Adult and neonatal astrocytes exhibit diverse gene expression profiles during exposure to beta amyloid ex vivo
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE29317 | GEO | 2012/07/14
SECONDARY ACCESSION(S): PRJNA141617
REPOSITORIES: GEO
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Project description:Research regarding the role of astrocytes as M-NM-2-amyloid (AM-NM-2) degrading cells has broadened our view about the mechanisms how these common glia cells function in AlzheimerM-bM-^@M-^Ys disease (AD). Based on previous studies adult mouse astrocytes are able to degrade AM-NM-2 deposits from AD mouse model and human brain tissue sections ex vivo, contrary to neonatal astrocytes. In this study, we studied the possible altered gene expression profiles of adult and neonatal astrocytes cultured for 22 h on top of the AM-NM-2 burdened tg APdE9 or wild-type mouse brain sections using whole genome microarrays. Quantitative RT-PCR analysis confirmed the significant up-regulation of HtrA serine peptidase 1 (Htra1), metallopeptidase 9 (Mmp9), phosphate regulating gene with homologies to endopeptidases on the X chromosome (Phex) and scavenger receptor class A, member 5 (Scara5) in adult astrocytes, whereas neonatal astrocytes up-regulated Mmp9 and down-regulated genes related to cholesterol transport and synthesis: apolipoprotein E (Apoe), 24-dehydrocholesterol reductase (Dhcr24) and 3-hydroxy-3-methylglutaryl-CoA synthase 1 (Hmgcs1). These findings brought out novel genes which expression is altered during AM-NM-2 clearance in adult and neonatal astrocytes ex vivo. Astrocyte cultures: For the adult astrocyte cultures, hippocampi and cortices were isolated from 6-8-week-old C57Bl/6j wild-type and tg eGFP mice and the tissue was suspended in DMEM/F12 (3:1, Gibco BRL, NY, USA) containing 10 % heat-inactivated fetal bovine serum (Gibco BRL) and 100 U / ml penicillin-streptomycin (Gibco BRL). The cells were treated with Percoll (Sigma-Aldrich, St.Louis, USA) and plated onto poly-L-lysine coated flasks in DMEM/F12 (3:1) containing 10 % heat-inactivated fetal bovine serum, 100 U / ml penicillin-streptomycin and G5 supplement (Gibco BRL). Before the experiments the glial cell cultures were shaken to remove microglia at 200 rpm for 2 h. For the neonatal astrocyte cultures, hippocampi and cortices were isolated from 2-day-old wild-type and eGFP mice according to the protocol described above, except that the culture medium was DMEM (+4500mg/l glucose, + L-glutamine, -pyruvate, Gibco BRL) without G5 supplement and the isolation method included no Percoll treatment. Standard anti-GFAP (1:500; Dako Cytomation, Glostrup, Denmark) immunocytochemistry was used to determine the purity of astrocyte cultures. The cells were incubated with biotinylated goat anti-rabbit IgG (1:200 dilution; Vector Laboratories, CA) secondary antibody and Vectastain ABC Elite kit was used (Vector Laboratories) according to manufacturerM-bM-^@M-^Ys protocol. Hydroxen peroxide (H2O2) and nickel enhanced diaminobenzidine (Ni-DAB) was added to detect the immunoreactivity. Three fields per well and at least three wells per cell type were analyzed for the percentage of Ni-DAB stained cells of all cellular profiles in the field. Adult and neonatal astrocyte cultures both contained on average 99.6 % M-BM-1 0.6 % anti-GFAP immunoreactive astrocytes. Anti-Iba (2 M-BM-5g/ml; Wako, Germany) and anti-CD11b (1:500 dilution; Serotec, UK) antibodies were used to detect possible microglial cells. The cultures contained less than 0.4 % of microglial cells in all experiments. Ex vivo treatments: tg APdE9 / wild-type mouse brain section incubated with neonatal (age 3 d) or adult (age 6-8 wks) mouse eGFP expressing astrocytes (4 x 105 cells / well), n=6. The mouse brain sections used were prepared from tg APdE9 mouse line (created by co-injection of chimeric mouse/human APPSwe and PS1-dE9 vectors, both controlled by their own mouse prion protein promoter element [APdE9 mice (Jankowsky et al. 2004) provided by Prof. Heikki Tanila] and their wild type C57Bl/6j littermates. Before the mRNA isolation process, the samples were pooled (n=3). The purity of the samples was checked with FACS (FACSCalibur, Becton Dickinson, USA) using the analyzing program CellQuestTM version 3.3 (Becton Dickinson, USA). After 22 h incubation the culture medium was removed from the wells and the brain sections with cultured eGFP astrocytes were incubated with 1 x trypsin-EDTA (500 M-BM-5l /well) for up to 15 min at 37M-BM-0 C. Partial detachment (at this point, the astrocytes should not lose the grip completely) of the astrocytes from the underlying brain section was monitored with a standard light