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INTRODUCTION: The apolipoprotein E gene (APOE) is an established central player in the pathogenesis of Alzheimer's disease (AD), with distinct apoE isoforms exerting diverse effects. apoE influences not only amyloid-beta and tau pathologies but also lipid and energy metabolism, neuroinflammation, cerebral vascular health, and sex-dependent disease manifestations. Furthermore, ancestral background may significantly impact the link between APOE and AD, underscoring the need for more inclusive research. METHODS: In 2023, the Alzheimer's Association convened multidisciplinary researchers at the "AAIC Advancements: APOE" conference to discuss various topics, including apoE isoforms and their roles in AD pathogenesis, progress in apoE-targeted therapeutic strategies, updates on disease models and interventions that modulate apoE expression and function. RESULTS: This manuscript presents highlights from the conference and provides an overview of opportunities for further research in the field. DISCUSSION: Understanding apoE's multifaceted roles in AD pathogenesis will help develop targeted interventions for AD and advance the field of AD precision medicine. HIGHLIGHTS: APOE is a central player in the pathogenesis of Alzheimer's disease. APOE exerts a numerous effects throughout the brain on amyloid-beta, tau, and other pathways. The AAIC Advancements: APOE conference encouraged discussions and collaborations on understanding the role of APOE.
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The immune system substantially influences age-related cognitive decline and Alzheimer's disease (AD) progression, affected by genetic and environmental factors. In a Mayo Clinic Study of Aging cohort, we examined how risk factors like APOE genotype, age, and sex affect inflammatory molecules and AD biomarkers in cerebrospinal fluid (CSF). Among cognitively unimpaired individuals over 65 (N = 298), we measured 365 CSF inflammatory molecules, finding age, sex, and diabetes status predominantly influencing their levels. We observed age-related correlations with AD biomarkers such as total tau, phosphorylated tau-181, neurofilament light chain (NfL), and YKL40. APOE4 was associated with lower Aß42 and higher SNAP25 in CSF. We explored baseline variables predicting cognitive decline risk, finding age, CSF Aß42, NfL, and REG4 to be independently correlated. Subjects with older age, lower Aß42, higher NfL, and higher REG4 at baseline had increased cognitive impairment risk during follow-up. This suggests that assessing CSF inflammatory molecules and AD biomarkers could predict cognitive impairment risk in the elderly.
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Enfermedad de Alzheimer , Disfunción Cognitiva , Humanos , Anciano , Enfermedad de Alzheimer/diagnóstico , Enfermedad de Alzheimer/etiología , Enfermedad de Alzheimer/líquido cefalorraquídeo , Disfunción Cognitiva/diagnóstico , Disfunción Cognitiva/etiología , Proteínas tau , Biomarcadores , Péptidos beta-Amiloides , Fragmentos de PéptidosRESUMEN
Microglial involvement in Alzheimer's disease (AD) pathology has emerged as a risk-determining pathogenic event. While apolipoprotein E (APOE) is known to modify AD risk, it remains unclear how microglial apoE impacts brain cognition and AD pathology. Here, using conditional mouse models expressing apoE isoforms in microglia and central nervous system-associated macrophages (CAMs), we demonstrate a cell-autonomous effect of apoE3-mediated microglial activation and function, which are negated by apoE4. Expression of apoE3 in microglia/CAMs improves cognitive function, increases microglia surrounding amyloid plaque and reduces amyloid pathology and associated toxicity, whereas apoE4 expression either compromises or has no effects on these outcomes by impairing lipid metabolism. Single-cell transcriptomic profiling reveals increased antigen presentation and interferon pathways upon apoE3 expression. In contrast, apoE4 expression downregulates complement and lysosomal pathways, and promotes stress-related responses. Moreover, in the presence of mouse endogenous apoE, microglial apoE4 exacerbates amyloid pathology. Finally, we observed a reduction in Lgals3-positive responsive microglia surrounding amyloid plaque and an increased accumulation of lipid droplets in APOE4 human brains and induced pluripotent stem cell-derived microglia. Our findings establish critical isoform-dependent effects of microglia/CAM-expressed apoE in brain function and the development of amyloid pathology, providing new insight into how apoE4 vastly increases AD risk.
