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Conformation-specific antibodies to target amyloid ? oligomers and their application to immunotherapy for Alzheimer's disease.
Biosci. Biotechnol. Biochem.
PUBLISHED: 08-19-2014
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Amyloid ?-protein (A?) oligomers, intermediates of A? aggregation, cause cognitive impairment and synaptotoxicity in the pathogenesis of Alzheimer's disease (AD). Immunotherapy using anti-A? antibody is one of the most promising approaches for AD treatment. However, most clinical trials using conventional sequence-specific antibodies have proceeded with difficulty. This is probably due to the unintended removal of the non-pathological monomer and fibrils of A? as well as the pathological oligomers by these antibodies that recognize A? sequence, which is not involved in synaptotoxicity. Several efforts have been made recently to develop conformation-specific antibodies that target the tertiary structure of A? oligomers. Here, we review the recent findings of A? oligomers and anti-A? antibodies including our own, and discuss their potential as therapeutic and diagnostic tools.
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Altered regulation of sleep and feeding contributes to starvation resistance in Drosophila melanogaster.
J. Exp. Biol.
PUBLISHED: 06-19-2014
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Animals respond to changes in food availability by adjusting sleep and foraging strategies to optimize their fitness. Wild populations of the fruit fly, Drosophila melanogaster, display highly variable levels of starvation resistance that are dependent on geographic location, food availability and evolutionary history. How behaviors that include sleep and feeding vary in Drosophila with increased starvation resistance is unclear. We have generated starvation-resistant flies through experimental evolution to investigate the relationship between foraging behaviors and starvation resistance. Outbred populations of D. melanogaster were selected for starvation resistance over 60 generations. This selection process resulted in flies with a threefold increase in total lipids that survive up to 18 days without food. We tested starvation-selected (S) flies for sleep and feeding behaviors to determine the effect that selection for starvation resistance has had on foraging behavior. Flies from three replicated starvation-selected populations displayed a dramatic reduction in feeding and prolonged sleep duration compared to fed control (F) populations, suggesting that modified sleep and feeding may contribute to starvation resistance. A prolonged larval developmental period contributes to the elevated energy stores present in starvation-selected flies. By preventing S larvae from feeding longer than F larvae, we were able to reduce energy stores in adult S flies to the levels seen in adult F flies, thus allowing us to control for energy storage levels. However, the reduction of energy stores in S flies fails to generate normal sleep and feeding behavior seen in F flies with similar energy stores. These findings suggest that the behavioral changes observed in S flies are due to genetic regulation of behavior rather than elevated lipid levels. Testing S-F hybrid individuals for both feeding and sleep revealed a lack of correlation between food consumption and sleep duration, indicating further independence in genetic factors underlying the sleep and feeding changes observed in S flies. Taken together, these findings provide evidence that starvation selection results in prolonged sleep and reduced feeding through a mechanism that is independent of elevated energy stores. These findings suggest that changes in both metabolic function and behavior contribute to the increase in starvation resistance seen in flies selected for starvation resistance.
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Development: better sleep on it, children.
Curr. Biol.
PUBLISHED: 06-18-2014
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A new study has identified a neural circuit that is responsible for increasing sleep in young fruit flies. Reduced dopamine signaling to the fan-shaped body during early life promotes sleep and is critical for proper brain development.
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Intracellular accumulation of toxic turn amyloid-? is associated with endoplasmic reticulum stress in Alzheimers disease.