microscope. After the incubation the brain sections with cultured astrocytes were carefully removed into small petri dishes filled with FBS-containing culture medium to inactivate the trypsin. Subsequently, the brain sections were immediately examined with fluorescence microscope (Olympus IX-71, Japan). The eGFP astrocytes were separated from the underlying brain section using a special suction hose, which was a modified version from suction hoses typically used for the microinjection techniques. In the other end of the tube there is a pipet tip as a mouthpiece, in the middle of the tube a 0.22 M-BM-5m filter and in the other end a stretched glass capillary (prepared with a Bunsen burner). The green fluorescent eGFP astrocytes were picked up gently from the underlying brain section (without breaking the brain tissue) using wavelength 468 nm of the fluorescence microscope and simultaneous light microscopy. Data normalization and analysis: The raw data was preprocessed with the robust multichip algorithm (Irizarry et al. 2003), normalized per chip to the median. 12 samples were grouped into 4 sample types: adult_wt, adult_tg, neonatal_wt, neonatal_tg. The change in the astrocyte gene expression was identified according to the sections the astrocytes were incubated (WT or TG). The differentially expressed probe sets were further processed using statistical analysis with Welch unpaired t-test assuming unequal variances (p<0.05; fold change > 2.0 or < 0.5). Benjamini-Hochberg false-discovery rate (FDR) correction for multiple testing was used to control the number of false-positives results.
2012-07-13 | E-GEOD-29317 | biostudies-arrayexpress
Project description:To reveal the mechanisms that Ogt controls inflammatory response of astrocytes, we first performed RNA-seq with Ctrl and Ogt cKO astrocytes isolated from the brains of adult mice. Given the inflammation in the brain of Alzheimer’s disease, we next performed RNA-seq with astrocytes isolated from the brains of adult Ctrl and 5X APP Alzheimer’s mice model (AD), and Aβ treated astrocytes, respectively. Taken together, these findings suggest that differentially expressed genes shared between cKO astrocytes, AD astrocytes and Aβ-treated astrocytes are related with inflammation.
2024-03-22 | GSE169347 | GEO
Project description:Astrocytes, one of the most resilient cells in the brain, transform into reactive astrocytes in response to toxic proteins such as amyloid beta (Aβ) in Alzheimer’s disease (AD). However, reactive astrocyte-mediated non-cell autonomous neuropathological mechanism is not fully understood yet. We aimed our study to find out whether Aβ-induced proteotoxic stress affects the expression of autophagy genes and the modulation of autophagic flux in astrocytes, and if yes, how Aβ-induced autophagy-associated genes are involved Aβ clearance in astrocytes of animal model of AD. Whole RNA sequencing (RNA-seq) was performed to detect gene expression patterns in Aβ-treated human astrocytes in a time-dependent manner. To verify the role of astrocytic autophagy in an AD mouse model, we developed AAVs expressing shRNAs for MAP1LC3B/LC3B (LC3B) and Sequestosome1 (SQSTM1) based on AAV-R-CREon vector, which is a Cre recombinase-dependent gene-silencing system. Also, the effect of astrocyte-specific overexpression of LC3B on the neuropathology in AD (APP/PS1) mice was determined. Neuropathological alterations of AD mice with astrocytic autophagy dysfunction were observed by confocal microscopy and transmission electron microscope (TEM). Behavioral changes of mice were examined through novel object recognition test (NOR) and novel object place recognition test (NOPR). Here, we show that astrocytes, unlike neurons, undergo plastic changes in autophagic processes to remove Aβ. Aβ transiently induces expression of LC3B gene and turns on a prolonged transcription of SQSTM1 gene. The Aβ-induced astrocytic autophagy accelerates urea cycle and putrescine degradation pathway. Pharmacological inhibition of autophagy exacerbates mitochondrial dysfunction and oxidative stress in astrocytes. Astrocyte-specific knockdown of LC3B and SQSTM1 significantly increases Aβ plaque formation and hypertrophic reactive astrocytes in APP/PS1 mice, along with a significant reduction of neuronal marker and cognitive function. In contrast, astrocyte-specific overexpression of LC3B reduced Ab aggregates in the brain of APP/PS1 mice An increase of LC3B and SQSTM1 protein is found in astrocytes of the hippocampus in AD patients. Taken together, our data indicates that Aβ-induced astrocytic autophagic plasticity is an important cellular event to modulate Aβ clearance and maintain cognitive function in AD mice.