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Enfermedad de Alzheimer , Ratones , Animales , Humanos , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/patología , Apolipoproteína E4/genética , Apolipoproteína E4/metabolismo , Microglía/metabolismo , Apolipoproteína E3/genética , Apolipoproteína E3/metabolismo , Placa Amiloide/metabolismo , Placa Amiloide/patología , Apolipoproteínas E/genética , Apolipoproteínas E/metabolismo , Encéfalo , Homeostasis , Ratones TransgénicosRESUMEN
The prevalence of Alzheimer's disease is greater in women, but the underlying mechanisms remain to be elucidated. We herein demonstrated that α-secretase ADAM10 was downregulated and ADAM10 inhibitor sFRP1 was upregulated in 5xFAD mice. While there were no sex effects on ADAM10 protein and sFRP1 mRNA levels, female 5xFAD and age-matched non-transgenic mice exhibited higher levels of sFRP1 protein than corresponding male mice. Importantly, female 5xFAD mice accumulated more Aß than males, and sFRP1 protein levels were positively associated with Aß42 levels in 5xFAD mice. Our study suggests that sFRP1 is associated with amyloid pathology in a sex-dependent manner.
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Enfermedad de Alzheimer , Precursor de Proteína beta-Amiloide , Animales , Femenino , Masculino , Ratones , Proteína ADAM10/genética , Proteína ADAM10/metabolismo , Enfermedad de Alzheimer/patología , Amiloide/metabolismo , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Proteínas Amiloidogénicas/metabolismo , Ácido Aspártico Endopeptidasas/metabolismo , Encéfalo/patología , Modelos Animales de Enfermedad , Ratones Transgénicos , Regulación hacia ArribaRESUMEN
Vascular cognitive impairment and dementia (VCID) is commonly caused by vascular injuries in cerebral large and small vessels and is a key driver of age-related cognitive decline. Severe VCID includes post-stroke dementia, subcortical ischemic vascular dementia, multi-infarct dementia, and mixed dementia. While VCID is acknowledged as the second most common form of dementia after Alzheimer's disease (AD) accounting for 20% of dementia cases, VCID and AD frequently coexist. In VCID, cerebral small vessel disease (cSVD) often affects arterioles, capillaries, and venules, where arteriolosclerosis and cerebral amyloid angiopathy (CAA) are major pathologies. White matter hyperintensities, recent small subcortical infarcts, lacunes of presumed vascular origin, enlarged perivascular space, microbleeds, and brain atrophy are neuroimaging hallmarks of cSVD. The current primary approach to cSVD treatment is to control vascular risk factors such as hypertension, dyslipidemia, diabetes, and smoking. However, causal therapeutic strategies have not been established partly due to the heterogeneous pathogenesis of cSVD. In this review, we summarize the pathophysiology of cSVD and discuss the probable etiological pathways by focusing on hypoperfusion/hypoxia, blood-brain barriers (BBB) dysregulation, brain fluid drainage disturbances, and vascular inflammation to define potential diagnostic and therapeutic targets for cSVD.
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Enfermedad de Alzheimer , Enfermedades de los Pequeños Vasos Cerebrales , Demencia Vascular , Humanos , Causalidad , Factores de Riesgo , Enfermedades de los Pequeños Vasos Cerebrales/complicacionesRESUMEN
Cerebrovasculature is critical in maintaining brain homeostasis; its dysregulation often leads to vascular cognitive impairment and dementia (VCID) during aging. VCID is the second most prevalent cause of dementia in the elderly, after Alzheimer's disease (AD), with frequent cooccurrence of VCID and AD. While multiple factors are involved in the pathogenesis of AD and VCID, APOE4 increases the risk for both diseases. A major apolipoprotein E (apoE) receptor, the low-density lipoprotein receptor-related protein 1 (LRP1), is abundantly expressed in vascular mural cells (pericytes and smooth muscle cells). Here, we investigated how deficiency of vascular mural cell LRP1 affects the cerebrovascular system and cognitive performance using vascular mural cell-specific Lrp1-KO mice (smLrp1-/-) in a human APOE3 or APOE4 background. We found that spatial memory was impaired in the 13- to 16-month-old APOE4 smLrp1-/- mice but not in the APOE3 smLrp1-/- mice, compared with their respective littermate control mice. These disruptions in the APOE4 smLrp1-/- mice were accompanied with excess paravascular glial activation and reduced cerebrovascular collagen IV. In addition, blood-brain barrier (BBB) integrity was disrupted in the APOE4 smLrp1-/- mice. Together, our results suggest that vascular mural cell LRP1 modulates cerebrovasculature integrity and function in an APOE genotype-dependent manner.
