APP gene family has experienced both expansion and contraction during evolution. The three mammalian members have been studied quite extensively in combined knock out models. The underlying assumption is that APP, amyloid precursor like protein 1 and 2 (APLP1, APLP2) are functionally redundant. This assumption is primarily supported by the similarities in biochemical processing of APP and APLPs and on the fact that the different APP genes appear to genetically interact at the level of the phenotype in combined knockout mice. However, unique features in each member of the APP family possibly contribute to specification of their function. In the current review, we discuss the evolution and the biology of the APP protein family with special attention to the distinct properties of each homologue. We propose that the functions of APP, APLP1 and APLP2 have diverged after duplication to contribute distinctly to different neuronal events. Our analysis reveals that APLP2 is significantly diverged from APP and APLP1. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Clinical and MRI models predicting amyloid deposition in progressive aphasia and apraxia of speech.

Science.gov (United States)

Whitwell, Jennifer L; Weigand, Stephen D; Duffy, Joseph R; Strand, Edythe A; Machulda, Mary M; Senjem, Matthew L; Gunter, Jeffrey L; Lowe, Val J; Jack, Clifford R; Josephs, Keith A

2016-01-01

Beta-amyloid (Aβ) deposition can be observed in primary progressive aphasia (PPA) and progressive apraxia of speech (PAOS). While it is typically associated with logopenic PPA, there are exceptions that make predicting Aβ status challenging based on clinical diagnosis alone. We aimed to determine whether MRI regional volumes or clinical data could help predict Aβ deposition. One hundred and thirty-nine PPA (n = 97; 15 agrammatic, 53 logopenic, 13 semantic and 16 unclassified) and PAOS (n = 42) subjects were prospectively recruited into a cross-sectional study and underwent speech/language assessments, 3.0 T MRI and C11-Pittsburgh Compound B PET. The presence of Aβ was determined using a 1.5 SUVR cut-point. Atlas-based parcellation was used to calculate gray matter volumes of 42 regions-of-interest across the brain. Penalized binary logistic regression was utilized to determine what combination of MRI regions, and what combination of speech and language tests, best predicts Aβ (+) status. The optimal MRI model and optimal clinical model both performed comparably in their ability to accurately classify subjects according to Aβ status. MRI accurately classified 81% of subjects using 14 regions. Small left superior temporal and inferior parietal volumes and large left Broca's area volumes were particularly predictive of Aβ (+) status. Clinical scores accurately classified 83% of subjects using 12 tests. Phonological errors and repetition deficits, and absence of agrammatism and motor speech deficits were particularly predictive of Aβ (+) status. In comparison, clinical diagnosis was able to accurately classify 89% of subjects. However, the MRI model performed well in predicting Aβ deposition in unclassified PPA. Clinical diagnosis provides optimum prediction of Aβ status at the group level, although regional MRI measurements and speech and language testing also performed well and could have advantages in predicting Aβ status in unclassified PPA subjects.

Clinical and MRI models predicting amyloid deposition in progressive aphasia and apraxia of speech

Directory of Open Access Journals (Sweden)

Jennifer L. Whitwell

2016-01-01

Full Text Available Beta-amyloid (Aβ deposition can be observed in primary progressive aphasia (PPA and progressive apraxia of speech (PAOS. While it is typically associated with logopenic PPA, there are exceptions that make predicting Aβ status challenging based on clinical diagnosis alone. We aimed to determine whether MRI regional volumes or clinical data could help predict Aβ deposition. One hundred and thirty-nine PPA (n = 97; 15 agrammatic, 53 logopenic, 13 semantic and 16 unclassified and PAOS (n = 42 subjects were prospectively recruited into a cross-sectional study and underwent speech/language assessments, 3.0 T MRI and C11-Pittsburgh Compound B PET. The presence of Aβ was determined using a 1.5 SUVR cut-point. Atlas-based parcellation was used to calculate gray matter volumes of 42 regions-of-interest across the brain. Penalized binary logistic regression was utilized to determine what combination of MRI regions, and what combination of speech and language tests, best predicts Aβ (+ status. The optimal MRI model and optimal clinical model both performed comparably in their ability to accurately classify subjects according to Aβ status. MRI accurately classified 81% of subjects using 14 regions. Small left superior temporal and inferior parietal volumes and large left Broca's area volumes were particularly predictive of Aβ (+ status. Clinical scores accurately classified 83% of subjects using 12 tests. Phonological errors and repetition deficits, and absence of agrammatism and motor speech deficits were particularly predictive of Aβ (+ status. In comparison, clinical diagnosis was able to accurately classify 89% of subjects. However, the MRI model performed well in predicting Aβ deposition in unclassified PPA. Clinical diagnosis provides optimum prediction of Aβ status at the group level, although regional MRI measurements and speech and language testing also performed well and could have advantages in predicting Aβ status in unclassified

Zn(II)- and Cu(II)-induced non-fibrillar aggregates of amyloid-beta (1-42) peptide are transformed to amyloid fibrils, both spontaneously and under the influence of metal chelators.

Science.gov (United States)

Tõugu, Vello; Karafin, Ann; Zovo, Kairit; Chung, Roger S; Howells, Claire; West, Adrian K; Palumaa, Peep

2009-09-01

Aggregation of amyloid-beta (Abeta) peptides is a central phenomenon in Alzheimer's disease. Zn(II) and Cu(II) have profound effects on Abeta aggregation; however, their impact on amyloidogenesis is unclear. Here we show that Zn(II) and Cu(II) inhibit Abeta(42) fibrillization and initiate formation of non-fibrillar Abeta(42) aggregates, and that the inhibitory effect of Zn(II) (IC(50) = 1.8 micromol/L) is three times stronger than that of Cu(II). Medium and high-affinity metal chelators including metallothioneins prevented metal-induced Abeta(42) aggregation. Moreover, their addition to preformed aggregates initiated fast Abeta(42) fibrillization. Upon prolonged incubation the metal-induced aggregates also transformed spontaneously into fibrils, that appear to represent the most stable state of Abeta(42). H13A and H14A mutations in Abeta(42) reduced the inhibitory effect of metal ions, whereas an H6A mutation had no significant impact. We suggest that metal binding by H13 and H14 prevents the formation of a cross-beta core structure within region 10-23 of the amyloid fibril. Cu(II)-Abeta(42) aggregates were neurotoxic to neurons in vitro only in the presence of ascorbate, whereas monomers and Zn(II)-Abeta(42) aggregates were non-toxic. Disturbed metal homeostasis in the vicinity of zinc-enriched neurons might pre-dispose formation of metal-induced Abeta aggregates, subsequent fibrillization of which can lead to amyloid formation. The molecular background underlying metal-chelating therapies for Alzheimer's disease is discussed in this light.

Quantitative longitudinal interrelationships between brain metabolism and amyloid deposition during a 2-year follow-up in patients with early Alzheimer's disease

International Nuclear Information System (INIS)

Foerster, Stefan; Yousefi, Behrooz H.; Wester, Hans-Juergen; Klupp, Elisabeth; Rominger, Axel; Foerstl, Hans; Kurz, Alexander; Grimmer, Timo; Drzezga, Alexander

2012-01-01

Similar regional anatomical distributions were reported for fibrillary amyloid deposition [measured by 11 C-Pittsburgh compound B (PIB) positron emission tomography (PET)] and brain hypometabolism [measured by 18 F-fluorodeoxyglucose (FDG) PET] in numerous Alzheimer's disease (AD) studies. However, there is a lack of longitudinal studies evaluating the interrelationships of these two different pathological markers in the same AD population. Our most recent AD study suggested that the longitudinal pattern of hypometabolism anatomically follows the pattern of amyloid deposition with temporal delay, which indicates that neuronal dysfunction may spread within the anatomical pattern of amyloid pathology. Based on this finding we now hypothesize that in early AD patients quantitative longitudinal decline in hypometabolism may be related to the amount of baseline amyloid deposition during a follow-up period of 2 years. Fifteen patients with mild probable AD underwent baseline (T1) and follow-up (T2) examination after 24 ± 2.1 months with [ 18 F]FDG PET, [ 11 C]PIB PET, structural T1-weighted MRI and neuropsychological testing [Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neuropsychological battery]. Longitudinal cognitive measures and quantitative PET measures of amyloid deposition and metabolism [standardized uptake value ratios (SUVRs)] were obtained using volume of interest (VOI)-based approaches in the frontal-lateral-retrosplenial (FLR) network and in predefined bihemispheric brain regions after partial volume effect (PVE) correction of PET data. Statistical group comparisons (SUVRs and cognitive measures) between patients and 15 well-matched elderly controls who had undergone identical imaging procedures once as well as Pearson's correlation analyses within patients were performed. Group comparison revealed significant cognitive decline and increased mean PIB/decreased FDG SUVRs in the FLR network as well as in several AD-typical regions in

Amyloid fibril formation in vitro from halophilic metal binding protein: Its high solubility and reversibility minimized formation of amorphous protein aggregations

Science.gov (United States)

Tokunaga, Yuhei; Matsumoto, Mitsuharu; Tokunaga, Masao; Arakawa, Tsutomu; Sugimoto, Yasushi

2013-01-01

Halophilic proteins are characterized by high net negative charges and relatively small fraction of hydrophobic amino acids, rendering them aggregation resistant. These properties are also shared by histidine-rich metal binding protein (HP) from moderate halophile, Chromohalobacter salexigens, used in this study. Here, we examined how halophilic proteins form amyloid fibrils in vitro. His-tagged HP, incubated at pH 2.0 and 58°C, readily formed amyloid fibrils, as observed by thioflavin fluorescence, CD spectra, and transmission or atomic force microscopies. Under these low-pH harsh conditions, however, His-HP was promptly hydrolyzed to smaller peptides most likely responsible for rapid formation of amyloid fibril. Three major acid-hydrolyzed peptides were isolated from fibrils and turned out to readily form fibrils. The synthetic peptides predicted to form fibrils in these peptide sequences by Waltz software also formed fibrils. Amyloid fibril was also readily formed from full-length His-HP when incubated with 10–20% 2,2,2-trifluoroethanol at pH 7.8 and 25°C without peptide bond cleavage. PMID:24038709

Origin of life. Primordial genetics: Information transfer in a pre-RNA world based on self-replicating beta-sheet amyloid conformers.