Curr Alzheimer Res
PUBLISHED: 08-22-2013
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Amyloid-? protein (A?) accumulates in the neurons of Alzheimers disease (AD) patients at an early stage of the disease. Recently, we found that A? with a toxic turn at positions 22 and 23 accumulates in neurons in AD brain. Here, we studied the accumulation of A?, toxic turn A? and high-molecular-weight A? oligomers in presenilin 1 (PS1) gene-transfected SH-SY5Y cells as well as in the brains of 3xTg-AD mice and AD patients. Immunostaining revealed that accumulation of toxic turn A? was promoted in G384A- and I143T-mutant PS1-transfected cells and further enhanced by co-transfection of cells with the A?-precursor protein (A?PP) gene. In contrast, accumulation of high-molecular-weight A? oligomers was promoted in mutant PS1 cells but attenuated by co-transfection of cells with the A?PP gene. Toxic turn A? was detected in the neurons of 3xTg-AD mice aged 2 months, when the mice were cognitively unimpaired. In contrast, high-molecular-weight A? oligomers were detected in the neurons of 7-month-old mice, when memory dysfunction is apparent. Furthermore, immunostaining and western blotting for Rab4, Rab6 and GRP78 revealed increased levels of these proteins in mutant PS1 cells and their accumulation in the neurons of 3xTg-AD mice. Remarkably, GRP78 immunoreactivity was increased at 2 months of age. Double-label immunostaining of AD brain revealed an apparent association between toxic turn A? and GRP78, an endoplasmic reticulum (ER) stress marker. Intraneuronal accumulation of toxic turn A? may be associated with ER stress in the brains of AD model mice and AD patients at an early stage.
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Site-specific inhibitory mechanism for amyloid ?42 aggregation by catechol-type flavonoids targeting the Lys residues.
J. Biol. Chem.
PUBLISHED: 06-21-2013
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The aggregation of the 42-residue amyloid ?-protein (A?42) is involved in the pathogenesis of Alzheimer disease (AD). Numerous flavonoids exhibit inhibitory activity against A?42 aggregation, but their mechanism remains unclear in the molecular level. Here we propose the site-specific inhibitory mechanism of (+)-taxifolin, a catechol-type flavonoid, whose 3,4-dihydroxyl groups of the B-ring plays a critical role. Addition of sodium periodate, an oxidant, strengthened suppression of A?42 aggregation by (+)-taxifolin, whereas no inhibition was observed under anaerobic conditions, suggesting the inhibition to be associated with the oxidation to form o-quinone. Because formation of the A?42-taxifolin adduct was suggested by mass spectrometry, A?42 mutants substituted at Arg(5), Lys(16), and/or Lys(28) with norleucine (Nle) were prepared to identify the residues involved in the conjugate formation. (+)-Taxifolin did not suppress the aggregation of A?42 mutants at Lys(16) and/or Lys(28) except for the mutant at Arg(5). In addition, the aggregation of A?42 was inhibited by other catechol-type flavonoids, whereas that of K16Nle-A?42 was not. In contrast, some non-catechol-type flavonoids suppressed the aggregation of K16Nle-A?42 as well as A?42. Furthermore, interaction of (+)-taxifolin with the ?-sheet region in A?42 was not observed using solid-state NMR unlike curcumin of the non-catechol-type. These results demonstrate that catechol-type flavonoids could specifically suppress A?42 aggregation by targeting Lys residues. Although the anti-AD activity of flavonoids has been ascribed to their antioxidative activity, the mechanism that the o-quinone reacts with Lys residues of A?42 might be more intrinsic. The Lys residues could be targets for Alzheimer disease therapy.
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Inhibition of amyloid ? aggregation by acteoside, a phenylethanoid glycoside.
Biosci. Biotechnol. Biochem.
PUBLISHED: 06-07-2013
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We examined the effects of acteoside (1a), which was isolated from Orobanche minor, and its derivatives on the aggregation of a 42-mer amyloid ? protein (A?42) in our search for anti-amyloidogenic compounds for Alzheimers disease (AD) therapy. Acteoside (1a) strongly inhibited the aggregation of A?42 in a dose-dependent manner. The structure-activity relationship for acteoside (1a) and related compounds suggests the catechol moiety of phenylethanoid glycosides to be essential for this inhibitory activity.
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Non-toxic conformer of amyloid ? may suppress amyloid ?-induced toxicity in rat primary neurons: implications for a novel therapeutic strategy for Alzheimers disease.
Biochem. Biophys. Res. Commun.
