scholarly journals Fibrillogenesis in Alzheimer's disease of amyloid β peptides and apolipoprotein E

1995 ◽  
Vol 306 (2) ◽  
pp. 599-604 ◽  
Author(s):  
E M Castano ◽  
F Prelli ◽  
T Wisniewski ◽  
A Golabek ◽  
R A Kumar ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Apolipoprotein E ◽  
Late Onset ◽  
Senile Plaques ◽  
Amyloid Β ◽  
Fibril Formation ◽  
Tau Proteins ◽  
Amyloid Formation

A central event in Alzheimer's disease is the conformational change from normally circulating soluble amyloid beta peptides (A beta) and tau proteins into amyloid fibrils, in the form of senile plaques and neurofibrillary tangles respectively. The apolipoprotein E (apoE) gene locus has recently been associated with late-onset Alzheimer's disease. It is not know whether apoE plays a direct role in the pathogenesis of the disease. In the present work we have investigated whether apoE can affect the known spontaneous in vitro formation of amyloid-like fibrils by synthetic A beta analogues using a thioflavine-T assay for fibril formation, electron microscopy and Congo Red staining. Our results show that, under the conditions used, apoE directly promotes amyloid fibril formation, increasing both the rate of fibrillogenesis and the total amount of amyloid formed. ApoE accelerated fibril formation of both wild-type A beta-(1-40) and A beta-(1-40A), an analogue created by the replacement of valine with alanine at residue 18, which alone produces few amyloid-like fibrils. However, apoE produced only a minimal effect on A beta-(1-40Q), found in the Dutch variant of Alzheimer's disease. When recombinant apoE isoforms were used, apoE4 was more efficient than apoE3 at enhancing amyloid formation. These in vitro observations support the hypothesis that apoE acts as a pathological chaperone, promoting the beta-pleated-sheet conformation of soluble A beta into amyloid fibres, and provide a possible explanation for the association of the apoE4 genetic isoform with Alzheimer's disease.

Poor Diet, Stress, and Inactivity Converge to Form a “Perfect Storm” That Drives Alzheimer’s Disease Pathogenesis

2019 ◽  
Vol 19 (2) ◽  
pp. 60-77 ◽  
Author(s):  
Anthony G. Pacholko ◽  
Caitlin A. Wotton ◽  
Lane K. Bekar
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Environmental Factors ◽  
Late Onset ◽  
Caloric Intake ◽  
Amyloid Β ◽  
Tau Proteins ◽  
Loss Of Function ◽  
Brain Insulin Resistance ◽  
Perfect Storm

North American incidence of Alzheimer’s disease (AD) is expected to more than double over the coming generation. Although genetic factors surrounding the production and clearance of amyloid-β and phosphorylated tau proteins are known to be responsible for a subset of early-onset AD cases, they do not explain the pathogenesis of the far more prevalent sporadic late-onset variant of the disease. It is thus likely that lifestyle and environmental factors contribute to neurodegenerative processes implicated in the pathogenesis of AD. Herein, we review evidence that (1) excess sucrose consumption induces AD-associated liver pathologies and brain insulin resistance, (2) chronic stress overdrives activity of locus coeruleus neurons, leading to loss of function (a common event in neurodegeneration), (3) high-sugar diets and stress promote the loss of neuroprotective sex hormones in men and women, and (4) Western dietary trends set the stage for a lithium-deficient state. We propose that these factors may intersect as part of a “perfect storm” to contribute to the widespread prevalence of neurodegeneration and AD. In addition, we put forth the argument that exercise and supplementation with trace lithium can counteract many of the deleterious consequences associated with excessive caloric intake and perpetual stress. We conclude that lifestyle and environmental factors likely contribute to AD pathogenesis and that simple lifestyle and dietary changes can help counteract their effects.

