Expression profiling of laser-microdissected tissue from APPPS1 plaque-depositing mouse model of Alzheimer's disease
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE15058 | GEO | 2014/11/04
SECONDARY ACCESSION(S): PRJNA123155
REPOSITORIES: GEO
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Project description:Amyloid-M-CM-^_ (AM-CM-^_) plaques are pathological hallmarks of Alzheimer disease. However, the precise neuropathological changes that occur in brain in response to amyloid deposition are largely unknown. To study the molecular mechanism(s) responsible for AM-CM-^_-mediated neuropathology, we performed a gene expression analysis on frontal neocortical brain tissue of APPPS1 mice compared to their littermate controls. 4 samples; 2 biological replicates of each condition = 2 transgenic versus 2 non-transgenic mice; no amplification of total RNA; Cy3/Cy5 dye-swap design
2014-11-04 | E-GEOD-15058 | biostudies-arrayexpress
Project description:Amyloid-ß (Aß) plaques are pathological hallmarks of Alzheimer disease. However, the precise neuropathological changes that occur in brain in response to amyloid deposition are largely unknown. To study the molecular mechanism(s) responsible for Aß-mediated neuropathology, we performed a gene expression analysis on laser-microdissected brain tissue of Tg2576 mice compared to their littermate controls.
2014-11-04 | GSE15056 | GEO
Project description:Amyloid-M-CM-^_ (AM-CM-^_) plaques are pathological hallmarks of Alzheimer disease. However, the precise neuropathological changes that occur in brain in response to amyloid deposition are largely unknown. To study the molecular mechanism(s) responsible for AM-CM-^_-mediated neuropathology, we performed a gene expression analysis on laser-microdissected brain tissue of Tg2576 mice compared to their littermate controls. 4 samples; 2 biological replicates of each condition = 2 transgenic versus 2 non-transgenic mice; double amplification of total RNA; only Cy3; no dye-swaps
2014-11-04 | E-GEOD-15056 | biostudies-arrayexpress
Project description:The accumulation of amyloid-ß (Aß) peptides in the brain is a crucial step in the pathogenesis of Alzheimer`s disease (AD). Several studies indicate that microglia cells in the brain have the ability to internalize Aß by phagocytosis and might therefore play a protective role in AD. However, the mechanisms underlying Aß clearance remain unresolved. We have found that small molecule inhibitors of the ubiquitous glycogen synthase kinase 3ß (GSK3ß) stimulate the uptake of Aß by human THP-1 monocytes and primary murine microglia cells. To investigate how GSK3ß inhibitors might stimulate Aß uptake, we conducted microarray-based gene expression analyses of THP-1 cells after treatment with three different GSK3ß inhibitors. We identified a subset of genes similarly altered by all three inhibitors, including chemokines and surface receptors that have been linked to the regulation of microglial activation and phagocytosis.
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Project description:Alzheimer's disease (AD) is the most common form of dementia, characterized by progressive cognitive impairment and neurodegeneration as a result of abnormal neuronal loss. To elucidate the molecular systems associated with AD, we characterized the gene expression changes associated with multiple clinical and neuropathological traits in 1,053 postmortem brain samples across 19 brain regions from 125 persons dying with varying severities of dementia and variable AD-neuropathology severities. 125 human brains were accessed from the Mount Sinai/JJ Peters VA Medical Center Brain Bank (MSBB). This brain resource was assembled after applying stringent inclusion/exclusion criteria and represents the full spectrum of clinical and neuropathological disease severity in the absence of discernable non-AD neuropathology. RNA samples from 19 brain regions isolated from the 125 MSBB specimens were collected and profiled using Affymetrix Genechip microarrays. There were 50 to 60 subjects per brain region with varying degrees of AD pathological abnormalities.
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Project description:Proctor2012 - Amyloid-beta aggregation
This model supports the current thinking that levels of dimers are important in initiating the aggregation process.
This model is described in the article:
Aggregation, impaired degradation and immunization targeting of amyloid-beta dimers in Alzheimer's disease: a stochastic modelling approach.
Proctor CJ, Pienaar IS, Elson JL, Kirkwood TB
Molecular Neurodegeneration. 2012; 7:32
Abstract:
BACKGROUND:
Alzheimer's disease (AD) is the most frequently diagnosed neurodegenerative disorder affecting humans, with advanced age being the most prominent risk factor for developing AD. Despite intense research efforts aimed at elucidating the precise molecular underpinnings of AD, a definitive answer is still lacking. In recent years, consensus has grown that dimerisation of the polypeptide amyloid-beta (Aß), particularly Aß₄₂, plays a crucial role in the neuropathology that characterise AD-affected post-mortem brains, including the large-scale accumulation of fibrils, also referred to as senile plaques. This has led to the realistic hope that targeting Aß₄₂ immunotherapeutically could drastically reduce plaque burden in the ageing brain, thus delaying AD onset or symptom progression. Stochastic modelling is a useful tool for increasing understanding of the processes underlying complex systems-affecting disorders such as AD, providing a rapid and inexpensive strategy for testing putative new therapies. In light of the tool's utility, we developed computer simulation models to examine Aß₄₂ turnover and its aggregation in detail and to test the effect of immunization against Aß dimers.
