PLCG2 modulates TREM2 expression and signaling in response to Alzheimer’s disease pathology
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE291648 | GEO | 2025/05/14
REPOSITORIES: GEO
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Project description:PLCG2 modulates TREM2 expression and signaling in response to Alzheimer’s disease pathology
| PRJNA1234569 | ENA
Project description:The most common form of senile dementia, Alzheimer’s disease (AD), is characterized by Aβ plaques and neurofibrillary tangles in the CNS. AD genetic studies have identified high-risk hypomorphic variants in TREM2, a myeloid cell surface receptor that enables concerted microglial responses to Aβ plaques and neuronal cell death, including proliferation, survival, clustering and phagocytosis. How TREM2 promotes these responses is not known. Here, we demonstrate that TREM2 drives mTOR signaling, which maintains high ATP levels, supports biosynthetic pathways and suppresses AMPK phosphorylation and autophagy. In vitro, TREM2-deficient macrophages undergo dramatically increased autophagy and die in response to growth factor limitation or ER stress. Excessive autophagy is also evident in microglia from Trem2-/- 5XFAD mice and in post-mortem specimens from AD patients carrying TREM2 risk variants. Metabolic derailment, autophagy and cell death can be circumvented by engaging alternative energy production pathways. Thus, restoring microglial energetic and anabolic levels may be a future therapeutic avenue for TREM2-associated neurological disease.
2017-08-15 | GSE98563 | GEO
Project description:TREM2, a microglia-specific receptor, is strongly associated with Alzheimer’s disease (AD) risk and modulates microglial responses critical to AD pathogenesis. However, its role in tauopathy and neurodegeneration remains unclear. Here, by using a PS19 tauopathy mouse model with inducible overexpression of human wild-type TREM2 (TREM2-WT) or the R47H variant (TREM2-R47H), we show that TREM2-WT overexpression modestly reduces soluble phosphorylated tau (p-tau) levels and mildly preserves neuronal integrity, whereas TREM2-R47H fails to impact p-tau levels or neurodegeneration. Single-cell RNA sequencing revealed that TREM2-WT enhances disease-associated microglia (DAM) signatures, while TREM2-R47H drives the MHCII+ microglial phenotypes. These findings demonstrate that TREM2-WT confers modest benefits in tauopathy models, whereas TREM2-R47H exhibits reduced functionality. Our study underscores the therapeutic potential of enhancing TREM2 activity to modulate microglial responses and mitigate neurodegeneration in AD.
2025-04-02 | GSE285713 | GEO
Project description:Alzheimer’s disease (AD) remains one of the grand challenges facing human society. Much controversy exists around the complex and multifaceted pathogenesis of this prevalent disease. Given strong human genetic evidence, there is little doubt, however, that microglia play an important role in preventing degeneration of neurons. E.g., loss-of-function of the microglial gene Trem2 render microglia dysfunctional and causes an early-onset neurodegenerative syndrome and Trem2 variants are among the strongest genetic risk factors for AD. Thus, restoring microglial function represents a rational therapeutic approach. Here we show that systemic hematopoietic cell transplantation followed by enhancement of microglia replacement restores microglial function in a Trem2 mutant model of Alzheimer’s disease.
2023-06-26 | GSE235607 | GEO
Project description:PLCG2 Regulates Divergent Microglial Functions via TREM2-Dependent and -Independent Signaling
| PRJNA602826 | ENA
Project description:Genetic findings have highlighted key roles for microglia in the pathology of neurodegenerative conditions such as Alzheimer’s disease (AD). A number of mutations in the microglial protein TREM2 (triggering receptor expressed on myeloid cells 2) have been associated with increased risk for developing Alzheimer’s disease (AD), most notably the R47H/+ substitution. We employed gene editing and stem cell models to gain insight into the effects of the TREM2 R47H/+ mutation on human iPSC-derived microglia. We found transcriptional changes affecting numerous cellular processes, with R47H/+ cells exhibiting a pro-inflammatory gene expression signature. TREM2 R47H/+ also caused impairments in microglial movement and the uptake of multiple substrates, as well as rendering microglia hyper-responsive to inflammatory stimuli. We developed an in vitro laser-induced injury model in neuron-microglia co-cultures, finding an impaired injury response by TREM2 R47H/+ microglia. Furthermore, mouse brains transplanted with TREM2 R47H/+ microglia exhibited reduced synaptic density, with upregulation of multiple complement cascade components in TREM2 R47H/+ microglia suggesting inappropriate synaptic pruning as one potential mechanism. These findings identify a number of potentially detrimental effects of the TREM2 R47H/+ mutation on microglial gene expression and function likely to underlie its association with AD.