PUBLISHED: 05-22-2013
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The 42-mer amyloid ?-protein (A?42) oligomers cause neurotoxicity and cognitive impairment in Alzheimers disease (AD). We previously identified the toxic conformer of A?42 with a turn at positions 22-23 ("toxic" turn) to form oligomers and to induce toxicity in rat primary neurons, along with the non-toxic conformer with a turn at positions 25-26. G25P-A?42 and E22V-A?42 are non-toxic mutants that disfavor the "toxic" turn. Here we hypothesize that these non-toxic mutants of A?42 could suppress A?42-induced neurotoxicity, and examined their effects on the neurotoxicity, aggregation, and levels of the toxic conformer, which was evaluated by dot blotting using a monoclonal antibody (11A1) against the toxic conformer. G25P-A?42 and E22V-A?42 suppressed the neurotoxicity and aggregation of A?42 as well as the formation of the toxic conformer. The neurotoxicity induced by A?42 was also significantly reduced by the treatment of 11A1, but not of A?-sequence specific antibodies (6E10 and 4G8). Since recent studies indicate that A? oligomers contain parallel ?-sheet, the present results suggest that the non-toxic mutants of A?42 without the "toxic" turn could prevent the propagation process of the toxic conformer of A?42 resulting in suppression of the formation of the toxic oligomers. This could be a promising strategy for AD therapeutics.
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Structure-activity relationship for (+)-taxifolin isolated from silymarin as an inhibitor of amyloid ? aggregation.
Biosci. Biotechnol. Biochem.
PUBLISHED: 05-07-2013
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Silymarin, the seed extract of Silybium marianum, has preventive effects against Alzheimers disease-like pathogenesis in vivo. We isolated (+)-taxifolin (4) from silymarin as an inhibitor of aggregation of the 42-residue amyloid ?-protein. Structure-activity relationship studies revealed the 3,4-dihydroxyl groups to be critical to the anti-aggregative ability, whereas the 7-hydroxyl group and the stereochemistry at positions 2 and 3 were not important.
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Structure-activity studies on the side chain of a simplified analog of aplysiatoxin (aplog-1) with anti-proliferative activity.
Bioorg. Med. Chem.
PUBLISHED: 01-30-2013
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We have recently developed a simplified analog of aplysiatoxin (aplog-1) as an activator of protein kinase C (PKC) with anti-proliferative activity like bryostain 1. To identify sites in aplog-1 that could be readily modified to optimize therapeutic performance and to develop a molecular probe for examining the analogs mode of action, substituent effects on the phenol ring were systematically examined. Whereas hydrophilic acetamido derivatives were less active than aplog-1 in inhibiting cancer cell growth and binding to PKC?, introduction of hydrophobic bromine and iodine atoms enhanced both biological activities. The anti-proliferative activity was found to correlate closely with molecular hydrophobicity, and maximal activity was observed at a logP value of 4.0-4.5. On the other hand, an induction test with Epstein-Barr virus early antigen demonstrated that these derivatives have less tumor-promoting activity in vitro than aplog-1 regardless of the hydrophobicity of their substituents. These results would facilitate rapid preparation of molecular probes to examine the mechanism of the unique biological activities of aplog-1.
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Modeling Alzheimers disease with iPSCs reveals stress phenotypes associated with intracellular A? and differential drug responsiveness.
Cell Stem Cell
PUBLISHED: 01-18-2013
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Oligomeric forms of amyloid-? peptide (A?) are thought to play a pivotal role in the pathogenesis of Alzheimers disease (AD), but the mechanism involved is still unclear. Here, we generated induced pluripotent stem cells (iPSCs) from familial and sporadic AD patients and differentiated them into neural cells. A? oligomers accumulated in iPSC-derived neurons and astrocytes in cells from patients with a familial amyloid precursor protein (APP)-E693? mutation and sporadic AD, leading to endoplasmic reticulum (ER) and oxidative stress. The accumulated A? oligomers were not proteolytically resistant, and docosahexaenoic acid (DHA) treatment alleviated the stress responses in the AD neural cells. Differential manifestation of ER stress and DHA responsiveness may help explain variable clinical results obtained with the use of DHA treatment and suggests that DHA may in fact be effective for a subset of patients. It also illustrates how patient-specific iPSCs can be useful for analyzing AD pathogenesis and evaluating drugs.
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Geranyl modification on the tryptophan residue of ComXRO-E-2 pheromone by a cell-free system.
