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

PubMed

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.

Amyloid Precursor Protein Processing and Alzheimer’s Disease

PubMed Central

O’Brien, Richard J.; Wong, Philip C.

2011-01-01

Alzheimer’s disease (AD), the leading cause of dementia worldwide, is characterized by the accumulation of the β-amyloid peptide (Aβ) within the brain along with hyperphosphorylated and cleaved forms of the microtubule-associated protein tau. Genetic, biochemical, and behavioral research suggest that physiologic generation of the neurotoxic Aβ peptide from sequential amyloid precursor protein (APP) proteolysis is the crucial step in the development of AD. APP is a single-pass transmembrane protein expressed at high levels in the brain and metabolized in a rapid and highly complex fashion by a series of sequential proteases, including the intramembranous γ-secretase complex, which also process other key regulatory molecules. Why Aβ accumulates in the brains of elderly individuals is unclear but could relate to changes in APP metabolism or Aβ elimination. Lessons learned from biochemical and genetic studies of APP processing will be crucial to the development of therapeutic targets to treat AD. PMID:21456963

Amyloid precursor protein controls cholesterol turnover needed for neuronal activity

PubMed Central

Pierrot, Nathalie; Tyteca, Donatienne; D'auria, Ludovic; Dewachter, Ilse; Gailly, Philippe; Hendrickx, Aurélie; Tasiaux, Bernadette; Haylani, Laetitia El; Muls, Nathalie; N'Kuli, Francisca; Laquerrière, Annie; Demoulin, Jean-Baptiste; Campion, Dominique; Brion, Jean-Pierre; Courtoy, Pierre J; Kienlen-Campard, Pascal; Octave, Jean-Noël

2013-01-01

Perturbation of lipid metabolism favours progression of Alzheimer disease, in which processing of Amyloid Precursor Protein (APP) has important implications. APP cleavage is tightly regulated by cholesterol and APP fragments regulate lipid homeostasis. Here, we investigated whether up or down regulation of full-length APP expression affected neuronal lipid metabolism. Expression of APP decreased HMG-CoA reductase (HMGCR)-mediated cholesterol biosynthesis and SREBP mRNA levels, while its down regulation had opposite effects. APP and SREBP1 co-immunoprecipitated and co-localized in the Golgi. This interaction prevented Site-2 protease-mediated processing of SREBP1, leading to inhibition of transcription of its target genes. A GXXXG motif in APP sequence was critical for regulation of HMGCR expression. In astrocytes, APP and SREBP1 did not interact nor did APP affect cholesterol biosynthesis. Neuronal expression of APP decreased both HMGCR and cholesterol 24-hydroxylase mRNA levels and consequently cholesterol turnover, leading to inhibition of neuronal activity, which was rescued by geranylgeraniol, generated in the mevalonate pathway, in both APP expressing and mevastatin treated neurons. We conclude that APP controls cholesterol turnover needed for neuronal activity. PMID:23554170

The Fate of Nascent APP in Hippocampal Neurons: A Live Cell Imaging Study.

PubMed

DelBove, Claire E; Deng, Xian-Zhen; Zhang, Qi

2018-06-21

Amyloid precursor protein (APP) is closely associated with Alzheimer's disease (AD) because its proteolytic products form amyloid plaques and its mutations are linked to familial AD patients. As a membrane protein, APP is involved in neuronal development and plasticity. However, it remains unclear how nascent APP is distributed and transported to designated membrane compartments to execute its diverse functions. Here, we employed a dual-tagged APP fusion protein in combination with a synaptic vesicle marker to study the surface trafficking and cleavage of APP in hippocampal neurons immediately after its synthesis. Using long-term time-lapse imaging, we found that a considerable amount of nascent APP was directly transported to the somatodendritic surface, from which it propagates to distal neurites. Some APP in the plasma membrane was endocytosed and some was cleaved by α-secretase. Hence, we conclude that surface transportation of APP is a major step preceding its proteolytic processing and neuritic distribution.

Membrane microdomain switching: a regulatory mechanism of amyloid precursor protein processing

PubMed Central

Sakurai, Takashi; Kaneko, Kumi; Okuno, Misako; Wada, Koji; Kashiyama, Taku; Shimizu, Hideaki; Akagi, Takumi; Hashikawa, Tsutomu; Nukina, Nobuyuki

2008-01-01

Neuronal activity has an impact on β cleavage of amyloid precursor protein (APP) by BACE1 to generate amyloid-β peptide (Aβ). However, the molecular mechanisms underlying this effect remain to be elucidated. Cholesterol dependency of β cleavage prompted us to analyze immunoisolated APP-containing detergent-resistant membranes from rodent brains. We found syntaxin 1 as a key molecule for activity-dependent regulation of APP processing in cholesterol-dependent microdomains. In living cells, APP associates with syntaxin 1–containing microdomains through X11–Munc18, which inhibits the APP–BACE1 interaction and β cleavage via microdomain segregation. Phosphorylation of Munc18 by cdk5 causes a shift of APP to BACE1-containing microdomains. Neuronal hyperactivity, implicated in Aβ overproduction, promotes the switching of APP microdomain association as well as β cleavage in a partially cdk5-dependent manner. We propose that microdomain switching is a mechanism of cholesterol- and activity-dependent regulation of APP processing in neurons. PMID:18936252

APP metabolism regulates tau proteostasis in human cerebral cortex neurons.

PubMed

Moore, Steven; Evans, Lewis D B; Andersson, Therese; Portelius, Erik; Smith, James; Dias, Tatyana B; Saurat, Nathalie; McGlade, Amelia; Kirwan, Peter; Blennow, Kaj; Hardy, John; Zetterberg, Henrik; Livesey, Frederick J

2015-05-05

Accumulation of Aβ peptide fragments of the APP protein and neurofibrillary tangles of the microtubule-associated protein tau are the cellular hallmarks of Alzheimer's disease (AD). To investigate the relationship between APP metabolism and tau protein levels and phosphorylation, we studied human-stem-cell-derived forebrain neurons with genetic forms of AD, all of which increase the release of pathogenic Aβ peptides. We identified marked increases in intracellular tau in genetic forms of AD that either mutated APP or increased its dosage, suggesting that APP metabolism is coupled to changes in tau proteostasis. Manipulating APP metabolism by β-secretase and γ-secretase inhibition, as well as γ-secretase modulation, results in specific increases and decreases in tau protein levels. These data demonstrate that APP metabolism regulates tau proteostasis and suggest that the relationship between APP processing and tau is not mediated solely through extracellular Aβ signaling to neurons. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Amyloid-β Production Via Cleavage of Amyloid-β Protein Precursor is Modulated by Cell Density

PubMed Central

Zhang, Can; Browne, Andrew; DiVito, Jason R.; Stevenson, Jesse A.; Romano, Donna; Dong, Yuanlin; Xie, Zhongcong; Tanzi, Rudolph E.

2012-01-01

Mounting evidence suggests that Alzheimer disease (AD) is caused by the accumulation of the small peptide, Aβ, a proteolytic cleavage product of amyloid-β protein precursor (AβPP; or APP). Aβ is generated through a serial cleavage of APP by β- and γ-secretase. Aβ40 and Aβ42 are the two main components of amyloid plaques in AD brains, with Aβ42 being more prone to aggregation. APP can also be processed by α-secretase, which cleaves APP within the Aβ sequence, thereby preventing the generation of Aβ. Little is currently known regarding the effects of cell density on APP processing and Aβ generation. Here we assessed the effects of cell density on APP processing in neuronal and non-neuronal cell lines, as well as mouse primary cortical neurons. We found that decreased cell density significantly increases levels of Aβ40, Aβ42, total Aβ, and the ratio of Aβ42:Aβ40. These results also indicate that cell density is a significant modulator of APP processing. Overall, these findings carry profound implications for both previous and forthcoming studies aiming to assess the effects of various conditions and genetic/chemical factors, e.g. novel drugs on APP processing and Aβ generation in cell-based systems. Moreover, it is interesting to speculate whether cell density changes in vivo may also affect APP processing and Aβ levels in the AD brain. PMID:20847415

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

PubMed

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.

Redundancy and divergence in the amyloid precursor protein family.

PubMed

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.

Modulation of beta-amyloid precursor protein trafficking and processing by the low density lipoprotein receptor family.

PubMed

Cam, Judy A; Bu, Guojun

2006-08-18

Amyloid-beta peptide (Abeta) accumulation in the brain is an early, toxic event in the pathogenesis of Alzheimer's disease (AD). Abeta is produced by proteolytic processing of a transmembrane protein, beta-amyloid precursor protein (APP), by beta- and gamma-secretases. Mounting evidence has demonstrated that alterations in APP cellular trafficking and localization directly impact its processing to Abeta. Recent studies have shown that members of the low-density lipoprotein receptor family, including LRP, LRP1B, SorLA/LR11, and apolipoprotein E (apoE) receptor 2, interact with APP and regulate its endocytic trafficking. Another common feature of these receptors is their ability to bind apoE, which exists in three isoforms in humans and the presence of the epsilon4 allele represents a genetic risk factor for AD. In this review, we summarize the current understanding of the function of these apoE receptors with a focus on their role in APP trafficking and processing. Knowledge of the interactions between these distinct low-density lipoprotein receptor family members and APP may ultimately influence future therapies for AD.

Rivastigmine Lowers Aβ and Increases sAPPα Levels, Which Parallel Elevated Synaptic Markers and Metabolic Activity in Degenerating Primary Rat Neurons

PubMed Central

Bailey, Jason A.; Ray, Balmiki; Greig, Nigel H.; Lahiri, Debomoy K.

2011-01-01

Overproduction of amyloid-β (Aβ) protein in the brain has been hypothesized as the primary toxic insult that, via numerous mechanisms, produces cognitive deficits in Alzheimer's disease (AD). Cholinesterase inhibition is a primary strategy for treatment of AD, and specific compounds of this class have previously been demonstrated to influence Aβ precursor protein (APP) processing and Aβ production. However, little information is available on the effects of rivastigmine, a dual acetylcholinesterase and butyrylcholinesterase inhibitor, on APP processing. As this drug is currently used to treat AD, characterization of its various activities is important to optimize its clinical utility. We have previously shown that rivastigmine can preserve or enhance neuronal and synaptic terminal markers in degenerating primary embryonic cerebrocortical cultures. Given previous reports on the effects of APP and Aβ on synapses, regulation of APP processing represents a plausible mechanism for the synaptic effects of rivastigmine. To test this hypothesis, we treated degenerating primary cultures with rivastigmine and measured secreted APP (sAPP) and Aβ. Rivastigmine treatment increased metabolic activity in these cultured cells, and elevated APP secretion. Analysis of the two major forms of APP secreted by these cultures, attributed to neurons or glia based on molecular weight showed that rivastigmine treatment significantly increased neuronal relative to glial secreted APP. Furthermore, rivastigmine treatment increased α-secretase cleaved sAPPα and decreased Aβ secretion, suggesting a therapeutic mechanism wherein rivastigmine alters the relative activities of the secretase pathways. Assessment of sAPP levels in rodent CSF following once daily rivastigmine administration for 21 days confirmed that elevated levels of APP in cell culture translated in vivo. Taken together, rivastigmine treatment enhances neuronal sAPP and shifts APP processing toward the α-secretase pathway in degenerating neuronal cultures, which mirrors the trend of synaptic proteins, and metabolic activity. PMID:21799757

Herpes simplex virus interferes with amyloid precursor protein processing

PubMed Central

Shipley, Suzanne J; Parkin, Edward T; Itzhaki, Ruth F; Dobson, Curtis B

2005-01-01

Background The early events underlying Alzheimer's disease (AD) remain uncertain, although environmental factors may be involved. Work in this laboratory has shown that the combination of herpes simplex virus type 1 (HSV1) in brain and carriage of the APOE-ε4 allele of the APOE gene strongly increases the risk of developing AD. The development of AD is thought to involve abnormal aggregation or deposition of a 39–43 amino acid protein – β amyloid (Aβ) – within the brain. This is cleaved from the much larger transmembranal protein 'amyloid precursor protein' (APP). Any agent able to interfere directly with Aβ or APP metabolism may therefore have the capacity to contribute towards AD. One recent report showed that certain HSV1 glycoprotein peptides may aggregate like Aβ; a second study described a role for APP in transport of virus in squid axons. However to date the effects of acute herpesvirus infection on metabolism of APP in human neuronal-type cells have not been investigated. In order to find if HSV1 directly affects APP and its degradation, we have examined this protein from human neuroblastoma cells (normal and transfected with APP 695) infected with the virus, using Western blotting. Results We have found that acute HSV1 (and also HSV2) infection rapidly reduces full length APP levels – as might be expected – yet surprisingly markedly increases levels of a novel C-terminal fragment of APP of about 55 kDa. This band was not increased in cells treated with the protein synthesis inhibitor cycloheximide Conclusion Herpes virus infection leads to rapid loss of full length APP from cells, yet also causes increased levels of a novel 55 kDa C-terminal APP fragment. These data suggest that infection can directly alter the processing of a transmembranal protein intimately linked to the aetiology of AD. PMID:16109164

Rapid endocytosis of the low density lipoprotein receptor-related protein modulates cell surface distribution and processing of the beta-amyloid precursor protein.

PubMed

Cam, Judy A; Zerbinatti, Celina V; Li, Yonghe; Bu, Guojun

2005-04-15

The low density lipoprotein receptor-related protein (LRP) is a approximately 600-kDa multifunctional endocytic receptor that is highly expressed in the brain. LRP and its ligands apolipoprotein E, alpha2-macroglobulin, and beta-amyloid precursor protein (APP), are genetically linked to Alzheimer disease and are found in characteristic plaque deposits in brains of patients with Alzheimer disease. To identify which extracellular domains of LRP interact with APP, we used minireceptors of each of the individual LRP ligand binding domains and assessed their ability to bind and degrade a soluble APP fragment. LRP minireceptors containing ligand binding domains II and IV, but not I or III, interacted with APP. To test whether APP trafficking is directly related to the rapid endocytosis of LRP, we generated stable Chinese hamster ovary cell lines expressing either a wild-type LRP minireceptor or its endocytosis mutants. Chinese hamster ovary cells stably expressing wild-type LRP minireceptor had less cell surface APP than pcDNA3 vector-transfected cells, whereas those stably expressing endocytosis-defective LRP minireceptors accumulated APP at the cell surface. We also found that the steady-state levels of the amyloid beta-peptides (Abeta) is dictated by the relative expression levels of APP and LRP, probably reflecting the dual roles of LRP in both Abeta production and clearance. Together, these data establish a relationship between LRP rapid endocytosis and APP trafficking and proteolytic processing to generate Abeta.

Contribution of Kunitz protease inhibitor and transmembrane domains to amyloid precursor protein homodimerization.

PubMed

Ben Khalifa, N; Tyteca, D; Courtoy, P J; Renauld, J C; Constantinescu, S N; Octave, J N; Kienlen-Campard, P

2012-01-01

The two major isoforms of the human amyloid precursor protein (APP) are APP695 and APP751. They differ by the insertion of a Kunitz-type protease inhibitor (KPI) sequence in the extracellular domain of APP751. APP-KPI isoforms are increased in Alzheimer's disease brains, and they could be associated with disease progression. Recent studies have shown that APP processing to Aβ is regulated by homodimerization, which involves both extracellular and juxtamembrane/transmembrane (JM/TM) regions. Our aim is to understand the mechanisms controlling APP dimerization and the contribution of the ectodomain and JM/TM regions to this process. We used bimolecular fluorescence complementation approaches coupled to fluorescence-activated cell sorting analysis to measure the dimerization level of different APP isoforms and APP C-terminal fragments (C99) mutated in their JM/TM region. APP751 was found to form significantly more homodimers than APP695. Mutation of dimerization motifs in the TM domain of APP or C99 did not significantly affect fluorescence complementation. These findings indicate that the KPI domain plays a major role in APP dimerization. They set the basis for further investigation of the relation between dimerization, metabolism and function of APP. Copyright © 2012 S. Karger AG, Basel.

β- but not γ-secretase proteolysis of APP causes synaptic and memory deficits in a mouse model of dementia.

PubMed

Tamayev, Robert; Matsuda, Shuji; Arancio, Ottavio; D'Adamio, Luciano

2012-03-01

A mutation in the BRI2/ITM2b gene causes loss of BRI2 protein leading to familial Danish dementia (FDD). BRI2 deficiency of FDD provokes an increase in amyloid-β precursor protein (APP) processing since BRI2 is an inhibitor of APP proteolysis, and APP mediates the synaptic/memory deficits in FDD. APP processing is linked to Alzheimer disease (AD) pathogenesis, which is consistent with a common mechanism involving toxic APP metabolites in both dementias. We show that inhibition of APP cleavage by β-secretase rescues synaptic/memory deficits in a mouse model of FDD. β-cleavage of APP yields amino-terminal-soluble APPβ (sAPPβ) and β-carboxyl-terminal fragments (β-CTF). Processing of β-CTF by γ-secretase releases amyloid-β (Aβ), which is assumed to cause AD. However, inhibition of γ-secretase did not ameliorate synaptic/memory deficits of FDD mice. These results suggest that sAPPβ and/or β-CTF, rather than Aβ, are the toxic species causing dementia, and indicate that reducing β-cleavage of APP is an appropriate therapeutic approach to treating human dementias. Our data and the failures of anti-Aβ therapies in humans advise against targeting γ-secretase cleavage of APP and/or Aβ. Copyright © 2012 EMBO Molecular Medicine.

β- but not γ-secretase proteolysis of APP causes synaptic and memory deficits in a mouse model of dementia

PubMed Central

Tamayev, Robert; Matsuda, Shuji; Arancio, Ottavio; D'Adamio, Luciano

2012-01-01

A mutation in the BRI2/ITM2b gene causes loss of BRI2 protein leading to familial Danish dementia (FDD). BRI2 deficiency of FDD provokes an increase in amyloid-β precursor protein (APP) processing since BRI2 is an inhibitor of APP proteolysis, and APP mediates the synaptic/memory deficits in FDD. APP processing is linked to Alzheimer disease (AD) pathogenesis, which is consistent with a common mechanism involving toxic APP metabolites in both dementias. We show that inhibition of APP cleavage by β-secretase rescues synaptic/memory deficits in a mouse model of FDD. β-cleavage of APP yields amino-terminal-soluble APPβ (sAPPβ) and β-carboxyl-terminal fragments (β-CTF). Processing of β-CTF by γ-secretase releases amyloid-β (Aβ), which is assumed to cause AD. However, inhibition of γ-secretase did not ameliorate synaptic/memory deficits of FDD mice. These results suggest that sAPPβ and/or β-CTF, rather than Aβ, are the toxic species causing dementia, and indicate that reducing β-cleavage of APP is an appropriate therapeutic approach to treating human dementias. Our data and the failures of anti-Aβ therapies in humans advise against targeting γ-secretase cleavage of APP and/or Aβ. PMID:22170863

An Aberrant Phosphorylation of Amyloid Precursor Protein Tyrosine Regulates Its Trafficking and the Binding to the Clathrin Endocytic Complex in Neural Stem Cells of Alzheimer's Disease Patients

PubMed Central

Poulsen, Ebbe T.; Iannuzzi, Filomena; Rasmussen, Helle F.; Maier, Thorsten J.; Enghild, Jan J.; Jørgensen, Arne L.; Matrone, Carmela

2017-01-01

Alzheimer's disease (AD) is the most common cause of dementia and is likely caused by defective amyloid precursor protein (APP) trafficking and processing in neurons leading to amyloid plaques containing the amyloid-β (Aβ) APP peptide byproducts. Understanding how APP is targeted to selected destinations inside neurons and identifying the mechanisms responsible for the generation of Aβ are thus the keys for the advancement of new therapies. We previously developed a mouse model with a mutation at tyrosine (Tyr) 682 in the C-terminus of APP. This residue is needed for APP to bind to the coating protein Clathrin and to the Clathrin adaptor protein AP2 as well as for the correct APP trafficking and sorting in neurons. By extending these findings to humans, we found that APP binding to Clathrin is decreased in neural stem cells from AD sufferers. Increased APP Tyr phosphorylation alters APP trafficking in AD neurons and it is associated to Fyn Tyr kinase activation. We show that compounds affecting Tyr kinase activity and counteracting defects in AD neurons can control APP location and compartmentalization. APP Tyr phosphorylation is thus a potential therapeutic target for AD. PMID:28360834

3,4-Methylenedioxymethamphetamine (MDMA), but not morphine, alters APP processing in the rat brain.

PubMed

Kálmán, János; Bjelik, Annamária; Hugyecz, Marietta; Tímár, Júlia; Gyarmati, Zsuzsanna; Zana, Marianna; Fürst, Zsuzsanna; Janka, Zoltán; Rakonczay, Zoltán; Horváth, Zoltán; Pákáski, Magdolna

2007-04-01

The abuse of drugs such as opioids and 3,4-methylenedioxymethamphetamine (MDMA or 'ecstasy') can have detrimental effects on the cognitive functions, but the exact molecular mechanism whereby these drugs promote neurodegeneration remains to be elucidated. The major purpose of the present pilot study was to determine whether the chronic in-vivo administration of morphine (10 mg/kg) or MDMA (1 mg/kg) to rats can alter the expression and processing of amyloid precursor protein (APP), the central molecule in the proposed pathomechanism of Alzheimer's disease. MDMA treatment significantly decreased the production of APP in the cytosolic fraction of the brain cortex. A concomitant 25% increase was found both in the beta-secretase (BACE) and APP mRNA levels (108%). In contrast, in the applied single dosage chronic morphine treatment did not influence either the APP and BACE protein levels or the APP mRNA production. These results indicate that the chronic use of 'ecstasy', but not morphine, may be harmful via a novel mode of action, i.e. by altering the APP expression and processing in the brain.

Effects of acetylate hyperforin on the processing of amyloid precursor protein.

PubMed

Chen, Xiang; Feng, Wenshang; Chen, Qing; Yang, Xiangling; Yang, Depo; Wang, Dongmei; Zhong, Ling

2009-02-20

Hyperforin (HF) is a phloroglucinol compound obtained from St. John's Wort (Hypericum perforatum). Recent studies have shown that Hyperforin can be used to improve psychopathologic symptoms of Alzheimer's disease but the mechanism is not clear. This may be partly due to the difficult in studying Hyperforin, since this chemical is unstable and is sensitive to light, oxygen, and heat. In this study, we explored the effects of acetylate hyperforin (ace-HF), a stable derivative of hyperforin, on the processing of amyloid precursor protein (APP). HEK293 cells transfected with pcDNA3.1APP695sw and SH-SY5Y cells were treated with ace-HF, followed by measuring the levels of APP and sAPPα. Twelve hours of treatment led to an increase in extracellular sAPPα, but APP mRNA and protein levels were unchanged. Further studies with α-secretase and a pan PKC inhibitor, Calphostin C, indicated that ace-HF's effect on extracellular sAPPα was closely related to PKC activities and α-secretase activities. Our findings suggest that ace-HF can modulate α-secretase-mediated APP processing via a PKC signaling pathway.

The low density lipoprotein receptor-related protein 1B retains beta-amyloid precursor protein at the cell surface and reduces amyloid-beta peptide production.

PubMed

Cam, Judy A; Zerbinatti, Celina V; Knisely, Jane M; Hecimovic, Silva; Li, Yonghe; Bu, Guojun

2004-07-09

The low density lipoprotein (LDL) receptor-related protein 1B (LRP1B) is a newly identified member of the LDL receptor family that shares high homology with the LDL receptor-related protein (LRP). LRP1B was originally described as a putative tumor suppressor in lung cancer cells; however, its expression profile in several regions of adult human brain suggests it may have additional functions in the central nervous system. Since LRP1B has overlapping ligand binding properties with LRP, we investigated whether LRP1B, like LRP, could interact with the beta-amyloid precursor protein (APP) and modulate its processing to amyloid-beta peptides (Abetas). Using an LRP1B minireceptor (mLRP1B4) generated to study the trafficking of LRP1B, we found that mLRP1B4 and APP form an immunoprecipitable complex. Furthermore mLRP1B4 bound and facilitated the degradation of a soluble isoform of APP containing a Kunitz proteinase inhibitor domain but not soluble APP lacking a Kunitz proteinase inhibitor domain. A functional consequence of mLRP1B4 expression was a significant accumulation of APP at the cell surface, which is likely related to the slow endocytosis rate of LRP1B. More importantly, mLRP1B4-expressing cells that accumulated cell surface APP produced less Abeta and secreted more soluble APP. These findings reveal that LRP1B is a novel binding partner of APP that functions to decrease APP processing to Abeta. Consequently LRP1B expression could function to protect against the pathogenesis of Alzheimer's disease.

Full-length amyloid precursor protein regulates lipoprotein metabolism and amyloid-β clearance in human astrocytes.

PubMed

Fong, Lauren K; Yang, Max M; Dos Santos Chaves, Rodrigo; Reyna, Sol M; Langness, Vanessa F; Woodruff, Grace; Roberts, Elizabeth A; Young, Jessica E; Goldstein, Lawrence S B

2018-06-01

Mounting evidence suggests that alterations in cholesterol homeostasis are involved in Alzheimer's disease (AD) pathogenesis. Amyloid precursor protein (APP) or multiple fragments generated by proteolytic processing of APP have previously been implicated in the regulation of cholesterol metabolism. However, the physiological function of APP in regulating lipoprotein homeostasis in astrocytes, which are responsible for de novo cholesterol biosynthesis and regulation in the brain, remains unclear. To address this, here we used CRISPR/Cas9 genome editing to generate isogenic APP-knockout (KO) human induced pluripotent stem cells (hiPSCs) and differentiated them into human astrocytes. We found that APP-KO astrocytes have reduced cholesterol and elevated levels of sterol regulatory element-binding protein (SREBP) target gene transcripts and proteins, which were both downstream consequences of reduced lipoprotein endocytosis. To elucidate which APP fragments regulate cholesterol homeostasis and examine whether familial AD mutations in APP affect lipoprotein metabolism, we analyzed an isogenic allelic series harboring the APP Swedish and APP V717F variants. Only astrocytes homozygous for the APP Swedish (APP Swe/Swe ) mutation, which had reduced full-length APP (FL APP) due to increased β-secretase cleavage, recapitulated the APP-KO phenotypes. Astrocytic internalization of amyloid-β (Aβ), another ligand for low-density lipoprotein (LDL) receptors, was also impaired in APP-KO and APP Swe/Swe astrocytes. Finally, impairing cleavage of FL APP through β-secretase inhibition in APP Swe/Swe astrocytes reversed the LDL and Aβ endocytosis defects. In conclusion, FL APP is involved in the endocytosis of LDL receptor ligands and required for proper cholesterol homeostasis and Aβ clearance in human astrocytes. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

The kunitz protease inhibitor form of the amyloid precursor protein (KPI/APP) inhibits the proneuropeptide processing enzyme prohormone thiol protease (PTP). Colocalization of KPI/APP and PTP in secretory vesicles.

PubMed

Hook, V Y; Sei, C; Yasothornsrikul, S; Toneff, T; Kang, Y H; Efthimiopoulos, S; Robakis, N K; Van Nostrand, W

1999-01-29

Proteolytic processing of proenkephalin and proneuropeptides is required for the production of active neurotransmitters and peptide hormones. Variations in the extent of proenkephalin processing in vivo suggest involvement of endogenous protease inhibitors. This study demonstrates that "protease nexin 2 (PN2)," the secreted form of the kunitz protease inhibitor (KPI) of the amyloid precursor protein (APP), potently inhibited the proenkephalin processing enzyme known as prohormone thiol protease (PTP), with a Ki,app of 400 nM. Moreover, PTP and PN2 formed SDS-stable complexes that are typical of kunitz protease inhibitor interactions with target proteases. In vivo, KPI/APP (120 kDa), as well as a truncated form of KPI/APP that resembles PN2 in apparent molecular mass (110 kDa), were colocalized with PTP and (Met)enkephalin in secretory vesicles of adrenal medulla (chromaffin granules). KPI/APP (110-120 kDa) was also detected in pituitary secretory vesicles that contain PTP. In chromaffin cells, calcium-dependent secretion of KPI/APP with PTP and (Met)enkephalin demonstrated the colocalization of these components in functional secretory vesicles. These results suggest a role for KPI/APP inhibition of PTP in regulated secretory vesicles. In addition, these results are the first to identify an endogenous protease target of KPI/APP, which is developmentally regulated in aging and Alzheimer's disease.

APP heterozygosity averts memory deficit in knockin mice expressing the Danish dementia BRI2 mutant.

PubMed

Tamayev, Robert; Matsuda, Shuji; Giliberto, Luca; Arancio, Ottavio; D'Adamio, Luciano

2011-05-17

An autosomal dominant mutation in the BRI2/ITM2B gene causes familial Danish dementia (FDD). Analysis of FDD(KI) mice, a mouse model of FDD genetically congruous to the human disease since they carry one mutant and one wild-type Bri2/Itm2b allele, has shown that the Danish mutation causes loss of Bri2 protein, synaptic plasticity and memory impairments. BRI2 is a physiological interactor of Aβ-precursor protein (APP), a gene associated with Alzheimer disease, which inhibits processing of APP. Here, we show that APP/Bri2 complexes are reduced in synaptic membranes of FDD(KI) mice. Consequently, APP metabolites derived from processing of APP by β-, α- and γ-secretases are increased in Danish dementia mice. APP haplodeficiency prevents memory and synaptic dysfunctions, consistent with a role for APP metabolites in the pathogenesis of memory and synaptic deficits. This genetic suppression provides compelling evidence that APP and BRI2 functionally interact, and that the neurological effects of the Danish form of BRI2 only occur when sufficient levels of APP are supplied by two alleles. This evidence establishes a pathogenic sameness between familial Danish and Alzheimer's dementias.

APP heterozygosity averts memory deficit in knockin mice expressing the Danish dementia BRI2 mutant

PubMed Central

Tamayev, Robert; Matsuda, Shuji; Giliberto, Luca; Arancio, Ottavio; D'Adamio, Luciano

2011-01-01

An autosomal dominant mutation in the BRI2/ITM2B gene causes familial Danish dementia (FDD). Analysis of FDDKI mice, a mouse model of FDD genetically congruous to the human disease since they carry one mutant and one wild-type Bri2/Itm2b allele, has shown that the Danish mutation causes loss of Bri2 protein, synaptic plasticity and memory impairments. BRI2 is a physiological interactor of Aβ-precursor protein (APP), a gene associated with Alzheimer disease, which inhibits processing of APP. Here, we show that APP/Bri2 complexes are reduced in synaptic membranes of FDDKI mice. Consequently, APP metabolites derived from processing of APP by β-, α- and γ-secretases are increased in Danish dementia mice. APP haplodeficiency prevents memory and synaptic dysfunctions, consistent with a role for APP metabolites in the pathogenesis of memory and synaptic deficits. This genetic suppression provides compelling evidence that APP and BRI2 functionally interact, and that the neurological effects of the Danish form of BRI2 only occur when sufficient levels of APP are supplied by two alleles. This evidence establishes a pathogenic sameness between familial Danish and Alzheimer's dementias. PMID:21587206

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

PubMed

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.

Adaptor protein 2–mediated endocytosis of the β-secretase BACE1 is dispensable for amyloid precursor protein processing

PubMed Central

Prabhu, Yogikala; Burgos, Patricia V.; Schindler, Christina; Farías, Ginny G.; Magadár, Javier G.; Bonifacino, Juan S.

2012-01-01

The β-site amyloid precursor protein (APP)–cleaving enzyme 1 (BACE1) is a transmembrane aspartyl protease that catalyzes the proteolytic processing of APP and other plasma membrane protein precursors. BACE1 cycles between the trans-Golgi network (TGN), the plasma membrane, and endosomes by virtue of signals contained within its cytosolic C-terminal domain. One of these signals is the DXXLL-motif sequence DISLL, which controls transport between the TGN and endosomes via interaction with GGA proteins. Here we show that the DISLL sequence is embedded within a longer [DE]XXXL[LI]-motif sequence, DDISLL, which mediates internalization from the plasma membrane by interaction with the clathrin-associated, heterotetrameric adaptor protein 2 (AP-2) complex. Mutation of this signal or knockdown of either AP-2 or clathrin decreases endosomal localization and increases plasma membrane localization of BACE1. Remarkably, internalization-defective BACE1 is able to cleave an APP mutant that itself cannot be delivered to endosomes. The drug brefeldin A reversibly prevents BACE1-catalyzed APP cleavage, ruling out that this reaction occurs in the endoplasmic reticulum (ER) or ER–Golgi intermediate compartment. Taken together, these observations support the notion that BACE1 is capable of cleaving APP in late compartments of the secretory pathway. PMID:22553349

Tyrosine Binding Protein Sites Regulate the Intracellular Trafficking and Processing of Amyloid Precursor Protein through a Novel Lysosome-Directed Pathway

PubMed Central

Tam, Joshua H. K.; Cobb, M. Rebecca; Seah, Claudia; Pasternak, Stephen H.

2016-01-01

The amyloid hypothesis posits that the production of β-amyloid (Aβ) aggregates leads to neurodegeneration and cognitive decline associated with AD. Aβ is produced by sequential cleavage of the amyloid precursor protein (APP) by β- and γ-secretase. While nascent APP is well known to transit to the endosomal/ lysosomal system via the cell surface, we have recently shown that APP can also traffic to lysosomes intracellularly via its interaction with AP-3. Because AP-3 interacts with cargo protein via interaction with tyrosine motifs, we mutated the three tyrosines motif in the cytoplasmic tail of APP. Here, we show that the YTSI motif interacts with AP-3, and phosphorylation of the serine in this motif disrupts the interaction and decreases APP trafficking to lysosomes. Furthermore, we show that phosphorylation at this motif can decrease the production of neurotoxic Aβ 42. This demonstrates that reducing APP trafficking to lysosomes may be a strategy to reduce Aβ 42 in Alzheimer’s disease. PMID:27776132

Tyrosine Binding Protein Sites Regulate the Intracellular Trafficking and Processing of Amyloid Precursor Protein through a Novel Lysosome-Directed Pathway.

PubMed

Tam, Joshua H K; Cobb, M Rebecca; Seah, Claudia; Pasternak, Stephen H

2016-01-01

The amyloid hypothesis posits that the production of β-amyloid (Aβ) aggregates leads to neurodegeneration and cognitive decline associated with AD. Aβ is produced by sequential cleavage of the amyloid precursor protein (APP) by β- and γ-secretase. While nascent APP is well known to transit to the endosomal/ lysosomal system via the cell surface, we have recently shown that APP can also traffic to lysosomes intracellularly via its interaction with AP-3. Because AP-3 interacts with cargo protein via interaction with tyrosine motifs, we mutated the three tyrosines motif in the cytoplasmic tail of APP. Here, we show that the YTSI motif interacts with AP-3, and phosphorylation of the serine in this motif disrupts the interaction and decreases APP trafficking to lysosomes. Furthermore, we show that phosphorylation at this motif can decrease the production of neurotoxic Aβ 42. This demonstrates that reducing APP trafficking to lysosomes may be a strategy to reduce Aβ 42 in Alzheimer's disease.

Opposite Dysregulation of Fragile-X Mental Retardation Protein and Heteronuclear Ribonucleoprotein C Protein Associates with Enhanced APP Translation in Alzheimer Disease.

PubMed

Borreca, Antonella; Gironi, Katia; Amadoro, Giusy; Ammassari-Teule, Martine

2016-07-01

Amyloid precursor protein (APP) is overexpressed in familiar and sporadic Alzheimer Disease (AD) patients suggesting that, in addition to abnormalities in APP cleavage, enhanced levels of APP full length might contribute to the pathology. Based on data showing that the two RNA binding proteins (RBPs), Fragile-X Mental Retardation Protein (FMRP) and heteronuclear Ribonucleoprotein C (hnRNP C), exert an opposite control on APP translation, we have analyzed whether expression and translation of these two RBPs vary in relation to changes in APP protein and mRNA levels in the AD brain at 1, 3, and 6 months of age. Here, we show that, as expected, human APP is overexpressed in hippocampal total extract from Tg2576 mice at all age points. APP overexpression, however, is not stable over time but reaches its maximal level in 1-month-old mutants in association with the stronger (i) reduction of FMRP and (ii) augmentation of hnRNP C. APP levels then decrease progressively as a function of age in close relationship with the gradual normalization of FMRP and hnRNP C levels. Consistent with the mouse data, expression of FMRP and hnRNP C are, respectively, decreased and increased in hippocampal synaptosomes from sporadic AD patients. Our findings identify two RBP targets that might be manipulated for reducing abnormally elevated levels of APP in the AD brain, with the hypothesis that acting upstream of amyloidogenic processing might contribute to attenuate the amyloid burden.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kosicek, Marko, E-mail: marko.kosicek@irb.hr; Malnar, Martina, E-mail: martina.malnar@irb.hr; Goate, Alison, E-mail: goate@icarus.wustl.edu

It has been suggested that cholesterol may modulate amyloid-{beta} (A{beta}) formation, a causative factor of Alzheimer's disease (AD), by regulating distribution of the three key proteins in the pathogenesis of AD ({beta}-amyloid precursor protein (APP), {beta}-secretase (BACE1) and/or presenilin 1 (PS1)) within lipid rafts. In this work we tested whether cholesterol accumulation upon NPC1 dysfunction, which causes Niemann Pick type C disease (NPC), causes increased partitioning of APP into lipid rafts leading to increased CTF/A{beta} formation in these cholesterol-rich membrane microdomains. To test this we used CHO NPC1{sup -/-} cells (NPC cells) and parental CHOwt cells. By sucrose density gradientmore » centrifugation we observed a shift in fl-APP/CTF compartmentalization into lipid raft fractions upon cholesterol accumulation in NPC vs. wt cells. Furthermore, {gamma}-secretase inhibitor treatment significantly increased fl-APP/CTF distribution in raft fractions in NPC vs. wt cells, suggesting that upon cholesterol accumulation in NPC1-null cells increased formation of APP-CTF and its increased processing towards A{beta} occurs in lipid rafts. Our results support that cholesterol overload, such as in NPC disease, leads to increased partitioning of APP/CTF into lipid rafts resulting in increased amyloidogenic processing of APP in these cholesterol-rich membranes. This work adds to the mechanism of the cholesterol-effect on APP processing and the pathogenesis of Alzheimer's disease and supports the role of lipid rafts in these processes.« less

Effects of acetylate hyperforin on the processing of amyloid precursor protein

PubMed Central

Chen, Xiang; Feng, Wenshang; Chen, Qing; Yang, Xiangling; Yang, Depo; Wang, Dongmei; Zhong, Ling

2009-01-01

Hyperforin (HF) is a phloroglucinol compound obtained from St. John's Wort (Hypericum perforatum). Recent studies have shown that Hyperforin can be used to improve psychopathologic symptoms of Alzheimer's disease but the mechanism is not clear. This may be partly due to the difficult in studying Hyperforin, since this chemical is unstable and is sensitive to light, oxygen, and heat. In this study, we explored the effects of acetylate hyperforin (ace-HF), a stable derivative of hyperforin, on the processing of amyloid precursor protein (APP). HEK293 cells transfected with pcDNA3.1APP695sw and SH-SY5Y cells were treated with ace-HF, followed by measuring the levels of APP and sAPPα. Twelve hours of treatment led to an increase in extracellular sAPPα, but APP mRNA and protein levels were unchanged. Further studies with α-secretase and a pan PKC inhibitor, Calphostin C, indicated that ace-HF's effect on extracellular sAPPα was closely related to PKC activities and α-secretase activities. Our findings suggest that ace-HF can modulate α-secretase-mediated APP processing via a PKC signaling pathway. PMID:21383880

Human apoB overexpression and a high-cholesterol diet differently modify the brain APP metabolism in the transgenic mouse model of atherosclerosis.

PubMed

Bjelik, Annamária; Bereczki, Erika; Gonda, Szilvia; Juhász, Anna; Rimanóczy, Agnes; Zana, Marianna; Csont, Tamás; Pákáski, Magdolna; Boda, Krisztina; Ferdinandy, Péter; Dux, László; Janka, Zoltán; Sántha, Miklós; Kálmán, János

2006-09-01

Epidemiological and biochemical data suggest a link between the cholesterol metabolism, the amyloid precursor protein (APP) processing and the increased cerebral beta-amyloid (Abeta) deposition in Alzheimer's disease (AD). The individual and combined effects of a high-cholesterol (HC) diet and the overexpression of the human apoB-100 gene were therefore examined on the cerebral expression and processing of APP in homozygous apoB-100 transgenic mice [Tg (apoB(+/+))], a validated model of atherosclerosis. When fed with 2% cholesterol for 17 weeks, only the wild-type mice exhibited significantly increased APP695 (123%) and APP770 (138%) mRNA levels in the cortex. The HC diet-induced hypercholesterolemia significantly increased the APP isoform levels in the membrane-bound fraction, not only in the wild-type animals (114%), but also in the Tg apoB(+/+) group (171%). The overexpression of human apoB-100 gene by the liver alone reduced the brain APP isoform levels in the membrane-bound fraction (78%), whereas the levels were increased by the combined effect of HC and the overexpression of the human apoB-100 gene (134%). The protein kinase C and beta-secretase protein levels were not altered by the individual or combined effects of these two factors. Our data indicate that the two atherogenic factors, the HC diet and the overexpression of the human apoB-100 gene by the liver, could exert different effects on the processing and expression of APP in the mice brain.

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

PubMed Central

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

Ubiquilin-1 and protein quality control in Alzheimer disease.

PubMed

El Ayadi, Amina; Stieren, Emily S; Barral, José M; Boehning, Darren

2013-01-01

Single nucleotide polymorphisms in the ubiquilin-1 gene may confer risk for late-onset Alzheimer disease (AD). We have shown previously that ubiquilin-1 functions as a molecular chaperone for the amyloid precursor protein (APP) and that protein levels of ubiquilin-1 are decreased in the brains of AD patients. We have recently found that ubiquilin-1 regulates APP trafficking and subsequent secretase processing by stimulating non-degradative ubiquitination of a single lysine residue in the cytosolic domain of APP. Thus, ubiquilin-1 plays a central role in regulating APP biosynthesis, trafficking and ultimately toxicity. As ubiquilin-1 and other ubiquilin family members have now been implicated in the pathogenesis of numerous neurodegenerative diseases, these findings provide mechanistic insights into the central role of ubiquilin proteins in maintaining neuronal proteostasis.

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

PubMed

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.

Decreasing the expression of PICALM reduces endocytosis and the activity of β-secretase: implications for Alzheimer's disease.

PubMed

Thomas, Rhian S; Henson, Alex; Gerrish, Amy; Jones, Lesley; Williams, Julie; Kidd, Emma J

2016-07-18

Polymorphisms in the gene for phosphatidylinositol binding clathrin assembly protein (PICALM), an endocytic-related protein, are associated with a small, increased risk of developing Alzheimer's disease (AD), strongly suggesting that changes in endocytosis are involved in the aetiology of the disease. We have investigated the involvement of PICALM in the processing of amyloid precursor protein (APP) to understand how PICALM could be linked to the development of AD. We used siRNA to deplete levels of PICALM, its isoforms and clathrin heavy chain in the human brain-derived H4 neuroglioma cell line that expresses endogenous levels of APP. We then used Western blotting, ELISA and immunohistochemistry to detect intra- and extracellular protein levels of endocytic-related proteins, APP and APP metabolites including β-amyloid (Aβ). Levels of functional endocytosis were quantified using ALEXA 488-conjugated transferrin and flow cytometry as a marker of clathrin-mediated endocytosis (CME). Following depletion of all the isoforms of PICALM by siRNA in H4 cells, levels of intracellular APP, intracellular β-C-terminal fragment (β-CTF) and secreted sAPPβ (APP fragments produced by β-secretase cleavage) were significantly reduced but Aβ40 was not affected. Functional endocytosis was significantly reduced after both PICALM and clathrin depletion, highlighting the importance of PICALM in this process. However, depletion of clathrin did not affect APP but did reduce β-CTF levels. PICALM depletion altered the intracellular distribution of clathrin while clathrin reduction affected the subcellular pattern of PICALM labelling. Both PICALM and clathrin depletion reduced the expression of BACE1 mRNA and PICALM siRNA reduced protein levels. Individual depletion of PICALM isoforms 1 and 2 did not affect APP levels while clathrin depletion had a differential effect on the isoforms, increasing isoform 1 while decreasing isoform 2 expression. The depletion of PICALM in brain-derived cells has significant effects on the processing of APP, probably by reducing CME. In particular, it affects the production of β-CTF which is increasingly considered to be an important mediator in AD independent of Aβ. Thus a decrease in PICALM expression in the brain could be beneficial to slow or prevent the development of AD.

Interaction of the amyloid precursor protein-like protein 1 (APLP1) E2 domain with heparan sulfate involves two distinct binding modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahms, Sven O., E-mail: sdahms@fli-leibniz.de; Mayer, Magnus C.; Miltenyi Biotec GmbH, Robert-Koch-Strasse 1, 17166 Teterow

2015-03-01

Two X-ray structures of APLP1 E2 with and without a heparin dodecasaccharide are presented, revealing two distinct binding modes of the protein to heparan sulfate. The data provide a mechanistic explanation of how APP-like proteins bind to heparan sulfates and how they specifically recognize nonreducing structures of heparan sulfates. Beyond the pathology of Alzheimer’s disease, the members of the amyloid precursor protein (APP) family are essential for neuronal development and cell homeostasis in mammals. APP and its paralogues APP-like protein 1 (APLP1) and APP-like protein 2 (APLP2) contain the highly conserved heparan sulfate (HS) binding domain E2, which effects variousmore » (patho)physiological functions. Here, two crystal structures of the E2 domain of APLP1 are presented in the apo form and in complex with a heparin dodecasaccharide at 2.5 Å resolution. The apo structure of APLP1 E2 revealed an unfolded and hence flexible N-terminal helix αA. The (APLP1 E2){sub 2}–(heparin){sub 2} complex structure revealed two distinct binding modes, with APLP1 E2 explicitly recognizing the heparin terminus but also interacting with a continuous heparin chain. The latter only requires a certain register of the sugar moieties that fits to a positively charged surface patch and contributes to the general heparin-binding capability of APP-family proteins. Terminal binding of APLP1 E2 to heparin specifically involves a structure of the nonreducing end that is very similar to heparanase-processed HS chains. These data reveal a conserved mechanism for the binding of APP-family proteins to HS and imply a specific regulatory role of HS modifications in the biology of APP and APP-like proteins.« less

Nicergoline stimulates protein kinase C mediated alpha-secretase processing of the amyloid precursor protein in cultured human neuroblastoma SH-SY5Y cells.

PubMed

Cedazo-Minguez, A; Bonecchi, L; Winblad, B; Post, C; Wong, E H; Cowburn, R F; Benatti, L

1999-10-01

We investigated the ability of the antidementia agents, nicergoline, aniracetam and hydergine to stimulate PKC mediated alpha-secretase amyloid precursor protein (APP) processing in cultured human neuroblastoma SH-SY5Y cells. Western immunoblotting of cell conditioned media using the Mabs 22C11 and 6E10 revealed the presence of 2 bands with molecular mass of 90 and 120 kDa, corresponding to possible alternatively glycosylated forms of secreted APP (APPs). Short-term (30 min and 2 h) treatment of cells with nicergoline gave an increased intensity of both bands, compared to non-treated cells. Maximal nicergoline effects, of the order of 150-200% over basal APPs release, were seen at concentrations between 1 and 10 microM. Under the same condition, 1 microM PdBu, used as a positive control, gave 500-1000% increases of basal APPs release. In contrast, aniracetam and hydergine, did not show any effect on APPs secretion. 2 h treatment with nicergoline had no effect on cellular full-length APP levels, as determined by immunoblotting of cell extracts with 22C11 and CT15 antibodies. Immunoblotting with PKC isoform specific antibodies of soluble and membrane fractions prepared from 2 h treated cells, showed that nicergoline (50 microM) and PdBu (1 microM) both induced translocation of PKC alpha, gamma and epsilon, but not PKC beta. The involvement of PKC in mediating nicergoline stimulated APPs release was also studied using specific inhibitors. 1 microM calphostin C, a broad range PKC inhibitor, significantly reduced both PdBu (1 microM) and nicergoline (10 microM) induced APPs release. In contrast, Go6976 (1 microM), a selective PKC alpha and beta1 inhibitor, as well as the cAMP-dependent protein kinase inhibitor, H89 (1 microM) were without effect. These results indicate that nicergoline can modulate alpha-secretase APP processing by a PKC dependent mechanism that is likely to involve the gamma and epsilon isoforms of this enzyme.

The Exosome Secretory Pathway Transports Amyloid Precursor Protein Carboxyl-terminal Fragments from the Cell into the Brain Extracellular Space*

PubMed Central

Perez-Gonzalez, Rocio; Gauthier, Sebastien A.; Kumar, Asok; Levy, Efrat

2012-01-01

In vitro studies have shown that neuronal cell cultures secrete exosomes containing amyloid-β precursor protein (APP) and the APP-processing products, C-terminal fragments (CTFs) and amyloid-β (Aβ). We investigated the secretion of full-length APP (flAPP) and APP CTFs via the exosome secretory pathway in vivo. To this end, we developed a novel protocol designed to isolate exosomes secreted into mouse brain extracellular space. Exosomes with typical morphology were isolated from freshly removed mouse brains and from frozen mouse and human brain tissues, demonstrating that exosomes can be isolated from post-mortem tissue frozen for long periods of time. flAPP, APP CTFs, and enzymes that cleave both flAPP and APP CTFs were identified in brain exosomes. Although higher levels of both flAPP and APP CTFs were observed in exosomes isolated from the brains of transgenic mice overexpressing human APP (Tg2576) compared with wild-type control mice, there was no difference in the number of secreted brain exosomes. These data indicate that the levels of flAPP and APP CTFs associated with exosomes mirror the cellular levels of flAPP and APP CTFs. Interestingly, exosomes isolated from the brains of both Tg2576 and wild-type mice are enriched with APP CTFs relative to flAPP. Thus, we hypothesize that the exosome secretory pathway plays a pleiotropic role in the brain: exosome secretion is beneficial to the cell, acting as a specific releasing system of neurotoxic APP CTFs and Aβ, but the secretion of exosomes enriched with APP CTFs, neurotoxic proteins that are also a source of secreted Aβ, is harmful to the brain. PMID:23129776

Amyloid precursor protein modulates ERK-1 and -2 signaling.

PubMed

Venezia, Valentina; Nizzari, Mario; Repetto, Emanuela; Violani, Elisabetta; Corsaro, Alessandro; Thellung, Stefano; Villa, Valentina; Carlo, Pia; Schettini, Gennaro; Florio, Tullio; Russo, Claudio

2006-12-01

The amyloid precursor protein (APP) is a transmembrane protein with a short cytoplasmic tail whose physiological function is unclear, although it is well documented that the proteolytic processing of APP could influence the development of Alzheimer's disease (AD) through the formation of membrane-bound C-terminal fragments (CTFs) and of beta-amyloid peptides (Abeta). We have recently shown that tyrosine-phosphorylated APP and CTFs may interact with Grb2 and ShcA adaptor proteins and that this coupling occurs at a higher extent in AD subjects only. To study the interaction between APP or CTFs and ShcA/Grb2 and to investigate their molecular target we have used as experimental model two different cell lines: H4 human neuroglioma cells and APP/APLP null mouse embryonic fibroblast cells (MEFs). Here we show that in H4 cells APP interacts with Grb2; conversely in APP/APLP-null MEF cells this interaction is possible only after the reintroduction of human APP by transfection. We have also shown that in MEF cells the transfection of a plasmid encoding for human APP wild-type enhances the phosphorylation of ERK-1 and -2 as revealed by Western blotting and immunofluorescence experiments. Finally, also in H4 cells the overexpression of APP upregulates the levels of phospho-ERK-1 and -2. In summary our data suggest that APP may influence phospho-ERK-1 and -2 signaling through its binding with Grb2 and ShcA adaptors. The meaning of this event is not clear, but APP interaction with these adaptors could be relevant to regulate mitogenic pathway.

The Prenylflavonoid Xanthohumol Reduces Alzheimer-Like Changes and Modulates Multiple Pathogenic Molecular Pathways in the Neuro2a/APPswe Cell Model of AD.

PubMed

Huang, Xianfeng; Wang, Jing; Chen, Xiao; Liu, Pan; Wang, Shujin; Song, Fangchen; Zhang, Zaijun; Zhu, Feiqi; Huang, Xinfeng; Liu, Jianjun; Song, Guoqiang; Spencer, Peter S; Yang, Xifei

2018-01-01

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that has proved refractory to drug treatment. Given evidence of neuroprotection in animal models of ischemic stroke, we assessed the prenylflavonoid xanthohumol from the Common Hop ( Humulus lupulus L.) for therapeutic potential in murine neuroblastoma N2a cells stably expressing human Swedish mutant amyloid precursor protein (N2a/APP), a well-characterized cellular model of AD. The ELISA and Western-blot analysis revealed that xanthohumol (Xn) inhibited Aβ accumulation and APP processing, and that Xn ameliorated tau hyperphosphorylation via PP2A, GSK3β pathways in N2a/APP cells. The amelioration of tau hyperphosphorylation by Xn was also validated on HEK293/Tau cells, another cell line with tau hyperphosphorylation. Proteomic analysis (2D-DIGE-coupled MS) revealed a total of 30 differentially expressed lysate proteins in N2a/APP vs. wild-type (WT) N2a cells (N2a/WT), and a total of 21 differentially expressed proteins in lysates of N2a/APP cells in the presence or absence of Xn. Generally, these 51 differential proteins could be classified into seven main categories according to their functions, including: endoplasmic reticulum (ER) stress-associated proteins; oxidative stress-associated proteins; proteasome-associated proteins; ATPase and metabolism-associated proteins; cytoskeleton-associated proteins; molecular chaperones-associated proteins, and others. We used Western-blot analysis to validate Xn-associated changes of some key proteins in several biological/pathogenic processes. Taken together, we show that Xn reduces AD-related changes in stably transfected N2a/APP cells. The underlying mechanisms involve modulation of multiple pathogenic pathways, including those involved in ER stress, oxidative stress, proteasome molecular systems, and the neuronal cytoskeleton. These results suggest Xn may have potential for the treatment of AD and/or neuropathologically related neurodegenerative diseases.

The amyloid precursor protein and postnatal neurogenesis/neuroregeneration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Yanan; Tang, Bor Luen

2006-03-03

The amyloid precursor protein (APP) is the source of amyloid-beta (A{beta}) peptide, produced via its sequential cleavage {beta}- and {gamma}-secretases. Various biophysical forms of A{beta} (and the mutations of APP which results in their elevated levels) have been implicated in the etiology and early onset of Alzheimer's disease. APP's evolutionary conservation and the existence of APP-like isoforms (APLP1 and APLP2) which lack the A{beta} sequence, however, suggest that these might have important physiological functions that are unrelated to A{beta} production. Soluble N-terminal fragments of APP have been known to be neuroprotective, and the interaction of its cytoplasmic C-terminus with amore » myriad of proteins associates it with diverse processes such as axonal transport and transcriptional regulation. The notion for an essential postnatal function of APP has been demonstrated genetically, as mice deficient in both APP and APLP2 or all three APP isoforms exhibit early postnatal lethality and neuroanatomical abnormalities. Recent findings have also brought to light two possible functions of the APP family in Brain-regulation of neural progenitor cell proliferation and axonal outgrowth after injury. Interestingly, these two apparently related neurogenic/neuroregenerative functions of APP involve two separate domains of the molecule.« less

Substance P activates ADAM9 mRNA expression and induces α-secretase-mediated amyloid precursor protein cleavage.

PubMed

Marolda, R; Ciotti, M T; Matrone, C; Possenti, R; Calissano, P; Cavallaro, S; Severini, C

2012-04-01

Altered levels of Substance P (SP), a neuropeptide endowed with neuroprotective and anti-apoptotic properties, were found in brain areas and spinal fluid of Alzheimer's disease (AD) patients. One of the hallmarks of AD is the abnormal extracellular deposition of neurotoxic beta amyloid (Aβ) peptides, derived from the proteolytic processing of amyloid precursor protein (APP). In the present study, we confirmed, the neurotrophic action of SP in cultured rat cerebellar granule cells (CGCs) and investigated its effects on APP metabolism. Incubation with low (5 mM) potassium induced apoptotic cell death of CGCs and amyloidogenic processing of APP, whereas treatment with SP (200 nM) reverted these effects via NK1 receptors. The non-amyloidogenic effect of SP consisted of reduction of Aβ(1-42), increase of sAPPα and enhanced α-secretase activity, without a significant change in steady-state levels of cellular APP. The intracellular mechanisms whereby SP alters APP metabolism were further investigated by measuring mRNA and/or steady-state protein levels of key enzymes involved with α-, β- and γ-secretase activity. Among them, Adam9, both at the mRNA and protein level, was the only enzyme to be significantly down-regulated following the induction of apoptosis (K5) and up-regulated after SP treatment. In addition to its neuroprotective properties, this study shows that SP is able to stimulate non-amyloidogenic APP processing, thereby reducing the possibility of generation of toxic Aβ peptides in brain. Copyright © 2011 Elsevier Ltd. All rights reserved.

Acute phase proteins in healthy goats: establishment of reference intervals.

PubMed

Heller, Meera C; Johns, Jennifer L

2015-03-01

Acute inflammatory processes can trigger increased production of acute phase proteins (APPs) that can be useful biomarkers of inflammation. APPs are diverse and include proteins involved in coagulation, opsonization, iron regulation, and limitation of tissue injury. Haptoglobin, serum amyloid A, and alpha-1 acid glycoprotein have been proposed as useful APPs in goats. APPs can differ markedly by species, therefore species-specific reference intervals and studies are necessary. The objective of this study was to determine species-specific reference intervals for 4 APPs in goats. Haptoglobin, serum amyloid A, lipopolysaccharide binding protein, and alpha-1 acid glycoprotein were measured in in 54 clinically normal adult goats. APPs were measured using goat-specific commercial enzyme-linked immunosorbent assay kits. Results were analyzed by 1-way analysis of variance to compare sexes and breeding status. Reference Value Advisor was used to calculate reference limits according to the IFCC-CLSI guidelines. Only 1 APP was found to vary in healthy animals; serum haptoglobin was increased in lactating animals and decreased in pregnant does in their second trimester when compared with open, nonlactating does. No sex-based differences were seen for any of the APPs measured. We report normal reference intervals for 4 serum APPs that may be useful as disease markers. Haptoglobin should be interpreted with caution in animals with unknown pregnancy status. Further studies are needed to determine whether these APPs are useful biomarkers in goat disease states. © 2015 The Author(s).

Attenuating astrocyte activation accelerates plaque pathogenesis in APP/PS1 mice

PubMed Central

Kraft, Andrew W.; Hu, Xiaoyan; Yoon, Hyejin; Yan, Ping; Xiao, Qingli; Wang, Yan; Gil, So Chon; Brown, Jennifer; Wilhelmsson, Ulrika; Restivo, Jessica L.; Cirrito, John R.; Holtzman, David M.; Kim, Jungsu; Pekny, Milos; Lee, Jin-Moo

2013-01-01

The accumulation of aggregated amyloid-β (Aβ) in amyloid plaques is a neuropathological hallmark of Alzheimer's disease (AD). Reactive astrocytes are intimately associated with amyloid plaques; however, their role in AD pathogenesis is unclear. We deleted the genes encoding two intermediate filament proteins required for astrocyte activation—glial fibrillary acid protein (Gfap) and vimentin (Vim)—in transgenic mice expressing mutant human amyloid precursor protein and presenilin-1 (APP/PS1). The gene deletions increased amyloid plaque load: APP/PS1 Gfap−/−Vim−/− mice had twice the plaque load of APP/PS1 Gfap+/+Vim+/+ mice at 8 and 12 mo of age. APP expression and soluble and interstitial fluid Aβ levels were unchanged, suggesting that the deletions had no effect on APP processing or Aβ generation. Astrocyte morphology was markedly altered by the deletions: wild-type astrocytes had hypertrophied processes that surrounded and infiltrated plaques, whereas Gfap−/−Vim−/− astrocytes had little process hypertrophy and lacked contact with adjacent plaques. Moreover, Gfap and Vim gene deletion resulted in a marked increase in dystrophic neurites (2- to 3-fold higher than APP/PS1 Gfap+/+Vim+/+ mice), even after normalization for amyloid load. These results suggest that astrocyte activation limits plaque growth and attenuates plaque-related dystrophic neurites. These activities may require intimate contact between astrocyte and plaque.—Kraft, A. W., Hu, X., Yoon, H., Yan, P., Xiao, Q., Wang, Y., Gil, S. C., Brown, J., Wilhelmsson, U., Restivo, J. L., Cirrito, J. R., Holtzman, D. M., Kim, J., Pekny, M., Lee, J.-M. Attenuating astrocyte activation accelerates plaque pathogenesis in APP/PS1 mice. PMID:23038755

APP Function and Lipids: A Bidirectional Link

PubMed Central

Grimm, Marcus O. W.; Mett, Janine; Grimm, Heike S.; Hartmann, Tobias

2017-01-01

Extracellular neuritic plaques, composed of aggregated amyloid-β (Aβ) peptides, are one of the major histopathological hallmarks of Alzheimer’s disease (AD), a progressive, irreversible neurodegenerative disorder and the most common cause of dementia in the elderly. One of the most prominent risk factor for sporadic AD, carrying one or two aberrant copies of the apolipoprotein E (ApoE) ε4 alleles, closely links AD to lipids. Further, several lipid classes and fatty acids have been reported to be changed in the brain of AD-affected individuals. Interestingly, the observed lipid changes in the brain seem not only to be a consequence of the disease but also modulate Aβ generation. In line with these observations, protective lipids being able to decrease Aβ generation and also potential negative lipids in respect to AD were identified. Mechanistically, Aβ peptides are generated by sequential proteolytic processing of the amyloid precursor protein (APP) by β- and γ-secretase. The α-secretase appears to compete with β-secretase for the initial cleavage of APP, preventing Aβ production. All APP-cleaving secretases as well as APP are transmembrane proteins, further illustrating the impact of lipids on Aβ generation. Beside the pathological impact of Aβ, accumulating evidence suggests that Aβ and the APP intracellular domain (AICD) play an important role in regulating lipid homeostasis, either by direct effects or by affecting gene expression or protein stability of enzymes involved in the de novo synthesis of different lipid classes. This review summarizes the current literature addressing the complex bidirectional link between lipids and AD and APP processing including lipid alterations found in AD post mortem brains, lipids that alter APP processing and the physiological functions of Aβ and AICD in the regulation of several lipid metabolism pathways. PMID:28344547

Novel Roles of Amyloid-Beta Protein Precursor Metabolites in Fragile X Syndrome and Autism

PubMed Central

Westmark, Cara J.; Sokol, Deborah K.; Maloney, Bryan; Lahiri, Debomoy K.

2017-01-01

Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and is associated with up to 5% of autism cases. Several promising drugs are in preclinical testing for FXS; however, bench-to-bedside plans for the clinic are severely limited due to lack of validated biomarkers and outcome measures. Published work from our laboratories has demonstrated altered levels of amyloid-beta (Aβ) protein precursor (APP) and its metabolites in FXS and idiopathic autism. Westmark and colleagues have focused on β-secretase (amyloidogenic) processing and the accumulation of Aβ peptides in adult FXS models while Lahiri and Sokol have studied α-secretase (nonamyloidogenic or anabolic) processing and altered levels of sAPPα and Aβ in pediatric autism and FXS. Thus, our groups have hypothesized a pivotal role for these Alzheimer’s disease (AD)-related proteins in the neurodevelopmental disorders of FXS and autism. In this review, we discuss the contribution of APP metabolites to FXS and autism pathogenesis as well as the potential use of these metabolites as blood-based biomarkers and therapeutic targets. Our future focus is to identify key underlying mechanisms through which APP metabolites contribute to FXS and autism condition-to-disease pathology. Positive outcomes will support utilizing APP metabolites as blood-based biomarkers in clinical trials as well as testing drugs that modulate APP processing as potential disease therapeutics. Our studies to understand the role of APP metabolites in developmental conditions such as FXS and autism are a quantum leap for the neuroscience field, which has traditionally restricted any role of APP to AD and aging. PMID:27573877

beta. -Amyloid precursor protein of Alzheimer disease occurs as 110- to 135-kilodalton membrane-associated proteins in neural and nonneural tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selkoe, D.J.; Podlisny, M.B.; Joachim, C.L.

1988-10-01

Progressive cerebral deposition of extracellular filaments composed of the {beta}-amyloid protein ({beta}AP) is a constant feature of Alzheimer disease (AD). Since the gene on chromosome 21 encoding the {beta}AP precursor ({beta}APP) is not known to be altered in AD, transcriptional or posttranslational changes may underlie accelerated {beta}AP deposition. Using two antibodies to the predicted carboxyl terminus of {beta}APP, the authors have identified the native {beta}APP in brain and nonneural human tissues as a 110- to 135-kDa protein complex that is insoluble in buffer and found in various membrane-rich subcellular fractions. These proteins are relatively uniformly distributed in adult brain, abundantmore » in fetal brain, and detected in nonneural tissues that contain {beta}APP mRNA. Similarly sized proteins occur in rat, cow, and monkey brain and in cultured human HL-60 and HeLa cells; the precise patterns in the 110- to 135-kDa range are heterogeneous among various tissues and cell lines. They conclude that the highly conserved {beta}APP molecule occurs in mammalian tissues as a heterogeneous group of membrane-associated proteins of {approx} 120 kDa. Detection of the nonamyloidogenic carboxyl terminus within plaques suggests that proteolytic processing of the {beta}APP into insoluble filaments occurs locally in cortical regions that develop {beta}-amyloid deposits with age.« less

The Na+/H+ exchanger NHE6 modulates endosomal pH to control processing of amyloid precursor protein in a cell culture model of Alzheimer disease.

PubMed

Prasad, Hari; Rao, Rajini

2015-02-27

Early intervention may be key to safe and effective therapies in patients with Alzheimer disease. Endosomal dysfunction is an early step in neurodegeneration. Endosomes are a major site of production of Aβ peptide from the processing of amyloid precursor protein (APP) by clipping enzymes (β- and γ-secretases). The β-secretase enzyme BACE1 requires acidic lumen pH for optimum function, and acid pH promotes Aβ aggregation. The Na(+)/H(+) exchanger NHE6 provides a leak pathway for protons, limiting luminal acidification by proton pumps. Like APP, NHE6 expression was induced upon differentiation of SH-SY5Y neuroblastoma cells and localized to an endosomal compartment. Therefore, we investigated whether NHE6 expression altered APP localization and processing in a stably transfected cell culture model of human APP expression. We show that co-expression with NHE6 or treatment with the Na(+)/H(+) ionophore monensin shifted APP away from the trans-Golgi network into early and recycling endosomes in HEK293 cells. NHE6 alkalinized the endosomal lumen, similar to monensin, and significantly attenuated APP processing and Aβ secretion. In contrast, Aβ production was elevated upon NHE6 knockdown. We show that NHE6 transcript and protein levels are lowered in Alzheimer brains relative to control. These findings, taken together with emerging genetic evidence linking endosomal Na(+)/H(+) exchangers with Alzheimer disease, suggest that proton leak pathways may regulate Aβ generation and contribute to disease etiology. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

The Na+/H+ Exchanger NHE6 Modulates Endosomal pH to Control Processing of Amyloid Precursor Protein in a Cell Culture Model of Alzheimer Disease*

PubMed Central

Prasad, Hari; Rao, Rajini

2015-01-01

Early intervention may be key to safe and effective therapies in patients with Alzheimer disease. Endosomal dysfunction is an early step in neurodegeneration. Endosomes are a major site of production of Aβ peptide from the processing of amyloid precursor protein (APP) by clipping enzymes (β- and γ-secretases). The β-secretase enzyme BACE1 requires acidic lumen pH for optimum function, and acid pH promotes Aβ aggregation. The Na+/H+ exchanger NHE6 provides a leak pathway for protons, limiting luminal acidification by proton pumps. Like APP, NHE6 expression was induced upon differentiation of SH-SY5Y neuroblastoma cells and localized to an endosomal compartment. Therefore, we investigated whether NHE6 expression altered APP localization and processing in a stably transfected cell culture model of human APP expression. We show that co-expression with NHE6 or treatment with the Na+/H+ ionophore monensin shifted APP away from the trans-Golgi network into early and recycling endosomes in HEK293 cells. NHE6 alkalinized the endosomal lumen, similar to monensin, and significantly attenuated APP processing and Aβ secretion. In contrast, Aβ production was elevated upon NHE6 knockdown. We show that NHE6 transcript and protein levels are lowered in Alzheimer brains relative to control. These findings, taken together with emerging genetic evidence linking endosomal Na+/H+ exchangers with Alzheimer disease, suggest that proton leak pathways may regulate Aβ generation and contribute to disease etiology. PMID:25561733

The E2 Domains of APP and APLP1 Share a Conserved Mode of Dimerization

DOE Office of Scientific and Technical Information (OSTI.GOV)

S Lee; Y Xue; J Hulbert

2011-12-31

Amyloid precursor protein (APP) is genetically linked to Alzheimer's disease. APP is a type I membrane protein, and its oligomeric structure is potentially important because this property may play a role in its function or affect the processing of the precursor by the secretases to generate amyloid {beta}-peptide. Several independent studies have shown that APP can form dimers in the cell, but how it dimerizes remains controversial. At least three regions of the precursor, including a centrally located and conserved domain called E2, have been proposed to contribute to dimerization. Here we report two new crystal structures of E2, onemore » from APP and the other from APLP1, a mammalian APP homologue. Comparison with an earlier APP structure, which was determined in a different space group, shows that the E2 domains share a conserved and antiparallel mode of dimerization. Biophysical measurements in solution show that heparin binding induces E2 dimerization. The 2.1 {angstrom} resolution electron density map also reveals phosphate ions that are bound to the protein surface. Mutational analysis shows that protein residues interacting with the phosphate ions are also involved in heparin binding. The locations of two of these residues, Arg-369 and His-433, at the dimeric interface suggest a mechanism for heparin-induced protein dimerization.« less

APP mRNA splicing is upregulated in the brain of biglycan transgenic mice.

PubMed

Bjelik, Annamária; Pákáski, Magdolna; Bereczki, Erika; Gonda, Szilvia; Juhász, Anna; Rimanóczy, Agnes; Zana, Marianna; Janka, Zoltán; Sántha, Miklós; Kálmán, János

2007-01-01

Many of the risk factors for cerebrovascular disease and atherosclerosis also increase the risk of Alzheimer's disease, characterized by the cerebral deposition of beta-amyloid plaques resulting from the abnormal processing of the transmembrane amyloid precursor protein (APP). The initiating event of cholesterol-induced atherosclerosis is the retention and accumulation of atherogenic apolipoprotein B (apoB) together with low-density lipoproteins in the vascular intima. Biglycan, a member of the small leucine-rich protein family, was suspected of contributing to this process. The individual and combined overexpressions of biglycan and apoB-100 were therefore examined on the cortical APP mRNA levels of transgenic mice by means of semiquantitative PCR. As compared with the control littermates, transgenic biglycan mice had significantly increased cortical APP695 (122%) and APP770 (157%) mRNA levels, while the double transgenic (apoB(+/-)xbiglycan(+/-)) mice did not exhibit any changes. These results provide the first experimental evidence that the atherogenic risk factor biglycan alters APP splicing and may participate in the pathogenesis of both Alzheimer and vascular dementias.

Amyloid precursor protein regulates migration and metalloproteinase gene expression in prostate cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyazaki, Toshiaki; Ikeda, Kazuhiro; Horie-Inoue, Kuniko

Highlights: • APP knockdown reduced proliferation and migration of prostate cancer cells. • APP knockdown reduced expression of metalloproteinase and EMT-related genes. • APP overexpression promoted LNCaP cell migration. • APP overexpression increased expression of metalloproteinase and EMT-related genes. - Abstract: Amyloid precursor protein (APP) is a type I transmembrane protein, and one of its processed forms, β-amyloid, is considered to play a central role in the development of Alzheimer’s disease. We previously showed that APP is a primary androgen-responsive gene in prostate cancer and that its increased expression is correlated with poor prognosis for patients with prostate cancer. APPmore » has also been implicated in several human malignancies. Nevertheless, the mechanism underlying the pro-proliferative effects of APP on cancers is still not well-understood. In the present study, we explored a pathophysiological role for APP in prostate cancer cells using siRNA targeting APP (siAPP). The proliferation and migration of LNCaP and DU145 prostate cancer cells were significantly suppressed by siAPP. Differentially expressed genes in siAPP-treated cells compared to control siRNA-treated cells were identified by microarray analysis. Notably, several metalloproteinase genes, such as ADAM10 and ADAM17, and epithelial–mesenchymal transition (EMT)-related genes, such as VIM, and SNAI2, were downregulated in siAPP-treated cells as compared to control cells. The expression of these genes was upregulated in LNCaP cells stably expressing APP when compared with control cells. APP-overexpressing LNCaP cells exhibited enhanced migration in comparison to control cells. These results suggest that APP may contribute to the proliferation and migration of prostate cancer cells by modulating the expression of metalloproteinase and EMT-related genes.« less

Nuclear 82-kDa choline acetyltransferase decreases amyloidogenic APP metabolism in neurons from APP/PS1 transgenic mice.

PubMed

Albers, Shawn; Inthathirath, Fatima; Gill, Sandeep K; Winick-Ng, Warren; Jaworski, Ewa; Wong, Daisy Y L; Gros, Robert; Rylett, R Jane

2014-09-01

Alzheimer disease (AD) is associated with increased amyloidogenic processing of amyloid precursor protein (APP) to β-amyloid peptides (Aβ), cholinergic neuron loss with decreased choline acetyltransferase (ChAT) activity, and cognitive dysfunction. Both 69-kDa ChAT and 82-kDa ChAT are expressed in cholinergic neurons in human brain and spinal cord with 82-kDa ChAT localized predominantly to neuronal nuclei, suggesting potential alternative functional roles for the enzyme. By gene microarray analysis, we found that 82-kDa ChAT-expressing IMR32 neural cells have altered expression of genes involved in diverse cellular functions. Importantly, genes for several proteins that regulate APP processing along amyloidogenic and non-amyloidogenic pathways are differentially expressed in 82-kDa ChAT-containing cells. The predicted net effect based on observed changes in expression patterns of these genes would be decreased amyloidogenic APP processing with decreased Aβ production. This functional outcome was verified experimentally as a significant decrease in BACE1 protein levels and activity and a concomitant reduction in the release of endogenous Aβ1-42 from neurons cultured from brains of AD-model APP/PS1 transgenic mice. The expression of 82-kDa ChAT in neurons increased levels of GGA3, which is involved in trafficking BACE1 to lysosomes for degradation. shRNA-induced decreases in GGA3 protein levels attenuated the 82-kDa ChAT-mediated decreases in BACE1 protein and activity and Aβ1-42 release. Evidence that 82-kDa ChAT can enhance GGA3 gene expression is shown by enhanced GGA3 gene promoter activity in SN56 neural cells expressing this ChAT protein. These studies indicate a novel relationship between cholinergic neurons and APP processing, with 82-kDa ChAT acting as a negative regulator of Aβ production. This decreased formation of Aβ could result in protection for cholinergic neurons, as well as protection of other cells in the vicinity that are sensitive to increased levels of Aβ. Decreasing levels of 82-kDa ChAT due to increasing age or neurodegeneration could alter the balance towards increasing Aβ production, with this potentiating the decline in function of cholinergic neurons. Copyright © 2014 Elsevier Inc. All rights reserved.

Direct imaging of APP proteolysis in living cells.

PubMed

Parenti, Niccoló; Del Grosso, Ambra; Antoni, Claudia; Cecchini, Marco; Corradetti, Renato; Pavone, Francesco S; Calamai, Martino

2017-01-01

Alzheimer's disease is a multifactorial disorder caused by the interaction of genetic, epigenetic and environmental factors. The formation of cytotoxic oligomers consisting of A β peptide is widely accepted as being one of the main key events triggering the development of Alzheimer's disease. A β peptide production results from the specific proteolytic processing of the amyloid precursor protein (APP). Deciphering the factors governing the activity of the secretases responsible for the cleavage of APP is still a critical issue. Kits available commercially measure the enzymatic activity of the secretases from cells lysates, in vitro . By contrast, we have developed a prototypal rapid bioassay that provides visible information on the proteolytic processing of APP directly in living cells. APP was fused to a monomeric variant of the green fluorescent protein and a monomeric variant of the red fluorescent protein at the C-terminal and N-terminal (mChAPPmGFP), respectively. Changes in the proteolytic processing rate in transfected human neuroblastoma and rat neuronal cells were imaged with confocal microscopy as changes in the red/green fluorescence intensity ratio. The significant decrease in the mean red/green ratio observed in cells over-expressing the β -secretase BACE1, or the α -secretase ADAM10, fused to a monomeric blue fluorescent protein confirms that the proteolytic site is still accessible. Specific siRNA was used to evaluate the contribution of endogenous BACE1. Interestingly, we found that the degree of proteolytic processing of APP is not completely homogeneous within the same single cell, and that there is a high degree of variability between cells of the same type. We were also able to follow with a fluorescence spectrometer the changes in the red emission intensity of the extracellular medium when BACE1 was overexpressed. This represents a complementary approach to fluorescence microscopy for rapidly detecting changes in the proteolytic processing of APP in real time. In order to allow the discrimination between the α - and the β -secretase activity, we have created a variant of mChAPPmGFP with a mutation that inhibits the α -secretase cleavage without perturbing the β -secretase processing. Moreover, we obtained a quantitatively robust estimate of the changes in the red/green ratio for the above conditions by using a flow cytometer able to simultaneously excite and measure the red and green fluorescence. Our novel approach lay the foundation for a bioassay suitable to study the effect of drugs or particular conditions, to investigate in an unbiased way the the proteolytic processing of APP in single living cells in order, and to elucidate the causes of the variability and the factors driving the processing of APP.

Distinct amyloid precursor protein processing machineries of the olfactory system.

PubMed

Kim, Jae Yeon; Rasheed, Ameer; Yoo, Seung-Jun; Kim, So Yeun; Cho, Bongki; Son, Gowoon; Yu, Seong-Woon; Chang, Keun-A; Suh, Yoo-Hun; Moon, Cheil

2018-01-01

Processing of amyloid precursor protein (APP) occurs through sequential cleavages first by β-secretase and then by the γ-secretase complex. However, abnormal processing of APP leads to excessive production of β-amyloid (Aβ) in the central nervous system (CNS), an event which is regarded as a primary cause of Alzheimer's disease (AD). In particular, gene mutations of the γ-secretase complex-which contains presenilin 1 or 2 as the catalytic core-could trigger marked Aβ accumulation. Olfactory dysfunction usually occurs before the onset of typical AD-related symptoms (eg, memory loss or muscle retardation), suggesting that the olfactory system may be one of the most vulnerable regions to AD. To date however, little is known about why the olfactory system is affected so early by AD prior to other regions. Thus, we examined the distribution of secretases and levels of APP processing in the olfactory system under either healthy or pathological conditions. Here, we show that the olfactory system has distinct APP processing machineries. In particular, we identified higher expressions levels and activity of γ-secretase in the olfactory epithelium (OE) than other regions of the brain. Moreover, APP c-terminal fragments (CTF) are markedly detected. During AD progression, we note increased expression of presenilin2 of γ-secretases in the OE, not in the OB, and show that neurotoxic Aβ*56 accumulates more quickly in the OE. Taken together, these results suggest that the olfactory system has distinct APP processing machineries under healthy and pathological conditions. This finding may provide a crucial understanding of the unique APP-processing mechanisms in the olfactory system, and further highlights the correlation between olfactory deficits and AD symptoms. Copyright © 2017 Elsevier Inc. All rights reserved.

Optimal processing for gel electrophoresis images: Applying Monte Carlo Tree Search in GelApp.

PubMed

Nguyen, Phi-Vu; Ghezal, Ali; Hsueh, Ya-Chih; Boudier, Thomas; Gan, Samuel Ken-En; Lee, Hwee Kuan

2016-08-01

In biomedical research, gel band size estimation in electrophoresis analysis is a routine process. To facilitate and automate this process, numerous software have been released, notably the GelApp mobile app. However, the band detection accuracy is limited due to a band detection algorithm that cannot adapt to the variations in input images. To address this, we used the Monte Carlo Tree Search with Upper Confidence Bound (MCTS-UCB) method to efficiently search for optimal image processing pipelines for the band detection task, thereby improving the segmentation algorithm. Incorporating this into GelApp, we report a significant enhancement of gel band detection accuracy by 55.9 ± 2.0% for protein polyacrylamide gels, and 35.9 ± 2.5% for DNA SYBR green agarose gels. This implementation is a proof-of-concept in demonstrating MCTS-UCB as a strategy to optimize general image segmentation. The improved version of GelApp-GelApp 2.0-is freely available on both Google Play Store (for Android platform), and Apple App Store (for iOS platform). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of the amyloid precursor protein role in neuritogenesis reveals a biphasic SH-SY5Y neuronal cell differentiation model.

PubMed

da Rocha, Joana Fernandes; da Cruz e Silva, Odete A B; Vieira, Sandra Isabel

2015-07-01

The existence of an intrinsic programme controlling neuritogenesis and activated during early neuronal differentiation and regeneration stages is well established. However, the identity and role of each molecular player and event, as well as how such a programme is modified by environmental signals, remain a focus of research. The amyloid precursor protein (APP) is a neuromodulator of the developing and mature nervous system, although in a highly complex manner which is far from clear. To study APP-induced neuritogenesis, the retinoic acid (RA)-induced SH-SY5Y cell differentiation model was first minutely characterized in terms of RA dose, morphological outputs and relevant biochemical markers. The findings reported here unveiled two differentiation phases for the 10 μM RA dose: 1-4 (4 days excluded) and 4-8 days, clearly defined by fold increases in the ratio between APP and acetylated Tubulin. Moreover, we describe, for the first time, a unique peak of secreted APP (sAPP)/APP ratio in the first phase. Subsequent APP and sAPP modulations confirmed that a high sAPP/APP ratio potentiates the elongation of smaller processes at the earlier neuritogenic phase. This sAPP/APP ratio drops in the second phase, as holoAPP levels increase to assist the maintenance of the longer neurites, potentially via their stabilization. © 2015 International Society for Neurochemistry.

Amyloid precursor protein interaction network in human testis: sentinel proteins for male reproduction.

PubMed

Silva, Joana Vieira; Yoon, Sooyeon; Domingues, Sara; Guimarães, Sofia; Goltsev, Alexander V; da Cruz E Silva, Edgar Figueiredo; Mendes, José Fernando F; da Cruz E Silva, Odete Abreu Beirão; Fardilha, Margarida

2015-01-16

Amyloid precursor protein (APP) is widely recognized for playing a central role in Alzheimer's disease pathogenesis. Although APP is expressed in several tissues outside the human central nervous system, the functions of APP and its family members in other tissues are still poorly understood. APP is involved in several biological functions which might be potentially important for male fertility, such as cell adhesion, cell motility, signaling, and apoptosis. Furthermore, APP superfamily members are known to be associated with fertility. Knowledge on the protein networks of APP in human testis and spermatozoa will shed light on the function of APP in the male reproductive system. We performed a Yeast Two-Hybrid screen and a database search to study the interaction network of APP in human testis and sperm. To gain insights into the role of APP superfamily members in fertility, the study was extended to APP-like protein 2 (APLP2). We analyzed several topological properties of the APP interaction network and the biological and physiological properties of the proteins in the APP interaction network were also specified by gene ontologyand pathways analyses. We classified significant features related to the human male reproduction for the APP interacting proteins and identified modules of proteins with similar functional roles which may show cooperative behavior for male fertility. The present work provides the first report on the APP interactome in human testis. Our approach allowed the identification of novel interactions and recognition of key APP interacting proteins for male reproduction, particularly in sperm-oocyte interaction.

Expression of APP pathway mRNAs and proteins in Alzheimer's disease.

PubMed

Matsui, Toshifumi; Ingelsson, Martin; Fukumoto, Hiroaki; Ramasamy, Karunya; Kowa, Hisatomo; Frosch, Matthew P; Irizarry, Michael C; Hyman, Bradley T

2007-08-03

In both trisomy 21 and rare cases of triplication of amyloid precursor protein (APP) Alzheimer's disease (AD) pathological changes are believed to be secondary to increased expression of APP. We hypothesized that sporadic AD may also be associated with changes in transcription of APP or its metabolic partners. To address this issue, temporal neocortex of 27 AD and 21 non-demented control brains was examined to assess mRNA levels of APP isoforms (total APP, APP containing the Kunitz protease inhibitor domain [APP-KPI] and APP770) and APP metabolic enzymatic partners (the APP cleaving enzymes beta-secretase [BACE] and presenilin-1 [PS-1], and putative clearance molecules, low-density lipoprotein receptor protein [LRP] and apolipoprotein E [apoE]). Furthermore, we evaluated how changes in APP at the mRNA level affect the amount of Tris buffer extractable APP protein and Abeta40 and 42 peptides in AD and control brains. As assessed by quantitative PCR, APP-KPI (p=0.007), APP770 (p=0.004), PS-1 (p=0.004), LRP (p=0.003), apoE (p=0.0002) and GFAP (p<0.0001) mRNA levels all increased in AD, and there was a shift from APP695 (a neuronal isoform) towards KPI containing isoforms that are present in glia as well. APP-KPI mRNA levels correlated with soluble APPalpha-KPI protein (sAPPalpha-KPI) levels measured by ELISA (tau=0.33, p=0.015 by Kendall's rank correlation); in turn, soluble APPalpha-KPI protein levels positively correlated with Tris-extractable, soluble Abeta40 (p=0.046) and 42 levels (p=0.007). The ratio of soluble APPalpha-KPI protein levels to total APP protein increased in AD, and also correlated with GFAP protein levels in AD. These results suggest that altered transcription of APP in AD is proportionately associated with Abeta peptide, may occur in the context of gliosis, and may contribute to Abeta deposition in sporadic AD.

Glycines from the APP GXXXG/GXXXA Transmembrane Motifs Promote Formation of Pathogenic Aβ Oligomers in Cells

PubMed Central

Decock, Marie; Stanga, Serena; Octave, Jean-Noël; Dewachter, Ilse; Smith, Steven O.; Constantinescu, Stefan N.; Kienlen-Campard, Pascal

2016-01-01

Alzheimer’s disease (AD) is the most common neurodegenerative disorder characterized by progressive cognitive decline leading to dementia. The amyloid precursor protein (APP) is a ubiquitous type I transmembrane (TM) protein sequentially processed to generate the β-amyloid peptide (Aβ), the major constituent of senile plaques that are typical AD lesions. There is a growing body of evidence that soluble Aβ oligomers correlate with clinical symptoms associated with the disease. The Aβ sequence begins in the extracellular juxtamembrane region of APP and includes roughly half of the TM domain. This region contains GXXXG and GXXXA motifs, which are critical for both TM protein interactions and fibrillogenic properties of peptides derived from TM α-helices. Glycine-to-leucine mutations of these motifs were previously shown to affect APP processing and Aβ production in cells. However, the detailed contribution of these motifs to APP dimerization, their relation to processing, and the conformational changes they can induce within Aβ species remains undefined. Here, we describe highly resistant Aβ42 oligomers that are produced in cellular membrane compartments. They are formed in cells by processing of the APP amyloidogenic C-terminal fragment (C99), or by direct expression of a peptide corresponding to Aβ42, but not to Aβ40. By a point-mutation approach, we demonstrate that glycine-to-leucine mutations in the G29XXXG33 and G38XXXA42 motifs dramatically affect the Aβ oligomerization process. G33 and G38 in these motifs are specifically involved in Aβ oligomerization; the G33L mutation strongly promotes oligomerization, while G38L blocks it with a dominant effect on G33 residue modification. Finally, we report that the secreted Aβ42 oligomers display pathological properties consistent with their suggested role in AD, but do not induce toxicity in survival assays with neuronal cells. Exposure of neurons to these Aβ42 oligomers dramatically affects neuronal differentiation and, consequently, neuronal network maturation. PMID:27242518

Pathway-Based Analysis of Genome-Wide siRNA Screens Reveals the Regulatory Landscape of App Processing

PubMed Central

Camargo, Luiz Miguel; Zhang, Xiaohua Douglas; Loerch, Patrick; Caceres, Ramon Miguel; Marine, Shane D.; Uva, Paolo; Ferrer, Marc; de Rinaldis, Emanuele; Stone, David J.; Majercak, John; Ray, William J.; Yi-An, Chen; Shearman, Mark S.; Mizuguchi, Kenji

2015-01-01

The progressive aggregation of Amyloid-β (Aβ) in the brain is a major trait of Alzheimer's Disease (AD). Aβ is produced as a result of proteolytic processing of the β-amyloid precursor protein (APP). Processing of APP is mediated by multiple enzymes, resulting in the production of distinct peptide products: the non-amyloidogenic peptide sAPPα and the amyloidogenic peptides sAPPβ, Aβ40, and Aβ42. Using a pathway-based approach, we analyzed a large-scale siRNA screen that measured the production of different APP proteolytic products. Our analysis identified many of the biological processes/pathways that are known to regulate APP processing and have been implicated in AD pathogenesis, as well as revealing novel regulatory mechanisms. Furthermore, we also demonstrate that some of these processes differentially regulate APP processing, with some mechanisms favouring production of certain peptide species over others. For example, synaptic transmission having a bias towards regulating Aβ40 production over Aβ42 as well as processes involved in insulin and pancreatic biology having a bias for sAPPβ production over sAPPα. In addition, some of the pathways identified as regulators of APP processing contain genes (CLU, BIN1, CR1, PICALM, TREM2, SORL1, MEF2C, DSG2, EPH1A) recently implicated with AD through genome wide association studies (GWAS) and associated meta-analysis. In addition, we provide supporting evidence and a deeper mechanistic understanding of the role of diabetes in AD. The identification of these processes/pathways, their differential impact on APP processing, and their relationships to each other, provide a comprehensive systems biology view of the “regulatory landscape” of APP. PMID:25723573

Cerebrospinal fluid Aβ42 levels and APP processing pathway genes in Parkinson's disease.

PubMed

Bekris, Lynn M; Tsuang, Debby W; Peskind, Elaine R; Yu, Chang E; Montine, Thomas J; Zhang, Jing; Zabetian, Cyrus P; Leverenz, James B

2015-06-01

Of recent interest is the finding that certain cerebrospinal fluid (CSF) biomarkers traditionally linked to Alzheimer's disease (AD), specifically amyloid beta protein (Aβ), are abnormal in PD CSF. The aim of this exploratory investigation was to determine whether genetic variation within the amyloid precursor protein (APP) processing pathway genes correlates with CSF Aβ42 levels in Parkinson's disease (PD). Parkinson's disease (n = 86) and control (n = 161) DNA were genotyped for 19 regulatory region tagging single-nucleotide polymorphisms (SNPs) within nine genes (APP, ADAM10, BACE1, BACE2, PSEN1, PSEN2, PEN2, NCSTN, and APH1B) involved in the cleavage of APP. The SNP genotypes were tested for their association with CSF biomarkers and PD risk while adjusting for age, sex, and APOE ɛ4 status. Significant correlation with CSF Aβ42 levels in PD was observed for two SNPs, (APP rs466448 and APH1B rs2068143). Conversely, significant correlation with CSF Aβ42 levels in controls was observed for three SNPs (APP rs214484, rs2040273, and PSEN1 rs362344). In addition, results of this exploratory investigation suggest that an APP SNP and an APH1B SNP are marginally associated with PD CSF Aβ42 levels in APOE ɛ4 noncarriers. Further hypotheses generated include that decreased CSF Aβ42 levels are in part driven by genetic variation in APP processing genes. Additional investigation into the relationship between these findings and clinical characteristics of PD, including cognitive impairment, compared with other neurodegenerative diseases, such as AD, are warranted. © 2015 International Parkinson and Movement Disorder Society. © 2015 International Parkinson and Movement Disorder Society.

Functional Roles of the Interaction of APP and Lipoprotein Receptors

PubMed Central

Pohlkamp, Theresa; Wasser, Catherine R.; Herz, Joachim

2017-01-01

The biological fates of the key initiator of Alzheimer’s disease (AD), the amyloid precursor protein (APP), and a family of lipoprotein receptors, the low-density lipoprotein (LDL) receptor-related proteins (LRPs) and their molecular roles in the neurodegenerative disease process are inseparably interwoven. Not only does APP bind tightly to the extracellular domains (ECDs) of several members of the LRP group, their intracellular portions are also connected through scaffolds like the one established by FE65 proteins and through interactions with adaptor proteins such as X11/Mint and Dab1. Moreover, the ECDs of APP and LRPs share common ligands, most notably Reelin, a regulator of neuronal migration during embryonic development and modulator of synaptic transmission in the adult brain, and Agrin, another signaling protein which is essential for the formation and maintenance of the neuromuscular junction (NMJ) and which likely also has critical, though at this time less well defined, roles for the regulation of central synapses. Furthermore, the major independent risk factors for AD, Apolipoprotein (Apo) E and ApoJ/Clusterin, are lipoprotein ligands for LRPs. Receptors and ligands mutually influence their intracellular trafficking and thereby the functions and abilities of neurons and the blood-brain-barrier to turn over and remove the pathological product of APP, the amyloid-β peptide. This article will review and summarize the molecular mechanisms that are shared by APP and LRPs and discuss their relative contributions to AD. PMID:28298885

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

PubMed

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.

Lovastatin inhibits amyloid precursor protein (APP) beta-cleavage through reduction of APP distribution in Lubrol WX extractable low density lipid rafts.