RESULTS:
Our model demonstrates for the first time that even a slight decrease in the clearance rate of Aß₄₂ monomers is sufficient to increase the chance of dimers forming, which could act as instigators of protofibril and fibril formation, resulting in increased plaque levels. As the process is slow and levels of Aβ are normally low, stochastic effects are important. Our model predicts that reducing the rate of dimerisation leads to a significant reduction in plaque levels and delays onset of plaque formation. The model was used to test the effect of an antibody mediated immunological response. Our results showed that plaque levels were reduced compared to conditions where antibodies are not present.
CONCLUSION:
Our model supports the current thinking that levels of dimers are important in initiating the aggregation process. Although substantial knowledge exists regarding the process, no therapeutic intervention is on offer that reliably decreases disease burden in AD patients. Computer modelling could serve as one of a number of tools to examine both the validity of reliable biomarkers and aid the discovery of successful intervention strategies.
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2024-09-02 | BIOMD0000000462 | BioModels
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Project description:Alzheimer’s disease (AD) is the most common form of dementia and neurodegenerative disease with increasing prevalence due to longer lifespan in the human population. Why aging constitutes the greatest risk factor for development of AD, however, remains poorly understood. Aging markedly affects oligodendrocytes and the structural integrity of their myelin sheaths which also causes secondary tissue inflammation. We propose a mechanistic link between aging-associated myelin dysfunction and the deposition of Amyloid-ß (Aß) as primary neuropathological hallmark of early AD and hypothesized that breakdown of myelin - especially in cortical regions – is an upstream driver of amyloid deposition in AD. Here, we show that in transgenic mouse models of AD, genetically induced myelin defects by Cnp or Plp1 depletion, as well as direct demyelination are potent drivers of amyloid deposition in vivo as shown by light sheet microscopy imaging. At transcriptomic level, bulk and single-cell RNA sequencing revealed successfully induced disease-associated-microglia (DAM)-like phenotypes in Cnp-/- animals. These activated microglia, however, are primarily engaged with myelin seemingly preventing the protective reactions of the microglia pool to Aß plaques. Our work, therefore, identifies myelin aging as a previously overlooked risk factor for AD and makes the case for myelin health-directed therapies in AD.
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Project description:Psychological, psychosocial and physical stress are major risk factors, which enhance the development of sporadic late-onset Alzheimer`s disease. The chronic unpredictable mild stress model mimics those risk factors and triggers signs of neurodegeneration and neuropathological features of sporadic AD such as tau hyperphosphorylation and enhanced amyloid beta generation. The study investigated the impact of chronic unpredictable mild stress on signs of neurodegeneration by analyzing hippocampal gene expression with whole genome microarray gene expression profiling.
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Project description:The e4 allele of the apolipoprotein E (APOE) gene is the strongest genetic risk factor for late-onset Alzheimer's disease and has been shown to increase amyloid pathology relative to the presence of the e2 and e3 alleles. In the brain, apoE is primarily produced by astrocytes and under pathological conditions also by microglia. The cell-type-specific role of apoE in amyloid pathology, especially after amyloid plaque deposition, has not been fully elucidated. We generated APPPS1-21/Aldh1l1-Cre/ERT2/apoE4flox/flox and APPPS1-21/apoE4flox/flox mice. At 3.8-months-of-age, during the phase of rapid plaque growth, we administered tamoxifen to reduce astrocytic APOE4 and assessed mice at 6-months-of-age. One day before tamoxifen treatment, mice were injected with methoxy-X04, a blood-brain-barrier permeant fluorescent marker that labeled the pre-existing fibrillar amyloid plaques. By using this strategy, we were able to characterize pre-existing plaques prior to the loss of astrocytic APOE4 and to also analyze newly-formed amyloid plaques after the loss of astrocytic APOE4. Interestingly, astrocytic APOE4 deletion strongly reduced pre-existing plaques. It also prevented new plaque formation and decreased glial reactivity. Importantly, the removal of astrocytic APOE4 resulted in enhanced microglial and astrocytic phagocytic ability, which may contribute to the reduction of the amyloid pathology.
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