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Enfermedad de Alzheimer , Apolipoproteína E4 , Humanos , Ratones , Animales , Anciano , Lactante , Apolipoproteína E4/genética , Apolipoproteína E3/metabolismo , Apolipoproteínas E/metabolismo , Barrera Hematoencefálica/metabolismo , Enfermedad de Alzheimer/patología , Proteína 1 Relacionada con Receptor de Lipoproteína de Baja Densidad/metabolismoRESUMEN
BACKGROUND: The rare p.H157Y variant of TREM2 (Triggering Receptor Expressed on Myeloid Cells 2) was found to increase Alzheimer's disease (AD) risk. This mutation is located at the cleavage site of TREM2 extracellular domain. Ectopic expression of TREM2-H157Y in HEK293 cells resulted in increased TREM2 shedding. However, the physiological outcomes of the TREM2 H157Y mutation remain unknown in the absence and presence of AD related pathologies. METHODS: We generated a novel Trem2 H157Y knock-in mouse model through CRISPR/Cas9 technology and investigated the effects of Trem2 H157Y on TREM2 proteolytic processing, synaptic function, and AD-related amyloid pathologies by conducting biochemical assays, targeted mass spectrometry analysis of TREM2, hippocampal electrophysiology, immunofluorescent staining, in vivo micro-dialysis, and cortical bulk RNA sequencing. RESULTS: Consistent with previous in vitro findings, Trem2 H157Y increases TREM2 shedding with elevated soluble TREM2 levels in the brain and serum. Moreover, Trem2 H157Y enhances synaptic plasticity without affecting microglial density and morphology, or TREM2 signaling. In the presence of amyloid pathology, Trem2 H157Y accelerates amyloid-ß (Aß) clearance and reduces amyloid burden, dystrophic neurites, and gliosis in two independent founder lines. Targeted mass spectrometry analysis of TREM2 revealed higher ratios of soluble to full-length TREM2-H157Y compared to wild-type TREM2, indicating that the H157Y mutation promotes TREM2 shedding in the presence of Aß. TREM2 signaling was further found reduced in Trem2 H157Y homozygous mice. Transcriptomic profiling revealed that Trem2 H157Y downregulates neuroinflammation-related genes and an immune module correlated with the amyloid pathology. CONCLUSION: Taken together, our findings suggest beneficial effects of the Trem2 H157Y mutation in synaptic function and in mitigating amyloid pathology. Considering the genetic association of TREM2 p.H157Y with AD risk, we speculate TREM2 H157Y in humans might increase AD risk through an amyloid-independent pathway, such as its effects on tauopathy and neurodegeneration which merit further investigation.
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Péptidos beta-Amiloides , Proteínas Amiloidogénicas , Humanos , Animales , Ratones , Células HEK293 , Encéfalo , Modelos Animales de Enfermedad , Glicoproteínas de Membrana/genética , Receptores Inmunológicos/genéticaRESUMEN
BACKGROUND: Abnormal lipid accumulation has been recognized as a key element of immune dysregulation in microglia whose dysfunction contributes to neurodegenerative diseases. Microglia play essential roles in the clearance of lipid-rich cellular debris upon myelin damage or demyelination, a common pathogenic event in neuronal disorders. Apolipoprotein E (apoE) plays a pivotal role in brain lipid homeostasis; however, the apoE isoform-dependent mechanisms regulating microglial response upon demyelination remain unclear. METHODS: To determine how apoE isoforms impact microglial response to myelin damage, 2-month-old apoE2-, apoE3-, and apoE4-targeted replacement (TR) mice were fed with normal diet (CTL) or 0.2% cuprizone (CPZ) diet for four weeks to induce demyelination in the brain. To examine the effects on subsequent remyelination, the cuprizone diet was switched back to regular chow for an additional two weeks. After treatment, brains were collected and subjected to immunohistochemical and biochemical analyses to assess the myelination status, microglial responses, and their capacity for myelin debris clearance. Bulk RNA sequencing was performed on the corpus callosum (CC) to address the molecular mechanisms underpinning apoE-mediated microglial activation upon demyelination. RESULTS: We demonstrate dramatic isoform-dependent differences in the activation and function of microglia upon cuprizone-induced demyelination. ApoE2 microglia were hyperactive and more efficient in clearing lipid-rich myelin debris, whereas apoE4 microglia displayed a less activated phenotype with reduced clearance efficiency, compared with apoE3 microglia. Transcriptomic profiling revealed that key molecules known to modulate microglial functions had differential expression patterns in an apoE isoform-dependent manner. Importantly, apoE4 microglia had excessive buildup of lipid droplets, consistent with an impairment in lipid metabolism, whereas apoE2 microglia displayed a superior ability to metabolize myelin enriched lipids. Further, apoE2-TR mice had a greater extent of remyelination; whereas remyelination was compromised in apoE4-TR mice. CONCLUSIONS: Our findings provide critical mechanistic insights into how apoE isoforms differentially regulate microglial function and the maintenance of myelin dynamics, which may inform novel therapeutic avenues for targeting microglial dysfunctions in neurodegenerative diseases.
