Integrative analysis reveals a conserved role for the amyloid precursor protein in proteostasis during aging
Ontology highlight
ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE231518 | GEO | 2023/10/03
REPOSITORIES: GEO
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Project description:Aβ peptides derived from the amyloid precursor protein (APP) have been strongly implicated in the pathogenesis of Alzheimer’s disease. However, the normal function of APP and the importance of that role in neurodegenerative disease is less clear. We recovered the Drosophila ortholog of APP, Appl, in an unbiased forward genetic screen for neurodegeneration mutants. We performed comprehensive single cell transcriptional and proteomic studies of Appl mutant flies to investigate Appl function in the aging brain.
2023-10-04 | PXD041862 | Pride
Project description:Genome-wide association studies (GWAS) have identified genes in lipid metabolism,inflammation and vesicular trafficking pathways as risk factors for late onset Alzheimer disease (LOAD). The mechanism by which they cause AD and their relationship to the amyloid cascade affected by genes causing early onset familial AD is unknown. Unproven hypotheses are that these LOAD genes modulate the amyloid cascade itself or downstream targets affected by this cascade.If so, it is likely that these genes and/or other genes in the same pathways may show alterations in their expression as an early consequence of misprocessing of amyloid precursor protein (APP) and accumulation of amyloid β-peptides (Aβ). We report that in three independent APP transgenic mouse models of AD, multiple genes in lipid and inflammation pathways show very early changes in mRNA and protein expression. Many of these changes are reversed by treatment with LXR agonists, which regulate transcription of genes in lipid/inflammation pathways, and which we have previously shown can reverse the cognitive deficits and neuropathology in Tg2756 mice. These results suggest that changes in lipid and inflammation pathways are likely to be very early consequences of APP misprocessing and Aβ accumulation in AD. Moreover, genetic variants within these pathways might affect risk for AD by modulating this early response. These pathways are likely to contain biomarkers of early disease and targets for therapies. TgCRND8 mice and wild-type littermate controls at ages 70, 80, and 150 days (n = 4 mice per cohort) were used in the study.
2014-08-12 | E-GEOD-31372 | biostudies-arrayexpress
Project description:Background: ABCA1 has recently been identified as a novel genetic risk factor for Alzheimer’s disease. The major known role of ABCA1 in the brain is to transfer lipids onto lipid poor APOE. Given that APOEε4 is the strongest genetic risk factor for developing late onset Alzheimer’s disease, this recent finding implicates the cholesterol homeostatic pathway in the onset/progression of Alzheimer’s disease. microRNAs (miRs) are small RNA species that negatively regulate expression of their target genes. ABCA1 is regulated by miR-33, and loss of this miR significantly increases protein levels of ABCA1 and increases the lipidation of APOE. However, it is unknown if loss of miR-33 and subsequent increase in ABCA1 protein levels ameliorates amyloid pathology. Methods: We generated miR-33+/+;APP/PS1 and miR-33-/-;APP/PS1 mice to determine changes in amyloid-beta (Aβ) peptides and amyloid plaque formation utilizing biochemical and histological analyses. In addition to amyloid pathology, we assessed if deletion of miR-33 altered the activation of glial cells in the brains of these mice. We utilized in vitro methods to determine if miR-33 alters the phagocytosis of Aβ aggregates. We utilized RNA-sequencing and mass spectrometry to identify the transcriptome and proteome regulation by miR-33 in the context of amyloid pathology. Results: Deletion of miR-33 dramatically reduces insoluble Aβ peptide levels and the deposition of amyloid plaques in APP/PS1 mice. In addition, we identified that astrocyte and microglial activation is markedly decreased in miR-33-/-;APP/PS1 mice through histological analyses. Intriguingly, we show that loss of miR-33 results in amyloid plaques that are more compact, potentially implicating enhanced microglial phagocytosis. We confirm in vitro that loss of miR-33 significantly increases microglial phagocytosis of Aβ aggregates. Our multi-omics analyses reveal that deletion of miR-33 regulates immune response in the context of amyloid pathology. Interestingly, we identified that WNT/Beta-catenin signaling is significantly upregulated in miR-33-/-;APP/PS1 mice. Conclusion: We confirm that the deletion of miR-33 increases APOE lipidation and significantly reduces amyloid pathology as well as glial activation in APP/PS1 mice. Our results agree with previous work identifying APOE lipidation as an important modulator of amyloid pathology. We show, for the first time, that loss of miR-33 increases the phagocytosis of Aβ by microglia. In total, we identify miR-33 as a promising target for the amelioration of amyloid pathology.