Science.gov (United States)

Maury, Carl Peter J

2015-10-07

The question of the origin of life on Earth can largely be reduced to the question of what was the first molecular replicator system that was able to replicate and evolve under the presumably very harsh conditions on the early Earth. It is unlikely that a functional RNA could have existed under such conditions and it is generally assumed that some other kind of information system preceded the RNA world. Here, I present an informational molecular system that is stable, self-replicative, environmentally responsive, and evolvable under conditions characterized by high temperatures, ultraviolet and cosmic radiation. This postulated pregenetic system is based on the amyloid fold, a functionally unique polypeptide fold characterized by a cross beta-sheet structure in which the beta strands are arranged perpendicular to the fiber axis. Beside an extraordinary structural robustness, the amyloid fold possesses a unique ability to transmit information by a three-dimensional templating mechanism. In amyloidogenesis short peptide monomers are added one by one to the growing end of the fiber. From the same monomeric subunits several structural variants of amyloid may be formed. Then, in a self-replicative mode, a specific amyloid conformer can act as a template and confer its spatially encoded information to daughter molecular entities in a repetitive way. In this process, the specific conformational information, the spatially changed organization, is transmitted; the coding element is the steric zipper structure, and recognition occurs by amino acid side chain complementarity. The amyloid information system fulfills several basic requirements of a primordial evolvable replicator system: (i) it is stable under the presumed primitive Earth conditions, (ii) the monomeric building blocks of the informational polymer can be formed from available prebiotic compounds, (iii) the system is self-assembling and self-replicative and (iv) it is adaptive to changes in the environment and

Surface Mediated Self-Assembly of Amyloid Peptides

Science.gov (United States)

Fakhraai, Zahra

2015-03-01

Amyloid fibrils have been considered as causative agents in many neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, type II diabetes and amyloidosis. Amyloid fibrils form when proteins or peptides misfold into one dimensional crystals of stacked beta-sheets. In solution, amyloid fibrils form through a nucleation and growth mechanism. The rate limiting nucleation step requires a critical concentration much larger than those measured in physiological conditions. As such the exact origins of the seeds or oligomers that result in the formation of fully mature fibrils in the body remain topic intense studies. It has been suggested that surfaces and interfaces can enhance the fibrillization rate. However, studies of the mechanism and kinetics of the surface-mediated fibrillization are technologically challenging due to the small size of the oligomer and protofibril species. Using smart sample preparation technique to dry the samples after various incubation times we are able to study the kinetics of fibril formation both in solution and in the vicinity of various surfaces using high-resolution atomic force microscopy. These studies elucidate the role of surfaces in catalyzing amyloid peptide formation through a nucleation-free process. The nucleation free self-assembly is rapid and requires much smaller concentrations of peptides or proteins. We show that this process resembles diffusion limited aggregation and is governed by the peptide adhesion rate, two -dimensional diffusion of the peptides on the surface, and preferential interactions between the peptides. These studies suggest an alternative pathway for amyloid formation may exist, which could lead to new criteria for disease prevention and alternative therapies. Research was partially supported by a seed grant from the National Institute of Aging of the National Institutes of Health (NIH) under Award Number P30AG010124 (PI: John Trojanowski) and the University of Pennsylvania.

Viscoelasticity of amyloid plaques in transgenic mouse brain studied by Brillouin microspectroscopy and correlative Raman analysis

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Sara Mattana

2017-11-01

Full Text Available Amyloidopathy is one of the most prominent hallmarks of Alzheimer’s disease (AD, the leading cause of dementia worldwide, and is characterized by the accumulation of amyloid plaques in the brain parenchyma. The plaques consist of abnormal deposits mainly composed of an aggregation-prone protein fragment, β-amyloid 1-40/1-42, into the extracellular matrix. Brillouin microspectroscopy is an all-optical contactless technique that is based on the interaction between visible light and longitudinal acoustic waves or phonons, giving access to the viscoelasticity of a sample on a subcellular scale. Here, we describe the first application of micromechanical mapping based on Brillouin scattering spectroscopy to probe the stiffness of individual amyloid plaques in the hippocampal part of the brain of a β-amyloid overexpressing transgenic mouse. Correlative analysis based on Brillouin and Raman microspectroscopy showed that amyloid plaques have a complex structure with a rigid core of β-pleated sheet conformation (β-amyloid protein surrounded by a softer ring-shaped region richer in lipids and other protein conformations. These preliminary results give a new insight into the plaque biophysics and biomechanics, and a valuable contrast mechanism for the study and diagnosis of amyloidopathy.

Proteomic analysis of highly prevalent amyloid A amyloidosis endemic to endangered island foxes.

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Patricia M Gaffney

Full Text Available Amyloid A (AA amyloidosis is a debilitating, often fatal, systemic amyloid disease associated with chronic inflammation and persistently elevated serum amyloid A (SAA. Elevated SAA is necessary but not sufficient to cause disease and the risk factors for AA amyloidosis remain poorly understood. Here we identify an extraordinarily high prevalence of AA amyloidosis (34% in a genetically isolated population of island foxes (Urocyon littoralis with concurrent chronic inflammatory diseases. Amyloid deposits were most common in kidney (76%, spleen (58%, oral cavity (45%, and vasculature (44% and were composed of unbranching, 10 nm in diameter fibrils. Peptide sequencing by mass spectrometry revealed that SAA peptides were dominant in amyloid-laden kidney, together with high levels of apolipoprotein E, apolipoprotein A-IV, fibrinogen-α chain, and complement C3 and C4 (false discovery rate ≤ 0.05. Reassembled peptide sequences showed island fox SAA as an 111 amino acid protein, most similar to dog and artic fox, with 5 unique amino acid variants among carnivores. SAA peptides extended to the last two C-terminal amino acids in 5 of 9 samples, indicating that near full length SAA was often present in amyloid aggregates. These studies define a remarkably prevalent AA amyloidosis in island foxes with widespread systemic amyloid deposition, a unique SAA sequence, and the co-occurrence of AA with apolipoproteins.

A comparison of serum amyloid A (SAA) synthesis with that of the pentraxins: Serum amyloid P (SAP) and C-reactive protein (CRP)

International Nuclear Information System (INIS)

Tatsuta, E.; Shirahama, T.; Sipe, J.D.; Skinner, M.

1986-01-01

Serum amyloid A (SAA) and serum amyloid P (SAP) were detected in cultures of hepatocytes which had been isolated from normal CBA/J mice by the collagenase perfusion technique. SAP production in 24 h cultures was more resistant than SAA and total protein synthesis to inhibition by actinomycin D, but was more sensitive to inhibition by 48 h. However, the production of SAP was more sensitive to cycloheximide than SAA and total protein throughout the 48 hr incubation period. SAP and SAA levels in the culture media were suppressed by treatment of liver cells with 10 -6 M of colchicine for 48 h. Inhibition of SAP production by colchicine was the same regardless of culture condition, but the effect of colchicine on SAA synthesis varied according to the presence of serum of monokine. These observations also support the concept that the two amyloid proteins are produced under different regulatory mechanisms. When C-reactive protein (CRP) was not detected in the sera of patients with severe chronic liver diseases, the SAA levels were very low. When CRP was detected, SAA values were within the normal range. Thus, in order to produce SAA, liver cells in these patients not only were viable but also maintained their specialized function

IS BRAIN AMYLOID PRODUCTION A CAUSE OR A RESULT OF DEMENTIA OF THE ALZHEIMER TYPE?

Science.gov (United States)

Ala, Tom; Patrylo, Peter R.; Brewer, Gregory J.; Yan, Xiao-Xin

2011-01-01

The amyloid cascade hypothesis has guided much of research into Alzheimer disease (AD) over the last 25 years. We argue that the hypothesis of beta amyloid (Aβ) as the primary cause of dementia may not be fully correct. Rather, we propose that decline in brain metabolic activity, which is tightly linked to synaptic activity, actually underlies both the cognitive decline and the deposition of Aβ. Aβ may further exacerbate metabolic decline and result in a downward spiral of cognitive function, leading to dementia. This novel interpretation can tie the disparate risk factors for dementia to a unifying hypothesis and present a roadmap for interventions to decrease the prevalence of dementia in the elderly population. PMID:20847431

The metabolic enhancer piracetam ameliorates the impairment of mitochondrial function and neurite outgrowth induced by beta-amyloid peptide.

Science.gov (United States)

Kurz, C; Ungerer, I; Lipka, U; Kirr, S; Schütt, T; Eckert, A; Leuner, K; Müller, W E

2010-05-01

beta-Amyloid peptide (Abeta) is implicated in the pathogenesis of Alzheimer's disease by initiating a cascade of events from mitochondrial dysfunction to neuronal death. The metabolic enhancer piracetam has been shown to improve mitochondrial dysfunction following brain aging and experimentally induced oxidative stress. We used cell lines (PC12 and HEK cells) and murine dissociated brain cells. The protective effects of piracetam in vitro and ex vivo on Abeta-induced impairment of mitochondrial function (as mitochondrial membrane potential and ATP production), on secretion of soluble Abeta and on neurite outgrowth in PC12 cells were investigated. Piracetam improves mitochondrial function of PC12 cells and acutely dissociated brain cells from young NMRI mice following exposure to extracellular Abeta(1-42). Similar protective effects against Abeta(1-42) were observed in dissociated brain cells from aged NMRI mice, or mice transgenic for mutant human amyloid precursor protein (APP) treated with piracetam for 14 days. Soluble Abeta load was markedly diminished in the brain of those animals after treatment with piracetam. Abeta production by HEK cells stably transfected with mutant human APP was elevated by oxidative stress and this was reduced by piracetam. Impairment of neuritogenesis is an important consequence of Abeta-induced mitochondrial dysfunction and Abeta-induced reduction of neurite growth in PC12 cells was substantially improved by piracetam. Our findings strongly support the concept of improving mitochondrial function as an approach to ameliorate the detrimental effects of Abeta on brain function.

Clinical approach of patients with systemic amyloidosis

NARCIS (Netherlands)

Hazenberg, Bouke

2011-01-01

Amyloidosis is the name of diseases characterised by deposition of protein fibrils with a beta-sheet structure. This beta-sheet structure generates affinity of amyloid for Congo red dye and is resistant to proteolysis. The main three types of systemic amyloidosis are AA (related to underlying

Strong transthyretin immunostaining: potential pitfall in cardiac amyloid typing.

Science.gov (United States)

Satoskar, Anjali A; Efebera, Yvonne; Hasan, Ayesha; Brodsky, Sergey; Nadasdy, Gyongyi; Dogan, Ahmet; Nadasdy, Tibor

2011-11-01

Although systemic amyloidosis commonly presents with renal disease, cardiac involvement usually determines the patient's prognosis. Cardiac involvement is seen in light chain amyloid and transthyretin amyloidosis. Distinguishing between these two is critical because prognosis and treatment differ. Our study demonstrates the unreliability of transthyretin immunostaining in subtyping cardiac amyloid. Between January 2003 and August 2010, we retrieved 229 native endomyocardial biopsies, of which 24 had amyloid. Immunohistochemistry for κ, λ, transthyretin, and serum amyloid A protein was performed on formalin-fixed, paraffin-embedded sections. Staining was graded as weak (trace to 1+) or strong (2 to 3+). Mass spectrometry (MS)-based proteomic typing of microdissected amyloid material was performed on selected cases. Fifteen patients had monoclonal gammopathy/plasma cell dyscrasia with cardiac amyloid. Eight of them (53%) showed strong transthyretin staining in the cardiac amyloid deposits. MS was performed in 5 of these 8 biopsies, and all 5 biopsies revealed light chain amyloid-type amyloid. Two of these 5 light chain amyloid biopsies did not even have concomitant strong staining for the appropriate light chain. Among the 15 cases with plasma cell dyscrasia, only 7 biopsies showed strong staining for the corresponding monoclonal light chain. Strong, false-positive immunostaining for transthyretin in cardiac amyloid is a potential pitfall, augmented by the frequent lack of staining for immunoglobulin light chains. Therefore, the presence of amyloid in the cardiac biopsy should prompt a search for plasma cell dyscrasia irrespective of transthyretin staining. Confirmation with MS should be sought, particularly if there is any discrepancy between κ/λ staining and serum immunofixation results.