FEBS Lett.
PUBLISHED: 11-28-2011
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ComX pheromone is an isoprenoidal oligopeptide containing a modified tryptophan residue, which stimulates natural genetic competence in the gram-positive bacterium Bacillus. Since posttranslational prenylation on the tryptophan residue has not been reported except in ComX pheromone, the universality of this modification has not yet been elucidated. In this paper, we established a cell-free system, whereby the tryptophan residue in peptides is modified with a geranyl group by modifying enzyme ComQ. In addition, we investigated enzymatic reaction conditions using an in vitro enzyme reaction system. This is the first report of in vitro geranylation on the tryptophan residue. This system is potentially a useful tool for elucidating the universality of prenylation on the tryptophan residue.
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SOD1 (copper/zinc superoxide dismutase) deficiency drives amyloid ? protein oligomerization and memory loss in mouse model of Alzheimer disease.
J. Biol. Chem.
PUBLISHED: 11-09-2011
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Oxidative stress is closely linked to the pathogenesis of neurodegeneration. Soluble amyloid ? (A?) oligomers cause cognitive impairment and synaptic dysfunction in Alzheimer disease (AD). However, the relationship between oligomers, oxidative stress, and their localization during disease progression is uncertain. Our previous study demonstrated that mice deficient in cytoplasmic copper/zinc superoxide dismutase (CuZn-SOD, SOD1) have features of drusen formation, a hallmark of age-related macular degeneration (Imamura, Y., Noda, S., Hashizume, K., Shinoda, K., Yamaguchi, M., Uchiyama, S., Shimizu, T., Mizushima, Y., Shirasawa, T., and Tsubota, K. (2006) Proc. Natl. Acad. Sci. U.S.A. 103, 11282-11287). Amyloid assembly has been implicated as a common mechanism of plaque and drusen formation. Here, we show that Sod1 deficiency in an amyloid precursor protein-overexpressing mouse model (AD mouse, Tg2576) accelerated A? oligomerization and memory impairment as compared with control AD mouse and that these phenomena were basically mediated by oxidative damage. The increased plaque and neuronal inflammation were accompanied by the generation of N(?)-carboxymethyl lysine in advanced glycation end products, a rapid marker of oxidative damage, induced by Sod1 gene-dependent reduction. The Sod1 deletion also caused Tau phosphorylation and the lower levels of synaptophysin. Furthermore, the levels of SOD1 were significantly decreased in human AD patients rather than non-AD age-matched individuals, but mitochondrial SOD (Mn-SOD, SOD2) and extracellular SOD (CuZn-SOD, SOD3) were not. These findings suggest that cytoplasmic superoxide radical plays a critical role in the pathogenesis of AD. Activation of Sod1 may be a therapeutic strategy for the inhibition of AD progression.
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Insulin receptor mutation results in insulin resistance and hyperinsulinemia but does not exacerbate Alzheimers-like phenotypes in mice.
Biochem. Biophys. Res. Commun.
PUBLISHED: 04-20-2011
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Obesity is a risk factor for Alzheimers disease (AD), which is characterized by amyloid ? depositions and cognitive dysfunction. Although insulin resistance is one of the phenotypes of obesity, its deleterious effects on AD progression remain to be fully elucidated. We previously reported that the suppression of insulin signaling in a mouse with a heterozygous mutation (P1195L) in the gene for the insulin receptor showed insulin resistance and hyperinsulinemia but did not develop diabetes mellitus [15]. Here, we generated a novel AD mouse model carrying the same insulin receptor mutation and showed that the combination of insulin resistance and hyperinsulinemia did not accelerate plaque formation or memory abnormalities in these mice. Interestingly, the insulin receptor mutation reduced oxidative damage in the brains of the AD mice. These findings suggest that insulin resistance is not always involved in the pathogenesis of AD.
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Formation of the 42-mer Amyloid ? Radical and the Therapeutic Role of Superoxide Dismutase in Alzheimers Disease.