2024-09-30 | GSE235179 | GEO
Project description:Alzheimer’s disease (AD) is a progressive neurodegenerative disease and the most common cause of dementia, characterized by deposition of extracellular amyloid-beta (Aβ) aggregates and intraneuronal hyperphosphorylated Tau. Many AD risk genes, identified in genome-wide association studies (GWAS), are expressed in microglia, the innate immune cells of the central nervous system. Specific subtypes of microglia emerged in relation to AD pathology, such as disease-associated microglia (DAMs), which increased in number with age in amyloid mouse models and in human AD cases. However, the initial transcriptional changes in these microglia in response to amyloid are still unknown. Here, to determine early changes in microglia gene expression, hippocampal microglia from APPswe/PS1dE9 (APP/PS1) mice and wildtype littermates were isolated and analyzed by RNA sequencing (RNA-seq). By bulk RNA-seq, transcriptomic changes were detected in hippocampal microglia from 6-months-old APP/PS1 mice. By performing single cell RNA-seq of CD11c-positive and negative microglia from 6-months-old APP/PS1 mice and analysis of the transcriptional trajectory from homeostatic to CD11c-positive microglia, we identified a set of genes that potentally reflect the initial response of microglia to Aβ.
2024-04-01 | GSE226938 | GEO
Project description:Alzheimer’s disease (AD) is a progressive neurodegenerative disease and the most common cause of dementia, characterized by deposition of extracellular amyloid-beta (Aβ) aggregates and intraneuronal hyperphosphorylated Tau. Many AD risk genes, identified in genome-wide association studies (GWAS), are expressed in microglia, the innate immune cells of the central nervous system. Specific subtypes of microglia emerged in relation to AD pathology, such as disease-associated microglia (DAMs), which increased in number with age in amyloid mouse models and in human AD cases. However, the initial transcriptional changes in these microglia in response to amyloid are still unknown. Here, to determine early changes in microglia gene expression, hippocampal microglia from APPswe/PS1dE9 (APP/PS1) mice and wildtype littermates were isolated and analyzed by RNA sequencing (RNA-seq). By bulk RNA-seq, transcriptomic changes were detected in hippocampal microglia from 6-months-old APP/PS1 mice. By performing single cell RNA-seq of CD11c-positive and negative microglia from 6-months-old APP/PS1 mice and analysis of the transcriptional trajectory from homeostatic to CD11c-positive microglia, we identified a set of genes that potentally reflect the initial response of microglia to Aβ.
2024-04-01 | GSE226937 | GEO
Project description:The amyloid precursor protein (APP) plays a central role in the pathogenesis of Alzheimer’s disease (AD). Processing of APP by β- and γ-secretase activities results in the production of ß-amyloid (Aß), the main constituent of Alzheimer plaques, but also in the generation of the APP intracellular domain (AICD). Recently, it has been demonstrated that AICD has transactivation potential, however, the targets of AICD dependent gene regulation and hence the physiological role of AICD remain largely unknown. In this work we analysed transcriptome changes during AICD dependent gene regulation using a human neural cell culture system inducible for expression of AICD, its co-activator Fe65, or the combination of both. Induction of AICD was associated with increased expression of genes with known function in the organization and dynamics of the actin cytoskeleton as well as genes involved in the regulation of apoptosis. Keywords: (Tet-Off)
2006-05-01 | GSE4097 | GEO
Project description:Genome-wide association studies (GWAS) have identified genes in lipid metabolism,inflammation and vesicular trafficking pathways as risk factors for late onset Alzheimer disease (LOAD). The mechanism by which they cause AD and their relationship to the amyloid cascade affected by genes causing early onset familial AD is unknown. Unproven hypotheses are that these LOAD genes modulate the amyloid cascade itself or downstream targets affected by this cascade.If so, it is likely that these genes and/or other genes in the same pathways may show alterations in their expression as an early consequence of misprocessing of amyloid precursor protein (APP) and accumulation of amyloid β-peptides (Aβ). We report that in three independent APP transgenic mouse models of AD, multiple genes in lipid and inflammation pathways show very early changes in mRNA and protein expression. Many of these changes are reversed by treatment with LXR agonists, which regulate transcription of genes in lipid/inflammation pathways, and which we have previously shown can reverse the cognitive deficits and neuropathology in Tg2756 mice. These results suggest that changes in lipid and inflammation pathways are likely to be very early consequences of APP misprocessing and Aβ accumulation in AD. Moreover, genetic variants within these pathways might affect risk for AD by modulating this early response. These pathways are likely to contain biomarkers of early disease and targets for therapies.
