scholarly journals The inhibition of cellular toxicity of amyloid-beta by dissociated transthyretin

2019 ◽  
Author(s):  
Qin Cao ◽  
Daniel H. Anderson ◽  
Wilson Liang ◽  
Joshua Chou ◽  
Lorena Saelices
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Beta ◽  
Amyloid Plaques ◽  
Inhibitory Effect ◽  
Aβ Oligomers ◽  
Transthyretin Amyloidosis ◽  
Cellular Toxicity ◽  
Aβ Aggregation

AbstractThe protective effect of transthyretin (TTR) on cellular toxicity of amyloid-beta (Aβ) has been previously reported. TTR is a tetrameric carrier of thyroxine in blood and cerebrospinal fluid, whose pathogenic aggregation causes systemic amyloidosis. In contrast, many reports have shown that TTR binds amyloid-beta (Aβ), associated with Alzheimer’s disease, alters its aggregation, and inhibits its toxicity both in vitro and in vivo. In this study, we question whether TTR amyloidogenic ability and its anti-amyloid inhibitory effect are associated. Our results indicate that the dissociation of the TTR tetramer, required for its amyloid pathogenesis, is also necessary to prevent cellular toxicity from Aβ oligomers. These findings suggest that the Aβ binding site of TTR may be hidden in its tetrameric form. Aided by computational docking and peptide screening, we identified a TTR segment that is capable of altering Aβ aggregation and toxicity, mimicking TTR cellular protection. This segment inhibits Aβ oligomer formation and also promotes the formation of non-toxic, non-amyloid, amorphous aggregates which are more sensitive to protease digestion. This segment also inhibits seeding of Aβ catalyzed by Aβ fibrils extracted from the brain of an Alzheimer’s patient. Our results suggest that mimicking the inhibitory effect of TTR with peptide-based therapeutics represents an additional avenue to explore for the treatment of Alzheimer’s disease.Significance statementThe pathological landmarks of Alzheimer’s disease are the formation of amyloid plaques and neurofibrillary tangles. Amyloid plaques contain fibrous structures made of aggregated amyloid-beta (Aβ). In 1982, Shirahama and colleagues observed the presence of transthyretin (TTR) in these plaques. TTR is a tetrameric protein whose aggregation causes transthyretin amyloidosis. However, TTR protects Aβ from aggregating and causing toxicity to neurons. In this study, we show that the dissociation of TTR tetramers is required to inhibit cellular toxicity caused by Aβ. In addition, we identified a minimum segment of TTR that inhibits Aβ aggregation and cellular toxicity by the formation of amorphous aggregates that are sensitive to proteases, similar to the natural effect of TTR found by others in vivo.

scholarly journals The inhibition of cellular toxicity of amyloid-β by dissociated transthyretin

2020 ◽  
Vol 295 (41) ◽  
pp. 14015-14024 ◽  
Author(s):  
Qin Cao ◽  
Daniel H. Anderson ◽  
Wilson Y. Liang ◽  
Joshua Chou ◽  
Lorena Saelices
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Protective Effect ◽  
Amyloid Β ◽  
Inhibitory Effect ◽  
Aβ Oligomers ◽  
Cellular Toxicity ◽  
Computational Docking

The protective effect of transthyretin (TTR) on cellular toxicity of β-amyloid (Aβ) has been previously reported. TTR is a tetrameric carrier of thyroxine in blood and cerebrospinal fluid, the pathogenic aggregation of which causes systemic amyloidosis. However, studies have documented a protective effect of TTR against cellular toxicity of pathogenic Aβ, a protein associated with Alzheimer's disease. TTR binds Aβ, alters its aggregation, and inhibits its toxicity both in vitro and in vivo. In this study, we investigate whether the amyloidogenic ability of TTR and its antiamyloid inhibitory effect are associated. Using protein aggregation and cytotoxicity assays, we found that the dissociation of the TTR tetramer, required for its amyloid pathogenesis, is also necessary to prevent cellular toxicity from Aβ oligomers. These findings suggest that the Aβ-binding site of TTR may be hidden in its tetrameric form. Aided by computational docking and peptide screening, we identified a TTR segment that is capable of altering Aβ aggregation and toxicity, mimicking TTR cellular protection. EM, immune detection analysis, and assessment of aggregation and cytotoxicity revealed that the TTR segment inhibits Aβ oligomer formation and also promotes the formation of nontoxic, nonamyloid amorphous aggregates, which are more sensitive to protease digestion. Finally, this segment also inhibits seeding of Aβ catalyzed by Aβ fibrils extracted from the brain of an Alzheimer's patient. Together, these findings suggest that mimicking the inhibitory effect of TTR with peptide-based therapeutics represents an additional avenue to explore for the treatment of Alzheimer's disease.

