Neuroprotective signaling and transcriptional pathways in microglia associated with Alzheimer's disease

与阿尔茨海默病相关的小胶质细胞的神经保护信号传导和转录途径

基本信息

批准号：
10552538
负责人：
ALISON M GOATE
金额：
$ 119.92万
依托单位：
ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-02-01 至 2026-11-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10552538
关键词：
Actins Address Aging Alleles Alzheimer&apos s Disease Alzheimer&apos s disease model Alzheimer&apos s disease risk Alzheimer&apos s disease therapeutic Apoptotic Biochemical Brain Catalytic Domain Cell Nucleus Cell physiology Cells Chemotaxis Chronic Complex Cytoplasm Cytosol Data Development Disease EZH2 gene Ectoderm Embryo Embryo Loss Enhancers Environment Epigenetic Process Etiology Exhibits Gene Expression Gene Silencing Genes Genetic Genetic Epistasis Genetic Transcription Genetic study Goals Hematopoietic stem cells Histone H3 Histones Human Human Genetics Immune Impairment In Vitro Inflammatory Knockout Mice Link Lysine Macrophage Maps Mediating Microglia Missense Mutation Mus Myelogenous Myeloid Cells Nerve Degeneration Nuclear Onset of illness Pathway interactions Phagocytosis Phenocopy Phenotype Play Polycomb Polymers Process Proliferating Public Health Role Signal Induction Signal Pathway Signal Transduction Signaling Protein Stimulus TREM2 gene Testing Therapeutic Variant Xenograft procedure causal variant derepression disorder risk exome sequencing functional genomics genome editing genome wide association study genomic data in vivo induced pluripotent stem cell loss of function loss of function mutation monocyte mouse genetics mouse model mutant neuroinflammation neuroprotection novel pharmacologic polymerization prevent receptor response risk variant therapeutic target tissue stress whole genome

项目摘要

Functional genomics studies have identified an enrichment for Alzheimer’s disease (AD) risk variants in active enhancers of human myeloid cells. These data, along with myeloid-specific expression of several AD risk genes, strongly implicate these cells in the etiology of AD. Partial loss-of-function mutations in Triggering Receptor Expressed on Myeloid cells 2 (TREM2), linked to increased risk for AD, point to a protective role for TREM2 against neurodegeneration. Microglia are known to play numerous beneficial functions in the brain, including clearance of dying cells as well as cellular debris and orchestrate complex responses to tissue stress or damage. However, chronic activation of microglia can lead to toxic neuroinflammation and impairment of homeostatic functions. A better understanding of the mechanisms underlying the neuroprotective functions of microglia is critical to identifying therapeutic targets to prevent or delay AD onset. Using fine mapping approaches, we have identified likely causal genes within many AD GWAS loci. In one locus, the gene encoding embryonic ectoderm development (EED) is a strong candidate causal gene and a putative target of a myeloid cell enhancer containing an AD-associated functional variant. EED is an essential, non-catalytic component of the polycomb repressive complex 2 (PRC2), which functions to maintain the repressive histone mark H3K27me3. Modulation of H3K27me3 is critical for epigenetic remodeling following inflammatory stimuli and has been implicated in microglial clearance of apoptotic cells. Cytoplasmic PRC2 (cPRC2), also exhibits direct signaling activity, controlling receptor-driven activation of Erk as well as actin polymerization in immune cells, cellular processes implicated by our AD genetics studies. Furthermore, our preliminary data show that microglial Eed-/- on the 5XFAD background phenocopies TREM2-/-. Based on these genetic and biochemical observations we hypothesize that EED and PRC2 operate as a master regulator of the TREM2 signaling pathway and that factors that control PRC2 expression levels and activity define the TREM2 driven neuroprotective microglial state. To test this hypothesis, we propose 4 aims to examine the impact of Eed/PRC2 on both human and mouse microglial function and Trem2 signaling in vitro and in vivo. We will determine the role of EED/PRC2 loss of function on microglial function and TREM2 signaling using both mouse and human microglia in vitro (aim 1) and in vivo in 5XFAD mice (aim 2). In aim 3 we will examine the impact of cytoplasmic PRC2 on microglial function and Trem2 signaling in vitro and in vivo. In aim 4 we will use human genetic data to test for enrichment of AD risk alleles within the Trem2 signaling pathway genes and in the Eed regulatory network and determine the impact of select alleles on microglial function and Trem2 signaling. Finally, we will test for epistasis by examining the impact of Eed+/- on Trem2 haploinsufficiency in 5XFAD mice in vivo and in hiPSC-derived microglia in vitro.

功能基因组学研究已经确定了活跃的阿尔茨海默氏病（AD）风险变异的富集人髓样细胞的增强子。这些数据，以及几个AD风险基因的粒细胞特异性表达，强烈暗示这些细胞在AD的病因中。触发受体的部分功能丧失突变在髓样细胞2（trem2）上表达，与AD的风险增加有关，指向TREM2的受保护作用反对神经变性。众所周知，小胶质细胞在大脑中发挥了许多有益的功能，包括垂死细胞以及细胞碎屑的清除，并协调对组织应力或损伤的复杂反应。但是，小胶质细胞的慢性激活会导致有毒神经炎症和稳态损害功能。更好地了解小胶质细胞神经保护功能的机制是确定预防或延迟AD发作的治疗靶标至关重要。使用精细的映射方法，我们有确定了许多AD GWAS基因座中可能的因果基因。在一个基因座中，编码胚胎外胚层的基因开发（EED）是一个强大的候选因果基因，也是含有髓样细胞增强子的推定靶标与广告相关的功能变体。 EED是Polycomb反射性的必不可少的非催化成分复合物2（PRC2），该功能可维持反射性组蛋白标记H3K27me3。调制 H3K27me3对于炎症刺激后的表观遗传重塑至关重要，并且与凋亡细胞的小胶质清除。细胞质PRC2（CPRC2）也表现出直接的信号活性，控制受体驱动的ERK的激活以及免疫细胞中的肌动蛋白聚合，细胞过程由我们的广告遗传学研究实施。此外，我们的初步数据表明，在 5xFAD背景表trem2 - / - 。基于这些遗传和生化观察，我们假设EED和PRC2运算符是TREM2信号通路的主要调节剂，而这些因素控制PRC2表达水平和活性定义了TREM2驱动神经保护小胶质细胞状态。到检验该假设，我们提出4个旨在检查EED/PRC2对人和小鼠小胶质细胞的影响功能和TREM2信号在体外和体内。我们将确定EED/PRC2功能丧失在在体外使用小鼠和人类小胶质细胞（AIM 1）和体内的小胶质细胞功能和TREM2信号传导 5xfad小鼠（AIM 2）。在AIM 3中，我们将检查细胞质PRC2对小胶质细胞功能和TREM2的影响体外和体内信号传导。在AIM 4中，我们将使用人类遗传数据来测试AD风险等位基因的富集在Trem2信号通路基因和EED调节网络中，并确定选择的影响小胶质函数和TREM2信号传导上的等位基因。最后，我们将通过检查 EED +/-在体内和HIPSC衍生的小胶质细胞体外的5xFAD小鼠中的trem2单倍不足。