Age Impaired ER Homeostasis in Wake-Active Neurons: BiP/Nox2 Crosstalk

描述（由申请人提供）：正常的衰老导致睡眠和觉醒的持续恶化。这两种行为状态的损伤在许多年龄依赖性神经退行性过程中变得更加明显。失眠干扰了数百万美国老年人的认知功能和生活质量。拟议的研究是两个实验室之间的合作努力，以合并每个实验室已经确定的与年龄相关的神经损伤途径。Naidoo博士最近证明，长时间的清醒会激活大脑中未折叠的蛋白质反应。年轻小鼠通过增加BiP和减弱蛋白质翻译来维持蛋白质稳态。相比之下，老年动物的BiP反应不足，表现为ER稳态失调，GADD 153/CHOP增加。她的实验室将探索BiP在年龄相关的ER稳态反应下降中发挥的作用，以使用全球范围内BiP水平改变的小鼠模型和选择唤醒神经元组（目的1）。Veasey博士的实验室已经确定神经元NADPH氧化酶是氧化损伤模型中蛋白质损伤的主要贡献者。这些NADPH氧化酶阳性神经元（去甲肾上腺素能和多巴胺能）比非NADPH氧化酶唤醒神经元更早地发展出与年龄相关的ER稳态受损。她的小组已经确定了增加的内质网（ER）损伤与GADD 153/CHOP激活，核糖体解聚和蛋白质聚集在NADPH氧化酶阳性唤醒神经元。选择具有不同年龄相关损伤的唤醒活跃神经元组提供了一种有价值的工具，可以识别衰老损害唤醒功能的机制。我们假设，在整个生命周期中，儿茶酚胺能神经元中NADPH氧化酶的反复激活破坏了这些神经元中的ER稳态，足以导致不可逆错误折叠蛋白的进行性积累（目的2）。这些研究旨在确定为什么特定的觉醒神经元群体更容易受到与年龄相关的损伤，并将与蛋白质稳态老化有关的两种致病机制联系起来，以解释神经元功能对衰老下降的不同易感性。觉醒障碍可能会导致新的治疗方法，以增强健康老年人和神经退行性疾病患者的日间功能。这项研究旨在研究衰老损害清醒的机制。我们推测，在唤醒神经元氧化酶逐步破坏内质网的伴侣系统。因此，蛋白质稳态受到损害，有毒蛋白质聚集体积累。

DESCRIPTION (provided by applicant): Normal aging results in a relentless deterioration of both sleep and wakefulness. Impairments in both behavioral states become more pronounced in many age-dependent neurodegenerative processes. Impaired wakefulness interferes with cognitive function and quality of life for millions of older Americans. The proposed studies are a collaborative effort between two labs to merge pathways of age-related neural injury that each lab has identified. Dr. Naidoo has recently demonstrated that prolonged wakefulness activates the unfolded protein response in the brain. Young mice maintain protein homeostasis, in part, by increasing BiP and attenuating protein translation. In contrast, aged animals mount an insufficient BiP response and manifest ER dyshomeostasis with increased GADD153/CHOP. Her lab will explore the role BiP plays in age-related declines in ER homeostatic response to prolonged wakefulness using murine models with altered BiP levels globally and in select wake neuronal groups (Aim 1). Dr. Veasey's laboratory has identified neuronal NADPH oxidase as a major contributor to protein damage in a model of oxidative injury. These NADPH oxidase-positive neurons (noradrenergic and dopaminergic) develop age-related impaired ER homeostasis earlier than in non-NADPH oxidase wake neurons. Her group has identified increased endoplasmic reticulum (ER) injury with GADD153/CHOP activation, ribosomal disaggregation and protein aggregation in the NADPH oxidase-positive wake neurons. Having select groups of wake-active neurons with differential age-related injury presents a valuable tool with which to identify mechanisms by which aging impairs wake function. We hypothesize that repeated NADPH oxidase activation in catecholaminergic neurons across the lifetime disrupts ER homeostasis in these neurons sufficiently to result in a progressive accumulation of irreversibly misfolded proteins (Aim 2). The studies are designed to determine why select populations of wake neurons are more susceptible to age-related injury and will link two pathogenic mechanisms implicated in the aging of protein homeostasis to explain differential susceptibility to aging decline in neuronal function. Wake impairments may lead to novel therapeutic approaches to enhance daytime functioning in healthy elderly and those with neurodegenerative processes. The proposed studies examine mechanisms by which aging impairs wakefulness. We hypothesize that an oxidase enzyme in wake neurons progressively disrupts the chaperoning system in the endoplasmic reticulum. Consequently protein homeostasis is compromised and toxic protein aggregates accumulate.