APOE4/4 is linked to damaging lipid droplets in Alzheimer's microglia
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE254205 | GEO | 2024/02/01
REPOSITORIES: GEO
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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.
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Project description:Microglia is a primary brain immune cell type that has been implicated in the pathogenesis of neurodegenerative disorders such as Alzheimer’s disease (AD) and neurodevelopmental disorders such as schizophrenia. Generating microglia from human induced pluripotent stem cells (hiPSC) has become an attractive approach to study the microglia-mediated causal mechanism of AD. Among other methods, Brownjohn et al. recently developed a particularly efficient and simple hiPSC-derived microglia (iMG) protocol. However, the transferability of this method to other labs, the transcriptomic similarity of these iMG to primary adult microglia, and their genetic relevance to AD remain unclear. With two hiPSC lines, we demonstrated that the Brownjohn method can efficiently give rise to iMG that were morphologically and functionally like microglia. Our pure iMG were also transcriptionally similar to previously reported iMG lines, as well as fetal and adult microglia. More importantly, we further showed the genetic relevance of iMG to AD using cell type-specific gene expression to partition disease heritability. Contrasting with neuronal and immune cell types, our iMG and several primary microglia and microglia-like cell types were all significantly enriched for AD relevant GWAS loci. These results supported the use of iMG as a valid human cellular model for understanding AD disease progression and a feasible mechanism for generation of AD patient-specific cell types for more precise in vitro analyses, and potentially more effective clinical care.
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2023-07-18 | GSE208006 | GEO
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Project description:Variations in many genes linked to sporadic Alzheimer’s disease (AD), show abundant expression in microglia, however, relationships between these genes remain largely elusive. Here, we establish isogenic human ES-derived microglia-like cell lines (hMGLs) harboring AD variants in CD33, INPP5D, SORL1 and TREM2 loci, and curate a comprehensive atlas comprising ATACseq, ChIPseq, RNAseq and proteomics datasets. AD-like expression signatures are observed in AD mutant SORL1 and TREM2 hMGLs, while integrative multi-omic analysis of combined epigenetic and expression datasets indicates upregulation of APOE as a convergent pathogenic node. We also observe cross-regulatory relationships between SORL1 and TREM2, where SORL1R744X hMGLs induce TREM2 expression to enhance APOE expression. AD-associated SORL1 and TREM2 mutations also impaired hMGL Aβ uptake in an APOE-dependent manner in vitro, and attenuated Aβ uptake/clearance in mouse AD brain xenotransplants. Utilizing this modeling and analysis platform for human microglia, we provide new insight into epistatic interactions in AD genes and demonstrate convergence of microglial AD genes at the APOE locus.
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2020-09-01 | GSE153655 | GEO
Project description:Variations in many genes linked to sporadic Alzheimer’s disease (AD), show abundant expression in microglia, however, relationships between these genes remain largely elusive. Here, we establish isogenic human ES-derived microglia-like cell lines (hMGLs) harboring AD variants in CD33, INPP5D, SORL1 and TREM2 loci, and curate a comprehensive atlas comprising ATACseq, ChIPseq, RNAseq and proteomics datasets. AD-like expression signatures are observed in AD mutant SORL1 and TREM2 hMGLs, while integrative multi-omic analysis of combined epigenetic and expression datasets indicates upregulation of APOE as a convergent pathogenic node. We also observe cross-regulatory relationships between SORL1 and TREM2, where SORL1R744X hMGLs induce TREM2 expression to enhance APOE expression. AD-associated SORL1 and TREM2 mutations also impaired hMGL Aβ uptake in an APOE-dependent manner in vitro, and attenuated Aβ uptake/clearance in mouse AD brain xenotransplants. Utilizing this modeling and analysis platform for human microglia, we provide new insight into epistatic interactions in AD genes and demonstrate convergence of microglial AD genes at the APOE locus.
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