PubMed

Won, Je-Seong; Im, Yeong-Bin; Khan, Mushfiquddin; Contreras, Miguel; Singh, Avtar K; Singh, Inderjit

2008-05-01

Previous studies have described that statins (inhibitors of cholesterol and isoprenoid biosynthesis) inhibit the output of amyloid-beta (Abeta) in the animal model and thus decrease risk of Alzheimer's disease. However, their action mechanism(s) in Abeta precursor protein (APP) processing and Abeta generation is not fully understood. In this study, we report that lovastatin treatment reduced Abeta output in cultured hippocampal neurons as a result of reduced APP levels and beta-secretase activities in low density Lubrol WX (non-ionic detergent) extractable lipid rafts (LDLR). Rather than altering cholesterol levels in lipid raft fractions and thus disrupting lipid raft structure, lovastatin decreased Abeta generation through down-regulating geranylgeranyl-pyrophosphate dependent endocytosis pathway. The inhibition of APP endocytosis by treatment with lovastatin and reduction of APP levels in LDLR fractions by treatment with phenylarsine oxide (a general endocytosis inhibitor) support the involvement of APP endocytosis in APP distribution in LDLR fractions and subsequent APP beta-cleavage. Moreover, lovastatin-mediated down-regulation of endocytosis regulators, such as early endosomal antigen 1, dynamin-1, and phosphatidylinositol 3-kinase activity, indicates that lovastatin modulates APP endocytosis possibly through its pleiotropic effects on endocytic regulators. Collectively, these data report that lovastatin mediates inhibition of LDLR distribution and beta-cleavage of APP in a geranylgeranyl-pyrophosphate and endocytosis-dependent manner.

LOVASTATIN INHIBITS AMYLOID PRECURSOR PROTEIN (APP) β-CLEAVAGE THROUGH REDUCTION OF APP DISTRIBUTION IN LUBROL WX EXTRACTABLE LOW DENSITY LIPID RAFTS

PubMed Central

Won, Je-Seong; Im, Yeong-Bin; Khan, Mushfiquddin; Contreras, Miguel; Singh, Avtar K.; Singh, Inderjit

2009-01-01

Previous studies have described that statins (inhibitors of cholesterol and isoprenoid biosynthesis) inhibit the output of amyloid-β (Aβ) in the animal model and thus decrease risk of Alzheimer's disease. However, their action mechanism(s) in APP processing and Aβ generation is not fully understood. Here we report that lovastatin treatment reduced Aβ output in cultured hippocampal neurons as a result of reduced Aβ precursor protein (APP) levels and β-secretase activities in low density Lubrol WX (non-ionic detergent) extractable lipid rafts (LDLR). Rather than altering cholesterol levels in lipid raft fractions and thus disrupting lipid raft structure, lovastatin decreased Aβ generation through down-regulating geranylgeranyl-pyrophosphate (GGPP) dependent endocytosis pathway. The inhibition of APP endocytosis by treatment with lovastatin and reduction of APP levels in LDLR fractions by treatment with phenylarsine oxide (a general endocytosis inhibitor) support the involvement of APP endocytosis in APP distribution in LDLR fractions and subsequent APP β-cleavage. Moreover, lovastatin-mediated down-regulation of endocytosis regulators, such as EEA1, dynamin-I and phosphatidylinositol-3 kinase activity, indicates that lovastatin modulates APP endocytosis possibly through its pleiotropic effects on endocytic regulators. Collectively, these data report that lovastatin mediates inhibition of LDLR distribution and β-cleavage of APP in a GGPP and endocytosis dependent manner. PMID:18266936

LRP1 Modulates APP Intraneuronal Transport and Processing in Its Monomeric and Dimeric State

PubMed Central

Herr, Uta-Mareike; Strecker, Paul; Storck, Steffen E.; Thomas, Carolin; Rabiej, Verena; Junker, Anne; Schilling, Sandra; Schmidt, Nadine; Dowds, C. Marie; Eggert, Simone; Pietrzik, Claus U.; Kins, Stefan

2017-01-01

The low-density lipoprotein receptor-related protein 1, LRP1, interacts with APP and affects its processing. This is assumed to be mostly caused by the impact of LRP1 on APP endocytosis. More recently, also an interaction of APP and LRP1 early in the secretory pathway was reported whereat retention of LRP1 in the ER leads to decreased APP cell surface levels and in turn, to reduced Aβ secretion. Here, we extended the biochemical and immunocytochemical analyses by showing via live cell imaging analyses in primary neurons that LRP1 and APP are transported only partly in common (one third) but to a higher degree in distinct fast axonal transport vesicles. Interestingly, co-expression of LRP1 and APP caused a change of APP transport velocities, indicating that LRP1 recruits APP to a specific type of fast axonal transport vesicles. In contrast lowered levels of LRP1 facilitated APP transport. We further show that monomeric and dimeric APP exhibit similar transport characteristics and that both are affected by LRP1 in a similar way, by slowing down APP anterograde transport and increasing its endocytosis rate. In line with this, a knockout of LRP1 in CHO cells and in primary neurons caused an increase of monomeric and dimeric APP surface localization and in turn accelerated shedding by meprin β and ADAM10. Notably, a choroid plexus specific LRP1 knockout caused a much higher secretion of sAPP dimers into the cerebrospinal fluid compared to sAPP monomers. Together, our data show that LRP1 functions as a sorting receptor for APP, regulating its cell surface localization and thereby its processing by ADAM10 and meprin β, with the latter exhibiting a preference for APP in its dimeric state. PMID:28496400

Docosahexaenoic Acid Reduces Amyloid β Production via Multiple Pleiotropic Mechanisms*

PubMed Central

Grimm, Marcus O. W.; Kuchenbecker, Johanna; Grösgen, Sven; Burg, Verena K.; Hundsdörfer, Benjamin; Rothhaar, Tatjana L.; Friess, Petra; de Wilde, Martijn C.; Broersen, Laus M.; Penke, Botond; Péter, Mária; Vígh, László; Grimm, Heike S.; Hartmann, Tobias

2011-01-01

Alzheimer disease is characterized by accumulation of the β-amyloid peptide (Aβ) generated by β- and γ-secretase processing of the amyloid precursor protein (APP). The intake of the polyunsaturated fatty acid docosahexaenoic acid (DHA) has been associated with decreased amyloid deposition and a reduced risk in Alzheimer disease in several epidemiological trials; however, the exact underlying molecular mechanism remains to be elucidated. Here, we systematically investigate the effect of DHA on amyloidogenic and nonamyloidogenic APP processing and the potential cross-links to cholesterol metabolism in vivo and in vitro. DHA reduces amyloidogenic processing by decreasing β- and γ-secretase activity, whereas the expression and protein levels of BACE1 and presenilin1 remain unchanged. In addition, DHA increases protein stability of α-secretase resulting in increased nonamyloidogenic processing. Besides the known effect of DHA to decrease cholesterol de novo synthesis, we found cholesterol distribution in plasma membrane to be altered. In the presence of DHA, cholesterol shifts from raft to non-raft domains, and this is accompanied by a shift in γ-secretase activity and presenilin1 protein levels. Taken together, DHA directs amyloidogenic processing of APP toward nonamyloidogenic processing, effectively reducing Aβ release. DHA has a typical pleiotropic effect; DHA-mediated Aβ reduction is not the consequence of a single major mechanism but is the result of combined multiple effects. PMID:21324907

Cross-linking of cell surface amyloid precursor protein leads to increased β-amyloid peptide production in hippocampal neurons: implications for Alzheimer's disease.

PubMed

Lefort, Roger; Pozueta, Julio; Shelanski, Michael

2012-08-01

The accumulation of the β-amyloid peptide (Aβ) in Alzheimer's disease (AD) is thought to play a causative role in triggering synaptic dysfunction in neurons, leading to their eventual demise through apoptosis. Aβ is produced and secreted upon sequential cleavage of the amyloid precursor protein (APP) by β-secretases and γ-secretases. However, while Aβ levels have been shown to be increased in the brains of AD patients, little is known about how the cleavage of APP and the subsequent generation of Aβ is influenced, or whether the cleavage process changes over time. It has been proposed that Aβ can bind APP and promote amyloidogenic processing of APP, further enhancing Aβ production. Proof of this idea has remained elusive because a clear mechanism has not been identified, and the promiscuous nature of Aβ binding complicates the task of demonstrating the idea. To work around these problems, we used an antibody-mediated approach to bind and cross-link cell-surface APP in cultured rat primary hippocampal neurons. Here we show that cross-linking of APP is sufficient to raise the levels of Aβ in viable neurons with a concomitant increase in the levels of the β-secretase BACE1. This appears to occur as a result of a sorting defect that stems from the caspase-3-mediated inactivation of a key sorting adaptor protein, namely GGA3, which prevents the lysosomal degradation of BACE1. Together, our data suggest the occurrence of a positive pathogenic feedback loop involving Aβ and APP in affected neurons possibly allowing Aβ to spread to nearby healthy neurons.

Proteasome stress leads to APP axonal transport defects by promoting its amyloidogenic processing in lysosomes.

PubMed

Otero, María Gabriela; Fernandez Bessone, Ivan; Hallberg, Alan Earle; Cromberg, Lucas Eneas; De Rossi, María Cecilia; Saez, Trinidad M; Levi, Valeria; Almenar-Queralt, Angels; Falzone, Tomás Luis

2018-06-11

Alzheimer disease (AD) pathology includes the accumulation of poly-ubiquitylated (also known as poly-ubiquitinated) proteins and failures in proteasome-dependent degradation. Whereas the distribution of proteasomes and its role in synaptic function have been studied, whether proteasome activity regulates the axonal transport and metabolism of the amyloid precursor protein (APP), remains elusive. By using live imaging in primary hippocampal neurons, we showed that proteasome inhibition rapidly and severely impairs the axonal transport of APP. Fluorescence cross-correlation analyses and membrane internalization blockage experiments showed that plasma membrane APP does not contribute to transport defects. Moreover, by western blotting and double-color APP imaging, we demonstrated that proteasome inhibition precludes APP axonal transport by enhancing its endo-lysosomal delivery, where β-cleavage is induced. Taken together, we found that proteasomes control the distal transport of APP and can re-distribute Golgi-derived vesicles to the endo-lysosomal pathway. This crosstalk between proteasomes and lysosomes regulates the intracellular APP dynamics, and defects in proteasome activity can be considered a contributing factor that leads to abnormal APP metabolism in AD.This article has an associated First Person interview with the first author of the paper. © 2018. Published by The Company of Biologists Ltd.

Amyloid precursor protein expression is enhanced in human platelets from subjects with Alzheimer's disease and frontotemporal lobar degeneration: a real-time PCR study.

PubMed

Vignini, Arianna; Morganti, Stefano; Salvolini, Eleonora; Sartini, Davide; Luzzi, Simona; Fiorini, Rosamaria; Provinciali, Leandro; Di Primio, Roberto; Mazzanti, Laura; Emanuelli, Monica

2013-12-01

Frontotemporal lobar degeneration (FTLD) and Alzheimer's disease (AD) represent the most frequent causes of early-onset and late-onset degenerative dementia, respectively. A correct diagnosis entails the choice of appropriate therapies. In this view the present study aimed to identify biomarkers that could improve the differential diagnosis. We recently found an overexpression of platelet amyloid precursor protein (APP) in AD; furthermore, recent studies have suggested the presence of changes in APP processing in FTLD. In this context, we analyzed the mRNA expression level of Total APP (TOT) and APP containing a Kunitz-type serine protease inhibitor domain (KPI) in platelets obtained from AD patients, subjects with FTLD, and healthy subjects. In addition, we evaluated the correlation between platelet APP mRNA expression levels and cognitive impairment.Differential gene expression measurements revealed a significant up-regulation of APP TOT and APP KPI in both AD and FTLD patients compared to the controls (being AD/Controls: 1.67 for APP TOT and 1.47 for APP KPI; FTLD/Controls: 1.62 for APP TOT and 1.51 for APP KPI; p < 0.05), although it is interesting to note that in FTLD patients this expression did not correlate with the severity of cognitive impairment.This could be related to a reduced beta-amyloid (Aβ) formation, caused by an alteration of secretase enzymatic activity, even though a post-transcriptional regulation of APP mRNAs in FTLD cannot be excluded.

Amyloid precursor protein expression is enhanced in human platelets from subjects with Alzheimer's disease and Frontotemporal lobar degeneration: A Real-time PCR study.

PubMed

Vignini, Arianna; Morganti, Stefano; Salvolini, Eleonora; Sartini, Davide; Luzzi, Simona; Fiorini, Rosamaria; Provinciali, Leandro; Di Primio, Roberto; Mazzanti, Laura; Emanuelli, Monica

2013-10-26

Frontotemporal lobar degeneration (FTLD) and Alzheimer's disease (AD) represent the most frequent causes of early-onset and late-onset degenerative dementia, respectively. A correct diagnosis entails the choice of appropriate therapies. In this view the present study aimed to identify biomarkers that could improve the differential diagnosis. We recently found an overexpression of platelet amyloid precursor protein (APP) in AD; furthermore, recent studies have suggested the presence of changes in APP processing in FTLD. In this context, we analyzed the mRNA expression level of Total APP (TOT) and APP containing a Kunitz-type serine protease inhibitor domain (KPI) in platelets obtained from AD patients, subjects with FTLD, and healthy subjects. In addition, we evaluated the correlation between platelet APP mRNA expression levels and cognitive impairment. Differential gene expression measurements revealed a significant up-regulation of APP TOT and APP KPI in both AD and FTLD patients compared to the controls (being AD/Controls: 1.67 for APP TOT and 1.47 for APP KPI; FTLD/Controls: 1.62 for APP TOT and 1.51 for APP KPI; p<0.05) , although it is interesting to note that in FTLD patients this expression did not correlate with the severity of cognitive impairment. This could be related to a reduced beta-amyloid (Aβ) formation, caused by an alteration of secretase enzymatic activity, even though a post-transcriptional regulation of APP mRNAs in FTLD cannot be excluded. © 2013.

The Metalloprotease Meprin β Generates Amino Terminal-truncated Amyloid β Peptide Species*

PubMed Central

Bien, Jessica; Jefferson, Tamara; Čaušević, Mirsada; Jumpertz, Thorsten; Munter, Lisa; Multhaup, Gerd; Weggen, Sascha; Becker-Pauly, Christoph; Pietrzik, Claus U.

2012-01-01

The amyloid β (Aβ) peptide, which is abundantly found in the brains of patients suffering from Alzheimer disease, is central in the pathogenesis of this disease. Therefore, to understand the processing of the amyloid precursor protein (APP) is of critical importance. Recently, we demonstrated that the metalloprotease meprin β cleaves APP and liberates soluble N-terminal APP (N-APP) fragments. In this work, we present evidence that meprin β can also process APP in a manner reminiscent of β-secretase. We identified cleavage sites of meprin β in the amyloid β sequence of the wild type and Swedish mutant of APP at positions p1 and p2, thereby generating Aβ variants starting at the first or second amino acid residue. We observed even higher kinetic values for meprin β than BACE1 for both the wild type and the Swedish mutant APP form. This enzymatic activity of meprin β on APP and Aβ generation was also observed in the absence of BACE1/2 activity using a β-secretase inhibitor and BACE knock-out cells, indicating that meprin β acts independently of β-secretase. PMID:22879596

Lessons from a Rare Familial Dementia: Amyloid and Beyond

PubMed Central

Cantlon, Adam; Frigerio, Carlo Sala; Walsh, Dominic M.

2015-01-01

Here we review the similarities between a rare inherited disorder, familial British dementia (FBD), and the most common of all late-life neurological conditions, Alzheimer's diseases (AD). We describe the symptoms, pathology and genetics of FBD, the biology of the BRI2 protein and mouse models of FBD and familial Danish dementia. In particular, we focus on the evolving recognition of the importance of protein oligomers and aberrant processing of the amyloid β-protein precursor (APP) - themes that are common to both FBD and AD. The initial discovery that FBD is phenotypically similar to AD, but associated with the deposition of an amyloid peptide (ABri) distinct from the amyloid β-protein (Aβ) led many to assume that amyloid production alone is sufficient to initiate disease and that ABri is the molecular equivalent of Aβ. Parallel with work on Aβ, studies of ABri producing animal models and in vitro ABri toxicity experiments caused a revision of the amyloid hypothesis and a focus on soluble oligomers of Aβ and ABri. Contemporaneous other studies suggested that loss of the ABri precursor protein (BRI2) may underlie the cognitive deficits in FBD. In this regard it is important to note that BRI2 has been shown to interact with and regulate the processing of APP, and that mutant BRI2 leads to altered cleavage of APP. A synthesis of these results suggests that a “two-hit mechanism” better explains FBD than earlier toxic gain of function and toxic loss of function models. The lessons learned from the study of FBD imply that the molecular pathology of AD is also likely to involve both aberrant aggregation (in AD, Aβ) and altered APP processing. With regard to FBD, we propose that the C-terminal 11 amino acid of FBD-BRI2 interfere with both the normal function of BRI2 and promotes the production of cystine cross-linked toxic ABri oligomers. In this scenario, loss of BRI2 function leads to altered APP processing in as yet underappreciated ways. Given the similarities between FBD and AD it seems likely that study of the structure of ABri oligomers and FBD-induced changes in APP metabolites will further our understanding of AD. PMID:26405694

c-Abl links APP-BACE1 interaction promoting APP amyloidogenic processing in Niemann-Pick type C disease.

PubMed

Yáñez, M J; Belbin, O; Estrada, L D; Leal, N; Contreras, P S; Lleó, A; Burgos, P V; Zanlungo, S; Alvarez, A R

2016-11-01

Niemann-Pick type C (NPC) disease is characterized by lysosomal accumulation of cholesterol. Interestingly, NPC patients' brains also show increased levels of amyloid-β (Aβ) peptide, a key protein in Alzheimer's disease pathogenesis. We previously reported that the c-Abl tyrosine kinase is active in NPC neurons and in AD animal models and that Imatinib, a specific c-Abl inhibitor, decreased the amyloid burden in brains of the AD mouse model. Active c-Abl was shown to interact with the APP cytosolic domain, but the relevance of this interaction to APP processing has yet to be defined. In this work we show that c-Abl inhibition reduces APP amyloidogenic cleavage in NPC cells overexpressing APP. Indeed, we found that levels of the Aβ oligomers and the carboxy-terminal fragment βCTF were decreased when the cells were treated with Imatinib and upon shRNA-mediated c-Abl knockdown. Moreover, Imatinib decreased APP amyloidogenic processing in the brain of an NPC mouse model. In addition, we found decreased levels of βCTF in neuronal cultures from c-Abl null mice. We demonstrate that c-Abl directly interacts with APP, that c-Abl inhibition prevents this interaction, and that Tyr682 in the APP cytoplasmic tail is essential for this interaction. More importantly, we found that c-Abl inhibition by Imatinib significantly inhibits the interaction between APP and BACE1. We conclude that c-Abl activity facilitates the APP-BACE1 interaction, thereby promoting amyloidogenic processing of APP. Thus, inhibition of c-Abl could be a pharmacological target for preventing the injurious effects of increased Aβ levels in NPC disease. Copyright © 2016 Elsevier B.V. All rights reserved.

Spatial Segregation of γ-Secretase and Substrates in Distinct Membrane Domains*

PubMed Central

Vetrivel, Kulandaivelu S.; Cheng, Haipeng; Kim, Seong-Hun; Chen, Ying; Barnes, Natalie Y.; Parent, Ange‘le T.; Sisodia, Sangram S.; Thinakaran, Gopal

2005-01-01

γ-Secretase facilitates the regulated intramembrane proteolysis of select type I membrane proteins that play diverse physiological roles in multiple cell types and tissue. In this study, we used biochemical approaches to examine the distribution of amyloid precursor protein (APP) and several additional γ-secretase substrates in membrane microdomains. We report that APP C-terminal fragments (CTFs) and γ-secretase reside in Lubrol WX detergent-insoluble membranes (DIM) of cultured cells and adult mouse brain. APP CTFs that accumulate in cells lacking γ-secretase activity preferentially associate with DIM. Cholesterol depletion and magnetic im-munoisolation studies indicate recruitment of APP CTFs into cholesterol- and sphingolipid-rich lipid rafts, and co-residence of APP CTFs, PS1, and syntaxin 6 in DIM patches derived from the trans-Golgi network. Photoaffinity cross-linking studies provided evidence for the preponderance of active γ-secretase in lipid rafts of cultured cells and adult brain. Remarkably, unlike the case of APP, CTFs derived from Notch1, Jagged2, deleted in colorectal cancer (DCC), and N-cadherin remain largely detergent-soluble, indicative of their spatial segregation in non-raft domains. In embryonic brain, the majority of PS1 and nicastrin is present in Lubrol WX-soluble membranes, wherein the CTFs derived from APP, Notch1, DCC, and N-cadherin also reside. We suggest that γ-secretase residence in non-raft membranes facilitates proteolysis of diverse substrates during embryonic development but that the translocation of γ-secretase to lipid rafts in adults ensures processing of certain substrates, including APP CTFs, while limiting processing of other potential substrates. PMID:15886206

Spatial segregation of gamma-secretase and substrates in distinct membrane domains.

PubMed

Vetrivel, Kulandaivelu S; Cheng, Haipeng; Kim, Seong-Hun; Chen, Ying; Barnes, Natalie Y; Parent, Angèle T; Sisodia, Sangram S; Thinakaran, Gopal

2005-07-08

Gamma-secretase facilitates the regulated intramembrane proteolysis of select type I membrane proteins that play diverse physiological roles in multiple cell types and tissue. In this study, we used biochemical approaches to examine the distribution of amyloid precursor protein (APP) and several additional gamma-secretase substrates in membrane microdomains. We report that APP C-terminal fragments (CTFs) and gamma-secretase reside in Lubrol WX detergent-insoluble membranes (DIM) of cultured cells and adult mouse brain. APP CTFs that accumulate in cells lacking gamma-secretase activity preferentially associate with DIM. Cholesterol depletion and magnetic immunoisolation studies indicate recruitment of APP CTFs into cholesterol- and sphingolipid-rich lipid rafts, and co-residence of APP CTFs, PS1, and syntaxin 6 in DIM patches derived from the trans-Golgi network. Photoaffinity cross-linking studies provided evidence for the preponderance of active gamma-secretase in lipid rafts of cultured cells and adult brain. Remarkably, unlike the case of APP, CTFs derived from Notch1, Jagged2, deleted in colorectal cancer (DCC), and N-cadherin remain largely detergent-soluble, indicative of their spatial segregation in non-raft domains. In embryonic brain, the majority of PS1 and nicastrin is present in Lubrol WX-soluble membranes, wherein the CTFs derived from APP, Notch1, DCC, and N-cadherin also reside. We suggest that gamma-secretase residence in non-raft membranes facilitates proteolysis of diverse substrates during embryonic development but that the translocation of gamma-secretase to lipid rafts in adults ensures processing of certain substrates, including APP CTFs, while limiting processing of other potential substrates.

Manduca Contactin Regulates Amyloid Precursor Protein-Dependent Neuronal Migration

PubMed Central

Ramaker, Jenna M.; Swanson, Tracy L.

2016-01-01

Amyloid precursor protein (APP) was originally identified as the source of β-amyloid peptides that accumulate in Alzheimer's disease (AD), but it also has been implicated in the control of multiple aspects of neuronal motility. APP belongs to an evolutionarily conserved family of transmembrane proteins that can interact with a variety of adapter and signaling molecules. Recently, we showed that both APP and its insect ortholog [APPL (APP-Like)] directly bind the heterotrimeric G-protein Goα, supporting the model that APP can function as an unconventional Goα-coupled receptor. We also adapted a well characterized assay of neuronal migration in the hawkmoth, Manduca sexta, to show that APPL–Goα signaling restricts ectopic growth within the developing nervous system, analogous to the role postulated for APP family proteins in controlling migration within the mammalian cortex. Using this assay, we have now identified Manduca Contactin (MsContactin) as an endogenous ligand for APPL, consistent with previous work showing that Contactins interact with APP family proteins in other systems. Using antisense-based knockdown protocols and fusion proteins targeting both proteins, we have shown that MsContactin is selectively expressed by glial cells that ensheath the migratory neurons (expressing APPL), and that MsContactin–APPL interactions normally prevent inappropriate migration and outgrowth. These results provide new evidence that Contactins can function as authentic ligands for APP family proteins that regulate APP-dependent responses in the developing nervous system. They also support the model that misregulated Contactin–APP interactions might provoke aberrant activation of Goα and its effectors, thereby contributing to the neurodegenerative sequelae that typify AD. SIGNIFICANCE STATEMENT Members of the amyloid precursor protein (APP) family participate in many aspects of neuronal development, but the ligands that normally activate APP signaling have remained controversial. This research provides new evidence that members of the Contactin family function as authentic ligands for APP and its orthologs, and that this evolutionarily conserved class of membrane-attached proteins regulates key aspects of APP-dependent migration and outgrowth in the embryonic nervous system. By defining the normal role of Contactin–APP signaling during development, these studies also provide the framework for investigating how the misregulation of Contactin–APP interactions might contribute to neuronal dysfunction in the context of both normal aging and neurodegenerative conditions, including Alzheimer's disease. PMID:27535920

APP Processing Induced by Herpes Simplex Virus Type 1 (HSV-1) Yields Several APP Fragments in Human and Rat Neuronal Cells

PubMed Central

Civitelli, Livia; Argnani, Rafaela; Piacentini, Roberto; Ripoli, Cristian; Manservigi, Roberto; Grassi, Claudio; Garaci, Enrico; Palamara, Anna Teresa

2010-01-01

Lifelong latent infections of the trigeminal ganglion by the neurotropic herpes simplex virus type 1 (HSV-1) are characterized by periodic reactivation. During these episodes, newly produced virions may also reach the central nervous system (CNS), causing productive but generally asymptomatic infections. Epidemiological and experimental findings suggest that HSV-1 might contribute to the pathogenesis of Alzheimer's disease (AD). This multifactorial neurodegenerative disorder is related to an overproduction of amyloid beta (Aβ) and other neurotoxic peptides, which occurs during amyloidogenic endoproteolytic processing of the transmembrane amyloid precursor protein (APP). The aim of our study was to identify the effects of productive HSV-1 infection on APP processing in neuronal cells. We found that infection of SH-SY5Y human neuroblastoma cells and rat cortical neurons is followed by multiple cleavages of APP, which result in the intra- and/or extra-cellular accumulation of various neurotoxic species. These include: i) APP fragments (APP-Fs) of 35 and 45 kDa (APP-F35 and APP-F45) that comprise portions of Aβ; ii) N-terminal APP-Fs that are secreted; iii) intracellular C-terminal APP-Fs; and iv) Aβ1-40 and Aβ1-42. Western blot analysis of infected-cell lysates treated with formic acid suggests that APP-F35 may be an Aβ oligomer. The multiple cleavages of APP that occur in infected cells are produced in part by known components of the amyloidogenic APP processing pathway, i.e., host-cell β-secretase, γ-secretase, and caspase-3-like enzymes. These findings demonstrate that HSV-1 infection of neuronal cells can generate multiple APP fragments with well-documented neurotoxic potentials. It is tempting to speculate that intra- and extracellular accumulation of these species in the CNS resulting from repeated HSV-1 reactivation could, in the presence of other risk factors, play a co-factorial role in the development of AD. PMID:21085580

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

PubMed

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.

Specific Inhibition of β-Secretase Processing of the Alzheimer Disease Amyloid Precursor Protein.

PubMed

Ben Halima, Saoussen; Mishra, Sabyashachi; Raja, K Muruga Poopathi; Willem, Michael; Baici, Antonio; Simons, Kai; Brüstle, Oliver; Koch, Philipp; Haass, Christian; Caflisch, Amedeo; Rajendran, Lawrence

2016-03-08

Development of disease-modifying therapeutics is urgently needed for treating Alzheimer disease (AD). AD is characterized by toxic β-amyloid (Aβ) peptides produced by β- and γ-secretase-mediated cleavage of the amyloid precursor protein (APP). β-secretase inhibitors reduce Aβ levels, but mechanism-based side effects arise because they also inhibit β-cleavage of non-amyloid substrates like Neuregulin. We report that β-secretase has a higher affinity for Neuregulin than it does for APP. Kinetic studies demonstrate that the affinities and catalytic efficiencies of β-secretase are higher toward non-amyloid substrates than toward APP. We show that non-amyloid substrates are processed by β-secretase in an endocytosis-independent manner. Exploiting this compartmentalization of substrates, we specifically target the endosomal β-secretase by an endosomally targeted β-secretase inhibitor, which blocked cleavage of APP but not non-amyloid substrates in many cell systems, including induced pluripotent stem cell (iPSC)-derived neurons. β-secretase inhibitors can be designed to specifically inhibit the Alzheimer process, enhancing their potential as AD therapeutics without undesired side effects. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

LRP in amyloid-beta production and metabolism.

PubMed

Bu, Guojun; Cam, Judy; Zerbinatti, Celina

2006-11-01

Amyloid-beta peptide (Abeta) production and accumulation in the brain is a central event in the pathogenesis of Alzheimer's disease (AD). Recent studies have shown that apolipoprotein E (apoE) receptors, members of the low-density lipoprotein receptor (LDLR) family, modulate Abeta production as well as Abeta cellular uptake. Abeta is derived from proteolytic processing of the amyloid precursor protein (APP), which interacts with several members of the LDLR family. Studies from our laboratory have focused on two members of the LDLR family, the LDLR-related protein (LRP) and LRP1B. Our in vitro studies have shown that while LRP's rapid endocytosis facilitates APP endocytic trafficking and processing to Abeta, LRP1B's slow endocytosis inhibits these processes. In addition to modulating APP endocytic trafficking, LRP's rapid endocytosis also facilitates Abeta cellular uptake by binding to Abeta either directly or via LRP ligands such as apoE. Our in vivo studies using transgenic mice have shown that overexpression of LRP in central nervous system (CNS) neurons increases soluble brain Abeta and this increase correlates with deficits in memory. Together our studies demonstrate that members of the LDLR family modulate APP processing and Abeta metabolism by several independent mechanisms. Understanding the pathways that modulate brain Abeta metabolism may enable the rational design of molecular medicine to treat AD.

Lack of tau proteins rescues neuronal cell death and decreases amyloidogenic processing of APP in APP/PS1 mice.

PubMed

Leroy, Karelle; Ando, Kunie; Laporte, Vincent; Dedecker, Robert; Suain, Valérie; Authelet, Michèle; Héraud, Céline; Pierrot, Nathalie; Yilmaz, Zehra; Octave, Jean-Noël; Brion, Jean-Pierre

2012-12-01

Lack of tau expression has been reported to protect against excitotoxicity and to prevent memory deficits in mice expressing mutant amyloid precursor protein (APP) identified in familial Alzheimer disease. In APP mice, mutant presenilin 1 (PS1) enhances generation of Aβ42 and inhibits cell survival pathways. It is unknown whether the deficient phenotype induced by concomitant expression of mutant PS1 is rescued by absence of tau. In this study, we have analyzed the effect of tau deletion in mice expressing mutant APP and PS1. Although APP/PS1/tau(+/+) mice had a reduced survival, developed spatial memory deficits at 6 months and motor impairments at 12 months, these deficits were rescued in APP/PS1/tau(-/-) mice. Neuronal loss and synaptic loss in APP/PS1/tau(+/+) mice were rescued in the APP/PS1/tau(-/-) mice. The amyloid plaque burden was decreased by roughly 50% in the cortex and the spinal cord of the APP/PS1/tau(-/-) mice. The levels of soluble and insoluble Aβ40 and Aβ42, and the Aβ42/Aβ40 ratio were reduced in APP/PS1/tau(-/-) mice. Levels of phosphorylated APP, of β-C-terminal fragments (CTFs), and of β-secretase 1 (BACE1) were also reduced, suggesting that β-secretase cleavage of APP was reduced in APP/PS1/tau(-/-) mice. Our results indicate that tau deletion had a protective effect against amyloid induced toxicity even in the presence of mutant PS1 and reduced the production of Aβ. Copyright © 2012 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

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

PubMed

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.

γ-Secretase Modulators and APH1 Isoforms Modulate γ-Secretase Cleavage but Not Position of ε-Cleavage of the Amyloid Precursor Protein (APP).

PubMed

Lessard, Christian B; Cottrell, Barbara A; Maruyama, Hiroko; Suresh, Suraj; Golde, Todd E; Koo, Edward H

2015-01-01

The relative increase in Aβ42 peptides from familial Alzheimer disease (FAD) linked APP and PSEN mutations can be related to changes in both ε-cleavage site utilization and subsequent step-wise cleavage. Cleavage at the ε-site releases the amyloid precursor protein (APP) intracellular domain (AICD), and perturbations in the position of ε-cleavage are closely associated with changes in the profile of amyloid β-protein (Aβ) species that are produced and secreted. The mechanisms by which γ-secretase modulators (GSMs) or FAD mutations affect the various γ-secretase cleavages to alter the generation of Aβ peptides have not been fully elucidated. Recent studies suggested that GSMs do not modulate ε-cleavage of APP, but the data were derived principally from recombinant truncated epitope tagged APP substrate. Here, using full length APP from transfected cells, we investigated whether GSMs modify the ε-cleavage of APP under more native conditions. Our results confirmed the previous findings that ε-cleavage is insensitive to GSMs. In addition, fenofibrate, an inverse GSM (iGSM), did not alter the position or kinetics of ε-cleavage position in vitro. APH1A and APH1B, a subunit of the γ-secretase complex, also modulated Aβ42/Aβ40 ratio without any alterations in ε-cleavage, a result in contrast to what has been observed with PS1 and APP FAD mutations. Consequently, GSMs and APH1 appear to modulate γ-secretase activity and Aβ42 generation by altering processivity but not ε-cleavage site utilization.

Secreted Amyloid β-Proteins in a Cell Culture Model Include N-Terminally Extended Peptides That Impair Synaptic Plasticity

PubMed Central

2014-01-01

Evidence for a central role of amyloid β-protein (Aβ) in the genesis of Alzheimer’s disease (AD) has led to advanced human trials of Aβ-lowering agents. The “amyloid hypothesis” of AD postulates deleterious effects of small, soluble forms of Aβ on synaptic form and function. Because selectively targeting synaptotoxic forms of soluble Aβ could be therapeutically advantageous, it is important to understand the full range of soluble Aβ derivatives. We previously described a Chinese hamster ovary (CHO) cell line (7PA2 cells) that stably expresses mutant human amyloid precursor protein (APP). Here, we extend this work by purifying an sodium dodecyl sulfate (SDS)-stable, ∼8 kDa Aβ species from the 7PA2 medium. Mass spectrometry confirmed its identity as a noncovalently bonded Aβ40 homodimer that impaired hippocampal long-term potentiation (LTP) in vivo. We further report the detection of Aβ-containing fragments of APP in the 7PA2 medium that extend N-terminal from Asp1 of Aβ. These N-terminally extended Aβ-containing monomeric fragments are distinct from soluble Aβ oligomers formed from Aβ1-40/42 monomers and are bioactive synaptotoxins secreted by 7PA2 cells. Importantly, decreasing β-secretase processing of APP elevated these alternative synaptotoxic APP fragments. We conclude that certain synaptotoxic Aβ-containing species can arise from APP processing events N-terminal to the classical β-secretase cleavage site. PMID:24840308

Quantitative modelling of amyloidogenic processing and its influence by SORLA in Alzheimer's disease.

PubMed

Schmidt, Vanessa; Baum, Katharina; Lao, Angelyn; Rateitschak, Katja; Schmitz, Yvonne; Teichmann, Anke; Wiesner, Burkhard; Petersen, Claus Munck; Nykjaer, Anders; Wolf, Jana; Wolkenhauer, Olaf; Willnow, Thomas E

2012-01-04

The extent of proteolytic processing of the amyloid precursor protein (APP) into neurotoxic amyloid-β (Aβ) peptides is central to the pathology of Alzheimer's disease (AD). Accordingly, modifiers that increase Aβ production rates are risk factors in the sporadic form of AD. In a novel systems biology approach, we combined quantitative biochemical studies with mathematical modelling to establish a kinetic model of amyloidogenic processing, and to evaluate the influence by SORLA/SORL1, an inhibitor of APP processing and important genetic risk factor. Contrary to previous hypotheses, our studies demonstrate that secretases represent allosteric enzymes that require cooperativity by APP oligomerization for efficient processing. Cooperativity enables swift adaptive changes in secretase activity with even small alterations in APP concentration. We also show that SORLA prevents APP oligomerization both in cultured cells and in the brain in vivo, eliminating the preferred form of the substrate and causing secretases to switch to a less efficient non-allosteric mode of action. These data represent the first mathematical description of the contribution of genetic risk factors to AD substantiating the relevance of subtle changes in SORLA levels for amyloidogenic processing as proposed for patients carrying SORL1 risk alleles.

Quantitative modelling of amyloidogenic processing and its influence by SORLA in Alzheimer's disease

PubMed Central

Schmidt, Vanessa; Baum, Katharina; Lao, Angelyn; Rateitschak, Katja; Schmitz, Yvonne; Teichmann, Anke; Wiesner, Burkhard; Petersen, Claus Munck; Nykjaer, Anders; Wolf, Jana; Wolkenhauer, Olaf; Willnow, Thomas E

2012-01-01

The extent of proteolytic processing of the amyloid precursor protein (APP) into neurotoxic amyloid-β (Aβ) peptides is central to the pathology of Alzheimer's disease (AD). Accordingly, modifiers that increase Aβ production rates are risk factors in the sporadic form of AD. In a novel systems biology approach, we combined quantitative biochemical studies with mathematical modelling to establish a kinetic model of amyloidogenic processing, and to evaluate the influence by SORLA/SORL1, an inhibitor of APP processing and important genetic risk factor. Contrary to previous hypotheses, our studies demonstrate that secretases represent allosteric enzymes that require cooperativity by APP oligomerization for efficient processing. Cooperativity enables swift adaptive changes in secretase activity with even small alterations in APP concentration. We also show that SORLA prevents APP oligomerization both in cultured cells and in the brain in vivo, eliminating the preferred form of the substrate and causing secretases to switch to a less efficient non-allosteric mode of action. These data represent the first mathematical description of the contribution of genetic risk factors to AD substantiating the relevance of subtle changes in SORLA levels for amyloidogenic processing as proposed for patients carrying SORL1 risk alleles. PMID:21989385

GPR3 Stimulates Aβ Production via Interactions with APP and β-Arrestin2

PubMed Central

Nelson, Christopher D.; Sheng, Morgan

2013-01-01

The orphan G protein-coupled receptor (GPCR) GPR3 enhances the processing of Amyloid Precursor Protein (APP) to the neurotoxic beta-amyloid (Aβ) peptide via incompletely understood mechanisms. Through overexpression and shRNA knockdown experiments in HEK293 cells, we show that β-arrestin2 (βarr2), a GPCR-interacting scaffold protein reported to bind γ-secretase, is an essential factor for GPR3-stimulated Aβ production. For a panel of GPR3 receptor mutants, the degree of stimulation of Aβ production correlates with receptor-β-arrestin binding and receptor trafficking to endocytic vesicles. However, GPR3’s recruitment of βarr2 cannot be the sole explanation, because interaction with βarr2 is common to most GPCRs, whereas GPR3 is relatively unique among GPCRs in enhancing Aβ production. In addition to β-arrestin, APP is present in a complex with GPR3 and stimulation of Aβ production by GPR3 mutants correlates with their level of APP binding. Importantly, among a broader selection of GPCRs, only GPR3 and prostaglandin E receptor 2 subtype EP2 (PTGER2; another GPCR that increases Aβ production) interact with APP, and PTGER2 does so in an agonist-stimulated manner. These data indicate that a subset of GPCRs, including GPR3 and PTGER2, can associate with APP when internalized via βarr2, and thereby promote the cleavage of APP to generate Aβ. PMID:24069330

Autism, Alzheimer disease, and fragile X: APP, FMRP, and mGluR5 are molecular links.

PubMed

Sokol, D K; Maloney, B; Long, J M; Ray, B; Lahiri, D K

2011-04-12

The present review highlights an association between autism, Alzheimer disease (AD), and fragile X syndrome (FXS). We propose a conceptual framework involving the amyloid-β peptide (Aβ), Aβ precursor protein (APP), and fragile X mental retardation protein (FMRP) based on experimental evidence. The anabolic (growth-promoting) effect of the secreted α form of the amyloid-β precursor protein (sAPPα) may contribute to the state of brain overgrowth implicated in autism and FXS. Our previous report demonstrated that higher plasma sAPPα levels associate with more severe symptoms of autism, including aggression. This molecular effect could contribute to intellectual disability due to repression of cell-cell adhesion, promotion of dense, long, thin dendritic spines, and the potential for disorganized brain structure as a result of disrupted neurogenesis and migration. At the molecular level, APP and FMRP are linked via the metabotropic glutamate receptor 5 (mGluR5). Specifically, mGluR5 activation releases FMRP repression of APP mRNA translation and stimulates sAPP secretion. The relatively lower sAPPα level in AD may contribute to AD symptoms that significantly contrast with those of FXS and autism. Low sAPPα and production of insoluble Aβ would favor a degenerative process, with the brain atrophy seen in AD. Treatment with mGluR antagonists may help repress APP mRNA translation and reduce secretion of sAPP in FXS and perhaps autism.

Regulation of Synaptic Amyloid-β Generation through BACE1 Retrograde Transport in a Mouse Model of Alzheimer's Disease

PubMed Central

Ye, Xuan; Chang, Qing; Jeong, Yu Young; Cai, Huaibin; Kusnecov, Alexander

2017-01-01

Amyloid-β (Aβ) peptides play a key role in synaptic damage and memory deficits in the early pathogenesis of Alzheimer's disease (AD). Abnormal accumulation of Aβ at nerve terminals leads to synaptic pathology and ultimately to neurodegeneration. β-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) is the major neuronal β-secretase for Aβ generation. However, the mechanisms regulating BACE1 distribution in axons and β cleavage of APP at synapses remain largely unknown. Here, we reveal that dynein–Snapin-mediated retrograde transport regulates BACE1 trafficking in axons and APP processing at presynaptic terminals. BACE1 is predominantly accumulated within late endosomes at the synapses of AD-related mutant human APP (hAPP) transgenic (Tg) mice and patient brains. Defective retrograde transport by genetic ablation of snapin in mice recapitulates late endocytic retention of BACE1 and increased APP processing at presynaptic sites. Conversely, overexpressing Snapin facilitates BACE1 trafficking and reduces synaptic BACE1 accumulation by enhancing the removal of BACE1 from distal AD axons and presynaptic terminals. Moreover, elevated Snapin expression via stereotactic hippocampal injections of adeno-associated virus particles in mutant hAPP Tg mouse brains decreases synaptic Aβ levels and ameliorates synapse loss, thus rescuing cognitive impairments associated with hAPP mice. Altogether, our study provides new mechanistic insights into the complex regulation of BACE1 trafficking and presynaptic localization through Snapin-mediated dynein-driven retrograde axonal transport, thereby suggesting a potential approach of modulating Aβ levels and attenuating synaptic deficits in AD. SIGNIFICANCE STATEMENT β-Site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) trafficking and synaptic localization significantly influence its β secretase activity and amyloid-β (Aβ) production. In AD brains, BACE1 is accumulated within dystrophic neurites, which is thought to augment Aβ-induced synaptotoxicity by Aβ overproduction. However, it remains largely unknown whether axonal transport regulates synaptic APP processing. Here, we demonstrate that Snapin-mediated retrograde transport plays a critical role in removing BACE1 from presynaptic terminals toward the soma, thus reducing synaptic Aβ production. Adeno-associated virus–mediated Snapin overexpression in the hippocampus of mutant hAPP mice significantly decreases synaptic Aβ levels, attenuates synapse loss, and thus rescues cognitive deficits. Our study uncovers a new pathway that controls synaptic APP processing by enhancing axonal BACE1 trafficking, thereby advancing our fundamental knowledge critical for ameliorating Aβ-linked synaptic pathology. PMID:28159908

Tetrahydrohyperforin Inhibits the Proteolytic Processing of Amyloid Precursor Protein and Enhances Its Degradation by Atg5-Dependent Autophagy

PubMed Central

Muñoz, Vanessa C.; Yefi, Claudia P.; Bustamante, Hianara A.; Barraza, Rafael R.; Tapia-Rojas, Cheril; Otth, Carola; Barrera, María José; González, Carlos; Mardones, Gonzalo A.; Inestrosa, Nibaldo C.; Burgos, Patricia V.

2015-01-01

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) peptide. We have previously shown that the compound tetrahydrohyperforin (IDN5706) prevents accumulation of Aβ species in an in vivo model of AD, however the mechanism that explains this reduction is not well understood. We show herein that IDN5706 decreases the levels of ER degradation enhancer, mannosidase alpha-like 1 (EDEM1), a key chaperone related to endoplasmic-reticulum-associated degradation (ERAD). Moreover, we observed that low levels of EDEM1 correlated with a strong activation of autophagy, suggesting a crosstalk between these two pathways. We observed that IDN5706 perturbs the glycosylation and proteolytic processing of the amyloid precursor protein (APP), resulting in the accumulation of immature APP (iAPP) in the endoplasmic reticulum. To investigate the contribution of autophagy, we tested the effect of IDN5706 in Atg5-depleted cells. We found that depletion of Atg5 enhanced the accumulation of iAPP in response to IDN5706 by slowing down its degradation. Our findings reveal that IDN5706 promotes degradation of iAPP via the activation of Atg5-dependent autophagy, shedding light on the mechanism that may contribute to the reduction of Aβ production in vivo. PMID:26308941

Tetrahydrohyperforin Inhibits the Proteolytic Processing of Amyloid Precursor Protein and Enhances Its Degradation by Atg5-Dependent Autophagy.

PubMed

Cavieres, Viviana A; González, Alexis; Muñoz, Vanessa C; Yefi, Claudia P; Bustamante, Hianara A; Barraza, Rafael R; Tapia-Rojas, Cheril; Otth, Carola; Barrera, María José; González, Carlos; Mardones, Gonzalo A; Inestrosa, Nibaldo C; Burgos, Patricia V

2015-01-01

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) peptide. We have previously shown that the compound tetrahydrohyperforin (IDN5706) prevents accumulation of Aβ species in an in vivo model of AD, however the mechanism that explains this reduction is not well understood. We show herein that IDN5706 decreases the levels of ER degradation enhancer, mannosidase alpha-like 1 (EDEM1), a key chaperone related to endoplasmic-reticulum-associated degradation (ERAD). Moreover, we observed that low levels of EDEM1 correlated with a strong activation of autophagy, suggesting a crosstalk between these two pathways. We observed that IDN5706 perturbs the glycosylation and proteolytic processing of the amyloid precursor protein (APP), resulting in the accumulation of immature APP (iAPP) in the endoplasmic reticulum. To investigate the contribution of autophagy, we tested the effect of IDN5706 in Atg5-depleted cells. We found that depletion of Atg5 enhanced the accumulation of iAPP in response to IDN5706 by slowing down its degradation. Our findings reveal that IDN5706 promotes degradation of iAPP via the activation of Atg5-dependent autophagy, shedding light on the mechanism that may contribute to the reduction of Aβ production in vivo.

Autism, Alzheimer disease, and fragile X

PubMed Central

Sokol, D.K.; Maloney, B.; Long, J.M.; Ray, B.

2011-01-01

The present review highlights an association between autism, Alzheimer disease (AD), and fragile X syndrome (FXS). We propose a conceptual framework involving the amyloid-β peptide (Aβ), Aβ precursor protein (APP), and fragile X mental retardation protein (FMRP) based on experimental evidence. The anabolic (growth-promoting) effect of the secreted α form of the amyloid-β precursor protein (sAPPα) may contribute to the state of brain overgrowth implicated in autism and FXS. Our previous report demonstrated that higher plasma sAPPα levels associate with more severe symptoms of autism, including aggression. This molecular effect could contribute to intellectual disability due to repression of cell–cell adhesion, promotion of dense, long, thin dendritic spines, and the potential for disorganized brain structure as a result of disrupted neurogenesis and migration. At the molecular level, APP and FMRP are linked via the metabotropic glutamate receptor 5 (mGluR5). Specifically, mGluR5 activation releases FMRP repression of APP mRNA translation and stimulates sAPP secretion. The relatively lower sAPPα level in AD may contribute to AD symptoms that significantly contrast with those of FXS and autism. Low sAPPα and production of insoluble Aβ would favor a degenerative process, with the brain atrophy seen in AD. Treatment with mGluR antagonists may help repress APP mRNA translation and reduce secretion of sAPP in FXS and perhaps autism. PMID:21482951

Protein levels of ADAM10, BACE1, and PSEN1 in platelets and leukocytes of Alzheimer's disease patients.

PubMed

Bram, Jessyka Maria de França; Talib, Leda Leme; Joaquim, Helena Passarelli Giroud; Sarno, Tamires Alves; Gattaz, Wagner Farid; Forlenza, Orestes Vicente

2018-05-29

The clinical diagnosis of Alzheimer's disease (AD) is a probabilistic formulation that may lack accuracy particularly at early stages of the dementing process. Abnormalities in amyloid-beta precursor protein (APP) metabolism and in the level of APP secretases have been demonstrated in platelets, and to a lesser extent in leukocytes, of AD patients, with conflicting results. The aim of the present study was to compare the protein level of the APP secretases A-disintegrin and metalloprotease 10 (ADAM10), Beta-site APP-cleaving enzyme 1 (BACE1), and presenilin-1 (PSEN1) in platelets and leukocytes from 20 non-medicated older adults with AD and 20 healthy elders, and to determine the potential use of these biomarkers to discriminate cases of AD from controls. The protein levels of all APP secretases were significantly higher in platelets compared to leukocytes. We found statistically a significant decrease in ADAM10 (52.5%, p < 0.0001) and PSEN1 (32%, p = 0.02) in platelets from AD patients compared to controls, but not in leukocytes. Combining all three secretases to generate receiver-operating characteristic (ROC) curves, we found a good discriminatory effect (AD vs. controls) when using platelets (the area under the curve-AUC-0.90, sensitivity 88.9%, specificity 66.7%, p = 0.003), but not in leukocytes (AUC 0.65, sensitivity 77.8%, specificity 50.0%, p = 0.2). Our findings indicate that platelets represent a better biological matrix than leukocytes to address the peripheral level of APP secretases. In addition, combining the protein level of ADAM10, BACE1, and PSEN1 in platelets, yielded a good accuracy to discriminate AD from controls.

η-Secretase processing of APP inhibits neuronal activity in the hippocampus.

PubMed

Willem, Michael; Tahirovic, Sabina; Busche, Marc Aurel; Ovsepian, Saak V; Chafai, Magda; Kootar, Scherazad; Hornburg, Daniel; Evans, Lewis D B; Moore, Steven; Daria, Anna; Hampel, Heike; Müller, Veronika; Giudici, Camilla; Nuscher, Brigitte; Wenninger-Weinzierl, Andrea; Kremmer, Elisabeth; Heneka, Michael T; Thal, Dietmar R; Giedraitis, Vilmantas; Lannfelt, Lars; Müller, Ulrike; Livesey, Frederick J; Meissner, Felix; Herms, Jochen; Konnerth, Arthur; Marie, Hélène; Haass, Christian

2015-10-15

Alzheimer disease (AD) is characterized by the accumulation of amyloid plaques, which are predominantly composed of amyloid-β peptide. Two principal physiological pathways either prevent or promote amyloid-β generation from its precursor, β-amyloid precursor protein (APP), in a competitive manner. Although APP processing has been studied in great detail, unknown proteolytic events seem to hinder stoichiometric analyses of APP metabolism in vivo. Here we describe a new physiological APP processing pathway, which generates proteolytic fragments capable of inhibiting neuronal activity within the hippocampus. We identify higher molecular mass carboxy-terminal fragments (CTFs) of APP, termed CTF-η, in addition to the long-known CTF-α and CTF-β fragments generated by the α- and β-secretases ADAM10 (a disintegrin and metalloproteinase 10) and BACE1 (β-site APP cleaving enzyme 1), respectively. CTF-η generation is mediated in part by membrane-bound matrix metalloproteinases such as MT5-MMP, referred to as η-secretase activity. η-Secretase cleavage occurs primarily at amino acids 504-505 of APP695, releasing a truncated ectodomain. After shedding of this ectodomain, CTF-η is further processed by ADAM10 and BACE1 to release long and short Aη peptides (termed Aη-α and Aη-β). CTFs produced by η-secretase are enriched in dystrophic neurites in an AD mouse model and in human AD brains. Genetic and pharmacological inhibition of BACE1 activity results in robust accumulation of CTF-η and Aη-α. In mice treated with a potent BACE1 inhibitor, hippocampal long-term potentiation was reduced. Notably, when recombinant or synthetic Aη-α was applied on hippocampal slices ex vivo, long-term potentiation was lowered. Furthermore, in vivo single-cell two-photon calcium imaging showed that hippocampal neuronal activity was attenuated by Aη-α. These findings not only demonstrate a major functionally relevant APP processing pathway, but may also indicate potential translational relevance for therapeutic strategies targeting APP processing.

Development and use of the Cytoscape app GFD-Net for measuring semantic dissimilarity of gene networks

PubMed Central

Diaz-Montana, Juan J.; Diaz-Diaz, Norberto

2014-01-01

Gene networks are one of the main computational models used to study the interaction between different elements during biological processes being widely used to represent gene–gene, or protein–protein interaction complexes. We present GFD-Net, a Cytoscape app for visualizing and analyzing the functional dissimilarity of gene networks. PMID:25400907

Increased Alzheimer's disease-like pathology in the APP/ PS1ΔE9 mouse model lacking Nrf2 through modulation of autophagy.

PubMed

Joshi, Gururaj; Gan, Kok Ann; Johnson, Delinda A; Johnson, Jeffrey A

2015-02-01

The presence of senile plaques is one of the major pathologic hallmarks of the brain with Alzheimer's disease (AD). The plaques predominantly contain insoluble amyloid β-peptide, a cleavage product of the larger amyloid precursor protein (APP). Two enzymes, named β and γ secretase, generate the neurotoxic amyloid-β peptide from APP. Mature APP is also turned over endogenously by autophagy, more specifically by the endosomal-lysosomal pathway. A defective lysosomal system is known to be pathogenic in AD. Modulation of NF-E2 related factor 2 (Nrf2) has been shown in several neurodegenerative disorders, and Nrf2 has become a potential therapeutic target for various neurodegenerative disorders, including AD, Parkinson's disease, and amyotrophic lateral sclerosis. In the current study, we explored the effect of genetic ablation of Nrf2 on APP/Aβ processing and/or aggregation as well as changes in autophagic dysfunction in APP/PS1 mice. There was a significant increase in inflammatory response in APP/PS1 mice lacking Nrf2. This was accompanied by increased intracellular levels of APP, Aβ (1-42), and Aβ (1-40), without a change total full-length APP. There was a shift of APP and Aβ into the insoluble fraction, as well as increased poly-ubiquitin conjugated proteins in mice lacking Nrf2. APP/PS1-mediated autophagic dysfunction is also enhanced in Nrf2-deficient mice. Finally, neurons in the APP/PS1/Nrf2-/- mice had increased accumulation of multivesicular bodies, endosomes, and lysosomes. These outcomes provide a better understanding of the role of Nrf2 in modulating autophagy in an AD mouse model and may help design better Nrf2 targeted therapeutics that could be efficacious in the treatment of AD. Published by Elsevier Inc.

MicroRNA-153 Physiologically Inhibits Expression of Amyloid-β Precursor Protein in Cultured Human Fetal Brain Cells and Is Dysregulated in a Subset of Alzheimer Disease Patients*

PubMed Central

Long, Justin M.; Ray, Balmiki; Lahiri, Debomoy K.

2012-01-01

Regulation of amyloid-β (Aβ) precursor protein (APP) expression is complex. MicroRNAs (miRNAs) are expected to participate in the molecular network that controls this process. The composition of this network is, however, still undefined. Elucidating the complement of miRNAs that regulate APP expression should reveal novel drug targets capable of modulating Aβ production in AD. Here, we investigated the contribution of miR-153 to this regulatory network. A miR-153 target site within the APP 3′-untranslated region (3′-UTR) was predicted by several bioinformatic algorithms. We found that miR-153 significantly reduced reporter expression when co-transfected with an APP 3′-UTR reporter construct. Mutation of the predicted miR-153 target site eliminated this reporter response. miR-153 delivery in both HeLa cells and primary human fetal brain cultures significantly reduced APP expression. Delivery of a miR-153 antisense inhibitor to human fetal brain cultures significantly elevated APP expression. miR-153 delivery also reduced expression of the APP paralog APLP2. High functional redundancy between APP and APLP2 suggests that miR-153 may target biological pathways in which they both function. Interestingly, in a subset of human AD brain specimens with moderate AD pathology, miR-153 levels were reduced. This same subset also exhibited elevated APP levels relative to control specimens. Therefore, endogenous miR-153 inhibits expression of APP in human neurons by specifically interacting with the APP 3′-UTR. This regulatory interaction may have relevance to AD etiology, where low miR-153 levels may drive increased APP expression in a subset of AD patients. PMID:22733824

The Amyloid Precursor Protein (APP) Triplicated Gene Impairs Neuronal Precursor Differentiation and Neurite Development through Two Different Domains in the Ts65Dn Mouse Model for Down Syndrome*

PubMed Central

Trazzi, Stefania; Fuchs, Claudia; Valli, Emanuele; Perini, Giovanni; Bartesaghi, Renata; Ciani, Elisabetta

2013-01-01

Intellectual disability in Down syndrome (DS) appears to be related to severe proliferation impairment during brain development. Recent evidence shows that it is not only cellular proliferation that is heavily compromised in DS, but also cell fate specification and dendritic maturation. The amyloid precursor protein (APP), a gene that is triplicated in DS, plays a key role in normal brain development by influencing neural precursor cell proliferation, cell fate specification, and neuronal maturation. APP influences these processes via two separate domains, the APP intracellular domain (AICD) and the soluble secreted APP. We recently found that the proliferation impairment of neuronal precursors (NPCs) from the Ts65Dn mouse model for DS was caused by derangement of the Shh pathway due to overexpression of patched1(Ptch1), its inhibitory regulator. Ptch1 overexpression was related to increased levels within the APP/AICD system. The overall goal of this study was to determine whether APP contributes to neurogenesis impairment in DS by influencing in addition to proliferation, cell fate specification, and neurite development. We found that normalization of APP expression restored the reduced neuronogenesis, the increased astrogliogenesis, and the reduced neurite length of trisomic NPCs, indicating that APP overexpression underpins all aspects of neurogenesis impairment. Moreover, we found that two different domains of APP impair neuronal differentiation and maturation in trisomic NPCs. The APP/AICD system regulates neuronogenesis and neurite length through the Shh pathway, whereas the APP/secreted AP system promotes astrogliogenesis through an IL-6-associated signaling cascade. These results provide novel insight into the mechanisms underlying brain development alterations in DS. PMID:23740250

Association of gamma-secretase with lipid rafts in post-Golgi and endosome membranes.

PubMed

Vetrivel, Kulandaivelu S; Cheng, Haipeng; Lin, William; Sakurai, Takashi; Li, Tong; Nukina, Nobuyuki; Wong, Philip C; Xu, Huaxi; Thinakaran, Gopal

2004-10-22

Alzheimer's disease-associated beta-amyloid peptides (Abeta) are generated by the sequential proteolytic processing of amyloid precursor protein (APP) by beta- and gamma-secretases. There is growing evidence that cholesterol- and sphingolipid-rich membrane microdomains are involved in regulating trafficking and processing of APP. BACE1, the major beta-secretase in neurons is a palmitoylated transmembrane protein that resides in lipid rafts. A subset of APP is subject to amyloidogenic processing by BACE1 in lipid rafts, and this process depends on the integrity of lipid rafts. Here we describe the association of all four components of the gamma-secretase complex, namely presenilin 1 (PS1)-derived fragments, mature nicastrin, APH-1, and PEN-2, with cholesterol-rich detergent insoluble membrane (DIM) domains of non-neuronal cells and neurons that fulfill the criteria of lipid rafts. In PS1(-/-)/PS2(-/-) and NCT(-/-) fibroblasts, gamma-secretase components that still remain fail to become detergent-resistant, suggesting that raft association requires gamma-secretase complex assembly. Biochemical evidence shows that subunits of the gamma-secretase complex and three TGN/endosome-resident SNAREs cofractionate in sucrose density gradients, and show similar solubility or insolubility characteristics in distinct non-ionic and zwitterionic detergents, indicative of their co-residence in membrane microdomains with similar protein-lipid composition. This notion is confirmed using magnetic immunoisolation of PS1- or syntaxin 6-positive membrane patches from a mixture of membranes with similar buoyant densities following Lubrol WX extraction or sonication, and gradient centrifugation. These findings are consistent with the localization of gamma-secretase in lipid raft microdomains of post-Golgi and endosomes, organelles previously implicated in amyloidogenic processing of APP.

Association of γ-Secretase with Lipid Rafts in Post-Golgi and Endosome Membranes*

PubMed Central

Vetrivel, Kulandaivelu S.; Cheng, Haipeng; Lin, William; Sakurai, Takashi; Li, Tong; Nukina, Nobuyuki; Wong, Philip C.; Xu, Huaxi; Thinakaran, Gopal

2005-01-01

Alzheimer’s disease-associated β-amyloid peptides (Aβ) are generated by the sequential proteolytic processing of amyloid precursor protein (APP) by β- and γ-secretases. There is growing evidence that cholesterol- and sphingolipid-rich membrane microdomains are involved in regulating trafficking and processing of APP. BACE1, the major γ-secretase in neurons is a palmi-toylated transmembrane protein that resides in lipid rafts. A subset of APP is subject to amyloidogenic processing by BACE1 in lipid rafts, and this process depends on the integrity of lipid rafts. Here we describe the association of all four components of the γ-secretase complex, namely presenilin 1 (PS1)-derived fragments, mature nicastrin, APH-1, and PEN-2, with cholesterol-rich detergent insoluble membrane (DIM) domains of non-neuronal cells and neurons that fulfill the criteria of lipid rafts. In PS1−/−/PS2−/− and NCT−/− fibroblasts, γ-secretase components that still remain fail to become detergent-resistant, suggesting that raft association requires γ-secretase complex assembly. Biochemical evidence shows that subunits of the γ-secretase complex and three TGN/endosome-resident SNAREs cofractionate in sucrose density gradients, and show similar solubility or insolubility characteristics in distinct non-ionic and zwitterionic detergents, indicative of their co-residence in membrane microdomains with similar protein-lipid composition. This notion is confirmed using magnetic immunoisolation of PS1- or syntaxin 6-positive membrane patches from a mixture of membranes with similar buoyant densities following Lubrol WX extraction or sonication, and gradient centrifugation. These findings are consistent with the localization of γ-secretase in lipid raft microdomains of post-Golgi and endosomes, organelles previously implicated in amyloidogenic processing of APP. PMID:15322084

Optimal combinations of acute phase proteins for detecting infectious disease in pigs.

PubMed

Heegaard, Peter M H; Stockmarr, Anders; Piñeiro, Matilde; Carpintero, Rakel; Lampreave, Fermin; Campbell, Fiona M; Eckersall, P David; Toussaint, Mathilda J M; Gruys, Erik; Sorensen, Nanna Skall

2011-03-17

The acute phase protein (APP) response is an early systemic sign of disease, detected as substantial changes in APP serum concentrations and most disease states involving inflammatory reactions give rise to APP responses. To obtain a detailed picture of the general utility of porcine APPs to detect any disease with an inflammatory component seven porcine APPs were analysed in serum sampled at regular intervals in six different experimental challenge groups of pigs, including three bacterial (Actinobacillus pleuropneumoniae, Streptococcus suis, Mycoplasma hyosynoviae), one parasitic (Toxoplasma gondii) and one viral (porcine respiratory and reproductive syndrome virus) infection and one aseptic inflammation. Immunochemical analyses of seven APPs, four positive (C-reactive protein (CRP), haptoglobin (Hp), pig major acute phase protein (pigMAP) and serum amyloid A (SAA)) and three negative (albumin, transthyretin, and apolipoprotein A1 (apoA1)) were performed in the more than 400 serum samples constituting the serum panel. This was followed by advanced statistical treatment of the data using a multi-step procedure which included defining cut-off values and calculating detection probabilities for single APPs and for APP combinations. Combinations of APPs allowed the detection of disease more sensitively than any individual APP and the best three-protein combinations were CRP, apoA1, pigMAP and CRP, apoA1, Hp, respectively, closely followed by the two-protein combinations CRP, pigMAP and apoA1, pigMAP, respectively. For the practical use of such combinations, methodology is described for establishing individual APP threshold values, above which, for any APP in the combination, ongoing infection/inflammation is indicated.

How the formation of amyloid plaques and neurofibrillary tangles may be related: a mathematical modelling study

NASA Astrophysics Data System (ADS)

Kuznetsov, I. A.; Kuznetsov, A. V.

2018-02-01

We develop a mathematical model that enables us to investigate possible mechanisms by which two primary markers of Alzheimer's disease (AD), extracellular amyloid plaques and intracellular tangles, may be related. Our model investigates the possibility that the decay of anterograde axonal transport of amyloid precursor protein (APP), caused by toxic tau aggregates, leads to decreased APP transport towards the synapse and APP accumulation in the soma. The developed model thus couples three processes: (i) slow axonal transport of tau, (ii) tau misfolding and agglomeration, which we simulated by using the Finke-Watzky model and (iii) fast axonal transport of APP. Because the timescale for tau agglomeration is much larger than that for tau transport, we suggest using the quasi-steady-state approximation for formulating and solving the governing equations for these three processes. Our results suggest that misfolded tau most likely accumulates in the beginning of the axon. The analysis of APP transport suggests that APP will also likely accumulate in the beginning of the axon, causing an increased APP concentration in this region, which could be interpreted as a `traffic jam'. The APP flux towards the synapse is significantly reduced by tau misfolding, but not due to the APP traffic jam, which can be viewed as a symptom, but rather due to the reduced affinity of kinesin-1 motors to APP-transporting vesicles.

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

PubMed

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.

Loss of Function of ATXN1 Increases Amyloid β-Protein Levels by Potentiating β-Secretase Processing of β-Amyloid Precursor Protein*

PubMed Central

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

2010-01-01

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 ∼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 Aβ, the proteolytic product of β-amyloid precursor protein (APP), is the primary AD pathological event. In this study, we ask whether ATXN1 may lead to AD pathogenesis by affecting Aβ 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 Aβ40 and Aβ42. This effect could be rescued with concurrent overexpression of ATXN1. Moreover, overexpression of ATXN1 decreased Aβ levels. Regarding the underlying molecular mechanism, we show that the effect of ATXN1 expression on Aβ levels is modulated via β-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 β-secretase cleavage of APP and Aβ levels. PMID:20097758

Selective deletion of apolipoprotein E in astrocytes ameliorates the spatial learning and memory deficits in Alzheimer's disease (APP/PS1) mice by inhibiting TGF-β/Smad2/STAT3 signaling.

PubMed

Zheng, Jin-Yu; Sun, Jian; Ji, Chun-Mei; Shen, Lin; Chen, Zhong-Jun; Xie, Peng; Sun, Yuan-Zhao; Yu, Ru-Tong

2017-06-01

Astrocytes and apolipoprotein E (apoE) play critical roles in cognitive function, not only under physiological conditions but also in some pathological situations, particularly in the pathological progression of Alzheimer's disease (AD). The regulatory mechanisms underlying the effect of apoE, derived from astrocytes, on cognitive deficits during AD pathology development are unclear. In this study, we generated amyloid precursor protein/apoE knockout (APP/apoE KO ) and APP/glial fibrillary acidic protein (GFAP)-apoE KO mice (the AD mice model used in this study was based on the APP-familial Alzheimer disease overexpression) to investigate the role of apoE, derived from astrocytes, in AD pathology and cognitive function. To explore the mechanism, we investigated the amyloidogenic process related transforming growth factor β/mothers against decapentaplegic homolog 2/signal transducer and activator of transcription 3 (TGF-β/Smad2/STAT3) signaling pathway and further confirmed by administering TGF-β-overexpression adeno-associated virus (specific to astrocytes) to APP/GFAP-apoE KO mice and TGF-β-inhibition adeno-associated virus (specific to astrocytes) to APP/WT mice. Whole body deletion of apoE significantly ameliorated the spatial learning and memory impairment, reduced amyloid β-protein production and inhibited astrogliosis in APP/apoE KO mice, as well as specific deletion apoE in astrocytes in APP/GFAP-apoE KO mice. Moreover, amyloid β-protein accumulation was increased due to promotion of amyloidogenesis of APP, and astrogliosis was upregulated by activation of TGF-β/Smad2/STAT3 signaling. Furthermore, the overexpression of TGF-β in astrocytes in APP/GFAP-apoE KO mice abrogated the effects of apoE knockout. In contrast, repression of TGF-β in astrocytes of APP/WT mice exerted a therapeutic effect similar to apoE knockout. These data suggested that apoE derived from astrocytes contributes to the risk of AD through TGF-β/Smad2/STAT3 signaling activation. These findings enhance our understanding of the role of apoE, derived from astrocytes, in AD and suggest it to be a potential biomarker and therapeutic target for AD. Copyright © 2017 Elsevier Inc. All rights reserved.

P2 receptor stimulation induces amyloid precursor protein production and secretion in rat cortical astrocytes.

PubMed

Tran, Minh D

2011-04-04

Amyloid precursor protein (APP) is ubiquitously expressed in a variety of tissues but is predominantly expressed in the brain. The expression of APP has been well studied in neurons but little is known about its presence in astrocytes. The study presented here shows that purinergic signaling is involved in the production and secretion of APP in primary cultures of rat cortical astrocytes. Extracellular ATP caused an increase in APP production and release in a time- and concentration-dependent manner and was inhibited by antagonists of P2 receptors. Further agonist and antagonist studies revealed involvement of P2Y2 and P2Y4 receptors in nucleotide-stimulated production and release of APP. In addition, signaling studies with various protein kinase inhibitors demonstrated that blockade of mitogen-activated protein kinases, but not Akt, inhibited nucleotide-stimulated APP expression and release. These results indicate that APP production and secretion can be regulated by activation of P2Y2/4 receptors coupled to protein kinase signaling pathways and suggest that astrocytes can be a potential source of APP. Published by Elsevier Ireland Ltd.

Multiple layers of temporal and spatial control regulate accumulation of the fruiting body-specific protein APP in Sordaria macrospora and Neurospora crassa.

PubMed

Nowrousian, Minou; Piotrowski, Markus; Kück, Ulrich

2007-07-01

During fungal fruiting body development, specialized cell types differentiate from vegetative mycelium. We have isolated a protein from the ascomycete Sordaria macrospora that is not present during vegetative growth but accumulates in perithecia. The protein was sequenced by mass spectrometry and the corresponding gene was termed app (abundant perithecial protein). app transcript occurs only after the onset of sexual development; however, the formation of ascospores is not a prerequisite for APP accumulation. The transcript of the Neurospora crassa ortholog is present prior to fertilization, but the protein accumulates only after fertilization. In crosses of N. crassa Deltaapp strains with the wild type, APP accumulates when the wild type serves as female parent, but not in the reciprocal cross; thus, the presence of a functional female app allele is necessary and sufficient for APP accumulation. These findings highlight multiple layers of temporal and spatial control of gene expression during fungal development.

The use of atmospheric pressure plasma as a curing process for canned ground ham.

PubMed

Lee, Juri; Jo, Kyung; Lim, Yubong; Jeon, Hee Joon; Choe, Jun Ho; Jo, Cheorun; Jung, Samooel

2018-02-01

This study investigated the potential use of atmospheric pressure plasma (APP) treatment as a curing process for canned ground ham. APP treatment for 60min while mixing increased the nitrite content in the meat batters from 0.64 to 60.50mgkg -1 while the pH and the total content of aerobic bacteria in the meat batters were unchanged. The canned ground hams cured by the APP treatment for 30min displayed no difference in their physicochemical qualities, such as nitrosyl hemochrome, color, residual nitrite, texture, lipid oxidation, and protein oxidation, compared with those of canned ground hams cured with sodium nitrite or celery powder at 42mgkg -1 of nitrite. The canned ground hams cured by the APP treatment received a higher score in taste and overall acceptability than those cured with sodium nitrite. Canned ground ham can be cured by the APP treatment without nitrite additives. Copyright © 2017 Elsevier Ltd. All rights reserved.

APP/Go protein Gβγ-complex signaling mediates Aβ degeneration and cognitive impairment in Alzheimer's disease models.

PubMed

Bignante, Elena Anahi; Ponce, Nicolás Eric; Heredia, Florencia; Musso, Juliana; Krawczyk, María C; Millán, Julieta; Pigino, Gustavo F; Inestrosa, Nibaldo C; Boccia, Mariano M; Lorenzo, Alfredo

2018-04-01

Deposition of amyloid-β (Aβ), the proteolytic product of the amyloid precursor protein (APP), might cause neurodegeneration and cognitive decline in Alzheimer's disease (AD). However, the direct involvement of APP in the mechanism of Aβ-induced degeneration in AD remains on debate. Here, we analyzed the interaction of APP with heterotrimeric Go protein in primary hippocampal cultures and found that Aβ deposition dramatically enhanced APP-Go protein interaction in dystrophic neurites. APP overexpression rendered neurons vulnerable to Aβ toxicity by a mechanism that required Go-Gβγ complex signaling and p38-mitogen-activated protein kinase activation. Gallein, a selective pharmacological inhibitor of Gβγ complex, inhibited Aβ-induced dendritic and axonal dystrophy, abnormal tau phosphorylation, synaptic loss, and neuronal cell death in hippocampal neurons expressing endogenous protein levels. In the 3xTg-AD mice, intrahippocampal application of gallein reversed memory impairment associated with early Aβ pathology. Our data provide further evidence for the involvement of APP/Go protein in Aβ-induced degeneration and reveal that Gβγ complex is a signaling target potentially relevant for developing therapies for halting Aβ degeneration in AD. Copyright © 2017 Elsevier Inc. All rights reserved.

Protein misfolding, congophilia, oligomerization, and defective amyloid processing in preeclampsia.

PubMed

Buhimschi, Irina A; Nayeri, Unzila A; Zhao, Guomao; Shook, Lydia L; Pensalfini, Anna; Funai, Edmund F; Bernstein, Ira M; Glabe, Charles G; Buhimschi, Catalin S

2014-07-16

Preeclampsia is a pregnancy-specific disorder of unknown etiology and a leading contributor to maternal and perinatal morbidity and mortality worldwide. Because there is no cure other than delivery, preeclampsia is the leading cause of iatrogenic preterm birth. We show that preeclampsia shares pathophysiologic features with recognized protein misfolding disorders. These features include urine congophilia (affinity for the amyloidophilic dye Congo red), affinity for conformational state-dependent antibodies, and dysregulation of prototype proteolytic enzymes involved in amyloid precursor protein (APP) processing. Assessment of global protein misfolding load in pregnancy based on urine congophilia (Congo red dot test) carries diagnostic and prognostic potential for preeclampsia. We used conformational state-dependent antibodies to demonstrate the presence of generic supramolecular assemblies (prefibrillar oligomers and annular protofibrils), which vary in quantitative and qualitative representation with preeclampsia severity. In the first attempt to characterize the preeclampsia misfoldome, we report that the urine congophilic material includes proteoforms of ceruloplasmin, immunoglobulin free light chains, SERPINA1, albumin, interferon-inducible protein 6-16, and Alzheimer's β-amyloid. The human placenta abundantly expresses APP along with prototype APP-processing enzymes, of which the α-secretase ADAM10, the β-secretases BACE1 and BACE2, and the γ-secretase presenilin-1 were all up-regulated in preeclampsia. The presence of β-amyloid aggregates in placentas of women with preeclampsia and fetal growth restriction further supports the notion that this condition should join the growing list of protein conformational disorders. If these aggregates play a pathophysiologic role, our findings may lead to treatment for preeclampsia. Copyright © 2014, American Association for the Advancement of Science.

Amyloid precursor protein and Presenilin1 interact with the adaptor GRB2 and modulate ERK 1,2 signaling.

PubMed

Nizzari, Mario; Venezia, Valentina; Repetto, Emanuela; Caorsi, Valentina; Magrassi, Raffaella; Gagliani, Maria Cristina; Carlo, Pia; Florio, Tullio; Schettini, Gennaro; Tacchetti, Carlo; Russo, Tommaso; Diaspro, Alberto; Russo, Claudio

2007-05-04

The amyloid precursor protein (APP) and the presenilins 1 and 2 are genetically linked to the development of familial Alzheimer disease. APP is a single-pass transmembrane protein and precursor of fibrillar and toxic amyloid-beta peptides, which are considered responsible for Alzheimer disease neurodegeneration. Presenilins are multipass membrane proteins, involved in the enzymatic cleavage of APP and other signaling receptors and transducers. The role of APP and presenilins in Alzheimer disease development seems to be related to the formation of amyloid-beta peptides; however, their physiological function, reciprocal interaction, and molecular mechanisms leading to neurodegeneration are unclear. APP and presenilins are also involved in multiple interactions with intracellular proteins, the significance of which is under investigation. Among the different APP-interacting proteins, we focused our interest on the GRB2 adaptor protein, which connects cell surface receptors to intracellular signaling pathways. In this study we provide evidence by co-immunoprecipitation experiments, confocal and electron microscopy, and by fluorescence resonance energy transfer experiments that both APP and presenilin1 interact with GRB2 in vesicular structures at the centrosome of the cell. The final target for these interactions is ERK1,2, which is activated in mitotic centrosomes in a PS1- and APP-dependent manner. These data suggest that both APP and presenilin1 can be part of a common signaling pathway that regulates ERK1,2 and the cell cycle.

Exosomes: vehicles for the transfer of toxic proteins associated with neurodegenerative diseases?

PubMed

Bellingham, Shayne A; Guo, Belinda B; Coleman, Bradley M; Hill, Andrew F

2012-01-01

Exosomes are small membranous vesicles secreted by a number of cell types including neurons and can be isolated from conditioned cell media or bodily fluids such as urine and plasma. Exosome biogenesis involves the inward budding of endosomes to form multivesicular bodies (MVB). When fused with the plasma membrane, the MVB releases the vesicles into the extracellular environment as exosomes. Proposed functions of these vesicles include roles in cell-cell signaling, removal of unwanted proteins, and the transfer of pathogens between cells. One such pathogen which exploits this pathway is the prion, the infectious particle responsible for the transmissible neurodegenerative diseases such as Creutzfeldt-Jakob disease (CJD) of humans or bovine spongiform encephalopathy (BSE) of cattle. Similarly, exosomes are also involved in the processing of the amyloid precursor protein (APP) which is associated with Alzheimer's disease. Exosomes have been shown to contain full-length APP and several distinct proteolytically cleaved products of APP, including Aβ. In addition, these fragments can be modulated using inhibitors of the proteases involved in APP cleavage. These observations provide further evidence for a novel pathway in which PrP and APP fragments are released from cells. Other proteins such as superoxide dismutase I and alpha-synuclein (involved in amyotrophic lateral sclerosis and Parkinson's disease, respectively) are also found associated with exosomes. This review will focus on the role of exosomes in neurodegenerative disorders and discuss the potential of these vesicles for the spread of neurotoxicity, therapeutics, and diagnostics for these diseases.

The Possible Mechanism of Advanced Glycation End Products (AGEs) for Alzheimer’s Disease

PubMed Central

Ko, Shun-Yao; Ko, Hshin-An; Chu, Kuo-Hsiung; Shieh, Tzong-Ming; Chi, Tzong-Cherng; Chen, Hong-I; Chang, Weng-Cheng; Chang, Shu-Shing

2015-01-01

Amyloid precursor protein (APP) has been modified by β and γ-secretase that cause amyloid deposits (plaques) in neuronal cells. Glyceraldhyde-derived AGEs has been identified as a major source of neurotoxicity in Alzheimer’s disease (AD). In a previous study, we demonstrated that glyceraldehyde-derived AGEs increase APP and Aβ via ROS. Furthermore, the combination of AGEs and Aβ has been shown to enhance neurotoxicity. In mice, APP expression is increased by tail vein injection of AGEs. This evidence suggests a correlation between AGEs and the development of AD. However, the role played by AGEs in the pathogenesis of AD remains unclear. In this report, we demonstrate that AGEs up-regulate APP processing protein (BACE and PS1) and Sirt1 expression via ROS, but do not affect the expression of downstream antioxidant genes HO-1 and NQO-1. Moreover, we found that AGEs increase GRP78 expression and enhance the cell death-related pathway p53, bcl-2/bax ratio, caspase 3. These results indicate that AGEs impair the neuroprotective effects of Sirt1 and lead to neuronal cell death via ER stress. Our findings suggest that AGEs increase ROS production, which stimulates downstream pathways related to APP processing, Aβ production, Sirt1, and GRP78, resulting in the up-regulation of cell death related pathway. This in-turn enhances neuronal cell death, which leads to the development of AD. PMID:26587989

The Possible Mechanism of Advanced Glycation End Products (AGEs) for Alzheimer's Disease.

PubMed

Ko, Shun-Yao; Ko, Hshin-An; Chu, Kuo-Hsiung; Shieh, Tzong-Ming; Chi, Tzong-Cherng; Chen, Hong-I; Chang, Weng-Cheng; Chang, Shu-Shing

2015-01-01

Amyloid precursor protein (APP) has been modified by β and γ-secretase that cause amyloid deposits (plaques) in neuronal cells. Glyceraldhyde-derived AGEs has been identified as a major source of neurotoxicity in Alzheimer's disease (AD). In a previous study, we demonstrated that glyceraldehyde-derived AGEs increase APP and Aβ via ROS. Furthermore, the combination of AGEs and Aβ has been shown to enhance neurotoxicity. In mice, APP expression is increased by tail vein injection of AGEs. This evidence suggests a correlation between AGEs and the development of AD. However, the role played by AGEs in the pathogenesis of AD remains unclear. In this report, we demonstrate that AGEs up-regulate APP processing protein (BACE and PS1) and Sirt1 expression via ROS, but do not affect the expression of downstream antioxidant genes HO-1 and NQO-1. Moreover, we found that AGEs increase GRP78 expression and enhance the cell death-related pathway p53, bcl-2/bax ratio, caspase 3. These results indicate that AGEs impair the neuroprotective effects of Sirt1 and lead to neuronal cell death via ER stress. Our findings suggest that AGEs increase ROS production, which stimulates downstream pathways related to APP processing, Aβ production, Sirt1, and GRP78, resulting in the up-regulation of cell death related pathway. This in-turn enhances neuronal cell death, which leads to the development of AD.

Effect of Different Phospholipids on α-Secretase Activity in the Non-Amyloidogenic Pathway of Alzheimer’s Disease

PubMed Central

Grimm, Marcus O. W.; Haupenthal, Viola J.; Rothhaar, Tatjana L.; Zimmer, Valerie C.; Grösgen, Sven; Hundsdörfer, Benjamin; Lehmann, Johannes; Grimm, Heike S.; Hartmann, Tobias

2013-01-01

Alzheimer’s disease (AD) is characterized by extracellular accumulation of amyloid-β peptide (Aβ), generated by proteolytic processing of the amyloid precursor protein (APP) by β- and γ-secretase. Aβ generation is inhibited when the initial ectodomain shedding is caused by α-secretase, cleaving APP within the Aβ domain. Therefore, an increase in α-secretase activity is an attractive therapeutic target for AD treatment. APP and the APP-cleaving secretases are all transmembrane proteins, thus local membrane lipid composition is proposed to influence APP processing. Although several studies have focused on γ-secretase, the effect of the membrane lipid microenvironment on α-secretase is poorly understood. In the present study, we systematically investigated the effect of fatty acid (FA) acyl chain length (10:0, 12:0, 14:0, 16:0, 18:0, 20:0, 22:0, 24:0), membrane polar lipid headgroup (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine), saturation grade and the FA double-bond position on α-secretase activity. We found that α-secretase activity is significantly elevated in the presence of FAs with short chain length and in the presence of polyunsaturated FAs, whereas variations in the phospholipid headgroups, as well as the double-bond position, have little or no effect on α-secretase activity. Overall, our study shows that local lipid membrane composition can influence α-secretase activity and might have beneficial effects for AD. PMID:23485990

Generation and initial characterization of FDD knock in mice.

PubMed

Giliberto, Luca; Matsuda, Shuji; Vidal, Ruben; D'Adamio, Luciano

2009-11-18

Mutations in the integral membrane protein 2B, also known as BRI(2), a type II trans-membrane domain protein cause two autosomal dominant neurodegenerative diseases, Familial British and Danish Dementia. In these conditions, accumulation of a C-terminal peptide (ABri and ADan) cleaved off from the mutated precursor protein by the pro-protein convertase furin, leads to amyloid deposition in the walls of blood vessels and parenchyma of the brain. Recent advances in the understanding of the generation of amyloid in Alzheimer's disease has lead to the finding that BRI(2) interacts with the Amyloid Precursor Protein (APP), decreasing the efficiency of APP processing to generate Abeta. The interaction between the two precursors, APP and BRI(2), and possibly between Abeta and ABri or ADan, could be important in influencing the rate of amyloid production or the tendency of these peptides to aggregate. We have generated the first BRI(2) Danish Knock-In (FDD(KI)) murine model of FDD, expressing the pathogenic decamer duplication in exon 6 of the BRI(2) gene. FDD(KI) mice do not show any evident abnormal phenotype, with normal brain histology and no detectable amyloid deposition in blood vessel walls or parenchyma. This new murine mouse model will be important to further understand the interaction between APP and BRI(2), and to provide insights into the molecular basis of FDD.

Trans fatty acids enhance amyloidogenic processing of the Alzheimer amyloid precursor protein (APP).

PubMed

Grimm, Marcus O W; Rothhaar, Tatjana L; Grösgen, Sven; Burg, Verena K; Hundsdörfer, Benjamin; Haupenthal, Viola J; Friess, Petra; Kins, Stefan; Grimm, Heike S; Hartmann, Tobias

2012-10-01

Hydrogenation of oils and diary products of ruminant animals leads to an increasing amount of trans fatty acids in the human diet. Trans fatty acids are incorporated in several lipids and accumulate in the membrane of cells. Here we systematically investigate whether the regulated intramembrane proteolysis of the amyloid precursor protein (APP) is affected by trans fatty acids compared to the cis conformation. Our experiments clearly show that trans fatty acids compared to cis fatty acids increase amyloidogenic and decrease nonamyloidogenic processing of APP, resulting in an increased production of amyloid beta (Aβ) peptides, main components of senile plaques, which are a characteristic neuropathological hallmark for Alzheimer's disease (AD). Moreover, our results show that oligomerization and aggregation of Aβ are increased by trans fatty acids. The mechanisms identified by this in vitro study suggest that the intake of trans fatty acids potentially increases the AD risk or causes an earlier onset of the disease. Copyright © 2012 Elsevier Inc. All rights reserved.

A molecular dynamics study of the binary complexes of APP, JIP1, and the cargo binding domain of KLC.

PubMed

Taylor, Cooper A; Miller, Bill R; Shah, Soleil S; Parish, Carol A

2017-02-01

Mutations in the amyloid precursor protein (APP) are responsible for the formation of amyloid-β peptides. These peptides play a role in Alzheimer's and other dementia-related diseases. The cargo binding domain of the kinesin-1 light chain motor protein (KLC1) may be responsible for transporting APP either directly or via interaction with C-jun N-terminal kinase-interacting protein 1 (JIP1). However, to date there has been no direct experimental or computational assessment of such binding at the atomistic level. We used molecular dynamics and free energy estimations to gauge the affinity for the binary complexes of KLC1, APP, and JIP1. We find that all binary complexes (KLC1:APP, KLC1:JIP1, and APP:JIP1) contain conformations with favorable binding free energies. For KLC1:APP the inclusion of approximate entropies reduces the favorability. This is likely due to the flexibility of the 42-residue APP protein. In all cases we analyze atomistic/residue driving forces for favorable interactions. Proteins 2017; 85:221-234. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Amyloid Precursor Protein (APP) May Act as a Substrate and a Recognition Unit for CRL4CRBN and Stub1 E3 Ligases Facilitating Ubiquitination of Proteins Involved in Presynaptic Functions and Neurodegeneration.

PubMed

Del Prete, Dolores; Rice, Richard C; Rajadhyaksha, Anjali M; D'Adamio, Luciano

2016-08-12

The amyloid precursor protein (APP), whose mutations cause Alzheimer disease, plays an important in vivo role and facilitates transmitter release. Because the APP cytosolic region (ACR) is essential for these functions, we have characterized its brain interactome. We found that the ACR interacts with proteins that regulate the ubiquitin-proteasome system, predominantly with the E3 ubiquitin-protein ligases Stub1, which binds the NH2 terminus of the ACR, and CRL4(CRBN), which is formed by Cul4a/b, Ddb1, and Crbn, and interacts with the COOH terminus of the ACR via Crbn. APP shares essential functions with APP-like protein-2 (APLP2) but not APP-like protein-1 (APLP1). Noteworthy, APLP2, but not APLP1, interacts with Stub1 and CRL4(CRBN), pointing to a functional pathway shared only by APP and APLP2. In vitro ubiquitination/ubiquitome analysis indicates that these E3 ligases are enzymatically active and ubiquitinate the ACR residues Lys(649/650/651/676/688) Deletion of Crbn reduces ubiquitination of Lys(676) suggesting that Lys(676) is physiologically ubiquitinated by CRL4(CRBN) The ACR facilitated in vitro ubiquitination of presynaptic proteins that regulate exocytosis, suggesting a mechanism by which APP tunes transmitter release. Other dementia-related proteins, namely Tau and apoE, interact with and are ubiquitinated via the ACR in vitro This, and the evidence that CRBN and CUL4B are linked to intellectual disability, prompts us to hypothesize a pathogenic mechanism, in which APP acts as a modulator of E3 ubiquitin-protein ligase(s), shared by distinct neuronal disorders. The well described accumulation of ubiquitinated protein inclusions in neurodegenerative diseases and the link between the ubiquitin-proteasome system and neurodegeneration make this concept plausible. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Relative increase in Alzheimer's disease of soluble forms of cerebral Abeta amyloid protein precursor containing the Kunitz protease inhibitory domain.

PubMed

Moir, R D; Lynch, T; Bush, A I; Whyte, S; Henry, A; Portbury, S; Multhaup, G; Small, D H; Tanzi, R E; Beyreuther, K; Masters, C L

1998-02-27

Although a number of studies have examined amyloid precursor protein (APP) mRNA levels in Alzheimer's disease (AD), no clear consensus has emerged as to whether the levels of transcripts for isoforms containing a Kunitz protease inhibitory (KPI)-encoded region are increased or decreased in AD. Here we compare AD and control brain for the relative amounts of APP protein containing KPI to APP protein lacking this domain. APP protein was purified from the soluble subcellular fraction and Triton X-100 membrane pellet extract of one hemisphere of AD (n = 10), normal (n = 7), and neurological control (n = 5) brains. The amount of KPI-containing APP in the purified protein samples was determined using two independent assay methods. The first assay exploited the inhibitory action of KPI-containing APP on trypsin. The second assay employed reflectance analysis of Western blots. The proportion of KPI-containing forms of APP in the soluble subcellular fraction of AD brains is significantly elevated (p < 0.01) compared with controls. Species containing a KPI domain comprise 32-41 and 76-77% of purified soluble APP from control and AD brains, respectively. For purified membrane-associated APP, 72-77 and 65-82% of control and AD samples, respectively, contain a KPI domain. Since KPI-containing species of APP may be more amyloidogenic (Ho, L., Fukuchi, K., and Yonkin, S. G. (1996) J. Biol. Chem. 271, 30929-30934), our findings support an imbalance of isoforms as one possible mechanism for amyloid deposition in sporadic AD.

Inhibition of γ-secretase worsens memory deficits in a genetically congruous mouse model of Danish dementia

PubMed Central

2012-01-01

Background A mutation in the BRI2/ITM2b gene causes familial Danish dementia (FDD). BRI2 is an inhibitor of amyloid-β precursor protein (APP) processing, which is genetically linked to Alzheimer’s disease (AD) pathogenesis. The FDD mutation leads to a loss of BRI2 protein and to increased APP processing. APP haplodeficiency and inhibition of APP cleavage by β-secretase rescue synaptic/memory deficits of a genetically congruous mouse model of FDD (FDDKI). β-cleavage of APP yields the β-carboxyl-terminal (β-CTF) and the amino-terminal-soluble APPβ (sAPPβ) fragments. γ-secretase processing of β-CTF generates Aβ, which is considered the main cause of AD. However, inhibiting Aβ production did not rescue the deficits of FDDKI mice, suggesting that sAPPβ/β-CTF, and not Aβ, are the toxic species causing memory loss. Results Here, we have further analyzed the effect of γ-secretase inhibition. We show that treatment with a γ-secretase inhibitor (GSI) results in a worsening of the memory deficits of FDDKI mice. This deleterious effect on memory correlates with increased levels of the β/α-CTFs APP fragments in synaptic fractions isolated from hippocampi of FDDKI mice, which is consistent with inhibition of γ-secretase activity. Conclusion This harmful effect of the GSI is in sharp contrast with a pathogenic role for Aβ, and suggests that the worsening of memory deficits may be due to accumulation of synaptic-toxic β/α-CTFs caused by GSI treatment. However, γ-secretase cleaves more than 40 proteins; thus, the noxious effect of GSI on memory may be dependent on inhibition of cleavage of one or more of these other γ-secretase substrates. These two possibilities do not need to be mutually exclusive. Our results are consistent with the outcome of a clinical trial with the GSI Semagacestat, which caused a worsening of cognition, and advise against targeting γ-secretase in the therapy of AD. Overall, the data also indicate that FDDKI is a valuable mouse model to study AD pathogenesis and predict the clinical outcome of therapeutic agents for AD. PMID:22537414

Inhibition of γ-secretase worsens memory deficits in a genetically congruous mouse model of Danish dementia.