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Apolipoproteína E4 , Enfermedades Desmielinizantes , Animales , Ratones , Apolipoproteína E2 , Apolipoproteína E4/genética , Microglía , Apolipoproteína E3 , Metabolismo de los Lípidos , Cuprizona/toxicidad , Apolipoproteínas ERESUMEN
The ε4 allele of the apolipoprotein E (APOE) gene, a genetic risk factor for Alzheimer's disease, is abundantly expressed in both the brain and periphery. Here, we present evidence that peripheral apoE isoforms, separated from those in the brain by the blood-brain barrier, differentially impact Alzheimer's disease pathogenesis and cognition. To evaluate the function of peripheral apoE, we developed conditional mouse models expressing human APOE3 or APOE4 in the liver with no detectable apoE in the brain. Liver-expressed apoE4 compromised synaptic plasticity and cognition by impairing cerebrovascular functions. Plasma proteome profiling revealed apoE isoform-dependent functional pathways highlighting cell adhesion, lipoprotein metabolism and complement activation. ApoE3 plasma from young mice improved cognition and reduced vessel-associated gliosis when transfused into aged mice, whereas apoE4 compromised the beneficial effects of young plasma. A human induced pluripotent stem cell-derived endothelial cell model recapitulated the plasma apoE isoform-specific effect on endothelial integrity, further supporting a vascular-related mechanism. Upon breeding with amyloid model mice, liver-expressed apoE4 exacerbated brain amyloid pathology, whereas apoE3 reduced it. Our findings demonstrate pathogenic effects of peripheral apoE4, providing a strong rationale for targeting peripheral apoE to treat Alzheimer's disease.
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Enfermedad de Alzheimer , Células Madre Pluripotentes Inducidas , Enfermedad de Alzheimer/metabolismo , Animales , Apolipoproteína E3/genética , Apolipoproteína E3/metabolismo , Apolipoproteína E4/genética , Apolipoproteína E4/metabolismo , Apolipoproteínas E/genética , Encéfalo/metabolismo , Cognición , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Ratones , Ratones Transgénicos , Isoformas de Proteínas/metabolismoRESUMEN
Apolipoprotein E (APOE) genetic variants have been shown to modify Alzheimer's disease (AD) risk. We previously identified an APOE3 variant (APOE3-V236E), named APOE3-Jacksonville (APOE3-Jac), associated with healthy brain aging and reduced risk for AD and dementia with Lewy bodies (DLB). Herein, we resolved the functional mechanism by which APOE3-Jac reduces APOE aggregation and enhances its lipidation in human brains, as well as in cellular and biochemical assays. Compared to APOE3, expression of APOE3-Jac in astrocytes increases several classes of lipids in the brain including phosphatidylserine, phosphatidylethanolamine, phosphatidic acid, and sulfatide, critical for synaptic functions. Mice expressing APOE3-Jac have reduced amyloid pathology, plaque-associated immune responses, and neuritic dystrophy. The V236E substitution is also sufficient to reduce the aggregation of APOE4, whose gene allele is a major genetic risk factor for AD and DLB. These findings suggest that targeting APOE aggregation might be an effective strategy for treating a subgroup of individuals with AD and DLB.
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Apolipoproteína E3/genética , Demencia , Apolipoproteínas E , Demencia/genética , HumanosRESUMEN
APOE4 is a strong genetic risk factor for Alzheimer's disease and Dementia with Lewy bodies; however, how its expression impacts pathogenic pathways in a human-relevant system is not clear. Here using human iPSC-derived cerebral organoid models, we find that APOE deletion increases α-synuclein (αSyn) accumulation accompanied with synaptic loss, reduction of GBA levels, lipid droplet accumulation and dysregulation of intracellular organelles. These phenotypes are partially rescued by exogenous apoE2 and apoE3, but not apoE4. Lipidomics analysis detects the increased fatty acid utilization and cholesterol ester accumulation in apoE-deficient cerebral organoids. Furthermore, APOE4 cerebral organoids have increased αSyn accumulation compared to those with APOE3. Carrying APOE4 also increases apoE association with Lewy bodies in postmortem brains from patients with Lewy body disease. Our findings reveal the predominant role of apoE in lipid metabolism and αSyn pathology in iPSC-derived cerebral organoids, providing mechanistic insights into how APOE4 drives the risk for synucleinopathies.
