Epigenetic Signaling in the Aging Hypothalamus

项目总结 在女性中，衰老的特征是循环中的雌激素(E)水平显著下降，这对 影响许多生理系统，包括睡眠-觉醒周期和认知表现。因此， 许多绝经后妇女选择接受E激素替代疗法(HRT)，希望能 逆转或减轻这些消极症状。不幸的是，潜在的神经内分泌机制 与HRT相关的是鲜为人知的，以及这些激素调控对 中枢神经系统不清楚，特别是超重的女性。用恒河猴作为 翻译动物模型，我们之前证明了与年龄相关的扰乱睡眠-觉醒增加 周期，并发现周期受干扰最严重的个体在 空间记忆任务，以及免疫反应受损。我们还展示了认知方面的好处 由于长期给去卵巢的老年女性服用E；然而，重要的是，有益的 在维持高脂、高脂饮食的动物中，E对各种生理功能的影响是不可持续的。 糖西式饮食(WSD)。这项R21探索性研究的目标是检验年龄- 视交叉上核(SCN)内的相关分子变化导致睡眠-觉醒周期中断 而绝经后循环E浓度的显著下降加剧了这些问题， 尤其是当同时接触到WSD时。因此，我们的研究将检查DNA甲基化 SCN内的发展(目标1)，并使用RNA-seq来描述基因表达变化(目标2)，使用 存档的脑组织来自以下两组以前描述过特征的猕猴： 1.卵巢完好的年轻成年雌性(标准饮食) 2.卵巢完好的老年雌性(标准饮食) 3.去卵巢的老年女性(标准饮食) 4.去卵巢的老年女性(标准饮食+HRT治疗~3年) 5.去卵巢的老年女性(接受水务署治疗约3年) 6.去卵巢的老年女性(水疗3年+HRT治疗3年) 使用先前验证的甲基序列方法来提供单碱基分辨DNA甲基化数据，我们 将检查SCN中的差异甲基化CpG(DMC)和区域(DMR)-即已建立的位置 在维持睡眠和同步日常生理活动中起关键作用的生物钟 功能。我们预测，老化，对WSD的维护，以及循环产生的E不足 SCN核心时钟机制内的功能性表观遗传修饰导致扰动 昼夜节律活动-休息模式，反过来又使个人更容易患上阿尔茨海默病。

PROJECT SUMMARY In women, aging is characterized by a marked decrease in circulating estrogen (E) levels, which negatively impacts many physiological systems including sleep-wake cycles and cognitive performance. Consequently, many postmenopausal women chose to undergo E hormone replacement therapy (HRT), with the hope of reversing or alleviating these negative symptoms. Unfortunately, the underlying neuroendocrine mechanisms associated with HRT are poorly understood and the long-term efficacy of these hormonal manipulations on the central nervous system are unclear, especially in women who are overweight. Using the rhesus macaque as a translational animal model, we previously demonstrated an age-associated increase in perturbed sleep-wake cycles, and found that individuals with the most perturbed cycles showed inferior cognitive performance in a spatial memory task, as well as compromised immune responses. We also demonstrated cognitive benefits resulting from long-term administration of E to old ovariectomized females; importantly, however, the beneficial effects of E on various physiological functions were not sustained in animals maintained on a high-fat, high- sugar Western-style diet (WSD). The goal of this R21 exploratory study is to test the hypothesis that age- related molecular changes within the suprachiasmatic nucleus (SCN) contribute to disrupted sleep-wake cycles and that these are exacerbated by the marked postmenopausal attenuation of circulating E concentrations, especially when concomitantly exposed to a WSD. Therefore, our study will examine DNA methylation developments within the SCN (Aim 1), and use RNA-seq to profile gene expression changes (Aim 2), using archived brain tissue from the following pair-groups of previously-characterized rhesus macaques: 1. Young adult ovary-intact females (on a standard diet) 2. Old ovary-intact females (on a standard diet) 3. Old ovariectomized females (on a standard diet) 4. Old ovariectomized females (on a standard diet + treated with HRT for ~3 years) 5. Old ovariectomized females (on a WSD for ~3 years) 6. Old ovariectomized females (on a WSD for ~3 years + treated with HRT for ~3 years) Using a previously-validated MethylSeq approach to provide single-base resolution DNA methylation data, we will examine differential methylation CpG (DMC) and region (DMR) in the SCN – i.e., the well-established site of the master circadian clock that plays a key role in sleep maintenance and synchronizing daily physiological functions. We predict that aging, maintenance on a WSD, and insufficient E in the circulation produce functional epigenetic modifications within the core clock mechanism of the SCN that result in perturbed circadian activity-rest pattern, and in turn predispose individuals to development of Alzheimer’s disease.