A Multifunctional Chemical Agent as an Attenuator of Amyloid and Tau Burden and Neuroinflammation in Alzheimer’s Disease

2019 ◽  
Author(s):  
Hong-Jun Cho ◽  
Anuj K. Sharma ◽  
Ying Zhang ◽  
Michael L. Gross ◽  
Liviu M. Mirica
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Metal Binding ◽  
Amyloid Plaques ◽  
Chemical Agent ◽  
Aβ Oligomers ◽  
Neuroinflammatory Response ◽  
Aβ Aggregation ◽  
5Xfad Mice

<div>Alzheimer’s disease (AD) is the most common neurodegenerative degenerative disease, and its main hallmark is the deposition of amyloid beta (Aβ) peptides. However, several clinical trials focusing on Aβ-targeting agents have failed recently, and thus new therapeutic leads are focusing on alternate targets such as tau protein pathology, Aβ-metal induced oxidative stress, and neuroinflammation. To address these different pathological aspects of AD, we have employed a multifunctional compound (MFC) L1 that integrates Aβ-interacting and metal-binding functional groups in a single molecular framework. By perturbing the interactions between the Aβ species and metal ions during the Aβ aggregation process, L1 alleviates the formation of neurotoxic Aβ oligomers and promotes the formation of nontoxic, amorphous Aβ aggregates. Furthermore, the significant antioxidant activity and strong metal chelating ability of L1 are operating cooperatively to rescue neuroblastoma N2A cells from Cu2+-induced Aβ neurotoxicity. Along with in vivo Aβ-binding and favorable BBB permeability properties, the treatment of transgenic 5xFAD mice with L1 significantly reduces the amount of both amyloid plaques and associated phosphorylated tau (p-tau) aggregates in the brain by 40–50% versus the vehicle-treated 5xFAD mice. Besides, L1 mitigates the neuroinflammatory response of the activated microglia during the Aβ-induced inflammation process. Overall, these results suggest that L1 not only efficiently attenuates the formation of amyloid plaques and p-tau aggregates in vivo, but also reduces the microgliamediated neuroinflammatory response, which is quite uncommon among the previously reported amyloid-targeting chemical agents, and thus L1 could be envisioned as a lead compound for the development of novel AD therapeutics.</div>

A Multifunctional Chemical Agent as an Attenuator of Amyloid and Tau Burden and Neuroinflammation in Alzheimer’s Disease

2019 ◽  
Author(s):  
Hong-Jun Cho ◽  
Anuj K. Sharma ◽  
Ying Zhang ◽  
Michael L. Gross ◽  
Liviu M. Mirica
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Metal Binding ◽  
Amyloid Plaques ◽  
Chemical Agent ◽  
Aβ Oligomers ◽  
Neuroinflammatory Response ◽  
Aβ Aggregation ◽  
5Xfad Mice