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Apolipoproteínas E/metabolismo , Metabolismo de los Lípidos/fisiología , Organoides/patología , Sinucleinopatías/metabolismo , alfa-Sinucleína/metabolismo , Animales , Humanos , Células Madre Pluripotentes Inducidas , Ratones , Organoides/metabolismo , Isoformas de Proteínas/metabolismo , Sinucleinopatías/patologíaRESUMEN
Cerebral blood vessels supply oxygen and nutrients, remove metabolic waste, and play a critical role in maintaining brain homeostasis. Cerebrovasculature is composed of heterogeneous populations of brain vascular cells (BVCs). A major challenge in effective cerebrovascular transcriptional profiling is high-quality BVC procurement, permitting high sequencing depth. Here, we establish cell isolation procedures for glio-vascular cell-enriched single-cell RNA sequencing enabling unbiased characterization of BVC transcriptional heterogeneity. Our approach can be used to address vascular-specific contribution to brain diseases. For complete details on the use and execution of this protocol, please refer to Yamazaki et al. (2021).
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Encéfalo/irrigación sanguínea , Secuenciación del Exoma/métodos , Análisis de la Célula Individual/métodos , Animales , Células Sanguíneas/metabolismo , Vasos Sanguíneos , Encéfalo/metabolismo , Sistema Cardiovascular/metabolismo , Circulación Cerebrovascular/fisiología , Ratones , Análisis de Secuencia de ARN/métodos , Suspensiones/aislamiento & purificaciónRESUMEN
The ε4 allele of the apolipoprotein E gene (APOE4) is a strong genetic risk factor for Alzheimer's disease (AD) and multiple vascular conditions. ApoE is abundantly expressed in multiple brain cell types, including astrocytes, microglia, and vascular mural cells (VMCs). Here, we show that VMC-specific expression of apoE4 in mice impairs behavior and cerebrovascular function. Expression of either apoE3 or apoE4 in VMCs was sufficient to rescue the hypercholesterolemia and atherosclerosis phenotypes seen in Apoe knockout mice. Intriguingly, vascular expression of apoE4, but not apoE3, reduced arteriole blood flow, impaired spatial learning, and increased anxiety-like phenotypes. Single-cell RNA sequencing of vascular and glial cells revealed that apoE4 in VMCs was associated with astrocyte activation, while apoE3 was linked to angiogenic signature in pericytes. Together, our data support cell-autonomous effects of vascular apoE on brain homeostasis in an isoform-dependent manner, suggesting a critical contribution of vascular apoE to AD pathogenesis.
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Apolipoproteína E4/genética , Arteriolas/metabolismo , Astrocitos/metabolismo , Encéfalo/metabolismo , Gliosis/genética , Animales , Apolipoproteína E3/genética , Apolipoproteína E3/metabolismo , Apolipoproteína E4/metabolismo , Arteriolas/patología , Astrocitos/patología , Encéfalo/patología , Gliosis/metabolismo , Gliosis/patología , Ratones , Ratones TransgénicosRESUMEN
APOE4 is the strongest genetic risk factor associated with late-onset Alzheimer's disease (AD). To address the underlying mechanism, we develop cerebral organoid models using induced pluripotent stem cells (iPSCs) with APOE ε3/ε3 or ε4/ε4 genotype from individuals with either normal cognition or AD dementia. Cerebral organoids from AD patients carrying APOE ε4/ε4 show greater apoptosis and decreased synaptic integrity. While AD patient-derived cerebral organoids have increased levels of Aß and phosphorylated tau compared to healthy subject-derived cerebral organoids, APOE4 exacerbates tau pathology in both healthy subject-derived and AD patient-derived organoids. Transcriptomics analysis by RNA-sequencing reveals that cerebral organoids from AD patients are associated with an enhancement of stress granules and disrupted RNA metabolism. Importantly, isogenic conversion of APOE4 to APOE3 attenuates the APOE4-related phenotypes in cerebral organoids from AD patients. Together, our study using human iPSC-organoids recapitulates APOE4-related phenotypes and suggests APOE4-related degenerative pathways contributing to AD pathogenesis.