Anti-Neuroinflammatory Potential of Polyphenols by Inhibiting NF-κB to Halt Alzheimer's Disease

2020 ◽  
Vol 26 ◽  
Author(s):  
Md. Sahab Uddin ◽  
Sharifa Hasana ◽  
Jamil Ahmad ◽  
Md. Farhad Hossain ◽  
Md. Mosiqur Rahman ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Senile Plaques ◽  
Amyloid Β ◽  
Neuronal Loss ◽  
Research Area ◽  
Tau Proteins ◽  
Brain Disorder ◽  
Drug Candidates ◽  
Life Threatening

: Alzheimer's disease (AD) is an irrevocable chronic brain disorder featured by neuronal loss, microglial accumulation, and progressive cognitive impairment. The proper pathophysiology of this life-threatening disorder is not completely understood and no exact remedies are found yet. Over the last few decades, research on AD has mainly highlighted in pathomechanisms linked to a couple of the major pathological hallmarks, including extracellular senile plaques, made of amyloid-β (Aβ) peptides, and intracellular neurofibrillary tangles (NFTs), made of tau proteins. Aβ can induce apoptosis, trigger an inflammatory response, and inhibit the synaptic plasticity of the hippocampus, which ultimately contributes to reducing cognitive functions and memory impairment. Recently, a third disease hallmark, the neuroinflammatory reaction that is mediated by cerebral innate immune cells, has become a spotlight in the current research area, assured by pre-clinical, clinical, and genetic investigations. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a cytokine producer, is significantly associated with physiological inflammatory proceedings and thus showing a promising candidate for inflammation-based AD therapy. Recent data reveal that phytochemicals mainly polyphenols compounds exhibit potential neuroprotective functions and it may be considered as a vital resource for discovering several drug candidates against AD. Interestingly, phytochemicals can easily interfere with the signaling pathway of NF-κB. This review represents the anti-neuroinflammatory potential of polyphenols as inhibitors of NF-κB to combat AD pathogenesis.

scholarly journals Postmortem Neocortical 3H-PiB Binding and Levels of Unmodified and Pyroglutamate Aβ in Down Syndrome and Sporadic Alzheimer’s Disease

2021 ◽  
Vol 13 ◽  
Author(s):  
Violetta N. Pivtoraiko ◽  
Tamara Racic ◽  
Eric E. Abrahamson ◽  
Victor L. Villemagne ◽  
Benjamin L. Handen ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Down Syndrome ◽  
Late Onset ◽  
Amyloid Β ◽  
Molecular Profile ◽  
Amyloid Angiopathy ◽  
Neuritic Plaques ◽  
Amyloid Deposits

Individuals with Down syndrome (DS) have a genetic predisposition for amyloid-β (Aβ) overproduction and earlier onset of Aβ deposits compared to patients with sporadic late-onset Alzheimer’s disease (AD). Positron emission tomography (PET) with Pittsburgh Compound-B (PiB) detects fibrillar Aβ pathology in living people with DS and AD, but its relationship with heterogeneous Aβ forms aggregated within amyloid deposits is not well understood. We performed quantitative in vitro3H-PiB binding assays and enzyme-linked immunosorbent assays of fibrillar (insoluble) unmodified Aβ40 and Aβ42 forms and N-terminus truncated and pyroglutamate-modified AβNpE3-40 and AβNpE3-42 forms in postmortem frontal cortex and precuneus samples from 18 DS cases aged 43–63 years and 17 late-onset AD cases aged 62–99 years. Both diagnostic groups had frequent neocortical neuritic plaques, while the DS group had more severe vascular amyloid pathology (cerebral amyloid angiopathy, CAA). Compared to the AD group, the DS group had higher levels of Aβ40 and AβNpE3-40, while the two groups did not differ by Aβ42 and AβNpE3-42 levels. This resulted in lower ratios of Aβ42/Aβ40 and AβNpE3-42/AβNpE3-40 in the DS group compared to the AD group. Correlations of Aβ42/Aβ40 and AβNpE3-42/AβNpE3-40 ratios with CAA severity were strong in DS cases and weak in AD cases. Pyroglutamate-modified Aβ levels were lower than unmodified Aβ levels in both diagnostic groups, but within group proportions of both pyroglutamate-modified Aβ forms relative to both unmodified Aβ forms were lower in the DS group but not in the AD group. The two diagnostic groups did not differ by 3H-PiB binding levels. These results demonstrate that compared to late-onset AD cases, adult DS individuals with similar severity of neocortical neuritic plaques and greater CAA pathology have a preponderance of both pyroglutamate-modified AβNpE3-40 and unmodified Aβ40 forms. Despite the distinct molecular profile of Aβ forms and greater vascular amyloidosis in DS cases, cortical 3H-PiB binding does not distinguish between diagnostic groups that are at an advanced level of amyloid plaque pathology. This underscores the need for the development of CAA-selective PET radiopharmaceuticals to detect and track the progression of cerebral vascular amyloid deposits in relation to Aβ plaques in individuals with DS.