<div>Alzheimer’s disease (AD) is the most common neurodegenerative degenerative disease, and its main hallmark is the deposition of amyloid beta (Aβ) peptides. However, several clinical trials focusing on Aβ-targeting agents have failed recently, and thus new therapeutic leads are focusing on alternate targets such as tau protein pathology, Aβ-metal induced oxidative stress, and neuroinflammation. To address these different pathological aspects of AD, we have employed a multifunctional compound (MFC) L1 that integrates Aβ-interacting and metal-binding functional groups in a single molecular framework. By perturbing the interactions between the Aβ species and metal ions during the Aβ aggregation process, L1 alleviates the formation of neurotoxic Aβ oligomers and promotes the formation of nontoxic, amorphous Aβ aggregates. Furthermore, the significant antioxidant activity and strong metal chelating ability of L1 are operating cooperatively to rescue neuroblastoma N2A cells from Cu2+-induced Aβ neurotoxicity. Along with in vivo Aβ-binding and favorable BBB permeability properties, the treatment of transgenic 5xFAD mice with L1 significantly reduces the amount of both amyloid plaques and associated phosphorylated tau (p-tau) aggregates in the brain by 40–50% versus the vehicle-treated 5xFAD mice. Besides, L1 mitigates the neuroinflammatory response of the activated microglia during the Aβ-induced inflammation process. Overall, these results suggest that L1 not only efficiently attenuates the formation of amyloid plaques and p-tau aggregates in vivo, but also reduces the microgliamediated neuroinflammatory response, which is quite uncommon among the previously reported amyloid-targeting chemical agents, and thus L1 could be envisioned as a lead compound for the development of novel AD therapeutics.</div>

scholarly journals In vivo multi-parametric manganese-enhanced MRI for detecting amyloid plaques in rodent models of Alzheimer’s disease

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Eugene Kim ◽  
Davide Di Censo ◽  
Mattia Baraldo ◽  
Camilla Simmons ◽  
Ilaria Rosa ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Plaques ◽  
Transgenic Animals ◽  
Surrounding Tissue ◽  
Rodent Models ◽  
Enhanced Mri ◽  
5Xfad Mice ◽  
Manganese Enhanced Mri

AbstractAmyloid plaques are a hallmark of Alzheimer’s disease (AD) that develop in its earliest stages. Thus, non-invasive detection of these plaques would be invaluable for diagnosis and the development and monitoring of treatments, but this remains a challenge due to their small size. Here, we investigated the utility of manganese-enhanced MRI (MEMRI) for visualizing plaques in transgenic rodent models of AD across two species: 5xFAD mice and TgF344-AD rats. Animals were given subcutaneous injections of MnCl2 and imaged in vivo using a 9.4 T Bruker scanner. MnCl2 improved signal-to-noise ratio but was not necessary to detect plaques in high-resolution images. Plaques were visible in all transgenic animals and no wild-types, and quantitative susceptibility mapping showed that they were more paramagnetic than the surrounding tissue. This, combined with beta-amyloid and iron staining, indicate that plaque MR visibility in both animal models was driven by plaque size and iron load. Longitudinal relaxation rate mapping revealed increased manganese uptake in brain regions of high plaque burden in transgenic animals compared to their wild-type littermates. This was limited to the rhinencephalon in the TgF344-AD rats, while it was most significantly increased in the cortex of the 5xFAD mice. Alizarin Red staining suggests that manganese bound to plaques in 5xFAD mice but not in TgF344-AD rats. Multi-parametric MEMRI is a simple, viable method for detecting amyloid plaques in rodent models of AD. Manganese-induced signal enhancement can enable higher-resolution imaging, which is key to visualizing these small amyloid deposits. We also present the first in vivo evidence of manganese as a potential targeted contrast agent for imaging plaques in the 5xFAD model of AD.

Is Olfactory Epithelium Biopsy Useful for Confirming Alzheimer’s Disease?