2014-08-12 | GSE31372 | GEO
Project description:The β-amyloid precursor protein APP and the related APLPs, undergo complex proteolytic processing giving rise to several fragments. Whereas it is well established that Aβ accumulation is a central trigger for Alzheimer disease (AD), the physiological role of APP family members and their diverse proteolytic products is still largely unknown. The secreted APPsα ectodomain has been shown to be involved in neuroprotection and synaptic plasticity. The γ-secretase generated APP intracellular domain AICD, functions as a transciptional regulator in heterologous reporter assays, although its role for endogenous gene regulation has remained controversial. To gain further insight into the molecular changes associated with knockout phenotypes and to elucidate the physiological functions of APP family members including their proposed role as transcriptional regulators we performed a DNA microarray transcriptome profiling of the frontal cortex of adult wild type, APP-/-, APLP2-/- and APPsα knockin (KI) mice, APPα/α, expressing solely the secreted APPsα ectodomain. Biological pathways affected by the lack of APP family members included regulation of neurogenesis, regulation of transcription and regulation of neuron projection development. Comparative analysis of transcriptome changes and qPCR validation identified co-regulated gene sets. Interestingly, these included heat shock proteins and plasticity related genes that were down-regulated in knock-out cortices. In contrast, we failed to detect significant differences in expression of previously proposed AICD target genes including Bace1, Kai1, Gsk3b, p53, Tip60 and Vglut2. Only Egfr was slightly up-regulated in APLP2-/- mice. Comparison of APP-/- and APPα/α with wild-type mice revealed a high proportion of co-regulated genes indicating an important role of the C-terminus for cellular signaling. Finally, comparison of APLP2-/- on different genetic backgrounds revealed that background related transcriptome changes may dominate over changes due to the knockout of a single gene. Shared transcriptome profiles corroborated closely related physiological functions of APP family members in the adult central nervous system. As expression of proposed AICD target genes was not altered in adult cortex, this may indicate that these genes are not affected by lack of APP under resting conditions or only in a small subset of cells.
2011-03-18 | GSE25926 | GEO
Project description:Objective: Blast induced traumatic brain injuries are a signature injury of recent war campaigns; yet little is known about the biological mechanisms underlying blast exposures. Methods: In a group of military personnel (N = 69), prior to, and on each day of a blast training program (10 days total), blood was collected; throughout training, blast exposure measures were detected by helmet sensors to determine the mean peak pressure in pounds per square inch (psi). On day 7, some participants (n= 29) sustained a moderate blast (mean peak pressure = 7.9 psi) and were matched to participants with no/low blast exposure during the training (n = 40). Results: RNA-seq identified 1,803 dysregulated genes, including 746 up-regulated genes and 1,058 down-regulated genes following a moderate blast exposure. The IPA showed the APP gene network to be most dysregulated following blast, with an IPA network score of 43. Real-time qPCR was used to validate the expression changes for four genes 4 genes, namely: amyloid precursor protein (APP), amyloid precursor-like protein 2 (APLP2), nicastrin (NCSTN) and NEDD8 Activating Enzyme E1 Subunit 1 (NAE1) and significant dysregulation of these genes was confirmed (p = 0.00083476, p = 0.000105, p = 0.000673 and p = 0.043145, respectively). Conclusions: Moderate blast exposure results in a signature biological profile that includes acute APP reductions, followed by genetic expression increases and normalization of APP levels; these changes likely influence neuronal recovery.
2019-11-15 | GSE89866 | GEO
Project description:The β-amyloid precursor protein APP and the related APLPs, undergo complex proteolytic processing giving rise to several fragments. Whereas it is well established that Aβ accumulation is a central trigger for Alzheimer disease (AD), the physiological role of APP family members and their diverse proteolytic products is still largely unknown. The secreted APPsα ectodomain has been shown to be involved in neuroprotection and synaptic plasticity. The γ-secretase generated APP intracellular domain AICD, functions as a transciptional regulator in heterologous reporter assays, although its role for endogenous gene regulation has remained controversial. To gain further insight into the molecular changes associated with knockout phenotypes and to elucidate the physiological functions of APP family members including their proposed role as transcriptional regulators we performed a DNA microarray transcriptome profiling of the frontal cortex of adult wild type, APP-/-, APLP2-/- and APPsα knockin (KI) mice, APPα/α, expressing solely the secreted APPsα ectodomain. Biological pathways affected by the lack of APP family members included regulation of neurogenesis, regulation of transcription and regulation of neuron projection development. Comparative analysis of transcriptome changes and qPCR validation identified co-regulated gene sets. Interestingly, these included heat shock proteins and plasticity related genes that were down-regulated in knock-out cortices. In contrast, we failed to detect significant differences in expression of previously proposed AICD target genes including Bace1, Kai1, Gsk3b, p53, Tip60 and Vglut2. Only Egfr was slightly up-regulated in APLP2-/- mice. Comparison of APP-/- and APPα/α with wild-type mice revealed a high proportion of co-regulated genes indicating an important role of the C-terminus for cellular signaling. Finally, comparison of APLP2-/- on different genetic backgrounds revealed that background related transcriptome changes may dominate over changes due to the knockout of a single gene. Shared transcriptome profiles corroborated closely related physiological functions of APP family members in the adult central nervous system. As expression of proposed AICD target genes was not altered in adult cortex, this may indicate that these genes are not affected by lack of APP under resting conditions or only in a small subset of cells. Prefrontal cortices of adult male mice (24 - 28 weeks) of the following genotypes were analyzed: WT (n=3), APP-/- (n=3), APPα/α (n=3), APLP2-/- (n=3), APLP2(R1)-/- (n=3). WT, APP-/-, APPα/α, APLP2-/- had been backcrossed for six generations to C57BL/6 mice. APLP2(R1)-/- harbors the identical knockout allele as APLP2-/- but was back-crossed only once.
2011-03-18 | E-GEOD-25926 | biostudies-arrayexpress