scholarly journals Apolipoprotein E Isoforms Differentially Regulate Alzheimer’s Disease and Amyloid-β-Induced Inflammatory Response in vivo and in vitro

2017 ◽  
Vol 57 (4) ◽  
pp. 1265-1279 ◽  
Author(s):  
Evan Dorey ◽  
Michelle Bamji-Mirza ◽  
Dema Najem ◽  
Yan Li ◽  
Hong Liu ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Inflammatory Response ◽  
Apolipoprotein E ◽  
Amyloid Β

Fragmentation of brain apolipoprotein E (ApoE) and its relevance in Alzheimer's disease

2020 ◽  
Vol 31 (6) ◽  
pp. 589-603 ◽  
Author(s):  
Asiamah Ernest Amponsah ◽  
Baofeng Feng ◽  
Ruiyun Guo ◽  
Wei Zhang ◽  
Jingjing He ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Apolipoprotein E ◽  
Neurofibrillary Tangles ◽  
Late Onset ◽  
Current Knowledge ◽  
Senile Plaques ◽  
The Elderly ◽  
Pathogenic Potential ◽  
Apoe Protein

AbstractAlzheimer's disease (AD) is a very common cause of dementia in the elderly. It is characterized by progressive amnesia and accretions of neurofibrillary tangles (NFTs) of neurons and senile plaques in the neuropil. After aging, the inheritance of the apolipoprotein E (ApoE) epsilon 4 (ε4) allele is the greatest risk factor for late-onset AD. The ApoE protein is the translated product of the ApoE gene. This protein undergoes proteolysis, and the resulting fragments colocalize with neurofibrillary tangles and amyloid plaques, and for that matter may be involved in AD onset and/or progression. Previous studies have reported the pathogenic potential of various ApoE fragments in AD pathophysiology. However, the pathways activated by the fragments are not fully understood. In this review, ApoE fragments obtained from post-mortem brains and body fluids, cerebrospinal fluid (CSF) and plasma, are discussed. Additionally, current knowledge about the process of fragmentation is summarized. Finally, the mechanisms by which these fragments are involved in AD pathogenesis and pathophysiology are discussed.

scholarly journals A Study of the SORL1 Gene in the Pathogenesis of Late-onset Alzheimer’s Disease by Affecting the Expression of BDNF

2021 ◽  
Author(s):  
Mingri Zhao ◽  
Jiangfeng Liu ◽  
Jingli He ◽  
Xun Chen ◽  
Yanjin Feng ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Late Onset ◽  
Cell Model ◽  
Amyloid Β ◽  
Cognitive Disorders ◽  
Amyloid Β Protein ◽  
Bdnf Expression ◽  
The Brain