PubMed

Tamayev, Robert; D'Adamio, Luciano

2012-04-26

A mutation in the BRI2/ITM2b gene causes familial Danish dementia (FDD). BRI2 is an inhibitor of amyloid-β precursor protein (APP) processing, which is genetically linked to Alzheimer's disease (AD) pathogenesis. The FDD mutation leads to a loss of BRI2 protein and to increased APP processing. APP haplodeficiency and inhibition of APP cleavage by β-secretase rescue synaptic/memory deficits of a genetically congruous mouse model of FDD (FDDKI). β-cleavage of APP yields the β-carboxyl-terminal (β-CTF) and the amino-terminal-soluble APPβ (sAPPβ) fragments. γ-secretase processing of β-CTF generates Aβ, which is considered the main cause of AD. However, inhibiting Aβ production did not rescue the deficits of FDDKI mice, suggesting that sAPPβ/β-CTF, and not Aβ, are the toxic species causing memory loss. Here, we have further analyzed the effect of γ-secretase inhibition. We show that treatment with a γ-secretase inhibitor (GSI) results in a worsening of the memory deficits of FDDKI mice. This deleterious effect on memory correlates with increased levels of the β/α-CTFs APP fragments in synaptic fractions isolated from hippocampi of FDDKI mice, which is consistent with inhibition of γ-secretase activity. This harmful effect of the GSI is in sharp contrast with a pathogenic role for Aβ, and suggests that the worsening of memory deficits may be due to accumulation of synaptic-toxic β/α-CTFs caused by GSI treatment. However, γ-secretase cleaves more than 40 proteins; thus, the noxious effect of GSI on memory may be dependent on inhibition of cleavage of one or more of these other γ-secretase substrates. These two possibilities do not need to be mutually exclusive. Our results are consistent with the outcome of a clinical trial with the GSI Semagacestat, which caused a worsening of cognition, and advise against targeting γ-secretase in the therapy of AD. Overall, the data also indicate that FDDKI is a valuable mouse model to study AD pathogenesis and predict the clinical outcome of therapeutic agents for AD.

Alpha-Linolenic Acid from Perilla frutescens var. japonica Oil Protects Aβ-Induced Cognitive Impairment through Regulation of APP Processing and Aβ Degradation.

PubMed

Lee, Ah Young; Lee, Myoung Hee; Lee, Sanghyun; Cho, Eun Ju

2017-12-13

Alzheimer's disease (AD) is characterized by progressive cognitive and memory impairment. The major pathological hallmark of AD is the accumulation of amyloid beta (Aβ), which is produced from the amyloid precursor protein (APP) through cleavage of β- and γ-secretase. Recently, dietary plant oil containing ω-3 polyunsaturated fatty acid has become an attractive alternative source to fish oil containing eicosapentaenoic acid or docosahexaenoic acid (DHA). We investigated whether ALA isolated from perilla oil has direct effects on improvement of cognitive ability and molecular mechanisms in APP processing in comparison with DHA. In the present study, ICR mice were treated orally with ALA or DHA (100 mg/kg/day) for 14 days after i.c.v. injection of Aβ 25-35 . Administration of ALA resulted in a prevention of learning and memory deficit in Aβ 25-35 -injected mice compared with the control group, as observed in T-maze, novel object recognition, and Morris water maze tests. ALA supplementation also markedly ameliorated the Aβ 25-35 -induced oxidative stress by inhibition of lipid peroxidation and nitric oxide overproduction in the mouse brain, liver, and kidney, almost down to the levels in DHA-administered group. These effects of ALA on protective mechanisms were related to the regulation of APP processing via promoting nonamyloidogenic pathway such as up-regulation of soluble APP alpha, C-terminal fragment alpha/beta ratio, and A disintegrin and metalloprotease10 protein expressions. Furthermore, ALA inhibited the amyloidogenic pathway through the down-regulation of β-site APP-cleaving enzyme and presenilin2. ALA also enhanced Aβ degradation enzyme, insulin-degrading enzyme. In conclusion, the present study indicated a beneficial effect of ALA in improving the cognitive ability against Aβ 25-35 , and these effects were comparable to those exerted by DHA. Its neuroprotective effects are mediated, in part, by regulation of APP processing and Aβ degradation, and thus, ALA might be a potential candidate for prevention or treatment of neurodegenerative diseases such as AD.

[From physiopathology to treatment of Alzheimer's disease].

PubMed

Delacourte, A

2006-10-01

The natural and molecular history of familial or sporadic Alzheimer's disease (AD) shows that APP (amyloid protein precursor) dysfunction is a consensual central etiological factor in Alzheimer's disease (AD). This is demonstrated by 1) genetic defects involving APP gene or APP dysfunction (such as PS1 or PS2), leading to the formation of neocortical amyloid plaques in familial AD; 2) transgenic mice with these mutated genes that develop plaques; 3) both sporadic and familial AD develop plaques. But two alternatives to explain the physiopathology can be proposed: a gain of toxic function of AB peptide (reflected by the amyloid cascade hypothesis) or a loss of function of APP, a ubiquitous and well conserved protein with numerous possible neurotrophic activities. On the other hand, AD is also characterized by another inescapable degenerating process: tauopathy, an intraneuronal aggregation of tau proteins into neurofibrillary tangles. Remarkably enough, progression of tauopathy in neocortical areas fully explains the progressive clinical deficits of AD, from memory loss to aphasia, apraxia, agnosia. Also one has to bare in mind that most demented patients and most dementing neurodegenerative disorders have a tauopathy. From that, it is concluded that APP an Tau are solid therapeutic targets. But if we know that APP and Tau dysfunctions interact to boost neurodegeneration in AD, we still do no know what are the intraneuronal signaling pathways to activate or to inhibit to stop the degenerating process. There are many hypotheses and many possible approaches: the inhibition of toxicity of plaque, of AB protofibrils, or of AB oligomers inside or outside the neuron, using vaccination or ligands (Alzhemed). On the other hand, modulation of secretases that cleave APP by inhibiting those involved in the amyloidogenic pathway or by stimulating those of the non-amyloidogenic pathway, is a major route of research. Also modulation of kinases or phosphatases possibly involved in the aggregation of tau is also investigated. Because animal models are not perfectly relevant, at the end of the long and costly pathway of drug discovery, therapeutic trials are the only way to test these different hypotheses.

Evidence against roles for phorbol binding protein Munc13-1, ADAM adaptor Eve-1, or vesicle trafficking phosphoproteins Munc18 or NSF as phospho-state-sensitive modulators of phorbol/PKC-activated Alzheimer APP ectodomain shedding

PubMed Central

Ikin, Annat F; Causevic, Mirsada; Pedrini, Steve; Benson, Lyndsey S; Buxbaum, Joseph D; Suzuki, Toshiharu; Lovestone, Simon; Higashiyama, Shigeki; Mustelin, Tomas; Burgoyne, Robert D; Gandy, Sam

2007-01-01

Background Shedding of the Alzheimer amyloid precursor protein (APP) ectodomain can be accelerated by phorbol esters, compounds that act via protein kinase C (PKC) or through unconventional phorbol-binding proteins such as Munc13-1. We have previously demonstrated that application of phorbol esters or purified PKC potentiates budding of APP-bearing secretory vesicles at the trans-Golgi network (TGN) and toward the plasma membrane where APP becomes a substrate for enzymes responsible for shedding, known collectively as α-secretase(s). However, molecular identification of the presumptive "phospho-state-sensitive modulators of ectodomain shedding" (PMES) responsible for regulated shedding has been challenging. Here, we examined the effects on APP ectodomain shedding of four phorbol-sensitive proteins involved in regulation of vesicular membrane trafficking of APP: Munc13-1, Munc18, NSF, and Eve-1. Results Overexpression of either phorbol-sensitive wildtype Munc13-1 or phorbol-insensitive Munc13-1 H567K resulted in increased basal APP ectodomain shedding. However, in contrast to the report of Roßner et al (2004), phorbol ester-dependent APP ectodomain shedding from cells overexpressing APP and Munc13-1 wildtype was indistinguishable from that observed following application of phorbol to cells overexpressing APP and Munc13-1 H567K mutant. This pattern of similar effects on basal and stimulated APP shedding was also observed for Munc18 and NSF. Eve-1, an ADAM adaptor protein reported to be essential for PKC-regulated shedding of pro-EGF, was found to play no obvious role in regulated shedding of sAPPα. Conclusion Our results indicate that, in the HEK293 system, Munc13-1, Munc18, NSF, and EVE-1 fail to meet essential criteria for identity as PMES for APP. PMID:18067682

Evidence against roles for phorbol binding protein Munc13-1, ADAM adaptor Eve-1, or vesicle trafficking phosphoproteins Munc18 or NSF as phospho-state-sensitive modulators of phorbol/PKC-activated Alzheimer APP ectodomain shedding.

PubMed

Ikin, Annat F; Causevic, Mirsada; Pedrini, Steve; Benson, Lyndsey S; Buxbaum, Joseph D; Suzuki, Toshiharu; Lovestone, Simon; Higashiyama, Shigeki; Mustelin, Tomas; Burgoyne, Robert D; Gandy, Sam

2007-12-09

Shedding of the Alzheimer amyloid precursor protein (APP) ectodomain can be accelerated by phorbol esters, compounds that act via protein kinase C (PKC) or through unconventional phorbol-binding proteins such as Munc13-1. We have previously demonstrated that application of phorbol esters or purified PKC potentiates budding of APP-bearing secretory vesicles at the trans-Golgi network (TGN) and toward the plasma membrane where APP becomes a substrate for enzymes responsible for shedding, known collectively as alpha-secretase(s). However, molecular identification of the presumptive "phospho-state-sensitive modulators of ectodomain shedding" (PMES) responsible for regulated shedding has been challenging. Here, we examined the effects on APP ectodomain shedding of four phorbol-sensitive proteins involved in regulation of vesicular membrane trafficking of APP: Munc13-1, Munc18, NSF, and Eve-1. Overexpression of either phorbol-sensitive wildtype Munc13-1 or phorbol-insensitive Munc13-1 H567K resulted in increased basal APP ectodomain shedding. However, in contrast to the report of Rossner et al (2004), phorbol ester-dependent APP ectodomain shedding from cells overexpressing APP and Munc13-1 wildtype was indistinguishable from that observed following application of phorbol to cells overexpressing APP and Munc13-1 H567K mutant. This pattern of similar effects on basal and stimulated APP shedding was also observed for Munc18 and NSF. Eve-1, an ADAM adaptor protein reported to be essential for PKC-regulated shedding of pro-EGF, was found to play no obvious role in regulated shedding of sAPPalpha. Our results indicate that, in the HEK293 system, Munc13-1, Munc18, NSF, and EVE-1 fail to meet essential criteria for identity as PMES for APP.

SUBFIELD AND LAYER-SPECIFIC DEPLETION IN CALBINDIN-D28K, CALRETININ AND PARVALBUMIN IMMUNOREACTIVITY IN THE DENTATE GYRUS OF APP/PS1 TRANSGENIC MICE

PubMed Central

Popovi, Miroljub; Caballero-Bleda, María; Kadish, Inga; van Groen, Thomas

2008-01-01

The depletion of neuronal calcium binding proteins deprives neurons of the capacity to buffer high levels of intracellular Ca2+ and this leaves them vulnerable to pathological processes, such as those present in Alzheimer’s disease (AD). The aim of the present study was to investigate the expression of the calcium binding proteins, calbindin-D28K, calretinin and parvalbumin in the dentate gyrus (DG) of APP/PS1 transgenic mice and their non-Tg littermates, as well as the relation with the deposition of human Aβ. We measured the expression of these three proteins at seven different rostro-caudal levels, and in the molecular, granular and polymorphic layers of the DG. We found that, except in the most caudal part of the DG, there is a substantial loss of calbindin-D28K immunoreactivity in all three layers of the DG in APP/PS1 mice compared to the non-Tg mice. Significant loss of calretinin immunoreactivity is present in most of the polymorphic layer of the DG of APP/PS1 mice compared to the non-Tg mice, as well as in the rostral and intermediate part of the inner molecular layer. Compared to the non-Tg mice parvalbumin immunoreactivity is significantly reduced throughout the whole polymorphic layer as well as in the rostral and intermediate part of the granular layer of DG in APP/PS1 mice. The relatively preservation of calbindin immunoreactivity in the caudal part of molecular and granular layers as well as calretinin immunoreactivity in the caudal part of polymorphic layer of the DG is likely related to the lower Aβ expression in those parts of DG. The present data suggest an involvement of calcium-dependent pathways in the pathogenesis of AD and indicate that there exists a subfield and layer-specific decrease in immunoreactivity which is related to the type of calcium-binding protein in APP/PS1 mice. Moreover, it seems that APP expression affects more the calbindin expression then parvalbumin and calretinin expression in the DG of APP/PS1 transgenic mice. PMID:18583063

Curcumin decreases amyloid-beta peptide levels by attenuating the maturation of amyloid-beta precursor protein.

PubMed

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

2010-09-10

Alzheimer disease (AD) is a devastating neurodegenerative disease with no cure. The pathogenesis of AD is believed to be driven primarily by amyloid-beta (Abeta), the principal component of senile plaques. Abeta is an approximately 4-kDa peptide generated via cleavage of the amyloid-beta 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 Abeta-related pathology in transgenic AD mouse models via unknown molecular mechanisms. Here, we investigated the effects of curcumin on Abeta levels and APP processing in various cell lines and mouse primary cortical neurons. We show for the first time that curcumin potently lowers Abeta 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-beta pathology.

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

PubMed Central

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

Quantitation and localization of intracellular redox active metals by X-ray fluorescence microscopy in cortical neurons derived from APP and APLP2 knockout tissue

DOE PAGES

Ciccotosto, Giuseppe D.; James, Simon A.; Altissimo, Matteo; ...

2014-10-01

The amyloid precursor protein (APP) gene family includes APP and the amyloid precursor-like proteins, APLP1 and APLP2. These proteins contain metal binding sites for copper, zinc and iron and are known to have physiological roles in modulating the metal homeostasis in brain cells. Here we report the application of X-ray fluorescence microscopy (XFM) to investigate the subcellular distribution patterns of the metal ions Cu, Zn, Fe, and Ca in individual neurons derived from APP and APLP2 knockout mice brains to further define their role in metal homeostasis. These studies add to the growing body of data that the APP familymore » of proteins are metalloproteins that have shared as well as distinct effects on metals. As we continue to delineate the cellular effects of the APP family of proteins it is important to consider how metals are involved in their actions.« less

Amyloid precursor protein and endosomal-lysosomal dysfunction in Alzheimer's disease: inseparable partners in a multifactorial disease.

PubMed

Nixon, Ralph A

2017-07-01

Abnormalities of the endosomal-lysosomal network (ELN) are a signature feature of Alzheimer's disease (AD). These include the earliest known cytopathology that is specific to AD and that affects endosomes and induces the progressive failure of lysosomes, each of which are directly linked by distinct mechanisms to neurodegeneration. The origins of ELN dysfunction and β-amyloidogenesis closely overlap, which reflects their common genetic basis, the established early involvement of endosomes and lysosomes in amyloid precursor protein (APP) processing and clearance, and the pathologic effect of certain APP metabolites on ELN functions. Genes that promote β-amyloidogenesis in AD (APP, PSEN1/2, and APOE4) have primary effects on ELN function. The importance of primary ELN dysfunction to pathogenesis is underscored by the mutations in more than 35 ELN-related genes that, thus far, are known to cause familial neurodegenerative diseases even though different pathogenic proteins may be involved. In this article, I discuss growing evidence that implicates AD gene-driven ELN disruptions as not only the antecedent pathobiology that underlies β-amyloidogenesis but also as the essential partner with APP and its metabolites that drive the development of AD, including tauopathy, synaptic dysfunction, and neurodegeneration. The striking amelioration of diverse deficits in animal AD models by remediating ELN dysfunction further supports a need to integrate APP and ELN relationships, including the role of amyloid-β, into a broader conceptual framework of how AD arises, progresses, and may be effectively therapeutically targeted.-Nixon, R. A. Amyloid precursor protein and endosomal-lysosomal dysfunction in Alzheimer's disease: inseparable partners in a multifactorial disease. © FASEB.

Photo dynamics of BLUF domain mutant H44R of AppA from Rhodobacter sphaeroides

NASA Astrophysics Data System (ADS)

Zirak, P.; Penzkofer, A.; Hegemann, P.; Mathes, T.

2007-05-01

The photo-cycle dynamics of the H44R mutant of the BLUF domain of the transcriptional anti-repressor protein AppA (AppA-H44R) from the non-sulfur anoxyphototropic purple bacterium Rhodobacter sphaeroides is studied in order to gain information on the involvement of His44 in the photo-cyclic mechanism of the AppA BLUF domain and to add information to the involved processes. The amino acid residue histidine at position 44 is replaced by arginine. A 12 nm red-shifted signalling state is formed upon blue-light excitation, while in wild-type AppA (AppA-wt) the red-shift is 16 nm. The recovery to the receptor dark state is approximately a factor of 2.5 faster ( τrec ≈ 6.5 min) than the recovery of the wild-type counterpart. Extended light exposure of the mutant causes photo-degradation of flavin (mainly free flavin conversion to lumichrome and re-equilibration between free and non-covalently bound flavin) and protein aggregation (showing up as light scattering). No photo-degradation was observed for AppA-wt. The quantum efficiency of signalling-state formation determined by intensity dependent absorption measurements is found to be ϕs ≈ 0.3 (for AppA-wt: ϕs ≈ 0.24). A two-component single-exponential fluorescence relaxation was observed, which is interpreted as fast fluorescence quenching to an equilibrium value by photo-induced electron transfer followed by slower fluorescence decay due to charge recombination. Based on the experimental findings, an extended photo-cycle model for BLUF domains is proposed.

Generation and Initial Characterization of FDD Knock In Mice

PubMed Central

Giliberto, Luca; Matsuda, Shuji; Vidal, Ruben; D'Adamio, Luciano

2009-01-01

Background Mutations in the integral membrane protein 2B [1], also known as BRI2 [2], a type II trans-membrane domain protein cause two autosomal dominant neurodegenerative diseases, Familial British and Danish Dementia [3]. In these conditions, accumulation of a C-terminal peptide (ABri and ADan) cleaved off from the mutated precursor protein by the pro-protein convertase furin [4], leads to amyloid deposition in the walls of blood vessels and parenchyma of the brain. Recent advances in the understanding of the generation of amyloid in Alzheimer's disease has lead to the finding that BRI2 interacts with the Amyloid Precursor Protein (APP), decreasing the efficiency of APP processing to generate Aβ [5], [6], [7]. The interaction between the two precursors, APP and BRI2, and possibly between Aβ and ABri or ADan, could be important in influencing the rate of amyloid production or the tendency of these peptides to aggregate. Methodology/Principal Findings We have generated the first BRI2 Danish Knock-In (FDDKI) murine model of FDD, expressing the pathogenic decamer duplication in exon 6 of the BRI2 gene. FDDKI mice do not show any evident abnormal phenotype, with normal brain histology and no detectable amyloid deposition in blood vessel walls or parenchyma. Conclusions/Significance This new murine mouse model will be important to further understand the interaction between APP and BRI2, and to provide insights into the molecular basis of FDD. PMID:19924302

Human Brain-Derived Aβ Oligomers Bind to Synapses and Disrupt Synaptic Activity in a Manner That Requires APP.

PubMed

Wang, Zemin; Jackson, Rosemary J; Hong, Wei; Taylor, Walter M; Corbett, Grant T; Moreno, Arturo; Liu, Wen; Li, Shaomin; Frosch, Matthew P; Slutsky, Inna; Young-Pearse, Tracy L; Spires-Jones, Tara L; Walsh, Dominic M

2017-12-06

Compelling genetic evidence links the amyloid precursor protein (APP) to Alzheimer's disease (AD) and several theories have been advanced to explain the relationship. A leading hypothesis proposes that a small amphipathic fragment of APP, the amyloid β-protein (Aβ), self-associates to form soluble aggregates that impair synaptic and network activity. Here, we used the most disease-relevant form of Aβ, protein isolated from AD brain. Using this material, we show that the synaptotoxic effects of Aβ depend on expression of APP and that the Aβ-mediated impairment of synaptic plasticity is accompanied by presynaptic effects that disrupt the excitatory/inhibitory (E/I) balance. The net increase in the E/I ratio and inhibition of plasticity are associated with Aβ localizing to synapses and binding of soluble Aβ aggregates to synapses requires the expression of APP. Our findings indicate a role for APP in AD pathogenesis beyond the generation of Aβ and suggest modulation of APP expression as a therapy for AD. SIGNIFICANCE STATEMENT Here, we report on the plasticity-disrupting effects of amyloid β-protein (Aβ) isolated from Alzheimer's disease (AD) brain and the requirement of amyloid precursor protein (APP) for these effects. We show that Aβ-containing AD brain extracts block hippocampal LTP, augment glutamate release probability, and disrupt the excitatory/inhibitory balance. These effects are associated with Aβ localizing to synapses and genetic ablation of APP prevents both Aβ binding and Aβ-mediated synaptic dysfunctions. Our results emphasize the importance of APP in AD and should stimulate new studies to elucidate APP-related targets suitable for pharmacological manipulation. Copyright © 2017 the authors 0270-6474/17/3711947-20$15.00/0.

Autism as early neurodevelopmental disorder: evidence for an sAPPα-mediated anabolic pathway

PubMed Central

Lahiri, Debomoy K.; Sokol, Deborah K.; Erickson, Craig; Ray, Balmiki; Ho, Chang Y.; Maloney, Bryan

2013-01-01

Autism is a neurodevelopmental disorder marked by social skills and communication deficits and interfering repetitive behavior. Intellectual disability often accompanies autism. In addition to behavioral deficits, autism is characterized by neuropathology and brain overgrowth. Increased intracranial volume often accompanies this brain growth. We have found that the Alzheimer’s disease (AD) associated amyloid-β precursor protein (APP), especially its neuroprotective processing product, secreted APP α, is elevated in persons with autism. This has led to the “anabolic hypothesis” of autism etiology, in which neuronal overgrowth in the brain results in interneuronal misconnections that may underlie multiple autism symptoms. We review the contribution of research in brain volume and of APP to the anabolic hypothesis, and relate APP to other proteins and pathways that have already been directly associated with autism, such as fragile X mental retardation protein, Ras small GTPase/extracellular signal-regulated kinase, and phosphoinositide 3 kinase/protein kinase B/mammalian target of rapamycin. We also present additional evidence of magnetic resonance imaging intracranial measurements in favor of the anabolic hypothesis. Finally, since it appears that APP’s involvement in autism is part of a multi-partner network, we extend this concept into the inherently interactive realm of epigenetics. We speculate that the underlying molecular abnormalities that influence APP’s contribution to autism are epigenetic markers overlaid onto potentially vulnerable gene sequences due to environmental influence. PMID:23801940

Amyloid Precursor Protein (APP) Mediated Regulation of Ganglioside Homeostasis Linking Alzheimer's Disease Pathology with Ganglioside Metabolism

PubMed Central

Grimm, Marcus O. W.; Zinser, Eva G.; Grösgen, Sven; Hundsdörfer, Benjamin; Rothhaar, Tatjana L.; Burg, Verena K.; Kaestner, Lars; Bayer, Thomas A.; Lipp, Peter; Müller, Ulrike; Grimm, Heike S.; Hartmann, Tobias

2012-01-01

Gangliosides are important players for controlling neuronal function and are directly involved in AD pathology. They are among the most potent stimulators of Aβ production, are enriched in amyloid plaques and bind amyloid beta (Aβ). However, the molecular mechanisms linking gangliosides with AD are unknown. Here we identified the previously unknown function of the amyloid precursor protein (APP), specifically its cleavage products Aβ and the APP intracellular domain (AICD), of regulating GD3-synthase (GD3S). Since GD3S is the key enzyme converting a- to b-series gangliosides, it therefore plays a major role in controlling the levels of major brain gangliosides. This regulation occurs by two separate and additive mechanisms. The first mechanism directly targets the enzymatic activity of GD3S: Upon binding of Aβ to the ganglioside GM3, the immediate substrate of the GD3S, enzymatic turnover of GM3 by GD3S was strongly reduced. The second mechanism targets GD3S expression. APP cleavage results, in addition to Aβ release, in the release of AICD, a known candidate for gene transcriptional regulation. AICD strongly down regulated GD3S transcription and knock-in of an AICD deletion mutant of APP in vivo, or knock-down of Fe65 in neuroblastoma cells, was sufficient to abrogate normal GD3S functionality. Equally, knock-out of the presenilin genes, presenilin 1 and presenilin 2, essential for Aβ and AICD production, or of APP itself, increased GD3S activity and expression and consequently resulted in a major shift of a- to b-series gangliosides. In addition to GD3S regulation by APP processing, gangliosides in turn altered APP cleavage. GM3 decreased, whereas the ganglioside GD3, the GD3S product, increased Aβ production, resulting in a regulatory feedback cycle, directly linking ganglioside metabolism with APP processing and Aβ generation. A central aspect of this homeostatic control is the reduction of GD3S activity via an Aβ-GM3 complex and AICD-mediated repression of GD3S transcription. PMID:22470521

Control of Aβ release from human neurons by differentiation status and RET signaling.

PubMed

Scholz, Diana; Chernyshova, Yana; Leist, Marcel

2013-01-01

Few studies have compared the processing of endogenous human amyloid precursor protein (APP) in younger and older neurons. Here, we characterized LUHMES cells as a human model to study Alzheimer's disease-related processes during neuronal maturation and aging. Differentiated LUHMES expressed and spontaneously processed APP via the secretase pathways, and they secreted amyloid β (Aβ) peptide. This was inhibited by cholesterol depletion or secretase inhibition, but not by block of tau phosphorylation. In vitro aged cells increased Aβ secretion without upregulation of APP or secretases. We identified the medium constituent glial cell line-derived neurotrophic factor (GDNF) as responsible for this effect. GDNF-triggered Aβ release was associated with rapid upregulation of the GDNF coreceptor "rearranged during transfection" (RET). Other direct (neurturin) or indirect (nerve growth factor) RET activators also increased Aβ, whereas different neurotrophins were ineffective. Downstream of RET, we found activation of protein kinase B (AKT) to be involved. Accordingly, inhibitors of the AKT regulator phosphatidylinositol-3-kinase completely blocked GDNF-triggered AKT phosphorylation and Aβ increase. This suggests that RET signaling affects Aβ release from aging neurons. Copyright © 2013 Elsevier Inc. All rights reserved.

APP with Kunitz type protease inhibitor domain (KPI) correlates with neuritic plaque density but not with cortical synaptophysin immunoreactivity in Alzheimer's disease and non-demented aged subjects: a multifactorial analysis.

PubMed

Zhan, S S; Sandbrink, R; Beyreuther, K; Schmitt, H P

1995-01-01

The formation of beta A4 amyloid protein in neuritic plaques in Alzheimer's disease (AD) and advanced age is a complex process that involves a number of both cellular and molecular mechanisms, the interrelations of which are not yet completely understood. We have examined quantitatively, in AD and aged controls an extended spectrum of amyloid plaque-related cellular and molecular factors and the cortical synaptophysin immunoreactivity (synaptic density) in order to check for interrelations between them by multifactorial analysis. In 3 cases of senile dementia of the Alzheimer type (SDAT) aged 72, 80 and 82 years, and 9 controls aged 43-88 (mean age 65) years, the cortical synaptophysin immunoreactivity was assessed, together with the numbers of neurons, astrocytes and microglial cells, senile plaques, of tangle-bearing neurons, and the amount of beta A4 amyloid precursor protein (APP) with and without the Kunitz type serine protease inhibitor (KPI) domain. The main results were: APP including the KPI domain (KPI-APP) correlated with the number of neuritic plaques, regardless of whether they occurred in SDAT or non-demented controls. There was no significant difference in the amount of KPI-APP between SDAT and controls. Conversely, APP695 (without KPI) was significantly reduced in SDAT. KPI-APP did not correlate with the synaptophysin immunoreactivity (RGVA), while APP695 showed a significant correlation with the latter in all evaluations. It also correlated with the neuron counts, which was not true for KPI-APP. These results support previous findings indicating that KPI-APP is an important local factor for amyloid deposition in the neuritic plaques, both in AD and in non-demented aged people. On the contrary, KPI-APP does not seem to be significantly involved in the mechanisms of synaptic change outside of the plaques.

Neuronal-Targeted TFEB Accelerates Lysosomal Degradation of APP, Reducing Aβ Generation and Amyloid Plaque Pathogenesis

PubMed Central

Xiao, Qingli; Yan, Ping; Ma, Xiucui; Liu, Haiyan; Perez, Ronaldo; Zhu, Alec; Gonzales, Ernesto; Tripoli, Danielle L.; Czerniewski, Leah; Ballabio, Andrea; Cirrito, John R.

2015-01-01

In AD, an imbalance between Aβ production and removal drives elevated brain Aβ levels and eventual amyloid plaque deposition. APP undergoes nonamyloidogenic processing via α-cleavage at the plasma membrane, amyloidogenic β- and γ-cleavage within endosomes to generate Aβ, or lysosomal degradation in neurons. Considering multiple reports implicating impaired lysosome function as a driver of increased amyloidogenic processing of APP, we explored the efficacy of targeting transcription factor EB (TFEB), a master regulator of lysosomal pathways, to reduce Aβ levels. CMV promoter-driven TFEB, transduced via stereotactic hippocampal injections of adeno-associated virus particles in APP/PS1 mice, localized primarily to neuronal nuclei and upregulated lysosome biogenesis. This resulted in reduction of APP protein, the α and β C-terminal APP fragments (CTFs), and in the steady-state Aβ levels in the brain interstitial fluid. In aged mice, total Aβ levels and amyloid plaque load were selectively reduced in the TFEB-transduced hippocampi. TFEB transfection in N2a cells stably expressing APP695, stimulated lysosome biogenesis, reduced steady-state levels of APP and α- and β-CTFs, and attenuated Aβ generation by accelerating flux through the endosome-lysosome pathway. Cycloheximide chase assays revealed a shortening of APP half-life with exogenous TFEB expression, which was prevented by concomitant inhibition of lysosomal acidification. These data indicate that TFEB enhances flux through lysosomal degradative pathways to induce APP degradation and reduce Aβ generation. Activation of TFEB in neurons is an effective strategy to attenuate Aβ generation and attenuate amyloid plaque deposition in AD. SIGNIFICANCE STATEMENT A key driver for AD pathogenesis is the net balance between production and clearance of Aβ, the major component of amyloid plaques. Here we demonstrate that lysosomal degradation of holo-APP influences Aβ production by limiting the availability of APP for amyloidogenic processing. Using viral gene transfer of transcription factor EB (TFEB), a master regulator of lysosome biogenesis in neurons of APP/PS1 mice, steady-state levels of APP were reduced, resulting in decreased interstitial fluid Aβ levels and attenuated amyloid deposits. These effects were caused by accelerated lysosomal degradation of endocytosed APP, reflected by reduced APP half-life and steady-state levels in TFEB-expressing cells, with resultant decrease in Aβ production and release. Additional studies are needed to explore the therapeutic potential of this approach. PMID:26338325

Epigenetic Induction of EGR-1 Expression by the Amyloid Precursor Protein during Exposure to Novelty

PubMed Central

Hendrickx, Aurélie; Pierrot, Nathalie; Tasiaux, Bernadette; Schakman, Olivier; Brion, Jean-Pierre; Kienlen-Campard, Pascal; De Smet, Charles; Octave, Jean-Noël

2013-01-01

Following transcriptome comparison of primary cultures isolated from brain of mice expressing or not the amyloid precursor protein APP, we found transcription of the EGR-1 gene to be regulated by APP. In primary cultures of cortical neurons, APP significantly down regulated EGR-1 expression at both mRNA and protein levels in a γ-secretase independent manner. The intracellular domain of APP did not interact with EGR-1 gene promoter, but enrichment of acetylated histone H4 at the EGR-1 promoter region was measured in APP-/- neurons, as well as in brain of APP-/- mice, in which increase in EGR-1 expression was also measured. These results argue for an important function of APP in the epigenetic regulation of EGR-1 gene transcription both in vitro and in vivo. In APP-/- mice, constitutive overexpression of EGR-1 in brain impaired epigenetic induction of this early transcriptional regulator during exposure to novelty. Altogether, these results indicate an important function of APP in the epigenetic regulation of the transcription of EGR-1, known to be important for memory formation. PMID:24066134

Amyloid Precursor Protein Haploinsufficiency Preferentially Mediates Brain Iron Accumulation in Mice Transgenic for The Huntington's Disease Mutation.

PubMed

Berggren, Kiersten; Agrawal, Sonal; Fox, Julia A; Hildenbrand, Justin; Nelson, Ryan; Bush, Ashley I; Fox, Jonathan H

2017-01-01

Huntington's disease (HD) is an autosomal dominant disorder caused by a CAG expansion in the huntingtin gene that results in expression of mutant huntingtin protein. Iron accumulates in HD brain neurons. Amyloid precursor protein (APP) promotes neuronal iron export. However, the role of APP in brain iron accumulation in HD is unclear. To determine the effects of APP insufficiency on HD in YAC128 mice. We crossed APP hemizygous mice (APP+/-) with YAC128 mice that are transgenic (Tg) for human mutant huntingtin (hmHTT) to generate APP+/+ hmHTT-/-, APP+/- hmHTT-/-, APP+/+ hmHTT+/- and APP+/- hmHTT+/- progeny. Mice were evaluated for behavioral, biochemical and neuropathology HD outcomes at 2-12 months of age. APP heterozygosity decreased cortical APP 25% and 60% in non-Tg and Tg mice, respectively. Cerebral and striatal iron levels were increased by APP knockdown in Tg mice only. Nest-building behavior was decreased in Tg mice; APP knockdown decreased nest building in non-Tg but not Tg mice. Rota-rod endurance was decreased in Tg mice. APP+/- hHTT+/- mice demonstrated additional decreases in rota-rod endurance from 4-10 months of age. Tg mice had smaller striatal volumes and fewer striatal neurons but were not affected by APP knockdown. APP heterozygosity results in greater decreases of cortical APP in Tg versus non-Tg mice. Mutant huntingtin transgenic mice develop brain iron accumulation as a result of greater suppression of APP levels. Elevated brain iron in Tg mice was associated with a decline in motor endurance consistent with a disease promoting effect of iron in the YAC128 model of human HD.

Natural Modulators of Amyloid-Beta Precursor Protein Processing

PubMed Central

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

The crystal structure of DR6 in complex with the amyloid precursor protein provides insight into death receptor activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Kai; Olsen, Olav; Tzvetkova-Robev, Dorothea

The amyloid precursor protein (APP) has garnered considerable attention due to its genetic links to Alzheimer's disease. Death receptor 6 (DR6) was recently shown to bind APP via the protein extracellular regions, stimulate axonal pruning, and inhibit synapse formation. Here, we report the crystal structure of the DR6 ectodomain in complex with the E2 domain of APP and show that it supports a model for APP-induced dimerization and activation of cell surface DR6.

The crystal structure of DR6 in complex with the amyloid precursor protein provides insight into death receptor activation

DOE PAGES

Xu, Kai; Olsen, Olav; Tzvetkova-Robev, Dorothea; ...

2015-04-02

The amyloid precursor protein (APP) has garnered considerable attention due to its genetic links to Alzheimer's disease. Death receptor 6 (DR6) was recently shown to bind APP via the protein extracellular regions, stimulate axonal pruning, and inhibit synapse formation. Here, we report the crystal structure of the DR6 ectodomain in complex with the E2 domain of APP and show that it supports a model for APP-induced dimerization and activation of cell surface DR6.

Herpes Simplex Virus Dances with Amyloid Precursor Protein while Exiting the Cell

PubMed Central

Cheng, Shi-Bin; Ferland, Paulette; Webster, Paul; Bearer, Elaine L.

2011-01-01

Herpes simplex type 1 (HSV1) replicates in epithelial cells and secondarily enters local sensory neuronal processes, traveling retrograde to the neuronal nucleus to enter latency. Upon reawakening newly synthesized viral particles travel anterograde back to the epithelial cells of the lip, causing the recurrent cold sore. HSV1 co-purifies with amyloid precursor protein (APP), a cellular transmembrane glycoprotein and receptor for anterograde transport machinery that when proteolyzed produces A-beta, the major component of senile plaques. Here we focus on transport inside epithelial cells of newly synthesized virus during its transit to the cell surface. We hypothesize that HSV1 recruits cellular APP during transport. We explore this with quantitative immuno-fluorescence, immuno-gold electron-microscopy and live cell confocal imaging. After synchronous infection most nascent VP26-GFP-labeled viral particles in the cytoplasm co-localize with APP (72.8+/−6.7%) and travel together with APP inside living cells (81.1+/−28.9%). This interaction has functional consequences: HSV1 infection decreases the average velocity of APP particles (from 1.1+/−0.2 to 0.3+/−0.1 µm/s) and results in APP mal-distribution in infected cells, while interplay with APP-particles increases the frequency (from 10% to 81% motile) and velocity (from 0.3+/−0.1 to 0.4+/−0.1 µm/s) of VP26-GFP transport. In cells infected with HSV1 lacking the viral Fc receptor, gE, an envelope glycoprotein also involved in viral axonal transport, APP-capsid interactions are preserved while the distribution and dynamics of dual-label particles differ from wild-type by both immuno-fluorescence and live imaging. Knock-down of APP with siRNA eliminates APP staining, confirming specificity. Our results indicate that most intracellular HSV1 particles undergo frequent dynamic interplay with APP in a manner that facilitates viral transport and interferes with normal APP transport and distribution. Such dynamic interactions between APP and HSV1 suggest a mechanistic basis for the observed clinical relationship between HSV1 seropositivity and risk of Alzheimer's disease. PMID:21483850

New Insights to Clathrin and Adaptor Protein 2 for the Design and Development of Therapeutic Strategies

PubMed Central

Poulsen, Ebbe Toftgaard; Larsen, Agnete; Zollo, Alen; Jørgensen, Arne L.; Sanggaard, Kristian W.; Enghild, Jan J.; Matrone, Carmela

2015-01-01

The Amyloid Precursor Protein (APP) has been extensively studied for its role as the precursor of the β-amyloid protein (Aβ) in Alzheimer’s disease (AD). However, our understanding of the normal function of APP is still patchy. Emerging evidence indicates that a dysfunction in APP trafficking and degradation can be responsible for neuronal deficits and progressive degeneration in humans. We recently reported that the Y682 mutation in the 682YENPTY687 domain of APP affects its binding to specific adaptor proteins and leads to its anomalous trafficking, to defects in the autophagy machinery and to neuronal degeneration. In order to identify adaptors that influence APP function, we performed pull-down experiments followed by quantitative mass spectrometry (MS) on hippocampal tissue extracts of three month-old mice incubated with either the 682YENPTY687 peptide, its mutated form, 682GENPTY687 or its phosphorylated form, 682pYENPTY687. Our experiments resulted in the identification of two proteins involved in APP internalization and trafficking: Clathrin heavy chain (hc) and its Adaptor Protein 2 (AP-2). Overall our results consolidate and refine the importance of Y682 in APP normal functions from an animal model of premature aging and dementia. Additionally, they open the perspective to consider Clathrin hc and AP-2 as potential targets for the design and development of new therapeutic strategies. PMID:26690411

X11/Mint Genes Control Polarized Localization of Axonal Membrane Proteins in Vivo

PubMed Central

Gross, Garrett G.; Lone, G. Mohiddin; Leung, Lok Kwan; Hartenstein, Volker

2013-01-01

Mislocalization of axonal proteins can result in misassembly and/or miswiring of neural circuits, causing disease. To date, only a handful of genes that control polarized localization of axonal membrane proteins have been identified. Here we report that Drosophila X11/Mint proteins are required for targeting several proteins, including human amyloid precursor protein (APP) and Drosophila APP-like protein (APPL), to axonal membranes and for their exclusion from dendrites of the mushroom body in Drosophila, a brain structure involved in learning and memory. Axonal localization of APP is mediated by an endocytic motif, and loss of X11/Mint results in a dramatic increase in cell-surface levels of APPL, especially on dendrites. Mutations in genes required for endocytosis show similar mislocalization of these proteins to dendrites, and strongly enhance defects seen in X11/Mint mutants. These results suggest that X11/Mint-dependent endocytosis in dendrites may serve to promote the axonal localization of membrane proteins. Since X11/Mint binds to APP, and abnormal trafficking of APP contributes to Alzheimer's disease, deregulation of X11/Mint may be important for Alzheimer's disease pathogenesis. PMID:23658195

Immunohistochemical localization of beta-amyloid precursor protein sequences in Alzheimer and normal brain tissue by light and electron microscopy.

PubMed

McGeer, P L; Akiyama, H; Kawamata, T; Yamada, T; Walker, D G; Ishii, T

1992-03-01

Immunohistochemical staining with antibodies directed against four segments of the amyloid precursor protein (APP) was studied by light and electron microscopy in normal and Alzheimer (AD) brain tissue. The segments according to the Kang et al. sequence were: 18-38 (T97); 527-540 (R36); 597-620 (1-24 of beta-amyloid protein [BAP], R17); and 681-695 (R37) (Kang et al. [1987]: Nature 325:733-736). The antibodies recognized full length APP in Western blots of extracts of APP transfected cells. They stained cytoplasmic granules in some pyramidal neurons in normal appearing tissue from control and AD cases. In AD affected tissue, the antibodies to amino terminal sections of APP stained tangled neurons and neuropil threads, and intensely stained dystrophic neurites in senile plaques. By electron microscopy, this staining was localized to abnormal filaments. The antibody to the carboxy terminal segment failed to stain neurofibrillary tangles or neuropil threads; it did stain some neurites with globular swellings. It also stained globular and elongated deposits in senile plaque areas. The antibody against the BAP intensely stained extracellular material in senile plaques and diffuse deposits. By electron microscopy, the antibodies all stained intramicroglial deposits. Some of the extracellular and intracellular BAP-positive deposits were fibrillary. Communication between intramicroglial and extracellular fibrils was detected in plaque areas. These data suggest the following sequence of events. APP is normally concentrated in intraneuronal granules. In AD, it accumulates in damaged neuronal fibers. The amino terminal portion binds to abnormal neurofilaments. Major fragments of APP are phagocytosed and processed by microglia with the BAP portion being preserved. The preserved BAP is then extruded and accumulates in extracellular tissue.

Insight into inhibition of the human amyloid beta protein precursor (APP: PDB ID ) using (E)-N-(pyridin-2-ylmethylene)arylamine (LR) models: structure elucidation of a family of ZnX2-LR complexes.

PubMed

Basu Baul, Tushar S; Kundu, Sajal; Singh, Palwinder; Shaveta; Guedes da Silva, M Fátima C

2015-02-07

The amyloid beta precursor protein (APP) and its neurotoxic cleavage product amyloid beta (Aβ) are a cause of Alzheimer's disease and appear essential for neuronal development and cell homeostasis. Proteolytic processing of APP is influenced by metal ions and protein ligands, however the structural and functional mechanism of APP regulation is not known so far. In this context, molecular modeling studies were performed to understand the molecular behavior of (E)-N-(pyridin-2-ylmethylene)arylamines (LR) with an E2 domain of the APP in its complex with zinc (APP; PDB ID: ). Docking results indeed confirmed that the LR interacts with Zn in the binding site of the protein between two α-helical chains. In view of these findings, LR was further investigated for complexation reactions with Zn(2+) in order to establish the structural models in solution and in the solid state. Five new Zn(2+) complexes of compositions viz. [Zn(Br)2(L2-Me)] (), [Zn(Br)2(L2-OMe)] (), [Zn(i)2(L2-OMe)] (), [Zn(NO3)2(L2-OMe)(H2O)] () and [Zn(L4-Me)2(H2O)2](NO3)2 () were synthesized and their structures were ascertained by microanalysis, IR and (1)H NMR spectroscopy, and single-crystal X-ray diffraction. The zinc atom in complex exhibits a distorted tetrahedral geometry while the crystal structures of complexes and show distorted square pyramidal geometries. The zinc cation in and has an octahedral coordination environment, but in the zinc coordination geometry is less distorted. The Zn(ii) cations take part in one ( and ) or two () 5-membered metallacycles imposed by the NN or NNO chelation modes of LR. The significant intermolecular ππ interactions are also discussed.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Shuxia; Zhou, Hua; Walian, Peter J.

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 HeLamore » 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, such as APP, CD44, DCC, ErbB4, E-cadherin, LRP, N-cadherin, Nectin-1, and Notch, within their transmembranous regions (2-11); therefore, in addition to its role in AD, {gamma}-secretase has been found to participate in other important biological functions, such as intracellular signaling. {gamma}-secretase processing of APP requires prior removal of a major fragment of the APP extracellular domain (sAPP{sub {beta}}) by {beta}-secretase to yield a membrane bound fragment (APP CTF{sub {beta}}). Subsequent cleavage of this membrane bound fragment by {gamma}-secretase results in the release of the Alzheimer's disease (AD) associated amyloid {beta}-peptides (12). The proteolytic activity of {gamma}-secretase is found not to be critically dependent on the specific sequence, but instead on the size of the extracellular domain (13); such sequence independent characteristics of the substrate are reminiscent of those of the 26S proteasome complex that cleaves substrates in a non-sequence specific manner. {gamma}-secretase is present in almost all animal species, vertebrates and invertebrates; it is expressed in many human organs and tissues.« less

Biotin-c10-AppCH2ppA is an effective new chemical proteomics probe for diadenosine polyphosphate binding proteins.

PubMed

Azhar, M Ameruddin; Wright, Michael; Kamal, Ahmed; Nagy, Judith; Miller, Andrew D

2014-07-01

Here we report on the synthesis of a synthetic, stable biotin-c10-AppCH2ppA conjugate involving an unusual Cannizzaro reaction step. This conjugate is used to bind prospective Ap4A binding proteins from Escherichia coli bacterial cell lyzates. Following binding, identities of these proteins are then determined smoothly by a process of magnetic bio-panning and electrospray mass spectrometry. Protein hits appear to be a definitive set of stress protein related targets. While this hit list may not be exclusive, and may vary with the nature of sampling conditions and organism status, nevertheless hits do appear to correspond with bona fide Ap4A-binding proteins. Therefore these hits represent a sound basis on which to construct new hypotheses concerning the cellular importance of Ap4A to bacterial cells and the potential biological significance of Ap4A-protein binding interactions. Copyright © 2014. Published by Elsevier Ltd.

Oxidative Stress and Hypoxia Contribute to Alzheimer's Disease Pathogenesis: Two Sides of the Same Coin

PubMed Central

Guglielmotto, Michela; Tamagno, Elena; Danni, Oliviero

2009-01-01

While it is well established that stroke and cerebral hypoperfusion are risk factors for Alzheimer's disease (AD), the molecular link between ischemia/hypoxia and amyloid precursor protein (APP) processing has only been recently established. Here we review the role of the release of reactive oxygen species (ROS) by the mitochondrial electron chain in response to hypoxia, providing evidence that hypoxia fosters the amyloidogenic APP processing through a biphasic mechanism that up-regulates β-secretase activity, which involves an early release of ROS and an activation of HIF-1α. PMID:19705038

Meat juice: An alternative matrix for assessing animal health by measuring acute phase proteins. Correlations of pig-MAP and haptoglobin concentrations in pig meat juice and plasma.

PubMed

Piñeiro, M; Gymnich, S; Knura, S; Piñeiro, C; Petersen, B

2009-10-01

Quantification of acute phase proteins (APPs) in blood can be used for monitoring animal health and welfare on farms, and could be also of interest for the detection of diseased animals during the meat inspection process. However serum or plasma is not always available for end-point analysis at slaughter. Meat juice might provide an adequate, alternative matrix that can be easily obtained for post-mortem analysis at abattoirs. The concentrations of pig Major Acute phase Protein (pig-MAP) and haptoglobin, two of the main APPs in pigs, were determined in approximately 300 paired samples of plasma and meat juice from the diaphragm (pars costalis), obtained after freezing and thawing the muscle. APPs concentrations in meat juice were closely correlated to those in plasma (r=0.695 for haptoglobin, r=0.858 for pig-MAP, p<0.001). These results open new possibilities for the assessment of animal health in pig production, with implications for food safety and meat quality.

Evidence that the C-terminus of Human Presenilin 1 is Located in the Extra-cytoplasmic Space

PubMed Central

James Turner, R.

2005-01-01

The polytopic membrane protein presenilin 1 (PS1) is a component of the γ-secretase complex that is responsible for the intramembranous cleavage of a number of type I transmembrane proteins including the β-amyloid precursor protein (APP). Mutations of PS1, apparently leading to aberrant processing of APP, have been genetically linked to early-onset familial Alzheimer's disease. PS1 contains ten hydrophobic regions (HRs) sufficiently long to be α-helical membrane spanning segments. Most topology models for PS1 place its C-terminal ∼40 amino acids, which include the 10th HR, in the cytosolic space. However, several recent observations suggest that HR 10 may be integrated into the membrane and involved in the interaction between PS1 and APP. We have applied three independent methodologies to investigate the location of HR 10 and the extreme C-terminus of PS1. The results from these methods indicate that HR 10 spans the membrane and that the C-terminal amino acids of PS1 lie in the extra-cytoplasmic space. PMID:15843437

Neurodegeneration in Alzheimer disease: role of amyloid precursor protein and presenilin 1 intracellular signaling.

PubMed

Nizzari, Mario; Thellung, Stefano; Corsaro, Alessandro; Villa, Valentina; Pagano, Aldo; Porcile, Carola; Russo, Claudio; Florio, Tullio

2012-01-01

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.

Amyloid-β Precursor Protein Modulates the Sorting of Testican-1 and Contributes to Its Accumulation in Brain Tissue and Cerebrospinal Fluid from Patients with Alzheimer Disease.

PubMed

Barrera-Ocampo, Alvaro; Arlt, Sönke; Matschke, Jakob; Hartmann, Ursula; Puig, Berta; Ferrer, Isidre; Zürbig, Petra; Glatzel, Markus; Sepulveda-Falla, Diego; Jahn, Holger

2016-09-01

The mechanisms leading to amyloid-β (Aβ) accumulation in sporadic Alzheimer disease (AD) are unknown but both increased production or impaired clearance likely contribute to aggregation. To understand the potential roles of the extracellular matrix proteoglycan Testican-1 in the pathophysiology of AD, we used samples from AD patients and controls and an in vitro approach. Protein expression analysis showed increased levels of Testican-1 in frontal and temporal cortex of AD patients; histological analysis showed that Testican-1 accumulates and co-aggregates with Aβ plaques in the frontal, temporal and entorhinal cortices of AD patients. Proteomic analysis identified 10 fragments of Testican-1 in cerebrospinal fluid (CSF) from AD patients. HEK293T cells expressing human wild type or mutant Aβ precursor protein (APP) were transfected with Testican-1. The co-expression of both proteins modified the sorting of Testican-1 into the endocytic pathway leading to its transient accumulation in Golgi, which seemed to affect APP processing, as indicated by reduced Aβ40 and Aβ42 levels in APP mutant cells. In conclusion, patient data reflect a clearance impairment that may favor Aβ accumulation in AD brains and our in vitro model supports the notion that the interaction between APP and Testican-1 may be a key step in the production and aggregation of Aβ species. © 2016 Oxford University Press OR American Association of Neuropathologists.

A novel snRNA-like transcript affects amyloidogenesis and cell cycle progression through perturbation of Fe65L1 (APBB2) alternative splicing.

PubMed

Penna, Ilaria; Vassallo, Irene; Nizzari, Mario; Russo, Debora; Costa, Delfina; Menichini, Paola; Poggi, Alessandro; Russo, Claudio; Dieci, Giorgio; Florio, Tullio; Cancedda, Ranieri; Pagano, Aldo

2013-06-01

FE65 proteins constitute a family of adaptors which modulates the processing of amyloid precursor protein and the consequent amyloid β production. Thus, they have been involved in the complex and partially unknown cascade of reactions at the base of Alzheimer's disease etiology. However, FE65 and FE65-like proteins may be linked to neurodegeneration through the regulation of cell cycle in post-mitotic neurons. In this work we disclose novel molecular mechanisms by which APBB2 can modulate APP processing. We show that APBB2 mRNA splicing, driven by the over-expression of a novel non-coding RNA named 45A, allow the generation of alternative protein forms endowed with differential effects on Aβ production, cell cycle control, and DNA damage response. 45A overexpression also favors cell transformation and tumorigenesis leading to a marked increase of malignancy of neuroblastoma cells. Therefore, our results highlight a novel regulatory pathway of considerable interest linking APP processing with cell cycle regulation and DNA-surveillance systems, that may represent a molecular mechanism to induce neurodegeneration in post-mitotic neurons. Copyright © 2013 Elsevier B.V. All rights reserved.

Multisite tyrosine phosphorylation of the N-terminus of Mint1/X11α by Src kinase regulates the trafficking of amyloid precursor protein.

PubMed

Dunning, Christopher J R; Black, Hannah L; Andrews, Katie L; Davenport, Elizabeth C; Conboy, Michael; Chawla, Sangeeta; Dowle, Adam A; Ashford, David; Thomas, Jerry R; Evans, Gareth J O

2016-05-01

Mint/X11 is one of the four neuronal trafficking adaptors that interact with amyloid precursor protein (APP) and are linked with its cleavage to generate β-amyloid peptide, a key player in the pathology of Alzheimer's disease. How APP switches between adaptors at different stages of the secretory pathway is poorly understood. Here, we show that tyrosine phosphorylation of Mint1 regulates the destination of APP. A canonical SH2-binding motif ((202) YEEI) was identified in the N-terminus of Mint1 that is phosphorylated on tyrosine by C-Src and recruits the active kinase for sequential phosphorylation of further tyrosines (Y191 and Y187). A single Y202F mutation in the Mint1 N-terminus inhibits C-Src binding and tyrosine phosphorylation. Previous studies observed that co-expression of wild-type Mint1 and APP causes accumulation of APP in the trans-Golgi. Unphosphorylatable Mint1 (Y202F) or pharmacological inhibition of Src reduced the accumulation of APP in the trans-Golgi of heterologous cells. A similar result was observed in cultured rat hippocampal neurons where Mint1(Y202F) permitted the trafficking of APP to more distal neurites than the wild-type protein. These data underline the importance of the tyrosine phosphorylation of Mint1 as a critical switch for determining the destination of APP. The regulation of amyloid precursor protein (APP) trafficking is poorly understood. We have discovered that the APP adapter, Mint1, is phosphorylated by C-Src kinase. Mint1 causes APP accumulation in the trans-Golgi network, whereas inhibition of Src or mutation of Mint1-Y202 permits APP recycling. The phosphorylation status of Mint1 could impact on the pathological trafficking of APP in Alzheimer's disease. © 2016 The Authors. Journal of Neurochemistry published by John Wiley & Sons Ltd on behalf of International Society for Neurochemistry.

Iron overload accelerates neuronal amyloid-β production and cognitive impairment in transgenic mice model of Alzheimer's disease.

PubMed

Becerril-Ortega, Javier; Bordji, Karim; Fréret, Thomas; Rush, Travis; Buisson, Alain

2014-10-01

Iron dyshomeostasis is proving increasingly likely to be involved in the pathology of Alzheimer's disease (AD); yet, its mechanism is not well understood. Here, we investigated the AD-related mechanism(s) of iron-sulfate exposure in vitro and in vivo, using cultured primary cortical neurons and APP/PS1 AD-model mice, respectively. In both systems, we observed iron-induced disruptions of amyloid precursor protein (APP) processing, neuronal signaling, and cognitive behavior. Iron overload increased production of amyloidogenic KPI-APP and amyloid beta. Further, this APP misprocessing was blocked by MK-801 in vitro, suggesting the effect was N-methyl-D-aspartate receptor (NMDAR) dependent. Calcium imaging confirmed that 24 hours iron exposure led to disrupted synaptic signaling by augmenting GluN2B-containing NMDAR expression-GluN2B messenger RNA and protein levels were increased and promoting excessing extrasynaptic NMDAR signaling. The disrupted GluN2B expression was concurrent with diminished expression of the splicing factors, sc35 and hnRNPA1. In APP/PS1 mice, chronic iron treatment led to hastened progression of cognitive impairment with the novel object recognition discrimination index, revealing a deficit at the age of 4 months, concomitant with augmented GluN2B expression. Together, these data suggest iron-induced APP misprocessing and hastened cognitive decline occur through inordinate extrasynaptic NMDAR activation. Copyright © 2014 Elsevier Inc. All rights reserved.

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.

PubMed

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.

Hippocampal mutant APP and amyloid beta-induced cognitive decline, dendritic spine loss, defective autophagy, mitophagy and mitochondrial abnormalities in a mouse model of Alzheimer's disease.

PubMed

Manczak, Maria; Kandimalla, Ramesh; Yin, Xiangling; Reddy, P Hemachandra

2018-04-15

The purpose of our study was to determine the toxic effects of hippocampal mutant APP and amyloid beta (Aβ) in 12-month-old APP transgenic mice. Using rotarod and Morris water maze tests, immunoblotting and immunofluorescence, Golgi-cox staining and transmission electron microscopy, we assessed cognitive behavior, protein levels of synaptic, autophagy, mitophagy, mitochondrial dynamics, biogenesis, dendritic protein MAP2 and quantified dendritic spines and mitochondrial number and length in 12-month-old APP mice that express Swedish mutation. Mitochondrial function was assessed by measuring the levels of hydrogen peroxide, lipid peroxidation, cytochrome c oxidase activity and mitochondrial ATP. Morris water maze and rotarod tests revealed that hippocampal learning and memory and motor learning and coordination were impaired in APP mice relative to wild-type (WT) mice. Increased levels of mitochondrial fission proteins, Drp1 and Fis1 and decreased levels of fusion (Mfn1, Mfn2 and Opa1) biogenesis (PGC1α, NRF1, NRF2 and TFAM), autophagy (ATG5 and LC3BI, LC3BII), mitophagy (PINK1 and TERT), synaptic (synaptophysin and PSD95) and dendritic (MAP2) proteins were found in 12-month-old APP mice relative to age-matched non-transgenic WT mice. Golgi-cox staining analysis revealed that dendritic spines are significantly reduced. Transmission electron microscopy revealed significantly increased mitochondrial numbers and reduced mitochondrial length in APP mice. These findings suggest that hippocampal accumulation of mutant APP and Aβ is responsible for abnormal mitochondrial dynamics and defective biogenesis, reduced MAP2, autophagy, mitophagy and synaptic proteins and reduced dendritic spines and hippocampal-based learning and memory impairments, and mitochondrial structural and functional changes in 12-month-old APP mice.

Neuronal-Targeted TFEB Accelerates Lysosomal Degradation of APP, Reducing Aβ Generation and Amyloid Plaque Pathogenesis.

PubMed

Xiao, Qingli; Yan, Ping; Ma, Xiucui; Liu, Haiyan; Perez, Ronaldo; Zhu, Alec; Gonzales, Ernesto; Tripoli, Danielle L; Czerniewski, Leah; Ballabio, Andrea; Cirrito, John R; Diwan, Abhinav; Lee, Jin-Moo

2015-09-02

In AD, an imbalance between Aβ production and removal drives elevated brain Aβ levels and eventual amyloid plaque deposition. APP undergoes nonamyloidogenic processing via α-cleavage at the plasma membrane, amyloidogenic β- and γ-cleavage within endosomes to generate Aβ, or lysosomal degradation in neurons. Considering multiple reports implicating impaired lysosome function as a driver of increased amyloidogenic processing of APP, we explored the efficacy of targeting transcription factor EB (TFEB), a master regulator of lysosomal pathways, to reduce Aβ levels. CMV promoter-driven TFEB, transduced via stereotactic hippocampal injections of adeno-associated virus particles in APP/PS1 mice, localized primarily to neuronal nuclei and upregulated lysosome biogenesis. This resulted in reduction of APP protein, the α and β C-terminal APP fragments (CTFs), and in the steady-state Aβ levels in the brain interstitial fluid. In aged mice, total Aβ levels and amyloid plaque load were selectively reduced in the TFEB-transduced hippocampi. TFEB transfection in N2a cells stably expressing APP695, stimulated lysosome biogenesis, reduced steady-state levels of APP and α- and β-CTFs, and attenuated Aβ generation by accelerating flux through the endosome-lysosome pathway. Cycloheximide chase assays revealed a shortening of APP half-life with exogenous TFEB expression, which was prevented by concomitant inhibition of lysosomal acidification. These data indicate that TFEB enhances flux through lysosomal degradative pathways to induce APP degradation and reduce Aβ generation. Activation of TFEB in neurons is an effective strategy to attenuate Aβ generation and attenuate amyloid plaque deposition in AD. A key driver for AD pathogenesis is the net balance between production and clearance of Aβ, the major component of amyloid plaques. Here we demonstrate that lysosomal degradation of holo-APP influences Aβ production by limiting the availability of APP for amyloidogenic processing. Using viral gene transfer of transcription factor EB (TFEB), a master regulator of lysosome biogenesis in neurons of APP/PS1 mice, steady-state levels of APP were reduced, resulting in decreased interstitial fluid Aβ levels and attenuated amyloid deposits. These effects were caused by accelerated lysosomal degradation of endocytosed APP, reflected by reduced APP half-life and steady-state levels in TFEB-expressing cells, with resultant decrease in Aβ production and release. Additional studies are needed to explore the therapeutic potential of this approach. Copyright © 2015 the authors 0270-6474/15/3512137-15$15.00/0.

Amyloid precursor protein and Presenilin 1 interaction studied by FRET in human H4 cells.

PubMed

Nizzari, Mario; Venezia, Valentina; Bianchini, Paolo; Caorsi, Valentina; Diaspro, Alberto; Repetto, Emanuela; Thellung, Stefano; Corsaro, Alessandro; Carlo, Pia; Schettini, Gennaro; Florio, Tullio; Russo, Claudio

2007-01-01

The mayor pathologic hallmarks of Alzheimer's disease (AD) are senile plaque and neurofibrillary tangles. Senile plaque are primarily made up of deposits of amyloid-beta protein, a proteolytic product derived from the amyloid precursor protein (APP). APP is a transmembrane protein detected into the endoplasmic reticulum, in the Golgi apparatus, at the cell surface, recycled by endocytosis to endosomes, whose physiological function is unclear. Presenilins (PS), are a component of gamma-secretase complex that cleave alpha-CTFs (carboxy-terminal fragment), or beta-CTFs, leaving 40 or 42 amino acids amyloid-beta peptides and 58 or 56 amino acids intracellular domains (AICD). Where the amyloid-beta peptides is generated is not clear. The study of APP-PS interaction in specific cell compartments provides a good opportunity to light upon the molecular mechanisms regulating the activity of the "gamma-secretase complex," and where beta-amyloid is generated. In our study we used a biophysical assay of protein proximity: fluorescence resonance energy transfer (FRET), that can provide information about molecular interactions when two proteins are in the close proximity (<10 nm), to examine the subcellular localization and interaction between APP and PS1 in human neuroglioma cells (H4). Confocal microscopic analysis reveals extensive colocalization in different cells' compartment, and centrosomal or microtubule organizing center (MTOC) localization of APP and PS1, but not necessarily a close molecular interaction. We used FRET to determine if APP and PS1 interact at the cell centrosome. FRET data suggest a close interaction between APP and PS1 in subcellular compartments and at the centrosome of H4 cells. Using this approach we show that APP and PS1 are closely associated in the centrosomes of the H4 cell.

BACE1 elevation engendered by GGA3 deletion increases β-amyloid pathology in association with APP elevation and decreased CHL1 processing in 5XFAD mice.

PubMed

Kim, WonHee; Ma, Liang; Lomoio, Selene; Willen, Rachel; Lombardo, Sylvia; Dong, Jinghui; Haydon, Philip G; Tesco, Giuseppina

2018-02-02

β-site amyloid precursor protein cleaving enzyme 1 (BACE1) is the rate-limiting enzyme in the production of amyloid beta (Aβ), the toxic peptide that accumulates in the brains of Alzheimer's disease (AD) patients. Our previous studies have shown that the clathrin adaptor Golgi-localized γ-ear-containing ARF binding protein 3 (GGA3) plays a key role in the trafficking of BACE1 to lysosomes, where it is normally degraded. GGA3 depletion results in BACE1 stabilization both in vitro and in vivo. Moreover, levels of GGA3 are reduced and inversely related to BACE1 levels in post-mortem brains of AD patients. In order to assess the effect of GGA3 deletion on AD-like phenotypes, we crossed GGA3 -/- mice with 5XFAD mice. BACE1-mediated processing of APP and the cell adhesion molecule L1 like protein (CHL1) was measured as well as levels of Aβ42 and amyloid burden. In 5XFAD mice, we found that hippocampal and cortical levels of GGA3 decreased while BACE1 levels increased with age, similar to what is observed in human AD brains. GGA3 deletion prevented age-dependent elevation of BACE1 in GGA3KO;5XFAD mice. We also found that GGA3 deletion resulted in increased hippocampal levels of Aβ42 and amyloid burden in 5XFAD mice at 12 months of age. While levels of BACE1 did not change with age and gender in GGAKO;5XFAD mice, amyloid precursor protein (APP) levels increased with age and were higher in female mice. Moreover, elevation of APP was associated with a decreased BACE1-mediated processing of CHL1 not only in 12 months old 5XFAD mice but also in human brains from subjects affected by Down syndrome, most likely due to substrate competition. This study demonstrates that GGA3 depletion is a leading candidate mechanism underlying elevation of BACE1 in AD. Furthermore, our findings suggest that BACE1 inhibition could exacerbate mechanism-based side effects in conditions associated with APP elevation (e.g. Down syndrome) owing to impairment of BACE1-mediated processing of CHL1. Therefore, therapeutic approaches aimed to restore GGA3 function and to prevent the down stream effects of its depletion (e.g. BACE1 elevation) represent an attractive alternative to BACE inhibition for the prevention/treatment of AD.

SAP97-mediated ADAM10 trafficking from Golgi outposts depends on PKC phosphorylation

PubMed Central

Saraceno, C; Marcello, E; Di Marino, D; Borroni, B; Claeysen, S; Perroy, J; Padovani, A; Tramontano, A; Gardoni, F; Di Luca, M

2014-01-01

A disintegrin and metalloproteinase 10 (ADAM10) is the major α-secretase that catalyzes the amyloid precursor protein (APP) ectodomain shedding in the brain and prevents amyloid formation. Its activity depends on correct intracellular trafficking and on synaptic membrane insertion. Here, we describe that in hippocampal neurons the synapse-associated protein-97 (SAP97), an excitatory synapse scaffolding element, governs ADAM10 trafficking from dendritic Golgi outposts to synaptic membranes. This process is mediated by a previously uncharacterized protein kinase C phosphosite in SAP97 SRC homology 3 domain that modulates SAP97 association with ADAM10. Such mechanism is essential for ADAM10 trafficking from the Golgi outposts to the synapse, but does not affect ADAM10 transport from the endoplasmic reticulum. Notably, this process is altered in Alzheimer's disease brains. These results help in understanding the mechanism responsible for the modulation of ADAM10 intracellular path, and can constitute an innovative therapeutic strategy to finely tune ADAM10 shedding activity towards APP. PMID:25429624

Mutant APP and Amyloid beta-induced defective autophagy, mitophagy, mitochondrial structural and functional changes and synaptic damage in hippocampal neurons from Alzheimer's disease.

PubMed

Reddy, P Hemachandra; Yin, XiangLin; Manczak, Maria; Kumar, Subodh; Jangampalli Adi, Pradeepkiran; Vijayan, Murali; Reddy, Arubala P

2018-04-25

The purpose of our study was to determine the toxic effects of hippocampal mutant APP and amyloid beta (Aβ) in human mutant APP (mAPP) cDNA transfected with primary mouse hippocampal neurons (HT22). Hippocampal tissues are the best source of studying learning and memory functions in patients with Alzheimer's disease (AD) and healthy controls. However, investigating immortalized hippocampal neurons that express AD proteins provide an excellent opportunity for drug testing. Using quantitative RT-PCR, immunoblotting & immunofluorescence, and transmission electron microscopy, we assessed mRNA and protein levels of synaptic, autophagy, mitophagy, mitochondrial dynamics, biogenesis, dendritic protein MAP2, and assessed mitochondrial number and length in mAPP-HT22 cells that express Swedish/Indiana mutations. Mitochondrial function was assessed by measuring the levels of hydrogen peroxide, lipid peroxidation, cytochrome c oxidase activity and mitochondrial ATP. Increased levels of mRNA and protein levels of mitochondrial fission genes, Drp1 and Fis1 and decreased levels fusion (Mfn1, Mfn2 and Opa1) biogenesis (PGC1α, NRF1, NRF2 & TFAM), autophagy (ATG5 & LC3BI, LC3BII), mitophagy (PINK1 & TERT, BCL2 & BNIPBL), synaptic (synaptophysin & PSD95) and dendritic (MAP2) genes were found in mAPP-HT22 cells relative to WT-HT22 cells. Cell survival was significantly reduced mAPP-HT22 cells. GTPase-Dp1 enzymatic activity was increased in mAPP-HT22 cells. Transmission electron microscopy revealed significantly increased mitochondrial numbers and reduced mitochondrial length in mAPP-HT22 cells. These findings suggest that hippocampal accumulation of mutant APP and Aβ is responsible for abnormal mitochondrial dynamics and defective biogenesis, reduced MAP2, autophagy, mitophagy and synaptic proteins & reduced dendritic spines and mitochondrial structural and functional changes in mutant APP hippocampal cells. These observations strongly suggest that accumulation of mAPP and Aβ causes mitochondrial, synaptic and autophagy/mitophagy abnormalities in hippocampal neurons, leading to neuronal dysfunction.

Citrulline diet supplementation improves specific age-related raft changes in wild-type rodent hippocampus.

PubMed

Marquet-de Rougé, Perrine; Clamagirand, Christine; Facchinetti, Patricia; Rose, Christiane; Sargueil, Françoise; Guihenneuc-Jouyaux, Chantal; Cynober, Luc; Moinard, Christophe; Allinquant, Bernadette

2013-10-01

The levels of molecules crucial for signal transduction processing change in the brain with aging. Lipid rafts are membrane microdomains involved in cell signaling. We describe here substantial biophysical and biochemical changes occurring within the rafts in hippocampus neurons from aging wild-type rats and mice. Using continuous sucrose density gradients, we observed light-, medium-, and heavy raft subpopulations in young adult rodent hippocampus neurons containing very low levels of amyloid precursor protein (APP) and almost no caveolin-1 (CAV-1). By contrast, old rodents had a homogeneous age-specific high-density caveolar raft subpopulation containing significantly more cholesterol (CHOL), CAV-1, and APP. C99-APP-Cter fragment detection demonstrates that the first step of amyloidogenic APP processing takes place in this caveolar structure during physiological aging of the rat brain. In this age-specific caveolar raft subpopulation, levels of the C99-APP-Cter fragment are exponentially correlated with those of APP, suggesting that high APP concentrations may be associated with a risk of large increases in beta-amyloid peptide levels. Citrulline (an intermediate amino acid of the urea cycle) supplementation in the diet of aged rats for 3 months reduced these age-related hippocampus raft changes, resulting in raft patterns tightly close to those in young animals: CHOL, CAV-1, and APP concentrations were significantly lower and the C99-APP-Cter fragment was less abundant in the heavy raft subpopulation than in controls. Thus, we report substantial changes in raft structures during the aging of rodent hippocampus and describe new and promising areas of investigation concerning the possible protective effect of citrulline on brain function during aging.

Amyloid precursor protein-induced axonopathies are independent of amyloid-beta peptides.

PubMed

Stokin, Gorazd B; Almenar-Queralt, Angels; Gunawardena, Shermali; Rodrigues, Elizabeth M; Falzone, Tomás; Kim, Jungsu; Lillo, Concepción; Mount, Stephanie L; Roberts, Elizabeth A; McGowan, Eileen; Williams, David S; Goldstein, Lawrence S B

2008-11-15

Overexpression of amyloid precursor protein (APP), as well as mutations in the APP and presenilin genes, causes rare forms of Alzheimer's disease (AD). These genetic changes have been proposed to cause AD by elevating levels of amyloid-beta peptides (Abeta), which are thought to be neurotoxic. Since overexpression of APP also causes defects in axonal transport, we tested whether defects in axonal transport were the result of Abeta poisoning of the axonal transport machinery. Because directly varying APP levels also alters APP domains in addition to Abeta, we perturbed Abeta generation selectively by combining APP transgenes in Drosophila and mice with presenilin-1 (PS1) transgenes harboring mutations that cause familial AD (FAD). We found that combining FAD mutant PS1 with FAD mutant APP increased Abeta42/Abeta40 ratios and enhanced amyloid deposition as previously reported. Surprisingly, however, this combination suppressed rather than increased APP-induced axonal transport defects in both Drosophila and mice. In addition, neuronal apoptosis induced by expression of FAD mutant human APP in Drosophila was suppressed by co-expressing FAD mutant PS1. We also observed that directly elevating Abeta with fusions to the Familial British and Danish Dementia-related BRI protein did not enhance axonal transport phenotypes in APP transgenic mice. Finally, we observed that perturbing Abeta ratios in the mouse by combining FAD mutant PS1 with FAD mutant APP did not enhance APP-induced behavioral defects. A potential mechanism to explain these findings was suggested by direct analysis of axonal transport in the mouse, which revealed that axonal transport or entry of APP into axons is reduced by FAD mutant PS1. Thus, we suggest that APP-induced axonal defects are not caused by Abeta.

3DProIN: Protein-Protein Interaction Networks and Structure Visualization.

PubMed

Li, Hui; Liu, Chunmei

2014-06-14

3DProIN is a computational tool to visualize protein-protein interaction networks in both two dimensional (2D) and three dimensional (3D) view. It models protein-protein interactions in a graph and explores the biologically relevant features of the tertiary structures of each protein in the network. Properties such as color, shape and name of each node (protein) of the network can be edited in either 2D or 3D views. 3DProIN is implemented using 3D Java and C programming languages. The internet crawl technique is also used to parse dynamically grasped protein interactions from protein data bank (PDB). It is a java applet component that is embedded in the web page and it can be used on different platforms including Linux, Mac and Window using web browsers such as Firefox, Internet Explorer, Chrome and Safari. It also was converted into a mac app and submitted to the App store as a free app. Mac users can also download the app from our website. 3DProIN is available for academic research at http://bicompute.appspot.com.

Toward a reliable distinction between patients with mild cognitive impairment and Alzheimer-type dementia versus major depression.

PubMed

Post, Anke; Ackl, Nibal; Rücker, Monika; Schreiber, Yvonne; Binder, Elisabeth B; Ising, Marcus; Sonntag, Annette; Holsboer, Florian; Almeida, Osborne F X

2006-05-01

Cerebrospinal fluid (CSF) levels of soluble amyloid precursor protein (sAPP) and its alpha-secreted form (alpha-sAPP) were investigated as a means to distinguish between individuals with mild cognitive impairment (MCI) and Alzheimer-type dementia (DAT) and those with major depressive episode (MDE) showing secondary memory deficits. Twenty-seven patients with MCI, 32 with probable DAT, and 24 with MDE attending a memory clinic were studied. Cerebrospinal fluid levels of sAPP/amyloid precursor-like protein 2 (APLP2) and alpha-sAPP were detected by Western blotting. Patients with MDE had the highest CSF levels of total sAPP/APLP2 as compared with MCI and DAT patients (p < .001); sAPP/APLP2 levels were higher in MCI than in DAT subjects. Whereas alpha-sAPP levels did not differ between the MCI and DAT groups, median levels of this peptide were significantly lower in MCI and DAT versus MDE patients. Soluble amyloid precursor protein/APLP2 and alpha-sAPP concentrations in CSF can differentiate between DAT and MCI versus MDE, facilitating early ameliorative interventions and appropriate treatment regimens.

Bacteriophage T4 capsid packaging and unpackaging of DNA and proteins.

PubMed

Mullaney, Julienne M; Black, Lindsay W

2014-01-01

Bacteriophage T4 has proven itself readily amenable to phage-based DNA and protein packaging, expression, and display systems due to its physical resiliency and genomic flexibility. As a large dsDNA phage with dispensable internal proteins and dispensable outer capsid proteins it can be adapted to package both DNA and proteins of interest within the capsid and to display peptides and proteins externally on the capsid. A single 170 kb linear DNA, or single or multiple copies of shorter linear DNAs, of any sequence can be packaged by the large terminase subunit in vitro into protein-containing proheads and give full or partially full capsids. The prohead receptacles for DNA packaging can also display peptides or full-length proteins from capsid display proteins HOC and SOC. Our laboratory has also developed a protein expression, packaging, and processing (PEPP) system which we have found to have advantages over mammalian and bacterial cell systems, including high yield, increased stability, and simplified downstream processing. Proteins that we have produced by the phage PEPP platform include human HIV-1 protease, micrococcal endonuclease from Staphylococcus aureus, restriction endonuclease EcoRI, luciferase, human granulocyte colony stimulating factor (GCSF), green fluorescent protein (GFP), and the 99 amino acid C-terminus of amyloid precursor protein (APP). Difficult to produce proteins that are toxic in mammalian protein expression systems are easily produced, packaged, and processed with the PEPP platform. APP is one example of such a highly refractory protein that has been produced successfully. The methods below describe the procedures for in vitro packaging of proheads with DNA and for producing recombinant T4 phage that carry a gene of interest in the phage genome and produce and internally package the corresponding protein of interest.

Intracellular APP Domain Regulates Serine-Palmitoyl-CoA Transferase Expression and Is Affected in Alzheimer's Disease

PubMed Central

Grimm, Marcus O. W.; Grösgen, Sven; Rothhaar, Tatjana L.; Burg, Verena K.; Hundsdörfer, Benjamin; Haupenthal, Viola J.; Friess, Petra; Müller, Ulrike; Fassbender, Klaus; Riemenschneider, Matthias; Grimm, Heike S.; Hartmann, Tobias

2011-01-01

Lipids play an important role as risk or protective factors in Alzheimer's disease (AD), a disease biochemically characterized by the accumulation of amyloid beta peptides (Aβ), released by proteolytic processing of the amyloid precursor protein (APP). Changes in sphingolipid metabolism have been associated to the development of AD. The key enzyme in sphingolipid de novo synthesis is serine-palmitoyl-CoA transferase (SPT). In the present study we identified a new physiological function of APP in sphingolipid synthesis. The APP intracellular domain (AICD) was found to decrease the expression of the SPT subunit SPTLC2, the catalytic subunit of the SPT heterodimer, resulting in that decreased SPT activity. AICD function was dependent on Fe65 and SPTLC2 levels are increased in APP knock-in mice missing a functional AICD domain. SPTLC2 levels are also increased in familial and sporadic AD postmortem brains, suggesting that SPT is involved in AD pathology. PMID:21660213

Glycogen Synthase Kinase 3 Inhibition Promotes Lysosomal Biogenesis and Autophagic Degradation of the Amyloid-β Precursor Protein

PubMed Central

Parr, Callum; Carzaniga, Raffaela; Gentleman, Steve M.; Van Leuven, Fred; Walter, Jochen

2012-01-01

Alzheimer's disease (AD) has been associated with altered activity of glycogen synthase kinase 3 (GSK3) isozymes, which are proposed to contribute to both neurofibrillary tangles and amyloid plaque formation. However, the molecular basis by which GSK3 affects the formation of Aβ remains unknown. Our aim was to identify the underlying mechanisms of GSK3-dependent effects on the processing of amyloid precursor protein (APP). For this purpose, N2a cells stably expressing APP carrying the Swedish mutation were treated with specific GSK3 inhibitors or transfected with GSK3α/β short interfering RNA. We show that inhibition of GSK3 leads to decreased expression of APP by enhancing its degradation via an increase in the number of lysosomes. This induction of the lysosomal/autophagy pathway was associated with nuclear translocation of transcription factor EB (TFEB), a master regulator of lysosomal biogenesis. Our data indicate that GSK3 inhibition reduces Aβ through an increase of the degradation of APP and its carboxy-terminal fragment (CTF) by activation of the lysosomal/autophagy pathway. These results suggest that an increased propensity toward autophagic/lysosomal alterations in AD patients could have consequences for neuronal function. PMID:22927642

Lost region in amyloid precursor protein (APP) through TALEN-mediated genome editing alters mitochondrial morphology.

PubMed

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.

Autophagy-mediated Regulation of BACE1 Protein Trafficking and Degradation*

PubMed Central

Feng, Tuancheng; Tammineni, Prasad; Agrawal, Chanchal; Jeong, Yu Young

2017-01-01

β-Site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) is the major neuronal β-secretase for amyloid-β generation and is degraded in lysosomes. The autophagy-lysosomal system plays a key role in the maintenance of cellular homeostasis in neurons. Recent studies established that nascent autophagosomes in distal axons move predominantly in the retrograde direction toward the soma, where mature lysosomes are mainly located. However, it remains unknown whether autophagy plays a critical role in regulation of BACE1 trafficking and degradation. Here, we report that induction of neuronal autophagy enhances BACE1 turnover, which is suppressed by lysosomal inhibition. A significant portion of BACE1 is recruited to the autophagy pathway and co-migrates robustly with autophagic vacuoles along axons. Moreover, we reveal that autophagic vacuole-associated BACE1 is accumulated in the distal axon of Alzheimer's disease-related mutant human APP transgenic neurons and mouse brains. Inducing autophagy in mutant human APP neurons augments autophagic retention of BACE1 in distal axons, leading to enhanced β-cleavage of APP. This phenotype can be reversed by Snapin-enhanced retrograde transport, which facilitates BACE1 trafficking to lysosomes for degradation. Therefore, our study provides new insights into autophagy-mediated regulation of BACE1 turnover and APP processing, thus building a foundation for future development of potential Alzheimer's disease therapeutic strategies. PMID:28028177

Zinc and Copper Differentially Modulate Amyloid Precursor Protein Processing by γ-Secretase and Amyloid-β Peptide Production.

PubMed

Gerber, Hermeto; Wu, Fang; Dimitrov, Mitko; Garcia Osuna, Guillermo M; Fraering, Patrick C

2017-03-03

Recent evidence suggests involvement of biometal homeostasis in the pathological mechanisms in Alzheimer's disease (AD). For example, increased intracellular copper or zinc has been linked to a reduction in secreted levels of the AD-causing amyloid-β peptide (Aβ). However, little is known about whether these biometals modulate the generation of Aβ. In the present study we demonstrate in both cell-free and cell-based assays that zinc and copper regulate Aβ production by distinct molecular mechanisms affecting the processing by γ-secretase of its Aβ precursor protein substrate APP-C99. We found that Zn 2+ induces APP-C99 dimerization, which prevents its cleavage by γ-secretase and Aβ production, with an IC 50 value of 15 μm Importantly, at this concentration, Zn 2+ also drastically raised the production of the aggregation-prone Aβ43 found in the senile plaques of AD brains and elevated the Aβ43:Aβ40 ratio, a promising biomarker for neurotoxicity and AD. We further demonstrate that the APP-C99 histidine residues His-6, His-13, and His-14 control the Zn 2+ -dependent APP-C99 dimerization and inhibition of Aβ production, whereas the increased Aβ43:Aβ40 ratio is substrate dimerization-independent and involves the known Zn 2+ binding lysine Lys-28 residue that orientates the APP-C99 transmembrane domain within the lipid bilayer. Unlike zinc, copper inhibited Aβ production by directly targeting the subunits presenilin and nicastrin in the γ-secretase complex. Altogether, our data demonstrate that zinc and copper differentially modulate Aβ production. They further suggest that dimerization of APP-C99 or the specific targeting of individual residues regulating the production of the long, toxic Aβ species, may offer two therapeutic strategies for preventing AD. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Cerebrospinal fluid levels of amyloid precursor protein are associated with ventricular size in post-hemorrhagic hydrocephalus of prematurity.

PubMed

Morales, Diego M; Holubkov, Richard; Inder, Terri E; Ahn, Haejun C; Mercer, Deanna; Rao, Rakesh; McAllister, James P; Holtzman, David M; Limbrick, David D

2015-01-01

Neurological outcomes of preterm infants with post-hemorrhagic hydrocephalus (PHH) remain among the worst in infancy, yet there remain few instruments to inform the treatment of PHH. We previously observed PHH-associated elevations in cerebrospinal fluid (CSF) amyloid precursor protein (APP), neural cell adhesion molecule-L1 (L1CAM), neural cell adhesion molecule-1 (NCAM-1), and other protein mediators of neurodevelopment. The objective of this study was to examine the association of CSF APP, L1CAM, and NCAM-1 with ventricular size as an early step toward developing CSF markers of PHH. CSF levels of APP, L1CAM, NCAM-1, and total protein (TP) were measured in 12 preterm infants undergoing PHH treatment. Ventricular size was determined using cranial ultrasounds. The relationships between CSF APP, L1CAM, and NCAM-1, occipitofrontal circumference (OFC), volume of CSF removed, and ventricular size were examined using correlation and regression analyses. CSF levels of APP, L1CAM, and NCAM-1 but not TP paralleled treatment-related changes in ventricular size. CSF APP demonstrated the strongest association with ventricular size, estimated by frontal-occipital horn ratio (FOR) (Pearson R = 0.76, p = 0.004), followed by NCAM-1 (R = 0.66, p = 0.02) and L1CAM (R = 0.57,p = 0.055). TP was not correlated with FOR (R = 0.02, p = 0.95). Herein, we report the novel observation that CSF APP shows a robust association with ventricular size in preterm infants treated for PHH. The results from this study suggest that CSF APP and related proteins at once hold promise as biomarkers of PHH and provide insight into the neurological consequences of PHH in the preterm infant.

Effects of Folic Acid on Secretases Involved in Aβ Deposition in APP/PS1 Mice

PubMed Central

Tian, Tian; Bai, Dong; Li, Wen; Huang, Guo-Wei; Liu, Huan

2016-01-01

Alzheimer’s disease (AD) is the most common type of dementia. Amyloid-β protein (Aβ) is identified as the core protein of neuritic plaques. Aβ is generated by the sequential cleavage of the amyloid precursor protein (APP) via the APP cleaving enzyme (α-secretase, or β-secretase) and γ-secretase. Previous studies indicated that folate deficiency elevated Aβ deposition in APP/PS1 mice, and this rise was prevented by folic acid. In the present study, we aimed to investigate whether folic acid could influence the generation of Aβ by regulating α-, β-, and γ-secretase. Herein, we demonstrated that folic acid reduced the deposition of Aβ42 in APP/PS1 mice brain by decreasing the mRNA and protein expressions of β-secretase [beta-site APP-cleaving enzyme 1 (BACE1)] and γ-secretase complex catalytic component—presenilin 1 (PS1)—in APP/PS1 mice brain. Meanwhile, folic acid increased the levels of ADAM9 and ADAM10, which are important α-secretases in ADAM (a disintegrin and metalloprotease) family. However, folic acid has no impact on the protein expression of nicastrin (Nct), another component of γ-secretase complex. Moreover, folic acid regulated the expression of miR-126-3p and miR-339-5p, which target ADAM9 and BACE1, respectively. Taken together, the effect of folic acid on Aβ deposition may relate to making APP metabolism through non-amyloidogenic pathway by decreasing β-secretase and increasing α-secretase. MicroRNA (miRNA) may involve in the regulation mechanism of folic acid on secretase expression. PMID:27618097

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gough, Mallory, E-mail: m.gough1@lancaster.ac.uk; Blanthorn-Hazell, Sophee, E-mail: s.blanthorn-hazell@lancaster.ac.uk; Delury, Craig, E-mail: c.delury@lancaster.ac.uk

Highlights: • Copper levels are elevated in the tumour microenvironment. • APP mitigates copper-induced growth inhibition of DU145 prostate cancer (PCa) cells. • The APP intracellular domain is a prerequisite; soluble forms have no effect. • The E1 CuBD of APP is also a prerequisite. • APP copper binding potentially mitigates copper-induced PCa cell growth inhibition. - Abstract: Copper plays an important role in the aetiology and growth of tumours and levels of the metal are increased in the serum and tumour tissue of patients affected by a range of cancers including prostate cancer (PCa). The molecular mechanisms that enablemore » cancer cells to proliferate in the presence of elevated copper levels are, therefore, of key importance in our understanding of tumour growth progression. In the current study, we have examined the role played by the amyloid precursor protein (APP) in mitigating copper-induced growth inhibition of the PCa cell line, DU145. A range of APP molecular constructs were stably over-expressed in DU145 cells and their effects on cell proliferation in the presence of copper were monitored. Our results show that endogenous APP expression was induced by sub-toxic copper concentrations in DU145 cells and over-expression of the wild-type protein was able to mitigate copper-induced growth inhibition via a mechanism involving the cytosolic and E1 copper binding domains of the full-length protein. APP likely represents one of a range of copper binding proteins that PCa cells employ in order to ensure efficient proliferation despite elevated concentrations of the metal within the tumour microenvironment. Targeting the expression of such proteins may contribute to therapeutic strategies for the treatment of cancers.« less

Hypoxic stress, brain vascular system, and β-amyloid: a primary cell culture study.

PubMed

Muche, Abebe; Bürger, Susanne; Arendt, Thomas; Schliebs, Reinhard

2015-01-01

This study stresses the hypothesis whether hypoxic events contribute to formation and deposition of β-amyloid (Aβ) in cerebral blood vessels by affecting the processing of endothelial amyloid precursor protein (APP). Therefore, cerebral endothelial cells (ECs) derived from transgenic Tg2576 mouse brain, were subjected to short periods of hypoxic stress, followed by assessment of formation and secretion of APP cleavage products sAPPα, sAPPβ, and Aβ as well as the expression of endothelial APP. Hypoxic stress of EC leads to enhanced secretion of sAPPβ into the culture medium as compared to normoxic controls, which is accompanied by increased APP expression, induction of vascular endothelial growth factor (VEGF) synthesis, nitric oxide production, and differential changes in endothelial p42/44 (ERK1/2) expression. The hypoxia-mediated up-regulation of p42/44 at a particular time of incubation was accompanied by a corresponding down-regulation of the phosphorylated form of p42/44. To reveal any role of hypoxia-induced VEGF in endothelial APP processing, ECs were exposed by VEGF. VEGF hardly affected the amount of sAPPβ and Aβ(1-40) secreted into the culture medium, whereas the suppression of the VEGF receptor action by SU-5416 resulted in decreased release of sAPPβ and Aβ(1-40) in comparison to control incubations, suggesting a role of VEGF in controlling the activity of γ-secretase, presumably via the VEGF receptor-associated tyrosine kinase. The data suggest that hypoxic stress represents a mayor risk factor in causing Aβ deposition in the brain vascular system by favoring the amyloidogenic route of endothelial APP processing. The hypoxic-stress-induced changes in β-secretase activity are presumably mediated by altering the phosphorylation status of p42/44, whereas the stress-induced up-regulation of VEGF appears to play a counteracting role by maintaining the balance of physiological APP processing.

Amyloid precursor protein at node of Ranvier modulates nodal formation

PubMed Central

Xu, De-En; Zhang, Wen-Min; Yang, Zara Zhuyun; Zhu, Hong-Mei; Yan, Ke; Li, Shao; Bagnard, Dominique; Dawe, Gavin S; Ma, Quan-Hong; Xiao, Zhi-Cheng

2014-01-01

Amyloid precursor protein (APP), commonly associated with Alzheimer disease, is upregulated and distributes evenly along the injured axons, and therefore, also known as a marker of demyelinating axonal injury and axonal degeneration. However, the physiological distribution and function of APP along myelinated axons was unknown. We report that APP aggregates at nodes of Ranvier (NOR) in the myelinated central nervous system (CNS) axons but not in the peripheral nervous system (PNS). At CNS NORs, APP expression co-localizes with tenascin-R and is flanked by juxtaparanodal potassium channel expression demonstrating that APP localized to NOR. In APP-knockout (KO) mice, nodal length is significantly increased, while sodium channels are still clustered at NORs. Moreover, APP KO and APP-overexpressing transgenic (APP TG) mice exhibited a decreased and an increased thickness of myelin in spinal cords, respectively, although the changes are limited in comparison to their littermate WT mice. The thickness of myelin in APP KO sciatic nerve also increased in comparison to that in WT mice. Our observations indicate that APP acts as a novel component at CNS NORs, modulating nodal formation and has minor effects in promoting myelination. PMID:25482638

The structure and function of Alzheimer's gamma secretase enzyme complex.

PubMed

Krishnaswamy, Sudarsan; Verdile, Giuseppe; Groth, David; Kanyenda, Limbikani; Martins, Ralph N

2009-01-01

The production and accumulation of the beta amyloid protein (Abeta) is a key event in the cascade of oxidative and inflammatory processes that characterizes Alzheimer's disease (AD). A multi-subunit enzyme complex, referred to as gamma (gamma) secretase, plays a pivotal role in the generation of Abeta from its parent molecule, the amyloid precursor protein (APP). Four core components (presenilin, nicastrin, aph-1, and pen-2) interact in a high-molecular-weight complex to perform intramembrane proteolysis on a number of membrane-bound proteins, including APP and Notch. Inhibitors and modulators of this enzyme have been assessed for their therapeutic benefit in AD. However, although these agents reduce Abeta levels, the majority have been shown to have severe side effects in pre-clinical animal studies, most likely due to the enzymes role in processing other proteins involved in normal cellular function. Current research is directed at understanding this enzyme and, in particular, at elucidating the roles that each of the core proteins plays in its function. In addition, a number of interacting proteins that are not components of gamma-secretase also appear to play important roles in modulating enzyme activity. This review will discuss the structural and functional complexity of the gamma-secretase enzyme and the effects of inhibiting its activity.

