5xFAD transgenic mouse Abeta proteoforms
Ontology highlight
ABSTRACT:
INSTRUMENT(S): Orbitrap Fusion Lumos
ORGANISM(S): Mus Musculus (mouse)
TISSUE(S): Brain
SUBMITTER: 
Soumya Kandi
LAB HEAD: Steven Patrie
PROVIDER: PXD042921 | Pride | 2023-09-27
REPOSITORIES: Pride
Similar Datasets
Project description:Amyloid-beta (Aβ) plays a key role in the neuropathogenesis of Alzheimer’s disease, but little is known about the proteoforms (i.e., all protein variants of a single gene including post-translational modifications and sequence variants) present in human AD brain. We used high-resolution mass spectrometry to analyze intact, whole Aβ from soluble and insoluble aggregates in brains of 6 cases with severe dementia and pathologically confirmed Alzheimer’s disease. We found an extraordinary diversity of Aβ peptides totaling 91 unique proteoforms including various N- and C-terminal truncations, 17 different types of post-translational modifications (PTMs), and remarkably 5 amino acid variants in the peptide sequence never before described. Ratios of Aβ proteoforms did not distinguish between soluble and insoluble aggregates, but four individual Aβ proteoforms, three in the insoluble and one in the soluble fraction, were markedly increased when compared across aggregates. Such heterogeneity of the Aβ peptide both deepens our understanding of AD, but perhaps also warrants pause and consideration in our investigation into pathological mechanisms of the disease and therapeutic development.
2017-09-04 | PXD005119 | Pride
Project description:Amyloid-beta (Aβ) plays a key role in the pathogenesis of Alzheimer’s disease (AD), but little is known about the proteoforms present in human AD brain. We used high-resolution mass spectrometry to analyze intact, undigested Aβ from purified soluble aggregates and insoluble material in brains of 6 cases with severe dementia and pathologically confirmed AD. The soluble aggregates are especially relevant because they are believed to be the most toxic form of Aβ. We found a diversity of Aβ peptides, with 26 unique proteoforms including various N- and C-terminal truncations. N- and C-terminal truncations comprised 73% and 30%, respectively, of the number of Aβ proteoforms detected. The Aβ proteoforms segregated between the soluble and more insoluble aggregates with N-terminal truncations predominating in the insoluble material and C- terminal truncations segregating into the soluble aggregates. In contrast, canonical Aβ comprised the minority of the number of identified proteoforms (15.3%) and did not distinguish between the soluble and more insoluble aggregates. The relative abundance of many truncated Aβ proteoforms did not correlate with post-mortem interval, suggesting they are not artefacts. This heterogeneity of Aβ proteoforms deepens our understanding of AD and offers many new avenues for investigation into pathological mechanisms of the disease, with implications for therapeutic development.
2017-08-28 | PXD006552 | Pride
Project description:Brain-derived amyloid-β (Aβ) dimers are associated with Alzheimer´s disease (AD). However, their covalent nature remains controversial. This feature is relevant, as a covalent cross-link would make brain-derived dimers (native dimers) more synaptotoxic than Aβ monomers and would make them suitable candidates for biomarker development. To resolve this controversy, we here present a three-step approach. First, we validated a type of synthetic cross-linked Aβ (CL Aβ) dimers, obtained by means of the photo-induced cross-linking of unmodified proteins (PICUP) reaction, as well-defined mimics of putative native CL Aβ dimers. Second, we used these PICUP CL Aβ dimers as standards to improve the isolation of native Aβ dimers and to develop state-of-the-art mass spectrometry (MS) strategies to allow their characterization. Third, we applied these MS methods to the analysis of native Aβ dimer samples allowing the detection of the CL [Aβ(6-16)]2 peptide comprising a dityrosine cross-link. This result demonstrates the presence of CL Aβ dimers in the brains of patients with AD and opens up avenues for establishing new therapeutic targets and developing novel biomarkers for this disease.
2021-05-13 | PXD005657 | Pride
Project description:The aggregation of amyloid beta (Aβ) peptide is associated with Alzheimer’s disease (AD) pathogenesis. Cell membrane composition, especially monosialotetrahexosylganglioside (GM1), is known to promote the formation of Aβ fibrils, yet little is known about the roles of GM1 in the early steps of Aβ oligomer formation. Here, by using GM1-contained liposomes as a mimic of neuronal cell membrane, we demonstrate that GM1 is a critical trigger of Aβ oligomerization and aggregation. We find that GM1 not only promotes the formation of Aβ fibrils, but also facilitates the maintenance of Aβ oligomers on liposome membranes. We structurally characterize the Aβ oligomers formed on the membrane and find that GM1 captures Aβ by binding to its arginine-5 residue. To interrogate the mechanism of Aβ oligomer toxicity, we design a new liposome-based Ca2+-encapsulation assay and provide new evidence for the Aβ ion channel hypothesis. Finally, we conduct cell viability assay to determine the toxicity of Aβ oligomers formed on membranes. Overall, by uncovering the roles of GM1 in mediating early Aβ oligomer formation and maintenance, our work provides a novel direction for pharmaceutical research for AD.