2024-06-30 | GSE267554 | GEO
Project description:Extracellular matrix (ECM) remodeling is strongly linked to Alzheimer’s disease (AD) risk, but its functions are not fully understood. Here, we found that medial prefrontal cortex (mPFC) injection with chondroitinase ABC (ChABC) to remodel ECM reverses short-term memory loss and reduces Aβ deposition in 5xFAD mice. ECM remodeling also reactivates astrocytes, untangles aggrecan’s entanglement with amyloid-beta (Aβ) plaques, and encourages astrocyte recruitment to the surrounding plaques. ECM remodeling promotes astrocyte phagocytosis of Aβ plaque by activating the astrocyte phagocytosis receptor mertk and astrocytic vesicle circulation. Importantly, ECM remodeling enhances the autophagy-lysosome pathway in astrocytes to mediate Aβ clearance and alleviate AD pathology. Our work thus discovers a cellular mechanism to remodel the ECM to active astrocyte autophagic lysosomal pathway alleviation AD pathology. It may represent a potential therapeutic strategy and serve as a hallmark for treating AD.
2024-10-17 | PXD046784 | Pride
Project description:The major genetic risk factor for Alzheimer’s disease (AD), APOE4, accelerates beta-amyloid (Aβ) plaque formation, but whether this is caused by APOE expressed in microglia or astrocytes is debated. We express here the human APOE isoforms in astrocytes in an Apoe-deficient AD mouse model. This is not only sufficient to restore the amyloid plaque pathology but also induces the characteristic transcriptional pathological responses in Apoe-deficient microglia surrounding the plaques. We find that both APOE4 and the protective APOE2 from astrocytes increase fibrillar plaque deposition, but differentially affect soluble Aβ aggregates. Microglia and astrocytes show specific alterations in function of APOE genotype expressed in astrocytes. Our experiments indicate a central role of the astrocytes in APOE mediated amyloid plaque pathology and in the induction of associated microglia responses.
2024-10-04 | GSE252454 | GEO
Project description:A pathological hallmark of Alzheimer’s disease (AD) is the deposition of amyloid-β protein (Aβ) in the brain. Physical exercise has been shown to reduce Aβ burden in various AD mouse models, but the underlying mechanisms have not been elucidated. Irisin, an exercise-induced hormone, is the secreted form of fibronectin-domain III containing 5 (FNDC5). Here, using a three-dimensional (3D) cell culture model of AD, we show that irisin significantly reduces Aβ pathology by increasing astrocytic release of the Aβ-degrading enzyme neprilysin (NEP). This is mediated by downregulation of ERK-STAT3 signaling. Finally, we show that integrin αV/β5 acts as the irisin receptor on astrocytes required for irisin-induced release of astrocytic NEP, leading to clearance of Aβ. Our findings reveal for the first time a cellular and molecular mechanism by which exercise-induced irisin attenuates Aβ pathology, suggesting a new target pathway for therapies aimed at the prevention and treatment of AD
2023-09-08 | GSE240161 | GEO
Project description:Although sporadic AD (sAD) accounts for the majority of AD cases, the underlying mechanisms remain largely unknown. Here we modeled sAD using human induced pluripotent stem cell (iPSC)-derived three-dimensional brain organoids. We exposed brain organoids to serum to mimic the serum exposure consequence of BBB breakdown in AD patient brains. The serum-exposed brain organoids were able to recapitulate AD-like pathologies, including increased Aβ aggregates and p-Tau level, synaptic loss, and impaired calcium signaling and neural network. Serum exposure increased Aβ and p-Tau levels through inducing BACE and GSK3α/β levels, respectively. In addition, single-cell transcriptomic analysis of brain organoids revealed that serum exposure reduced synaptic function in both neurons and astrocytes, and induced immune response in astrocytes. The human brain organoid-based sAD model established in this study could provide a powerful platform for both mechanistic study and therapeutic development.
