Chou Ching-Chieh, Vest Ryan, Prado Miguel A, Wilson-Grady Joshua, Paulo Joao A, Shibuya Yohei, Moran-Losada Patricia, Lee Ting-Ting, Luo Jian, Gygi Steven P, Kelly Jeffery W, Finley Daniel, Wernig Marius, Wyss-Coray Tony, Frydman Judith
Department of Biology, Stanford University, Stanford, California, USA.
Department of Chemical Engineering, Stanford University, Stanford, California, USA.
Res Sq. 2024 May 30:rs.3.rs-4407236. doi: 10.21203/rs.3.rs-4407236/v1.
Aging is a prominent risk factor for Alzheimer's disease (AD), but the cellular mechanisms underlying neuronal phenotypes remain elusive. Both accumulation of amyloid plaques and neurofibrillary tangles in the brain and age-linked organelle deficits are proposed as causes of AD phenotypes but the relationship between these events is unclear. Here, we address this question using a transdifferentiated neuron (tNeuron) model directly from human dermal fibroblasts. Patient-derived tNeurons retain aging hallmarks and exhibit AD-linked deficits. Quantitative tNeuron proteomic analyses identify aging and AD-linked deficits in proteostasis and organelle homeostasis, particularly affecting endosome-lysosomal components. The proteostasis and lysosomal homeostasis deficits in aged tNeurons are exacerbated in sporadic and familial AD tNeurons, promoting constitutive lysosomal damage and defects in ESCRT-mediated repair. We find deficits in neuronal lysosomal homeostasis lead to inflammatory cytokine secretion, cell death and spontaneous development of Aß and phospho-Tau deposits. These proteotoxic inclusions co-localize with lysosomes and damage markers and resemble inclusions in brain tissue from AD patients and APP-transgenic mice. Supporting the centrality of lysosomal deficits driving AD phenotypes, lysosome-function enhancing compounds reduce AD-associated cytokine secretion and Aβ deposits. We conclude that proteostasis and organelle deficits are upstream initiating factors leading to neuronal aging and AD phenotypes.
衰老 是阿尔茨海默病（AD）的一个主要风险因素，但神经元表型背后的细胞机制仍不清楚。大脑中淀粉样斑块和神经原纤维缠结的积累以及与年龄相关的细胞器缺陷都被认为是AD表型的原因，但这些事件之间的关系尚不清楚。在这里，我们使用直接从人真皮成纤维细胞转分化而来的神经元（tNeuron）模型来解决这个问题。患者来源的tNeurons保留了衰老特征，并表现出与AD相关的缺陷。定量tNeuron蛋白质组学分析确定了蛋白质稳态和细胞器稳态中与衰老和AD相关的缺陷，尤其影响内体-溶酶体成分。在散发性和家族性AD的tNeurons中，衰老tNeurons的蛋白质稳态和溶酶体稳态缺陷加剧，促进了组成型溶酶体损伤和ESCRT介导的修复缺陷。我们发现神经元溶酶体稳态缺陷会导致炎性细胞因子分泌、细胞死亡以及Aβ和磷酸化Tau沉积物的自发形成。这些蛋白毒性包涵体与溶酶体和损伤标记物共定位，类似于AD患者脑组织和APP转基因小鼠中的包涵体。支持溶酶体缺陷驱动AD表型的核心地位，增强溶酶体功能的化合物可减少AD相关的细胞因子分泌和Aβ沉积物。我们得出结论，蛋白质稳态和细胞器缺陷是导致神经元衰老和AD表型的上游起始因素。