A Small Molecule Inhibitor of Plasminogen Activator Inhibitor-1 Reduces Brain Amyloid-β Load and Improves Memory in an Animal Model of Alzheimer's Disease.

PubMed

Akhter, Hasina; Huang, Wen-Tan; van Groen, Thomas; Kuo, Hui-Chien; Miyata, Toshio; Liu, Rui-Ming

2018-01-01

Alzheimer's disease (AD) is a major cause of dementia in the elderly with no effective treatment. Accumulation of amyloid-β peptide (Aβ) in the brain is a pathological hallmark of AD and is believed to be a central disease-causing and disease-promoting event. In a previous study, we showed that deletion of plasminogen activator inhibitor 1 (PAI-1), a primary inhibitor of tissue type and urokinase type plasminogen activators (tPA and uPA), significantly reduced brain Aβ load in APP/PS1 mice, an animal model of familial AD. In this study, we further show that oral administration of TM5275, a small molecule inhibitor of PAI-1, for a period of 6 weeks, inhibits the activity of PAI-1 and increases the activities of tPA and uPA as well as plasmin, which is associated with a reduction of Aβ load in the hippocampus and cortex and improvement of learning/memory function in APP/PS1 mice. Protein abundance of low density lipoprotein related protein-1 (LRP-1), a multi ligand endocytotic receptor involved in transporting Aβ out of the brain, as well as plasma Aβ42 are increased, whereas the expression and processing of full-length amyloid-β protein precursor is not affected by TM5275 treatment in APP/PS1 mice. In vitro studies further show that PAI-1 increases, whereas TM5275 reduces, Aβ40 level in the culture medium of SHSY5Y-APP neuroblastoma cells. Collectively, our data suggest that TM5275 improves memory function of APP/PS1 mice, probably by reducing brain Aβ accumulation through increasing plasmin-mediated degradation and LRP-1-mediated efflux of Aβ in the brain.

Contextual Hub Analysis Tool (CHAT): A Cytoscape app for identifying contextually relevant hubs in biological networks.

PubMed

Muetze, Tanja; Goenawan, Ivan H; Wiencko, Heather L; Bernal-Llinares, Manuel; Bryan, Kenneth; Lynn, David J

2016-01-01

Highly connected nodes (hubs) in biological networks are topologically important to the structure of the network and have also been shown to be preferentially associated with a range of phenotypes of interest. The relative importance of a hub node, however, can change depending on the biological context. Here, we report a Cytoscape app, the Contextual Hub Analysis Tool (CHAT), which enables users to easily construct and visualize a network of interactions from a gene or protein list of interest, integrate contextual information, such as gene expression or mass spectrometry data, and identify hub nodes that are more highly connected to contextual nodes (e.g. genes or proteins that are differentially expressed) than expected by chance. In a case study, we use CHAT to construct a network of genes that are differentially expressed in Dengue fever, a viral infection. CHAT was used to identify and compare contextual and degree-based hubs in this network. The top 20 degree-based hubs were enriched in pathways related to the cell cycle and cancer, which is likely due to the fact that proteins involved in these processes tend to be highly connected in general. In comparison, the top 20 contextual hubs were enriched in pathways commonly observed in a viral infection including pathways related to the immune response to viral infection. This analysis shows that such contextual hubs are considerably more biologically relevant than degree-based hubs and that analyses which rely on the identification of hubs solely based on their connectivity may be biased towards nodes that are highly connected in general rather than in the specific context of interest. CHAT is available for Cytoscape 3.0+ and can be installed via the Cytoscape App Store ( http://apps.cytoscape.org/apps/chat).

The Kunitz-protease inhibitor domain in amyloid precursor protein reduces cellular mitochondrial enzymes expression and function.

PubMed

Chua, Li-Min; Lim, Mei-Li; Wong, Boon-Seng

2013-08-09

Mitochondrial dysfunction is a prominent feature of Alzheimer's disease (AD) and this can be contributed by aberrant metabolic enzyme function. But, the mechanism causing this enzymatic impairment is unclear. Amyloid precursor protein (APP) is known to be alternatively spliced to produce three major isoforms in the brain (APP695, APP751, APP770). Both APP770 and APP751 contain the Kunitz Protease Inhibitory (KPI) domain, but the former also contain an extra OX-2 domain. APP695 on the other hand, lacks both domains. In AD, up-regulation of the KPI-containing APP isoforms has been reported. But the functional contribution of this elevation is unclear. In the present study, we have expressed and compared the effect of the non-KPI containing APP695 and the KPI-containing APP751 on mitochondrial function. We found that the KPI-containing APP751 significantly decreased the expression of three major mitochondrial metabolic enzymes; citrate synthase, succinate dehydrogenase and cytochrome c oxidase (COX IV). This reduction lowers the NAD(+)/NADH ratio, COX IV activity and mitochondrial membrane potential. Overall, this study demonstrated that up-regulation of the KPI-containing APP isoforms is likely to contribute to the impairment of metabolic enzymes and mitochondrial function in AD. Copyright © 2013 Elsevier Inc. All rights reserved.

Amyloid Precursor Protein and Proinflammatory Changes Are Regulated in Brain and Adipose Tissue in a Murine Model of High Fat Diet-Induced Obesity

PubMed Central

Puig, Kendra L.; Floden, Angela M.; Adhikari, Ramchandra; Golovko, Mikhail Y.; Combs, Colin K.

2012-01-01

Background Middle age obesity is recognized as a risk factor for Alzheimer's disease (AD) although a mechanistic linkage remains unclear. Based upon the fact that obese adipose tissue and AD brains are both areas of proinflammatory change, a possible common event is chronic inflammation. Since an autosomal dominant form of AD is associated with mutations in the gene coding for the ubiquitously expressed transmembrane protein, amyloid precursor protein (APP) and recent evidence demonstrates increased APP levels in adipose tissue during obesity it is feasible that APP serves some function in both disease conditions. Methodology/Principal Findings To determine whether diet-induced obesity produced proinflammatory changes and altered APP expression in brain versus adipose tissue, 6 week old C57BL6/J mice were maintained on a control or high fat diet for 22 weeks. Protein levels and cell-specific APP expression along with markers of inflammation and immune cell activation were compared between hippocampus, abdominal subcutaneous fat and visceral pericardial fat. APP stimulation-dependent changes in macrophage and adipocyte culture phenotype were examined for comparison to the in vivo changes. Conclusions/Significance Adipose tissue and brain from high fat diet fed animals demonstrated increased TNF-α and microglial and macrophage activation. Both brains and adipose tissue also had elevated APP levels localizing to neurons and macrophage/adipocytes, respectively. APP agonist antibody stimulation of macrophage cultures increased specific cytokine secretion with no obvious effects on adipocyte culture phenotype. These data support the hypothesis that high fat diet-dependent obesity results in concomitant pro-inflammatory changes in brain and adipose tissue that is characterized, in part, by increased levels of APP that may be contributing specifically to inflammatory changes that occur. PMID:22276186

Identifying Blood Biomarkers and Physiological Processes That Distinguish Humans with Superior Performance under Psychological Stress

DTIC Science & Technology

2009-12-18

338 (Pt2): 281–287. 27. Berbee JF, van der Hoogt CC, Sundararaman D, Havekes LM, Rensen PC (2005) Severe hypertriglyceridemia in human APOC1 transgenic...plasma lipid regulation. Each of these processes is discussed in detail. Innate Immunity Several innate immune response pathways were differentially...response to infection, injury or stress resulting in the increased or decreased plasma concentration of several proteins called acute phase proteins (APP

Turnover of C99 is Controlled by a Crosstalk between ERAD and Ubiquitin-Independent Lysosomal Degradation in Human Neuroglioma Cells

PubMed Central

Bustamante, Hianara A.; Rivera-Dictter, Andrés; Cavieres, Viviana A.; Muñoz, Vanessa C.; González, Alexis; Lin, Yimo; Mardones, Gonzalo A.; Burgos, Patricia V.

2013-01-01

Alzheimer’s disease (AD) is characterized by the buildup of amyloid-β peptides (Aβ) aggregates derived from proteolytic processing of the β-amyloid precursor protein (APP). Amyloidogenic cleavage of APP by β-secretase/BACE1 generates the C-terminal fragment C99/CTFβ that can be subsequently cleaved by γ-secretase to produce Aβ. Growing evidence indicates that high levels of C99/CTFβ are determinant for AD. Although it has been postulated that γ-secretase-independent pathways must control C99/CTFβ levels, the contribution of organelles with degradative functions, such as the endoplasmic reticulum (ER) or lysosomes, is unclear. In this report, we investigated the turnover and amyloidogenic processing of C99/CTFβ in human H4 neuroglioma cells, and found that C99/CTFβ is localized at the Golgi apparatus in contrast to APP, which is mostly found in endosomes. Conditions that localized C99/CTFβ to the ER resulted in its degradation in a proteasome-dependent manner that first required polyubiquitination, consistent with an active role of the ER associated degradation (ERAD) in this process. Furthermore, when proteasomal activity was inhibited C99/CTFβ was degraded in a chloroquine (CQ)-sensitive compartment, implicating lysosomes as alternative sites for its degradation. Our results highlight a crosstalk between degradation pathways within the ER and lysosomes to avoid protein accumulation and toxicity. PMID:24376644

Turnover of C99 is controlled by a crosstalk between ERAD and ubiquitin-independent lysosomal degradation in human neuroglioma cells.

PubMed

Bustamante, Hianara A; Rivera-Dictter, Andrés; Cavieres, Viviana A; Muñoz, Vanessa C; González, Alexis; Lin, Yimo; Mardones, Gonzalo A; Burgos, Patricia V

2013-01-01

Alzheimer's disease (AD) is characterized by the buildup of amyloid-β peptides (Aβ) aggregates derived from proteolytic processing of the β-amyloid precursor protein (APP). Amyloidogenic cleavage of APP by β-secretase/BACE1 generates the C-terminal fragment C99/CTFβ that can be subsequently cleaved by γ-secretase to produce Aβ. Growing evidence indicates that high levels of C99/CTFβ are determinant for AD. Although it has been postulated that γ-secretase-independent pathways must control C99/CTFβ levels, the contribution of organelles with degradative functions, such as the endoplasmic reticulum (ER) or lysosomes, is unclear. In this report, we investigated the turnover and amyloidogenic processing of C99/CTFβ in human H4 neuroglioma cells, and found that C99/CTFβ is localized at the Golgi apparatus in contrast to APP, which is mostly found in endosomes. Conditions that localized C99/CTFβ to the ER resulted in its degradation in a proteasome-dependent manner that first required polyubiquitination, consistent with an active role of the ER associated degradation (ERAD) in this process. Furthermore, when proteasomal activity was inhibited C99/CTFβ was degraded in a chloroquine (CQ)-sensitive compartment, implicating lysosomes as alternative sites for its degradation. Our results highlight a crosstalk between degradation pathways within the ER and lysosomes to avoid protein accumulation and toxicity.

Thymoquinone-rich fraction nanoemulsion (TQRFNE) decreases Aβ40 and Aβ42 levels by modulating APP processing, up-regulating IDE and LRP1, and down-regulating BACE1 and RAGE in response to high fat/cholesterol diet-induced rats.

PubMed

Ismail, Norsharina; Ismail, Maznah; Azmi, Nur Hanisah; Bakar, Muhammad Firdaus Abu; Yida, Zhang; Abdullah, Maizaton Atmadini; Basri, Hamidon

2017-11-01

Though the causes of Alzheimer's disease (AD) are yet to be understood, much evidence has suggested that excessive amyloid-β (Aβ) accumulation due to abnormal amyloid-β precursor protein (APP) processing and Aβ metabolism are crucial processes towards AD pathogenesis. Hence, approaches aiming at APP processing and Aβ metabolism are currently being actively pursued for the management of AD. Studies suggest that high cholesterol and a high fat diet have harmful effects on cognitive function and may instigate the commencement of AD pathogenesis. Despite the neuropharmacological attributes of black cumin seed (Nigella sativa) extracts and its main active compound, thymoquinone (TQ), limited records are available in relation to AD research. Nanoemulsion (NE) is exploited as drug delivery systems due to their capacity of solubilising non-polar active compounds and is widely examined for brain targeting. Herewith, the effects of thymoquinone-rich fraction nanoemulsion (TQRFNE), thymoquinone nanoemulsion (TQNE) and their counterparts' conventional emulsion in response to high fat/cholesterol diet (HFCD)-induced rats were investigated. Particularly, the Aβ generation; APP processing, β-secretase 1 (BACE1), γ-secretases of presenilin 1 (PSEN1) and presenilin 2 (PSEN2), Aβ degradation; insulin degrading enzyme (IDE), Aβ transportation; low density lipoprotein receptor-related protein 1 (LRP1) and receptor for advanced glycation end products (RAGE) were measured in brain tissues. TQRFNE reduced the brain Aβ fragment length 1-40 and 1-42 (Aβ40 and Aβ42) levels, which would attenuate the AD pathogenesis. This reduction could be due to the modulation of β- and γ-secretase enzyme activity, and the Aβ degradation and transportation in/out of the brain. The findings show the mechanistic actions of TQRFNE in response to high fat and high cholesterol diet associated to Aβ generation, degradation and transportation in the rat's brain tissue. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Ear2 deletion causes early memory and learning deficits in APP/PS1 mice.

PubMed

Kummer, Markus P; Hammerschmidt, Thea; Martinez, Ana; Terwel, Dick; Eichele, Gregor; Witten, Anika; Figura, Stefanie; Stoll, Monika; Schwartz, Stephanie; Pape, Hans-Christian; Schultze, Joachim L; Weinshenker, David; Heneka, Michael T; Urban, Inga

2014-06-25

To assess the consequences of locus ceruleus (LC) degeneration and subsequent noradrenaline (NA) deficiency in early Alzheimer's disease (AD), mice overexpressing mutant amyloid precursor protein and presenilin-1 (APP/PS1) were crossed with Ear2(-/-) mice that have a severe loss of LC neurons projecting to the hippocampus and neocortex. Testing spatial memory and hippocampal long-term potentiation revealed an impairment in APP/PS1 Ear2(-/-) mice, whereas APP/PS1 or Ear2(-/-) mice showed only minor changes. These deficits were associated with distinct synaptic changes including reduced expression of the NMDA 2A subunit and increased levels of NMDA receptor 2B in APP/PS1 Ear2(-/-) mice. Acute pharmacological replacement of NA by L-threo-DOPS partially restored phosphorylation of β-CaMKII and spatial memory performance in APP/PS1 Ear2(-/-) mice. These changes were not accompanied by altered APP processing or amyloid β peptide (Aβ) deposition. Thus, early LC degeneration and subsequent NA reduction may contribute to cognitive deficits via CaMKII and NMDA receptor dysfunction independent of Aβ and suggests that NA supplementation could be beneficial in treating AD. Copyright © 2014 the authors 0270-6474/14/348845-10$15.00/0.

Structural features of the KPI domain control APP dimerization, trafficking, and processing.

PubMed

Ben Khalifa, Naouel; Tyteca, Donatienne; Marinangeli, Claudia; Depuydt, Mathieu; Collet, Jean-François; Courtoy, Pierre J; Renauld, Jean-Christophe; Constantinescu, Stefan; Octave, Jean-Noël; Kienlen-Campard, Pascal

2012-02-01

The two major isoforms of human APP, APP695 and APP751, differ by the presence of a Kunitz-type protease inhibitor (KPI) domain in the extracellular region. APP processing and function is thought to be regulated by homodimerization. We used bimolecular fluorescence complementation (BiFC) to study dimerization of different APP isoforms and mutants. APP751 was found to form significantly more homodimers than APP695. Mutation of dimerization motifs in the TM domain did not affect fluorescence complementation, but native folding of KPI is critical for APP751 homodimerization. APP751 and APP695 dimers were mostly localized at steady state in the Golgi region, suggesting that most of the APP751 and 695 dimers are in the secretory pathway. Mutation of the KPI led to the retention of the APP homodimers in the endoplasmic reticulum. We finally showed that APP751 is more efficiently processed through the nonamyloidogenic pathway than APP695. These findings provide new insight on the particular role of KPI domain in APP dimerization. The correlation observed between dimerization, subcellular localization, and processing suggests that dimerization acts as an efficient regulator of APP trafficking in the secretory compartments that has major consequences on its processing.

Interferon-γ and Tumor Necrosis Factor-α Regulate Amyloid-β Plaque Deposition and β-Secretase Expression in Swedish Mutant APP Transgenic Mice

PubMed Central

Yamamoto, Masaru; Kiyota, Tomomi; Horiba, Masahide; Buescher, James L.; Walsh, Shannon M.; Gendelman, Howard E.; Ikezu, Tsuneya

2007-01-01

Reactive astrocytes and microglia in Alzheimer’s disease surround amyloid plaques and secrete proinflammatory cytokines that affect neuronal function. Relationship between cytokine signaling and amyloid-β peptide (Aβ) accumulation is poorly understood. Thus, we generated a novel Swedish β-amyloid precursor protein mutant (APP) transgenic mouse in which the interferon (IFN)-γ receptor type I was knocked out (APP/GRKO). IFN-γ signaling loss in the APP/GRKO mice reduced gliosis and amyloid plaques at 14 months of age. Aggregated Aβ induced IFN-γ production from co-culture of astrocytes and microglia, and IFN-γ elicited tumor necrosis factor (TNF)-α secretion in wild type (WT) but not GRKO microglia co-cultured with astrocytes. Both IFN-γ and TNF-α enhanced Aβ production from APP-expressing astrocytes and cortical neurons. TNF-α directly stimulated β-site APP-cleaving enzyme (BACE1) expression and enhanced β-processing of APP in astrocytes. The numbers of reactive astrocytes expressing BACE1 were increased in APP compared with APP/GRKO mice in both cortex and hippocampus. IFN-γ and TNF-α activation of WT microglia suppressed Aβ degradation, whereas GRKO microglia had no changes. These results support the idea that glial IFN-γ and TNF-α enhance Aβ deposition through BACE1 expression and suppression of Aβ clearance. Taken together, these observations suggest that proinflammatory cytokines are directly linked to Alzheimer’s disease pathogenesis. PMID:17255335

Aβ-Induced Inflammatory Processes in Microglia Cells of APP23 Transgenic Mice

PubMed Central

Bornemann, Klaus D.; Wiederhold, Karl-Heinz; Pauli, Chantal; Ermini, Florian; Stalder, Martina; Schnell, Lisa; Sommer, Bernd; Jucker, Mathias; Staufenbiel, Matthias

2001-01-01

A microglial response is part of the inflammatory processes in Alzheimer’s disease (AD). We have used APP23 transgenic mice overexpressing human amyloid precursor protein with the Swedish mutation to characterize this microglia response to amyloid deposits in aged mice. Analyses with MAC-1 and F4/80 antibodies as well as in vivo labeling with bromodeoxyuridine demonstrate that microglia in the plaque vicinity are in an activated state and that proliferation contributes to their accumulation at the plaque periphery. The amyloid-induced microglia activation may be mediated by scavenger receptor A, which is generally elevated, whereas the increased immunostaining of the receptor for advanced glycation end products is more restricted. Although components of the phagocytic machinery such as macrosialin and Fc receptors are increased in activated microglia, efficient clearance of amyloid is missing seemingly because of the lack of amyloid-bound autoantibodies. Similarly, although up-regulation of major histocompatibility complex class II (IA) points toward an intact antigen-presenting function of microglia, lack of T and B lymphocytes does not indicate a cell-mediated immune response in the brains of APP23 mice. The similar characteristics of microglia in the APP23 mice and in AD render the mouse model suitable to study the role of inflammatory processes during AD pathogenesis. PMID:11141480

The Large Hydrophilic Loop of Presenilin 1 Is Important for Regulating γ-Secretase Complex Assembly and Dictating the Amyloid β Peptide (Aβ) Profile without Affecting Notch Processing*

PubMed Central

Wanngren, Johanna; Frånberg, Jenny; Svensson, Annelie I.; Laudon, Hanna; Olsson, Fredrik; Winblad, Bengt; Liu, Frank; Näslund, Jan; Lundkvist, Johan; Karlström, Helena

2010-01-01

γ-Secretase is an enzyme complex that mediates both Notch signaling and β-amyloid precursor protein (APP) processing, resulting in the generation of Notch intracellular domain, APP intracellular domain, and the amyloid β peptide (Aβ), the latter playing a central role in Alzheimer disease (AD). By a hitherto undefined mechanism, the activity of γ-secretase gives rise to Aβ peptides of different lengths, where Aβ42 is considered to play a particular role in AD. In this study we have examined the role of the large hydrophilic loop (amino acids 320–374, encoded by exon 10) of presenilin 1 (PS1), the catalytic subunit of γ-secretase, for γ-secretase complex formation and activity on Notch and APP processing. Deletion of exon 10 resulted in impaired PS1 endoproteolysis, γ-secretase complex formation, and had a differential effect on Aβ-peptide production. Although the production of Aβ38, Aβ39, and Aβ40 was severely impaired, the effect on Aβ42 was affected to a lesser extent, implying that the production of the AD-related Aβ42 peptide is separate from the production of the Aβ38, Aβ39, and Aβ40 peptides. Interestingly, formation of the intracellular domains of both APP and Notch was intact, implying a differential cleavage activity between the ϵ/S3 and γ sites. The most C-terminal amino acids of the hydrophilic loop were important for regulating APP processing. In summary, the large hydrophilic loop of PS1 appears to differentially regulate the relative production of different Aβ peptides without affecting Notch processing, two parameters of significance when considering γ-secretase as a target for pharmaceutical intervention in AD. PMID:20106965

Omega-3 fatty acids, lipids, and apoE lipidation in Alzheimer's disease: a rationale for multi-nutrient dementia prevention.

PubMed

Grimm, Marcus O W; Michaelson, Daniel M; Hartmann, Tobias

2017-11-01

In the last decade, it has become obvious that Alzheimer's disease (AD) is closely linked to changes in lipids or lipid metabolism. One of the main pathological hallmarks of AD is amyloid-β (Aβ) deposition. Aβ is derived from sequential proteolytic processing of the amyloid precursor protein (APP). Interestingly, both, the APP and all APP secretases are transmembrane proteins that cleave APP close to and in the lipid bilayer. Moreover, apoE4 has been identified as the most prevalent genetic risk factor for AD. ApoE is the main lipoprotein in the brain, which has an abundant role in the transport of lipids and brain lipid metabolism. Several lipidomic approaches revealed changes in the lipid levels of cerebrospinal fluid or in post mortem AD brains. Here, we review the impact of apoE and lipids in AD, focusing on the major brain lipid classes, sphingomyelin, plasmalogens, gangliosides, sulfatides, DHA, and EPA, as well as on lipid signaling molecules, like ceramide and sphingosine-1-phosphate. As nutritional approaches showed limited beneficial effects in clinical studies, the opportunities of combining different supplements in multi-nutritional approaches are discussed and summarized. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

[Association between serum aluminium level and methylation of amyloid precursor protein gene in workers engaged in aluminium electrolysis].

PubMed

Yang, X J; Yuan, Y Z; Niu, Q

2016-04-20

To investigate the association between serum aluminium level and methylation of the promoter region of amyloid precursor protein (APP)gene in workers engaged in aluminium electrolysis. In 2012, 366 electrolysis workers in an aluminium factory were enrolled as exposure group (working years >10 and age >40 years)and divided into low-exposure group and high-exposure group based on the median serum aluminium level. Meanwhile, 102 workers in a cement plant not exposed to aluminium were enrolled as control group. Graphite furnace atomic absorption spectrometry was used to measure serum aluminium level, methylation specific PCR was used to measure the methylation rate of the promoter region of APP gene, and ELI-SA was used to measure the protein expression of APP in lymphocytes in peripheral blood. The exposure group had a significantly higher serum aluminium level than the control group (45.07 μg/L vs 30.51 μg/L, P< 0.01). The exposure group had a significantly lower methylation rate of the promoter region of APP gene than the control group (18.85% vs 25.49%, P=0.025), and the high-exposure group had a significantly lower methylation rate of the promoter region of APP gene than the low-exposure group (15.84% vs 21.85%, P<0.05). The exposure group had a significantly higher protein expression of APP in lymphocytes in peripheral blood than the control group (66.73 ng/ml vs 54.17 ng/ml, P<0.05); compared with the low-exposure group (65.39 ng/ml), the high-exposure group showed an increase in the protein expression of APP in lymphocytes in peripheral blood (67.22 ng/ml), but there was no significant difference between these two groups (P>0.05). The multivariate logistic regression analysis showed that with reference to the control group, low aluminium exposure (OR=1.86, 95% CI 1.67~3.52)and high aluminium exposure (OR=2.98, 95% CI 1.97~4.15)were risk factors for a reduced methylation rate of the promoter region of APP gene. Reduced methylation of the promoter region of APP gene may be associated with increased serum aluminium level, and downregulated methylation of the promoter region of APP gene may accelerate APP gene transcription.

Trehalose Alters Subcellular Trafficking and the Metabolism of the Alzheimer-associated Amyloid Precursor Protein*

PubMed Central

Tien, Nguyen T.; Karaca, Ilker; Tamboli, Irfan Y.

2016-01-01

The disaccharide trehalose is commonly considered to stimulate autophagy. Cell treatment with trehalose could decrease cytosolic aggregates of potentially pathogenic proteins, including mutant huntingtin, α-synuclein, and phosphorylated tau that are associated with neurodegenerative diseases. Here, we demonstrate that trehalose also alters the metabolism of the Alzheimer disease-related amyloid precursor protein (APP). Cell treatment with trehalose decreased the degradation of full-length APP and its C-terminal fragments. Trehalose also reduced the secretion of the amyloid-β peptide. Biochemical and cell biological experiments revealed that trehalose alters the subcellular distribution and decreases the degradation of APP C-terminal fragments in endolysosomal compartments. Trehalose also led to strong accumulation of the autophagic marker proteins LC3-II and p62, and decreased the proteolytic activation of the lysosomal hydrolase cathepsin D. The combined data indicate that trehalose decreases the lysosomal metabolism of APP by altering its endocytic vesicular transport. PMID:26957541

Platelet amyloid precursor protein isoform expression in Alzheimer's disease: evidence for peripheral marker.

PubMed

Vignini, A; Sartini, D; Morganti, S; Nanetti, L; Luzzi, S; Provinciali, L; Mazzanti, L; Emanuelli, M

2011-01-01

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by a progressive cognitive and memory decline. Among peripheral markers of AD, great interest has been focused on the amyloid precursor protein (APP). In this regard, platelets represent an important peripheral source of APP since it has been demonstrated that the three major isoforms, that are constituted of 770, 751 and 695 aa residues, are inserted in the membrane of resting platelets. APP 751 and APP 770 contain a Kunitz-type serine protease inhibitor domain (APP KPI) and APP 695 lacks this domain. To address this issue, we first examined the platelet APP isoform mRNAs prospectively as biomarker for the diagnosis of AD by means of real-time quantitative PCR, and then evaluated the correlation between APP mRNA expression levels and cognitive impairment of enrolled subjects. Differential gene expression measurements in the AD patient group (n=18) revealed a significant up-regulation of APP TOT (1.52-fold), APP KPI (1.32-fold), APP 770 (1.33-fold) and APP 751 (1.26-fold) compared to controls (n=22). Moreover, a statistically significant positive correlation was found between APP mRNA levels (TOT, KPI, 770 and 751) and cognitive impairment. Since AD definitive diagnosis still relies on pathological evaluation at autopsy, the present results are consistent with the hypothesis that platelet APP could be considered a potential reliable peripheral marker for studying AD and could contribute to define a signature for the presence of AD pathology.

Nebula/DSCR1 upregulation delays neurodegeneration and protects against APP-induced axonal transport defects by restoring calcineurin and GSK-3β signaling.

PubMed

Shaw, Jillian L; Chang, Karen T

2013-01-01

Post-mortem brains from Down syndrome (DS) and Alzheimer's disease (AD) patients show an upregulation of the Down syndrome critical region 1 protein (DSCR1), but its contribution to AD is not known. To gain insights into the role of DSCR1 in AD, we explored the functional interaction between DSCR1 and the amyloid precursor protein (APP), which is known to cause AD when duplicated or upregulated in DS. We find that the Drosophila homolog of DSCR1, Nebula, delays neurodegeneration and ameliorates axonal transport defects caused by APP overexpression. Live-imaging reveals that Nebula facilitates the transport of synaptic proteins and mitochondria affected by APP upregulation. Furthermore, we show that Nebula upregulation protects against axonal transport defects by restoring calcineurin and GSK-3β signaling altered by APP overexpression, thereby preserving cargo-motor interactions. As impaired transport of essential organelles caused by APP perturbation is thought to be an underlying cause of synaptic failure and neurodegeneration in AD, our findings imply that correcting calcineurin and GSK-3β signaling can prevent APP-induced pathologies. Our data further suggest that upregulation of Nebula/DSCR1 is neuroprotective in the presence of APP upregulation and provides evidence for calcineurin inhibition as a novel target for therapeutic intervention in preventing axonal transport impairments associated with AD.

Nebula/DSCR1 Upregulation Delays Neurodegeneration and Protects against APP-Induced Axonal Transport Defects by Restoring Calcineurin and GSK-3β Signaling

PubMed Central

Shaw, Jillian L.; Chang, Karen T.

2013-01-01

Post-mortem brains from Down syndrome (DS) and Alzheimer's disease (AD) patients show an upregulation of the Down syndrome critical region 1 protein (DSCR1), but its contribution to AD is not known. To gain insights into the role of DSCR1 in AD, we explored the functional interaction between DSCR1 and the amyloid precursor protein (APP), which is known to cause AD when duplicated or upregulated in DS. We find that the Drosophila homolog of DSCR1, Nebula, delays neurodegeneration and ameliorates axonal transport defects caused by APP overexpression. Live-imaging reveals that Nebula facilitates the transport of synaptic proteins and mitochondria affected by APP upregulation. Furthermore, we show that Nebula upregulation protects against axonal transport defects by restoring calcineurin and GSK-3β signaling altered by APP overexpression, thereby preserving cargo-motor interactions. As impaired transport of essential organelles caused by APP perturbation is thought to be an underlying cause of synaptic failure and neurodegeneration in AD, our findings imply that correcting calcineurin and GSK-3β signaling can prevent APP-induced pathologies. Our data further suggest that upregulation of Nebula/DSCR1 is neuroprotective in the presence of APP upregulation and provides evidence for calcineurin inhibition as a novel target for therapeutic intervention in preventing axonal transport impairments associated with AD. PMID:24086147

LRP-mediated clearance of Abeta is inhibited by KPI-containing isoforms of APP.

PubMed

Moir, Robert D; Tanzi, Rudolph E

2005-04-01

The pathogenesis of Alzheimer's disease (AD) involves the abnormal accumulation and deposition of beta-amyloid in cerebral blood vessels and in the brain parenchyma. Critical in modulating beta-amyloid deposition in brain is the flux of Abeta across the blood brain barrier. The low-density lipoprotein receptor-related protein (LRP), is a large endocytic receptor that mediates the efflux of Abeta out of brain and into the periphery. The first step in the LRP-mediated clearance of Abeta involves the formation of a complex between Abeta and the LRP ligands apolipoprotein E (apoE) or alpha(2)-macroglobulin (alpha(2)M). The Abeta/chaperone complexes then bind to LRP via binding sites on apoE or alpha(2)M. The efflux of Abeta/chaperone complexes out of the neuropil and into the periphery may be attenuated by LRP-ligands that compete with apoE or alpha(2)M for LRP binding. LRP is also the cell surface receptor for Kunitz Protease Inhibitor (KPI) containing isoforms of Abeta's parent protein, the amyloid protein precursor (APP). Protein and mRNA levels of KPI-containing APP isoforms (APP-KPI) are elevated in AD brain and are associated with increased Abeta production. In this study we show that soluble non-amyloidogenic APP-KPI can also inhibit the uptake of Abeta/alpha(2)M in a cell culture model of LRP mediated Abeta clearance. Clearance of Abeta/apoE complexes was not inhibited by APP-KPI. Our findings are consistent with studies showing that apoE and alpha(2)M have discrete binding sites on LRP. Most significantly, our data suggests that the elevated levels of APP-KPI in AD brain may attenuate the clearance of Abeta, the proteins own amyloidogenic catabolic product.

Alzheimer CSF biomarkers may be misleading in normal-pressure hydrocephalus

PubMed Central

2014-01-01

Objective: This article discusses why CSF biomarkers found in normal-pressure hydrocephalus (NPH) can be misleading when distinguishing NPH from comorbid NPH with Alzheimer disease (AD). Methods: We describe NPH CSF biomarkers and how shunt surgery can change them. We hypothesize the effects that hydrocephalus may play on interstitial fluid space and amyloid precursor protein (APP) fragment drainage into the CSF based on a recent report and how this may explain the misleading CSF NPH biomarker findings. Results: In NPH, β-amyloid protein 42 (Aβ42) is low (as in AD), but total tau (t-tau) and phospho-tau (p-tau) levels are normal, providing conflicting biomarker findings. Low Aβ42 supports an AD diagnosis but tau findings do not. Importantly, not only Aβ42, but all APP fragments and tau proteins are low in NPH CSF. Further, these proteins increase after shunting. An increase in interstitial space and APP fragment drainage into the CSF during sleep was reported recently. Conclusions: In the setting of hydrocephalus when the brain is compressed, a decrease in interstitial space and APP protein fragment drainage into the CSF may be impeded, resulting in low levels of all APP fragments and tau proteins, which has been reported. Shunting, which decompresses the brain, would create more room for the interstitial space to increase and protein waste fragments to drain into the CSF. In fact, CSF proteins increase after shunting. CSF biomarkers in pre-shunt NPH have low Aβ42 and tau protein levels, providing misleading information to distinguish NPH from comorbid NPH plus AD. PMID:25332445

In vivo neuronal synthesis and axonal transport of Kunitz protease inhibitor (KPI)-containing forms of the amyloid precursor protein.

PubMed

Moya, K L; Confaloni, A M; Allinquant, B

1994-11-01

We have shown previously that the amyloid precursor protein (APP) is synthesized in retinal ganglion cells and is rapidly transported down the axons, and that different molecular weight forms of the precursor have different developmental time courses. Some APP isoforms contain a Kunitz protease inhibitor (KPI) domain, and APP that lacks the KPI domain is considered the predominant isoform in neurons. We now show that, among the various rapidly transported APPs, a 140-kDa isoform contains the KPI domain. This APP isoform is highly expressed in rapidly growing retinal axons, and it is also prominent in adult axon endings. This 140-kDa KPI-containing APP is highly sulfated compared with other axonally transported isoforms. These results show that APP with the KPI domain is a prominent isoform synthesized in neurons in vivo, and they suggest that the regulation of protease activity may be an important factor during the establishment of neuronal connections.

Apolipoprotein E-mimetics inhibit neurodegeneration and restore cognitive functions in a transgenic Drosophila model of Alzheimer's disease.

PubMed

Sarantseva, Svetlana; Timoshenko, Svetlana; Bolshakova, Olga; Karaseva, Eugenia; Rodin, Dmitry; Schwarzman, Alexander L; Vitek, Michael P

2009-12-07

Mutations of the amyloid precursor protein gene (APP) are found in familial forms of Alzheimer's disease (AD) and some lead to the elevated production of amyloid-beta-protein (Abeta). While Abeta has been implicated in the causation of AD, the exact role played by Abeta and its APP precursor are still unclear. In our study, Drosophila melanogaster transgenics were established as a model to analyze AD-like pathology caused by APP overexpression. We demonstrated that age related changes in the levels and pattern of synaptic proteins accompanied progressive neurodegeneration and impairment of cognitive functions in APP transgenic flies, but that these changes may be independent from the generation of Abeta. Using novel peptide mimetics of Apolipoprotein-E, COG112 or COG133 proved to be neuroprotective and significantly improved the learning and memory of APP transgenic flies. The development of neurodegeneration and cognitive deficits was corrected by injections of COG112 or COG133, novel mimetics of apolipoprotein-E (apoE) with neuroprotective activities.

Silencing of Amyloid Precursor Protein Expression Using a New Engineered Delta Ribozyme

PubMed Central

Ben Aissa, Manel; April, Marie-Claude; Bergeron, Lucien-Junior; Perreault, Jean-Pierre; Levesque, Georges

2012-01-01

Alzheimer's disease (AD) etiological studies suggest that an elevation in amyloid-β peptides (Aβ) level contributes to aggregations of the peptide and subsequent development of the disease. The major constituent of these amyloid peptides is the 1 to 40–42 residue peptide (Aβ 40−42) derived from amyloid protein precursor (APP). Most likely, reducing Aβ levels in the brain may block both its aggregation and neurotoxicity and would be beneficial for patients with AD. Among the several possible ways to lower Aβ accumulation in the cells, we have selectively chosen to target the primary step in the Aβ cascade, namely, to reduce APP gene expression. Toward this end, we engineered specific SOFA-HDV ribozymes, a new generation of catalytic RNA tools, to decrease APP mRNA levels. Additionally, we demonstrated that APP-ribozymes are effective at decreasing APP mRNA and protein levels as well as Aβ levels in neuronal cells. Our results could lay the groundwork for a new protective treatment for AD. PMID:22482079

An Intracellular Threonine of Amyloid-β Precursor Protein Mediates Synaptic Plasticity Deficits and Memory Loss

PubMed Central

Lombino, Franco; Biundo, Fabrizio; Tamayev, Robert; Arancio, Ottavio; D’Adamio, Luciano

2013-01-01

Mutations in Amyloid-ß Precursor Protein (APP) and BRI2/ITM2b genes cause Familial Alzheimer and Danish Dementias (FAD/FDD), respectively. APP processing by BACE1, which is inhibited by BRI2, yields sAPPß and ß-CTF. ß-CTF is cleaved by gamma-secretase to produce Aß. A knock-in mouse model of FDD, called FDDKI, shows deficits in memory and synaptic plasticity, which can be attributed to sAPPß/ß-CTF but not Aß. We have investigated further the pathogenic function of ß-CTF focusing on Thr668 of ß-CTF because phosphorylation of Thr668 is increased in AD cases. We created a knock-in mouse bearing a Thr668Ala mutation (APPTA mice) that prevents phosphorylation at this site. This mutation prevents the development of memory and synaptic plasticity deficits in FDDKI mice. These data are consistent with a role for the carboxyl-terminal APP domain in the pathogenesis of dementia and suggest that averting the noxious role of Thr668 is a viable therapeutic strategy for human dementias. PMID:23451158

Preserved Fronto-Striatal Plasticity and Enhanced Procedural Learning in a Transgenic Mouse Model of Alzheimer's Disease Overexpressing Mutant "hAPPswe"

ERIC Educational Resources Information Center

Middei, Silvia; Geracitano, Raffaella; Caprioli, Antonio; Mercuri, Nicola; Ammassari-Teule, Martine

2004-01-01

Mutations in the amyloid precursor protein (APP) gene inducing abnormal processing and deposition of [beta]-amyloid protein in the brain have been implicated in the pathogenesis of Alzheimer's disease (AD). Although Tg2576 mice with the Swedish mutation ("hAPPswe") exhibit age-related [Alpha][beta]-plaque formation in brain regions like the…

Amyloid precursor protein mRNA levels in Alzheimer's disease brain.

PubMed

Preece, Paul; Virley, David J; Costandi, Moheb; Coombes, Robert; Moss, Stephen J; Mudge, Anne W; Jazin, Elena; Cairns, Nigel J

2004-03-17

Insoluble beta-amyloid deposits in Alzheimer's disease (AD) brain are proteolytically derived from the membrane bound amyloid precursor protein (APP). The APP gene is differentially spliced to produce isoforms that can be classified into those containing a Kunitz-type serine protease inhibitor domain (K(+), APP(751), APP(770), APRP(365) and APRP(563)), and those without (K(-), APP(695) and APP(714)). Given the hypothesis that Abeta is a result of aberrant catabolism of APP, differential expression of mRNA isoforms containing protease inhibitors might play an active role in the pathology of AD. We took 513 cerebral cortex samples from 90 AD and 81 control brains and quantified the mRNA isoforms of APP with TaqMan real-time RT-PCR. After adjustment for age at death, brain pH and gender we found a change in the ratio of KPI(+) to KPI(-) mRNA isoforms of APP. Three separate probes, designed to recognise only KPI(+) mRNA species, gave increases of between 28% and 50% in AD brains relative to controls (p=0.002). There was no change in the mRNA levels of KPI-(APP 695) (p=0.898). Therefore, whilst KPI-mRNA levels remained stable the KPI(+) species increased specifically in the AD brains.

APP Regulates Microglial Phenotype in a Mouse Model of Alzheimer's Disease

PubMed Central

Manocha, Gunjan D.; Floden, Angela M.; Rausch, Keiko; Kulas, Joshua A.; McGregor, Brett A.; Rojanathammanee, Lalida; Puig, Kelley R.; Puig, Kendra L.; Karki, Sanjib; Nichols, Michael R.; Darland, Diane C.; Porter, James E.

2016-01-01

Prior work suggests that amyloid precursor protein (APP) can function as a proinflammatory receptor on immune cells, such as monocytes and microglia. Therefore, we hypothesized that APP serves this function in microglia during Alzheimer's disease. Although fibrillar amyloid β (Aβ)-stimulated cytokine secretion from both wild-type and APP knock-out (mAPP−/−) microglial cultures, oligomeric Aβ was unable to stimulate increased secretion from mAPP−/− cells. This was consistent with an ability of oligomeric Aβ to bind APP. Similarly, intracerebroventricular infusions of oligomeric Aβ produced less microgliosis in mAPP−/− mice compared with wild-type mice. The mAPP−/− mice crossed to an APP/PS1 transgenic mouse line demonstrated reduced microgliosis and cytokine levels and improved memory compared with wild-type mice despite robust fibrillar Aβ plaque deposition. These data define a novel function for microglial APP in regulating their ability to acquire a proinflammatory phenotype during disease. SIGNIFICANCE STATEMENT A hallmark of Alzheimer's disease (AD) brains is the accumulation of amyloid β (Aβ) peptide within plaques robustly invested with reactive microglia. This supports the notion that Aβ stimulation of microglial activation is one source of brain inflammatory changes during disease. Aβ is a cleavage product of the ubiquitously expressed amyloid precursor protein (APP) and is able to self-associate into a wide variety of differently sized and structurally distinct multimers. In this study, we demonstrate both in vitro and in vivo that nonfibrillar, oligomeric forms of Aβ are able to interact with the parent APP protein to stimulate microglial activation. This provides a mechanism by which metabolism of APP results in possible autocrine or paracrine Aβ production to drive the microgliosis associated with AD brains. PMID:27511018

Activation of extrasynaptic, but not synaptic, NMDA receptors modifies amyloid precursor protein expression pattern and increases amyloid-ß production.

PubMed

Bordji, Karim; Becerril-Ortega, Javier; Nicole, Olivier; Buisson, Alain

2010-11-24

Calcium is a key mediator controlling essential neuronal functions depending on electrical activity. Altered neuronal calcium homeostasis affects metabolism of amyloid precursor protein (APP), leading to increased production of β-amyloid (Aβ), and contributing to the initiation of Alzheimer's disease (AD). A linkage between excessive glutamate receptor activation and neuronal Aβ release was established, and recent reports suggest that synaptic and extrasynaptic NMDA receptor (NMDAR) activation may have distinct consequences in plasticity, gene regulation, and neuronal death. Here, we report for the first time that prolonged activation of extrasynaptic NMDAR, but not synaptic NMDAR, dramatically increased the neuronal production of Aβ. This effect was preceded by a shift from APP695 to Kunitz protease inhibitory domain (KPI) containing APPs (KPI-APPs), isoforms exhibiting an important amyloidogenic potential. Conversely, after synaptic NMDAR activation, we failed to detect any KPI-APP expression and neuronal Aβ production was not modified. Calcium imaging data showed that intracellular calcium concentration after extrasynaptic NMDAR stimulation was lower than after synaptic activation. This suggests distinct signaling pathways for each pool of receptors. We found that modification of neuronal APP expression pattern triggered by extrasynaptic NMDAR activation was regulated at an alternative splicing level involving calcium-/calmodulin-dependent protein kinase IV, but overall APP expression remained identical. Finally, memantine dose-dependently inhibited extrasynaptic NMDAR-induced KPI-APPs expression as well as neuronal Aβ release. Altogether, these data suggest that a chronic activation of extrasynaptic NMDAR promotes amyloidogenic KPI-APP expression leading to neuronal Aβ release, representing a causal risk factor for developing AD.

Memory Enhancing Effect of Black Pepper in the AlCl3 Induced Neurotoxicity Mouse Model is Mediated Through Its Active Component Chavicine.

PubMed

Iqbal, Ghazala; Iqbal, Anila; Mahboob, Aamra; Farhat, Syeda M; Ahmed, Touqeer

Black pepper (Piper nigrum Linn.) has vital pharmacological properties with profound effects on central nervous system. Neurotoxic agents like Aluminum Chloride (AlCl3) cause the oxidative stress and result in improper processing of amyloid proteins leading to accumulation of amyloid β plaques. The study aimed to explore the neuroprotective potential of black pepper (BP) extract (12.5mg/kg/day) on memory enhancement and its effect on expression of amyloid precursor protein (APP) isoforms (APP770 and APP695) in AlCl3 induced neurotoxicity (250mg/kg) mouse model. The study included the isolation and identification of pure compound from BP (chavicine) which was found pharmacologically active. Morris water maze test, elevated plus maze, fear conditioning, context and cue dependent test and social preference tests were performed to investigate the learning and memory. Gene expression (APP isoforms) and in-vitro and ex-vivo DPPH free radical scavenging activity were performed to evaluate the role of BP. BP significantly improved memory in AlCl3 induced neurotoxicity mouse model along with effectively decreasing the expression of APP770 (amyloidogenic) isoform and improved level of APP695 (non-amyloidogenic) in hippocampus, amygdala and cortex. Fear extinction learning was considerably improved in BP treated group (7.83±2.03) than AlCl3 induced neurotoxicity group (39.75±4.25). In the hippocampus, BP significantly reduced the expression of APP770 (0.37±0.05) as compared to AlCl3 induced neurotoxicity group (0.72±0.06), and effectively increased (34.80±1.39) the percentage inhibition of DPPH free radicals as compared to AlCl3 induced neurotoxicity group (14±2.68). The study revealed that BP improves memory and chavicine is a lead compound producing pharmacological effects of BP.

Chronic Cladribine Administration Increases Amyloid Beta Peptide Generation and Plaque Burden in Mice

PubMed Central

Hayes, Crystal D.; Dey, Debleena; Palavicini, Juan Pablo; Wang, Hongjie; Araki, Wataru; Lakshmana, Madepalli K.

2012-01-01

Background The clinical uses of 2-chloro-2′-deoxyadenosine (2-CDA) or cladribine which was initially prescribed to patients with hematological and lymphoid cancers is now extended to treat patients with multiple sclerosis (MS). Previous data has shown that 2-CDA has high affinity to the brain and readily passes through the blood brain barrier reaching CSF concentrations 25% of that found in plasma. However, whether long-term administration of 2-CDA can lead to any adverse effects in patients or animal models is not yet clearly known. Methodology Here we show that exposure of 2-CDA to CHO cells stably expressing wild-type APP751 increased generation and secretion of amyloid β peptide (Aβ) in to the conditioned medium. Interestingly, increased Aβ levels were noticed even at non-toxic concentrations of 2-CDA. Remarkably, chronic treatment of APdE9 mice, a model of Alzheimer's disease with 2-CDA for 60 days increased amyloid plaque burden by more than 1-fold. Increased Aβ generation appears to result from increased turnover of APP as revealed by cycloheximide-chase experiments. Additionally, surface labeling of APP with biotin and immunoprecipitation of surface labeled proteins with anti-biotin antibody also indicated increased APP at the cell surface in 2-CDA treated cells compared to controls. Increased turnover of APP by 2-CDA in turn might be a consequence of decreased protein levels of PIN 1, which is known to regulate cis-trans isomerization and phosphorylation of APP. Most importantly, like many other oncology drugs, 2-CDA administration led to significant delay in acquiring a reward-based learning task in a T maze paradigm. Conclusions Taken together, these data provide compelling evidence for the first time that chronic 2-CDA administration can increase amyloidogenic processing of APP leading to robustly increased plaque burden which may be responsible for the observed deficits in learning skills. Thus chronic treatment of mice with 2-CDA can have deleterious effects in vivo. PMID:23056220

Macroautophagy-generated increase of lysosomal amyloid β-protein mediates oxidant-induced apoptosis of cultured neuroblastoma cells

PubMed Central

Terman, Alexei; Hallbeck, Martin; Dehvari, Nodi; Cowburn, Richard F.; Benedikz, Eirikur; Kågedal, Katarina; Cedazo-Minguez, Angel; Marcusson, Jan

2011-01-01

Increasing evidence suggests the toxicity of intracellular amyloid β-protein (Aβ) to neurons, as well as the involvement of oxidative stress in Alzheimer disease (AD). Here we show that normobaric hyperoxia (exposure of cells to 40% oxygen for five days), and consequent activation of macroautophagy and accumulation of Aβ within lysosomes, induced apoptosis in differentiated SH-SY5Y neuroblastoma cells. Cells under hyperoxia showed: (1) increased numbers of autophagic vacuoles that contained amyloid precursor protein (APP) as well as Aβ monomers and oligomers, (2) increased reactive oxygen species production, and (3) enhanced apoptosis. Oxidant-induced apoptosis positively correlated with cellular Aβ production, being the highest in cells that were stably transfected with APP Swedish KM670/671NL double mutation. Inhibition of γ-secretase, prior and/or in parallel to hyperoxia, suggested that the increase of lysosomal Aβ resulted mainly from its autophagic uptake, but also from APP processing within autophagic vacuoles. The oxidative stress-mediated effects were prevented by macroautophagy inhibition using 3-methyladenine or ATG5 downregulation. Our results suggest that upregulation of macroautophagy and resulting lysosomal Aβ accumulation are essential for oxidant-induced apoptosis in cultured neuroblastoma cells and provide additional support for the interactive role of oxidative stress and the lysosomal system in AD-related neurodegeneration. PMID:22108004

Genetically Augmenting Aβ42 Levels in Skeletal Muscle Exacerbates Inclusion Body Myositis-Like Pathology and Motor Deficits in Transgenic Mice

PubMed Central

Kitazawa, Masashi; Green, Kim N.; Caccamo, Antonella; LaFerla, Frank M.

2006-01-01

The pathogenic basis of inclusion body myositis (IBM), the leading muscle degenerative disease afflicting the elderly, is unknown, although the histopathological features are remarkably similar to those observed in Alzheimer’s disease. One leading hypothesis is that the buildup of amyloid-β (Aβ) peptide within selective skeletal muscle fibers contributes to the degenerative phenotype. Aβ is a small peptide derived via endoproteolysis of the amyloid precursor protein (APP). To determine the pathogenic effect of augmenting Aβ42 levels in skeletal muscle, we used a genetic approach to replace the endogenous wild-type presenilin-1 (PS1) allele with the PS1M146V allele in MCK-APP mice. Although APP transgene expression was unaltered, Aβ levels, particularly Aβ42, were elevated in skeletal muscle of the double transgenic (MCK-APP/PS1) mice compared to the parental MCK-APP line. Elevated phospho-tau accumulation was found in the MCK-APP/PS1 mice, and the greater activation of GSK-3β and cdk5 were observed. Other IBM-like pathological features, such as inclusion bodies and inflammatory infiltrates, were more severe and prominent in the MCK-APP/PS1 mice. Motor coordination and balance were more adversely affected and manifested at an earlier age in the MCK-APP/PS1 mice. The data presented here provide experimental evidence that Aβ42 plays a proximal and critical role in the muscle degenerative process. PMID:16723713

Chimeric proteins combining phosphatase and cellulose-binding activities: proof-of-concept and application in the hydrolysis of paraoxon.

PubMed

Gonçalves, Larissa M; Chaimovich, Hernan; Cuccovia, Iolanda M; Marana, Sandro R

2014-05-01

Phosphatases for organophosphate degradation and carbohydrate-binding domains (CBMs) have potential biotechnological applications. As a proof-of-concept, a soluble chimeric protein that combines acid phosphatase (AppA) from Escherichia coli and a CBM from Xanthomonas axonopodis pv. citri (AppA-CBM) was produced in E.coli. AppACBM adsorbed in microcrystalline cellulose Avicel PH101 catalyzed the hydrolysis of p-nitrophenyl phosphate (PNPP). The binding to microcrystalline cellulose displayed saturation behavior with an apparent binding constant (Kb) of 22 ± 5 mg and a maximum binding (Bmax) of 1.500 ± 0.001 enzyme units. Binding was highest at pH 2.5 and decreased above pH 6.5, as previously observed for family 2 CBMs. The Km values for PNPP of AppA-CBM and native AppA were identical (2.7 mM). To demonstrate that this strategy for protein engineering has practical applications and is largely functional, even for phosphatases exhibiting diverse folds, a chimeric protein combining human paraoxonase 1 (hPON1) and the CBM was produced. Both PON1-CBM and hPON1 had identical K_m values for paraoxon (1.3 mM). Additionally, hPON1 bound to microcrystalline cellulose with a Kb of 27 ± 3 mg, the same as that observed for AppA-CBM. These data show that the phosphatase domains are as functional in both of the chimeric proteins as they are in the native enzymes and that the CBM domain maintains the same cellulose affinity. Therefore, the engineering of chimeric proteins combining domains of phosphatases and CBMs is fully feasible, resulting in chimeric enzymes that exhibit potential for OP detoxification.

Alpha-Secretase ADAM10 Regulation: Insights into Alzheimer’s Disease Treatment

PubMed Central

Peron, Rafaela; Vatanabe, Izabela Pereira; Manzine, Patricia Regina; Camins, Antoni

2018-01-01

ADAM (a disintegrin and metalloproteinase) is a family of widely expressed, transmembrane and secreted proteins of approximately 750 amino acids in length with functions in cell adhesion and proteolytic processing of the ectodomains of diverse cell-surface receptors and signaling molecules. ADAM10 is the main α-secretase that cleaves APP (amyloid precursor protein) in the non-amyloidogenic pathway inhibiting the formation of β-amyloid peptide, whose accumulation and aggregation leads to neuronal degeneration in Alzheimer’s disease (AD). ADAM10 is a membrane-anchored metalloprotease that sheds, besides APP, the ectodomain of a large variety of cell-surface proteins including cytokines, adhesion molecules and notch. APP cleavage by ADAM10 results in the production of an APP-derived fragment, sAPPα, which is neuroprotective. As increased ADAM10 activity protects the brain from β-amyloid deposition in AD, this strategy has been proved to be effective in treating neurodegenerative diseases, including AD. Here, we describe the physiological mechanisms regulating ADAM10 expression at different levels, aiming to propose strategies for AD treatment. We report in this review on the physiological regulation of ADAM10 at the transcriptional level, by epigenetic factors, miRNAs and/or translational and post-translational levels. In addition, we describe the conditions that can change ADAM10 expression in vitro and in vivo, and discuss how this knowledge may help in AD treatment. Regulation of ADAM10 is achieved by multiple mechanisms that include transcriptional, translational and post-translational strategies, which we will summarize in this review. PMID:29382156

Acute γ-secretase Inhibition of Nonhuman Primate CNS Shifts Amyloid Precursor Protein (APP) Metabolism from Amyloid-β Production to Alternative APP Fragments without Amyloid-β Rebound

PubMed Central

Cook, Jacquelynn J.; Wildsmith, Kristin R.; Gilberto, David B.; Holahan, Marie A.; Kinney, Gene G.; Mathers, Parker D.; Michener, Maria S.; Price, Eric A.; Shearman, Mark S.; Simon, Adam J.; Wang, Jennifer X.; Wu, Guoxin; Yarasheski, Kevin E.; Bateman, Randall J.

2010-01-01

The accumulation of amyloid beta (Aβ) in Alzheimer’s disease is caused by an imbalance of production and clearance, which leads to increased soluble Aβ species and extracellular plaque formation in the brain. Multiple Aβ-lowering therapies are currently in development: an important goal is to characterize the molecular mechanisms of action and effects on physiological processing of Aβ, as well as other amyloid precursor protein (APP) metabolites, in models which approximate human Aβ physiology. To this end, we report the translation of the human in vivo stable-isotope-labeling kinetics (SILK) method to a rhesus monkey cisterna magna ported (CMP) nonhuman primate model, and use the model to test the mechanisms of action of a γ-secretase inhibitor (GSI). A major concern of inhibiting the enzymes which produce Aβ (β- and γ-secretase) is that precursors of Aβ may accumulate and cause a rapid increase in Aβ production when enzyme inhibition discontinues. In this study, the GSI MK-0752 was administered to conscious CMP rhesus monkeys in conjunction with in vivo stable isotope labeling, and dose-dependently reduced newly generated CNS Aβ. In contrast to systemic Aβ metabolism, CNS Aβ production was not increased after the GSI was cleared. These results indicate that most of the CNS APP was metabolized to products other than Aβ, including C-terminal truncated forms of Aβ: 1–14, 1–15 and 1–16; this demonstrates an alternative degradation pathway for CNS amyloid precursor protein during γ-secretase inhibition. PMID:20463236

Increased BMP6 levels in the brains of Alzheimer's disease patients and APP transgenic mice are accompanied by impaired neurogenesis.

PubMed

Crews, Leslie; Adame, Anthony; Patrick, Christina; Delaney, Alexandra; Pham, Emiley; Rockenstein, Edward; Hansen, Lawrence; Masliah, Eliezer

2010-09-15

During aging and in the progression of Alzheimer's disease (AD), synaptic plasticity and neuronal integrity are disturbed. In addition to the alterations in plasticity in mature neurons, the neurodegenerative process in AD has been shown to be accompanied by alterations in neurogenesis. Members of the bone morphogenetic protein (BMP) family of growth factors have been implicated as important regulators of neurogenesis and neuronal cell fate determination during development; however, their role in adult neurogenesis and in AD is less clear. We show here by qRT-PCR analysis that BMP6 mRNA levels were significantly increased in the hippocampus of human patients with AD and in APP transgenic mice compared to controls. Immunoblot and immunohistochemical analyses confirmed that BMP6 protein levels were increased in human AD brains and APP transgenic mouse brains compared to controls and accumulated around hippocampal plaques. The increased levels of BMP6 were accompanied by defects in hippocampal neurogenesis in AD patients and APP transgenic mice. In support of a role for BMP6 in defective neurogenesis in AD, we show in an in vitro model of adult neurogenesis that treatment with amyloid-β(1-42) protein (Aβ) resulted in increased expression of BMP6, and that exposure to recombinant BMP6 resulted in reduced proliferation with no toxic effects. Together, these results suggest that Aβ-associated increases in BMP6 expression in AD may have deleterious effects on neurogenesis in the hippocampus, and therapeutic approaches could focus on normalization of BMP6 levels to protect against AD-related neurogenic deficits.

Pharmacologic Inhibition of ROCK2 Suppresses Amyloid-β Production in an Alzheimer's Disease Mouse Model

PubMed Central

Herskowitz, Jeremy H.; Feng, Yangbo; Mattheyses, Alexa L.; Hales, Chadwick M.; Higginbotham, Lenora A.; Duong, Duc M.; Montine, Thomas J.; Troncoso, Juan C.; Thambisetty, Madhav; Seyfried, Nicholas T.; Levey, Allan I.

2013-01-01

Alzheimer's disease (AD) is the leading cause of dementia and has no cure. Genetic, cell biological, and biochemical studies suggest that reducing amyloid-β (Aβ) production may serve as a rational therapeutic avenue to delay or prevent AD progression. Inhibition of RhoA, a Rho GTPase family member, is proposed to curb Aβ production. However, a barrier to this hypothesis has been the limited understanding of how the principal downstream effectors of RhoA, Rho-associated, coiled-coil containing protein kinase (ROCK) 1 and ROCK2, modulate Aβ generation. Here, we report that ROCK1 knockdown increased endogenous human Aβ production, whereas ROCK2 knockdown decreased Aβ levels. Inhibition of ROCK2 kinase activity, using an isoform-selective small molecule (SR3677), suppressed β-site APP cleaving enzyme 1 (BACE1) enzymatic action and diminished production of Aβ in AD mouse brain. Immunofluorescence and confocal microscopy analyses revealed that SR3677 alters BACE1 endocytic distribution and promotes amyloid precursor protein (APP) traffic to lysosomes. Moreover, SR3677 blocked ROCK2 phosphorylation of APP at threonine 654 (T654); in neurons, T654 was critical for APP processing to Aβ. These observations suggest that ROCK2 inhibition reduces Aβ levels through independent mechanisms. Finally, ROCK2 protein levels were increased in asymptomatic AD, mild cognitive impairment, and AD brains, demonstrating that ROCK2 levels change in the earliest stages of AD and remain elevated throughout disease progression. Collectively, these findings highlight ROCK2 as a mechanism-based therapeutic target to combat Aβ production in AD. PMID:24305806

Axonal Membrane Proteins Are Transported in Distinct Carriers: A Two-Color Video Microscopy Study in Cultured Hippocampal NeuronsV⃞

PubMed Central

Kaether, Christoph; Skehel, Paul; Dotti, Carlos G.

2000-01-01

Neurons transport newly synthesized membrane proteins along axons by microtubule-mediated fast axonal transport. Membrane proteins destined for different axonal subdomains are thought to be transported in different transport carriers. To analyze this differential transport in living neurons, we tagged the amyloid precursor protein (APP) and synaptophysin (p38) with green fluorescent protein (GFP) variants. The resulting fusion proteins, APP-yellow fluorescent protein (YFP), p38-enhanced GFP, and p38-enhanced cyan fluorescent protein, were expressed in hippocampal neurons, and the cells were imaged by video microscopy. APP-YFP was transported in elongated tubules that moved extremely fast (on average 4.5 μm/s) and over long distances. In contrast, p38-enhanced GFP-transporting structures were more vesicular and moved four times slower (0.9 μm/s) and over shorter distances only. Two-color video microscopy showed that the two proteins were sorted to different carriers that moved with different characteristics along axons of doubly transfected neurons. Antisense treatment using oligonucleotides against the kinesin heavy chain slowed down the long, continuous movement of APP-YFP tubules and increased frequency of directional changes. These results demonstrate for the first time directly the sorting and transport of two axonal membrane proteins into different carriers. Moreover, the extremely fast-moving tubules represent a previously unidentified type of axonal carrier. PMID:10749925

Trehalose Alters Subcellular Trafficking and the Metabolism of the Alzheimer-associated Amyloid Precursor Protein.

PubMed

Tien, Nguyen T; Karaca, Ilker; Tamboli, Irfan Y; Walter, Jochen

2016-05-13

The disaccharide trehalose is commonly considered to stimulate autophagy. Cell treatment with trehalose could decrease cytosolic aggregates of potentially pathogenic proteins, including mutant huntingtin, α-synuclein, and phosphorylated tau that are associated with neurodegenerative diseases. Here, we demonstrate that trehalose also alters the metabolism of the Alzheimer disease-related amyloid precursor protein (APP). Cell treatment with trehalose decreased the degradation of full-length APP and its C-terminal fragments. Trehalose also reduced the secretion of the amyloid-β peptide. Biochemical and cell biological experiments revealed that trehalose alters the subcellular distribution and decreases the degradation of APP C-terminal fragments in endolysosomal compartments. Trehalose also led to strong accumulation of the autophagic marker proteins LC3-II and p62, and decreased the proteolytic activation of the lysosomal hydrolase cathepsin D. The combined data indicate that trehalose decreases the lysosomal metabolism of APP by altering its endocytic vesicular transport. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Reference intervals for acute phase protein and serum protein electrophoresis values in captive Asian elephants (Elephas maximus).

PubMed

Isaza, Ramiro; Wiedner, Ellen; Hiser, Sarah; Cray, Carolyn

2014-09-01

Acute phase protein (APP) immunoassays and serum protein electrophoresis (SPEP) are assays for evaluating the inflammatory response and have use as diagnostic tools in a variety of species. Acute phase proteins are markers of inflammation that are highly conserved across different species while SPEP separates and quantifies serum protein fractions based on their physical properties. In the current study, serum samples from 35 clinically healthy Asian elephants (Elephas maximus) were analyzed using automated assays for C-reactive protein, serum amyloid A, and haptoglobin and SPEP. Robust methods were used to generate reference intervals for the APPs: C-reactive protein (1.3-12.8 mg/l), serum amyloid A (0-47.5 mg/l), and haptoglobin (0-1.10 mg/ml). In addition, SPEP was performed on these samples to establish reference intervals for each protein fraction. A combination of APPs and SPEP measurements are valuable adjunctive diagnostic tools in elephant health care. © 2014 The Author(s).

The circular RNA ciRS-7 promotes APP and BACE1 degradation in an NF-κB-dependent manner.

PubMed

Shi, Zhemin; Chen, Ting; Yao, Qingbin; Zheng, Lina; Zhang, Zhen; Wang, Jingzhao; Hu, Zhimei; Cui, Hongmei; Han, Yawei; Han, Xiaohui; Zhang, Kun; Hong, Wei

2017-04-01

The aberrant accumulation of β-amyloid peptide (Aβ) in the brain is a key feature of Alzheimer's disease (AD), and enhanced cleavage of β-amyloid precursor protein (APP) by β-site APP-cleaving enzyme 1 (BACE1) has a major causative role in AD. Despite their prominence in AD pathogenesis, the regulation of BACE1 and APP is incompletely understood. In this study, we report that the circular RNA circular RNA sponge for miR-7 (ciRS-7) has an important role in regulating BACE1 and APP protein levels. Previous studies have shown that ciRS-7, which is highly expressed in the human brain, is down-regulated in the brain of people with AD but the relevance of this finding was not clear. We have found that ciRS-7 is not involved in the regulation of APP and BACE1 gene expression, but instead reduces the protein levels of APP and BACE1 by promoting their degradation via the proteasome and lysosome. Consequently, overexpression of ciRS-7 reduces the generation of Aβ, indicating a potential neuroprotective role of ciRS-7. Our data also suggest that ciRS-7 modulates APP and BACE1 levels in a nuclear factor-κB (NF-κB)-dependent manner: ciRS-7 expression inhibits translation of NF-κB and induces its cytoplasmic localization, thus derepressing expression of UCHL1, which promotes APP and BACE1 degradation. Additionally, we demonstrated that APP reduces the level of ciRS-7, revealing a mutual regulation of ciRS-7 and APP. Taken together, our data provide a molecular mechanism implicating reduced ciRS-7 expression in AD, suggesting that ciRS-7 may represent a useful target in the development of therapeutic strategies for AD. © 2017 Federation of European Biochemical Societies.

Serum acute phase protein concentrations in female dogs with mammary tumors.

PubMed

Tecles, Fernando; Caldín, Marco; Zanella, Anna; Membiela, Francisco; Tvarijonaviciute, Asta; Subiela, Silvia Martínez; Cerón, José Joaquín

2009-03-01

Acute phase proteins (APPs) are proteins whose concentrations in serum change after any inflammatory stimulus or tissue damage. The aim of the current study was to evaluate 3 positive APPs (C-reactive protein, serum amyloid A, and haptoglobin) and 1 negative APP (albumin) in female dogs with mammary neoplasia. Acute phase proteins were studied in 70 female dogs aged 8-12 years in the following groups: healthy (n = 10); mammary tumors in stages I (n = 19), II (n = 5), III (n = 6), IV (n = 5), and V (n = 7); and with mammary neoplasia plus a concomitant disease (n = 18). In animals with mammary neoplasia, significant increases of positive APPs were only detected in those that had metastasis or a neoplasm with a diameter greater than 5 cm and ulceration. Dogs with mammary neoplasia and a concomitant disease also had high C-reactive protein concentrations. Albumin concentration was decreased in animals with metastasis and with a concomitant disease. The results of the present study indicate that the acute phase response could be stimulated in female dogs with mammary gland tumors because of different factors, such as metastasis, large size of the primary mass, and ulceration or secondary inflammation of the neoplasm.

Use of acute phase proteins for the clinical assessment and management of canine leishmaniosis: general recommendations.

PubMed

Ceron, J J; Pardo-Marin, L; Caldin, M; Furlanello, T; Solano-Gallego, L; Tecles, F; Bernal, L; Baneth, G; Martinez-Subiela, S

2018-06-20

Dogs with canine leishmaniosis (CanL) due to Leishmania infantum can show a wide spectrum of clinical and clinicopathological findings at the time of diagnosis. The aim of this paper is to describe the possible application of acute phase proteins (APPs) for the characterization and management of this disease, based on previously published information on the utility of APPs in CanL and the experience of the authors in using APPs as analytes in the profiling of canine diseases. Dogs diagnosed with L. infantum infection by serology, polymerase chain reaction, cytological or histopathological identification, can be divided into three groups based on their clinical condition at physical examination and their APPs concentrations: Group 1: dogs with no clinical signs on physical examination and APPs in reference range; Group 2: dogs with changes in APPs but no clinical signs on physical examination; Group 3: dogs with clinical signs and changes in APPs. This report describes the main characteristics of each group as well as its association with the clinical classification schemes of CanL. APPs concentration can be a useful clinical tool to characterize and manage CanL.

Amyloid precursor protein modulates Nav1.6 sodium channel currents through a Go-coupled JNK pathway.

PubMed

Li, Shao; Wang, Xi; Ma, Quan-Hong; Yang, Wu-Lin; Zhang, Xiao-Gang; Dawe, Gavin S; Xiao, Zhi-Cheng

2016-12-23

Amyloid precursor protein (APP), commonly associated with Alzheimer's disease, also marks axonal degeneration. In the recent studies, we demonstrated that APP aggregated at nodes of Ranvier (NORs) in myelinated central nervous system (CNS) axons and interacted with Nav1.6. However, the physiological function of APP remains unknown. In this study, we described reduced sodium current densities in APP knockout hippocampal neurons. Coexpression of APP or its intracellular domains containing a VTPEER motif with Na v 1.6 sodium channels in Xenopus oocytes resulted in an increase in peak sodium currents, which was enhanced by constitutively active Go mutant and blocked by a dominant negative mutant. JNK and CDK5 inhibitor attenuated increases in Nav1.6 sodium currents induced by overexpression of APP. Nav1.6 sodium currents were increased by APPT668E (mutant Thr to Glu) and decreased by T668A (mutant Thr to ALa) mutant, respectively. The cell surface expression of Nav1.6 sodium channels in the white matter of spinal cord and the spinal conduction velocity is decreased in APP, p35 and JNK3 knockout mice. Therefore, APP modulates Nav1.6 sodium channels through a Go-coupled JNK pathway, which is dependent on phosphorylation of APP at Thr668.

Amyloid precursor protein modulates Nav1.6 sodium channel currents through a Go-coupled JNK pathway

PubMed Central

Li, Shao; Wang, Xi; Ma, Quan-Hong; Yang, Wu-lin; Zhang, Xiao-Gang; Dawe, Gavin S.; Xiao, Zhi-Cheng

2016-01-01

Amyloid precursor protein (APP), commonly associated with Alzheimer’s disease, also marks axonal degeneration. In the recent studies, we demonstrated that APP aggregated at nodes of Ranvier (NORs) in myelinated central nervous system (CNS) axons and interacted with Nav1.6. However, the physiological function of APP remains unknown. In this study, we described reduced sodium current densities in APP knockout hippocampal neurons. Coexpression of APP or its intracellular domains containing a VTPEER motif with Nav1.6 sodium channels in Xenopus oocytes resulted in an increase in peak sodium currents, which was enhanced by constitutively active Go mutant and blocked by a dominant negative mutant. JNK and CDK5 inhibitor attenuated increases in Nav1.6 sodium currents induced by overexpression of APP. Nav1.6 sodium currents were increased by APPT668E (mutant Thr to Glu) and decreased by T668A (mutant Thr to ALa) mutant, respectively. The cell surface expression of Nav1.6 sodium channels in the white matter of spinal cord and the spinal conduction velocity is decreased in APP, p35 and JNK3 knockout mice. Therefore, APP modulates Nav1.6 sodium channels through a Go-coupled JNK pathway, which is dependent on phosphorylation of APP at Thr668. PMID:28008944

Bepridil decreases Aβ and calcium levels in the thalamus after middle cerebral artery occlusion in rats

PubMed Central

Sarajärvi, Timo; Lipsanen, Anu; Mäkinen, Petra; Peräniemi, Sirpa; Soininen, Hilkka; Haapasalo, Annakaisa; Jolkkonen, Jukka; Hiltunen, Mikko

2012-01-01

Alzheimer's disease (AD) and cerebral ischaemia share similar features in terms of altered amyloid precursor protein (APP) processing and β-amyloid (Aβ) accumulation. We have previously shown that Aβ and calcium deposition, and β-secretase activity, are robustly increased in the ipsilateral thalamus after transient middle cerebral artery occlusion (MCAO) in rats. Here, we investigated whether the non-selective calcium channel blocker bepridil, which also inhibits β-secretase cleavage of APP, affects thalamic accumulation of Aβ and calcium and in turn influences functional recovery in rats subjected to MCAO. A 27-day bepridil treatment (50 mg/kg, p.o.) initiated 2 days after MCAO significantly decreased the levels of soluble Aβ40, Aβ42 and calcium in the ipsilateral thalamus, as compared with vehicle-treated MCAO rats. Expression of seladin-1/DHCR24 protein, which is a potential protective factor against neuronal damage, was decreased at both mRNA and protein levels in the ipsilateral thalamus of MCAO rats. Conversely, bepridil treatment restored seladin-1/DHCR24 expression in the ipsilateral thalamus. Bepridil treatment did not significantly affect heme oxygenase-1- or NAD(P)H quinone oxidoreductase-1-mediated oxidative stress or inflammatory responses in the ipsilateral thalamus of MCAO rats. Finally, bepridil treatment mitigated MCAO-induced alterations in APP processing in the ipsilateral thalamus and improved contralateral forelimb use in MCAO rats. These findings suggest that bepridil is a plausible therapeutic candidate in AD or stroke owing to its multifunctional role in key cellular events that are relevant for the pathogenesis of these diseases. PMID:22805236

Specific interactions between amyloid-β peptide and curcumin derivatives: Ab initio molecular simulations

NASA Astrophysics Data System (ADS)

Ishimura, Hiromi; Kadoya, Ryushi; Suzuki, Tomoya; Murakawa, Takeru; Shulga, Sergiy; Kurita, Noriyuki

2015-07-01

Alzheimer's disease is caused by accumulation of amyloid-β (Aβ) peptides in a brain. To suppress the production of Aβ peptides, it is effective to inhibit the cleavage of amyloid precursor protein (APP) by secretases. However, because the secretases also play important roles to produce vital proteins for human body, inhibitors for the secretases may have side effects. To propose new agents for protecting the cleavage site of APP from the attacking of the γ-secretase, we have investigated here the specific interactions between a short APP peptide and curcumin derivatives, using protein-ligand docking as well as ab initio molecular simulations.

Activation of Ras-ERK Signaling and GSK-3 by Amyloid Precursor Protein and Amyloid Beta Facilitates Neurodegeneration in Alzheimer's Disease.

PubMed

Kirouac, Lisa; Rajic, Alexander J; Cribbs, David H; Padmanabhan, Jaya

2017-01-01

It is widely accepted that amyloid β (Aβ) generated from amyloid precursor protein (APP) oligomerizes and fibrillizes to form neuritic plaques in Alzheimer's disease (AD), yet little is known about the contribution of APP to intracellular signaling events preceding AD pathogenesis. The data presented here demonstrate that APP expression and neuronal exposure to oligomeric Aβ42 enhance Ras/ERK signaling cascade and glycogen synthase kinase 3 (GSK-3) activation. We find that RNA interference (RNAi)-directed knockdown of APP in B103 rat neuroblastoma cells expressing APP inhibits Ras-ERK signaling and GSK-3 activation, indicating that APP acts upstream of these signal transduction events. Both ERK and GSK-3 are known to induce hyperphosphorylation of tau and APP at Thr668, and our findings suggest that aberrant signaling by APP facilitates these events. Supporting this notion, analysis of human AD brain samples showed increased expression of Ras, activation of GSK-3, and phosphorylation of APP and tau, which correlated with Aβ levels in the AD brains. Furthermore, treatment of primary rat neurons with Aβ recapitulated these events and showed enhanced Ras-ERK signaling, GSK-3 activation, upregulation of cyclin D1, and phosphorylation of APP and tau. The finding that Aβ induces Thr668 phosphorylation on APP, which enhances APP proteolysis and Aβ generation, denotes a vicious feedforward mechanism by which APP and Aβ promote tau hyperphosphorylation and neurodegeneration in AD. Based on these results, we hypothesize that aberrant proliferative signaling by APP plays a fundamental role in AD neurodegeneration and that inhibition of this would impede cell cycle deregulation and neurodegeneration observed in AD.

Amyloid Precursor Protein Translation Is Regulated by a 3’UTR Guanine Quadruplex

PubMed Central

Sharoni, Michal; Olson, Kalee; Sebastian, Neeraj P.; Ansaloni, Sara; Schweitzer-Stenner, Reinhard; Akins, Michael R.; Bevilacqua, Philip C.; Saunders, Aleister J.

2015-01-01

A central event in Alzheimer’s disease is the accumulation of amyloid β (Aβ) peptides generated by the proteolytic cleavage of the amyloid precursor protein (APP). APP overexpression leads to increased Aβ generation and Alzheimer’s disease in humans and altered neuronal migration and increased long term depression in mice. Conversely, reduction of APP expression results in decreased Aβ levels in mice as well as impaired learning and memory and decreased numbers of dendritic spines. Together these findings indicate that therapeutic interventions that aim to restore APP and Aβ levels must do so within an ideal range. To better understand the effects of modulating APP levels, we explored the mechanisms regulating APP expression focusing on post-transcriptional regulation. Such regulation can be mediated by RNA regulatory elements such as guanine quadruplexes (G-quadruplexes), non-canonical structured RNA motifs that affect RNA stability and translation. Via a bioinformatics approach, we identified a candidate G-quadruplex within the APP mRNA in its 3’UTR (untranslated region) at residues 3008–3027 (NM_201414.2). This sequence exhibited characteristics of a parallel G-quadruplex structure as revealed by circular dichroism spectrophotometry. Further, as with other G-quadruplexes, the formation of this structure was dependent on the presence of potassium ions. This G-quadruplex has no apparent role in regulating transcription or mRNA stability as wild type and mutant constructs exhibited equivalent mRNA levels as determined by real time PCR. Instead, we demonstrate that this G-quadruplex negatively regulates APP protein expression using dual luciferase reporter and Western blot analysis. Taken together, our studies reveal post-transcriptional regulation by a 3’UTR G-quadruplex as a novel mechanism regulating APP expression. PMID:26618502

[Effect of hyperforin on learning and memory abilities and Aβ₁₋₄₂, βAPP and BACE1 protein expressions in hippocampus of Alzheimer's disease model mice].

PubMed

Geng, Yan-Na; Wu, Yi-Jun; Zhang, Wen-Xin

2016-08-01

To investigate the effect of the hyperforin (HF) on learning and memory function and Aβ₁₋₄₂, βAPP and BACE1 protein expressions in hippocampus of five-month-old APP/PS1 double transgenic mice, and discuss the underlying mechanism of HF. The five-month-old APP/PS1 double transgenic mice were randomly divided into the model group, rosiglitazone group (12 mg•kg⁻¹•d⁻¹) and HF high dose, middle dose and low dose groups (600, 300 and 150 mg•kg⁻¹•d⁻¹) in each group; in addition, 15C57BL/6J mice with the same months and background were selected as normal group. Drugs were diluted in the same volume before using, and then administrated by ig for 7 months, 1 time a day; the mice in normal group and model group received the same volume of distilled water. The learning and memory ability was tested by Morris water maze; Aβ₁₋₄₂, βAPP and BACE1proteinexpressionlevelswere tested by immunohistochemistry and Western blot. The Morris water maze results showed that as compared with the normal group, the learning and memory ability was significantly impaired in mice of model group (P<0.01); as compared with the model group, the learning and memory ability was improved in mice of rosiglitazone group and HF high, middle and low dose groups(P<0.01 or P<0.05). Immunohistochemistry and western blot results showed thatas compared with the normal group, the Aβ₁₋₄₂, βAPP and BACE1 protein expression levels in hippocampus were significantly increased in mice of model group (P<0.01);as compared with the model group, Aβ₁₋₄₂, βAPP and BACE1 protein expression levels in hippocampus were decreased in mice of rosiglitazone group and HF high, middle and low dose groups (P<0.01 or P<0.05). HF may improve the learning and memory ability of AD model mice via inhibition of βAPP and BACE1 protein expressions, thus reduced the generation of Aβ₁₋₄₂ proteins and amyloid plaque deposits in the brain. Copyright© by the Chinese Pharmaceutical Association.

Bidirectional Regulation of Amyloid Precursor Protein-Induced Memory Defects by Nebula/DSCR1: A Protein Upregulated in Alzheimer's Disease and Down Syndrome

PubMed Central

Shaw, Jillian L.; Zhang, Shixing

2015-01-01

Aging individuals with Down syndrome (DS) have an increased risk of developing Alzheimer's disease (AD), a neurodegenerative disorder characterized by impaired memory. Memory problems in both DS and AD individuals usually develop slowly and progressively get worse with age, but the cause of this age-dependent memory impairment is not well understood. This study examines the functional interactions between Down syndrome critical region 1 (DSCR1) and amyloid-precursor protein (APP), proteins upregulated in both DS and AD, in regulating memory. Using Drosophila as a model, we find that overexpression of nebula (fly homolog of DSCR1) initially protects against APP-induced memory defects by correcting calcineurin and cAMP signaling pathways but accelerates the rate of memory loss and exacerbates mitochondrial dysfunction in older animals. We report that transient upregulation of Nebula/DSCR1 or acute pharmacological inhibition of calcineurin in aged flies protected against APP-induced memory loss. Our data suggest that calcineurin dyshomeostasis underlies age-dependent memory impairments and further imply that chronic Nebula/DSCR1 upregulation may contribute to age-dependent memory impairments in AD in DS. SIGNIFICANCE STATEMENT Most Down syndrome (DS) individuals eventually develop Alzheimer's disease (AD)-like dementia, but mechanisms underlying this age-dependent memory impairment remain poorly understood. This study examines Nebula/Down syndrome critical region 1 (DSCR1) and amyloid-precursor protein (APP), proteins upregulated in both DS and AD, in regulating memory. We uncover a previously unidentified role for Nebula/DSCR1 in modulating APP-induced memory defects during aging. We show that upregulation of Nebula/DSCR1, an inhibitor of calcineurin, rescues APP-induced memory defects in young flies but enhances memory loss of older flies. Excitingly, transient Nebula/DSCR1 overexpression or calcineurin inhibition in aged flies ameliorates APP-mediated memory problems. These results suggest that chronic Nebula/DSCR1 upregulation may contribute to age-dependent memory loss in DS and AD and points to correcting calcineurin signaling as a means to improve memory during aging. PMID:26269644

Bidirectional Regulation of Amyloid Precursor Protein-Induced Memory Defects by Nebula/DSCR1: A Protein Upregulated in Alzheimer's Disease and Down Syndrome.

PubMed

Shaw, Jillian L; Zhang, Shixing; Chang, Karen T

2015-08-12

Aging individuals with Down syndrome (DS) have an increased risk of developing Alzheimer's disease (AD), a neurodegenerative disorder characterized by impaired memory. Memory problems in both DS and AD individuals usually develop slowly and progressively get worse with age, but the cause of this age-dependent memory impairment is not well understood. This study examines the functional interactions between Down syndrome critical region 1 (DSCR1) and amyloid-precursor protein (APP), proteins upregulated in both DS and AD, in regulating memory. Using Drosophila as a model, we find that overexpression of nebula (fly homolog of DSCR1) initially protects against APP-induced memory defects by correcting calcineurin and cAMP signaling pathways but accelerates the rate of memory loss and exacerbates mitochondrial dysfunction in older animals. We report that transient upregulation of Nebula/DSCR1 or acute pharmacological inhibition of calcineurin in aged flies protected against APP-induced memory loss. Our data suggest that calcineurin dyshomeostasis underlies age-dependent memory impairments and further imply that chronic Nebula/DSCR1 upregulation may contribute to age-dependent memory impairments in AD in DS. Most Down syndrome (DS) individuals eventually develop Alzheimer's disease (AD)-like dementia, but mechanisms underlying this age-dependent memory impairment remain poorly understood. This study examines Nebula/Down syndrome critical region 1 (DSCR1) and amyloid-precursor protein (APP), proteins upregulated in both DS and AD, in regulating memory. We uncover a previously unidentified role for Nebula/DSCR1 in modulating APP-induced memory defects during aging. We show that upregulation of Nebula/DSCR1, an inhibitor of calcineurin, rescues APP-induced memory defects in young flies but enhances memory loss of older flies. Excitingly, transient Nebula/DSCR1 overexpression or calcineurin inhibition in aged flies ameliorates APP-mediated memory problems. These results suggest that chronic Nebula/DSCR1 upregulation may contribute to age-dependent memory loss in DS and AD and points to correcting calcineurin signaling as a means to improve memory during aging. Copyright © 2015 the authors 0270-6474/15/3511374-10$15.00/0.

Huperzine A alleviates synaptic deficits and modulates amyloidogenic and nonamyloidogenic pathways in APPswe/PS1dE9 transgenic mice.

PubMed

Wang, Ying; Tang, Xi Can; Zhang, Hai Yan

2012-02-01

Huperzine A (HupA) is a potent acetylcholinesterase inhibitor (AChEI) used in the treatment of Alzheimer's disease (AD). Recently, HupA was shown to be active in modulating the nonamyloidogenic metabolism of β-amyloid precursor protein (APP) in APP-transfected human embryonic kidney cell line (HEK293swe). However, in vivo research concerning the mechanism of HupA in APP transgenic mice has not yet been fully elucidated. The present study indicates that the loss of dendritic spine density and synaptotagmin levels in the brain of APPswe/presenilin-1 (PS1) transgenic mice was significantly ameliorated by chronic HupA treatment and provides evidence that this neuroprotection was associated with reduced amyloid plaque burden and oligomeric β-amyloid (Aβ) levels in the cortex and hippocampus of APPswe/PS1dE9 transgenic mice. Our findings further demonstrate that the amelioration effect of HupA on Aβ deposits may be mediated, at least in part, by regulation of the compromised expression of a disintegrin and metalloprotease 10 (ADAM10) and excessive membrane trafficking of β-site APP cleavage enzyme 1 (BACE1) in these transgenic mice. In addition, extracellular signal-regulated kinases 1/2 (Erk1/2) phosphorylation may also be partially involved in the effect of HupA on APP processing. In conclusion, our work for the first time demonstrates the neuroprotective effect of HupA on synaptic deficits in APPswe/PS1dE9 transgenic mice and further clarifies the potential pharmacological targets for this protective effect, in which modulation of nonamyloidogenic and amyloidogenic APP processing pathways may be both involved. These findings may provide adequate evidence for the clinical and experimental benefits gained from HupA treatment. Copyright © 2011 Wiley Periodicals, Inc.

Targeting neuronal MAPK14/p38α activity to modulate autophagy in the Alzheimer disease brain.

PubMed

Alam, John; Scheper, Wiep

2016-12-01

Dysregulated autophagic-lysosomal degradation of proteins has been linked to the most common genetic defect in familial Alzheimer disease, and has been correlated with disease progression in both human disease and in animal models. Recently, it was demonstrated that the expression of MAPK14/p38α protein is upregulated in the brain of APP-PS1 transgenic Alzheimer mouse and further that genetic deficiency of Mapk14 in the APP-PS1 mouse stimulates macroautophagy/autophagy, which then leads to reduced amyloid pathology via increasing autophagic-lysosomal degradation of BACE1. The findings resolve at least in the context of the APP-PS1 mouse, prior conflicting in vitro observations that have implicated MAPK14 in autophagic processes, and indicate that inhibition of MAPK14 enzyme activity has potential as a therapeutic approach to mitigate a critical physiological defect within neurons of the Alzheimer disease brain. Moreover, the findings suggest that biomarkers of BACE1 activity could be utilized to evaluate the effects of MAPK14 inhibition and other autophagy-inducing therapeutic approaches in human clinical studies, thereby potentially facilitating the clinical development of such agents.

Molecular genetics of Alzheimer disease.

PubMed

St George-Hyslop, P H

1999-01-01

Epidemiological and individual case studies indicate that genetic factors play a significant role in the genesis of Alzheimer Disease (AD). To date, molecular genetic studies in families multiply affected with AD have identified three genes (Presenilin 1-PS1, Presenilin 2-PS2, and beta-amyloid precursor protein--betaAPP) associated with highly penetrant early onset AD, and one gene (Apolipoprotein E) associated with late onset AD. A fifth potential AD susceptibility locus has been mapped to a broad region of chromosome 12, but the responsible gene defect has not yet been identified. Case-control studies comparing the frequency of alleles in numerous other candidate genes have identified a number of additional potential AD genes. However, methodological difficulties and conflicting results in follow-up studies, make it unclear whether allelic variations in these genes are truly pathogenic. Nevertheless, analysis of the biochemical effects of mutations in PS1, PS2, betaAPP at least, suggest a common biochemical effect-namely disturbances in the processing of betaAPP protein. In addition to utility in defining potential therapeutic targets, in some circumstances these genes can also potentially be used as adjunctives in clinical presymptomatic, symptomatic or pharmacogenomic diagnosis.

Targeting neuronal MAPK14/p38α activity to modulate autophagy in the Alzheimer disease brain

PubMed Central

Alam, John; Scheper, Wiep

2016-01-01

ABSTRACT Dysregulated autophagic-lysosomal degradation of proteins has been linked to the most common genetic defect in familial Alzheimer disease, and has been correlated with disease progression in both human disease and in animal models. Recently, it was demonstrated that the expression of MAPK14/p38α protein is upregulated in the brain of APP-PS1 transgenic Alzheimer mouse and further that genetic deficiency of Mapk14 in the APP-PS1 mouse stimulates macroautophagy/autophagy, which then leads to reduced amyloid pathology via increasing autophagic-lysosomal degradation of BACE1. The findings resolve at least in the context of the APP-PS1 mouse, prior conflicting in vitro observations that have implicated MAPK14 in autophagic processes, and indicate that inhibition of MAPK14 enzyme activity has potential as a therapeutic approach to mitigate a critical physiological defect within neurons of the Alzheimer disease brain. Moreover, the findings suggest that biomarkers of BACE1 activity could be utilized to evaluate the effects of MAPK14 inhibition and other autophagy-inducing therapeutic approaches in human clinical studies, thereby potentially facilitating the clinical development of such agents. PMID:27715387

A Presenilin-1 Mutation Identified in Familial Alzheimer Disease with Cotton Wool Plaques Causes a Nearly Complete Loss of γ-Secretase Activity*

PubMed Central

Heilig, Elizabeth A.; Xia, Weiming; Shen, Jie; Kelleher, Raymond J.

2010-01-01

Mutations in presenilin-1 and presenilin-2 (PS1 and PS2) are the most common cause of familial Alzheimer disease. PS1 and PS2 are the presumptive catalytic components of the multisubunit γ-secretase complex, which proteolyzes a number of type I transmembrane proteins, including the amyloid precursor protein (APP) and Notch. APP processing by γ-secretase produces β-amyloid peptides (Aβ40 and Aβ42) that accumulate in the Alzheimer disease brain. Here we identify a pathogenic L435F mutation in PS1 in two affected siblings with early-onset familial Alzheimer disease characterized by deposition of cerebral cotton wool plaques. The L435F mutation resides in a conserved C-terminal PAL sequence implicated in active site conformation and catalytic activity. The impact of PS1 mutations in and around the PAL motif on γ-secretase activity was assessed by expression of mutant PS1 in mouse embryo fibroblasts lacking endogenous PS1 and PS2. Surprisingly, the L435F mutation caused a nearly complete loss of γ-secretase activity, including >90% reductions in the generation of Aβ40, Aβ42, and the APP and Notch intracellular domains. Two nonpathogenic PS1 mutations, P433L and L435R, caused essentially complete loss of γ-secretase activity, whereas two previously identified pathogenic PS1 mutations, P436Q and P436S, caused partial loss of function with substantial reductions in production of Aβ40, Aβ42, and the APP and Notch intracellular domains. These results argue against overproduction of Aβ42 as an essential property of presenilin proteins bearing pathogenic mutations. Rather, our findings provide support for the hypothesis that pathogenic mutations cause a general loss of presenilin function. PMID:20460383

Missing the mark for patient engagement: mHealth literacy strategies and behavior change processes in smoking cessation apps.