2023-05-10 | PXD029117 | Pride
Project description:Microglia, the innate immune cells of the central nervous system, perform critical inflammatory and non-inflammatory functions to maintain homeostasis and normal neural function. However in Alzheimer’s disease (AD), these beneficial functions become progressively impaired, contributing to synapse and neuron loss and cognitive impairment. The inflammatory cyclooxygenase-PGE2 pathway, including the PGE2 receptor EP2, is implicated in AD development, both in human epidemiology and in transgenic models of AD. To test the transcriptional responses of EP2-deficient microglia to Aβ in vivo, we used mice in which the EP2 receptor is conditionally deleted in microglia using the CD11b-Cre transgene and floxed alleles of the EP2 gene. By injecting these mice with Aβ ICV and isolating microglia from the brains, we have been able to establish the transcriptional response of microglia to Aβ in vivo and test how EP2 deletion in microglia affects this response. 8 month-old C57BL/6 mice, of the genotype CD11b-Cre; EP2+/+ or CD11b-Cre; EP2lox/lox, were injected I.C.V. with either Aβ or vehicle. 48 hours after injection, the mice were sacrificed and transcardially perfused with cold heparinized 0.9% NaCl. Brains were then removed from the mice and pooled, two brains of the same genotype per sample, to ensure adequate cell and RNA yield. The brains were then enzymatically dissociated for microglia isolation using the Neural Tissue Dissociation Kit (P), MACS Separation Columns (LS), and magnetic CD11b Microbeads from Miltenyi Biotec according to the manufacturer's protocol. Immediately after isolating the microglia, RNA was extracted from the cells for microarray analysis.
2015-02-20 | E-GEOD-57181 | biostudies-arrayexpress
Project description:Amyloid plaques (Aβ plaques) are one of the hallmarks of Alzheimer’s disease (AD). The main constituent of Aβ plaques is beta-amyloid peptides but a complex interplay of other infiltrating proteins also co-localizes. We focused on proteomic differences between Aβ plaques and adjacent control tissue in the transgenic mouse model of AD (APPPS1-21) and in similar regions from non-transgenic littermates. A microproteomic strategy included isolation of regions of interest by laser capture microdissection and analyzed by label-free liquid chromatography mass spectrometry. An in-solution digest protocol with a buffer containing an acid-labile surfactant was used to increase protein solubilization and protease efficiency.
2021-03-25 | PXD014274 | Pride
Project description:Brain myeloid cells, include infiltrating macrophages and resident microglia, play an essential role in responding to and inducing neurodegenerative diseases, such as Alzheimer’s disease (AD). Genome-wide association studies (GWAS) implicate many AD casual and risk genes enriched in brain myeloid cells. Coordinated arginine metabolism through arginase 1 (Arg1) is critical for brain myeloid cells to perform biological functions, whereas dysregulated arginine metabolism disrupts them. Altered arginine metabolism is proposed as a new biomarker pathway for AD. We previously reported Arg1 deficiency in myeloid biased cells using lysozyme M (LysM) promoter-driven deletion worsened amyloidosis-related neuropathology and behavioral impairment. However, it remains unclear how Arg1 deficiency in these cells impacts the whole brain to promote amyloidosis. Herein, we aim to determine how Arg1 deficiency driven by LysM restriction during amyloidosis affects fundamental neurodegenerative pathways at the transcriptome level. By applying several bioinformatic tools and analyses, we found that amyloid-β (Aβ) stimulated transcriptomic signatures in autophagy-related pathways and myeloid cells' inflammatory response. At the same time, myeloid Arg1 deficiency during amyloidosis promoted gene signatures of lipid metabolism, myelination, and migration of myeloid cells. Focusing on Aβ associated glial transcriptomic signatures, we found myeloid Arg1 deficiency up-regulated glial gene transcripts that positively correlated with Aβ plaque burden. We also observed that Aβ preferentially activated disease-associated microglial signatures to increase phagocytic response, whereas myeloid Arg1 deficiency selectively promoted homeostatic microglial signature that is non-phagocytic. These transcriptomic findings suggest a critical role for proper Arg1 function during normal and pathological challenges associated with amyloidosis. Furthermore, understanding pathways that govern Arg1 metabolism may provide new therapeutic opportunities to rebalance immune function and improve microglia/macrophage fitness.