Methyl Salicylate Lactoside Protects Neurons Ameliorating Cognitive Disorder Through Inhibiting Amyloid Beta-Induced Neuroinflammatory Response in Alzheimer's Disease.

Science.gov (United States)

Li, Jinze; Ma, Xiaowei; Wang, Yu; Chen, Chengjuan; Hu, Min; Wang, Linlin; Fu, Junmin; Shi, Gaona; Zhang, Dongming; Zhang, Tiantai

2018-01-01

Neuroinflammatory reactions mediated by microglia and astrocytes have been shown to play a key role in early progression of Alzheimer's disease (AD). Increased evidences have demonstrated that neurons exacerbate local inflammatory reactions by producing inflammatory mediators and act as an important participant in the pathogenesis of AD. Methyl salicylate lactoside (MSL) is an isolated natural product that is part of a class of novel non-steroidal anti-inflammatory drugs (NSAID). In our previous studies, we demonstrated that MSL exhibited therapeutic effects on arthritis-induced mice and suppressed the activation of glial cells. In the current study, we investigated the effects of MSL on cognitive function and neuronal protection induced by amyloid-beta peptides (Aβ) and explored potential underlying mechanisms involved. Amyloid precursor protein (APP) and presenilin 1 (PS1) double transgenic mice were used to evaluate the effects of MSL through behavioral testing and neuronal degenerative changes. In addition, copper-injured APP Swedish mutation overexpressing SH-SY5Y cells were used to determine the transduction of cyclooxygenase (COX) and mitogen-activated protein kinase (MAPK) pathways. Our results indicated that at an early stage, MSL treatment ameliorated cognitive impairment and neurodegeneration in APP/PS1 mice. Moreover, in an in vitro AD model, MSL treatment protected injured cells by increasing cell viability, improving mitochondrial dysfunction, and decreasing oxidative damage. In addition, MSL inhibited the phosphorylated level of c-Jun N-terminal kinase (JNK) and p38 MAPK, and suppressed the expression of COX-1/2. As a novel NSAIDs and used for the treatment in early stage of AD, MSL clearly demonstrated cognitive preservation by protecting neurons via a pleiotropic anti-inflammatory effect in the context of AD-associated deficits. Therefore, early treatment of anti-inflammatory therapy may be an effective strategy for treating AD.

Vitamin k3 inhibits protein aggregation: Implication in the treatment of amyloid diseases.

Science.gov (United States)

Alam, Parvez; Chaturvedi, Sumit Kumar; Siddiqi, Mohammad Khursheed; Rajpoot, Ravi Kant; Ajmal, Mohd Rehan; Zaman, Masihuz; Khan, Rizwan Hasan

2016-05-27

Protein misfolding and aggregation have been associated with several human diseases such as Alzheimer's, Parkinson's and familial amyloid polyneuropathy etc. In this study, anti-fibrillation activity of vitamin k3 and its effect on the kinetics of amyloid formation of hen egg white lysozyme (HEWL) and Aβ-42 peptide were investigated. Here, in combination with Thioflavin T (ThT) fluorescence assay, circular dichroism (CD), transmission electron microscopy and cell cytotoxicity assay, we demonstrated that vitamin k3 significantly inhibits fibril formation as well as the inhibitory effect is dose dependent manner. Our experimental studies inferred that vitamin k3 exert its neuro protective effect against amyloid induced cytotoxicity through concerted pathway, modifying the aggregation formation towards formation of nontoxic aggregates. Molecular docking demonstrated that vitamin k3 mediated inhibition of HEWL and Aβ-42 fibrillogenesis may be initiated by interacting with proteolytic resistant and aggregation prone regions respectively. This work would provide an insight into the mechanism of protein aggregation inhibition by vitamin k3; pave the way for discovery of other small molecules that may exert similar effect against amyloid formation and its associated neurodegenerative diseases.

Mutation-based structural modification and dynamics study of amyloid beta peptide (1–42: An in-silico-based analysis to cognize the mechanism of aggregation

Directory of Open Access Journals (Sweden)

Pritam Kumar Panda

2016-03-01

Full Text Available Alzheimer's disease is the prevalent cause of premature senility, a progressive mental disorder due to degeneration in brain and deposition of amyloid β peptide (1–42, a misfolded protein in the form of aggregation that prevails for a prolonged time and obstructs every aspect of life. One of the primary hallmarks of the neuropathological disease is the accretion of amyloid β peptide in the brain that leads to Alzheimer's disease, but the mechanism is still a mystery. Several investigations have shown that mutations at specific positions have a significant impact in stability of the peptide as predicted from aggregation profiles. Here in our study, we have analyzed the mutations by substituting residues at position A22G, E22G, E22K, E22Q, D23N, L34V and molecular dynamics have been performed to check the deviation in stability and conformation of the peptide. The results validated that the mutations at specific positions lead to instability and the proline substitution at E22P and L34P stalled the aggregation of the peptide. Keywords: Amyloid β peptide, Alzheimer's disease, Aggregation, Mutational analysis, NAMD, UCSF Chimera, Discovery Studio Visualizer

Increased tau phosphorylation and beta amyloid in the hipocampus of mouse pups by early life lead exposure.

Science.gov (United States)

Li, N; Yu, Z L; Wang, L; Zheng, Y T; Jia, J X; Wang, Q; Zhu, M J; Liu, X L; Xia, X; Li, W J

2010-06-01

The aim of this study was to investigate the effects of maternal lead exposure on the learning and memory ability and expression of tau protein phosphorylation (P-tau) and beta amyloid protein (Abeta) in hippocampus of mice offspring. Pb exposure initiated from beginning of gestation to weaning. Pb acetate administered in drinking solutions was dissolved in distilled deionized water at the concentrations of 0.1%, 0.5% and 1% groups. On the 21 th of postnatal day, the learning and memory ability of the mouse pups was tested by Water Maze test and the Pb levels in blood and hippocampus of the offspring were also determined. The expression of P-tau and Abeta in hippocampus was measured by immunohistochemistry and Western blotting. The Pb levels in blood and hippocampus of all exposure groups were significantly higher than that of the control group ( P < 0.05). In Water Maze test, the performances of 0.5% and 1% groups were worse than that of the control group ( P < 0.05). The expression of P-tau and Abeta was increased in Pb exposed groups than that of the control group ( P < 0.05). Tau hyper-phosphorylation and Abeta increase in the hippocampus of pups may contribute to the impairment of learning and memory associated with maternal Pb exposure.

Liquid Crystal Enabled Early Stage Detection of Beta Amyloid Formation on Lipid Monolayers

Energy Technology Data Exchange (ETDEWEB)

Sadati, Monirosadat [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Apik, Aslin Izmitli [Chemical and Biological Engineering, University of Wisconsin, Madison WI 53706 USA; Armas-Perez, Julio C. [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Martinez-Gonzalez, Jose [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Hernandez-Ortiz, Juan P. [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Departamento de Materiales y Minerales, Facultad de Minas, Universidad Nacional de Colombia, Sede Medellín, Calle 75 # 79A-51, Bloque M17 Medellín Colombia; Abbott, Nicholas L. [Chemical and Biological Engineering, University of Wisconsin, Madison WI 53706 USA; de Pablo, Juan J. [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Argonne National Laboratory, Argonne IL 60439 USA

2015-09-09

Liquid crystals (LCs) can serve as sensitive reporters of interfacial events, and this property has been used for sensing of synthetic or biological toxins. Here it is demonstrated that LCs can distinguish distinct molecular motifs and exhibit a specific response to beta-sheet structures. That property is used to detect the formation of highly toxic protofibrils involved in neurodegenerative diseases, where it is crucial to develop methods that probe the early-stage aggregation of amyloidogenic peptides in the vicinity of biological membranes. In the proposed method, the amyloid fibrils formed at the lipid-decorated LC interface can change the orientation of LCs and form elongated and branched structures that are amplified by the mesogenic medium; however, nonamyloidogenic peptides form ellipsoidal domains of tilted LCs. Moreover, a theoretical and computational analysis is used to reveal the underlying structure of the LC, thereby providing a detailed molecular-level view of the interactions and mechanisms responsible for such motifs. The corresponding signatures can be detected at nanomolar concentrations of peptide by polarized light microscopy and much earlier than the ones that can be identified by fluorescence-based techniques. As such, it offers the potential for early diagnoses of neurodegenerative diseases and for facile testing of inhibitors of amyloid formation.

A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

Energy Technology Data Exchange (ETDEWEB)

Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner, E-mail: maentele@biophysik.uni-frankfurt.de [Institut für Biophysik, Goethe-Universität Frankfurt am Main, Max-von Laue-Straße 1, D-60438 Frankfurt am Main (Germany)

2014-08-15

A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

Science.gov (United States)

Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner

2014-08-01

A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

Insulin Resistance as a Link between Amyloid-Beta and Tau Pathologies in Alzheimer’s Disease

Directory of Open Access Journals (Sweden)

Roger J. Mullins

2017-05-01

Full Text Available Current hypotheses and theories regarding the pathogenesis of Alzheimer’s disease (AD heavily implicate brain insulin resistance (IR as a key factor. Despite the many well-validated metrics for systemic IR, the absence of biomarkers for brain-specific IR represents a translational gap that has hindered its study in living humans. In our lab, we have been working to develop biomarkers that reflect the common mechanisms of brain IR and AD that may be used to follow their engagement by experimental treatments. We present two promising biomarkers for brain IR in AD: insulin cascade mediators probed in extracellular vesicles (EVs enriched for neuronal origin, and two-dimensional magnetic resonance spectroscopy (MRS measures of brain glucose. As further evidence for a fundamental link between brain IR and AD, we provide a novel analysis demonstrating the close spatial correlation between brain expression of genes implicated in IR (using Allen Human Brain Atlas data and tau and beta-amyloid pathologies. We proceed to propose the bold hypotheses that baseline differences in the metabolic reliance on glycolysis, and the expression of glucose transporters (GLUT and insulin signaling genes determine the vulnerability of different brain regions to Tau and/or Amyloid beta (Aβ pathology, and that IR is a critical link between these two pathologies that define AD. Lastly, we provide an overview of ongoing clinical trials that target IR as an angle to treat AD, and suggest how biomarkers may be used to evaluate treatment efficacy and target engagement.

Early Detection of Aβ Deposition in the 5xFAD Mouse by Amyloid PET

Directory of Open Access Journals (Sweden)

Se Jong Oh

2018-01-01

Full Text Available Purpose. 18F-FC119S is a positron emission tomography (PET tracer for imaging β-amyloid (Aβ plaques in Alzheimer’s disease (AD. The aim of this study is to evaluate the efficacy of 18F-FC119S in quantitating Aβ deposition in a mouse model of early amyloid deposition (5xFAD by PET. Method. Dynamic 18F-FC119S PET images were obtained in 5xFAD (n=5 and wild-type (WT mice (n=7. The brain PET images were spatially normalized to the M. Mirrione T2-weighted mouse brain MR template, and the volumes of interest were then automatically drawn on the cortex, hippocampus, thalamus, and cerebellum. The specific binding of 18F-FC119S to Aβ was quantified as the distribution volume ratio using Logan graphical analysis with the cerebellum as a reference tissue. The Aβ levels in the brain were also confirmed by immunohistochemical analysis. Result. For the 5xFAD group, radioactivity levels in the cortex, the hippocampus, and the thalamus were higher than those for the WT group. In these regions, specific binding was approximately 1.2-fold higher in 5xFAD mice than in WT. Immunohistochemistry supported these findings; the 5xFAD showed severe Aβ deposition in the cortex and hippocampus in contrast to the WT group. Conclusion. These results demonstrated that 18F-FC119S PET can successfully distinguish Aβ depositions in 5xFAD mice from WT.