PubMed

Paige, Samantha R; Alber, Julia M; Stellefson, Michael L; Krieger, Janice L

2018-05-01

To examine how Transtheoretical Model (TTM)'s processes of change and mHealth literacy strategies are employed in mobile smoking cessation apps. A purposive sample of 100 iTunes apps were coded to assess descriptive (price, type, developer, user-rating) and engagement metrics, including processes of change and mHealth literacy strategies (plain language, usability, interactivity). One-way ANOVAs and independent samples t-tests examined associations between descriptive and engagement metrics. Over half of the apps included 7 (78%) processes of change. Fewer included self-liberation (36%) and reinforcement management (34%). Most apps incorporated plain language, but few integrated usability and interactivity strategies. Hypnotherapy and informational apps included more behavioral processes of change than apps incorporating a combination of features, including gaming, cigarette trackers, and motivational coaching (p<0.01). Apps included behavior change processes but rarely incorporated usability and interactivity features to promote patient engagement. Engagement metrics did not vary by app user-ratings, price-to-download, or developer, including for-profit organizations or government and educational institutions. Providers should acknowledge the popularity of smoking cessation apps as potential cessation aids and communicate their benefits and drawbacks to patients. Future efforts to improve smoking cessation apps should focus on enhancing the quality of tailored and interactive content. Copyright © 2017 Elsevier B.V. All rights reserved.

Cholinergic neurodegeneration in an Alzheimer mouse model overexpressing amyloid-precursor protein with the Swedish-Dutch-Iowa mutations.

PubMed

Foidl, Bettina Maria; Do-Dinh, Patricia; Hutter-Schmid, Bianca; Bliem, Harald R; Humpel, Christian

2016-12-01

Alzheimer's disease (AD) is a chronic neurodegenerative disorder that is mainly characterized by beta-amyloid (Aβ) plaque deposition, Tau pathology and dysfunction of the cholinergic system causing memory impairment. The aim of the present study was to examine (1) anxiety and cognition, (2) Aβ plaque deposition and (3) degeneration of cholinergic neurons in the nucleus basalis of Meynert (nbM) and cortical cholinergic innervation in an Alzheimer mouse model (APP_SweDI; overexpressing amyloid precursor protein (APP) with the Swedish K670N/M671L, Dutch E693Q, and Iowa D694N mutations). Our results show that 12-month-old APP_SweDI mice were more anxious and had more memory impairment. A large number of Aβ plaques were already visible at the age of 6 months and increased with age. A significant decrease in cholinergic neurons was seen in the transgenic mouse model in comparison to the wild-type mice, identified by immunohistochemistry against choline acetyltransferase (ChAT) and p75 neurotrophin receptor as well as by in situ hybridization. Moreover, a significant decrease in cortical cholinergic fiber density was found in the transgenic mice as compared to the wild-type. In the cerebral cortex of APP_SweDI mice, swollen cholinergic varicosities were seen in the vicinity of Aβ plaques. In conclusion, the present study shows that in an AD mouse model (APP_SweDI mice) a high Aβ plaque load in the cortex causes damage to cholinergic axons in the cortex, followed by subsequent retrograde-induced cell death of cholinergic neurons and some forms of compensatory processes. This degeneration was accompanied by enhanced anxiety and impaired cognition. Copyright © 2016 Elsevier Inc. All rights reserved.

Ablation of Prion Protein in Wild Type Human Amyloid Precursor Protein (APP) Transgenic Mice Does Not Alter The Proteolysis of APP, Levels of Amyloid-β or Pathologic Phenotype

PubMed Central

Baybutt, Herbert; Diack, Abigail B.; Kellett, Katherine A. B.; Piccardo, Pedro; Manson, Jean C.

2016-01-01

The cellular prion protein (PrPC) has been proposed to play an important role in the pathogenesis of Alzheimer’s disease. In cellular models PrPC inhibited the action of the β-secretase BACE1 on wild type amyloid precursor protein resulting in a reduction in amyloid-β (Aβ) peptides. Here we have assessed the effect of genetic ablation of PrPC in transgenic mice expressing human wild type amyloid precursor protein (line I5). Deletion of PrPC had no effect on the α- and β-secretase proteolysis of the amyloid precursor protein (APP) nor on the amount of Aβ38, Aβ40 or Aβ42 in the brains of the mice. In addition, ablation of PrPC did not alter Aβ deposition or histopathology phenotype in this transgenic model. Thus using this transgenic model we could not provide evidence to support the hypothesis that PrPC regulates Aβ production. PMID:27447728

Overexpression of amyloid precursor protein increases copper content in HEK293 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suazo, Miriam; Hodar, Christian; Morgan, Carlos

2009-05-15

Amyloid precursor protein (APP) is a transmembrane glycoprotein widely expressed in mammalian tissues and plays a central role in Alzheimer's disease. However, its physiological function remains elusive. Cu{sup 2+} binding and reduction activities have been described in the extracellular APP135-156 region, which might be relevant for cellular copper uptake and homeostasis. Here, we assessed Cu{sup 2+} reduction and {sup 64}Cu uptake in two human HEK293 cell lines overexpressing APP. Our results indicate that Cu{sup 2+} reduction increased and cells accumulated larger levels of copper, maintaining cell viability at supra-physiological levels of Cu{sup 2+} ions. Moreover, wild-type cells exposed to bothmore » Cu{sup 2+} ions and APP135-155 synthetic peptides increased copper reduction and uptake. Complementation of function studies in human APP751 transformed Fre1 defective Saccharomyces cerevisiae cells rescued low Cu{sup 2+} reductase activity and increased {sup 64}Cu uptake. We conclude that Cu{sup 2+} reduction activity of APP facilitates copper uptake and may represent an early step in cellular copper homeostasis.« less

Inhibition of GSK3β-mediated BACE1 expression reduces Alzheimer-associated phenotypes

PubMed Central

Ly, Philip T.T.; Wu, Yili; Zou, Haiyan; Wang, Ruitao; Zhou, Weihui; Kinoshita, Ayae; Zhang, Mingming; Yang, Yi; Cai, Fang; Woodgett, James; Song, Weihong

2012-01-01

Deposition of amyloid β protein (Aβ) to form neuritic plaques in the brain is the pathological hallmark of Alzheimer’s disease (AD). Aβ is generated from sequential cleavages of the β-amyloid precursor protein (APP) by the β- and γ-secretases, and β-site APP-cleaving enzyme 1 (BACE1) is the β-secretase essential for Aβ generation. Previous studies have indicated that glycogen synthase kinase 3 (GSK3) may play a role in APP processing by modulating γ-secretase activity, thereby facilitating Aβ production. There are two highly conserved isoforms of GSK3: GSK3α and GSK3β. We now report that specific inhibition of GSK3β, but not GSK3α, reduced BACE1-mediated cleavage of APP and Aβ production by decreasing BACE1 gene transcription and expression. The regulation of BACE1 gene expression by GSK3β was dependent on NF-κB signaling. Inhibition of GSK3 signaling markedly reduced Aβ deposition and neuritic plaque formation, and rescued memory deficits in the double transgenic AD model mice. These data provide evidence for regulation of BACE1 expression and AD pathogenesis by GSK3β and that inhibition of GSK3 signaling can reduce Aβ neuropathology and alleviate memory deficits in AD model mice. Our study suggests that interventions that specifically target the β-isoform of GSK3 may be a safe and effective approach for treating AD. PMID:23202730

In vivo effects on photosynthesis gene expression of base pair exchanges in the gene encoding the light-responsive BLUF domain of AppA in Rhodobacter sphaeroides.

PubMed

Metz, Sebastian; Hendriks, Johnny; Jäger, Andreas; Hellingwerf, Klaas; Klug, Gabriele

2010-01-01

The Rhodobacter sphaeroides protein AppA has the unique quality of sensing and transmitting light and redox signals. By acting as antirepressor to the PpsR protein, it acts as a major regulator in photosynthesis gene expression. In this study, we show that by introducing amino acid exchanges into the AppA protein, the in vivo activity as an antirepressor can be greatly altered. The tryptophan 104 to phenylalanine (W104F) base exchange greatly diminished blue-light sensitivity of the BLUF domain. From the obtained in vivo data, the difference in thermal recovery rate of the signaling state of the BLUF domain between the wild type and mutated protein was calculated, predicting an about 10-fold faster recovery in the mutant, which is consistent with in vitro data. Introduction of a tyrosine 21 to phenylalanine (Y21F) or to cysteine (Y21C) mutation led to a complete loss of AppA antirepressor activity, while additionally leading to an increase of photosynthesis gene expression after illumination with high blue-light quantities. Interestingly, this effect is not visible in a W104F/Y21F double mutant that again shows a wild-type-like behavior of the BLUF domain after blue-light illumination, thus restoring the activity of AppA.

Screening for Small Molecule Inhibitors of Statin-Induced APP C-terminal Toxic Fragment Production

PubMed Central

Poksay, Karen S.; Sheffler, Douglas J.; Spilman, Patricia; Campagna, Jesus; Jagodzinska, Barbara; Descamps, Olivier; Gorostiza, Olivia; Matalis, Alex; Mullenix, Michael; Bredesen, Dale E.; Cosford, Nicholas D. P.; John, Varghese

2017-01-01

Alzheimer’s disease (AD) is characterized by neuronal and synaptic loss. One process that could contribute to this loss is the intracellular caspase cleavage of the amyloid precursor protein (APP) resulting in release of the toxic C-terminal 31-amino acid peptide APP-C31 along with the production of APPΔC31, full-length APP minus the C-terminal 31 amino acids. We previously found that a mutation in APP that prevents this caspase cleavage ameliorated synaptic loss and cognitive impairment in a murine AD model. Thus, inhibition of this cleavage is a reasonable target for new therapeutic development. In order to identify small molecules that inhibit the generation of APP-C31, we first used an APPΔC31 cleavage site-specific antibody to develop an AlphaLISA to screen several chemical compound libraries for the level of N-terminal fragment production. This antibody was also used to develop an ELISA for validation studies. In both high throughput screening (HTS) and validation testing, the ability of compounds to inhibit simvastatin- (HTS) or cerivastatin- (validation studies) induced caspase cleavage at the APP-D720 cleavage site was determined in Chinese hamster ovary (CHO) cells stably transfected with wildtype (wt) human APP (CHO-7W). Several compounds, as well as control pan-caspase inhibitor Q-VD-OPh, inhibited APPΔC31 production (measured fragment) and rescued cell death in a dose-dependent manner. The effective compounds fell into several classes including SERCA inhibitors, inhibitors of Wnt signaling, and calcium channel antagonists. Further studies are underway to evaluate the efficacy of lead compounds – identified here using cells and tissues expressing wt human APP – in mouse models of AD expressing mutated human APP, as well as to identify additional compounds and determine the mechanisms by which they exert their effects. PMID:28261092

Caspase-9 mediates synaptic plasticity and memory deficits of Danish dementia knock-in mice: caspase-9 inhibition provides therapeutic protection.

PubMed

Tamayev, Robert; Akpan, Nsikan; Arancio, Ottavio; Troy, Carol M; D'Adamio, Luciano

2012-12-10

Mutations in either Aβ Precursor protein (APP) or genes that regulate APP processing, such as BRI2/ITM2B and PSEN1/PSEN2, cause familial dementias. Although dementias due to APP/PSEN1/PSEN2 mutations are classified as familial Alzheimer disease (FAD) and those due to mutations in BRI2/ITM2B as British and Danish dementias (FBD, FDD), data suggest that these diseases have a common pathogenesis involving toxic APP metabolites. It was previously shown that FAD mutations in APP and PSENs promote activation of caspases leading to the hypothesis that aberrant caspase activation could participate in AD pathogenesis. Here, we tested whether a similar mechanism applies to the Danish BRI2/ITM2B mutation. We have generated a genetically congruous mouse model of FDD, called FDD(KI), which presents memory and synaptic plasticity deficits. We found that caspase-9 is activated in hippocampal synaptic fractions of FDD(KI) mice and inhibition of caspase-9 activity rescues both synaptic plasticity and memory deficits. These data directly implicate caspase-9 in the pathogenesis of Danish dementia and suggest that reducing caspase-9 activity is a valid therapeutic approach to treating human dementias.

Caspase-9 mediates synaptic plasticity and memory deficits of Danish dementia knock-in mice: caspase-9 inhibition provides therapeutic protection

PubMed Central

2012-01-01

Background Mutations in either Aβ Precursor protein (APP) or genes that regulate APP processing, such as BRI2/ITM2B and PSEN1/PSEN2, cause familial dementias. Although dementias due to APP/PSEN1/PSEN2 mutations are classified as familial Alzheimer disease (FAD) and those due to mutations in BRI2/ITM2B as British and Danish dementias (FBD, FDD), data suggest that these diseases have a common pathogenesis involving toxic APP metabolites. It was previously shown that FAD mutations in APP and PSENs promote activation of caspases leading to the hypothesis that aberrant caspase activation could participate in AD pathogenesis. Results Here, we tested whether a similar mechanism applies to the Danish BRI2/ITM2B mutation. We have generated a genetically congruous mouse model of FDD, called FDDKI, which presents memory and synaptic plasticity deficits. We found that caspase-9 is activated in hippocampal synaptic fractions of FDDKI mice and inhibition of caspase-9 activity rescues both synaptic plasticity and memory deficits. Conclusion These data directly implicate caspase-9 in the pathogenesis of Danish dementia and suggest that reducing caspase-9 activity is a valid therapeutic approach to treating human dementias. PMID:23217200

Transgenic APP expression during postnatal development causes persistent locomotor hyperactivity in the adult.

PubMed

Rodgers, Shaefali P; Born, Heather A; Das, Pritam; Jankowsky, Joanna L

2012-06-18

Transgenic mice expressing disease-associated proteins have become standard tools for studying human neurological disorders. Transgenes are often expressed using promoters chosen to drive continuous high-level expression throughout life rather than temporal and spatial fidelity to the endogenous gene. This approach has allowed us to recapitulate diseases of aging within the two-year lifespan of the laboratory mouse, but has the potential for creating aberrant phenotypes by mechanisms unrelated to the human disorder. We show that overexpression of the Alzheimer's-related amyloid precursor protein (APP) during early postnatal development leads to severe locomotor hyperactivity that can be significantly attenuated by delaying transgene onset until adulthood. Our data suggest that exposure to transgenic APP during maturation influences the development of neuronal circuits controlling motor activity. Both when matched for total duration of APP overexpression and when matched for cortical amyloid burden, animals exposed to transgenic APP as juveniles are more active in locomotor assays than animals in which APP overexpression was delayed until adulthood. In contrast to motor activity, the age of APP onset had no effect on thigmotaxis in the open field as a rough measure of anxiety, suggesting that the interaction between APP overexpression and brain development is not unilateral. Our findings indicate that locomotor hyperactivity displayed by the tet-off APP transgenic mice and several other transgenic models of Alzheimer's disease may result from overexpression of mutant APP during postnatal brain development. Our results serve as a reminder of the potential for unexpected interactions between foreign transgenes and brain development to cause long-lasting effects on neuronal function in the adult. The tet-off APP model provides an easy means of avoiding developmental confounds by allowing transgene expression to be delayed until the mice reach adulthood.

Amyloid β production is regulated by β2-adrenergic signaling-mediated post-translational modifications of the ryanodine receptor.

PubMed

Bussiere, Renaud; Lacampagne, Alain; Reiken, Steven; Liu, Xiaoping; Scheuerman, Valerie; Zalk, Ran; Martin, Cécile; Checler, Frederic; Marks, Andrew R; Chami, Mounia

2017-06-16

Alteration of ryanodine receptor (RyR)-mediated calcium (Ca 2+ ) signaling has been reported in Alzheimer disease (AD) models. However, the molecular mechanisms underlying altered RyR-mediated intracellular Ca 2+ release in AD remain to be fully elucidated. We report here that RyR2 undergoes post-translational modifications (phosphorylation, oxidation, and nitrosylation) in SH-SY5Y neuroblastoma cells expressing the β-amyloid precursor protein (βAPP) harboring the familial double Swedish mutations (APPswe). RyR2 macromolecular complex remodeling, characterized by depletion of the regulatory protein calstabin2, resulted in increased cytosolic Ca 2+ levels and mitochondrial oxidative stress. We also report a functional interplay between amyloid β (Aβ), β-adrenergic signaling, and altered Ca 2+ signaling via leaky RyR2 channels. Thus, post-translational modifications of RyR occur downstream of Aβ through a β2-adrenergic signaling cascade that activates PKA. RyR2 remodeling in turn enhances βAPP processing. Importantly, pharmacological stabilization of the binding of calstabin2 to RyR2 channels, which prevents Ca 2+ leakage, or blocking the β2-adrenergic signaling cascade reduced βAPP processing and the production of Aβ in APPswe-expressing SH-SY5Y cells. We conclude that targeting RyR-mediated Ca 2+ leakage may be a therapeutic approach to treat AD. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Acute phase proteins in dogs naturally infected with the Giant Kidney Worm (Dioctophyme renale).

PubMed

Schmidt, Elizabeth M S; Kjelgaard-Hansen, Mads; Thomas, Funmilola; Tvarijonaviciute, Asta; Cerón, José J; Eckersall, P David

2016-12-01

Dioctophyme renale is a nematode parasite of dogs, usually found in the right kidney, causing severe damage to the renal parenchyma. The objective was to evaluate the acute phase response in dogs naturally infected with this Giant Kidney Worm and the possible effects of nephrectomy on circulating concentrations of select acute phase proteins (APP) such as serum amyloid A (SAA), C-reactive protein (CRP), and haptoglobin (HP). Nephrectomy was performed in infected dogs and the worms were collected for identification. Blood samples were taken 24 hours before surgery, and 4, 8, and 12 hours postoperatively on the following 10 consecutive days, and 28 days after surgery. Acute phase protein concentrations were determined at all time points. Cortisol concentrations were determined 24 hours before surgery and at recovery (28 days after surgery). One-way ANOVA and Friedman test were used for multiple comparisons; the Wilcoxon-signed rank test was used to compare variables, and Spearman's rho rank test was used to assess the correlation between the number of parasites recovered from the dogs and the APP concentration. Forty-five parasites were recovered from the 12 dogs evaluated in this study. Dogs showed significantly increased HP concentrations (P < .05) but lower CRP and SAA concentrations before surgery, and cortisol concentrations were significantly higher at admission when compared to recovery. No significant correlations were found between the number of parasites and APP concentrations. There is a particular acute phase response profile in dogs with kidney worm infection. Nephrectomy induced a short-term inflammatory process. © 2016 American Society for Veterinary Clinical Pathology.

Positive evolutionary selection of an HD motif on Alzheimer precursor protein orthologues suggests a functional role.

PubMed

Miklós, István; Zádori, Zoltán

2012-02-01

HD amino acid duplex has been found in the active center of many different enzymes. The dyad plays remarkably different roles in their catalytic processes that usually involve metal coordination. An HD motif is positioned directly on the amyloid beta fragment (Aβ) and on the carboxy-terminal region of the extracellular domain (CAED) of the human amyloid precursor protein (APP) and a taxonomically well defined group of APP orthologues (APPOs). In human Aβ HD is part of a presumed, RGD-like integrin-binding motif RHD; however, neither RHD nor RXD demonstrates reasonable conservation in APPOs. The sequences of CAEDs and the position of the HD are not particularly conserved either, yet we show with a novel statistical method using evolutionary modeling that the presence of HD on CAEDs cannot be the result of neutral evolutionary forces (p<0.0001). The motif is positively selected along the evolutionary process in the majority of APPOs, despite the fact that HD motif is underrepresented in the proteomes of all species of the animal kingdom. Position migration can be explained by high probability occurrence of multiple copies of HD on intermediate sequences, from which only one is kept by selective evolutionary forces, in a similar way as in the case of the "transcription binding site turnover." CAED of all APP orthologues and homologues are predicted to bind metal ions including Amyloid-like protein 1 (APLP1) and Amyloid-like protein 2 (APLP2). Our results suggest that HDs on the CAEDs are most probably key components of metal-binding domains, which facilitate and/or regulate inter- or intra-molecular interactions in a metal ion-dependent or metal ion concentration-dependent manner. The involvement of naturally occurring mutations of HD (Tottori (D7N) and English (H6R) mutations) in early onset Alzheimer's disease gives additional support to our finding that HD has an evolutionary preserved function on APPOs.

Positive Evolutionary Selection of an HD Motif on Alzheimer Precursor Protein Orthologues Suggests a Functional Role

PubMed Central

Miklós, István; Zádori, Zoltán

2012-01-01

HD amino acid duplex has been found in the active center of many different enzymes. The dyad plays remarkably different roles in their catalytic processes that usually involve metal coordination. An HD motif is positioned directly on the amyloid beta fragment (Aβ) and on the carboxy-terminal region of the extracellular domain (CAED) of the human amyloid precursor protein (APP) and a taxonomically well defined group of APP orthologues (APPOs). In human Aβ HD is part of a presumed, RGD-like integrin-binding motif RHD; however, neither RHD nor RXD demonstrates reasonable conservation in APPOs. The sequences of CAEDs and the position of the HD are not particularly conserved either, yet we show with a novel statistical method using evolutionary modeling that the presence of HD on CAEDs cannot be the result of neutral evolutionary forces (p<0.0001). The motif is positively selected along the evolutionary process in the majority of APPOs, despite the fact that HD motif is underrepresented in the proteomes of all species of the animal kingdom. Position migration can be explained by high probability occurrence of multiple copies of HD on intermediate sequences, from which only one is kept by selective evolutionary forces, in a similar way as in the case of the “transcription binding site turnover.” CAED of all APP orthologues and homologues are predicted to bind metal ions including Amyloid-like protein 1 (APLP1) and Amyloid-like protein 2 (APLP2). Our results suggest that HDs on the CAEDs are most probably key components of metal-binding domains, which facilitate and/or regulate inter- or intra-molecular interactions in a metal ion-dependent or metal ion concentration-dependent manner. The involvement of naturally occurring mutations of HD (Tottori (D7N) and English (H6R) mutations) in early onset Alzheimer's disease gives additional support to our finding that HD has an evolutionary preserved function on APPOs. PMID:22319430

The Amyloid Precursor Protein (APP) Family Members are Key Players in S-adenosylmethionine Formation by MAT2A and Modify BACE1 and PSEN1 Gene Expression-Relevance for Alzheimer's Disease*

PubMed Central

Schrötter, Andreas; Pfeiffer, Kathy; El Magraoui, Fouzi; Platta, Harald W.; Erdmann, Ralf; Meyer, Helmut E.; Egensperger, Rupert; Marcus, Katrin; Müller, Thorsten

2012-01-01

Central hallmark of Alzheimer's disease are senile plaques mainly composed of β-amyloid, which is a cleavage product of the amyloid precursor protein (APP). The physiological function of APP and its family members APLP1 and APLP2 is poorly understood. In order to fill this gap, we established a cell-culture based model with simultaneous knockdown of all members of the family. A comprehensive proteome study of the APP/APLP1/APLP2 knockdown cell lysates versus controls revealed significant protein abundance changes of more than 30 proteins. Targeted validation of selected candidates by immunoblotting supported the significant down-regulation of the methionine adenosyltransferase II, alpha (MAT2A) as well as of peroxiredoxin 4 in the knockdown cells. Moreover, MAT2A was significantly down-regulated at the mRNA level as well. MAT2A catalyzes the production of S-adenosylmethionine from methionine and ATP, which plays a pivotal role in the methylation of neurotransmitters, DNA, proteins, and lipids. MAT2A-dependent significant up-regulation of S-adenosylmethionine was also detectable in the knockdown cells compared with controls. Our results point to a role of the APP family proteins in cellular methylation mechanisms and fit to findings of disturbed S-adenosylmethionine levels in tissue and CSF of Alzheimer disease patients versus controls. Importantly, methylation plays a central role for neurotransmitter generation like acetylcholine pointing to a crucial relevance of our findings for Alzheimer's disease. In addition, we identified differential gene expression of BACE1 and PSEN1 in the knockdown cells, which is possibly a consequence of MAT2A deregulation and may indicate a self regulatory mechanism. PMID:22879628

Suppression of amyloid beta A11 antibody immunoreactivity by vitamin C: possible role of heparan sulfate oligosaccharides derived from glypican-1 by ascorbate-induced, nitric oxide (NO)-catalyzed degradation.

PubMed

Cheng, Fang; Cappai, Roberto; Ciccotosto, Giuseppe D; Svensson, Gabriel; Multhaup, Gerd; Fransson, Lars-Åke; Mani, Katrin

2011-08-05

Amyloid β (Aβ) is generated from the copper- and heparan sulfate (HS)-binding amyloid precursor protein (APP) by proteolytic processing. APP supports S-nitrosylation of the HS proteoglycan glypican-1 (Gpc-1). In the presence of ascorbate, there is NO-catalyzed release of anhydromannose (anMan)-containing oligosaccharides from Gpc-1-nitrosothiol. We investigated whether these oligosaccharides interact with Aβ during APP processing and plaque formation. anMan immunoreactivity was detected in amyloid plaques of Alzheimer (AD) and APP transgenic (Tg2576) mouse brains by immunofluorescence microscopy. APP/APP degradation products detected by antibodies to the C terminus of APP, but not Aβ oligomers detected by the anti-Aβ A11 antibody, colocalized with anMan immunoreactivity in Tg2576 fibroblasts. A 50-55-kDa anionic, sodium dodecyl sulfate-stable, anMan- and Aβ-immunoreactive species was obtained from Tg2576 fibroblasts using immunoprecipitation with anti-APP (C terminus). anMan-containing HS oligo- and disaccharide preparations modulated or suppressed A11 immunoreactivity and oligomerization of Aβ42 peptide in an in vitro assay. A11 immunoreactivity increased in Tg2576 fibroblasts when Gpc-1 autoprocessing was inhibited by 3-β[2(diethylamino)ethoxy]androst-5-en-17-one (U18666A) and decreased when Gpc-1 autoprocessing was stimulated by ascorbate. Neither overexpression of Gpc-1 in Tg2576 fibroblasts nor addition of copper ion and NO donor to hippocampal slices from 3xTg-AD mice affected A11 immunoreactivity levels. However, A11 immunoreactivity was greatly suppressed by the subsequent addition of ascorbate. We speculate that temporary interaction between the Aβ domain and small, anMan-containing oligosaccharides may preclude formation of toxic Aβ oligomers. A portion of the oligosaccharides are co-secreted with the Aβ peptides and deposited in plaques. These results support the notion that an inadequate supply of vitamin C could contribute to late onset AD in humans.

Trafficking regulation of proteins in Alzheimer’s disease

PubMed Central

2014-01-01

The β-amyloid (Aβ) peptide has been postulated to be a key determinant in the pathogenesis of Alzheimer’s disease (AD). Aβ is produced through sequential cleavage of the β-amyloid precursor protein (APP) by β- and γ-secretases. APP and relevant secretases are transmembrane proteins and traffic through the secretory pathway in a highly regulated fashion. Perturbation of their intracellular trafficking may affect dynamic interactions among these proteins, thus altering Aβ generation and accelerating disease pathogenesis. Herein, we review recent progress elucidating the regulation of intracellular trafficking of these essential protein components in AD. PMID:24410826

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

PubMed Central

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

2002-01-01

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 exposure. Our results indicate that low levels of OP are bioactive and can alter the expression of APLP-2 and APP. Because members of the APP gene family are involved in neuronal development, we hypothesize that OP exposure may disrupt hypothalamic development in young turtles. PMID:11882478

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

PubMed

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 exposure. Our results indicate that low levels of OP are bioactive and can alter the expression of APLP-2 and APP. Because members of the APP gene family are involved in neuronal development, we hypothesize that OP exposure may disrupt hypothalamic development in young turtles.

Mitochondria-targeted catalase reduces abnormal APP processing, amyloid β production and BACE1 in a mouse model of Alzheimer's disease: implications for neuroprotection and lifespan extension.

PubMed

Mao, Peizhong; Manczak, Maria; Calkins, Marcus J; Truong, Quang; Reddy, Tejaswini P; Reddy, Arubala P; Shirendeb, Ulziibat; Lo, Herng-Hsiang; Rabinovitch, Peter S; Reddy, P Hemachandra

2012-07-01

The purpose of this study was to investigate the protective effects of the mitochondria-targeted antioxidant catalase (MCAT) and lifespan extension in mice that express amyloid beta (Aβ). Using immunoblotting and immunostaining analyses, we measured the production of full-length amyloid precursor protein (APP), soluble APPα, C-terminal fragments CTF99 and CTF83, monomeric and oligomeric Aβ, Aβ deposits and beta site amyloid precursor protein cleaving enzyme 1 (BACE1), in different stages of disease progression in MCAT/AβPP and AβPP mice. Using quantitative reverse transcriptase polymerase chain reaction and immunostaining analyses, we studied the expression of catalase, BACE1, the Alzheimer's disease (AD) markers, synaptophysin, APP, neprilysin, insulin-degrading enzyme and transthyretin in MCAT, AβPP, MCAT/AβPP and wild-type (WT) mice. Using the high pressure liquid chromatography analysis of 8-hydroxy-2-deoxyguanosine, we measured oxidative DNA damage in the cerebral cortical tissues from MCAT, AβPP, MCAT/AβPP and WT mice. We found that the AβPP transgenic mice that carried the human MCAT gene lived 5 months longer than did the AβPP mice. We also found that the overexpression of MCAT in the brain sections from the MCAT/AβPP transgenic mice significantly correlated with a reduction in the levels of full-length APP, CTF99, BACE1, Aβ levels (40 and 42), Aβ deposits and oxidative DNA damage relative to the brain sections from the AβPP mice. Interestingly, we found significantly increased levels of soluble APPα and CTF83 in the MCAT/AβPP mice, relative to the AβPP mice. These data provide direct evidence that oxidative stress plays a primary role in AD etiopathology and that in MCAT mice express Aβ, MCAT prevents abnormal APP processing, reduces Aβ levels and enhances Aβ-degrading enzymes in mice at different ages, corresponding to different stages of disease progression. These findings indicate that mitochondria-targeted molecules may be an effective therapeutic approach to treat patients with AD.

Mitochondria-targeted catalase reduces abnormal APP processing, amyloid β production and BACE1 in a mouse model of Alzheimer's disease: implications for neuroprotection and lifespan extension

PubMed Central

Mao, Peizhong; Manczak, Maria; Calkins, Marcus J.; Truong, Quang; Reddy, Tejaswini P.; Reddy, Arubala P.; Shirendeb, Ulziibat; Lo, Herng-Hsiang; Rabinovitch, Peter S.; Reddy, P. Hemachandra

2012-01-01

The purpose of this study was to investigate the protective effects of the mitochondria-targeted antioxidant catalase (MCAT) and lifespan extension in mice that express amyloid beta (Aβ). Using immunoblotting and immunostaining analyses, we measured the production of full-length amyloid precursor protein (APP), soluble APPα, C-terminal fragments CTF99 and CTF83, monomeric and oligomeric Aβ, Aβ deposits and beta site amyloid precursor protein cleaving enzyme 1 (BACE1), in different stages of disease progression in MCAT/AβPP and AβPP mice. Using quantitative reverse transcriptase polymerase chain reaction and immunostaining analyses, we studied the expression of catalase, BACE1, the Alzheimer's disease (AD) markers, synaptophysin, APP, neprilysin, insulin-degrading enzyme and transthyretin in MCAT, AβPP, MCAT/AβPP and wild-type (WT) mice. Using the high pressure liquid chromatography analysis of 8-hydroxy-2-deoxyguanosine, we measured oxidative DNA damage in the cerebral cortical tissues from MCAT, AβPP, MCAT/AβPP and WT mice. We found that the AβPP transgenic mice that carried the human MCAT gene lived 5 months longer than did the AβPP mice. We also found that the overexpression of MCAT in the brain sections from the MCAT/AβPP transgenic mice significantly correlated with a reduction in the levels of full-length APP, CTF99, BACE1, Aβ levels (40 and 42), Aβ deposits and oxidative DNA damage relative to the brain sections from the AβPP mice. Interestingly, we found significantly increased levels of soluble APPα and CTF83 in the MCAT/AβPP mice, relative to the AβPP mice. These data provide direct evidence that oxidative stress plays a primary role in AD etiopathology and that in MCAT mice express Aβ, MCAT prevents abnormal APP processing, reduces Aβ levels and enhances Aβ-degrading enzymes in mice at different ages, corresponding to different stages of disease progression. These findings indicate that mitochondria-targeted molecules may be an effective therapeutic approach to treat patients with AD. PMID:22492996

Structural and functional characterization of cargo-binding sites on the μ4-subunit of adaptor protein complex 4.

PubMed

Ross, Breyan H; Lin, Yimo; Corales, Esteban A; Burgos, Patricia V; Mardones, Gonzalo A

2014-01-01

Adaptor protein (AP) complexes facilitate protein trafficking by playing key roles in the selection of cargo molecules to be sorted in post-Golgi compartments. Four AP complexes (AP-1 to AP-4) contain a medium-sized subunit (μ1-μ4) that recognizes YXXØ-sequences (Ø is a bulky hydrophobic residue), which are sorting signals in transmembrane proteins. A conserved, canonical region in μ subunits mediates recognition of YXXØ-signals by means of a critical aspartic acid. Recently we found that a non-canonical YXXØ-signal on the cytosolic tail of the Alzheimer's disease amyloid precursor protein (APP) binds to a distinct region of the μ4 subunit of the AP-4 complex. In this study we aimed to determine the functionality of both binding sites of μ4 on the recognition of the non-canonical YXXØ-signal of APP. We found that substitutions in either binding site abrogated the interaction with the APP-tail in yeast-two hybrid experiments. Further characterization by isothermal titration calorimetry showed instead loss of binding to the APP signal with only the substitution R283D at the non-canonical site, in contrast to a decrease in binding affinity with the substitution D190A at the canonical site. We solved the crystal structure of the C-terminal domain of the D190A mutant bound to this non-canonical YXXØ-signal. This structure showed no significant difference compared to that of wild-type μ4. Both differential scanning fluorimetry and limited proteolysis analyses demonstrated that the D190A substitution rendered μ4 less stable, suggesting an explanation for its lower binding affinity to the APP signal. Finally, in contrast to overexpression of the D190A mutant, and acting in a dominant-negative manner, overexpression of μ4 with either a F255A or a R283D substitution at the non-canonical site halted APP transport at the Golgi apparatus. Together, our analyses support that the functional recognition of the non-canonical YXXØ-signal of APP is limited to the non-canonical site of μ4.

Structural and Functional Characterization of Cargo-Binding Sites on the μ4-Subunit of Adaptor Protein Complex 4

PubMed Central

Ross, Breyan H.; Lin, Yimo; Corales, Esteban A.; Burgos, Patricia V.; Mardones, Gonzalo A.

2014-01-01

Adaptor protein (AP) complexes facilitate protein trafficking by playing key roles in the selection of cargo molecules to be sorted in post-Golgi compartments. Four AP complexes (AP-1 to AP-4) contain a medium-sized subunit (μ1-μ4) that recognizes YXXØ-sequences (Ø is a bulky hydrophobic residue), which are sorting signals in transmembrane proteins. A conserved, canonical region in μ subunits mediates recognition of YXXØ-signals by means of a critical aspartic acid. Recently we found that a non-canonical YXXØ-signal on the cytosolic tail of the Alzheimer's disease amyloid precursor protein (APP) binds to a distinct region of the μ4 subunit of the AP-4 complex. In this study we aimed to determine the functionality of both binding sites of μ4 on the recognition of the non-canonical YXXØ-signal of APP. We found that substitutions in either binding site abrogated the interaction with the APP-tail in yeast-two hybrid experiments. Further characterization by isothermal titration calorimetry showed instead loss of binding to the APP signal with only the substitution R283D at the non-canonical site, in contrast to a decrease in binding affinity with the substitution D190A at the canonical site. We solved the crystal structure of the C-terminal domain of the D190A mutant bound to this non-canonical YXXØ-signal. This structure showed no significant difference compared to that of wild-type μ4. Both differential scanning fluorimetry and limited proteolysis analyses demonstrated that the D190A substitution rendered μ4 less stable, suggesting an explanation for its lower binding affinity to the APP signal. Finally, in contrast to overexpression of the D190A mutant, and acting in a dominant-negative manner, overexpression of μ4 with either a F255A or a R283D substitution at the non-canonical site halted APP transport at the Golgi apparatus. Together, our analyses support that the functional recognition of the non-canonical YXXØ-signal of APP is limited to the non-canonical site of μ4. PMID:24498434

Reducing expression of synapse-restricting protein Ephexin5 ameliorates Alzheimer’s-like impairment in mice

PubMed Central

Sell, Gabrielle L.; Schaffer, Thomas B.; Margolis, Seth S.

2017-01-01

Accumulation of amyloid-β (Aβ) protein may cause synapse degeneration and cognitive impairment in Alzheimer’s disease (AD) by reactivating expression of the developmental synapse repressor protein Ephexin5 (also known as ARHGEF15). Here, we have reported that Aβ is sufficient to acutely promote the production of Ephexin5 in mature hippocampal neurons and in mice expressing human amyloid precursor protein (hAPP mice), a model for familial AD that produces high brain levels of Aβ. Ephexin5 expression was highly elevated in the hippocampi of human AD patients, indicating its potential relevance to AD. We also observed elevated Ephexin5 expression in the hippocampi of hAPP mice. Removal of Ephexin5 expression eliminated hippocampal dendritic spine loss and rescued AD-associated behavioral deficits in the hAPP mice. Furthermore, selective reduction of Ephexin5 expression using shRNA in the dentate gyrus of presymptomatic adolescent hAPP mice was sufficient to protect these mice from developing cognitive impairment. Thus, pathological elevation of Ephexin5 expression critically drives Aβ-induced memory impairment, and strategies aimed at reducing Ephexin5 levels may represent an effective approach to treating AD. PMID:28346227

Cholesterol-dependent energy transfer between fluorescent proteins-insights into protein proximity of APP and BACE1 in different membranes in Niemann-Pick type C disease cells.

PubMed

von Einem, Bjoern; Weber, Petra; Wagner, Michael; Malnar, Martina; Kosicek, Marko; Hecimovic, Silva; Arnim, Christine A F von; Schneckenburger, Herbert

2012-11-26

Förster resonance energy transfer (FRET) -based techniques have recently been applied to study the interactions between β-site APP-cleaving enzyme-GFP (BACE1-GFP) and amyloid precursor protein-mRFP (APP-mRFP) in U373 glioblastoma cells. In this context, the role of APP-BACE1 proximity in Alzheimer's disease (AD) pathogenesis has been discussed. FRET was found to depend on intracellular cholesterol levels and associated alterations in membrane stiffness. Here, NPC1 null cells (CHO-NPC1-/-), exhibiting increased cholesterol levels and disturbed cholesterol transport similar to that observed in Niemann-Pick type C disease (NPC), were used to analyze the influence of altered cholesterol levels on APP-BACE1 proximity. Fluorescence lifetime measurements of whole CHO-wild type (WT) and CHO-NPC1-/- cells (EPI-illumination microscopy), as well as their plasma membranes (total internal reflection fluorescence microscopy, TIRFM), were performed. Additionally, generalized polarization (GP) measurements of CHO-WT and CHO-NPC1-/- cells incubated with the fluorescence marker laurdan were performed to determine membrane stiffness of plasma- and intracellular-membranes. CHO-NPC1-/- cells showed higher membrane stiffness at intracellular- but not plasma-membranes, equivalent to cholesterol accumulation in late endosomes/lysosomes. Along with higher membrane stiffness, the FRET efficiency between BACE1-GFP and APP-mRFP was reduced at intracellular membranes, but not within the plasma membrane of CHO-NPC1-/-. Our data show that FRET combined with TIRF is a powerful technique to determine protein proximity and membrane fluidity in cellular models of neurodegenerative diseases.

Developing smartphone apps for behavioural studies: The AlcoRisk app case study.

PubMed

Smith, Anthony; de Salas, Kristy; Lewis, Ian; Schüz, Benjamin

2017-08-01

Smartphone apps have emerged as valuable research tools to sample human behaviours at their time of occurrence within natural environments. Human behaviour sampling methods, such as Ecological Momentary Assessment (EMA), aim to facilitate research that is situated in ecologically valid real world environments rather than laboratory environments. Researchers have trialled a range of EMA smartphone apps to sample human behaviours such as dieting, physical activity and smoking. Software development processes for EMA smartphones apps, however, are not widely documented with little guidance provided for the integration of complex multidisciplinary behavioural and technical fields. In this paper, the AlcoRisk app for studying alcohol consumption and risk taking tendencies is presented alongside a software development process that integrates these multidisciplinary fields. The software development process consists of three stages including requirements analysis, feature and interface design followed by app implementation. Results from a preliminary feasibility study support the efficacy of the AlcoRisk app's software development process. Copyright © 2017 Elsevier Inc. All rights reserved.

Smartphones in ecology and evolution: a guide for the app-rehensive.

PubMed

Teacher, Amber G F; Griffiths, David J; Hodgson, David J; Inger, Richard

2013-12-01

Smartphones and their apps (application software) are now used by millions of people worldwide and represent a powerful combination of sensors, information transfer, and computing power that deserves better exploitation by ecological and evolutionary researchers. We outline the development process for research apps, provide contrasting case studies for two new research apps, and scan the research horizon to suggest how apps can contribute to the rapid collection, interpretation, and dissemination of data in ecology and evolutionary biology. We emphasize that the usefulness of an app relies heavily on the development process, recommend that app developers are engaged with the process at the earliest possible stage, and commend efforts to create open-source software scaffolds on which customized apps can be built by nonexperts. We conclude that smartphones and their apps could replace many traditional handheld sensors, calculators, and data storage devices in ecological and evolutionary research. We identify their potential use in the high-throughput collection, analysis, and storage of complex ecological information.

Disrupted-in-Schizophrenia-1 Attenuates Amyloid-β Generation and Cognitive Deficits in APP/PS1 Transgenic Mice by Reduction of β-Site APP-Cleaving Enzyme 1 Levels

PubMed Central

Deng, Qing-Shan; Dong, Xing-Yu; Wu, Hao; Wang, Wang; Wang, Zhao-Tao; Zhu, Jian-Wei; Liu, Chun-Feng; Jia, Wei-Qiang; Zhang, Yan; Schachner, Melitta; Ma, Quan-Hong; Xu, Ru-Xiang

2016-01-01

Disrupted-in-Schizophrenia-1 (DISC1) is a genetic risk factor for a wide range of major mental disorders, including schizophrenia, major depression, and bipolar disorders. Recent reports suggest a potential role of DISC1 in the pathogenesis of Alzheimer's disease (AD), by referring to an interaction between DISC1 and amyloid precursor protein (APP), and to an association of a single-nucleotide polymorphism in a DISC1 intron and late onset of AD. However, the function of DISC1 in AD remains unknown. In this study, decreased levels of DISC1 were observed in the cortex and hippocampus of 8-month-old APP/PS1 transgenic mice, an animal model of AD. Overexpression of DISC1 reduced, whereas knockdown of DISC1 increased protein levels, but not mRNA levels of β-site APP-Cleaving Enzyme 1 (BACE1), a key enzyme in amyloid-β (Aβ) generation. Reduction of BACE1 protein levels by overexpression of DISC1 was accompanied by an accelerating decline rate of BACE1, and was blocked by the lysosomal inhibitor chloroquine, rather than proteasome inhibitor MG-132. Moreover, overexpression of DISC1 in the hippocampus with an adeno-associated virus reduced the levels of BACE1, soluble Aβ40/42, amyloid plaque density, and rescued cognitive deficits of APP/PS1 transgenic mice. These results indicate that DISC1 attenuates Aβ generation and cognitive deficits of APP/PS1 transgenic mice through promoting lysosomal degradation of BACE1. Our findings provide new insights into the role of DISC1 in AD pathogenesis and link a potential function of DISC1 to the psychiatric symptoms of AD. PMID:26062786

The APP-Interacting Protein FE65 is Required for Hippocampus-Dependent Learning and Long-Term Potentiation

ERIC Educational Resources Information Center

Wang, Yan; Zhang, Ming; Moon, Changjong; Hu, Qubai; Wang, Baiping; Martin, George; Sun, Zhongsheng; Wang, Hongbing

2009-01-01

FE65 is expressed predominantly in the brain and interacts with the C-terminal domain of [beta]-amyloid precursor protein (APP). We examined hippocampus-dependent memory and in vivo long-term potentiation (LTP) at the CA1 synapses with isoform-specific FE65 knockout (p97FE65[superscript -/-]) mice. When examined using the Morris water maze,…

Overexpression of Amyloid Precursor Protein Promotes the Onset of Seborrhoeic Keratosis and is Related to Skin Ageing.

PubMed

Li, Yuanying; Wang, Yu; Zhang, Wei; Jiang, Leiwei; Zhou, Wenming; Liu, Zhi; Li, Shijun; Lu, Hongguang

2018-02-28

Seborrhoeic keratosis is an age-related skin disease. Amyloid precursor protein (APP) plays an important role in the pathogenesis of age-related Alzheimer's disease. The aim of this study was to elucidate the expression characteristics of APP in seborrhoeic keratosis tissues (n = 50), and explore whether the production of APP is related to the onset of seborrhoeic keratosis and skin ageing, including ultraviolet (UV)-induced ageing, as observed in normal skin (n = 79). The results of immunohistochemistry, Western blotting and quantitative real-time PCR showed that APP and its downstream products (i.e. amyloid-β42) were more highly expressed in seborrhoeic keratosis than in paired adjacent normal skin tissues. In contrast, the expression of its key secretase (i.e. β-secretase1) was generally low. Furthermore, APP expression was higher in UV-exposed than non-exposed skin sites, and expression in the older age group (61-85 years) was greater than that in the younger age group (41-60 years) in seborrhoeic keratosis tissues (p<0.05). APP expression correlated positively with age in epidermis (p<0.05), but not in dermis. These findings suggest that overexpression of APP may promote the onset of seborrhoeic keratosis and is a marker of skin ageing and UV damage. Further research will elucidate whether therapeutic mitigation of increased levels of APP in the skin might delay the onset of seborrhoeic keratosis and skin ageing.

Activation of PPARδ prevents endothelial dysfunction induced by overexpression of amyloid-β precursor protein

PubMed Central

d'Uscio, Livius V.; Das, Pritam; Santhanam, Anantha V.R.; He, Tongrong; Younkin, Steven G.; Katusic, Zvonimir S.

2012-01-01

Aims Existing evidence suggests that amyloid-β precursor protein (APP) causes endothelial dysfunction and contributes to pathogenesis of atherosclerosis. In the present study, experiments were designed to: (1) determine the mechanisms underlying endothelial dysfunction and (2) define the effects of peroxisome proliferator-activated receptor delta (PPARδ) ligand on endothelial function in transgenic Tg2576 mice overexpressing mutated human APP. Methods and results Confocal microscopy and western blot analyses of wild-type mice aortas provided evidence that APP protein is mainly present in endothelial cells. Overexpression of APP significantly impaired endothelium-dependent relaxations to acetylcholine and phosphorylation of endothelial nitric oxide synthase at Ser1177 in aortas. HPLC analysis revealed that tetrahydrobiopterin (BH4) levels were reduced in Tg2576 mice aortas. This was caused by increased oxidation of BH4 and reduced expression and activity of GTP-cyclohydrolase I. Furthermore, gp91phox protein expression and superoxide anion production were increased in aortas of Tg2576 mice. This augmented superoxide formation was completely prevented by the NADPH oxidase inhibitor VAS2870. Expression of copper-/zinc-superoxide dismutase (Cu/ZnSOD) and extracellular SOD was downregulated. Treatment with PPARδ ligand GW501516 (2 mg/kg/day) for 14 days significantly increased BH4 bioavailability and improved endothelium-dependent relaxations in Tg2576 mice aortas. GW501516 also normalized protein expression of gp91phox and SODs, thereby reducing production of superoxide anion in the aortas. Conclusion Our results suggest that in APP transgenic mice loss of nitric oxide and increased oxidative stress are the major causes of endothelial dysfunction. The vascular protective effects of GW501516 in Tg2576 mice appear to be critically dependent on prevention of superoxide anion production. PMID:22886847

Activation of PPARδ prevents endothelial dysfunction induced by overexpression of amyloid-β precursor protein.

PubMed

d'Uscio, Livius V; Das, Pritam; Santhanam, Anantha V R; He, Tongrong; Younkin, Steven G; Katusic, Zvonimir S

2012-12-01

Existing evidence suggests that amyloid-β precursor protein (APP) causes endothelial dysfunction and contributes to pathogenesis of atherosclerosis. In the present study, experiments were designed to: (1) determine the mechanisms underlying endothelial dysfunction and (2) define the effects of peroxisome proliferator-activated receptor delta (PPARδ) ligand on endothelial function in transgenic Tg2576 mice overexpressing mutated human APP. Confocal microscopy and western blot analyses of wild-type mice aortas provided evidence that APP protein is mainly present in endothelial cells. Overexpression of APP significantly impaired endothelium-dependent relaxations to acetylcholine and phosphorylation of endothelial nitric oxide synthase at Ser(1177) in aortas. HPLC analysis revealed that tetrahydrobiopterin (BH(4)) levels were reduced in Tg2576 mice aortas. This was caused by increased oxidation of BH(4) and reduced expression and activity of GTP-cyclohydrolase I. Furthermore, gp91phox protein expression and superoxide anion production were increased in aortas of Tg2576 mice. This augmented superoxide formation was completely prevented by the NADPH oxidase inhibitor VAS2870. Expression of copper-/zinc-superoxide dismutase (Cu/ZnSOD) and extracellular SOD was downregulated. Treatment with PPARδ ligand GW501516 (2 mg/kg/day) for 14 days significantly increased BH(4) bioavailability and improved endothelium-dependent relaxations in Tg2576 mice aortas. GW501516 also normalized protein expression of gp91(phox) and SODs, thereby reducing production of superoxide anion in the aortas. Our results suggest that in APP transgenic mice loss of nitric oxide and increased oxidative stress are the major causes of endothelial dysfunction. The vascular protective effects of GW501516 in Tg2576 mice appear to be critically dependent on prevention of superoxide anion production.

Similarities in acute phase protein response during hibernation in black bears and major depression in humans: A response to underlying metabolic depression?

USGS Publications Warehouse

Tsiouris, J.A.; Chauhan, V.P.S.; Sheikh, A.M.; Chauhan, A.; Malik, M.; Vaughan, M.R.

2004-01-01

This study investigated the effects of hibernation with mild hypothermia and the stress of captivity on levels of six acute-phase proteins (APPs) in serial samples of serum from 11 wild and 6 captive black bears (Ursus americanus Pallas, 1780) during active and hibernating states. We hypothesize that during hibernation with mild hypothermia, bears would show an APP response similar to that observed in major depression. Enzyme-linked immunoabsorbent assay was used to measure alpha2-macroglobulin and C-reactive protein, and a nephelometer to measure alpha1-antitrypsin, haptoglobin, ceruloplasmin, and transferrin. Levels of all other proteins except ceruloplasmin were significantly elevated during hibernation in both wild and captive bears at the p < 0.05 to p < 0.001 level. Alpha 2-macroglobulin and C-reactive-protein levels were increased in captive versus wild bears in both active and hibernating states at the p < 0.01 to p < 0.0001 level. During hibernation with mild hypothermia, black bears do not show immunosuppression, but show an increased APP response similar to that in patients with major depression. This APP response is explained as an adaptive response to the underlying metabolic depression in both conditions. Metabolic depression in hibernating bears is suggested as a natural model for research to explain the neurobiology of depression.

Two different immunostaining patterns of beta-amyloid precursor protein (APP) may distinguish traumatic from nontraumatic axonal injury.

PubMed

Hayashi, Takahito; Ago, Kazutoshi; Nakamae, Takuma; Higo, Eri; Ogata, Mamoru

2015-09-01

Immunostaining for beta-amyloid precursor protein (APP) is recognized as an effective tool for detecting traumatic axonal injury, but it also detects axonal injury due to ischemic or other metabolic causes. Previously, we reported two different patterns of APP staining: labeled axons oriented along with white matter bundles (pattern 1) and labeled axons scattered irregularly (pattern 2) (Hayashi et al. (Leg Med (Tokyo) 11:S171-173, 2009). In this study, we investigated whether these two patterns are consistent with patterns of trauma and hypoxic brain damage, respectively. Sections of the corpus callosum from 44 cases of blunt head injury and equivalent control tissue were immunostained for APP. APP was detected in injured axons such as axonal bulbs and varicose axons in 24 of the 44 cases of head injuries that also survived for three or more hours after injury. In 21 of the 24 APP-positive cases, pattern 1 alone was observed in 14 cases, pattern 2 alone was not observed in any cases, and both patterns 1 and 2 were detected in 7 cases. APP-labeled injured axons were detected in 3 of the 44 control cases, all of which were pattern 2. These results suggest that pattern 1 indicates traumatic axonal injury, while pattern 2 results from hypoxic insult. These patterns may be useful to differentiate between traumatic and nontraumatic axonal injuries.

Tannic Acid Is a Natural β-Secretase Inhibitor That Prevents Cognitive Impairment and Mitigates Alzheimer-like Pathology in Transgenic Mice*

PubMed Central

Mori, Takashi; Rezai-Zadeh, Kavon; Koyama, Naoki; Arendash, Gary W.; Yamaguchi, Haruyasu; Kakuda, Nobuto; Horikoshi-Sakuraba, Yuko; Tan, Jun; Town, Terrence

2012-01-01

Amyloid precursor protein (APP) proteolysis is essential for production of amyloid-β (Aβ) peptides that form β-amyloid plaques in brains of Alzheimer disease (AD) patients. Recent focus has been directed toward a group of naturally occurring anti-amyloidogenic polyphenols known as flavonoids. We orally administered the flavonoid tannic acid (TA) to the transgenic PSAPP mouse model of cerebral amyloidosis (bearing mutant human APP and presenilin-1 transgenes) and evaluated cognitive function and AD-like pathology. Consumption of TA for 6 months prevented transgene-associated behavioral impairment including hyperactivity, decreased object recognition, and defective spatial reference memory, but did not alter nontransgenic mouse behavior. Accordingly, brain parenchymal and cerebral vascular β-amyloid deposits and abundance of various Aβ species including oligomers were mitigated in TA-treated PSAPP mice. These effects occurred with decreased cleavage of the β-carboxyl-terminal APP fragment, lowered soluble APP-β production, reduced β-site APP cleaving enzyme 1 protein stability and activity, and attenuated neuroinflammation. As in vitro validation, we treated well characterized mutant human APP-overexpressing murine neuron-like cells with TA and found significantly reduced Aβ production associated with less amyloidogenic APP proteolysis. Taken together, these results raise the possibility that dietary supplementation with TA may be prophylactic for AD by inhibiting β-secretase activity and neuroinflammation and thereby mitigating AD pathology. PMID:22219198

ADP-Ribosylation Factor 6 and a Functional PIX/p95-APP1 Complex Are Required for Rac1B-mediated Neurite Outgrowth

PubMed Central

Albertinazzi, Chiara; Za, Lorena; Paris, Simona; de Curtis, Ivan

2003-01-01

The mechanisms coordinating adhesion, actin organization, and membrane traffic during growth cone migration are poorly understood. Neuritogenesis and branching from retinal neurons are regulated by the Rac1B/Rac3 GTPase. We have identified a functional connection between ADP-ribosylation factor (Arf) 6 and p95-APP1 during the regulation of Rac1B-mediated neuritogenesis. P95-APP1 is an ADP-ribosylation factor GTPase-activating protein (ArfGAP) of the GIT family expressed in the developing nervous system. We show that Arf6 has a predominant role in neurite extension compared with Arf1 and Arf5. Cotransfection experiments indicate a specific and cooperative potentiation of neurite extension by Arf6 and the carboxy-terminal portion of p95-APP1. Localization studies in neurons expressing different p95-derived constructs show a codistribution of p95-APP1 with Arf6, but not Arf1. Moreover, p95-APP1–derived proteins with a mutated or deleted ArfGAP domain prevent Rac1B-induced neuritogenesis, leading to PIX-mediated accumulation at large Rab11-positive endocytic vesicles. Our data support a role of p95-APP1 as a specific regulator of Arf6 in the control of membrane trafficking during neuritogenesis. PMID:12686588

RCSB PDB Mobile: iOS and Android mobile apps to provide data access and visualization to the RCSB Protein Data Bank.

PubMed

Quinn, Gregory B; Bi, Chunxiao; Christie, Cole H; Pang, Kyle; Prlić, Andreas; Nakane, Takanori; Zardecki, Christine; Voigt, Maria; Berman, Helen M; Bourne, Philip E; Rose, Peter W

2015-01-01

The Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB PDB) resource provides tools for query, analysis and visualization of the 3D structures in the PDB archive. As the mobile Web is starting to surpass desktop and laptop usage, scientists and educators are beginning to integrate mobile devices into their research and teaching. In response, we have developed the RCSB PDB Mobile app for the iOS and Android mobile platforms to enable fast and convenient access to RCSB PDB data and services. Using the app, users from the general public to expert researchers can quickly search and visualize biomolecules, and add personal annotations via the RCSB PDB's integrated MyPDB service. RCSB PDB Mobile is freely available from the Apple App Store and Google Play (http://www.rcsb.org). © The Author 2014. Published by Oxford University Press.

RCSB PDB Mobile: iOS and Android mobile apps to provide data access and visualization to the RCSB Protein Data Bank

PubMed Central

Quinn, Gregory B.; Bi, Chunxiao; Christie, Cole H.; Pang, Kyle; Prlić, Andreas; Nakane, Takanori; Zardecki, Christine; Voigt, Maria; Berman, Helen M.; Rose, Peter W.

2015-01-01

Summary: The Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB PDB) resource provides tools for query, analysis and visualization of the 3D structures in the PDB archive. As the mobile Web is starting to surpass desktop and laptop usage, scientists and educators are beginning to integrate mobile devices into their research and teaching. In response, we have developed the RCSB PDB Mobile app for the iOS and Android mobile platforms to enable fast and convenient access to RCSB PDB data and services. Using the app, users from the general public to expert researchers can quickly search and visualize biomolecules, and add personal annotations via the RCSB PDB’s integrated MyPDB service. Availability and implementation: RCSB PDB Mobile is freely available from the Apple App Store and Google Play (http://www.rcsb.org). Contact: pwrose@ucsd.edu PMID:25183487

Exposure to As-, Cd-, and Pb-mixture induces Aβ, amyloidogenic APP processing and cognitive impairments via oxidative stress-dependent neuroinflammation in young rats.

PubMed

Ashok, Anushruti; Rai, Nagendra Kumar; Tripathi, Sachin; Bandyopadhyay, Sanghamitra

2015-01-01

Environmental pollutants act as risk factors for Alzheimer's disease (AD), mainly affecting the aging population. We investigated early manifestations of AD-like pathology by a mixture of arsenic (As), cadmium (Cd), and lead (Pb), reported to impair neurodevelopment. We treated rats with As+Cd+Pb at their concentrations detected in groundwater of India, ie, 0.38, 0.098, and 0.22 ppm or 10 times of each, respectively, from gestation-05 to postnatal day-180. We identified dose-dependent increase in amyloid-beta (Aβ) in frontal cortex and hippocampus as early as post-weaning. The effect was strongly significant during early-adulthood, reaching levels comparable to an Aβ-infused AD-like rat model. The metals activated the proamyloidogenic pathway, mediated by increase in amyloid precursor protein (APP), and subsequent beta secretase (BACE) and presenilin (PS)-mediated APP-processing. Investigating the mechanism of Aβ-induction revealed an augmentation in oxidative stress-dependent neuroinflammation that stimulated APP expression through interleukin-responsive-APP-mRNA 5'-untranslated region. We then examined the effects of individual metals and binary mixtures in comparison with the tertiary. Among individual metals, Pb triggered maximum induction of Aβ, whereas individual As or Cd had a relatively non-significant effect on Aβ despite enhanced APP, owing to reduced induction of BACE and PS. Interestingly, when combined the metals demonstrated synergism, with a major contribution by As. The synergistic effect was significant and consistent in tertiary mixture, resulting in the augmentation of Aβ. Eventually, increase in Aβ culminated in cognitive impairments in the young rats. Together, our data demonstrate that exposure to As+Cd+Pb induces premature manifestation of AD-like pathology that is synergistic, and oxidative stress and inflammation dependent. © The Author 2014. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Visualizing APP and BACE-1 approximation in neurons yields insight into the amyloidogenic pathway.

PubMed

Das, Utpal; Wang, Lina; Ganguly, Archan; Saikia, Junmi M; Wagner, Steven L; Koo, Edward H; Roy, Subhojit

2016-01-01

Cleavage of amyloid precursor protein (APP) by BACE-1 (β-site APP cleaving enzyme-1) is the rate-limiting step in amyloid-β (Aβ) production and a neuropathologic hallmark of Alzheimer's disease; thus, physical approximation of this substrate-enzyme pair is a crucial event with broad biological and therapeutic implications. Despite much research, neuronal locales of APP and BACE-1 convergence and APP cleavage remain unclear. Here we report an optical assay, based on fluorescence complementation, for visualizing in cellulo APP-BACE-1 interactions as a simple on/off signal. Combining this with other assays tracking the fate of internalized APP in hippocampal neurons, we found that APP and BACE-1 interacted in both biosynthetic and endocytic compartments, particularly along recycling microdomains such as dendritic spines and presynaptic boutons. In axons, APP and BACE-1 were cotransported, and they also interacted during transit. Finally, our assay revealed that the Alzheimer's disease-protective 'Icelandic' mutation greatly attenuates APP-BACE-1 interactions, suggesting a mechanistic basis for protection. Collectively, the data challenge canonical models and provide concrete insights into long-standing controversies in the field.

DeDaL: Cytoscape 3 app for producing and morphing data-driven and structure-driven network layouts.

PubMed

Czerwinska, Urszula; Calzone, Laurence; Barillot, Emmanuel; Zinovyev, Andrei

2015-08-14

Visualization and analysis of molecular profiling data together with biological networks are able to provide new mechanistic insights into biological functions. Currently, it is possible to visualize high-throughput data on top of pre-defined network layouts, but they are not always adapted to a given data analysis task. A network layout based simultaneously on the network structure and the associated multidimensional data might be advantageous for data visualization and analysis in some cases. We developed a Cytoscape app, which allows constructing biological network layouts based on the data from molecular profiles imported as values of node attributes. DeDaL is a Cytoscape 3 app, which uses linear and non-linear algorithms of dimension reduction to produce data-driven network layouts based on multidimensional data (typically gene expression). DeDaL implements several data pre-processing and layout post-processing steps such as continuous morphing between two arbitrary network layouts and aligning one network layout with respect to another one by rotating and mirroring. The combination of all these functionalities facilitates the creation of insightful network layouts representing both structural network features and correlation patterns in multivariate data. We demonstrate the added value of applying DeDaL in several practical applications, including an example of a large protein-protein interaction network. DeDaL is a convenient tool for applying data dimensionality reduction methods and for designing insightful data displays based on data-driven layouts of biological networks, built within Cytoscape environment. DeDaL is freely available for downloading at http://bioinfo-out.curie.fr/projects/dedal/.

Expression of amyloid-β protein and amyloid-β precursor protein after primary brain-stem injury in rats.

PubMed

Yang, Shudong; Sun, Rongchao; Zhou, Zhiyi; Zhou, Jing; Liang, Jiabei; Mu, Huijun

2014-09-01

Amyloid-β (Aβ) protein and its precursor, amyloid-β precursor protein (β-APP), have traditionally been used in the diagnosis of Alzheimer disease. Their use in diagnosis of traumatic brain injury by forensic analysis is becoming more widespread. However, to date, no reliable small animal model exists to evaluate these brain injury indicators. To address this, we have studied primary brain-stem injury in rats to assess the appearance of diffuse axonal injury in brain sections and correlate these findings with appearance of Aβ and relative β-APP mRNA levels. Using an EnVision 2-step immunohistochemical staining method to measure axon diameter, we found that there was significant difference in axon diameters within the medulla oblongata and several time points after brain injury, ranging from 3 to 24 hours. In addition, mRNA expression levels of β-APP increased following brain injury, peaking 3 hours following injury and decreasing back to baseline levels by 24 hours after injury. These results suggest that using immunohistochemistry and reverse transcription-polymerase chain reaction to detect changes in Aβ-associated axonal changes and β-APP mRNA levels, respectively, can be useful for the diagnosis of diffuse axonal injury during autopsy at early time points following fatal brain injury.

Mutation screening of patients with Alzheimer disease identifies APP locus duplication in a Swedish patient

PubMed Central

2011-01-01

Background Missense mutations in three different genes encoding amyloid-β precursor protein, presenilin 1 and presenilin 2 are recognized to cause familial early-onset Alzheimer disease. Also duplications of the amyloid precursor protein gene have been shown to cause the disease. At the Dept. of Geriatric Medicine, Karolinska University Hospital, Sweden, patients are referred for mutation screening for the identification of nucleotide variations and for determining copy-number of the APP locus. Methods We combined the method of microsatellite marker genotyping with a quantitative real-time PCR analysis to detect duplications in patients with Alzheimer disease. Results In 22 DNA samples from individuals diagnosed with clinical Alzheimer disease, we identified one patient carrying a duplication on chromosome 21 which included the APP locus. Further mapping of the chromosomal region by array-comparative genome hybridization showed that the duplication spanned a maximal region of 1.09 Mb. Conclusions This is the first report of an APP duplication in a Swedish Alzheimer patient and describes the use of quantitative real-time PCR as a tool for determining copy-number of the APP locus. PMID:22044463

Mutation screening of patients with Alzheimer disease identifies APP locus duplication in a Swedish patient.

PubMed

Thonberg, Håkan; Fallström, Marie; Björkström, Jenny; Schoumans, Jacqueline; Nennesmo, Inger; Graff, Caroline

2011-11-01

Missense mutations in three different genes encoding amyloid-β precursor protein, presenilin 1 and presenilin 2 are recognized to cause familial early-onset Alzheimer disease. Also duplications of the amyloid precursor protein gene have been shown to cause the disease. At the Dept. of Geriatric Medicine, Karolinska University Hospital, Sweden, patients are referred for mutation screening for the identification of nucleotide variations and for determining copy-number of the APP locus. We combined the method of microsatellite marker genotyping with a quantitative real-time PCR analysis to detect duplications in patients with Alzheimer disease. In 22 DNA samples from individuals diagnosed with clinical Alzheimer disease, we identified one patient carrying a duplication on chromosome 21 which included the APP locus. Further mapping of the chromosomal region by array-comparative genome hybridization showed that the duplication spanned a maximal region of 1.09 Mb. This is the first report of an APP duplication in a Swedish Alzheimer patient and describes the use of quantitative real-time PCR as a tool for determining copy-number of the APP locus.

Aging process alters hippocampal and cortical secretase activities of Wistar rats.

PubMed

Bertoldi, Karine; Cechinel, Laura Reck; Schallenberger, Bruna; Meireles, Louisiana; Basso, Carla; Lovatel, Gisele Agustini; Bernardi, Lisiane; Lamers, Marcelo Lazzaron; Siqueira, Ionara Rodrigues

2017-01-15

A growing body of evidence has demonstrated amyloid plaques in aged brain; however, little attention has been given to amyloid precursor protein (APP) processing machinery during the healthy aging process. The amyloidogenic and non-amyloidogenic pathways, represented respectively by β- and α-secretases (BACE and TACE), are responsible for APP cleavage. Our working hypothesis is that the normal aging process could imbalance amyloidogenic and non-amyloidogenic pathways specifically BACE and TACE activities. Besides, although it has been showed that exercise can modulate secretase activities in Alzheimer Disease models the relationship between exercise effects and APP processing during healthy aging process is rarely studied. Our aim was to investigate the aging process and the exercise effects on cortical and hippocampal BACE and TACE activities and aversive memory performance. Young adult and aged Wistar rats were subjected to an exercise protocol (20min/day for 2 weeks) and to inhibitory avoidance task. Biochemical parameters were evaluated 1h and 18h after the last exercise session in order to verify transitory and delayed exercise effects. Aged rats exhibited impaired aversive memory and diminished cortical TACE activity. Moreover, an imbalance between TACE and BACE activities in favor of BACE activity was observed in aged brain. Moderate treadmill exercise was unable to alter secretase activities in any brain areas or time points evaluated. Our results suggest that aging-related aversive memory decline is partly linked to decreased cortical TACE activity. Additionally, an imbalance between secretase activities can be related to the higher vulnerability to neurodegenerative diseases induced by aging. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of the acute-phase protein response in pigs to clinical and subclinical infection with H3N2 swine influenza virus.

PubMed

Pomorska-Mól, Małgorzata; Kwit, Krzysztof; Pejsak, Zygmunt; Markowska-Daniel, Iwona

2014-03-01

Swine influenza (SI) is a contagious, important respiratory disease. Diagnosis of SI is based on the clinical signs, confirmed by the detection of viral RNA or specific antibodies. However, the infection is much more frequent than the disease. The aim of study was to investigate the kinetics of acute-phase protein (APP) response during subclinical and clinical influenza in pigs. The utility of APP measurements in identification of infected animals was also evaluated. Twenty-eight piglets were used. C-reactive protein (CRP), haptoglobin (Hp), serum amyloid A (SAA) and pig major acute-phase protein (Pig-MAP) concentrations in serum were measured using commercial ELISAs. No relevant clinical signs were observed in intranasally infected pigs. In contrast, coughing, nasal discharge, and fever were observed in pigs infected intratracheally. All infected pigs exhibited specific antibodies in the serum at 10 dpi, and viral shedding was confirmed. The concentrations of CRP, Hp and SAA were significantly increased after infection. The level of Pig-MAP remained constant during subclinical and clinical infection. The concentrations of CRP, Hp and SAA were higher in pigs with clinical disease. Although not specific, strategic APP measurements may reveal ongoing clinical and subclinical infection. A close relationship between the magnitude of serum APP response with the severity of disease, providing an objective tool for validation the severity of infection. The maximum concentration of SAA in serum was closely correlated with lung score and makes this APP potential indicator for disease progress or estimation of treatment strategy.

Analysis of the acute-phase protein response in pigs to clinical and subclinical infection with H3N2 swine influenza virus

PubMed Central

Pomorska-Mól, Małgorzata; Krzysztof, Kwit; Pejsak, Zygmunt; Markowska-Daniel, Iwona

2014-01-01

Background Swine influenza (SI) is a contagious, important respiratory disease. Diagnosis of SI is based on the clinical signs, confirmed by the detection of viral RNA or specific antibodies. However, the infection is much more frequent than the disease. Objectives The aim of study was to investigate the kinetics of acute-phase protein (APP) response during subclinical and clinical influenza in pigs. The utility of APP measurements in identification of infected animals was also evaluated. Methods Twenty-eight piglets were used. C-reactive protein (CRP), haptoglobin (Hp), serum amyloid A (SAA) and pig major acute-phase protein (Pig-MAP) concentrations in serum were measured using commercial ELISAs. Results and Conclusions No relevant clinical signs were observed in intranasally infected pigs. In contrast, coughing, nasal discharge, and fever were observed in pigs infected intratracheally. All infected pigs exhibited specific antibodies in the serum at 10 dpi, and viral shedding was confirmed. The concentrations of CRP, Hp and SAA were significantly increased after infection. The level of Pig-MAP remained constant during subclinical and clinical infection. The concentrations of CRP, Hp and SAA were higher in pigs with clinical disease. Although not specific, strategic APP measurements may reveal ongoing clinical and subclinical infection. A close relationship between the magnitude of serum APP response with the severity of disease, providing an objective tool for validation the severity of infection. The maximum concentration of SAA in serum was closely correlated with lung score and makes this APP potential indicator for disease progress or estimation of treatment strategy. PMID:24734294

Effects of short-term Western diet on cerebral oxidative stress and diabetes related factors in APP x PS1 knock-in mice.

PubMed

Studzinski, Christa M; Li, Feng; Bruce-Keller, Annadora J; Fernandez-Kim, Sun Ok; Zhang, Le; Weidner, Adam M; Markesbery, William R; Murphy, M Paul; Keller, Jeffrey N

2009-02-01

A chronic high fat Western diet (WD) promotes a variety of morbidity factors although experimental evidence for short-term WD mediating brain dysfunction remains to be elucidated. The amyloid precursor protein and presenilin-1 (APP x PS1) knock-in mouse model has been demonstrated to recapitulate some key features of Alzheimer's disease pathology, including amyloid-beta (Abeta) pathogenesis. In this study, we placed 1-month-old APP x PS1 mice and non-transgenic littermates on a WD for 4 weeks. The WD resulted in a significant elevation in protein oxidation and lipid peroxidation in the brain of APP x PS1 mice relative to non-transgenic littermates, which occurred in the absence of increased Abeta levels. Altered adipokine levels were also observed in APP x PS1 mice placed on a short-term WD, relative to non-transgenic littermates. Taken together, these data indicate that short-term WD is sufficient to selectively promote cerebral oxidative stress and metabolic disturbances in APP x PS1 knock-in mice, with increased oxidative stress preceding alterations in Abeta. These data have important implications for understanding how WD may potentially contribute to brain dysfunction and the development of neurodegenerative disorders such as Alzheimer's disease.

Cilostazol Upregulates Autophagy via SIRT1 Activation: Reducing Amyloid-β Peptide and APP-CTFβ Levels in Neuronal Cells.

PubMed

Lee, Hye Rin; Shin, Hwa Kyoung; Park, So Youn; Kim, Hye Young; Bae, Sun Sik; Lee, Won Suk; Rhim, Byung Yong; Hong, Ki Whan; Kim, Chi Dae

2015-01-01

Autophagy is a vital pathway for the removal of β-amyloid peptide (Aβ) and the aggregated proteins that cause Alzheimer's disease (AD). We previously found that cilostazol induced SIRT1 expression and its activity in neuronal cells, and thus, we hypothesized that cilostazol might stimulate clearances of Aβ and C-terminal APP fragment β subunit (APP-CTFβ) by up-regulating autophagy.When N2a cells were exposed to soluble Aβ1-42, protein levels of beclin-1, autophagy-related protein5 (Atg5), and SIRT1 decreased significantly. Pretreatment with cilostazol (10-30 μM) or resveratrol (20 μM) prevented these Aβ1-42 evoked suppressions. LC3-II (a marker of mammalian autophagy) levels were significantly increased by cilostazol, and this increase was reduced by 3-methyladenine. To evoke endogenous Aβ overproduction, N2aSwe cells (N2a cells stably expressing human APP containing the Swedish mutation) were cultured in medium with or without tetracycline (Tet+ for 48 h and then placed in Tet- condition). Aβ and APP-CTFβ expressions were increased after 12~24 h in Tet- condition, and these increased expressions were significantly reduced by pretreating cilostazol. Cilostazol-induced reductions in the expressions of Aβ and APP-CTFβ were blocked by bafilomycin A1 (a blocker of autophagosome to lysosome fusion). After knockdown of the SIRT1 gene (to ~40% in SIRT1 protein), cilostazol failed to elevate the expressions of beclin-1, Atg5, and LC3-II, indicating that cilostazol increases these expressions by up-regulating SIRT1. Further, decreased cell viability induced by Aβ was prevented by cilostazol, and this inhibition was reversed by 3-methyladenine, indicating that the protective effect of cilostazol against Aβ induced neurotoxicity is, in part, ascribable to the induction of autophagy. In conclusion, cilostazol modulates autophagy by increasing the activation of SIRT1, and thereby enhances Aβ clearance and increases cell viability.

Smartphone apps and the nutrition care process: Current perspectives and future considerations.

PubMed

Chen, Juliana; Gemming, Luke; Hanning, Rhona; Allman-Farinelli, Margaret

2018-04-01

To provide dietitians with practical guidance on incorporating smartphone applications (apps) in the nutrition care process (NCP) to optimize patient education and counseling. The current evidence-base for mobile health (mHealth) apps was searched using PubMed and Google Scholar. Where and how apps could be implemented by dietitians across the four steps of the NCP is discussed. With functionality to automatically convert patient dietary records into nutrient components, nutrition assessment can be streamlined using nutrition apps, allowing more time for dietitians to deliver education and nutrition counseling. Dietitians could prescribe apps to provide patients with education on nutrition skills and in counseling for better adherence to behavior change. Improved patient-provider communication is also made possible through the opportunity for real-time monitoring and evaluation of patient progress via apps. A practical framework termed the 'Mobile Nutrition Care Process Grid' provides dietitians with best-practice guidance on how to use apps. Including apps into dietetic practice could enhance the efficiency and quality of nutrition care and counseling delivered by dietitians. Apps should be considered an adjunct to enable dietetic counseling and care, rather than to replace the expertise, social support and accountability provided by dietitians. Copyright © 2017 Elsevier B.V. All rights reserved.

Phosphorylation of amyloid precursor protein at threonine 668 is essential for its copper-responsive trafficking in SH-SY5Y neuroblastoma cells.

PubMed

Acevedo, Karla M; Opazo, Carlos M; Norrish, David; Challis, Leesa M; Li, Qiao-Xin; White, Anthony R; Bush, Ashley I; Camakaris, James

2014-04-18

Amyloid precursor protein (APP) undergoes post-translational modification, including O- and N-glycosylation, ubiquitination, and phosphorylation as it traffics through the secretory pathway. We have previously reported that copper promotes a change in the cellular localization of APP. We now report that copper increases the phosphorylation of endogenous APP at threonine 668 (Thr-668) in SH-SY5Y neuronal cells. The level of APPT668-p (detected using a phospho-site-specific antibody) exhibited a copper-dependent increase. Using confocal microscopy imaging we demonstrate that the phospho-deficient mutant, Thr-668 to alanine (T668A), does not exhibit detectable copper-responsive APP trafficking. In contrast, mutating a serine to an alanine at residue 655 does not affect copper-responsive trafficking. We further investigated the importance of the Thr-668 residue in copper-responsive trafficking by treating SH-SY5Y cells with inhibitors for glycogen synthase kinase 3-β (GSK3β) and cyclin-dependent kinases (Cdk), the main kinases that phosphorylate APP at Thr-668 in neurons. Our results show that the GSK3β kinase inhibitors LiCl, SB 216763, and SB 415286 prevent copper-responsive APP trafficking. In contrast, the Cdk inhibitors Purvalanol A and B had no significant effect on copper-responsive trafficking in SH-SY5Y cells. In cultured primary hippocampal neurons, copper promoted APP re-localization to the axon, and this effect was inhibited by the addition of LiCl, indicating that a lithium-sensitive kinase(s) is involved in copper-responsive trafficking in hippocampal neurons. This is consistent with APP axonal transport to the synapse, where APP is involved in a number of functions. We conclude that copper promotes APP trafficking by promoting a GSK3β-dependent phosphorylation in SH-SY5Y cells.

Phosphorylation of Amyloid Precursor Protein at Threonine 668 Is Essential for Its Copper-responsive Trafficking in SH-SY5Y Neuroblastoma Cells*

PubMed Central

Acevedo, Karla M.; Opazo, Carlos M.; Norrish, David; Challis, Leesa M.; Li, Qiao-Xin; White, Anthony R.; Bush, Ashley I.; Camakaris, James

2014-01-01

Amyloid precursor protein (APP) undergoes post-translational modification, including O- and N-glycosylation, ubiquitination, and phosphorylation as it traffics through the secretory pathway. We have previously reported that copper promotes a change in the cellular localization of APP. We now report that copper increases the phosphorylation of endogenous APP at threonine 668 (Thr-668) in SH-SY5Y neuronal cells. The level of APPT668-p (detected using a phospho-site-specific antibody) exhibited a copper-dependent increase. Using confocal microscopy imaging we demonstrate that the phospho-deficient mutant, Thr-668 to alanine (T668A), does not exhibit detectable copper-responsive APP trafficking. In contrast, mutating a serine to an alanine at residue 655 does not affect copper-responsive trafficking. We further investigated the importance of the Thr-668 residue in copper-responsive trafficking by treating SH-SY5Y cells with inhibitors for glycogen synthase kinase 3-β (GSK3β) and cyclin-dependent kinases (Cdk), the main kinases that phosphorylate APP at Thr-668 in neurons. Our results show that the GSK3β kinase inhibitors LiCl, SB 216763, and SB 415286 prevent copper-responsive APP trafficking. In contrast, the Cdk inhibitors Purvalanol A and B had no significant effect on copper-responsive trafficking in SH-SY5Y cells. In cultured primary hippocampal neurons, copper promoted APP re-localization to the axon, and this effect was inhibited by the addition of LiCl, indicating that a lithium-sensitive kinase(s) is involved in copper-responsive trafficking in hippocampal neurons. This is consistent with APP axonal transport to the synapse, where APP is involved in a number of functions. We conclude that copper promotes APP trafficking by promoting a GSK3β-dependent phosphorylation in SH-SY5Y cells. PMID:24610780

Visualization of APP and BACE-1 approximation in neurons: new insights into the amyloidogenic pathway

PubMed Central

Das, Utpal; Wang, Lina; Ganguly, Archan; Saikia, Junmi M.; Wagner, Steven L.; Koo, Edward H.; Roy, Subhojit

2016-01-01

Cleavage of APP (amyloid precursor protein) by BACE-1 (β-site APP cleaving enzyme-1) is the rate-limiting step in amyloid-beta (Aβ) production and a neuropathologic hallmark of Alzheimer's disease (AD); thus physical approximation of this substrate-enzyme pair is a critical event with broad biological and therapeutic implications. Despite much research, neuronal locales of APP/BACE-1 convergence and APP-cleavage remain unclear. Here we report an optical assay – based on fluorescence complementation – to visualize in-cellulo APP/BACE-1 interactions as a simple on/off signal. Combined with other assays tracking the fate of internalized APP in hippocampal neurons, we found that APP/BACE-1 interact in both biosynthetic and endocytic compartments; particularly along recycling-microdomains such as dendritic spines and presynaptic boutons. In axons, APP and BACE-1 are co-transported, and also interact during transit. Finally, our assay reveals that the AD-protective “Icelandic” mutation greatly attenuates APP/BACE-1 interactions, suggesting a mechanistic basis for protection. Collectively, the data challenge canonical models and provide concrete insights into long-standing controversies in the field. PMID:26642089

Mobile Phone Apps to Improve Medication Adherence: A Systematic Stepwise Process to Identify High-Quality Apps.

PubMed

Santo, Karla; Richtering, Sarah S; Chalmers, John; Thiagalingam, Aravinda; Chow, Clara K; Redfern, Julie

2016-12-02

There are a growing number of mobile phone apps available to support people in taking their medications and to improve medication adherence. However, little is known about how these apps differ in terms of features, quality, and effectiveness. We aimed to systematically review the medication reminder apps available in the Australian iTunes store and Google Play to assess their features and their quality in order to identify high-quality apps. This review was conducted in a similar manner to a systematic review by using a stepwise approach that included (1) a search strategy; (2) eligibility assessment; (3) app selection process through an initial screening of all retrieved apps and full app review of the included apps; (4) data extraction using a predefined set of features considered important or desirable in medication reminder apps; (5) analysis by classifying the apps as basic and advanced medication reminder apps and scoring and ranking them; and (6) a quality assessment by using the Mobile App Rating Scale (MARS), a reliable tool to assess mobile health apps. We identified 272 medication reminder apps, of which 152 were found only in Google Play, 87 only in iTunes, and 33 in both app stores. Apps found in Google Play had more customer reviews, higher star ratings, and lower cost compared with apps in iTunes. Only 109 apps were available for free and 124 were recently updated in 2015 or 2016. Overall, the median number of features per app was 3.0 (interquartile range 4.0) and only 18 apps had ≥9 of the 17 desirable features. The most common features were flexible scheduling that was present in 56.3% (153/272) of the included apps, medication tracking history in 54.8% (149/272), snooze option in 34.9% (95/272), and visual aids in 32.4% (88/272). We classified 54.8% (149/272) of the included apps as advanced medication reminder apps and 45.2% (123/272) as basic medication reminder apps. The advanced apps had a higher number of features per app compared with the basic apps. Using the MARS instrument, we were able to identify high-quality apps that were rated as being very interesting and entertaining, highly interactive and customizable, intuitive, and easy to use and to navigate as well as having a high level of visual appeal and good-quality information. Many medication reminder apps are available in the app stores; however, the majority of them did not have many of the desirable features and were, therefore, considered low quality. Through a systematic stepwise process, we were able to identify high-quality apps to be tested in a future study that will provide evidence on the use of medication reminder apps to improve medication adherence. ©Karla Santo, Sarah S Richtering, John Chalmers, Aravinda Thiagalingam, Clara K Chow, Julie Redfern. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 02.12.2016.

Mobile Phone Apps to Improve Medication Adherence: A Systematic Stepwise Process to Identify High-Quality Apps

PubMed Central

Richtering, Sarah S; Chalmers, John; Thiagalingam, Aravinda; Chow, Clara K; Redfern, Julie

2016-01-01

Background There are a growing number of mobile phone apps available to support people in taking their medications and to improve medication adherence. However, little is known about how these apps differ in terms of features, quality, and effectiveness. Objective We aimed to systematically review the medication reminder apps available in the Australian iTunes store and Google Play to assess their features and their quality in order to identify high-quality apps. Methods This review was conducted in a similar manner to a systematic review by using a stepwise approach that included (1) a search strategy; (2) eligibility assessment; (3) app selection process through an initial screening of all retrieved apps and full app review of the included apps; (4) data extraction using a predefined set of features considered important or desirable in medication reminder apps; (5) analysis by classifying the apps as basic and advanced medication reminder apps and scoring and ranking them; and (6) a quality assessment by using the Mobile App Rating Scale (MARS), a reliable tool to assess mobile health apps. Results We identified 272 medication reminder apps, of which 152 were found only in Google Play, 87 only in iTunes, and 33 in both app stores. Apps found in Google Play had more customer reviews, higher star ratings, and lower cost compared with apps in iTunes. Only 109 apps were available for free and 124 were recently updated in 2015 or 2016. Overall, the median number of features per app was 3.0 (interquartile range 4.0) and only 18 apps had ≥9 of the 17 desirable features. The most common features were flexible scheduling that was present in 56.3% (153/272) of the included apps, medication tracking history in 54.8% (149/272), snooze option in 34.9% (95/272), and visual aids in 32.4% (88/272). We classified 54.8% (149/272) of the included apps as advanced medication reminder apps and 45.2% (123/272) as basic medication reminder apps. The advanced apps had a higher number of features per app compared with the basic apps. Using the MARS instrument, we were able to identify high-quality apps that were rated as being very interesting and entertaining, highly interactive and customizable, intuitive, and easy to use and to navigate as well as having a high level of visual appeal and good-quality information. Conclusions Many medication reminder apps are available in the app stores; however, the majority of them did not have many of the desirable features and were, therefore, considered low quality. Through a systematic stepwise process, we were able to identify high-quality apps to be tested in a future study that will provide evidence on the use of medication reminder apps to improve medication adherence. PMID:27913373

Isoflurane-Induced Caspase-3 Activation Is Dependent on Cytosolic Calcium and Can Be Attenuated by Memantine

PubMed Central

Zhang, Guohua; Dong, Yuanlin; Zhang, Bin; Ichinose, Fumito; Wu, Xu; Culley, Deborah J.; Crosby, Gregory

2008-01-01

Increasing evidence indicates that caspase activation and apoptosis are associated with a variety of neurodegenerative disorders, including Alzheimer's disease. We reported that anesthetic isoflurane can induce apoptosis, alter processing of the amyloid precursor protein (APP), and increase amyloid-β protein (Aβ) generation. However, the mechanism by which isoflurane induces apoptosis is primarily unknown. We therefore set out to assess effects of extracellular calcium concentration on isoflurane-induced caspase-3 activation in H4 human neuroglioma cells stably transfected to express human full-length APP (H4-APP cells). In addition, we tested effects of RNA interference (RNAi) silencing of IP3 receptor, NMDA receptor, and endoplasmic reticulum (ER) calcium pump, sacro-/ER calcium ATPase (SERCA1). Finally, we examined the effects of the NMDA receptor partial antagonist, memantine, in H4-APP cells and brain tissue of naive mice. EDTA (10 mm), BAPTA (10 μm), and RNAi silencing of IP3 receptor, NMDA receptor, or SERCA1 attenuated capase-3 activation. Memantine (4 μm) inhibited isoflurane-induced elevations in cytosolic calcium levels and attenuated isoflurane-induced caspase-3 activation, apoptosis, and cell viability. Memantine (20 mg/kg, i.p.) reduced isoflurane-induced caspase-3 activation in brain tissue of naive mice. These results suggest that disruption of calcium homeostasis underlies isoflurane-induced caspase activation and apoptosis. We also show for the first time that the NMDA receptor partial antagonist, memantine, can prevent isoflurane-induced caspase-3 activation and apoptosis in vivo and in vitro. These findings, indicating that isoflurane-induced caspase activation and apoptosis are dependent on cytosolic calcium levels, should facilitate the provision of safer anesthesia care, especially for Alzheimer's disease and elderly patients. PMID:18434534

Total flavonoid extract from Dracoephalum moldavica L. attenuates β-amyloid-induced toxicity through anti-amyloidogenesic and neurotrophic pathways.

PubMed

Liu, Qing-Shan; Jiang, Hai-Lun; Wang, Yu; Wang, Lin-Lin; Zhang, Jun-Xia; He, Cheng-Hui; Shao, Shuai; Zhang, Tian-Tai; Xing, Jian-Guo; Liu, Rui

2018-01-15

Alzheimer's disease (AD) is an incurable neurodegenerative disorder characterized by global cognitive impairment that involves accumulation of amyloid-beta peptides (Aβ) in the brain. Herbal approaches can be used as alternative medicines to slow the progression of AD. This study aimed to determine the beneficial effects and potential underlying mechanisms of total flavonoid extract from Dracoephalum moldavica L. (TFDM) for attenuating Alzheimer-related deficits induced by Aβ. We used amyloid precursor protein (APP) and presenilin 1 (PS1) double transgenic mice and copper-injured APP Swedish mutation overexpressing SH-SY5Y cells to evaluate the beneficial effects of TFDM. Further, identifying the mechanisms of action was conducted on anti-amyloidogenic and neurotrophic transductions. Our results indicated that TFDM treatment ameliorated cognitive impairments and neurodegeneration and improved the antioxidant defense system in APP/PS1 mice. TFDM also reduced Aβ burden by relieving Aβ deposition, decreasing insoluble Aβ levels, and inhibiting β-amyloidogenic processing pathway involving downregulation of β-secretase and β-C-terminal fragment in the brain. In the in vitro model of AD, TFDM treatment protected injured cells, and combined with the beneficial effects of decreasing APP levels, lowered Aβ 1-42 and regulated the redox imbalance. Moreover, TFDM preserved the extracellular signal-regulated kinase/cAMP response element-binding protein/brain-derived neurotrophic factor pathway both in vitro and in vivo. In conclusion, TFDM clearly demonstrated neuroprotective effects by restoring the anti-amyloidogenic and neurotrophic transductions in the context of AD-associated deficits. These findings indicate the potential use of herb-based substances as supplements or potential alternative supplements for attenuating the progression of AD. Copyright © 2017. Published by Elsevier Inc.

Guidelines and Recommendations for Developing Interactive eHealth Apps for Complex Messaging in Health Promotion.

PubMed

Heffernan, Kayla Joanne; Chang, Shanton; Maclean, Skye Tamara; Callegari, Emma Teresa; Garland, Suzanne Marie; Reavley, Nicola Jane; Varigos, George Andrew; Wark, John Dennis

2016-02-09

The now ubiquitous catchphrase, "There's an app for that," rings true owing to the growing number of mobile phone apps. In excess of 97,000 eHealth apps are available in major app stores. Yet the effectiveness of these apps varies greatly. While a minority of apps are developed grounded in theory and in conjunction with health care experts, the vast majority are not. This is concerning given the Hippocratic notion of "do no harm." There is currently no unified formal theory for developing interactive eHealth apps, and development is especially difficult when complex messaging is required, such as in health promotion and prevention. This paper aims to provide insight into the creation of interactive eHealth apps for complex messaging, by leveraging the Safe-D case study, which involved complex messaging required to guide safe but sufficient UV exposure for vitamin D synthesis in users. We aim to create recommendations for developing interactive eHealth apps for complex messages based on the lessons learned during Safe-D app development. For this case study we developed an Apple and Android app, both named Safe-D, to safely improve vitamin D status in young women through encouraging safe ultraviolet radiation exposure. The app was developed through participatory action research involving medical and human computer interaction researchers, subject matter expert clinicians, external developers, and target users. The recommendations for development were created from analysis of the development process. By working with clinicians and implementing disparate design examples from the literature, we developed the Safe-D app. From this development process, recommendations for developing interactive eHealth apps for complex messaging were created: (1) involve a multidisciplinary team in the development process, (2) manage complex messages to engage users, and (3) design for interactivity (tailor recommendations, remove barriers to use, design for simplicity). This research has provided principles for developing interactive eHealth apps for complex messaging as guidelines by aggregating existing design concepts and expanding these concepts and new learnings from our development process. A set of guidelines to develop interactive eHealth apps generally, and specifically those for complex messaging, was previously missing from the literature; this research has contributed these principles. Safe-D delivers complex messaging simply, to aid education, and explicitly, considering user safety.