2021-04-15 | GSE172108 | GEO
Project description:Alzheimer’s disease (AD) is an unremitting neurodegenerative disorder characterized by cerebral amyloid-β (Aβ) accumulation and gradual decline in cognitive function. Changes in brain energy metabolism arise in the preclinical phase of AD, suggesting an important metabolic component of early AD pathology. Neurons and astrocytes function in close metabolic collaboration, which is essential for the recycling of neurotransmitters in the synapse. However, how this metabolic interplay may be affected during the early stages of AD development has not been sufficiently investigated. Here, we provide an integrative analysis of cellular metabolism during the early stages of Aβ accumulation in the cerebral cortex and hippocampus of the 5xFAD mouse model of AD. Our electrophysiological examination revealed an increase in spontaneous excitatory signaling in hippocampal brain slices of 5xFAD mice. This hyperactive neuronal phenotype coincided with decreased hippocampal TCA cycle metabolism mapped by stable 13C isotope tracing. Particularly, reduced astrocyte TCA cycle activity led to decreased glutamine synthesis, in turn hampering neuronal GABA synthesis in the 5xFAD hippocampus. In contrast, cerebral cortical slices of 5xFAD mice displayed an elevated capacity for oxidative glucose metabolism suggesting a metabolic compensation. When we explored the brain proteome and metabolome of the 5xFAD mice, we found limited changes, supporting that the functional metabolic disturbances between neurons and astrocytes are early events in AD pathology. In addition, we show that synaptic mitochondrial and glycolytic function was impaired selectively in the 5xFAD hippocampus, whereas non-synaptic mitochondrial function was maintained. These findings were supported by ultrastructural analyses demonstrating disruptions in mitochondrial morphology, particularly in the 5xFAD hippocampus. Collectively, our study reveals complex region and cell specific metabolic adaptations, in the early stages of amyloid pathology, which may be fundamental for the progressing synaptic dysfunction in AD.
2021-11-09 | PXD025240 | Pride
Project description:Pantethine, an anti-cholesterol drug, was shown to inhibit the Ab (amyloid beta) peptide-induced expression of IL-1b in primary culture astrocytes derived from either untreated Ab-treated and untreated 5XFAD or Ab-treated WT. These observations prompted us to investigate the effects of pantethine at the transcriptomic level in the mouse AD model.
2018-07-15 | E-MTAB-6772 | biostudies-arrayexpress
Project description:Microglia are innate immune cells of the brain that perform phagocytic and inflammatory functions in disease conditions. Transcriptomic studies of acutely-isolated microglia have provided novel insights into their molecular and functional diversity in homeostatic and neurodegenerative disease states. State-of-the-art mass spectrometric methods can comprehensively characterize proteomic alterations in microglia in neurodegenerative disorders, potentially providing novel functionally-relevant molecular insights that are not provided by transcriptomics. However, proteomic profiling of adult primary microglia in neurodegenerative disease conditions has not been performed. We performed quantitative proteomic analyses of purified CD11b+ acutely-isolated microglia adult mice in normal, acute neuroinflammatory (LPS-treatment) and chronic neurodegenerative states (5xFAD model of Alzheimer’s disease [AD]) using tandem mass tag mass spectrometry. Differential expression analyses were performed to characterize specific microglial proteomic changes in 5xFAD mice and identify overlap with LPS-induced pro-inflammatory changes. Our results were also contrasted with existing proteomic data from wild-type mouse microglia and from existing microglial transcriptomic data from wild-type and 5xFAD mice. Neuropathological validation studies of select proteins were performed in human AD and 5xFAD brains. Of 4,133 proteins identified, 187 microglial proteins were differentially expressed in the 5xFAD mouse model of AD pathology, including proteins with previously known (Apoe, Clu and Htra1) as well as previously unreported relevance to AD biology (Cotl1 and Hexb). Proteins upregulated in 5xFAD microglia shared significant overlap with pro-inflammatory changes observed in LPS-treated mice. Several proteins increased in human AD brain were also upregulated by 5xFAD microglia (Aβ peptide, Apoe, Htra1, Cotl1 and Clu). Cotl1 was identified as a novel microglia-specific marker with increased expression and strong association with AD neuropathology. Apoe protein was also detected within plaque-associated microglia in which Apoe and Aβ were highly co-localized suggesting a role for Apoe in phagocytic clearance of Aβ. We report the first comprehensive comparative proteomic study of adult mouse microglia derived from acute neuroinflammatory and AD models, representing a valuable resource to the neuroscience research community. We highlight shared and unique microglial proteomic changes in acute neuroinflammatory, aging and AD mouse models in addition to identifying novel roles for microglial proteins in human neurodegeneration.
2018-09-18 | PXD009137 | Pride