Beneficial characteristics of mechanically functional amyloid fibrils evolutionarily preserved in natural adhesives

Energy Technology Data Exchange (ETDEWEB)

Mostaert, Anika S; Jarvis, Suzanne P [Centre for Research on Adaptive Nanostructures and Nanodevices, Trinity College Dublin, Dublin 2 (Ireland)

2007-01-31

While biological systems are notorious for their complexity, nature sometimes displays mechanisms that are elegant in their simplicity. We have recently identified such a mechanism at work to enhance the mechanical properties of certain natural adhesives. The mechanism is simple because it utilizes a non-specific protein folding and subsequent aggregation process, now thought to be generic for any polypeptide under appropriate conditions. This non-specific folding forms proteinaceous crossed {beta}-sheet amyloid fibrils, which are usually associated with neurodegenerative diseases. Here we show evidence for the beneficial mechanical characteristics of these fibrils discovered in natural adhesives. We suggest that amyloid protein quaternary structures should be considered as a possible generic mechanism for mechanical strength in a range of natural adhesives and other natural materials due to their many beneficial mechanical features and apparent ease of self-assembly.

Phenotypic Screening Identifies Modulators of Amyloid Precursor Protein Processing in Human Stem Cell Models of Alzheimer’s Disease

Directory of Open Access Journals (Sweden)

Philip W. Brownjohn

2017-04-01

Full Text Available Summary: Human stem cell models have the potential to provide platforms for phenotypic screens to identify candidate treatments and cellular pathways involved in the pathogenesis of neurodegenerative disorders. Amyloid precursor protein (APP processing and the accumulation of APP-derived amyloid β (Aβ peptides are key processes in Alzheimer's disease (AD. We designed a phenotypic small-molecule screen to identify modulators of APP processing in trisomy 21/Down syndrome neurons, a complex genetic model of AD. We identified the avermectins, commonly used as anthelmintics, as compounds that increase the relative production of short Aβ peptides at the expense of longer, potentially more toxic peptides. Further studies demonstrated that this effect is not due to an interaction with the core γ-secretase responsible for Aβ production. This study demonstrates the feasibility of phenotypic drug screening in human stem cell models of Alzheimer-type dementia, and points to possibilities for indirectly modulating APP processing, independently of γ-secretase modulation. : In this article, Livesey and colleagues perform a phenotypic drug screen in a human stem cell model of Alzheimer's disease. The anthelminthic avermectins are identified as a family of compounds that increase the production of short Aβ peptides over longer more toxic Aβ forms. The effect is analogous to existing γ-secretase modulators, but is independent of the core γ-secretase complex. Keywords: neural stem cells, Alzheimer's disease, phenotypic screening, iPSCs, human neurons, dementia, Down syndrome, amyloid beta, ivermectin, selamectin

PiB fails to map amyloid deposits in cerebral cortex of aged dogs with canine cognitive dysfunction

DEFF Research Database (Denmark)

Fast, Rikke; Rodell, Anders; Gjedde, Albert

2013-01-01

to the understanding of AD. However, the sensitivity of the biomarker Pittsburgh Compound B (PiB) to the presence of Aβ in humans and in other mammalian species is in doubt. To test the sensitivity and assess the distribution of Aβ in dog brain, we mapped the brains of dogs with signs of CCD (n = 16) and a control......]PiB in the cerebellum, compared to the cerebral cortex. Retention in the cerebellum is at variance with evidence from brains of humans with AD. To confirm the lack of sensitivity, we stained two dog brains with the immunohistochemical marker 6E10, which is sensitive to the presence of both Aβ and Aβ precursor protein......Dogs with Canine Cognitive Dysfunction (CCD) accumulate amyloid beta (Aβ) in the brain. As the cognitive decline and neuropathology of these old dogs share features with Alzheimer's disease (AD), the relation between Aβ and cognitive decline in animal models of cognitive decline is of interest...

Amyloid precursor protein overexpression depresses excitatory transmission through both presynaptic and postsynaptic mechanisms

OpenAIRE

Ting, Jonathan T.; Kelley, Brooke G.; Lambert, Talley J.; Cook, David G.; Sullivan, Jane M.

2006-01-01

Overexpression of the amyloid precursor protein (APP) in hippocampal neurons leads to elevated β-amyloid peptide (Aβ) production and consequent depression of excitatory transmission. The precise mechanisms underlying APP-induced synaptic depression are poorly understood. Uncovering these mechanisms could provide insight into how neuronal function is compromised before cell death during the early stages of Alzheimer's disease. Here we verify that APP up-regulation leads to depression of transm...

LINGO-1 promotes lysosomal degradation of amyloid-β protein precursor

Directory of Open Access Journals (Sweden)

Rian de Laat

2015-03-01

Full Text Available Sequential proteolytic cleavages of amyloid-β protein precursor (AβPP by β-secretase and γ-secretase generate amyloid β (Aβ peptides, which are thought to contribute to Alzheimer's disease (AD. Much of this processing occurs in endosomes following endocytosis of AβPP from the plasma membrane. However, this pathogenic mode of processing AβPP may occur in competition with lysosomal degradation of AβPP, a common fate of membrane proteins trafficking through the endosomal system. Following up on published reports that LINGO-1 binds and promotes the amyloidogenic processing of AβPP we have examined the consequences of LINGO-1/AβPP interactions. We report that LINGO-1 and its paralogs, LINGO-2 and LINGO-3, decrease processing of AβPP in the amyloidogenic pathway by promoting lysosomal degradation of AβPP. We also report that LINGO-1 levels are reduced in AD brain, representing a possible pathogenic mechanism stimulating the generation of Aβ peptides in AD.

The first case of multiple pulmonary granulomas with amyloid deposition in a dental technician; a rare manifestation as an occupational lung disease.

Science.gov (United States)

Hirano, Taizou; Numakura, Tadahisa; Moriyama, Hiroshi; Saito, Ryoko; Shishikura, Yutaka; Shiihara, Jun; Sugiura, Hisatoshi; Ichinose, Masakazu

2018-05-22

Occupational lung diseases, such as pneumoconiosis, are one of the health problems of dental workers that have been receiving increasing interest. Pulmonary amyloidosis is a heterogenous group of diseases, and can be classified into primary (idiopathic) and secondary (associated with various inflammatory diseases, hereditary, or neoplastic). To date, the development of pulmonary amyloidosis in dental workers has not been reported. A 58-year-old Japanese female presented with chest discomfort and low-grade fever that has persisted for 2 months. She was a dental technician but did not regularly wear a dust mask in the workplace. Chest X ray and computed tomography revealed multiple well-defined nodules in both lungs and fluorodeoxyglucose (FDG)-positron emission tomography revealed abnormal FDG uptake in the same lesions with a maximal standardized uptake value (SUV [max]) of 5.6. We next performed thoracoscopic partial resection of the lesions in the right upper and middle lobes. The histological examination of the specimens revealed granuloma formation with foreign body-type giant cells and amyloid deposition that was confirmed by Congo red staining and direct fast scarlet (DFS) staining that produce apple-green birefringence under crossed polarized light. Because there were no other causes underlying the pulmonary amyloidosis, we performed electron probe X-ray microanalysis (EPMA) of the specimens and the result showed silica deposition in the lesions. Based on these results, we finally diagnosed the patient with pulmonary granulomas with amyloid deposition caused by chronic silica exposure. Afterward, her symptoms were improved and the disease has not progressed for 2 years since proper measures against additional occupational exposure were implemented. Our case presented three important clinical insights: First, occupational exposure to silica in a dental workplace could be associated with the development of amyloid deposition in lung. Second, EPMA was useful to

Detection of AA76, a Common Form of Amyloid A Protein, as a Way of Diagnosing AA Amyloidosis.

Science.gov (United States)

Sato, Junji; Okuda, Yasuaki; Kuroda, Takeshi; Yamada, Toshiyuki

2016-01-01

Reactive amyloid deposits consist of amyloid A (AA) proteins, the degradation products of serum amyloid A (SAA). Since the most common species of AA is the amino terminal portion produced by cleavage between residues 76 and 77 of SAA (AA76), the presence of AA76 in tissues could be a consequence of AA amyloid deposition. This study assessed the diagnostic significance of the detection of AA76 for AA amyloidosis using two different approaches. Biopsy specimens (n=130 from 54 subjects) from gastroduodenal mucosa or abdominal fat (n=9 from 9 subjects) of patients who had already been diagnosed with or were suspected of having AA amyloidosis were used. Fixed mucosal sections were subjected to immunohistochemistry using a newly developed antibody recognizing the carboxyl terminal end of AA76 (anti-AA76). The non-fixed materials from gastroduodenal mucosa or abdominal fat were subjected to immunoblotting for detection of the size of AA76. Among the gastroduodenal specimens (n=115) from already diagnosed patients, the positive rates of Congo red staining, immunohistochemistry using anti-AA76, and immunoblotting were 68.4%, 73.0%, and 92.2%, respectively. The anti-AA76 did not stain the supposed SAA in the blood or leakage, which was stained by anti-SAA antibody. AA76 was not detected either by immunohistochemistry or by immunoblot in the materials from patients in whom AA amyloidosis had been ruled out. In the abdominal fat, the immunoblot detected AA76 in 8 materials from 8 already diagnosed patients and did not in 1 patient whose gastroduodenal mucosa was negative. In conclusion, the detection of AA76 may alter the ability to diagnose AA amyloidosis. In immunohistochemistry for fixed specimens, the new anti-AA76 antibody can improve the specificity. Immunoblot for non-fixed materials, which can considerably improve the sensitivity, should be beneficial for small materials like abdominal fat. © 2016 by the Association of Clinical Scientists, Inc.

Poor Memory Performance in Aged Cynomolgus Monkeys with Hippocampal Atrophy, Depletion of Amyloid Beta 1-42 and Accumulation of Tau Proteins in Cerebrospinal Fluid

DEFF Research Database (Denmark)

Darusman, Huda S; Pandelaki, Jacub; Mulyadi, Rahmad

2014-01-01

, aged cynomolgus monkeys were divided into two groups to compare high-performing (n=6) and low-performing (n=6) subjects. Both groups were tested for biomarkers related to Alzheimer's disease and their brains were scanned using structural magnetic resonance imaging. RESULTS: The subjects with poor DRT......BACKGROUND: Due to their similarities in behavior and disease pathology to humans, non-human primate models are desirable to complement small animals as models for the study of age-related dementia. MATERIALS AND METHODS: Based on their performance on delayed response task (DRT) tests of memory...... performance had evidence of atrophy in the hippocampus and cortical areas, significantly lower cerebrospinal fluid levels of amyloid beta amino acid 1-42 (pperforming well on the DRT tests. CONCLUSION: Old, memory...