J Amino Acids
PUBLISHED: 01-16-2011
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Oxidative stress is closely involved in age-related diseases and ageing itself. There is evidence of the leading contribution of oxidative damage to neurodegenerative disease, in contrast to other diseases where oxidative stress plays a secondary role. The 42-mer amyloid ? (A?42) peptide is thought to be a culprit in the pathogenesis of Alzheimers disease (AD). A?42 aggregates form the oligomeric assembly and show neurotoxicity, causing synaptic dysfunction. A?42 also induces tissue oxidation (DNA/RNA, proteins, and lipids) through trace metals (Cu, Zn, and Fe), which can be protected by antioxidant enzymes, vitamin C, and vitamin E. Superoxide dismutase catalyzes the conversion of toxic superoxide radical to less reactive hydrogen peroxide, contributing to protection from AD. Here we review the involvement of oxidative stress in AD progression induced from an imbalance between the radical formation of A?42 itself together with unique turn structure at positions Glu22 and Asp23 and several defense systems.
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Silymarin attenuated the amyloid ? plaque burden and improved behavioral abnormalities in an Alzheimers disease mouse model.
Biosci. Biotechnol. Biochem.
PUBLISHED: 11-07-2010
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Alzheimers disease (AD) is characterized by progressive cognitive impairment and the formation of senile plaques. Silymarin, an extract of milk thistle, has long been used as a medicinal herb for liver diseases. Here we report marked suppression of amyloid ?-protein (A?) fibril formation and neurotoxicity in PC12 cells after silymarin treatment in vitro. In vivo studies had indicated a significant reduction in brain A? deposition and improvement in behavioral abnormalities in amyloid precursor protein (APP) transgenic mice that had been preventively treated with a powdered diet containing 0.1% silymarin for 6 months. The silymarin-treated APP mice also showed less anxiety than the vehicle-treated APP mice. These behavioral changes were associated with a decline in A? oligomer production induced by silymarin intake. These results suggest that silymarin is a promising agent for the prevention of AD.
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Monoclonal antibody against the turn of the 42-residue amyloid ?-protein at positions 22 and 23.
ACS Chem Neurosci
PUBLISHED: 08-04-2010
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Aggregation of the 42-mer amyloid ?-protein (A?42) plays a critical role in the pathogenesis of Alzheimers disease (AD). We have proposed a toxic conformer with a turn at positions 22 and 23, as well as a nontoxic conformer with a turn at positions 25 and 26, in A?42 aggregates from systematic proline scanning and solid-state NMR studies. Although recent clinical trials of immunization targeting A?42 aggregates have proved useful, some adverse effects were reported. One of the reasons was hypothesized to be excessive immunoreactions derived from the unintended removal of nontoxic A?42, which plays an important role in the physiological function. To develop a monoclonal antibody for toxic A?42, E22P-A?10-35, a minimum moiety for neurotoxicity containing the turn at positions 22 and 23, was used for the generation of antibodies, following the selection of clones using A?42 mutants of E22P (turn-inducing) and E22V (turn-preventing). The obtained clone (11A1) showed a high binding affinity (K(D) = 10.3 nM) for A?42 using surface plasmon resonance. 11A1 also inhibited the neurotoxicity of A?42 in PC12 cells. Immunohistochemical studies showed that not only extracellular but intracellular amyloid was stained in human AD brains. In Western blotting analyses using human brains, low-molecular weight-oligomers rather than the monomer of A? were readily recognized by 11A1. These results imply that 11A1 could detect toxic A?42 oligomers with the turn at positions 22 and 23 and that 11A1 could be applicable for the therapeutic targeting of toxic A?42 in AD.
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The turn formation at positions 22 and 23 in the 42-mer amyloid beta peptide: the emerging role in the pathogenesis of Alzheimers disease.
Geriatr Gerontol Int
PUBLISHED: 07-02-2010
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One hallmark of Alzheimers disease (AD) is the accumulation of amyloid beta (Abeta) peptides in the brain; Abeta mainly consists of 42-mer and 40-mer peptides (Abeta42 and Abeta40). Abeta42 plays a more critical role in the pathogenesis of AD because Abeta42 aggregates much faster and is more toxic than Abeta40. Therefore, there is an urgent need to elucidate the mechanism of aggregation and neurotoxicity of Abeta42 to develop therapeutic agents. Here, we introduce the pathological role of Abeta42 in AD and review our recent findings of the structural analysis of Abeta42 using systematic proline replacement, electron spin resonance and solid-state nuclear magnetic resonance, and the new mechanism of neurotoxicity of Abeta42 through the formation of radicals.
