Uncovering the Role of the MS4A Gene Family in Alzheimer's Disease

项目总结 阿尔茨海默病(AD)是一种严重的神经退行性疾病，其特征是无情的记忆丧失和 执行功能缺陷，没有有效的治疗方法。从全基因组关联中积累证据 研究表明，大脑的先天免疫系统在阿尔茨海默病的病因中起着核心作用。作为中央 神经系统的常驻免疫细胞小胶质细胞因此成为治疗靶点的有吸引力的细胞。 这样的药物靶点可能位于MS4A基因座内，这是一个与预防AD相关的区域，在晚年- 小胶质细胞活性的生物标志物sTREM2水平升高。该区域包含多个基因 在跨膜的4结构域亚家族A(MS4A)基因簇中，它们在结构上共同编码 相关跨膜蛋白主要由免疫细胞表达，其确切功能尚不清楚 明白了。我们的工作提名了该基因座内的一个候选因果变体rs636317，它会扰乱锚定 染色质重塑蛋白CTCF的结合位点并与MS4A4A表达增加相关 和髓系细胞中的MS4A6A。这一建议旨在直接测试假设，通过调制MS4A4A和 MS4A6A通过差异CTCF结合表达，变异体rs636317在上下文中改变小胶质细胞功能 疾病的威胁。在目标1中，我将使用CRISPR编辑的人在体外确定MS4A基因的功能影响 诱导多能干细胞(IPSC)来源的小胶质细胞(IMGL)。已知MS4A蛋白之间的相互作用 和其他免疫受体，如TREM2和CLEC7A，I将进行与以下相关的靶向功能检测 MS4A4A/MS4A6A基因敲除系和等基因系两种IPSC模型中iMGL的免疫信号 候选因果变异的保护性或危险等位基因纯合。在《目标2》中，我将用一部小说 小鼠脑内直接注射人小胶质前体细胞的异种移植模型 利用5xFAD嵌合体在体内和疾病背景下评估这些基因对细胞功能的影响 老鼠。我推测敲除人类小胶质细胞中的MS4A4A和MS4A6A可促进保护性小胶质细胞 反应，改善斑块抑制和随后的认知能力下降。阐明这一点的功能 基因家族及其在阿尔茨海默病进展中所起的特定作用有可能极大地影响公众健康。这个 这里概述的拟议研究和严格的培训计划将使我具备成功的 未来在神经退行性疾病方面的职业生涯领导一个独立的研究团队。

PROJECT SUMMARY Alzheimer’s disease (AD) is a grave neurodegenerative disorder characterized by unrelenting memory loss and deficits in executive function with no effective treatment. Accumulating evidence from genome wide association studies (GWAS) posit that the brain’s innate immune system plays a central role in AD etiology. As the central nervous system’s resident immune cells, microglia have thus emerged as attractive cells to target therapeutically. Such drug targets may lie within the MS4A locus, a region associated with protection from AD, later age-at- onset, and increased levels of sTREM2, a biomarker of microglial activity. This region contains multiple genes within the membrane-spanning 4-domain subfamily A (MS4A) gene cluster, which together encode structurally related transmembrane proteins largely expressed by immune cells whose exact functions are not yet understood. Our work nominated a candidate causal variant within this locus, rs636317, which disrupts an anchor binding site for the chromatin remodeling protein CTCF and is associated with increased expression of MS4A4A and MS4A6A in myeloid cells. This proposal aims to directly test the hypothesis that by modulating MS4A4A and MS4A6A expression via differential CTCF binding, variant rs636317 alters microglial cell function in the context of disease. In AIM 1, I will determine the functional impact of MS4A genes in vitro using CRISPR-edited human induced pluripotent stem cell (iPSC)-derived microglia (iMGL). Given known interactions between MS4A proteins and other immune receptors such as TREM2 and CLEC7A, I will perform targeted functional assays related to immune signaling in iMGLs from two iPSC models: MS4A4A/MS4A6A knockout lines and isogenic lines homozygous for the protective or risk alleles of the candidate causal variant. In AIM 2, I will employ a novel xenotransplantation model involving direct injection of human microglia precursor cells into the mouse brain to evaluate the effect of these genes on cell function in vivo and in the context of disease using 5xFAD chimeric mice. I hypothesize that knocking out MS4A4A and MS4A6A in human microglia promotes protective microglial responses, ameliorating plaque containment and subsequent cognitive decline. Elucidating the function of this gene family and the specific role it plays in AD progression has the potential to greatly impact public health. The proposed research and rigorous training plan outlined here will equip me with the skills needed for a successful future career in neurodegeneration leading an independent research team.