Programming age in iPS models of Alzheimer's disease

项目摘要 阿尔茨海默病（AD）是人类最常见的神经退行性疾病。尽管几十年来 尽管进行了大量的研究，但目前仍然没有有效的治疗AD的方法。有相当大的兴趣 在探索使用诱导多能干细胞（iPSC）作为一种新的工具来研究AD，因为该技术可以 捕捉特定AD患者的精确遗传背景。此外，现在可以产生大量的 根据需要，可以提供大量这样的患者特异性的人iPSC衍生的神经元。这是一个强大的工具， 在体外研究AD疾病机制，并使用基于iPSC的新候选疗法开发和测试 筛选测定。然而，困扰iPSC领域的一个问题是iPSC的不成熟、胎儿般的性质。 这导致神经元与AD患者的年龄相关特征不匹配。此外，任何年龄- 存在于来自AD患者的原代细胞中的相关细胞标记物似乎在AD患者的细胞分化后恢复活力。 重新编程回到多能性。为了解决这些限制，我们最近报告了一些战略， 通过操纵已知的通路，人工触发iPSC衍生神经元中与年龄相关的标志物表达， 导致过早衰老。此外，我们还提供了使用这种诱导老化策略的概念验证 在帕金森病的iPSC模型中。这些"诱导衰老"的策略包括异位表达 早老蛋白，核纤层蛋白LMNA的突变形式，以及端粒在 神经分化其他实验室报告的其他候选策略包括敲除RanBP 17 基因，一种参与核/胞质转运和异染色质整体丢失的因子，一种表观遗传细胞 在成纤维细胞中引发过早衰老样特征的变化。本研究的目的是测试当前和 开发新的诱导衰老策略，可能特别适合AD模型。首先，我们要比较 在AD-iPSC衍生的皮质神经元中的几种电流诱导的老化策略，以评估它们的能力 以触发年龄相关的标志物表达和AD相关的生化和退行性变化。建模 AD特异性效应，我们将使用最近建立的携带APP突变的同基因AD-iPSC系（Swe） 和早老素1（PSEN1（M146V））。其次，我们将确定和验证新的候选人诱导衰老的策略， 在触发AD中的退行性表型方面特别相关，但在对照iPSC衍生的神经元中不相关。 第三，我们将使用目标1和目标2中最有希望的策略来确定它们触发疾病的能力 表型在源自散发性AD患者的iPSC衍生的皮质神经元中的表达。散发性AD患者 代表了疾病的最常见形式，并且特别难以使用常规方法建模。 iPSC技术。 这项拟议的研究将探讨目前或新的诱导衰老策略是否有助于 改进的AD的iPSC模型。类似的方法可能适用于许多其他迟发性疾病， 对神经元老化机制的基本见解。

Project Summary Alzheimer’s disease (AD) is the most common neurodegenerative disorder in humans. Despite several decades of intense research there are currently still no effective treatments for AD. There has been considerable interest in exploring the use of induced pluripotent stem cells (iPSCs) as a novel tool to study AD, as the technology can capture the precise genetic background of a given AD patient. Furthermore, it is now possible to generate large numbers of such patient-specific, human iPSC-derived neurons on demand. This represents a powerful tool to study AD disease mechanisms in vitro, and to develop and test novel candidate therapies using iPSC-based screening assays. However, a problem that has plagued the iPSC field is the immature, fetal-like nature of the resulting neurons that does not match the age-related characteristics of AD patients. Furthermore, any age- related cellular markers that are present in primary cells from AD patients appear to be rejuvenated after reprogramming back to pluripotency. To address those limitations, we have recently reported on strategies to artificially trigger age-related marker expression in iPSC-derived neurons by manipulating pathways known to cause premature aging. Furthermore, we have provided proof-of-concept for using such induced aging strategies in iPSC models of Parkinson’s disease. Those “induced aging” strategies include the ectopic expression of progerin, a mutant form of the nuclear lamina protein LMNA, and the shortening of telomeres prior to and during neural differentiation. Additional candidate strategies reported by other labs include knockdown of the RanBP17 gene, a factor involved in nuclear/cytoplasmic transport and global loss of heterochromatin, an epigenetic cellular change that triggers premature aging-like feature in fibroblast. The goal of the current study is to test current and to develop novel induced aging strategies that may be particularly suitable to model AD. First, we aim to compare several current induced aging strategies in AD-iPSC-derived cortical neurons to assess, side-by-side, their ability to trigger age-related marker expression and AD-related biochemical and degenerative changes. To model the AD-specific effects, we will use isogenic AD-iPSC lines, recently established, carrying mutations in APP(Swe) and presenilin 1 (PSEN1(M146V). Second, we will identify and validate novel candidate induced aging strategies of particular relevance in triggering degenerative phenotypes in AD- but not in control iPSC-derived neurons. Third, we will use the most promising strategies from Aim 1 and Aim 2 to determine their ability to trigger disease phenotypes in iPSC-derived cortical neurons derived from patients with sporadic AD. Sporadic AD patients represent the most common form of the disease and have been particularly difficult to model using conventional iPSC technology. The proposed study will address whether current or novel induced aging strategies can contribute to improved iPSC models of AD. Similar approaches may apply to many other late-onset disorders and could offer fundamental insights into the mechanism of neuronal aging.