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RNA aptamers generated against oligomeric Abeta40 recognize common amyloid aptatopes with low specificity but high sensitivity.
PLoS ONE
PUBLISHED: 07-28-2009
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Aptamers are useful molecular recognition tools in research, diagnostics, and therapy. Despite promising results in other fields, aptamer use has remained scarce in amyloid research, including Alzheimers disease (AD). AD is a progressive neurodegenerative disease believed to be caused by neurotoxic amyloid beta-protein (Abeta) oligomers. Abeta oligomers therefore are an attractive target for development of diagnostic and therapeutic reagents. We used covalently-stabilized oligomers of the 40-residue form of Abeta (Abeta40) for aptamer selection. Despite gradually increasing the stringency of selection conditions, the selected aptamers did not recognize Abeta40 oligomers but reacted with fibrils of Abeta40, Abeta42, and several other amyloidogenic proteins. Aptamer reactivity with amyloid fibrils showed some degree of protein-sequence dependency. Significant fibril binding also was found for the naïve library and could not be eliminated by counter-selection using Abeta40 fibrils, suggesting that aptamer binding to amyloid fibrils was RNA-sequence-independent. Aptamer binding depended on fibrillogenesis and showed a lag phase. Interestingly, aptamers detected fibril formation with > or =15-fold higher sensitivity than thioflavin T (ThT), revealing substantial beta-sheet and fibril formation undetected by ThT. The data suggest that under physiologic conditions, aptamers for oligomeric forms of amyloidogenic proteins cannot be selected due to high, non-specific affinity of oligonucleotides for amyloid fibrils. Nevertheless, the high sensitivity, whereby aptamers detect beta-sheet formation, suggests that they can serve as superior amyloid recognition tools.
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Skin atrophy in cytoplasmic SOD-deficient mice and its complete recovery using a vitamin C derivative.
Biochem. Biophys. Res. Commun.
PUBLISHED: 03-06-2009
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Intrinsic skin ageing is characterized by atrophy and loss of elasticity. Although the skin hypertrophy induced by photoageing has been studied, the molecular mechanisms of skin atrophy during ageing remain unclear. Here, we report that copper/zinc superoxide dismutase (CuZn-SOD)-deficient mice show atrophic morphology in their skin. This atrophy is accompanied by the degeneration of collagen and elastic fibers, and skin hydroxyproline is also significantly reduced in deficient mice. These imply that the dysfunction of collagen and elastin biosynthesis are involved in the progression of skin thinning. Furthermore, transdermal administration of a vitamin C derivative which can permeate through the membrane, completely reversed the skin thinning and deterioration of collagen and elastin in the mutant mice. These indicate that the vitamin C derivative is a powerful agent for alleviating skin ageing through regeneration of collagen and elastin. The CuZn-SOD-deficient mice might be applicable to evaluation of therapeutic medicines against skin ageing.
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[A causal analysis of the determinants of trust of the Forest Administration in the prefecture where the forest environmental tax was introduced].
Shinrigaku Kenkyu
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This paper examines the determinants, and interrelationships, of trust of the Forest Administration by using structural equation modeling with questionnaire data from 1 500 residents in six prefectures. The proposed model demonstrates that value similarity, ability and intention are determinants of the trust of the Forest Administration. There is a causal relationship of intention to value similarity. Furthermore, multiple group analysis in the structural equation modeling showed that the group with high interest in local forest problems showed a relatively large influence of intention and value similarity, compared to the low interest group, where intention and ability had a relatively large influence.
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Toxicity in rat primary neurons through the cellular oxidative stress induced by the turn formation at positions 22 and 23 of A?42.