Abstract BackgroundAlzheimer’s disease is a neurodegenerative disease characterized by progressive memory impairment and other cognitive disorders. It is divided into Familial Alzheimer's disease (FAD) and Sporadic Alzheimer's disease (SAD). SAD is also called delayed Late-onset Alzheimer's disease (LOAD). Sortilin Related Receptor 1 (SORL1) is a high-risk pathogenic gene of LOAD, which can participate in the occurrence and development of AD by affecting the transport and metabolism of intracellular β-amyloid precursor protein (APP). The expression of SORL1 is significantly downregulated in patients with LOAD.ResultsIn the SORL1 knockout (SORL1 KO) mouse model constructed by CRISPR/cas9, we found that the expression of Brain Derived Neurotrophic Factor (BDNF) in the brain of SORL1 KO mice was significantly down-regulated and Amyloid β-protein (Aβ) deposition was found in the brain ofSORL1 KO mice. Through the SORL1 knockdown N2a cell model constructed by shRNA, we also found that when the SORL1 expression was knocked down, the BDNF expression was also downregulated and the cell viability decreased. The results of immunohistochemistry and in vitro cell model experiments suggest that the downregulation of BDNF caused by SORL1 knockdown may be mainly achieved by affecting the expression and distribution of N-Methyl-D-aspartate (NMDAR).ConclusionsSORL1 knockout changes the expression and distribution of NMDAR in cells, downregulates the expression of BDNF, and thus affects the learning and memory of mice.

Inhibition of Aβ(1–40) fibril formation by cyclophilins

2016 ◽  
Vol 473 (10) ◽  
pp. 1355-1368 ◽  
Author(s):  
Marten Villmow ◽  
Monika Baumann ◽  
Miroslav Malesevic ◽  
Rolf Sachs ◽  
Gerd Hause ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Β ◽  
Fibril Formation ◽  
Water Soluble ◽  
Main Process ◽  
Amyloid Β Peptide ◽  
Cyclophilin D ◽  
Aβ Amyloid

Cyclophilins interact directly with the Alzheimer's disease peptide Aβ (amyloid β-peptide) and are therefore involved in the early stages of Alzheimer's disease. Aβ binding to CypD (cyclophilin D) induces dysfunction of human mitochondria. We found that both CypD and CypA suppress in vitro fibril formation of Aβ(1–40) at substoichiometric concentrations when present early in the aggregation process. The prototypic inhibitor CsA (cyclosporin A) of both cyclophilins as well as the new water-soluble MM258 derivative prevented this suppression. A SPOT peptide array approach and NMR titration experiments confirmed binding of Aβ(1–40) to the catalytic site of CypD mainly via residues Lys16–Glu22. The peptide Aβ(16–20) representing this section showed submicromolar IC50 values for the peptidyl prolyl cis–trans isomerase activity of CypD and CypA and low-micromolar KD values in ITC experiments. Chemical cross-linking and NMR-detected hydrogen–deuterium exchange experiments revealed a shift in the populations of small Aβ(1–40) oligomers towards the monomeric species, which we investigated in the present study as being the main process of prevention of Aβ fibril formation by cyclophilins.

scholarly journals Apolipoprotein E forms stable complexes with recombinant Alzheimer's disease β-amyloid precursor protein

1997 ◽  
Vol 325 (1) ◽  
pp. 169-175 ◽  
Author(s):  
Cristina HAAS ◽  
Pilar CAZORLA ◽  
Carlos DE MIGUEL ◽  
Fernando VALDIVIESO ◽  
Jesús VÁZQUEZ
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Apolipoprotein E ◽  
Senile Plaques ◽  
Precursor Protein ◽  
Amyloid Peptide ◽  
Reducing Conditions ◽  
Β Amyloid

Apolipoprotein E (apoE), a protein genetically linked to the incidence of Alzheimer's disease, forms SDS-stable complexes in vitro with β-amyloid peptide (Aβ), the primary component of senile plaques. In the present study, we investigated whether apoE was able to bind full-length Aβ precursor protein (APP). Using a maltose-binding-protein–APP fusion protein and human very-low-density lipoprotein (VLDL), we detected an interaction of apoE with APP that was inhibited by Aβ or anti-apoE antibody. Saturation-binding experiments indicated a single binding equilibrium with an apparent 1:1 stoichiometry and a dissociation constant of 15 nM. An interaction was also observed using apoE from cerebrospinal fluid or delipidated VLDL, as well as recombinant apoE. APP·apoE complexes were SDS-stable, and their formation was not inhibited by reducing conditions; however, they were dissociated by SDS under reducing conditions. ApoE·APP complexes formed high-molecular-mass aggregates, and competition experiments suggested that amino acids 14–23 of Aβ are responsible for complex-formation. Finally, no differences were found when studying the interaction of APP with apoE3 or apoE4. Taken together, our results demonstrate that apoE may form stable complexes with the Aβ moiety of APP with characteristics similar to those of complexes formed with isolated Aβ, and suggest the intriguing possibility that apoE–APP interactions may be pathologically relevant in vivo.