Guidelines and Recommendations for Developing Interactive eHealth Apps for Complex Messaging in Health Promotion

PubMed Central

Heffernan, Kayla Joanne; Maclean, Skye Tamara; Callegari, Emma Teresa; Garland, Suzanne Marie; Reavley, Nicola Jane; Varigos, George Andrew; Wark, John Dennis

2016-01-01

Background The now ubiquitous catchphrase, “There’s an app for that,” rings true owing to the growing number of mobile phone apps. In excess of 97,000 eHealth apps are available in major app stores. Yet the effectiveness of these apps varies greatly. While a minority of apps are developed grounded in theory and in conjunction with health care experts, the vast majority are not. This is concerning given the Hippocratic notion of “do no harm.” There is currently no unified formal theory for developing interactive eHealth apps, and development is especially difficult when complex messaging is required, such as in health promotion and prevention. Objective This paper aims to provide insight into the creation of interactive eHealth apps for complex messaging, by leveraging the Safe-D case study, which involved complex messaging required to guide safe but sufficient UV exposure for vitamin D synthesis in users. We aim to create recommendations for developing interactive eHealth apps for complex messages based on the lessons learned during Safe-D app development. Methods For this case study we developed an Apple and Android app, both named Safe-D, to safely improve vitamin D status in young women through encouraging safe ultraviolet radiation exposure. The app was developed through participatory action research involving medical and human computer interaction researchers, subject matter expert clinicians, external developers, and target users. The recommendations for development were created from analysis of the development process. Results By working with clinicians and implementing disparate design examples from the literature, we developed the Safe-D app. From this development process, recommendations for developing interactive eHealth apps for complex messaging were created: (1) involve a multidisciplinary team in the development process, (2) manage complex messages to engage users, and (3) design for interactivity (tailor recommendations, remove barriers to use, design for simplicity). Conclusions This research has provided principles for developing interactive eHealth apps for complex messaging as guidelines by aggregating existing design concepts and expanding these concepts and new learnings from our development process. A set of guidelines to develop interactive eHealth apps generally, and specifically those for complex messaging, was previously missing from the literature; this research has contributed these principles. Safe-D delivers complex messaging simply, to aid education, and explicitly, considering user safety. PMID:26860623

Proposal for novel curcumin derivatives as potent inhibitors against Alzheimer's disease: Ab initio molecular simulations on the specific interactions between amyloid-beta peptide and curcumin

NASA Astrophysics Data System (ADS)

Ota, Shintaro; Fujimori, Mitsuki; Ishimura, Hiromi; Shulga, Sergiy; Kurita, Noriyuki

2017-10-01

Accumulation of amyloid-β (Aβ) peptides in a brain is closely related with the pathogenesis of Alzheimer's disease. To suppress the production of Aβ peptides, we propose novel curcumin derivatives and investigate their binding properties with the amyloid precursor protein (APP), using protein-ligand docking as well as ab initio molecular simulations. Our proposed derivative (curcumin XIV) is found to have a large binding energy with APP and interacts strongly with the cleavage site Ala19 by secretase. It is thus expected that curcumin XIV can protect APP from the secretase attack and be a potent inhibitor against the production of Aβ peptides.

Reduction of Brain β-Amyloid (Aβ) by Fluvastatin, a Hydroxymethylglutaryl-CoA Reductase Inhibitor, through Increase in Degradation of Amyloid Precursor Protein C-terminal Fragments (APP-CTFs) and Aβ Clearance*

PubMed Central

Shinohara, Mitsuru; Sato, Naoyuki; Kurinami, Hitomi; Takeuchi, Daisuke; Takeda, Shuko; Shimamura, Munehisa; Yamashita, Toshihide; Uchiyama, Yasuo; Rakugi, Hiromi; Morishita, Ryuichi

2010-01-01

Epidemiological studies suggest that statins (hydroxymethylglutaryl-CoA reductase inhibitors) could reduce the risk of Alzheimer disease. Although one possible explanation is through an effect on β-amyloid (Aβ) metabolism, its effect remains to be elucidated. Here, we explored the molecular mechanisms of how statins influence Aβ metabolism. Fluvastatin at clinical doses significantly reduced Aβ and amyloid precursor protein C-terminal fragment (APP-CTF) levels among APP metabolites in the brain of C57BL/6 mice. Chronic intracerebroventricular infusion of lysosomal inhibitors blocked these effects, indicating that up-regulation of the lysosomal degradation of endogenous APP-CTFs is involved in reduced Aβ production. Biochemical analysis suggested that this was mediated by enhanced trafficking of APP-CTFs from endosomes to lysosomes, associated with marked changes of Rab proteins, which regulate endosomal function. In primary neurons, fluvastatin enhanced the degradation of APP-CTFs through an isoprenoid-dependent mechanism. Because our previous study suggests additive effects of fluvastatin on Aβ metabolism, we examined Aβ clearance rates by using the brain efflux index method and found its increased rates at high Aβ levels from brain. As LRP1 in brain microvessels was increased, up-regulation of LRP1-mediated Aβ clearance at the blood-brain barrier might be involved. In cultured brain microvessel endothelial cells, fluvastatin increased LRP1 and the uptake of Aβ, which was blocked by LRP1 antagonists, through an isoprenoid-dependent mechanism. Overall, the present study demonstrated that fluvastatin reduced Aβ level by an isoprenoid-dependent mechanism. These results have important implications for the development of disease-modifying therapy for Alzheimer disease as well as understanding of Aβ metabolism. PMID:20472556

PPARγ agonist pioglitazone improves cerebellar dysfunction at pre-Aβ deposition stage in APPswe/PS1dE9 Alzheimer's disease model mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toba, Junya; Nikkuni, Miyu; Ishizeki, Masato

Alzheimer's disease (AD) is one of the best known neurodegenerative diseases; it causes dementia and its pathological features include accumulation of amyloid β (Aβ) and neurofibrillary tangles (NFTs) in the brain. Elevated Cdk5 activity and CRMP2 phosphorylation have been reported in the brains of AD model mice at the early stage of the disease, but the significance thereof in human AD remains unelucidated. We have recently reported that Aβ accumulation in the cerebellum of AD model APPswe/PS1dE9 (APP/PS1) mice, and cerebellar dysfunctions, such as impairment of motor coordination ability and long-term depression (LTD) induction, at the pre-Aβ accumulation stage. Inmore » the present study, we found increased phosphorylation levels of CRMP2 as well as increased p35 protein levels in the cerebellum of APP/PS1 mice. Interestingly, we show that pioglitazone, an agonist of peroxisome proliferator-activated receptor γ, normalized the p35 protein and CRMP2 phosphorylation levels in the cerebellum. Impaired motor coordination ability and LTD in APP/PS1 mice were ameliorated by pioglitazone treatment at the pre-Aβ accumulation stage. These results suggest a correlation between CRMP2 phosphorylation and AD pathophysiology, and indicate the effectiveness of pioglitazone treatment at the pre-Aβ accumulation stage in AD model mice. -- Highlights: •Phosphorylation level of CRMP2 increased in the cerebellum of APP/PS1 mice. •p35 protein levels increased in the cerebellum of APP/PS1 mice. •Pioglitazone treatment improved cerebellar dysfunction of APP/PS1 mice.« less

A Comprehensive Onboarding and Orientation Plan for Neurocritical Care Advanced Practice Providers.

PubMed

Langley, Tamra M; Dority, Jeremy; Fraser, Justin F; Hatton, Kevin W

2018-06-01

As the role of advanced practice providers (APPs) expands to include increasingly complex patient care within the intensive care unit, the educational needs of these providers must also be expanded. An onboarding process was designed for APPs in the neurocritical care service line. Onboarding for new APPs revolved around 5 specific areas: candidate selection, proctor assignment, 3-phased orientation process, remediation, and mentorship. To ensure effective training for APPs, using the most time-conscious approach, the backbone of the process is a structured curriculum. This was developed and integrated within the standard orientation and onboarding process. The curriculum design incorporated measurable learning goals, objective assessments of phased goal achievements, and opportunities for remediation. The neurocritical care service implemented an onboarding process in 2014. Four APPs (3 nurse practitioners and 1 physician assistant) were employed by the department before the implementation of the orientation program. The length of employment ranged from 1 to 4 years. Lack of clinical knowledge and/or sufficient training was cited as reasons for departure from the position in 2 of the 4 APPs, as either self-expression or peer evaluation. Since implementation of this program, 12 APPs have completed the program, of which 10 remain within the division, creating an 83% retention rate. The onboarding process, including a 3-phased, structured orientation plan for neurocritical care, has increased APP retention since its implementation. The educational model, along with proctoring and mentorship, has improved clinical knowledge and increased nurse practitioner retention. A larger-scale study would help to support the validity of this onboarding process.

Development of a smartphone app for adolescents with lupus: a collaborative meeting-based methodology inclusive of a wide range of stakeholders.

PubMed

Herschman, Jessica; Kasenberg, Todd; Levy, Deborah; Ruth, Natasha; Taberner, Christy; Kaufman, Miriam; Regina, Andrea

2014-01-01

Traditional challenges of creating a medical app include hearing the voices of various stakeholders as a collective rather than in a consultative process that is sequential. This report describes the development of a mobile (smartphone) app for adolescents with lupus as well as the process that was used to overcome the challenge described above. The development of the smartphone app addressed optimal ways to incorporate information about 1) lupus, including the effects of both the disease and the medications used to treat it; 2) how life choices can affect lupus patients' condition; and 3) ways to increase self-management and communication. The collaborative concept-generating and requirements-gathering methodology was used during a two-day workshop with a range of stakeholders (ages 16 - 59 years) that focused on leveraging user-centered design methods to generate guidance to mobile app developers. The app development process conducted during the workshop included the following steps: 1) recruiting a goal-focused collaborative group, 2) defining app objectives, 3) evaluating potential needs of users, 4) brainstorming app features and use-case modeling, 5) reviewing existing app features and prototypes, 6) refining functionalities, 7) writing user narratives, 8) visualizing navigation and feature design, and 9) identifying content. The use of creative devices such as drawing interfaces fostered fun, engagement, and sustained energy, and the use of a brainstorming technique leveraged methods that ensured an inclusive process so that even participants who were shy, quiet, or easily intimidated by "professionals" felt confident to contribute. In addition to a name change for the app, project outcomes included the selection of the following app features: symptom tracking; appointment and medication reminders; a social media component; a medical summary; easy navigation; informational content; gamification; and personalization (options for customization).

Hypoperfusion induces overexpression of beta-amyloid precursor protein mRNA in a focal ischemic rodent model.

PubMed

Shi, J; Yang, S H; Stubley, L; Day, A L; Simpkins, J W

2000-01-17

Silent stroke is one of the risk factors of dementia. In the present study, we used a novel focal ischemic animal model to investigate the effects of comparatively small changes of cerebral blood flow (CBF) on the expression of beta-amyloid precursor protein (APP) mRNA. Focal ischemia was achieved by introducing a 4-0 monofilament to the bifurcation of anterior and middle cerebral arteries. Brain samples were harvested from ischemic core and penumbra of cortices at 1, 4 and 7 days following ischemia. The expression of APP mRNA was assessed by RT-PCR. The CBF was decreased to 50% for 1 day after stroke and recovered to 90% at the fourth day after stroke. The changes of CBF were accompanied by an increase in the expression of APP mRNA. APP mRNA increased to 208% and 152% in the penumbra and core ischemic regions, respectively, on the fourth day after MCAO and remained high through the seventh day of ischemia. This study suggests brain hypoperfusion enhances APP mRNA expression and may contribute to the progression of cognitive impairment after silent stroke.

Interaction of two photoreceptors in the regulation of bacterial photosynthesis genes

PubMed Central

Metz, Sebastian; Haberzettl, Kerstin; Frühwirth, Sebastian; Teich, Kristin; Hasewinkel, Christian; Klug, Gabriele

2012-01-01

The expression of photosynthesis genes in the facultatively photosynthetic bacterium Rhodobacter sphaeroides is controlled by the oxygen tension and by light quantity. Two photoreceptor proteins, AppA and CryB, have been identified in the past, which are involved in this regulation. AppA senses light by its N-terminal BLUF domain, its C-terminal part binds heme and is redox-responsive. Through its interaction to the transcriptional repressor PpsR the AppA photoreceptor controls expression of photosynthesis genes. The cryptochrome-like protein CryB was shown to affect regulation of photosynthesis genes, but the underlying signal chain remained unknown. Here we show that CryB interacts with the C-terminal domain of AppA and modulates the binding of AppA to the transcriptional repressor PpsR in a light-dependent manner. Consequently, binding of the transcription factor PpsR to its DNA target is affected by CryB. In agreement with this, all genes of the PpsR regulon showed altered expression levels in a CryB deletion strain after blue-light illumination. These results elucidate for the first time how a bacterial cryptochrome affects gene expression. PMID:22434878

Interaction of two photoreceptors in the regulation of bacterial photosynthesis genes.

PubMed

Metz, Sebastian; Haberzettl, Kerstin; Frühwirth, Sebastian; Teich, Kristin; Hasewinkel, Christian; Klug, Gabriele

2012-07-01

The expression of photosynthesis genes in the facultatively photosynthetic bacterium Rhodobacter sphaeroides is controlled by the oxygen tension and by light quantity. Two photoreceptor proteins, AppA and CryB, have been identified in the past, which are involved in this regulation. AppA senses light by its N-terminal BLUF domain, its C-terminal part binds heme and is redox-responsive. Through its interaction to the transcriptional repressor PpsR the AppA photoreceptor controls expression of photosynthesis genes. The cryptochrome-like protein CryB was shown to affect regulation of photosynthesis genes, but the underlying signal chain remained unknown. Here we show that CryB interacts with the C-terminal domain of AppA and modulates the binding of AppA to the transcriptional repressor PpsR in a light-dependent manner. Consequently, binding of the transcription factor PpsR to its DNA target is affected by CryB. In agreement with this, all genes of the PpsR regulon showed altered expression levels in a CryB deletion strain after blue-light illumination. These results elucidate for the first time how a bacterial cryptochrome affects gene expression.

Amyloid precursor protein gene isoforms in Alzheimer's disease and other neurodegenerative disorders.

PubMed

Panegyres, P K; Zafiris-Toufexis, K; Kakulas, B A

2000-02-15

Differential expression of the amyloid precursor protein gene (APP) may be important in the development of amyloidosis in Alzheimer's disease (AD) and experimentally in the brain's response to injury. Controversial data suggests that APP isoforms containing the Kunitz protease inhibitor isoform (APP KPI+) are over expressed in the brains of patients with AD when compared to the non-Kunitz protease inhibitor containing isoforms (APP KPI-). We have investigated this hypothesis using a quantitative analysis of gene expression on brain tissue collected at post-mortem. In situ hybridization has been used with synthetic oligonucleotide probes labelled with 35S to detect the two principal splice variants of APP: APP 695 (KPI-) and APP 751 (KPI+). A prospective brain bank of frozen brain specimens has been established and includes pathologically proven AD (n=15) and other neurodegenerative disorders as controls (n=18). The controls consist of frontal lobe atrophy (n=4), Huntington's disease (n=5), Parkinson's disease (n=4), motor neuron disease (n=2), multi-infarct dementia (n=1), multisystem atrophy (n=1), and subacute sclerosing panencephalitis (n=1). We have observed no significant differences in the expression of APP 695 KPI- mRNA in frontal lobe: 17.49+/-3.26 optical density (OD) units of mRNA expression in AD vs. 16.13+/-1.76 OD units mRNA in controls (P=0.80, linear regression); or temporal lobe: 14.73+/-2.96 in AD vs. 16.49+/-2.15 in controls (P=0.55). No significant differences have been found in APP 751 KPI+ in frontal lobe: 12.86+/-2.98 in AD vs. 13.70+/-2.88 in controls (P=0.97); and temporal lobe: 13.31+/-4.93 in AD vs. 11.07+/-1.99 in controls (P=0. 65). Analysis of the ratios of APP 751 KPI+ OD units of mRNA to APP 695 KPI- mRNA revealed a trend to an increased ratio which did not reach statistical significance: frontal lobe APP 751 KPI+/APP 695 KPI- 1.92+/-1.04 in AD vs. 0.86+/-0.17 in controls (P=0.54); temporal lobe 2.54+/-1.59 in AD vs. 0.96+/-0.11 controls (P=0.34). Our data has not revealed differential expression of APP mRNA isoforms in AD and supports the hypothesis that post-translational events in APP metabolism are important in amyloidogenesis and the pathogenesis of AD.

Modeling the complex pathology of Alzheimer’s disease in Drosophila

PubMed Central

Fernandez-Funez, Pedro; de Mena, Lorena; Rincon-Limas, Diego E.

2015-01-01

Alzheimer’s disease (AD) is the leading cause of dementia and the most common neurodegenerative disorder. AD is mostly a sporadic disorder and its main risk factor is age, but mutations in three genes that promote the accumulation of the amyloid-β (Aβ42) peptide revealed the critical role of Amyloid precursor protein (APP) processing in AD. Neurofibrillary tangles enriched in tau are the other pathological hallmark of AD, but the lack of causative tau mutations still puzzles researchers. Here, we describe the contribution of a powerful invertebrate model, the fruit fly Drosophila melanogaster, to uncovering the function and pathogenesis of human APP, Aβ42, and tau. APP and tau participate in many complex cellular processes, although their main function is microtubule stabilization and the to-and-fro transport of axonal vesicles. Additionally, expression of secreted Aβ42 induces prominent neuronal death in Drosophila, a critical feature of AD, making this model a popular choice for identifying intrinsic and extrinsic factors mediating Aβ42 neurotoxicity. Overall, Drosophila has made significant contributions to better understand the complex pathology of AD, although additional insight can be expected from combining multiple transgenes, performing genome-wide loss-of-function screens, and testing anti-tau therapies alone or in combination with Aβ42. PMID:26024860

A ternary AppA-PpsR-DNA complex mediates light regulation of photosynthesis-related gene expression.

PubMed

Winkler, Andreas; Heintz, Udo; Lindner, Robert; Reinstein, Jochen; Shoeman, Robert L; Schlichting, Ilme

2013-07-01

The anoxygenic phototrophic bacterium Rhodobacter sphaeroides uses different energy sources, depending on environmental conditions including aerobic respiration or, in the absence of oxygen, photosynthesis. Photosynthetic genes are repressed at high oxygen tension, but at intermediate levels their partial expression prepares the bacterium for using light energy. Illumination, however, enhances repression under semiaerobic conditions. Here, we describe molecular details of two proteins mediating oxygen and light control of photosynthesis-gene expression: the light-sensing antirepressor AppA and the transcriptional repressor PpsR. Our crystal structures of both proteins and their complex and hydrogen/deuterium-exchange data show that light activation of AppA-PpsR2 affects the PpsR effector region within the complex. DNA binding studies demonstrate the formation of a light-sensitive ternary AppA-PpsR-DNA complex. We discuss implications of these results for regulation by light and oxygen, highlighting new insights into blue light-mediated signal transduction.

''Are Chemistry Educational Apps Useful?''--A Quantitative Study with Three In-House Apps

ERIC Educational Resources Information Center

Ping, Grace Lee Yuan; Lok, Chang; Yeat, Tan Wei; Cherynn, Tan Jie Ying; Tan, Emelyn Sue Qing

2018-01-01

Three internally developed mobile apps, "3D Sym Op", "SM2 Chem" and "ARMolVis," available for free on both the Apple App Store and Google Play Store were evaluated in seven studies. Each study was a systematic process of Pre-Test, In-lecture App Demo, App Assisted Interactive Tutorials (AAITs) and/or Independent App…

Differential proteomic and behavioral effects of long-term voluntary exercise in wild-type and APP-overexpressing transgenics.

PubMed

Rao, Shailaja Kishan; Ross, Jordan M; Harrison, Fiona E; Bernardo, Alexandra; Reiserer, Randall S; Reiserer, Ronald S; Mobley, James A; McDonald, Michael P

2015-06-01

Physical exercise may provide protection against the cognitive decline and neuropathology associated with Alzheimer's disease, although the mechanisms are not clear. In the present study, APP/PSEN1 double-transgenic and wild-type mice were allowed unlimited voluntary exercise for 7months. Consistent with previous reports, wheel-running improved cognition in the double-transgenic mice. Interestingly, the average daily distance run was strongly correlated with spatial memory in the water maze in wild-type mice (r(2)=.959), but uncorrelated in transgenics (r(2)=.013). Proteomics analysis showed that sedentary transgenic mice differed significantly from sedentary wild-types with respect to proteins involved in synaptic transmission, cytoskeletal regulation, and neurogenesis. When given an opportunity to exercise, the transgenics' deficiencies in cytoskeletal regulation and neurogenesis largely normalized, but abnormal synaptic proteins did not change. In contrast, exercise enhanced proteins associated with cytoskeletal regulation, oxidative phosphorylation, and synaptic transmission in wild-type mice. Soluble and insoluble Aβ40 and Aβ42 levels were significantly decreased in both cortex and hippocampus of active transgenics, suggesting that this may have played a role in the cognitive improvement in APP/PSEN1 mice. β-secretase was significantly reduced in active APP/PSEN1 mice compared to sedentary controls, suggesting a mechanism for reduced Aβ. Taken together, these data illustrate that exercise improves memory in wild-type and APP-overexpressing mice in fundamentally different ways. Copyright © 2015 Elsevier Inc. All rights reserved.

Methylene Blue Modulates β-Secretase, Reverses Cerebral Amyloidosis, and Improves Cognition in Transgenic Mice*

PubMed Central

Mori, Takashi; Koyama, Naoki; Segawa, Tatsuya; Maeda, Masahiro; Maruyama, Nobuhiro; Kinoshita, Noriaki; Hou, Huayan; Tan, Jun; Town, Terrence

2014-01-01

Amyloid precursor protein (APP) proteolysis is required for production of amyloid-β (Aβ) peptides that comprise β-amyloid plaques in the brains of patients with Alzheimer disease (AD). Here, we tested whether the experimental agent methylene blue (MB), used for treatment of methemoglobinemia, might improve AD-like pathology and behavioral deficits. We orally administered MB to the aged transgenic PSAPP mouse model of cerebral amyloidosis and evaluated cognitive function and cerebral amyloid pathology. Beginning at 15 months of age, animals were gavaged with MB (3 mg/kg) or vehicle once daily for 3 months. MB treatment significantly prevented transgene-associated behavioral impairment, including hyperactivity, decreased object recognition, and defective spatial working and reference memory, but it did not alter nontransgenic mouse behavior. Moreover, brain parenchymal and cerebral vascular β-amyloid deposits as well as levels of various Aβ species, including oligomers, were mitigated in MB-treated PSAPP mice. These effects occurred with inhibition of amyloidogenic APP proteolysis. Specifically, β-carboxyl-terminal APP fragment and β-site APP cleaving enzyme 1 protein expression and activity were attenuated. Additionally, treatment of Chinese hamster ovary cells overexpressing human wild-type APP with MB significantly decreased Aβ production and amyloidogenic APP proteolysis. These results underscore the potential for oral MB treatment against AD-related cerebral amyloidosis by modulating the amyloidogenic pathway. PMID:25157105

Rescue of Hypovitaminosis A Induces Non-Amyloidogenic Amyloid Precursor Protein (APP) Processing.

PubMed

Reinhardt, Sven; Grimm, Marcus O W; Stahlmann, Christoph; Hartmann, Tobias; Shudo, Koichi; Tomita, Taisuke; Endres, Kristina

2016-01-01

Retinoic acid, the bioactive metabolite of beta-carotene or vitamin A, plays a pleiotropic, multifunctional role in vertebrate development. Studies in rodents revealed that a diet deficient in vitamin A results in a complex neonatal syndrome (the VAD syndrome), manifested in many organs. In humans, the function of retinoic acid (RA) extends into adulthood, where it has important roles in fertility, vision, and suppression of neoplastic growth. In recent years, it has also been suggested that retinoic acid might potentially act as a therapeutically relevant drug in attenuating or even preventing neurodegenerative diseases such as Alzheimer's disease (AD). Here, we report that VAD leads to an increase in A-beta peptide levels while only minor effects were observed on expression levels of the amyloid precursor protein (APP) processing proteinases in wild type mice. In line with these findings, rescue of hypovitaminosis reduced A-beta amount to baseline and induced sApp-alpha secretion in combination with an increase of alpha-secretase Adam10. By comparing retinoic acid treatment starting from a full nutrition status and a "VAD" situation in human neuroblastoma cells, we show that while intensities of differential gene expression were higher in replenished cells, a large overlap in AD-related, regulated genes was observed. Our data suggest that hypovitaminosis A can contribute to onset or progression of AD by increasing synthesis of A-beta peptides and that several AD-related genes such as ADAM10 or BDNF are regulated by retinoic acid. We suggest that dietary supplementation with retinoic acid derivatives is likely to have a beneficial effect on AD-pathology in individuals with hypovitaminosis and patients with normal vitamin A status.

Multiple pathogenic proteins implicated in neuronopathic Gaucher disease mice.

PubMed

Xu, You-hai; Xu, Kui; Sun, Ying; Liou, Benjamin; Quinn, Brian; Li, Rong-hua; Xue, Ling; Zhang, Wujuan; Setchell, Kenneth D R; Witte, David; Grabowski, Gregory A

2014-08-01

Gaucher disease, a prevalent lysosomal storage disease (LSD), is caused by insufficient activity of acid β-glucosidase (GCase) and the resultant glucosylceramide (GC)/glucosylsphingosine (GS) accumulation in visceral organs (Type 1) and the central nervous system (Types 2 and 3). Recent clinical and genetic studies implicate a pathogenic link between Gaucher and neurodegenerative diseases. The aggregation and inclusion bodies of α-synuclein with ubiquitin are present in the brains of Gaucher disease patients and mouse models. Indirect evidence of β-amyloid pathology promoting α-synuclein fibrillation supports these pathogenic proteins as a common feature in neurodegenerative diseases. Here, multiple proteins are implicated in the pathogenesis of chronic neuronopathic Gaucher disease (nGD). Immunohistochemical and biochemical analyses showed significant amounts of β-amyloid and amyloid precursor protein (APP) aggregates in the cortex, hippocampus, stratum and substantia nigra of the nGD mice. APP aggregates were in neuronal cells and colocalized with α-synuclein signals. A majority of APP co-localized with the mitochondrial markers TOM40 and Cox IV; a small portion co-localized with the autophagy proteins, P62/LC3, and the lysosomal marker, LAMP1. In cultured wild-type brain cortical neural cells, the GCase-irreversible inhibitor, conduritol B epoxide (CBE), reproduced the APP/α-synuclein aggregation and the accumulation of GC/GS. Ultrastructural studies showed numerous larger-sized and electron-dense mitochondria in nGD cerebral cortical neural cells. Significant reductions of mitochondrial adenosine triphosphate production and oxygen consumption (28-40%) were detected in nGD brains and in CBE-treated neural cells. These studies implicate defective GCase function and GC/GS accumulation as risk factors for mitochondrial dysfunction and the multi-proteinopathies (α-synuclein-, APP- and Aβ-aggregates) in nGD. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Memory deficiency, cerebral amyloid angiopathy, and amyloid-β plaques in APP+PS1 double transgenic rat model of Alzheimer's disease.

PubMed

Klakotskaia, Diana; Agca, Cansu; Richardson, Rachel A; Stopa, Edward G; Schachtman, Todd R; Agca, Yuksel

2018-01-01

Transgenic rat models of Alzheimer's disease were used to examine differences in memory and brain histology. Double transgenic female rats (APP+PS1) over-expressing human amyloid precursor protein (APP) and presenilin 1 (PS1) and single transgenic rats (APP21) over-expressing human APP were compared with wild type Fischer rats (WT). The Barnes maze assessed learning and memory and showed that both APP21 and APP+PS1 rats made significantly more errors than the WT rats during the acquisition phase, signifying slower learning. Additionally, the APP+PS1 rats made significantly more errors following a retention interval, indicating impaired memory compared to both the APP21 and WT rats. Immunohistochemistry using an antibody against amyloid-β (Aβ) showed extensive and mostly diffuse Aβ plaques in the hippocampus and dense plaques that contained tau in the cortex of the brains of the APP+PS1 rats. Furthermore, the APP+PS1 rats also showed vascular changes, including cerebral amyloid angiopathy with extensive Aβ deposits in cortical and leptomeningeal blood vessel walls and venous collagenosis. In addition to the Aβ accumulation observed in arterial, venous, and capillary walls, APP+PS1 rats also displayed enlarged blood vessels and perivascular space. Overall, the brain histopathology and behavioral assessment showed that the APP+PS1 rats demonstrated behavioral characteristics and vascular changes similar to those commonly observed in patients with Alzheimer's disease.

Describing the Process of Adopting Nutrition and Fitness Apps: Behavior Stage Model Approach

PubMed Central

Sproesser, Gudrun; Schupp, Harald T; Renner, Britta

2018-01-01

Background Although mobile technologies such as smartphone apps are promising means for motivating people to adopt a healthier lifestyle (mHealth apps), previous studies have shown low adoption and continued use rates. Developing the means to address this issue requires further understanding of mHealth app nonusers and adoption processes. This study utilized a stage model approach based on the Precaution Adoption Process Model (PAPM), which proposes that people pass through qualitatively different motivational stages when adopting a behavior. Objective To establish a better understanding of between-stage transitions during app adoption, this study aimed to investigate the adoption process of nutrition and fitness app usage, and the sociodemographic and behavioral characteristics and decision-making style preferences of people at different adoption stages. Methods Participants (N=1236) were recruited onsite within the cohort study Konstanz Life Study. Use of mobile devices and nutrition and fitness apps, 5 behavior adoption stages of using nutrition and fitness apps, preference for intuition and deliberation in eating decision-making (E-PID), healthy eating style, sociodemographic variables, and body mass index (BMI) were assessed. Results Analysis of the 5 behavior adoption stages showed that stage 1 (“unengaged”) was the most prevalent motivational stage for both nutrition and fitness app use, with half of the participants stating that they had never thought about using a nutrition app (52.41%, 533/1017), whereas less than one-third stated they had never thought about using a fitness app (29.25%, 301/1029). “Unengaged” nonusers (stage 1) showed a higher preference for an intuitive decision-making style when making eating decisions, whereas those who were already “acting” (stage 4) showed a greater preference for a deliberative decision-making style (F4,1012=21.83, P<.001). Furthermore, participants differed widely in their readiness to adopt nutrition and fitness apps, ranging from having “decided to” but not yet begun to act (stage 2; nutrition: 6.88%, 70/1017; fitness: 9.23%, 95/1029) to being “disengaged” following previous adoption (stage 5; nutrition: 13.77%, 140/1017; fitness: 15.06%, 155/1029). Conclusions Using a behavior stage model approach to describe the process of adopting nutrition and fitness apps revealed motivational stage differences between nonusers (being “unengaged,” having “decided not to act,” having “decided to act,” and being “disengaged”), which might contribute to a better understanding of the process of adopting mHealth apps and thus inform the future development of digital interventions. This study highlights that new user groups might be better reached by apps designed to address a more intuitive decision-making style. PMID:29535078

Describing the Process of Adopting Nutrition and Fitness Apps: Behavior Stage Model Approach.

PubMed

König, Laura M; Sproesser, Gudrun; Schupp, Harald T; Renner, Britta

2018-03-13

Although mobile technologies such as smartphone apps are promising means for motivating people to adopt a healthier lifestyle (mHealth apps), previous studies have shown low adoption and continued use rates. Developing the means to address this issue requires further understanding of mHealth app nonusers and adoption processes. This study utilized a stage model approach based on the Precaution Adoption Process Model (PAPM), which proposes that people pass through qualitatively different motivational stages when adopting a behavior. To establish a better understanding of between-stage transitions during app adoption, this study aimed to investigate the adoption process of nutrition and fitness app usage, and the sociodemographic and behavioral characteristics and decision-making style preferences of people at different adoption stages. Participants (N=1236) were recruited onsite within the cohort study Konstanz Life Study. Use of mobile devices and nutrition and fitness apps, 5 behavior adoption stages of using nutrition and fitness apps, preference for intuition and deliberation in eating decision-making (E-PID), healthy eating style, sociodemographic variables, and body mass index (BMI) were assessed. Analysis of the 5 behavior adoption stages showed that stage 1 ("unengaged") was the most prevalent motivational stage for both nutrition and fitness app use, with half of the participants stating that they had never thought about using a nutrition app (52.41%, 533/1017), whereas less than one-third stated they had never thought about using a fitness app (29.25%, 301/1029). "Unengaged" nonusers (stage 1) showed a higher preference for an intuitive decision-making style when making eating decisions, whereas those who were already "acting" (stage 4) showed a greater preference for a deliberative decision-making style (F 4,1012 =21.83, P<.001). Furthermore, participants differed widely in their readiness to adopt nutrition and fitness apps, ranging from having "decided to" but not yet begun to act (stage 2; nutrition: 6.88%, 70/1017; fitness: 9.23%, 95/1029) to being "disengaged" following previous adoption (stage 5; nutrition: 13.77%, 140/1017; fitness: 15.06%, 155/1029). Using a behavior stage model approach to describe the process of adopting nutrition and fitness apps revealed motivational stage differences between nonusers (being "unengaged," having "decided not to act," having "decided to act," and being "disengaged"), which might contribute to a better understanding of the process of adopting mHealth apps and thus inform the future development of digital interventions. This study highlights that new user groups might be better reached by apps designed to address a more intuitive decision-making style. ©Laura M König, Gudrun Sproesser, Harald T Schupp, Britta Renner. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 13.03.2018.

Enriched endogenous n-3 polyunsaturated fatty acids alleviate cognitive and behavioral deficits in a mice model of Alzheimer's disease.

PubMed

Wu, Kefeng; Gao, Xiang; Shi, Baoyan; Chen, Shiyu; Zhou, Xin; Li, Zhidong; Gan, Yuhong; Cui, Liao; Kang, Jing Xuan; Li, Wende; Huang, Ren

2016-10-01

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that accompanied by memory deficits and neuropsychiatric dysfunction. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have seemly therapeutic potential in AD, but the benefit of n-3 PUFAs is still in debates. Here, we employed a transgenic mice carry fat-1 gene to encode n-3 desaturase from Caenorhabditis elegans, which increase endogenous n-3 PUFAs by converting n-6 PUFAs to n-3 PUFAs crossed with amyloid precursor protein (APP) Tg mice to evaluate the protective effects of endogenous n-3 PUFAs on cognitive and behavioral deficits of APP Tg mice. We fed APP, APP/fat-1 and fat-1 mice with n-6 PUFAs rich diet. Brain tissues were collected at 3, 9 and 12 months for fatty acid and gene expression analysis, histology and protein assays. Morris Water Maze Test, open field test and elevated plus maze test were performed to measure the behavior capability. From the results, the expression of fat-1 transgene increased cortical n-3: n-6 PUFAs ratio and n-3 PUFAs concentrations, and sensorimotor dysfunction and cognitive deficits in AD were significantly less severe in APP/fat-1 mice with endogenous n-3 PUFAs than in APP mice controls. The protection against disturbance of spontaneous motor activity and cognitive deficits in AD was strongly correlated with increased n-3: n-6 PUFAs ratio and endogenous n-3 PUFAs, reduced APP generation, inhibited amyloid β peptide aggregation, suppressed nuclear factor-kappa B and astroglia activation, and reduced death of neurons in the cortex of APP/fat-1 mice compared with APP mice controls. In conclusion, our study demonstrates that an available medication with the maintenance of enriched n-3 PUFAs in the brain could slow down cognitive decline and prevent neuropsychological disorder in AD. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

RCSB PDB Mobile: iOS and Android mobile apps to provide data access and visualization to the RCSB Protein Data Bank

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quinn, Gregory B.; Bi, Chunxiao; Christie, Cole H.

The Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB PDB) resource provides tools for query, analysis and visualization of the 3D structures in the PDB archive. As the mobile Web is starting to surpass desktop and laptop usage, scientists and educators are beginning to integrate mobile devices into their research and teaching. In response, we have developed the RCSB PDB Mobile app for the iOS and Android mobile platforms to enable fast and convenient access to RCSB PDB data and services. Lastly, using the app, users from the general public to expert researchers can quickly search and visualize biomolecules,more » and add personal annotations via the RCSB PDB's integrated MyPDB service.« less

RCSB PDB Mobile: iOS and Android mobile apps to provide data access and visualization to the RCSB Protein Data Bank

DOE PAGES

Quinn, Gregory B.; Bi, Chunxiao; Christie, Cole H.; ...

2014-09-02

The Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB PDB) resource provides tools for query, analysis and visualization of the 3D structures in the PDB archive. As the mobile Web is starting to surpass desktop and laptop usage, scientists and educators are beginning to integrate mobile devices into their research and teaching. In response, we have developed the RCSB PDB Mobile app for the iOS and Android mobile platforms to enable fast and convenient access to RCSB PDB data and services. Lastly, using the app, users from the general public to expert researchers can quickly search and visualize biomolecules,more » and add personal annotations via the RCSB PDB's integrated MyPDB service.« less

Neurobehavioral characterization of APP23 transgenic mice with the SHIRPA primary screen.

PubMed

Lalonde, R; Dumont, M; Staufenbiel, M; Strazielle, C

2005-02-10

The SHIRPA primary screen comprises 40 measures covering various reflexes and basic sensorimotor functions. This multi-test battery was used to compare non-transgenic controls with APP23 transgenic mice, expressing the 751 isoform of human beta-amyloid precursor protein and characterized by amyloid deposits in parenchyma and vessel walls. The APP23 mice were distinguishable from controls by pathological limb reflexes, myoclonic jumping, seizure activity, and tail malformation. In addition, this mouse model of Alzheimer's disease was also marked by a crooked swimming trajectory. APP23 mice were also of lighter weight and were less inclined to stay immobile during a transfer arousal test. Despite the neurologic signs, APP23 transgenic mice were not deficient in stationary beam, coat-hanger, and rotorod tests, indicating intact motor coordination abilities.

Cloning and Expression of Phytase appA Gene from Shigella sp. CD2 in Pichia pastoris and Comparison of Properties with Recombinant Enzyme Expressed in E. coli

PubMed Central

Pal Roy, Moushree; Mazumdar, Deepika; Dutta, Subhabrata; Saha, Shyama Prasad; Ghosh, Shilpi

2016-01-01

The phytase gene appAS was isolated from Shigella sp. CD2 genomic library. The 3.8 kb DNA fragment contained 1299 bp open reading frame encoding 432 amino acid protein (AppAS) with 22 amino acid signal peptide at N-terminal and three sites of N-glycosylation. AppAS contained the active site RHGXRXP and HDTN sequence motifs, which are conserved among histidine acid phosphatases. It showed maximum identity with phytase AppA of Escherichia coli and Citrobacter braakii. The appAS was expressed in Pichia pastoris and E. coli to produce recombinant phytase rAppAP and rAppAE, respectively. Purified glycosylated rAppAP and nonglycosylated rAppAE had specific activity of 967 and 2982 U mg-1, respectively. Both had pH optima of 5.5 and temperature optima of 60°C. Compared with rAppAE, rAppAP was 13 and 17% less active at pH 3.5 and 7.5 and 11 and 18% less active at temperature 37 and 50°C, respectively; however, it was more active at higher incubation temperatures. Thermotolerance of rAppAP was 33% greater at 60°C and 24% greater at 70°C, when compared with rAppAE. Both the recombinant enzymes showed high specificity to phytate and resistance to trypsin. To our knowledge, this is the first report on cloning and expression of phytase from Shigella sp. PMID:26808559

Cloning and Expression of Phytase appA Gene from Shigella sp. CD2 in Pichia pastoris and Comparison of Properties with Recombinant Enzyme Expressed in E. coli.

PubMed

Pal Roy, Moushree; Mazumdar, Deepika; Dutta, Subhabrata; Saha, Shyama Prasad; Ghosh, Shilpi

2016-01-01

The phytase gene appAS was isolated from Shigella sp. CD2 genomic library. The 3.8 kb DNA fragment contained 1299 bp open reading frame encoding 432 amino acid protein (AppAS) with 22 amino acid signal peptide at N-terminal and three sites of N-glycosylation. AppAS contained the active site RHGXRXP and HDTN sequence motifs, which are conserved among histidine acid phosphatases. It showed maximum identity with phytase AppA of Escherichia coli and Citrobacter braakii. The appAS was expressed in Pichia pastoris and E. coli to produce recombinant phytase rAppAP and rAppAE, respectively. Purified glycosylated rAppAP and nonglycosylated rAppAE had specific activity of 967 and 2982 U mg(-1), respectively. Both had pH optima of 5.5 and temperature optima of 60°C. Compared with rAppAE, rAppAP was 13 and 17% less active at pH 3.5 and 7.5 and 11 and 18% less active at temperature 37 and 50°C, respectively; however, it was more active at higher incubation temperatures. Thermotolerance of rAppAP was 33% greater at 60°C and 24% greater at 70°C, when compared with rAppAE. Both the recombinant enzymes showed high specificity to phytate and resistance to trypsin. To our knowledge, this is the first report on cloning and expression of phytase from Shigella sp.

Building a Mobile HIV Prevention App for Men Who Have Sex With Men: An Iterative and Community-Driven Process

PubMed Central

McDougal, Sarah J; Sullivan, Patrick S; Stekler, Joanne D; Stephenson, Rob

2015-01-01

Background Gay, bisexual, and other men who have sex with men (MSM) account for a disproportionate burden of new HIV infections in the United States. Mobile technology presents an opportunity for innovative interventions for HIV prevention. Some HIV prevention apps currently exist; however, it is challenging to encourage users to download these apps and use them regularly. An iterative research process that centers on the community’s needs and preferences may increase the uptake, adherence, and ultimate effectiveness of mobile apps for HIV prevention. Objective The aim of this paper is to provide a case study to illustrate how an iterative community approach to a mobile HIV prevention app can lead to changes in app content to appropriately address the needs and the desires of the target community. Methods In this three-phase study, we conducted focus group discussions (FGDs) with MSM and HIV testing counselors in Atlanta, Seattle, and US rural regions to learn preferences for building a mobile HIV prevention app. We used data from these groups to build a beta version of the app and theater tested it in additional FGDs. A thematic data analysis examined how this approach addressed preferences and concerns expressed by the participants. Results There was an increased willingness to use the app during theater testing than during the first phase of FGDs. Many concerns that were identified in phase one (eg, disagreements about reminders for HIV testing, concerns about app privacy) were considered in building the beta version. Participants perceived these features as strengths during theater testing. However, some disagreements were still present, especially regarding the tone and language of the app. Conclusions These findings highlight the benefits of using an interactive and community-driven process to collect data on app preferences when building a mobile HIV prevention app. Through this process, we learned how to be inclusive of the larger MSM population without marginalizing some app users. Though some issues in phase one were able to be addressed, disagreements still occurred in theater testing. If the app is going to address a large and diverse risk group, we cannot include niche functionality that may offend some of the target population. PMID:27227136

Mobile Apps for Teaching Intubation: Scoping Review and Critical Analysis in eLearning

PubMed Central

2017-01-01

Background Airway management is a core skill in anesthesia ensuring adequate oxygenation and delivery of inhalational agents for the patient. Objective The goals of this study were to critically evaluate the quality of airway management apps and target revised Bloom's Taxonomy cognitive levels. Methods An electronic search using the keywords “airway” and “airway management” was conducted in May 2015 across the App Store, Google Play, BlackBerry World, and Windows Store. Apps were included in the study if their content was related to airway management. App content and characteristics were extracted into a standard form and evaluated. Results A total of 65 apps met the inclusion criteria, and 73% (47/65) of apps were developed by companies or industry. Anesthesiology trainees were the target audience in only 20% (13/65) of apps. Bag mask ventilation and laryngeal mask airways were covered in only 20% (13/65) of apps. Only 2 apps were supported in the scientific literature. For Bloom’s Taxonomy, 37% (24/65) of apps targeted knowledge, 5% (3/65) comprehension, 22% (14/65) application, 28% (18/65) analysis, 9% (6/65) evaluation, and 0% synthesis. Multivariate analysis identified cost of apps, size of apps (MB), and apps targeting trainees and paramedics to be associated with higher levels of cognitive processing of revised Bloom’s Taxonomy. Conclusions Apps developed for teaching intubation target lower levels of cognitive processing and are largely not validated by research. Cost, app size, and targeted user are associated with higher cognitive levels. Trainees and all users should be aware of the paucity of the published evidence behind the efficacy of some of these apps. PMID:28874335

Mobile Apps for Teaching Intubation: Scoping Review and Critical Analysis in eLearning.

PubMed

Matava, Clyde; Leo, Anne-Marie; Alam, Fahad

2017-09-05

Airway management is a core skill in anesthesia ensuring adequate oxygenation and delivery of inhalational agents for the patient. The goals of this study were to critically evaluate the quality of airway management apps and target revised Bloom's Taxonomy cognitive levels. An electronic search using the keywords "airway" and "airway management" was conducted in May 2015 across the App Store, Google Play, BlackBerry World, and Windows Store. Apps were included in the study if their content was related to airway management. App content and characteristics were extracted into a standard form and evaluated. A total of 65 apps met the inclusion criteria, and 73% (47/65) of apps were developed by companies or industry. Anesthesiology trainees were the target audience in only 20% (13/65) of apps. Bag mask ventilation and laryngeal mask airways were covered in only 20% (13/65) of apps. Only 2 apps were supported in the scientific literature. For Bloom's Taxonomy, 37% (24/65) of apps targeted knowledge, 5% (3/65) comprehension, 22% (14/65) application, 28% (18/65) analysis, 9% (6/65) evaluation, and 0% synthesis. Multivariate analysis identified cost of apps, size of apps (MB), and apps targeting trainees and paramedics to be associated with higher levels of cognitive processing of revised Bloom's Taxonomy. Apps developed for teaching intubation target lower levels of cognitive processing and are largely not validated by research. Cost, app size, and targeted user are associated with higher cognitive levels. Trainees and all users should be aware of the paucity of the published evidence behind the efficacy of some of these apps. ©Clyde Matava, Anne-Marie Leo, Fahad Alam. Originally published in JMIR Medical Education (http://mededu.jmir.org), 05.09.2017.

Epic Allies: Development of a Gaming App to Improve Antiretroviral Therapy Adherence Among Young HIV-Positive Men Who Have Sex With Men.

PubMed

LeGrand, Sara; Muessig, Kathryn Elizabeth; McNulty, Tobias; Soni, Karina; Knudtson, Kelly; Lemann, Alex; Nwoko, Nkechinyere; Hightow-Weidman, Lisa B

2016-05-13

In the United States, the human immunodeficiency virus (HIV) disproportionately affects young men who have sex with men (YMSM). For HIV-positive individuals, adherence to antiretroviral therapy (ART) is critical for achieving optimal health outcomes and reducing secondary transmission of HIV. However, YMSM often struggle with ART adherence. Novel mobile phone apps that incorporate game-based mechanics and social networking elements represent a promising intervention approach for improving ART adherence among YMSM. This study used a multiphase, iterative development process to create an ART adherence app for YMSM. The three-phase development process included: (1) theory-based concept development jointly by public health researchers and the technology team, (2) assessment of the target population's ART adherence needs and app preferences and development and testing of a clickable app prototype, and (3) development and usability testing of the final app prototype. The initial theory-based app concept developed in Phase One included medication reminders, daily ART adherence tracking and visualization, ART educational modules, limited virtual interactions with other app users, and gamification elements. In Phase Two, adherence needs, including those related to information, motivation, and behavioral skills, were identified. Participants expressed preferences for an ART adherence app that was informational, interactive, social, and customizable. Based on the findings from Phase Two, additional gaming features were added in Phase Three, including an interactive battle, superhero app theme, and app storyline. Other features were modified to increase interactivity and customization options and integrate the game theme. During usability testing of the final prototype, participants were able to understand and navigate the app successfully and rated the app favorably. An iterative development process was critical for the development of an ART adherence game app that was viewed as highly acceptable, relevant, and useful by YMSM.

Epic Allies: Development of a Gaming App to Improve Antiretroviral Therapy Adherence Among Young HIV-Positive Men Who Have Sex With Men

PubMed Central

Muessig, Kathryn Elizabeth; McNulty, Tobias; Soni, Karina; Knudtson, Kelly; Lemann, Alex; Nwoko, Nkechinyere; Hightow-Weidman, Lisa B

2016-01-01

Background In the United States, the human immunodeficiency virus (HIV) disproportionately affects young men who have sex with men (YMSM). For HIV-positive individuals, adherence to antiretroviral therapy (ART) is critical for achieving optimal health outcomes and reducing secondary transmission of HIV. However, YMSM often struggle with ART adherence. Novel mobile phone apps that incorporate game-based mechanics and social networking elements represent a promising intervention approach for improving ART adherence among YMSM. Objective This study used a multiphase, iterative development process to create an ART adherence app for YMSM. Methods The three-phase development process included: (1) theory-based concept development jointly by public health researchers and the technology team, (2) assessment of the target population’s ART adherence needs and app preferences and development and testing of a clickable app prototype, and (3) development and usability testing of the final app prototype. Results The initial theory-based app concept developed in Phase One included medication reminders, daily ART adherence tracking and visualization, ART educational modules, limited virtual interactions with other app users, and gamification elements. In Phase Two, adherence needs, including those related to information, motivation, and behavioral skills, were identified. Participants expressed preferences for an ART adherence app that was informational, interactive, social, and customizable. Based on the findings from Phase Two, additional gaming features were added in Phase Three, including an interactive battle, superhero app theme, and app storyline. Other features were modified to increase interactivity and customization options and integrate the game theme. During usability testing of the final prototype, participants were able to understand and navigate the app successfully and rated the app favorably. Conclusions An iterative development process was critical for the development of an ART adherence game app that was viewed as highly acceptable, relevant, and useful by YMSM. PMID:27178752

Docosahexaenoic Acid and the Aging Brain1–3

PubMed Central

Lukiw, Walter J.; Bazan, Nicolas G.

2008-01-01

The dietary essential PUFA docosahexaenoic acid [DHA; 22:6(n-3)] is a critical contributor to cell structure and function in the nervous system, and deficits in DHA abundance are associated with cognitive decline during aging and in neurodegenerative disease. Recent studies underscore the importance of DHA-derived neuroprotectin D1 (NPD1) in the homeostatic regulation of brain cell survival and repair involving neurotrophic, antiapoptotic and antiinflammatory signaling. Emerging evidence suggests that NPD1 synthesis is activated by growth factors and neurotrophins. Evolving research indicates that NPD1 has important determinant and regulatory interactions with the molecular-genetic mechanisms affecting β-amyloid precursor protein (βAPP) and amyloid beta (Aβ) peptide neurobiology. Deficits in DHA or its peroxidation appear to contribute to inflammatory signaling, apoptosis, and neuronal dysfunction in Alzheimer disease (AD), a common and progressive age-related neurological disorder unique to structures and processes of the human brain. This article briefly reviews our current understanding of the interactions of DHA and NPD1 on βAPP processing and Aβ peptide signaling and how this contributes to oxidative and pathogenic processes characteristic of aging and AD pathology. PMID:19022980

BRI2 (ITM2b) Inhibits Aβ Deposition in Vivo

PubMed Central

Kim, Jungsu; Miller, Victor M.; Levites, Yona; West, Karen Jansen; Zwizinski, Craig W.; Moore, Brenda D.; Troendle, Fredrick J.; Bann, Maralyssa; Verbeeck, Christophe; Price, Robert W.; Smithson, Lisa; Sonoda, Leilani; Wagg, Kayleigh; Rangachari, Vijayaraghavan; Zou, Fanggeng; Younkin, Steven G.; Graff-Radford, Neill; Dickson, Dennis; Rosenberry, Terrone; Golde, Todd E.

2008-01-01

Analyses of the biologic effects of mutations in the BRI2 (ITM2b) and the amyloid β precursor protein (APP) genes support the hypothesis that cerebral accumulation of amyloidogenic peptides in familial British and familial Danish dementias and Alzheimer’s disease (AD) is associated with neurodegeneration. We have used somatic brain transgenic technology to express the BRI2 and BRI2-Aβ1-40 transgenes in amyloid β protein precursor (APP) mouse models. Expression of BRI2-Aβ1-40 mimics the suppressive effect previously observed using conventional transgenic methods, further validating the somatic brain transgenic methodology. Unexpectedly, we also find that expression of wild type human BRI2 reduces cerebral Aβ deposition in an AD mouse model. Additional data indicate that the 23 amino acid peptide, Bri23, released from BRI2 by normal processing is present in human cerebrospinal fluid (CSF), inhibits Aβ aggregation in vitro, and mediates its anti-amyloidogenic effect in vivo. These studies demonstrate that BRI2 is a novel mediator of Aβ deposition in vivo. PMID:18524908

Impairments of long-term depression induction and motor coordination precede Aβ accumulation in the cerebellum of APPswe/PS1dE9 double transgenic mice.

PubMed

Kuwabara, Yuki; Ishizeki, Masato; Watamura, Naoto; Toba, Junya; Yoshii, Aya; Inoue, Takafumi; Ohshima, Toshio

2014-08-01

Alzheimer's disease (AD) is a neurodegenerative disorder that represents the most common type of dementia among elderly people. Amyloid beta (Aβ) peptides in extracellular Aβ plaques, produced from the amyloid precursor protein (APP) via sequential processing by β- and γ-secretases, impair hippocampal synaptic plasticity, and cause cognitive dysfunction in AD patients. Here, we report that Aβ peptides also impair another form of synaptic plasticity; cerebellar long-term depression (LTD). In the cerebellum of commonly used AD mouse model, APPswe/PS1dE9 mice, Aβ plaques were detected from 8 months and profound accumulation of Aβ plaques was observed at 18 onths of age. Biochemical analysis revealed relatively high levels of APP protein and Aβ in the cerebellum of APPswe/PS1dE9 mice. At pre-Aβ accumulation stage, LTD induction, and motor coordination are disturbed. These results indicate that soluble Aβ oligomers disturb LTD induction and cerebellar function in AD mouse model. © 2014 International Society for Neurochemistry.

Low-frequency magnetic fields do not aggravate disease in mouse models of Alzheimer's disease and amyotrophic lateral sclerosis

PubMed Central

Liebl, Martina P.; Windschmitt, Johannes; Besemer, Anna S.; Schäfer, Anne-Kathrin; Reber, Helmut; Behl, Christian; Clement, Albrecht M.

2015-01-01

Low-frequency magnetic fields (LF-MF) generated by power lines represent a potential environmental health risk and are classified as possibly carcinogenic by the World Health Organization. Epidemiological studies indicate that LF-MF might propagate neurodegenerative diseases like Alzheimer's disease (AD) or amyotrophic lateral sclerosis (ALS). We conducted a comprehensive analysis to determine whether long-term exposure to LF-MF (50 Hz, 1 mT) interferes with disease development in established mouse models for AD and ALS, namely APP23 mice and mice expressing mutant Cu/Zn-superoxide dismutase (SOD1), respectively. Exposure for 16 months did not aggravate learning deficit of APP23 mice. Likewise, disease onset and survival of SOD1G85R or SOD1G93A mice were not altered upon LF-MF exposure for ten or eight months, respectively. These results and an extended biochemical analysis of protein aggregation, glial activation and levels of toxic protein species suggests that LF-MF do not affect cellular processes involved in the pathogenesis of AD or ALS. PMID:25717019

Content Analysis of Diet-Related Mobile Apps: A Self-Regulation Perspective.

PubMed

Zahry, Nagwan R; Cheng, Ying; Peng, Wei

2016-10-01

Diet-related mobile apps hold promise in helping individuals self-regulate their eating behaviors. Nevertheless, little is known about the extent to which diet-related mobile apps incorporate the established behavior change theories and evidence-based practices that promote dietary self-regulation. Guided by the self-regulation aspect of Bandura's social cognitive theory and the Dietary Guidelines for Americans 2010 of the U.S. Department of Agriculture, this study conducts a content analysis of diet-related mobile apps for iPhone (N = 400). In terms of the adherence to the self-regulation aspect of the social cognitive theory, results show that although 72.5% of the apps incorporate at least one theoretical construct, few apps tap all three processes of self-regulation (i.e., self-observation/monitoring, judgment process, and self-reaction). Additionally, outcome expectation is manifested in a majority of the diet-related apps. In terms of the Dietary Guidelines for Americans 2010, while the diet-related apps equally emphasize setting goals for calorie intake or nutrient consumption, more apps feature nutrient tracking than calorie tracking. Implications and limitations are discussed.

Evaluation of Cu(i) binding to the E2 domain of the amyloid precursor protein - a lesson in quantification of metal binding to proteins via ligand competition.

PubMed

Young, Tessa R; Wedd, Anthony G; Xiao, Zhiguang

2018-01-24

The extracellular domain E2 of the amyloid precursor protein (APP) features a His-rich metal-binding site (denoted as the M1 site). In conjunction with surrounding basic residues, the site participates in interactions with components of the extracellular matrix including heparins, a class of negatively charged polysaccharide molecules of varying length. This work studied the chemistry of Cu(i) binding to APP E2 with the probe ligands Bcs, Bca, Fz and Fs. APP E2 forms a stable Cu(i)-mediated ternary complex with each of these anionic ligands. The complex with Bca was selected for isolation and characterization and was demonstrated, by native ESI-MS analysis, to have the stoichiometry E2 : Cu(i) : Bca = 1 : 1 : 1. Formation of these ternary complexes is specific for the APP E2 domain and requires Cu(i) coordination to the M1 site. Mutation of the M1 site was consistent with the His ligands being part of the E2 ligand set. It is likely that interactions between the negatively charged probe ligands and a positively charged patch on the surface of APP E2 are one aspect of the generation of the stable ternary complexes. Their formation prevented meaningful quantification of the affinity of Cu(i) binding to the M1 site with these probe ligands. However, the ternary complexes are disrupted by heparin, allowing reliable determination of a picomolar Cu(i) affinity for the E2/heparin complex with the Fz or Bca probe ligands. This is the first documented example of the formation of stable ternary complexes between a Cu(i) binding protein and a probe ligand. The ready disruption of the complexes by heparin identified clear 'tell-tale' signs for diagnosis of ternary complex formation and allowed a systematic review of conditions and criteria for reliable determination of affinities for metal binding via ligand competition. This study also provides new insights into a potential correlation of APP functions regulated by copper binding and heparin interaction.

Apps in therapy: occupational therapists' use and opinions.

PubMed

Seifert, Anna M; Stotz, Nicole; Metz, Alexia E

2017-11-01

To gather information on occupational therapy practitioners' use and opinions of apps, an online survey was distributed to occupational therapy practitioners licensed in the state of Ohio. The survey sought information regarding clinical populations and skill areas for which apps are used, potential barriers to use of apps and preferred apps/app features. OTs working in medical and education-based settings and with clients of all ages responded to the survey. Over half (53%) reported not using apps in therapy, with "not having access to the technology at work" being the leading reason endorsed. Of practitioners who did report using apps, the majority used them with ≤25% of their case load and primarily used tablets to do so. Clinicians indicated that they use apps for a wide variety of reasons, including to promote skill building and to support the therapeutic process. Preferred features included the ability to grade difficulty up/down, multiple uses and accurate feedback. Recommendations from peers were the most commonly reported way respondents found new apps. The results suggest that occupational therapy practitioners employ clinical reasoning when implementing apps in therapy. Possible ways to improve access to apps for therapists who would like to implement them are discussed. Implications for Rehabilitation Many occupational therapy practitioners are using apps with at least a portion of their caseloads. Therapists select apps based on peer recommendations, most commonly selecting those which promote skill building and support the therapeutic process. More therapists might make use of apps if potential barriers were reduced or eliminated, including availability of technology in the clinical practice setting, therapist training and education, therapist input into app development and an enhanced evidence base.

[Effects of aluminium chloride on the methylation of app in hippocampal of rats].

PubMed

Yang, Xiaojuan; Yuan, Yuzhou; Niu, Qiao

2016-05-01

To study the effect of aluminum chloride on amyloid precursor protein ( APP ) promoter methylation and the content of amyloid beta-protein (Abeta) in hippocampus of rats. Forty male SPF grade SD rats were divided into four groups: control group (0.9% NaCl), 10 mg/kg AlCl3 group, 20 mg/kg AlCl3 group, and 30 mg/kg AlCl3 group, respectively. After treatment for 8 weeks, the APP methylation level and expressions of APP mRNA was detected by methylation specific PCR and quantitative real time PCR, respectively. The content of APP and Abeta were detected with enzym-linked immunosorbent assay (ELISA). With the increase of the content of aluminium chloride, the escape latency were significantly prolong (P < 0.05), numbers of traversing flat in AlCl3 20 mg/kg and AlCl3 30 mg/kg group high and were significantly decreased (P < 0.05), the methylation level of APP contaminated by AlCl3 were decreased (chi2 = 27.61, P < 0.05), the level of APP methylation in 30 mg/kg AlCl3 group was lower than three groups (P < 0.01). With the increase of aluminium chloride, the level of APP methylation were decreased (chi2 = 19.08, P < 0.01). With the increase of the content of aluminium chloride, the methylation level of APP treated with 20 mg/kg AlCl3 and 30 mg/kg AlCl3 were decreased compared with control group (P < 0.05), the level of APP methylation in 30 mg/kg AlCl3 group was lower than 10mg/kg AlCl3 group (P < 0.05), the APP mRNA expression level in AlCl3 group was of statistical significance compared to the control group (F = 8.973, P < 0.05), the level of APP mRNA in 30 mg/kg AlCl3 were higher than 10 mg/kg AlCl3 (P < 0.05). Compared with the control group, the content of APP and Abeta in hippocampus of AlCl3 group were increased (F = 11.14, P = 0. 032, F = 17.82, P = 0.018), and 30 mg/kg AlCl3 group were higher than 10 mg/kg AlCl3 (P < 0.05), the content of APP in 20 mg/kg AlCl3 group were higher than 10 mg/kg AlCl3 (P < 0.05). The result of immunohistochemistry revealed that the grey scale in hippocampus, which suggested that the deposition of Abeta was the most in 20 mg/kg AlCl3 group and 30 mg/kg AlCl3 group. Aluminium chloride might cause APP promoter methylation decline, affect the APP mRNA and APP expression increased and result in Abeta deposition in hippocampal.

MicroRNA-339-5p down-regulates protein expression of β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) in human primary brain cultures and is reduced in brain tissue specimens of Alzheimer disease subjects.

PubMed

Long, Justin M; Ray, Balmiki; Lahiri, Debomoy K

2014-02-21

Alzheimer disease (AD) results, in part, from the excess accumulation of the amyloid-β (Aβ) peptide as neuritic plaques in the brain. The short Aβ peptide is derived from the large transmembrane Aβ precursor protein (APP). The rate-limiting step in the production of Aβ from APP is mediated by the β-site APP-cleaving enzyme 1 (BACE1). Dysregulation of BACE1 levels leading to excess Aβ deposition is implicated in sporadic AD. Thus, elucidating the full complement of regulatory pathways that control BACE1 expression is key to identifying novel drug targets central to the Aβ-generating process. MicroRNAs (miRNAs) are expected to participate in this molecular network. Here, we identified a known miRNA, miR-339-5p, as a key contributor to this regulatory network. Two distinct miR-339-5p target sites were predicted in the BACE1 3'-UTR by in silico analyses. Co-transfection of miR-339-5p with a BACE1 3'-UTR reporter construct resulted in significant reduction in reporter expression. Mutation of both target sites eliminated this effect. Delivery of the miR-339-5p mimic also significantly inhibited expression of BACE1 protein in human glioblastoma cells and human primary brain cultures. Delivery of target protectors designed against the miR-339-5p BACE1 3'-UTR target sites in primary human brain cultures significantly elevated BACE1 expression. Finally, miR-339-5p levels were found to be significantly reduced in brain specimens isolated from AD patients as compared with age-matched controls. Therefore, miR-339-5p regulates BACE1 expression in human brain cells and is most likely dysregulated in at least a subset of AD patients making this miRNA a novel drug target.

MicroRNA-339-5p Down-regulates Protein Expression of β-Site Amyloid Precursor Protein-Cleaving Enzyme 1 (BACE1) in Human Primary Brain Cultures and Is Reduced in Brain Tissue Specimens of Alzheimer Disease Subjects*

PubMed Central

Long, Justin M.; Ray, Balmiki; Lahiri, Debomoy K.

2014-01-01

Alzheimer disease (AD) results, in part, from the excess accumulation of the amyloid-β (Aβ) peptide as neuritic plaques in the brain. The short Aβ peptide is derived from the large transmembrane Aβ precursor protein (APP). The rate-limiting step in the production of Aβ from APP is mediated by the β-site APP-cleaving enzyme 1 (BACE1). Dysregulation of BACE1 levels leading to excess Aβ deposition is implicated in sporadic AD. Thus, elucidating the full complement of regulatory pathways that control BACE1 expression is key to identifying novel drug targets central to the Aβ-generating process. MicroRNAs (miRNAs) are expected to participate in this molecular network. Here, we identified a known miRNA, miR-339-5p, as a key contributor to this regulatory network. Two distinct miR-339-5p target sites were predicted in the BACE1 3′-UTR by in silico analyses. Co-transfection of miR-339-5p with a BACE1 3′-UTR reporter construct resulted in significant reduction in reporter expression. Mutation of both target sites eliminated this effect. Delivery of the miR-339-5p mimic also significantly inhibited expression of BACE1 protein in human glioblastoma cells and human primary brain cultures. Delivery of target protectors designed against the miR-339-5p BACE1 3′-UTR target sites in primary human brain cultures significantly elevated BACE1 expression. Finally, miR-339-5p levels were found to be significantly reduced in brain specimens isolated from AD patients as compared with age-matched controls. Therefore, miR-339-5p regulates BACE1 expression in human brain cells and is most likely dysregulated in at least a subset of AD patients making this miRNA a novel drug target. PMID:24352696

PSD-93 Attenuates Amyloid-β-Mediated Cognitive Dysfunction by Promoting the Catabolism of Amyloid-β.

PubMed

Yu, Linjie; Liu, Yi; Yang, Hui; Zhu, Xiaolei; Cao, Xiang; Gao, Jun; Zhao, Hui; Xu, Yun

2017-01-01

Amyloid-β (Aβ) is a key neuropathological hallmark of Alzheimer's disease (AD). Postsynaptic density protein 93 (PSD-93) is a key scaffolding protein enriched at postsynaptic sites. The aim of the present study was to examine whether PSD-93 overexpression could alleviate Aβ-induced cognitive dysfunction in APPswe/PS1dE9 (APP/PS1) mice by reducing Aβ levels in the brain. The level of PSD-93 was significantly decreased in the hippocampus of 6-month-old APP/PS1 mice compared with that in wild-type mice. Following lentivirus-mediated PSD-93 overexpression, cognitive function, synaptic function, and amyloid burden were investigated. The open field test, Morris water maze test, and fear condition test revealed that PSD-93 overexpression ameliorated spatial memory deficits in APP/PS1 mice. The facilitation of long-term potentiation induction was observed in APP/PS1 mice after PSD-93 overexpression. The expression of somatostatin receptor 4 (SSTR4) and neprilysin was increased, while the amyloid plaque load and Aβ levels were decreased in the brains of APP/PS1 mice. Moreover, PSD-93 interacted with SSTR4 and affected the level of SSTR4 on cell membrane, which was associated with the ubiquitination. Together, these findings suggest that PSD-93 attenuates spatial memory deficits and decreases amyloid levels in APP/PS1 mice, which might be associated with Aβ catabolism, and overexpression of PSD-93 might be a potential therapy for AD.

Car App's Persuasive Design Principles and Behavior Change

ERIC Educational Resources Information Center

Zhang, Chao; Wan, Lili; Min, Daihwan

2016-01-01

The emphasis of this study lies in behavior change after using car apps that assist users in using their vehicles and establishing a process for examining the interrelationship between car app's persuasive characteristics and behavior change. A categorizing method was developed and 697 car apps were investigated and classified into eight…

Protein expression of targets of the FMRP regulon is altered in brains of subjects with schizophrenia and mood disorders

PubMed Central

Folsom, Timothy D.; Thuras, Paul D.; Fatemi, S. Hossein

2016-01-01

Fragile X mental retardation protein (FMRP) is an RNA binding protein with 842 target mRNAs in mammalian brain. Silencing of the fragile X mental retardation 1 (FMR1) gene leads to loss of expression of FMRP and upregulated metabotropic glutamate receptor 5 (mGluR5) signaling resulting in the multiple physical and cognitive deficits associated with fragile X syndrome (FXS). Reduced FMRP expression has been identified in subjects with autism, schizophrenia, bipolar disorder, and major depression who do not carry the mutation for FMR1. Our laboratory has recently demonstrated altered expression of four downstream targets of FMRP-mGluR5 signaling in brains of subjects with autism: homer 1, amyloid beta A4 precursor protein (APP), ras-related C3 botulinum toxin substrate 1 (RAC1), and striatal-enriched protein tyrosine phosphatase (STEP). In the current study we investigated the expression of the same four proteins in lateral cerebella of subjects with schizophrenia, bipolar disorder, and major depression and in frontal cortex of subjects with schizophrenia and bipolar disorder. In frontal cortex we observed: 1) reduced expression of 120 kDa form of APP in subjects with schizophrenia and bipolar disorder; 2) reduced expression of 61 kDa and 33 kDa forms of STEP in subjects with schizophrenia; 3) reduced expression of 88 kDa form of APP in subjects with bipolar disorder; and 3) trends for reduced expression of 88 kDa form of APP and homer 1 in subjects with schizophrenia and bipolar disorder, respectively. In lateral cerebella there was no group difference, however we observed increased expression of RAC1 in subjects with bipolar disorder, and trends for increased RAC1 in subjects with schizophrenia and major depression. Our results provide further evidence that proteins involved in the FMRP-mGluR5 signaling pathway are altered in schizophrenia and mood disorders. PMID:25956630

Protein expression of targets of the FMRP regulon is altered in brains of subjects with schizophrenia and mood disorders.

PubMed

Folsom, Timothy D; Thuras, Paul D; Fatemi, S Hossein

2015-07-01

Fragile X mental retardation protein (FMRP) is an RNA binding protein with 842 target mRNAs in mammalian brain. Silencing of the fragile X mental retardation 1 (FMR1) gene leads to loss of expression of FMRP and upregulated metabotropic glutamate receptor 5 (mGluR5) signaling resulting in the multiple physical and cognitive deficits associated with fragile X syndrome (FXS). Reduced FMRP expression has been identified in subjects with autism, schizophrenia, bipolar disorder, and major depression who do not carry the mutation for FMR1. Our laboratory has recently demonstrated altered expression of four downstream targets of FMRP-mGluR5 signaling in brains of subjects with autism: homer 1, amyloid beta A4 precursor protein (APP), ras-related C3 botulinum toxin substrate 1 (RAC1), and striatal-enriched protein tyrosine phosphatase (STEP). In the current study we investigated the expression of the same four proteins in lateral cerebella of subjects with schizophrenia, bipolar disorder, and major depression and in frontal cortex of subjects with schizophrenia and bipolar disorder. In frontal cortex we observed: 1) reduced expression of 120 kDa form of APP in subjects with schizophrenia and bipolar disorder; 2) reduced expression of 61 kDa and 33k Da forms of STEP in subjects with schizophrenia; 3) reduced expression of 88 kDa form of APP in subjects with bipolar disorder; and 3) trends for reduced expression of 88 kDa form of APP and homer 1 in subjects with schizophrenia and bipolar disorder, respectively. In lateral cerebella there was no group difference, however we observed increased expression of RAC1 in subjects with bipolar disorder, and trends for increased RAC1 in subjects with schizophrenia and major depression. Our results provide further evidence that proteins involved in the FMRP-mGluR5 signaling pathway are altered in schizophrenia and mood disorders. Copyright © 2015 Elsevier B.V. All rights reserved.

The Totality App — General Lessons and Future Eclipses

NASA Astrophysics Data System (ADS)

Bennett, Jeffrey

2018-06-01

With the excitement around the 2017 eclipse, I worked with an app development company to create the Totality app, which featured eclipse predictions from the code of Xavier Jubier. We have since updated the app for future eclipses, including a Spanish version given the upcoming eclipses in Chile/Argentina. I will briefly discuss the current app, the process through which we developed it, and relevant lessons learned along the way that may be useful to others interested in developing apps for astronomy education.

Comparison of gene expression levels of appA, ppsR, and EL368 in Erythrobacter litoralis spheroplasts under aerobic and anaerobic conditions, and under blue light, red light, and dark conditions.

PubMed

Nishino, Koki; Takahashi, Sawako; Nishida, Hiromi

2018-03-31

We compared the gene expression levels of the blue-light-responsive genes, appA (encoding photosynthesis promoting protein AppA), ppsR (encoding photosynthesis suppressing protein PpsR), and EL368 (encoding a blue-light-activated histidine kinase with a light, oxygen, or voltage domain) between aerobic and anaerobic conditions in spheroplasts of the aerobic photosynthetic bacterium Erythrobacter litoralis. The spheroplasts conducted photosynthesis under red light but not under blue light. All three blue-light-responsive genes showed higher expression under aerobic conditions than under anaerobic conditions under blue light. In contrast, under red light, although the expression level of appA was higher in the presence of oxygen than in the absence of oxygen, the expression levels of ppsR and EL368 were similar in the presence and absence of oxygen. Our findings demonstrate that the expression of blue-light-responsive genes is strongly affected by oxygen in E. litoralis spheroplasts.

TRPC6 specifically interacts with APP to inhibit its cleavage by γ-secretase and reduce Aβ production

PubMed Central

Wang, Junfeng; Lu, Rui; Yang, Jian; Li, Hongyu; He, Zhuohao; Jing, Naihe; Wang, Xiaomin; Wang, Yizheng

2015-01-01

Generation of β-amyloid (Aβ) peptide in Alzheimer's disease involves cleavage of amyloid precursor protein (APP) by γ-secretase, a protease known to cleave several substrates, including Notch. Finding specific modulators for γ-secretase could be a potential avenue to treat the disease. Here, we report that transient receptor potential canonical (TRPC) 6 specifically interacts with APP leading to inhibition of its cleavage by γ-secretase and reduction in Aβ production. TRPC6 interacts with APP (C99), but not with Notch, and prevents C99 interaction with presenilin 1 (PS1). A fusion peptide derived from TRPC6 also reduces Aβ levels without effect on Notch cleavage. Crossing APP/PS1 mice with TRPC6 transgenic mice leads to a marked reduction in both plaque load and Aβ levels, and improvement in structural and behavioural impairment. Thus, TRPC6 specifically modulates γ-secretase cleavage of APP and preventing APP (C99) interaction with PS1 via TRPC6 could be a novel strategy to reduce Aβ formation. PMID:26581893

Molecular determinants and thermodynamics of the amyloid precursor protein transmembrane domain implicated in Alzheimer's disease

PubMed Central

Wang, Hao; Barreyro, Laura; Provasi, Davide; Djemil, Imane; Torres-Arancivia, Celia; Filizola, Marta; Ubarretxena-Belandia, Iban

2011-01-01

The deposition of toxic amyloid-β peptide (Aβ) aggregates in the brain is a hallmark of Alzheimer's disease. The intramembrane proteolysis by γ-secretase of the amyloid precursor protein carboxy-terminal fragment (APP-βCTF) constitutes the final step in the production of Aβs. Mounting evidence suggests that APP-βCTF is a transmembrane domain (TMD) dimer, and that dimerization might modulate the production of Aβ species that are prone to aggregation, and therefore most toxic. We combined experimental and computational approaches to study the molecular determinants and thermodynamics of APP-βCTF dimerization, and produced a unifying structural model that reconciles much of the published data. Using a cell assay, which exploits a dimerization-dependent activator of transcription, we identified specific dimerization-disrupting mutations located mostly at the N-terminus of the TMD of APP-βCTF. The ability of selected mutants to disrupt the dimerization of full length APP-βCTF was confirmed by fluorescence resonance energy transfer experiments. Free-energy estimates of wild-type (WT) and mutants of the TMD of APP-βCTF derived from enhanced molecular dynamics simulations showed that the dimeric state is comprised of different arrangements, in which either 709GXXXA713 or 700GXXXG704GXXXG708 interaction motifs can engage in symmetric or asymmetric associations. Mutations along the TMD of APP-βCTF were found to modulate the relative free energy of the dimeric configurations, and to differently affect the distribution of interfaces within the dimeric state. This observation might have important biological implications, since dimers with a different arrangement of the transmembrane helices are likely to be recognized differently by γ-secretase and lead to a variation of Aβ levels. PMID:21440556

Curcumin Decreases Hyperphosphorylation of Tau by Down-Regulating Caveolin-1/GSK-3β in N2a/APP695swe Cells and APP/PS1 Double Transgenic Alzheimer's Disease Mice.

PubMed

Sun, Jieyun; Zhang, Xiong; Wang, Chen; Teng, Zhipeng; Li, Yu

2017-01-01

Caveolin-1, the marker protein of membranal caveolae, is not only involved in cholesterol regulation, but also participates in the cleavage of amyloid [Formula: see text]-protein precursor (APP) and the generation of [Formula: see text]-amyloid peptide. It has been reported to be tightly related with Tau. In our previous studies, curcumin has been confirmed to play a neuroprotective role in Alzheimer's disease (AD), but its effects on Caveolin-1, Tau and their correlation, and the mechanism is still unknown. As such, in the present study, N2a/WT cells, N2a/APP695swe cell and six-month-old APP/PS1 double transgenic mice were enrolled. After curcumin treatment, the expression of Caveolin-1, Tau and their relationship was detected, and the potential mechanisms were explored. The results showed that in the N2a/APP695swe cells, curcumin not only decreased the number of caveolae, but also made their membrane to be thinner; and curcumin could decreased the expression of phosphorylated Tau (P-Tau(ser404)/Tau) and Caveolin-1 ([Formula: see text]), but the expression of phosphorylated GSK-3[Formula: see text] (P-GSK-3[Formula: see text]/GSK-3[Formula: see text] was increased ([Formula: see text]). In APP/PS1 transgenic mice, the same results were observed. Taken together, our data suggest that curcumin may play an important role in AD via reducing Caveolin-1, inactivating GSK-3[Formula: see text] and inhibiting the abnormal excessive phosphorylation of Tau, which will provide a new theory for AD treatment with curcumin.

Hierarchical regulation of photosynthesis gene expression by the oxygen-responsive PrrBA and AppA-PpsR systems of Rhodobacter sphaeroides.

PubMed

Gomelsky, Larissa; Moskvin, Oleg V; Stenzel, Rachel A; Jones, Denise F; Donohue, Timothy J; Gomelsky, Mark

2008-12-01

In the facultatively phototrophic proteobacterium Rhodobacter sphaeroides, formation of the photosynthetic apparatus is oxygen dependent. When oxygen tension decreases, the response regulator PrrA of the global two-component PrrBA system is believed to directly activate transcription of the puf, puh, and puc operons, encoding structural proteins of the photosynthetic complexes, and to indirectly upregulate the photopigment biosynthesis genes bch and crt. Decreased oxygen also results in inactivation of the photosynthesis-specific repressor PpsR, bringing about derepression of the puc, bch, and crt operons. We uncovered a hierarchical relationship between these two regulatory systems, earlier thought to function independently. We also more accurately assessed the spectrum of gene targets of the PrrBA system. First, expression of the appA gene, encoding the PpsR antirepressor, is PrrA dependent, which establishes one level of hierarchical dominance of the PrrBA system over AppA-PpsR. Second, restoration of the appA transcript to the wild-type level is insufficient for rescuing phototrophic growth impairment of the prrA mutant, whereas inactivation of ppsR is sufficient. This suggests that in addition to controlling appA transcription, PrrA affects the activity of the AppA-PpsR system via an as yet unidentified mechanism(s). Third, PrrA directly activates several bch and crt genes, traditionally considered to be the PpsR targets. Therefore, in R. sphaeroides, the global PrrBA system regulates photosynthesis gene expression (i) by rigorous control over the photosynthesis-specific AppA-PpsR regulatory system and (ii) by extensive direct transcription activation of genes encoding structural proteins of photosynthetic complexes as well as genes encoding photopigment biosynthesis enzymes.

Membrane-targeted strategies for modulating APP and Aβ-mediated toxicity

PubMed Central

Price, Katherine A; Crouch, Peter J; Donnelly, Paul S; Masters, Colin L; White, Anthony R; Curtain, Cyril C

2009-01-01

Abstract Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by numerous pathological features including the accumulation of neurotoxic amyloid-β (Aβ) peptide. There is currently no effective therapy for AD, but the development of therapeutic strategies that target the cell membrane is gaining increased interest. The amyloid precursor protein (APP) from which Aβ is formed is a membrane-bound protein, and Aβ production and toxicity are both membrane mediated events. This review describes the critical role of cell membranes in AD with particular emphasis on how the composition and structure of the membrane and its specialized regions may influence toxic or benign Aβ/APP pathways in AD. The putative role of copper (Cu) in AD is also discussed, and we highlight how targeting the cell membrane with Cu complexes has therapeutic potential in AD. PMID:19278455

An Alzheimer Disease-linked Rare Mutation Potentiates Netrin Receptor Uncoordinated-5C-induced Signaling That Merges with Amyloid β Precursor Protein Signaling.

PubMed

Hashimoto, Yuichi; Toyama, Yuka; Kusakari, Shinya; Nawa, Mikiro; Matsuoka, Masaaki

2016-06-03

A missense mutation (T835M) in the uncoordinated-5C (UNC5C) netrin receptor gene increases the risk of late-onset Alzheimer disease (AD) and also the vulnerability of neurons harboring the mutation to various insults. The molecular mechanisms underlying T835M-UNC5C-induced death remain to be elucidated. In this study, we show that overexpression of wild-type UNC5C causes low-grade death, which is intensified by an AD-linked mutation T835M. An AD-linked survival factor, calmodulin-like skin protein (CLSP), and a natural ligand of UNC5C, netrin1, inhibit this death. T835M-UNC5C-induced neuronal cell death is mediated by an intracellular death-signaling cascade, consisting of death-associated protein kinase 1/protein kinase D/apoptosis signal-regulating kinase 1 (ASK1)/JNK/NADPH oxidase/caspases, which merges at ASK1 with a death-signaling cascade, mediated by amyloid β precursor protein (APP). Notably, netrin1 also binds to APP and partially inhibits the death-signaling cascade, induced by APP. These results may provide new insight into the amyloid β-independent pathomechanism of AD. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

CytoCluster: A Cytoscape Plugin for Cluster Analysis and Visualization of Biological Networks.

PubMed

Li, Min; Li, Dongyan; Tang, Yu; Wu, Fangxiang; Wang, Jianxin

2017-08-31

Nowadays, cluster analysis of biological networks has become one of the most important approaches to identifying functional modules as well as predicting protein complexes and network biomarkers. Furthermore, the visualization of clustering results is crucial to display the structure of biological networks. Here we present CytoCluster, a cytoscape plugin integrating six clustering algorithms, HC-PIN (Hierarchical Clustering algorithm in Protein Interaction Networks), OH-PIN (identifying Overlapping and Hierarchical modules in Protein Interaction Networks), IPCA (Identifying Protein Complex Algorithm), ClusterONE (Clustering with Overlapping Neighborhood Expansion), DCU (Detecting Complexes based on Uncertain graph model), IPC-MCE (Identifying Protein Complexes based on Maximal Complex Extension), and BinGO (the Biological networks Gene Ontology) function. Users can select different clustering algorithms according to their requirements. The main function of these six clustering algorithms is to detect protein complexes or functional modules. In addition, BinGO is used to determine which Gene Ontology (GO) categories are statistically overrepresented in a set of genes or a subgraph of a biological network. CytoCluster can be easily expanded, so that more clustering algorithms and functions can be added to this plugin. Since it was created in July 2013, CytoCluster has been downloaded more than 9700 times in the Cytoscape App store and has already been applied to the analysis of different biological networks. CytoCluster is available from http://apps.cytoscape.org/apps/cytocluster.

CytoCluster: A Cytoscape Plugin for Cluster Analysis and Visualization of Biological Networks

PubMed Central

Li, Min; Li, Dongyan; Tang, Yu; Wang, Jianxin

2017-01-01

Nowadays, cluster analysis of biological networks has become one of the most important approaches to identifying functional modules as well as predicting protein complexes and network biomarkers. Furthermore, the visualization of clustering results is crucial to display the structure of biological networks. Here we present CytoCluster, a cytoscape plugin integrating six clustering algorithms, HC-PIN (Hierarchical Clustering algorithm in Protein Interaction Networks), OH-PIN (identifying Overlapping and Hierarchical modules in Protein Interaction Networks), IPCA (Identifying Protein Complex Algorithm), ClusterONE (Clustering with Overlapping Neighborhood Expansion), DCU (Detecting Complexes based on Uncertain graph model), IPC-MCE (Identifying Protein Complexes based on Maximal Complex Extension), and BinGO (the Biological networks Gene Ontology) function. Users can select different clustering algorithms according to their requirements. The main function of these six clustering algorithms is to detect protein complexes or functional modules. In addition, BinGO is used to determine which Gene Ontology (GO) categories are statistically overrepresented in a set of genes or a subgraph of a biological network. CytoCluster can be easily expanded, so that more clustering algorithms and functions can be added to this plugin. Since it was created in July 2013, CytoCluster has been downloaded more than 9700 times in the Cytoscape App store and has already been applied to the analysis of different biological networks. CytoCluster is available from http://apps.cytoscape.org/apps/cytocluster. PMID:28858211

Reduced Aβ secretion by human neurons under conditions of strongly increased BACE activity.

PubMed

Scholz, Diana; Chernyshova, Yana; Ückert, Anna-Katharina; Leist, Marcel

2018-05-27

The initial step in the amyloidogenic cascade of amyloid precursor protein (APP) processing is catalyzed by beta-site APP-cleaving enzyme (BACE), and this protease has increased activities in affected areas of Alzheimer's disease brains. We hypothesized that altered APP processing, due to augmented BACE activity, would affect the actions of direct and indirect BACE inhibitors. We therefore compared postmitotic human neurons (LUHMES) with their BACE-overexpressing counterparts (BLUHMES). Although β-cleavage of APP was strongly increased in BLUHMES, they produced less full-length and truncated amyloid beta (Aβ) than LUHMES. Moreover, low concentrations of BACE inhibitors decreased cellular BACE activity as expected, but increased Aβ 1-40 levels. Several other approaches to modulate BACE activity led to a similar, apparently paradoxical, behavior. For instance, reduction of intracellular acidification by bepridil increased Aβ production in parallel with decreased BACE activity. In contrast to BLUHMES, the respective control cells (LUHMES or BLUHMES with catalytically inactive BACE) showed conventional pharmacological responses. Other non-canonical neurochemical responses (so-called 'rebound effects') are well-documented for the Aβ pathway, especially for γ-secretase: a partial block of its activity leads to an increased Aβ secretion by some cell types. We therefore compared LUHMES and BLUHMES regarding rebound effects of γ-secretase inhibitors and found an Aβ rise in LUHMES but not in BLUHMES. Thus, different cellular factors are responsible for the γ-secretase- vs. BACE-related Aβ rebound. We conclude that increased BACE activity, possibly accompanied by an altered cellular localization pattern, can dramatically influence Aβ generation in human neurons and affect pharmacological responses to secretase inhibitors. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Finding Quality Geometry Apps: Not as Simple as a[superscript 2] + b[superscript 2] = c[superscript 2

ERIC Educational Resources Information Center

Larkin, Kevin

2016-01-01

Trying to find quality apps for use in mathematics classes can be time consuming and bewildering. This article outlines a process for evaluating apps and provides teachers with access to comprehensive qualitative evaluations of 53 geometrical apps based on pedagogical, mathematical and cognitive fidelities.

Implementing Project SIED: Special Education Teachers' Perceptions of a Simplified Technology Decision-Making Process for App Identification and Evaluation

ERIC Educational Resources Information Center

Schmidt, Matthew M.; Lin, Meng-Fen Grace; Paek, Seungoh; MacSuga-Gage, Ashley; Gage, Nicholas A.

2017-01-01

The worldwide explosion in popularity of mobile devices has created a dramatic increase in mobile software (apps) that are quick and easy to find and install, cheap, disposable, and usually single purpose. Hence, teachers need an equally streamlined and simplified decision-making process to help them identify educational apps--an approach that…

Digital health technology and trauma: development of an app to standardize care.

PubMed

Hsu, Jeremy M

2015-04-01

Standardized practice results in less variation, therefore reducing errors and improving outcome. Optimal trauma care is achieved through standardization, as is evidenced by the widespread adoption of the Advanced Trauma Life Support approach. The challenge for an individual institution is how does one educate and promulgate these standardized processes widely and efficiently? In today's world, digital health technology must be considered in the process. The aim of this study was to describe the process of developing an app, which includes standardized trauma algorithms. The objective of the app was to allow easy, real-time access to trauma algorithms, and therefore reduce omissions/errors. A set of trauma algorithms, relevant to the local setting, was derived from the best available evidence. After obtaining grant funding, a collaborative endeavour was undertaken with an external specialist app developing company. The process required 6 months to translate the existing trauma algorithms into an app. The app contains 32 separate trauma algorithms, formatted as a single-page flow diagram. It utilizes specific smartphone features such as 'pinch to zoom', jump-words and pop-ups to allow rapid access to the desired information. Improvements in trauma care outcomes result from reducing variation. By incorporating digital health technology, a trauma app has been developed, allowing easy and intuitive access to evidenced-based algorithms. © 2015 Royal Australasian College of Surgeons.

Neprilysin and Aβ Clearance: Impact of the APP Intracellular Domain in NEP Regulation and Implications in Alzheimer’s Disease

PubMed Central

Grimm, Marcus O. W.; Mett, Janine; Stahlmann, Christoph P.; Haupenthal, Viola J.; Zimmer, Valerie C.; Hartmann, Tobias

2013-01-01

One of the characteristic hallmarks of Alzheimer’s disease (AD) is an accumulation of amyloid β (Aβ) leading to plaque formation and toxic oligomeric Aβ complexes. Besides the de novo synthesis of Aβ caused by amyloidogenic processing of the amyloid precursor protein (APP), Aβ levels are also highly dependent on Aβ degradation. Several enzymes are described to cleave Aβ. In this review we focus on one of the most prominent Aβ degrading enzymes, the zinc-metalloprotease Neprilysin (NEP). In the first part of the review we discuss beside the general role of NEP in Aβ degradation the alterations of the enzyme observed during normal aging and the progression of AD. In vivo and cell culture experiments reveal that a decreased NEP level results in an increased Aβ level and vice versa. In a pathological situation like AD, it has been reported that NEP levels and activity are decreased and it has been suggested that certain polymorphisms in the NEP gene result in an increased risk for AD. Conversely, increasing NEP activity in AD mouse models revealed an improvement in some behavioral tests. Therefore it has been suggested that increasing NEP might be an interesting potential target to treat or to be protective for AD making it indispensable to understand the regulation of NEP. Interestingly, it is discussed that the APP intracellular domain (AICD), one of the cleavage products of APP processing, which has high similarities to Notch receptor processing, might be involved in the transcriptional regulation of NEP. However, the mechanisms of NEP regulation by AICD, which might be helpful to develop new therapeutic strategies, are up to now controversially discussed and summarized in the second part of this review. In addition, we review the impact of AICD not only in the transcriptional regulation of NEP but also of further genes. PMID:24391587

Osmotic virial coefficients for model protein and colloidal solutions: importance of ensemble constraints in the analysis of light scattering data.

PubMed

Siderius, Daniel W; Krekelberg, William P; Roberts, Christopher J; Shen, Vincent K

2012-05-07

Protein-protein interactions in solution may be quantified by the osmotic second virial coefficient (OSVC), which can be measured by various experimental techniques including light scattering. Analysis of Rayleigh light scattering measurements from such experiments requires identification of a scattering volume and the thermodynamic constraints imposed on that volume, i.e., the statistical mechanical ensemble in which light scattering occurs. Depending on the set of constraints imposed on the scattering volume, one can obtain either an apparent OSVC, A(2,app), or the true thermodynamic OSVC, B(22)(osm), that is rigorously defined in solution theory [M. A. Blanco, E. Sahin, Y. Li, and C. J. Roberts, J. Chem. Phys. 134, 225103 (2011)]. However, it is unclear to what extent A(2,app) and B(22)(osm) differ, which may have implications on the physical interpretation of OSVC measurements from light scattering experiments. In this paper, we use the multicomponent hard-sphere model and a well-known equation of state to directly compare A(2,app) and B(22)(osm). Our results from the hard-sphere equation of state indicate that A(2,app) underestimates B(22)(osm), but in a systematic manner that may be explained using fundamental thermodynamic expressions for the two OSVCs. The difference between A(2,app) and B(22)(osm) may be quantitatively significant, but may also be obscured in experimental application by statistical uncertainty or non-steric interactions. Consequently, the two OSVCs that arise in the analysis of light scattering measurements do formally differ, but in a manner that may not be detectable in actual application.

Repeat propofol anesthesia does not exacerbate plaque deposition or synapse loss in APP/PS1 Alzheimer's disease mice.

PubMed

Woodhouse, Adele; Fernandez-Martos, Carmen Maria; Atkinson, Rachel Alice Kathryn; Hanson, Kelsey Anne; Collins, Jessica Marie; O'Mara, Aidan Ryan; Terblanche, Nico; Skinner, Marcus Welby; Vickers, James Clement; King, Anna Elizabeth

2018-04-25

There is increasing interest in whether anesthetic agents affect the risk or progression of Alzheimer's disease (AD). To mitigate many of the methodological issues encountered in human retrospective cohort studies we have used a transgenic model of AD to investigate the effect of propofol on AD pathology. Six month-old amyloid precursor protein/presenilin 1 (APP/PS1) transgenic AD mice and control mice were exposed to 3 doses of propofol (200 mg/kg) or vehicle, delivered at monthly intervals. There was no difference in the extent of β-amyloid (Aβ) immunolabeled plaque deposition in APP/PS1 mice in vehicle versus propofol treatment groups. We also detected no difference in plaque-associated synapse loss in APP/PS1 mice following repeat propofol exposure relative to vehicle. Western blotting indicated that there was no difference in post-synaptic density protein 95, synaptophysin or glutamic acid decarboxylase 65/67 expression in control or APP/PS1 mice subjected to repeat propofol treatment relative to vehicle. These data suggest that repeat propofol anesthesia may not exacerbate plaque deposition or associated synapse loss in AD. Interestingly, this data also provides some of the first evidence suggesting that repeat propofol exposure in adult wild-type mice does not result in robust long-term alterations in the levels of key excitatory and inhibitory synaptic markers.

The Alzheimer's Disease Mitochondrial Cascade Hypothesis: Progress and Perspectives

PubMed Central

Swerdlow, Russell H.; Burns, Jeffrey M.; Khan, Shaharyar M.