Methyl Salicylate Lactoside Protects Neurons Ameliorating Cognitive Disorder Through Inhibiting Amyloid Beta-Induced Neuroinflammatory Response in Alzheimer’s Disease

Science.gov (United States)

Li, Jinze; Ma, Xiaowei; Wang, Yu; Chen, Chengjuan; Hu, Min; Wang, Linlin; Fu, Junmin; Shi, Gaona; Zhang, Dongming; Zhang, Tiantai

2018-01-01

Neuroinflammatory reactions mediated by microglia and astrocytes have been shown to play a key role in early progression of Alzheimer’s disease (AD). Increased evidences have demonstrated that neurons exacerbate local inflammatory reactions by producing inflammatory mediators and act as an important participant in the pathogenesis of AD. Methyl salicylate lactoside (MSL) is an isolated natural product that is part of a class of novel non-steroidal anti-inflammatory drugs (NSAID). In our previous studies, we demonstrated that MSL exhibited therapeutic effects on arthritis-induced mice and suppressed the activation of glial cells. In the current study, we investigated the effects of MSL on cognitive function and neuronal protection induced by amyloid-beta peptides (Aβ) and explored potential underlying mechanisms involved. Amyloid precursor protein (APP) and presenilin 1 (PS1) double transgenic mice were used to evaluate the effects of MSL through behavioral testing and neuronal degenerative changes. In addition, copper-injured APP Swedish mutation overexpressing SH-SY5Y cells were used to determine the transduction of cyclooxygenase (COX) and mitogen-activated protein kinase (MAPK) pathways. Our results indicated that at an early stage, MSL treatment ameliorated cognitive impairment and neurodegeneration in APP/PS1 mice. Moreover, in an in vitro AD model, MSL treatment protected injured cells by increasing cell viability, improving mitochondrial dysfunction, and decreasing oxidative damage. In addition, MSL inhibited the phosphorylated level of c-Jun N-terminal kinase (JNK) and p38 MAPK, and suppressed the expression of COX-1/2. As a novel NSAIDs and used for the treatment in early stage of AD, MSL clearly demonstrated cognitive preservation by protecting neurons via a pleiotropic anti-inflammatory effect in the context of AD-associated deficits. Therefore, early treatment of anti-inflammatory therapy may be an effective strategy for treating AD. PMID:29636677

Quantitative longitudinal interrelationships between brain metabolism and amyloid deposition during a 2-year follow-up in patients with early Alzheimer's disease

Energy Technology Data Exchange (ETDEWEB)

Foerster, Stefan [Technische Universitaet Muenchen, Department of Nuclear Medicine, Munich (Germany); Technische Universitaet Muenchen, TUM-Neuroimaging Center (TUM-NIC), Munich (Germany); Technische Universitaet Muenchen (TUM), Klinik und Poliklinik fuer Nuklearmedizin, Klinikum rechts der Isar, Munich (Germany); Yousefi, Behrooz H.; Wester, Hans-Juergen; Klupp, Elisabeth [Technische Universitaet Muenchen, Department of Nuclear Medicine, Munich (Germany); Rominger, Axel [Ludwig Maximilians Universitaet Muenchen, Department of Nuclear Medicine, Munich (Germany); Foerstl, Hans; Kurz, Alexander; Grimmer, Timo [Technische Universitaet Muenchen, Department of Psychiatry and Psychotherapy, Munich (Germany); Drzezga, Alexander [Technische Universitaet Muenchen, Department of Nuclear Medicine, Munich (Germany); Technische Universitaet Muenchen, TUM-Neuroimaging Center (TUM-NIC), Munich (Germany)

2012-12-15

Similar regional anatomical distributions were reported for fibrillary amyloid deposition [measured by {sup 11}C-Pittsburgh compound B (PIB) positron emission tomography (PET)] and brain hypometabolism [measured by {sup 18}F-fluorodeoxyglucose (FDG) PET] in numerous Alzheimer's disease (AD) studies. However, there is a lack of longitudinal studies evaluating the interrelationships of these two different pathological markers in the same AD population. Our most recent AD study suggested that the longitudinal pattern of hypometabolism anatomically follows the pattern of amyloid deposition with temporal delay, which indicates that neuronal dysfunction may spread within the anatomical pattern of amyloid pathology. Based on this finding we now hypothesize that in early AD patients quantitative longitudinal decline in hypometabolism may be related to the amount of baseline amyloid deposition during a follow-up period of 2 years. Fifteen patients with mild probable AD underwent baseline (T1) and follow-up (T2) examination after 24 {+-} 2.1 months with [{sup 18}F]FDG PET, [{sup 11}C]PIB PET, structural T1-weighted MRI and neuropsychological testing [Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neuropsychological battery]. Longitudinal cognitive measures and quantitative PET measures of amyloid deposition and metabolism [standardized uptake value ratios (SUVRs)] were obtained using volume of interest (VOI)-based approaches in the frontal-lateral-retrosplenial (FLR) network and in predefined bihemispheric brain regions after partial volume effect (PVE) correction of PET data. Statistical group comparisons (SUVRs and cognitive measures) between patients and 15 well-matched elderly controls who had undergone identical imaging procedures once as well as Pearson's correlation analyses within patients were performed. Group comparison revealed significant cognitive decline and increased mean PIB/decreased FDG SUVRs in the FLR network as well as

Vitamin k3 inhibits protein aggregation: Implication in the treatment of amyloid diseases

OpenAIRE

Parvez Alam; Sumit Kumar Chaturvedi; Mohammad Khursheed Siddiqi; Ravi Kant Rajpoot; Mohd Rehan Ajmal; Masihuz Zaman; Rizwan Hasan Khan

2016-01-01

Protein misfolding and aggregation have been associated with several human diseases such as Alzheimer?s, Parkinson?s and familial amyloid polyneuropathy etc. In this study, anti-fibrillation activity of vitamin k3 and its effect on the kinetics of amyloid formation of hen egg white lysozyme (HEWL) and A?-42 peptide were investigated. Here, in combination with Thioflavin T (ThT) fluorescence assay, circular dichroism (CD), transmission electron microscopy and cell cytotoxicity assay, we demons...

Glutathione-mimetic D609 alleviates memory deficits and reduces amyloid-β deposition in an AβPP/PS1 transgenic mouse model.

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Yang, Hui; Xie, ZhaoHong; Wei, LiFei; Ding, Mao; Wang, Ping; Bi, JianZhong

2018-04-18

Excessive extracellular deposition of amyloid-β-peptide (Aβ) in the brain is a pathological hallmark of Alzheimer's disease (AD). Oxidative stress is associated with the onset and progression of AD and contributes to Aβ generation. Tricyclodecan-9-yl-xanthogenate (D609) is a glutathione (GSH)-mimetic compound. Although the antioxidant properties of D609 have been well-studied, its potential therapeutic significance on AD remains unclear. In the present study, we used a mouse model of AD to investigate the effects and the mechanism of action of D609 on AD. We found that D609 treatment significantly improved the spatial learning and alleviated the memory decline in the mice harboring amyloid precursor protein (APP) and presenilin-1 (PS1) double mutations (AβPP/PS1 mice). D609 treatment also increased GSH level, GSH and oxidative glutathione ratio, and superoxide dismutase activity, whereas decreased malondialdehyde and protein carbonyl levels, suggesting that D609 alleviated oxidative stress in AβPP/PS1 mice. In addition, D609 reduced β-secretase 1 level and decreased amyloidogenic processing of AβPP, consequently reducing Aβ deposition in the mice. Thus, our findings suggest that D609 might produce beneficial effects on the prevention and treatment of AD.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0/.

The Effect of Milk Constituents and Crowding Agents on Amyloid Fibril Formation by κ-Casein.

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Liu, Jihua; Dehle, Francis C; Liu, Yanqin; Bahraminejad, Elmira; Ecroyd, Heath; Thorn, David C; Carver, John A

2016-02-17

When not incorporated into the casein micelle, κ-casein, a major milk protein, rapidly forms amyloid fibrils at physiological pH and temperature. In this study, the effects of milk components (calcium, lactose, lipids, and heparan sulfate) and crowding agents on reduced and carboxymethylated (RCM) κ-casein fibril formation was investigated using far-UV circular dichroism spectroscopy, thioflavin T binding assays, and transmission electron microscopy. Longer-chain phosphatidylcholine lipids, which form the lining of milk ducts and milk fat globules, enhanced RCM κ-casein fibril formation irrespective of whether the lipids were in a monomeric or micellar state, whereas shorter-chain phospholipids and triglycerides had little effect. Heparan sulfate, a component of the milk fat globule membrane and catalyst of amyloid deposition in extracellular tissue, had little effect on the kinetics of RCM κ-casein fibril formation. Major nutritional components such as calcium and lactose also had no significant effect. Macromolecular crowding enhances protein-protein interactions, but in contrast to other fibril-forming species, the extent of RCM κ-casein fibril formation was reduced by the presence of a variety of crowding agents. These data are consistent with a mechanism of κ-casein fibril formation in which the rate-determining step is dissociation from the oligomer to give the highly amyloidogenic monomer. We conclude that the interaction of κ-casein with membrane-associated phospholipids along its secretory pathway may contribute to the development of amyloid deposits in mammary tissue. However, the formation of spherical oligomers such as casein micelles is favored over amyloid fibrils in the crowded environment of milk, within which the occurrence of amyloid fibrils is low.

Chronic apocynin treatment attenuates beta amyloid plaque size and microglial number in hAPP(751(SL mice.

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Melinda E Lull

Full Text Available NADPH oxidase is implicated in neurotoxic microglial activation and the progressive nature of Alzheimer's Disease (AD. Here, we test the ability of two NADPH oxidase inhibitors, apocynin and dextromethorphan (DM, to reduce learning deficits and neuropathology in transgenic mice overexpressing human amyloid precursor protein with the Swedish and London mutations (hAPP(751(SL.Four month old hAPP(751(SL mice were treated daily with saline, 15 mg/kg DM, 7.5 mg/kg DM, or 10 mg/kg apocynin by gavage for four months.Only hAPP(751(SL mice treated with apocynin showed reduced plaque size and a reduction in the number of cortical microglia, when compared to the saline treated group. Analysis of whole brain homogenates from all treatments tested (saline, DM, and apocynin demonstrated low levels of TNFα, protein nitration, lipid peroxidation, and NADPH oxidase activation, indicating a low level of neuroinflammation and oxidative stress in hAPP(751(SL mice at 8 months of age that was not significantly affected by any drug treatment. Despite in vitro analyses demonstrating that apocynin and DM ameliorate Aβ-induced extracellular superoxide production and neurotoxicity, both DM and apocynin failed to significantly affect learning and memory tasks or synaptic density in hAPP(751(SL mice. To discern how apocynin was affecting plaque levels (plaque load and microglial number in vivo, in vitro analysis of microglia was performed, revealing no apocynin effects on beta-amyloid (Aβ phagocytosis, microglial proliferation, or microglial survival.Together, this study suggests that while hAPP(751(SL mice show increases in microglial number and plaque load, they fail to exhibit elevated markers of neuroinflammation consistent with AD at 8 months of age, which may be a limitation of this animal model. Despite absence of clear neuroinflammation, apocynin was still able to reduce both plaque size and microglial number, suggesting that apocynin may have additional

F-box only protein 2 (Fbxo2) regulates amyloid precursor protein levels and processing.

