Dissecting the origin, regulation and function of microglial subsets in Alzheimer's disease

剖析阿尔茨海默病中小胶质细胞亚群的起源、调控和功能

• 批准号: 10660028
• 负责人: Qingyun Li
• 金额: $ 55.03万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2028-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10660028
• 关键词: Adult; Affect; Aging; Alzheimer' s Disease; Alzheimer' s disease model; Alzheimer' s disease pathology; Alzheimer' s disease patient; Alzheimer' s disease related dementia; Alzheimer' s disease risk; American; Amyloidosis; Apolipoprotein E; Bioinformatics; Brain; Cells; Deposition; Development; Diphtheria Toxin; Disease; Disease Progression; Disease associated microglia; Drug resistance; Elements; Enhancers; Epigenetic Process; Event; Gene Expression; Gene Mutation; Genes; Genetic; Genetic Transcription; Goals; Heterogeneity; Human; Human Genetics; Immune; Immunity; In Vitro; Intervention; Knock-out; Knowledge; Late Onset Alzheimer Disease; Life; Link; Maps; Memory; Microglia; Molecular; Mus; Mutation; Names; Neurodegenerative Disorders; Pathologic; Phenotype; Regulation; Research; Risk Factors; Role; Senile Plaques; Signal Transduction; TREM2 gene; Testing; Training; Transcriptional Regulation; Transplant-Related Disorder; Transplantation; amyloid pathology; cohort; disorder control; epigenetic memory; epigenetic profiling; genetic signature; genomic locus; glial activation; human old age (65+); in vivo; insight; mouse model; mutant; neuroprotection; new therapeutic target; novel; postnatal; response; single-cell RNA sequencing; theories; transcription factor; transcriptomics; white matter

PROJECT SUMMARY Recent advances in human genetics have unequivocally demonstrated mutations in microglia-specific genes, such as TREM2 R47H, to be some of the strongest risk factors for late-onset Alzheimer’s disease (AD). These breakthroughs point to microglia as a potential driver for AD pathology and thus a promising target for novel therapeutics. Remarkably, single-cell RNA sequencing studies have also uncovered a unique microglial subset, named disease-associated microglia (DAM), which are found to surround amyloid plaques in mouse models of AD. Compared to homeostatic microglia, DAM upregulate a cohort of signature genes, including AD risk genes TREM2 and APOE, which are also elevated in microglial subsets from human AD patients. Despite the apparent significance of DAM in AD, critical knowledge gaps exist regarding the cellular and molecular mechanisms that generate DAM as well as the functional contribution of DAM to different stages of AD pathology. The overall- objectives of this proposal are to determine the cellular origin, transcriptional regulation and subset-specific func- tion of DAM in AD. As microglial gene loci can be primed at the enhancers, microglial activation may lead to depositions of certain long-lasting epigenetic marks, which facilitate more rapid changes of gene expression upon a second hit later in life. Therefore, in theory, developmental activations, as we have observed for prolifer- ative region-associated microglia (PAM) in the normal developing white matter, may confer naïve homeostatic microglia such memory at the epigenetic level to allow their faster conversion to DAM in response to disease signals. Consistently, PAM and DAM share the same transcriptomic signature, which is presumably in turn reg- ulated by conserved transcription factors. In addition, analyses based on microglial depletion and global mutants of Trem2 and Apoe (partially controlling the DAM phenotype) have provided important hints for a possible neu- roprotective role of DAM by compacting amyloid plaques and limiting its spread. However, given the heteroge- neity of microglia and technical limitations (e.g. DAM resistant to drug depletion), the function of DAM during AD progression is still controversial. In this proposal, we will test the central hypothesis that conserved transcriptional and epigenetic mechanisms regulate DAM, which are ontogenically related to PAM and serve as the major neuroprotective microglial subset in AD amyloid pathology. Aim 1 will delineate the cellular origin of DAM in AD through genetic fate mapping and epigenetic profiling. Aim 2 will determine the transcriptional regulation of DAM in AD by transplantation of genetically modified primary microglial cells. Aim 3 will define the function of DAM in AD via microglia subset-specific manipulations. Upon completion of the proposed research, we expect to have elucidated the cellular origin, genetic and epigenetic mechanisms as well as in vivo function of the disease- associated microglia subset in AD. These results will provide mechanistic insights into selective subpopulations of microglia that may control AD progression, ultimately paving a new avenue for the development of precise microglia-based interventions to treat AD.

项目摘要 人类遗传学的最新进展已经明确证明了小胶质细胞特异性基因的突变， 例如TREM2 R47 H，是晚发性阿尔茨海默病（AD）的一些最强的风险因素。这些 这些突破指出小胶质细胞是AD病理学的潜在驱动因素，因此是治疗AD的新靶点。 治疗学值得注意的是，单细胞RNA测序研究还发现了一个独特的小胶质细胞亚群， 命名为疾病相关的小胶质细胞（DAM），在小鼠模型中发现其围绕淀粉样蛋白斑块。 ad.与稳态小胶质细胞相比，DAM上调了一组签名基因，包括AD风险基因 TREM2和APOE，其在来自人类AD患者的小胶质细胞亚群中也升高。尽管表面 DAM在AD中的重要性，关于细胞和分子机制存在关键的知识空白， 产生DAM以及DAM对AD病理学不同阶段的功能贡献。总的来说- 该建议的目的是确定细胞起源、转录调节和亚群特异性功能， AD中的DAM。由于小胶质细胞基因位点可以在增强子处引发，因此小胶质细胞活化可能导致 某些持久的表观遗传标记的沉积，这有助于基因表达的更快变化 第二次被击中后的生活。因此，在理论上，发育激活，正如我们所观察到的增殖- 在正常发育的白色物质中的活动区相关小胶质细胞（PAM）可能提供幼稚的稳态 小胶质细胞这种记忆在表观遗传水平，使他们更快地转换为DAM，以应对疾病 信号.一致的是，PAM和DAM共享相同的转录组学特征，这可能反过来是reg- 由保守的转录因子调控。此外，基于小胶质细胞耗竭和全局突变体的分析 Trem2和Apoe（部分控制DAM表型）的突变为可能的neu- DAM通过压缩淀粉样蛋白斑块并限制其扩散而起保护作用。但是，考虑到异质性- 小胶质细胞的特性和技术限制（例如，DAM对药物耗竭具有抗性），DAM在AD期间的功能 进展仍有争议。在这个建议中，我们将测试中心假设，保守的转录 和表观遗传机制调节DAM，它们与PAM在个体发生学上相关，并作为DAM的主要调控机制。 AD淀粉样蛋白病理学中的神经保护性小胶质细胞亚群。目的1阐明AD中DAM的细胞来源 通过基因命运绘图和表观遗传分析。目的2是确定DAM的转录调控 通过移植遗传修饰的原代小胶质细胞治疗AD。目标3将定义DAM的功能， 通过小胶质细胞亚群特异性操作的AD。待建议的研究完成后，我们预计 阐明了该疾病的细胞起源、遗传和表观遗传机制以及体内功能- 相关的小胶质细胞亚群。这些结果将为选择性亚群提供机制性见解 小胶质细胞可以控制AD的进展，最终为精确的 基于小胶质细胞的干预治疗AD。