Regional, Synpatic, Cellular Modulation of Abeta Metabolism

描述(申请人提供)：阿尔茨海默病(AD)是导致痴呆症的最常见原因。有令人信服的数据表明，淀粉样β蛋白(Abeta)在疾病发病机制的启动中起着关键的早期作用。有毒形式的Abeta在大脑中的逐渐积聚似乎最终会导致下游事件，最终导致痴呆。由于可溶性Abeta多肽的浓度与其聚集的概率直接相关，因此确定大脑中正常调节Abeta水平的因素可能会为启动AD病理级联反应的因素提供关键的见解。这一PPG方案的研究人员发现，突触活动与脑细胞外空间中Abeta多肽的释放是动态耦合的。我们的实验室利用AD的小鼠模型来发现一些细胞机制，这些机制将突触传递和清醒行为小鼠Abeta水平的动态变化联系起来，并在人类研究中得到证实。Abeta受睡眠-觉醒周期的动态调节，这一调节似乎对决定以后生命中Abeta的沉积很重要。睡眠-觉醒周期对Abeta的调节可能与突触活动有关，因为脑间质液(ISF)水平与突触前和突触后的突触活动直接相关。一个可能参与这种偶联的分子是LRP1，因为APP内吞作用是Abeta生成的主要组成部分，而LRP1影响APP内吞和Abeta生成。我们的假设是，突触活动影响大脑中Abeta的产生和清除，随着时间的推移，这种活动会影响Abeta是否、在哪里以及何时在大脑中聚集成有毒物种。此外，我们假设突触活性介导的Abeta的产生和释放1)受到睡眠/觉醒周期和调节该周期的分子的影响；2)部分通过ERK信号在突触后刺激NMDA受体发生；3)通过与APP的相互作用受到低密度脂蛋白受体相关蛋白-1(LRP1)的影响。我们将结合独特的技术，包括体内蛋白质微透析，13C标记的氨基酸脉冲追逐标记结合质谱仪，以及焦点病毒介导的基因传递，与评估系统水平网络功能、突触和分子信号以及细胞生物学的方法相结合。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) is the most common cause of dementia. There is compelling data that the amyloid- beta (Abeta) peptide plays a key early role in initiating disease pathogenesis. The progressive buildup of toxic forms of Abeta in the brain appears to ultimately lead to downstream events culminating in dementia. Since the concentration of soluble Abeta peptide is directly related to the probability that it will aggregate, determining what normally regulates Abeta levels in the brain will likely provide critical insights ino factors that initiate the AD pathological cascade. The investigators on this PPG proposal have found that synaptic activity is dynamically coupled with the release of the Abeta peptide in the extracellular space of the brain. Our labs have utilized mouse models of AD to discover some of the cellular mechanisms that link synaptic transmission and dynamic changes in Abeta levels in awake, behaving mice with confirmation in human studies. Abeta is dynamically regulated by the sleep-wake cycle and this regulation appears important in determining Abeta deposition later in life. The regulation of Abeta by the sleep-wake cycle may be tied to synaptic activity as brain interstitial fluid (ISF) levels of Abeta are directly coupled with synaptic activity both pre- and post-synapticall. A molecule likely involved in this coupling is LRP1, since APP endocytosis is required for a large component of Abeta generation and LRP1 influences APP endocytosis and Abeta generation. Our hypothesis is that synaptic activity influences both Abeta production and clearance in the brain and that over time this activity influences whether, where, and when Abeta aggregates into toxic species in the brain. In addition, we hypothesize that synaptic activity-mediated Abeta generation and release 1) is influenced by the sleep/wake cycle and molecules that regulate that cycle; 2) occurs in part via post-synaptic stimulation of NMDA receptors via ERK signaling; and 3) is influenced by the LDL-receptor related protein-1 (LRP1) via its interactions with APP. We will combine unique techniques including in vivo protein microdialysis, 13C-labeled amino acid pulse chase labeling combined with mass spectrometry, and focal viral-mediated gene delivery with approaches that assess systems level network function, synaptic and molecular signaling, and cell biology.