2018 ◽  
Vol 128 (3) ◽  
pp. 184-192 ◽  
Author(s):  
Maria Dantas Costa Lima Godoy ◽  
Marco Aurélio Fornazieri ◽  
Richard L. Doty ◽  
Fábio de Rezende Pinna ◽  
José Marcelo Farfel ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Beta ◽  
Olfactory Epithelium ◽  
Clinical Symptoms ◽  
Middle Turbinate ◽  
Superior Turbinate ◽  
Significant Difference ◽  
Amyloid Beta Proteins

Objectives: The clinical symptoms of Alzheimer’s disease (AD) are preceded by a long asymptomatic period associated with “silent” deposition of aberrant paired helical filament (PHF)-tau and amyloid-beta proteins in brain tissue. Similar depositions have been reported within the olfactory epithelium (OE), a tissue that can be biopsied in vivo. The degree to which such biopsies are useful in identifying AD is controversial. This postmortem study had 3 main goals: first, to quantify the relative densities of AD-related proteins in 3 regions of the olfactory neuroepithelium, namely, the nasal septum, middle turbinate, and superior turbinate; second, to establish whether such densities are correlated among these epithelial regions as well as with semi-quantitative ratings of general brain cortex pathology; and third, to evaluate correlations between the protein densities and measures of antemortem cognitive function. Methods: Postmortem blocks of olfactory mucosa were obtained from 12 AD cadavers and 24 controls and subjected to amyloid-beta and PHF-tau immunohistochemistry. Results: We observed marked heterogeneity in the presence of the biomarkers of tau and amyloid-beta among the targeted olfactory epithelial regions. No significant difference was observed between the cadavers with AD and the controls regarding the concentration of these proteins in any of these epithelial regions. Only one correlation significant was evident, namely, that between the tau protein densities of the middle and the upper turbinate ( r = .58, P = .002). Conclusion: AD-related biomarker heterogeneity, which has not been previously demonstrated, makes comparisons across studies difficult and throws into question the usefulness of OE amyloid-beta and PHF-tau biopsies in detecting AD.

scholarly journals Transcranial in vivo detection of amyloid-beta at single plaque resolution with large-field multifocal illumination fluorescence microscopy

2020 ◽  
Author(s):  
Ruiqing Ni ◽  
Zhenyue Chen ◽  
Gloria Shi ◽  
Alessia Villois ◽  
Quanyu Zhou ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Fluorescence Microscopy ◽  
Amyloid Beta ◽  
Large Field ◽  
Microscopy Technique ◽  
In Vivo Detection ◽  
Amyloid Deposits ◽  
Microscopy Techniques

AbstractThe abnormal deposition of beta-amyloid proteins in the brain is one of the major histopathological hallmarks of Alzheimer’s disease. Currently available intravital microscopy techniques for high-resolution plaque visualization commonly involve highly invasive procedures and are limited to a small field-of-view within the rodent brain. Here, we report the transcranial detection of amyloid-beta deposits at the whole brain scale with 20 μm resolution in APP/PS1 and arcAβ mouse models of Alzheimer’s disease amyloidosis using a large-field multifocal (LMI) fluorescence microscopy technique. Highly sensitive and specific detection of amyloid-beta deposits at a single plaque level in APP/PS1 and arcAβ mice was facilitated using luminescent conjugated oligothiophene HS-169. Immunohistochemical staining with HS-169, anti-Aβ antibody 6E10, and conformation antibodies OC (fibrillar) of brain tissue sections further showed that HS-169 resolved compact parenchymal and vessel-associated amyloid deposits. The novel imaging platform offers new prospects for in vivo studies into Alzheimer’s disease mechanisms in animal models as well as longitudinal monitoring of therapeutic responses at a single plaque level.

scholarly journals Cu-Based Turn-on Fluorescent Sensors for Cu-rich Amyloid β Aggregates

2021 ◽  
Author(s):  
Yiran Huang ◽  
Liang Sun ◽  
Liviu M. Mirica
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Fluorescence Imaging ◽  
Protein Misfolding ◽  
Picolinic Acid ◽  
Amyloid Β ◽  
Fluorescent Sensors ◽  
Aβ Oligomers ◽  
Turn On ◽  
Aβ Aggregation

<div>Protein misfolding and metal dishomeostasis are two key</div><div>pathological factors of Alzheimer’s disease. Previous studies have showed that Cu‐mediated Aβ aggregation pathways lead to formation of neurotoxic Aβ oligomers. Herein, we reported a series of picolinic acid‐based Cu‐activatable sensors, which can be used for the fluorescence imaging of Cu‐rich Aβ aggregates.</div>

scholarly journals Evaluation of Plant Phenolic Metabolites as a Source of Alzheimer's Drug Leads

