The physical biology of neurodegeneration in sporadic Amyotrophic Lateral Sclerosis/Frontotemporal dementia

关于散发性肌萎缩侧索硬化症-额颞叶痴呆(SALS/FTD)的临床谱 TDP-43等疾病相关蛋白的聚集和积聚是一种显著的神经病理 然而，我们对为什么会发生这种高度异常的事件知之甚少。尽管多个项目的中断 细胞过程与肌萎缩侧索硬化症有关，仍然存在3个关键的知识空白：1)是什么触发了 散发性疾病中野生型蛋白的聚集？蛋白质聚集足以推动病理吗？2) 是什么导致了从ALS到FTD的细胞特异性脆弱性和不同的临床表现？3)如何 疾病相关的蛋白质稳态改变扰乱了组织微环境中的通讯？ 鉴于95%以上的肌萎缩侧索硬化症是零星发生的，而且散发性疾病的机制仍然存在 未知，我们将超越个体突变，并建立一个新的概念框架来检查 在疾病状态下发生的细胞变化。我们假设，通过关注TDP-43聚集的原因 发生，特别是在散发的ALS中，我们将深入了解其背后的致病机制 疾病的谱系。我们的中心假设是细胞和组织发生了物理变化 启动ALS/FTD的比例。我们认为细胞内生物物理性质的改变(主要是 改变的分子拥挤)，这与组织微环境的机械扰动有关 (僵硬、炎症、水肿导致渗透应激)，通过以下方式导致年龄依赖性细胞功能障碍 改变大分子蛋白质机器的组装、拆卸和运输的动态。我们会 在细胞模型、动物模型和患者组织中测试这一假设，方法是(1)使用新的工具来探测 细胞内生物物理环境；(2)利用新的基因组学技术整合这些发现 应用于小鼠模型研究(I)细胞内拥挤的变化和细胞外的变化 组织微环境可能驱动体内的发病，以及(Ii)这种扰动如何扰乱细胞-细胞 和(3)通过重新检查，将我们的发现与人类疾病联系起来 这些发现是在临床和神经病理学深度策划的ALS/FTD患者队列的背景下得出的。 这些研究将使我们能够解决以下问题：1)为什么蛋白质异常聚集 和聚集发生在散发性疾病中，这在疾病发病机制中可能起到什么作用；2) 这些蛋白质稳态的改变扰乱了组织微环境中的细胞间通讯； 3)是什么导致了ALS/FTD独一无二的细胞类型漏洞？拟议的工作将完成 以下是对神经细胞中分子拥挤的第一次详细调查；b)揭示 细胞内拥挤、蛋白质聚集和神经变性之间存在因果联系，C)建立 细胞内拥挤的影响是否表现出细胞类型的特定特征，包括蛋白质的变化- D)为探索治疗ALS/FTD的治疗策略提供了一个新的框架。

On the sporadic Amyotrophic Lateral Sclerosis-Frontotemporal Dementia (sALS/FTD) clinical spectrum, the aggregation and accumulation of disease-associated proteins such as TDP-43 is a notable neuropathological hallmark, yet we know little about why this highly abnormal event might occur. Although disruptions in multiple cellular processes have been implicated in ALS, 3 critical gaps in knowledge remain: 1) What triggers the aggregation of wildtype proteins in sporadic disease? Is protein aggregation sufficient to drive pathology? 2) What drives the cell-specific vulnerabilities and variable clinical manifestation from ALS to FTD? 3) How do disease-associated alterations in protein homeostasis perturb communication in the tissue microenvironment? Given that more than 95% of ALS arises sporadically, and that the mechanisms of sporadic disease remain unknown, we will look beyond individual mutations, and establish a novel conceptual framework that examines the cellular changes that occur during disease states. We posit that by focusing on why TDP-43 aggregation occurs, especially in sporadic ALS, we will gain insights into pathogenic mechanisms underlying this spectrum of disorders. Our central hypothesis is that there are physical changes at the cell and tissue scale that initiate ALS/FTD. We propose that altered biophysical properties within cells (predominantly altered molecular crowding), which are linked to mechanical perturbations to the tissue microenvironment (stiffening, inflammation, edema causing osmotic stress), lead to age-dependent cellular dysfunction by altering the dynamics of assembly, disassembly and transport of macromolecular protein machines. We will test this hypothesis in cellular models, animal models, and patient tissue by (1) using novel tools to probe the intracellular biophysical environment of cells; (2) integrating these findings using novel genomics technologies applied to mouse models to study (i) how intracellular changes in crowding and extracellular changes in the tissue microenvironment may drive pathogenesis in vivo, and (ii) how such perturbations disrupt cell-cell communication in vulnerable regions of tissue; and (3) relating our findings to human disease by re-examining these findings in the context of a clinically and neuropathologically deeply curated cohort of ALS/FTD patients. These studies will allow us to address the following questions: 1) Why does abnormal protein aggregation and accumulation occur in sporadic disease, and how might this contribute to disease pathogenesis; 2) Do these alterations in protein homeostasis perturb intercellular communication in the tissue microenvironment; and 3) What drives the cell type vulnerability that makes ALS/FTD unique? The proposed work will accomplish the following: A) represent the first detailed survey of molecular crowding in neural cells; B) uncover whether a causal link between intracellular crowding, protein aggregation, and neurodegeneration exists, C) establish whether the impacts of intracellular crowding show cell type specific signatures including changes in protein- protein interactions, and D) provide a new framework to explore therapeutic strategies for treating ALS/FTD.