Alterations in neuronal metabolic pathways contribute to human cognitive aging and are exacerbated in Alzheimer's disease

项目摘要 为了找到改变年龄相关疾病进程的疗法， 正常和病理性衰老过程之间的联系。这方面的需要没有比在 寻求有效治疗阿尔茨海默病（AD）的方法。尽管经过几十年的研究，AD仍然是一个 使人衰弱的、进行性的、最终致命的痴呆，几乎没有和无效的疾病改善治疗 选项.绝大多数病例（~95%）是散发性的，除了高龄之外没有已知的原因。作为 随着65岁以上人口的增长，AD的负担注定会同步增长。要避免这种命运， 重新思考为什么现有的努力是无效的。 虽然AD是一种老年人大脑疾病，但许多AD研究未能将衰老与疾病分开。我们有 开发了一个系统，让我们在体外模拟人类年龄的各个方面：诱导神经元（iNs）。一旦成熟， 大脑的神经元再也不会复制它们的基因组或分裂。因此，有丝分裂后神经元下调 细胞周期介导的代谢途径，用于合成DNA结构单元、脱氧核糖核苷酸 （dNT），并变得依赖于核糖核苷酸（rNT）的补救。我问这些重要的 稳态过程在人的寿命期间或在AD中维持。多种实验方法， iN来源于13名散发性AD（sAD）患者对13名认知正常、年龄匹配的个体（CN）， 结果显示，NT库存在显著差异，相对于年轻健康人，氯化萘中的rNT显著增加。 iNs.这种影响在AD iNs中甚至进一步加剧。我在这里问，rNT的急剧增加是否会导致 增加核和线粒体DNA中的核糖取代，从而促进增加的DNA损伤， 老年和AD的生物能量功能障碍。此外，我观察到关键细胞周期的显著差异表达， 以及代谢基因，如CDK 1和RRM 1，我已经在蛋白质水平上证实了这一点。我们的建议，对于 第一次，结合了长期注意到的染色体不稳定性和存在的病理观察， 细胞周期标志物转化为一个可测试的模型系统，为AD的发展提供了机制基础。 零星AD。 除了这项提案旨在实现的关键科学进步外，我还将为实现这一目标贡献新的强大力量。 衰老和AD领域的新工具和数据集。我把我们最近开发的修复序列 技术来量化核糖取代在老年人和AD iNs。我将进一步映射表观遗传漂移超过人类 神经元的寿命，并量化神经元产生新的甲基的能力， 转录调控。

PROJECT SUMMARY To find therapies for altering the course of age-related diseases, experimental methods that discriminate between normal and pathological aging processes are needed. Nowhere is this need more urgent than in the quest for effective treatments for Alzheimer’s disease (AD). Despite decades of research, AD remains a debilitating, progressive, and ultimately fatal dementia with few and ineffective disease-modifying treatment options. The vast majority of cases (~95%) are sporadic, with no known cause aside from advanced age. As the population over age 65 grows, the burden of AD is destined to grow in lockstep. Avoiding this fate requires rethinking why existing efforts have been ineffective. Although AD is a disease of aged human brains, many AD studies fail to parse aging from disease. We have developed a system that lets us model aspects of human age in vitro: induced neurons (iNs). Once matured, neurons of the brain never again replicate their genome or divide. As such, post-mitotic neurons downregulate cell-cycle mediated metabolic pathways used for the synthesis of DNA building blocks, deoxyribonucleotides (dNTs) and become reliant on the salvage of ribonucleotides (rNTs). I asked if these fundamentally important homeostatic processes are maintained over the human lifespan or in AD. Multiple experimental approaches on iNs derived from 13 sporadic AD (sAD) patients against 13 cognitively normal, age-match individuals (CN), revealed dramatic differences in NT pools, with a significant increase in rNTs in CNs relative to young healthy iNs. This effect was even further exacerbated in AD iNs. I ask here if the dramatic increases in rNTs result in increased ribo-substitution in nuclear and mitochondrial DNA, thus promoting increased DNA damage and bioenergetic dysfunction in age and AD. Further, I observed significant differential expression of key cell cycle and metabolic genes such as CDK1 and RRM1, which I have confirmed at the protein level. Our proposal, for the first time, incorporates long noted pathological observations of chromosomal instability and presence of cell-cycle markers in AD into a testable model system that provides a mechanistic basis for the development of sporadic AD. In addition to the critical scientific advances this proposal aims to achieve, I will also contribute new powerful new tools and datasets to the fields of aging and AD. I have adapted our recently developed repair-seq technology to quantify ribo-substitution in aged and AD iNs. I will further map epigenetic drift over the human lifespan in neurons and quantify the neuronal capacity to generate new methyl groups for non-genetic regulation of transcription.