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Atkin, Graham; Hunt, Jack; Minakawa, Eiko; Sharkey, Lisa; Tipper, Nathan; Tennant, William; Paulson, Henry L

2014-03-07

The amyloid precursor protein (APP) is an integral membrane glycoprotein whose cleavage products, particularly amyloid-β, accumulate in Alzheimer disease (AD). APP is present at synapses and is thought to play a role in both the formation and plasticity of these critical neuronal structures. Despite the central role suggested for APP in AD pathogenesis, the mechanisms regulating APP in neurons and its processing into cleavage products remain incompletely understood. F-box only protein 2 (Fbxo2), a neuron-enriched ubiquitin ligase substrate adaptor that preferentially binds high-mannose glycans on glycoproteins, was previously implicated in APP processing by facilitating the degradation of the APP-cleaving β-secretase, β-site APP-cleaving enzyme. Here, we sought to determine whether Fbxo2 plays a similar role for other glycoproteins in the amyloid processing pathway. We present in vitro and in vivo evidence that APP is itself a substrate for Fbxo2. APP levels were decreased in the presence of Fbxo2 in non-neuronal cells, and increased in both cultured hippocampal neurons and brain tissue from Fbxo2 knock-out mice. The processing of APP into its cleavage products was also increased in hippocampi and cultured hippocampal neurons lacking Fbxo2. In hippocampal slices, this increase in cleavage products was accompanied by a significant reduction in APP at the cell surface. Taken together, these results suggest that Fbxo2 regulates APP levels and processing in the brain and may play a role in modulating AD pathogenesis.

Brain amyloid β protein and memory disruption in Alzheimer’s disease

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Weiming Xia

2010-09-01

Full Text Available Weiming XiaCenter for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USAAbstract: The development of amyloid-containing neuritic plaques is an invariable characteristic of Alzheimer’s diseases (AD. The conversion from monomeric amyloid β protein (Aβ to oligomeric Aβ and finally neuritic plaques is highly dynamic. The specific Aß species that is correlated with disease severity remains to be discovered. Oligomeric Aβ has been detected in cultured cells, rodent and human brains, as well as human cerebrospinal fluid. Synthetic, cell, and brain derived Aβ oligomers have been found to inhibit hippocampal long-term potentiation (LTP and this effect can be suppressed by the blockage of Aβ oligomer formation. A large body of evidence suggests that Aβ oligomers inhibit N-methyl-D-aspartate receptor dependent LTP; additional receptors have also been found to elicit downstream pathways upon binding to Aβ oligomers. Amyloid antibodies and small molecular compounds that reduce brain Aβ levels and block Aβ oligomer formation are capable of reversing synaptic dysfunction and these approaches hold a promising therapeutic potential to rescue memory disruption.Keywords: Alzheimer, amyloid, oligomer, long-term potentiation, NMDA

Imaging Amyloid Tissues Stained with Luminescent Conjugated Oligothiophenes by Hyperspectral Confocal Microscopy and Fluorescence Lifetime Imaging.

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Nyström, Sofie; Bäck, Marcus; Nilsson, K Peter R; Hammarström, Per

2017-10-20

Proteins that deposit as amyloid in tissues throughout the body can be the cause or consequence of a large number of diseases. Among these we find neurodegenerative diseases such as Alzheimer's and Parkinson's disease afflicting primarily the central nervous system, and systemic amyloidosis where serum amyloid A, transthyretin and IgG light chains deposit as amyloid in liver, carpal tunnel, spleen, kidney, heart, and other peripheral tissues. Amyloid has been known and studied for more than a century, often using amyloid specific dyes such as Congo red and Thioflavin T (ThT) or Thioflavin (ThS). In this paper, we present heptamer-formyl thiophene acetic acid (hFTAA) as an example of recently developed complements to these dyes called luminescent conjugated oligothiophenes (LCOs). hFTAA is easy to use and is compatible with co-staining in immunofluorescence or with other cellular markers. Extensive research has proven that hFTAA detects a wider range of disease associated protein aggregates than conventional amyloid dyes. In addition, hFTAA can also be applied for optical assignment of distinct aggregated morphotypes to allow studies of amyloid fibril polymorphism. While the imaging methodology applied is optional, we here demonstrate hyperspectral imaging (HIS), laser scanning confocal microscopy and fluorescence lifetime imaging (FLIM). These examples show some of the imaging techniques where LCOs can be used as tools to gain more detailed knowledge of the formation and structural properties of amyloids. An important limitation to the technique is, as for all conventional optical microscopy techniques, the requirement for microscopic size of aggregates to allow detection. Furthermore, the aggregate should comprise a repetitive β-sheet structure to allow for hFTAA binding. Excessive fixation and/or epitope exposure that modify the aggregate structure or conformation can render poor hFTAA binding and hence pose limitations to accurate imaging.

Preventive immunization of aged and juvenile non-human primates to beta-amyloid

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Kofler Julia

2012-05-01

Full Text Available Abstract Background Immunization against beta-amyloid (Aβ is a promising approach for the treatment of Alzheimer’s disease, but the optimal timing for the vaccination remains to be determined. Preventive immunization approaches may be more efficacious and associated with fewer side-effects; however, there is only limited information available from primate models about the effects of preclinical vaccination on brain amyloid composition and the neuroinflammatory milieu. Methods Ten non-human primates (NHP of advanced age (18–26 years and eight 2-year-old juvenile NHPs were immunized at 0, 2, 6, 10 and 14 weeks with aggregated Aβ42 admixed with monophosphoryl lipid A as adjuvant, and monitored for up to 6 months. Anti-Aβ antibody levels and immune activation markers were assessed in plasma and cerebrospinal fluid samples before and at several time-points after immunization. Microglial activity was determined by [11C]PK11195 PET scans acquired before and after immunization, and by post-mortem immunohistochemical and real-time PCR evaluation. Aβ oligomer composition was assessed by immunoblot analysis in the frontal cortex of aged immunized and non-immunized control animals. Results All juvenile animals developed a strong and sustained serum anti-Aβ IgG antibody response, whereas only 80 % of aged animals developed detectable antibodies. The immune response in aged monkeys was more delayed and significantly weaker, and was also more variable between animals. Pre- and post-immunization [11C]PK11195 PET scans showed no evidence of vaccine-related microglial activation. Post-mortem brain tissue analysis indicated a low overall amyloid burden, but revealed a significant shift in oligomer size with an increase in the dimer:pentamer ratio in aged immunized animals compared with non-immunized controls (P  Conclusions Our results indicate that preventive Aβ immunization is a safe therapeutic approach lacking adverse CNS immune system

Localization and expression of substance P in transgenic mice overexpressing human APP751 with the London (V717I) and Swedish (K670M/N671L) mutations.

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Willis, Michael; Hutter-Paier, Birgit; Wietzorrek, Georg; Windisch, Manfred; Humpel, Christian; Knaus, Hans Günther; Marksteiner, Josef

2007-04-27

Substance P-like immunoreactivity (-LI) is found in neuritic plaques, and is reduced in patients suffering from Alzheimer disease (AD). In this study, we examined the distribution and expression of substance P in transgenic mice overexpressing human amyloid precursor protein (hAPP) APP751 with the London (V717I) and Swedish (K670M/N671L) mutations. Immunohistochemistry was performed to localize substance P- and glial fibrillary acidic protein-LI by confocal microscopy. In hAPP transgenic mice, the number of beta-amyloid plaques significantly increased from 6 to 12 months. About 5% of beta-amyloid plaques were substance P-immunoreactive. In transgenic mice, the morphology of substance P-immunoreactive structures changed by consisting of swollen and dystrophic neurites mostly associated with beta-amyloid plaques. The overall localization and the relative substance P densities were not different between wild type and transgenic mice at 6 and 12 months. At month 12, a dramatic change in the distribution pattern of substance P-LI was observed as it was now expressed in a high number of reactive astrocytes. This expression of substance P in astrocytes was mainly found in the hippocampal formation and thalamic nuclei with a preferential association with beta-amyloid plaques, whereas in cortical regions only faintly substance P-immunoreactive astrocytes were observed. This study indicates that substance P undergoes complex changes in this animal Alzheimer disease model. Future experiments including substance P antagonists are necessary to further explore the interaction between beta-amyloid deposits and substance P.

Viewing ageing eyes: diverse sites of amyloid Beta accumulation in the ageing mouse retina and the up-regulation of macrophages.

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Jaimie Hoh Kam

Full Text Available BACKGROUND: Amyloid beta (Aβ accumulates in the ageing central nervous system and is associated with a number of age-related diseases, including age-related macular degeneration (AMD in the eye. AMD is characterised by accumulation of extracellular deposits called drusen in which Aβ is a key constituent. Aβ activates the complement cascade and its deposition is associated with activated macrophages. So far, little is known about the quantitative measurements of Aβ accumulation and definitions of its relative sites of ocular deposition in the normal ageing mouse. METHODOLOGY/PRINCIPAL FINDINGS: We have traced Aβ accumulation quantitatively in the ageing mouse retina using immunohistochemistry and Western blot analysis. We reveal that it is not only deposited at Bruch's membrane and along blood vessels, but unexpectedly, it also coats photoreceptor outer segments. While Aβ is present at all sites of deposition from 3 months of age, it increases markedly from 6 months onward. Progressive accumulation of deposits on outer segments was confirmed with scanning electron microscopy, revealing age-related changes in their morphology. Such progress of accumulation of Aβ on photoreceptor outer segments with age was also confirmed in human retinae using immunohistochemistry. We also chart the macrophage response to increases in Aβ showing up-regulation in their numbers using both confocal laser imaging of the eye in vivo followed by in vitro immunostaining. With age macrophages become bloated with cellular debris including Aβ, however, their increasing numbers fail to stop Aβ accumulation. CONCLUSIONS: Increasing Aβ deposition in blood vessels and Bruch's membrane will impact upon retinal perfusion and clearance of cellular waste products from the outer retina, a region of very high metabolic activity. This accumulation of Aβ may contribute to the 30% reduction of photoreceptors found throughout life and the shortening of those that remain. The

Functional Amyloids in Reproduction.

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Hewetson, Aveline; Do, Hoa Quynh; Myers, Caitlyn; Muthusubramanian, Archana; Sutton, Roger Bryan; Wylie, Benjamin J; Cornwall, Gail A

2017-06-29

Amyloids are traditionally considered pathological protein aggregates that play causative roles in neurodegenerative disease, diabetes and prionopathies. However, increasing evidence indicates that in many biological systems nonpathological amyloids are formed for functional purposes. In this review, we will specifically describe amyloids that carry out biological roles in sexual reproduction including the processes of gametogenesis, germline specification, sperm maturation and fertilization. Several of these functional amyloids are evolutionarily conserved across several taxa, including human, emphasizing the critical role amyloids perform in reproduction. Evidence will also be presented suggesting that, if altered, some functional amyloids may become pathological.

The contrasting effect of macromolecular crowding on amyloid fibril formation.