ACS Chem Neurosci
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The 42-mer amyloid ?-protein (A?42) aggregates to form soluble oligomers that cause memory loss and synaptotoxicity in Alzheimers disease (AD). Oxidative stress is closely related to the pathogenesis of AD. We previously identified the toxic conformer of A?42 with a turn at positions 22 and 23 ("toxic turn") by solid-state NMR and demonstrated that a monoclonal antibody (11A1) against the toxic turn in A?42 mainly detected the oligomer in the brains of AD patients. Our recent study suggested that oxidative stress is a key factor of the oligomerization and cognitive impairment induced by A? overproduction in vivo. However, the involvement of the toxic conformer in A?42-induced oxidative damage remains unclear. To investigate this mechanism, we examined the levels of intracellular reactive oxygen species (ROS) and neurotoxicity in rat primary neurons using E22P-A?42, a mutant that induces a turn at positions 22 and 23, and E22V-A?42, a turn-preventing mutant. E22P-A?42, but not E22V-A?42, induced greater ROS production than Wt-A?42 in addition to potent neurotoxicity. Interestingly, the formation of the toxic conformer in both E22P-A?42 and Wt-A?42 probed by the 11A1 antibody preceded A?42-induced neurotoxicity. Trolox (a radical scavenger) and Congo red (an aggregation inhibitor) significantly prevented the neurotoxicity and intracellular ROS induced by E22P-A?42 and Wt-A?42, respectively. These results suggest that A?42-mediated toxicity is caused by the turn that favors toxic oligomers, which increase generation of ROS.
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Protective effects of caffeoylquinic acids on the aggregation and neurotoxicity of the 42-residue amyloid ?-protein.
Bioorg. Med. Chem.
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Alzheimers disease (AD), a neurodegenerative disorder, is characterized by aggregation of 42-mer amyloid ?-protein (A?42). A?42 aggregates through ?-sheet formation and induces cytotoxicity against neuronal cells. A?42 oligomer, an intermediate of the aggregates, causes memory loss and synaptotoxicity in AD. Inhibition of A?42 aggregation by small molecules is thus a promising strategy for the treatment of AD. Caffeoylquinic acid (CQA), a phenylpropanoid found widely in natural sources including foods, shows various biological activities such as anti-oxidative ability. Previously, our group reported that 3,5-di-O-caffeoylquinic acid (3,5-di-CQA) rescued the cognitive impairment in senescence-accelerated-prone mice 8. However, structure-activity relationship of CQA derivatives on the aggregation and neurotoxicity of A?42 remains elusive. To evaluate the anti-amyloidogenic property of CQA-related compounds for AD therapy, we examined the effect of CQA and its derivatives on the aggregation and neurotoxicity of A?42. In particular, 4,5-di-O-caffeoylquinic acid (4,5-di-CQA) and 3,4,5-tri-O-caffeoylquinic acid (3,4,5-tri-CQA) strongly inhibited the aggregation of A?42 in a dose-dependent manner. Structure-activity relationship studies suggested that the caffeoyl group in CQA is essential for the inhibitory activity. These CQAs also suppressed the transformation into ?-sheet and cytotoxicity against human neuroblastoma cells of A?42. Furthermore, 3,4,5-tri-CQA blocked the formation of A?42 oligomer. These results indicate that 3,4,5-tri-CQA could be a potential agent for the prevention of AD.
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Cytoplasmic superoxide radical: a possible contributing factor to intracellular A? oligomerization in Alzheimer disease.
Commun Integr Biol
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Soluble amyloid ? (A?) oligomers cause memory loss and synaptic dysfunction in Alzheimer disease (AD). Despite intensive studies on A? assembly in vitro and in vivo, the localization and cellular mechanism of A? oligomerization are not fully understood. Previously, we demonstrated that cytoplasmic superoxide radicals contribute to drusen deposition, a hallmark of age-related macular degeneration as well as other geriatric diseases (fatty liver, skin thinning, and osteoporosis). Using a transgenic mouse model of AD, we recently clarified the role of cytoplasmic oxidative stress in cognitive impairment and oligomer formation. Moreover, we also found that these phenomena were associated with neuroinflammation, tau phosphorylation, and synaptic loss. Notably, studies using human brains support the involvement of cytoplasmic superoxide radicals in AD pathology. In this addendum to Murakami et al. (JBC 2011), we discuss and comment on intracellular A? oligomer formation and the possible therapeutic effects of intracellular redox state modulators.