2013-01-01

Ten years ago we first proposed the Alzheimer's disease (AD) mitochondrial cascade hypothesis. This hypothesis maintains gene inheritance defines an individual's baseline mitochondrial function; inherited and environmental factors determine rates at which mitochondrial function changes over time; and baseline mitochondrial function and mitochondrial change rates influence AD chronology. Our hypothesis unequivocally states in sporadic, late-onset AD, mitochondrial function affects amyloid precursor protein (APP) expression, APP processing, or beta amyloid (Aβ) accumulation and argues if an amyloid cascade truly exists, mitochondrial function triggers it. We now review the state of the mitochondrial cascade hypothesis, and discuss it in the context of recent AD biomarker studies, diagnostic criteria, and clinical trials. Our hypothesis predicts biomarker changes reflect brain aging, new AD definitions clinically stage brain aging, and removing brain Aβ at any point will marginally impact cognitive trajectories. Our hypothesis, therefore, offers unique perspective into what sporadic, late-onset AD is and how to best treat it. PMID:24071439

Formononetin attenuates Aβ25-35-induced cytotoxicity in HT22 cells via PI3K/Akt signaling and non-amyloidogenic cleavage of APP.

PubMed

Chen, Lizhi; Ou, Shanshan; Zhou, Lingqi; Tang, Hai; Xu, Jie; Guo, Kaihua

2017-02-03

Amyloid beta (Aβ) is the main component of the amyloid plaques that accumulate in the brains of Alzheimer patients. Here, we reported the protective role of Formononetin (Form) against Aβ 25-35 -induced neurotoxicity in HT22 cells. We found that Form significantly increased the viability of HT22 cells but decreased the cell apoptosis when challenging with Aβ 25-35. The inhibitory effects of Form were associated with PI3K/Akt signaling pathway as PI3K inhibitor (LY294002) or ERα specific inhibitor (MPP) blocked the effects. Form also accelerated the non-amyloidogenic process of amyloid precursor protein (APP) by enhancing α-secretase activity and sAPPα release. Altogether, our findings may provide a novel therapeutic target to treat AD sufferers. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Effects of growth hormone-releasing hormone on sleep and brain interstitial fluid amyloid-β in an APP transgenic mouse model.

PubMed

Liao, Fan; Zhang, Tony J; Mahan, Thomas E; Jiang, Hong; Holtzman, David M

2015-07-01

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by impairment of cognitive function, extracellular amyloid plaques, intracellular neurofibrillary tangles, and synaptic and neuronal loss. There is substantial evidence that the aggregation of amyloid β (Aβ) in the brain plays a key role in the pathogenesis of AD and that Aβ aggregation is a concentration dependent process. Recently, it was found that Aβ levels in the brain interstitial fluid (ISF) are regulated by the sleep-wake cycle in both humans and mice; ISF Aβ is higher during wakefulness and lower during sleep. Intracerebroventricular infusion of orexin increased wakefulness and ISF Aβ levels, and chronic sleep deprivation significantly increased Aβ plaque formation in amyloid precursor protein transgenic (APP) mice. Growth hormone-releasing hormone (GHRH) is a well-documented sleep regulatory substance which promotes non-rapid eye movement sleep. GHRHR(lit/lit) mice that lack functional GHRH receptor have shorter sleep duration and longer wakefulness during light periods. The current study was undertaken to determine whether manipulating sleep by interfering with GHRH signaling affects brain ISF Aβ levels in APPswe/PS1ΔE9 (PS1APP) transgenic mice that overexpress mutant forms of APP and PSEN1 that cause autosomal dominant AD. We found that intraperitoneal injection of GHRH at dark onset increased sleep and decreased ISF Aβ and that delivery of a GHRH antagonist via reverse-microdialysis suppressed sleep and increased ISF Aβ. The diurnal fluctuation of ISF Aβ in PS1APP/GHRHR(lit/lit) mice was significantly smaller than that in PS1APP/GHRHR(lit/+) mice. However despite decreased sleep in GHRHR deficient mice, this was not associated with an increase in Aβ accumulation later in life. One of several possibilities for the finding is the fact that GHRHR deficient mice have GHRH-dependent but sleep-independent factors which protect against Aβ deposition. Copyright © 2014 Elsevier Inc. All rights reserved.

Therapeutic impact of rHuEPO on abnormal platelet APP, BACE 1, presenilin 1, ADAM 10 and Aβ expressions in chronic kidney disease patients with cognitive dysfunction like Alzheimer's disease: A pilot study.

PubMed

G, Vinothkumar; S, Krishnakumar; Sureshkumar; G, Shivashekar; S, Sreedhar; Preethikrishnan; S, Dinesh; A, Sundaram; D, Balakrishnan; Riya; P, Venkataraman

2018-08-01

Cognitive dysfunction is reported to be a major cause of morbidity in chronic kidney disease (CKD). The senile plaques (SPs) in the brain are one of the most pathophysiological characteristics of cognitive dysfunction and its major constituent amyloid β (Aβ) released from amyloid precursor protein (APP) by β (BACE1) and γ (presenilin 1) secretases . Platelets contain more than 95% of the circulating APP and implicate as a candidate biomarker for cognitive decline. Recombinant human erythropoietin (rHuEPO) is a standard therapy for anemia in CKD and also acts as a neuroprotective agent. The aim of the study is to determine the impact of rHuEPO therapy on platelet APP processing in CKD with Cognitive Dysfunction. A total of 60 subjects comprising of 30 CKD without cognitive dysfunction and 30 CKD with cognitive dysfunction based on neuropsychological assessment. APP, BACE1, Presenilin 1, ADAM 10 (α secretase) and Aβ expressions in platelets were determined by western blotting and lipid peroxidation (LPO) in platelet rich plasma (PRP) was done by spectrophotometrically. The parameters were statistically compared with Alzheimer's disease (AD), Normocytic normochromic anemic and healthy subjects. Significantly (p < 0.05) decreased APP, ADAM 10 while increased BACE1, Presenilin 1, Aβ and LPO were observed in CKD with cognitive dysfunction like AD subjects compared to other groups. The parameters were reassessed in CKD with cognitive dysfunction subjects after rHuEPO (100 IU/ kg, weekly twice, 6 months) therapy. All the parameters were retrieved significantly (p < 0.05) along with improved neuropsychological tests scoring after rHuEPO therapy. This study demonstrated that rHuEPO is an effective neuroprotective agent in the context of CKD associated cognitive dysfunction and proved its clinical usefulness. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Alternations of central insulin-like growth factor-1 sensitivity in APP/PS1 transgenic mice and neuronal models.

PubMed

Zhang, Bing; Tang, Xi Can; Zhang, Hai Yan

2013-05-01

Although many post-mortem studies have found evidence of central insulin resistance in Alzheimer's disease (AD) patients, results on changes of central insulin-like growth factor-1 (IGF-1) signaling in the pathological process of AD remain controversial. In the present study, we observed the activation states of IGF-1 downstream signaling in brain slices of transgenic mice carrying APPswe/PS1dE9 mutations (APP/PS1 mice) at both early and late stages (ex vivo) and further investigated the involvement of oligomeric β-amyloid (Aβ) and Aβ-enriched culture medium (CM) on IGF-1 sensitivity employing neuronal models (in vitro). In 6- and 18-month-old APP/PS1 mice, the phosphorylations of IGF-1 receptor (IGF-1R) and Akt in response to IGF-1 stimulation were significantly reduced in the hippocampal and cortical slices, whereas IGF-1R protein expression and mRNA levels of IGF-1 and IGF-1R in the hippocampal slices were significantly higher than that in wild-type mice. In agreement with these results, reduced IGF-1 sensitivity was verified in APP and PS1 double stably transfected CHO cells; moreover, IGF-1 stimulated phosphorylations of IGF-1R and Akt were also markedly weakened by oligomeric Aβ or Aβ-enriched CM posttreatment in CHO cells without APP/PS1-transfected (K1 cells) and primary hippocampal neurons. These observations indicate that the impaired central IGF-1 sensitivity at early and late stages of APP/PS1 transgenic mice might be attributable, at least partially, to the overproduced Aβ, especially the oligomeric Aβ. These findings may shed new light on the mechanisms underlying the defective IGF-1 signaling in AD pathogenesis and provide important clues for AD drug discovery. Copyright © 2013 Wiley Periodicals, Inc.

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

PubMed

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.

Absorption and fluorescence spectroscopic characterization of BLUF domain of AppA from Rhodobacter sphaeroides

NASA Astrophysics Data System (ADS)

Zirak, P.; Penzkofer, A.; Schiereis, T.; Hegemann, P.; Jung, A.; Schlichting, I.

2005-08-01

The BLUF domain of the transcriptional anti-repressor protein AppA from the non-sulfur anoxyphototrophic purple bacterium Rhodobacter sphaeroides was characterized by absorption and emission spectroscopy. The BLUF domain constructs AppA 148 (consisting of amino-acid residues 1-148) and AppA 126 (amino-acid residues 1-126) are investigated. The cofactor of the investigated domains is found to consist of a mixture of the flavins riboflavin, FMN, and FAD. The dark-adapted domains exist in two different active receptor conformations (receptor states) with different sub-nanosecond fluorescence lifetimes (BLUF r,f and BLUF r,sl) and a small non-interacting conformation (BLUF nc). The active receptor conformations are transformed to putative signalling states (BLUF s,f and BLUF s,sl) of low fluorescence efficiency and picosecond fluorescence lifetime by blue-light excitation (light-adapted domains). In the dark at room temperature both signalling states recover back to the initial receptor states with a time constant of about 17 min. A quantum yield of signalling state formation of about 25% was determined by intensity dependent transmission measurements. A photo-cycle scheme is presented including photo-induced charge transfer complex formation, charge recombination, and protein binding pocket reorganisation.

HMGCS2 promotes autophagic degradation of the amyloid-β precursor protein through ketone body-mediated mechanisms.

PubMed

Hu, Li-Tian; Zhu, Bing-Lin; Lai, Yu-Jie; Long, Yan; Zha, Jing-Si; Hu, Xiao-Tong; Zhang, John H; Chen, Guo-Jun

2017-04-29

HMGCS2 (mitochondrial 3-hydroxy-3-methylglutaryl-COA synthase 2) is a control enzyme in ketogenesis. The mitochondrial localization and interaction with APP (β-amyloid precursor protein) suggest that HMGCS2 may play a role in the pathophysiology of AD (Alzheimer's disease). Here we report that overexpression of HMGCS2 decreased levels of APP and related CTFs (carboxy-terminal fragments), which was largely prevented by an autophagic inhibitor chloroquine. In addition, HMGCS2 enhancement of autophagic marker LC3II was diminished by rapamycin, an inhibitor of mechanistic target of rapamycin. Moreover, deprivation of EBSS (Earle's Balanced Salt Solution) significantly augmented the effect of HMGCS2 on LC3II, while acetoacetate reversed the reduction of LC3II, APP and CTFs which was induced by HMGCS2 knockdown. In the presence of acetoacetate, rapamycin failed to induce further increase of LC3II, which mimicked the effect of HMGCS2 overexpression. Finally, HMGCS2 enhanced the antioxidant response. Collectively, HMGCS2 shares with ketone bodies common features in autophagic clearance of APP and CTFs, suggesting that ketone bodies play an important role in HMGCS2 regulation of the autophagy. Copyright © 2017 Elsevier Inc. All rights reserved.

Regional distribution of synaptic markers and APP correlate with distinct clinicopathological features in sporadic and familial Alzheimer’s disease

PubMed Central

Shinohara, Mitsuru; Fujioka, Shinsuke; Murray, Melissa E.; Wojtas, Aleksandra; Baker, Matthew; Rovelet-Lecrux, Anne; Rademakers, Rosa; Das, Pritam; Parisi, Joseph E.; Graff-Radford, Neill R.; Petersen, Ronald C.; Dickson, Dennis W.

2014-01-01

Recent studies suggest that subcortical structures, including striatum, are vulnerable to amyloid-β accumulation and other neuropathological features in familial Alzheimer’s disease due to autosomal dominant mutations. We explored differences between familial and sporadic Alzheimer’s disease that might shed light on their respective pathogenic mechanisms. To this end, we analysed 12 brain regions, including neocortical, limbic and subcortical areas, from post-mortem brains of familial Alzheimer’s disease (n = 10; age at death: 50.0 ± 8.6 years) with mutations in amyloid precursor protein (APP) or presenilin 1 (PSEN1), sporadic Alzheimer’s disease (n = 19; age at death: 84.7 ± 7.8 years), neurologically normal elderly without amyloid-β accumulation (normal ageing; n = 13, age at death: 82.9 ± 10.8 years) and neurologically normal elderly with extensive cortical amyloid-β deposits (pathological ageing; n = 15; age at death: 92.7 ± 5.9 years). The levels of amyloid-β40, amyloid-β42, APP, apolipoprotein E, the synaptic marker PSD95 (now known as DLG4), the astrocyte marker GFAP, other molecules related to amyloid-β metabolism, and tau were determined by enzyme-linked immunosorbent assays. We observed that familial Alzheimer’s disease had disproportionate amyloid-β42 accumulation in subcortical areas compared with sporadic Alzheimer’s disease, whereas sporadic Alzheimer’s disease had disproportionate amyloid-β42 accumulation in cortical areas compared to familial Alzheimer’s disease. Compared with normal ageing, the levels of several proteins involved in amyloid-β metabolism were significantly altered in both sporadic and familial Alzheimer’s disease; however, such changes were not present in pathological ageing. Among molecules related to amyloid-β metabolism, the regional distribution of PSD95 strongly correlated with the regional pattern of amyloid-β42 accumulation in sporadic Alzheimer’s disease and pathological ageing, whereas the regional distribution of APP as well as β-C-terminal fragment of APP were strongly associated with the regional pattern of amyloid-β42 accumulation in familial Alzheimer’s disease. Apolipoprotein E and GFAP showed negative regional association with amyloid-β (especially amyloid-β40) accumulation in both sporadic and familial Alzheimer’s disease. Familial Alzheimer’s disease had greater striatal tau pathology than sporadic Alzheimer’s disease. In a retrospective medical record review, atypical signs and symptoms were more frequent in familial Alzheimer’s disease compared with sporadic Alzheimer’s disease. These results suggest that disproportionate amyloid-β42 accumulation in cortical areas in sporadic Alzheimer’s disease may be mediated by synaptic processes, whereas disproportionate amyloid-β42 accumulation in subcortical areas in familial Alzheimer’s disease may be driven by APP and its processing. Region-specific amyloid-β42 accumulation might account for differences in the relative amounts of tau pathology and clinical symptoms in familial and sporadic Alzheimer’s disease. PMID:24625695

Induced lung inflammation and dietary protein supply affect nitrogen retention and amino acid metabolism in growing pigs.

PubMed

Kampman-van de Hoek, Esther; Sakkas, Panagiotis; Gerrits, Walter J J; van den Borne, Joost J G C; van der Peet-Schwering, Carola M C; Jansman, Alfons J M

2015-02-14

It is hypothesised that during immune system activation, there is a competition for amino acids (AA) between body protein deposition and immune system functioning. The aim of the present study was to quantify the effect of immune system activation on N retention and AA metabolism in growing pigs, depending on dietary protein supply. A total of sixteen barrows received an adequate (Ad) or restricted (Res) amount of dietary protein, and were challenged at day 0 with intravenous complete Freund's adjuvant (CFA). At days - 5, 3 and 8, an irreversible loss rate (ILR) of eight AA was determined. CFA successfully activated the immune system, as indicated by a 2- to 4-fold increase in serum concentrations of acute-phase proteins (APP). Pre-challenge C-reactive protein concentrations were lower (P< 0·05) and pre- and post-challenge albumin tended to be lower in Res-pigs. These findings indicate that a restricted protein supply can limit the acute-phase response. CFA increased urinary N losses (P= 0·04) and tended to reduce N retention in Ad-pigs, but not in Res-pigs (P= 0·07). The ILR for Val was lower (P= 0·05) at day 8 than at day 3 in the post-challenge period. The ILR of most AA, except for Trp, were strongly affected by dietary protein supply and positively correlated with N retention. The correlations between the ILR and APP indices were absent or negative, indicating that changes in AA utilisation for APP synthesis were either not substantial or more likely outweighed by a decrease in muscle protein synthesis during immune system activation in growing pigs.

Cleavage of amyloid precursor protein by an archaeal presenilin homologue PSH

PubMed Central

Dang, Shangyu; Wu, Shenjie; Wang, Jiawei; Li, Hongbo; Huang, Min; He, Wei; Li, Yue-Ming; Wong, Catherine C. L.; Shi, Yigong

2015-01-01

Aberrant cleavage of amyloid precursor protein (APP) by γ-secretase contributes to the development of Alzheimer’s disease. More than 200 disease-derived mutations have been identified in presenilin (the catalytic subunit of γ-secretase), making modulation of γ-secretase activity a potentially attractive therapeutic opportunity. Unfortunately, the technical challenges in dealing with intact γ-secretase have hindered discovery of modulators and demand a convenient substitute approach. Here we report that, similar to γ-secretase, the archaeal presenilin homolog PSH faithfully processes the substrate APP C99 into Aβ42, Aβ40, and Aβ38. The molar ratio of the cleavage products Aβ42 over Aβ40 by PSH is nearly identical to that by γ-secretase. The proteolytic activity of PSH is specifically suppressed by presenilin-specific inhibitors. Known modulators of γ-secretase also modulate PSH similarly in terms of the Aβ42/Aβ40 ratio. Structural analysis reveals association of a known γ-secretase inhibitor with PSH between its two catalytic aspartate residues. These findings identify PSH as a surrogate protease for the screening of agents that may regulate the protease activity and the cleavage preference of γ-secretase. PMID:25733893

The development of Drink Less: an alcohol reduction smartphone app for excessive drinkers.

PubMed

Garnett, Claire; Crane, David; West, Robert; Brown, Jamie; Michie, Susan

2018-05-04

Excessive alcohol consumption poses a serious problem for public health. Digital behavior change interventions have the potential to help users reduce their drinking. In accordance with Open Science principles, this paper describes the development of a smartphone app to help individuals who drink excessively to reduce their alcohol consumption. Following the UK Medical Research Council's guidance and the Multiphase Optimization Strategy, development consisted of two phases: (i) selection of intervention components and (ii) design and development work to implement the chosen components into modules to be evaluated further for inclusion in the app. Phase 1 involved a scoping literature review, expert consensus study and content analysis of existing alcohol apps. Findings were integrated within a broad model of behavior change (Capability, Opportunity, Motivation-Behavior). Phase 2 involved a highly iterative process and used the "Person-Based" approach to promote engagement. From Phase 1, five intervention components were selected: (i) Normative Feedback, (ii) Cognitive Bias Re-training, (iii) Self-monitoring and Feedback, (iv) Action Planning, and (v) Identity Change. Phase 2 indicated that each of these components presented different challenges for implementation as app modules; all required multiple iterations and design changes to arrive at versions that would be suitable for inclusion in a subsequent evaluation study. The development of the Drink Less app involved a thorough process of component identification with a scoping literature review, expert consensus, and review of other apps. Translation of the components into app modules required a highly iterative process involving user testing and design modification.

Optimization of protein solution by a novel experimental design method using thermodynamic properties.

PubMed

Kim, Nam Ah; An, In Bok; Lee, Sang Yeol; Park, Eun-Seok; Jeong, Seong Hoon

2012-09-01

In this study, the structural stability of hen egg white lysozyme in solution at various pH levels and in different types of buffers, including acetate, phosphate, histidine, and Tris, was investigated by means of differential scanning calorimetry (DSC). Reasonable pH values were selected from the buffer ranges and were analyzed statistically through design of experiment (DoE). Four factors were used to characterize the thermograms: calorimetric enthalpy (ΔH), temperature at maximum heat flux (T( m )), van't Hoff enthalpy (ΔH( V )), and apparent activation energy of protein solution (E(app)). It was possible to calculate E(app) through mathematical elaboration from the Lumry-Eyring model by changing the scan rate. The transition temperature of protein solution, T( m ), increased when the scan rate was faster. When comparing the T( m ), ΔH( V ), ΔH, and E(app) of lysozyme in various pH ranges and buffers with different priorities, lysozyme in acetate buffer at pH 4.767 (scenario 9) to pH 4.969 (scenario 11) exhibited the highest thermodynamic stability. Through this experiment, we found a significant difference in the thermal stability of lysozyme in various pH ranges and buffers and also a new approach to investigate the physical stability of protein by DoE.

Epigenetic Regulation of Axonal Growth of Drosophila Pacemaker Cells by Histone Acetyltransferase Tip60 Controls Sleep

PubMed Central

Pirooznia, Sheila K.; Chiu, Kellie; Chan, May T.; Zimmerman, John E.; Elefant, Felice

2012-01-01

Tip60 is a histone acetyltransferase (HAT) enzyme that epigenetically regulates genes enriched for neuronal functions through interaction with the amyloid precursor protein (APP) intracellular domain. However, whether Tip60-mediated epigenetic dysregulation affects specific neuronal processes in vivo and contributes to neurodegeneration remains unclear. Here, we show that Tip60 HAT activity mediates axonal growth of the Drosophila pacemaker cells, termed “small ventrolateral neurons” (sLNvs), and their production of the neuropeptide pigment-dispersing factor (PDF) that functions to stabilize Drosophila sleep–wake cycles. Using genetic approaches, we show that loss of Tip60 HAT activity in the presence of the Alzheimer’s disease-associated APP affects PDF expression and causes retraction of the sLNv synaptic arbor required for presynaptic release of PDF. Functional consequence of these effects is evidenced by disruption of the sleep–wake cycle in these flies. Notably, overexpression of Tip60 in conjunction with APP rescues these sleep–wake disturbances by inducing overelaboration of the sLNv synaptic terminals and increasing PDF levels, supporting a neuroprotective role for dTip60 in sLNv growth and function under APP-induced neurodegenerative conditions. Our findings reveal a novel mechanism for Tip60 mediated sleep–wake regulation via control of axonal growth and PDF levels within the sLNv-encompassing neural network and provide insight into epigenetic-based regulation of sleep disturbances observed in neurodegenerative diseases like Alzheimer’s disease. PMID:22982579

Development and Mechanism of γ-Secretase Modulators for Alzheimer Disease

PubMed Central

Crump, Christina J.; Johnson, Douglas S.; Li, Yue-Ming

2013-01-01

γ-Secretase is an aspartyl intramembranal protease composed of presenilin, Nicastrin, Aph1 and Pen2 with 19 transmembrane domains. γ-Secretase cleaves the amyloid precursor proteins (APP) to release Aβ peptides that likely play a causative role in the pathogenesis of Alzheimer disease (AD). In addition, γ-secretase cleaves Notch and other type I membrane proteins. γ-Secretase inhibitors (GSIs) have been developed and used for clinical studies. However, clinical trials have shown adverse effects of GSIs that are potentially linked with non-discriminatory inhibition of Notch signaling, overall APP processing and other substrate cleavages. Therefore, these findings call for the development of disease modifying agents that target γ-secretase activity to lower Aβ42 production without blocking the overall processing of γ-secretase substrates. γ-Secretase modulators (GSMs) originally derived from non-steroidal anti-inflammatory drugs (NSAIDs) display such characteristics and are the focus of this review. However, first generation GSMs have limited potential due to low potency and undesired neuropharmacokinetic properties. This generation of GSMs has been suggested to interact with the APP substrate, γ-secretase or both. To improve the potency and brain availability, second generation GSMs including NSAID-derived carboxylic acid and non-NSAID-derived heterocyclic chemotypes as well as natural product-derived GSMs have been developed. Animal studies of this generation of GSMs have shown encouraging preclinical profiles. Moreover, using potent GSM photoaffinity probes, multiple studies unambiguously have showed that both carboxylic acid and heterocyclic GSMs specifically target presenilin, the catalytic subunit of γ-secretase. In addition, two types of GSMs have distinct binding sites within the γ-secretase complex and exhibit different Aβ profiles. GSMs induce a conformational change of γ-secretase to achieve modulation. Various models are proposed and discussed. Despite the progress of GSM research, many outstanding issues remain to be investigated to achieve the ultimate goal of developing GSMs as effective AD therapies. PMID:23614767

Regulation of neuronal APL-1 expression by cholesterol starvation.

PubMed

Wiese, Mary; Antebi, Adam; Zheng, Hui

2012-01-01

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the deposition of β-amyloid plaques composed primarily of the amyloid-β peptide, a cleavage product of amyloid precursor protein (APP). While mutations in APP lead to the development of Familial Alzheimer's Disease (FAD), sporadic AD has only one clear genetic modifier: the ε4 allele of the apolipoprotein E (ApoE) gene. Cholesterol starvation in Caenorhabditis elegans leads to molting and arrest phenotypes similar to loss-of-function mutants of the APP ortholog, apl-1 (amyloid precursor-like protein 1), and lrp-1 (lipoprotein receptor-related protein 1), suggesting a potential interaction between apl-1 and cholesterol metabolism. Previously, we found that RNAi knock-down of apl-1 leads to aldicarb hypersensitivity, indicating a defect in synaptic function. Here we find the same defect is recapitulated during lrp-1 knock-down and by cholesterol starvation. A cholesterol-free diet or loss of lrp-1 directly affects APL-1 levels as both lead to loss of APL-1::GFP fluorescence in neurons. However, loss of cholesterol does not affect global transcription or protein levels as seen by qPCR and Western blot. Our results show that cholesterol and lrp-1 are involved in the regulation of synaptic transmission, similar to apl-1. Both are able to modulate APL-1 protein levels in neurons, however cholesterol changes do not affect global apl-1 transcription or APL-1 protein indicating the changes are specific to neurons. Thus, regulation of synaptic transmission and molting by LRP-1 and cholesterol may be mediated by their ability to control APL-1 neuronal protein expression.

The Long Way From Government Open Data to Mobile Health Apps: Overcoming Institutional Barriers in the US Federal Government

PubMed Central

2014-01-01

Background Government agencies in the United States are creating mobile health (mHealth) apps as part of recent policy changes initiated by the White House’s Digital Government Strategy. Objective The objective of the study was to understand the institutional and managerial barriers for the implementation of mHealth, as well as the resulting adoption pathways of mHealth. Methods This article is based on insights derived from qualitative interview data with 35 public managers in charge of promoting the reuse of open data through Challenge.gov, the platform created to run prizes, challenges, and the vetting and implementation of the winning and vendor-created apps. Results The process of designing apps follows three different pathways: (1) entrepreneurs start to see opportunities for mobile apps, and develop either in-house or contract out to already vetted Web design vendors; (2) a top-down policy mandates agencies to adopt at least two customer-facing mobile apps; and (3) the federal government uses a policy instrument called “Prizes and Challenges”, encouraging civic hackers to design health-related mobile apps using open government data from HealthData.gov, in combination with citizen needs. All pathways of the development process incur a set of major obstacles that have to be actively managed before agencies can promote mobile apps on their websites and app stores. Conclusions Beyond the cultural paradigm shift to design interactive apps and to open health-related data to the public, the managerial challenges include accessibility, interoperability, security, privacy, and legal concerns using interactive apps tracking citizen. PMID:25537314

The Long Way From Government Open Data to Mobile Health Apps: Overcoming Institutional Barriers in the US Federal Government.

PubMed

Mergel, Ines

2014-12-23

Government agencies in the United States are creating mobile health (mHealth) apps as part of recent policy changes initiated by the White House's Digital Government Strategy. The objective of the study was to understand the institutional and managerial barriers for the implementation of mHealth, as well as the resulting adoption pathways of mHealth. This article is based on insights derived from qualitative interview data with 35 public managers in charge of promoting the reuse of open data through Challenge.gov, the platform created to run prizes, challenges, and the vetting and implementation of the winning and vendor-created apps. The process of designing apps follows three different pathways: (1) entrepreneurs start to see opportunities for mobile apps, and develop either in-house or contract out to already vetted Web design vendors; (2) a top-down policy mandates agencies to adopt at least two customer-facing mobile apps; and (3) the federal government uses a policy instrument called "Prizes and Challenges", encouraging civic hackers to design health-related mobile apps using open government data from HealthData.gov, in combination with citizen needs. All pathways of the development process incur a set of major obstacles that have to be actively managed before agencies can promote mobile apps on their websites and app stores. Beyond the cultural paradigm shift to design interactive apps and to open health-related data to the public, the managerial challenges include accessibility, interoperability, security, privacy, and legal concerns using interactive apps tracking citizen.

Privacy as Part of the App Decision-Making Process

DTIC Science & Technology

2013-02-06

concerns they may not actively consider privacy while downloading apps from smartphone application marketplaces. Currently Android users have only the... Android permissions display which appears after they have selected an app to download to help them understand how applications access their information...marketplaces. Currently, Android users have only the Android permissions display, which appears after they have selected an app to download, to help

RanBP9 at the intersection between cofilin and Aβ pathologies: rescue of neurodegenerative changes by RanBP9 reduction.

PubMed

Woo, J A; Boggess, T; Uhlar, C; Wang, X; Khan, H; Cappos, G; Joly-Amado, A; De Narvaez, E; Majid, S; Minamide, L S; Bamburg, J R; Morgan, D; Weeber, E; Kang, D E

2015-03-05

Molecular pathways underlying the neurotoxicity and production of amyloid β protein (Aβ) represent potentially promising therapeutic targets for Alzheimer's disease (AD). We recently found that overexpression of the scaffolding protein RanBP9 increases Aβ production in cell lines and in transgenic mice while promoting cofilin activation and mitochondrial dysfunction. Translocation of cofilin to mitochondria and induction of cofilin-actin pathology require the activation/dephosphorylation of cofilin by Slingshot homolog 1 (SSH1) and cysteine oxidation of cofilin. In this study, we found that endogenous RanBP9 positively regulates SSH1 levels and mediates Aβ-induced translocation of cofilin to mitochondria and induction of cofilin-actin pathology in cultured cells, primary neurons, and in vivo. Endogenous level of RanBP9 was also required for Aβ-induced collapse of growth cones in immature neurons (days in vitro 9 (DIV9)) and depletion of synaptic proteins in mature neurons (DIV21). In vivo, amyloid precursor protein (APP)/presenilin-1 (PS1) mice exhibited 3.5-fold increased RanBP9 levels, and RanBP9 reduction protected against cofilin-actin pathology, synaptic damage, gliosis, and Aβ accumulation associated with APP/PS1 mice. Brains slices derived from APP/PS1 mice showed significantly impaired long-term potentiation (LTP), and RanBP9 reduction significantly enhanced paired pulse facilitation and LTP, as well as partially rescued contextual memory deficits associated with APP/PS1 mice. Therefore, these results underscore the critical importance of endogenous RanBP9 not only in Aβ accumulation but also in mediating the neurotoxic actions of Aβ at the level of synaptic plasticity, mitochondria, and cofilin-actin pathology via control of the SSH1-cofilin pathway in vivo.

Deletion of the γ-secretase subunits Aph1B/C impairs memory and worsens the deficits of knock-in mice modeling the Alzheimer-like familial Danish dementia

PubMed Central

Biundo, Fabrizio; Ishiwari, Keita; Del Prete, Dolores; D'Adamio, Luciano

2016-01-01

Mutations in BRI2/ITM2b genes cause Familial British and Danish Dementias (FBD and FDD), which are pathogenically similar to Familial Alzheimer Disease (FAD). BRI2 inhibits processing of Amyloid precursor protein (APP), a protein involved in FAD pathogenesis. Accumulation of a carboxyl-terminal APP metabolite –β-CTF- causes memory deficits in a knock-in mouse model of FDD, called FDDKI. We have investigated further the pathogenic function of β-CTF studying the effect of Aph1B/C deletion on FDDKI mice. This strategy is based on the evidence that deletion of Aph1B/C proteins, which are components of the γ-secretase that cleaves β-CTF, results in stabilization of β-CTF and a reduction of Aβ. We found that both the FDD mutation and the Aph1B/C deficiency mildly interfered with spatial long term memory, spatial working/short-term memory and long-term contextual fear memory. In addition, the Aph1BC deficiency induced deficits in long-term cued fear memory. Moreover, the two mutations have additive adverse effects as they compromise the accuracy of spatial long-term memory and induce spatial memory retention deficits in young mice. Overall, the data are consistent with a role for β-CTF in the genesis of memory deficits. PMID:26942869

Deletion of the γ-secretase subunits Aph1B/C impairs memory and worsens the deficits of knock-in mice modeling the Alzheimer-like familial Danish dementia.

PubMed

Biundo, Fabrizio; Ishiwari, Keita; Del Prete, Dolores; D'Adamio, Luciano

2016-03-15

Mutations in BRI2/ITM2b genes cause Familial British and Danish Dementias (FBD and FDD), which are pathogenically similar to Familial Alzheimer Disease (FAD). BRI2 inhibits processing of Amyloid precursor protein (APP), a protein involved in FAD pathogenesis. Accumulation of a carboxyl-terminal APP metabolite -ß-CTF- causes memory deficits in a knock-in mouse model of FDD, called FDDKI.We have investigated further the pathogenic function of ß-CTF studying the effect of Aph1B/C deletion on FDDKI mice. This strategy is based on the evidence that deletion of Aph1B/C proteins, which are components of the γ-secretase that cleaves ß-CTF, results in stabilization of ß-CTF and a reduction of Aβ. We found that both the FDD mutation and the Aph1B/C deficiency mildly interfered with spatial long term memory, spatial working/short-term memory and long-term contextual fear memory. In addition, the Aph1BC deficiency induced deficits in long-term cued fear memory. Moreover, the two mutations have additive adverse effects as they compromise the accuracy of spatial long-term memory and induce spatial memory retention deficits in young mice. Overall, the data are consistent with a role for β-CTF in the genesis of memory deficits.

Discoveries in Down syndrome: moving basic science to clinical care.

PubMed

Kleschevnikov, A M; Belichenko, P V; Salehi, A; Wu, C

2012-01-01

This review describes recent discoveries in neurobiology of Down syndrome (DS) achieved with use of mouse genetic models and provides an overview of experimental approaches aimed at development of pharmacological restoration of cognitive function in people with this developmental disorder. Changes in structure and function of synaptic connections within the hippocampal formation of DS model mice, as well as alterations in innervations of the hippocampus by noradrenergic and cholinergic neuromodulatory systems, provided important clues for potential pharmacological treatments of cognitive disabilities in DS. Possible molecular and cellular mechanisms underlying this genetic disorder have been addressed. We discuss novel mechanisms engaging misprocessing of amyloid precursor protein (App) and other proteins, through their affect on axonal transport and endosomal dysfunction, to "Alzheimer-type" neurodegenerative processes that affect cognition later in life. In conclusion, a number of therapeutic strategies have been defined that may restore cognitive function in mouse models of DS. In the juvenile and young animals, these strategists focus on restoration of synaptic plasticity, rate of adult neurogenesis, and functions of the neuromodulatory subcortical systems. Later in life, the major focus is on recuperation of misprocessed App and related proteins. It is hoped that the identification of an increasing number of potential targets for pharmacotherapy of cognitive deficits in DS will add to the momentum for creating and completing clinical trials. Copyright © 2012 Elsevier B.V. All rights reserved.

Systemic acute phase proteins response in calves experimentally infected with Eimeria zuernii.

PubMed

Lassen, Brian; Bangoura, Berit; Lepik, Triin; Orro, Toomas

2015-09-15

Acute phase proteins (APPs) have been demonstrated to be useful in evaluating general health stress and diseases in cattle. Serum amyloid A (SAA) and haptoglobin (Hp) are APPs that are produced during inflammation, and likely play a role in host immunological defence against Eimeria infection and the associated intestinal tissue damage. We investigated the involvement of SAA and HP in an experimental study, including three groups of calves: a control group (group 0, n=11), and two groups infected with either 150,000 or 250,000 Eimeria zuernii oocysts (group 1 (n=11) and group 2 (n=12), respectively). The calves were monitored for 28 days and data was collected on oocyst excretion, faecal score, animal weight, and SAA and Hp serum concentrations. Generalized linear mixed models showed that the clinical symptoms, indicated by an increase in the number of oocysts in the faeces and severe diarrhoea, manifested at patency for group 1 and 2. Serum Hp and SAA levels also increased during this period. Hp appeared to be a more sensitive marker than SAA, and differences between groups 1 and 2 were observed only for Hp. Linear regression models showed a negative association between weight gain and Hp concentrations, calculated as the area under the curve (AUC) during the overall experimental period and the patency period. A similar result was seen for SAA only during the patency period. This result supports the assumption that reduced weight gain due to E. zuernii infection is an immunologically driven process that involves an increase in APPs. A random intercept regression model of oocyst shedding groups showed that calves shedding 1-500 oocysts had reduced concentrations of Hp, indicating that a different immunological reaction occurs during mild shedding of E. zuernii oocysts than during more intensive shedding. A similar model was used to examine associations between faecal scores and Hp concentrations for each group. Group 2 calves with haemorrhagic diarrhoea displayed higher Hp levels than calves in that group with lower faecal scores, which may be in response to an increased demand for Hp in the repair process as a result of haemolysis. APPs seem to play an important role in determining the course of E. zuernii infection in calves, which may enhance our understanding of the immunological reaction and development of this disease. Copyright © 2015 Elsevier B.V. All rights reserved.

BeWell24: development and process evaluation of a smartphone "app" to improve sleep, sedentary, and active behaviors in US Veterans with increased metabolic risk.

PubMed

Buman, Matthew P; Epstein, Dana R; Gutierrez, Monica; Herb, Christine; Hollingshead, Kevin; Huberty, Jennifer L; Hekler, Eric B; Vega-López, Sonia; Ohri-Vachaspati, Punam; Hekler, Andrea C; Baldwin, Carol M

2016-09-01

Lifestyle behaviors across the 24-h spectrum (i.e., sleep, sedentary, and active behaviors) drive metabolic risk. We describe the development and process evaluation of BeWell24, a multicomponent smartphone application (or "app") that targets behavior change in these interdependent behaviors. A community-embedded iterative design framework was used to develop the app. An 8-week multiphase optimization strategy design study was used to test the initial efficacy of the sleep, sedentary, and exercise components of the app. Process evaluation outcomes included objectively measured app usage statistics (e.g., minutes of usage, self-monitoring patterns), user experience interviews, and satisfaction ratings. Participants (N = 26) logged approximately 60 % of their sleep, sedentary, and exercise behaviors, which took 3-4 min/day to complete. Usage of the sleep and sedentary components peaked at week 2 and remained high throughout the intervention. Exercise component use was low. User experiences were mixed, and overall satisfaction was modest.

Galactose-1-phosphate uridyltransferase (GalT), an in vivo-induced antigen of Actinobacillus pleuropneumoniae serovar 5b strain L20, provided immunoprotection against serovar 1 strain MS71.

PubMed

Zhang, Fei; Zhao, Qin; Quan, Keji; Zhu, Zhuang; Yang, Yusheng; Wen, Xintian; Chang, Yung-Fu; Huang, Xiaobo; Wu, Rui; Wen, Yiping; Yan, Qigui; Huang, Yong; Ma, Xiaoping; Han, Xinfeng; Cao, Sanjie

2018-01-01

GALT is an important antigen of Actinobacillus pleuropneumoniae (APP), which was shown to provide partial protection against APP infection in a previous study in our lab. The main purpose of the present study is to investigate GALT induced cross-protection between different APP serotypes and elucidate key mechanisms of the immune response to GALT antigenic stimulation. Bioinformatic analysis demonstrated that galT is a highly conserved gene in APP, widely distributed across multiple pathogenic strains. Homologies between any two strains ranges from 78.9% to 100% regarding the galT locus. Indirect enzyme-linked immunosorbent assay (ELISA) confirmed that GALT specific antibodies could not be induced by inactivated APP L20 or MS71 whole cell bacterin preparations. A recombinant fusion GALT protein derived from APP L20, however has proven to be an effective cross-protective antigen against APP sevorar 1 MS71 (50%, 4/8) and APP sevorar 5b L20 (75%, 6/8). Histopathological examinations have confirmed that recombinant GALT vaccinated animals showed less severe pathological signs in lung tissues than negative controls after APP challenge. Immunohistochemical (IHC) analysis indicated that the infiltration of neutrophils in the negative group is significantly increased compared with that in the normal control (P<0.001) and that in surviving animals is decreased compared to the negative group. Anti-GALT antibodies were shown to mediate phagocytosis of neutrophils. After interaction with anti-GALT antibodies, survival rate of APP challenged vaccinated animals was significantly reduced (P<0.001). This study demonstrated that GALT is an effective cross-protective antigen, which could be used as a potential vaccine candidate against multiple APP serotypes.

The Ames dwarf mutation attenuates Alzheimer's disease phenotype of APP/PS1 mice.

PubMed

Puig, Kendra L; Kulas, Joshua A; Franklin, Whitney; Rakoczy, Sharlene G; Taglialatela, Giulio; Brown-Borg, Holly M; Combs, Colin K

2016-04-01

APP/PS1 double transgenic mice expressing human mutant amyloid precursor protein (APP) and presenilin-1 (PS1) demonstrate robust brain amyloid beta (Aβ) peptide containing plaque deposition, increased markers of oxidative stress, behavioral dysfunction, and proinflammatory gliosis. On the other hand, lack of growth hormone, prolactin, and thyroid-stimulating hormone due to a recessive mutation in the Prop 1 gene (Prop1df) in Ames dwarf mice results in a phenotype characterized by potentiated antioxidant mechanisms, improved learning and memory, and significantly increased longevity in homozygous mice. Based on this, we hypothesized that a similar hormone deficiency might attenuate disease changes in the brains of APP/PS1 mice. To test this idea, APP/PS1 mice were crossed to the Ames dwarf mouse line. APP/PS1, wild-type, df/+, df/df, df/+/APP/PS1, and df/df/APP/PS1 mice were compared at 6 months of age through behavioral testing and assessing amyloid burden, reactive gliosis, and brain cytokine levels. df/df mice demonstrated lower brain growth hormone and insulin-like growth factor 1 concentrations. This correlated with decreased astrogliosis and microgliosis in the df/df/APP/PS1 mice and, surprisingly, reduced Aβ plaque deposition and Aβ 1-40 and Aβ 1-42 concentrations. The df/df/APP/PS1 mice also demonstrated significantly elevated brain levels of multiple cytokines in spite of the attenuated gliosis. These data indicate that the df/df/APP/PS1 line is a unique resource in which to study aging and resistance to disease and suggest that the affected pituitary hormones may have a role in regulating disease progression. Copyright © 2016 Elsevier Inc. All rights reserved.

The Development of the Recovery Assessments by Phone Points (RAPP): A Mobile Phone App for Postoperative Recovery Monitoring and Assessment.

PubMed

Jaensson, Maria; Dahlberg, Karuna; Eriksson, Mats; Grönlund, Åke; Nilsson, Ulrica

2015-09-11

In Sweden, day surgery is performed in almost 2 million patients per year. Patient satisfaction is closely related to potential adverse events during the recovery process. A way to empower patients and give them the opportunity to affect care delivery is to let them evaluate their recovery process. The most common evaluation method is a follow-up telephone call by a nurse one or two days after surgery. In recent years, mHealth apps have been used to evaluate the nurse-patient relationship for self-management in chronic diseases or to evaluate pain after surgery. To the best of our knowledge, no previous research has explored the recovery process after day surgery via mobile phone in a Swedish cohort. The objective of the study is to describe the process of developing a mobile phone app using a Swedish Web-based Quality of Recovery (SwQoR) questionnaire to evaluate postoperative recovery after day surgery. The development process included five steps: (1) setting up an interdisciplinary task force, (2) evaluating the potential needs of app users, (3) developing the Swedish Web version of a QoR questionnaire, (4) constructing a mobile phone app, and (5) evaluating the interface and design by staff working in a day-surgery department and patients undergoing day surgery. A task force including specialists in information and communication technology, eHealth, and nursing care worked closely together to develop a Web-based app. Modifications to the QoR questionnaire were inspired by instruments used in the field of recovery for both children and adults. The Web-based app, Recovery Assessment by Phone Points (RAPP) consists of two parts: (1) a mobile app installed on the patient's private mobile phone, and (2) an administrator interface for the researchers. The final version of the SwQoR questionnaire, which includes 31 items, was successfully installed in RAPP. The interface and the design were evaluated by asking for user opinions about the design and usefulness of the app with 10 day surgery patients. Some minor adjustments were made concerning text size and screen color. Taking advantage of joint expertise, a useable Web-based app adaptable to different technical platforms was constructed. In addition, the SwQoR was successfully transferred into digital format for use on mobile phones.

Anti-amyloid precursor protein antibodies inhibit amyloid-β production by steric hindrance

PubMed Central

Thomas, Rhian S.; Liddell, J. Eryl; Kidd, Emma J.

2015-01-01

Summary Cleavage of amyloid precursor protein (APP) by β- and γ-secretases results in the production of amyloid-β (Aβ) in Alzheimer’s disease (AD). We raised two monoclonal antibodies, 2B3 and 2B12, that recognise the β-secretase cleavage site on APP but not Aβ. We hypothesised that these antibodies would reduce Aβ levels via steric hindrance of β-secretase. Both antibodies decreased extracellular Aβ levels from astrocytoma cells, but 2B3 was more potent than 2B12. Levels of soluble sAPPα from the non-amyloidogenic α-secretase pathway and intracellular APP were not affected by either antibody nor were there any effects on cell viability. 2B3 exhibited a higher affinity for APP than 2B12 and its epitope appeared to span the cleavage site while 2B12 bound slightly upstream. Both of these factors probably contribute to its greater effect on Aβ levels. After 60 minutes incubation at pH 4.0, most 2B3 and 2B12 remained bound to their antigen, suggesting that the antibodies will remain bound to APP in the acidic endosomes where β-secretase cleavage probably occurs. Only 2B3 and 2B12, but not control antibodies, inhibited the cleavage of sAPPα by β-secretase in a cell-free assay where effects of antibody internalisation and intracellular degradation were excluded. 2B3 virtually abolished this cleavage. In addition, levels of C-terminal APP fragments, βCTF, generated following β-secretase cleavage, were significantly reduced in cells after incubation with 2B3. These results strongly suggest that anti-cleavage site antibodies can generically reduce Aβ levels via inhibition of β-secretase by steric hindrance and may provide a novel alternative therapy for AD. PMID:21122073

Hydrophobic and superhydrophobic surfaces fabricated using atmospheric pressure cold plasma technology: A review.

PubMed

Dimitrakellis, Panagiotis; Gogolides, Evangelos

2018-04-01

Hydrophobic surfaces are often used to reduce wetting of surfaces by water. In particular, superhydrophobic surfaces are highly desired for several applications due to their exceptional properties such as self-cleaning, anti-icing, anti-friction and others. Such surfaces can be prepared via numerous methods including plasma technology, a dry technique with low environmental impact. Atmospheric pressure plasma (APP) has recently attracted significant attention as lower-cost alternative to low-pressure plasmas, and as a candidate for continuous rather than batch processing. Although there are many reviews on water-repellent surfaces, and a few reviews on APP technology, there are hardly any review works on APP processing for hydrophobic and superhydrohobic surface fabrication, a topic of high importance in nanotechnology and interface science. Herein, we critically review the advances on hydrophobic and superhydrophobic surface fabrication using APP technology, trying also to give some perspectives in the field. After a short introduction to superhydrophobicity of nanostructured surfaces and to APPs we focus this review on three different aspects: (1) The atmospheric plasma reactor technology used for fabrication of (super)hydrophobic surfaces. (2) The APP process for hydrophobic surface preparation. The hydrophobic surface preparation processes are categorized methodologically as: a) activation, b) grafting, c) polymerization, d) roughening and hydrophobization. Each category includes subcategories related to different precursors used. (3) One of the most important sections of this review concerns superhydrophobic surfaces fabricated using APP. These are methodologically characterized as follows: a) single step processes where micro-nano textured topography and low surface energy coating are created at the same time, or b) multiple step processes, where these steps occur sequentially in or out of the plasma. We end the review with some perspectives in the field. We aspire to address scientists, who will get involved in the fields of (super)hydrophobicity and/or in atmospheric pressure plasma processing. Copyright © 2018 Elsevier B.V. All rights reserved.

Cerebrolysin modulates pronerve growth factor/nerve growth factor ratio and ameliorates the cholinergic deficit in a transgenic model of Alzheimer's disease.

PubMed

Ubhi, Kiren; Rockenstein, Edward; Vazquez-Roque, Ruben; Mante, Michael; Inglis, Chandra; Patrick, Christina; Adame, Anthony; Fahnestock, Margaret; Doppler, Edith; Novak, Philip; Moessler, Herbert; Masliah, Eliezer

2013-02-01

Alzheimer's disease (AD) is characterized by degeneration of neocortex, limbic system, and basal forebrain, accompanied by accumulation of amyloid-β and tangle formation. Cerebrolysin (CBL), a peptide mixture with neurotrophic-like effects, is reported to improve cognition and activities of daily living in patients with AD. Likewise, CBL reduces synaptic and behavioral deficits in transgenic (tg) mice overexpressing the human amyloid precursor protein (hAPP). The neuroprotective effects of CBL may involve multiple mechanisms, including signaling regulation, control of APP metabolism, and expression of neurotrophic factors. We investigate the effects of CBL in the hAPP tg model of AD on levels of neurotrophic factors, including pro-nerve growth factor (NGF), NGF, brain-derived neurotrophic factor (BDNF), neurotropin (NT)-3, NT4, and ciliary neurotrophic factor (CNTF). Immunoblot analysis demonstrated that levels of pro-NGF were increased in saline-treated hAPP tg mice. In contrast, CBL-treated hAPP tg mice showed levels of pro-NGF comparable to control and increased levels of mature NGF. Consistently with these results, immunohistochemical analysis demonstrated increased NGF immunoreactivity in the hippocampus of CBL-treated hAPP tg mice. Protein levels of other neurotrophic factors, including BDNF, NT3, NT4, and CNTF, were unchanged. mRNA levels of NGF and other neurotrophins were also unchanged. Analysis of neurotrophin receptors showed preservation of the levels of TrKA and p75(NTR) immunoreactivity per cell in the nucleus basalis. Cholinergic cells in the nucleus basalis were reduced in the saline-treated hAPP tg mice, and treatment with CBL reduced these cholinergic deficits. These results suggest that the neurotrophic effects of CBL might involve modulation of the pro-NGF/NGF balance and a concomitant protection of cholinergic neurons. Copyright © 2012 Wiley Periodicals, Inc.

Moving Phones Tick Slower: Creating an Android App to Demonstrate Time Dilation

NASA Astrophysics Data System (ADS)

Underwood, Bret; Zhai, Yunxiao

2016-05-01

Smartphones and tablets are packed with sensors that allow us to take experimental data, essentially making them mobile physics labs. Apps exist that make it easy to capture and analyze data from these sensors, allowing users to study diverse phenomena such as free fall acceleration, the speed of sound, radioactivity, and many others. Commonly, the use of apps in the physics classroom focuses on existing apps rather than on the creation of apps themselves. This is for a good reason-writing an app usually requires advanced knowledge of programming languages and experience with app design. These skills are generally regarded as beyond the typical physics student. However, there are app development environments, such as MIT App Inventor 2 for Android, which make the process of creating an app and utilizing the sensors much more accessible to students. Putting the ability to create and configure apps within the reach of students can also help integrate computation into the curriculum. In this article, we discuss our creation of an Android app, Time Dilation Calculator, done as part of a senior undergraduate capstone project, which uses App Inventor and a mobile device's global positioning system (GPS) receiver to calculate the time dilation effect of special relativity.

The use of Facebook and WhatsApp application in learning process of physics to train students’ critical thinking skills

NASA Astrophysics Data System (ADS)

Kustijono, R.; Zuhri, F.

2018-01-01

The purpose of this research is to describe the learning process by using Facebook and WhatsApp to train students’ critical thinking skills. The research steps are: 1) analysis; 2) design; 3) development; 4) implementation; 5) evaluation. The research subjects are 40 students of Physics Department of Universitas Negeri Surabaya. This research used descriptive qualitative approach. The study The validation point, practicality, effectiveness, and critical thinking skills of students assessment use Likert scale. Learning process criteria are eligible if ≥ 60% is rated good or excellent. The results are: 1) the use of Facebook and WhatsApp can be implemented in the learning process, and the existing constraints can be overcome; 2) the assessment of students’ critical thinking skills is categorized as good and excellent. These results suggest that learning by using Facebook and WhatsApp can be used to train students’ critical thinking skills.

Label-free Quantitative Proteomics of Mouse Cerebrospinal Fluid Detects β-Site APP Cleaving Enzyme (BACE1) Protease Substrates In Vivo*

PubMed Central

Dislich, Bastian; Wohlrab, Felix; Bachhuber, Teresa; Müller, Stephan A.; Kuhn, Peer-Hendrik; Hogl, Sebastian; Meyer-Luehmann, Melanie; Lichtenthaler, Stefan F.

2015-01-01

Analysis of murine cerebrospinal fluid (CSF) by quantitative mass spectrometry is challenging because of low CSF volume, low total protein concentration, and the presence of highly abundant proteins such as albumin. We demonstrate that the CSF proteome of individual mice can be analyzed in a quantitative manner to a depth of several hundred proteins in a robust and simple workflow consisting of single ultra HPLC runs on a benchtop mass spectrometer. The workflow is validated by a comparative analysis of BACE1−/− and wild-type mice using label-free quantification. The protease BACE1 cleaves the amyloid precursor protein (APP) as well as several other substrates and is a major drug target in Alzheimer's disease. We identified a total of 715 proteins with at least 2 unique peptides and quantified 522 of those proteins in CSF from BACE1−/− and wild-type mice. Several proteins, including the known BACE1 substrates APP, APLP1, CHL1 and contactin-2 showed lower abundance in the CSF of BACE1−/− mice, demonstrating that BACE1 substrate identification is possible from CSF. Additionally, ectonucleotide pyrophosphatase 5 was identified as a novel BACE1 substrate and validated in cells using immunoblots and by an in vitro BACE1 protease assay. Likewise, receptor-type tyrosine-protein phosphatase N2 and plexin domain-containing 2 were confirmed as BACE1 substrates by in vitro assays. Taken together, our study shows the deepest characterization of the mouse CSF proteome to date and the first quantitative analysis of the CSF proteome of individual mice. The BACE1 substrates identified in CSF may serve as biomarkers to monitor BACE1 activity in Alzheimer patients treated with BACE inhibitors. PMID:26139848

The PpaA/AerR regulators of photosynthesis gene expression from anoxygenic phototrophic proteobacteria contain heme-binding SCHIC domains.

PubMed

Moskvin, Oleg V; Gilles-Gonzalez, Marie-Alda; Gomelsky, Mark

2010-10-01

The SCHIC domain of the B12-binding domain family present in the Rhodobacter sphaeroides AppA protein binds heme and senses oxygen. Here we show that the predicted SCHIC domain PpaA/AerR regulators also bind heme and respond to oxygen in vitro, despite their low sequence identity with AppA.

Cerebrospinal Fluid Biomarker and Brain Biopsy Findings in Idiopathic Normal Pressure Hydrocephalus

PubMed Central

Pyykkö, Okko T.; Lumela, Miikka; Rummukainen, Jaana; Nerg, Ossi; Seppälä, Toni T.; Herukka, Sanna-Kaisa; Koivisto, Anne M.; Alafuzoff, Irina; Puli, Lakshman; Savolainen, Sakari; Soininen, Hilkka; Jääskeläinen, Juha E.; Hiltunen, Mikko; Zetterberg, Henrik; Leinonen, Ville

2014-01-01

Background The significance of amyloid precursor protein (APP) and neuroinflammation in idiopathic normal pressure hydrocephalus (iNPH) and Alzheimer's disease (AD) is unknown. Objective To investigate the role of soluble APP (sAPP) and amyloid beta (Aβ) isoforms, proinflammatory cytokines, and biomarkers of neuronal damage in the cerebrospinal fluid (CSF) in relation to brain biopsy Aβ and hyperphosphorylated tau (HPτ) findings. Methods The study population comprised 102 patients with possible NPH with cortical brain biopsies, ventricular and lumbar CSF samples, and DNA available. The final clinical diagnoses were: 53 iNPH (91% shunt-responders), 26 AD (10 mixed iNPH+AD), and 23 others. Biopsy samples were immunostained against Aβ and HPτ. CSF levels of AD-related biomarkers (Aβ42, p-tau, total tau), non-AD-related Aβ isoforms (Aβ38, Aβ40), sAPP isoforms (sAPPα, sAPPβ), proinflammatory cytokines (several interleukins (IL), interferon-gamma, monocyte chemoattractant protein-1, tumor necrosis factor-alpha) and biomarkers of neuronal damage (neurofilament light and myelin basic protein) were measured. All patients were genotyped for APOE. Results Lumbar CSF levels of sAPPα were lower (p<0.05) in patients with shunt-responsive iNPH compared to non-iNPH patients. sAPPβ showed a similar trend (p = 0.06). CSF sAPP isoform levels showed no association to Aβ or HPτ in the brain biopsy. Quantified Aβ load in the brain biopsy showed a negative correlation with CSF levels of Aβ42 in ventricular (r = −0.295, p = 0.003) and lumbar (r = −0.356, p = 0.01) samples, while the levels of Aβ38 and Aβ40 showed no correlation. CSF levels of proinflammatory cytokines and biomarkers of neuronal damage did not associate to the brain biopsy findings, diagnosis, or shunt response. Higher lumbar/ventricular CSF IL-8 ratios (p<0.001) were seen in lumbar samples collected after ventriculostomy compared to the samples collected before the procedure. Conclusions The role of sAPP isoforms in iNPH seems to be independent from the amyloid cascade. No neuroinflammatory background was observed in iNPH or AD. PMID:24638077

Fe65 is required for Tip60-directed histone H4 acetylation at DNA strand breaks

PubMed Central

Stante, Maria; Minopoli, Giuseppina; Passaro, Fabiana; Raia, Maddalena; Vecchio, Luigi Del; Russo, Tommaso

2009-01-01

Fe65 is a binding partner of the Alzheimer's β-amyloid precursor protein APP. The possible involvement of this protein in the cellular response to DNA damage was suggested by the observation that Fe65 null mice are more sensitive to genotoxic stress than WT counterpart. Fe65 associated with chromatin under basal conditions and its involvement in DNA damage repair requires this association. A known partner of Fe65 is the histone acetyltransferase Tip60. Considering the crucial role of Tip60 in DNA repair, we explored the hypothesis that the phenotype of Fe65 null cells depended on its interaction with Tip60. We demonstrated that Fe65 knockdown impaired recruitment of Tip60-TRRAP complex to DNA double strand breaks and decreased histone H4 acetylation. Accordingly, the efficiency of DNA repair was decreased upon Fe65 suppression. To explore whether APP has a role in this mechanism, we analyzed a Fe65 mutant unable to bind to APP. This mutant failed to rescue the phenotypes of Fe65 null cells; furthermore, APP/APLP2 suppression results in the impairment of recruitment of Tip60-TRRAP complex to DNA double strand breaks, decreased histone H4 acetylation and repair efficiency. On these bases, we propose that Fe65 and its interaction with APP play an important role in the response to DNA damage by assisting the recruitment of Tip60-TRRAP to DNA damage sites. PMID:19282473

Constitutive α- and β-secretase cleavages of the amyloid precursor protein are partially coupled in neurons, but not in frequently used cell lines.

PubMed

Colombo, Alessio; Wang, Huanhuan; Kuhn, Peer-Hendrik; Page, Richard; Kremmer, Elisabeth; Dempsey, Peter J; Crawford, Howard C; Lichtenthaler, Stefan F

2013-01-01

Proteolytic cleavage of the amyloid precursor protein (APP) by the two proteases α- and β-secretases controls the generation of the amyloid β peptide (Aβ), a key player in Alzheimer's disease pathogenesis. The α-secretase ADAM10 and the β-secretase BACE1 have opposite effects on Aβ generation and are assumed to compete for APP as a substrate, such that their cleavages are inversely coupled. This concept was mainly demonstrated in studies using activation or overexpression of α- and β-secretases. Here, we report that this inverse coupling is not seen to the same extent upon inhibition of the endogenous proteases. Genetic and pharmacological inhibition of ADAM10 and BACE1 revealed that the endogenous, constitutive α-secretase cleavage of APP is largely uncoupled from β-secretase cleavage and Aβ generation in neuroglioma H4 cells and in neuronally differentiated SH-SY5Y cells. In contrast, inverse coupling was observed in primary cortical neurons. However, this coupling was not bidirectional. Inhibition of BACE1 increased ADAM10 cleavage of APP, but a reduction of ADAM10 activity did not increase the BACE1 cleavage of APP in the neurons. Our analysis shows that the inverse coupling of the endogenous α- and β-secretase cleavages depends on the cellular model and suggests that a reduction of ADAM10 activity is unlikely to increase the AD risk through increased β-secretase cleavage. Copyright © 2012 Elsevier Inc. All rights reserved.

Systematic and Iterative Development of a Smartphone App to Promote Sun-Protection Among Holidaymakers: Design of a Prototype and Results of Usability and Acceptability Testing

PubMed Central

Sniehotta, Falko F; Birch-Machin, Mark A; Olivier, Patrick; Araújo-Soares, Vera

2017-01-01

Background Sunburn and intermittent exposure to ultraviolet rays are risk factors for melanoma. Sunburn is a common experience during holidays, making tourism settings of particular interest for skin cancer prevention. Holidaymakers are a volatile populations found at different locations, which may make them difficult to reach. Given the widespread use of smartphones, evidence suggests that this might be a novel, convenient, scalable, and feasible way of reaching the target population. Objective The main objective of this study was to describe and appraise the process of systematically developing a smartphone intervention (mISkin app) to promote sun-protection during holidays. Methods The iterative development process of the mISkin app was conducted over four sequential stages: (1) identify evidence on the most effective behavior change techniques (BCTs) used (active ingredients) as well as theoretical predictors and theories, (2) evidence-based intervention design, (3) co-design with users of the mISkin app prototype, and (4) refinement of the app. Each stage provided key findings that were subsequently used to inform the design of the mISkin app. Results The sequential approach to development integrates different strands of evidence to inform the design of an evidence-based intervention. A systematic review on previously tested interventions to promote sun-protection provided cues and constraints for the design of this intervention. The development and design of the mISkin app also incorporated other sources of information, such as other literature reviews and experts’ consultations. The developed prototype of the mISkin app was evaluated by engaging potential holidaymakers in the refinement and further development of the mISkin app through usability (ease-of-use) and acceptability testing of the intervention prototype. All 17 participants were satisfied with the mISkin prototype and expressed willingness to use it. Feedback on the app was integrated in the optimization process of the mISkin app. Conclusions The mISkin app was designed to promote sun-protection among holidaymakers and was based on current evidence, experts’ knowledge and experience, and user involvement. Based on user feedback, the app has been refined and a fully functional version is ready for formal testing in a feasibility pilot study. PMID:28606892

Genomic Footprints in Selected and Unselected Beef Cattle Breeds in Korea.

PubMed

Lim, Dajeong; Strucken, Eva M; Choi, Bong Hwan; Chai, Han Ha; Cho, Yong Min; Jang, Gul Won; Kim, Tae-Hun; Gondro, Cedric; Lee, Seung Hwan

2016-01-01

Korean Hanwoo cattle have been subjected to intensive artificial selection over the past four decades to improve meat production traits. Another three cattle varieties very closely related to Hanwoo reside in Korea (Jeju Black and Brindle) and in China (Yanbian). These breeds have not been part of a breeding scheme to improve production traits. Here, we compare the selected Hanwoo against these similar but presumed to be unselected populations to identify genomic regions that have been under recent selection pressure due to the breeding program. Rsb statistics were used to contrast the genomes of Hanwoo versus a pooled sample of the three unselected population (UN). We identified 37 significant SNPs (FDR corrected) in the HW/UN comparison and 21 known protein coding genes were within 1 MB to the identified SNPs. These genes were previously reported to affect traits important for meat production (14 genes), reproduction including mammary gland development (3 genes), coat color (2 genes), and genes affecting behavioral traits in a broader sense (2 genes). We subsequently sequenced (Illumina HiSeq 2000 platform) 10 individuals of the brown Hanwoo and the Chinese Yanbian to identify SNPs within the candidate genomic regions. Based on allele frequency differences, haplotype structures, and literature research, we singled out one non-synonymous SNP in the APP gene (APP: c.569C>T, Ala199Val) and predicted the mutational effect on the protein structure. We found that protein-protein interactions might be impaired due to increased exposed hydrophobic surfaces of the mutated protein. The APP gene has also been reported to affect meat tenderness in pigs and obesity in humans. Meat tenderness has been linked to intramuscular fat content, which is one of the main breeding goals for brown Hanwoo, potentially supporting a causal influence of the herein described nsSNP in the APP gene.

A Standards-Based Architecture Proposal for Integrating Patient mHealth Apps to Electronic Health Record Systems.

PubMed

Marceglia, S; Fontelo, P; Rossi, E; Ackerman, M J

2015-01-01

Mobile health Applications (mHealth Apps) are opening the way to patients' responsible and active involvement with their own healthcare management. However, apart from Apps allowing patient's access to their electronic health records (EHRs), mHealth Apps are currently developed as dedicated "island systems". Although much work has been done on patient's access to EHRs, transfer of information from mHealth Apps to EHR systems is still low. This study proposes a standards-based architecture that can be adopted by mHealth Apps to exchange information with EHRs to support better quality of care. Following the definition of requirements for the EHR/mHealth App information exchange recently proposed, and after reviewing current standards, we designed the architecture for EHR/mHealth App integration. Then, as a case study, we modeled a system based on the proposed architecture aimed to support home monitoring for congestive heart failure patients. We simulated such process using, on the EHR side, OpenMRS, an open source longitudinal EHR and, on the mHealth App side, the iOS platform. The integration architecture was based on the bi-directional exchange of standard documents (clinical document architecture rel2 - CDA2). In the process, the clinician "prescribes" the home monitoring procedures by creating a CDA2 prescription in the EHR that is sent, encrypted and de-identified, to the mHealth App to create the monitoring calendar. At the scheduled time, the App alerts the patient to start the monitoring. After the measurements are done, the App generates a structured CDA2-compliant monitoring report and sends it to the EHR, thus avoiding local storage. The proposed architecture, even if validated only in a simulation environment, represents a step forward in the integration of personal mHealth Apps into the larger health-IT ecosystem, allowing the bi-directional data exchange between patients and healthcare professionals, supporting the patient's engagement in self-management and self-care.

Cerebral amyloid angiopathy increases susceptibility to infarction after focal cerebral ischemia in Tg2576 mice.

PubMed

Milner, Eric; Zhou, Meng-Liang; Johnson, Andrew W; Vellimana, Ananth K; Greenberg, Jacob K; Holtzman, David M; Han, Byung Hee; Zipfel, Gregory J

2014-10-01

We and others have shown that soluble amyloid β-peptide (Aβ) and cerebral amyloid angiopathy (CAA) cause significant cerebrovascular dysfunction in mutant amyloid precursor protein (APP) mice, and that these deficits are greater in aged APP mice having CAA compared with young APP mice lacking CAA. Amyloid β-peptide in young APP mice also increases infarction after focal cerebral ischemia, but the impact of CAA on ischemic brain injury is unknown. To determine this, we assessed cerebrovascular reactivity, cerebral blood flow (CBF), and extent of infarction and neurological deficits after transient middle cerebral artery occlusion in aged APP mice having extensive CAA versus young APP mice lacking CAA (and aged-matched littermate controls). We found that aged APP mice have more severe cerebrovascular dysfunction that is CAA dependent, have greater CBF compromise during and immediately after middle cerebral artery occlusion, and develop larger infarctions after middle cerebral artery occlusion. These data indicate CAA induces a more severe form of cerebrovascular dysfunction than amyloid β-peptide alone, leading to intra- and postischemic CBF deficits that ultimately exacerbate cerebral infarction. Our results shed mechanistic light on human studies identifying CAA as an independent risk factor for ischemic brain injury. © 2014 American Heart Association, Inc.

The systemic iron-regulatory proteins hepcidin and ferroportin are reduced in the brain in Alzheimer’s disease

PubMed Central

2013-01-01

Background The pathological features of the common neurodegenerative conditions, Alzheimer’s disease (AD), Parkinson’s disease and multiple sclerosis are all known to be associated with iron dysregulation in regions of the brain where the specific pathology is most highly expressed. Iron accumulates in cortical plaques and neurofibrillary tangles in AD where it participates in redox cycling and causes oxidative damage to neurons. To understand these abnormalities in the distribution of iron the expression of proteins that maintain systemic iron balance was investigated in human AD brains and in the APP-transgenic (APP-tg) mouse. Results Protein levels of hepcidin, the iron-homeostatic peptide, and ferroportin, the iron exporter, were significantly reduced in hippocampal lysates from AD brains. By histochemistry, hepcidin and ferroportin were widely distributed in the normal human brain and co-localised in neurons and astrocytes suggesting a role in regulating iron release. In AD brains, hepcidin expression was reduced and restricted to the neuropil, blood vessels and damaged neurons. In the APP-tg mouse immunoreactivity for ferritin light-chain, the iron storage isoform, was initially distributed throughout the brain and as the disease progressed accumulated in the core of amyloid plaques. In human and mouse tissues, extensive AD pathology with amyloid plaques and severe vascular damage with loss of pericytes and endothelial disruption was seen. In AD brains, hepcidin and ferroportin were associated with haem-positive granular deposits in the region of damaged blood vessels. Conclusion Our results suggest that the reduction in ferroportin levels are likely associated with cerebral ischaemia, inflammation, the loss of neurons due to the well-characterised protein misfolding, senile plaque formation and possibly the ageing process itself. The reasons for the reduction in hepcidin levels are less clear but future investigation could examine circulating levels of the peptide in AD and a possible reduction in the passage of hepcidin across damaged vascular endothelium. Imbalance in the levels and distribution of ferritin light-chain further indicate a failure to utilize and release iron by damaged and degenerating neurons. PMID:24252754

Combining apps targeting professionals and senior citizens to improve housing accessibility and influence housing provision policies.

PubMed

Helle, Tina; Iwarsson, Susanne; Lunn, Tine Bieber; Iversen, Mogens Holm; Jonsson, Oskar; Mårtensson, Knut; Svarre, Tanja; Slaug, Björn

2015-01-01

Two separate apps that address the increasingly important issue of accessible housing for senior citizens have been developed in different project settings. One of the apps was developed to facilitate the process for professional raters to assess housing accessibility in the context of individual housing adaptations. The other app was developed for senior citizens to raise their awareness of possible accessibility problems in their current dwelling and in other apartments within the available housing stock. Both apps were developed with a high degree of active user involvement in processes utilizing multiple state of the art methods. The results are two well accepted prototype apps perceived as user-friendly and appropriate for the intended user groups. By combining these two apps, our ambition is for the professional raters to benefit by gaining knowledge of their clients' perceived needs and desires, and for senior citizens to benefit by getting access to a database of professionally rated dwellings. The ultimate goal is the generation of sound knowledge reflecting the needs and desires of senior citizens and professional requirements regarding accessible housing as a means to inform and influence housing provision policies.

Effect of flavonols on wine astringency and their interaction with human saliva.

PubMed

Ferrer-Gallego, Raúl; Brás, Natércia F; García-Estévez, Ignacio; Mateus, Nuno; Rivas-Gonzalo, Julián C; de Freitas, Victor; Escribano-Bailón, M Teresa

2016-10-15

The addition of external phenolic compounds to wines in order to improve their sensory quality is an established winemaking practice. This study was aimed at evaluating the effect of the addition of quercetin 3-O-glucoside on the astringency and bitterness of wines. Sensory results showed that the addition of this flavonol to wines results in an increase in astringency and bitterness. Additionally, flavonol-human salivary protein interactions were studied using fluorescence spectroscopy, dynamic light scattering and molecular dynamic simulations (MD). The apparent Stern-Volmer (KsvApp) and the apparent bimolecular quenching constants (kqApp) were calculated from fluorescence spectra. The KsvApp was 12620±390M(-1), and the apparent biomolecular constant was 3.94×10(12)M(-1)s(-1), which suggests that a complex was formed between the human salivary proteins and quercetin 3-O-glucoside. MD simulations showed that the quercetin 3-O-glucoside molecules have the ability to bind to the IB937 model peptide. Copyright © 2016 Elsevier Ltd. All rights reserved.

The amyloid precursor protein locus and very-late-onset Alzheimer disease.

PubMed

Olson, J M; Goddard, K A; Dudek, D M

2001-10-01

Although mutations in the amyloid-beta precursor protein (APP) gene are known to confer high risk of Alzheimer disease (AD) to a small percentage of families in which it has early onset, convincing evidence of a major role for the APP locus in late-onset AD has not been forthcoming. In this report, we have used a covariate-based affected-sib-pair linkage method to analyze the chromosome 21 clinical and genetic data obtained on affected sibships by the National Institute of Mental Health Alzheimer Disease Genetics Initiative. The baseline model (without covariates) gave a LOD score of 0.02, which increases to 1.43 when covariates representing the additive effects of E2 and E4 are added. Larger increases in LOD scores were found when age at last examination/death (LOD score 5.54; P=.000002) or age at onset plus disease duration (LOD score 5.63; P=.000006) were included in the linkage model. We conclude that the APP locus may predispose to AD in the very elderly.

Fe65 does not stabilize AICD during activation of transcription in a luciferase assay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huysseune, Sandra; Kienlen-Campard, Pascal; Octave, Jean-Noel

2007-09-21

The APP intracellular domain (AICD) could be involved in signaling via interaction with the adaptor protein Fe65, and with the histone acetyl transferase Tip60. However, the real function of AICD and Fe65 in regulation of transcription remains controversial. In this study, the human APPGal4 fusion protein was expressed in CHO cells and the transcriptional activity of AICDGal4 was measured in a luciferase-based reporter assay. AICDGal4 was stabilized by expression of Fe65 and levels of AICDGal4 controlled luciferase activity. On the contrary, when human APP was expressed in CHO cells, coexpression of Fe65 increased luciferase activity without affecting the amount ofmore » AICD fragment. AICD produced from APP was protected from degradation by orthophenanthroline, but not by lactacystine, indicating that AICD is not a substrate of the chymotryptic activity of the proteasome. It is concluded that Fe65 can control luciferase activity without stabilizing the labile AICD fragment.« less

Involvement of activated leukocytes in the regulation of plasma levels of acute phase proteins in microgravity simulation experiments

NASA Astrophysics Data System (ADS)

Larina, Olga; Bekker, Anna; Turin-Kuzmin, Alexey

2016-07-01

Earth-based studies of microgravity effects showed the induction of the mechanisms of acute phase reaction (APR). APR comprises the transition of stress-sensitive protein kinases of macrophages and other responsive cells into the active state and the phosphorylation of transcription factors which in turn stimulate the production of acute-phase reaction cytokines. Leukocyte activation is accompanied by the acceleration of the formation of oxygen radicals which can serve a functional indice of leukocyte cell state. The series of events at acute phase response result in selective changes in the synthesis of a number of secretory blood proteins (acute phase proteins, APPs) in liver cells thus contributing the recovery of homeostasis state in the organism. Earlier experiment with head-down tilt showed the increase in plasma concentrations of two cytokine mediators of acute phase response, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) being the outcome of the activation of producer cells, foremost, leukocytes. In experiment with 4-day dry immersion chemiluminescent (ChL) reply of the whole blood samples to a test stimulus were studied along with the measurements of plasma levels of APPs, namely, alpha1-antitrypsin (alpha1-AT), alpha1-acid glycoprotein (alpha1-AGP), alpha2-macroglobulin (alpha2-M), ceruloplasmin (Cer), haptoglobin (Hp), C3-complement component (C3), C-reactive protein (CRP). Eight individuals aged 21.2 ± 3.2 years were the test subjects in the investigation. Protein studies showed a noticeable increase in the mean plasma levels of all APPs measured in experiment thus producing the evidence of the activation of acute phase response mechanisms while individual patterns revealed variability during the immersion period. The overall trends were similar to these in the previous immersion series. The augment in the strength of signal in stimulated light emission tests was higher after 1- and 2-day of immersion exposure than before the experiment. The effects obtained in this survey suggest the enhancement of the synthesis of active oxygen species by blood phagocytes at the initial stages of adaptation to immersion conditions. The gain of chemiluminescence signal correlated with maximal augment in APP concentrations registered in the course of 4-day immersion. Moreover, in the only case with zero effects in chemiluminescent reply stable APP levels were obtained. The data from functional studies performed with phagocytic cells in the experiment with dry immersion corroborate their implication in acute phase mechanisms participating in the adaptation to simulated microgravity conditions.

Amyloid-clearing proteins and their epigenetic regulation as a therapeutic target in Alzheimer’s disease

PubMed Central

Nalivaeva, Natalia N.; Belyaev, Nikolai D.; Kerridge, Caroline; Turner, Anthony J.

2014-01-01

Abnormal elevation of amyloid β-peptide (Aβ) levels in the brain is the primary trigger for neuronal cell death specific to Alzheimer’s disease (AD). It is now evident that Aβ levels in the brain are manipulable due to a dynamic equilibrium between its production from the amyloid precursor protein (APP) and removal by amyloid clearance proteins. Clearance can be either enzymic or non-enzymic (binding/transport proteins). Intriguingly several of the main amyloid-degrading enzymes (ADEs) are members of the M13 peptidase family (neprilysin (NEP), NEP2 and the endothelin converting enzymes (ECE-1 and -2)). A distinct metallopeptidase, insulin-degrading enzyme (IDE), also contributes to Aβ degradation in the brain. The ADE family currently embraces more than 20 members, both membrane-bound and soluble, and of differing cellular locations. NEP plays an important role in brain function terminating neuropeptide signals. Its decrease in specific brain areas with age or after hypoxia, ischaemia or stroke contribute significantly to the development of AD pathology. The recently discovered mechanism of epigenetic regulation of NEP (and other genes) by the APP intracellular domain (AICD) and its dependence on the cell type and APP isoform expression suggest possibilities for selective manipulation of NEP gene expression in neuronal cells. We have also observed that another amyloid-clearing protein, namely transthyretin (TTR), is also regulated in the neuronal cell by a mechanism similar to NEP. Dependence of amyloid clearance proteins on histone deacetylases and the ability of HDAC inhibitors to up-regulate their expression in the brain opens new avenues for developing preventive strategies in AD. PMID:25278875

B cell cross-epitope of Propionibacterium acnes and Actinobacillus pleuropneumonia selected by phage display library can efficiently protect from Actinobacillus pleuropneumonia infection.

PubMed

Liu, Jianfang; Ma, Qiuyue; Yang, Feng; Zhu, Rining; Gu, Jingmin; Sun, Changjiang; Feng, Xin; Du, Chongtao; Langford, Paul R; Han, Wenyu; Yang, Junling; Lei, Liancheng

2017-06-01

Contagious porcine pleuropneumonia (CPP), caused by Actinobacillus pleuropneumoniae (APP), is a highly transmissible and fatal respiratory illness that causes tremendous economic losses for the pig breeding industry worldwide. Propionibacterium acnes (PA) has a strong cross-reaction with anti-APP1 and anti-APP5 serum and can efficiently prevent APP infection, which was fortuitously found in researching the differential gene between the different APP serotypes. There seems to be some natural cross-protection between PA and APP. To identify the common epitope, the phage display library of a PA whole genome was constructed, whose size is 10 5 . The DNA sequence of the positive clone was determined after three rounds of biopanning, and ten common protein types were identified and the epitope was predicted by computer software. Six peptide epitopes were selected and synthesized for further analysis. Among these epitopes, Ba1, Bb5 and C1 could bind to anti-PA serum and anti-APP1 serum and vice versa. Furthermore, the IgG and IL-4 levels and CD4 + /CD8 + T cell ratios in the Ba1, Bb5 and C1 groups were significantly higher than that in the control group, indicating that the epitopes could trigger an immune response, which was mainly humoral immunity. Moreover, Ba1 and Bb5 equally protected 80% of mice from a fatal dose of APP1 infection compared with the control group. Mice could resist APP1 and APP5 challenge after being treated with the combination of Ba1 and Bb5, with survival rates of 80% and 90%, respectively. These findings suggest that the PA epitope confers antigenicity and can heterologously resist to the APP infection. This finding provides a novel strategy for preventing APP infection. Copyright © 2017 Elsevier B.V. All rights reserved.

Role of P-glycoprotein in mediating rivastigmine effect on amyloid-β brain load and related pathology in Alzheimer’s disease mouse model

PubMed Central

Mohamed, Loqman A.; Keller, Jeffrey N.; Kaddoumi, Amal

2016-01-01

Recently, we showed that rivastigmine decreased amyloid-β (Aβ) brain load in aged rats by enhancing its clearance across the blood-brain barrier (BBB) via upregulation of P-glycoprotein (P-gp) and low-density lipoprotein receptor-related protein 1 (LRP1). Here, we extend our previous work to clarify P-gp role in mediating rivastigmine effect on Aβ brain levels and neuroprotection in a mouse model of Alzheimer’s disease (AD) that expresses different levels of P-gp. APPSWE mice were bred with mdr1a/b knockout mice to produce littermates that were divided into three groups; APP+/mdr1+/+, APP+/mdr1+/− and APP+/mdr1−/−. Animals received rivastigmine treatment (0.3 mg/kg/day) or vehicle for 8 weeks using Alzet osmotic mini-pumps. ELISA analysis of brain homogenates for Aβ showed rivastigmine treatment to significantly decrease Aβ brain load in APP+/mdr1+/+ by 25% and in APP+/mdr1+/− mice by 21% compared to their vehicle treated littermates, but not in APP+/mdr1−/− mice. In addition, rivastigmine reduced GFAP immunostaining of astrocytes by 50% and IL-1β brain level by 43% in APP+/mdr1+/+ mice, however its effect was less pronounced in P-gp knockout mice. Moreover, rivastigmine demonstrated a P-gp expression dependent neuroprotective effect that was highest in APP+/mdr1+/+>APP+/mdr1+/−>APP+/mdr1−/− as determined by expression of synaptic markers PSD-95 and SNAP-25 using Western blot analysis. Collectively, our results suggest that P-gp plays important role in mediating rivastigmine non-cholinergic beneficial effects, including Aβ brain load reduction, neuroprotective and anti-inflammatory effects in the AD mouse models. PMID:26780497

An intronic ncRNA-dependent regulation of SORL1 expression affecting Aβ formation is upregulated in post-mortem Alzheimer's disease brain samples.

PubMed

Ciarlo, Eleonora; Massone, Sara; Penna, Ilaria; Nizzari, Mario; Gigoni, Arianna; Dieci, Giorgio; Russo, Claudio; Florio, Tullio; Cancedda, Ranieri; Pagano, Aldo

2013-03-01

Recent studies indicated that sortilin-related receptor 1 (SORL1) is a risk gene for late-onset Alzheimer's disease (AD), although its role in the aetiology and/or progression of this disorder is not fully understood. Here, we report the finding of a non-coding (nc) RNA (hereafter referred to as 51A) that maps in antisense configuration to intron 1 of the SORL1 gene. 51A expression drives a splicing shift of SORL1 from the synthesis of the canonical long protein variant A to an alternatively spliced protein form. This process, resulting in a decreased synthesis of SORL1 variant A, is associated with impaired processing of amyloid precursor protein (APP), leading to increased Aβ formation. Interestingly, we found that 51A is expressed in human brains, being frequently upregulated in cerebral cortices from individuals with Alzheimer's disease. Altogether, these findings document a novel ncRNA-dependent regulatory pathway that might have relevant implications in neurodegeneration.

Structural Characterization of the E2 Domain of APL-1, a C. Elegans Homolog of Human Amyloid Precursor Protein, and its Heparin Binding Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoopes, J.; Liu, X; Xu, X

2010-01-01

The amyloid {beta}-peptide deposit found in the brain tissue of patients with Alzheimer disease is derived from a large heparin-binding protein precursor APP. The biological function of APP and its homologs is not precisely known. Here we report the x-ray structure of the E2 domain of APL-1, an APP homolog in Caenorhabditis elegans, and compare it to the human APP structure. We also describe the structure of APL-1 E2 in complex with sucrose octasulfate, a highly negatively charged disaccharide, which reveals an unexpected binding pocket between the two halves of E2. Based on the crystal structure, we are able tomore » map, using site-directed mutagenesis, a surface groove on E2 to which heparin may bind. Our biochemical data also indicate that the affinity of E2 for heparin is influenced by pH: at pH 5, the binding appears to be much stronger than that at neutral pH. This property is likely caused by histidine residues in the vicinity of the mapped heparin binding site and could be important for the proposed adhesive function of APL-1.« less

Substance P and Alzheimer's Disease: Emerging Novel Roles.

PubMed

Severini, Cinzia; Petrella, Carla; Calissano, Pietro

2016-01-01

Alzheimer`s disease (AD) is an irreversible neurodegenerative disease, clinically characterized by progressive impairments of memory and cognition. The hallmarks of AD are neurofibrillary tangles, mainly constituted by altered phosphorylated and truncated portions of tau protein, and the abnormal extracellular deposition of neurotoxic beta amyloid (Aβ) peptides, derived from the proteolytic processing of amyloid precursor protein (APP). According to the amyloid hypothesis, Aβ is considered to be linked to the selective neurodegeneration seen in AD. Recent evidence points to an increase in voltage-gated potassium (Kv) channel currents in the etiology of Aβ-induced neuronal apoptosis. Substance P (SP) is an 11-aa neuropeptide, member of the tachykinin family, broadly distributed in the Central Nervous System where it acts as a neurotransmitter, neuromodulator, and neurotrophic factor. This peptide may play an important role in neurodegenerative disorders, since reduced levels of SP were found in brain areas and spinal fluid of AD patients. In addition to its neuroprotective properties, it was recently demonstrated that SP is able to stimulate non-amyloidogenic APP processing, thereby reducing the possibility of generation of toxic Aβ peptides in the brain. Recent studies, using in vitro and in vivo models, have also shown that the neuroprotective role of SP against Aβ could be related to its ability of modulate Kv channel currents. In this review, we briefly summarized the current findings on the neurotrophic and neuroprotective effects of SP, providing information about its anti-amyloidogenic and anti-Aβ toxicity role.

NDM29, a RNA polymerase III-dependent non coding RNA, promotes amyloidogenic processing of APP and amyloid β secretion.

PubMed

Massone, Sara; Ciarlo, Eleonora; Vella, Serena; Nizzari, Mario; Florio, Tullio; Russo, Claudio; Cancedda, Ranieri; Pagano, Aldo

2012-07-01

Neuroblastoma Differentiation Marker 29 (NDM29) is a RNA polymerase (pol) III-transcribed non-coding (nc) RNA whose synthesis drives neuroblastoma (NB) cell differentiation to a nonmalignant neuron-like phenotype. Since in this process a complex pattern of molecular changes is associated to plasma membrane protein repertoire we hypothesized that the expression of NDM29 might influence also key players of neurodegenerative pathways. In this work we show that the NDM29-dependent cell maturation induces amyloid precursor protein (APP) synthesis, leading to the increase of amyloid β peptide (Aβ) secretion and the concomitant increment of Aβ x-42/Aβ x-40 ratio. We also demonstrate that the expression of NDM29 RNA, and the consequent increase of Aβ formation, can be promoted by inflammatory stimuli (and repressed by anti-inflammatory drugs). Moreover, NDM29 expression was detected in normal human brains although an abnormal increased synthesis of this ncRNA is induced in patients affected by neurodegenerative diseases. Therefore, the complex of events triggered by NDM29 expression induces a condition that favors the formation of Aβ peptides in the extracellular space, as it may occur in Alzheimer's Disease (AD). In addition, these data unexpectedly show that a pol III-dependent small RNA can act as key regulator of brain physiology and/or pathology suggesting that a better knowledge of this portion of the human transcriptome might provide hints for neurodegeneration studies. Copyright © 2012 Elsevier B.V. All rights reserved.

Effects of glutamine supplementation on gut barrier, glutathione content and acute phase response in malnourished rats during inflammatory shock.

PubMed

Belmonte, Liliana; Coëffier, Moïse; Le Pessot, Florence; Miralles-Barrachina, Olga; Hiron, Martine; Leplingard, Antony; Lemeland, Jean-François; Hecketsweiler, Bernadette; Daveau, Maryvonne; Ducrotté, Philippe; Déchelotte, Pierre

2007-05-28

To evaluate the effect of glutamine on intestinal mucosa integrity, glutathione stores and acute phase response in protein-depleted rats during an inflammatory shock. Plasma acute phase proteins (APP), jejunal APP mRNA levels, liver and jejunal glutathione concentrations were measured before and one, three and seven days after turpentine injection in 4 groups of control, protein-restricted, protein-restricted rats supplemented with glutamine or protein powder. Bacterial translocation in mesenteric lymph nodes and intestinal morphology were also assessed. Protein deprivation and turpentine injection significantly reduced jejunal villus height, and crypt depths. Mucosal glutathione concentration significantly decreased in protein-restricted rats. Before turpentine oil, glutamine supplementation restored villus heights and glutathione concentration (3.24 +/- 1.05 vs 1.72 +/- 0.46 mumol/g tissue, P<0.05) in the jejunum, whereas in the liver glutathione remained low. Glutamine markedly increased jejunal alpha1-acid glycoprotein mRNA level after turpentine oil but did not affect its plasma concentration. Bacterial translocation in protein-restricted rats was not prevented by glutamine or protein powder supplementation. Glutamine restored gut glutathione stores and villus heights in malnourished rats but had no preventive effect on bacterial translocation in our model.

Modulation of Gamma-Secretase for the Treatment of Alzheimer's Disease

PubMed Central

McKee, Timothy D.; Loureiro, Robyn M. B.; Dumin, Jo Ann; Xia, Weiming; Pojasek, Kevin; Austin, Wesley F.; Fuller, Nathan O.; Hubbs, Jed L.; Shen, Ruichao; Jonker, Jeff; Ives, Jeff; Bronk, Brian S.

2012-01-01

The Amyloid Hypothesis states that the cascade of events associated with Alzheimer's disease (AD)—formation of amyloid plaques, neurofibrillary tangles, synaptic loss, neurodegeneration, and cognitive decline—are triggered by Aβ peptide dysregulation (Kakuda et al., 2006, Sato et al., 2003, Qi-Takahara et al., 2005). Since γ-secretase is critical for Aβ production, many in the biopharmaceutical community focused on γ-secretase as a target for therapeutic approaches for Alzheimer's disease. However, pharmacological approaches to control γ-secretase activity are challenging because the enzyme has multiple, physiologically critical protein substrates. To lower amyloidogenic Aβ peptides without affecting other γ-secretase substrates, the epsilon (ε) cleavage that is essential for the activity of many substrates must be preserved. Small molecule modulators of γ-secretase activity have been discovered that spare the ε cleavage of APP and other substrates while decreasing the production of Aβ 42. Multiple chemical classes of γ-secretase modulators have been identified which differ in the pattern of Aβ peptides produced. Ideally, modulators will allow the ε cleavage of all substrates while shifting APP cleavage from Aβ 42 and other highly amyloidogenic Aβ peptides to shorter and less neurotoxic forms of the peptides without altering the total Aβ pool. Here, we compare chemically distinct modulators for effects on APP processing and in vivo activity. PMID:23320246

Rational heterodoxy: cholesterol reformation of the amyloid doctrine.

PubMed

Castello, Michael A; Soriano, Salvador

2013-01-01

According to the amyloid cascade hypothesis, accumulation of the amyloid peptide Aβ, derived by proteolytic processing from the amyloid precursor protein (APP), is the key pathogenic trigger in Alzheimer's disease (AD). This view has led researchers for more than two decades and continues to be the most influential model of neurodegeneration. Nevertheless, close scrutiny of the current evidence does not support a central pathogenic role for Aβ in late-onset AD. Furthermore, the amyloid cascade hypothesis lacks a theoretical foundation from which the physiological generation of Aβ can be understood, and therapeutic approaches based on its premises have failed. We present an alternative model of neurodegeneration, in which sustained cholesterol-associated neuronal distress is the most likely pathogenic trigger in late-onset AD, directly causing oxidative stress, inflammation and tau hyperphosphorylation. In this scenario, Aβ generation is part of an APP-driven adaptive response to the initial cholesterol distress, and its accumulation is neither central to, nor a requirement for, the initiation of the disease. Our model provides a theoretical framework that places APP as a regulator of cholesterol homeostasis, accounts for the generation of Aβ in both healthy and demented brains, and provides suitable targets for therapeutic intervention. Copyright © 2012 Elsevier B.V. All rights reserved.