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Qian Ma

Full Text Available Amyloid fibrils associated with neurodegenerative diseases can be considered biologically relevant failures of cellular quality control mechanisms. It is known that in vivo human Tau protein, human prion protein, and human copper, zinc superoxide dismutase (SOD1 have the tendency to form fibril deposits in a variety of tissues and they are associated with different neurodegenerative diseases, while rabbit prion protein and hen egg white lysozyme do not readily form fibrils and are unlikely to cause neurodegenerative diseases. In this study, we have investigated the contrasting effect of macromolecular crowding on fibril formation of different proteins.As revealed by assays based on thioflavin T binding and turbidity, human Tau fragments, when phosphorylated by glycogen synthase kinase-3β, do not form filaments in the absence of a crowding agent but do form fibrils in the presence of a crowding agent, and the presence of a strong crowding agent dramatically promotes amyloid fibril formation of human prion protein and its two pathogenic mutants E196K and D178N. Such an enhancing effect of macromolecular crowding on fibril formation is also observed for a pathological human SOD1 mutant A4V. On the other hand, rabbit prion protein and hen lysozyme do not form amyloid fibrils when a crowding agent at 300 g/l is used but do form fibrils in the absence of a crowding agent. Furthermore, aggregation of these two proteins is remarkably inhibited by Ficoll 70 and dextran 70 at 200 g/l.We suggest that proteins associated with neurodegenerative diseases are more likely to form amyloid fibrils under crowded conditions than in dilute solutions. By contrast, some of the proteins that are not neurodegenerative disease-associated are unlikely to misfold in crowded physiological environments. A possible explanation for the contrasting effect of macromolecular crowding on these two sets of proteins (amyloidogenic proteins and non-amyloidogenic proteins has been

A kinetic model for beta-amyloid adsorption at the air/solution interface and its implication to the beta-amyloid aggregation process.

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Jiang, Dianlu; Dinh, Kim Lien; Ruthenburg, Travis C; Zhang, Yi; Su, Lei; Land, Donald P; Zhou, Feimeng

2009-03-12

At the air/buffer solution interface the kinetics of adsorption of amyloid beta peptide, Abeta(1-42), whose bulk concentration (submicromolar) is more than 2 orders of magnitude lower than that typically used in other in vitro aggregation studies, has been studied using a Langmuir-Blodgett trough. The pressure-time curves exhibit a lag phase, wherein the surface pressure essentially remains at zero, and a rising phase, corresponding to the Abeta adsorption at the interface. The duration of the lag phase was found to be highly dependent on both the Abeta bulk concentration and the solution temperature. A large activation energy (62.2 +/- 4.1 KJ/mol) was determined and the apparent adsorption rate constant was found to be linearly dependent on the Abeta bulk concentration. Attenuated total reflection-IR spectra of the adsorbed Abeta transferred to a solid substrate and circular dichroism measurements of Abeta in the solution layer near the interface reveal that the natively unstructured Abeta in the bulk undergo a conformation change (folding) to mainly the alpha-helical structure. The results suggest that, prior to the adsorption step, an equilibrium between Abeta conformations is established within the subsurface. The kinetic equation derived from this model confirms that the overall Abeta adsorption is kinetically controlled and the apparent rate constant is proportional to the Abeta bulk concentration. This model also indicates that interfaces such as cell membranes and lipid bilayers may facilitate Abeta aggregation/ fibrillation by providing a thin hydrophobic layer adjacent to the interface for the initial A/beta conformation change (misfolding) and accumulation. Such a preconcentration effect offers a plausible explanation of the fact that Abeta fibrillation occurs in vivo at nanomolar concentrations. Another important biological implication from our work is that Abeta misfolding may occur before its adsorption onto a cell membrane. This general kinetic model

Amyloid and tau cerebrospinal fluid biomarkers in HIV infection

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Rosengren Lars

2009-12-01

Full Text Available Abstract Background Because of the emerging intersections of HIV infection and Alzheimer's disease, we examined cerebrospinal fluid (CSF biomarkers related of amyloid and tau metabolism in HIV-infected patients. Methods In this cross-sectional study we measured soluble amyloid precursor proteins alpha and beta (sAPPα and sAPPβ, amyloid beta fragment 1-42 (Aβ1-42, and total and hyperphosphorylated tau (t-tau and p-tau in CSF of 86 HIV-infected (HIV+ subjects, including 21 with AIDS dementia complex (ADC, 25 with central nervous system (CNS opportunistic infections and 40 without neurological symptoms and signs. We also measured these CSF biomarkers in 64 uninfected (HIV- subjects, including 21 with Alzheimer's disease, and both younger and older controls without neurological disease. Results CSF sAPPα and sAPPβ concentrations were highly correlated and reduced in patients with ADC and opportunistic infections compared to the other groups. The opportunistic infection group but not the ADC patients had lower CSF Aβ1-42 in comparison to the other HIV+ subjects. CSF t-tau levels were high in some ADC patients, but did not differ significantly from the HIV+ neuroasymptomatic group, while CSF p-tau was not increased in any of the HIV+ groups. Together, CSF amyloid and tau markers segregated the ADC patients from both HIV+ and HIV- neuroasymptomatics and from Alzheimer's disease patients, but not from those with opportunistic infections. Conclusions Parallel reductions of CSF sAPPα and sAPPβ in ADC and CNS opportunistic infections suggest an effect of CNS immune activation or inflammation on neuronal amyloid synthesis or processing. Elevation of CSF t-tau in some ADC and CNS infection patients without concomitant increase in p-tau indicates neural injury without preferential accumulation of hyperphosphorylated tau as found in Alzheimer's disease. These biomarker changes define pathogenetic pathways to brain injury in ADC that differ from those

Spatial patterns of atrophy, hypometabolism, and amyloid deposition in Alzheimer's disease correspond to dissociable functional brain networks.

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Grothe, Michel J; Teipel, Stefan J

2016-01-01

Recent neuroimaging studies of Alzheimer's disease (AD) have emphasized topographical similarities between AD-related brain changes and a prominent cortical association network called the default-mode network (DMN). However, the specificity of distinct imaging abnormalities for the DMN compared to other intrinsic connectivity networks (ICNs) of the limbic and heteromodal association cortex has not yet been examined systematically. We assessed regional amyloid load using AV45-PET, neuronal metabolism using FDG-PET, and gray matter volume using structural MRI in 473 participants from the Alzheimer's Disease Neuroimaging Initiative, including preclinical, predementia, and clinically manifest AD stages. Complementary region-of-interest and voxel-based analyses were used to assess disease stage- and modality-specific changes within seven principle ICNs of the human brain as defined by a standardized functional connectivity atlas. Amyloid deposition in AD dementia showed a preference for the DMN, but high effect sizes were also observed for other neocortical ICNs, most notably the frontoparietal-control network. Atrophic changes were most specific for an anterior limbic network, followed by the DMN, whereas other neocortical networks were relatively spared. Hypometabolism appeared to be a mixture of both amyloid- and atrophy-related profiles. Similar patterns of modality-dependent network specificity were also observed in the predementia and, for amyloid deposition, in the preclinical stage. These quantitative data confirm a high vulnerability of the DMN for multimodal imaging abnormalities in AD. However, rather than being selective for the DMN, imaging abnormalities more generally affect higher order cognitive networks and, importantly, the vulnerability profiles of these networks markedly differ for distinct aspects of AD pathology. © 2015 Wiley Periodicals, Inc.

A semi-automated motion-tracking analysis of locomotion speed in the C. elegans transgenics overexpressing beta-amyloid in neurons

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Kevin eMachino

2014-07-01

Full Text Available Multi-Worm Tracker (MWT is a real-time computer vision system that can simultaneously quantify motional patterns of multiple worms. MWT provides several behavioral parameters, including analysis of accurate real-time locomotion speed in the nematode, Caenorhabditis elegans. Here, we determined locomotion speed of the Alzheimer’s disease (AD transgenic strain that over-expresses human beta-amyloid1-42 (Aβ in the neurons. The MWT analysis showed that the AD strain logged a slower average speed than the wild type worms. The results may be consistent with the observation that the AD patients with dementia tend to show deficits in physical activities, including frequent falls. The AD strain showed reduced ability of the eggs to hatch and slowed hatching of the eggs. Thus, over-expression of Aβ in neurons causes negative effects on locomotion and hatchability. This study sheds light on new examples of detrimental effects that Aβ deposits can exhibit using C. elegans as a model system. The information gathered from this study indicates that the motion tracking analysis is a cost-effective, efficient way to assess the deficits of Aβ over-expression in the C. elegans system.

Peptide p5 binds both heparinase-sensitive glycosaminoglycans and fibrils in patient-derived AL amyloid extracts

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Martin, Emily B.; Williams, Angela [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Heidel, Eric [Department of Surgery, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Macy, Sallie [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Kennel, Stephen J. [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Department of Radiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Wall, Jonathan S., E-mail: jwall@utmck.edu [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Department of Radiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States)

2013-06-21

Highlights: •Polybasic peptide p5 binds human light chain amyloid extracts. •The binding of p5 with amyloid involves both glycosaminoglycans and fibrils. •Heparinase treatment led to a correlation between p5 binding and fibril content. •p5 binding to AL amyloid requires electrostatic interactions. -- Abstract: In previously published work, we have described heparin-binding synthetic peptides that preferentially recognize amyloid deposits in a mouse model of reactive systemic (AA) amyloidosis and can be imaged by using positron and single photon emission tomographic imaging. We wanted to extend these findings to the most common form of visceral amyloidosis, namely light chain (AL); however, there are no robust experimental animal models of AL amyloidosis. To further define the binding of the lead peptide, p5, to AL amyloid, we characterized the reactivity in vitro of p5 with in situ and patient-derived AL amyloid extracts which contain both hypersulfated heparan sulfate proteoglycans as well as amyloid fibrils. Histochemical staining demonstrated that the peptide specifically localized with tissue-associated AL amyloid deposits. Although we anticipated that p5 would undergo electrostatic interactions with the amyloid-associated glycosaminoglycans expressing heparin-like side chains, no significant correlation between peptide binding and glycosaminoglycan content within amyloid extracts was observed. In contrast, following heparinase I treatment, although overall binding was reduced, a positive correlation between peptide binding and amyloid fibril content became evident. This interaction was further confirmed using synthetic light chain fibrils that contain no carbohydrates. These data suggest that p5 can bind to both the sulfated glycosaminoglycans and protein fibril components of AL amyloid. Understanding these complex electrostatic interactions will aid in the optimization of synthetic peptides for use as amyloid imaging agents and potentially as

Protective effects of components of the Chinese herb grassleaf sweetflag rhizome on PC12 cells incubated with amyloid-beta42

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Zi-hao Liang

2015-01-01

Full Text Available The major ingredients of grassleaf sweetflag rhizome are β-asarone and eugenol, which can cross the blood-brain barrier and protect neurons. This study aimed to observe the neuroprotective effects and mechanisms of β-asarone and eugenol, components of the Chinese herb grassleaf sweetflag rhizome, on PC12 cells. First, PC12 cells were cultured with different concentrations (between 1 × 10 -10 M and 1 × 10 -5 M of β-asarone and eugenol. Survival rates of PC12 cells were not significantly affected. Second, PC12 cells incubated with amyloid-beta42, which reduced cell survival, were cultured under the same conditions (1 × 10 -6 M β-asarone and eugenol. The survival rates of PC12 cells significantly increased, while expression levels of the mRNAs for the pro-apoptotic protein Bax decreased, and those for the anti-apoptotic protein Bcl mRNA increased. In addition, the combination of β-asarone with eugenol achieved better results than either component alone. Our experimental findings indicate that both β-asarone and eugenol protect PC12 cells through inhibiting apoptosis, and that the combination of the two is better than either alone.

