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 在密集的研究中，目前仍没有治疗阿尔茨海默病的有效方法。已经有相当大的兴趣 在探索使用诱导多能干细胞(IPSCs)作为研究AD的新工具方面，正如这项技术所能做到的 获取给定AD患者的精确遗传背景。此外，现在有可能产生大量的 这种患者特定的、人类IPSC来源的神经元的数量随需而定。这是一个强大的工具，可以 体外研究AD的发病机制，并利用IPSC开发和测试新的候选疗法 筛选化验。然而，困扰IPSC领域的一个问题是，IPSC的不成熟、胎儿般的本质 所产生的神经元与AD患者的年龄相关特征不匹配。此外，任何年龄- AD患者原代细胞中存在的相关细胞标记物似乎在 重新编程回到多能性。为了解决这些限制，我们最近报告了以下战略 通过操纵已知的通路，人工触发IPSC来源神经元中年龄相关标志物的表达 导致过早衰老。此外，我们还为使用这种诱导衰老策略提供了概念验证 在帕金森氏病的IPSC模型中。这些“诱导衰老”的策略包括异位表达 孕激素，核层蛋白LMNA的突变形式，以及端粒在端粒前后的缩短 神经分化。其他实验室报告的其他候选策略包括击倒RanBP17 基因，参与核/胞质运输和表观遗传细胞异染色质全球丢失的因素 触发成纤维细胞类早衰特征的变化。当前研究的目标是测试当前和 开发可能特别适用于AD模型的新的诱导衰老策略。首先，我们致力于比较 几种电流诱导AD-IPSC来源的皮质神经元老化的策略，以并排评估其能力 以触发年龄相关标记物的表达和AD相关的生化和退行性变化。要对 AD特有的效应，我们将使用最近建立的携带APP(SWE)突变的等基因AD-IPSC系 和早老素1(PSEN1(M146V))。第二，我们将识别和验证新的候选诱导衰老策略 在AD中触发退化表型尤其相关，但在对照IPSC来源的神经元中不相关。 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引发疾病的能力 散发性AD患者IPSC来源的皮质神经元的表型。散发性阿尔茨海默病患者 代表了最常见的疾病形式，并且特别难使用常规的 IPSC技术。 这项拟议的研究将探讨现有的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晚发型障碍，并可能提供 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.