Investigating the Role of p21-Highly Expressing Senescent Cells in Alzheimer's Dementia

项目总结/摘要 阿尔茨海默氏痴呆症（AD）是发病率和死亡率的主要原因，其不完全理解， 缺乏有效治疗。近年来，衰老细胞（SnCs）的积累与AD有关 发病机制和靶向去除这些细胞可能提供新的治疗途径。细胞衰老是一种 细胞命运由稳定的增殖停滞、凋亡抗性和促炎因子的产生来定义。 分泌蛋白虽然衰老编程可以有助于适当的发展和再生 在这些过程中，其失调越来越多地与疾病负担和病理学（包括AD）相关。虽然SnC 调节和清除是一个有前途的治疗靶点，越来越清楚的是，这些细胞是高度 它们的特性和功能是不同的。我们最近开发了一种小鼠模型来表征 高度表达细胞周期阻断蛋白p21的独特SnC群体（p21 high细胞）， 研究表明，这些细胞在与年龄相关的身体功能障碍和代谢疾病中起着因果作用。 此外，其他文献已经涉及泛-SnC的清除，其包括p21高亚群， AD的认知改善。然而，目前尚不清楚p21 high细胞是否对AD有明显的作用，或者它们是否对AD有明显的作用。 靶向去除可进一步抵消AD病理。因此，本建议旨在调查具体的 p21高SnCs对AD的贡献。初步实验表明，p21 high细胞在 小鼠AD模型的大脑具有淀粉样蛋白- β斑块。然而，这些细胞何时开始 积累与潜在的疾病过程和什么样的细胞类型正在经历衰老。 因此，在目标1中，我们将定义与β淀粉样蛋白斑块相关的p21高细胞积累的精确时间轴 沉积（1A），并通过用转基因细胞跟踪这些细胞来确定这些细胞代表什么类型（1B）。 荧光报告系统和免疫组织化学。为了了解这些p21 high SnCs是否在 在AD中，在目标2中，我们提出通过诱导性自杀基因选择性地消除这些细胞，以确定是否 靶向去除这些细胞可以预防（2A）或减轻（2B）AD相关的淀粉样蛋白- β斑块 形成和受损的表现对认知测定。我们还将进行单核RNA测序， (2C)在有或没有p21 high细胞消除的脑中评估AD相关的神经炎性改变， 通路，并探索与p21 high细胞相关的潜在疾病机制。这些目标将有助于 明确了p21 highSnCs在AD中的作用，为新的靶向疾病调节治疗奠定了基础。 此外，这些结果将进一步暗示p21 high细胞在年龄相关疾病中的作用，并拓宽该领域的研究。 SnC异质性的评价。这项工作是康州大学健康部量身定制的职业发展计划的一部分， 整合了老化生物学、计算分析、科学交流、导师制、临床 实践，更多的是为了推进我作为一个未来的医生科学家的职业生涯，研究衰老的驱动因素。

PROJECT SUMMARY/ABSTRACT Alzheimer’s Dementia (AD) is a leading cause of morbidity and mortality that is incompletely understood and lacking effective treatment. Accumulation of senescent cells (SnCs) has recently been implicated in AD pathogenesis and targeted removal of these cells may offer new therapeutic avenues. Cellular senescence is a cell fate defined by stable proliferative arrest, apoptotic resistance, and production of a pro-inflammatory secretome. Though senescence programming can contribute to proper development and regenerative processes, its dysregulation is increasingly linked with disease burden and pathology, including AD. While SnC modulation and clearance is a promising therapeutic target, it is increasingly clear that these cells are highly heterogeneous in their characteristics and function. We recently developed a mouse model to characterize a unique population of SnCs that highly express the cell cycle blockade protein p21 (p21high cells) and demonstrated that these cells play a causal role in age related physical dysfunction and metabolic disease. Furthermore, other literature has implicated clearance of pan-SnCs, which include p21high subpopulations, with cognitive improvements in AD. However, it is unknown if p21high cells make distinct contributions to AD or if their targeted removal can further counteract AD pathology. Therefore, this proposal aims to investigate the specific contributions of p21high SnCs to AD. Preliminary experiments have demonstrated that p21high cells accumulate in the brain of mouse AD models featuring amyloid- β plaque. However, it is unknown when these cells begin to accumulate in relation to the underlying disease process and what cell types are undergoing senescence. Therefore, in Aim 1, we will define the precise timeline of p21high cell accumulation in relation to amyloid- β plaque deposition (1A) and determine what cell types these represent (1B) by tracking these cells with a transgenic fluorescence reporter system and immunohistochemistry. To understand if these p21high SnCs play a causal role in AD, in Aim 2 we propose to selectively eliminate these cells via an inducible suicide gene to determine if targeted removal of these cells can either prevent (2A) or alleviate (2B) AD associated amyloid- β plaque formation and impaired performance on cognitive assays. We will also conduct single nuclei RNA sequencing (2C) on brains with or without p21high cell elimination to assess for changes in AD associated neuro-inflammatory pathways and explore underlying disease mechanisms associated with p21high cells. These aims will help to define the role of p21high SnCs in AD and may serve as a basis for new targeted disease modulating therapy. Furthermore, these results will further implicate p21high cells in age related disease and broaden the field’s appreciation of SnC heterogeneity. This work is part of a tailored career development plan at UConn Health that integrates training in aging biology, computational analysis, scientific communication, mentorship, clinical practice, and more to advance my career as a future physician-scientist that studies the drivers of aging.