Regulatory RNAs as mediators and biomarkers in Alzheimer's Disease

描述（由申请人提供）：我们和其他人的高通量努力提供了强有力的证据，与早期的理解形成鲜明对比，大部分哺乳动物基因组被转录为非编码RNA。我们现在试图了解非编码RNA调控网络是否与阿尔茨海默病（AD）中的2-淀粉样蛋白假说有关。本申请集中于非编码RNA网络，该网络似乎调节AD病理生理学中的关键酶和主要AD药物靶点的<$-分泌酶-1（BACE 1）的表达。我们最近报道了一种BACE 1非编码反义转录物（BACE 1-AS）协调并有效地调节BACE 1 mRNA和蛋白的表达。重要的是，BACE 1-AS浓度在人类AD患者以及淀粉样前体蛋白转基因小鼠（AD动物模型）中显著升高。BACE 1-AS在细胞核中富集，但在暴露于淀粉样蛋白1-42（A 1-42）或其他细胞应激物时，这种非编码转录物易位到细胞质中，导致BACE 1 mRNA稳定性增加，以及BACE 1 mRNA上microRNA结合位点的“掩蔽”;这些似乎是协同机制，导致在“恶性循环”中产生额外的A 1-42。这种推定的前馈途径与BACE 1-AS从核库中的释放有关，可能是AD相关病理的驱动方面。考虑到这些发现，本研究应用程序集中在三个目标。我们的第一个目标是获得一个详细的机制的了解，在体外调节作用，BACE 1-AS对BACE 1表达以及BACE 1-AS对AD相关的病理学的潜在影响。其次，我们将试图验证BACE 1-AS对BACE 1表达的体外调节作用也存在于小鼠脑中。在此，我们将开发BACE 1-AS转基因小鼠，以确定这种非编码RNA的过表达是否足以引起或加速AD样病理。第三，我们将讨论BACE 1相关的转录本，特别是BACE 1-AS，是否可以作为AD研究的生物标志物。为了补充我们对AD和对照脑样本的研究，我们将在大量外周血单核细胞样本中研究外周BACE 1相关生物标志物是否可用作生物标志物。总的来说，这些实验有望对BACE 1表达的控制机制产生重要的见解。此外，我们认为，非编码调控RNA，特别是BACE 1-AS，必须被视为候选人的早期生物标志物签名在AD。公共卫生相关性：阿尔茨海默病（Alzheimer's disease，AD）是一种以进行性认知功能损害和短期记忆丧失为特征的与年龄相关的神经退行性疾病。虽然淀粉样蛋白途径与AD之间的联系以及导致AD的事件的优先性仍存在争议，但A2 1-42沉积到老年斑中是AD神经病理学的已证实特征。BACE 1是A2 1-42生物合成所必需的一种半位点淀粉样前体蛋白（APP）裂解酶。因此，BACE 1是AD中热门的药物靶标。了解BACE 1的调控机制可能会揭示AD发病机制的重要见解，并导致新的治疗方法和AD生物标志物的开发。

DESCRIPTION (provided by applicant): High-throughput efforts by us and others have provided strong evidence that, in sharp contrast to earlier understanding, much of the mammalian genome is transcribed into noncoding RNA. We now seek to understand if noncoding RNA regulatory networks may relate to the 2-amyloid hypothesis in Alzheimer's disease (AD). This application focuses on a noncoding RNA network that appears to regulate the expression of ¿-secretase-1 (BACE1), a critical enzyme in AD pathophysiology and a prime AD drug target. We have recently reported that a BACE1 noncoding antisense transcript (BACE1-AS) concordantly and potently regulates BACE1 mRNA and protein expression. Important, BACE1-AS concentrations were markedly elevated in human AD patients as well as in amyloid precursor protein transgenic mice, an AD animal model. BACE1-AS is enriched in the cell nucleus but upon exposure to amyloid-¿ 1-42 (A¿ 1-42), or other cellular stressors, this noncoding transcript translocates into the cytoplasm resulting in increased BACE1 mRNA stability, as well as "masking" of a microRNA binding site on BACE1 mRNA; these appear to be synergistic mechanisms leading to generation of additional A¿ 1-42 in a "vicious cycle". This putative feed-forward pathway, linked to the release of BACE1-AS from a nuclear reservoir, may be driving aspects of AD related pathologies. Considering these findings, the present research application focuses on three aims. Our first aim is to gain a detailed mechanistic understanding of the in vitro regulatory effect that BACE1-AS exerts on BACE1 expression as well as the potential impact of BACE1-AS on AD related pathologies. Second, we will seek to verify that the in vitro regulatory effects of BACE1-AS on BACE1 expression are also present in vivo in mouse brain. Here we will develop BACE1-AS transgenic mice to determine if the overexpression of this noncoding RNA is sufficient to cause or accelerate AD- like pathology. Third, we will address the issue as to whether BACE1-related transcripts, notably BACE1-AS, may be useful as biomarkers for studies on AD. To complement our studies on AD and control brain samples, we shall investigate, in a large number of peripheral blood mononuclear cell samples, whether peripheral BACE1-related biomarkers might be useful as biomarkers. Overall, these experiments promise to yield significant insights into mechanisms by which BACE1 expression is controlled. Furthermore we argue that noncoding regulatory RNAs, notably BACE1-AS, must be viewed as candidates for an early biomarker signature in AD. PUBLIC HEALTH RELEVANCE: Alzheimer's disease (AD) is a devastating age-related neurodegenerative disorder characterized by progressive impairment of cognition and short- term memory loss. Although controversy still exists in the link between amyloid pathway and AD and in the precedence of events leading to AD, deposition of A2 1-42 into senile plaques is a proven feature of AD neuropathology. BACE1 is a ¿-site amyloid precursor protein (APP) cleaving enzyme essential for A2 1-42 biosynthesis. BACE1 is therefore a hotly pursued drug target in AD. Understanding the mechanisms by which BACE1 is regulated may reveal important insights into the pathogenesis of AD, and lead to the development of novel therapeutics and AD biomarkers.