Noggin and BMP4 co-modulate adult hippocampal neurogenesis in the APP{sub swe}/PS1{sub {Delta}E9} transgenic mouse model of Alzheimer's disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Jun; Department of Physiology, Third Military Medical University, Chongqing 400038; Song, Min

2009-07-31

In addition to the subventricular zone, the dentate gyrus of the hippocampus is one of the few brain regions in which neurogenesis continues into adulthood. Perturbation of neurogenesis can alter hippocampal function, and previous studies have shown that neurogenesis is dysregulated in Alzheimer disease (AD) brain. Bone morphogenetic protein-4 (BMP4) and its antagonist Noggin have been shown to play important roles both in embryonic development and in the adult nervous system, and may regulate hippocampal neurogenesis. Previous data indicated that increased expression of BMP4 mRNA within the dentate gyrus might contribute to decreased hippocampal cell proliferation in the APP{sub swe}/PS1{submore » {Delta}E9} mouse AD model. However, it is not known whether the BMP antagonist Noggin contributes to the regulation of neurogenesis. We therefore studied the relative expression levels and localization of BMP4 and its antagonist Noggin in the dentate gyrus and whether these correlated with changes in neurogenesis in 6-12 mo old APP{sub swe}/PS1{sub {Delta}E9} transgenic mice. Bromodeoxyuridine (BrdU) was used to label proliferative cells. We report that decreased neurogenesis in the APP/PS1 transgenic mice was accompanied by increased expression of BMP4 and decreased expression of Noggin at both the mRNA and protein levels; statistical analysis showed that the number of proliferative cells at different ages correlated positively with Noggin expression and negatively with BMP4 expression. Intraventricular administration of a chimeric Noggin/Fc protein was used to block the action of endogenous BMP4; this resulted in a significant increase in the number of BrdU-labeled cells in dentate gyrus subgranular zone and hilus in APP/PS1 mice. These results suggest that BMP4 and Noggin co-modulate neurogenesis.« less

Research on the development and preliminary application of Beijing agricultural sci-tech service hotline WebApp in agricultural consulting services

NASA Astrophysics Data System (ADS)

Yu, Weishui; Luo, Changshou; Zheng, Yaming; Wei, Qingfeng; Cao, Chengzhong

2017-09-01

To deal with the “last kilometer” problem during the agricultural science and technology information service, we analyzed the feasibility, necessity and advantages of WebApp applied to agricultural information service and discussed the modes of WebApp used in agricultural information service based on the requirements analysis and the function of WebApp. To overcome the existing App’s defects of difficult installation and weak compatibility between the mobile operating systems, the Beijing Agricultural Sci-tech Service Hotline WebApp was developed based on the HTML and JAVA technology. The WebApp has greater compatibility and simpler operation than the Native App, what’s more, it can be linked to the WeChat public platform making it spread easily and run directly without setup process. The WebApp was used to provide agricultural expert consulting services and agriculture information push, obtained a good preliminary application achievement. Finally, we concluded the creative application of WebApp in agricultural consulting services and prospected the development of WebApp in agricultural information service.

A Smartphone App for Adolescents With Sleep Disturbance: Development of the Sleep Ninja

PubMed Central

O'Dea, Bridianne; Shand, Fiona; Johnston, Lara; Frayne, Anna; Fogarty, Andrea S; Christensen, Helen

2017-01-01

Background Sleep disturbances are common in young people and have consequences for academic, social, emotional, and behavioral development. The most effective treatment is cognitive behavioral therapy for insomnia (CBT-I), with evidence suggesting that it is efficacious even when delivered digitally. Objective There are no commercially available digitally delivered CBT-I programs for use by young people. The aim of this project was to develop a smartphone app that delivers CBT-I to young people to improve sleep. Methods To inform the development of the app, young people (N=21) aged between 12 and 16 years attended one of the 3 focus groups (each with 4-10 participants). These focus groups were conducted at different stages of the development process such that the process could be iterative. Participants were asked the reasons why they might use an app to help them sleep, the kinds of features or functions that they would like to see in such an app, and any concerns they may have in using the app. Data were analyzed using a thematic analysis approach. Of the issues discussed by the participants, the researchers selected themes associated with content, functionality, and accessibility and user experience to examine, as these were most informative for the app design process. Results In terms of content, young people were interested in receiving information about recommended sleep guidelines and personalized information for their age group. They reported that keeping a sleep diary was acceptable, but they should be able to complete it flexibly, in their own time. They reported mixed views about the use of the phone’s accelerometer. Young people felt that the functionality of the app should include elements of game playing if they were to remain engaged with the app. Flexibility of use and personalized features were also desirable, and there were mixed views about the schedule of notifications and reminders. Participants reported that for the app to be accessible and usable, it should be from a trusted developer, have engaging aesthetics, have a layout that is easy to navigate, not rely on Internet coverage, and preferably be free. Participants felt that being able to conceal the purpose of the app from peers was an advantage and were willing to provide personal information to use the app if the purpose and use of that information was made clear. Overall, participants endorsed the use of the app for sleep problems among their age group and reported motivation to use it. Conclusions The Sleep Ninja is a fully-automated app that delivers CBT-I to young people, incorporating the features and information that young people reported they would expect from this app. A pilot study testing the feasibility, acceptability, and efficacy of the Sleep Ninja is now underway. PMID:28754651

Direct exposure of guinea pig CNS to human luteinizing hormone increases cerebrospinal fluid and cerebral beta amyloid levels.

PubMed

Wahjoepramono, Eka J; Wijaya, Linda K; Taddei, Kevin; Bates, Kristyn A; Howard, Matthew; Martins, Georgia; deRuyck, Karl; Matthews, Paul M; Verdile, Giuseppe; Martins, Ralph N

2011-01-01

Luteinizing hormone (LH) has been shown to alter the metabolism of beta amyloid (Aβ), a key protein in Alzheimer's disease (AD) pathogenesis. While LH and components required for LH receptor signalling are present in the brain, their role in the CNS remains unclear. In vitro, LH has been shown to facilitate neurosteroid production and alter Aβ metabolism. However, whether LH can directly modulate cerebral Aβ levels in vivo has not previously been studied. In this study, we investigated the effect of chronic administration of LH to the guinea pig CNS on cerebral Aβ levels. Gonadectomised male animals were administered, via cortical placement, either placebo or LH slow-release pellets. At 14 and 28 days after treatment, animals were sacrificed. Brain, plasma and CSF were collected and Aβ levels measured via ELISA. Levels of the Aβ precursor protein (APP) and the neurosteroidogenic enzyme cytochrome P450 side-chain cleavage enzyme (P450scc) were also assayed. An increase in CSF Aβ40 levels was observed 28 days following treatment. These CSF data also reflected changes in Aβ40 levels observed in brain homogenates. No change was observed in plasma Aβ40 levels but APP and its C-terminal fragments (APP-CTF) were significantly increased in response to LH exposure. Protein expression of P450scc was increased after 28 days of LH exposure, suggesting activation of the LH receptor. These data indicate that direct exposure of guinea pig CNS to LH results in altered brain Aβ levels, perhaps due to altered APP expression/metabolism. Copyright © 2011 S. Karger AG, Basel.

Transplantation of NSC-derived cholinergic neuron-like cells improves cognitive function in APP/PS1 transgenic mice.

PubMed

Gu, G; Zhang, W; Li, M; Ni, J; Wang, P

2015-04-16

The ability to selectively control the differentiation of neural stem cells (NSCs) into cholinergic neurons in vivo would be an important step toward cell replacement therapy. First, green fluorescent protein (GFP)-NSCs were induced to differentiate into cholinergic neuron-like cells (CNLs) with retinoic acid (RA) pre-induction followed by nerve growth factor (NGF) induction. Then, these CNLs were transplanted into bilateral hippocampus of APP/PS1 transgenic mice. Behavioral parameters showed by Morris water maze (MWM) tests and the percentages of GFP-labeled cholinergic neurons of CNL transplanted mice were compared with those of controls. Brain levels of choline acetyltransferase (ChAT) mRNA and proteins were analyzed by quantitative real-time PCR and Western blotting, ChAT activity and acetylcholine (ACh) concentration were also evaluated by ChAT activity and ACh concentration assay kits. Immunofluorescence analysis showed that 80.3±1.5% NSCs differentiated into CNLs after RA pre-induction followed by NGF induction in vitro. Three months after transplantation, 82.4±6.3% CNLs differentiated into cholinergic neurons in vivo. APP/PS1 mice transplanted with CNLs showed a significant improvement in learning and memory ability compared with control groups at different time points. Furthermore, CNLs transplantation dramatically increased in the expressions of ChAT mRNA and protein, as well ChAT activity and ACh concentration in APP/PS1 mice. Our findings support the prospect of using NSC-derived CNLs in developing therapies for Alzheimer's disease (AD). Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Reduction in open field activity in the absence of memory deficits in the AppNL-G-F knock-in mouse model of Alzheimer's disease.

PubMed

Whyte, Lauren S; Hemsley, Kim M; Lau, Adeline A; Hassiotis, Sofia; Saito, Takashi; Saido, Takaomi C; Hopwood, John J; Sargeant, Timothy J

2018-01-15

The recent development of knock-in mouse models of Alzheimer's disease provides distinct advantages over traditional transgenic mouse models that rely on over-expression of amyloid precursor protein. Two such knock-in models that have recently been widely adopted by Alzheimer's researchers are the App NL-F and App NL-G-F mice. This study aimed to further characterise the behavioural phenotype and amyloid plaque distribution of App NL-G-F/NL-G-F (C57BL/6J background) mice at six-months of age. An attempt to replicate a previous study that observed deficits in working memory in the Y-maze, showed no difference between App NL-G-F/NL-G-F and wild-type mice. Further assessment of these mice using the novel object recognition test and Morris water maze also revealed no differences between App NL-G-F/NL-G-F and wild-type mice. Despite a lack of demonstrated cognitive deficits, we report a reduction in locomotor/exploratory activity in an open field. Histological examination of App NL-G-F/NL-G-F mice showed widespread distribution of amyloid plaques at this age. We conclude that whilst at six-months of age, memory deficits are not sufficiently robust to be replicated in varying environments, amyloid plaque burden is significant in App NL-G-F/NL-G-F knock-in brain. Copyright © 2017 Elsevier B.V. All rights reserved.

Co-creating and Evaluating a Web-app Mapping Real-World Health Care Services for Students: The servi-Share Protocol.

PubMed

Montagni, Ilaria; Langlois, Emmanuel; Wittwer, Jérôme; Tzourio, Christophe

2017-02-16

University students aged 18-30 years are a population group reporting low access to health care services, with high rates of avoidance and delay of medical care. This group also reports not having appropriate information about available health care services. However, university students are at risk for several health problems, and regular medical consultations are recommended in this period of life. New digital devices are popular among the young, and Web-apps can be used to facilitate easy access to information regarding health care services. A small number of electronic health (eHealth) tools have been developed with the purpose of displaying real-world health care services, and little is known about how such eHealth tools can improve access to care. This paper describes the processes of co-creating and evaluating the beta version of a Web-app aimed at mapping and describing free or low-cost real-world health care services available in the Bordeaux area of France, which is specifically targeted to university students. The co-creation process involves: (1) exploring the needs of students to know and access real-world health care services; (2) identifying the real-world health care services of interest for students; and (3) deciding on a user interface, and developing the beta version of the Web-app. Finally, the evaluation process involves: (1) testing the beta version of the Web-app with the target audience (university students aged 18-30 years); (2) collecting their feedback via a satisfaction survey; and (3) planning a long-term evaluation. The co-creation process of the beta version of the Web-app was completed in August 2016 and is described in this paper. The evaluation process started on September 7, 2016. The project was completed in December 2016 and implementation of the Web-app is ongoing. Web-apps are an innovative way to increase the health literacy of young people in terms of delivery of and access to health care. The creation of Web-apps benefits from the involvement of stakeholders (eg, students and health care providers) to correctly identify the real-world health care services to be displayed. ©Ilaria Montagni, Emmanuel Langlois, Jérôme Wittwer, Christophe Tzourio. Originally published in JMIR Research Protocols (http://www.researchprotocols.org), 16.02.2017.

Co-creating and Evaluating a Web-app Mapping Real-World Health Care Services for Students: The servi-Share Protocol

PubMed Central

Langlois, Emmanuel; Wittwer, Jérôme; Tzourio, Christophe

2017-01-01

Background University students aged 18-30 years are a population group reporting low access to health care services, with high rates of avoidance and delay of medical care. This group also reports not having appropriate information about available health care services. However, university students are at risk for several health problems, and regular medical consultations are recommended in this period of life. New digital devices are popular among the young, and Web-apps can be used to facilitate easy access to information regarding health care services. A small number of electronic health (eHealth) tools have been developed with the purpose of displaying real-world health care services, and little is known about how such eHealth tools can improve access to care. Objective This paper describes the processes of co-creating and evaluating the beta version of a Web-app aimed at mapping and describing free or low-cost real-world health care services available in the Bordeaux area of France, which is specifically targeted to university students. Methods The co-creation process involves: (1) exploring the needs of students to know and access real-world health care services; (2) identifying the real-world health care services of interest for students; and (3) deciding on a user interface, and developing the beta version of the Web-app. Finally, the evaluation process involves: (1) testing the beta version of the Web-app with the target audience (university students aged 18-30 years); (2) collecting their feedback via a satisfaction survey; and (3) planning a long-term evaluation. Results The co-creation process of the beta version of the Web-app was completed in August 2016 and is described in this paper. The evaluation process started on September 7, 2016. The project was completed in December 2016 and implementation of the Web-app is ongoing. Conclusions Web-apps are an innovative way to increase the health literacy of young people in terms of delivery of and access to health care. The creation of Web-apps benefits from the involvement of stakeholders (eg, students and health care providers) to correctly identify the real-world health care services to be displayed. PMID:28209561

A Framework for Mobile Apps in Colleges and Universities: Data Mining Perspective

ERIC Educational Resources Information Center

Singh, Archana; Ranjan, Jayanthi

2016-01-01

The Enterprise mobility communication technology provides easy and quick accessibility to data and information integrated into one single touch point device. This device incorporates or integrates all the processes into small applications or App and thus increases the workforce capability of knowledge workers. "App" which is a small set…

Evaluation Method for an App Involving Kitchen Activities.

PubMed

Burzagli, Laura; Gaggioli, Andrea

2017-01-01

An app, developed for the national Italian project "Design for all", is evaluated here. This app supports the user in most of his/her cooking activities. The evaluation process integrates different technologies, such as expert interview, cognitive walkthrough and focus group, to consider different aspects that include, but are not limited to, usability and accessibility.

Systematic and Iterative Development of a Smartphone App to Promote Sun-Protection Among Holidaymakers: Design of a Prototype and Results of Usability and Acceptability Testing.

PubMed

Rodrigues, Angela M; Sniehotta, Falko F; Birch-Machin, Mark A; Olivier, Patrick; Araújo-Soares, Vera

2017-06-12

Sunburn and intermittent exposure to ultraviolet rays are risk factors for melanoma. Sunburn is a common experience during holidays, making tourism settings of particular interest for skin cancer prevention. Holidaymakers are a volatile populations found at different locations, which may make them difficult to reach. Given the widespread use of smartphones, evidence suggests that this might be a novel, convenient, scalable, and feasible way of reaching the target population. The main objective of this study was to describe and appraise the process of systematically developing a smartphone intervention (mISkin app) to promote sun-protection during holidays. The iterative development process of the mISkin app was conducted over four sequential stages: (1) identify evidence on the most effective behavior change techniques (BCTs) used (active ingredients) as well as theoretical predictors and theories, (2) evidence-based intervention design, (3) co-design with users of the mISkin app prototype, and (4) refinement of the app. Each stage provided key findings that were subsequently used to inform the design of the mISkin app. The sequential approach to development integrates different strands of evidence to inform the design of an evidence-based intervention. A systematic review on previously tested interventions to promote sun-protection provided cues and constraints for the design of this intervention. The development and design of the mISkin app also incorporated other sources of information, such as other literature reviews and experts' consultations. The developed prototype of the mISkin app was evaluated by engaging potential holidaymakers in the refinement and further development of the mISkin app through usability (ease-of-use) and acceptability testing of the intervention prototype. All 17 participants were satisfied with the mISkin prototype and expressed willingness to use it. Feedback on the app was integrated in the optimization process of the mISkin app. The mISkin app was designed to promote sun-protection among holidaymakers and was based on current evidence, experts' knowledge and experience, and user involvement. Based on user feedback, the app has been refined and a fully functional version is ready for formal testing in a feasibility pilot study. ©Angela M Rodrigues, Falko F Sniehotta, Mark A Birch-Machin, Patrick Olivier, Vera Araújo-Soares. Originally published in JMIR Research Protocols (http://www.researchprotocols.org), 12.06.2017.

TEAMS (Tele-Exercise and Multiple Sclerosis), a Tailored Telerehabilitation mHealth App: Participant-Centered Development and Usability Study.

PubMed

Thirumalai, Mohanraj; Rimmer, James H; Johnson, George; Wilroy, Jereme; Young, Hui-Ju; Mehta, Tapan; Lai, Byron

2018-05-24

People with multiple sclerosis face varying levels of disability and symptoms, thus requiring highly trained therapists and/or exercise trainers to design personalized exercise programs. However, for people living in geographically isolated communities, access to such trained professionals can be challenging due to a number of barriers associated with cost, access to transportation, and travel distance. Generic mobile health exercise apps often fall short of what people with multiple sclerosis need to become physically active (ie, exercise content that has been adapted to accommodate a wide range of functional limitations). This usability study describes the development process of the TEAMS (Tele-Exercise and Multiple Sclerosis) app, which is being used by people with multiple sclerosis in a large randomized controlled trial to engage in home-based telerehabilitation. Twenty-one participants with disabilities (10 people with multiple sclerosis) were involved in the double iterative design, which included the simultaneous development of the app features and exercise content (exercise videos and articles). Framed within a user-centered design approach, the development process included 2 stages: ground-level creation (focus group followed by early stage evaluations and developments), and proof of concept through 2 usability tests. Usability (effectiveness, usefulness, and satisfaction) was evaluated using a mixed-methods approach. During testing of the app's effectiveness, the second usability test resulted in an average of 1 problem per participant, a decrease of 53% compared to the initial usability test. Five themes were constructed from the qualitative data that related to app usefulness and satisfaction, namely: high perceived confidence for app usability, positive perceptions of exercise videos, viable exercise option at home, orientation and familiarity required for successful participation, and app issues. Participants acknowledged that the final app was ready to be delivered to the public after minor revisions. After including these revisions, the project team released the final app that is being used in the randomized controlled trial. A multi-level user-centered development process resulted in the development of an inclusive exercise program for people with multiple sclerosis operated through an easy-to-use app. The promotion of exercise through self-regulated mHealth programs requires a stakeholder-driven approach to app development. This ensures that app and content match the preferences and functional abilities of the end user (ie, people with varying levels of multiple sclerosis). ©Mohanraj Thirumalai, James H Rimmer, George Johnson, Jereme Wilroy, Hui-Ju Young, Tapan Mehta, Byron Lai. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 24.05.2018.

An app for patient education and self-audit within an enhanced recovery program for bowel surgery: a pilot study assessing validity and usability.

PubMed

Pecorelli, Nicolò; Fiore, Julio F; Kaneva, Pepa; Somasundram, Abarna; Charlebois, Patrick; Liberman, A Sender; Stein, Barry L; Carli, Franco; Feldman, Liane S

2018-05-01

While patient engagement and clinical audit are key components of successful enhanced recovery programs (ERPs), they require substantial resource allocation. The objective of this study was to assess the validity and usability of a novel mobile device application for education and self-reporting of adherence for patients undergoing bowel surgery within an established ERP. Prospectively recruited patients undergoing bowel surgery within an ERP used a novel app specifically designed to provide daily recovery milestones and record adherence to 15 different ERP processes and six patient-reported outcomes (PROs). Validity was measured by the agreement index (Cohen's kappa coefficient for categorical, and interclass correlation coefficient (ICC) for continuous variables) between patient-reported data through the app and data recorded by a clinical auditor. Acceptability and usability of the app were measured by the System Usability Scale (SUS). Forty-five patients participated in the study (mean age 61, 64% male). Overall, patients completed 159 of 179 (89%) of the available questionnaires through the app. Median time to complete a questionnaire was 2 min 49 s (i.q.r. 2'32″-4'36″). Substantial (kappa > 0.6) or almost perfect agreement (kappa > 0.8) and strong correlation (ICC > 0.7) between data collected through the app and by the clinical auditor was found for 14 ERP processes and four PROs. Patient-reported usability was high; mean SUS score was 87 (95% CI 83-91). Only 6 (13%) patients needed technical support to use the app. Forty (89%) patients found the app was helpful to achieve their daily goals, and 34 (76%) thought it increased their motivation to recover after surgery. This novel application provides a tool to record patient adherence to care processes and PROs, with high agreement with traditional clinical audit, high usability, and patient satisfaction. Future studies should investigate the use of mobile device apps as strategies to increase adherence to perioperative interventions.

Neuroendocrine immunomodulation network dysfunction in SAMP8 mice and PrP-hAβPPswe/PS1ΔE9 mice: potential mechanism underlying cognitive impairment

PubMed Central

Wang, Jian-hui; Cheng, Xiao-rui; Zhang, Xiao-rui; Wang, Tong-xing; Xu, Wen-jian; Li, Fei; Liu, Feng; Cheng, Jun-ping; Bo, Xiao-chen; Wang, Sheng-qi; Zhou, Wen-xia; Zhang, Yong-xiang

2016-01-01

Senescence-accelerated mouse prone 8 strain (SAMP8) and PrP-hAβPPswe/PS1ΔE9 (APP/PS1) mice are classic animal models of sporadic Alzheimer's disease and familial AD respectively. Our study showed that object recognition memory, spatial learning and memory, active and passive avoidance were deteriorated and neuroendocrine immunomodulation (NIM) network was imbalance in SAMP8 and APP/PS1 mice. SAMP8 and APP/PS1 mice had their own specific phenotype of cognition, neuroendocrine, immune and NIM molecular network. The endocrine hormone corticosterone, luteinizing hormone and follicle-stimulating hormone, chemotactic factor monocyte chemotactic protein-1, macrophage inflammatory protein-1β, regulated upon activation normal T cell expressed and secreted factor and eotaxin, pro-inflammatory factor interleukin-23, and the Th1 cell acting as cell immunity accounted for cognitive deficiencies in SAMP8 mice, while adrenocorticotropic hormone and gonadotropin-releasing hormone, colony stimulating factor granulocyte colony stimulating factor, and Th2 cell acting as humoral immunity in APP/PS1 mice. On the pathway level, chemokine signaling and T cell receptor signaling pathway played the key role in cognition impairments of two models, while cytokine-cytokine receptor interaction and natural killer cell mediated cytotoxicity were more important in cognitive deterioration of SAMP8 mice than APP/PS1 mice. This mechanisms of NIM network underlying cognitive impairment is significant for further understanding the pathogenesis of AD and can provide useful information for development of AD therapeutic drug. PMID:27049828

Amyloid-β Peptide Exacerbates the Memory Deficit Caused by Amyloid Precursor Protein Loss-of-Function in Drosophila

PubMed Central

Bourdet, Isabelle; Lampin-Saint-Amaux, Aurélie; Preat, Thomas; Goguel, Valérie

2015-01-01

The amyloid precursor protein (APP) plays a central role in Alzheimer’s disease (AD). APP can undergo two exclusive proteolytic pathways: cleavage by the α-secretase initiates the non-amyloidogenic pathway while cleavage by the β-secretase initiates the amyloidogenic pathway that leads, after a second cleavage by the γ-secretase, to amyloid-β (Aβ) peptides that can form toxic extracellular deposits, a hallmark of AD. The initial events leading to AD are still unknown. Importantly, aside from Aβ toxicity whose molecular mechanisms remain elusive, several studies have shown that APP plays a positive role in memory, raising the possibility that APP loss-of-function may participate to AD. We previously showed that APPL, the Drosophila APP ortholog, is required for associative memory in young flies. In the present report, we provide the first analysis of the amyloidogenic pathway’s influence on memory in the adult. We show that transient overexpression of the β-secretase in the mushroom bodies, the center for olfactory memory, did not alter memory. In sharp contrast, β-secretase overexpression affected memory when associated with APPL partial loss-of-function. Interestingly, similar results were observed with Drosophila Aβ peptide. Because Aβ overexpression impaired memory only when combined to APPL partial loss-of-function, the data suggest that Aβ affects memory through the APPL pathway. Thus, memory is altered by two connected mechanisms—APPL loss-of-function and amyloid peptide toxicity—revealing in Drosophila a functional interaction between APPL and amyloid peptide. PMID:26274614

The Cognitive Processing of an Educational App with Electroencephalogram and "Eye Tracking"

ERIC Educational Resources Information Center

Cuesta-Cambra, Ubaldo; Niño-González, José Ignacio; Rodríguez-Terceño, José

2017-01-01

The use of apps in education is becoming more frequent. However, the mechanisms of attention and processing of their contents and their consequences in learning have not been sufficiently studied. The objective of this work is to analyze how information is processed and learned and how visual attention takes place. It also investigates the…

SORL1 variants across Alzheimer's disease European American cohorts.

PubMed

Fernández, Maria Victoria; Black, Kathleen; Carrell, David; Saef, Ben; Budde, John; Deming, Yuetiva; Howells, Bill; Del-Aguila, Jorge L; Ma, Shengmei; Bi, Catherine; Norton, Joanne; Chasse, Rachel; Morris, John; Goate, Alison; Cruchaga, Carlos

2016-12-01

The accumulation of the toxic Aβ peptide in Alzheimer's disease (AD) largely relies upon an efficient recycling of amyloid precursor protein (APP). Recent genetic association studies have described rare variants in SORL1 with putative pathogenic consequences in the recycling of APP. In this work, we examine the presence of rare coding variants in SORL1 in three different European American cohorts: early-onset, late-onset AD (LOAD) and familial LOAD.

Improving specific activity and thermostability of Escherichia coli phytase by structure-based rational design.

PubMed

Wu, Tzu-Hui; Chen, Chun-Chi; Cheng, Ya-Shan; Ko, Tzu-Ping; Lin, Cheng-Yen; Lai, Hui-Lin; Huang, Ting-Yung; Liu, Je-Ruei; Guo, Rey-Ting

2014-04-10

Escherichia coli phytase (EcAppA) which hydrolyzes phytate has been widely applied in the feed industry, but the need to improve the enzyme activity and thermostability remains. Here, we conduct rational design with two strategies to enhance the EcAppA performance. First, residues near the substrate binding pocket of EcAppA were modified according to the consensus sequence of two highly active Citrobacter phytases. One out of the eleven mutants, V89T, exhibited 17.5% increase in catalytic activity, which might be a result of stabilized protein folding. Second, the EcAppA glycosylation pattern was modified in accordance with the Citrobacter phytases. An N-glycosylation motif near the substrate binding site was disrupted to remove spatial hindrance for phytate entry and product departure. The de-glycosylated mutants showed 9.6% increase in specific activity. On the other hand, the EcAppA mutants that adopt N-glycosylation motifs from CbAppA showed improved thermostability that three mutants carrying single N-glycosylation motif exhibited 5.6-9.5% residual activity after treatment at 80°C (1.8% for wild type). Furthermore, the mutant carrying all three glycosylation motifs exhibited 27% residual activity. In conclusion, a successful rational design was performed to obtain several useful EcAppA mutants with better properties for further applications. Copyright © 2014 Elsevier B.V. All rights reserved.

The YeastGenome app: the Saccharomyces Genome Database at your fingertips.

PubMed

Wong, Edith D; Karra, Kalpana; Hitz, Benjamin C; Hong, Eurie L; Cherry, J Michael

2013-01-01

The Saccharomyces Genome Database (SGD) is a scientific database that provides researchers with high-quality curated data about the genes and gene products of Saccharomyces cerevisiae. To provide instant and easy access to this information on mobile devices, we have developed YeastGenome, a native application for the Apple iPhone and iPad. YeastGenome can be used to quickly find basic information about S. cerevisiae genes and chromosomal features regardless of internet connectivity. With or without network access, you can view basic information and Gene Ontology annotations about a gene of interest by searching gene names and gene descriptions or by browsing the database within the app to find the gene of interest. With internet access, the app provides more detailed information about the gene, including mutant phenotypes, references and protein and genetic interactions, as well as provides hyperlinks to retrieve detailed information by showing SGD pages and views of the genome browser. SGD provides online help describing basic ways to navigate the mobile version of SGD, highlights key features and answers frequently asked questions related to the app. The app is available from iTunes (http://itunes.com/apps/yeastgenome). The YeastGenome app is provided freely as a service to our community, as part of SGD's mission to provide free and open access to all its data and annotations.

A Standards-Based Architecture Proposal for Integrating Patient mHealth Apps to Electronic Health Record Systems

PubMed Central

Fontelo, P.; Rossi, E.; Ackerman, MJ

2015-01-01

Summary Background Mobile health Applications (mHealth Apps) are opening the way to patients’ responsible and active involvement with their own healthcare management. However, apart from Apps allowing patient’s access to their electronic health records (EHRs), mHealth Apps are currently developed as dedicated “island systems”. Objective Although much work has been done on patient’s access to EHRs, transfer of information from mHealth Apps to EHR systems is still low. This study proposes a standards-based architecture that can be adopted by mHealth Apps to exchange information with EHRs to support better quality of care. Methods Following the definition of requirements for the EHR/mHealth App information exchange recently proposed, and after reviewing current standards, we designed the architecture for EHR/mHealth App integration. Then, as a case study, we modeled a system based on the proposed architecture aimed to support home monitoring for congestive heart failure patients. We simulated such process using, on the EHR side, OpenMRS, an open source longitudinal EHR and, on the mHealth App side, the iOS platform. Results The integration architecture was based on the bi-directional exchange of standard documents (clinical document architecture rel2 – CDA2). In the process, the clinician “prescribes” the home monitoring procedures by creating a CDA2 prescription in the EHR that is sent, encrypted and de-identified, to the mHealth App to create the monitoring calendar. At the scheduled time, the App alerts the patient to start the monitoring. After the measurements are done, the App generates a structured CDA2-compliant monitoring report and sends it to the EHR, thus avoiding local storage. Conclusions The proposed architecture, even if validated only in a simulation environment, represents a step forward in the integration of personal mHealth Apps into the larger health-IT ecosystem, allowing the bi-directional data exchange between patients and healthcare professionals, supporting the patient’s engagement in self-management and self-care. PMID:26448794

Anti-amnesic effect of extract and alkaloid fraction from aerial parts of Peganum harmala on scopolamine-induced memory deficits in mice.

PubMed

Liu, Wei; Zhu, Yudan; Wang, Yongli; Qi, Shenglan; Wang, Yuwen; Ma, Chao; Li, Shuping; Jiang, Bo; Cheng, Xuemei; Wang, Zhengtao; Xuan, Zhenyu; Wang, Changhong

2017-05-23

Aerial parts of Peganum harmala Linn (APP) is used as traditional medical herb for treatment of forgetfulness in Uighur medicine in China. But, the active ingredients and underlying mechanisms are unclear. The present study was undertaken to investigate the improvement effects of extract and alkaloid fraction from APP on scopolamine-induced cognitive dysfunction and to elucidate their underlying mechanisms of action, and to support its folk use with scientific evidence, and lay a foundation for its further researches. The acetylcholinesterase (AChE) inhibitory activities of extract (EXT), alkaloid fraction (ALK) and flavonoid fraction (FLA) from APP were evaluated in normal male C57BL/6 mice. The anti-amnesic effects of EXT and ALK from APP were measured in scopolamine-induced memory deficits mice by the Morris water maze (MWM) tasks. The levels of biomarkers, enzyme activity and protein expression of cholinergic system were determined in brain tissues. The AChE activity was significantly decreased and the content of neurotransmitter acetylcholine (ACh) was significantly increased in normal mice cortex and hippocampus by treatment with donepezil at dosage of 8mg/kg, EXT at dosages of 183, 550, 1650mg/kg and ALK at dosages of 10, 30, 90mg/kg (P<0.05), and the AChE activity and the content of ACh were not significantly changed in cortex and hippocampus after treatment with FLA at dosages of 10, 30, 90mg/kg (P>0.05). In the MWM task, scopolamine-induced a decrease in both the swimming time within the target zone and the number of crossings where the platform had been placed were significantly reversed by treatment with EXT at dosages of 550, 1650mg/kg and ALK at dosages of 30, 90mg/kg (P<0.05). Moreover, the activity and protein expression of AChE was significantly decreased and the content of neurotransmitter ACh was significantly increased in cerebral cortex of scopolamine-induced mice by treatment with EXT at dosages of 183, 550, 1650mg/kg and ALK at dosages of 10, 30, 90mg/kg (P<0.05), compared with scopolamine-treated group. EXT and ALK from APP exert beneficial effect on learning and memory processes in mice with scopolamine-induced memory impairment. APP is an effective traditional folk medicine and the ALK fraction is proved to be the main effective components for the treatment of forgetfulness. The ALK may be valuable source for lead compounds discovery and drug development for treatment of memory impairment such as in Alzheimer's disease. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Expert Involvement Predicts mHealth App Downloads: Multivariate Regression Analysis of Urology Apps

PubMed Central

Osório, Luís; Cavadas, Vitor; Fraga, Avelino; Carrasquinho, Eduardo; Cardoso de Oliveira, Eduardo; Castelo-Branco, Miguel; Roobol, Monique J

2016-01-01

Background Urological mobile medical (mHealth) apps are gaining popularity with both clinicians and patients. mHealth is a rapidly evolving and heterogeneous field, with some urology apps being downloaded over 10,000 times and others not at all. The factors that contribute to medical app downloads have yet to be identified, including the hypothetical influence of expert involvement in app development. Objective The objective of our study was to identify predictors of the number of urology app downloads. Methods We reviewed urology apps available in the Google Play Store and collected publicly available data. Multivariate ordinal logistic regression evaluated the effect of publicly available app variables on the number of apps being downloaded. Results Of 129 urology apps eligible for study, only 2 (1.6%) had >10,000 downloads, with half having ≤100 downloads and 4 (3.1%) having none at all. Apps developed with expert urologist involvement (P=.003), optional in-app purchases (P=.01), higher user rating (P<.001), and more user reviews (P<.001) were more likely to be installed. App cost was inversely related to the number of downloads (P<.001). Only data from the Google Play Store and the developers’ websites, but not other platforms, were publicly available for analysis, and the level and nature of expert involvement was not documented. Conclusions The explicit participation of urologists in app development is likely to enhance its chances to have a higher number of downloads. This finding should help in the design of better apps and further promote urologist involvement in mHealth. Official certification processes are required to ensure app quality and user safety. PMID:27421338

Neuroprotective effect of formononetin in ameliorating learning and memory impairment in mouse model of Alzheimer's disease.

PubMed

Fei, Hong-Xin; Zhang, Ying-Bo; Liu, Ting; Zhang, Xiao-Jie; Wu, Shu-Liang

2018-01-01

Alzheimer's disease (AD) is the most common cause of dementia among elderly population. Deranged β-amyloid (Aβ) trafficking across the blood-brain barrier is known to be a critical element in the pathogenesis of AD. In the vascular endothelial cells of hippocampus, Aβ transport is mainly mediated by low-density lipoprotein-associated protein 1 (LRP1) and the receptor for advanced glycation end (RAGE) products; therefore, LRP1 and RAGE endothelial cells are potential therapeutic targets for AD. In this study, we explored the effects of Formononetin (FMN) on learning and memory improvement in APP/PS1 mice and the related mechanisms. We found that FMN significantly improved learning and memory ability by suppressing Aβ production from APP processing, RAGE-dependent inflammatory signaling and promoted LRP1-dependent cerebral Aβ clearance pathway. Moreover, FMN treatment alleviated ultrastructural changes in hippocampal vascular endothelial cells. In conclusion, we believe that FMN may be an efficacious and promising treatment for AD.

Quality of Publicly Available Physical Activity Apps: Review and Content Analysis

PubMed Central

Alkhaldi, Ghadah; Slee, April; Hamilton, Fiona L; Murray, Elizabeth

2018-01-01

Background Within the new digital health landscape, the rise of health apps creates novel prospects for health promotion. The market is saturated with apps that aim to increase physical activity (PA). Despite the wide distribution and popularity of PA apps, there are limited data on their effectiveness, user experience, and safety of personal data. Objective The purpose of this review and content analysis was to evaluate the quality of the most popular PA apps on the market using health care quality indicators. Methods The top-ranked 400 free and paid apps from iTunes and Google Play stores were screened. Apps were included if the primary behavior targeted was PA, targeted users were adults, and the apps had stand-alone functionality. The apps were downloaded on mobile phones and assessed by 2 reviewers against the following quality assessment criteria: (1) users’ data privacy and security, (2) presence of behavior change techniques (BCTs) and quality of the development and evaluation processes, and (3) user ratings and usability. Results Out of 400 apps, 156 met the inclusion criteria, of which 65 apps were randomly selected to be downloaded and assessed. Almost 30% apps (19/65) did not have privacy policy. Every app contained at least one BCT, with an average number of 7 and a maximum of 13 BCTs. All but one app had commercial affiliation, 12 consulted an expert, and none reported involving users in the app development. Only 12 of 65 apps had a peer-reviewed study connected to the app. User ratings were high, with only a quarter of the ratings falling below 4 stars. The median usability score was excellent—86.3 out of 100. Conclusions Despite the popularity of PA apps available on the commercial market, there were substantial shortcomings in the areas of data safety and likelihood of effectiveness of the apps assessed. The limited quality of the apps may represent a missed opportunity for PA promotion. PMID:29563080

Mobile Apps to Support and Assess Foreign Language Learning

ERIC Educational Resources Information Center

Berns, Anke; Palomo-Duarte, Manuel; Dodero, Juan Manuel; Ruiz-Ladrón, Juan Miguel; Márquez, Andrea Calderón

2015-01-01

In the last two decades there have been many attempts to integrate all kinds of mobile devices and apps to support formal as well as informal learning processes. However, most of the available apps still support mainly individual learning, using mobile devices to deliver content rather than providing learners with the opportunity to interact with…

Co-Designing Mobile Apps to Assist in Clinical Nursing Education: A Study Protocol.

PubMed

O'Connor, Siobhan; Andrews, Tom

2016-01-01

Mobile applications (apps) to train health professionals is gaining momentum as the benefits of mobile learning (mLearning) are becoming apparent in complex clinical environments. However, most educational apps are generic, off-the-shelf pieces of software that do not take into consideration the unique needs of nursing students. The proposed study will apply a user-centred design process to create a tailored mobile app for nursing students to learn and apply clinical skills in practice. The app will be piloted and evaluated to understand how nursing students use mobile technology in clinical settings to support their learning and educational needs.

Suppression of angiogenesis by atmospheric pressure plasma in human aortic endothelial cells

NASA Astrophysics Data System (ADS)

Gweon, Bomi; Kim, Hyeonyu; Kim, Kijung; Kim, Mina; Shim, Eunyoung; Kim, Sunja; Choe, Wonho; Shin, Jennifer H.

2014-03-01

Atmospheric pressure plasma (APP) has been recognized as a promising tool for cancer therapy based on its ability to remove cancer cells by causing apoptosis and necrosis. However, the effect of APP on the neighboring tissues of tumors remains unknown. Moreover, the role of APP on the vessels near tumors could be very important, because once a tumor becomes vascularized, the potential for metastasis can increase dramatically. We show in the present study that APP can induce cell cycle arrest in endothelial cells and further suppress the angiogenesis process. These results strongly support the use of APP in cancer treatment.

MicroRNA-195 prevents dendritic degeneration and neuron death in rats following chronic brain hypoperfusion

PubMed Central

Chen, Xin; Jiang, Xue-Mei; Zhao, Lin-Jing; Sun, Lin-Lin; Yan, Mei-Ling; Tian, You; Zhang, Shuai; Duan, Ming-Jing; Zhao, Hong-Mei; Li, Wen-Rui; Hao, Yang-Yang; Wang, Li-Bo; Xiong, Qiao-Jie; Ai, Jing

2017-01-01

Impaired synaptic plasticity and neuron loss are hallmarks of Alzheimer’s disease and vascular dementia. Here, we found that chronic brain hypoperfusion (CBH) by bilateral common carotid artery occlusion (2VO) decreased the total length, numbers and crossings of dendrites and caused neuron death in rat hippocampi and cortices. It also led to increase in N-terminal β-amyloid precursor protein (N-APP) and death receptor-6 (DR6) protein levels and in the activation of caspase-3 and caspase-6. Further study showed that DR6 protein was downregulated by miR-195 overexpression, upregulated by miR-195 inhibition, and unchanged by binding-site mutation and miR-masks. Knockdown of endogenous miR-195 by lentiviral vector-mediated overexpression of its antisense molecule (lenti-pre-AMO-miR-195) decreased the total length, numbers and crossings of dendrites and neuron death, upregulated N-APP and DR6 levels, and elevated cleaved caspase-3 and caspase-6 levels. Overexpression of miR-195 using lenti-pre-miR-195 prevented these changes triggered by 2VO. We conclude that miR-195 is involved in CBH-induced dendritic degeneration and neuron death through activation of the N-APP/DR6/caspase pathway. PMID:28569780

Defective lysosomal proteolysis and axonal transport are early pathogenic events that worsen with age leading to increased APP metabolism and synaptic Abeta in transgenic APP/PS1 hippocampus.

PubMed

Torres, Manuel; Jimenez, Sebastian; Sanchez-Varo, Raquel; Navarro, Victoria; Trujillo-Estrada, Laura; Sanchez-Mejias, Elisabeth; Carmona, Irene; Davila, Jose Carlos; Vizuete, Marisa; Gutierrez, Antonia; Vitorica, Javier

2012-11-22

Axonal pathology might constitute one of the earliest manifestations of Alzheimer disease. Axonal dystrophies were observed in Alzheimer's patients and transgenic models at early ages. These axonal dystrophies could reflect the disruption of axonal transport and the accumulation of multiple vesicles at local points. It has been also proposed that dystrophies might interfere with normal intracellular proteolysis. In this work, we have investigated the progression of the hippocampal pathology and the possible implication in Abeta production in young (6 months) and aged (18 months) PS1(M146L)/APP(751sl) transgenic mice. Our data demonstrated the existence of a progressive, age-dependent, formation of axonal dystrophies, mainly located in contact with congophilic Abeta deposition, which exhibited tau and neurofilament hyperphosphorylation. This progressive pathology was paralleled with decreased expression of the motor proteins kinesin and dynein. Furthermore, we also observed an early decrease in the activity of cathepsins B and D, progressing to a deep inhibition of these lysosomal proteases at late ages. This lysosomal impairment could be responsible for the accumulation of LC3-II and ubiquitinated proteins within axonal dystrophies. We have also investigated the repercussion of these deficiencies on the APP metabolism. Our data demonstrated the existence of an increase in the amyloidogenic pathway, which was reflected by the accumulation of hAPPfl, C99 fragment, intracellular Abeta in parallel with an increase in BACE and gamma-secretase activities. In vitro experiments, using APPswe transfected N2a cells, demonstrated that any imbalance on the proteolytic systems reproduced the in vivo alterations in APP metabolism. Finally, our data also demonstrated that Abeta peptides were preferentially accumulated in isolated synaptosomes. A progressive age-dependent cytoskeletal pathology along with a reduction of lysosomal and, in minor extent, proteasomal activity could be directly implicated in the progressive accumulation of APP derived fragments (and Abeta peptides) in parallel with the increase of BACE-1 and gamma-secretase activities. This retard in the APP metabolism seemed to be directly implicated in the synaptic Abeta accumulation and, in consequence, in the pathology progression between synaptically connected regions.

Patient characteristics and process factors associated with antipsychotic polypharmacy in a nationwide sample of psychiatric inpatients in Italy.

PubMed

Santone, Giovanni; Bellantuono, Cesario; Rucci, Paola; Picardi, Angelo; Preti, Antonio; de Girolamo, Giovanni

2011-05-01

The present study investigated: (i) the rate of prescription of antipsychotic (AP) polypharmacy (APP) in a large, representative sample of psychiatric inpatients; and (ii) the relationship between APP prescription and the characteristics of patients and facilities. The sample included 1022 psychiatric patients scheduled to be discharged from acute inpatient facilities with drug therapies including AP. Demographic and clinical data were obtained from the treating physician or retrieved from patients' records through a standardized Patient Form. Patients were administered the 24-item Brief Psychiatric Rating Scale. Three indicators were used to describe the process of care in the facilities: a Restrictiveness score, a Standardization score, and a Treatment score. A multilevel mixed-effect logistic regression was used to predict APP using patient and facility as the variables. APP was prescribed to 333 (32.5%) patients, the most common patterns being a first-generation and a second-generation AP (n = 178, 17.6%) or of two first-generation APs (n = 80, 7.8%). Patients with a diagnosis of schizophrenia and poorer insight into illness at admission were significantly more likely to receive APP. The availability of more complex therapeutic interventions in the facility was also associated with APP. In our nationwide sample of psychiatric inpatients, APP was frequently prescribed to treat the more severe patients. However, it was also associated with process of care characteristics such as delivery of more complex therapeutic interventions, and was therefore not used only to control patient behavior. Copyright © 2010 John Wiley & Sons, Ltd.

Mobile phone applications in Parkinson's disease: A systematic review.

PubMed

Linares-Del Rey, M; Vela-Desojo, L; Cano-de la Cuerda, R

2017-05-23

Parkinson's disease (PD) is the second most common neurodegenerative disease. However, diagnosing, assessing, and treating these patients is a complex process requiring continuous monitoring. In this context, smartphones may be useful in the management of patients with PD. The purpose of this study is to perform a systematic review of the literature addressing the use of mobile phone applications (apps) in PD. We conducted a literature search of articles published in English or Spanish between 2011 and 2016 analysing or validating apps specifically designed for or useful in PD. In addition, we searched for apps potentially useful for PD patients in the leading app stores. The literature and app searches yielded a total of 125 apps, 56 of which were classified as potentially useful in PD and 69 as specifically designed for PD (23 information apps, 29 assessment apps, 13 treatment apps, and 4 assessment and treatment apps). Numerous mobile apps are potentially useful in or specifically designed for PD management. However, scientific evidence of their usefulness is scarce and of poor quality. Further studies are needed to validate these tools and regulate their use. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

Popularity Modeling for Mobile Apps: A Sequential Approach.

PubMed

Zhu, Hengshu; Liu, Chuanren; Ge, Yong; Xiong, Hui; Chen, Enhong

2015-07-01

The popularity information in App stores, such as chart rankings, user ratings, and user reviews, provides an unprecedented opportunity to understand user experiences with mobile Apps, learn the process of adoption of mobile Apps, and thus enables better mobile App services. While the importance of popularity information is well recognized in the literature, the use of the popularity information for mobile App services is still fragmented and under-explored. To this end, in this paper, we propose a sequential approach based on hidden Markov model (HMM) for modeling the popularity information of mobile Apps toward mobile App services. Specifically, we first propose a popularity based HMM (PHMM) to model the sequences of the heterogeneous popularity observations of mobile Apps. Then, we introduce a bipartite based method to precluster the popularity observations. This can help to learn the parameters and initial values of the PHMM efficiently. Furthermore, we demonstrate that the PHMM is a general model and can be applicable for various mobile App services, such as trend based App recommendation, rating and review spam detection, and ranking fraud detection. Finally, we validate our approach on two real-world data sets collected from the Apple Appstore. Experimental results clearly validate both the effectiveness and efficiency of the proposed popularity modeling approach.

A Smartphone App for Adolescents With Sleep Disturbance: Development of the Sleep Ninja.

PubMed

Werner-Seidler, Aliza; O'Dea, Bridianne; Shand, Fiona; Johnston, Lara; Frayne, Anna; Fogarty, Andrea S; Christensen, Helen

2017-07-28

Sleep disturbances are common in young people and have consequences for academic, social, emotional, and behavioral development. The most effective treatment is cognitive behavioral therapy for insomnia (CBT-I), with evidence suggesting that it is efficacious even when delivered digitally. There are no commercially available digitally delivered CBT-I programs for use by young people. The aim of this project was to develop a smartphone app that delivers CBT-I to young people to improve sleep. To inform the development of the app, young people (N=21) aged between 12 and 16 years attended one of the 3 focus groups (each with 4-10 participants). These focus groups were conducted at different stages of the development process such that the process could be iterative. Participants were asked the reasons why they might use an app to help them sleep, the kinds of features or functions that they would like to see in such an app, and any concerns they may have in using the app. Data were analyzed using a thematic analysis approach. Of the issues discussed by the participants, the researchers selected themes associated with content, functionality, and accessibility and user experience to examine, as these were most informative for the app design process. In terms of content, young people were interested in receiving information about recommended sleep guidelines and personalized information for their age group. They reported that keeping a sleep diary was acceptable, but they should be able to complete it flexibly, in their own time. They reported mixed views about the use of the phone's accelerometer. Young people felt that the functionality of the app should include elements of game playing if they were to remain engaged with the app. Flexibility of use and personalized features were also desirable, and there were mixed views about the schedule of notifications and reminders. Participants reported that for the app to be accessible and usable, it should be from a trusted developer, have engaging aesthetics, have a layout that is easy to navigate, not rely on Internet coverage, and preferably be free. Participants felt that being able to conceal the purpose of the app from peers was an advantage and were willing to provide personal information to use the app if the purpose and use of that information was made clear. Overall, participants endorsed the use of the app for sleep problems among their age group and reported motivation to use it. The Sleep Ninja is a fully-automated app that delivers CBT-I to young people, incorporating the features and information that young people reported they would expect from this app. A pilot study testing the feasibility, acceptability, and efficacy of the Sleep Ninja is now underway. ©Aliza Werner-Seidler, Bridianne O'Dea, Fiona Shand, Lara Johnston, Anna Frayne, Andrea S Fogarty, Helen Christensen. Originally published in JMIR Mental Health (http://mental.jmir.org), 28.07.2017.

Amyloid protein-mediated differential DNA methylation status regulates gene expression in Alzheimer's disease model cell line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sung, Hye Youn; Choi, Eun Nam; Ahn Jo, Sangmee

2011-11-04

Highlights: Black-Right-Pointing-Pointer Genome-wide DNA methylation pattern in Alzheimer's disease model cell line. Black-Right-Pointing-Pointer Integrated analysis of CpG methylation and mRNA expression profiles. Black-Right-Pointing-Pointer Identify three Swedish mutant target genes; CTIF, NXT2 and DDR2 gene. Black-Right-Pointing-Pointer The effect of Swedish mutation on alteration of DNA methylation and gene expression. -- Abstract: The Swedish mutation of amyloid precursor protein (APP-sw) has been reported to dramatically increase beta amyloid production through aberrant cleavage at the beta secretase site, causing early-onset Alzheimer's disease (AD). DNA methylation has been reported to be associated with AD pathogenesis, but the underlying molecular mechanism of APP-sw-mediated epigenetic alterationsmore » in AD pathogenesis remains largely unknown. We analyzed genome-wide interplay between promoter CpG DNA methylation and gene expression in an APP-sw-expressing AD model cell line. To identify genes whose expression was regulated by DNA methylation status, we performed integrated analysis of CpG methylation and mRNA expression profiles, and identified three target genes of the APP-sw mutant; hypomethylated CTIF (CBP80/CBP20-dependent translation initiation factor) and NXT2 (nuclear exporting factor 2), and hypermethylated DDR2 (discoidin domain receptor 2). Treatment with the demethylating agent 5-aza-2 Prime -deoxycytidine restored mRNA expression of these three genes, implying methylation-dependent transcriptional regulation. The profound alteration in the methylation status was detected at the -435, -295, and -271 CpG sites of CTIF, and at the -505 to -341 region in the promoter of DDR2. In the promoter region of NXT2, only one CpG site located at -432 was differentially unmethylated in APP-sw cells. Thus, we demonstrated the effect of the APP-sw mutation on alteration of DNA methylation and subsequent gene expression. This epigenetic regulatory mechanism may contribute to the pathogenesis of AD.« less

Development of a Mobile App for Family Planning Providers.

PubMed

Halsall, Viannella; Rogers, Jennifer; Witt, Jacki; Song, Sejun; Nguyen, Hoang Duc Huy; Kelly, Patricia

To provide an overview of lessons learned during the development process of an app for iOS and Android based on national recommendations for providing quality family planning services. After a review of existing apps was conducted to determine whether an app of clinical recommendations for family planning existed, a team of clinicians, training specialists, and app developers created a resource app by first drafting a comprehensive content map. A prototype of the app was then pilot tested using smart tablets by a volunteer convenience sample of women's healthcare professionals. Outcomes measured included usability, acceptability, download analytics, and satisfaction by clinicians as reported through an investigator-developed tool. Sixty-nine professionals tested a prototype of the app, and completed a user satisfaction tool. Overall, user feedback was positive, and a zoom function was added to the final version as a result of the pilot test. Within 3 months of being publicly available, the app was downloaded 677 times, with 97% of downloads occurring on smart phones, 76% downloads occurring on iOS devices, and 24% on Android devices. This trend persisted throughout the following 3 months. Clinicians with an interest in developing an app should consider a team approach to development, pilot test the app prior to wider distribution, and develop a web-based version of the app to be used by clinicians who are unable to access smart devices in their practice setting.

The Role of Gay Identity Confusion and Outness in Sex-Seeking on Mobile Dating Apps Among Men Who Have Sex With Men: A Conditional Process Analysis.

PubMed

Chan, Lik Sam

2017-01-01

Mobile dating apps are now a popular platform for men who have sex with men (MSM) to connect with others. Based on the uses and gratifications (U&G) theory, this study explores the relationship between sex-seeking and the number of casual sex partners met through MSM-based mobile dating apps (Grindr, Jack'd, and SCRUFF). The conditional process analysis (N = 401) shows that this relationship was significant and was mediated by the intensity of app use. That is, sex-seeking indirectly affected the number of casual sex partners through the intensity of app use. Furthermore, gay identity confusion and outness to the world moderated this indirect effect: it was stronger when the user was either more confused about his sexuality or was less out to the world. This research introduces an alternative way to incorporate psychographics variables into the U&G framework.

Cholesterol as a co-solvent and a ligand for membrane proteins

PubMed Central

Song, Yuanli; Kenworthy, Anne K; Sanders, Charles R

2014-01-01

As of mid 2013 a Medline search on “cholesterol” yielded over 200,000 hits, reflecting the prominence of this lipid in numerous aspects of animal cell biology and physiology under conditions of health and disease. Aberrations in cholesterol homeostasis underlie both a number of rare genetic disorders and contribute to common sporadic and complex disorders including heart disease, stroke, type II diabetes, and Alzheimer's disease. The corresponding author of this review and his lab stumbled only recently into the sprawling area of cholesterol research when they discovered that the amyloid precursor protein (APP) binds cholesterol, a topic covered by the Hans Neurath Award lecture at the 2013 Protein Society Meeting. Here, we first provide a brief overview of cholesterol-protein interactions and then offer our perspective on how and why binding of cholesterol to APP and its C99 domain (β-CTF) promotes the amyloidogenic pathway, which is closely related to the etiology of Alzheimer's disease. PMID:24155031

TEAMS (Tele-Exercise and Multiple Sclerosis), a Tailored Telerehabilitation mHealth App: Participant-Centered Development and Usability Study

PubMed Central

Rimmer, James H; Johnson, George; Wilroy, Jereme; Young, Hui-Ju; Mehta, Tapan; Lai, Byron

2018-01-01

Background People with multiple sclerosis face varying levels of disability and symptoms, thus requiring highly trained therapists and/or exercise trainers to design personalized exercise programs. However, for people living in geographically isolated communities, access to such trained professionals can be challenging due to a number of barriers associated with cost, access to transportation, and travel distance. Generic mobile health exercise apps often fall short of what people with multiple sclerosis need to become physically active (ie, exercise content that has been adapted to accommodate a wide range of functional limitations). Objective This usability study describes the development process of the TEAMS (Tele-Exercise and Multiple Sclerosis) app, which is being used by people with multiple sclerosis in a large randomized controlled trial to engage in home-based telerehabilitation. Methods Twenty-one participants with disabilities (10 people with multiple sclerosis) were involved in the double iterative design, which included the simultaneous development of the app features and exercise content (exercise videos and articles). Framed within a user-centered design approach, the development process included 2 stages: ground-level creation (focus group followed by early stage evaluations and developments), and proof of concept through 2 usability tests. Usability (effectiveness, usefulness, and satisfaction) was evaluated using a mixed-methods approach. Results During testing of the app’s effectiveness, the second usability test resulted in an average of 1 problem per participant, a decrease of 53% compared to the initial usability test. Five themes were constructed from the qualitative data that related to app usefulness and satisfaction, namely: high perceived confidence for app usability, positive perceptions of exercise videos, viable exercise option at home, orientation and familiarity required for successful participation, and app issues. Participants acknowledged that the final app was ready to be delivered to the public after minor revisions. After including these revisions, the project team released the final app that is being used in the randomized controlled trial. Conclusions A multi-level user-centered development process resulted in the development of an inclusive exercise program for people with multiple sclerosis operated through an easy-to-use app. The promotion of exercise through self-regulated mHealth programs requires a stakeholder-driven approach to app development. This ensures that app and content match the preferences and functional abilities of the end user (ie, people with varying levels of multiple sclerosis). PMID:29798832

Expression of endogenous mouse APP modulates β-amyloid deposition in hAPP-transgenic mice.

PubMed

Steffen, Johannes; Krohn, Markus; Schwitlick, Christina; Brüning, Thomas; Paarmann, Kristin; Pietrzik, Claus U; Biverstål, Henrik; Jansone, Baiba; Langer, Oliver; Pahnke, Jens

2017-06-20

Amyloid-β (Aβ) deposition is one of the hallmarks of the amyloid hypothesis in Alzheimer's disease (AD). Mouse models using APP-transgene overexpression to generate amyloid plaques have shown to model only certain parts of the disease. The extent to which the data from mice can be transferred to man remains controversial. Several studies have shown convincing treatment results in reducing Aβ and enhancing cognition in mice but failed totally in human. One model-dependent factor has so far been almost completely neglected: the endogenous expression of mouse APP and its effects on the transgenic models and the readout for therapeutic approaches.Here, we report that hAPP-transgenic models of amyloidosis devoid of endogenous mouse APP expression (mAPP-knockout / mAPPko) show increased amounts and higher speed of Aβ deposition than controls with mAPP. The number of senile plaques and the level of aggregated hAβ were elevated in mAPPko mice, while the deposition in cortical blood vessels was delayed, indicating an alteration in the general aggregation propensity of hAβ together with endogenous mAβ. Furthermore, the cellular response to Aβ deposition was modulated: mAPPko mice developed a pronounced and age-dependent astrogliosis, while microglial association to amyloid plaques was diminished. The expression of human and murine aggregation-prone proteins with differing amino acid sequences within the same mouse model might not only alter the extent of deposition but also modulate the route of pathogenesis, and thus, decisively influence the study outcome, especially in translational research.

Transport and metabolism of MitoQ10, a mitochondria-targeted antioxidant, in Caco-2 cell monolayers.

PubMed

Li, Yan; Fawcett, J Paul; Zhang, Hu; Tucker, Ian G

2007-04-01

Mitoquinone (MitoQ(10) mesylate) is a mitochondria-targeted antioxidant formulated for oral administration in the treatment of neurodegenerative diseases. We have investigated the absorption and metabolism of MitoQ(10) in Caco-2 cell monolayers. The intracellular accumulation of MitoQ(10) was 18-41% of the total amount of MitoQ(10) added. Some of the intracellular MitoQ(10) was reduced to mitoquinol and subsequently metabolized to glucuronide and sulfate conjugates. Transport of MitoQ(10) was polarized with the apparent permeability (P(app)) from basolateral (BL) to apical (AP) (P(appBL-->AP)) being >2.5-fold the P(app) from apical to basolateral (P(appAP-->BL)). In the presence of 4% bovine serum albumin on the basolateral side, the P(appAP-->BL) value increased 7-fold compared with control. The P(appBL-->AP) value decreased by 26, 31 and 61% in the presence of verapamil 100 microM, ciclosporin 10 and 30 microM, respectively, whereas the P(appAP-->BL) value increased 71% in the presence of ciclosporin 30 microM. Apical efflux of mitoquinol sulfate and mitoquinol glucuronide conjugates was significantly decreased by ciclosporin 30 microM and the breast cancer receptor protein (BCRP) inhibitor, reserpine 25 microM, respectively. These results suggested that the bioavailability of MitoQ(10) may be limited by intracellular metabolism and the action of P-glycoprotein and BCRP. However, the dramatic increase in absorptive P(app) in the presence of bovine serum albumin on the receiver side suggests these barrier functions may be less significant in-vivo.

Severe diffuse axon injury in chronic alcoholic rat medulla oblongata following a concussion blow.

PubMed

Luo, Jianming; Chen, Guang; Wei, Lai; Qian, Hong; Lai, Xiaoping; Wang, Dian; Lv, Junyao; Yu, Xiaojun

2014-01-01

We investigated the axonal morphological changes and expression of both tau protein and β-APP following concussion to the medulla oblongata, in a rat model of chronic alcoholism. Fifty-nine male Sprague-Dawley rats were randomly divided into EtOH, EtOH-TBI and control groups (water group, water-TBI group). To establish chronic alcoholic rats, rats were intragastrically given edible spirituous liquor twice daily. Rats also received a blow on the occipital tuberosity with an iron pendulum. Morphological changes and expression of tau and β-APP proteins in the medulla oblongata were examined. (a) Nerve fibre thickening and twisting were observed in alcoholic rats, with nerve fibre changes becoming more significant following a concussion blow, which leads to some nerve fibres fracturing. (b) Transmission electron microscopy revealed that the nerve fibre myelin became loosened and displayed lamellar separation, which became more significant following concussion. (c) The integral optical density (IOD) sum value of β-APP of the EtOH-TBI group was lower than that in the EtOH group (P < 0.05); the Tau IOD sum value of the EtOH-TBI group was higher than that in the EtOH group (P < 0.05). (a) Chronic alcoholism caused nerve fibre and neuronal morphology damage in the rat medulla oblongata, with structural damage becoming more significant following concussion. (b) Concussion changed the expression of β-APP and tau protein in chronic alcoholic rat medulla oblongata, suggesting that chronic alcoholism can lead to severe axonal injury following a concussion blow. (c) The effect of chronic alcoholism may be synergistic the concussion blow to promote animal injury and death.

BMP9 ameliorates amyloidosis and the cholinergic defect in a mouse model of Alzheimer's disease.

PubMed

Burke, Rebecca M; Norman, Timothy A; Haydar, Tarik F; Slack, Barbara E; Leeman, Susan E; Blusztajn, Jan Krzysztof; Mellott, Tiffany J

2013-11-26

Bone morphogenetic protein 9 (BMP9) promotes the acquisition of the cholinergic phenotype in basal forebrain cholinergic neurons (BFCN) during development and protects these neurons from cholinergic dedifferentiation following axotomy when administered in vivo. A decline in BFCN function occurs in patients with Alzheimer's disease (AD) and contributes to the AD-associated memory deficits. We infused BMP9 intracerebroventricularly for 7 d in transgenic AD model mice expressing green fluorescent protein specifically in cholinergic neurons (APP.PS1/CHGFP) and in wild-type littermate controls (WT/CHGFP). We used 5-mo-old mice, an age when the AD transgenics display early amyloid deposition and few cholinergic defects, and 10-mo-old mice, by which time these mice exhibit established disease. BMP9 infusion reduced the number of Aβ42-positive amyloid plaques in the hippocampus and cerebral cortex of 5- and 10-mo-old APP.PS1/CHGFP mice and reversed the reductions in choline acetyltransferase protein levels in the hippocampus of 10-mo-old APP.PS1/CHGFP mice. The treatment increased cholinergic fiber density in the hippocampus of both WT/CHGFP and APP.PS1/CHGFP mice at both ages. BMP9 infusion also increased hippocampal levels of neurotrophin 3, insulin-like growth factor 1, and nerve growth factor and of the nerve growth factor receptors, tyrosine kinase receptor A and p75/NGFR, irrespective of the genotype of the mice. These data show that BMP9 administration is effective in reducing the Aβ42 amyloid plaque burden, reversing cholinergic neuron abnormalities, and generating a neurotrophic milieu for BFCN in a mouse model of AD and provide evidence that the BMP9-signaling pathway may constitute a therapeutic target for AD.

Effects of glutamine supplementation on gut barrier, glutathione content and acute phase response in malnourished rats during inflammatory shock

PubMed Central

Belmonte, Liliana; Coëffier, Moïse; Pessot, Florence Le; Miralles-Barrachina, Olga; Hiron, Martine; Leplingard, Antony; Lemeland, Jean-François; Hecketsweiler, Bernadette; Daveau, Maryvonne; Ducrotté, Philippe; Déchelotte, Pierre

2007-01-01

AIM: To evaluate the effect of glutamine on intestinal mucosa integrity, glutathione stores and acute phase response in protein-depleted rats during an inflammatory shock. METHODS: Plasma acute phase proteins (APP), jejunal APP mRNA levels, liver and jejunal glutathione concentrations were measured before and one, three and seven days after turpentine injection in 4 groups of control, protein-restricted, protein-restricted rats supplemented with glutamine or protein powder. Bacterial translocation in mesenteric lymph nodes and intestinal morphology were also assessed. RESULTS: Protein deprivation and turpentine injection significantly reduced jejunal villus height, and crypt depths. Mucosal glutathione concentration significantly decreased in protein-restricted rats. Before turpentine oil, glutamine supplementation restored villus heights and glutathione concentration (3.24 ± 1.05 vs 1.72 ± 0.46 μmol/g tissue, P < 0.05) in the jejunum, whereas in the liver glutathione remained low. Glutamine markedly increased jejunal α1-acid glycoprotein mRNA level after turpentine oil but did not affect its plasma concentration. Bacterial translocation in protein-restricted rats was not prevented by glutamine or protein powder supplementation. CONCLUSION: Glutamine restored gut glutathione stores and villus heights in malnourished rats but had no preventive effect on bacterial translocation in our model. PMID:17569119

C-reactive protein, haptoglobin, serum amyloid A and pig major acute phase protein response in pigs simultaneously infected with H1N1 swine influenza virus and Pasteurella multocida

PubMed Central

2013-01-01

Background Swine influenza (SI) is an acute respiratory disease caused by swine influenza virus (SIV). Swine influenza is generally characterized by acute onset of fever and respiratory symptoms. The most frequent complications of influenza are secondary bacterial pneumonia. The objective of this work was to study the acute phase proteins (APP) responses after coinfection of piglets with H1N1 swine influenza virus (SwH1N1) and Pasteurella multocida (Pm) in order to identify whether the individual APP response correlate with disease severity and whether APP could be used as markers of the health status of coinfected pigs. Results In all coinfected pigs clinical sings, including fever, coughing and dyspnea, were seen. Viral shedding was observed from 2 to 7 dpi. The mean level of antibodies against Pm dermonecrotoxin in infected piglets increase significantly from 7 dpi. Anti-SwH1N1 antibodies in the serum were detected from 7 dpi. The concentration of C-reactive protein (CRP) increased significantly at 1 dpi as compared to control pigs, and remained significantly higher to 3 dpi. Level of serum amyloid A (SAA) was significantly higher from 2 to 3 dpi. Haptoglobin (Hp) was significantly elevated from 3 dpi to the end of study, while pig major acute phase protein (Pig-MAP) from 3 to 7 dpi. The concentrations of CRP, Hp and SAA significantly increased before specific antibodies were detected. Positive correlations were found between serum concentration of Hp and SAA and lung scores, and between clinical score and concentrations of Pig-MAP and SAA. Conclusions The results of current study confirmed that monitoring of APP may revealed ongoing infection, and in this way may be useful in selecting clinically healthy pigs (i.e. before integration into an uninfected herd). Present results corroborated our previous findings that SAA could be a potentially useful indicator in experimental infection studies (e.g. vaccine efficiency investigations) or as a marker for disease severity, because of correlation observed between its concentration in serum and disease severity (lung scores, clinical scores). PMID:23332090

C-reactive protein, haptoglobin, serum amyloid A and pig major acute phase protein response in pigs simultaneously infected with H1N1 swine influenza virus and Pasteurella multocida.

PubMed

Pomorska-Mól, Małgorzata; Markowska-Daniel, Iwona; Kwit, Krzysztof; Stępniewska, Katarzyna; Pejsak, Zygmunt

2013-01-18

Swine influenza (SI) is an acute respiratory disease caused by swine influenza virus (SIV). Swine influenza is generally characterized by acute onset of fever and respiratory symptoms. The most frequent complications of influenza are secondary bacterial pneumonia. The objective of this work was to study the acute phase proteins (APP) responses after coinfection of piglets with H1N1 swine influenza virus (SwH1N1) and Pasteurella multocida (Pm) in order to identify whether the individual APP response correlate with disease severity and whether APP could be used as markers of the health status of coinfected pigs. In all coinfected pigs clinical sings, including fever, coughing and dyspnea, were seen. Viral shedding was observed from 2 to 7 dpi. The mean level of antibodies against Pm dermonecrotoxin in infected piglets increase significantly from 7 dpi. Anti-SwH1N1 antibodies in the serum were detected from 7 dpi. The concentration of C-reactive protein (CRP) increased significantly at 1 dpi as compared to control pigs, and remained significantly higher to 3 dpi. Level of serum amyloid A (SAA) was significantly higher from 2 to 3 dpi. Haptoglobin (Hp) was significantly elevated from 3 dpi to the end of study, while pig major acute phase protein (Pig-MAP) from 3 to 7 dpi. The concentrations of CRP, Hp and SAA significantly increased before specific antibodies were detected. Positive correlations were found between serum concentration of Hp and SAA and lung scores, and between clinical score and concentrations of Pig-MAP and SAA. The results of current study confirmed that monitoring of APP may revealed ongoing infection, and in this way may be useful in selecting clinically healthy pigs (i.e. before integration into an uninfected herd). Present results corroborated our previous findings that SAA could be a potentially useful indicator in experimental infection studies (e.g. vaccine efficiency investigations) or as a marker for disease severity, because of correlation observed between its concentration in serum and disease severity (lung scores, clinical scores).

Proteomic Profiling of Cranial (Superior) Cervical Ganglia Reveals Beta-Amyloid and Ubiquitin Proteasome System Perturbations in an Equine Multiple System Neuropathy.

PubMed

McGorum, Bruce C; Pirie, R Scott; Eaton, Samantha L; Keen, John A; Cumyn, Elizabeth M; Arnott, Danielle M; Chen, Wenzhang; Lamont, Douglas J; Graham, Laura C; Llavero Hurtado, Maica; Pemberton, Alan; Wishart, Thomas M

2015-11-01

Equine grass sickness (EGS) is an acute, predominantly fatal, multiple system neuropathy of grazing horses with reported incidence rates of ∼2%. An apparently identical disease occurs in multiple species, including but not limited to cats, dogs, and rabbits. Although the precise etiology remains unclear, ultrastructural findings have suggested that the primary lesion lies in the glycoprotein biosynthetic pathway of specific neuronal populations. The goal of this study was therefore to identify the molecular processes underpinning neurodegeneration in EGS. Here, we use a bottom-up approach beginning with the application of modern proteomic tools to the analysis of cranial (superior) cervical ganglion (CCG, a consistently affected tissue) from EGS-affected patients and appropriate control cases postmortem. In what appears to be the proteomic application of modern proteomic tools to equine neuronal tissues and/or to an inherent neurodegenerative disease of large animals (not a model of human disease), we identified 2,311 proteins in CCG extracts, with 320 proteins increased and 186 decreased by greater than 20% relative to controls. Further examination of selected proteomic candidates by quantitative fluorescent Western blotting (QFWB) and subcellular expression profiling by immunohistochemistry highlighted a previously unreported dysregulation in proteins commonly associated with protein misfolding/aggregation responses seen in a myriad of human neurodegenerative conditions, including but not limited to amyloid precursor protein (APP), microtubule associated protein (Tau), and multiple components of the ubiquitin proteasome system (UPS). Differentially expressed proteins eligible for in silico pathway analysis clustered predominantly into the following biofunctions: (1) diseases and disorders, including; neurological disease and skeletal and muscular disorders and (2) molecular and cellular functions, including cellular assembly and organization, cell-to-cell signaling and interaction (including epinephrine, dopamine, and adrenergic signaling and receptor function), and small molecule biochemistry. Interestingly, while the biofunctions identified in this study may represent pathways underpinning EGS-induced neurodegeneration, this is also the first demonstration of potential molecular conservation (including previously unreported dysregulation of the UPS and APP) spanning the degenerative cascades from an apparently unrelated condition of large animals, to small animal models with altered neuronal vulnerability, and human neurological conditions. Importantly, this study highlights the feasibility and benefits of applying modern proteomic techniques to veterinary investigations of neurodegenerative processes in diseases of large animals. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

A canine model of Alzheimer's disease generated by overexpressing a mutated human amyloid precursor protein.

PubMed

Lee, Geun-Shik; Jeong, Yeon Woo; Kim, Joung Joo; Park, Sun Woo; Ko, Kyeong Hee; Kang, Mina; Kim, Yu Kyung; Jung, Eui-Man; Moon, Changjong; Hyun, Sang Hwan; Hwang, Kyu-Chan; Kim, Nam-Hyung; Shin, Taeyoung; Jeung, Eui-Bae; Hwang, Woo Suk

2014-04-01

Canines are considered the most authentic model for studying multifactorial human diseases, as these animals typically share a common environment with man. Somatic cell nuclear transfer (SCNT) technology along with genetic engineering of nuclear donor cells provides a unique opportunity for examining human diseases using transgenic canines. In the present study, we generated transgenic canines that overexpressed the human amyloid precursor protein (APP) gene containing well-characterized familial Alzheimer's disease (AD) mutations. We successfully obtained five out of six live puppies by SCNT. This was confirmed by observing the expression of green fluorescence protein in the body as a visual transgenic marker and the overexpression of the mutated APP gene in the brain. The transgenic canines developed AD-like symptoms, such as enlarged ventricles, an atrophied hippocampus, and β-amyloid plaques in the brain. Thus, the transgenic canines we created can serve as a novel animal model for studying human AD.

There’s an App for That: A Guide for Healthcare Practitioners and Researchers on Smartphone Technology

PubMed Central

Trevena, Lyndal

2015-01-01

Smartphone technology is nascent compared to other technologies; however, it has shown an unprecedented uptake amongst lay consumers and professionals. This article presents the history, components, and key features of smartphones, as well as their related concepts and how they work, and it also delineates the process of smartphone applications (apps) development and publishing in the app stores. It also describes and discusses smartphone technology utilisation for health consumers, healthcare professionals, and health researchers, as well as the regulations of health-related apps. PMID:26392848

Use of and Beliefs About Mobile Phone Apps for Diabetes Self-Management: Surveys of People in a Hospital Diabetes Clinic and Diabetes Health Professionals in New Zealand.

PubMed

Boyle, Leah; Grainger, Rebecca; Hall, Rosemary M; Krebs, Jeremy D

2017-06-30

People with diabetes mellitus (DM) are using mobile phone apps to support self-management. The numerous apps available to assist with diabetes management have a variety of functions. Some functions, like insulin dose calculators, have significant potential for harm. The study aimed to establish (1) whether people with DM in Wellington, New Zealand, use apps for DM self-management and evaluate desirable features of apps and (2) whether health professionals (HPs) in New Zealand treating people with DM recommend apps to patients, the features HPs regard as important, and their confidence with recommending apps. A survey of patients seen at a hospital diabetes clinic over 12 months (N=539) assessed current app use and desirable features. A second survey of HPs attending a diabetes conference (n=286) assessed their confidence with app recommendations and perceived usefulness. Of the 189 responders (35.0% response rate) to the patient survey, 19.6% (37/189) had used a diabetes app. App users were younger and in comparison to other forms of diabetes mellitus, users prominently had type 1 DM. The most favored feature of the app users was a glucose diary (87%, 32/37), and an insulin calculator was the most desirable function for a future app (46%, 17/37). In non-app users, the most desirable feature for a future app was a glucose diary (64.4%, 98/152). Of the 115 responders (40.2% response rate) to the HPs survey, 60.1% (68/113) had recommended a diabetes app. Diaries for blood glucose levels and carbohydrate counting were considered the most useful app features and the features HPs felt most confident to recommend. HPs were least confident in recommending insulin calculation apps. The use of apps to record blood glucose was the most favored function in apps used by people with diabetes, with interest in insulin dose calculating function. HPs do not feel confident in recommending insulin dose calculators. There is an urgent need for an app assessment process to give confidence in the quality and safety of diabetes management apps to people with diabetes (potential app users) and HPs (potential app prescribers). ©Leah Boyle, Rebecca Grainger, Rosemary M Hall, Jeremy D Krebs. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 30.06.2017.

Development of an Ecological Momentary Assessment Mobile App for a Low-Literacy, Mexican American Population to Collect Disordered Eating Behaviors

PubMed Central

Stein, Karen F; Chaudry, Beenish; Trabold, Nicole

2016-01-01

Background Ecological momentary assessment (EMA) is a popular method for understanding population health in which participants report their experiences while in naturally occurring contexts in order to increase the reliability and ecological validity of the collected data (as compared to retrospective recall). EMA studies, however, have relied primarily on text-based questionnaires, effectively eliminating low-literacy populations from the samples. Objective To provide a case study of design of an EMA mobile app for a low-literacy population. In particular, we present the design process and final design of an EMA mobile app for low literate, Mexican American women to record unhealthy eating and weight control behaviors (UEWCBs). Methods An iterative, user-centered design process was employed to develop the mobile app. An existing EMA protocol to measure UEWCBs in college-enrolled Mexican American women was used as the starting point for the application. The app utilizes an icon interface, with optional audio prompts, that is culturally sensitive and usable by a low-literacy population. A total of 41 women participated over the course of 4 phases of the design process, which included 2 interview and task-based phases (n=8, n=11), focus groups (n=15), and a 5-day, in situ deployment (n=7). Results Participants’ mental models of UEWCBs differed substantially from prevailing definitions found in the literature, prompting a major reorganization of the app interface. Differences in health literacy and numeracy were better identified with the Newest Vital Sign tool, as compared with the Short Assessment of Health Literacy tool. Participants had difficulty imagining scenarios in the interviews to practice recording a specific UEWCB; instead, usability was best tested in situ. Participants were able to use the EMA mobile app over the course of 5 days to record UEWCBs. Conclusions Results suggest that the iterative, user-centered design process was essential for designing the app to be made usable by the target population. Simply taking the protocol designed for a higher-literacy population and replacing words with icons and/or audio would have been unsuccessful with this population. PMID:27418020

Oiling the gate: a mobile application to improve the admissions process from the emergency department to an academic community hospital inpatient medicine service.

PubMed

Fung, Russell; Hyde, Jensen Hart; Davis, Mike

2018-01-01

The process of admitting patients from the emergency department (ED) to an academic internal medicine (AIM) service in a community teaching hospital is one fraught with variability and disorder. This results in an inconsistent volume of patients admitted to academic versus private hospitalist services and results in frustration of both ED and AIM clinicians. We postulated that implementation of a mobile application (app) would improve provider satisfaction and increase admissions to the academic service. The app was designed and implemented to be easily accessible to ED physicians, regularly updated by academic residents on call, and a real-time source of the number of open AIM admission spots. We found a significant improvement in ED and AIM provider satisfaction with the admission process. There was also a significant increase in admissions to the AIM service after implementation of the app. We submit that the implementation of a mobile app is a viable, cost-efficient, and effective method to streamline the admission process from the ED to AIM services at community-based hospitals.

Comparative study of the effects of phosphatidylcholine rich in DHA and EPA on Alzheimer's disease and the possible mechanisms in CHO-APP/PS1 cells and SAMP8 mice.

PubMed

Che, Hongxia; Zhou, Miaomiao; Zhang, Tiantian; Zhang, Lingyu; Ding, Lin; Yanagita, Teruyoshi; Xu, Jie; Xue, Changhu; Wang, Yuming

2018-01-24

Metabolic stress induced by a high-fat (HF) diet leads to cognitive dysfunction and aging. In the present study, Chinese hamster ovary cells stably transfected with amyloid precursor protein (APP) and presenilin 1 (PS1) (CHO-APP/PS1 cells) and SAMP8 mice fed with an HF diet were used to study the effects of docosahexaenoic acid (DHA)-enriched phosphatidylcholine (DHA-PC) and eicosapentaenoic acid (EPA)-enriched phosphatidylcholine (EPA-PC) on Alzheimer's disease (AD) and the possible mechanisms involved in these effects. Behavior test results indicated that DHA-PC exerted better effects than EPA-PC on improving memory and cognitive deficiency. Further analysis showed that DHA-PC and EPA-PC could significantly decrease β-amyloid (Aβ) concentrations in CHO-APP/PS1 cells and SAMP8 mice by inhibiting APP, PS1, and BACE1 expression. Moreover, both DHA-PC and EPA-PC can increase the activities of the antioxidant index, including SOD, T-AOC, GSH, and GSH-PX, and inhibit levels of MDA, NO, and NOS. In addition, the expressions of inflammatory factors (TNF-α, IL-1β) and apoptosis were significantly suppressed via improving the ratio of Bcl-2/Bax and decreasing the expression of pro-apoptosis factors. Interestingly, only DHA-PC could improve the expression of neurotrophic factors, including BDNF, synaptophysin, and growth associated protein 43. DHA-PC and EPA-PC could ameliorate memory and cognitive function of HF diet-fed SAMP8 mice via inhibiting Aβ generation, suppressing oxidative stress and apoptosis, down-regulating inflammatory response, and improving neurotrophic activity. Therefore, DHA-PC and EPA-PC may be applied as food supplements and/or functional ingredients to relieve neurodegenerative disease.

Amyloid Precursor Protein 96–110 and β-Amyloid 1–42 Elicit Developmental Anomalies in Sea Urchin Embryos and Larvae that are Alleviated by Neurotransmitter Analogs for Acetylcholine, Serotonin and Cannabinoids

PubMed Central

Buznikov, Gennady A.; Nikitina, Lyudmila A.; Seidler, Frederic J.; Slotkin, Theodore A.; Bezuglov, Vladimir V.; Milošević, Ivan; Lazarević, Lidija; Rogač, Ljubica; Ruzdijić, Sabera; Rakić, Ljubiša M.

2008-01-01

Amyloid precursor protein (APP) is overexpressed in the developing brain and portions of its extracellular domain, especially amino acid residues 96–110, play an important role in neurite outgrowth and neural cell differentiation. In the current study, we evaluated the developmental abnormalities caused by administration of exogenous APP96–110 in sea urchin embryos and larvae, which, like the developing mammalian brain, utilize acetylcholine and other neurotransmitters as morphogens; effects were compared to those of β-amyloid 1–42 (Aβ42), the neurotoxic APP fragment contained within neurodegenerative plaques in Alzheimer’s Disease. Although both peptides elicited dysmorphogenesis, Aβ42 was far more potent; in addition, whereas Aβ42 produced abnormalities at developmental stages ranging from early cleavage divisions to the late pluteus, APP96–110 effects were restricted to the intermediate, mid-blastula stage. For both agents, anomalies were prevented or reduced by addition of lipid-permeable analogs of acetylcholine, serotonin or cannabinoids; physostigmine, a carbamate-derived cholinesterase inhibitor, was also effective. In contrast, agents that act on NMDA receptors (memantine) or α-adrenergic receptors (nicergoline), and that are therapeutic in Alzheimer’s Disease, were themselves embryotoxic, as was tacrine, a cholinesterase inhibitor from a different chemical class than physostigmine. Protection was also provided by agents acting downstream from receptor-mediated events: increasing cyclic AMP with caffeine or isobutylmethylxanthine, or administering the antioxidant, α-tocopherol, were all partially effective. Our findings reinforce a role for APP in development and point to specific interactions with neurotransmitter systems that act as morphogens in developing sea urchins as well as in the mammalian brain. PMID:18565728

Impairment of fragile X mental retardation protein-metabotropic glutamate receptor 5 signaling and its downstream cognates ras-related C3 botulinum toxin substrate 1, amyloid beta A4 precursor protein, striatal-enriched protein tyrosine phosphatase, and homer 1, in autism: a postmortem study in cerebellar vermis and superior frontal cortex

PubMed Central

2013-01-01

Background Candidate genes associated with idiopathic forms of autism overlap with other disorders including fragile X syndrome. Our laboratory has previously shown reduction in fragile X mental retardation protein (FMRP) and increase in metabotropic glutamate receptor 5 (mGluR5) in cerebellar vermis and superior frontal cortex (BA9) of individuals with autism. Methods In the current study we have investigated expression of four targets of FMRP and mGluR5 signaling - homer 1, amyloid beta A4 precursor protein (APP), ras-related C3 botulinum toxin substrate 1 (RAC1), and striatal-enriched protein tyrosine phosphatase (STEP) - in the cerebellar vermis and superior frontal cortex (BA9) via SDS-PAGE and western blotting. Data were analyzed based on stratification with respect to age (children and adolescents vs. adults), anatomic region of the brain (BA9 vs. cerebellar vermis), and impact of medications (children and adolescents on medications (n = 4) vs. total children and adolescents (n = 12); adults on medications (n = 6) vs. total adults (n = 12)). Results There were significant increases in RAC1, APP 120 kDa and APP 80 kDa proteins in BA9 of children with autism vs. healthy controls. None of the same proteins were significantly affected in cerebellar vermis of children with autism. In BA9 of adults with autism there were significant increases in RAC1 and STEP 46 kDa and a significant decrease in homer 1 vs. controls. In the vermis of adult subjects with autism, RAC1 was significantly increased while APP 120, STEP 66 kDa, STEP 27 kDa, and homer 1 were significantly decreased when compared with healthy controls. No changes were observed in vermis of children with autism. There was a significant effect of anticonvulsant use on STEP 46 kDa/β-actin and a potential effect on homer 1/NSE, in BA9 of adults with autism. However, no other significant confound effects were observed in this study. Conclusions Our findings provide further evidence of abnormalities in FMRP and mGluR5 signaling partners in brains of individuals with autism and open the door to potential targeted treatments which could help ameliorate the symptoms of autism. PMID:23803181

Application of Ferulic Acid for Alzheimer’s Disease: Combination of Text Mining and Experimental Validation

PubMed Central

Meng, Guilin; Meng, Xiulin; Ma, Xiaoye; Zhang, Gengping; Hu, Xiaolin; Jin, Aiping; Liu, Xueyuan

2018-01-01

Alzheimer’s disease (AD) is an increasing concern in human health. Despite significant research, highly effective drugs to treat AD are lacking. The present study describes the text mining process to identify drug candidates from a traditional Chinese medicine (TCM) database, along with associated protein target mechanisms. We carried out text mining to identify literatures that referenced both AD and TCM and focused on identifying compounds and protein targets of interest. After targeting one potential TCM candidate, corresponding protein-protein interaction (PPI) networks were assembled in STRING to decipher the most possible mechanism of action. This was followed by validation using Western blot and co-immunoprecipitation in an AD cell model. The text mining strategy using a vast amount of AD-related literature and the TCM database identified curcumin, whose major component was ferulic acid (FA). This was used as a key candidate compound for further study. Using the top calculated interaction score in STRING, BACE1 and MMP2 were implicated in the activity of FA in AD. Exposure of SHSY5Y-APP cells to FA resulted in the decrease in expression levels of BACE-1 and APP, while the expression of MMP-2 and MMP-9 increased in a dose-dependent manner. This suggests that FA induced BACE1 and MMP2 pathways maybe novel potential mechanisms involved in AD. The text mining of literature and TCM database related to AD suggested FA as a promising TCM ingredient for the treatment of AD. Potential mechanisms interconnected and integrated with Aβ aggregation inhibition and extracellular matrix remodeling underlying the activity of FA were identified using in vitro studies. PMID:29896095

Application of Ferulic Acid for Alzheimer's Disease: Combination of Text Mining and Experimental Validation.

PubMed

Meng, Guilin; Meng, Xiulin; Ma, Xiaoye; Zhang, Gengping; Hu, Xiaolin; Jin, Aiping; Zhao, Yanxin; Liu, Xueyuan

2018-01-01

Alzheimer's disease (AD) is an increasing concern in human health. Despite significant research, highly effective drugs to treat AD are lacking. The present study describes the text mining process to identify drug candidates from a traditional Chinese medicine (TCM) database, along with associated protein target mechanisms. We carried out text mining to identify literatures that referenced both AD and TCM and focused on identifying compounds and protein targets of interest. After targeting one potential TCM candidate, corresponding protein-protein interaction (PPI) networks were assembled in STRING to decipher the most possible mechanism of action. This was followed by validation using Western blot and co-immunoprecipitation in an AD cell model. The text mining strategy using a vast amount of AD-related literature and the TCM database identified curcumin, whose major component was ferulic acid (FA). This was used as a key candidate compound for further study. Using the top calculated interaction score in STRING, BACE1 and MMP2 were implicated in the activity of FA in AD. Exposure of SHSY5Y-APP cells to FA resulted in the decrease in expression levels of BACE-1 and APP, while the expression of MMP-2 and MMP-9 increased in a dose-dependent manner. This suggests that FA induced BACE1 and MMP2 pathways maybe novel potential mechanisms involved in AD. The text mining of literature and TCM database related to AD suggested FA as a promising TCM ingredient for the treatment of AD. Potential mechanisms interconnected and integrated with Aβ aggregation inhibition and extracellular matrix remodeling underlying the activity of FA were identified using in vitro studies.

Gastrodin Attenuates Bilateral Common Carotid Artery Occlusion-Induced Cognitive Deficits via Regulating Aβ-Related Proteins and Reducing Autophagy and Apoptosis in Rats

PubMed Central

Liu, Bo; Gao, Jian-Mei; Li, Fei; Gong, Qi-Hai; Shi, Jing-Shan

2018-01-01

Gastrodin (GAS), an active constituent extracted from Gastrodia elata Blume, is used to treat ischemic stroke, epilepsy, dizziness, and dementia for centuries in China. This study examined its effects on vascular dementia (VD) and the underlying molecular mechanisms. VD was established by ligation of bilateral common carotid artery occlusion (BCCAO). A total of 7 days after BCCAO surgery, GAS (15, 30, and 60 mg/kg) was orally administered for 28 consecutive days to evaluate therapeutic effects. Cognitive function was tested by the Morris water maze. The neuronal morphological changes were examined via Hematoxylin–Eosin staining. Flow cytometry was used for evaluating apoptosis in the hippocampi. The target protein expression was examined by Western blot. The results showed that BCCAO induced cognitive impairment, hippocampus CA1 and CA3 pyramidal neuron damage, beta-amyloid (Aβ) deposition, excessive autophagy, and apoptosis. GAS treatment significantly improved BCCAO-induced cognitive deficits and hippocampus neuron damage. Molecular analysis revealed that GAS exerted the protective effect via reducing the levels of Aβ1–40/42, APP, and β-site APP-cleaving enzyme 1 expression, and increasing Aβ-related protein, a disintegrin and metalloprotease 10, and insulin degrading enzyme expression. Meanwhile, GAS inhibited excessive autophagy via decreasing Beclin-1, LC3-II, and p62 levels. Furthermore, GAS inhibited apoptosis through the downregulation of Bax and upregulation of Bcl-2. Moreover, P38 MAPK signaling pathway was involved in the process. Our findings demonstrate that GAS was effective in the treatment of BCCAO-induced VD via targeting Aβ-related protein formation and inhibiting autophagy and apoptosis of hippocampus neurons. PMID:29755351

Modelling APOE ɛ3/4 allele-associated sporadic Alzheimer's disease in an induced neuron.

PubMed

Kim, Hongwon; Yoo, Junsang; Shin, Jaein; Chang, Yujung; Jung, Junghyun; Jo, Dong-Gyu; Kim, Janghwan; Jang, Wonhee; Lengner, Christopher J; Kim, Byung-Soo; Kim, Jongpil

2017-08-01

The recent generation of induced neurons by direct lineage conversion holds promise for in vitro modelling of sporadic Alzheimer's disease. Here, we report the generation of induced neuron-based model of sporadic Alzheimer's disease in mice and humans, and used this system to explore the pathogenic mechanisms resulting from the sporadic Alzheimer's disease risk factor apolipoprotein E (APOE) ɛ3/4 allele. We show that mouse and human induced neurons overexpressing mutant amyloid precursor protein in the background of APOE ɛ3/4 allele exhibit altered amyloid precursor protein (APP) processing, abnormally increased production of amyloid-β42 and hyperphosphorylation of tau. Importantly, we demonstrate that APOE ɛ3/4 patient induced neuron culture models can faithfully recapitulate molecular signatures seen in APOE ɛ3/4-associated sporadic Alzheimer's disease patients. Moreover, analysis of the gene network derived from APOE ɛ3/4 patient induced neurons reveals a strong interaction between APOE ɛ3/4 and another Alzheimer's disease risk factor, desmoglein 2 (DSG2). Knockdown of DSG2 in APOE ɛ3/4 induced neurons effectively rescued defective APP processing, demonstrating the functional importance of this interaction. These data provide a direct connection between APOE ɛ3/4 and another Alzheimer's disease susceptibility gene and demonstrate in proof of principle the utility of induced neuron-based modelling of Alzheimer's disease for therapeutic discovery. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Genetic Ablation of Apolipoprotein A-IV Accelerates Alzheimer's Disease Pathogenesis in a Mouse Model

PubMed Central

Cui, Yujie; Huang, Mingwei; He, Yingbo; Zhang, Shuyan; Luo, Yongzhang

2011-01-01

The link between lipoprotein metabolism and Alzheimer's disease (AD) has been established. Apolipoprotein A-IV (apoA-IV), a component of lipoprotein particles similar to apolipoprotein E, has been suggested to play an important role in brain metabolism. Although there are clinical debates on the function of its polymorphism in AD, the pathologic role of apoA-IV in AD is still unknown. Here, we report that genetic ablation of apoA-IV is able to accelerate AD pathogenesis in mice. In a mouse model that overexpresses human amyloid precursor protein (APP) and presenilin 1, genetic reduction of apoA-IV augments extracellular amyloid-β peptide (Aβ) burden and aggravates neuron loss in the brain. In addition, genetic ablation of apoA-IV also accelerates spatial learning deficits and increases the mortality of mice. We have found that apoA-IV colocalizes within Aβ plaques in APP/presenilin 1 transgenic mice and binds to Aβ in vitro. Subsequent studies show that apoA-IV in this model facilitates Aβ uptake in the Aβ clearance pathway mediated by astrocytes rather than the amyloidogenic pathway of APP processing. Taken together, we conclude that apoA-IV deficiency increases Aβ deposition and results in cognitive damage in the mouse model. Enhancing levels of apoA-IV may have therapeutic potential in AD treatment. PMID:21356380