scholarly journals Danger-Sensing/Patten Recognition Receptors and Neuroinflammation in Alzheimer’s Disease

2020 ◽  
Vol 21 (23) ◽  
pp. 9036
Author(s):  
Anna Chiarini ◽  
Ubaldo Armato ◽  
Peng Hu ◽  
Ilaria Dal Prà
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cortical Neurons ◽  
Therapeutic Potential ◽  
Amyloid Β ◽  
Tau Proteins ◽  
Calcium Sensing ◽  
Chronic Neuroinflammation

Fibrillar aggregates and soluble oligomers of both Amyloid-β peptides (Aβs) and hyperphosphorylated Tau proteins (p-Tau-es), as well as a chronic neuroinflammation are the main drivers causing progressive neuronal losses and dementia in Alzheimer’s disease (AD). However, the underlying pathogenetic mechanisms are still much disputed. Several endogenous neurotoxic ligands, including Aβs, and/or p-Tau-es activate innate immunity-related danger-sensing/pattern recognition receptors (PPRs) thereby advancing AD’s neuroinflammation and progression. The major PRR families involved include scavenger, Toll-like, NOD-like, AIM2-like, RIG-like, and CLEC-2 receptors, plus the calcium-sensing receptor (CaSR). This quite intricate picture stresses the need to identify the pathogenetically topmost Aβ-activated PRR, whose signaling would trigger AD’s three main drivers and their intra-brain spread. In theory, the candidate might belong to any PRR family. However, results of preclinical studies using in vitro nontumorigenic human cortical neurons and astrocytes and in vivo AD-model animals have started converging on the CaSR as the pathogenetically upmost PRR candidate. In fact, the CaSR binds both Ca2+ and Aβs and promotes the spread of both Ca2+ dyshomeostasis and AD’s three main drivers, causing a progressive neurons’ death. Since CaSR’s negative allosteric modulators block all these effects, CaSR’s candidacy for topmost pathogenetic PRR has assumed a growing therapeutic potential worth clinical testing.

scholarly journals Deconstructing Alzheimer’s Disease: How to Bridge the Gap between Experimental Models and the Human Pathology?

2021 ◽  
Vol 22 (16) ◽  
pp. 8769
Author(s):  
Anaïs Vignon ◽  
Lucie Salvador-Prince ◽  
Sylvain Lehmann ◽  
Véronique Perrier ◽  
Joan Torrent
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Molecular Mechanisms ◽  
Amyloid Β ◽  
Experimental Models ◽  
Tau Proteins ◽  
Human Pathology ◽  
Set Up

Discovered more than a century ago, Alzheimer’s disease (AD) is not only still present in our societies but has also become the most common dementia, with 50 million people worldwide affected by the disease. This number is expected to double in the next generation, and no cure is currently available to slow down or stop the disease progression. Recently, some advances were made due to the approval of the aducanumab treatment by the American Food and Drug Administration. The etiology of this human-specific disease remains poorly understood, and the mechanisms of its development have not been completely clarified. Several hypotheses concerning the molecular mechanisms of AD have been proposed, but the existing studies focus primarily on the two main markers of the disease: the amyloid β peptides, whose aggregation in the brain generates amyloid plaques, and the abnormally phosphorylated tau proteins, which are responsible for neurofibrillary tangles. These protein aggregates induce neuroinflammation and neurodegeneration, which, in turn, lead to cognitive and behavioral deficits. The challenge is, therefore, to create models that best reproduce this pathology. This review aims at gathering the different existing AD models developed in vitro, in cellulo, and in vivo. Many models have already been set up, but it is necessary to identify the most relevant ones for our investigations. The purpose of the review is to help researchers to identify the most pertinent disease models, from the most often used to the most recently generated and from simple to complex, explaining their specificities and giving concrete examples.

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