2021-09-29 | GSE164089 | GEO
Project description:A pathological hallmark of Alzheimer’s disease (AD) is the deposition of amyloid-β protein (Aβ) in the brain. Physical exercise has been shown to reduce Aβ burden in various AD mouse models, but the underlying mechanisms have not been elucidated. Irisin, an exercise-induced hormone, is the secreted form of fibronectin-domain III containing 5 (FNDC5). Here, using a three-dimensional (3D) cell culture model of AD, we show that irisin significantly reduces Aβ pathology by increasing astrocytic release of the Aβ-degrading enzyme neprilysin (NEP). This is mediated by downregulation of ERK-STAT3 signaling. Finally, we show that integrin αV/β5 acts as the irisin receptor on astrocytes required for irisin-induced release of astrocytic NEP, leading to clearance of Aβ. Our findings reveal for the first time a cellular and molecular mechanism by which exercise-induced irisin attenuates Aβ pathology, suggesting a new target pathway for therapies aimed at the prevention and treatment of AD.
2023-08-11 | PXD044499 |
Project description:Purpose: The existence and role of the urea cycle has not been well studied in the astrocytes of Alzheimer's Disease (AD). In the past, ODC1-inhibitor DFMO (Diflouromethylornithine) has been shown to have a neuroprotective effect on AD-like pathology, but the biochemical mechanism of this effect remains largely unknown. In this study, we aim to compare the transcriptome of naive and Aβ-treated astrocytes and further study the effect of DFMO treatment in Aβ-treatment condition. Methods: Primary astrocyte culture (from P0-P1 mouse pups) mRNA profiles were generated by high-throughput NGS in 3 treatment conditions in duplicate using HiSeq 2500. Sequence reads were analysed using Partek Genomics Suite, aligned using STAR and then quantified to the mouse genome assembly (mm10 Ensemble transcripts release 99), following which they were normalised to median ratio values and differentially analysed using the DeSeq2 algorithm. Finally, pathway analysis was carried out to study the differential expression of biomolecular pathways, with reference to the KEGG database. Results: Using an optimized data analysis workflow, we mapped about 50 million sequence reads per sample to the mouse genome (build mm10) and identified 18783 genes in the dataset. Differential analysis revealed upregulation of autophagy-related genes as well as switching-on of the genes involved in the cyclic metabolism of urea on Aβ treatment of astrocytes. ODC1 inhibition by DFMO induced upregulation of genes involved in the non-amyloidogenic processing of APP and downregulation of amyloidogenic genes. Pathway analysis revealed upregulation of urea cycle and urea metabolic process pathways, as well as selective autophagy and phagosome-lysosome fusion on Aβ treatment. Conclusions: Our study represents the first detailed analysis of mouse astrocyte culture transcriptome on Aβ-treatment, and the effect of ODC1 inhibition on the same, with biological replicates, generated by RNA-seq technology. The optimized data analysis workflows reported here should provide a framework for comparative investigations of expression profiles. From our results, we can conclude that the urea cycle is turned on in Alzheimer's Disease (AD)-like condition and that ODC1-inhibition can be a suitable therapeutic strategy to reduce the Aβ load in AD.
2021-10-16 | GSE185916 | GEO
Project description:Communication within the glial cell ecosystem is essential for neuronal and brain health1–3. The influence of glial cells on the accumulation and clearance of β-amyloid (Aβ) and neurofibrillary tau in the brains of individuals with Alzheimer’s disease (AD) is poorly understood, despite growing awareness that these are therapeutically important interactions4,5. Here we show, in humans and mice, that astrocyte-sourced interleukin-3 (IL-3) programs microglia to ameliorate the pathology of AD. Upon recognition of Aβ deposits, microglia increase their expression of IL-3Rα—the specific receptor for IL-3 (also known as CD123)—making them responsive to IL-3. Astrocytes constitutively produce IL-3, which elicits transcriptional, morphological, and functional programming of microglia to endow them with an acute immune response program, enhanced motility, and the capacity to cluster and clear aggregates of Aβ and tau. These changes restrict AD pathology and cognitive decline. Our findings identify IL-3 as a key mediator of astrocyte–microglia cross-talk and a node for therapeutic intervention in AD.
2021-06-02 | GSE163289 | GEO