Neuronal senescence and inflammation in Alzheimer's disease

项目摘要 年龄是阿尔茨海默病（AD）的单一最强预测因素。绝大多数的AD病例 偶尔在70岁或以上，除了高龄之外没有已知的病因。到 了解AD根源的细胞和分子变化，研究需要实验方法来区分- 从病理性衰老中恢复健康。到目前为止，选择体外研究老年人神经元，细胞类型 被AD破坏的，一直缺乏。该提案将使用诱导神经元（iN），这是一种生成 通过直接转分化从成纤维细胞中分化出神经元，以研究神经元老化中的细胞过程， AD.与诱导多能干细胞（iPSC）衍生的神经元不同， 阶段并在生理上恢复活力，iN保留了其来源成纤维细胞的年龄相关特征。 iN中的基因表达、表观遗传标记和细胞代谢与供体的年龄相对应。使用 在系统中，该建议将评估与年龄相关的两个因素之间的相互作用， AD脑：细胞衰老和炎症。初步数据表明，来自AD患者的iN是 比iN更可能显示衰老和衰老相关基因上调的蛋白质标记物 健康老年对照组（CTL）。在目标1中，将来自AD和CTL系的衰老细胞和非衰老细胞进行体外培养。 通过RNA-Seq和ATAC-Seq检测。这些分析将确定非衰老性细胞中预先存在的差异。 AD神经元与CTL的区别，以及细胞衰老的特定成分， 这是神经元所特有的，神经元是一种细胞类型，其中衰老的存在仍然存在争议。在其他组织中， 衰老细胞释放炎性因子（统称为衰老相关分泌表型， 型或SASP），破坏局部环境，导致与年龄相关的组织功能障碍。在目标2中， 将评估来自AD和CTL iN的分泌因子激活人星形胶质细胞和小胶质细胞的能力。 这些实验将生成SASP的神经元成分列表，并确定哪些是贡献者 AD引起的慢性炎症最后，目标3将检查细胞过程假设， 在衰老的上游先前的工作和初步数据表明，AD和CTL iN在其细胞内的表达不同， 代谢和细胞内核苷酸库。比较AD和CTL iN的核苷酸含量， 小分子将被用来操纵核苷酸合成的成分，或挽救和测试 从而影响衰老。这些研究将揭示核苷酸代谢的内在差异是否是遗传性的。 消化导致细胞衰老速率增加并促进炎症反应。整体而言， 这些研究将为衰老和炎症如何在老年人中相互作用提供新的见解。 神经元环境是允许AD的。

Project Summary Age is the single strongest predictive factor for Alzheimer's disease (AD). The vast majority of AD cases arise sporadically in the seventh decade of life or beyond, with no known etiology aside from advanced age. To understand cellular and molecular changes at the root of AD, studies need experimental methods that discrim- inate healthy from pathological aging. Until now, options for in vitro study of aged human neurons, the cell type devastated by AD, have been lacking. This proposal will use induced neurons (iNs), a method that generates neurons from fibroblasts by direct transdifferentiation, to study the cellular processes in neuronal aging and AD. Unlike induced pluripotent stem cell (iPSC)-derived neurons, which pass through a stem cell intermediate phase and become physiologically rejuvenated, iNs retain age-related features of their source fibroblasts. Gene expression, epigenetic marks, and cell metabolism in iNs correspond to the age of the donor. Using the iN system, this proposal will evaluate the interaction between two age-correlated factors associated with the AD brain: cellular senescence and inflammation. Preliminary data demonstrate that iNs from AD patients are more likely to show protein markers of senescence and upregulation of senescence-associated genes than iNs from healthy aged controls (CTL). In Aim 1, senescent and non-senescent cells from AD and CTL Iines will be examined by RNA-Seq and ATAC-Seq. These analyses will identify pre-existing differences in non-senescent AD neurons that differentiate them from CTL as well as specific components of cellular senescence that are unique to neurons, a cell type in which the existence of senescence remains controversial. In other tissues, senescent cells release inflammatory factors (collectively termed the senescence associated secretory pheno- type or SASP) that disrupt the local environment, contributing to age-related tissue dysfunction. In Aim 2, the ability of secreted factors from AD and CTL iNs to activate human astrocytes and microglia will be assessed. These experiments will generate a list of neuronal components of the SASP and identify which are contributors to the chronic inflammation that arises with AD. Finally, Aim 3 will examine cellular processes hypothesized to be upstream of senescence. Prior work and preliminary data show that AD and CTL iNs differ in their cellular metabolism and intracellular nucleotide pools. The nucleotide content of AD and CTL iNs will be compared, and small molecules will be used to manipulate components of nucleotide synthesis or salvage and test the resulting impact on senescence. These studies will reveal whether inherent differences in nucleotide metab- olism lead to increased rates of cellular senescence and contribute to the inflammatory response. As a whole, these studies will provide novel insights into how senescence and inflammation interact within the aged neuronal environment that is permissive to AD.