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Yara Hassaan ◽  
Heba Handoussa ◽  
Ahmed H. El-Khatib ◽  
Michael W. Linscheid ◽  
Nesrine El Sayed ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Beta ◽  
Epidemiological Studies ◽  
Aqueous Alcohol ◽  
Alcohol Extract ◽  
Y Maze ◽  
Pharmacological Screening

Epidemiological studies have proven an association between consumption of polyphenols and prevention of Alzheimer’s disease, the most common form of dementia characterized by extracellular deposition of amyloid beta plaques. The aim of this study is pharmacological screening of the aqueous alcohol extract ofMarkhamia platycalyxleaves,Schotia brachypetalaleaves and stalks, and piceatannol compared to aqueous alcohol extract ofCamellia sinensisleaves as potential Alzheimer’s disease drugs. LC-HRESI(-ve)-MSnwas performed to identify phenolics’ profile ofSchotia brachypetalastalks aqueous alcohol extract and revealed ten phenolic compounds as first report: daidzein, naringin, procyanidin isomers, procyanidin dimer gallate, quercetin 3-O-rhamnoside, quercetin 3-O-glucuronide, quercetin hexose gallic acid, quercetin hexose protocatechuic acid, and ellagic acid. Alzheimer’s disease was induced by a single intraperitoneal injection of LPS. Adult male Swiss albino mice were divided into groups of 8–10 mice each receiving treatment for six days.In vivobehavioral tests (Y maze and object recognition) andin vitroestimation of amyloid beta 42 by ELISA showed significant differences between results of treated and nontreated animals.

In Vivo Magnetic Resonance of Amyloid Plaques in Alzheimer’s Disease Model Mice

2004 ◽  
pp. 47-59 ◽  
Author(s):  
Einar M. Sigurdsson ◽  
Youssef Zaim Wadghiri ◽  
Marcin Sadowski ◽  
James I. Elliott ◽  
Yongsheng Li ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Magnetic Resonance ◽  
Disease Model ◽  
Amyloid Plaques

scholarly journals SPON1 Can Reduce Amyloid Beta and Reverse Cognitive Impairment and Memory Dysfunction in Alzheimer’s Disease Mouse Model

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1275
Author(s):  
Soo Yong Park ◽  
Joo Yeong Kang ◽  
Taehee Lee ◽  
Donggyu Nam ◽  
Chang-Jin Jeon ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Amyloid Precursor Protein ◽  
Amyloid Beta ◽  
Physiological Activity ◽  
Precursor Protein ◽  
Age Related

Alzheimer’s disease (AD) is a complex, age-related neurodegenerative disease that is the most common form of dementia. However, the cure for AD has not yet been founded. The accumulation of amyloid beta (Aβ) is considered to be a hallmark of AD. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), also known as beta secretase is the initiating enzyme in the amyloidogenic pathway. Blocking BACE1 could reduce the amount of Aβ, but this would also prohibit the other functions of BACE1 in brain physiological activity. SPONDIN1 (SPON1) is known to bind to the BACE1 binding site of the amyloid precursor protein (APP) and blocks the initiating amyloidogenesis. Here, we show the effect of SPON1 in Aβ reduction in vitro in neural cells and in an in vivo AD mouse model. We engineered mouse induced neural stem cells (iNSCs) to express Spon1. iNSCs harboring mouse Spon1 secreted SPON1 protein and reduced the quantity of Aβ when co-cultured with Aβ-secreting Neuro 2a cells. The human SPON1 gene itself also reduced Aβ in HEK 293T cells expressing the human APP transgene with AD-linked mutations through lentiviral-mediated delivery. We also demonstrated that injecting SPON1 reduced the amount of Aβ and ameliorated cognitive dysfunction and memory impairment in 5xFAD mice expressing human APP and PSEN1 transgenes with five AD-linked mutations.

Sign in / Sign up

Export Citation Format

Share Document