2024-03-06 | GSE241858 | GEO
Project description:We use genetically engineered human iPSC-derived microglia-like cells (iMG) to show that TREM2 signals through PLCγ2 to mediate cell survival, phagocytosis, and lipid metabolism following myelin challenge. Loss of TREM2 or PLCγ2 signaling leads to a shared signature of transcriptional dysregulation that underlies these phenotypes. However, PLCγ2 also signals downstream of Toll-like receptors to mediate inflammatory responses in a TREM2-independent manner. Therefore, PLCγ2 activity regulates divergent microglial functions via distinct TREM2-dependent and -independent signaling and may be involved in the transition to a microglial state associated with neurodegenerative disease.
2020-05-24 | GSE144120 | GEO
Project description:TREM2 is a microglial cell surface receptor, with risk mutations linked to Alzheimer’s disease (AD), including R47H. TREM2 signalling via SYK aids phagocytosis, chemotaxis, survival, and changes to microglial activation state. In AD mouse models, knockout (KO) of TREM2 impairs microglial clustering around amyloid, and prevents microglial activation. The R47H mutation is proposed to reduce TREM2 ligand binding. We investigated cell phenotypes of the R47H mutant and TREM2 KO in a model of human microglia, and compared their transcriptional signatures, to determine the mechanism by which R47H TREM2 disrupts function. We generated human microglia-like iPSC-macrophages (pMac) from isogenic induced pluripotent stem cell (iPSC) lines, with homozygous R47H mutation or TREM2 knockout (KO). We firstly validated the effect of the R47H mutant on TREM2 surface and subcellular localization in pMac. To assess microglial phenotypic function we measured phagocytosis of dead neurons, cell morphology, directed migration, survival, and LPS-induced inflammation. We performed bulk RNA-seq, comparing significant differentially-expressed genes (DEGs: p<0.05) between the R47H and KO versus WT, and bioinformatically predicted potential upstream regulators of TREM2-mediated gene expression. Altered gene expression in the R47H TREM2 pMac overlapped by 90% with the TREM2 KO, and was characterized by dysregulation of genes involved with immunity, proliferation, activation, chemotaxis and adhesion. Downregulated mediators of ECM adhesion included the vitronectin receptor αVβ3, and consequently R47H TREM2 pMac adhered weakly to vitronectin compared with WT pMac. To counteract these transcriptional defects, we investigated TGFβ1, as a candidate upstream regulator. TGFβ1 failed to rescue vitronectin adhesion of pMac, although improved αVβ3 expression. The R47H mutation is not sufficient to cause gross phenotypic defects of human pMac under standard culture conditions. However, overlapping transcriptional defects with TREM2 KO supports the hypothesised partial loss-of-function effects of the R47H mutation. Furthermore, transcriptomics can guide us to more subtle phenotypic defects in the R47H cells, such as reduced cell adhesion, and can be used to predict targets for therapeutic intervention.
2020-11-24 | GSE157635 | GEO
Project description:Glia have been implicated in Alzheimer’s disease (AD) pathogenesis. Variants of the microglia receptor TREM2 increase AD risk and activation of “disease-associated microglia” (DAM) is dependent on TREM2 in mouse models of AD. We surveyed gene expression changes associated with AD pathology and TREM2 in 5XFAD mice and human AD by snRNA-seq. We confirmed the presence of Trem2-dependent DAM and identified a novel Serpina3n+C4b+ reactive oligodendrocyte population in mice. Interestingly, remarkably different glial phenotypes were evident in human AD. Microglia signature was reminiscent of IRF8-driven reactive microglia in peripheral nerve injury. Oligodendrocyte signatures suggested impaired axonal myelination and metabolic adaptation to neuronal degeneration. Astrocyte profiles indicated weakened metabolic coordination with neurons. Notably, the reactive phenotype of microglia was less palpable in TREM2 R47H and R62H carriers than in non-carriers, demonstrating a TREM2 requirement in both mouse and human AD, despite the marked species-specific differences.
2019-12-31 | GSE140399 | GEO
Project description:Glia have been implicated in Alzheimer’s disease (AD) pathogenesis. Variants of the microglia receptor TREM2 increase AD risk and activation of “disease-associated microglia” (DAM) is dependent on TREM2 in mouse models of AD. We surveyed gene expression changes associated with AD pathology and TREM2 in 5XFAD mice and human AD by snRNA-seq. We confirmed the presence of Trem2-dependent DAM and identified a novel Serpina3n+C4b+ reactive oligodendrocyte population in mice. Interestingly, remarkably different glial phenotypes were evident in human AD. Microglia signature was reminiscent of IRF8-driven reactive microglia in peripheral nerve injury. Oligodendrocyte signatures suggested impaired axonal myelination and metabolic adaptation to neuronal degeneration. Astrocyte profiles indicated weakened metabolic coordination with neurons. Notably, the reactive phenotype of microglia was less palpable in TREM2 R47H and R62H carriers than in non-carriers, demonstrating a TREM2 requirement in both mouse and human AD, despite the marked species-specific differences.
2019-12-31 | GSE140510 | GEO