Cellular and substrate adhesion molecules (integrins) and their ligands in cerebral amyloid plaques in Alzheimer's disease

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Eikelenboom, P.; Zhan, S. S.; Kamphorst, W.; van der Valk, P.; Rozemuller, J. M.

1994-01-01

Integrins belonging to different subfamilies can be identified immunohistochemically in cerebral amyloid plaques. Monoclonal antibodies against the VLA family beta 1-integrins show staining of the corona of classical amyloid plaques for beta 1, alpha 3 and alpha 6. Immunostaining reveal also the

Fluorescence Microspectroscopy for Testing the Dimerization Hypothesis of BACE1 Protein in Cultured HEK293 Cells

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Gardeen, Spencer; Johnson, Joseph L.; Heikal, Ahmed A.

2016-06-01

Alzheimer's Disease (AD) is a neurodegenerative disorder that results from the formation of beta-amyloid plaques in the brain that trigger the known symptoms of memory loss in AD patients. The beta-amyloid plaques are formed by the proteolytic cleavage of the amyloid precursor protein (APP) by the proteases BACE1 and gamma-secretase. These enzyme-facilitated cleavages lead to the production of beta-amyloid fragments that aggregate to form plaques, which ultimately lead to neuronal cell death. Recent detergent protein extraction studies suggest that BACE1 protein forms a dimer that has significantly higher catalytic activity than its monomeric counterpart. In this contribution, we examine the dimerization hypothesis of BACE1 in cultured HEK293 cells using complementary fluorescence spectroscopy and microscopy methods. Cells were transfected with a BACE1-EGFP fusion protein construct and imaged using confocal, and differential interference contrast to monitor the localization and distribution of intracellular BACE1. Complementary fluorescence lifetime and anisotropy measurements enabled us to examine the conformational and environmental changes of BACE1 as a function of substrate binding. Using fluorescence correlation spectroscopy, we also quantified the diffusion coefficient of BACE1-EGFP on the plasma membrane as a means to test the dimerization hypothesis as a fucntion of substrate-analog inhibitition. Our results represent an important first towards examining the substrate-mediated dimerization hypothesis of BACE1 in live cells.

Altered β-Amyloid Precursor Protein Isoforms in Mexican Alzheimer’s Disease Patients

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V. J. Sánchez-González

2006-01-01

Full Text Available Objective: To determine the β-amyloid precursor protein (βAPP isoforms ratio as a risk factor for Alzheimer’s Disease and to assess its relationship with demographic and genetic variables of the disease.

Distribution of precursor amyloid-β-protein messenger RNA in human cerebral cortex: relationship to neurofibrillary tangles and neuritic plaques

International Nuclear Information System (INIS)

Lewis, D.A.; Higgins, G.A.; Young, W.G.; Goldgaber, D.; Gajdusek, D.C.; Wilson, M.C.; Morrison, J.H.

1988-01-01

Neurofibrillary tangles (NFT) and neuritic plaques (NP), two neuropathological markers of Alzheimer disease, may both contain peptide fragments derived from the human amyloid β protein. However, the nature of the relationship between NFT and NP and the source of the amyloid β proteins found in each have remained unclear. The authors used in situ hybridization techniques to map the anatomical distribution of precursor amyloid-β-protein mRNA in the neocortex of brains from three subjects with no known neurologic disease and from five patients with Alzheimer disease. In brains from control subjects, positively hybridizing neurons were present in cortical regions and layers that contain a high density of neuropathological markers in Alzheimer disease, as well as in those loci that contain NP but few NFT. Quantitative analyses of in situ hybridization patterns within layers III and V of the superior frontal cortex revealed that the presence of high numbers of NFT in Alzheimer-diseased brains was associated with a decrease in the number of positively hybridizing neurons compared to controls and Alzheimer-diseased brains with few NFT. These findings suggest that the expression of precursor amyloid-β-protein mRNA may be a necessary but is clearly not a sufficient prerequisite for NFT formation. In addition, these results may indicate that the amyloid β protein, present in NP in a given region or layer of cortex, is not derived from the resident neuronal cell bodies that express the mRNA for the precursor protein

Fibril specific, conformation dependent antibodies recognize a generic epitope common to amyloid fibrils and fibrillar oligomers that is absent in prefibrillar oligomers

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Rasool Suhail

2007-09-01

Full Text Available Abstract Background Amyloid-related degenerative diseases are associated with the accumulation of misfolded proteins as amyloid fibrils in tissue. In Alzheimer disease (AD, amyloid accumulates in several distinct types of insoluble plaque deposits, intracellular Aβ and as soluble oligomers and the relationships between these deposits and their pathological significance remains unclear. Conformation dependent antibodies have been reported that specifically recognize distinct assembly states of amyloids, including prefibrillar oligomers and fibrils. Results We immunized rabbits with a morphologically homogeneous population of Aβ42 fibrils. The resulting immune serum (OC specifically recognizes fibrils, but not random coil monomer or prefibrillar oligomers, indicating fibrils display a distinct conformation dependent epitope that is absent in prefibrillar oligomers. The fibril epitope is also displayed by fibrils of other types of amyloids, indicating that the epitope is a generic feature of the polypeptide backbone. The fibril specific antibody also recognizes 100,000 × G soluble fibrillar oligomers ranging in size from dimer to greater than 250 kDa on western blots. The fibrillar oligomers recognized by OC are immunologically distinct from prefibrillar oligomers recognized by A11, even though their sizes overlap broadly, indicating that size is not a reliable indicator of oligomer conformation. The immune response to prefibrillar oligomers and fibrils is not sequence specific and antisera of the same specificity are produced in response to immunization with islet amyloid polypeptide prefibrillar oligomer mimics and fibrils. The fibril specific antibodies stain all types of amyloid deposits in human AD brain. Diffuse amyloid deposits stain intensely with anti-fibril antibody although they are thioflavin S negative, suggesting that they are indeed fibrillar in conformation. OC also stains islet amyloid deposits in transgenic mouse models of type

Lost region in amyloid precursor protein (APP) through TALEN-mediated genome editing alters mitochondrial morphology.

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Wang, Yajie; Wu, Fengyi; Pan, Haining; Zheng, Wenzhong; Feng, Chi; Wang, Yunfu; Deng, Zixin; Wang, Lianrong; Luo, Jie; Chen, Shi

2016-02-29

Alzheimer's disease (AD) is characterized by amyloid-β (Aβ) deposition in the brain. Aβ plaques are produced through sequential β/γ cleavage of amyloid precursor protein (APP), of which there are three main APP isoforms: APP695, APP751 and APP770. KPI-APPs (APP751 and APP770) are known to be elevated in AD, but the reason remains unclear. Transcription activator-like (TAL) effector nucleases (TALENs) induce mutations with high efficiency at specific genomic loci, and it is thus possible to knock out specific regions using TALENs. In this study, we designed and expressed TALENs specific for the C-terminus of APP in HeLa cells, in which KPI-APPs are predominantly expressed. The KPI-APP mutants lack a 12-aa region that encompasses a 5-aa trans-membrane (TM) region and 7-aa juxta-membrane (JM) region. The mutated KPI-APPs exhibited decreased mitochondrial localization. In addition, mitochondrial morphology was altered, resulting in an increase in spherical mitochondria in the mutant cells through the disruption of the balance between fission and fusion. Mitochondrial dysfunction, including decreased ATP levels, disrupted mitochondrial membrane potential, increased ROS generation and impaired mitochondrial dehydrogenase activity, was also found. These results suggest that specific regions of KPI-APPs are important for mitochondrial localization and function.

Kinetics of selective deposition of Apo SAA2 during development of amyloidosis in mice

International Nuclear Information System (INIS)

Meek, R.L.; Benditt, E.P.; Hoffman, J.S.

1986-01-01

The major murine serum amyloid proteins (apoSAA 1 , apoSAA 2 ) have been identified, of which only one (apoSAA 2 ) shares amino acid sequence identity with tissue protein AA. To examine the mechanism of this apparent isotypespecific amyloid protein deposition, we have studied apoSAA metabolism at the levels of gene expression and plasma content during amyloidogenesis. In CBA mice, daily intraperitoneal casein administration resulted in a linear increase in splenic amyloid content, beginning within 10 days and reaching approximately 30% of the organ volume at 20 days. Hepatic apoSAA mRNA content, estimated by in vitro translation, was highest at day 1 (3% of total mRNA) and declined thereafter (to 1%, day 20). The relative content of apoSAA 2 mRNA compared with that of apoSAA 1 was unchanged throughout amyloid induction. Simultaneously, a 2-3 fold drop in total serum apoSAA levels was observed with, by contrast, a 10-fold reduction in the serum ratio of apoSAA 2 /apoSAA 1 . These results are consistent with the hypothesis that murine tissue protein AA accumulates by selective deposition of apoSAA 2 from the serum

Imaging of amyloid deposition in human brain using positron emission tomography and [18F]FACT: comparison with [11C]PIB.

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Ito, Hiroshi; Shinotoh, Hitoshi; Shimada, Hitoshi; Miyoshi, Michie; Yanai, Kazuhiko; Okamura, Nobuyuki; Takano, Harumasa; Takahashi, Hidehiko; Arakawa, Ryosuke; Kodaka, Fumitoshi; Ono, Maiko; Eguchi, Yoko; Higuchi, Makoto; Fukumura, Toshimitsu; Suhara, Tetsuya

2014-04-01

The characteristic neuropathological changes in Alzheimer's disease (AD) are deposition of amyloid senile plaques and neurofibrillary tangles. The (18)F-labeled amyloid tracer, [(18)F]2-[(2-{(E)-2-[2-(dimethylamino)-1,3-thiazol-5-yl]vinyl}-1,3-benzoxazol-6-yl)oxy]-3-fluoropropan-1-ol (FACT), one of the benzoxazole derivatives, was recently developed. In the present study, deposition of amyloid senile plaques was measured by positron emission tomography (PET) with both [(11)C]Pittsburgh compound B (PIB) and [(18)F]FACT in the same subjects, and the regional uptakes of both radiotracers were directly compared. Two PET scans, one of each with [(11)C]PIB and [(18)F]FACT, were performed sequentially on six normal control subjects, two mild cognitive impairment (MCI) patients, and six AD patients. The standardized uptake value ratio of brain regions to the cerebellum was calculated with partial volume correction using magnetic resonance (MR) images to remove the effects of white matter accumulation. No significant differences in the cerebral cortical uptake were observed between normal control subjects and AD patients in [(18)F]FACT studies without partial volume correction, while significant differences were observed in [(11)C]PIB. After partial volume correction, the cerebral cortical uptake was significantly larger in AD patients than in normal control subjects for [(18)F]FACT studies as well as [(11)C]PIB. Relatively lower uptakes of [(11)C]PIB in distribution were observed in the medial side of the temporal cortex and in the occipital cortex as compared with [(18)F]FACT. Relatively higher uptake of [(11)C]PIB in distribution was observed in the frontal and parietal cortices. Since [(18)F]FACT might bind more preferentially to dense-cored amyloid deposition, regional differences in cerebral cortical uptake between [(11)C]PIB and [(18)F]FACT might be due to differences in regional distribution between diffuse and dense-cored amyloid plaque shown in the

Imaging of amyloid deposition in human brain using positron emission tomography and [18F]FACT: comparison with [11C]PIB