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Enfermedad de Alzheimer/metabolismo , Apolipoproteína E3/genética , Apolipoproteína E3/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Organoides/metabolismo , Sinapsis/metabolismo , Enfermedad de Alzheimer/genética , Apolipoproteína E4/genética , Regulación de la Expresión Génica , Genotipo , Humanos , Organoides/patología , ARN/metabolismo , TranscriptomaRESUMEN
Investigations of apolipoprotein E (APOE) gene, the major genetic risk modifier for Alzheimer's disease (AD), have yielded significant insights into the pathogenic mechanism. Among the three common coding variants, APOE*ε4 increases, whereas APOE*ε2 decreases the risk of late-onset AD compared with APOE*ε3. Despite increased understanding of the detrimental effect of APOE*ε4, it remains unclear how APOE*ε2 confers protection against AD. Accumulating evidence suggests that APOE*ε2 protects against AD through both amyloid-ß (Aß)-dependent and independent mechanisms. In addition, APOE*ε2 has been identified as a longevity gene, suggesting a systemic effect of APOE*ε2 on the aging process. However, APOE*ε2 is not entirely benign; APOE*ε2 carriers exhibit increased risk of certain cerebrovascular diseases and neurological disorders. Here, we review evidence from both human and animal studies demonstrating the protective effect of APOE*ε2 against AD and propose a working model depicting potential underlying mechanisms. Finally, we discuss potential therapeutic strategies designed to leverage the protective effect of APOE2 to treat AD.
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Enfermedad de Alzheimer/genética , Apolipoproteína E2/genética , Animales , HumanosRESUMEN
Mutation of Triggering receptor expressed on myeloid cells 2 (TREM2) impairs the response of microglia to amyloid-ß (Aß) pathology in Alzheimer's disease (AD), although the mechanism governing TREM2-regulated microglia recruitment to Aß plaques remains unresolved. Here, we confirm that TREM2 mutation attenuates microglial migration. Then, using Trem2-/- mice and an R47H variant mouse model for AD generated for this study, we show that TREM2 deficiency or the AD-associated R47H mutation results in inhibition of FAK and Rac1/Cdc42-GTPase signaling critical for cell migration. Intriguingly, treatment with CN04, a Rac1/Cdc42-GTPase activator, partially enhances microglial migration in response to oligomeric Aß42 in Trem2-/- or R47H microglia both in vitro and in vivo. Our study shows that the dysfunction of microglial migration in the AD-associated TREM2 R47H variant is caused by FAK/Rac1/Cdc42 signaling disruption, and that activation of this signaling ameliorates impaired microglial migration response to Aß42 , suggesting a therapeutic target for R47H-bearing patients with high risk of AD.
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Péptidos beta-Amiloides/genética , Movimiento Celular/genética , Quinasa 1 de Adhesión Focal/genética , GTP Fosfohidrolasas/genética , Microglía/patología , Células Mieloides/metabolismo , Neuropéptidos/genética , Fragmentos de Péptidos/genética , Proteína de Unión al GTP cdc42/genética , Proteína de Unión al GTP rac1/genética , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/patología , Animales , Encéfalo/patología , Células Cultivadas , Modelos Animales de Enfermedad , Mutación con Pérdida de Función/genética , Masculino , Glicoproteínas de Membrana/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Microglía/metabolismo , Células Mieloides/patología , Transducción de Señal/genéticaRESUMEN
Evidence suggests interplay among the three major risk factors for Alzheimer's disease (AD): age, APOE genotype, and sex. Here, we present comprehensive datasets and analyses of brain transcriptomes and blood metabolomes from human apoE2-, apoE3-, and apoE4-targeted replacement mice across young, middle, and old ages with both sexes. We found that age had the greatest impact on brain transcriptomes highlighted by an immune module led by Trem2 and Tyrobp, whereas APOE4 was associated with upregulation of multiple Serpina3 genes. Importantly, these networks and gene expression changes were mostly conserved in human brains. Finally, we observed a significant interaction between age, APOE genotype, and sex on unfolded protein response pathway. In the periphery, APOE2 drove distinct blood metabolome profile highlighted by the upregulation of lipid metabolites. Our work identifies unique and interactive molecular pathways underlying AD risk factors providing valuable resources for discovery and validation research in model systems and humans.