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Lack of the consensus sequence necessary for tryptophan prenylation in the ComX pheromone precursor.
Biosci. Biotechnol. Biochem.
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ComX, an oligopeptide pheromone that stimulates the natural genetic competence controlled by quorum sensing in Bacillus subtilis and related bacilli, contains a prenyl-modified tryptophan residue. Since ComX is the only protein known to contain prenylated tryptophan, the universality of this unique posttranslational modification has yet to be determined. Recently, we developed a cell-free assay system in which the tryptophan residue in the ComX(RO-E-2) pheromone precursor derived from B. subtilis strain RO-E-2 can be geranylated by the ComQ(RO-E-2) enzyme. We report here our attempt to identify the consensus sequence surrounding the geranylated tryptophan residue by using the cell-free system with various ComX(RO-E-2) pheromone precursor analogs. We found that [47-58]ComX(RO-E-2), corresponding to the C-terminal 12-residue peptide of the pheromone precursor, contained a short sequence essential for geranylation. We also found that the length of the sequence between the tryptophan residue and the C-terminus was important for geranylation, and that some [47-58]ComX(RO-E-2) pheromone precursor amino acids were involved in the geranylation reaction. However, we could not identify a consensus sequence surrounding the geranylated tryptophan. Our evidence suggests that, like Rab which lacks a consensus sequence yet is geranylgeranyl-modified on a cysteine residue, the ComX pheromone and its precursor also lack a consensus sequence.
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Stimulation of the amyloidogenic pathway by cytoplasmic superoxide radicals in an Alzheimers disease mouse model.
Biosci. Biotechnol. Biochem.
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Oxidative stress is involved in the pathogenesis of neurodegeneration. Amyloid ? (A?) oligomer as an intermediate of aggregates causes memory loss in Alzheimers disease (AD). We have suggested that oxidative stress plays an important role in A? oligomerization and cognitive impairment using a human amyloid precursor protein (hAPP) transgenic AD mice lacking cytoplasmic superoxide dismutase (hAPP/Sod1-/-). Recently, clinical trials revealed inhibitors of A? production from hAPP as promising therapeutics, but the relationship between oxidative stress and A? metabolism remains unclear. Here we found that Sod1 deficiency enhanced ?-cleavage of hAPP, suggesting that it increased A? production in hAPP/Sod1-/- mice. In contrast, A? degradation did not decrease in hAPP/Sod1-/- as compared with hAPP/Sod1+/+ mice. Furthermore, we successfully detected in situ superoxide radicals associated with increased protein carbonylation in hAPP/Sod1-/-. These results suggest that cytoplasmic oxidative stress is involved in A? production as well as aggregation during AD progression.
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Identification and biological activities of bryostatins from Japanese bryozoan.
Biosci. Biotechnol. Biochem.
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Six bryostatins were isolated from Japanese bryozoan by evaluating their binding to the C1B domain of protein kinase C? (PKC?). Structure-activity studies of bryostatins 4, 10, and 14 suggested that the ester group at C20 was not necessary for binding to and activating PKC?. These bryostatins showed significant anti-tumor-promoting activity in induction tests with the Epstein-Barr virus early antigen.
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Preparation of stable amyloid ?-protein oligomers of defined assembly order.
Methods Mol. Biol.
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Oligomeric assemblies of the amyloid ?-protein, A?, are thought to be the proximate neurotoxic agents in Alzheimers disease (AD). Oligomer formation is a complex process that produces a polydisperse population of metastable structures. For this reason, formal structure-activity correlations, both in vitro and in vivo, have been difficult to accomplish. An analytical solution to this problem was provided by the application of a photochemical cross-linking method to the A? assembly system. This method, photo-induced cross-linking of unmodified proteins (PICUP), enabled the quantitative determination of the oligomer size distribution. We report here the integration of PICUP with SDS-PAGE and alkaline extraction procedures to create a method for the isolation of pure populations of oligomers of defined order. This method has been used successfully to provide material for formal structure-activity studies of A? oligomers.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.